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Are deep eutectic solvents benign or toxic?
M. Hayyan; M. A. Hashim; A. Hayyan; M. A. Al-Saadi; I. M. AlNashef; M. E. S. Mirghani; O. K. Saheed
In continuation of investigation for environmentally benign protocol for new solvents termed deep eutectic solvents (DESs), it is herein reported results concerning the toxicity and cytotoxicity of choline chloride (ChCl) based DESs with four hydrogen bond donors including glycerine, ethylene glycol, triethylene glycol and urea. The toxicity was investigated using two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and
Are deep eutectic solvents benign or toxic?
Hayyan, Maan; Hashim, Mohd Ali; Hayyan, Adeeb; Al-Saadi, Mohammed A; AlNashef, Inas M; Mirghani, Mohamed E S; Saheed, Olorunnisola Kola
In continuation of investigation for environmentally benign protocol for new solvents termed deep eutectic solvents (DESs), it is herein reported results concerning the toxicity and cytotoxicity of choline chloride (ChCl) based DESs with four hydrogen bond donors including glycerine, ethylene glycol, triethylene glycol and urea. The toxicity was investigated using two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. The cytotoxicity effect was tested using the Artemia salina leach. It was found that there was no toxic effect for the tested DESs on all of the studied bacteria confirming their benign effects on these bacteria. Nevertheless, it was found that the cytotoxicity of DESs was much higher than their individual components (e.g. glycerine, ChCl) indicating that their toxicological behavior is different. For our best knowledge this is the first time that toxicity and cytotoxicity of DESs were studied. The toxicity and cytotoxicity of DESs varied depending on the structure of components. Careful usage of the terms non-toxicity and biodegradability must be considered. More investigation on this matter is required. PMID:23200570
Prediction of deep eutectic solvents densities at different temperatures
K. Shahbaz; F. S. Mjalli; M. A. Hashim; I. M. Alnashef
Predicting densities of nonconventional solvents like deep eutectic solvents (DESs) as a function of temperature is of considerable importance in the development and design of new processes utilizing these solvents. Because of the nature of bonding existing between the salt and the hydrogen bond donor, conventional methods result in very large deviations. In this study, the density of DESs based
Prebiotic phosphate ester syntheses in a deep eutectic solvent.
Gull, Maheen; Zhou, Manshui; Fernßndez, Facundo M; Pasek, Matthew A
We report a route to synthesize a wide range of organophosphates of biological significance in a deep eutectic solvent (2:1 urea and choline chloride), utilizing various orthophosphate sources. Heating an organic alcohol in the solvent along with a soluble phosphorus source yields phosphorus esters of choline as well as that of the added organic in yields between 15 to 99Ā%. In addition, phosphite analogs of biological phosphates and peptides were also formed by the simple mixing of reagents and heating at 60-70Ā░C in the deep eutectic solvent. The presented dehydration reactions are relevant to prebiotic and green chemistry in alternative solvents. PMID:24368625
Application of deep eutectic solvents in the extraction and separation of target compounds from various samples.
Tang, Baokun; Zhang, Heng; Row, Kyung Ho
Deep eutectic solvents, as a new type of eco-friendly solvent, have attracted increasing attention in chemistry for the extraction and separation of target compounds from various samples. To summarize the application of deep eutectic solvents, this review highlights some of the unique properties of deep eutectic solvents and deep-eutectic-solvent-based materials, as well as their applications in extraction and separation. In this paper, the available data and references in this field are reviewed to summarize the application developments of deep eutectic solvents. Based on the development of deep eutectic solvents, the exploitation of new deep eutectic solvents and deep-eutectic-solvent-based materials are expected to diversify into extraction and separation. PMID:25581398
Prediction of the surface tension of deep eutectic solvents
K. Shahbaz; F. S. Mjalli; M. A. Hashim; I. M. AlNashef
Surface tension is one of the important deep eutectic solvents (DESs) physical properties which provides considerable information related to the molecular influence on the intensity of interactions in the mixture. Due to the absence of DESs surface tension experimental data, prediction methods of this property become of high importance. In this work, two simple methods for the prediction of DESs
Protease activation in glycerol-based deep eutectic solvents
Hua Zhao; Gary A. Baker; Shaletha Holmes
Deep eutectic solvents (DESs) consisting of mixtures of a choline salt (chloride or acetate form) and glycerol are prepared as easily accessible, biodegradable, and inexpensive alternatives to conventional aprotic cation¢anion paired ionic liquids. These DES systems display excellent fluidity coupled with thermal stability to nearly 200░C. In this work, the transesterification activities of cross-linked proteases (subtilisin and ?-chymotrypsin), immobilized on
Glucose-based deep eutectic solvents: Physical properties
A. Hayyan; F. S. Mjalli; I. M. Alnashef; Y. M. Al-Wahaibi; T. Al-Wahaibi; M. A. Hashim
Deep eutectic solvents (DESs) are considered nowadays as green ionic liquid (IL) analogues. Despite their relatively short period of introduction as a special class of ILs, they have been under an increasing emphasis by the scientific community due to their favorable properties. In the present study, a glucose based DES of choline chloride (2-hydroxyethyl-trimethylammonium chloride) with the monosaccharide sugar d-glucose
Scientific Correspondence Are Natural Deep Eutectic Solvents the Missing Link in
Galis, Frietson
Scientific Correspondence Are Natural Deep Eutectic Solvents the Missing Link in Understanding and deep eutectic solvents (DES) have been revisited by chemical engineering, because such solvents can replace conventional organic solvents. Mixing salts and/or organic compounds may cause a considerable
Ionic liquids and deep eutectic solvents in natural products research: mixtures of solids as extraction solvents.
Dai, Yuntao; van Spronsen, Jaap; Witkamp, Geert-Jan; Verpoorte, Robert; Choi, Young Hae
Mixtures of solid chemicals may become liquid under certain conditions. These liquids are characterized by the formation of strong ionic (ionic liquids) or hydrogen bonds (deep eutectic solvents). Due to their extremely low vapor pressure, they are now widely used in polymer chemistry and synthetic organic chemistry, yet little attention has been paid to their use as extraction solvents of natural products. This review summarizes the preparation of ionic liquids and deep eutectic solvents with natural product components and recent progress in their applications to the extraction and analysis of natural products as well as the recovery of extracted compounds from their extracts. Additionally, various factors affecting extraction features of ionic liquids and deep eutectic solvents, as well as potential useful technologies including microwave and ultrasound to increase the extraction efficiency, are discussed. PMID:24188074
Deep eutectic solvent pretreatment and subsequent saccharification of corncob.
Procentese, Alessandra; Johnson, Erin; Orr, Valerie; Garruto Campanile, Anna; Wood, Jeffery A; Marzocchella, Antonio; Rehmann, Lars
Ionic liquid (ILs) pretreatment of lignocellulosic biomass has attracted broad scientific interest, despite high costs, possible toxicity and energy intensive recycling. An alternative group of ionic solvents with similar physicochemical properties are deep eutectic solvents (DESs). Corncob residues were pretreated with three different DES systems: choline chloride and glycerol, choline chloride and imidazole, choline chloride and urea. The pretreated biomass was characterised in terms of lignin content, sugars concentration, enzymatic digestibility and crystallinity index. A reduction of lignin and hemicellulose content resulted in increased crystallinity of the pretreated biomass while the crystallinity of the cellulose fraction could be reduced, depending on DES system and operating conditions. The subsequent enzymatic saccharification was enhanced in terms of rate and extent. A total of 41g fermentable sugars (27g glucose and 14g xylose) could be recovered from 100g corncob, representing 76% (86% and 63%) of the initially available carbohydrates. PMID:26005926
Protease activation in glycerol-based deep eutectic solvents
Zhao, Hua; Baker, Gary A.; Holmes, Shaletha
Deep eutectic solvents (DESs) consisting of mixtures of a choline salt (chloride or acetate form) and glycerol are prepared as easily accessible, biodegradable, and inexpensive alternatives to conventional aprotic cation-anion paired ionic liquids. These DES systems display excellent fluidity coupled with thermal stability to nearly 200 ░C. In this work, the transesterification activities of cross-linked proteases (subtilisin and ?-chymotrypsin), immobilized on chitosan, were individually examined in these novel DESs. In the 1:2 molar ratio mixture of choline chloride/glycerol containing 3% (v/v) water, cross-linked subtilisin exhibited an excellent activity (2.9 ?mo l min?1 g?1) in conjunction with a selectivity of 98% in the transesterification reaction of N-acetyl-L-phenylalanine ethyl ester with 1-propanol. These highly encouraging results advocate more extensive exploration of DESs in protease-mediated biotransformations of additional polar substrates and use of DESs in biocatalysis more generally. PMID:21909232
Prussian blue nanospheres synthesized in deep eutectic solvents
NASA Astrophysics Data System (ADS)
Sheng, Qinglin; Liu, Ruixiao; Zheng, Jianbin
A novel route for controlled synthesis of Prussian blue nanospheres (PB NSs) with different sizes by using deep eutectic solvents (DES) as both solvent and template provider was demonstrated. The size-controlled PB NSs were obtained directly by the coordination of Fe(CN)64- ion with Fe3+ ion in the DES. The probable mechanism of formation of PB NSs was discussed based on the characterization results of UV-visible, X-ray diffraction, X-ray photoelectronic spectrum and transfer electron microscopy. Furthermore, the electrochemical and electrocatalytic properties of the synthesized PB NSs were investigated, and it has demonstrated that the PB NSs exhibited excellent catalytic activity for H2O2 reduction, and then extended this strategy to glucose sensing, by detecting H2O2 formed from the enzymatic reaction of glucose oxidase with its substrate glucose. The linear calibration range for glucose was from 0.9 ?M to 0.12 mM, with a correlation coefficient of 0.998. The limit of detection was 0.3 ?M and the sensitivity was 61.7 A cm-2 M-1. The present study provides a general platform for the controlled synthesis of novel nanomaterials in DES and can be extended to other optical, electronic and magnetic nanocompounds.A novel route for controlled synthesis of Prussian blue nanospheres (PB NSs) with different sizes by using deep eutectic solvents (DES) as both solvent and template provider was demonstrated. The size-controlled PB NSs were obtained directly by the coordination of Fe(CN)64- ion with Fe3+ ion in the DES. The probable mechanism of formation of PB NSs was discussed based on the characterization results of UV-visible, X-ray diffraction, X-ray photoelectronic spectrum and transfer electron microscopy. Furthermore, the electrochemical and electrocatalytic properties of the synthesized PB NSs were investigated, and it has demonstrated that the PB NSs exhibited excellent catalytic activity for H2O2 reduction, and then extended this strategy to glucose sensing, by detecting H2O2 formed from the enzymatic reaction of glucose oxidase with its substrate glucose. The linear calibration range for glucose was from 0.9 ?M to 0.12 mM, with a correlation coefficient of 0.998. The limit of detection was 0.3 ?M and the sensitivity was 61.7 A cm-2 M-1. The present study provides a general platform for the controlled synthesis of novel nanomaterials in DES and can be extended to other optical, electronic and magnetic nanocompounds. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr31830j
Prussian blue nanospheres synthesized in deep eutectic solvents.
Sheng, Qinglin; Liu, Ruixiao; Zheng, Jianbin
A novel route for controlled synthesis of Prussian blue nanospheres (PB NSs) with different sizes by using deep eutectic solvents (DES) as both solvent and template provider was demonstrated. The size-controlled PB NSs were obtained directly by the coordination of Fe(CN)(6)(4-) ion with Fe(3+) ion in the DES. The probable mechanism of formation of PB NSs was discussed based on the characterization results of UV-visible, X-ray diffraction, X-ray photoelectronic spectrum and transfer electron microscopy. Furthermore, the electrochemical and electrocatalytic properties of the synthesized PB NSs were investigated, and it has demonstrated that the PB NSs exhibited excellent catalytic activity for H(2)O(2) reduction, and then extended this strategy to glucose sensing, by detecting H(2)O(2) formed from the enzymatic reaction of glucose oxidase with its substrate glucose. The linear calibration range for glucose was from 0.9 ?M to 0.12 mM, with a correlation coefficient of 0.998. The limit of detection was 0.3 ?M and the sensitivity was 61.7 A cm(-2) M(-1). The present study provides a general platform for the controlled synthesis of novel nanomaterials in DES and can be extended to other optical, electronic and magnetic nanocompounds. PMID:23034657
How polar are choline chloride-based deep eutectic solvents?
Pandey, Ashish; Rai, Rewa; Pal, Mahi; Pandey, Siddharth
Developing and characterizing green solvents with low toxicity and cost is one of the most important issues in chemistry. Deep Eutectic Solvents (DESs), in this regard, have shown tremendous promise. Compared to popular organic solvents, DESs possess negligible VOCs and are non-flammable. Compared to ionic liquids, which share many characteristics but are ionic compounds and not ionic mixtures, DESs are cheaper to make, much less toxic and mostly biodegradable. An estimate of the polarity associated with DESs is essential if they are to be used as green alternatives to common organic solvents in industries and academia. As no one physical parameter can satisfactorily represent solute-solvent interactions within a medium, polarity of DESs is assessed through solvatochromic optical spectroscopic responses of several UV-vis absorbance and molecular fluorescence probes. Information on the local microenvironment (i.e., the cybotactic region) that surrounds several solvatochromic probes [betaine dye, pyrene, pyrene-1-carboxaldehyde, 1-anilino-8-naphthalene sulfonate (ANS), p-toluidinyl-6-naphthalene sulfonate (TNS), 6-propionyl-2-(dimethylaminonaphthalene) (PRODAN), coumarin-153, and Nile Red] for four common and popular DESs formed from choline chloride combined with 1,2-ethanediol, glycerol, urea, and malonic acid, respectively, in 1?:?2 molar ratios termed ethaline, glyceline, reline, and maline is obtained and used to assess the effective polarity afforded by each of these DESs. The four DESs as indicated by these probe responses are found to be fairly dipolar in nature. Absorbance probe betaine dye and fluorescence probes ANS, TNS, PRODAN, coumarin-153, and Nile Red, whose solvatochromic responses are based on photoinduced charge-transfer, imply ethaline and glyceline, DESs formed using alcohol-based H-bond donors, to be relatively more dipolar in nature as compared to reline and maline. The pyrene polarity scale, which is based on polarity-induced changes in vibronic bands, indicates reline, the DES composed of urea as the hydrogen bond donor, to be significantly more dipolar than the other three DESs. Response of pyrene-1-carboxaldehyde, a polarity probe based on inversion of n-?* and ?-?* states, hints at maline to be the most dipolar of the four DESs. The molecular structure of the H-bond donor in a DES clearly controls the dipolarity afforded by the DES. H-bonding and other specific solute-solvent interactions are found to play an important role in solvatochromic probe behavior for the four DESs. The cybotactic region of a probe dissolved in a DES affords information on the polarity of the DES towards solutes of similar nature and functionality. PMID:24305780
Deep eutectic solvents as novel extraction media for phenolic compounds from model oil.
Gu, Tongnian; Zhang, Mingliang; Tan, Ting; Chen, Jia; Li, Zhan; Zhang, Qinghua; Qiu, Hongdeng
Deep eutectic solvents (DES) as a new kind of green solvent were used for the first time to excellently extract phenolic compounds from model oil. It was also proved that DES could be used to extract other polar compounds from non-polar or weakly-polar solvents by liquid-phase microextraction. PMID:25144155
Deep eutectic solvents as novel extraction media for protein partitioning.
Zeng, Qun; Wang, Yuzhi; Huang, Yanhua; Ding, Xueqin; Chen, Jing; Xu, Kaijia
Four kinds of green deep eutectic solvent (DES) were synthesized, including choline chloride (ChCl)-urea, tetramethylammonium chloride (TMACl)-urea, tetrapropylammonium bromide (TPMBr)-urea and ChCl-methylurea. An aqueous two-phase system (ATPS) based ChCl-urea DES was studied for the first time for the extraction of bovine serum albumin (BSA). Single factor experiments proved that the extraction efficiency of BSA was influenced by the mass of the DES, concentration of K2HPO4 solution, separation time and extraction temperature. The optimum conditions were determined through an orthogonal experiment with the four factors described above. The results showed that under the optimum conditions, the average extraction efficiency could reach up to 99.94%, 99.72%, 100.05% and 100.05% (each measured three times). The relative standard deviations (RSD) of extraction efficiencies in precision, repeatability and stability experiments were 0.5533% (n = 5), 0.8306% (n = 5) and 0.9829% (n = 5), respectively. UV-vis and FT-IR spectra confirmed that there were no chemical interactions between BSA and the DES in the extraction process, and the CD spectra proved that the conformation of BSA did not change after extraction. The conductivity, DLS and TEM were combined to investigate the microstructure of the top phase and the possible mechanism for the extraction. The results showed that hydrophobic interactions, hydrogen bonding interactions and the salting-out effect played important roles in the transfer process, and the aggregation and surrounding phenomenon were the main driving forces for the separation. All of these results proved that ionic liquid (IL)-based ATPSs could potentially be substituted with DES-based ATPSs to offer new possibilities in the extraction of proteins. PMID:24699681
Deep eutectic solvents: sustainable media for nanoscale and functional materials.
Wagle, Durgesh V; Zhao, Hua; Baker, Gary A
Deep eutectic solvents (DESs) represent an alternative class of ionic fluids closely resembling room-temperature ionic liquids (RTILs), although, strictly speaking, they are distinguished by the fact that they also contain an organic molecular component (typically, a hydrogen bond donor like a urea, amide, acid, or polyol), frequently as the predominant constituent. Practically speaking, DESs are attractive alternatives to RTILs, sharing most of their remarkable qualities (e.g., tolerance to humidity, negligible vapor pressure, thermostability, wide electrochemical potential windows, tunability) while overcoming several limitations associated with their RTIL cousins. Particularly, DESs are typically, less expensive, more synthetically accessible (typically, from bulk commodity chemicals using solvent/waste-free processes), nontoxic, and biodegradable. In this Account, we provide an overview of DESs as designer solvents to create well-defined nanomaterials including shape-controlled nanoparticles, electrodeposited films, metal-organic frameworks, colloidal assemblies, hierarchically porous carbons, and DNA/RNA architectures. These breakthroughs illustrate how DESs can fulfill multiple roles in directing chemistry at the nanoscale: acting as supramolecular template, metal/carbon source, sacrificial agent (e.g., ammonia release from urea), and/or redox agent, all in the absence of formal stabilizing ligand (here, solvent and stabilizer are one and the same). The ability to tailor the physicochemical properties of DESs is central to controlling their interfacial behavior. The preorganized "supramolecular" nature of DESs provides a soft template to guide the formation of bimodal porous carbon networks or the evolution of electrodeposits. A number of essential parameters (viscosity, polarity, surface tension, hydrogen bonding), plus coordination with solutes/surfaces, all play significant roles in modulating species reactivity and mass transport properties governing the genesis of nanostructure. Furthermore, DES components may modulate nucleation and growth mechanisms by charge neutralization, modification of reduction potentials (or chemical activities), and passivation of particular crystal faces, dictating growth along preferred crystallographic directions. Broad operational windows for electrochemical reactions coupled with their inherent ionic nature facilitate the electrodeposition of alloys and semiconductors inaccessible to classical means and the use of cosolvents or applied potential control provide under-explored strategies for mediating interfacial interactions leading to control over film characteristics. The biocompatibility of DESs suggests intriguing potential for the construction of biomolecular architectures in these novel media. It has been demonstrated that nucleic acid structures can be manipulated in the ionic, crowded, dehydrating (low water activity) DES environment-including the adoption of duplex helical structures divergent from the canonical B form and parallel G-quadruplex DNA persisting near water's boiling point-challenging the misconception that water is a necessity for maintenance of nucleic acid structure/functionality and suggesting an enticing trajectory toward DNA/RNA-based nanocatalysis within a strictly anhydrous medium. DESs offer tremendous opportunities and open intriguing perspectives for generating sophisticated nanostructures within an anhydrous or low-water medium. We conclude this Account by offering our thoughts on the evolution of the field, pointing to areas of clear and compelling utility which will surely see fruition in the coming years. Finally, we highlight a few hurdles (e.g., need for a universal nomenclature, absence of water-immiscible, oriented-phase, and low-viscosity DESs) which, once navigated, will hasten progress in this area. PMID:24892971
One-Pot Multi-component Synthesis of 1,4-Dihydropyridine Derivatives in Biocompatible Deep Eutectic Solvents
Pednekar, Suhas; Ghadge, Nitin
An efficient protocol for the synthesis of differently substituted 1, 4-dihydropyridines in deep eutectic solvents under solvent-free conditions is reported herewith. Excellent yields of the resultant products have been obtained. Recyclability studies have also been performed for deep eutectic solvents with very little loss in activity up to five recycles.
Prediction of refractive index and density of deep eutectic solvents using atomic contributions
K. Shahbaz; F. S. G. Bagh; F. S. Mjalli; I. M. AlNashef; M. A. Hashim
Deep eutectic solvents (DESs) are considered as potential alternatives for ionic liquids (ILs). The evaluation of DESs as new generation of solvents for various practical application requires enough knowledge about some main physical, chemical, and thermodynamic properties. In this study, due to lack of data for DESs' refractive indices, the refractive indices of twenty four DESs based on ammonium and
Using deep eutectic solvents to electrodeposit CoSm films and nanowires
P. Cojocaru; L. Magagnin; E. Gomez; E. Vallķs
A Deep Eutectic Solvent of 1 chlorine chloride: 2 urea eutectic mixture at 70░C has been tested as useful to electrodeposit both magnetic SmCo films and nanowires. Galvanostatic deposition allows obtaining homogeneous deposits over metallic substrate with variable composition as a function of the current density applied. The deposits obtained at 0.5¢1.5mAcm?2 were uniform and they correspond to a cobalt
A novel green approach for the chemical modification of silica particles based on deep eutectic solvents.
Gu, Tongnian; Zhang, Mingliang; Chen, Jia; Qiu, Hongdeng
Deep eutectic solvents (DESs), as a novel class of green solvents, were successfully applied as eco-friendly and sustainable reaction media for fast surface modification of spherical porous silica, resulting in stationary phases for high-performance liquid chromatography. The new reaction media were advantageous over organic solvents in many aspects, such as the high dispersibility of silica spheres and their non-volatility. PMID:25985926
Densities of ammonium and phosphonium based deep eutectic solvents: Prediction using artificial intelligence and group contribution techniques
K. Shahbaz; S. Baroutian; F. S. Mjalli; M. A. Hashim; I. M. Alnashef
As applications of deep eutectic solvents are growing fast as green alternatives, prediction of physical properties data for such systems becomes a necessity for engineering application designs and new process developments. In this study, densities of three classes of deep eutectic solvents, based on a phosphonium and two ammonium salts, were measured. Two predictive models based on artificial intelligence and
Natural deep eutectic solvents as new potential media for green technology.
Dai, Yuntao; van Spronsen, Jaap; Witkamp, Geert-Jan; Verpoorte, Robert; Choi, Young Hae
Developing new green solvents is one of the key subjects in Green Chemistry. Ionic liquids (ILs) and deep eutectic solvents, thus, have been paid great attention to replace current harsh organic solvents and have been applied to many chemical processing such as extraction and synthesis. However, current ionic liquids and deep eutectic solvents have still limitations to be applied to a real chemical industry due to toxicity against human and environment and high cost of ILs and solid state of most deep eutectic solvents at room temperature. Recently we discovered that many plant abundant primary metabolites changed their state from solid to liquid when they were mixed in proper ratio. This finding made us hypothesize that natural deep eutectic solvents (NADES) play a role as alternative media to water in living organisms and tested a wide range of natural products, which resulted in discovery of over 100 NADES from nature. In order to prove deep eutectic feature the interaction between the molecules was investigated by nuclear magnetic resonance spectroscopy. All the tested NADES show clear hydrogen bonding between components. As next step physical properties of NADES such as water activity, density, viscosity, polarity and thermal properties were measured as well as the effect of water on the physical properties. In the last stage the novel NADES were applied to the solubilization of wide range of biomolecules such as non-water soluble bioactive natural products, gluten, starch, and DNA. In most cases the solubility of the biomolecules evaluated in this study was greatly higher than water. Based on the results the novel NADES may be expected as potential green solvents at room temperature in diverse fields of chemistry. PMID:23427801
Using deep eutectic solvents for the removal of glycerol from palm oil-based biodiesel
K. Shahbaz; Farouq. S. Mjalli; M. A. Hashim; I. M. Al Nashef
One of the essential steps in the manufacture of biodiesel is its purification from the glycerol by-product. The produced biodiesel should have a low glycerol content which is regarded as one of the important needed pointers for passing the international biodiesel standards. Low cost Deep Eutectic Solvents (DES) have been tested for their solvation properties. In this work, DESs were
The electrochemical behaviour of ferrocene in deep eutectic solvents based on quaternary ammonium and phosphonium salts
L. Bahadori; N. S. Abdul Manan; M. H. Chakrabarti; M. A. Hashim; F. S. Mjalli; I. M. Alnashef; M. A. Hussain; C. T. J. Low
The electrochemical behaviour of ferrocene (Fc) is investigated in six different deep eutectic solvents (DESs) formed by means of hydrogen bonding between selected ammonium and phosphonium salts with glycerol and ethylene glycol. Combinations of cyclic voltammetry and chronoamperometry are employed to characterise the DESs. The reductive and oxidative potential limits are reported versus the Fc\\/Fc+ couple. The diffusion coefficient, D,
Assessment of cytotoxicity and toxicity for phosphonium-based deep eutectic solvents
M. Hayyan; M. A. Hashim; M. A. Al-Saadi; A. Hayyan; I. M. AlNashef; M. E. S. Mirghani
In this work, the cytotoxicity and toxicity of phosphonium-based deep eutectic solvents (DESs) with three hydrogen bond donors, namely glycerine, ethylene glycol, and triethylene glycol were investigated. The cytotoxicity effect was tested using brine shrimp (. Artemia salina). The toxicity was investigated using the two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and two Gram negative bacteria Escherichia coli
Natural deep eutectic solvents as a new extraction media for phenolic metabolites in Carthamus tinctorius L.
Dai, Yuntao; Witkamp, Geert-Jan; Verpoorte, Robert; Choi, Young Hae
Developing green solvents with low toxicity and cost is an important issue for the biochemical industry. Synthetic ionic liquids and deep eutectic solvents have received considerable attention due to their negligible volatility at room temperature, high solubilization ability, and tunable selectivity. However, the potential toxicity of the synthetic ionic liquids and the solid state at room temperature of most deep eutectic solvents hamper their application as extraction solvents. In this study, a wide range of recently discovered natural ionic liquids and deep eutectic solvents (NADES) composed of natural compounds were investigated for the extraction of phenolic compounds of diverse polarity. Safflower was selected as a case study because its aromatic pigments cover a wide range of polarities. Many advantageous features of NADES (such as their sustainability, biodegradability combined with acceptable pharmaceutical toxicity profiles, and their high solubilization power of both polar and nonpolar compounds) suggest their potential as green solvents for extraction. Experiments with different NADES and multivariate data analysis demonstrated that the extractability of both polar and less polar metabolites was greater with NADES than conventional solvents. The water content in NADES proved to have the biggest effect on the yield of phenolic compounds. Most major phenolic compounds were recovered from NADES with a yield between 75% and 97%. This study reveals the potential of NADES for applications involving the extraction of bioactive compounds from natural sources. PMID:23710664
Ionic liquids and deep eutectic mixtures: sustainable solvents for extraction processes.
Pena-Pereira, Francisco; Namie?nik, Jacek
In recent years, ionic liquids and deep eutectic mixtures have demonstrated great potential in extraction processes relevant to several scientific and technological activities. This review focuses on the applicability of these sustainable solvents in a variety of extraction techniques, including but not limited to liquid- and solid-phase (micro) extraction, microwave-assisted extraction, ultrasound-assisted extraction and pressurized liquid extraction. Selected applications of ionic liquids and deep eutectic mixtures on analytical method development, removal of environmental pollutants, selective isolation, and recovery of target compounds, purification of fuels, and azeotrope breaking are described and discussed. PMID:24811900
Solubility of sodium salts in ammonium-based deep eutectic solvents
F. S. Ghareh Bagh; F. S. Mjalli; M. A. Hashim; M. K. O. Hadj-Kali; I. M. Alnashef
The solubility of sodium chloride (NaCl), sodium bromide (NaBr), and sodium carbonate (Na2CO3) was measured in nine ammonium-based deep eutectic solvents (DESs). The aim of the study is to assess the potential use of these DESs as solvents and electrolytes for the separation of sodium metal from its salts. The studied DESs were prepared by combining ammonium salts with various
A novel group of quaternary ammonium salts as ionic liquids and deep eutectic solvents
NASA Astrophysics Data System (ADS)
Sparrow, Christopher R.
A growing number of non-toxic and biodegradable deep eutectic solvents (DES) have been discovered in recent years. This group encompasses the solidified crystalline material 3-(2-aminopyrimidin-1-yl)propanoate (3-2AP), a primary ammonium cation that is a construct of a typical DES. Synthesis of 3-(2-aminopyrimidin-1-yl)propanoate by quarternerization of the amine in the aromatic ring creates a novel deep eutectic solvent. An additional alteration to the DES construct is observed with the formation of a zwitterion between the positively charged quartenary amine group and the negatively charged carboxylate counter ion. The molecular arrangement, or construct, of a deep eutectic solvent will determine both its structure and application in industry. This report describes the synthesis and characterization of an 80:20 urea/3-2AP eutectic mixture with a melting point of 50░C, nearly 120░C lower than the melting temperature of 3-2AP (172.5░C). A cytotoxicity profile for 3-2AP exposed to A549 bronchoaveolar carcinoma cells revealed an LD50 of 337.65 mug/ml.
In situ PM-IRRAS of a glassy carbon electrode/deep eutectic solvent interface.
Vieira, Luciana; Schennach, Robert; Gollas, Bernhard
The interface of a 1?:?2 molar choline chloride/ethylene glycol deep eutectic solvent with a glassy carbon electrode has been investigated by polarization modulation reflection-absorption spectroscopy (PM-IRRAS). Temporal spectral changes at open circuit potential show the experiments to be surface sensitive and indicate slow adsorption of electrolyte molecules on the electrode surface. In situ spectroelectrochemical PM-IRRAS measurements reveal characteristic potential-dependent changes of band intensities and wavenumber-shifts in the surface spectra. The potential dependent spectral changes are discussed in terms of adsorption, reduction, desorption and reorientation of choline cations at the interface. Analogies are drawn to the ionic layer structure proposed for the architecture of electrode/ionic liquid interfaces. The results show that in situ PM-IRRAS is generally applicable to glassy carbon electrodes and to electrode interfaces with deep eutectic solvents. PMID:25908481
Deep eutectic solvents (DESs) are viable cosolvents for enzyme-catalyzed epoxide hydrolysis
Diana Lindberg; Mario de la Fuente Revenga; Mikael Widersten
A special group of ionic liquids, deep eutectic solvents (DESs) have been tested as cosolvents in enzyme-catalyzed hydrolysis of a chiral (1,2)-trans-2-methylstyrene oxide. The choline chloride:ethane diol (ET), choline chloride:glycerol (GLY) and choline:chloride:urea (REL) DESs were included in the reaction mixtures with epoxide and the potato epoxide hydrolase StEH1. The effect of the DESs on enzyme function was primarily elevations
Synthesis and Characterization of CuCl Nanoparticles in Deep Eutectic Solvents
In the present work, CuCl nanoparticles were fabricated in deep eutectic solvents (DES) which is a new kind of ionic liquid with special properties. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of polyvinylpyrrolidone (PVP), the molar ratio of ascorbic acid to copper chloride and the mixing method
The kinetics of the Cu 2+\\/Cu + redox couple in deep eutectic solvents
David Lloyd; Tuomas Vainikka; Lasse Murtomõki; Ky÷sti Kontturi; Elisabet Ahlberg
Kinetics of electron transfer of the Cu(I)\\/Cu(II) redox couple at a platinum electrode has been studied with chronoamperometry, cyclic voltammetry and impedance spectroscopy in a deep eutectic solvent consisting of choline chloride and ethylene glycol. At 25░C, the reaction was found to be quasi-reversible with a relatively high rate constant k0 of 9.5▒2ū10?4cms?1, and a charge transfer coefficient ? of
Cyclic voltammetry of metallic acetylacetonate salts in quaternary ammonium and phosphonium based deep eutectic solvents
M. H. Chakrabarti; N. P. Brandon; F. S. Mjalli; L. Bahadori; I. M. Al Nashef; M. A. Hashim; M. A. Hussain; C. T. J. Low; V. Yufit
Seven commercially sourced acetylacetonate salts were investigated in deep eutectic solvents (DESs that were prepared from ethylene glycol and trifluoroacetamide hydrogen bond donors) by cyclic voltammetry, to identify electrolytes suitable for future applications in electrochemical energy storage devices. Although the solubilities are low and on the order of 0.02 molĘL-1 for the most soluble salts, some were found to display
Electrodeposition of Co, Sm and SmCo from a Deep Eutectic Solvent
E. G¾mez; P. Cojocaru; L. Magagnin; E. Valles
The suitability of 1 choline chloride:2 urea mixture, Deep Eutectic Solvent (DES) for the electrodeposition of cobalt, samarium and cobalt¢samarium system has been studied. Its electrochemical window permits deposition analysis to be carried out without interference from parallel reactions. Deposition was studied at 70░C in order to stimulate mass transfer and to lower solution viscosity.Cobalt deposits according to a nucleation
A novel deep eutectic solvent-based ionic liquid used as electrolyte for dye-sensitized solar cells
Huei-Ru Jhong; David Shan-Hill Wong; Chi-Chao Wan; Yung-Yun Wang; Tzu-Chien Wei
We utilize a quaternary ammonium salt-derivative ionic liquid called G.CI which is a eutectic mixture of glycerol and choline iodide as electrolyte for dye-sensitized solar cells. Such eutectic compound belongs to a new series of ionic liquid called deep eutectic solvents (DES), which possess many outstanding features compared to the traditional imidazolium-based ionic liquids including cheap raw materials, simple preparation
Natural deep eutectic solvents providing enhanced stability of natural colorants from safflower (Carthamus tinctorius).
Dai, Yuntao; Verpoorte, Robert; Choi, Young Hae
A certain combination of natural products in the solid state becomes liquid, so called natural deep eutectic solvents (NADES). Recently, they have been considered promising new green solvents for foods, cosmetics and pharmaceuticals due to their unique solvent power which can dissolve many non-water-soluble compounds and their low toxicity. However, in addition to the features as solvents, the stabilisation ability of NADES for compounds is important for their further applications. In the study, the stability analysis demonstrates that natural pigments from safflower are more stable in sugar-based NADES than in water or 40% ethanol solution. Notably, the stabilisation capacity of NADES can be adjusted by reducing water content with increasing viscosity. The strong stabilisation ability is due to the formation of strong hydrogen bonding interactions between solutes and NADES molecules. The stabilising ability of NADES for phenolic compounds shows great promise for their applications in food, cosmetic and pharmaceutical industries. PMID:24767033
Selective N Alkylation of Aromatic Primary Amines Catalyzed by Biocatalyst or Deep Eutectic Solvent
Balvant Singh; Hyacintha Lobo; Ganapati Shankarling
\\u000a AbstractĀĀBiocatalysts or deep eutectic solvents (DES) are effective for selective N-alkylation of various aromatic primary amines. These methods avoided complexity of multiple alkylations giving products in\\u000a good yields. Both DES and lipase can be recycled and re-used at least five times. In addition, these catalysts are biodegradable,\\u000a non-toxic and cost-effective.\\u000a \\u000a \\u000a \\u000a \\u000a Graphical AbstractĀĀ
Thermal unfolding and refolding of lysozyme in deep eutectic solvents and their aqueous dilutions.
Esquembre, Rocio; Sanz, Jesus M; Wall, J Gerard; del Monte, Francisco; Mateo, C Reyes; Ferrer, M Luisa
The stability of hen's egg white lysozyme in different choline chloride-based pseudo-concentrated and neat deep eutectic solvents (DESs) has been studied by means of intrinsic fluorescence and CD spectroscopy. Thermal unfolding experiments carried out in non-diluted urea:choline chloride and glycerol:choline chloride eutectic solvents (UCCl-DES and GCCl-DES, respectively) showed the accumulation at certain temperatures of discrete, partially folded intermediates that displayed a high content of secondary structure and a disrupted tertiary structure. Reversibility of the unfolding process was incomplete in these circumstances, with the urea-based DES showing higher protein structure destabilization upon thermal treatment. On the other hand, aqueous dilution of the eutectic mixtures allowed the recovery of a reversible, two-state denaturation process. Lysozyme activity was also affected in neat and pseudo-concentrated GCCl-DES, with an increasing recovery of activity upon aqueous dilution, and full restoration after DES removal through extensive dialysis. These results suggest that protein interactions at room temperature are reversible and depend on the DES components and on the aqueous content of the original DES dilution. PMID:23722327
Sono-electrodeposition (20 and 850 kHz) of copper in aqueous and deep eutectic solvents
Bruno G. Pollet; Jean-Yves Hihn; Timothy J. Mason
This paper reports the effects of ultrasound at different frequencies and powers upon the electrodeposition of copper(II) chloride in aqueous potassium chloride and in glyceline 200 (a deep eutectic solvent ¢ DES) on Pt electrodes in the potential range for copper deposition and dissolution. It is shown that the deposition of copper in both solvents is greatly affected by ultrasound
Electrical conductivity of ammonium and phosphonium based deep eutectic solvents: Measurements and artificial intelligence-based prediction
F. S. G. Bagh; K. Shahbaz; F. S. Mjalli; I. M. AlNashef; M. A. Hashim
The evaluation of deep eutectic solvents (DESs) as a new generation of solvents for various practical application requires an insight of the main physical, chemical, and thermodynamic properties. In this study, the experimental measurements of the electrical conductivity of two classes of DESs based on ammonium and phosphonium salts at different compositions and temperatures were reported. The results revealed that
Deep eutectic solvents formed between choline chloride and carboxylic acids: versatile alternatives to ionic liquids.
Abbott, Andrew P; Boothby, David; Capper, Glen; Davies, David L; Rasheed, Raymond K
Deep Eutectic Solvents (DES) can be formed between a variety of quaternary ammonium salts and carboxylic acids. The physical properties are significantly affected by the structure of the carboxylic acid but the phase behavior of the mixtures can be simply modeled by taking account of the mole fraction of carboxylic acid in the mixture. The physical properties such as viscosity, conductivity, and surface tension of these DES are similar to ambient temperature ionic liquids and insight into the cause of these properties is gained using hole-theory. It is shown that the conductivity and viscosity of these liquids is controlled by ion mobility and the availability of voids of suitable dimensions, and this is consistent with the fluidity of other ionic liquids and molten salts. The DES are also shown to be good solvents for metal oxides, which could have potential application for metal extraction. PMID:15264850
Tailoring properties of natural deep eutectic solvents with water to facilitate their applications.
Dai, Yuntao; Witkamp, Geert-Jan; Verpoorte, Robert; Choi, Young Hae
Previously it was demonstrated that natural deep eutectic solvents (NADES) are promising green solvents for the extraction of natural products. However, despite their potential, an obvious disadvantage of NADES is the high viscosity. Here we explored the dilution effect on the structures and physicochemical properties of NADES and their improvements of applications using quercetin and carthamin. The results of FT-IR and (1)H NMR experiments demonstrated that there are intensive H-bonding interactions between the two components of NADES and dilution with water caused the interactions weaken gradually and even disappeared completely at around 50% (v/v) water addition. A small amount of water could reduce the viscosity of NADES to the range of water and increase the conductivity by up to 100 times for some NADES. This study provides the basis for modulating NADES in a controllable way for their applications in food processing, enzyme reactions, pharmaceuticals and cosmetics. PMID:25976992
EXAFS study into the speciation of metal salts dissolved in ionic liquids and deep eutectic solvents.
Hartley, Jennifer M; Ip, Chung-Man; Forrest, Gregory C H; Singh, Kuldip; Gurman, Stephen J; Ryder, Karl S; Abbott, Andrew P; Frisch, Gero
The speciation of metals in solution controls their reactivity, and this is extremely pertinent in the area of metal salts dissolved in ionic liquids. In the current study, the speciation of 25 metal salts is investigated in four deep eutectic solvents (DESs) and five imidazolium-based ionic liquids using extended X-ray absorption fine structure. It is shown that in diol-based DESs M(I) ions form [MCl2](-) and [MCl3](2-) complexes, while all M(II) ions form [MCl4](2-) complexes, with the exception of Ni(II), which exhibits a very unusual coordination by glycol molecules. This was also found in the X-ray crystal structure of the compound [Ni(phen)2(eg)]Cl2Ę2eg (eg = ethylene glycol). In a urea-based DES, either pure chloro or chloro-oxo coordination is observed. In [C6mim][Cl] pure chloro complexation is also observed, but coordination numbers are smaller (typically 3), which can be explained by the long alkyl chain of the cation. In [C2mim][SCN] metal ions are entirely coordinated by thiocyanate, either through the N or the S atom, depending on the hardness of the metal ion according to the hard-soft acid-base principle. With weaker coordinating anions, mixed coordination between solvent and solute anions is observed. The effect of hydrate or added water on speciation is insignificant for the diol-based DESs and small in other liquids with intermediate or strong ligands. One of the main findings of this study is that, with respect to metal speciation, there is no fundamental difference between deep eutectic solvents and classic ionic liquids. PMID:24897923
Self-aggregation of sodium dodecyl sulfate within (choline chloride + urea) deep eutectic solvent.
Pal, Mahi; Rai, Rewa; Yadav, Anita; Khanna, Rajesh; Baker, Gary A; Pandey, Siddharth
Deep eutectic solvents (DESs) have shown tremendous promise as green solvents with low toxicity and cost. Understanding molecular aggregation processes within DESs will not only enhance the application potential of these solvents but also help alleviate some of the limitations associated with them. Among DESs, those comprising choline chloride and appropriate hydrogen-bond donors are inexpensive and easy to prepare. On the basis of fluorescence probe, electrical conductivity, and surface tension experiments, we present the first clear lines of evidence for self-aggregation of an anionic surfactant within a DES containing a small fraction of water. Namely, well-defined assemblies of sodium dodecyl sulfate (SDS) apparently form in the archetype DES Reline comprising a 1:2 molar mixture of choline chloride and urea. Significant enhancement in the solubility of organic solvents that are otherwise not miscible in choline chloride-based DESs is achieved within Reline in the presence of SDS. The remarkably improved solubility of cyclohexane within SDS-added Reline is attributed to the presence of spontaneously formed cyclohexane-in-Reline microemulsions by SDS under ambient conditions. Surface tension, dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), density, and dynamic viscosity measurements along with responses from the fluorescence dipolarity and microfluidity probes of pyrene and 1,3-bis(1-pyrenyl)propane are employed to characterize these aggregates. Such water-free oil-in-DES microemulsions are appropriately sized to be considered as a new type of nanoreactor. PMID:25314953
Physicochemical properties of ammonium-based deep eutectic solvents and their electrochemical evaluation using organometallic reference redox systems
L. Bahadori; M. H. Chakrabarti; F. S. Mjalli; I. M. Alnashef; N. S. A. Manan; M. A. Hashim
Seven deep eutectic solvents (DESs) containing ammonium based salts are prepared by means of hydrogen bonding with acid, amine, amide and nitrate based compounds. The major physicochemical properties of the DESs in terms of density, viscosity, electrical conductivity, molar conductivity and pH are investigated prior to ascertaining their electrochemical characteristics by means of cyclic voltammetry and chronoamperometry. Nitrate based DESs
Prediction of glycerol removal from biodiesel using ammonium and phosphunium based deep eutectic solvents using artificial intelligence techniques
K. Shahbaz; S. Baroutian; F. S. Mjalli; M. A. Hashim; I. M. AlNashef
Biodiesel total glycerol content is an important characteristic which must pass the EN 14214 and ASTM D6751 international biodiesel quality standards. In this study, the experimental data of glycerol removal by means of deep eutectic solvents (DESs) was used to design a new modeling approach based on Artificial Neural Networks (ANNs) in order to predict glycerol removal. The DESs were
Prospects of applying ionic liquids and deep eutectic solvents for renewable energy storage by means of redox flow batteries
M. H. Chakrabarti; F. S. Mjalli; I. M. Alnashef; M. A. Hashim; M. A. Hussain; L. Bahadori; C. T. J. Low
Ionic liquids (ILs) and deep eutectic solvents (DESs) have been applied in various fields such as electrolytes for lithium ion batteries, electrodeposition, electropolishing and even in fuel cells. ILs and molten salts have found some applications in redox flow batteries (RFBs) in the past and recently some metal ion based ILs have been proposed and used by Sandia National Laboratories.
Molecular and ionic diffusion in aqueous - deep eutectic solvent mixtures: Probing inter-molecular interactions using PFG NMR
D'Agostino, Carmine; Gladden, Lynn F.; Mantle, Mick D.; Abbott, Andrew P.; Ahmed, Essa I.; Al-Murshedi, Azhar Y. m.; Harris, Robert C.
Pulsed field gradient (PFG) NMR has been used to probe self-diffusion of molecular and ionic species in aqueous mixtures of choline chloride (ChCl) based deep eutectic solvents (DESs), in order to elucidate the effect of water on motion and inter...
Recent progress in G-quadruplex DNA in deep eutectic solvent.
Zhao, Chuanqi; Qu, Xiaogang
Guanine-rich nucleic acids are known to form four-stranded G-quadruplex structures which are attracting increasing attention in diverse areas such as biology, medicinal chemistry, supramolecular chemistry and nanotechnology. To date, the handling media for DNA has largely been limited to an aqueous phase. Since many chemical reactions and devices are required to be performed under strictly anhydrous conditions, even at high temperature, it is meaningful but challenging to conduct G-quadruplex DNA in water-free medium. Recently, deep eutectic solvent (DES), a related material to ionic liquids (ILs) was considered as a new class of anhydrous media for DNA. This review highlights the stability, structure, folding dynamics and thermodynamics of G-quadruplex in DES. Spectroscopic methodologies, like circular dichroism, UV and fluorescence, are mainly employed in these studies. PMID:23628945
Applicability evaluation of Deep Eutectic Solvents-Cellulase system for lignocellulose hydrolysis.
Gunny, Ahmad Anas Nagoor; Arbain, Dachyar; Nashef, Enas Muen; Jamal, Parveen
Deep Eutectic Solvents (DESs) have recently emerged as a new generation of ionic liquids for lignocellulose pretreatment. However, DESs contain salt components which tend to inactivate cellulase in the subsequent saccharification process. To alleviate this problem, it is necessary to evaluate the applicability of the DESs-Cellulase system. This was accomplished in the present study by first studying the stability of cellulase in the presence of selected DESs followed by applicability evaluation based on glucose production, energy consumption and kinetic performance. Results showed that the cellulase was able to retain more than 90% of its original activity in the presence of 10% (v/v) for glycerol based DES (GLY) and ethylene glycol based DES (EG). Furthermore, both DESs system exhibited higher glucose percentage enhancement and lower energy consumption as compared to diluted alkali system. Among the two DESs studied, EG showed comparatively better kinetic performance. PMID:25661309
The electrochemical behaviour of ferrocene in deep eutectic solvents based on quaternary ammonium and phosphonium salts.
Bahadori, Laleh; Manan, Ninie Suhana Abdul; Chakrabarti, Mohammed Harun; Hashim, Mohd Ali; Mjalli, Farouq Sabri; AlNashef, Inas Muen; Hussain, Mohd Azlan; Low, Chee Tong John
The electrochemical behaviour of ferrocene (Fc) is investigated in six different deep eutectic solvents (DESs) formed by means of hydrogen bonding between selected ammonium and phosphonium salts with glycerol and ethylene glycol. Combinations of cyclic voltammetry and chronoamperometry are employed to characterise the DESs. The reductive and oxidative potential limits are reported versus the Fc/Fc(+) couple. The diffusion coefficient, D, of ferrocene in all studied DESs is found to lie between 8.49 ū 10(-10) and 4.22 ū 10(-8) cm(2) s(-1) (these do not change significantly with concentration). The standard rate constant for heterogeneous electron transfer across the electrode/DES interface is determined to be between 1.68 ū 10(-4) and 5.44 ū 10(-4) cm s(-1) using cyclic voltammetry. These results are of the same order of magnitude as those reported for other ionic liquids in the literature. PMID:23247115
Tetrabutylammonium bromide (TBABr)-based deep eutectic solvents (DESs) and their physical properties.
Yusof, Rizana; Abdulmalek, Emilia; Sirat, Kamaliah; Rahman, Mohd Basyaruddin Abdul
Density, viscosity and ionic conductivity data sets of deep eutectic solvents (DESs) formed by tetrabutylammonium bromide (TBABr) paired with ethlyene glycol, 1,3-propanediol, 1,5-pentanediol and glycerol hydrogen bond donors (HBDs) are reported. The properties of DES were measured at temperatures between 303 K and 333 K for HBD percentages of 66.7% to 90%. The effects of HBDs under different temperature and percentages are systematically analyzed. As expected, the measured density and viscosity of the studied DESs decreased with an increase in temperature, while ionic conductivity increases with temperature. In general, DESs made of TBABr and glycerol showed the highest density and viscosity and the lowest ionic conductivity when compared to other DESs. The presence of an extra hydroxyl group on glycerol in a DES affected the properties of the DES. PMID:24932572
Assessment of cytotoxicity and toxicity for phosphonium-based deep eutectic solvents.
Hayyan, Maan; Hashim, Mohd Ali; Al-Saadi, Mohammed A; Hayyan, Adeeb; AlNashef, Inas M; Mirghani, Mohamed E S
In this work, the cytotoxicity and toxicity of phosphonium-based deep eutectic solvents (DESs) with three hydrogen bond donors, namely glycerine, ethylene glycol, and triethylene glycol were investigated. The cytotoxicity effect was tested using brine shrimp (Artemia salina). The toxicity was investigated using the two Gram positive bacteria Bacillus subtilis and Staphylococcus aureus, and two Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa. The cytotoxicity of tested DESs was much higher than that of their individual components, indicating their toxicological behavior was different. It was also found that there was toxic effect on the studied bacteria, indicating their potential application as anti-bacterial agents. To the best of our knowledge, this is the first time the cytotoxicity and toxicity of phosphonium-based DESs were studied. PMID:23820537
Choline chloride-thiourea, a deep eutectic solvent for the production of chitin nanofibers.
Mukesh, Chandrakant; Mondal, Dibyendu; Sharma, Mukesh; Prasad, Kamalesh
Deep eutectic solvents (DESs) consisting of the mixtures of choline halide (chloride/bromide)-urea and choline chloride-thiourea were used as solvents to prepare ?-chitin nanofibers (CNFs). CNFs of diameter 20-30 nm could be obtained using the DESs comprising of the mixture of choline chloride and thiourea (CCT 1:2); however, NFs could not be obtained using the DESs having urea (CCU 1:2) as hydrogen bond donor. The physicochemical properties of thus obtained NFs were compared with those obtained using a couple of imidazolium based ionic liquids namely, 1-butyl-3-methylimidazolium hydrogen sulphate [(Bmim)HSO4] and 1-methylimidazolium hydrogen sulphate [(Hmim)HSO4] as well as choline based bio-ILs namely, choline hydrogen sulphate [(Chol)HSO4] and choline acrylate. The CNFs obtained using the DES as a solvent were used to prepare calcium alginate bio-nanocomposite gel beads having enhanced elasticity in comparison to Ca-alginate beads. The bio-nanocomposite gel beads thus obtained were used to study slow release of 5-fluorouracil, an anticancer drug. PMID:24528755
Solvatochromic probe behavior within choline chloride-based deep eutectic solvents: effect of temperature and water.
Pandey, Ashish; Pandey, Siddharth
Deep eutectic solvents (DESs) have shown potential as promising environmentally friendly alternatives to conventional solvents. Many common and popular DESs are obtained by simply mixing a salt and a H-bond donor. Properties of such a DES depend on its constituents. Change in temperature and addition of water, a benign cosolvent, can change the physicochemical properties of DESs. The effect of changing temperature and addition of water on solvatochromic probe behavior within three DESs formed from choline chloride combined with 1,2-ethanediol, glycerol, and urea, respectively, in 1:2 mol ratios termed ethaline, glyceline, and reline is presented. Increase in temperature results in reduced H-bond donating acidity of the DESs. Dipolarity/polarizability and H-bond accepting basicity do not change with changing temperature of the DESs. The response of the fluorescence probe pyrene also indicates a decrease in the polarity of the DESs as temperature is increased. Addition of water to DES results in increased dipolarity/polarizability and a decrease in H-bond accepting basicity. Except for pyrene, solvatochromic probes exhibit responses close to those predicted from ideal-additive behavior with slight preferential solvation by DES within the aqueous mixtures. Pyrene response reveals significant preferential solvation by DES and/or the presence of solvent-solvent interactions, especially within aqueous mixtures of ethaline and glyceline, the DESs constituted of H-bond donors with hydroxyl functionalities. FTIR absorbance and Raman spectroscopic measurements of aqueous DES mixtures support the outcomes from solvatochromic probe responses. Aqueous mixtures of ethaline and glyceline possess relatively more interspecies H-bonds as compared to aqueous mixtures of reline, where interstitial accommodation of water within the reline molecular network appears to dominate. PMID:25418894
Evaluation of toxicity and biodegradability of choline chloride based deep eutectic solvents.
RadoÜevi?, Kristina; Bubalo, Marina Cvjetko; Sr?ek, ViÜnje Gaurina; Grgas, Dijana; Dragi?evi?, Tibela Landeka; Redovnikovi?, Ivana Radoj?i?
Deep eutectic solvents (DESs) have been dramatically expanding in popularity as a new generation of environmentally friendly solvents with possible applications in various industrial fields, but their ecological footprint has not yet been thoroughly investigated. In the present study, three choline chloride-based DESs with glucose, glycerol and oxalic acid as hydrogen bond donors were evaluated for in vitro toxicity using fish and human cell line, phytotoxicity using wheat and biodegradability using wastewater microorganisms through closed bottle test. Obtained in vitro toxicity data on cell lines indicate that choline chloride: glucose and choline chloride:glycerol possess low cytotoxicity (EC50>10 mM for both cell lines) while choline chloride:oxalic acid possess moderate cytotoxicity (EC50 value 1.64 mM and 4.19 mM for fish and human cell line, respectively). Results on phytotoxicity imply that tested DESs are non-toxic with seed germination EC50 values higher than 5000 mg L(-1). All tested DESs were classified as'readily biodegradable' based on their high levels of mineralization (68-96%). These findings indicate that DESs have a green profile and a good prospect for a wider use in the field of green technologies. PMID:25463852
Improved antibacterial phototoxicity of a neutral porphyrin in natural deep eutectic solvents.
Wikene, Kristine Opsvik; Bruzell, Ellen; T°nnesen, Hanne Hjorth
Neutral porphyrins for antibacterial photodynamic therapy (aPDT) have received little attention due to their tendency to aggregate in aqueous media and reports of low phototoxic effect. These compounds may be less toxic to cells than positively and negatively charged photosensitisers. The preparation of highly bacterial phototoxic formulations of neutral porphyrins remains an open field of research with great potential if achievable. The purpose of this study was to develop novel hydrophilic formulations of the neutral porphyrin 5,10,15,20-tetrakis(4-hydroxyphenyl)-porphyrin (THPP) by use of natural deep eutectic solvents (NADES) prepared by the solvent evaporation method. Physical and photochemical stability and in vitro photoinactivation of Enterococcus faecalis and Escherichia coli were investigated. Two of the 15 NADES investigated demonstrated superior solubilising properties of THPP. The photostability of THPP was higher in NADES than in methanol. A 100-fold dilution of the preparations with buffer to a final concentration of 0.5-5nM THPP resulted in complete photoinactivation of E. faecalis and E. coli both in their exponential and stationary phase. THPP demonstrated significantly higher phototoxicity when formulated in NADES than in other aqueous preparations like phosphate buffered saline. NADES as a formulation concept for photosensitisers shows a great potential in aPDT. PMID:25966307
Simultaneous extraction of flavonoids from Chamaecyparis obtusa using deep eutectic solvents as additives of conventional extractions solvents.
Tang, Baokun; Park, Ha Eun; Row, Kyung Ho
Three flavones (quercetin, myricetin and amentoflavone) were extracted from Chamaecyparis obtusa leaves using deep eutectic solvents (DESs) as additives to conventional extractions solvents. Sixteen DESs were synthesized from different salts and hydrogen bond donors. In addition, C. obtusa was extracted under optimal conditions of methanol as the solvent in the heating process (60░C) for 120 min at a solid/liquid ratio of 80%. Under these optimal conditions, a good linear relationship was observed at analyte concentrations ranging from 5.0 to 200.0 ?g/mL (R(2) > 0.999). The extraction recovery ranged from 96.7 to 103.3% with the inter- and intraday relative standard deviations of <4.97%. Under the optimal conditions, from C. obtusa, the quantities of quercetin, myricetin and amentoflavone extracted were 325.90, 8.66 and 50.34 Ąg/mL, respectively. Overall, DESs are expected to have a wide range of applications. PMID:25228687
Liquid-liquid equilibria for the ternary system (phosphonium based deep eutectic solvent-benzene-hexane) at different temperatures: A new solvent introduced
Mukhtar A. Kareem; Farouq S. Mjalli; M. A. Hashim; Inas M. AlNashef
In this work we studied the applicability of one ionic liquid analogues namely phosphonium based deep eutectic solvent (DES) in the extraction of aromatic hydrocarbons from aromatic\\/aliphatic mixtures. Experimental data for liquid-liquid equilibria (LLE) were obtained for various mixtures of (benzene. +. hexane. +. DES) at 27, 35 and 45 ░C. Some of the mixtures showed excellent results in terms
Deep eutectic solvents in polymerizations: a greener alternative to conventional syntheses.
del Monte, Francisco; Carriazo, Daniel; Serrano, MarĒa C; Gutiķrrez, MarĒa C; Ferrer, M Luisa
The use of deep eutectic solvents (DESs) that act as all-in-one solvent-template-reactant systems offers an interesting green alternative to conventional syntheses in materials science. This Review aims to provide a comprehensive overview to emphasize the similarities and discrepancies between DES-assisted and conventional syntheses and rationalize certain green features that are common for the three DES-assisted syntheses described herein: one case of radical polymerization and two cases of polycondensations. For instance, DESs contain the precursor itself and some additional components that either provide certain functionality (e.g., drug delivery and controlled release, or electrical conductivity) to the resulting materials or direct their formation with a particular structure (e.g., hierarchical-type). Moreover, DESs provide a reaction medium, so polymerizations are ultimately carried out in a solventless fashion. This means that DES-assisted syntheses match green chemistry principles 2 and 5 because of the economy of reagents and solvents, whereas the functionality incorporated by the second component allows the need for any post-synthesis derivatization to be minimized or even fully avoided (principle 8). DESs also provide new precursors that favor more efficient polymerization (principle 6) by decreasing the energy input required for reaction progress. Finally, the use of mild reaction conditions in combination with the compositional versatility of DESs, which allows low-toxic components to be selected, is also of interest from the viewpoint of green chemistry because it opens up the way to design biocompatible and/or eco-friendly synthetic methods (principle 3). PMID:24376090
A green deep eutectic solvent-based aqueous two-phase system for protein extracting.
Xu, Kaijia; Wang, Yuzhi; Huang, Yanhua; Li, Na; Wen, Qian
As a new type of green solvent, deep eutectic solvent (DES) has been applied for the extraction of proteins with an aqueous two-phase system (ATPS) in this work. Four kinds of choline chloride (ChCl)-based DESs were synthesized to extract bovine serum albumin (BSA), and ChCl-glycerol was selected as the suitable extraction solvent. Single factor experiments have been done to investigate the effects of the extraction process, including the amount of DES, the concentration of salt, the mass of protein, the shaking time, the temperature and PH value. Experimental results show 98.16% of the BSA could be extracted into the DES-rich phase in a single-step extraction under the optimized conditions. A high extraction efficiency of 94.36% was achieved, while the conditions were applied to the extraction of trypsin (Try). Precision, repeatability and stability experiments were studied and the relative standard deviations (RSD) of the extraction efficiency were 0.4246% (n=3), 1.6057% (n=3) and 1.6132% (n=3), respectively. Conformation of BSA was not changed during the extraction process according to the investigation of UV-vis spectra, FT-IR spectra and CD spectra of BSA. The conductivity, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to explore the mechanism of the extraction. It turned out that the formation of DES-protein aggregates play a significant role in the separation process. All the results suggest that ChCl-based DES-ATPS are supposed to have the potential to provide new possibilities in the separation of proteins. PMID:25732422
Evaluating the Performance of Deep Eutectic Solvents for Use in Extractive Denitrification of Liquid Fuels by the Conductor-like Screening Model for Real Solvents
Hanee F. Hizaddin; Anantharaj Ramalingam; Mohd Ali Hashim; Mohamed K. O. Hadj-Kali
A total of 94 deep eutectic solvents (DESs) based on different combinations of salt cation, anion, hydrogen-bond donor (HBD) and salt:HBD molar ratio are screened via the conductor-like screening model for real solvents for potential use in the extractive denitrification of diesel. Five nonbasic and six basic nitrogen compounds were included in this study. The activity coefficient at infinite dilution,
A facile approach to prepare a dual functionalized DNA based material in a bio-deep eutectic solvent.
Mondal, Dibyendu; Bhatt, Jitkumar; Sharma, Mukesh; Chatterjee, Shruti; Prasad, Kamalesh
DNA (Salmon testes) was functionalized by Fe3O4 nanoparticles and protonated layered dititanate sheets (H2ĘTi2O5ĘH2O) in a mixture of choline chloride and ethylene glycol (a deep eutectic solvent) to yield a hybrid material having magnetic and antibacterial properties. Ti sheets were found to interact with the phosphate moieties, while Fe interacted with the base pair of DNA in the hybrid material. PMID:24609301
A new processing route for cleaner production of biodiesel fuel using a choline chloride based deep eutectic solvent
A. Hayyan; M. A. Hashim; M. Hayyan; F. S. Mjalli; I. M. Alnashef
In this study, the free fatty acids (FFA) content in acidic crude palm oil (ACPO) was converted to fatty acid methyl esters (FAME) using a choline chloride based deep eutectic solvent (ChCl-DES) for the first time. This DES is composed of a mixture of a hydrogen bond donor (i.e. p-toluenesulfonic acid monohydrate) and a salt (i.e. choline chloride). The pre-treatment
In situ electrochemical digital holographic microscopy; a study of metal electrodeposition in deep eutectic solvents.
Abbott, Andrew P; Azam, Muhammad; Ryder, Karl S; Saleem, Saima
This study has shown for the first time that digital holographic microscopy (DHM) can be used as a new analytical tool in analysis of kinetic mechanism and growth during electrolytic deposition processes. Unlike many alternative established electrochemical microscopy methods such as probe microscopy, DHM is both the noninvasive and noncontact, the unique holographic imaging allows the observations and measurement to be made remotely. DHM also provides interferometric resolution (nanometer vertical scale) with a very short acquisition time. It is a surface metrology technique that enables the retrieval of information about a 3D structure from the phase contrast of a single hologram acquired using a conventional digital camera. Here DHM has been applied to investigate directly the electro-crystallization of a metal on a substrate in real time (in situ) from two deep eutectic solvent (DES) systems based on mixture of choline chloride and either urea or ethylene glycol. We show, using electrochemical DHM that the nucleation and growth of silver deposits in these systems are quite distinct and influenced strongly by the hydrogen bond donor of the DES. PMID:23751128
Ultrasound assisted-deep eutectic solvent extraction of iron from sheep, bovine and chicken liver samples.
Yilmaz, Erkan; Soylak, Mustafa
A green, novel and effective ultrasound assisted-deep eutectic solvent (DES) extraction (UA-DES-E) procedure was developed for extraction of iron from sheep, bovine and chicken liver samples. The analytical parameters including type and composition DES, volume of DES, ultrasonication time and ratio of sample to DES were optimized by using 50mg of the NIST SRM 1577b bovine liver certified reference material. The limit of detection (LOD) and the limit of quantification (LOQ) were found as 0.026Ąg mL(-1) and 0.085Ąg mL(-1), respectively. The relative standard deviation (RSD) as a result of 7 replicates of 50mg of certified reference material was 1.4%. The accuracy of proposed method was checked by the addition/recovery tests to NIST SRM 1577b bovine liver and a sheep liver. The extraction method was applied to extraction of iron from bovine, sheep and chicken liver samples retail from markets at Kayseri, Turkey with satisfactory results (recoveries higher than 95%). PMID:25702999
Electrochemical fabrication of nanoporous copper films in choline chloride-urea deep eutectic solvent.
Zhang, Q B; Abbott, Andrew P; Yang, C
Nanoporous copper films were fabricated by a facile electrochemical alloying/dealloying process without the need of a template. A deep eutectic solvent made from choline chloride (ChCl) and urea was used with zinc oxide as the metal salt. Cyclic voltammetry was used to characterise the electrochemical reduction of zinc and follow Cu-Zn alloy formation on the copper substrate at elevated temperatures from 353 to 393 K. The alloy formation was confirmed by X-ray diffraction spectra. 3D, open and bicontinuous nanoporous copper films were obtained by in situ electrochemically etching (dealloying) of the zinc component in the Cu-Zn surface alloys at an appropriate potential (-0.4 V vs. Ag). This dealloying process was found to be highly temperature dependent and surface diffusion controlled, which involved the self-assembly of copper atoms at the alloy/electrolyte interface. Additionally, the effects of the deposition parameters, including deposition temperature, current density as well as total charge density on resulting the microstructure were investigated by scanning electron microscopy, and atomic force microscope. PMID:25972227
G-quadruplexes form ultrastable parallel structures in deep eutectic solvent.
Zhao, Chuanqi; Ren, Jinsong; Qu, Xiaogang
G-quadruplex DNA is highly polymorphic. Its conformation transition is involved in a series of important life events. These controllable diverse structures also make G-quadruplex DNA a promising candidate as catalyst, biosensor, and DNA-based architecture. So far, G-quadruplex DNA-based applications are restricted done in aqueous media. Since many chemical reactions and devices are required to be performed under strictly anhydrous conditions, even at high temperature, it is challenging and meaningful to conduct G-quadruplex DNA in water-free medium. In this report, we systemically studied 10 representative G-quadruplexes in anhydrous room-temperature deep eutectic solvents (DESs). The results indicate that intramolecular, intermolecular, and even higher-order G-quadruplex structures can be formed in DES. Intriguingly, in DES, parallel structure becomes the G-quadruplex DNA preferred conformation. More importantly, compared to aqueous media, G-quadruplex has ultrastability in DES and, surprisingly, some G-quadruplex DNA can survive even beyond 110 ░C. Our work would shed light on the applications of G-quadruplex DNA to chemical reactions and DNA-based devices performed in an anhydrous environment, even at high temperature. PMID:23282194
The ionothermal synthesis of metal organic frameworks, Ln(C 9O 6H 3)((CH 3NH) 2CO) 2, using deep eutectic solvents
Farida Himeur; Irene Stein; David S. Wragg; Alexandra M. Z. Slawin; Philip Lightfoot; Russell E. Morris
Three new isostructural materials Ln(TMA)(DMU)2 (Ln(C9O6H3)((CH3NH)2CO)2; Ln: La 1, Nd 2, Eu 3; TMA: trimesate, DMU: dimethylurea) have been synthesised ionothermally using a choline chloride\\/dimethylurea deep eutectic mixture as the solvent. Normally in ionothermal synthesis the urea portion of the deep eutectic solvent is unstable, breaking down to release ammonium cations that act as templates. In the case of 1¢3,
Aqueous Ionic Liquids and Deep Eutectic Solvents for Cellulosic Biomass Pretreatment and Saccharification.
Xia, Shuqian; Baker, Gary A; Li, Hao; Ravula, Sudhir; Zhao, Hua
Ionic liquids (ILs) have proven effective solvents for pretreating lignocellulose, leading to the fast saccharification of cellulose and hemicellulose. However, the high current cost of most ILs remains a major barrier to commercializing this recent approach at a practical scale. As a strategic detour, aqueous solutions of ILs are also being explored as less costly alternatives to neat ILs for cellulose pretreatment. However, limited studies on a few select IL systems are known and there remains no systematic survey of various ILs, eluding an in-depth understanding of pretreatment mechanisms afforded by aqueous IL systems. As a step toward filling this gap, this study presents results for Avicel cellulose pretreatment by neat and aqueous solutions (1.0 and 2.0 M) of 20 different ILs and three deep eutectic solvents, correlating enzymatic hydrolysis rates of pretreated cellulose with various IL properties such as hydrogen-bond basicity, polarity, Hofmeister ranking, and hydrophobicity. The pretreatment efficiencies of neat ILs may be loosely correlated to the hydrogen-bond basicity of the constituent anion and IL polarity; however, the pretreatment efficacies for aqueous ILs are more complicated and cannot be simply related to any single IL property. Several aqueous IL systems have been identified as effective alternatives to neat ILs in lignocellulose pretreatment. In particular, this study reveals that aqueous solutions of 1-butyl-3-methylimidazolium methanesulfonate ([BMIM][MeSO3]) are effective for pretreating switchgrass (Panicum virgatum), resulting in fast saccharification of both cellulose and hemicellulose. An integrated analysis afforded by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis and cellulase adsorption isotherm of lignocellulose samples is further used to deliver a more complete view of the structural changes attending aqueous IL pretreatment. PMID:24729865
Effects of ultrasound and temperature on copper electro reduction in Deep Eutectic Solvents (DES).
Mandroyan, Audrey; Mourad-Mahmoud, Mahmoud; Doche, Marie-Laure; Hihn, Jean-Yves
This paper concerns a preliminary study for a new copper recovery process from ionic solvent. The aim of this work is to study the reduction of copper in Deep Eutectic Solvent (choline chloride-ethylene glycol) and to compare the influence of temperature and the ultrasound effects on kinetic parameters. Solutions were prepared by dissolution of chloride copper salt CuCl2 (to obtain Copper in oxidation degree II) or CuCl (to obtain Copper in oxidation degree I) and by leaching metallic copper directly in DES. The spectrophotometry UV-visible analysis of the leached solution showed that the copper soluble form obtained is at oxidation degree I (Copper I). Both cyclic voltammetry and linear voltammetry were performed in the three solutions at three temperatures (25, 50 and 80░C) and under ultrasonic conditions (F=20kHz, PT=5.8W) to calculate the mass transfer diffusion coefficient kD and the standard rate coefficient k░. These parameters are used to determine that copper reduction is carried out via a mixed kinetic-diffusion control process. Temperature and ultrasound have the same effect on mass transfer for reduction of Cu(II)/Cu(I). On the other hand, temperature is more beneficial than ultrasound for mass transfer of Cu(I)/Cu. Standard rate constant improvement due to temperature increase is of the same order as that obtained with ultrasound. But, by combining higher temperature and ultrasound (F=20kHz, PT=5.6W at 50░C), reduction limiting current is increased by a factor of 10 compared to initial conditions (T=25░C, silent), because ultrasonic stirring is more efficient in lower viscosity fluid. These values can be considered as key-parameters in the design of copper recovery in global processes using ultrasound. PMID:24629581
Aqueous Ionic Liquids and Deep Eutectic Solvents for Cellulosic Biomass Pretreatment and Saccharification
Xia, Shuqian; Baker, Gary A.; Li, Hao; Ravula, Sudhir; Zhao, Hua
Ionic liquids (ILs) have proven effective solvents for pretreating lignocellulose, leading to the fast saccharification of cellulose and hemicellulose. However, the high current cost of most ILs remains a major barrier to commercializing this recent approach at a practical scale. As a strategic detour, aqueous solutions of ILs are also being explored as less costly alternatives to neat ILs for cellulose pretreatment. However, limited studies on a few select IL systems are known and there remains no systematic survey of various ILs, eluding an in-depth understanding of pretreatment mechanisms afforded by aqueous IL systems. As a step toward filling this gap, this study presents results for Avicel cellulose pretreatment by neat and aqueous solutions (1.0 and 2.0 M) of 20 different ILs and three deep eutectic solvents, correlating enzymatic hydrolysis rates of pretreated cellulose with various IL properties such as hydrogen-bond basicity, polarity, Hofmeister ranking, and hydrophobicity. The pretreatment efficiencies of neat ILs may be loosely correlated to the hydrogen-bond basicity of the constituent anion and IL polarity; however, the pretreatment efficacies for aqueous ILs are more complicated and cannot be simply related to any single IL property. Several aqueous IL systems have been identified as effective alternatives to neat ILs in lignocellulose pretreatment. In particular, this study reveals that aqueous solutions of 1-butyl-3-methylimidazolium methanesulfonate ([BMIM][MeSO3]) are effective for pretreating switchgrass (Panicum virgatum), resulting in fast saccharification of both cellulose and hemicellulose. An integrated analysis afforded by X-ray diffraction, scanning electron microscopy, thermogravimetric analysis and cellulase adsorption isotherm of lignocellulose samples is further used to deliver a more complete view of the structural changes attending aqueous IL pretreatment. PMID:24729865
Differential capacity of a deep eutectic solvent based on choline chloride and glycerol on solid electrodes
Marta Figueiredo; Cristiana Gomes; Renata Costa; Ana Martins; Carlos M. Pereira; Fernando Silva
The properties of the interface between platinum, gold and glassy carbon electrodes and a deep eutectic ionic liquid based on choline chloride and glycerol were assessed using cyclic voltammetry and electrochemical impedance spectroscopy. The double layer differential capacitance, obtained from electrochemical impedance, reveals a slight dependence of the potential but it is sensitive to the electrode material. In contrast to
Fluorescence Spectroscopic Studies of (Amide + Electrolyte) Deep Eutectic Systems Biswajit Guchhait and Ranjit Biswas*
Biswas, Ranjit
glass transition. Keywords: deep eutectic solvents, fluorescence measurements, viscosity decoupling Refs liquid at or near room temperature. These systems are known as deep eutectic solvents (DES) and exhibit1 Fluorescence Spectroscopic Studies of (Amide + Electrolyte) Deep Eutectic Systems Biswajit
Deep eutectic solvent-assisted synthesis of biodegradable polyesters with antibacterial properties.
GarcĒa-Arg³elles, Sara; Serrano, M Concepci¾n; Gutiķrrez, MarĒa C; Ferrer, M Luisa; Yuste, Luis; Rojo, Fernando; del Monte, Francisco
Bacterial infection related to the implantation of medical devices represents a serious clinical complication, with dramatic consequences for many patients. In past decades, numerous attempts have been made to develop materials with antibacterial and/or antifouling properties by the incorporation of antibiotic and/or antiseptic compounds. In this context, deep eutectic solvents (DESs) are acquiring increasing interest not only as efficient carriers of active principle ingredients (APIs) but also as assistant platforms for the synthesis of a wide repertoire of polymer-related materials. Herein, we have successfully prepared biodegradable poly(octanediol-co-citrate) polyesters with acquired antibacterial properties by the DES-assisted incorporation of quaternary ammonium or phosphonium salts into the polymer network. In the resulting polymers, the presence of these salts (i.e., choline chloride, tetraethylammonium bromide, hexadecyltrimethylammonium bromide, and methyltriphenylphosphonium bromide) inhibits bacterial growth in the early postimplantation steps, as tested in cultures of Escherichia coli on solid agar plates. Later, positive polymer cytocompatibility is expected to support cell colonization, as anticipated from in vitro preliminary studies with L929 fibroblasts. Finally, the attractive elastic properties of these polyesters permit matching those of soft tissues such as skin. For all of these reasons, we envisage the utility of some of these antibacterial, biocompatible, and biodegradable polyesters as potential candidates for the preparation of antimicrobial wound dressings. These results further emphasize the enormous versatility of DES-assisted synthesis for the incorporation, in the synthesis step, of a wide palette of APIs into polymeric networks suitable for biomedical applications. PMID:23808373
In Vitro and In Vivo toxicity profiling of ammonium-based deep eutectic solvents.
Hayyan, Maan; Looi, Chung Yeng; Hayyan, Adeeb; Wong, Won Fen; Hashim, Mohd Ali
The cytotoxic potential of ammonium-based deep eutectic solvents (DESs) with four hydrogen bond donors, namely glycerine (Gl), ethylene glycol (EG), triethylene glycol (TEG) and urea (U) were investigated. The toxicity of DESs was examined using In Vitro cell lines and In Vivo animal model. IC50 and selectivity index were determined for the DESs, their individual components and their combinations as aqueous solutions for comparison purposes. The cytotoxicity effect of DESs varied depending on cell lines. The IC50 for the GlDES, EGDES, UDES and TEGDES followed the sequence of TEGDES< GlDES< EGDES< UDES for OKF6, MCF-7, A375, HT29 and H413, respectively. GlDES was selective against MCF-7 and A375, EGDES was selective against MCF-7, PC3, HepG2 and HT29, UDES was selective against MCF-7, PC3, HepG2 and HT29, and TEGDES was selective against MCF-7 and A375. However, acute toxicity studies using ICR mice showed that these DESs were relatively toxic in comparison to their individual components. DES did not cause DNA damage, but it could enhance ROS production and induce apoptosis in treated cancer cells as evidenced by marked LDH release. Furthermore, the examined DESs showed less cytotoxicity compared with ionic liquids. To the best of our knowledge, this is the first time that combined In Vitro and In Vivo toxicity profiles of DESs were being demonstrated, raising the toxicity issue of these neoteric mixtures and their potential applicability to be used for therapeutic purposes. PMID:25679975
Phase equilibria of toluene\\/heptane with tetrabutylphosphonium bromide based deep eutectic solvents for the potential use in the separation of aromatics from naphtha
M. A. Kareem; F. S. Mjalli; M. A. Hashim; M. K. O. Hadj-Kali; F. S. G. Bagh; I. M. Alnashef
In this work, new solvents are introduced to conduct the task of removing aromatic hydrocarbons from the feed stream to ethylene cracker. Liquid-liquid equilibrium (LLE) data for ternary systems of toluene and heptane with two newly introduced deep eutectic solvents (DESs) were estimated experimentally at 40, 50 and 60. ░C and atmospheric pressure. The DESs are made from tetrabutylphosphonium bromide
Phase equilibria of toluene\\/heptane with deep eutectic solvents based on ethyltriphenylphosphonium iodide for the potential use in the separation of aromatics from naphtha
M. A. Kareem; F. S. Mjalli; M. A. Hashim; M. K. O. Hadj-Kali; F. S. Ghareh Bagh; I. M. Alnashef
In this work, the liquid-liquid extraction of toluene from hydrocarbons mixtures (toluene\\/heptane) was investigated using deep eutectic solvents as solvents. Ethyltriphenylphosphonium iodide as a salt with either ethylene glycol or sulfolane as hydrogen-bond donors (HBDs) were utilized for synthesizing six DESs. (Liquid + liquid) equilibria data were determined experimentally for the ternary system (toluene + heptane + DES) at (30,
Main chemical species and molecular structure of deep eutectic solvent studied by experiments with DFT calculation: a case of choline chloride and magnesium chloride hexahydrate.
Zhang, Chao; Jia, Yongzhong; Jing, Yan; Wang, Huaiyou; Hong, Kai
The infrared spectrum of deep eutectic solvent of choline chloride and magnesium chloride hexahydrate was measured by the FTIR spectroscopy and analyzed with the aid of DFT calculations. The main chemical species and molecular structure in deep eutectic solvent of [MgClm(H2O)6-m]2-m and [ChxCly]x+y complexes were mainly identified and the active ion of magnesium complex during the electrochemical process was obtained. The mechanism of the electrochemical process of deep eutectic solvent of choline chloride and magnesium chloride hexahydrate was well explained by combination theoretical calculations and experimental. Besides, based on our results we proposed a new system for the dehydration study of magnesium chloride hexahydrate. PMID:25031082
Separation of BTEX aromatics from n-octane using a (tetrabutylammonium bromide + sulfolane) deep eutectic solvent - experiments and COSMO-RS prediction
Sarwono Mulyono; Hanee F. Hizaddin; Inas M. Alnashef; Mohd A. Hashim; Anis H. Fakeeha; Mohamed K. Hadj-Kali
Separation of aromatics from aliphatics is a challenging process because of the close range of their boiling points and the formation of several combinations of azeotropes. Until now, no feasible separation process is available for aromatic concentrations below 20 wt%. In this work, we have investigated the possibility of using a selected deep eutectic solvent (DES) for the liquid-liquid extraction
Versatile Structure-directing Roles of Deep Eutectic Solvents and Their Implication in Generation of Porosity and Open Metal Sites for Gas Storage**
Zhang, Jian; Wu, Tao; Chen, Shumei; Feng, Pingyun; Bu, Xianhui
Trap it in and burn it out: the deep eutectic solvent provides a versatile route for the creation of highly stable porous frameworks encapsulating neutral coordinating ligand molecule, which can escape intact from the pore upon heating to directly become crystals, leaving behind permanent porosity and coordinatively unsaturated metal sites with potential applications in gas storage and catalysis. PMID:19343752
Deep eutectic solvents and glycerol: a simple, environmentally benign and efficient catalyst\\/reaction media for synthesis of N-aryl phthalimide derivatives
Hyacintha Rennet Lobo; Balvant Shyam Singh; Ganapati Subray Shankarling
Deep eutectic solvents (DES) and glycerol have been successfully employed as efficient catalysts\\/reaction media in the synthesis of N-aryl phthalimide derivatives from phthalic anhydride and primary aromatic amines. The DES prepared from choline chloride and malonic acid proved to be an efficient catalyst whereas glycerol and the DES of choline chloride and urea played a dual role of catalyst and
Electrochemically shape-controlled synthesis in deep eutectic solvents: triambic icosahedral platinum nanocrystals with high-index facets and their enhanced catalytic activity.
Wei, Lu; Zhou, Zhi-You; Chen, Sheng-Pei; Xu, Chang-Deng; Su, Dangsheng; Schuster, Manfred Erwin; Sun, Shi-Gang
Pt triambic icosahedral nanocrystals (TIH NCs) enclosed by {771} high-index facets were successfully synthesized electrochemically, for the first time, in ChCl-urea based deep eutectic solvents, and exhibited higher electrocatalytic activity and stability towards ethanol electrooxidation than a commercial Pt black catalyst. PMID:24084858
Synthesis of gold microstructures with surface nanoroughness using a deep eutectic solvent for catalytic and diagnostic applications.
Oh, Ju-Hwan; Lee, Jae-Seung
We synthesized highly monodisperse gold microparticles (AuMPs) using a deep eutectic solvent (DES) which composed of choline chloride and malonic acid as both a reaction medium and structure-directing agent. These microparticles exhibit distinctive surface nanoroughness and highly defined diameters that can be precisely controlled over a range of a few micrometers under different reductive conditions. The internal and external structures of the particles are thoroughly investigated by electron microscopy, which is further analyzed in association with their optical properties. We also investigate the gold microparticle concentration-dependent catalytic property employing a reductive reaction of 4-nitrophenol to 4-aminopenol as a model system. Importantly, the gold microparticles are densely functionalized with DNA and reversibly assemble with DNA-gold nanoparticle conjugate probes for the colorimetric detection of target DNA sequences, demonstrating that these novel structures can be utilized as platforms that quickly regulate the optical properties of plasmonic nanoparticles for diagnostic applications. PMID:24734628
Electrochemical exfoliation of graphite in quaternary ammonium-based deep eutectic solvents: a route for the mass production of graphane.
Abdelkader, Amr M; Patten, Hollie V; Li, Zheling; Chen, Yiqiang; Kinloch, Ian A
We demonstrate a facile and scalable electrochemical approach to exfoliate graphite, which permits in situ hydrogenation of the resultant graphene via a solvated NR(4+) graphite compound in quaternary ammonium-based deep eutectic solvents. Spectroscopic studies reveal the presence of sp(3) C-H bonds in the hydrogenated graphene. The resulting materials consist of micrometre-sized and predominantly monolayer to few layers thick hydrogenated graphenic flakes. A large band gap (?4 eV) further establishes the high level of hydrogenation. It is also possible to tune the band gap introduced to the graphene by controlling the level of hydrogenation. The mechanism of the exfoliation and hydrogenation is also discussed. PMID:26074262
Fabrication of PbS thin films composed of highly (200)-oriented nano-/micro-rods in deep eutectic solvent
NASA Astrophysics Data System (ADS)
Chen, Jun; Zhang, Jianjun; Xu, Huifang; Ouyang, Yan; Zhan, Funan; Li, Qiang
PbS thin films composed of highly (200)-oriented shuttle-like nano-/micro-rods were successfully fabricated on glass substrates by the environment friendly ionothermal method at 140 ░C in deep eutectic solvent (DES). The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), ultraviolet-visible (UV-vis) and photoluminescence (PL) spectra, respectively. The possible mechanism of the oriented growth of PbS nano-/micro-rods was discussed. The PbS thin films composed of shuttle-like nano-/micro-rods exhibited a large absorbance property in the wavelength range of 350-1100 nm, and moreover, the PL spectrum had a broad emission band centered at 490 nm. The shuttle-like PbS nano-/micro-rods-based thin films might have potential application in solar cells.
Evaluation of alcohol-based deep eutectic solvent in extraction and determination of flavonoids with response surface methodology optimization.
Bi, Wentao; Tian, Minglei; Row, Kyung Ho
Deep eutectic solvents (DESs) are emerging rapidly as a new type of green solvent instead of an ionic liquid (IL), and are typically formed by mixing choline chloride with hydrogen bond donors. Few studies have applied DESs to the extraction and determination of bioactive compounds. Therefore, in the present study, DESs were used to extract flavonoids (myricetin and amentoflavone), which are well known and widely used antioxidants, to extend their applications. A range of alcohol-based DESs with different alcohols to choline chloride (ChCl) mixing ratios were used for extraction using several extraction methods. Other factors, such as temperature, time, water addition and solid/liquid ratio, were examined systematically using a response surface methodology (RSM). A total of 0.031 and 0.518 mg g(-1) of myricetin and amentoflavone were extracted under the optimized conditions: 35 vol% of water in ChCl/1,4-butanediol (1/5) at 70.0 ░C for 40.0 min and a solid/liquid ratio of 1/1 (g 10 mL(-1)). Good linearity was obtained from 0.1 ū 10(-3) to 0.1 mg mL(-1) (r(2)>0.999). The excellent properties of DESs highlight their potential as promising green solvents for the extraction and determination of a range of bioactive compounds or drugs. PMID:23481471
Lipase-catalyzed (trans)esterification of 5-hydroxy- methylfurfural and separation from HMF esters using deep-eutectic solvents.
Krystof, Monika; Pķrez-Sßnchez, MarĒa; DomĒnguez de MarĒa, Pablo
5-Hydroxymethylfurfural (HMF) is a valuable biomass-derived building block. Among possible HMF valorization products, a broad range of HMF esters can be synthesized. These HMF esters have found some promising applications, such as monomers, fuels, additives, surfactants, and fungicides, and thus several catalytic approaches for HMF (trans)esterifications have been reported. The intrinsic reactivity of HMF is challenging, forcing the use of mild reaction conditions to avoid by-product formation. This paper explores the lipase-catalyzed (trans)esterification of HMF with different acyl donors (carboxylic acids and methyl- and ethyl esters) mostly in solvent-free conditions. The results demonstrate that lipases may be promising alternatives for the synthesis of HMF esters-with high productivities and reactions at high substrate loadings-provided that robust systems for lipase immobilization are applied to assure an adequate reusability of the enzymes. Once (trans)esterifications have been conducted, the separation of unreacted HMF and HMF esters is performed by using deep-eutectic solvents (DES) as separation agents. DES are able to dissolve hydrogen-bond donors (e.g., HMF), whereas non-hydrogen-bond donors (in this case HMF esters) form a second phase. By using this approach, high ester purities (>99 %) and efficiencies (up to >90 % HMF ester recovery) in separations were obtained by using choline chloride-based DES. PMID:23456887
Deep eutectic solvents for the self-assembly of gold nanoparticles: a SAXS, UV-Vis, and TEM investigation.
Raghuwanshi, Vikram Singh; Ochmann, Miguel; Hoell, Armin; Polzer, Frank; Rademann, Klaus
In this work, we report the formation and growth mechanisms of gold nanoparticles (AuNPs) in eco-friendly deep eutectic solvents (DES; choline chloride and urea). AuNPs are synthesized on the DES surface via a low-energy sputter deposition method. Detailed small angle X-ray scattering (SAXS), UV-Vis, and cryogenic transmission electron microscopy (cryo-TEM) investigations show the formation of AuNPs of 5 nm diameter. Data analysis reveals that for a prolonged gold-sputtering time there is no change in the size of the particles. Only the concentration of AuNPs increases linearly in time. More surprisingly, the self-assembly of AuNPs into a first and second shell ordered system is observed directly by in situ SAXS for prolonged gold-sputtering times. The self-assembly mechanism is explained by the templating nature of DES combined with the equilibrium between specific physical interaction forces between the AuNPs. A disulfide-based stabilizer, bis((2-mercaptoethyl)trimethylammonium) disulfide dichloride, was applied to suppress the self-assembly. Moreover, the stabilizer even reverses the self-assembled or agglomerated AuNPs back to stable 5 nm individual particles as directly evidenced by UV-Vis. The template behavior of DES is compared to that of nontemplating solvent castor oil. Our results will also pave the way to understand and control the self-assembly of metallic and bimetallic nanoparticles. PMID:24814886
Improved solubility of DNA in recyclable and reusable bio-based deep eutectic solvents with long-term structural and chemical stability.
Mondal, Dibyendu; Sharma, Mukesh; Mukesh, Chandrakant; Gupta, Vishal; Prasad, Kamalesh
The solubility of DNA in bio-based deep eutectic solvents (DESs) consisting of mixtures of choline chloride with levulinic acid, glycerol, ethylene glycol, sorbitol and resorcinol was investigated. The macromolecule was found to be soluble and chemically and structurally stable in DESs consisting of mixtures containing glycerol and ethylene glycol. Furthermore recyclability of the DESs was demonstrated over three consecutive reuses in DNA dissolution. PMID:24022824
In situ fabrication of electrochemically grown mesoporous metallic thin films by anodic dissolution in deep eutectic solvents.
Renjith, Anu; Roy, Arun; Lakshminarayanan, V
We describe here a simple electrodeposition process of forming thin films of noble metallic nanoparticles such as Au, Ag and Pd in deep eutectic solvents (DES). The method consists of anodic dissolution of the corresponding metal in DES followed by the deposition on the cathodic surface. The anodic dissolution process in DES overcomes the problems associated with copious hydrogen and oxygen evolution on the electrode surface when carried out in aqueous medium. The proposed method utilizes the inherent abilities of DES to act as a reducing medium while simultaneously stabilizing the nanoparticles that are formed. The mesoporous metal films were characterized by SEM, XRD and electrochemical techniques. Potential applications of these substrates in surface enhanced Raman spectroscopy and electrocatalysis have been investigated. A large enhancement of Raman signal of analyte was achieved on the mesoporous silver substrate after removing all the stabilizer molecules from the surface by calcination. The highly porous texture of the electrodeposited film provides superior electro catalytic performance for hydrogen evolution reaction (HER). The mechanisms of HER on the fabricated substrates were studied by Tafel analysis and electrochemical impedance spectroscopy (EIS). PMID:24863793
How a protein can remain stable in a solvent with high content of urea: insights from molecular dynamics simulation of Candida antarctica lipase B in urea?:?choline chloride deep eutectic solvent.
Monhemi, Hassan; Housaindokht, Mohammad Reza; Moosavi-Movahedi, Ali Akbar; Bozorgmehr, Mohammad Reza
Deep eutectic solvents (DESs) are utilized as green and inexpensive alternatives to classical ionic liquids. It has been known that some of DESs can be used as solvent in the enzymatic reactions to obtain very green chemical processes. DESs are quite poorly understood at the molecular level. Moreover, we do not know much about the enzyme microstructure in such systems. For example, how some hydrolase can remain active and stable in a deep eutectic solvent including 9 M of urea? In this study, the molecular dynamics of DESs as a liquid was simulated at the molecular level. Urea?:?choline chloride as a well-known eutectic mixture was chosen as a model DES. The behavior of the lipase as a biocatalyst was studied in this system. For comparison, the enzyme structure was also simulated in 8M urea. The thermal stability of the enzyme was also evaluated in DESs, water, and 8M urea. The enzyme showed very good conformational stability in the urea?:?choline chloride mixture with about 66% urea (9 M) even at high temperatures. The results are in good agreement with recent experimental observations. In contrast, complete enzyme denaturation occurred in 8M urea with only 12% urea in water. It was found that urea molecules denature the enzyme by interrupting the intra-chain hydrogen bonds in a "direct denaturation mechanism". However, in a urea?:?choline chloride deep eutectic solvent, as a result of hydrogen bonding with choline and chloride ions, urea molecules have a low diffusion coefficient and cannot reach the protein domains. Interestingly, urea, choline, and chloride ions form hydrogen bonds with the surface residues of the enzyme which, instead of lipase denaturation, leads to greater enzyme stability. To the best of our knowledge, this is the first study in which the microstructural properties of a macromolecule are examined in a deep eutectic solvent. PMID:24930496
Deep eutectic solvents based on N-methylacetamide and a lithium salt as suitable electrolytes for lithium-ion batteries.
Boisset, Aurķlien; Menne, Sebastian; Jacquemin, Johan; Balducci, Andrea; Anouti, MķriĶm
In this work, we present a study on the physical and electrochemical properties of three new Deep Eutectic Solvents (DESs) based on N-methylacetamide (MAc) and a lithium salt (LiX, with X = bis[(trifluoromethyl)sulfonyl]imide, TFSI; hexafluorophosphate, PF6; or nitrate, NO3). Based on DSC measurements, it appears that these systems are liquid at room temperature for a lithium salt mole fraction ranging from 0.10 to 0.35. The temperature dependences of the ionic conductivity and the viscosity of these DESs are correctly described by using the Vogel-Tammann-Fulcher (VTF) type fitting equation, due to the strong interactions between Li(+), X(-) and MAc in solution. Furthermore, these electrolytes possess quite large electrochemical stability windows up to 4.7-5 V on Pt, and demonstrate also a passivating behavior toward the aluminum collector at room temperature. Based on these interesting electrochemical properties, these selected DESs can be classified as potential and promising electrolytes for lithium-ion batteries (LIBs). For this purpose, a test cell was then constructed and tested at 25 ░C, 60 ░C and 80 ░C by using each selected DES as an electrolyte and LiFePO4 (LFP) material as a cathode. The results show a good compatibility between each DES and LFP electrode material. A capacity of up to 160 mA h g(-1) with a good efficiency (99%) is observed in the DES based on the LiNO3 salt at 60 ░C despite the presence of residual water in the electrolyte. Finally preliminary tests using a LFP/DES/LTO (lithium titanate) full cell at room temperature clearly show that LiTFSI-based DES can be successfully introduced into LIBs. Considering the beneficial properties, especially, the cost of these electrolytes, such introduction could represent an important contribution for the realization of safer and environmentally friendly LIBs. PMID:24153449
Magnetic graphene oxide modified with choline chloride-based deep eutectic solvent for the solid-phase extraction of protein.
Huang, Yanhua; Wang, Yuzhi; Pan, Qi; Wang, Ying; Ding, Xueqin; Xu, Kaijia; Li, Na; Wen, Qian
Four kinds of green deep eutectic solvents (DESs) based on choline chloride (ChCl) have been synthesized and coated on the surface of magnetic graphene oxide (Fe3O4@GO) to form Fe3O4@GO-DES for the magnetic solid-phase extraction of protein. X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FESEM) and thermal gravimetric analysis (TGA) were employed to characterize Fe3O4@GO-DES, and the results indicated the successful preparation of Fe3O4@GO-DES. The UV-vis spectrophotometer was used to measure the concentration of protein after extraction. Single factor experiments proved that the extraction amount was influenced by the types of DESs, solution temperature, solution ionic strength, extraction time, protein concentration and the amount of Fe3O4@GO-DES. Comparison of Fe3O4@GO and Fe3O4@GO-DES was carried out by extracting bovine serum albumin, ovalbumin, bovine hemoglobin and lysozyme. The experimental results showed that the proposed Fe3O4@GO-DES performs better than Fe3O4@GO in the extraction of acidic protein. Desorption of protein was carried out by eluting the solid extractant with 0.005molL(-1) Na2HPO4 contained 1molL(-1) NaCl. The obtained elution efficiency was about 90.9%. Attributed to the convenient magnetic separation, the solid extractant could be easily recycled. PMID:26002214
Molecular and ionic diffusion in aqueous - deep eutectic solvent mixtures: probing inter-molecular interactions using PFG NMR.
D'Agostino, Carmine; Gladden, Lynn F; Mantle, Mick D; Abbott, Andrew P; Ahmed, Essa I; Al-Murshedi, Azhar Y M; Harris, Robert C
Pulsed field gradient (PFG) NMR has been used to probe self-diffusion of molecular and ionic species in aqueous mixtures of choline chloride (ChCl) based deep eutectic solvents (DESs), in order to elucidate the effect of water on motion and inter-molecular interactions between the different species in the mixtures, namely the Ch(+) cation and hydrogen bond donor (HBD). The results reveal an interesting and complex behaviour of such mixtures at a molecular level. In general, it is observed that the hydroxyl protons ((1)H) of Ch(+) and the hydrogen bond donor have diffusion coefficients significantly different from those measured for their parent molecules when water is added. This indicates a clear and significant change in inter-molecular interactions. In aqueous Ethaline, the hydroxyl species of Ch(+) and HBD show a stronger interaction with water as water is added to the system. In the case of Glyceline, water has little effect on both hydroxyl proton diffusion of Ch(+) and HBD. In Reline, it is likely that water allows the formation of small amounts of ammonium hydroxide. The most surprising observation is from the self-diffusion of water, which is considerably higher that expected from a homogeneous liquid. This leads to the conclusion that Reline and Glyceline form mixtures that are inhomogeneous at a microscopic level despite the hydrophilicity of the salt and HBD. This work shows that PFG NMR is a powerful tool to elucidate both molecular dynamics and inter-molecular interactions in complex liquid mixtures, such as the aqueous DES mixtures. PMID:25994171
Ionic liquid and deep eutectic solvent-activated CelA2 variants generated by directed evolution.
Lehmann, Christian; Bocola, Marco; Streit, Wolfgang R; Martinez, Ronny; Schwaneberg, Ulrich
Chemoenzymatic cellulose degradation is one of the key steps for the production of biomass-based fuels under mild conditions. An effective cellulose degradation process requires diverse physico-chemical dissolution of the biomass prior to enzymatic degradation. In recent years, "green" solvents, such as ionic liquids and, more recently, deep eutectic liquids, have been proposed as suitable alternatives for biomass dissolution by homogenous catalysis. In this manuscript, a directed evolution campaign of an ionic liquid tolerant ?-1,4-endoglucanase (CelA2) was performed in order to increase its performance in the presence of choline chloride/glycerol (ChCl:Gly) or 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), as a first step to identify residues which govern ionic strength resistance and obtaining insights for employing cellulases on the long run in homogenous catalysis of lignocellulose degradation. After mutant library screening, variant M4 (His288Phe, Ser300Arg) was identified, showing a dramatically reduced activity in potassium phosphate buffer and an increased activity in the presence of ChCl:Gly or [BMIM]Cl. Further characterization showed that the CelA2 variant M4 is activated in the presence of these solvents, representing a first report of an engineered enzyme with an ionic strength activity switch. Structural analysis revealed that Arg300 could be a key residue for the ionic strength activation through a salt bridge with the neighboring Asp287. Experimental and computational results suggest that the salt bridge Asp287-Arg300 generates a nearly inactive CelA2 variant and activity is regained when ChCl:Gly or [BMIM]Cl are supplemented (~5-fold increase from 0.64 to 3.37 ?M 4-MU/h with the addition ChCl:Gly and ~23-fold increase from 3.84 to 89.21 ?M 4-pNP/h with the addition of [BMIM]Cl). Molecular dynamic simulations further suggest that the salt bridge between Asp287 and Arg300 in variant M4 (His288Phe, Ser300Arg) modulates the observed salt activation. PMID:24802079
Ionothermal synthesis of a three-dimensional zinc phosphate with DFT topology using unstable deep-eutectic solvent as template-delivery agent
Lei Liu; Ying Kong; Hong Xu; Jin P. Li; Jin X. Dong; Zhi Lin
A three-dimensional zinc phosphate compound with DFT topology, designated as ZnPO4-EU1, has been synthesized by an ionothermal approach from the system HF-ZnO¢P2O5-choline chloride-imidazolidone. Ethylenediamine, derived from decomposition of the imidazolidone component of the deep-eutectic solvent (DES) itself, is delivered to the synthesis and serves as an appropriate template for ZnPO4-EU1. Experiments in which the synthesis conditions were varied showed that
Density relaxation and particle motion characteristics in a non-ionic deep eutectic solvent (acetamide + urea): time-resolved fluorescence measurements and all-atom molecular dynamics simulations.
Das, Anuradha; Das, Suman; Biswas, Ranjit
Temperature dependent relaxation dynamics, particle motion characteristics, and heterogeneity aspects of deep eutectic solvents (DESs) made of acetamide (CH3CONH2) and urea (NH2CONH2) have been investigated by employing time-resolved fluorescence measurements and all-atom molecular dynamics simulations. Three different compositions (f) for the mixture [fCH3CONH2 + (1 - f)NH2CONH2] have been studied in a temperature range of 328-353 K which is ?120-145 K above the measured glass transition temperatures (?207 K) of these DESs but much lower than the individual melting temperature of either of the constituents. Steady state fluorescence emission measurements using probe solutes with sharply different lifetimes do not indicate any dependence on excitation wavelength in these metastable molten systems. Time-resolved fluorescence anisotropy measurements reveal near-hydrodynamic coupling between medium viscosity and rotation of a dissolved dipolar solute. Stokes shift dynamics have been found to be too fast to be detected by the time-resolution (?70 ps) employed, suggesting extremely rapid medium polarization relaxation. All-atom simulations reveal Gaussian distribution for particle displacements and van Hove correlations, and significant overlap between non-Gaussian (?2) and new non-Gaussian (?) heterogeneity parameters. In addition, no stretched exponential relaxations have been detected in the simulated wavenumber dependent acetamide dynamic structure factors. All these results are in sharp contrast to earlier observations for ionic deep eutectics with acetamide [Guchhait et al., J. Chem. Phys. 140, 104514 (2014)] and suggest a fundamental difference in interaction and dynamics between ionic and non-ionic deep eutectic solvent systems. PMID:25612718
Density relaxation and particle motion characteristics in a non-ionic deep eutectic solvent (acetamide + urea): Time-resolved fluorescence measurements and all-atom molecular dynamics simulations
NASA Astrophysics Data System (ADS)
Das, Anuradha; Das, Suman; Biswas, Ranjit
Temperature dependent relaxation dynamics, particle motion characteristics, and heterogeneity aspects of deep eutectic solvents (DESs) made of acetamide (CH3CONH2) and urea (NH2CONH2) have been investigated by employing time-resolved fluorescence measurements and all-atom molecular dynamics simulations. Three different compositions (f) for the mixture [fCH3CONH2 + (1 - f)NH2CONH2] have been studied in a temperature range of 328-353 K which is ś120-145 K above the measured glass transition temperatures (ś207 K) of these DESs but much lower than the individual melting temperature of either of the constituents. Steady state fluorescence emission measurements using probe solutes with sharply different lifetimes do not indicate any dependence on excitation wavelength in these metastable molten systems. Time-resolved fluorescence anisotropy measurements reveal near-hydrodynamic coupling between medium viscosity and rotation of a dissolved dipolar solute. Stokes shift dynamics have been found to be too fast to be detected by the time-resolution (ś70 ps) employed, suggesting extremely rapid medium polarization relaxation. All-atom simulations reveal Gaussian distribution for particle displacements and van Hove correlations, and significant overlap between non-Gaussian (?2) and new non-Gaussian (?) heterogeneity parameters. In addition, no stretched exponential relaxations have been detected in the simulated wavenumber dependent acetamide dynamic structure factors. All these results are in sharp contrast to earlier observations for ionic deep eutectics with acetamide [Guchhait et al., J. Chem. Phys. 140, 104514 (2014)] and suggest a fundamental difference in interaction and dynamics between ionic and non-ionic deep eutectic solvent systems.
Separation of the isomers of benzene poly(carboxylic acid)s by quaternary ammonium salt via formation of deep eutectic solvents.
Hou, Yucui; Li, Jian; Ren, Shuhang; Niu, Muge; Wu, Weize
Because of similar properties and very low volatility, isomers of benzene poly(carboxylic acid)s (BPCAs) are very difficult to separate. In this work, we found that isomers of BPCAs could be separated efficiently by quaternary ammonium salts (QASs) via formation of deep eutectic solvents (DESs). Three kinds of QASs were used to separate the isomers of BPCAs, including the isomers of benzene tricarboxylic acids (trimellitic acid, trimesic acid, and hemimellitic acid) and the isomers of benzene dicarboxylic acids (phthalic acid and isophthalic acid). Among the QASs, tetraethylammonium chloride was found to have the best performance, which could completely separate BPCA isomers in methyl ethyl ketone solutions. It was found that the hydrogen bond forming between QAS and BPCA results in the selective separation of BPCA isomers. QAS in DES was regenerated effectively by the antisolvent method, and the regenerated QAS was reused four times with the same high efficiency. PMID:25351281
Introducing deep eutectic solvents to polar organometallic chemistry: chemoselective addition of organolithium and Grignard reagents to ketones in air.
Vidal, Cristian; GarcĒa-┴lvarez, JoaquĒn; Hernßn-G¾mez, Alberto; Kennedy, Alan R; Hevia, Eva
Despite their enormous synthetic relevance, the use of polar organolithium and Grignard reagents is greatly limited by their requirements of low temperatures in order to control their reactivity as well as the need of dry organic solvents and inert atmosphere protocols to avoid their fast decomposition. Breaking new ground on the applications of these commodity organometallics in synthesis under more environmentally friendly conditions, this work introduces deep eutetic solvents (DESs) as a green alternative media to carry out chemoselective additions of ketones in air at room temperature. Comparing their reactivities in DES with those observed in pure water suggest that a kinetic activation of the alkylating reagents is taking place, favoring nucleophilic addition over the competitive hydrolysis, which can be rationalized through formation of halide-rich magnesiate or lithiate species. PMID:24771680
Electrochemical synthesis of copper nanoparticles using cuprous oxide as a precursor in choline chloride-urea deep eutectic solvent: nucleation and growth mechanism.
Zhang, Q B; Hua, Y X
The electrochemical nucleation and growth kinetics of copper nanoparticles on a Ni electrode have been studied with cyclic voltammetry and chronoamperometry in the choline chloride (ChCl)-urea based deep eutectic solvent (DES). The copper source was introduced into the solvent by the dissolution of Cu(I) oxide (Cu2O). Cyclic voltammetry indicates that the electroreduction of Cu(I) species in the DES is a diffusion-controlled quasi-reversible process. The analysis of the chronoamperometric transient behavior during electrodeposition suggests that the deposition of copper on the Ni electrode at low temperatures follows a progressive nucleation and three-dimensional growth controlled by diffusion. The effect of temperature on the diffusion coefficient of Cu(I) species that is present in the solvent and electron transfer rate constant obeys the Arrhenius law, according to which the activation energies are estimated to be 49.20 and 21.72 kJ mol(-1), respectively. The initial stage of morphological study demonstrates that both electrode potential and temperature play important roles in controlling the nucleation and growth kinetics of the nanocrystals during the electrodeposition process. Electrode potential is observed to affect mainly the nucleation process, whereas temperature makes a major contribution to the growth process. PMID:25387166
Ionothermal synthesis of two oxalate-bridged lanthanide(III) chains with slow magnetization relaxation by using a deep eutectic solvent.
Meng, Yan; Liu, Jun-Liang; Zhang, Ze-Min; Lin, Wei-Quan; Lin, Zhuo-Jia; Tong, Ming-Liang
Two novel isostructural oxalate-bridged lanthanide(III) chains, (choline)[Ln(ox)(H2O)3Cl]ClĘH2O (Ln = Dy/Er), were first obtained ionothermally by using a choline chloride-oxalic acid eutectic mixture as both solvent and structure-directing agent, both of which show field-induced slow relaxation of magnetization. PMID:23903323
Introducing deep eutectic solvents as biorenewable media for Au(I)-catalysed cycloisomerisation of ?-alkynoic acids: an unprecedented catalytic system.
RodrĒguez-┴lvarez, MarĒa J; Vidal, Cristian; DĒez, Josefina; GarcĒa-┴lvarez, JoaquĒn
Cycloisomerisation of ?-alkynoic acids into cyclic enol-lactones was conveniently performed, for the first time, in the eutectic mixture 1ChCl/2Urea under standard bench experimental conditions (at room temperature, under air and in the absence of co-catalysts) by using a new iminophosphorane-Au(I) complex as the catalyst. Furthermore, the catalytic system could be recycled up to four runs. PMID:25215857
Unexpected lateral-lithiation-induced alkylative ring opening of tetrahydrofurans in deep eutectic solvents: synthesis of functionalised primary alcohols.
Sassone, Francesca C; Perna, Filippo M; Salomone, Antonio; Florio, Saverio; Capriati, Vito
o-Tolyl-substituted tetrahydrofurans undergo highly regioselective ring opening with the concomitant formation of new C-C bonds as the result of a lateral lithiation reaction. This reaction provides a new method for the synthesis of functionalised primary alcohols and can be run directly in protic eutectic mixtures as benign reaction media at 0 ░C and under air, competitively with protonolysis. PMID:25959580
Preparation of chlorocholine chloride/urea deep eutectic solvent-modified silica and an examination of the ion exchange properties of modified silica as a Lewis adduct.
Tang, Baokun; Park, Ha Eun; Row, Kyung Ho
Chlorocholine chloride/urea (ClChCl-urea), a deep eutectic solvent (DES), was applied successfully to the modification of silica. The resulting modified silica was characterized by Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller analysis, and elemental analysis. Based on the ClChCl-urea modification of silica, the ClChCl-urea-modified silica is a Lewis adduct with ion exchange properties, and ferulic acid was adsorbed on the ClChCl-urea-modified silica via an ion exchange process. The adsorbed percentage of ferulic acid increased with the increasing amount of modified silica, and a high adsorbed percentage of 89% could be obtained by the ion exchange process. The Freundlich isotherm used to describe the adsorption of ferulic acid on the modified silica by ion exchange showed a good correlation (R(2) = 0.93). Based on the characterization of the structure and the analysis of the ion exchange property of the ClChCl-urea-modified silica, the modified silica as a potential medium can be applied in some analytical technologies such as solid phase extraction, chromatography, and so on. PMID:24748453
Glass transition dynamics and conductivity scaling in ionic deep eutectic solvents: The case of (acetamide + lithium nitrate/sodium thiocyanate) melts.
Tripathy, Satya N; Wojnarowska, Zaneta; Knapik, Justyna; Shirota, Hideaki; Biswas, Ranjit; Paluch, Marian
A detailed investigation on the molecular dynamics of ionic deep eutectic solvents (acetamide + lithium nitrate/sodium thiocyanate) is reported. The study was carried out employing dielectric relaxation spectroscopy covering seven decades in frequency (10(-1)-10(6) Hz) and in a wide temperature range from 373 K down to 173 K, accessing the dynamic observables both in liquid and glassy state. The dielectric response of the ionic system has been presented in the dynamic window of modulus formalism to understand the conductivity relaxation and its possible connection to the origin of localized motion. Two secondary relaxation processes appear below glass transition temperature. Our findings provide suitable interpretation on the nature of secondary Johari-Goldstein process describing the ion translation and orientation of dipoles in a combined approach using Ngai's coupling model. A nearly constant loss feature is witnessed at shorter times/lower temperatures. We also discuss the ac conductivity scaling behavior using Summerfield approach and random free energy barrier model which establish the time-temperature superposition principle. These experimental observations have fundamental importance on theoretical elucidation of the conductivity relaxation and glass transition phenomena in molten ionic conductors. PMID:25978897
Tuning the gallium content of metal precursors for Cu(In,Ga)Se2 thin film solar cells by electrodeposition from a deep eutectic solvent.
Malaquias, JoŃo C; Regesch, David; Dale, Phillip J; Steichen, Marc
Controlling the Ga incorporation of Cu-In-Ga metal precursors for Cu(In,Ga)Se2 (CIGS) solar cells is one of the main challenges for low cost electrodeposition processes, mainly due to the difficulty in electrodepositing metallic Ga from aqueous electrolytes. In this work we use the deep eutectic solvent (DES) Choline Chloride?:?Urea (ChCl?:?U - 1?:?2) to efficiently codeposit In-Ga on Cu and Mo electrodes. We control the Ga/(Ga+In) (Ga/III) ratio of the films via the mass fluxes. The electrochemical behavior of ChCl?:?U containing GaCl3 and InCl3 is studied by rotating disk electrode cyclic voltammetry (CV) on Mo and Cu electrodes. CV revealed on both Mo and Cu electrodes that the electrochemical behavior of the ChCl?:?U-GaCl3-InCl3 system is the superposition of the individual In and Ga electrochemistry. On a Cu electrode the morphology, crystal structure and element distribution of the deposits were a function of the Ga/III ratio. We demonstrate the precise control of Ga incorporation over a large composition range from 0.1 ? Ga/III ? 0.9 and proved that ED from DES is a straightforward, robust and efficient process. First solar cells based on Mo/Cu/In-Ga metal stacks achieved efficiencies as high as 7.9% with a Voc of 520 mV. PMID:24382400
Glass transition dynamics and conductivity scaling in ionic deep eutectic solvents: The case of (acetamide + lithium nitrate/sodium thiocyanate) melts
NASA Astrophysics Data System (ADS)
Tripathy, Satya N.; Wojnarowska, Zaneta; Knapik, Justyna; Shirota, Hideaki; Biswas, Ranjit; Paluch, Marian
A detailed investigation on the molecular dynamics of ionic deep eutectic solvents (acetamide + lithium nitrate/sodium thiocyanate) is reported. The study was carried out employing dielectric relaxation spectroscopy covering seven decades in frequency (10-1-106 Hz) and in a wide temperature range from 373 K down to 173 K, accessing the dynamic observables both in liquid and glassy state. The dielectric response of the ionic system has been presented in the dynamic window of modulus formalism to understand the conductivity relaxation and its possible connection to the origin of localized motion. Two secondary relaxation processes appear below glass transition temperature. Our findings provide suitable interpretation on the nature of secondary Johari-Goldstein process describing the ion translation and orientation of dipoles in a combined approach using Ngai's coupling model. A nearly constant loss feature is witnessed at shorter times/lower temperatures. We also discuss the ac conductivity scaling behavior using Summerfield approach and random free energy barrier model which establish the time-temperature superposition principle. These experimental observations have fundamental importance on theoretical elucidation of the conductivity relaxation and glass transition phenomena in molten ionic conductors.
Molecular motion and ion diffusion in choline chloride based deep eutectic solvents studied by 1H pulsed field gradient NMR spectroscopy.
D'Agostino, Carmine; Harris, Robert C; Abbott, Andrew P; Gladden, Lynn F; Mantle, Mick D
Deep Eutectic Solvents (DESs) are a novel class of solvents with potential industrial applications in separation processes, chemical reactions, metal recovery and metal finishing processes such as electrodeposition and electropolishing. Macroscopic physical properties such as viscosity, conductivity, eutectic composition and surface tension are already available for several DESs, but the microscopic transport properties for this class of compounds are not well understood and the literature lacks experimental data that could give a better insight into the understanding of such properties. This paper presents the first pulsed field gradient nuclear magnetic resonance (PFG-NMR) study of DESs. Several choline chloride based DESs were chosen as experimental samples, each of them with a different associated hydrogen bond donor. The molecular equilibrium self-diffusion coefficient of both the choline cation and hydrogen bond donor was probed using a standard stimulated echo PFG-NMR pulse sequence. It is shown that the increasing temperature leads to a weaker interaction between the choline cation and the correspondent hydrogen bond donor. The self-diffusion coefficients of the samples obey an Arrhenius law temperature-dependence, with values of self-diffusivity in the range of [10(-10)-10(-13) m(2) s(-1)]. In addition, the results also highlight that the molecular structure of the hydrogen bond donor can greatly affect the mobility of the whole system. While for ethaline, glyceline and reline the choline cation diffuses slower than the associated hydrogen bond donor, reflecting the trend of molecular size and molecular weight, the opposite behaviour is observed for maline, in which the hydrogen bond donor, i.e. malonic acid, diffuses slower than the choline cation, with self-diffusion coefficients values of the order of 10(-13) m(2) s(-1) at room temperature, which are remarkably low values for a liquid. This is believed to be due to the formation of extensive dimer chains between malonic acid molecules, which restricts the mobility of the whole system at low temperature (<30 ░C), with malonic acid and choline chloride having almost identical diffusivity values. Diffusion and viscosity data were combined together to gain insights into the diffusion mechanism, which was found to be the same as for ionic liquids with discrete anions. PMID:22033601
Synthesis of monoclinic structured BiVO 4 spindly microtubes in deep eutectic solvent and their application for dye degradation
Wei Liu; Yaqin Yu; Lixin Cao; Ge Su; Xiaoyun Liu; Lan Zhang; Yonggang Wang
Monoclinic structured spindly bismuth vanadate microtubes were fabricated on a large scale by a simple ionothermal treatment in the environment-friendly green solvent of urea\\/choline chloride. The as-prepared samples were characterized by XRD, SEM, TEM, IR and their photocatalytic activity was evaluated by photocatalytic decolorization of rhodamine B aqueous solution under visible-light irradiation. As-obtained BiVO4 microtubes exhibit the spindly shape with
A novel digestion method based on a choline chloride-oxalic acid deep eutectic solvent for determining Cu, Fe, and Zn in fish samples.
Habibi, Emadaldin; Ghanemi, Kamal; Fallah-Mehrjardi, Mehdi; Dadolahi-Sohrab, Ali
A novel and efficient digestion method based on choline chloride-oxalic acid (ChCl-Ox) deep eutectic solvent (DES) was developed for flame atomic absorption spectrometry (FAAS) determination of Cu, Zn, and Fe in biological fish samples. Key parameters that influence analyte recovery were investigated and optimized, using the fish protein certified reference material (CRM, DORM-3) throughout the procedure. In this method, 100 mg of the sample was dissolved in ChCl-Ox (1:2, molar ratio) at 100░C for 45 min. Then, 5.0 mL HNO(3) (1.0 M) was added. After centrifugation, the supernatant solution was filtered, diluted to a known volume, and analyzed by FAAS. Under optimized conditions, an excellent agreement between the obtained results and the certified values was observed, using Student's t-test (P=0.05); the extraction recovery of the all elements was greater than 95.3%. The proposed method was successfully applied to the determination of analytes in different tissues (muscle, liver, and gills) having a broad concentration range in a marine fish sample. The reproducibility of the method was validated by analyzing all samples by our method in a different laboratory, using inductively coupled plasma optical emission spectrometry (ICP-OES). For comparison, a conventional acid digestion (CAD) method was also used for the determination of analytes in all studied samples. The simplicity of the proposed experimental procedure, high extraction efficiency, short analysis time, lack of concentrated acids and oxidizing agents, and the use of safe and inexpensive components demonstrate the high potential of ChCl-Ox (1:2) for routine trace metal analysis in biological samples. PMID:23327946
Dissolution of biological samples in deep eutectic solvents: an approach for extraction of polycyclic aromatic hydrocarbons followed by liquid chromatography-fluorescence detection.
Helalat-Nezhad, Zahra; Ghanemi, Kamal; Fallah-Mehrjardi, Mehdi
A novel sample preparation method based on the complete dissolution of marine biological samples in choline chloride-oxalic acid (ChCl-Ox) deep eutectic solvent was developed for fast and efficient extraction of eight polycyclic aromatic hydrocarbons (PAHs) using minimum volumes of cyclohexane. The extracted PAHs were purified and then measured by high-performance liquid chromatography-fluorescence detection (HPLC-FL). The effect of key parameters on extraction recoveries and precision was investigated. At optimized conditions, the studied samples were dissolved under atmospheric pressure in ChCl-Ox (1:2) at 55░C for 30min, which is considerably lower than the temperature used in the classical and current methods. After dissolution, it took approximately 20min to quantitatively extract the PAHs from ChCl-Ox using 5mL cyclohexane. Depending on the analyte, the developed method was linear over the calibration range 1.0-250, 2.0-250, and 5.0-250ngg(-1), with r(2)>0.996. The detection limits of the method were between 0.50 and 3.08ngg(-1). The intra-day and inter-day precisions (based on the relative standard deviation, n=5) of the spiked PAHs at a concentration level of 50ngg(-1) were better than 12.6% and 13.3%, respectively. Individual PAH recoveries from spiked marine fish and macroalgae samples were in the range of 71.6% to 109.6%. For comparison, the spiked samples were also subjected to the Soxhlet extraction method. The simplicity of the procedure, high extraction efficiency, short analysis time, and use of safe and inexpensive components suggest the proposed method has a high potential for utilization in routine trace PAH analysis in biological samples. PMID:25857544
Low-frequency collective dynamics in deep eutectic solvents of acetamide and electrolytes: a femtosecond Raman-induced Kerr effect spectroscopic study.
Biswas, Ranjit; Das, Anuradha; Shirota, Hideaki
In this study, we have investigated the ion concentration dependent collective dynamics in two series of deep eutectic solvent (DES) systems by femtosecond Raman-induced Kerr effect spectroscopy, as well as some physical properties, e.g., shear viscosity (?), density (?), and surface tension (?). The DES systems studied here are [0.75CH3CONH2 + 0.25{f?KSCN + (1 - f?)NaSCN}] and [0.78CH3CONH2 + 0.22{f?LiBr + (1 - f?)LiNO3}] with f = 0, 0.2, 0.4, 0.6, 0.8, and 1.0. ? of these DES systems shows near insensitivity to f, while ? shows a moderate dependence on f. Interestingly, ? exhibits a strong dependence on f. In the low-frequency Kerr spectra, obtained via the Fourier transform of the collected Kerr transients, a characteristic band at ?70 cm(-1) is clear in [0.78CH3CONH2 + 0.22{f?LiBr + (1 - f?)LiNO3}] DES especially at the larger f. The band is attributed to the intermolecular hydrogen bond of acetamide. Because of less depolarized Raman activities of intermolecular/interionic vibrational motions, which are mostly translational (collision-induced or interaction-induced) motions, of spherical ions, the intermolecular hydrogen-bonding band is clearly observed. In contrast, the intermolecular hydrogen-bonding band is buried in the other intermolecular/interionic vibrational motions, which includes translational and reorientational (librational) motions and their cross-terms, in [0.75CH3CONH2 + 0.25{f?KSCN + (1 - f?)NaSCN}] system. The first moment (M1) of the intermolecular/interionic vibrational band in these DES systems is much higher than that in typical neutral molecular liquids and shows a weak but contrasting dependence on the bulk parameter ??/?. The time constants for picosecond overdamped Kerr transients in both the DES systems, which are obtained on the basis of the analysis fitted by a triexponential function, are rather insensitive to f for both the DES systems, but all the three time constants (fast: ?1-3 ps; intermediate: ?7-20 ps; and slow: ?100 ps) are different between the [0.78CH3CONH2 + 0.22{f?LiBr + (1 - f?)LiNO3}] and [0.75CH3CONH2 + 0.25{f?KSCN + (1 - f?)NaSCN}] systems. These results indicate that the intermolecular/interionic interactions in DES systems is strongly influenced by the ionic species present in these DES systems. PMID:25296820
Eutectic solvents for the removal of residual palm oil-based biodiesel catalyst
K. Shahbaz; F. S. Mjalli; M. A. Hashim; I. M. Alnashef
The production of biodiesel through transesterification requires numerous purification steps to remove the unreacted components and unwanted products for the biodiesel grade to satisfy the international standard specifications EN 14214 and ASTM D6751. The residual catalyst (KOH) is one of those impurities which must be removed at the end of alkali-catalyzed transesterification reaction. In this work, nine Deep eutectic solvents
Structure Property Relationships in Imidazole-based Deep Eutectic Mixtures
NASA Astrophysics Data System (ADS)
Terheggen, Logan; Cosby, Tyler; Sangoro, Joshua
Deep eutectic mixtures of levulinic acid with a systematic series of imidazoles are measured by broadband dielectric spectroscopy, differential scanning calorimetry, and Fourier transform infrared spectroscopy to investigate the impact of steric interactions on charge transport and structural dynamics. An enhancement of dc conductivity is found in each of the imidazoles upon the addition of levulinic acid. However, the extent of increase is dependent upon the alkyl substitution on the imidazole ring. These results highlight the importance of molecular structure on hydrogen bonding and charge transport in deep eutectic mixtures.
A novel ammonium based eutectic solvent for the treatment of free fatty acid and synthesis of biodiesel fuel
A. Hayyan; M. A. Hashim; M. Hayyan; F. S. Mjalli; I. M. AlNashef
In this work, low grade crude palm oil (LGCPO) with high free fatty acids (FFA) content is introduced as a possible biodiesel production feedstock alternative. The pre-treatment of LGCPO was conducted using ammonium-based deep eutectic solvent which consisted of hydrogen bond donor (i.e. p-toluenesulfonic acid monohydrate) (PTSA) and salt (i.e. N,N-diethylenethanol ammonium chloride) as a novel recyclable catalyst (DEAC-DES). The
Charge Transport and Structural Dynamics in Deep Eutectic Mixtures
NASA Astrophysics Data System (ADS)
Cosby, Tyler; Holt, Adam; Terheggen, Logan; Griffin, Philip; Benson, Roberto; Sangoro, Joshua
Charge transport and structural dynamics in a series of imidazole and carboxylic acid-based deep eutectic mixtures are investigated by broadband dielectric spectroscopy, dynamic light scattering, 1H nuclear magnetic resonance spectroscopy, calorimetry, and Fourier transform infrared spectroscopy. It is found that the extended hydrogen-bonded networks characteristic of imidazoles are broken down upon addition of carboxylic acids, resulting in an increase in dc conductivity of the mixtures. These results are discussed within the framework of recent theories of hydrogen bonding and proton transport.
A novel phosphonium-based deep eutectic catalyst for biodiesel production from industrial low grade crude palm oil
Adeeb Hayyan; Mohd Ali Hashim; Farouq S. Mjalli; Maan Hayyan; Inas M. AlNashef
This study explores the possibility of producing low grade crude palm oil (LGCPO)-based biodiesel using a two-stage process in which a phosphonium-based deep eutectic solvent (P-DES) and an alkali are used as catalysts. The pre-treatment of LGCPO was conducted using a P-DES composed of a hydrogen bond donor (i.e. p-toluenesulfonic acid monohydrate) and a salt (i.e. allyltriphenylphosphonium bromide) as a
A simple, efficient and environmentally benign synthetic protocol for the synthesis of spirooxindoles using choline chloride-oxalic acid eutectic mixture as catalyst/solvent system.
Khandelwal, Sarita; Rajawat, Anshu; Tailor, Yogesh Kumar; Kumar, Mahendra
An efficient and environmentally benign domino protocol has been presented for the synthesis of structurally diverse spirooxindoles spiroannulated with pyranopyridopyrimidines, indenopyridopyrimidines, and chromenopyridopyrimidines involving three-component reaction of aminouracils, isatins and cyclic carbonyl compounds in deep eutectic solvent (choline chloride-oxalic acid: 1:1) which acts as efficient catalyst and environmentally benign reaction medium. The present protocol offers several advantages such as operational simplicity with easy workup, shorter reaction times excellent yields with superior atom economy and environmentally benign reaction conditions with the use of cost-effective, recyclable, non-toxic and bio-degradable DES as catalyst/solvent. PMID:25329839
New synthetic route of polyoxometalate-based hybrids in choline chloride\\/urea eutectic media
Shi-Ming Wang; Yun-Wu Li; Xiao-Jia Feng; Yang-Guang Li; En-Bo Wang
The deep eutectic solvents synthetic method was initially explored as a facile synthesis route to prepare new polyoxometalate (POM)-based hybrids. Such a method can not only avoid poor solubility, lower yields and the potential explosion, but also act as a new type of noxious, convenient and environmental friendly organic reagents. Using the choline chloride\\/urea eutectic mixture as the deep eutectic
Three new polyoxometalate-based hybrids prepared from choline chloride\\/urea deep eutectic mixture at room temperature
Shi-Ming Wang; Wei-Lin Chen; En-Bo Wang; Yang-Guang Li; Xiao-Jia Feng; Lin Liu
Three new polyoxometalate-based hybrids {[(CH3)3N(CH2)2OH]2(H3O)}[Na2(H2O)6][IMo6O24]ĘH2O 1 , {Na2[(CH3)3N(CH2)2OH]4}[Al(OH)6Mo6O18]2Ę8NH2CONH2Ę4H2O 2 and {Na6(H2O)18[(CH3)3N(CH2)2OH]2(CON2H5)2}[NaMo7O24]2Ę4NH2CONH2ĘH2O 3 were successfully synthesized in the choline chloride\\/urea deep eutectic mixture at room temperature. Reactant quantities of water presents in the nonaqueous eutectic mixture solvent may influence the structure of the products. The three compounds are fully characterized by elemental analyses, IR, UV¢vis, TG analyses, power X-ray diffraction and
Recycling of electric arc furnace dust through dissolution in deep eutectic ionic liquids and electrowinning.
Bakkar, Ashraf
The dust waste formed during steelmaking in electric arc furnace (EAF) is rich in ferrous and nonferrous metals. Recycling of this dust as a raw material in iron or steel-making is hazardous and therefore it is mostly dumped. This paper demonstrates recycling of EAF dust through selective dissolution of metal oxides in a deep eutectic ionic liquid. It was found that about 60% of Zn and 39% of Pb could be dissolved from the dust when stirred for 48h in 1 choline chloride:2 urea ionic liquid at 60░C. The resultant electrolyte was subsequently fed to a conventional three-electrode cell where cyclic voltammetry (CV) measurements were conducted to describe its electrochemical behavior. Two deposition peaks were determined and ascribed to deposition of zinc and lead. Static potentials were successively applied to electrowin metallic zinc. SEM/EDX investigations showed that the zinc electrowon contained remarkable contents of lead. PMID:25156719
Charge transport and structural dynamics in carboxylic-acid-based deep eutectic mixtures.
Griffin, Philip J; Cosby, Tyler; Holt, Adam P; Benson, Roberto S; Sangoro, Joshua R
Charge transport and structural dynamics in the 1:2 mol ratio mixture of lidocaine and decanoic acid (LID-DA), a model deep eutectic mixture (DEM), have been characterized over a wide temperature range using broad-band dielectric spectroscopy and depolarized dynamic light scattering. Additionally, Fourier transform infrared spectroscopy measurements were performed to assess the degree of proton transfer between the neutral parent molecules. From our detailed analysis of the dielectric spectra, we have determined that this carboxylic-acid-based DEM is approximately 25% ionic at room temperature. Furthermore, we have found that the characteristic diffusion rate of mobile charge carriers is practically identical to the rate of structural relaxation at all measured temperatures, indicating that fast proton transport does not occur in LID-DA. Our results demonstrate that while LID-DA exhibits the thermal characteristics of a DEM, its charge transport properties resemble those of a protic ionic liquid. PMID:25025600
High-performance dye-sensitized solar cells based on solvent-free electrolytes produced from eutectic melts
NASA Astrophysics Data System (ADS)
Bai, Yu; Cao, Yiming; Zhang, Jing; Wang, Mingkui; Li, Renzhi; Wang, Peng; Zakeeruddin, Shaik M.; Grõtzel, Michael
Low-cost excitonic solar cells based on organic optoelectronic materials are receiving an ever-increasing amount of attention as potential alternatives to traditional inorganic photovoltaic devices. In this rapidly developing field, the dye-sensitized solar cell (DSC) has achieved so far the highest validated efficiency of 11.1% (ref. 2) and remarkable stability. However, the cells with the best performance use volatile solvents in their electrolytes, which may be prohibitive for outdoor solar panels in view of the need for robust encapsulation. Solvent-free room-temperature ionic liquids have been pursued as an attractive solution to this dilemma, and device efficiencies of over 7% were achieved by using some low-viscosity formulations containing 1-ethyl-3-methylimidazolium thiocyanate, selenocyanate, tricyanomethide or tetracyanoborate. Unfortunately, apart from tetracyanoborate, all of these low-viscosity melts proved to be unstable under prolonged thermal stress and light soaking. Here, we introduce the concept of using eutectic melts to produce solvent-free liquid redox electrolytes. Using a ternary melt in conjunction with a nanocrystalline titania film and the amphiphilic heteroleptic ruthenium complex Z907Na (ref. 10) as a sensitizer, we reach excellent stability and an unprecedented efficiency of 8.2% under air-mass 1.5 global illumination. Our results are of importance to realize large-scale outdoor applications of mesoscopic DSCs.
Eutectic Salt Catalyzed Environmentally Benign and Highly Efficient Biginelli Reaction
Azizi, Najmadin; Dezfuli, Sahar; Hahsemi, Mohmmad Mahmoodi
A simple deep eutectic solvent based on tin (II) chloride was used as a dual catalyst and environmentally benign reaction medium for an efficient synthesis of 3,4-dihydropyrimidin-2(1H)-one derivatives, from aromatic and aliphatic aldehydes, 1,3-dicarbonyl compounds, and urea in good-to-excellent yields and short reaction time. This simple ammonium deep eutectic solvent, easily synthesized from choline chloride and tin chloride, is relatively inexpensive and recyclable, making it applicable for industrial applications. PMID:22649326
Deep Metastable Eutectic Nanometer-Scale Particles in the MgO-Al2O3-SiO2 System
NASA Technical Reports Server (NTRS)
Reitmeijer, Frans J. M.; Nash, J. A., III
Laboratory vapor phase condensation experiments systematically yield amorphous, homogeneous, nanoparticles with unique deep metastable eutectic compositions. They formed during the nucleation stage in rapidly cooling vapor systems. These nanoparticles evidence the complexity of the nucleation stage. Similar complex behavior may occur during the nucleation stage in quenched-melt laboratory experiments. Because of the bulk size of the quenched system many of such deep metastable eutectic nanodomains will anneal and adjust to local equilibrium but some will persist metastably depending on the time-temperature regime and melt/glass transformation.
Electrochemical double layer at the interfaces of Hg\\/choline chloride based solvents
Renata Costa; Marta Figueiredo; Carlos M. Pereira; Fernando Silva
The electrochemical interfaces of several deep eutectic solvents based on choline chloride mixtures with 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, urea or thiourea, and mixtures of acetylcholine chloride with urea were studied at a Hg electrode. The cyclic voltammetric results identified the potential domains of electrochemical stability and illustrated their dependence on the deep eutectic solvents composition. The differential capacitance¢potentials, C(E), curves for
The effect of additives on zinc electrodeposition from deep eutectic solvents
Andrew P. Abbott; John C. Barron; Gero Frisch; Karl S. Ryder; A. Fernando Silva
The electrodeposition of metals using ionic liquids has received considerable attention during the last ten years. Recent developments have taken these novel electrolytes from laboratory to commercial scale. One of the factors limiting the development into practical plating systems is the understanding of how brighteners function. In this study we describe the addition of three polar additives and their effect
Self-assembly of gold nanoparticles on deep eutectic solvent (DES) surfaces.
Raghuwanshi, V S; Ochmann, M; Polzer, F; Hoell, A; Rademann, K
Self-assembly of gold nanoparticles was obtained by sputter deposition on DES. SAXS and TEM investigations reveal the formation of spherical nanoparticles with a mean diameter of 5 ▒ 0.5 nm. For extended sputtering times, the number density of AuNPs increases linearly and a very pronounced 1st and 2nd shell ordering is observed. PMID:24957797
Electrodeposition of zinc¢tin alloys from deep eutectic solvents based on choline chloride
Andrew P. Abbott; Glen Capper; Katy J. McKenzie; Karl S. Ryder
Here we describe the electrolytic deposition of Zn, Sn and Zn\\/Sn alloys from a solution of the metal chloride salts separately in urea and ethylene glycol\\/choline chloride based ionic liquids. We show that the deposition kinetics and thermodynamics differ from the aqueous processes and that qualitatively different phases, compositions and morphologies are obtained for the metal coatings in the different
Fruit sugar-based deep eutectic solvents and their physical properties
A. Hayyan; F. S. Mjalli; I. M. Alnashef; T. Al-Wahaibi; Y. M. Al-Wahaibi; M. A. Hashim
In this study, a novel fructose-based DES of choline chloride (2-hydroxyethyl-trimethylammonium) has been synthesized at different molar ratios. The physical properties such as density, viscosity, surface tension, refractive index and pH were measured and analyzed as function of various temperatures (25-85░C). The analysis of these physical properties revealed that these new DESs have the potential to be utilized for possible
One-pot ?-nucleophilic fluorination of acetophenones in a deep eutectic solvent
Zizhan Chen; Wei Zhu; Zubiao Zheng; Xinzhuo Zou
Two methods of nucleophilic fluorination to prepare ?-fluoroacetophenones from ?-bromoacetophenones by using KF with PEG-400 or TBAF with ZnF2 are described. On the fundamental of nucleophilic fluorination, a novel method of one-pot fluorination to prepare ?-fluoroacetophenones directly from acetophenones in DES was developed.
Interaction and dynamics of (alkylamide + electrolyte) deep eutectics: Dependence on alkyl chain-length, temperature, and anion identity
NASA Astrophysics Data System (ADS)
Guchhait, Biswajit; Das, Suman; Daschakraborty, Snehasis; Biswas, Ranjit
Here we investigate the solute-medium interaction and solute-centered dynamics in (RCONH2 + LiX) deep eutectics (DEs) via carrying out time-resolved fluorescence measurements and all-atom molecular dynamics simulations at various temperatures. Alkylamides (RCONH2) considered are acetamide (CH3CONH2), propionamide (CH3CH2CONH2), and butyramide (CH3CH2CH2CONH2); the electrolytes (LiX) are lithium perchlorate (LiClO4), lithium bromide (LiBr), and lithium nitrate (LiNO3). Differential scanning calorimetric measurements reveal glass transition temperatures (Tg) of these DEs are ś195 K and show a very weak dependence on alkyl chain-length and electrolyte identity. Time-resolved and steady state fluorescence measurements with these DEs have been carried out at six-to-nine different temperatures that are ś100-150 K above their individual Tgs. Four different solute probes providing a good spread of fluorescence lifetimes have been employed in steady state measurements, revealing strong excitation wavelength dependence of probe fluorescence emission peak frequencies. Extent of this dependence, which shows sensitivity to anion identity, has been found to increase with increase of amide chain-length and decrease of probe lifetime. Time-resolved measurements reveal strong fractional power dependence of average rates for solute solvation and rotation with fraction power being relatively smaller (stronger viscosity decoupling) for DEs containing longer amide and larger (weaker decoupling) for DEs containing perchlorate anion. Representative all-atom molecular dynamics simulations of (CH3CONH2 + LiX) DEs at different temperatures reveal strongly stretched exponential relaxation of wavevector dependent acetamide self dynamic structure factor with time constants dependent both on ion identity and temperature, providing justification for explaining the fluorescence results in terms of temporal heterogeneity and amide clustering in these multi-component melts.
High-performance dye-sensitized solar cells based on solvent-free electrolytes produced from eutectic melts
Yu Bai; Yiming Cao; Jing Zhang; Mingkui Wang; Renzhi Li; Peng Wang; Shaik M. Zakeeruddin; Michael Grõtzel
Low-cost excitonic solar cells based on organic optoelectronic materials are receiving an ever-increasing amount of attention as potential alternatives to traditional inorganic photovoltaic devices. In this rapidly developing field, the dye-sensitized solar cell (DSC) has achieved so far the highest validated efficiency of 11.1% (ref. 2) and remarkable stability. However, the cells with the best performance use volatile solvents in
Toward advanced ionic liquids. Polar, enzyme-friendly solvents for biocatalysis
Johnathan Gorke; Friedrich Srienc; Romas Kazlauskas
Ionic liquids, also called molten salts, are mixtures of cations and anions that melt below 100░C. Typical ionic liquids are\\u000a dialkylimidazolium cations with weakly coordinating anions such as (MeOSO3) or (PF6). Advanced ionic liquids such as choline citrate have biodegradable, less expensive, and less toxic anions and cations. Deep\\u000a eutectic solvents are also included in the advanced ionic liquids. Deep
Catalytic dehydration of carbohydrates suspended in organic solvents promoted by AlCl3 /SiO2 coated with choline chloride.
Yang, Jie; De Oliveira Vigier, Karine; Gu, Yanlong; Jķr¶me, Franńois
We show that the coating of choline chloride on silica-supported AlCl3 allows the dehydration of carbohydrates to successfully proceed in low boiling point organic solvents. The concept is based on the in?situ formation of a deep eutectic liquid phase on the catalyst surface, thus facilitating the interaction between the solid catalyst and insoluble carbohydrate. PMID:25404114
NASA Technical Reports Server (NTRS)
Wilcox, W. R.
The objectives of this program are to determine the influence of convection on the microstructure of eutectics and to develop a technique for revealing the longitudinal microstructure of the MnBi-Bi eutectic. Both objectives aim at trying to explain the observed influence of space processing on the microstructure of MnBi-Bi. A computer program was developed and used to determine the concentration field in front of a growing lamellar eutectic. From this the deviation of the interfacial concentration from the eutectic composition was calculated as a function of eutectic composition, freezing rate, convection, and lamellar spacing.
Lamellar eutectic growth with anisotropic interphase boundaries
NASA Astrophysics Data System (ADS)
Akamatsu, S.; Bottin-Rousseau, S.; Faivre, G.; Ghosh, S.; Plapp, M.
We present a numerical study of the effect of a free-energy anisotropy of the solid- solid interphase boundaries on the formation of tilted lamellar microstructures during directional solidification of nonfaceted binary eutectic alloys. We used two different methods - phase-field (PF) and dynamic boundary-integral (BI) - to simulate the growth of periodic eutectic patterns in two dimensions. For a given Wulff plot of the interphase boundary, which characterizes a eutectic grain with a given relative orientation of the two solid phases, the lamellar tilt angle depends on the angle between the thermal axis z and a reference crystallographic axis. Both PF and BI results confirm the general validity of a recent approximate theory which assumes that, at the trijunctions, the surface tension vector of the interphase boundary is parallel to z. In particular, a crystallographic locking of the lamellae onto a direction close to a deep minimum in the Wulff plot is well reproduced in the simulations.
Directionally solidified ceramic eutectics
NASA Technical Reports Server (NTRS)
Ashbrook, R. L.
The aligned structures which result from the directional solidification (DS) of ceramic eutectics are of interest because of their potential for use in electronic devices and as structural materials. Techniques for growing DS ceramic eutectics are briefly discussed. The principles and controlling parameters of DS eutectic growth are described. The criteria for plane-front growth and the effect of growth rate on interlamellar or interfiber spacing are discussed. Examples of the effect of growth parameters on the alignment of the microstructure are given. Examples of the mechanical properties of directionally solidified oxide-oxide ceramics are also cited.
Low-transition-temperature mixtures (LTTMs): a new generation of designer solvents.
Francisco, MarĒa; van den Bruinhorst, Adriaan; Kroon, Maaike C
A new generation of designer solvents emerged in the last decade as promising green media for multiple applications, including separation processes: the low-transition-temperature mixtures (LTTMs). They can be prepared by mixing natural high-melting-point starting materials, which form a liquid by hydrogen-bond interactions. Among them, deep-eutectic solvents (DESs) were presented as promising alternatives to conventional ionic liquids (ILs). Some limitations of ILs are overcome by LTTMs, which are cheap and easy to prepare from natural and readily available starting materials, biodegradable, and renewable. PMID:23401138
Improving prediction of secondary structure, local backbone angles, and solvent accessible surface area of proteins by iterative deep learning.
Heffernan, Rhys; Paliwal, Kuldip; Lyons, James; Dehzangi, Abdollah; Sharma, Alok; Wang, Jihua; Sattar, Abdul; Yang, Yuedong; Zhou, Yaoqi
Direct prediction of protein structure from sequence is a challenging problem. An effective approach is to break it up into independent sub-problems. These sub-problems such as prediction of protein secondary structure can then be solved independently. In a previous study, we found that an iterative use of predicted secondary structure and backbone torsion angles can further improve secondary structure and torsion angle prediction. In this study, we expand the iterative features to include solvent accessible surface area and backbone angles and dihedrals based on C? atoms. By using a deep learning neural network in three iterations, we achieved 82% accuracy for secondary structure prediction, 0.76 for the correlation coefficient between predicted and actual solvent accessible surface area, 19░ and 30░ for mean absolute errors of backbone ? and ? angles, respectively, and 8░ and 32░ for mean absolute errors of C?-based ? and ? angles, respectively, for an independent test dataset of 1199 proteins. The accuracy of the method is slightly lower for 72 CASP 11 targets but much higher than those of model structures from current state-of-the-art techniques. This suggests the potentially beneficial use of these predicted properties for model assessment and ranking. PMID:26098304
Improving prediction of secondary structure, local backbone angles, and solvent accessible surface area of proteins by iterative deep learning
Heffernan, Rhys; Paliwal, Kuldip; Lyons, James; Dehzangi, Abdollah; Sharma, Alok; Wang, Jihua; Sattar, Abdul; Yang, Yuedong; Zhou, Yaoqi
Direct prediction of protein structure from sequence is a challenging problem. An effective approach is to break it up into independent sub-problems. These sub-problems such as prediction of protein secondary structure can then be solved independently. In a previous study, we found that an iterative use of predicted secondary structure and backbone torsion angles can further improve secondary structure and torsion angle prediction. In this study, we expand the iterative features to include solvent accessible surface area and backbone angles and dihedrals based on C? atoms. By using a deep learning neural network in three iterations, we achieved 82% accuracy for secondary structure prediction, 0.76 for the correlation coefficient between predicted and actual solvent accessible surface area, 19░ and 30░ for mean absolute errors of backbone ? and ? angles, respectively, and 8░ and 32░ for mean absolute errors of C?-based ? and ? angles, respectively, for an independent test dataset of 1199 proteins. The accuracy of the method is slightly lower for 72 CASP 11 targets but much higher than those of model structures from current state-of-the-art techniques. This suggests the potentially beneficial use of these predicted properties for model assessment and ranking. PMID:26098304
NASA Technical Reports Server (NTRS)
Wilcox, W. R.; Eisa, G. F.; Baskaran, V.; Richardson, D. C.
A theory was developed for the influence of convection on the microstructure of lamellar eutectics. Convection is predicted to produce a coarser microstructure, especially at low freezing rates and large volume fractions of the minority phase. Similary convection is predicted to lower the interfacial undercooling, especially at low freezing rates. Experiments using spin-up/spin-down were performed on the Mn-Bi eutectic. This stirring had a dramatic effect on the microstructure, not only making it coarser but at low freezing rates also changing the morphology of the MnBi. The coarsering persisted to moderately high freezing rates. At the lowest freezing rate, vigorous stirring caused the MnBi to be concentrated at the periphery of the ingot and absent along the center. Progress was made on developing a technique for revealing the three-dimensional microstructure of the MnBi eutectic by time-lapse videotaping while etching.
Using deep eutectic solvents based on methyl triphenyl phosphunium bromide for the removal of glycerol from palm-oil-based biodiesel
K. Shahbaz; F. S. Mjalli; M. A. Hashim; I. M. AlNashef
Biodiesel is a remarkable alternative to the decreasing resources for fossil fuels. One of the critical steps in producing biodiesel is its purification from the byproduct glycerol. The content of glycerol permissible must pass the EN 14214 and ASTM D6751 international biodiesel standards. In this work, methyl triphenyl phosphunium bromide as salt and three different hydrogen-bond donors, namely, glycerol, ethylene
Elimination of All Free Glycerol and Reduction of Total Glycerol from Palm Oil-Based Biodiesel Using Non-Glycerol Based Deep Eutectic Solvents
K. Shahbaz; F. S. Mjalli; M. A. Hashim; I. M. AlNashef
Purification of biodiesel prior to utilizing it as an alternative fuel is an essential industrial practice. Low glycerol content is one of the important pointers needed for passing the EN 14214 and ASTM D6751 international biodiesel standards. In this study, choline chloride (ChCl) as salt and ethylene glycol and 2,2,2-Trifluoroacetamide as hydrogen bond donors (HBDs) were employed to synthesize two
NASA Technical Reports Server (NTRS)
Douglas, F. C.; Galasso, F. S.
Experimental work is reported which was directed toward obtaining interface shape control while a numerical thermal analysis program was being made operational. An experimental system was developed in which the solid-liquid interface in a directionally solidified aluminum-nickel eutectic could be made either concave to the melt or convex to the melt. This experimental system provides control over the solid-liquid interface shape and can be used to study the effect of such control on the microstructure. The SINDA thermal analysis program, obtained from Marshall Space Flight Center, was used to evaluate experimental directional solidification systems for the aluminum-nickel and the aluminum-copper eutectics. This program was applied to a three-dimensional ingot, and was used to calculate the thermal profiles in axisymmetric heat flow. The results show that solid-liquid interface shape control can be attained with physically realizable thermal configurations and the magnitudes of the required thermal inputs were indicated.
NASA Technical Reports Server (NTRS)
Douglas, F. C.; Galasso, S. F.
The investigations of directional solidification have indicated the necessity of establishing a secure foundation in earth-based laboratory processing in order to properly assess low-gravity processing. Emphasis was placed on evaluating the regularity of microstructure of the rod-like eutectic Al-Al3Ni obtained under different conditions of growth involving the parameters of thermal gradient, solidification rate, and interfacial curvature. In the case of Al-Al3Ni, where the Al3Ni phase appears as facets rods, solidification rate was determined to be a controlling parameter. Zone melting of thin eutectic films showed that for films of the order of 10 to 20 micrometers thick, the extra surface energy appears to act to stabilize a regular microstructure. The results suggest that the role of low-gravity as provided in space-laboratory processing of materials is to be sought in the possibility of generating a higher thermal gradient in the solidifying ingot for a given power input-output arrangement than can be obtained under normal one-g processes.
Structure-property relationships in eutectic composites
NASA Technical Reports Server (NTRS)
Hertzberg, R. W.
The preparation of a composite material of eutectic composition directly from the molten state is investigated. The manufacture of eutectic composites by unidirectional solidification is reviewed, and it is shown how two-phase composite structures of given relative volume fraction can be produced with a range of particle sizes. Crystallographic relationships and the thermal stability of interfaces in controlled eutectic structures are examined, the mechanical behavior of aligned eutectic microstructures is discussed, and characteristics of eutectic composites having mechanical properties of engineering significance are evaluated. Specific properties of the Ni-Nb eutectic alloy are reviewed to demonstrate the effect of structure control (through directional solidification) on the mechanical response of a eutectic composite. It is noted that unidirectionally solidified eutectic composites possess highly aligned and thermally stable microstructures and also exhibit excellent combinations of strength and ductility to very high temperature levels.
Directionally solidified eutectic ceramic oxides
Javier LLorca; Victor M. Orera
The processing, structure and properties (mechanical and functional) of directionally solidified eutectic ceramic oxides are reviewed with particular attention to the developments in the last 15 years. The article analyzes in detail the control of the microstructure from the processing variables, the recently gained knowledge on their microstructure (crystallographic orientation, interface structure, residual stresses, etc.), the microstructural and chemical stability
A numerical model for eutectic spacing selection in the CBr 4?C 2Cl 6 eutectic system
NASA Astrophysics Data System (ADS)
Liu, Jincheng; Elliott, R.
It is well established that the lamellar eutectic structure exhibits a limited range of spacings rather than a unique spacing during steady state growth at a constant growth velocity. The minimum observed spacing corresponds to the extremum spacing predicted by the Jackson and Hunt analysis of eutectic growth. However, the maximum observed spacing is much less than the maximum spacing predicted by their analysis. The assumption of a planar interface by Jackson and Hunt is relaxed in this paper and a numerical model is developed which uses the boundary element method and an iterative technique to obtain the solute distribution for a selfconsistent curved interface shape. The maximum selfconsistent spacing, for which a selfconsistent interface exists, is determined for several growth velocities. The maximum selfconsistent spacings calculated in this way show good agreement with the maximum spacings observed in the CBr 4?C 2Cl 6 eutectic system. The interface shape for the maximum selfconsistent spacings has a limiting slope which is far from vertical and the deepest point on the selfconsistent interface at the maximum spacing does not lie in a deep pocket.
New eutectic ionic liquids for lipase activation and enzymatic preparation of biodieselå
Zhao, Hua; Baker, Gary A.; Holmes, Shaletha
The enzymatic preparation of biodiesel has been hampered by the lack of suitable solvents with desirable properties such as high lipase compatibility, low cost, low viscosity, high biodegradability, and ease of product separation. Recent interest in using ionic liquids (ILs) as advanced reaction media has led to fast reaction rates and high yields in the enzymatic synthesis of biodiesel. However, conventional (i.e., cation¢anion paired) ILs based on imidazolium and other quaternary ammonium salts remain too expensive for wide application at industrial scales. In this study, we report on newly-synthesized eutectic ILs derived from choline acetate or choline chloride coupled with biocompatible hydrogen-bond donors, such as glycerol. These eutectic solvents have favorable properties including low viscosity, high biodegradability, and excellent compatibility with Novozym« 435, a commercial immobilized Candida antarctica lipase B. Furthermore, in a model biodiesel synthesis system, we demonstrate high reaction rates for the enzymatic transesterification of Miglyol« oil 812 with methanol, catalyzed by Novozym« 435 in choline acetate/glycerol (1 : 1.5 molar ratio). The high conversion (97%) of the triglyceride obtained within 3 h, under optimal conditions, suggests that these novel eutectic solvents warrant further exploration as potential media in the enzymatic production of biodiesel. PMID:21283901
J. D. Livingston
The addition of W, Ta, or Al to Co-rich Co-Si alloys suppresses the formation of Co3Si and produces stable eutectics between the Co2Si and the Co-rich solid-solution phase. The Co-Si-W and Co-Si-Ta alloys solidified as three-phase eutectics. The Co-Si-Al alloy solidified as a two-phase eutectic, but a third phase precipitated on cooling. Interesting morphological changes were produced by epitaxial precipitation
NASA Technical Reports Server (NTRS)
Winter, J. M., Jr.
Dendrite free eutectic mixture of Pb-Sb is expected to be superelastic material that can be used in formation of shaped charge liners for industrial explosive metal-forming processes and other applications.
Germanium nanowire growth below the eutectic temperature.
Kodambaka, S; Tersoff, J; Reuter, M C; Ross, F M
Nanowires are conventionally assumed to grow via the vapor-liquid-solid process, in which material from the vapor is incorporated into the growing nanowire via a liquid catalyst, commonly a low-melting point eutectic alloy. However, nanowires have been observed to grow below the eutectic temperature, and the state of the catalyst remains controversial. Using in situ microscopy, we showed that, for the classic Ge/Au system, nanowire growth can occur below the eutectic temperature with either liquid or solid catalysts at the same temperature. We found, unexpectedly, that the catalyst state depends on the growth pressure and thermal history. We suggest that these phenomena may be due to kinetic enrichment of the eutectic alloy composition and expect these results to be relevant for other nanowire systems. PMID:17478716
Eutectic Contact Inks for Solar Cells
NASA Technical Reports Server (NTRS)
Ross, B.
Low-resistance electrical contacts formed on solar cells by melting powders of eutectic composition of semiconductor and dopant. Process improves cell performance without subjecting cell to processing temperatures high enough to degrade other characteristics.
The promise of eutectics for aircraft turbines
NASA Technical Reports Server (NTRS)
Gray, H. R.
The current status of the first generation eutectics, gamma/gamma transition - delta and NiTaC-13, is described in detail. Several second generation systems, such as gamma/gamma transition - alpha and NiTaC 3-116A, gamma - beta, and COTAC 74 are also reviewed with particular emphasis on their critical physical and mechanical properties, future research directions, and potential applications. Results of recent cost-benefit analyses of eutectic turbine blades are discussed.
Eutectic experiment development for space processing
NASA Technical Reports Server (NTRS)
Hopkins, R. H.
A ground base test plan and a specimen evaluation scheme have been developed for the aluminum-copper eutectic solidification experiment to be run in the M518 multipurpose electric furnace during the Skylab mission. Besides thermal and solidification studies a detailed description is given of the quantitative metallographic technique which is appropriate for characterizing eutectic structures. This method should prove a key tool for evaluating specimen microstructure which is the most sensitive indicator of changes produced during solidification. It has been recommended that single grain pre-frozen eutectic specimens be used to simplify microstructural evaluation and to eliminate any porosity in the as-cast eutectic specimens. High purity (99.999%) materials from one supplier should be employed for all experiments. Laboratory studies indicate that porosity occurs in the MRC as-cast eutectic ingots but that this porosity can be eliminated by directional freezing. Chemical analysis shows that the MRC ingots are slightly Al rich and contain about .03% impurity. Because of the impurity content the lower cooldown rate (1.2 C/min) should be used for eutectic freezing if MRC material is used in the M518 furnace.
Enzymatic hybridization of ?-lipoic acid with bioactive compounds in ionic solvents.
Papadopoulou, Athena A; Katsoura, Maria H; Chatzikonstantinou, Alexandra; Kyriakou, Eleni; Polydera, Angeliki C; Tzakos, Andreas G; Stamatis, Haralambos
The lipase-catalyzed molecular hybridization of ?-lipoic acid (LA) with bioactive compounds pyridoxine, tyrosol and tyramine was performed in ionic solvents and deep eutectic solvents. The biocatalytic reactions were catalyzed by Candida antarctica lipase B immobilized onto various functionalized multi-walled carbon nanotubes (f-CNTs-CaLB), as well as by commercial Novozym 435. The use of f-CNTs-CaLB leads, in most cases, to higher conversion yields as compared to Novozym 435. The nature and ion composition of ionic solvents affect the performance of the biocatalytic process. The highest conversion yield was observed in (mtoa)NTf2. The high enzyme stability and the relatively low solubility of substrates in specific media account for the improved biocatalytic synthesis of molecular hybrids of LA. Principal component analysis was used to screen for potential lipoxygenase inhibitors. In vitro studies showed that the synthesized compounds exhibit up to 10-fold increased inhibitory activity on lipoxygenase mediated lipid peroxidation as compared to parent molecules. PMID:23567667
Modeling the glass forming ability of metals
Cheney, Justin Lee
strong solvent-solute clusters around deep eutectics in thesolvent-solute topological model suggests. Deep eutecticsdeep eutectic, among other criteria, is more critical. Furthermore, this study has revealed that the solvent-
Directionally solidified eutectic alloy gamma-beta
NASA Technical Reports Server (NTRS)
Tewari, S. N.
A pseudobinary eutectic alloy composition was determined by a previously developed bleed-out technique. The directionally solidified eutectic alloy with a composition of Ni-37.4Fe-10.0Cr-9.6Al (in wt%) had tensile strengths decreasing from 1,090 MPa at room temperature to 54 MPa at 1,100 C. The low density, excellent microstructural stability, and oxidation resistance of the alloy during thermal cycling suggest that it might have applicability as a gas turbine vane alloy while its relatively low high temperature strength precludes its use as a blade alloy. A zirconium addition increased the 750 C strength, and a tungsten addition was ineffective. The gamma=beta eutectic alloys appeared to obey a normal freezing relation.
Some physicochemical studies on organic eutectics
NASA Astrophysics Data System (ADS)
Gupta, R. K.; Singh, S. K.; Singh, R. A.
The phase diagrams of phenothiazine with each of m-nitrobenzoic acid ( m-NBA) and m-dinitrobenzene ( m-DNB) have been studied by thaw-melt method. These materials have been characterized by X-ray diffraction. Growth behavior of the parent components, eutectic and charge transfer complex (CTC) studied by measuring the rate of movement of the growth front in a capillary suggests the applicability of Hillig-Turnbull equation for the system. Microstructure and electrical conductivities of congruent melting complexes and eutectics have been determined. The low electrical conductivities of these materials have been due to weak interaction and mixed stacking of donor and acceptor. Excess thermodynamics functions of the charge-transfer (CT) materials and eutectics have been determined.
Eutectic growth under acoustic levitation conditions.
Xie, W J; Cao, C D; L³, Y J; Wei, B
Samples of Pb-Sn eutectic alloy with a high density of 8.5 x 10(3) kg/m(3) are levitated with a single-axis acoustic levitator, and containerlessly melted and then solidified in argon atmosphere. High undercoolings up to 38 K are obtained, which results in a microstructural transition of "lamellas-broken lamellas-dendrites." This transition is further investigated in the light of the coupled zone for eutectic growth and the effects of ultrasound. The breaking of regular eutectic lamellas and suppression of gravity-induced macrosegregation of (Pb) and (Sn) dendrites are explained by the complicated internal flow inside the levitated drop, which is jointly induced by the shape oscillation, bulk vibration and rotation of the levitated drop. The ultrasonic field is also found to drive forced surface vibration, which subsequently excites capillary ripples and catalyzes nucleation on the sample surface. PMID:12513291
Tin-silver-copper eutectic temperature and composition
M. E. Loomans; M. E. Fine
A careful investigation of the Sn-Ag-Cu phase diagram near the ternary eutectic composition was undertaken using annealed\\u000a alloys and differential scanning calorimetry to settle some uncertainties in the eutectic composition. The eutectic composition\\u000a was found to be 3.5 wt pct Ag, 0.9 wt pct Cu, and the balance Sn. The published eutectic temperature, 217 C, was confirmed.\\u000a A value of
Contact melting and the structure of binary eutectic near the eutectic point
Oleksiy Bystrenko; Valeriy Kartuzov
Computer simulations of contact melting and associated interfacial phenomena in binary eutectic systems were performed on the basis of the standard phase-field model with miscibility gap in solid state. It is shown that the model predicts the existence of equilibrium three-phase (solid-liquid-solid) states above the eutectic temperature, which suggest the explanation of the phenomenon of phase separation in liquid eutectic observed in experiments. The results of simulations provide the interpretation for the phenomena of contact melting and formation of diffusion zone observed in the experiments with binary metal-silicon systems.
Eutectic composite explosives containing ammonium nitrate
Stinecipher, M.M.
The eutectic of ammonium nitrate (AN), the ammonium salt of 3,5-dinitro-1,2,4-triazole was prepared and its sensitivity and performance were studied. It was found that this AN formulation was unusual in that it performed ideally at small diameter, which indicated that it was a monomolecular explosive. Sensitivity tests included type 12 impact, Henkin thermal and wedge tests, and performance tests included rate stick/plate dent, cylinder, and aquarium tests. Results were compared with calculations, standard explosives, and another eutectic, ethylendiamine dinitrate (EDD)/AN.
Microstructure Of MnBi/Bi Eutectic Alloy
NASA Technical Reports Server (NTRS)
Wilcox, William R.; Eisa, G. F.; Baskaran, B.; Richardson, Donald C.
Collection of three reports describes studies of directional solidification of MnBi/Bi eutectic alloy. Two of the reports, "Influence of Convection on Lamellar Spacing of Eutectics" and "Influence of Convection on Eutectic Microstructure," establish theoretical foundation for remaining document. Reports seek to quantify effect of convection on concentration field of growing lamellar eutectic. Remaining report, "Study of Eutectic Formation," begins by continuing theoretical developments. New technique under development by one of the authors helps to reveal three-dimensional microstructures of alloys.
Pb-free Sn-Ag-Cu ternary eutectic solder
Anderson, I.E.; Yost, F.G.; Smith, J.F.; Miller, C.M.; Terpstra, R.L.
A Pb-free solder includes a ternary eutectic composition consisting essentially of about 93.6 weight % Sn-about 4.7 weight % Ag-about 1.7 weight % Cu having a eutectic melting temperature of about 217 C and variants of the ternary composition wherein the relative concentrations of Sn, Ag, and Cu deviate from the ternary eutectic composition to provide a controlled melting temperature range (liquid-solid ``mushy`` zone) relative to the eutectic melting temperature (e.g. up to 15 C above the eutectic melting temperature). 5 figs.
Eutectic spacing and faults of directionally solidified Al¢Al 3Ni eutectic
Y. X. Zhuang; X. M. Zhang; L. H. Zhu; Z. Q. Hu
The Al¢Al3Ni eutectic was directionally solidified at a thermal gradient of 4.5K\\/mm in a vacuum Bridgman-type furnace in order to study eutectic spacing selection criterion. The microstructure was examined in transverse and longitudinal sections and the interrod spacings were measured at different growth velocity. It has been shown that the interrod spacing is not unique and displays a limited range
Not Available
The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated.
Investigation of a solvent polluted industrial site on a deep sandstone-mudstone sequence in the UK. Part 2. Contaminant sources, distributions, transport and retardation
NASA Astrophysics Data System (ADS)
Bishop, Philip Keith; Lerner, David Nicholas; Jakobsen, Rasmus; Gosk, Edmund; Burston, Mark William; Chen, Tong
A single industrial site has been investigated in detail to gain information on sources and movement of chlorinated hydrocarbon solvent (CHS) pollutants in groundwater under the industrialized city of Conventry in the UK. A soil gas survey identified the most polluted area of the site where two types of investigation borehole were drilled; open boreholes lined with plain and slotted casing, and a single dedicated borehole incorporating gas samplers and gas-driven water samplers. Specially designed sampling techniques using pumps and packers were employed to determine vertical pollution profiles in the open boreholes. Core material was collected for sorption and diffusion experiments. An assessment of field investigation procedures suggests that soil gas sampling is a useful method for reconnaissance surveying of pollution by volatile organic compounds, but the results reflect only shallow pollution in the vertical profile. Open boreholes were found not to be satisfactory for accurate groundwater profile sampling and dedicated boreholes are recommended for such studies. Many uncertainties are involved in such a study of solvent pollution owing to the limited number of boreholes drilled and the complex spatial and temporal variations of pollutants. Despite the limitations of the investigation, several useful conclusions are drawn concerning sources and movement of solvent pollution. The main pollution source at the site is identified as the solvent storage tanks and pollution has resulted from poor use practices. Vertical pollution profiles indicate that the downward migration of 1,1,1-trichloroethane is following that of trichloroethene, reflecting their history of use on the site. The overall quality of groundwater abstracted in the system is set to deteriorate, as high pollution loads, presently at shallow levels in the system penetrate deeper, little attenuated by sorption or degradation. Diffusion of pollutants between mobile fissure and immobile pore waters will result in poor quality groundwater under this site for the foreseeable future. This trend is expected to be reflected throughout the urban area as a whole, with most groundwaters falling below drinking water standards for CHSs.
Resolving Issues of Content Uniformity and Low Permeability Using Eutectic Blend of Camphor and Menthol
Gohel, M. C.; Nagori, S. A.
The aim of present study were to arrest the problem of content uniformity without the use of harmful organic solvent and to improve ex vivo permeability of captopril, a low dose class III drug as per biological classification system. Eutectic mixture of camphor and menthol was innovatively used in the work. Captopril solution in eutectic mixture was blended with Avicel PH 102 and then the mixture was blended with mannitol in different ratios. Formulated batches were characterized for angle of repose and Carr's index. A selected batch was filled in hard gelatin capsule. Tablet dosage form was also developed. Capsules and tablets were characterized for in vitro drug release in 0.1N HCl. Additionally, the captopril tablets were analyzed for content uniformity and ex vivo drug permeation study using rat ileum in modified apparatus. The measurement of angle of repose and Carr's index revealed that the powder blend exhibited good flow property and compressibility. The captopril capsules and tablets exhibited immediate drug release in 0.1 N HCl. The captopril tablets passed content uniformity test as per IP 1996. Ex vivo permeation of captopril, formulated with eutectic mixture, was faster than control. The permeation was increased by 15% at the end of 3 h. Tablets and capsule exhibited reasonable short term stability with no considerable change in performance characteristics. PMID:20376214
Expansion of solidified lead bismuth eutectic
NASA Astrophysics Data System (ADS)
Glasbrenner, H.; Gr÷schel, F.; Grimmer, H.; Patorski, J.; Rohde, M.
Lead bismuth eutectic (LBE) has been proposed both as spallation target and as coolant in a future accelerator driven system (ADS). Therefore this alloy should be fully characterised and its physical properties should be completely known before use. Experiments on the volumetric expansion of LBE were performed by variation of cooling rates, holding times and different starting temperatures of the melt. X-ray diffraction and optical metallurgical examination on LBE has been carried out in order to clarify the reasons for the volumetric expansion of LBE. Additionally thermal expansion of LBE solid was revealed. The results achieved will be discussed and at the end a model assumption will be given trying to explain the processes taking place to an ideal eutectic mixture.
Two-stage eutectic metal brushes
Hsu, John S (Oak Ridge, TN) [Oak Ridge, TN
A two-stage eutectic metal brush assembly having a slip ring rigidly coupled to a shaft, the slip ring being electrically coupled to first voltage polarity. At least one brush is rigidly coupled to a second ring and slidingly engaged to the slip ring. Eutectic metal at least partially fills an annulus between the second ring and a stationary ring. At least one conductor is rigidly coupled to the stationary ring and electrically coupled to a second voltage polarity. Electrical continuity is maintained between the first voltage polarity and the second voltage polarity. Periodic rotational motion is present between the stationary ring and the second ring. Periodic rotational motion is also present between the brush and the slip ring.
Use of eutectic mixtures for preparation of monolithic carbons with CO?-adsorption and gas-separation capabilities.
L¾pez-Salas, N; Jardim, E O; Silvestre-Albero, A; Gutiķrrez, M C; Ferrer, M L; RodrĒguez-Reinoso, F; Silvestre-Albero, J; del Monte, F
With global warming becoming one of the main problems our society is facing nowadays, there is an urgent demand to develop materials suitable for CO2 storage as well as for gas separation. Within this context, hierarchical porous structures are of great interest for in-flow applications because of the desirable combination of an extensive internal reactive surface along narrow nanopores with facile molecular transport through broad "highways" leading to and from these pores. Deep eutectic solvents (DESs) have been recently used in the synthesis of carbon monoliths exhibiting a bicontinuous porous structure composed of continuous macroporous channels and a continuous carbon network that contains a certain microporosity and provides considerable surface area. In this work, we have prepared two DESs for the preparation of two hierarchical carbon monoliths with different compositions (e.g., either nitrogen-doped or not) and structure. It is worth noting that DESs played a capital role in the synthesis of hierarchical carbon monoliths not only promoting the spinodal decomposition that governs the formation of the bicontinuous porous structure but also providing the precursors required to tailor the composition and the molecular sieve structure of the resulting carbons. We have studied the performance of these two carbons for CO2, N2, and CH4 adsorption in both monolithic and powdered form. We have also studied the selective adsorption of CO2 versus CH4 in equilibrium and dynamic conditions. We found that these materials combined a high CO2-sorption capacity besides an excellent CO2/N2 and CO2/CH4 selectivity and, interestingly, this performance was preserved when processed in both monolithic and powdered form. PMID:25255054
DNA-Based Asymmetric Catalysis: Role of Ionic Solvents and Glymes.
Zhao, Hua; Shen, Kai
Recently, DNA has been evaluated as a chiral scaffold for metal complexes to construct so called 'DNA-based hybrid catalysts', a robust and inexpensive alternative to enzymes. The unique chiral structure of DNA allows the hybrid catalysts to catalyze various asymmetric synthesis reactions. However, most current studies used aqueous buffers as solvents for these asymmetric reactions, where substrates/products are typically suspended in the solutions. The mass transfer limitation usually requires a long reaction time. To overcome this hurdle and to advance DNA-based asymmetric catalysis, we evaluated a series of ionic liquids (ILs), inorganic salts, deep eutectic solvents (DES), glymes, glycols, acetonitrile and methanol as co-solvents/additives for the DNA-based asymmetric Michael addition. In general, these additives induce indistinguishable changes to the DNA B-form duplex conformation as suggested by circular dichroism (CD) spectroscopy, but impose a significant influence on the catalytic efficiency of the DNA-based hybrid catalyst. Conventional organic solvents (e.g. acetonitrile and methanol) led to poor product yields and/or low enantioselectivities. Most ILs and inorganic salts cause the deactivation of the hybrid catalyst except 0.2 M [BMIM][CF3COO] (95.4% ee and 93% yield) and 0.2 M [BMIM]Cl (93.7% ee and 89% yield). Several other additives have also been found to improve the catalytic efficiency of the DNA-based hybrid catalyst (control reaction without additive gives >99% ee and 87% yield): 0.4 M glycerol (>99% ee and 96% yield at 5 ░C or 96.2% ee and 83% yield at room temperature), 0.2 M choline chloride/glycerol (1:2) (92.4% ee and 90% yield at 5 ░C or 94.0% ee and 88% yield at room temperature), and 0.5 M dipropylene glycol dimethyl ether (>99% ee and 87% yield at room temperature). The use of some co-solvents/additives allows the Michael addition to be performed at a higher temperature (e.g. room temperature vs 5 ░C) and a shorter reaction time (24 h vs 3 days). In addition, we found that a brief pre-sonication (5 min) of DNA in MOPS buffer prior to the reaction could improve the performance of the DNA-based hybrid catalyst. We have also shown that this DNA-based catalysis method is suitable for a variety of different substrates and relatively large-scale reactions. In conclusion, a judicious selection of benign co-solvents/additives could improve the catalytic efficiency of DNA-based hybrid catalyst. PMID:25386337
DNA¢Based Asymmetric Catalysis: Role of Ionic Solvents and Glymes
Zhao, Hua; Shen, Kai
Recently, DNA has been evaluated as a chiral scaffold for metal complexes to construct so called æDNA-based hybrid catalystsÆ, a robust and inexpensive alternative to enzymes. The unique chiral structure of DNA allows the hybrid catalysts to catalyze various asymmetric synthesis reactions. However, most current studies used aqueous buffers as solvents for these asymmetric reactions, where substrates/products are typically suspended in the solutions. The mass transfer limitation usually requires a long reaction time. To overcome this hurdle and to advance DNA-based asymmetric catalysis, we evaluated a series of ionic liquids (ILs), inorganic salts, deep eutectic solvents (DES), glymes, glycols, acetonitrile and methanol as co-solvents/additives for the DNA-based asymmetric Michael addition. In general, these additives induce indistinguishable changes to the DNA B-form duplex conformation as suggested by circular dichroism (CD) spectroscopy, but impose a significant influence on the catalytic efficiency of the DNA-based hybrid catalyst. Conventional organic solvents (e.g. acetonitrile and methanol) led to poor product yields and/or low enantioselectivities. Most ILs and inorganic salts cause the deactivation of the hybrid catalyst except 0.2 M [BMIM][CF3COO] (95.4% ee and 93% yield) and 0.2 M [BMIM]Cl (93.7% ee and 89% yield). Several other additives have also been found to improve the catalytic efficiency of the DNA-based hybrid catalyst (control reaction without additive gives >99% ee and 87% yield): 0.4 M glycerol (>99% ee and 96% yield at 5 ░C or 96.2% ee and 83% yield at room temperature), 0.2 M choline chloride/glycerol (1:2) (92.4% ee and 90% yield at 5 ░C or 94.0% ee and 88% yield at room temperature), and 0.5 M dipropylene glycol dimethyl ether (>99% ee and 87% yield at room temperature). The use of some co-solvents/additives allows the Michael addition to be performed at a higher temperature (e.g. room temperature vs 5 ░C) and a shorter reaction time (24 h vs 3 days). In addition, we found that a brief pre-sonication (5 min) of DNA in MOPS buffer prior to the reaction could improve the performance of the DNA-based hybrid catalyst. We have also shown that this DNA-based catalysis method is suitable for a variety of different substrates and relatively large-scale reactions. In conclusion, a judicious selection of benign co-solvents/additives could improve the catalytic efficiency of DNA-based hybrid catalyst. PMID:25386337
Solidification of eutectic system alloys in space (M-19)
NASA Technical Reports Server (NTRS)
Ohno, Atsumi
It is well known that in the liquid state eutectic alloys are theoretically homogeneous under 1 g conditions. However, the homogeneous solidified structure of this alloy is not obtained because thermal convection and non-equilibrium solidification occur. The present investigators have clarified the solidification mechanisms of the eutectic system alloys under 1 g conditions by using the in situ observation method; in particular, the primary crystals of the eutectic system alloys never nucleated in the liquid, but instead did so on the mold wall, and the crystals separated from the mold wall by fluid motion caused by thermal convection. They also found that the equiaxed eutectic grains (eutectic cells) are formed on the primary crystals. In this case, the leading phase of the eutectic must agree with the phase of the primary crystals. In space, no thermal convection occurs so that primary crystals should not move from the mold wall and should not appear inside the solidified structure. Therefore no equiaxed eutectic grains will be formed under microgravity conditions. Past space experiments concerning eutectic alloys were classified into two types of experiments: one with respect to the solidification mechanisms of the eutectic alloys and the other to the unidirectional solidification of this alloy. The former type of experiment has the problem that the solidified structures between microgravity and 1 g conditions show little difference. This is why the flight samples were prepared by the ordinary cast techniques on Earth. Therefore it is impossible to ascertain whether or not the nucleation and growth of primary crystals in the melt occur and if primary crystals influence the formation of the equiaxed eutectic grains. In this experiment, hypo- and hyper-eutectic aluminum copper alloys which are near eutectic point are used. The chemical compositions of the samples are Al-32.4mass%Cu (Hypo-eutectic) and Al-33.5mass%Cu (hyper-eutectic). Long rods for the samples are cast by the Ohno Continuous Casting Process and they show the unidirectionally solidified structure. Each flight and ground sample was made of these same rods. The dimensions of all samples are 4.5 mm in diameter and 23.5 mm in length. Each sample is put in a graphite capsule and then vacuum sealed in a double silica ampoule. Then the ampoule is put in the tantalum cartridge and sealed by electron beam welding. For onbard experiments, a Continuous Heating Furnance (CHF) will be used for melting and solidifying samples under microgravity conditions. Six flight samples will be used. Four samples are hypo-eutectic and two are hyper-eutectic alloys. The surface of the two hypo-eutectic alloy samples are covered with aluminum oxide film to prevent Marangoni convection expected under microgravity conditions. Each sample will be heated to 700 C and held at that temperature for 5 min. After that the samples will be allowed to cool to 500 C in the furnace and they will be taken out of the furnace for He gas cooling. The heating and cooling diagrams for the flight experiments are shown. After collecting the flight samples, the solidified structures of the samples will be examined and the mechanisms of eutectic solidification under microgravity conditions will be determined. It is likely that successful flight experiment results will lead to production of high quality eutectic alloys and eutectic composite materials in space.
Eutectic growth in unidirectionally solidified Fe-Cr-Ni alloy
Okane, Toshimitsu; Umeda, Takateru [Univ. of Tokyo (Japan)
In this report, transition of solidified phases for directionally solidified Fe-Cr-Ni alloys has been investigated in low growth rate range by using Bridgman type furnace. The ferritic-austenite eutectic growth has been confirmed like a plane front growth of ferrite single phase under low growth rate condition. The transition velocity between eutectic and ferrite cell growth has a good agreement with the result of calculation based on the phase selection criterion and the interface temperature calculation for ferrite, austenite and eutectic phases. These results show that the phase prediction by calculating interface temperature can be applied not only to competitive growth between single phases like peritectic systems, but also to eutectic systems. Furthermore, under the condition of eutectic coupled growth to be occurred in steady state, the changes of solidified phases and their morphologies in the initial transient are discussed.
Containerless solidification of acoustically levitated Ni-Sn eutectic alloy
NASA Astrophysics Data System (ADS)
Geng, D. L.; Xie, W. J.; Wei, B.
Containerless solidification of Ni-18.7at%Sn eutectic alloy has been achieved with a single-axis acoustic levitator. The temperature, motion, and oscillation of the sample were monitored by a high speed camera. The temperature of the sample can be determined from its image brightness, although the sample moves vertically and horizontally during levitation. The experimentally observed frequency of vertical motion is in good agreement with theoretical prediction. The sample undergoes shape oscillation before solidification finishes. The solidification microstructure of this alloy consists of a mixture of anomalous eutectic plus regular lamellar eutectic. This indicates the achievement of rapid solidification under acoustic levitation condition.
Eutectic propeties of primitive Earth's magma ocean
NASA Astrophysics Data System (ADS)
Lo Nigro, G.; Andrault, D.; Bolfan-Casanova, N.; Perillat, J.-P.
It is widely accepted that the early Earth was partially molten (if not completely) due to the high energy dissipated by terrestrial accretion [1]. After core formation, subsequent cooling of the magma ocean has led to fractional crystallization of the primitive mantle. The residual liquid corresponds to what is now called the fertile mantle or pyrolite. Melting relations of silicates have been extensively investigated using the multi-anvil press, for pressures between 3 and 25 GPa [2,3]. Using the quench technique, it has been shown that the pressure affects significantly the solidus and liquidus curves, and most probably the composition of the eutectic liquid. At higher pressures, up to 65 GPa, melting studies were performed on pyrolite starting material using the laser-heated diamond anvil cell (LH-DAC) technique [4]. However, the quench technique is not ideal to define melting criteria, and furthermore these studies were limited in pressure range of investigation. Finally, the use of pyrolite may not be relevant to study the melting eutectic temperature. At the core-mantle boundary conditions, melting temperature is documented by a single data point on (Mg,Fe)2SiO4 olivine, provided by shock wave experiments at around 130-140 GPa [5]. These previous results present large uncertainties of ~1000 K. The aim of this study is to determine the eutectic melting temperature in the chemically simplified system composed of the two major lower mantle phases, the MgSiO3 perovskite and MgO periclase. We investigated melting in-situ using the laser-heated diamond anvil cell coupled with angle dispersive X-ray diffraction at the ID27 beamline of the ESRF [6]. Melting relations were investigated in an extended P-T range comparable to those found in the Earth's lower mantle, i.e. from 25 to 120 GPa and up to more than 5000 K. Melting was evidenced from (a) disappearance of one of the two phases in the diffraction pattern, (b) drastic changes of the diffraction image itself, and/or (c) appearance of a broad band of diffuse X-ray scattering associated to the presence of silicate liquid. The pressure evolution of the eutectic temperature is found below the melting curve of pure MgSiO3 perovskite [7] for more than 500 K and also below the solidus curve of pyrolite [4] for 100-200 K at 60 GPa. References [1] B. T. Tonks, H. J. Melosh, Journal of Geophysical Research 98 5319 (1993). [2] Litasov, K., and Ohtani, E. Physics of The Earth and Planetary Interiors, 134(1-2), 105-127, (2002). [3] E. Ito, A. Kubo, T. Katsura et al., Phys. Earth Planet. Inter. 143-144 397 (2004). [4] A. Zerr, R. Boehler, Nature 506-508 (1994). [5] J. A. Akins, S. N. Luo, P. D. Asimov et al., Geophys. Res. Lett. 31 doi:10.1029/2004GL020237 (2004). [6] Schultz et al. International Journal of High Pressure Research. 25, 1, 71-83 (2005). [7] Zerr, A. and Boehler, R. Science, 262, 553-555 (1993).
Use of Microgravity to Control the Microstructure of Eutectics
NASA Technical Reports Server (NTRS)
Wilcox. William R.; Regel, Liya L.
This grant began in June of 1996. Its long term goal is to be able to control the microstructure of directionally solidified eutectic alloys, through an improved understanding of the influence of convection. The primary objective of the projects in the present grant is to test hypotheses for the reported influence of microgravity on the microstructure of eutectics. The prior experimental results on the influence of microgravity on the microstructure of eutectics have been contradictory. With lamellar eutectics, microgravity had a negligible effect on the microstructure. Microgravity experiments with fibrous eutectics sometimes showed a finer microstructure and sometimes a coarser microstructure. Most research has been done on the MnBi/Bi rod-like eutectic. Larson and Pirich obtained a two-fold finer microstructure both from microgravity and by use of a magnetic field to quench buoyancy-driven convection. Smith, on the other hand, observed no change in microgravity. Prior theoretical work at Clarkson University showed that buoyancy-driven convection in the vertical Bridgman configuration is not vigorous enough to alter the concentration field in front of a growing eutectic sufficiently to cause a measurable change in microstructure. We assumed that the bulk melt was at the eutectic composition and that freezing occurred at the extremum, i.e. with minimum total undercooling at the freezing interface. There have been four hypotheses attempting to explain the observed changes in microstructure of fibrous eutectics caused by convection: I .A fluctuating freezing rate, combined with unequal kinetics for fiber termination and branching. 2. Off-eutectic composition, either in the bulk melt due to an off-eutectic feed or at the freezing interface because of departure from the extremum condition. 3. Presence of a strong habit modifying impurity whose concentration at the freezing interface would be altered by convection. At the beginning of the present grant, we favored the first of these hypotheses and set out to test it both experimentally and theoretically. We planned the following approaches: I .Pass electric current pulses through the MnBi/Bi eutectic during directional solidification in order to produce an oscillatory freezing rate. 2. Directionally solidify the MnBi/Bi eutectic on Mir using the QUELD II gradient freeze furnace developed by Professor Smith at Queen's University. 3. Select another fibrous eutectic system for investigation using the Accelerated Crucible Rotation Technique to introduce convection. 4. Develop theoretical models for eutectic solidification with an oscillatory freezing rate. Because of the problems with Mir, we substituted ground-based experiments at Queen's University with QUELD II vertical and horizontal, with and without vibration of the furnace. The Al-Si system was chosen for the ACRT experiments. Three related approaches were used to model eutectic solidification with an oscillatory freezing rate. A sharp interface model was used to calculate composition oscillations at the freezing interface in response to imposed freezing rate oscillations.
Corrosion of ODS steels in lead¢bismuth eutectic
P. Hosemann; H. T. Thau; A. L. Johnson; S. A. Maloy; N. Li
Oxide dispersion strengthened (ODS) ferritic steels are advanced materials being developed for high temperature applications. Their properties (high temperature strength, creep resistance, corrosion\\/oxidation resistance) make them potentially usable for high temperature applications in liquid metal cooled systems like liquid lead¢bismuth eutectic cooled reactors and spallation sources. Corrosion tests on five different ODS alloys were performed in flowing liquid lead¢bismuth eutectic
Nanostructures from directionally solidified NiAl¢W eutectic alloys
Achim Walter Hassel; Andrew Jonathan Smith; Srdjan Milenkovic
A directionally solidified eutectic NiAl¢W alloy was employed as a source for NiAl nanopore arrays, W-nanowire arrays and W-nanowires. The NiAl¢W eutectic alloy containing 1.5at.% W. A growth rate of 30mmh?1 was used at a temperature gradient of 40Kcm?1 in a Bridgman-type directional solidification furnace. A combined stability diagram was derived from the Pourbaix diagrams of the three elements involved
Preparation of directionally solidified eutectics in some oxohalide systems
Chemekova, T.Yu.; Udalov, Yu.P.
Directionally solidified eutectics of systems formed by oxides and halides can be employed for developing materials with anisotropic properties. Preparation of directionally solidified eutectics by the method of zone melting with a heater submerged in the melt makes it possible to monitor visually the entire growth process. This method is apparently optimal, since it makes it possible to control the temperature gradient and the solidification rate over wide limits.
The microstructure of MnBi/Bi eutectic alloys
NASA Technical Reports Server (NTRS)
Ravishankar, P. S.; Wilcox, W. R.; Larson, D. J.
Directionally solidified eutectic alloys of the system MnBi/Bi have been investigated with reference to the dependence of the fiber spacing on the growth rate and the interfacial temperature gradient. It is found that the fiber spacing varies as the inverse square root of the growth rate and does not depend on the temperature gradient in contrast to the claims that all faceted/non-faceted eutectics should show a temperature gradient influence.
Regular rod-like eutectic spacing selection during directional solidified NiAl¢9Mo eutectic in situ composite
Jianfei Zhang; Jun Shen; Zhao Shang; Zhourong Feng; Lingshui Wang; Hengzhi Fu
NiAl¢9Mo (at%) eutectic alloy was produced by a Bridgman type crystal growing facility with Zone Melting Liquid Metal Cooling technique at the growth rate range from 60 to 200?m\\/s. The variation of rod eutectic spacing with growth rates was characterized. Statistical distributions of spacings at each growth rate were also determined. It was confirmed that the relationship between growth rate
Influence of convection on eutectic microstructure
NASA Technical Reports Server (NTRS)
Baskaran, V.; Eisa, G. F.; Wilcox, W. R.
When the MnBi-Bi eutectic is directionally solidified, it forms fibers of MnBi in a matrix of bismuth. When the material solidified in space at rates of 30 and 50 cm/hr, the average fiber spacing lambda was about one half of the value obtained in cases in which the same material solidified on earth. Neither an altered temperature gradient nor a fluctuating freezing rate are apparently responsible for the change in lambda, and the possibility is studied that natural convection increases lambda on earth by perturbing the compositional field in the melt ahead of the growing solid. A theoretical analysis is conducted along with some experiments. On the basis of the theoretical results for lamellar growth, it is concluded that the spacing lambda increases with increasing stirring, especially at small freezing rates. The experiments indicate that at low growth rates the cross-sectional area of the MnBi blades increases with increased stirring and with decreased growth rate.
Luminescence and scintillation properties of Ce dope SrHfO3 based eutectics
NASA Astrophysics Data System (ADS)
Kamada, Kei; Kurosawa, Shunsuke; Shoji, Yasuhiro; Pejchal, Jan; Ohashi, Yuji; Yokota, Yuui; Yoshikawa, Akira
Ce doped SrHfO3/SrAl12O19 eutectics were grown by the micro pulling down (?-PD) method and their directionally solidified eutectic system has been investigated. Investigations of obtained eutectic structure, luminescence and scintillation performances were also performed. Eutectics were grown at the speed of 0.60-0.90 mm/min. In the eutectics, Ce3+ 4f-5d emission was observed at 410 nm. The eutectics showed light yield of around 300 photon/5.5 meV alpha-ray by 241Am excitation. Scintillation decay time was 26.4 ns (45%) with slower decay component of 263 ns (55%).
Neace, James C. (Blackville, SC)
Process for removing diluent degradation products from a solvent extraction solution, which has been used to recover uranium and plutonium from spent nuclear fuel. A wash solution and the solvent extraction solution are combined. The wash solution contains (a) water and (b) up to about, and including, 50 volume percent of at least one-polar water-miscible organic solvent based on the total volume of the water and the highly-polar organic solvent. The wash solution also preferably contains at least one inorganic salt. The diluent degradation products dissolve in the highly-polar organic solvent and the organic solvent extraction solvent do not dissolve in the highly-polar organic solvent. The highly-polar organic solvent and the extraction solvent are separated.
Pyrochemical Extraction of Transition Metals from Pacific Ocean Deep Sea Nodules
S. Von Winbush; V. A. Maroni
Considerable success has been achieved in lixiviation transition metals from Pacific Ocean deep sea nodules. These nodules typically contain ?30 wt% Mn, ?7 wt% Fe, ?1 wt% Ni, ?1 wt% Cu, and ?0.3 wt% Co. Samples of the nodules have been subjected to extraction tests at 450░C using LiCl-KCl eutectic and MgCl2-NaCl-KCl eutectic. The most impressive results came from studies
Micro/macro solidification modeling of columnar eutectic growth
NASA Astrophysics Data System (ADS)
Judson, Ward Michael
A general multidimensional model of alloy solidification is presented in which a velocity-dependent freezing temperature is coupled with the macroscale energy equation. The velocity dependence of the freezing temperature ( Tfśv ) results from the microscale species diffusion for microstructures with coupled eutectic growth. At solidification rates ( ś 1--10 mm/s) that are representative of gravity permanent mold and die casting processes, consideration of the nonequilibrium conditions at the interface affects the prediction of the macroscale thermal field. Near-eutectic alloys freeze with a macroscopically discrete solid-liquid interface at a temperature below the equilibrium eutectic temperature. The model is illustrated with unidirectional solidification of a near-eutectic alloy in a finite domain and solved numerically with a fixed-grid Galerkin finite element method. The numerical algorithm includes inexpensive steps to compute the interface speed explicitly. By nondimensionalizing the governing equations the effect of coupled eutectic growth on heat transport is clearly identified so that the model's sensitivity to important parameters can be investigated. Additionally, the average eutectic spacing can be determined with the temperature field, rather than post-determination from a standard, uncoupled solution of the energy equation. The eutectic coupling results indicate that the predicted solid-liquid interface location lags behind the uncoupled solution; therefore, decreasing the amount of solid formed, increasing the total solidification time, and increasing the average eutectic spacing. A procedure is also illustrated for computing mechanical properties using experimental correlations and the computed interface velocity history. The effect of the eutectic undercooling is then studied in a square domain and a realistic three-dimensional production casting geometry. In order to address the multidimensional cases, a phase-field formulation is developed. Although the interface is considered to have a small finite thickness, the utility of the method is good for complex evolving solid-liquid interfaces and the velocity-dependent freezing temperature is satisfied implicitly. After demonstrating sufficient numerical accuracy, numerical results are presented for the square domain and three-dimensional geometry. Limitations of the phase-field method are discussed, and the conjugate heat transfer problem is studied to address boundary condition issues.
Effect of deep cryogenic treatment on microstructure, creep and wear behaviors of AZ91 magnesium alloy
Kaveh Meshinchi Asl; Alireza Tari; Farzad Khomamizadeh
This paper focuses on the effect of deep cryogenic treatment (?196░C) on microstructure and mechanical properties of AZ91 magnesium alloy. The execution of deep cryogenic treatment on samples changed the distribution of ? precipitates. The tiny laminar ? particles almost dissolved in the microstructure and the coarse divorced eutectic ? phase penetrated into the matrix. This microstructural modification resulted in
Evaluation of Composite Alumina Nanoparticle and Nitrate Eutectic Materials for use in Concentrating Solar Power PlantsĀ
Malik, Darren R.
The focus of this research was to create and characterize high temperature alumina and nitrate salt eutectic nanofluids for use in thermal energy storage (TES) systems. The nitrate eutectic was originally used in the TES system demonstrated as part...
Ternary eutectic growth of Ag-Cu-Sb alloy within ultrasonic field
NASA Astrophysics Data System (ADS)
Zhai, Wei; Hong, Zhenyu; Wei, Bingbo
The liquid to solid transformation of ternary Ag42.4Cu21.6Sb36 eutectic alloy was accomplished in an ultrasonic field with a frequency of 35 kHz, and the growth mechanism of this ternary eutectic was examined. Theoretical calculations predict that the sound intensity in the liquid phase at the solidification interface increases gradually as the interface moves up from the sample bottom to its top. The growth mode of ( ? + ? + Sb) ternary eutectic exhibits a transition of ōdivorced eutecticŚmixture of anomalous and regular structuresŚregular eutecticö along the sample axis due to the inhomogeneity of sound field distribution. In the top zone with the highest sound intensity, the cavitation effect promotes the three eutectic phases to nucleate independently, while the acoustic streaming efficiently suppresses the coupled growth of eutectic phases. In the meantime, the ultrasonic field accelerates the solute transportation at the solid-liquid interface, which reduces the solute solubility of eutectic phases.
Directionally solidified eutectic gamma-gamma nickel-base superalloys
NASA Technical Reports Server (NTRS)
Jackson, M. R. (inventor)
A directionally solidified multivariant eutectic gamma-gamma prime nickel-base superalloy casting having improved high temperature properties was developed. The alloy is comprised of a two phase eutectic structure consisting essentially of on a weight percent base, 6.0 to 9.0 aluminum, 5.0 to 17.0 tantalum, 0-10 cobalt, 0-6 vanadium, 0-6 rhenium, 2.0-6.0 tungsten, and the balance being nickel, subject to the proviso that the sum of the atomic percentages of aluminum plus tantalum is within the range of from 19-22, and the ratio of atomic percentages of tantalum to aluminum plus tantalum is within the range of from 0.12 to 0.23. Embedded within the gamma nickel-base matrix are aligned eutectic gamma prime phase (primarily nickel-aluminum-tantalum) reinforcing fibers.
Refinement of eutectic silicon phase of aluminum A356 alloy using high-intensity ultrasonic vibration
Xiaogang Jian; T. T. Meek; Q. Han
The eutectic silicon in A356 alloy can be refined and modified using either chemical, quench, or superheating modification. We observed, for the first time, that the eutectic silicon can also be significantly refined using high-intensity ultrasonic vibration. Rosette-like eutectic silicon is formed during solidification of specimen treated with high-intensity ultrasonic vibration.
Refinement of Eutectic Silicon Phase of Aluminum A356 Alloy Using High-Intensity Ultrasonic Vibration
Jian, Xiaogang [ORNL; Han, Qingyou [ORNL
The eutectic silicon in A356 alloy can be refined and modified using either chemical, quench, or superheating modification. We observed, for the first time, that the eutectic silicon can also be significantly refined using high-intensity ultrasonic vibration. Rosette-like eutectic silicon is formed during solidification of specimen treated with high-intensity ultrasonic vibration.
Lead-bismuth eutectic technology for Hyperion reactor
NASA Astrophysics Data System (ADS)
Zhang, J.; Kapernick, R. J.; McClure, P. R.; Trapp, T. J.
A small lead-bismuth eutectic-cooled reactor concept (referred to as the Hyperion reactor concept) is being studied at Los Alamos National Laboratory and Hyperion Power Generation. In this report, a critical assessment of the lead-bismuth eutectic technology for Hyperion reactor is presented based on currently available knowledge. Included are: material compatibility, oxygen control, thermal hydraulics, polonium control. The key advances in the technology and their applications to Hyperion reactor design are analyzed. Also, the near future studies in main areas of the technology are recommended for meeting the design requirements.
De Renzo, D.J.
Know solvents and how to protect yourself from dangerous exposure to them. Instant information for decision-making regarding industrial solvents in everyday use, is provided in this handbook which is a compilation of data on 335 hazardous and frequently-used solvents.
Cleaning without chlorinated solvents
L. M. Thompson; R. F. Simandl
Because of health and environmental concerns, many regulations have been passed in recent years regarding the use of chlorinated solvents. The Oak Ridge Y-12 Plant has had an active program to find alternatives for these solvents used in cleaning applications for the past 7 years. During this time frame, the quantity of solvents purchased has been reduced by 92%. The
Structure of directionally solidified InSb-Sb eutectic alloy
Umehara, Y.; Koda, S.
The eutectic alloy of InSb-Sb has been directionally solidified at various rates in order to investigate the structure changes due to solidification conditions. The boundary energy between the InSb and Sb phases was determined from a dislocation model of the interface.
Eutectic epsilon-near-zero metamaterial terahertz waveguides
. Tzortzakis1,3, * 1 Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology that subwavelength waveguiding of terahertz radiation is achieved within an alkaliŁhalide eutectic metamaterial or crystals [12]. Recently it has been shown that alkaliŁhalide polari- tonic materials can be structured
Eutectic alloys. Citations from the International Aerospace Abstracts data base
NASA Technical Reports Server (NTRS)
Moore, P.
These 250 abstracts from the international literature provide summaries of the preparation, treatments, composition and structure, and properties of eutectic alloys. Techniques for directional solidification and treatments including glazing, coating, and fiber reinforcement are discussed. In addition to the mechanical and thermal properties, the superconducting, corrosion, resistance, and thermionic emission and adsorption properties are described.
Microstructural evolution of eutectic Au-Sn solder joints
Song, Ho Geon
Current trends toward miniaturization and the use of lead(Pb)-free solder in electronic packaging present new problems in the reliability of solder joints. This study was performed in order to understand the microstructure and microstructural evolution of small volumes of nominally eutectic Au-Sn solder joints (80Au-20Sn by weight), which gives insight into properties and reliability.
Lamellar eutectic growth at large thermal gradient: I. Stationary patterns
Paris-Sud XI, Universitķ de
'inclinaison ╗. Abstract. 2014 We study stationary front profiles of directionally solidified lamellar eutectics. We show, Classification Physics Abstracts 61.50C - 64.60 - 64.70D - 81.30F 1. Introduction. Directional solidification rod patterns parallel to the common (Oz) direction of the pulling velocity V and of the external
Paffhausen, M.W.; Smith, D.L.; Ugaki, S.N.
This report describes Phase I of the Solvent Recycle/Recovery Task of the DOE Chlorinated Solvent Substitution Program for the US Air Force by the Idaho National Engineering Laboratory, EG G Idaho, Inc., through the US Department of Energy, Idaho Operations Office. The purpose of the task is to identify and test recovery and recycling technologies for proposed substitution solvents identified by the Biodegradable Solvent Substitution Program and the Alternative Solvents/Technologies for Paint Stripping Program with the overall objective of minimizing hazardous wastes. A literature search to identify recycle/recovery technologies and initial distillation studies has been conducted. 4 refs.
Use of Microgravity to Control the Microstructure of Eutectics
NASA Technical Reports Server (NTRS)
Wilcox, William R.; Regel, Liya L.; Smith, Reginald W.
This grant began in June of 1996. Its long term goal is to be able to control the microstructure of directionally solidified eutectic alloys, through an improved understanding of the influence of convection. The primary objective of the present projects is to test hypotheses for the reported influence of microgravity on the microstructure of three fibrous eutectics (MnBi-Bi, InSb-NiSb, Al3Ni-Al). A secondary objective is to determine the influence of convection on the microstructure of other eutectic alloys. Two doctoral students and a masters student supported as a teaching assistant were recruited for this research. Techniques were developed for directional solidification of MnBi-Bi eutectics with periodic application of current pulses to produce an oscillatory freezing rate. Image analysis techniques were developed to obtain the variation in MnBi fiber spacing, which was found to be normally distributed. The mean and standard deviation of fiber spacing were obtained for several freezing conditions. Eighteen ampoules were prepared for use in the gradient freeze furnace QUELD developed at Queen's University for use in microgravity. Nine of these ampoules will be solidified soon at Queen's in a ground-based model. We hope to solidify the other nine in the QUELD that is mounted on the Canadian Microgravity Isolation Mount on MIR. Techniques are being developed for directional solidification of the Al-Si eutectic at different freezing rates, with and without application of accelerated crucible rotation to induce convection. For the first time, theoretical methods are being developed to analyze eutectic solidification with an oscillatory freezing rate. In a classical sharp-interface model, we found that an oscillatory freezing rate increases the deviation of the average interfacial composition from the eutectic, and increases the undercooling of the two phases by different amounts. This would be expected to change the volume fraction solidifying and the fiber spacing. Because of difficulties in tracking the freezing interfaces of the two solid phases, a phase-field model is also being developed. A paper demonstrating application of phase field methods to periodic structures has been submitted for publication.
Solvent extraction of diatomite
Williams, W.
There is provided a method of extracting hydrocarbons from a diatomite ore. The particle size of the ore is first reduced to form a processed ore. The processed ore is then mixed with a substantially irregular granular material to form an unstratified ore mixture having increased permeability to an extracting solvent. The unstratified ore mixture is then permeated with an extracting solvent to obtain a hydrocarbon-solvent stream from which hydrocarbons are subsequently separated. The irregular granular material may be sand.
Activity coefficients of actinide and rare-earth chlorides in molten LiCl/KCl eutectic salt
Bechtel, T.B.; Storvick, T.S. [Univ. of Missouri, Columbia, MO (United States). Dept. of Chemical Engineering] [Univ. of Missouri, Columbia, MO (United States). Dept. of Chemical Engineering
Using a numerical Gibbs free-energy minimization technique, the activity coefficients of actinide and rare-earth chlorides in molten LiCl/KCl eutectic at 450 C have been calculated. Laboratory tests of an electrochemical process for separating actinide metals from rare-earth metals in LiCl/KCl solvent at 450 C provided experimental concentration and cathode potential data. The generalized expansion by Wohl was used to express the concentration dependence of the excess Gibbs free energy. The activity coefficients were expressed in terms of the Wohl volume and interaction energy parameters. The Wohl parameters for the activity coefficient expansions were obtained by minimizing the total Gibbs free energy expressed in terms of the experimental mole fractions. This thermodynamic model will be valuable for process design and scale-up calculations.
Eutectic bonding of boron-aluminum structural components. II
NASA Technical Reports Server (NTRS)
Niemann, J. T.; Garrett, R. A.
Eutectic bonding is a diffusion brazing process developed for fabricating boron-aluminum components from composite monolayer. This process relies on the diffusion of a thin surface film of copper into the aluminum matrix to form a liquid phase when heated above the copper-aluminum eutectic temperature of 1018 F. This type of fabrication offers design flexibility in that skin thickness may be varied, the stiffness geometry and orientation can be varied, and local reinforcement can be added. In addition, this type of boron-aluminum structure offers high efficiency. Also, this method of construction can be cost-comparative with complex titanium shapes; simple tooling permits easy layup, bonding is a one-step operation, and little finish machining is required.
Corrosion of ODS steels in lead bismuth eutectic
NASA Astrophysics Data System (ADS)
Hosemann, P.; Thau, H. T.; Johnson, A. L.; Maloy, S. A.; Li, N.
Oxide dispersion strengthened (ODS) ferritic steels are advanced materials being developed for high temperature applications. Their properties (high temperature strength, creep resistance, corrosion/oxidation resistance) make them potentially usable for high temperature applications in liquid metal cooled systems like liquid lead-bismuth eutectic cooled reactors and spallation sources. Corrosion tests on five different ODS alloys were performed in flowing liquid lead-bismuth eutectic in the DELTA Loop at the Los Alamos National Laboratory at 535 ░C for 200 h and 600 h. The tested materials were chromium alloyed ferritic/martensitic steels (12YWT, 14YWT, MA957) and Cr-Al alloyed steels (PM2000, MA956). It was shown that the Al alloyed ODS steel above 5.5 wt% Al (PM2000) is highly resistant to corrosion and oxidation in the conditions examined, and that the corrosion properties of the ODS steels depend strongly on their grain size.
Creep of directionally solidified alumina\\/YAG eutectic monofilaments
L. E. Matson; N. Hecht
Multi-phaseŚsingle crystal oxide fibers offer the best choice for reinforcing oxide matrix composites because they have superior creep resistance up to 1700░C without significant strength loss at moderate temperatures due to growth of processing flaws. In this work, Directionally Solidified Al2O3¢YAG eutectic fibers were grown at various rates by the Edge-defined, Film-fed Growth (EFG) method and their microstructure, microstructural stability
Unidirectional solidification of Co-Cr-C monovariant eutectic alloys
E. R. Thompson; F. D. Lemkey
Compositions on the eutectic liquidus line between Co-25 wt pct Cr-3.5 wt pct C and Co-45 wt pct Cr-2.2 wt pct C wherein the simultaneous freezing of a metal matrix and a carbide occur have been solidified unidirectionally. The composite structures formed consist of a cobalt matrix containing substantial amounts of soluble chromium with the carbide phase, (Cr, Co)7C3, as
Magnetic properties of directionally solidified MnBi-Bi eutectics
C. Graham; M. Notis; J.-C. Boulbes
Samples consisting of approximately parallel arrays of ferromagnetic MnBi rods in a Bi matrix have been grown by directional solidification of eutectic Mn-Bi alloys. The rods are of order 1?m in diameter, and very long in comparison to their diameter. Room-temperature intrinsic coercive fields up to 30 kOe have been attained, suggesting that the rods show single-domain behavior. The measured
An approximate formula for recalescence in binary eutectic alloys
NASA Technical Reports Server (NTRS)
Ohsaka, K.; Trinh, E. H.
In alloys, solidification takes place along various paths which may be ascertained via phase diagrams; while there would be no single formula applicable to all alloys, an approximate formula for a specific solidification path would be useful in estimating the fraction of the solid formed during recalescence. A formulation is here presented of recalescence in binary eutectic alloys. This formula is applied to Ag-Cu alloys which are of interest in containerless solidification, due to their formation of supersaturated solutions.
Fatigue crack propagation behaviour of unidirectionally solidified ?\\/??-? eutectic alloys
Philip E. Bretz; Richard W. Hertzberg
Fatigue crack propagation (FCP) studies were conducted on a series of?\\/??-? (Ni-Nb-Al) alloys by subjecting them to cyclic four-point bending loads at room temperature. The aluminium contents of the alloys investigated ranged from 1.5% to 2.5% by weight, with the niobium contents adjusted to maintain controlled eutectic microstructures. In addition to studies of as-grown alloys, heat treatments were performed on
?SR studies of superconductivity in eutectically grown mixed ruthenates
NASA Astrophysics Data System (ADS)
Shiroka, T.; Fittipaldi, R.; Cuoco, M.; De Renzi, R.; Maeno, Y.; Lycett, R. J.; Ramos, S.; Forgan, E. M.; Baines, C.; Rost, A.; Granata, V.; Vecchione, A.
The low-temperature magnetic behavior of the double-layered ruthenate Sr3Ru2O7, as grown from a eutectic Sr2RuO4-Sr3Ru2O7 system, was investigated via zero- and transverse-field muon-spin rotation. The gradual increase of the muon relaxation rate observed below 2.5 K, even in the absence of applied magnetic fields, indicates the occurrence of a spontaneous breaking of time-reversal symmetry. The onset of the latter at a temperature above 1.5 K, the Tc of the single phase Sr2RuO4, provides evidence about an unconventional superconducting state in the eutectic phase, which most likely takes place at the interface between the Sr2RuO4 and Sr3Ru2O7 domains, or even inside the Sr3Ru2O7 phase. We show that the superconducting state manifests a two-component behavior in the transverse-field response with change-over at about T=2.5 K and T=1.5 K. The comparison with zero-field ?SR data in the Ru-Sr2RuO4 eutectic system rules out the possibility of spurious effects due to embedded Ru islands.
Metastable Eutectic Equilibrium in Natural Environments: Recent Development and Research Opportunities
NASA Technical Reports Server (NTRS)
Rietmeijer, Frans J. M.; Nuth, Joseph A., III; Jablonska, Mariola; Karner, James M.
Chemical ordering at metastable eutectics was recognized in non-equilibrium gas-to- solid condensation experiments to constrain 'silicate' dust formation in O-rich circumstellar environments. The predictable metastable eutectic behavior successfully predicted the observed ferromagnesiosilica compositions of circumstellar dust presolar and solar nebula grains in the matrix of the collected aggregate IDPs (Interplanetary Dust Particles). Many of the experimentally determined metastable eutectic solids match the fundamental building blocks of common rock-forming layer silicates: this could have implications for the origin of Life. The physical conditions conducive to metastable eutectic behavior, i.e. high temperature and (ultra) fast quenching, lead to unique amorphous, typically nano- to micrometer-sized, materials. The new paradigm of metastable eutectic behavior opens the door to new and exciting research opportunities in uncovering the many implications of these unique amorphous, and typically nano-to micrometer-sized, metastable eutectic materials.
Metastable Eutectic Equilibrium in Natural Environments: Recent Developments and Research Opportunities
NASA Technical Reports Server (NTRS)
Rietmeijer, Fans J. M.; Nuth, Joseph A., II; Jablonska, Mariola; Karner, James M.
Chemical ordering at metastable eutectics was recognized in non-equilibrium gas-to- solid condensation experiments to constrain 'silicate' dust formation in O-rich circumstellar environments. The predictable metastable eutectic behavior successfully predicted the observed ferromagnesiosilica, compositions of circumstellar dust, presolar and solar nebula grains in the matrix of the collected aggregate IDPs. Many of the experimentally determined metastable eutectic solids match the fundamental building blocks of common rock-forming layer silicates: this could have implications for the origin of Life. The physical conditions conducive to metastable eutectic behavior, i.e. high temperature and (ultra)fast quenching, lead to unique amorphous, typically nano- to micrometer-sized, materials. The new paradigm of metastable eutectic behavior opens the door to new and exciting research opportunities in uncovering the many implications of these unique amorphous and typically nano- to micrometer-sized, metastable eutectic materials.
D. E. Hardesty; H. F. Buchholz
Drying of wet coal is facilitated by the addition of a nonaqueous solvent, such as acetone, to the coal followed by application of heat to remove both solvent and water from the coal. The coal may be further upgraded by briquetting or pelletizing fine coal particles with waxes and resins extracted from the coal, or the waxes and resins may
This study evaluated the product quality, waste reduction/pollution prevention, and economic aspects of three technologies for onsite solvent recovery: atmospheric batch distillation, vacuum heat-pump distillation, and a low-emission vapor degreaser with closed solvent, liquid an...
Studies of directionally solidified eutectic Bi\\/MnBi at low growth velocities
Ron G. Pirich
A deviation from the interrod spacing (?) and growth velocity (V) relation ?2V = constant, anticipated for diffusion-only rod eutectic growth, has been observed at growth velocities ?5 cm\\/h (14 Ąm\\/s)\\u000a in directionally solidified eutectic Bi-Mn (Bi\\/MnBi). At lower growth velocities,V? 0.5 cm\\/h, a breakdown in the aligned rod eutectic, cooperative growth mechanism, has also been noted. The ?2V relation
Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite
Lee, Seoung Wan; Kim, Jeong Tae; Hong, Sung Hwan; Park, Hae Jin; Park, Jun-Young; Lee, Nae Sung; Seo, Yongho; Suh, Jin Yoo; Eckert, J³rgen; Kim, Do Hyang; Park, Jin Man; Kim, Ki Buem
The outstading mechanical properties of bimodal ultrafine eutectic composites (BUECs) containing length scale hierarchy in eutectic structure were demonstrated by using AFM observation of surface topography with quantitative height measurements and were interpreted in light of the details of the deformation mechanisms by three different interface modes. It is possible to develop a novel strain accommodated eutectic structure for triggering three different interface-controlled deformation modes; (I) rotational boundary mode, (II) accumulated interface mode and (III) individual interface mode. A strain accommodated microstructure characterized by the surface topology gives a hint to design a novel ultrafine eutectic alloys with excellent mechanical properties. PMID:25265897
Stress production and relief in the gold/silicon eutectic die-attach process
NASA Astrophysics Data System (ADS)
Hund, T. D.; Burchett, S. N.
Eutectic braze thickness and package cooling rate for stress relief in eutectically bonded die were evaluated. Two package types, a 30 pin leadless chip carrier and a 28 pin flat pack were used as models in finite element stress calculations to study these parameters on the maximum principal stress, maximum circumferential stress, and maximum shear stress. Bonding temperature, creep rate, silicon tensile strength, and the effects of surface defects on silicon tensile strength were studied to evaluate their effects on stresses in the die. It is indicated that with a thicker eutectic braze and a slower cooling rate, die can be eutectically attached without excessive stress.
Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite.
Lee, Seoung Wan; Kim, Jeong Tae; Hong, Sung Hwan; Park, Hae Jin; Park, Jun-Young; Lee, Nae Sung; Seo, Yongho; Suh, Jin Yoo; Eckert, J³rgen; Kim, Do Hyang; Park, Jin Man; Kim, Ki Buem
The outstading mechanical properties of bimodal ultrafine eutectic composites (BUECs) containing length scale hierarchy in eutectic structure were demonstrated by using AFM observation of surface topography with quantitative height measurements and were interpreted in light of the details of the deformation mechanisms by three different interface modes. It is possible to develop a novel strain accommodated eutectic structure for triggering three different interface-controlled deformation modes; (I) rotational boundary mode, (II) accumulated interface mode and (III) individual interface mode. A strain accommodated microstructure characterized by the surface topology gives a hint to design a novel ultrafine eutectic alloys with excellent mechanical properties. PMID:25265897
Desulfurization of FCC Gasoline by Solvent Extraction and Photooxidation
Aladin Ibrahim; Shen Ben Xian; Zhou Wei
A deep desulfurization process for FCC light gasoline has been investigated. The process is comprised of liquid-liquid extraction with acetonitrile, and photooxidation with ultraviolet light from a high-pressure mercury lamp. After the extraction the sulfur-containing compounds transfer from the oil to the solvent and then the solvent containing these sulfur compounds was photo-irradiated with ultraviolet light from a high pressure
Continuous countercurrent membrane column for the separation of solute/solvent and solvent/solvent systems
Nerad, Bruce A. (Longmont, CO); Krantz, William B. (Boulder, CO)
A reverse osmosis membrane process or hybrid membrane - complementary separator process for producing enriched product or waste streams from concentrated and dilute feed streams for both solvent/solvent and solute/solvent systems is described.
NSDL National Science Digital Library
This interactive online tool helps students grasp just how deep scientists must dive to study deep sea vents. By providing points of comparison, it puts the nearly unfathomable depth of the ocean floor into perspective. It compares the scale of a 2,400-meter (7,874-foot) dive against the height of famous landmarks such as the Empire State Building, the Eiffel Tower, and the Space Needle. Students can also enter the height, in feet or meters, of any landmark they choose to gain additional perspective.
This lecture will cover recent success in controlling and assessing the treatment of shallow ground water plumes of chlorinated solvents, other halogenated organic compounds, and methyl tert-butyl ether (MTBE)....
Permeation of Tank C-103 sludge simulant by organic solvent
Gerber, M.A.
The plan for stabilizing underground storage tanks (USTs) calls for draining the supernate from the tanks; however, there is concern that draining the supernate from Tank C-103 will degrade safety in the tank. The sludge in Tank C-103 contains ranges in depth from 1 to 1.5 m and is covered by both an aqueous phase and a separate organic layer. The main concern is that draining the supernate will cause the solvent to permeate the sludge solids and provide a source of fuel for a fire on the surface of the drained sludge. The question of whether the solvent will permeate sludge that is 1 to 1.5 m deep after the tank is dewatered is the purpose of the tests conducted and described in this report. Evaluation of the solvent permeation mechanism required the preparation of solvent, supernate, and sludge simulants based on the known chemistry of Tank C-103. Solvent and aqueous phase supernate simulants are based on the results of fiscal year 1994 sampling of the tank solvent and supernate. Sludge simulant is based on the chemical analyses of tank sludge samples retrieved in 1986. Experiments were conducted with each simulant to evaluate solvent permeation under matric potentials ranging from 0.8 m to 1.8 m of supernate. The amount of solvent recovered for each experiment was recorded as well as the maximum amount of solvent that could be din the sludge based on solvent recovered from resuspended sludge and solvent not recovered. The wt% of water remaining in the sludge was also recorded for each experiment, which was determined by measuring the weight of the sludge after drying it. One observation noted from the test results is that the finer sludge material tended to have a greater amount of solvent loss compared to the coarser sludge material at comparable levels of vacuum. At this time, there is no explanation.
Supercritical solvent coal extraction
NASA Technical Reports Server (NTRS)
Compton, L. E. (inventor)
Yields of soluble organic extract are increased up to about 50% by the supercritical extraction of particulate coal at a temperature below the polymerization temperature for coal extract fragments (450 C.) and a pressure from 500 psig to 5,000 psig by the conjoint use of a solvent mixture containing a low volatility, high critical temperature coal dissolution catalyst such as phenanthrene and a high volatility, low critical temperature solvent such as toluene.
Cleaning without chlorinated solvents
Thompson, L.M.; Simandl, R.F.
Because of health and environmental concerns, many regulations have been passed in recent years regarding the use of chlorinated solvents. The Oak Ridge Y-12 Plant has had an active program to find alternatives for these solvents used in cleaning applications for the past 7 years. During this time frame, the quantity of solvents purchased has been reduced by 92%. The program has been a twofold effort. Vapor degreasers used in batch cleaning-operations have been replaced by ultrasonic cleaning with aqueous detergent, and other organic solvents have been identified for use in hand-wiping or specialty operations. In order to qualify these alternatives for use, experimentation was conducted on cleaning ability as well as effects on subsequent operations such as welding, painting and bonding. Cleaning ability was determined using techniques such as X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FTIR) which are capable of examining monolayer levels of contamination on a surface. Solvents have been identified for removal of rust preventative oils, lapping oils, machining coolants, lubricants, greases, and mold releases. Solvents have also been evaluated for cleaning urethane foam spray guns, swelling of urethanes and swelling of epoxies.
Asymmetric Binary Mixtures Under Cylindrical Confinement: A Molecular Dynamics Simulation Study
Biswas, Ranjit
liquids, binary mixtures of ionic liquids with polar solvents, deep eutectics and model asymmetric and complex systems, such as, ionic liquids, deep eutectics, binary and ternary mixtures, poly simulation study on solute and solvent dynamics in neutral and charged reverse micelles have been carried out
Pattern Formation and Growth Kinetics in Eutectic Systems
Jing Teng
Growth patterns during liquid/solid phase transformation are governed by simultaneous effects of heat and mass transfer mechanisms, creation of new interfaces, jump of the crystallization units from liquid to solid and their rearrangement in the solid matrix. To examine how the above processes influence the scale of microstructure, two eutectic systems are chosen for the study: a polymeric system polyethylene glycol-p-dibromobenzene (PEG-DBBZ) and a simple molecular system succinonitrile (SCN)-camphor. The scaling law for SCN-camphor system is found to follow the classical Jackson-Hunt model of circular rod eutectic, where the diffusion in the liquid and the interface energy are the main physics governing the two-phase pattern. In contrast, a significantly different scaling law is observed for the polymer system. The interface kinetics of PEG phase and its solute concentration dependence thus have been critically investigated for the first time by directional solidification technique. A model is then proposed that shows that the two-phase pattern in polymers is governed by the interface diffusion and the interface kinetics. In SCN-camphor system, a new branch of eutectic, elliptical shape rodl, is found in thin samples where only one layer of camphor rods is present. It is found that the orientation of the ellipse can change from the major axis in the direction of the thickness to the direction of the width as the velocity and/or the sample thickness is decreased. A theoretical model is developed that predicts the spacing and orientation of the elliptical rods in a thin sample. The single phase growth patterns of SCN-camphor system were also examined with emphasis on the three-dimensional single cell and cell/dendrite transition. For the 3D single cell in a capillary tube, the entire cell shape ahead of the eutectic front can be described by the Saffmann-Taylor finger only at extremely low growth rate. A 3D directional solidification model is developed to characterize the cell shape and tip undercooling and the experimental results are compared with the predictions of the model. From the investigation of cell/dendrite transition, a model is proposed, from which the condition for the onset of the transition can be obtained.
Microstructure of directionally solidified CrAs/GaAs eutectic
Holmes, D.E.; Koo, L.Y. [Electronic Materials Engineering, Camarillo, CA (United States)] [Electronic Materials Engineering, Camarillo, CA (United States)
The microstructure of the CrAs/GaAs eutectic directionally solidified by both the Czochralski (Cz) and vertical Bridgman (VB) methods consists of arrays of CrAs rods oriented along the axis of solidification in a GaAs matrix. Microdefects in Cz material including striations, terminations and nucleations, coalescence and branching, and oscillatory instabilities are prevalent and are the result of dynamic morphological adjustment under fluctuating conditions of microscopic solidification. In contrast, selected regions of VB material exhibit near-ideal hexagonal packing of circular rods in the matrix. Cause-effect relationships between microstructure and conditions of solidification were determined and are presented and discussed.
Development of high temperature fasteners using directionally solidified eutectic alloys
NASA Technical Reports Server (NTRS)
George, F. D.
The suitability of the eutectics for high temperature fasteners was investigated. Material properties were determined as a function of temperature, and included shear parallel and perpendicular to the growth direction and torsion parallel to it. Techniques for fabricating typical fastener shapes included grinding, creep forming, and direct casting. Both lamellar Ni3Al-Ni3Nb and fibrous (Co,Cr,Al)-(Cr,Co)7C3 alloys showed promise as candidate materials for high temperature fastener applications. A brief evaluation of the performance of the best fabricated fastener design was made.
Interface diffusion in eutectic Pb¢Sn solder
D. Gupta; K. Vieregge; W. Gust
Interface diffusion of 210Pb and 113Sn radioactive tracers in oriented Pb¢62wt%Sn eutectic specimens showing lamellar structure has been measured. The product of the interface diffusion coefficient and the width, ?Di, shows an Arrhenius relationship below 400K. The values of the Arrhenius parameters, Qi and ?D░i, for the 210Pb and 113Sn tracers are 84.8kJ\\/mol, 7ū10?10m3\\/s and 77kJ\\/mol, 7ū10?12m3\\/s, respectively. An interface
Divorced Eutectic Solidification of Mg-Al Alloys
NASA Astrophysics Data System (ADS)
Monas, Alexander; Shchyglo, Oleg; Kim, Se-Jong; Yim, Chang Dong; H÷che, Daniel; Steinbach, Ingo
We present simulations of the nucleation and equiaxed dendritic growth of the primary hexagonal close-packed ? -Mg phase followed by the nucleation of the ? -phase in interdendritic regions. A zoomed-in region of a melt channel under eutectic conditions is investigated and compared with experiments. The presented simulations allow prediction of the final properties of an alloy based on process parameters. The obtained results give insight into the solidification processes governing the microstructure formation of Mg-Al alloys, allowing their targeted design for different applications.
Creep in Directionally Solidified NiAl-Mo Eutectics
Dudova, Marie [Institute of Physics, Czech Republic; Kucharova, Kveta [Institute of Physics, Czech Republic; Bartak, Tomas [Institute of Physics, Czech Republic; Bei, Hongbin [ORNL; George, Easo P [ORNL; Somsen, Ch. [Ruhr University, Bochum, Germany; Dlouhy, A. [Institute of Physics of Materials, Brno, Czech Republic
A directionally solidified NiAl-Mo eutectic and an NiAl intermetallic, having respective nominal compositions Ni-45.5Al-9Mo and Ni-45.2Al (at.%), were loaded in compression at 1073 and 1173 K. Formidable strengthening by regularly distributed Mo fibres (average diameter 600 nm, volume fraction 14%) was observed. The fibres can support compression stresses transferred from the plastically deforming matrix up to a critical stress of the order of 2.5 GPa, at which point they yield. Microstructural evidence is provided for the dislocation-mediated stress transfer from the NiAl to the Mo phase.
Directional solidification of Pb-Sn eutectic with vibration
NASA Technical Reports Server (NTRS)
Caram, Rubens; Banan, Mohsen; Wilcox, William R.
Pb-Sn eutectic alloy was directionally solidified at 1.4 to 3.2 cm/hr with forced convection induced by axial vibration of the growth ampoule with a frequency of 10 to 40 Hz and an amplitude of 0.5 to 1.0 mm. To determine the exact growth rate, an interface demarcation technique was applied. The lamellar spacing was increased 10 to 40 percent in ingots solidified with vibration compared to those solidified without vibration. The average intensity of convection in the melt under axial vibration of the ampoule was estimated by comparing the experimental results with a theoretical model.
Composition gradients in electrolyzed LiCl-KCl eutectic melts
NASA Astrophysics Data System (ADS)
Vallet, C. E.; Heatherly, D. E.; Braunstein, J.
Analysis of transport in a mixed electrolyte has previously predicted significant composition gradients in the LiCl-KCl electrolyte of high temperature LiS/ batteries. Composition gradients in quenched electrolyzed LiCl-KCl eutectic contained in yttria felt are measured with high distance resolution by scanning electron microscopy with energy dispersive X-ray spectroscopy. The reported results include composition profiles of LiCl-KCl coontained in porous Y2O3 and electrolyzed in three cells, two with solid Li-Al electrodes and one with a porous Li-Al anode.
Composition gradients in electrolyzed LiCl-KCL eutectic melts
Vallet, C.E.; Braunstein, J.; Heatherly, D.E.
Analysis of transport in a mixed electrolyte has previously predicted significant composition gradients in the LiCl-KCl electrolyte of high temperature Li/S batteries. Composition gradients in quenched electrolyzed LiCl-KCl eutectic contained in yttria felt are measured with high distance resolution by scanning electron microscopy with energy dispersive x-ray spectroscopy. The reported results include composition profiles of LiCl-KCl contained in porous Y/sub 2/O/sub 3/ and electrolyzed in three cells, two with solid Li-Al electrodes and one with a porous Li-Al anode.
Low-Temperature Interface Reaction between Titanium and the Eutectic Silver-Copper Brazing Alloy
Paris-Sud XI, Universitķ de
is of 780 ░C) should be favourable to the preservation of the microstructure and composition of the titanium1 Low-Temperature Interface Reaction between Titanium and the Eutectic Silver-Copper Brazing Alloy zones formed at 790 ░C between solid titanium and liquid Ag-Cu eutectic alloys (pure and Ti
The eutectic characteristic of MC-type carbide precipitation in a DS nickel-base superalloy
W. R. Sun; J. H. Lee; S. M. Seo; S. J. Choe; Z. Q. Hu
The precipitation of MC-type carbide in a DS nickel-base superalloy has been studied. The nucleating temperature of the MC carbide was determined by analysis. The MC carbide and ? phase were complementary in composition, and the eutectic reaction of (?+MC) took place in different forms at varied solidification rate. The (?+MC) eutectic reaction was an important factor of determining the
Lead¢gold eutectic: An alternative liquid target material candidate for high power spallation neutron sources
Marisa Medarde; Rainer Moormann; Ruggero Frison; Robert J. Pu?niak; Ekaterina Pomjakushina; Kazimierz Conder; Ernests Platacis; Yong Dai; Daniela Kiselev; Luca Zanini; Szabina T÷r÷k; Peter Zagyvai; Stephan Heinitz; J÷rg Neuhausen; Dorothea Schumann; Knud Thomsen
One of the main technical concerns of Megawatt-class spallation neutron sources is the removal of the heat deposited in the target station. A way to overcome it is to use targets consisting of flowing liquid metals, but the already tested materials ¢ mercury and lead¢bismuth eutectic (LBE) ¢ are not unproblematic. We show here that another eutectic alloy containing lead
Transdermal delivery from eutectic systems: enhanced permeation of a model drug, ibuprofen
Paul W Stott; Adrian C Williams; Brian W Barry
The formation of eutectic systems between ibuprofen (ibu) and seven terpene skin penetration enhancers was studied and, by using the eutectic systems as donors, the effects of melting point depression of the delivery system on transdermal delivery were investigated. A range of ibu:terpene binary mixtures were melted together, cooled, and recrystallised. Composition\\/melting point phase diagrams were determined by DSC and
Competitive stochastic growth model for the 3D morphology of eutectic Si in Al-Si alloys
Schmidt, Volker
Competitive stochastic growth model for the 3D morphology of eutectic Si in Al-Si alloys Gerd for the simulation of the 3D morphology of eutectic silicon in Al-Si alloys, which represents the colonies-Si alloys, coral-like eutectic Si, stochastic growth model, multivariate time series, FIB-SEM tomography
JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 9, NO. 1, MARCH 2000 3 Localized Silicon Fusion and Eutectic Bonding for
Lin, Liwei
and Eutectic Bonding for MEMS Fabrication and Packaging Y. T. Cheng, Liwei Lin, Member, IEEE, and Khalil Najafi, Fellow, IEEE Abstract--Silicon fusion and eutectic bonding processes based on the technique of localized separately in the silicon-to-glass fusion bonding and silicon-to-gold eutectic bonding experiments
Ternary eutectic growth of nanostructured thermoelectric Ag-Pb-Te materials
Wu, Hsin-jay; Chen, Sinn-wen [Department of Chemical Engineering, National Tsing Hua University, 101, Sec. 2, Kuang-Fu Rd., Hsin-Chu 300, Taiwan (China); Foo, Wei-jian [Engineering Science Programme, National University of Singapore, Blk EA, 06-10, 9 Engineering Drive, Singapore 117576 (Singapore); Jeffrey Snyder, G. [Materials Science, California Institute of Technology, 1200 California Blvd., Pasadena, California 91125 (United States)
Nanostructured Ag-Pb-Te thermoelectric materials were fabricated by unidirectionally solidifying the ternary Ag-Pb-Te eutectic and near-eutectic alloys using the Bridgeman method. Specially, the Bridgman-grown eutectic alloy exhibited a partially aligned lamellar microstructure, which consisted of Ag{sub 5}Te{sub 3} and Te phases, with additional 200-600 nm size particles of PbTe. The self-assembled interfaces altered the thermal and electronic transport properties in the bulk Ag-Pb-Te eutectic alloy. Presumably due to phonon scattering from the nanoscale microstructure, a low thermal conductivity ({kappa} = 0.3 W/mK) was achieved of the eutectic alloy, leading to a zT peak of 0.41 at 400 K.
Localized removal of the Au-Si eutectic bonding layer for the selective release of microstructures
NASA Astrophysics Data System (ADS)
Gradin, Henrik; Braun, Stefan; Stemme, G÷ran; van der Wijngaart, Wouter
This paper presents and investigates a novel technique for the footprint and thickness-independent selective release of Au-Si eutectically bonded microstructures through the localized removal of their eutectic bond interface. The technique is based on the electrochemical removal of the gold in the eutectic layer and the selectivity is provided by patterning the eutectic layer and by proper electrical connection or isolation of the areas to be etched or removed, respectively. The gold removal results in a porous silicon layer, acting similar to standard etch holes in a subsequent sacrificial release etching. The paper presents the principle and the design requirements of the technique. First test devices were fabricated and the method successfully demonstrated. Furthermore, the paper investigates the release mechanism and the effects of different gold layouts on both the eutectic bonding and the release procedure.
Anthracene + Pyrene Solid Mixtures: Eutectic and Azeotropic Character
Rice, James W.; Fu, Jinxia; Suuberg, Eric M.
To better characterize the thermodynamic behavior of a binary polycyclic aromatic hydrocarbon mixture, thermochemical and vapor pressure experiments were used to examine the phase behavior of the anthracene (1) + pyrene (2) system. A solid-liquid phase diagram was mapped for the mixture. A eutectic point occurs at 404 K at x1 = 0.22. A model based on eutectic formation can be used to predict the enthalpy of fusion associated with the mixture. For mixtures that contain x1 < 0.90, the enthalpy of fusion is near that of pure pyrene. This and X-ray diffraction results indicate that mixtures of anthracene and pyrene have pyrene-like crystal structures and energetics until the composition nears that of pure anthracene. Solid-vapor equilibrium studies show that mixtures of anthracene and pyrene form solid azeotropes at x1 of 0.03 and 0.14. Additionally, mixtures at x1 = 0.99 sublime at the vapor pressure of pure anthracene, suggesting that anthracene behavior is not significantly influenced by x2 = 0.01 in the crystal structure. PMID:21116474
Eutectic Solder Bonding for Highly Manufacturable Microelectromechanical Systems Probe Card
NASA Astrophysics Data System (ADS)
Kim, Bonghwan
We developed eutectic solder bonding for the microelectromechanical systems (MEMS) probe card. We tested various eutectic solder materials, such as Sn, AgSn, and AuSn, and investigated the bonding ability of Sn-based multi-element alloys and their resistance to chemical solutions. The Sn-based alloys were formed by sputtering, electroplating, and the use of solder paste. According to our experimental results, Sn-rich solders, such as Ag3.5Sn, Ag3.5Sn96Cu0.5, and Sn, were severely damaged by silicon wet etchant such as potassium hydroxide (KOH) and tetramethylammonium hydroxide (TMAH). On the other hand Au80Sn20 was resistant to those chemicals. In order to verify the joint bondability of the solders, we used a cantilever probe beam, and bump which were made of nickel and nickel alloy. After flip-chip bonding of the cantilever beam and the bump with Au80Sn20 solder paste, we measured the contact force to verify the mechanical strength. We then re-inspected it with X-rays and found no voids in the joint.
NASA Technical Reports Server (NTRS)
Chang, Alice C. (Inventor); St. Clair, Terry L. (Inventor)
A solvent resistant copolyimide was prepared by reacting 4,4'-oxydiphthalic anhydride with a diaimine blend comprising, based on the total amount of the diamine blend, about 75 to 90 mole percent of 3,4'-oxydianiline and about 10 to 25 mole percent p-phenylene diamine. The solvent resistant copolyimide had a higher glass transition temperature when cured at 350.degree. , 371.degree. and 400.degree. C. than LaRC.TM.-IA. The composite prepared from the copolyimide had similar mechanical properties to LaRC.TM.-IA. Films prepared from the copolyimide were resistant to immediate breakage when exposed to solvents such as dimethylacetamide and chloroform. The adhesive properties of the copolyimide were maintained even after testing at 23.degree., 150.degree., 177.degree. and 204.degree. C.
Harrup, Mason K. (Idaho Falls, ID); Delmastro, Joseph R. (Idaho Falls, ID); Stewart, Frederick F. (Idaho Falls, ID); Luther, Thomas A. (Idaho Falls, ID)
An ion transporting solvent maintains very low vapor pressure, contains flame retarding elements, and is nontoxic. The solvent in combination with common battery electrolyte salts can be used to replace the current carbonate electrolyte solution, creating a safer battery. It can also be used in combination with polymer gels or solid polymer electrolytes to produce polymer batteries with enhanced conductivity characteristics. The solvents may comprise a class of cyclic and acyclic low molecular weight phosphazenes compounds, comprising repeating phosphorus and nitrogen units forming a core backbone and ion-carrying pendent groups bound to the phosphorus. In preferred embodiments, the cyclic phosphazene comprises at least 3 phosphorus and nitrogen units, and the pendent groups are polyethers, polythioethers, polyether/polythioethers or any combination thereof, and/or other groups preferably comprising other atoms from Group 6B of the periodic table of elements.
Halogenated solvent remediation
Sorenson, Kent S.
Methods for enhancing bioremediation of ground water contaminated with nonaqueous halogenated solvents are disclosed. A preferred method includes adding a composition to the ground water wherein the composition is an electron donor for microbe-mediated reductive dehalogenation of the halogenated solvents and enhances mass transfer of the halogenated solvents from residual source areas into the aqueous phase of the ground water. Illustrative compositions effective in these methods include surfactants such as C.sub.2 -C.sub.4 carboxylic acids and hydroxy acids, salts thereof, esters of C.sub.2 -C.sub.4 carboxylic acids and hydroxy acids, and mixtures thereof. Especially preferred compositions for use in these methods include lactic acid, salts of lactic acid, such as sodium lactate, lactate esters, and mixtures thereof. The microbes are either indigenous to the ground water, or such microbes can be added to the ground water in addition to the composition.
Hardesty, D.E.; Buchholz, H.F.
Drying of wet coal is facilitated by the addition of a nonaqueous solvent, such as acetone, to the coal followed by application of heat to remove both solvent and water from the coal. The coal may be further upgraded by briquetting or pelletizing fine coal particles with waxes and resins extracted from the coal, or the waxes and resins may be left on the coal to reduce the tendency of the coal to reabsorb water. In addition, minerals such as sodium and potassium salts may be removed from the coal to reduce slagging and fouling behavior of the coal.
Automated solvent concentrator
NASA Technical Reports Server (NTRS)
Griffith, J. S.; Stuart, J. L.
Designed for automated drug identification system (AUDRI), device increases concentration by 100. Sample is first filtered, removing particulate contaminants and reducing water content of sample. Sample is extracted from filtered residue by specific solvent. Concentrator provides input material to analysis subsystem.
Microstructure and Strength of NiTi-Nb Eutectic Braze Joining NiTi Wires
NASA Astrophysics Data System (ADS)
Wang, Liqiang; Wang, Cong; Dunand, David C.
NiTi wires were brazed together via liquid eutectic formation between NiTi and Nb powders deposited at the wire contact region. The brazed region shows proeutectic NiTi(Nb) in contact with the wires, sandwiching a NiTi-Nb eutectic structure, whose microhardness and stiffness, as characterized via nanoindentation, are higher than the NiTi wires, while also showing signs of high ductility. NiTi-Nb eutectic bonding may thus be a viable approach for producing shape-memory NiTi scaffolds brazed from stacked, woven, or braided wires.
Evaporation of mercury impurity from liquid lead-bismuth eutectic
NASA Astrophysics Data System (ADS)
Aerts, A.; Danaci, S.; Gonzalez Prieto, B.; Van den Bosch, J.; Neuhausen, J.
The equilibrium evaporation of mercury from dilute solutions in liquid lead-bismuth eutectic (LBE) was studied in argon atmosphere. Mercury present as impurity in LBE was evaporated and detected by atomic fluorescence spectroscopy. A method which could accurately simulate the experimental data was developed. Coefficients of the Henry constant temperature correlation for mercury dissolved in LBE were determined. Experiments with samples from several different batches of LBE revealed that mercury at mole fractions between 10-6 and 10-12 and temperatures between 150 and 350 ░C evaporated from liquid LBE close to ideal behavior. Evaporation of mercury from solid LBE on the other hand was unexpectedly high. These results are important for safety evaluations of LBE based spallation targets and accelerator driven systems.
Glass transition and mixing thermodynamics of a binary eutectic system.
Tu, Wenkang; Chen, Zeming; Gao, Yanqin; Li, Zijing; Zhang, Yaqi; Liu, Riping; Tian, Yongjun; Wang, Li-Min
A quantitative evaluation of the contribution of mixing thermodynamics to glass transition is performed for a binary eutectic benzil and m-nitroaniline system. The microcalorimetric measurements of the enthalpy of mixing give small and positive values, typically ~200 J mol(-1) for the equimolar mixture. The composition dependence of the glass transition temperature, T(g), is found to show a large and negative deviation from the ideal mixing rule. The Gordon-Taylor and Couchman-Karasz models are subsequently applied to interpret the T(g) behavior, however, only a small fraction of the deviation is explained. The analyses of the experimental results manifest quantitatively the importance of the mixing thermodynamics in the glass transition in miscible systems. PMID:24413254
Directional solidification of Pb-Sn eutectic with vibration
NASA Technical Reports Server (NTRS)
Caram, Rubens; Banan, Mohsen; Wilcox, William R.
Pb-Sn eutectic alloy was directionally solidified at 1.4 to 3.2 cm/h with forced convection induced by axial vibration of the growth ampoule with a frequency of 10 to 40 Hz and an amplitude of 0.5 to 1.0 mm. To determine the exact growth rate, an interface demarcation technique was applied. The lamellar spacing was increased 10 to 40 percent in ingots solidified with vibration, compared to those solidified without vibration. The number of grain boundaries was increased by vibration. The average intensity of convection in the melt under axial vibration of the ampoule was estimated by comparing the experimental results with a theoretical model.
Directional solidification of Pb-Sn eutectics with vibration
NASA Technical Reports Server (NTRS)
Caram, Rubens; Banan, Mohsen; Wilcox, William R.
Pb-Sn eutectic alloy was directionally solidified at 1.4 to 3.2 cm/hr with forced convection induced by axial vibration of the growth ampoule with a frequency of 10 to 40 Hz and an amplitude of 0.5 to 1.0 mm. To determine the exact growth rate, an interface demarcation technique was applied. The lamellar spacing was increased 10 to 40 percent in ingots solidified with vibration compared to those solidified without vibration. The number of grain boundaries was increased by vibration. The average intensity of convection in the melt under axial vibration of the ampoule was estimated by comparing the experimental results with a theoretical model.
Traceable Co-C eutectic points for thermocouple calibration
Jahan, F.; Ballico, M. J. [National Measurement Institute, Lindfield, NSW 2070 (Australia)] [National Measurement Institute, Lindfield, NSW 2070 (Australia)
National Measurement Institute of Australia (NMIA) has developed a miniature crucible design suitable for measurement by both thermocouples and radiation thermometry, and has established an ensemble of five Co-C eutectic-point cells based on this design. The cells in this ensemble have been individually calibrated using both ITS-90 radiation thermometry and thermocouples calibrated on the ITS-90 by the NMIA mini-coil methodology. The assigned ITS-90 temperatures obtained using these different techniques are both repeatable and consistent, despite the use of different furnaces and measurement conditions. The results demonstrate that, if individually calibrated, such cells can be practically used as part of a national traceability scheme for thermocouple calibration, providing a useful intermediate calibration point between Cu and Pd.
Lead-bismuth eutectic as advanced reactor collant : operational experience
Woloshun, K. A. (Keith A.); Watts, V. (Valentina); Li, N. (Ning)
Some proposed advanced reactor concepts would be cooled by lead or lead-bismuth eutectic (LBE). An LBE test loop was designed and built at Los Alamos to develop the engineering and materials technology necessary to successfully implement LBE as a coolant (Fig. 1). Operational since December 2001, this test loop has been used to develop and demonstrate safe operation, oxygen concentration and metal corrosion control, instrumentation, thermal-hydraulic performance of heat exchangers and recuperators, and free convection and forced pumping. This paper discusses the technology development and lessons learned from the operation of this facility. A LBE test loop has been operational since December 2001. Using procedures, training, and engineering controls, this loop has operated without an accident. Continuous improvements in operation procedures and instrumentation over these years have resulted in a facility of high reliability, providing the groundwork for the use of LBE as a reactor coolant for temperatures up to 550 C.
Treatment of textile wastewaters using Eutectic Freeze Crystallization.
Randall, D G; Zinn, C; Lewis, A E
A water treatment process needs to recover both water and other useful products if the process is to be viewed as being financially and environmentally sustainable. Eutectic Freeze Crystallization (EFC) is one such sustainable water treatment process that is able to produce both pure ice (water) and pure salt(s) by operating at a specific temperature. The use of EFC for the treatment of water is particularly useful in the textile industry because ice crystallization excludes all impurities from the recovered water, including dyes. Also, EFC can produce various salts with the intention of reusing these salts in the process. This study investigated the feasibility of EFC as a treatment method for textile industry wastewaters. The results showed that EFC can be used to convert 95% of the wastewater stream to pure ice (98% purity) and sodium sulfate. PMID:25116506
Dr. Yaw D. Yeboah; Dr. Yong Xu; Dr. Atul Sheth; Dr. Pradeep Agrawal
The Gas Research Institute (GRI) estimates that by the year 2010, 40% or more of U.S. gas supply will be provided by supplements including substitute natural gas (SNG) from coal. These supplements must be cost competitive with other energy sources. The first generation technologies for coal gasification e.g. the Lurgi Pressure Gasification Process and the relatively newer technologies e.g. the KBW (Westinghouse) Ash Agglomerating Fluidized-Bed, U-Gas Ash Agglomerating Fluidized-Bed, British Gas Corporation/Lurgi Slagging Gasifier, Texaco Moving-Bed Gasifier, and Dow and Shell Gasification Processes, have several disadvantages. These disadvantages include high severities of gasification conditions, low methane production, high oxygen consumption, inability to handle caking coals, and unattractive economics. Another problem encountered in catalytic coal gasification is deactivation of hydroxide forms of alkali and alkaline earth metal catalysts by oxides of carbon (CO{sub x}). To seek solutions to these problems, a team consisting of Clark Atlanta University (CAU, a Historically Black College and University, HBCU), the University of Tennessee Space Institute (UTSI) and Georgia Institute of Technology (Georgia Tech) proposed to identify suitable low melting eutectic salt mixtures for improved coal gasification. The research objectives of this project were to: Identify appropriate eutectic salt mixture catalysts for coal gasification; Assess agglomeration tendency of catalyzed coal; Evaluate various catalyst impregnation techniques to improve initial catalyst dispersion; Determine catalyst dispersion at high carbon conversion levels; Evaluate effects of major process variables (such as temperature, system pressure, etc.) on coal gasification; Evaluate the recovery, regeneration and recycle of the spent catalysts; and Conduct an analysis and modeling of the gasification process to provide better understanding of the fundamental mechanisms and kinetics of the process.
Since the signing of 1987 Montreal Protocol, reducing and eliminating the use of harmful solvents has become an internationally imminent environmental protection mission. Solvent substitution is an effective way to achieve this goal. The Program for Assisting the Replacement of...
Role of solvent/non-solvent ratio on microsphere formation using the solvent removal method.
Godbee, J; Scott, E; Pattamunuch, P; Chen, S; Mathiowitz, E
The importance of good solvent concentration in the non-solvent mixture and the non-solvent viscosity on the ability to form microspheres using solvent removal process was investigated. The higher the viscosity of the polymer solutions, the higher the concentration of good solvent needed in the nonsolvent mixture to produce microspheres. This finding was due to faster precipitation of the polymer phase. Also, the addition of a model drug, fluorescein isothiocyanate conjugated-labelled bovine serum albumin, to the polymer solution (10% poly-L-lactic acid:poly(fumaric-co-sebacic) anhydride in methylene chloride) resulted in an overall lower polymer solution viscosity (15.5 cP with fluorescein isothiocyanate conjugated-labelled bovine serum albumin as compared with 18.25 cP for blank polymer at 25 degrees C). Additionally, the effect of good solvent concentration on non-solvent viscosity was evaluated, and the viscosity decreased as the concentration of good solvent increased. The effect of good solvent concentration on the non-solvent mixture on sphere formation was of great importance. Microspheres would not form when the good polymer solvent (methylene chloride) in the non-solvent phase was too low (below 175 ml for poly-L-lactic acid or 150 ml for poly(D,L-lactidco-glycolid)) or was replaced by another good solvent such as ethyl acetate, even though the same viscosity was achieved. It was shown that the concentration of the good solvent in the non-solvent mixture was more of a controlling factor than the viscosity of the non-solvent mixture in microsphere formation and the findings support the conclusion that diffusion is the main controlling parameter in solvent removal. PMID:15198427
PARIS II (the program for assisting the replacement of industrial solvents, version II), developed at the USEPA, is a unique software tool that can be used for customizing the design of replacement solvents and for the formulation of new solvents. This program helps users avoid ...
Effect of high magnetic fields on the microstructure in directionally solidified Bi Mn eutectic alloy
NASA Astrophysics Data System (ADS)
Li, Xi; Ren, Zhongming; Fautrelle, Yves
The eutectic Bi/MnBi alloy has been directionally solidified in the presence of an axial magnetic field to investigate the influence of high magnetic fields on the growth of eutectic Bi/MnBi. The morphology and magnetic properties of the specimens indicate that a high magnetic field promotes the formation of MnBi fiber and makes the directional solidification structure of the eutectic more regular. The MnBi inter-rod spacing and rod diameters gradually increase with the magnetic field intensity. Furthermore, the magnetic field enhances the faceted growth of MnBi phase and the magnetic coercivities of the alloy. This may be attributed to the magnetic anisotropy and the shift of the eutectic point by the magnetic field.
Pre-eutectic densification in MgF/sub 2/-CaF/sub 2/
Hu, S C; De Jonghe, L C
Increased densification rates were found as much as 200/sup 0/C below the eutectic temperature (980/sup 0/C) for MgF/sub 2/ containing small amounts of CaF/sub 2/. Constant heating rate and constant temperature sintering data, as well as microstructural developments indicated that solid state grain-boundary transport rates had been enhanced by the eutectic forming additive. The effect saturated at about 1 wt % CaF/sub 2/. The results suggest that densification of ceramic powders could be favorably affected without a substantial increase in the grain growth rate, by the addition of small amounts of eutectic forming additives, and sintering below the eutectic temperature. 6 figures.
Effect of boron on the microstructure of near-eutectic Al-Si alloys
Wu Yuying [Key Laboratory of Materials Liquid Structure and Heredity, Ministry of Education, Shandong University, Jinan 250061, Shandong (China)]. E-mail: firstname.lastname@example.com; Liu Xiangfa [Key Laboratory of Materials Liquid Structure and Heredity, Ministry of Education, Shandong University, Jinan 250061, Shandong (China); Bian Xiufang [Key Laboratory of Materials Liquid Structure and Heredity, Ministry of Education, Shandong University, Jinan 250061, Shandong (China)
The effect of boron on the microstructure of a near-eutectic Al-Si alloy (ZL109) was investigated by scanning electron microscopy (SEM) and electron beam microprobe analysis (EPMA). It was found that {alpha}-Al dendrites and eutectic clusters were significantly refined by the addition of boron. Another interesting discovery is that the near-eutectic alloy exhibited hypereutectic structure characteristics when the level of boron added exceeds 0.3%, i.e., primary Si is precipitated in the eutectic microstructure. A new type of nucleation substrate for the primary Si is found, Al {sub x}Ca {sub m}B {sub n}Si. This appears to be the main reason for the precipitation of primary Si.
Study of uranium solubility in gallium-indium eutectic alloy by emf method
NASA Astrophysics Data System (ADS)
Volkovich, V. A.; Maltsev, D. S.; Yamshchikov, L. F.; Osipenko, A. G.; Raspopin, S. P.; Kormilitsyn, M. V.
Activity, activity coefficients and solubility of uranium in Ga-In eutectic alloy as well as activity of uranium in U-Ga and U-In alloys were determined between 573 and 1073 K using electromotive force (emf) method.
Phase composition, microstructure and electrical properties of alumina-zirconia eutectic composites
R. ?i?ka; V. Trnovcovß; M. Yu Starostin
Oxide eutectic composites prepared by a directional solidification are noticeable for their good mechanical properties and\\u000a high temperature stability in oxidizing environments. In this paper we study the influence of stabilizers (Y, Sc) on the phase\\u000a composition, microstructure and electrical properties of Al2O3 - ZrO2 eutectic composites. At a hypereutectic composition of the melt, we have prepared the composites with
Fracture behavior of directionally solidified YŌAlŌOŌüŌ\\/AlŌOŌ eutectic fiber
Jenn-Ming Yang; S. M. Jeng; Sekyung Chang
The strength and fracture of a directionally solidified YŌAlŌOŌüŌ\\/AlŌOŌ eutectic fiber were investigated. The fiber was grown continuously by an edge-defined film-fed growth technique. The microstructure was characterized using X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The tensile strength and Weibull`s modulus of the eutectic fibers were determined in the as-fabricated state and after extended thermal exposure at 1,460
Deformation and fracture of a directionally solidified NiAl28Cr6Mo eutectic alloy
X. F. Chen; D. R. Johnson; R. D. Noebe; B. F. Oliver
A directionally solidified alloy based on the NiAl-(Cr, Mo) eutectic was examined by transmission and scanning electron microscopy to characterize the microstructure and room temperature deformation and fracture behavior. The microstructure consisted of a lamellar morphology with a group of zone axes (111) growth direction for both the NiAl and (Cr, Mo) phases. The interphase boundary between the eutectic phases
The aging response of Al-Cu and Al-Cu-Mg directionally solidified eutectics
C. G. Rhodes; G. Garmong
The microstructure and mechanical properties of directionally solidified Al-Cu eutectic and the microstructure of directionally\\u000a solidified Al-Cu-Mg eutectic alloys have been studied in as-grown, quenched, and aged conditions. In both systems the microstructure\\u000a of the aluminum-rich ? phase responded to aging treatments in a manner like that of dilute alloys of comparable composition.\\u000a The cooling rate of the alloys from
Microstructure and crystallographic orientation relationship in directionally solidified Mg¢Mg 17Al 12eutectic
Sigrid Guldberg; Nils Ryum
The microstructure and crystallographic orientation relationship of the Mg- and the Mg17Al12-phase in a directionally solidified Mg¢Al-eutectic have been study in the light microscope and in the scanning electron microscope equipped with an electron back scattering facility. The effects of the addition of small amounts of Sr on the microstructure were also studied. The Mg¢Al-eutectic solidified with a lamellar morphology
Suppression of ambient temperature creep by eutectic phase for hexagonal close-packed metal
NASA Astrophysics Data System (ADS)
Matsunaga, Tetsuya; Abe, Tomonori; Itoh, Shun; Satoh, Yuhki; Abe, Hiroaki
Zr-Si alloys were designed to contain eutectic phase surrounding the parent phase to suppress creep behavior of claddings. Creep tests conducted at 294-573 K showed that creep behavior was inhibited and that the creep failure time of new Zr alloy became longer than that of a conventional alloy: Zircaloy-4. Results show that the eutectic phase can suppress creep at operating temperatures prevailing in current nuclear power plants.
The Thermodynamic Analysis of Chemistry Stability of Eutectic Salt Phase Change Materials
Jun Chen; Jin Wang; Jin Song Liu; Jian Hua Liu
This paper analyses the chemistry stability of eutectic salt phase change materials according to chemical thermodynamic principle, and introduces the methods and steps of thermodynamic calculation and analysis during the process of confecting eutectic salt materials. The paper takes thermodynamic calculation according to the two phase-change materials, Na2CO3-SiO2 and Na2SO4-SiO2. By comparing the relational graph of Gibbs free energy and
Eutectic structures in friction spot welding joint of aluminum alloy to copper
Shen, Junjun, E-mail: firstname.lastname@example.com; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; Santos, Jorge F. dos [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Materials Mechanics, Solid-State Joining Processes, Max-Planck-Str. 1, 21502 Geesthacht (Germany)
A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl{sub 2} eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.
Effect of erbium on properties and microstructure of Al-Si eutectic alloy
Pengfei XING; Bo GAO; Yanxin ZHUANG; Kaihua LIU; Ganfeng TU
Eutectic Al-12.6 wt.%Si alloys with various contents of the rare earth element Er were prepared by the conventional casting technique. The effect of Er on the microstructure and properties of the eutectic Al-Si alloys was investigated using optical microscopy, scanning electron microscopy as well as the friction and wear tests. It was found that the addition of Er obviously improved
Distribution behavior of plutonium and americium in LiCl¢KCl eutectic\\/liquid cadmium systems
Y Sakamura; O Shirai; T Iwai; Y Suzuki
The thermodynamics of plutonium and americium in LiCl¢KCl eutectic\\/liquid cadmium systems was studied with interest in the oxidation state of americium in the salt phase. The standard potential of plutonium vs. the Ag\\/AgCl (1 wt% AgCl) electrode, E0Pu\\/Pu(III), in the LiCl¢KCl eutectic was measured in the temperature range of 400¢500░C and given by the equation with a standard deviation, ?=0.0009
Eutectic structures in friction spot welding joint of aluminum alloy to copper
NASA Astrophysics Data System (ADS)
Shen, Junjun; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; dos Santos, Jorge F.
A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl2 eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.
Localized silicon fusion and eutectic bonding for MEMS fabrication and packaging
Y. T. Cheng; Liwei Lin; Khalil Najafi
Silicon fusion and eutectic bonding processes based on the technique of localized heating have been successfully demonstrated. Phosphorus-doped polysilicon and gold films are applied separately in the silicon-to-glass fusion bonding and silicon-to-gold eutectic bonding experiments. These films are patterned as line-shape resistive heaters with widths of 5 or 7 ?m for the purpose of heating and bonding. In the experiments,
On the properties of the eutectic alloy Al 3(Nb,Cr) + Cr(Al,Nb)
S. A. Souza; P. L. Ferrandini; E. A. Souza; A. O. dos Santos; R. Caram
The eutectic alloy Al3(Nb,Cr)+Cr(Al,Nb) forms an in situ composite and the Al3Nb presents high specific strength and low oxidation rate that may be improved by the combination with other phases. The purpose of this work is to investigate physical, mechanical and oxidation properties of the eutectic alloy. Therefore, Rietveld analysis was carried out for furnace cooled and water quenched samples
Directional solidification and characterization of the Cd¢Sn eutectic alloy
E. Ūad?rl?; H. Kaya; M. G³nd³z
The Cd¢67.8wt.% Sn eutectic alloy was prepared by melting together appropriate amounts of cadmium and tin (both of 99.99% purity) in a graphite crucible in a vacuum melting furnace. Then, this eutectic alloy was poured into graphite crucibles in a hot filling furnace and the samples were solidified. These samples were directionally solidified upward with different growth rate ranges (8.1¢165?m\\/s)
Hazardous solvent substitution
Twitchell, K.E.
Eliminating hazardous solvents is good for the environment, worker safety, and the bottom line. However, even though we are motivated to find replacements, the big question is `What can we use as replacements for hazardous solvents?`You, too, can find replacements for your hazardous solvents. All you have to do is search for them. Search through the vendor literature of hundreds of companies with thousands of products. Ponder the associated material safety data sheets, assuming of course that you can obtain them and, having obtained them, that you can read them. You will want to search the trade magazines and other sources for product reviews. You will want to talk to users about how well the product actually works. You may also want to check US Environmental Protection Agency (EPA) and other government reports for toxicity and other safety information. And, of course, you will want to compare the product`s constituent chemicals with the many hazardous constituency lists to ensure the safe and legal use of the product in your workplace.
Walker, D; Samuel Fink, S
Southwest Research Institute (SwRI) conducted a burn test of the Caustic-Side Solvent Extraction (CSSX) solvent to determine the combustion products. The testing showed hydrogen fluoride gas is not a combustion product from a solvent fire when up to 70% of the solvent is consumed. The absence of HF in the combustion gases may reflect concentration of the modifier containing the fluoride groups in the unburned portion. SwRI reported results for other gases (CO, HCN, NOx, formaldehyde, and hydrocarbons). The results, with other supporting information, can be used for evaluating the consequences of a facility fire involving the CSSX solvent inventory.
Laser-Induced Melting of Co-C Eutectic Cells as a New Research Tool
NASA Astrophysics Data System (ADS)
van der Ham, E.; Ballico, M.; Jahan, F.
A new laser-based technique to examine heat transfer and energetics of phase transitions in metal-carbon fixed points and potentially to improve the quality of phase transitions in furnaces with poor uniformity is reported. Being reproducible below 0.1 K, metal-carbon fixed points are increasingly used as reference standards for the calibration of thermocouples and radiation thermometers. At NMIA, the Co-C eutectic point is used for the calibration of thermocouples, with the fixed point traceable to the International Temperature Scale (ITS-90) using radiation thermometry. For thermocouple use, these cells are deep inside a high-uniformity furnace, easily obtaining excellent melting plateaus. However, when used with radiation thermometers, the essential large viewing cone to the crucible restricts the furnace depth and introduces large heat losses from the front furnace zone, affecting the quality of the phase transition. Short {CO}2 laser bursts have been used to illuminate the cavity of a conventional Co-C fixed-point cell during various points in its melting phase transition. The laser is employed to partially melt the metal at the rear of the crucible providing a liquid-solid interface close to the region being observed by the reference pyrometer. As the laser power is known, a quantitative estimate of (166 ▒ 30) { J}{\\cdot }{g}^{-1} can be made for the Co-C latent heat of fusion. Using a single laser pulse during a furnace-induced melt, a plateau up to 8 min is observed before the crucible resumes a characteristic conventional melt curve. Although this plateau is satisfyingly flat, well within 100 mK, it is observed that the plateau is laser energy dependent and elevates from the conventional melt "inflection-point" value.
Production of low-density poly (4-methyl-1-pentene) foam via phase inversion from binary solvent/nonsovent systems
Simandl, R.F.; Robinson, D.N.; Bolinger, W.L.; Davis, W.E.
Phase inversion from durene/naphthalene, durene/tmpdo, and durene/hexadecanol binary solvent/nonsolvent systems produced well interconnected, radiographically homogeneous, open-celled poly (4- methyl-1-pentene) or pmp foams. These foams ranged in density from 5 to 50 mg/cm{sup 2}. Foam homogeneity and casting efficiency were dependent on casting scheme, durene quality, solvent-to-nonsolvent ratio, and quench temperature. Foam density tracked linearly with dissolved-polymer content. Homogeneous, ultralow-density (5 to 6 mg/cm{sup 3}) foams were produced by using a 49/51 durene/naphthalene solvent eutectic. Foam hardness or firmness tracked somewhat linearly with foam density. Foams with densities above 20 mg/cm{sup 3} were too fragile to handle without damage.
Microstructures from a directionally solidified NiAl-Cr eutectic deformed at room temperature
Chen, X.F.; Johnson, D.R.; Oliver, B.F. (Univ. of Tennessee, Knoxville, TN (United States). Material Science and Engineering Dept.)
Directionally solidified alloys based on the NiAl-Cr eutectic have shown promise as high temperature structural materials. This eutectic is characterized by a fibrous microstructure consisting of chromium rods embedded within a NiAl matrix. The reinforcing metal phase provides improvements in the elevated temperature strength and the room temperature fracture toughness of the NiAl matrix. The fracture toughness of the NiAl-Cr eutectic is much greater than that of NiAl. The directionally solidified NiAl-Cr eutectic has a fracture toughness of approximately 18--21 MPa[radical]m while polycrystalline NiAl has a fracture toughness of 6 MPa[radical]m. Single crystals of NiAl oriented with a [001] notch plane have a fracture toughness of 8 MPa[radical]m. Recently, the fracture resistance of fibrous NiAl-refractory metal eutectics has been described by crack trapping and crack bridging mechanisms. However, mechanical property data for NiAl-Cr eutectic are sparse, especially those generated at room temperature. Typically, the fracture behavior is characterized by scanning electron microscopy (SEM) and optical microscopy. To complement these existing data, observations of the deformation and fracture behavior by transmission electron microscopy (TEM) are reported here.
Gravity-induced anomalies in interphase spacing reported for binary eutectics.
Smith, Reginald W
It has been reasoned that desirable microstructural refinement in binary eutectics could result from freezing in reduced-gravity. It is recognized that the interphase spacing in a binary eutectic is controlled by solute transport and that, on Earth, buoyancy-driven convection may enhance this. Hence, it has been presumed that the interphase spacing ought to decrease when a eutectic alloy is frozen under conditions of much-reduced gravity, where such buoyancy effects would be largely absent. The result of such speculation has been that many workers have frozen various eutectics under reduced gravity and have reported that, although some eutectics became finer, others showed no change, and some even became coarser. This reported varied behavior will be reviewed in the light of long term studies by the author at Queen's University, including recent microgravity studies in which samples of two eutectic alloy systems, MnBi-Bi and MnSb-Sb, were frozen under very stable conditions and showed no change in interphase spacing. PMID:12446324
Thermal storage in ammonium alum/ammonium nitrate eutectic for solar space heating applications
Jotshi, C.K.; Hsieh, C.K.; Goswami, D.Y.; Klausner, J.F.; Srinivasan, N. [Univ. of Florida, Gainesville, FL (United States). Dept. of Mechanical Engineering
Ammonium alum and ammonium nitrate in the weight ratio of 1:1 form a eutectic that melts at 53 C and solidifies at 48 C. The thermophysical properties of this eutectic were measured in detail and the eutectic was found to have properties desirable for energy storage for solar space heating applications. The eutectic was encapsulated in 0.0254-m diameter high-density polyethylene (HDPE) balls and packed into a cylindrical bed in a scale model for testing its heat transfer characteristics when exposed to an air flow. Test results indicate that the thermal extraction efficiency of the model was 89% with an uncertainty of {+-} 8.0%. The packed bed had a Stanton number value in close agreement with that predicted with an empirical equation for sensible heat extraction from the eutectic in the solid phase. This Stanton number was increased by about 74% for sensible heat extraction from the eutectic in the liquid phase, a phenomenon not previously reported in the literature.
Directionally solidified pseudo-binary eutectics of Ni-Cr-(Hf, Zr)
NASA Technical Reports Server (NTRS)
Kim, Y. G.; Ashbrook, R. L.
A pseudo-binary eutectic, in which the intermetallic Ni7Hf2 reinforces the Ni-Cr solid solution phase, was previously predicted in the Ni-Cr-Hf system by a computer analysis. The experimental determination of pseudo binary eutectic compositions and the directional solidification of the Ni-Cr-Hf, Zr, and Ni-Cr-Zr eutectic alloys are discussed. To determine unknown eutectics, chemical analyses were made of material bled from near eutectic ingots during incipient melting. Nominal compositions in weight percent of Ni-18.6Cr-24.0HF, Ni19.6Cr-12.8Zr-2.8Hf, and Ni-19.2Cr-14.8Zr formed aligned pseudo-binary eutectic structures. The melting points were about 1270 C. The reinforcing intermetallic phases were identified as noncubic (Ni,Cr)7Hf2 and (Ni,Cr)7(Hf,Zr)2, and face centered cubic (Ni,Cr)5Zr. The volume fraction of the reinforcing phases were about 0.5.
Formation mechanism of primary phases and eutectic structures within undercooled Pb-Sb-Sn ternary alloys
NASA Astrophysics Data System (ADS)
Wang, Weili; Dai, Fuping; Wei, Bingbo
The solidification characteristics of three types of Pb-Sb-Sn ternary alloys with different primary phases were studied under substantial undercooling conditions. The experimental results show that primary (Pb) and SbSn phases grow in the dendritic mode, whereas primary (Sb) phase exhibits faceted growth in the form of polygonal blocks and long strips. (Pb) solid solution phase displays strong affinity with SbSn intermetallic compound so that they produce various morphologies of pseudobinary eutectics, but it can only grow in the divorced eutectic mode together with (Sb) phase. Although (Sb) solid solution phase and SbSn intermetallic compound may grow cooperatively within ternary eutectic microstructures, they seldom form pseudobinary eutectics independently. The (Pb)+(Sb)+SbSn ternary eutectic structure usually shows lamellar morphology, but appears as anomalous eutectic when its volume fraction becomes small. EDS analyses reveal that all of the three primary (Pb), (Sb) and SbSn phases exhibit conspicuous solute trapping effect during rapid solidification, which results in the remarkable extension of solute solubility.
Fractal characteristic of laser zone remelted Al 2O 3/YAG eutectic in situ composite
NASA Astrophysics Data System (ADS)
Zhang, Jun; Su, Haijun; Tang, Bo; Liu, Lin; Fu, Hengzhi
Directionally solidified alumina-based eutectic in situ composite has complex, irregular and self-similar microstructure composed of two or more phases to form three dimensionally interpenetrating network as "Chinese Script" type structure. In this paper, the fractal analysis is applied to Al 2O 3/Y 3Al 5O 12 (YAG) eutectic in situ composite prepared by laser zone remelting in order to quantitatively characterize the microstructure morphology and mechanical property. The fractal dimension of the eutectic microstructure is determined by the box counting technique according to the scanning electron microscope micrograph. The relationships between the fractal dimension and the laser processing parameter, eutectic spacing, and mechanical properties are studied. The results indicate that the eutectic morphology of Al 2O 3/YAG in situ composite has typical fractal characteristic. The fractal dimension changes from 1.61 to 1.82 when the laser-scanning rate increases from 10 to 400 ?m/s. With the increase of the fractal dimension, the eutectic spacing decreases while the hardness and the fracture toughness all increase.
Directional solidification of Al2-Cu-Al and Al3-Ni-Al eutectics during TEXUS rocket flight
NASA Technical Reports Server (NTRS)
Favier, J. J.; Degoer, J.
One lamellar eutectic sample and one fiber-like eutectic sample were solidified directionally during the TEXUS-6 rocket flight. The microstructures and the results of the thermal analysis, obtained from the temperatures recorded on the cartridge skin, are compared. No appreciable modifications of the regularity of the eutectic structures were observed by passing from 1 g to 0.0001 g in these experiments. No steady state growth conditions were achieved in these experiments.
Interphase anisotropy effects on lamellar eutectics: a numerical study.
Ghosh, Supriyo; Choudhury, Abhik; Plapp, Mathis; Bottin-Rousseau, Sabine; Faivre, Gabriel; Akamatsu, SilvĶre
In directional solidification of binary eutectics, it is often observed that two-phase lamellar growth patterns grow tilted with respect to the direction z of the imposed temperature gradient. This crystallographic effect depends on the orientation of the two crystal phases ? and ? with respect to z. Recently, an approximate theory was formulated that predicts the lamellar tilt angle as a function of the anisotropy of the free energy of the solid(?)-solid(?) interphase boundary. We use two different numerical methods-phase field (PF) and dynamic boundary integral (BI)-to simulate the growth of steady periodic patterns in two dimensions as a function of the angle ?(R) between z and a reference crystallographic axis for a fixed relative orientation of ? and ? crystals, that is, for a given anisotropy function (Wulff plot) of the interphase boundary. For Wulff plots without unstable interphase-boundary orientations, the two simulation methods are in excellent agreement with each other and confirm the general validity of the previously proposed theory. In addition, a crystallographic "locking" of the lamellae onto a facet plane is well reproduced in the simulations. When unstable orientations are present in the Wulff plot, it is expected that two distinct values of the tilt angle can appear for the same crystal orientation over a finite ?(R) range. This bistable behavior, which has been observed experimentally, is well reproduced by BI simulations but not by the PF model. Possible reasons for this discrepancy are discussed. PMID:25768518
The effect of porosity and gamma-gamma-prime eutectic content on the fatigue behavior of hydrogen charged PWA 1480
NASA Technical Reports Server (NTRS)
Gayda, J.; Dreshfield, R. L.; Gabb, T. P.
The study addresses the effect of systematically varying gamma-gamma-prime eutectic content and porosity level on the fatigue life of a hydrogen-charged single crystal PWA 1480 superalloy. Four microstructural variants are produced, and differences in gamma-gamma-prime eutectic morphology among the four processing variants are analyzed. Single valued tensile test data indicate that the tensile and yield strength of the PWA 1480 are degraded by hydrogen charging, with the exception of the material given a eutectic solution treatment. It is shown that the reduction of the fatigue life can be minimized by a duplex thermomechanical treatment consisting of a eutectic solution followed by hot isostatic pressing.
Deep Web 100872 Deep Web Web Deep Web Web Web Deep Web Deep Web TP391 A Uncertain Schema Matching in Deep Web Integration Service JIANG Fang-Jiao MENG Xiao-Feng JIA Lin-Lin (School of Information, Renmin University of China, Beijing, 100872) Abstract: With increasing of Deep Web, providing
Solvent Blending Strategy to Upgrade MCU CSSX Solvent to Equivalent Next-Generation CSSX Solvent
Delmau, Laetitia Helene [ORNL; Moyer, Bruce A [ORNL
The results of the present study have validated an equal-volume blending strategy for upgrading freshly prepared CSSX solvent to a blended solvent functionally equivalent to NG-CSSX solvent. It is shown that blending fresh CSSX solvent as currently used in MCU with an equal volume of an NG-CSSX solvent concentrate of appropriate composition yields a blended solvent composition (46.5 mM of MaxCalix, 3.5 mM of BOBCalixC6, 0.5 M of Cs-7SB, 3 mM of guanidine suppressor, and 1.5 mM of TOA in Isopar L) that exhibits equivalent batch ESS performance to that of the NG-CSSX solvent containing 50 mM of MaxCalix, 0.5 M of Cs-7SB, and 3 mM of guanidine suppressor in Isopar L. The solvent blend composition is robust to third-phase formation. Results also show that a blend containing up to 60% v/v of CSSX solvent could be accommodated with minimal risk. Extraction and density data for the effect of solvent concentration mimicking diluent evaporation or over-dilution of the equal-volume blended solvent are also given, providing input for setting operational limits. Given that the experiments employed all pristine chemicals, the results do not qualify a blended solvent starting with actual used MCU solvent, which can be expected to have undergone some degree of degradation. Consequently, further work should be considered to evaluate this risk and implement appropriate remediation if needed.
Special Experiment in Solvent ExtractionĀ
count by 30 to 40 counts per minute (So80; p. 251). Polyethylene vials may distort or swell when used with toluene or similar aromatic solvents, but are suitable for use with dioxane solvents. A complete discussion of sample preparation techniques... sequence of events in which emitted P particles collide with solvent molecules thus causing ionization and/or excitation of the atoms and molecules involved. When the ionized or excited products return to a gmund state of energy (or recombine) energy...
A quantitative study of factors influencing lamellar eutectic morphology during solidification
NASA Technical Reports Server (NTRS)
Kaukler, W. F. S.
The factors that influence the shape of the solid-liquid interface of a lamellar binary eutectic alloy are evaluated. Alloys of carbon tetrabromide and hexachloroethane which serve as a transparent analogue of lamellar metallic eutectics are used. The observed interface shapes are analyzed by computer-aided methods. The solid-liquid interfacial free energies of each of the individual phases comprising the eutectic system are measured as a function of composition using a 'grain boundary groove' technique. The solid-liquid interfacial free energy of the two phases are evaluated directly from the eutectic interface. The phase diagram for the system, the heat of fusion as a function of composition, and the density as a function of composition are measured. The shape of the eutectic interface is controlled mainly by the solid-liquid and solid-solid interfacial free energy relationships at the interface and by the temperature gradient present, rather than by interlamellar diffusion in the liquid at the interface, over the range of growth rates studied.
Deformation and fracture of a directionally solidified NiAl-28Cr-6Mo eutectic alloy
NASA Technical Reports Server (NTRS)
Chen, X. F.; Johnson, D. R.; Noebe, R. D.; Oliver, B. F.
A directionally solidified alloy based on the NiAl-(Cr, Mo) eutectic was examined by transmission and scanning electron microscopy to characterize the microstructure and room temperature deformation and fracture behavior. The microstructure consisted of a lamellar morphology with a group of zone axes (111) growth direction for both the NiAl and (Cr, Mo) phases. The interphase boundary between the eutectic phases was semicoherent and composed of a well-defined dislocation network. In addition, a fine array of coherent NiAl precipitates was dispersed throughout the (Cr, Mo) phase. The eutectic morphology was stable at 1300 K with only coarsening of the NiAl precipitates occurring after heat treatment for 1.8 ks (500 h). Fracture of the aligned eutectic is characterized primarily by a crack bridging/renucleation mechanism and is controlled by the strength of the semicoherent interface between the two phases. However, contributions to the toughness of the eutectic may arise from plastic deformation of the NiAl phase and the geometry associated with the fracture surface.
Deformation and fracture of a directionally solidified NiAl-28Cr-6Mo eutectic alloy
Chen, X.F.; Johnson, D.R.; Noebe, R.D.; Oliver, B.F.
A directionally solidified alloy based on the NiAl-(Cr, Mo) eutectic was examined by transmission and scanning electron microscopy to characterize the microstructure and room temperature deformation and fracture behavior. The microstructure consisted of a lamellar morphology with a group of zone axes (111) growth direction for both the NiAl and (Cr, Mo) phases. The interphase boundary between the eutectic phases was semicoherent and composed of a well-defined dislocation network. In addition, a fine array of coherent NiAl precipitates was dispersed throughout the (Cr, Mo) phase. The eutectic morphology was stable at 1300 K with only coarsening of the NiAl precipitates occurring after heat treatment for 1.8 ks (500 h). Fracture of the aligned eutectic is characterized primarily by a crack bridging/renucleation mechanism and is controlled by the strength of the semicoherent interface between the two phases. However, contributions to the toughness of the eutectic may arise from plastic deformation of the NiAl phase and the geometry associated with the fracture surface.
Thermal storage in ammonium alum/ammonium nitrate eutectic for solar space heating
Goswami, D.Y.; Jotshi, C.K.; Klausner, J.F.; Hsieh, C.K.; Srinivasan, N. [Univ. of Florida, Gainesville, FL (United States). Dept. of Mechanical Engineering
Ammonium alum and ammonium nitrate in the weight ratio of 1:1 forms a eutectic that melts at 53 C and crystallizes at 48 C. The latent heat of fusion of this eutectic was found to be 215 kJ/kg. Its enthalpy as measured by drop calorimetry was found to be 287 kJ/kg in the temperature range of 24--65 C, which is 1.67 times greater than water (172.2 kJ/kg) and 8.75 times greater than rock (32.8 kJ/kg). Upon several heating/cooling cycles, phase separation was observed. However, by adding 5% attapulgite clay to this eutectic mixture, phase separation was prevented. This eutectic was encapsulated in 0.0254m diameter HDPE hollow balls and subjected to about 1,100 heating/cooling cycles in the temperature range between 25 and 65 C. At the end of these cycles, the decrease in enthalpy was found to be 5%. A scale model of the heat storage unit was fabricated to investigate the heat transfer characteristics of this eutectic encapsulated in HDPE balls. The thermal extraction efficiency of the system was measured with the recirculation of hot air during charging and was found to be in the range of 85--98%.
Melts microheterogeneity in binary metallic systems having eutectic and monotectic transformations
NASA Astrophysics Data System (ADS)
Zhukova, L. A.; Aksyonova, O. P.; Zhukov, A. A.
The distinctive features of limited solubility in liquid eutectic and monotectic metallic systems have been discovered. The monodispersed emulsion model has been elaborated for a description of the specific microheterogeneous structure of eutectic melts. It includes the transitional shells (TS) at the interface boundaries having the eutectic composition and the closest packing of atoms. By means of the thermodynamic analysis a possibility of a metastable equilibrium of the emulsion has been determined when dimensional and interface energy parameters of the emulsion adopt certain values. The metastable state is characterized by the colloidal sizes of disperse particles and the interface tension values typical for immiscible melts. The existence of the emulsion has been confirmed by the calorimetric experimental data on Sn-Pb and Al-Si systems. Structure factors and RDF's of the TS have been calculated by the original treatment of experimental diffraction data on Sn-Pb and Ag-Ge melts. The evidence of different microheterogeneity scales in liquid eutectic and monotectic systems has been obtained. From two immiscible phases only the liquid based on the light-melted metal shows the short-range microinhomogeneity and the second one is a homogeneous solution. So, the microheterogeneity in eutectic and monotectic melts has different nature.
Gupta, N.
In a radioactive material (RAM) packaging, the formation of eutectic at the Pu/SS (plutonium/stainless steel) interface is a serious concern and must be avoided to prevent of leakage of fissile material to the environment. The eutectic temperature for the Pu/SS is rather low (410 C) and could seriously impact the structural integrity of the containment vessel under accident conditions involving fire. The 9975 packaging is used for long term storage of Pu bearing materials in the DOE complex where the Pu comes in contact with the stainless steel containment vessel. Due to the serious consequences of the containment breach at the eutectic site, the Pu/SS interface temperature is kept well below the eutectic formation temperature of 410 C. This paper discusses the thermal models and the results for the extended fire conditions (1500 F for 86 minutes) that exist in a long term storage facility and concludes that the 9975 packaging Pu/SS interface temperature is well below the eutectic temperature.
Solvent substitution is an effective and useful means of eliminating the use of harmful solvents, but finding substitute solvents which are less harmful and as effective as currently used solvents presents significant difficulties. Solvent substitution is a form of reverse engin...
Solvent changeouts without plant shutdown
Vickery, D.J.; Campbell, S.W. (Taylor, Weiland and Associates, Inc., Potsdam, NY (US))
For reasons of greater selectivity, lower regeneration energy requirements, reduced corrosivity and possible greater amine stability, MDEA continues to replace DEA in numerous selective H/sub 2/S removal applications. Solvent changeouts from DEA to MDEA often require no equipment modification, yet they are generally achieved by shutting down the plant, draining the old solvent, cleaning, and finally recharging with MDEA. However, in at least one plant, solvent changeout was done on the fly simply by periodically making up normal DEA losses with MDEA until the plant was finally operating on MDEA alone. Gradual solvent changeouts have the advantages of no lost production, no disposal problems with the environmentally-hazardous old solvent, no use and subsequent disposal of cleaning agents, and no additional manpower requirements. An advanced flowsheet simulation capability can suggest when such a procedure is feasible and, when it is, plant simulation can help to ensure that the solvent changeout is done reliably and with no production or cost penalties. GASPLANT-PLUS(TM) is currently the only commercial simulator having formulated solvent (mixed amine) capabilities within a fully flexible flowsheeting environment. After highlighting its technical foundations, they will compare GASPLANT-PLUS predictions with some commercial plant data and, through examples, they will show how solvent changeouts can be done gradually, without plant shutdown.
Influence of microgravity on solidification behavior of Al-Al3Ni eutectic alloy
NASA Astrophysics Data System (ADS)
Huang, Q.; Luo, X.-H.; Li, Y.-Y.
Directional solidification experiments of Al-Al 3 Ni eutectic alloy were performed in the Multi-functional Crystal Growing Furnace on board the unmanned Chinese Shenzhou spacecraft and in the laboratory on earth respectively to compare their solidification behavior under microgravity and normal gravity conditions The specimens gained were investigated using metallographic SEM XRD and Image analysis techniques Many significant differences both macroscopic and microscopic were observed between the specimens solidified in space and on the earth Especially the mean inter-fiber spacing and spacing distribution range obtained under microgravity were found larger than those obtained under normal gravity An off-eutectic theory was tried to explain those differences and achieved a good agreement In combination with the analyses on reported experimental results in other works it could be deduced that the change of inter-fibre spacing of eutectic alloy with microgravity is determined by the alloy system
Magnetic properties of directionally solidified MnSb/Sb eutectic composite
Pan, Y.; Sun, G. [Southeast Univ., Nanjing (China). Dept. of Mechanical Engineering] [Southeast Univ., Nanjing (China). Dept. of Mechanical Engineering
MnSb is the only ferromagnetic compound in the first-row transition-metal antimonides; it is highly anisotropic and proposed to be an important magnetic material for a variety of potential applications. The controlled eutectics consisting of MnSb and other components may constitute functional in-situ composites without any contamination and wetting problem between the components because of multiphase cooperative growth. The anisotropic MnSb/Sb composite is expected to possess interesting magnetic properties if MnSb is embedded in a diamagnetic antimony matrix as regular eutectic by directional solidification. However, very little has been published on MnSb/Sb eutectic composites. In the composite, the shape, size, orientation and distribution of magnetic components are important parameters which determine the quality of the materials. Consideration of these factors leads to the investigation on the relationships between microstructure, magnetic property and temperature dependence of the property in this system.
Application of eutectic ceramic mixtures for the functional components of high temperature SOFC's
Gerk, C.; Willert-Porada, M.
A novel design for a high temperature SOFC, based on lamellar electrode-electrolyte segments obtained by solidification of an oxidic eutectic melt on an electrolyte substrate is presented. Such composite electrodes contain NiO or MnO - 8Y-ZrO{sub 2} lamellae, which after reduction/oxidation yield electrode-electrolyte lamellae with 1--2 {micro}m width and a vertical dimension of >100 {micro}m, depending upon the amount of eutectic melt solidified on a polycrystalline substrate. The nucleation of the eutectic on a polycrystalline substrate followed by a semi-directional crystallization of the two phases yields a gradient of 3-phase boundaries over the height of such an electrode, with the number of 3-phase boundaries increasing towards the substrate.
Revised form of Jackson¢Hunt theory: application to directional solidification of MnBi\\/Bi eutectics
L. L Zheng; D. J Larson Jr; H Zhang
A generalized eutectic theory, which defaults to the prior theories by Jackson¢Hunt and Trivedi et al. under their boundary conditions, has been developed to consider phase relations, solidification temperature and interface velocity over the entire parametric range, and for both lamellar and rod eutectic morphologies. The analytical solution reveals that ?2V and ??T, though varying with the Peclet number, are
Structural and phonon transmission study of Ge-Au-Ge eutectically bonded interfaces
Knowlton, W.B. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering]|[Lawrence Berkeley Lab., CA (United States). Materials Sciences Div.
This thesis presents a structural analysis and phonon transparency investigation of the Ge-Au-Ge eutectic bond interface. Interface development was intended to maximize the interfacial ballistic phonon transparency to enhance the detection of the dark matter candidate WIMPs. The process which was developed provides an interface which produces minimal stress, low amounts of impurities, and insures Ge lattice continuity through the interface. For initial Au thicknesses of greater than 1,000 {angstrom} Au per substrate side, eutectic epitaxial growth resulted in a Au dendritic structure with 95% cross sectional and 90% planar Au interfacial area coverages. In sections in which Ge bridged the interface, lattice continuity across the interface was apparent. Epitaxial solidification of the eutectic interface with initial Au thicknesses < 500 A per substrate side produced Au agglomerations thereby reducing the Au planar interfacial area coverage to as little as 30%. The mechanism for Au coalescence was attributed to lateral diffusion of Ge and Au in the liquid phase during solidification. Phonon transmission studies were performed on eutectic interfaces with initial Au thicknesses of 1,000 {angstrom}, 500 {angstrom}, and 300 {angstrom} per substrate side. Phonon imaging of eutectically bonded samples with initial Au thicknesses of 300 {angstrom}/side revealed reproducible interfacial percent phonon transmissions from 60% to 70%. Line scan phonon imaging verified the results. Phonon propagation TOF spectra distinctly showed the predominant phonon propagation mode was ballistic. This was substantiated by phonon focusing effects apparent in the phonon imaging data. The degree of interface transparency to phonons and resulting phonon propagation modes correlate with the structure of the interface following eutectic solidification. Structural studies of samples with initial Au thickness of 1,000 {angstrom}/side appear to correspond with the phonon transmission study.
Microstructural variations induced by gravity level during directional solidification of near-eutectic iron-carbon type alloys
NASA Astrophysics Data System (ADS)
Stefanescu, Doru M.; Curreri, Peter A.; Fiske, Michael R.
The effects of gravity on the microstructure of directionally solidified near-eutectic cast irons are studied, using a Bridgman-type automatic directional solidification furnace aboard a NASA KC-135 aircraft which flies parabolic arcs and generates alternating periods of low-g (0.01 to 0.001 g, 30 seconds long) and high-g (1.8 g, 1.5 minutes long). Results show a refinement of the interlamellar spacing of the eutectic during low-g processing of metastable Fe-C eutectic alloys. Low-g processing of stable Fe-C-Si eutectic alloys (lamellar or spheroidal graphite) results in a coarsening of the eutectic grain structure. Secondary dendrite arm spacing of austenite increases in low-g and decreases in high-g. The effectiveness of low-gravity in the removal of buoyancy-driven graphite phase segregation is demonstrated.
Numerical study of the effect of the shape of the phase diagram on the eutectic freezing temperature
Ode, M.; Shimono, M. [National Institute for Materials Science (NIMS), Tsukuba (Japan)] [National Institute for Materials Science (NIMS), Tsukuba (Japan); Sasajima, N.; Yamada, Y. [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ, AIST), Tsukuba (Japan)] [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ, AIST), Tsukuba (Japan); Bloembergen, P. [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ, AIST), Tsukuba, Japan and National Institute of Metrology, Beijing 100013 (China)] [National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ, AIST), Tsukuba, Japan and National Institute of Metrology, Beijing 100013 (China)
To evaluate the reliability of metal-carbon eutectic systems as fixed points for the next generation of high-temperature standards the effect of thermodynamic properties related to the shape of eutectic phase diagram on the freezing temperature is investigated within the context of the numerical multi-phase-field model. The partition coefficient and liquidus slopes of the two solids involved in the eutectic reaction are varied deliberately and independently. The difference between the eutectic temperature and the freezing temperature is determined in dependence of the solid/liquid (s/l) interface shape and concentration. Where appropriate reference is made to the Jackson-Hunt analytical theory. It is shown that there are mainly two typical conditions to decrease the undercooling: 1) a small liquidus slope and 2) the associated difference between the eutectic composition and the liquid composition during solidification.
Microstructural variations induced by gravity level during directional solidification of near-eutectic iron-carbon type alloys
NASA Technical Reports Server (NTRS)
Stefanescu, Doru M.; Fiske, Michael R.; Curreri, Peter A.
The effects of gravity on the microstructure of directionally solidified near-eutectic cast irons are studied, using a Bridgman-type automatic directional solidification furnace aboard a NASA KC-135 aircraft which flies parabolic arcs and generates alternating periods of low-g (0.01 to 0.001 g, 30 seconds long) and high-g (1.8 g, 1.5 minutes long). Results show a refinement of the interlamellar spacing of the eutectic during low-g processing of metastable Fe-C eutectic alloys. Low-g processing of stable Fe-C-Si eutectic alloys (lamellar or spheroidal graphic) results in a coarsening of the eutectic grain structure. Secondary dendrite arm spacing of austenite increases in low-g and decreases in high-g. The effectiveness of low-gravity in the removal of buoyancy-driven graphite phase segregation is demonstrated.
Eutectic Sn\\/Pb solder bump and under bump metallurgy: interfacial reactions and adhesion
Se-Young Jang; Kyung-Wook Paik
In flip-chip interconnection on organic substrates using eutectic tin\\/lead solder bumps, a highly reliable under bump metallurgy (UBM) is required to maintain adhesion and solder wettability. Various UBM systems such as 1?m Al\\/0.2?m Ti\\/5?m Cu, 1?m Al\\/02?m Ti\\/1?m Cu, 1?m Al\\/0.2?m Ni\\/1?m Cu and 1?m Al\\/0.2?m Pd\\/1?m Cu, applied under eutectic tin\\/lead solder bumps, have been investigated with regard to
The influences of convection on directional solidification of eutectic Bi/MnBi
NASA Technical Reports Server (NTRS)
Larson, David J., Jr.
Eutectic alloys of Bi-Mn were directionally solidified using the Bridgman-Stockbarger technique to determine the influences of gravitationally-driven thermo-solutal convection on the Bi-MnBi rod eutectic. Experiments were conducted that varied the level of convection by varying the growth parameters and growth orientation, by microgravity damping, by applied magnetic field damping, and by imposing forced convection. Peltier interface demarcation and in situ thermocouple measurements were used to monitor interface velocity and thermal gradient and to evaluate interface planarity.
To meet the great need of replacing many harmful solvents commonly used by industry and the public with environmentally benign substitute solvents, the PARIS II solvent design software has been developed. Although the difficulty of successfully finding replacements increases with...
LeCun, Yann; Bengio, Yoshua; Hinton, Geoffrey
Deep learning allows computational models that are composed of multiple processing layers to learn representations of data with multiple levels of abstraction. These methods have dramatically improved the state-of-the-art in speech recognition, visual object recognition, object detection and many other domains such as drug discovery and genomics. Deep learning discovers intricate structure in large data sets by using the backpropagation algorithm to indicate how a machine should change its internal parameters that are used to compute the representation in each layer from the representation in the previous layer. Deep convolutional nets have brought about breakthroughs in processing images, video, speech and audio, whereas recurrent nets have shone light on sequential data such as text and speech. PMID:26017442
SAGE is a comprehensive guide designed to provide pollution prevention information on solvent and process alternatives for parts cleaning and degreasing. SAGE does not recommend any ozone depleting chemicals. SAGE was developed by the Surface Cleaning Program at Research Triang...
Experimental Investigation of Evaporation Behavior of Polonium and Rare-Earth Elements in Lead-Bismuth Eutectic Pool
Shuji Ohno; Shinya Miyahara; Yuji Kurata [Japan Atomic Energy Agency (Japan); Ryoei Katsura [Nippon Nuclear Fuel Development Co., Ltd. (Japan); Shigeru Yoshida [KAKEN Co., Ltd. (Japan)
Equilibrium evaporation behavior was experimentally investigated for polonium ({sup 210}Po) in liquid lead-bismuth eutectic (LBE) and for rare-earth elements gadolinium (Gd) and europium (Eu) in LBE to understand and clarify the transfer behavior of toxic impurities from LBE coolant to a gas phase. The experiments utilized the 'transpiration method' in which saturated vapor in an isothermal evaporation pot was transported by inert carrier gas and collected outside of the pot. While the previous paper ICONE12-49111 has already reported the evaporation behavior of LBE and of tellurium in LBE, this paper summarizes the outlines and the results of experiments for important impurity materials {sup 210}Po and rare-earth elements which are accumulated in liquid LBE as activation products and spallation products. In the experiments for rare-earth elements, non-radioactive isotope was used. The LBE pool is about 330-670 g in weight and has a surface area of 4 cm x 14 cm. {sup 210}Po experiments were carried out with a smaller test apparatus and radioactive {sup 210}Po produced through neutron irradiation of LBE in the Japan Materials Testing Reactor (JMTR). We obtained fundamental and instructive evaporation data such as vapor concentration, partial vapor pressure of {sup 210}Po in the gas phase, and gas-liquid equilibrium partition coefficients of the impurities in LBE under the temperature condition between 450 and 750 deg. C. The {sup 210}Po test revealed that Po had characteristics to be retained in LBE but was still more volatile than LBE solvent. A part of Eu tests implied high volatility of rare-earth elements comparable to that of Po. This tendency is possibly related to the local enrichment of the solute near the pool surface and needs to be investigated more. These results are useful and indispensable for the evaluation of radioactive materials transfer to the gas phase in LBE-cooled nuclear systems. (authors)
Geometry Effects on the Electromigration of Eutectic SN\\/PB Flip-Chip Solder Bumps
Dennis H. Eaton; James D. Rowatt; Walter J. Dauksher
This work investigates the effect of passivation opening diameter and underbump metallization (UBM) diameter on the electromigration (EM) resistance of Sn\\/Pb eutectic solder bumps. For the bump geometries studied, the electromigration lifetime depends strongly on the UBM area but weakly on the passivation opening area. The applicability of Black's model for extrapolating lifetime from accelerated currents to operating currents is
Thermoelectric and morphological effects of peltier pulsing on directional solidification of eutectic Bi-Mn
R. P. Silberstein; D. J. Larson; B. Dressler
We have carried out extensive in situ thermal measurements during Peltier Interface Demarcation (PID) during directional solidification of eutectic Bi\\/MnBi. We have observed that significant thermal transients occur throughout the sample as a result of the Peltier pulsing. We have separated the contributions of the Peltier, Thomson, and Joule heats, and studied them as a function of pulse intensity and
Damage by eutectic particle cracking in aluminum casting alloys A356\\/357
Q. G. Wang; C. H. Caceres; J. R. Griffiths
The strain dependence of particle cracking in aluminum alloys A356\\/357 in the T6 temper has been studied in a range of microstructures produced by varying solidification rate and Mg content, and by chemical (Sr) modification of the eutectic silicon. The damage accumulates linearly with the applied strain for all microstructures, but the rate depends on the secondary dendrite arm spacing
A New Analytical Approach to Predict Spacing Selection in Lamellar and Rod Eutectic Systems
NASA Technical Reports Server (NTRS)
Catalina, Adrian V.; Sen, Subhayu; Stefanescu, Doru M.
The Jackson and Hunt (JH) theory has been modified to relax the assumption of isothermal solid liquid interface used in their treatment. Based on the predictions of this modified theory, the traditional definitions of regular and irregular eutectics are revised. For regular eutectics, the new model identifies a range of spacing within the limits defined by the minimum undercooling of the a and beta phases. For the irregular Al-Si eutectic system, two different spacing selection mechanisms were identified: (1) for a particular growth rate, a nearly isothermal interface can be achieved at a unique minimum spacing lambda (sub t); (2) the average spacing (lambda (sub av) greater than lambda (sub t) is essentially dictated by the undercooling of the faceted phase. Based on the modified theoretical model, a semiempirical expression has been developed to account for the influence of the temperature gradient, which is dominant in the irregular Al-Si system. The behavior of the Fe-Fe3C eutectic is also discussed. The theoretical calculations have been found to be in good agreement with the published experimental measurements.
A New Analytical Approach to Predict Spacing Selection in Lamellar and Rod Eutectic Systems
NASA Technical Reports Server (NTRS)
Catalina, Adrian V.; Sen, Subhayu; Stefanescu, D. M.; Curreri, Peter A. (Technical Monitor)
The Jackson and Hunt (JH) theory has been modified to relax the assumption of isothermal solid/liquid interface(SLI) used in their treatment. Based on the predictions of this modified theory the traditional definitions of regular and irregular eutectics are revised. For regular eutectics the new model identifies a range of spacing within the limits defined by the minimum undercooling of the alpha and beta phase. For the irregular Al-Si eutectic system two different spacing selection mechanisms were identified: a) for a particular growth rate, a nearly isothermal interface can be achieved at a unique minimum spacing lambda(sub I); b) the average spacing (lambda(sub av) greater than lambda(sub I)) is essentially dictated by the undercooling of the faceted phase. Based on the modified theoretical model a semiempirical expression has been developed to account for the influence of the temperature gradient, which is dominant in the irregular Al-Si system. The behavior of the Fe-Fe3C eutectic is also discussed The theoretical calculations have been found to be in good agreement with the published experimental measurements.
Regel, Liya L.
convection. Most experiments were performed on the MnBi-Bi eutectic. The rod spacing depended on the growth that directional solidification in microgravity caused a significant reduction in the fiber spacing of the MnBi experiments showed that the effect was real and reproducible [3-13]. Since Larson's ASTP experiment on Mn-Bi
Critical temperature of the leadbismuth eutectic (LBE) alloy Abdul-Majeed Azad *
Azad, Abdul-Majeed
; boiling point = 2022 K) and Pb (melting point = 600 K; boiling point = 1837 K) as well as the PbŁBi eutectic alloy (LBE, melting point = 396 K; boil- ing point = 1943 K) have been serious contenders for use neutron absorption and activation, high boiling point and poor interaction with water and air, etc
Damage by eutectic particle cracking in aluminum casting alloys A356/357
NASA Astrophysics Data System (ADS)
Wang, Q. G.; Caceres, C. H.; Griffiths, J. R.
The strain dependence of particle cracking in aluminum alloys A356/357 in the T6 temper has been studied in a range of microstructures produced by varying solidification rate and Mg content, and by chemical (Sr) modification of the eutectic silicon. The damage accumulates linearly with the applied strain for all microstructures, but the rate depends on the secondary dendrite arm spacing and modification state. Large and elongated eutectic silicon particles in the unmodified alloys and large ?-phase (Al9FeMg3Si5) particles in alloy A357 show the greatest tendency to cracking. In alloy A356, cracking of eutectic silicon particles dominates the accumulation of damage while cracking of Fe-rich particles is relatively unimportant. However, in alloy A357, especially with Sr modification, cracking of the large ?-phase intermetallics accounts for the majority of damage at low and intermediate strains but becomes comparable with silicon particle cracking at large strains. Fracture occurs when the volume fraction of cracked particles (eutectic silicon and Fe-rich intermetallics combined) approximates 45 pct of the total particle volume fraction or when the number fraction of cracked particles is about 20 pct. The results are discussed in terms of Weibull statistics and existing models for dispersion hardening.
Free energy change of off-eutectic binary alloys on solidification
NASA Technical Reports Server (NTRS)
Ohsaka, K.; Trinh, E. H.; Lin, J.-C.; Perepezko, J. H.
A formula for the free energy difference between the undercooled liquid phase and the stable solid phase is derived for off-eutectic binary alloys in which the equilibrium solid/liquid transition takes place over a certain temperature range. The free energy change is then evaluated numerically for a Bi-25 at. pct Cd alloy modeled as a sub-subregular solution.
Eutectic freeze crystallization in a new apparatus: the cooled disk column crystallizer
Frank van der Ham; Marcelo Martins Seckler; Geert Jan Witkamp
Eutectic freeze crystallization (EFC) is a technique for simultaneous crystallization of ice and salt that is energetically more efficient than conventional evaporative crystallization. In this paper, a new type of crystallizer is introduced for simultaneously conducting EFC and separating the ice from the salt crystals, the cooled disk column crystallizer (CDCC). Crystallization is achieved by indirect cooling with wiped disks
Eutectic freeze crystallization: Application to process streams and waste water purification
F. van der Ham; G. J. Witkamp; J. de Graauw; G. M. van Rosmalen
Two case studies are presented using eutectic freeze crystallization (EFC) as an alternative for evaporative crystallization: a 7.8 ton day?1 35 w% aqueous sodium nitrate and a 24 ton day?1 12 w% copper sulfate stream. The proposed crystallizer is a cooled disk column crystallizer (CDCC), using indirect cooling for heat transfer. In single stage operation, the formed ice crystals are
Quantitative modeling of diffusional coarsening in eutectic tin\\/lead solders
W. Dreyer
This paper presents a quantitative computer simulation of the coarsening phenomenon observed in eutectic tin\\/lead and other solder materials used for joining microelectronic components. The mathematical model is based on phase field theory and allows predicting the development of tin concentration over time within a representative volume element (RVE) of the solder. It accounts for the chemical free energy of
Experimental investigation of forced-convection heat-transfer characteristics of lead-bismuth eutectic
NASA Technical Reports Server (NTRS)
Lubarsky, Bernard
The forced-convection heat-transfer characteristics of lead-bismuth eutectic were experimentally investigated. Experimental values of Nusselt number for lead-bismuth fell considerably below predicted values. The addition of a wetting agent did not change the heat transfer characteristics.
Evaluation of magnesium-aluminum eutectic to improve combustion efficiency in low burning rate propellants
NASA Technical Reports Server (NTRS)
Northam, B. G.; Sullivan, E. M.
A previous investigation indicated that combustion efficiency of low burning-rate propellants could be improved if the aluminum fuel was replaced by aluminum particles coated with a magnesium-aluminum eutectic alloy (ALCAL). The purpose of the present investigation was to evaluate the possibility of improving the combustion efficiency of these propellants by admixing the eutectic with the aluminum rather than coating the aluminum. Tests of three propellants similar in every respect except for the metal fuel were conducted in test motors with 4.54 kg (10 lbm) of propellant. The first propellant used aluminum fuel; the second contained aluminum admixed with magnesium-aluminum eutectic; the third used ALCAL. The test results show the the admixed fuel gave better low burning-rate combustion efficiency than the other two. The test results also showed that the ALCAL was deficient in that much, if not all, of the coating material could be found as the fine particles in a bimodal mix of aluminum and eutectic. The combustion efficiency of low burning-rate aluminized propellants can be significantly improved by mixing a small amount of magnesium-aluminum alloy with the aluminum fuel.
The Effect of Silica Nanoparticles on Corrosion of Steel by Molten Carbonate Eutectics
Padmanaban Iyer, Ashwin
The effect of silica nanoparticles on corrosion of steel by molten carbonate eutectic (42.7 percent Li2CO3, K2CO3) was investigated. The experimental design was based on static coupon immersion methodology where a coupon (material under study...
High cycle fatigue of tantalum carbide reinforced nickel base eutectics at room temperature
D. E. Graham; D. A. Woodford
The high cycle fatigue response of two advanced tantalum carbide strengthened eutectic superalloys has been determined at room temperature. Since these alloys will be coated in service, the effects of variables associated with coating processes were given special attention. Both alloys showed a well defined fatigue limit. It was concluded that the maximum stress obtained in the cycle at the
Floreano, Dario
undercooling competition observed is confirmed by directional solidification and samples solidifiedGENERATION OF ULTRA-FINE EUTECTIC MICROSTRUCTURES IN AS-SOLIDIFIED METALS ╔tienne Landry-Dķsy1 Al-Cu-Si sample (600 Ąm thick) 2 1 DECREASING COOLING RATE The liquid directly contacting the cold
Mechanical Properties and Fracture Behavior of Directionally Solidified NiAl-V Eutectic Composites
NASA Astrophysics Data System (ADS)
Milenkovic, Srdjan; Caram, Rubens
Directional solidification of eutectic alloys has been recognized as promising technique for producing in situ composite materials exhibiting balance of properties. Therefore, an in situ NiAl-V eutectic composite has been successfully directionally solidified using Bridgman technique. The mechanical behavior of the composite including fracture resistance, microhardness, and compressive properties at room and elevated temperatures was investigated. Damage evolution and fracture characteristics were also discussed. The obtained results indicate that the NiAl-V eutectic retains high yield strength up to 1073 K (800 ░C), above which there is a rapid decrease in strength. Its yield strength is higher than that of binary NiAl and most of the NiAl-based eutectics. The exhibited fracture toughness of 28.5 MPa?m is the highest of all other NiAl-based systems investigated so far. The material exhibited brittle fracture behavior of transgranular type and all observations pointed out that the main fracture micromechanism was cleavage.
Studies of Al-Al 3Ni eutectic mixtures as insertion anodes in rechargeable lithium batteries
S. Machill; D. Rahner
This contribution will give a short overview of aluminium-nickel eutectic mixture alloys as the anode materials in lithium secondary batteries. These compounds allow to create an alloy matrix of modified grain size with stabilizing properties toward æmechanical stressingÆ during charge\\/discharge processes of lithium. Several electrochemical techniques have been used to investigate the electrochemical behaviour of these lithium-inserting materials.
Van Norman
Analyses for Zn(II) and Cd(II) in the fused lithium chloride - potassium ; chloride eutectic at 450 deg C were performed by controlled potential coulometric ; stripping of the predeposited metal from a bismuth pool electrode, and Ni(II) was ; determined by controlled potential stripping of the predeposited metal from a ; platinum gauze electrode. Analyses were performed with an
Hubbell, Joel M. (Idaho Falls, ID); Sisson, James B. (Idaho Falls, ID)
A deep lysimeter including a hollow vessel having a chamber, a fill conduit extending into the chamber through apertures, a semi-permeable member mounted on the vessel and in fluid communication with the fill conduit, and a line connection for retrieving the lysimeter.
NSDL National Science Digital Library
In this video a Penn State professor refers to National Park canyons carved out by water and wind as he explains ōdeep timeö - the notion that the earth is billions of years old; another professor states how the theory of evolution is supported by evidence of an ancient Earth recorded in rocks.
Nickel solubility limit in liquid lead-bismuth eutectic
NASA Astrophysics Data System (ADS)
Martinelli, L.; Vanneroy, F.; Diaz Rosado, J. C.; L'Hermite, D.; Tabarant, M.
In the framework of the Accelerator-Driven System (ADS), the Pb-Bi eutectic can be used as spallation target for neutron production. The Pb-Bi flow in contact with the ADS structural steels, T 91 (Fe-9Cr martensitic steel) and 316L (Fe-17Cr-10Ni austenitic steel), can dissolve the main steel components: iron, chromium and nickel. According to literature, in low oxygen containing Pb-Bi, the dissolution rates of 316L depend, at least, on the nickel solubility limit as it dissolves preferentially in the Pb-Bi alloy. Consequently, the determination of this physico-chemical data in the temperature range of the ADS operating conditions (350-450 ░C) is needed for the prediction of the corrosion rates in ADS. The nickel solubility limit in Pb-Bi is available in the literature from 400 ░C to 900 ░C but not for lower temperatures. However, the Ni-Bi phase diagram leads one to suppose that the nickel solubility limit law changes for lower temperatures. Consequently in this study, two experimental techniques have been implemented for the determination of the nickel solubility limit at low temperatures. The first one is performed from 400 ░C to 500 ░C using the Laser Induce Breakdown Spectroscopy (LIBS). The LIBS technique permits to obtain in situ measurements directly performed on liquid Pb-Bi. This characteristic is very interesting as it allows to monitor on line the concentration of the dissolved impurities in the liquid coolant. However, this technique is still under development and optimization on liquid Pb-Bi medium. The second technique is ICP-AES. This technique, commonly used to analyze alloys composition, is interesting as it permits a global analysis of a Pb-Bi sample. Moreover, the measurement made by ICP-AES is very reliable, very accurate and optimized for such analyses. However, this technique is ex situ; this is its main disadvantage. Experiments using ICP-AES were performed from 350 ░C to 535 ░C. The two techniques lead to the same solubility limit in their common temperature range. However, the experiment using ICP-AES technique revealed a change in the nickel solubility law for the temperatures lower than 415 ░C. Consequently, this study recommends the use of two solubility limits relations, which take into account these results, as well as the literature results: the solubility limits laws of Martynov and Rosenblatt. The nickel solubility limit can thus be expressed as: Log S(wt.%)=5.2▒0.12-{3500}/{T(K)} for the temperature range: 330-415 ░C. This law is the empirical solubility law obtained in this study at the low temperature range. Log S(wt.%)=1.7▒0.08-{1009}/{T(K)} for 415-900 ░C temperature range. This law is the linear regression made on the overall experimental points available in literature and in this study. According to the Martynov studies, it seems reliable up to 900 ░C.
Transient and steady state creep response of ice I and magnesium sulfate hydrate eutectic aggregates
McCarthy, C.; Cooper, R.F.; Goldsby, D.L.; Durham, W.B.; Kirby, S.H.
Using uniaxial compression creep experiments, we characterized the transient and steady state deformation behaviors of eutectic aggregates of system ice I and MgSO4 11H2O (MS11; meridianiite), which has significance because of its likely presence on moons of the outer solar system. Synthetic samples of eutectic liquid bulk composition, which produce eutectic colonies containing 0.35-0.50 volume fraction MS11, were tested as functions of colony size and lamellar spacing, temperature (230-250 K), and confining pressure (0.1 and 50 MPa) to strains ???0.2. Up to a differential stress of 6 MPa, the ice I-MS11 aggregates display an order of magnitude higher effective viscosity and higher stress sensitivity than do aggregates of pure polycrystalline ice at the same conditions. The creep data and associated microstructural observations demonstrate, however, that the aggregates are additionally more brittle than pure ice, approaching rate-independent plasticity that includes rupture of the hydrate phase at 6-8 MPa, depending on the scale of the microstructure. Microstructures of deformed samples reveal forms of semibrittle flow in which the hydrate phase fractures while the ice phase deforms plastically. Semibrittle flow in the icy shell of a planetary body would truncate the lithospheric strength envelope and thereby decrease the depth to the brittle-ductile transition by 55% and reduce the failure limit for compressional surface features from 10 to ???6 MPa. A constitutive equation that includes eutectic colony boundary sliding and intracolony flow is used to describe the steady state rheology of the eutectic aggregates. Copyright ?? 2011 by the American Geophysical Union.
Refinement of Eutectic Si in High Purity Al-5Si Alloys with Combined Ca and P Additions
NASA Astrophysics Data System (ADS)
Ludwig, Thomas Hartmut; Li, Jiehua; Schaffer, Paul Louis; Schumacher, Peter; Arnberg, Lars
The effects of combined additions of Ca and P on the eutectic Si in a series of high purity Al-5 wt pct Si alloys have been investigated with the entrained droplet technique and complementary sets of conventional castings. Differential scanning calorimetry (DSC) and thermal analysis were used to investigate the eutectic droplet undercooling and the recalescence undercooling, respectively. Optical microscopy, SEM, EPMA, and TEM were employed to characterize the resultant microstructures. It was found that 250 ppm Ca addition to Al-5Si wt pct alloys with higher P contents leads to a significant increase of the eutectic droplet undercooling. For low or moderate cooling rates, the TEM results underline that Ca additions do not promote Si twinning. Thus, a higher twin density cannot be expected in Ca containing Al-Si alloys after, e.g., sand casting. Consequently, a refinement of the eutectic Si from coarse flake-like to fine plate-like structure, rather than a modification of the eutectic Si to a fibrous morphology, was achieved. This strongly indicates that the main purpose of Ca additions is to counteract the coarsening effect of the eutectic Si imposed by higher P concentrations. Significant multiple Si twinning was observed in melt-spun condition; however, this can be attributed to the higher cooling rate. After DSC heating (slow cooling), most of Si twins disappeared. Thus, the well-accepted impurity-induced twinning mechanism may be not valid in the case of Ca addition. The possible refinement mechanisms were discussed in terms of nucleation and growth of eutectic Si. We propose that the pre-eutectic Al2Si2Ca phase and preferential formation of Ca3P2 deactivate impurity particles, most likely AlP, poisoning the nucleation sites for eutectic Si.
Computational comparison of oxidation stability: Solvent/salt monomers vs solvent-solvent/salt pairs
NASA Astrophysics Data System (ADS)
Kim, Dong Young; Park, Min Sik; Lim, Younhee; Kang, Yoon-Sok; Park, Jin-Hwan; Doo, Seok-Gwang
A fundamental understanding of the anodic stabilities of electrolytes is important for the development of advanced high-voltage electrolytes. In this study, we calculated and systematically compared the oxidation stabilities of monomeric solvents and anions, and bimolecular solvent-solvent and anion-solvent systems that are considered to be high-voltage electrolyte components, using ab initio calculations. Oxidation stabilities of solvent or anion monomers without considering specific solvation molecules cannot represent experimental oxidation stabilities. The oxidation of electrolytes usually forms neutral or cationic radicals, which immediately undergo further reactions stabilizing the products. Oxidatively driven intermolecular reactions are the main reason for the lower oxidation stabilities of electrolytes compared with those of monomeric compounds. Electrolyte components such as tetramethylene sulfone (TMS), ethyl methyl sulfone (EMS), bis(oxalate)borate (BOB-), and bis(trifluoromethane)sulfonamide (TFSI-) that minimize such intermolecular chemical reactions on oxidation can maintain the oxidation stabilities of monomers. In predictions of the theoretical oxidation stabilities of electrolytes, simple comparisons of highest occupied molecular orbital energies can be misleading, even if microsolvation or bulk clusters are considered. Instead, bimolecular solvent complexes with a salt anion should be at least considered in oxidation calculations. This study provides important information on fundamental and applied aspects of the development of electrolytes.
Solvent interactions with a triphenylated benzoxazole polymerĀ
Eversdyk, David Allen
solubility parameter for the pclymer, A for the solvent, and Hansen's polar solubility parameters for the solvent and polymer indicated that the best solvents of tripheny- lated PBO would be m-cresol, phenol, and the carboxylic acids. Laboratory tests... for this lack of solubility, at least in the case of PBO, might be due to the morphology of the material heing such that solvent diffusion is not possible to many polymer chains by large, weakly interacti. ng solvents. However, diffusion is observed...
DOE solvent handbook information sheet
Chavez, A.A.
Solvents and cleaners are used in the Department of Defense (DOD) and the Department of Energy-Defense Program (DOE-DP) maintenance facilities for removing wax, grease, oil, carbon, machining fluids, solder fluxes, mold releases, and other contaminants before repairing or electroplating parts. Private industry also uses cleaners and degreasers for surface preparation of various metals. Growing environmental and worker safety concerns have brought attention to these solvents and cleaners, most of which are classified as toxic. Tightening government regulations have already excluded the use of some chemicals, and restrict the use of various halogenated hydrocarbons because of their atmospheric-ozone depleting effects, as well as their cancer-related risks. As a result, a program was established to develop an efficient, easily accessible, electronic solvent utilization handbook. This is being accomplished by: (1) identifying solvents (alternatives) that are not currently restricted by government regulations for use DOE-DP facilities, and private industry, (2) evaluating their cleaning performance, (3) evaluating their corrosivity, (4) evaluating their air emissions, (5) evaluating the possibility of recycling or recovering all or portions of the alternative degreasers, (6) testing substitute solvents compatibility with non-metallic materials, (7) inputting all of the data gathered (including previous biodegradability information) into a database, and (8) developing a methodology for efficient, widespread access to the data base information system.
DOE solvent handbook information sheet
Chavez, A.A.
Solvents and cleaners are used in the Department of Defense (DOD) and the Department of Energy-Defense Program (DOE-DP) maintenance facilities for removing wax, grease, oil, carbon, machining fluids, solder fluxes, mold releases, and other contaminants before repairing or electroplating parts. Private industry also uses cleaners and degreasers for surface preparation of various metals. Growing environmental and worker safety concerns have brought attention to these solvents and cleaners, most of which are classified as toxic. Tightening government regulations have already excluded the use of some chemicals, and restrict the use of various halogenated hydrocarbons because of their atmospheric-ozone depleting effects, as well as their cancer-related risks. As a result, a program was established to develop an efficient, easily accessible, electronic solvent utilization handbook. This is being accomplished by: (1) identifying solvents (alternatives) that are not currently restricted by government regulations for use DOE-DP facilities, and private industry, (2) evaluating their cleaning performance, (3) evaluating their corrosivity, (4) evaluating their air emissions, (5) evaluating the possibility of recycling or recovering all or portions of the alternative degreasers, (6) testing substitute solvents compatibility with non-metallic materials, (7) inputting all of the data gathered (including previous biodegradability information) into a database, and (8) developing a methodology for efficient, widespread access to the data base information system.
Thermal cycling effect on the nanoparticle distribution and specific heat of a carbonate eutectic with alumina nanoparticles
Shankar, Sandhya
The objective of this research was to measure the effect of thermal cycling on the nanoparticle distribution and specific heat of a nanocomposite material consisting of a eutectic of lithium carbonate and potassium carbonate and 1% by mass alumina...
Growth and microstructure evolution of the Nb{sub 2}Al-Al{sub 3}Nb eutectic in situ composite
Rios, C.T. [State University of Campinas, P.O. Box 6122, Campinas, SP 13083-970 (Brazil); Ferrandini, P.L. [Centro Universitario da FEI, C.P.85, CEP:09850-901, SP-Brasil (Brazil); Milenkovic, S. [State University of Campinas, P.O. Box 6122, Campinas, SP 13083-970 (Brazil); Caram, R. [State University of Campinas, P.O. Box 6122, Campinas, SP 13083-970 (Brazil)]. E-mail: firstname.lastname@example.com
In situ composite materials obtained by directional growth of eutectic alloys usually show improved properties, that make them potential candidates for high temperature applications. The eutectic alloy found in the Al-Nb system is composed of the two intermetallic phases Al{sub 3}Nb (D0{sub 22}) and Nb{sub 2}Al (D8{sub b}). This paper describes the directional solidification of an Al-Nb eutectic alloy using a Bridgman type facility at growth rates varying from 1.0 to 2.9 cm/h. Longitudinal and transverse sections of grown samples were characterized regarding the solidification microstructure by using optical and scanning electron microscopy, energy dispersive spectroscopy (EDS) and X-ray diffraction. Despite both phases being intermetallic compounds, the eutectic microstructure obtained was very regular. The results obtained were discussed regarding the effect of the growth rate on the microstructure, lamellar-rod transition and variation of phase volume fraction.
MICROBIOLOGY: Breathing with Chlorinated Solvents
NSDL National Science Digital Library
Perry L. McCarty (Stanford University; Department of Civil Engineering)
Access to the article is free, however registration and sign-in are required: Chlorinated solvents, the carcinogenic agents that permeate the air in your dry cleaners, have accumulated in the groundwater because microorganisms in the soil do not break them down. Now Maymó-Gatell et al. have isolated the first bacterium that can metabolize trichloroethylene and perchloroethylene to the harmless compound ethene. Identification of the bacterium will potentially allow manipulation of the conditions underground to facilitate the natural destruction of chlorinated solvents.
Solvent reorganization of electron transitions in viscous solvents
Ghorai, Pradip K.; Matyushov, Dmitry V. [Department of Chemistry, Arizona State University, Tempe, Arizona 85287-1604 (United States) and Center for the Early Events in Photosynthesis, Arizona State University, Tempe, Arizona 85287-1604 (United States)
We develop a model of electron transfer reactions at conditions of nonergodicity when the time of solvent relaxation crosses the observation time window set up by the reaction rate. Solvent reorganization energy of intramolecular electron transfer in a charge-transfer molecule dissolved in water and acetonitrile is studied by molecular dynamics simulations at varying temperatures. We observe a sharp decrease of the reorganization energy at a temperature identified as the temperature of structural arrest due to cage effect, as discussed by the mode-coupling theory. This temperature also marks the onset of the enhancement of translational diffusion relative to rotational relaxation signaling the breakdown of the Stokes-Einstein relation. The change in the reorganization energy at the transition temperature reflects the dynamical arrest of the slow, collective relaxation of the solvent related to the relaxation of the solvent dipolar polarization. An analytical theory proposed to describe this effect agrees well with both the simulations and experimental Stokes shift data. The theory is applied to the analysis of charge-transfer kinetics in a low-temperature glass former. We show that the reorganization energy is substantially lower than its equilibrium value for the low-temperature portion of the data. The theory predicts the possibility of discontinuous changes in the dependence of the electron transfer rate on the free energy gap when the reaction switches between ergodic and nonergodic regimes.
A study of early corrosion behaviors of FeCrAl alloys in liquid lead¢bismuth eutectic environments
Jun Lim; Hyo On Nam; Il Soon Hwang; Ji Hyun Kim
Lead and lead¢bismuth eutectic (LBE) alloy have been increasingly receiving attention as heavy liquid metal coolants (HLMC) for future nuclear energy systems. The compatibility of structural materials and components with lead¢bismuth eutectic liquid at high temperature is one of key issues for the commercialization of lead fast reactors. In the present study, the corrosion behaviors of iron-based alumina-forming alloys (Kanthal-AF«,
Microstructures and hydrogen permeability of directionally solidified Nb¢Ni¢Ti alloys with the Nb¢NiTi eutectic microstructure
Kyosuke Kishida; Yuji Yamaguchi; Katsushi Tanaka; Haruyuki Inui; Sho Tokui; Kazuhiro Ishikawa; Kiyoshi Aoki
The microstructures and hydrogen permeability properties were investigated for Nb¢NiTi eutectic alloys directionally solidified in an optical floating zone furnace. Rod-type eutectic microstructures with Nb rods aligned parallel to the growth direction are obtained with an alloy having a composition of Nb¢41Ni¢40Ti grown at relatively slow growth rates below 2.5mm\\/h. The hydrogen permeability depends on the relative direction of aligned
Crystallographically aligned metal-oxide composite made by reduction of a directionally solidified oxide-oxide eutectic
A. Revcolevschi; G. Dhalenne
Aligned metal-oxide composite materials have been grown from the melt by directional solidification at eutectic composition of several binary metal-oxide systems. The resulting microstructures consist of metallic fibres ~1 Ąm in diameter imbedded in an oxide matrix1,2. The occurrence of such fibrous structures, as opposed to lamellar structures, corresponds to eutectic compositions for which the volume fraction of the minor
Binary eutectics formed between ammonium nitrate and amine salts of 5-nitrotetrazole I. preparation and initial characterization
K.-Y. Lee; M. D. Coburn
We have found that both the ammonium salt of 5-nitrotetrazole (ANT) and the ethylenediamine salt of 5-nitrotetrazole (ENT) form eutectics with ammonium nitrate (AN). Initial characterization and small-scale sensitivity tests of CO2-balanced AN\\/ANT and AN\\/ENT formulations were performed; it was found that both eutectics were less sensitive in all tests than pure ANT or ENT, respectively. The phase diagrams of
Microstructure characteristics and interface morphology evolvement of Si-TaSi 2 eutectic in situ composite for field emission
Chunjuan Cui; Jun Zhang; Bo Li; Min Han; Lin Liu; Hengzhi Fu
As one of the semiconductor-metal eutectic (SME) composites, Si-TaSi2 eutectic composite has many characters such as the high melting point of TaSi2 material, the large density of TaSi2 fibers incorporated into the Si matrix, three-dimensional array of Schottky junctions grown in the composite spontaneously. So it is an ideal candidate for field emission array cathodes. In this paper, the directionally
Microstructure and mechanical behavior of in-situ directional solidified NiAl\\/Cr(Mo) eutectic composite
J.-M. Yang; S. M. Jeng; K. Bain; R. A. Amato
NiAl-based composites reinforced with refractory metals in-situ by the directional solidification technique have been recognized as promising candidate materials for high temperature structural applications. An in-situ NiAl\\/Cr(Mo) eutectic composite has been successfully fabricated using an edge-defined film-fed growth technique. The purpose of adding Mo into the NiAl\\/Cr eutectic system is to control the morphology of the Cr from a fibrous
A feasibility study of a diffusion barrier between Ni-Cr-Al coatings and nickel-based eutectic alloys
NASA Technical Reports Server (NTRS)
Young, S. G.; Zellars, G. R.
Coating systems have been proposed for potential use on eutectic alloy components in high-temperature gas turbine engines. In a study to prevent the deterioration of such systems by diffusion, a tungsten sheet 25 microns thick was placed between eutectic alloys and an Ni-Cr-Al layer. Layered test specimens were aged at 1100 C for as long as 500 h. Without the tungsten barrier the delta phase of the eutectic deteriorated by diffusion of niobium into the Ni-Cr-Al. Insertion of the tungsten barrier stopped the diffusion of niobium from the delta phase. Chromium diffusion from the Ni-Cr-Al into the gamma/gamma-prime phase of the eutectic was greatly reduced by the barrier. However, the barrier thickness decreased with time, and tungsten diffused into both the Ni-Cr-Al and the eutectic. When the delta platelets were aligned parallel rather than perpendicular to the Ni-Cr-Al layer, diffusion into the eutectic was reduced.
Relationship between edge drift and atomic migration during electromigration of eutectic SnPb lines
NASA Astrophysics Data System (ADS)
Yoon, Min-Seung; Lee, Shin-Bok; Kim, Oh-Han; Park, Young-Bae; Joo, Young-Chang
The existence of an incubation stage before edge drift occurs was found by examining the electromigration characteristics of eutectic SnPb solder in an edge drift structure using in situ scanning electron microscopy and the interruptive test method. During this incubation stage, the depletion of Pb was observed at the cathode end. From the change in resistance, the activation energies for the incubation and edge movement stages were calculated to be 0.88 and 1.02eV, respectively. Based on a comparison of the activation energies for each stage with the previously reported values, it is believed that, during the incubation stage, Pb migrated before Sn and that the edge movement resulted from the migration of Sn. These results suggest that Pb depletion is a prerequisite for electromigration-induced void nucleation in eutectic SnPb solder.
TEM/HREM structural characterization of directionally solidified GaAs-CrAs eutectic crystals
Ruvimov, S.; Liliental-Weber, Z.; Swider, W.; Washburn, J. [Lawrence Berkeley Lab., CA (United States). Material Science Div.; Holmes, D.E. [Electronic Materials Engineering, Camarillo, CA (United States)
Conventional and high resolution electron microscopy have been applied to characterize the microstructure of the CrAs-GaAs eutectic. The CrAs-GaAs eutectic crystals were directionally solidified by the Czochralski method in order to produce an ordered array of CrAs rods embedded in a GaAs matrix. The CrAs rods of 2--3 {micro}m in diameter align parallel to the growth axis of the ingot. Where the GaAs matrix is found to contain structural defects, the CrAs rods are effectively defect-free. The CrAs has an orthorhombic structure with the parameters a = 3.5 {+-} 0.1 {angstrom}, b = 6.2 {+-} 0.1 {angstrom}, c = 5.7 {+-} 0.1 {angstrom}. The c-axis is close to the direction of solidification.
Studies of directionally solidified eutectic Bi/MnBi at low growth velocities
NASA Technical Reports Server (NTRS)
Pirich, R. G.
The (lambda-squared)(V) deviation for diffusion-only rod eutectic growth, where lambda is the interrod spacing and V is the growth velocity, was studied at growth velocities less than 5 cm/h in directionally solidified eutectic Bi-Mn (Bi/MnBi). At lower growth velocities, (V less than 0.5 cm/h) morphological instability occurred which resulted in nonaligned, irregularly dispersed MnBi fibers. The (lambda-squared)(V) relation was experimentally determined over a range of growth velocities between 0.1 and 50 cm/h, thermal gradients in the liquid at the liquid-solid interface that varied from 40 to 120 C/cm and solidification orientation with respect to the direction of gravity. Naturally induced, convective instabilities are suggested as a possible growth velocity limit for cooperative growth in the Bi-Mn and related alloy systems.
High temperature oxidation resistant coatings for the directionally solidified Ni-Nb-Cr-Al eutectic superalloy
NASA Technical Reports Server (NTRS)
Strangman, T. E.; Ulion, N. E.; Felten, E. J.
Protective coatings required for the Ni-Nb-Cr-Al directionally solidified eutectic superalloy were developed and evaluated on the basis of oxidation resistance, diffusional stability, thermal fatigue, and creep resistance. NiCrAlY+Pt and NiCrAlY physical vapor-deposition coating systems exhibited the best combination of properties. Burner-rig testing indicated that the useful life of a 127-micron-thick NiCrAlY+Pt coating exceeds 1000 h at 1366 K. Eutectic-alloy creep lives at 1311 K and a stress of 151.7 MN/sq m were greater for NiCrAlY+Pt-coated specimens than for uncoated specimens by a factor of two.
Thermoelectric properties of Bi2Te3-PbTe pseudo binary near the eutectic composition.
Jung, Kyooho; Jang, Ho Won; Kang, Chong-Yun; Yoo, Myong-Jae; Choi, Won Chel; Kim, Jin-Sang
(Bi2Te3)(1-x)(PbTe)(x) binary systems near eutectic composition were prepared by melting of elemental metals and a sequential water quenching process and their microstructures and thermoelectric properties were investigated. Multiple phases such as Bi2Te3, BiPbTe and PbTe were observed due to phase separation when the composition x was higher than the eutectic point. Also the electrical conduction type of the alloys converted from p-type to n-type in the phase separated alloys. The lattice thermal conductivities in the phase-separated alloys are lower than those in alloys without phase separation, attributable to increased boundary scattering. PMID:22849153
Fatigue of Ni-Ai-Mo aligned eutectics at elevated temperatures
NASA Astrophysics Data System (ADS)
Tartaglia, J. M.; Stoloff, N. S.
The elevated-temperature mechanical behavior of two aligned eutectics (Ni-8.1 wt pct Al-26.4 wt pct Mo and Ni-6.3 wt pct Al-31.2 wt pct Mo) has been investigated utilizing monotonic and cyclic testing in vacuum. Tensile yield strength and fatigue resistance increased from 25 to 725 ░C, but then were reduced at 825 ░C. The fatigue lives of specimens tested at 725 ░C decreased sharply with decreasing frequency. A shift from surface to internal crack initiation was observed upon increasing the test temperature from 725 to 825 ░C. Stage II crack propagation was observed at both temperatures, in contrast to stage I cracking at 25 ░C. The test results are compared to those for other nickel and cobalt-base aligned eutectics to show that the frequency effect on fatigue life is not limited to the Ni-AI-Mo system.
Microstructural Effects on High Cycle Fatigue of Ni-AI-Mo Aligned Eutectics
NASA Astrophysics Data System (ADS)
Tartaglia, J. M.; Stoloff, N. S.
Two nickel-base aligned eutectics, AG15 (Ni-8.1 wt pct Al-26.4 wt pct Mo) and AG34 (Ni-6.3 wt pct Al-31.2 wt pct Mo), have been tested in high cycle fatigue at room temperature. Experimental variables were test environment and post-solidification heat treatment. The fatigue lives of both alloys and the crack propagation resistance of AG15 improved substantially in tests performed in vacuum vs those performed in air. AG34 had a higher fatigue limit than AGI5; both alloys showed surface initiation and stage I crack propagation. Post-solidification heat treatment had a beneficial effect on the S-N lives of AG34 specimens. Fatigue resistance of both alloys is compared with that of other nickel or cobalt base eutectics strengthened with brittle fibers.
Eutectic bonding of a Ti sputter coated, carbon aerogel wafer to a Ni foil
Jankowski, A.F.; Hayes, J.P.; Kanna, R.L.
The formation of high energy density, storage devices is achievable using composite material systems. Alternate layering of carbon aerogel wafers and Ni foils with rnicroporous separators is a prospective composite for capacitor applications. An inherent problem exists to form a physical bond between Ni and the porous carbon wafer. The bonding process must be limited to temperatures less than 1000{degrees}C, at which point the aerogel begins to degrade. The advantage of a low temperature eutectic in the Ni-Ti alloy system solves this problem. Ti, a carbide former, is readily adherent as a sputter deposited thin film onto the carbon wafer. A vacuum bonding process is then used to join the Ni foil and Ti coating through eutectic phase formation. The parameters required for successfld bonding are described along with a structural characterization of the Ni foil-carbon aerogel wafer interface.
Replacement solvents for use in chemical synthesis
Molnar, Linda K. (Philadelphia, PA); Hatton, T. Alan (Sudbury, MA); Buchwald, Stephen L. (Newton, MA)
Replacement solvents for use in chemical synthesis include polymer-immobilized solvents having a flexible polymer backbone and a plurality of pendant groups attached onto the polymer backbone, the pendant groups comprising a flexible linking unit bound to the polymer backbone and to a terminal solvating moiety. The polymer-immobilized solvent may be dissolved in a benign medium. Replacement solvents for chemical reactions for which tetrahydrofuran or diethyl may be a solvent include substituted tetrahydrofurfuryl ethers and substituted tetrahydro-3-furan ethers. The replacement solvents may be readily recovered from the reaction train using conventional methods.
Compatibility of martensitic\\/austenitic steel welds with liquid lead bismuth eutectic environment
J. Van den Bosch; A. Almazouzi
The high-chromium ferritic\\/martensitic steel T91 and the austenitic stainless steel 316L are to be used in contact with liquid lead¢bismuth eutectic (LBE), under high irradiation doses. Both tungsten inert gas (TIG) and electron beam (EB) T91\\/316L welds have been examined by means of metallography, scanning electron microscopy (SEM-EDX), Vickers hardness measurements and tensile testing both in inert gas and in
Thermoelectric and morphological effects of peltier pulsing on directional solidification of eutectic Bi-Mn
R. P. Silberstein; D. J. Larson; B. Dressler
We have carried out extensivein situ thermal measurements during Peltier Interface Demarcation (PID) during directional solidification of eutectic Bi\\/MnBi. We\\u000a have observed that significant thermal transients occur throughout the sample as a result of the Peltier pulsing. We have\\u000a separated the contributions of the Peltier, Thomson, and Joule heats, and studied them as a function of pulse intensity and\\u000a polarity.
Microstructure and creep of eutectic indium\\/tin on copper and nickel substrates
J. L. Freer; J. W. Jr. Morris
The behavior during creep in shear of eutectic indium-tin joints on copper and nickel substrates was examined in order to\\u000a determine the effect of creep deformation on the microstructure of the alloy. Primary creep was absent in all the samples\\u000a tested. The stress exponent at 20░ C was much higher for samples on nickel than for those on copper, indicating
The effect of heat transfer on local solidification kinetics of eutectic Al-Si cast alloy
C. Gonzßlez-Rivera; M. H. Cruz; H. A. GarcĒa; J. A. Juarez-Islas
Recently, Fourier thermal analysis (FTA) has been proposed as a suitable technique to obtain information about local solidification\\u000a kinetics in casting alloys. In this work, FTA was applied to a near-eutectic aluminum-silicon cast alloy in order to seek\\u000a experimental evidence supporting the solidification kinetics obtained from this method. Also, a heat-transfer\\/solidification-kinetics\\u000a model was used to compare predictions with experimental results.
Damage by eutectic particle cracking in aluminum casting alloys A356\\/357
Q. G. Wang; C. H. Caceres; J. R. Griffiths
The strain dependence of particle cracking in aluminum alloys A356\\/357 in the T6 temper has been studied in a range of microstructures\\u000a produced by varying solidification rate and Mg content, and by chemical (Sr) modification of the eutectic silicon. The damage\\u000a accumulates linearly with the applied strain for all microstructures, but the rate depends on the secondary dendrite arm spacing
Interlamellar residual stresses in single grains of NiO-ZrOŌ(cubic) directionally solidified eutectics
Elizabeth C. Dickey; Vinayak P. Dravid; Camden R. Hubbard
Phase-to-phase residual stresses due to thermal expansion mismatch were measured in lamellar NiO-ZrOŌ (cubic) directionally solidified eutectics (DSEs). The triaxial strain tensors for both phases were measured using single-crystal X-ray diffractometry techniques on isolated grains of the DSE. From the strain tensors, the stress tensors were calculated, taking into account the full elastic anisotropy of the phases. The resulting stress
Structured porous Ni and Co-YSZ cermets fabricated from directionally solidified eutectic composites
M. A. Laguna-Bercero; A. Larrea; J. I. Pe±a; R. I. Merino; V. M. Orera
NiO-YSZ and CoO-YSZ eutectic rods were produced by directional solidification using the laser floating zone method (LFZ). This technique produces highly structured material consisting of alternate lamellae of transition metal oxide and zirconia with variable interlamellar spacing depending on growth conditions. We have chosen conditions for interlamellar spacing of about 1?m. The microstructure is homogeneous and mechanically stable during thermochemical
Stability of the directionally solidified eutectics NiAl-Cr and NiAl-Mo
J. L. Walter; H. E. Cline
The eutectics NiAl-Cr with cylindrical chromium fibers and NiAl-Mo with faceted molybdenum fibers were heated at 1400?C to\\u000a determine the stability of the composite structure and to compare the stability of the nonfaceted fibers with that of the\\u000a faceted fibers in the NiAl matrix. Fiber size and size distribution and number of fibers per unit area were measured as a
Microstructures and mechanical properties of a directionally solidified NiAl¢Mo eutectic alloy
H.. Bei; E. P.. George
A NiAl¢Mo ternary eutectic alloy, having the nominal composition Ni¢45.5Al¢9Mo (at.%), was directionally solidified in a high-temperature optical floating zone furnace. Well-aligned rod-like microstructures were obtained, consisting of NiAl matrix and 14% (by volume) continuous Mo fibers having a square cross-section. With increasing growth rate (from 20 to 80 mm\\/h), the spacing and size of the Mo fibers decreased, from
Mechanical behavior of a carbide reinforced Co-Cr eutectic alloy
E. R. Thompson; D. A. Koss; J. C. Chesnutt
The tensile and creep behavior of a unidirectionally solidified (Co, Cr)-(Cr, Co)7C3 monovariant eutectic alloy have been examined. The effect of fiber orientation on the tensile strength has been studied at temperatures to 2200░F. The composite was found to be anisotropic with considerable strengthening in the longitudinal direction and with the transverse and 45 deg ultimate strengths being limited by
Corrosion of selected alloys in eutectic lithium-sodium-potassium carbonate at 900C
R. T. Coyle; T. M. Thomas; P. Schissel
There is an ongoing interest at the US Department of Energy in using molten salts as high temperature sensible heat storage media in advanced solar thermal systems. In this report, the compatibility of selected alloys in eutectic lithium-sodium-potassium carbonate, the salt that will be used in the near-term engineering experiments, has been evaluated at 900C. Several combinations of oxidation potential
The influence of electric current pulses on the microstructure of the MnBi\\/Bi eutectic
F. Li; L. L. Regel; W. R. Wilcox
The MnBi\\/Bi eutectic was directionally solidified with freezing rate oscillations caused by electric current pulses. The influence of current pulsing on microstructure depended on the ampoule translation rate V and pulsing conditions. Continuous electric current had a small effect on the microstructure. Current pulsing with the solid positive had a substantial influence, greater than with the solid negative. For V?2cm\\/h,
Influence of freezing rate changes on MnBi-Bi eutectic microstructure
William R. Wilcox; Krishna Doddi; Manju Nair; David J. Larson
In an attempt to explain the influence of space processing on the microstructure of MnBi-Bi, eutectic mixtures were directionally solidified with a sudden change of translation rate. The MnBi fiber spacing was able to adapt to the changing freezing rate as predicted by heat transfer computations. Thus the microstructure adapts more rapidly than the freezing rate could be changed in
Influence of freezing rate changes of MnBi-Bi eutectic microstructure. [effects of space processing
NASA Technical Reports Server (NTRS)
Wilcox, W. R.; Doddi, K.; Nair, M.; Larson, D. J.
In an attempt to explain the influence of space processing on the microstructure of MnBi-Bi, eutectic mixtures were directionally solidified with a sudden change of translation rate. The MnBi fiber spacing was able to adapt to the changing freezing rate as predicted by heat transfer computations. Thus the microstructure adapts more rapidly than the freezing rate could be changed in the present experiments.
Structure and magnetic properties of directionally solidified Bi-MnBi eutectic alloys
M. R. Notis; D. M. Shah; S. Young; C. Graham
An alloy containing about 2 at% Mn and 98 at% Bi should solidify at 230░C to give a eutectic consisting of about 3 vol % ferromagnetic MnBi in a matrix of diamagnetic Bi. Directional solidification of this alloy produces a structure of elongated parallel MnBi rods with diameters from 0.1 to 1.5 ?m, decreasing with increasing growth rate. Samples solidified
Determination of phase diagrams of eutectic binary alloys with partial solid solubility
L. J. Gallego; J. A. Somoza; J. A. Alonso; J. M. Lopez
Using a semi-empirical theory largely based on the heat of formation model developed by Miedema and co-workers, we have constructed the phase diagram of the alloy CuAg, a prototypical example of a system of eutectic type with appreciable solid solubility and no intermetallic compounds. This is an advance on the simpler kind of phase diagrams we considered in a previous
High temperature ultrasonic transducers for imaging and measurements in a liquid Pb\\/Bi eutectic alloy
Rymantas Kazys; Algirdas Voleisis; Reimondas Sliteris; Liudas Mazeika; Rudi Van Nieuwenhove; Peter Kupschus; Hamid Ait Abderrahim
In some nuclear reactors or accelerator-driven systems (ADS) the core is intended to be cooled by means of a heavy liquid metal, for example, lead-bismuth (Pb\\/Bi) eutectic alloy. For safety and licensing reasons, an imaging method of the interior of ADS, based on application of ultrasonic waves, has thus to be developed. This paper is devoted to the description of
Eutectic bonding of austenitic stainless steel 316L to magnesium alloy AZ31 using copper interlayer
Waled M. Elthalabawy; Tahir I. Khan
The eutectic bonding of magnesium alloy (AZ31) to austenitic stainless steel alloy (316L) was performed using pure Cu interlayers.\\u000a The effect of hold time on the microstructural developments across the joint region and the related effect on bond shear strength\\u000a were studied at a bonding temperature of 530░C. The bonding process took place through a sequential occurrence of solid-state\\u000a diffusion
Selective Au-Si eutectic bonding for Si-based MEMS applications
Lee, A.; Lehew, S.; Yu, C. [and others
A novel method of fabricating three-dimensional silicon micro electromechanical systems (MEMS) is presented, using selectivity thin film deposited Au-Si eutectic bond pads. Utilizing this process, complicated structures such as microgrippers and microchannels are fabricated. Bond strengths are higher than the silicon fracture strength and the bond areas can be localized and aligned to the processed wafer. The process and the applications are described in this paper.
Corrosion of metals in molten lithium sulphate-potassium sulphate eutectic
G. M. Abou-Elenien
In conjunction with the development of a new electrochemical flue gas desulphurization process, a study is made of the corrosion of several electrode materials in molten lithium sulphate-potassium sulphate eutectic at 600░C. Measurements of the open-circuit potentials are made in air, oxygen and nitrogen to determine the existence of a stable oxide layer on the electrode surface. Voltammetric measurements are
Electrode reaction of plutonium at liquid cadmium in LiCl¢KCl eutectic melts
O. Shirai; M. Iizuka; T. Iwai; Y. Suzuki; Y. Arai
The electrode reaction of the Pu3+\\/Pu couple at the surface of a liquid Cd electrode was investigated by cyclic voltammetry at 723, 773 and 823 K in LiCl?KCl eutectic melt. It was found that the diffusion of Pu3+ in the salt phase was a rate-determining step in the cathodic reaction, but the dissolution of Pu from the liquid Cd phase
High cycle fatigue of tantalum carbide reinforced nickel base eutectics at room temperature
D. E. Graham; D. A. Woodford
The high cycle fatigue response of two advanced tantalum carbide strengthened eutectic superalloys has been determined at\\u000a room temperature. Since these alloys will be coated in service, the effects of variables associated with coating processes\\u000a were given special attention. Both alloys showed a well defined fatigue limit. It was concluded that the maximum stress obtained\\u000a in the cycle at the
Unidirectional solidification of Al¢Cu eutectic with the accelerated crucible rotation technique
D. Ma; W. Q Jie; W Xu; Y Li; S Liu
The accelerated crucible rotation technique (ACRT) has been applied to the unidirectional solidification of Al¢Cu eutectic to reveal the effect of forced convection on the solidification microstructures by a systematic experimental investigation combining different rotation methods (the maximum rotation rate ?max=100¢400rpm) with various growth velocities (V0=5¢60?m\\/s). The results can be concluded as follows: (1)Forced convection introduced by ACRT dramatically changes
The thermal expansion of the directionally solidified AI-CuAI2 eutectic
Dennis F. Baker; Robert H. Bragg
Alloys of Al-CuAl2 eutectic composition were prepared from 99.999 pct pure materials and directionally solidified in a temperature gradient of about 45 ░C\\/cm at different growth rates R. The lambda2R = constant relation was verified and lamellar spacings of 7.5, 3.5, 2.6, 1.8 and 1.4 mum were obtained. Dilatometer specimens were machined with axes aligned in the principal lamellae coordinate
Banding formation and eutectic lamellar growth in directional solidified Ni 50 Al 20 Fe 30 alloy
J. Chen; J. H. Lee; Y. T. Lee; Z. Q. Hut
Banding formation and eutectic lamellar growth in a directionally solidified Ni50Al20Fe30 alloy were investigated. It was found that the banding area consists of two layers. The first layer is a ? layer, while the\\u000a subsequent one is a ? layer. The composition of various phases around the banding area changes with the solidification process.\\u000a The banding is formed by two
I. N. Plaksin; K. F. Barysheva; A. V. Astafeva
Descriptions are given of rare earth separation by acid leaching and ; solvent extraction with TBP. Hydrometallurgical treatment of enriched rare earth ; products enables 85 to 95% extraction into nitric acid with 50% HNOŌ ; Ieaching at 80 to 904DEC. Multistaged and counter-current extraction with TBP ; separates Ca and Fe from rare earth products, extracting up to 94
The protocol will simply describe in detail, with references and illustrations, the approach currently used by staff of the SPRD to evaluate natural attenuation of chlorinated solvents in ground water. Staff of SPRD, and staff of the Air Force Center for environmental excellence...
A New Co-C Eutectic Fixed-Point Cell for Thermocouple Calibration at
NASA Astrophysics Data System (ADS)
Failleau, G.; Deuzķ, T.; Jouin, D.; Mokdad, S.; Briaudeau, S.; Sadli, M.
The eutectic Co-C is a promising system to serve as a thermometric fixed point beyond the freezing point of copper (). Some national metrology institutes have developed, characterized, and compared their Co-C fixed-point cells based on conventional designs. Indeed, the fixed-point cells constructed are directly inspired by the technologies applied to the fixed points of the ITS-90 to the lower levels of temperature. By studying the eutectic metal-carbon systems, is appears that the high temperatures of implementation give a set of difficulties, such as the strong mechanical stresses on the graphite crucibles, due to the important thermal expansion of the eutectic alloys during their phase transitions. If these devices are suitable with research activities to serve like primary standards, it is not envisaged to propose them for a direct application to the calibration activities for the industry. As regards the limited robustness of the conventional fixed-point cells constructed, an intensive use of these device would not be reasonable, in term of cost for example. In this paper, a new Co-C fixed-point design is introduced. This low cost device has been developed specifically for intensive use in thermocouple calibration activities, with the aim of achieving the lowest level of uncertainties as is practicable. Thus, in this paper, the metrological characterization of this device is also presented, and a direct comparison to a primary Co-C fixed-point cell previously constructed is discussed.
Brazing characteristics of a Zr-Ti-Cu-Fe eutectic alloy filler metal for Zircaloy-4
NASA Astrophysics Data System (ADS)
Lee, Jung G.; Lim, C. H.; Kim, K. H.; Park, S. S.; Lee, M. K.; Rhee, C. K.
A Zr-Ti-Cu-Fe quaternary eutectic alloy was employed as a new Be-free brazing filler metal for Zircaloy-4 to supersede physically vapor-deposited Be coatings used conventionally with several disadvantages. The quaternary eutectic composition of Zr58Ti16Cu10Fe16 (at.%) showing a low melting temperature range from 832 ░C to 853 ░C was designed by a partial substitution of Zr with Ti based on a Zr-Cu-Fe ternary eutectic system. By applying an alloy ribbon with the determined composition, a highly reliable joint was obtained with a homogeneous formation of predominantly grown ?-Zr phases owing to a complete isothermal solidification, exhibiting strength higher than that of Zircaloy-4. The homogenization of the joint was rate-controlled by the diffusion of the filler elements (Ti, Cu, and Fe) into the Zircaloy-4 base metal, and the detrimental segregation of the Zr2Fe phase in the central zone was completely eliminated by an isothermal holding at a brazing temperature of 920 ░C for 10 min.
Solubilization of Genistein in Poly(Ethylene Glycol) via Eutectic Crystal Melting
NASA Astrophysics Data System (ADS)
Buddhiranon, Sasiwimon; Kyu, Thein
Genistein (5,7,4'-trihydroxyisoflavone) is a phytoestrogen found in soybean. It possesses various biological/pharmacological functions, e.g., tyrosine kinase inhibitory, anticarcinogenic, antioxidant, anti-inflammatory, and anti-microbial activities. However, genistein has poor water solubility and skin permeability, which have seemingly prohibited the progress to preclinical evaluation. Eutectic melting approach has been performed as a means of solubilizing genistein in poly(ethylene glycol) (PEG). Eutectic phase diagrams of blends containing genistein and PEG having three different molecular weights, i.e., 44k, 7k, and 500 g/mol, were established by means of DSC and compared with the theoretical liquidus and solidus lines, calculated self-consistently by taking into consideration all interactions including amorphous-amorphous, crystal-amorphous, amorphous-crystal, and crystal-crystal interactions. The eutectic temperatures were found to decrease with decreasing molecular weight of PEG. Guided by the phase diagram, it was found that genistein can be dissolved in PEG500 up to ś7 wt% at room temperature. More importantly, the solubility of genistein in PEG can be improved to meet the end-use criteria of the PEG/genistein mixtures.
A New Analytical Approach to Predict Spacing Selection in Lamellar and Rod Eutectic Systems
NASA Technical Reports Server (NTRS)
Catalina, Adrian V.; Sen, Subhayu; Whitaker, Ann F. (Technical Monitor)
In this paper, we reexamine the Jackson and Hunt (JH) theory and relax the assumption of isothermal solid/liquid interface(SLI) used in their treatment. A modification of the term B. in the expression of the solute concentration profile is also proposed. Based on the predictions of this modified theory the traditional definitions of regular and irregular eutectics are discussed. For regular eutectics the new model identifies a range of spacing within the limits defined by the minimum undercooling of the alpha and beta phase. For the irregular Al-Si eutectic system in particular we identified two different spacing selection mechanisnis: a) for a particular growth rate, a nearly isothermal interface can be achieved at a unique minimum spacing lambda(sub I); b) the average spacing in the microstructure (lambda(sub av) > lambda(sub I)) is essentially dictated by the undercooling of the faceted phase. Based on the modified theoretical model a semi-empirical expression has been developed to account for the influence of the temperature gradient. The theoretical calculations have been found to be in good agreement with the published experimental measurements.
Influence of gravity driven convection on the directional solidification of Bi/MnBi eutectic composites
NASA Technical Reports Server (NTRS)
Pirich, R. G.; Larson, D. J.
The role of gravity on Bridgman-Stockharger directional solidification of eutectic Bi/MnBi has been studied in reduced gravity aboard NASA sounding rocket SPAR flight experiments and contrasted with normal gravity investigations. The directional solidification of eutectic Bi/MnBi results in a low volume fraction, faceted/nonfaceted aligned rod eutectic whose MnBi rod size, interrod spacing, thermal and magnetic properties are sensitive functions of solidification processing conditions. The morphology of the low-gravity samples showed striking differences compared with identically processed, normal gravity samples grown in the same apparatus. The MnBi rod diameter and interrod spacing distributions were significantly smaller, approximately 50 percent, for the low gravity samples compared with identically processed one gravity samples. Accompanying the smaller MnBi rod diameters observed in the flight samples, was an increase in permanent magnet properties which reached greater than 97 percent of the theoretical maximum. Gravitationally induced thermal instabilities in one-gravity which result in irregular interface movement and associated difficulty of the faceted MnBi phase to branch are suggested to explain the morphological differences between one and low gravity solidification.
Feasibility study of tungsten as a diffusion barrier between nickel-chromium-aluminum and Gamma/Gamma prime - Delta eutectic alloys
NASA Technical Reports Server (NTRS)
Young, S. G.; Zellars, G. R.
Coating systems proposed for potential use on eutectic alloy components in high-temperature gas turbine engines were studied with emphasis on deterioration of such systems by diffusion. A 1-mil thick W sheet was placed between eutectic alloys and a NiCrAl layer. Layered test specimens were aged at 1100 C for as long as long as 500 hours. Without the W barrier, the delta phase of the eutectic deteriorated by diffusion of Nb into the NiCrAl. Insertion of the W barrier stopped the diffusion of Nb from delta. Chromium diffusion from the NiCrAl into the gamma/gamma prime phase of the eutectic was greatly reduced by the barrier. However, the barrier thickness decreased with time; and W diffused into both the NiCrAl and the eutectic. When the delta platelets were alined parallel to the NiCrAl layer, rather than perpendicular, diffusion into the eutectic was reduced.
Microstructural characterization of a directionally-solidified Ni¢33 (at.%) Al¢31Cr¢3Mo eutectic alloy as a function of withdrawal rate
S. V. Raj; I. E. Locci
The Ni¢33 (at.%)Al¢31Cr¢3Mo eutectic alloy was directionally-solidified (DS) at different rates, VI, varying between 2.5 to 508 mm h?1. Detailed qualitative and quantitative metallographic and chemical analyses were conducted on the directionally-solidified rods. The microstructures consisted of eutectic colonies with parallel lamellar NiAl\\/(Cr,Mo) plates for solidification rates at and below 12.7 mm h?1. Cellular eutectic microstructures were observed at higher
Processing, Microstructures, and Properties of Cr-Cr3Si, Nb-Nb3Si, and V-V3Si Eutectics
B. P. Bewlay; J. A. Sutliff; M. R. Jackson; K. M. Chang
The present paper examines the potential of refractory metal-A15 silicide composites as structural materials for high temperature applications. Three eutectic systems are considered, Cr-Cr3Si, Nb-Nb3Si, and V-V3Si, since they all have melting points above 1700░C and densities lower than Ni-based superalloys. Eutectic compositions were selected because directional solidification of eutectics can be used to generate aligned composite microstructures. The present
Dipolar correlations in structured solvents under nanoconfinement.
Buyukdagli, Sahin; Blossey, Ralf
We study electrostatic correlations in structured solvents confined to nanoscale systems. We derive variational equations of Netz-Orland type for a model liquid composed of finite size dipoles. These equations are solved for both dilute solvents and solvents at physiological concentrations in a slit nanopore geometry. Correlation effects are of major importance for the dielectric reduction and anisotropy of the solvent resulting from dipole image interactions and also lead to a reduction of van der Waals attractions between low dielectric bodies. Finally, by comparison with other recently developed self-consistent theories and experiments, we scrutinize the effect of solvent-membrane interactions on the differential capacitance of the charged liquid in contact with low dielectric substrates. The interfacial solvent depletion driven by solvent-image interactions plays the major role in the observed low values of the experimental capacitance data, while non-locality associated with the extended charge structure of solvent molecules only brings a minor contribution. PMID:24952564
Hydrocarbon solvents in high solids coatings
Albaugh, E.W.; Chiozza, R.F.; Pecoraro, J.M.
In 1976, the Environmental Protection Agency (EPA) adopted a new approach to regulating emissions from coatings - to limit emissions regardless of chemical type. As a result, aromatic hydrocarbon solvents again can be incorporated into coatings when they provide performance and cost benefits. In this paper, alkyd and polyester high solids coatings formulated with a combination of aromatic hydrocarbon and oxygenated solvents are compared to the same coatings formulated only with oxygenated solvents. The properties investigated were solubility, volatile organic compound (VOC) content, viscosity, rheology, sprayability, and final film properties. To supplement the laboratory tests, a high solids alkyd baking enamel containing aromatic hydrocarbon solvent was evaluated in two commercial plant trials. It performed well. In summary, substituting hydrocarbon solvent for some of the oxygenated solvent reduced the viscosity and volatile organic compound content of the high solids coatings without compromising performance. The substitution also substantially reduces cost: Aromatic solvents cost about $2.00 per gallon less than the oxygenated solvents they replace.
NSDL National Science Digital Library
This page investigates the problems associated with migratory fish, salmon and tuna, with videos from the "Deep Crisis" television episode, related website articles and student activities, and an interactive ocean game that tests knowledge of what creature lives at what depth. The videos feature marine biologists helping salmon get around dams in the Columbia-Snake river system and then out to sea, working to save salmon stock in Maine and eastern Canada, and cooperating with tuna fisherman to manage the bluefin stock. The videos total approximately one hour in length. The articles explore fish catch numbers in China, cleaning the waters of the Boston Harbor, and policy decisions that affect access to the ocean and its resources.
Modified enzymes for reactions in organic solvents
A. B. Salleh; M. Basri; M. Taib; H. Jasmani; R. N. Z. A. Rahman; M. B. A. Rahman; C. N. A. Razak
Recent studies on biocatalysis in waterŚorganic solvent biphasic systems have shown that many enzymes retain their catalytic\\u000a activities in the presence of high concentrations of organic solvents. However, not all enzymes are organic solvent tolerant,\\u000a and most have limited and selective tolerance to particular organic solvents. Protein modification or protein tailoring is\\u000a an approach to alter the characteristics of enzymes,
Solvent extraction process for tar sands
E. W. Funk; W. G. May; J. C. Pirkle
A solvent extraction process for tar sands is disclosed wherein a low boiling solvent having a normal boiling point of from 20* to 70* C. Is used to extract tar sands. The solvent is mixed with tar sands in a dissolution zone, the solvent:bitumen weight ratio being maintained at from about 0.5:1 to 2:1. This mixture is passed to a
Remediating pesticide contaminated soils using solvent extraction
Endalkachew Sahle-Demessie; Mark C. Meckes; Teri L. Richardson
Bench-scale solvent extraction studies were performed on soil samples obtained from a Superfund site contaminated with high levels of p,pŌ▓-DDT, p,pŌ▓-DDE and toxaphene. The effectiveness of the solvent extraction process was assessed using methanol and 2-propanol as solvents over a wide range of operating conditions. It was demonstrated that a six-stage methanol extraction using a solvent-to-soil ratio of 1.6 can
Solvent pretreatment of feed coal for briquetting
Martin, D.M.; Miller, M.R.
Solvent pretreating of coal fines prior to briquetting results in coal briquettes which have no added binder and which will withstand weathering conditions better than binder containing briquettes. The solvents are generally described as organic Lewis base solvents which are capable of electron donor action, and include among others, acetone, methyl ethyl ketone, and ethylene diamine.
Solvent pretreatment of feed coal for briquetting
D. M. Martin; M. R. Miller
Solvent pretreating of coal fines prior to briquetting results in coal briquettes which have no added binder and which will withstand weathering conditions better than binder containing briquettes. The solvents are generally described as organic Lewis base solvents which are capable of electron donor action, and include among others, acetone, methyl ethyl ketone, and ethylene diamine.
Solvent cleaning system and method for removing contaminants from solvent used in resin recycling
Bohnert, George W. (Harrisonville, MO); Hand, Thomas E. (Lee's Summit, MO); DeLaurentiis, Gary M. (Jamestown, CA)
A two step solvent and carbon dioxide based system that produces essentially contaminant-free synthetic resin material and which further includes a solvent cleaning system for periodically removing the contaminants from the solvent so that the solvent can be reused and the contaminants can be collected and safely discarded in an environmentally safe manner.
Microstructural development and mechanical behavior of eutectic bismuth-tin and eutectic indium-tin in response to high temperature deformation
Goldstein, J.L.F. [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering; [Lawrence Berkeley Lab., CA (United States)
The mechanical behavior and microstructure of eutectic Bi-Sn and In-Sn solders were studied in parallel in order to better understand high temperature deformation of these alloys. Bi-Sn solder joints were made with Cu substrates, and In-Sn joints were made with either Cu or Ni substrates. The as-cast microstructure of Bi-Sn is complex regular, with the two eutectic phases interconnected in complicated patterns. The as-cast microstructure of In-Sn depends on the substrate. In-Sn on Cu has a non-uniform microstructure caused by diffusion of Cu into the solder during sample preparation, with regions of the Sn-rich {gamma} phase imbedded in a matrix of the In-rich {beta} phase. The microstructure of In-Sn on Ni is uniform and lamellar and the two phases are strongly coupled. The solders deform non-uniformly, with deformation concentrating in a band along the length of the sample for Bi-Sn and In-Sn on Cu, though the deformation is more diffuse in In-Sn than in Bi-Sn. Deformation of In-Sn on Ni spreads throughout the width of the joint. The different deformation patterns affect the shape of the stress-strain curves. Stress-strain curves for Bi-Sn and In-Sn on Cu exhibit sharp decays in the engineering stress after reaching a peak. Most of this stress decay is removed for In-Sn on Ni. The creep behavior of In-Sn also depends on the substrate, with the creep deformation controlled by the soft P phase of the eutectic for In-Sn on Cu and controlled by the harder {gamma} phase for In-Sn on Ni. When In-Sn on Ni samples are aged, the microstructure coarsens and changes to an array of {gamma} phase regions in a matrix of the {beta} phase, and the creep behavior changes to resemble that of In-Sn on Cu. The creep behavior of Bi-Sn changes with temperature. Two independent mechanisms operate at lower temperatures, but there is still some question as to whether one or both of these, or a third mechanism, operates at higher temperatures.
Woertz, Jeff
The Deep Sea Research Submarine (Figure 1) is a modified VIRGINIA Class Submarine that incorporates a permanently installed Deep Sea Operations Compartment (Figure 2). Table 1 summarizes the characteristics of the Deep ...
Deep Vein Thrombosis Deep Vein Thrombosis is like a ticking time bomb Ś knowing the symptoms of DVD can save your life. As temperatures ... a warning about the serious dangers associated with deep vein thrombosis (DVT). This is a condition occurring ...
Batch extracting process using magneticparticle held solvents
Nunez, Luis (Elmhurst, IL); Vandergrift, George F. (Bolingbrook, IL)
A process for selectively removing metal values which may include catalytic values from a mixture containing same, wherein a magnetic particle is contacted with a liquid solvent which selectively dissolves the metal values to absorb the liquid solvent onto the magnetic particle. Thereafter the solvent-containing magnetic particles are contacted with a mixture containing the heavy metal values to transfer metal values into the solvent carried by the magnetic particles, and then magnetically separating the magnetic particles. Ion exchange resins may be used for selective solvents.
Nash, C.; Fondeur, F.; Peters, T.
Savannah River National Laboratory (SRNL) found that the dispersion numbers for the six combinations of CSSX:Next Generation Solvent (NGS) ōblendö and pure NGS versus salt solution, caustic wash, and strip aqueous solutions are all good. The dispersion numbers are indications of processability with centrifugal contactors. A comparison of solvent physical and thermal properties shows that the IntekÖ solvent flow meter in the plant has a reading biased high versus calibrated flow when NGS is used, versus the standard CSSX solvent. The flow meter, calibrated for CSSX solvent, is predicted to read 2.8 gpm of NGS in a case where the true flow of NGS is 2.16 gpm.
Foaming properties of solvents for use in air-assisted solvent extraction
H. M. Tarkan; J. A. Finch
The air-assisted solvent extraction (AASX) concept uses a solvent-coated bubble to contact the organic and aqueous phases. Compared to conventional solvent extraction, a high contact area can be created using less solvent and the buoyancy provided by the air core promotes phase separation. Solvent-coated bubbles are produced by forming a foam. The foam is injected through a capillary and a
NSDL National Science Digital Library
Comets have fascinated humans for hundreds of years, and most recently with the idea of creating a "deep impact" upon a comet in order to study the interior composition and makeup of these bodies. With this scientific mission in mind, a team of researchers (including participants from NASA's Jet Propulsion Laboratory and the University of Maryland) will send an impactor spacecraft into the Comet Tempel 1 on July 4th, 2005. The data collected from this fascinating experiment will help answer many questions about comets, and should be of interest to research scientists and the general public alike. The site itself contains quite a few helpful sections, including one dedicated to explaining the science behind studying comets. A technology section offers detailed explanations behind much of the flight system, the launch vehicle, and the various instruments on board. The gallery section has some nice animations that show how the mission will encounter and impact Comet Tempel 1. Overall, this is very engaging and well thought out site that explains this mission in jargon-free language.
Microstructure of the Sn-Cu{sub 6}Sn{sub 5} fibrous eutectic and its modification by segregation
Drevet, B.; Camel, D.; Favier, J.J. [CEA/DTA/CEREM/DEM, Grenoble (France). Lab. de Recherche de Base en Solidification] [CEA/DTA/CEREM/DEM, Grenoble (France). Lab. de Recherche de Base en Solidification; Dupuy, M. [CEA/DTA/LETI/OPT, Grenoble (France). Section de Caracterisation Physique des Materiaux] [CEA/DTA/LETI/OPT, Grenoble (France). Section de Caracterisation Physique des Materiaux
The influence of segregation due to thermal convection on the microstructure of Sn-Cu{sub 6}Sn{sub 5} fibrous eutectic alloys is studied in a Bridgman type configuration. The eutectic microstructure is characterized by means of image analysis, X-ray diffraction and scanning and transmission electron microscopy. In the absence of segregation, the eutectic is regular and its growth controlled by that of the Cu{sub 6}Sn{sub 5} fibers. The effect of interphases on eutectic spacing, through orientation relationships between fibers and matrix, is also evidenced. The influence of segregation can be summed up by the following effects. At first, in agreement with the Jackson and Hunt model, it leads to a variation of the eutectic spacing which results from a variation of the fiber volume fraction. Then, the spacing is much greater than the one obtained in the absence of segregation, due to a different tin growth plane and non-optimized fiber/matrix orientation relationships. Finally, the absence of steady state leads to a large dispersion of the spacing associated with a microstructural disorder.
A Comparison between Growth Morphology of "Eutectic" Cells/Dendrites and Single-Phase Cells/Dendrites
NASA Technical Reports Server (NTRS)
Tewari, S. N.; Raj, S. V.; Locci, I. E.
Directionally solidified (DS) intermetallic and ceramic-based eutectic alloys with an in-situ composite microstructure containing finely distributed, long aspect ratio, fiber, or plate reinforcements are being seriously examined for several advanced aero-propulsion applications. In designing these alloys, additional solutes need to be added to the base eutectic composition in order to improve heir high-temperature strength, and provide for adequate toughness and resistance to environmental degradation. Solute addition, however, promotes instability at the planar liquid-solid interface resulting in the formation of two-phase eutectic "colonies." Because morphology of eutectic colonies is very similar to the single-phase cells and dendrites, the stability analysis of Mullins and Sekerka has been extended to describe their formation. Onset of their formation shows a good agreement with this approach; however, unlike the single-phase cells and dendrites, there is limited examination of their growth speed dependence of spacing, morphology, and spatial distribution. The purpose of this study is to compare the growth speed dependence of the morphology, spacing, and spatial distribution of eutectic cells and dendrites with that for the single-phase cells and dendrites.
Length-scale dependent mechanical properties of Al-Cu eutectic alloy: Molecular dynamics based model and its experimental verification
Tiwary, C. S., E-mail: firstname.lastname@example.com; Chattopadhyay, K. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India); Chakraborty, S.; Mahapatra, D. R. [Department of Aerospace Engineering, Indian Institute of Science, Bangalore 560012 (India)
This paper attempts to gain an understanding of the effect of lamellar length scale on the mechanical properties of two-phase metal-intermetallic eutectic structure. We first develop a molecular dynamics model for the in-situ grown eutectic interface followed by a model of deformation of Al-Al{sub 2}Cu lamellar eutectic. Leveraging the insights obtained from the simulation on the behaviour of dislocations at different length scales of the eutectic, we present and explain the experimental results on Al-Al{sub 2}Cu eutectic with various different lamellar spacing. The physics behind the mechanism is further quantified with help of atomic level energy model for different length scale as well as different strain. An atomic level energy partitioning of the lamellae and the interface regions reveals that the energy of the lamellae core are accumulated more due to dislocations irrespective of the length-scale. Whereas the energy of the interface is accumulated more due to dislocations when the length-scale is smaller, but the trend is reversed when the length-scale is large beyond a critical size of about 80?nm.
Thermodynamic description and unidirectional solidification of eutectic organic alloys: IV. Binary systems neopentylglycol-succinonitrile and amino-methyl-propanediol-succinonitrile
Witusiewicz, V.T. [Department of Materials and Processes, ACCESS e. V., Intzestrasse 5, D-52072 Aachen (Germany)]. E-mail: firstname.lastname@example.com; Sturz, L. [Department of Materials and Processes, ACCESS e. V., Intzestrasse 5, D-52072 Aachen (Germany); Hecht, U. [Department of Materials and Processes, ACCESS e. V., Intzestrasse 5, D-52072 Aachen (Germany); Rex, S. [Department of Materials and Processes, ACCESS e. V., Intzestrasse 5, D-52072 Aachen (Germany)
The temperature and enthalpy of transformations of organic alloys from the binary systems neopentylglycol-succinonitrile (NPG-SCN) and 2-amino-2-methyl-1,3-propanediol-succinonitrile (AMPD-SCN) were measured by means of differential scanning calorimetry (DSC). The phase diagrams of these binary systems were assessed via the CALPHAD approach using Thermo-Calc by simultaneously optimizing the thermodynamic and phase equilibrium data measured in the present work. Proper agreements between the experimental and calculated data for the phase diagrams as well as for the thermochemical properties were achieved. Experiments and calculations show that both the NPG-SCN and the AMPD-SCN systems exhibit a non-variant eutectic reaction with the eutectic point at 90.45 mol% SCN (318.0 K) and at 97.39 mol% SCN (325.7 K), respectively. In the NPG-SCN system the temperature of the eutectic reaction is about 3 K higher than the temperature of the transformation from the ordered crystals (OCs) to the orientationally disordered crystals (ODICs), whereas the eutectic reaction in the AMPD-SCN involves the OCs of AMPD and the ODICs of SCN. Unidirectional solidification experiments were performed with selected NPG-SCN and AMPD-SCN alloys in order to verify phases involved in solid-liquid equilibria and the nature of eutectic growth in these systems. We find that eutectic growth in NPG-SCN eutectic alloy occurs with both solid phases being non-facetted and with a rod-like eutectic structure. The eutectic as well as some hypo-eutectic alloys from the AMPD-SCN system show irregular eutectic growth with a non-facetted BCC{sub A}2 phase of SCN and a facetted monoclinic phase of AMPD.
40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2011 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2010 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2011 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2010 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2011 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2011 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 6 to Subpart Kkkk of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2010 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 3 to Subpart IIIi of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2011 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 3 to Subpart Pppp of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2010 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 3 to Subpart Nnnn of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2010 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2011 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 5 to Subpart Qqqq of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2010 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 3 to Subpart Rrrr of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2010 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
40 CFR Table 3 to Subpart Mmmm of... - Default Organic HAP Mass Fraction for Solvents and Solvent Blends
Code of Federal Regulations, 2011 CFR
... true Default Organic HAP Mass Fraction for Solvents and Solvent Blends...ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) ...Part 63ŚDefault Organic HAP Mass Fraction for Solvents and Solvent Blends...
Sensitized photoxygenation of piroxicam in neat solvents and solvent mixtures.
Lemp, E; Zanocco, A L; G³nther, G
Detection of O(2)(1Delta(g)) phosphorescence emission, lambda(max)=1270 nm, following laser excitation and steady state methods were employed to determine the total rate constant, k(T), for the reaction between the non-steroidal anti-inflammatory drug piroxicam (PRX) and singlet oxygen in several solvents. Values of k(T) ranged from 0.048+/-0.003 x 10(6) M(-1) s(-1) in chloroform to 71.2+/-2.2 x 10(6) M(-1) s(-1) in N,N-dimethylformamide. The chemical reaction rate constant, k(R), was determined by using thermal decomposition of 1,4-dimethylnaphthalene endoperoxide as the singlet oxygen source. In acetonitrile, the k(R) value is equal to 5.0+/-0.4 x 10(6) M(-1) s(-1), very close to the k(T) value. This result indicates that, in this solvent, the chemical reaction corresponds to the main reaction path. Dependence of total rate constant on the solvent parameters pi* and beta can be explained in terms of a reaction mechanism that involves the formation of a perepoxide intermediate. Rearrangement of the perepoxide to dioxetane followed by ring cleavage and transacylation accounts for the formation of N-methylsaccharine and N-(2-pyridyl)oxamic acid, the main reaction products. Data obtained in dioxane-water (pH 4) mixtures with neutral enolic and zwitterionic tautomers of piroxicam in equilibrium show that the zwitterionic tautomer reacts with singlet oxygen faster than the enolic tautomer. PMID:11809375
Kinetic Monte Carlo Simulations of Rod Eutectics and the Surface Roughening Transition in Binary Alloys
NASA Technical Reports Server (NTRS)
Bentz, Daniel N.; Betush, William; Jackson, Kenneth A.
In this paper we report on two related topics: Kinetic Monte Carlo simulations of the steady state growth of rod eutectics from the melt, and a study of the surface roughness of binary alloys. We have implemented a three dimensional kinetic Monte Carlo (kMC) simulation with diffusion by pair exchange only in the liquid phase. Entropies of fusion are first chosen to fit the surface roughness of the pure materials, and the bond energies are derived from the equilibrium phase diagram, by treating the solid and liquid as regular and ideal solutions respectively. A simple cubic lattice oriented in the {100} direction is used. Growth of the rods is initiated from columns of pure B material embedded in an A matrix, arranged in a close packed array with semi-periodic boundary conditions. The simulation cells typically have dimensions of 50 by 87 by 200 unit cells. Steady state growth is compliant with the Jackson-Hunt model. In the kMC simulations, using the spin-one Ising model, growth of each phase is faceted or nonfaceted phases depending on the entropy of fusion. There have been many studies of the surface roughening transition in single component systems, but none for binary alloy systems. The location of the surface roughening transition for the phases of a eutectic alloy determines whether the eutectic morphology will be regular or irregular. We have conducted a study of surface roughness on the spin-one Ising Model with diffusion using kMC. The surface roughness was found to scale with the melting temperature of the alloy as given by the liquidus line on the equilibrium phase diagram. The density of missing lateral bonds at the surface was used as a measure of surface roughness.
Creep-fatigue interactions in eutectic tin-lead-based solder alloys. Ph.D. Thesis
Kuo, C.W.
Eutectic tin-lead solder alloys subjected to cyclic loading at room temperature experience creep-fatigue interactions due to high homologous temperature. At temperature above 0.5 melting point, the dominant damage mechanism can be cavity nucleation and growth, especially for alloys that have fine grain structure and a large volume fraction of dispersoids. The objective of the present study is to model the damage evolution during creep-fatigue interactions and experimentally validate the damage evolution based life predictions in rapidly solidified solder alloys. Four types of solder alloys were considered in this research, namely, conventional 63Sn-37Pb, rapidly solidified 63Sn-37Pb, dispersion-strengthened eutectic solders, and solid solution strengthened eutectic solders. Mechanical properties of the solder alloys and the life times under creep-fatigue conditions were evaluated. Damage produced in the course of creep or fatigue deformation was studied by metallography, scanning electron microscopy, precision density measurement, and the observation of grain boundary sliding. Based on the damage characteristics, the dominant failure mechanism was proved to be cavity growth. Three cavity growth models were applied to four types of solder alloys to predict creep-fatigue life by taking into account the tensile loading component as well as the compressive loading component when reversed process can occur. An algorithm to calculate cavity growth in each fatigue cycle is used to predict the number of fatigue cycles to failure, where failure is defined as a critical cavity size. Calculated lives are compared to experimental data under six types of creep-fatigue loading histories. The method predicts the creep-fatigue lives within a factor of two with the incorporation of appropriate compressive healing factor. Discrepancy between calculated lives and experimental results is discussed.
Continuous melting and thermal-history-dependent freezing in the confined Na-K eutectic alloy
NASA Astrophysics Data System (ADS)
Charnaya, E. V.; Lee, M. K.; Tien, Cheng; Chang, L. J.; Wu, Z.-J.; Kumzerov, Yu. A.; Bugaev, A. S.
23Na NMR studies of the Na-K eutectic alloy embedded into porous glass with 7-nm pores showed that melting of Na2K confined nanoparticles is a continuous process with smooth changes in the Knight shift of a narrow resonance line and nuclear spin relaxation between those in the crystalline and liquid states. The intermediate state, which occurs upon melting is stable and more favorable than the liquid state. The inverse freezing transformation can be sharp as at a first-order transition or continuous depending on the initial temperature of cooling. The results suggest revision of theoretical predictions for the melting and freezing transitions in confined geometry.
Creep-fatigue interaction in a cobalt-base aligned eutectic
NASA Astrophysics Data System (ADS)
Koburger, C. W.; Duquette, D. J.; Stoloff, N. S.
The effects of microstructure, test temperature and frequency on the high cycle fatigue behavior of two cobalt-base aligned eutectics and a cobalt-base solid solution alloy have been determined. Fatigue resistance of the composites improved when interfiber spacing was reduced or post-solidification heat treatments were performed. Removal of chromium caused a reduction in fatigue life, especially at high stresses. Vacuum environment caused a significant improvement in fatigue endurance limit at 25 ░C but not at 825 ░C. Reducing test frequency in vacuum reduced fatigue lives at 825 ░C, indicating a creep-fatigue interaction was occurring. Additional evidence for a creep-fatigue interaction is discussed.
Fraction eutectic measurements in slowly cooled Pb - 15 wt percent Sn alloys
NASA Technical Reports Server (NTRS)
Studer, Anthony C.; Laxmanan, V.
A space shuttle experiment employing the General Purpose Furnace in its isothermal mode of operation is currently manifested for flight circa 1989. The aim of this experiment was to investigate the role of gravity in a slowly, and isothermally, cooled sample of a binary Pb - 15 wt percent Sn alloy. Ground based work in support of the microgravity experiment is discussed. In particular, it is shown that fraction eutectic measurements using an image analyzer, can be used to satisfactorily describe macrosegregation occurring in these slowly cooled ingots.
Spatial profile of thermoelectric effects during Peltier pulsing in Bi and Bi/MnBi eutectic
NASA Technical Reports Server (NTRS)
Silberstein, R. P.; Larson, D. J., Jr.
The spatial profile of the thermal transients that occur during and following the current pulsing associated with Peltier Interface Demarcation during directional solidification is studied. Results for pure Bi are presented in detail and compared with corresponding results for the Bi/MnBi eutectic. Significant thermal transients occur throughout the sample that can be accounted for by the Peltier effect, the Thomson effect, and Joule heating. These effects are separated and their behavior is studied as a function of time, current density, and position with respect to the solid/liquid interface.
The slip vectors in an NiAl-Mo directionally solidified eutectic alloy
Chen, X.F.; Joslin, S.M.; Oliver, B.F.; Brooks, C.R. (Univ. of Tennessee, Knoxville, TN (United States). Materials Science and Engineering Dept.)
Since NiAl is significantly elastically anisotropic, dislocations of b = a<100>, a<110>, and a<111> are all stable. Each of these dislocations have been determined to operate in NiAl under different crystal orientation and test conditions. Generally, the slip vector is a <100> over the entire temperature range for single crystals, tested along a non-<100> direction. In this paper, the authors describe the slip vector that was observed in the NiAl-9Mo-0.1Zr eutectic composite alloy. Although the sample was not deformed under well controlled conditions, the analyses provide information about the deformation mechanism in this composite material.
Embedded binary eutectic alloy nanostructures: a new class of phase change materials.
Shin, S J; Guzman, J; Yuan, C-W; Liao, Christopher Y; Boswell-Koller, Cosima N; Stone, P R; Dubon, O D; Minor, A M; Watanabe, Masashi; Beeman, Jeffrey W; Yu, K M; Ager, J W; Chrzan, D C; Haller, E E
Phase change materials are essential to a number of technologies ranging from optical data storage to energy storage and transport applications. This widespread interest has given rise to a substantial effort to develop bulk phase change materials well suited for desired applications. Here, we suggest a novel and complementary approach, the use of binary eutectic alloy nanoparticles embedded within a matrix. Using GeSn nanoparticles embedded in silica as an example, we establish that the presence of a nanoparticle/matrix interface enables one to stabilize both nanobicrystal and homogeneous alloy morphologies. Further, the kinetics of switching between the two morphologies can be tuned simply by altering the composition. PMID:20698591
Creep, stress relaxation, and plastic deformation in SnAg and Sn-Zn eutectic solders
H. Mavoori; J. Chin; S. Vaynman; B. Moran; L. Keer; M. Fine
Because of the high homologous operation temperature of solders used in electronic devices, time and temperature dependent\\u000a relaxation and creep processes affect their mechanical behavior. In this paper, two eutectic lead-free solders (96.5Sn-3.5Ag\\u000a and 91Sn-9Zn) are investigated for their creep and stress relaxation behavior. The creep tests were done in load-control with\\u000a initial stresses in the range of 10-22 MPa
Zero-gravity growth of a sodium chloride-lithium fluoride eutectic mixture
NASA Technical Reports Server (NTRS)
Yue, A. S.; Yeh, C. W.; Yue, B. K.
Continuous and discontinuous lithium fluoride fibers embedded in a sodium chloride matrix were produced in space and on Earth, respectively. The production of continuous fibers in a eutectic mixture was attributed to the absence of convective current in the liquid during solidification in space. Image transmission and optical transmittance measurements of transverse sections of the space-grown and Earth-grown ingots were made with a light microscope and a spectrometer. It was found that better optical properties were obtained from samples grown in space. This was attributed to a better alignment of lithium fluoride fibers along the growth direction.
Loss of Anatomical Landmarks with Eutectic Mixture of Local Anesthetic Cream for Neonatal Male Circumcision
Plank, Rebeca M.; Kubiak, David W.; Abdullahi, Rasak Bamidele; Ndubuka, Nnamdi; Nkgau, Maggie M.; Dapaah-Siakwan, Fredrick; Powis, Kathleen M.; Lockman, Shahin
We report two cases of newborns who developed marked local edema after application of a eutectic mixture of local anesthetic (EMLA) topical anesthetic cream for neonatal male circumcision (NMC). Although local edema and erythema are known potential side effects of EMLA cream, a common anesthetic used for NMC, the loss of landmarks precluding safe NMC has not previously been reported, and is described here. Although we cannot recommend an alternate local anesthetic for neonates with this reaction to EMLA, based on a review of the published data we think that serious systemic adverse events related to EMLA are extremely rare. PMID:23102766
Microstructural changes in eutectic tin-lead alloy due to severe bending
Severe plastic deformation in an eutectic tin-lead alloy is studied by imposing fast bending at room temperature, in an attempt to examine the microstructural response in the absence of thermally activated diffusion processes. A change in microstructure due to this purely mechanically imposed load is observed: the tin-rich matrix phase appears to be extruded out of the narrow region between neighboring layers of the lead-rich phase and alterations in the colony structure occur. A micromechanism is proposed to rationalize the experimental observations.
(abstract) A Brief, Selective Review of Thermal Cycling Fatigue in Eutectic Tin-Lead Solder
NASA Technical Reports Server (NTRS)
Winslow, J. W.; Silveira, C. de
This paper reviews selected parts of the current literature relevant to thermo-mechanical fatigue mechanisms in eutectic tin-lead solder, and suggests a general outline to account for some observed failures. The field is found to be complex. One recent experimental study finds some failure modes to be sensitive to joint geometry. Attempts to extrapolate from test environments to service environments have had only limited success. Much work remains to be done before fatigue failures in this material can be considered as under practical control.
The thermal expansion of the directionally solidified AI-CuAI 2 eutectic
Dennis F. Baker; Robert H. Bragg
Alloys of Al-CuAl2 eutectic composition were prepared from 99.999 pct pure materials and directionally solidified in a temperature gradient\\u000a of about 45 ░C\\/cm at different growth ratesR. The ?2R= constant relation was verified and lamellar spacings of 7.5, 3.5, 2.6, 1.8 and 1.4 ?m were obtained. Dilatometer specimens\\u000a were machined with axes aligned in the principal lamellae coordinate directions. Thermal
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REVIEW ARTICLE: Metal (carbide) carbon eutectics for thermometry and radiometry: a review of the first seven years
NASA Astrophysics Data System (ADS)
Woolliams, Emma R.; Machin, Graham; Lowe, David H.; Winkler, Rainer
Since 1999, when the first high temperature fixed-points based on the metal-carbon eutectic phase transitions were realized, more than 60 papers have been published on this topic. Eutectic based fixed-points are already being considered as secondary reference points for the International Temperature Scale and have been introduced into industrial laboratories. This rapid progress has been possible through the combined effort of scientists around the world, from national metrology institutes, universities and industry. It has been proposed that these fixed-points should be officially adopted as a way to improve the realization and dissemination of temperature scales above the silver point. In radiometry, the availability of stable high temperature fixed-points will give greater flexibility and at some wavelengths the potential for greater accuracy for spectral radiance and irradiance scale realization. This paper summarizes the major progress in eutectic research so far.
Directional solidification of Mo{sub 5}Si{sub 3}-MoSi{sub 2} eutectic
Borowicz, S.M.; Heatherly, L.; Zee, R.H.; George, E.P.
The Mo-Si phase diagram exhibits a Mo{sub 5}Si{sub 3}-MoSi{sub 2} eutectic at the 54% Si composition. Since the terminal phases have comparable melting points and are equidistant from the eutectic composition, there is the possibility of obtaining lamellar microstructures in this system. In addition, if the alloys are directionally solidified, there is the further possibility of obtaining aligned lamellae. In this study, a high temperature (xenon-arc-lamp) optical floating zone furnace is utilized to directionally solidify Mo-Si alloys of the eutectic composition. Growth conditions are systematically varied to investigate their effects on the solidification microstructure. Growth rates and rotation speeds are identified that result in lamellar microstructures.
Rational solvent selection for cooling crystallizations
Nass, K.K. (Eastman Kodak Co., Rochester, NY (United States). Chemicals Development Div.)
The development of a successful crystallization process for purification and isolation of an organic compound requires the selection of a suitable solvent or solvent mixture; to date, no logical method has been established for determining the best solvent combination. The process chemist or engineer often employs a trial-and-error procedure to identify an appropriate solvent system, the success of which is dependent on experience and intuition. This paper describes a strategy for choosing crystallization solvents based upon equilibrium limits. The approach utilizes a group-contribution method (UNIFAC) to predict a value for the activity coefficient of the solute in a given solvent system at the saturation point. This value is then used to calculate the solubility of the solute at a high'' temperature and a low'' temperature. The resulting solubility values determine the maximum theoretical yield for the process. Both quantities are used to rank order solvents and/or their mixtures relative to one another according to their solvent power and potential process yield. Several examples illustrating the successful application of this method are described, and potential improvements to the algorithm are discussed. Implementation of this strategy will reduce product cycle time, minimize solvent usage, and allow identification of cheaper solvent alternatives.
Rapid solidification of Al 2O 3/Y 3Al 5O 12/ZrO 2 eutectic in situ composites by laser zone remelting
NASA Astrophysics Data System (ADS)
Su, Haijun; Zhang, Jun; Cui, Chunjuan; Liu, Lin; Fu, Hengzhi
Directionally solidified rods and plates of Al 2O 3/YAG/ZrO 2 ternary eutectic in situ composites were grown by the laser zone remelting technique under different growth conditions, aiming to reveal the effect of rapid solidification on the microstructure characteristics, solidification behaviors and mechanical properties. The as-solidified eutectics presented smooth surfaces, well-defined phases, no pores and grain boundaries in their microstructures. The eutectic microstructure displayed a refined entangled network of Al 2O 3 (40%), YAG (43%) and ZrO 2 (17%) phases with sizes in the submicron range. Moreover, the refined ordered/aligned eutectic structure with the lamellar/fibrous and rod-type ZrO 2 in the nano-micron range was also observed. Two kinds of microstructures primarily resulted from the high-temperature gradient and solidification rate of the laser zone remelting. The eutectic interspacing decreased with increasing the scanning rate and the minimal spacing observed was as fine as 0.1-0.2 ?m. The eutectic interfaces showed a typical faceted/faceted growth characteristic and the formation mechanism was detailedly discussed. The mechanical characterization at ambient temperature showed that the hardness and fracture toughness of the eutectic were 16.67 GPa and 8.0 MPa m 1/2, respectively. The small size effect of eutectic phases related with the rapid solidification, the addition of the third component of ZrO 2 and the crack deflection contributed to the improved fracture toughness.
Directionally solidified in situ metal matrix composites. Part 1. Final report, 1 Nov 1974--1 Jan 1976. [Screening of eutectic superalloys for turbine blades
G. Haour; F. Mollard; B. Lux; A. H. Clauer; I. G. Wright
The aim of the present alloy screening program was to identify new eutectic superalloys suitable for the manufacture of directionally solidified turbine blades operating at up to 1150 C. In the course of this program, five eutectics not previously investigated have been found to meet the corresponding objectives of a melting point above 1200 C, a specific gravity below 9
Solvent effects on infrared spectra of 2-acetylthiophene in organic solvents
NASA Astrophysics Data System (ADS)
Liu, Qing; Xu, Xiaomin; Sang, Wenqiang
Infrared spectroscopy studies of 2-acetylthiophene (ACTH) in 18 different organic solvents, both polar and non-polar, were undertaken to investigate the solvent-solute interactions. The frequencies of carbonyl stretching vibration ?(C?O) of ACTH were correlated with the properties such as the solvent acceptor number (AN) and the linear solvation energy relationships (LSER). The solvent-induced stretching vibration frequency shifts showed a better correlation with the LSER than the AN. A six-membered ring-like hydrogen bonding structure was presented and the solvent effects of ACTH in alcohol solvents were investigated in detail.
Tribological Properties of a Nano-Eutectic Fe 1.87 C 0.13 Alloy Under Water Environment
Lin Wang; Jun Yang; Jiqiang Ma; Qinling Bi; Licai Fu; Junying Hao; Weimin Liu
Tribological properties of a nano-eutectic Fe1.87C0.13 alloy were investigated under distilled-water lubrication against AISI52100 steel ball for various applied loads and sliding\\u000a speeds. For comparison, the tribological behavior of annealed coarse-grained Fe1.87C0.13 alloy was also examined under the same testing conditions. Worn surfaces of both alloys were analyzed by using a scanning\\u000a electron microscope (SEM). The wear rate of nano-eutectic
Investigation of interfacial reaction between SnAg eutectic solder and Au\\/Ni\\/Cu\\/Ti thin film metallization
J. Y. Park; C. W. Yang; J. S. Ha; C.-U. Kim; E. J. Kwon; S. B. Jung; C. S. Kang
This paper reports the formation of intermetallic compounds in Au\\/Ni\\/Cu\\/Ti under-bump-metallization (UBM) structure reacted\\u000a with Ag-Sn eutectic solder. In this study, UBM is prepared by evaporating Au(500 ?)\\/Ni(1000 ?)\\/Cu(7500 ?) \\/Ti (700 ?) thin\\u000a films on top of Si substrates. It is then reacted with Ag-Sn eutectic solder at 260 C for various times to induce different\\u000a stages of the
Solvent dependent photophysical properties of dimethoxy curcumin
NASA Astrophysics Data System (ADS)
Barik, Atanu; Indira Priyadarsini, K.
Dimethoxy curcumin (DMC) is a methylated derivative of curcumin. In order to know the effect of ring substitution on photophysical properties of curcumin, steady state absorption and fluorescence spectra of DMC were recorded in organic solvents with different polarity and compared with those of curcumin. The absorption and fluorescence spectra of DMC, like curcumin, are strongly dependent on solvent polarity and the maxima of DMC showed red shift with increase in solvent polarity function (?f), but the above effect is prominently observed in case of fluorescence maxima. From the dependence of Stokes' shift on solvent polarity function the difference between the excited state and ground state dipole moment was estimated as 4.9 D. Fluorescence quantum yield (?f) and fluorescence lifetime (?f) of DMC were also measured in different solvents at room temperature. The results indicated that with increasing solvent polarity, ?f increased linearly, which has been accounted for the decrease in non-radiative rate by intersystem crossing (ISC) processes.
Neurotoxicity of solvent mixtures in spray painters
G. Triebig; A. Barocka; F. Erbguth; R. H÷ll; C. Lang; S. Lehrl; T. Rechlin; W. Weidenhammme; D. Weltle
Summary A multidisciplinary cross-sectional study was performed to examine the chronic neurotoxicity of organic solvents. Participating in the study were 105 persons employed as spray painters and having long-term solvent exposure (10¢44 years) and a control group consisting of 58 construction workers, electricians, and plumbers without occupational contact to solvents. Samples were matched for age, preexposure intelligence level, occupation, and
Conserve Energy: Modernize Your Solvent Deasphalting Unit
Lambert, J. S.; Gleitsmann, J. W.
in raising the temperature of DAO/solvent m~x to its critical temperature is quite high, a part of this heat can be recovered by exchange to preheat DAO/solvent mix from the extractor. Ecor;OMIcs Each added stage of evaporation requires an additional...CONSERVE ENERGY: MODERNIZE YOUR SOLVENT DEASPHALTING UNIT Joseph W. Gleitsmann* John S. Lambert Foster Wheeler Energy Corporation Livingston, New Jersey ABSTRACT Deasphalting units provide high quality feedstocks for lube oil manufacture...
Femtosecond dynamics in hydrogen-bonded solvents
Castner, E.W. Jr.; Chang, Y.J.
We present results on the ultrafast dynamics of pure hydrogen-bonding solvents, obtained using femtosecond Fourier-transform optical-heterodyne-detected, Raman-induced Kerr effect spectroscopy. Solvent systems we have studied include the formamides, water, ethylene glycol, and acetic acid. Inertial and diffusive motions are clearly resolved. We comment on the effect that such ultrafast solvent motions have on chemical reactions in solution.
Mechanism of paint removing by organic solvents
NASA Astrophysics Data System (ADS)
Del Nero, V.; Siat, C.; Marti, M. J.; Aubry, J. M.; Lallier, J. P.; Dupuy, N.; Huvenne, J. P.
The mechanism of paint removing has been studied by comparing the stripping efficiency of a given solvent with its ability to swell the film. The most effective solvents have a Hildebrand's parameter, ?H, ranging from 10.5 to 12 and a Dimroth parameter, ET(30), ranging from 0.25 to 0.4. The synergy observed with the mixtures DMSO/non polar solvent is explained by a dissociation of the DMSO clusters into individual molecules which diffuse more easily.
In-depth analysis of solvent effects on bulk heterojunction solar cell performance
NASA Astrophysics Data System (ADS)
Zohourian Aboutorabi, Reihaneh; Joodaki, Mojtaba; Shahbazi, Kowsar
Efficiency of an organic solar cell is very sensitive to fabrication procedure. One of the most important parameters is active layer morphology which radically influences several cell properties such as generation rate, layer resistance, charge carrier motilities etc. Meantime, in P3HT:fullerene based solar cells, using PCBM would improve the morphology and increase the cost simultaneously. On the other hand, C60 is way less expensive, but its limited solubility in common solvents would influence cell performance. To benefit from its cost and as the formation of C60 aggregates and P3HT crystallinity significantly depend on the solvent which would influence several cell properties, one should find a proper solvent. To make an in-depth investigation of solvent effects, experimental investigations will not suffice and using a precise model to fit the data and extract hidden parameters would help us to have a deep understanding of the cells physical basis. In this work, an optimization algorithm is employed to fit a numerical model simulation results with experiments and the model benefits from a field dependent series resistance. Simulation results indicate that a suitable solvent mainly improves the cell performance by changing 3 basic parameters which are G, ?n and ?p. Additionally, although parameters such as Eg and DC dielectric constant are very crucial in determining power conversion efficiency, they cannot be effectively improved changing the solvent. It is reported that the cell prepared by Cl-naph:CB performs better than the other cells. Considering our results, it can be attributed to its larger G, ?n and ?p. It also has the least Rs and the largest Rsh among all other P3HT:C60 based cells (which is caused by its higher mobility-carrier density product). This work gives experimentalists an idea of how they should choose a solvent. The results can also be generalized to find a proper solvent for other active layer materials.
A Promising New Class of High-Temperature Alloys: Eutectic High-Entropy Alloys
Lu, Yiping; Dong, Yong; Guo, Sheng; Jiang, Li; Kang, Huijun; Wang, Tongmin; Wen, Bin; Wang, Zhijun; Jie, Jinchuan; Cao, Zhiqiang; Ruan, Haihui; Li, Tingju
High-entropy alloys (HEAs) can have either high strength or high ductility, and a simultaneous achievement of both still constitutes a tough challenge. The inferior castability and compositional segregation of HEAs are also obstacles for their technological applications. To tackle these problems, here we proposed a novel strategy to design HEAs using the eutectic alloy concept, i.e. to achieve a microstructure composed of alternating soft fcc and hard bcc phases. As a manifestation of this concept, an AlCoCrFeNi2.1 (atomic portion) eutectic high-entropy alloy (EHEA) was designed. The as-cast EHEA possessed a fine lamellar fcc/B2 microstructure, and showed an unprecedented combination of high tensile ductility and high fracture strength at room temperature. The excellent mechanical properties could be kept up to 700░C. This new alloy design strategy can be readily adapted to large-scale industrial production of HEAs with simultaneous high fracture strength and high ductility. PMID:25160691
A study on the subgrain superplasticity of extruded Al-Al{sub 3}Ni eutectic alloy
Uan, J.Y.; Chen, L.H.; Lui, T.S.
A directionally solidified Al-Al{sub 3}Ni eutectic alloy was extruded to obtain micron-size subgrains with [111] fiber texture. The extrusion temperature was varied to have different distributions of the Al{sub 3}Ni eutectic particles. Choosing the fiber axis as the loading axis, the tensile test results at 500 C indicate that the elongation is concave downward and strain-rate dependent. Reducing the number of intragranular particles increases the maximum elongation as well as the strain rate of maximum elongation. With the particles residing only intergranularly in the as-extruded state, the maximum elongation, which occurs under the initial strain rate of 6.3 {times} 10{sup {minus}3} s{sup {minus}1}, is about 300 pct. This subgrain superplasticity is associated with low strain-rate sensitivity but high resistance against strain softening. The fiber texture is always retained, and the microstructure reveals slip of long parallel dislocations. If intragranular particles are also present in the as-extruded state, the occurrence of dislocation tangling and dynamic recovery will give rise to early onset of strain softening and inferior ductility.
Microstructural stability of directionally solidified eutectic NiAl-Mo under static and thermal cycling conditions
Kush, M.T.; Holmes, J.W.; Gibala, R. [Univ. of Michigan, Ann Arbor, MI (United States)
The quasi-binary eutectic NiAl-9% Mo with faceted molybdenum fibers was subjected to both thermal annealing conditions and to annealing under thermal cycling conditions to determine the microstructural stability of this alloy. The static temperature tests were run at 0.85T{sub M}--0.97T{sub M} in an argon gas atmosphere. The thermal cycling tests were performed between temperatures of 700 C and 1,200 C by induction heating disk-shaped specimens in an argon gas atmosphere using time-temperature heating and cooling profiles to approximate potential engine applications. To quantify microstructural changes, the fiber size and size distribution and number of fibers per unit area were measured as a function of time at temperature. The overall results demonstrate that the directionally solidified eutectic NiAl-9Mo subjected to thermal fatigue conditions exhibits cell boundary coarsening and large shape changes, whereas the microstructure under static stress-free annealing is stable.
THE THERMAL EXPANSION OF THE DIRECTIONALLY SOLIDIFIED Al-CuAl{sub 2} EUTECTIC
Baker, Dennis F.; Bragg, Robert H.
Alloys of Al- CuAl{sub 2} eutectic composition were prepared from 99.999% pure materials and directionally solidified in a temperature gradient of about 45░C/cm at different growth rates R. The {lambda}{sup 2}R = constant relation was verified and lamellar spacings of 7.5, 3.5, 2.6, 1.8 and 1.4 ~m were obtained. Dilatometer specimens were machined with axes aligned in the principal lamellae coordinate directions. Thermal expansion was measured by standard dilatometry (Cu standard) using a set point program cycling between room temperature and 500░C . Thermal expansion of the directionally solidified Al-CuAl{sub 2} eutectic is greatest in the growth direction (in the plane of the lamellae), least in the transverse direction (orthogonal to the growth direction in the plane of the lamellae) and intermediate in the vertical direction (normal to the lamellae) . The most significant finding of the study is that the thermal expansion increases with decreasing lamellar spacing between limits defined approximately by the thermal expansion of the CuAl{sub 2} phase alone and the predicted thermal expansion of an isotropic elastic model of the composite.
Eutectic mixed monolayers in equilibrium with phospholipid-bilayers and triolein-liquid phase.
Handa, T; Saito, H; Miyajima, K
Triolein (TO) and phospholipids (egg yolk phosphatidylcholine, egg yolk phosphatidylethanolamine, and bovine brain phosphatidylserine) had low mutual solubilities and separated into the TO-liquid phase and phospholipid-bilayers. Spreading pressures of the TO-phospholipid mixture (i.e., surface pressures of the mixed monolayer in equilibrium with the phase-separating lipid mixture) at the air/saline interface were independent of the lipid composition. On the other hand, collapse pressures of the mixed monolayer of TO and phospholipid (i.e., surface pressures of the mixed monolayer in equilibrium with the TO-liquid phase) at the interface changed with the monolayer composition and were lower than the spreading pressure. The experimental data indicated the spreading and collapse pressures as offering a phase diagram for the presence of equilibrium between the mixed monolayer, the phospholipid-bilayers and the TO-liquid phase. The diagram showed that TO and the phospholipids were miscible in the mixed monolayer, forming an eutectic mixed monolayer. When the mixed monolayer initially had the eutectic composition, no collapse of the monolayer was detected until the surface pressure reached the value of the spreading pressure. No specific complex between TO and the phospholipid is required to explain the stability and collapse of the mixed monolayers. The bulk immiscibility of the lipids elucidated by the spreading pressure-measurements, immediately leads to the phase behaviors observed. PMID:8369406
Research into the microstructure and mechanical behavior of eutectic Bi-Sn and In-Sn
Goldstein, J.L.F.; Mei, Z.; Morris, J.W. Jr. [Lawrence Berkeley Lab., CA (United States)]|[California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering
This manuscript reports on research into two low-melting, lead-free solder alloys, eutectic Bi-Sn and eutectic In-Sn. The microstructures were found to depend on both cooling rate and substrate, with the greatest variability in the In-Sn alloy. The nature of the intermetallic layer formed at the solder-substrate interface depends on both the solder and the substrate (Cu versus Ni). Also, the microstructure of the Bi-Sn can recrystallize during deformation, which is not the case with In-Sn. Data from creep and constant strain rate tests are given for slowly cooled samples. The creep behavior of In-Sn is constant with temperature, but the creep seems to be controlled by the In-rich phase in In-Sn on Cu and by the Sn-rich phase in In-Sn on Ni. Bi-Sn exhibits different creep behavior at temperatures above 40 {degrees}C than at 20 {degrees}C or lower. Stress-strain curves of Bi-Sn on Cu and In-Sn on Cu are similar, while In-Sn on Ni behaves differently. This is explained in terms of the deformation patterns in the alloys.
Phase Structure and Cyclic Deformation in Eutectic Tin-Lead Alloy: A Numerical Analysis
FANG,HUEI ELIOT; Li,W; SHEN,Y.-L
This study is devoted to providing a mechanistic rationale of coarsening induced failure in solder alloys during thermomechanical fatigue. Micromechanical modeling of cyclic deformation of eutectic tin-lead alloy was undertaken using the finite element method. The models consist of regularly arranged tin-rich and lead-rich phases, simulating the lamellar array and colony structure in a typical eutectic system. A fine structure and a coarse structure, bearing the same phase fraction but different in the aspect ratio of each lead-rich layer and in the number of lead-rich layers in each colony, are utilized for representing the microstructure before and after coarsening, respectively. Both phases are treated as elastic-plastic solids with their respective properties. For simplicity the creep effect is ignored without compromising the main objective of this study. Cyclic loading under pure shear and uniaxial conditions is modeled. It is found that both the fine and coarse structures exhibit essentially the same macroscopic stress-strain response. The coarse structure, however, shows a greater maximum effective plastic strain on a local scale throughout the deformation. The numerical result implies that, in a solder joint, a locally coarsened region may not be mechanically weaker than its surrounding, but it is subject to early damage initiation due to accumulated plasticity. Other implications regarding solder alloy failure and micromechanical modeling of two-phase materials are discussed.
Density functional theory study of the interfacial properties of Ni/Ni3Si eutectic alloy
NASA Astrophysics Data System (ADS)
Zhao, Yuhong; Wen, Zhiqin; Hou, Hua; Guo, Wei; Han, Peide
In order to clarify the heterogeneous nucleation potential of ?-Ni grains on Ni3Si particles in Ni-Ni3Si eutectic alloy, the work of adhesion (Wad), fracture toughness (G), interfacial energy (?i), and electronic structure of the index (0 0 1), (1 1 0) and (1 1 1) Ni/Ni3Si interfaces with two different cohesive manners are investigated using first-principles method based on density functional theory. Results indicate that the center site stacking sequence (OM) is preferable to continue the natural stacking sequence of bulk Ni and Ni3Si. Since OM stacking interfaces have larger Wad, G and ?i than that of the top site stacking (OT) interfaces. The Ni/Ni3Si (1 1 0) interface with OM stacking has the best mechanical properties. Therefore, the formation of this interface can improve the stability, ductility and fracture toughness of Ni-Ni3Si eutectic alloy. The calculated interfacial energy of Ni/Ni3Si (0 0 1), (1 1 0) and (1 1 1) interfaces with OM stacking proves the excellent nucleation potency of Ni3Si particles for ?-Ni phase from thermodynamic considerations. Besides, the electronic structure and chemical bonding of (1 1 0) interface with OM stacking are also discussed.
Review of fuel/cladding eutectic formation in metallic SFR fuel pins
Denman, M.; Todreas, N.; Driscoll, M. [MIT, 77 Mass Ave, Cambridge, MA 02139 (United States)
Sodium-cooled Fast Reactors (SFRs) remain a strong contender amongst the Generation IV reactor concepts. Metallic fuel has been a primary fuel option for SFR designers in the US and was used extensively in the first generation of SFRs. One of the benefits of metallic fuel is its chemical compatibility with the coolant; unfortunately this compatibility does not extend to steel cladding at elevated temperatures. It has been known that uranium, plutonium, and rare earths diffuse with cladding constituents to form a low melting point fuel/cladding eutectic which acts to thin the cladding once the interfacial temperature rises above the system liquidus temperature. Since the 1960's, many experiments have been performed and published to evaluate the rate of fuel/cladding eutectic formation and the temperature above which melting will begin as a function of fuel/cladding interfacial temperature, time at temperature, fuel constituents (uranium, fissium or uranium (plutonium) zirconium), cladding type (stainless steel 316, stainless steel 306, D9 or HT9), beginning of life linear power, plutonium enrichment and burnup. The results of these tests, however, remain scattered across conference and journal papers spanning 50 years. The tests used to collect this data also varied in experimental procedure throughout the years. This paper will consolidate the experimental data into four groups of similar test conditions and expand upon the testing performed for each group in detail. A companion paper in PSA 2011 will discuss predictive correlations formulated from this database. (authors)
Microstructure and thermoelectric properties of mechanically robust PbTe-Si eutectic composites.
Sootsman, J. R.; He, J.; Dravid, V. P.; Ballikaya, S.; Vermeulen, D.; Uher, C.; Kanatzidis, M. G. (Materials Science Division); (Northwestern Univ.); (Univ. of Michigan)
The microstructure and thermoelectric properties of the PbTe-Si eutectic system are presented in detail. When rapidly quenched from the melt this system yields materials with thermoelectric properties similar to PbTe itself but with improved mechanical properties. Doping optimization was performed using PbI{sub 2} as an n-type dopant giving precise control of the thermoelectric properties. Electron microscopy indicates that the PbTe-Si system is both a nanocomposite and microcomposite. Despite the added Si, the thermal conductivity of this composite follows closely that of PbTe. The temperature dependence of the Lorenz number was estimated, and it shows a significant departure from the value of metals (L{sub 0}) reaching only 45% of L{sub 0} at 650 K. The optimized ZT for the PbTe-Si(8%) eutectic was 0.9 at 675 K. The improved mechanical robustness of these composites makes them attractive for use in large scale thermoelectric device fabrication.
Solidification and thermal behaviour of binary organic eutectic and monotectic; succinonitrile pyrene system
NASA Astrophysics Data System (ADS)
Rai, U. S.; Pandey, Pinky
Transparent binary alloy models are important in metallurgical and materials science, as phase transformations can be observed during solidification. This communication concerns the solidification and thermal studies of succinonitrile (SCN)-pyrene (PY) system, which is an organic analogue of a metal-nonmetal-type system. Phase diagram of the SCN-PY system, determined by the thaw-melt method shows the formation of a monotectic and a eutectic at 143.3░C and 55.3░C with 0.025 and 0.744 mole fractions of SCN, respectively. The critical solution temperature of the system lies 48.7░C above the monotectic temperature. The growth velocity ( v) data at different undercoolings obtained from the capillary method, obey the Hillig-Turnbull equation, v= u(? T) n. The heats of fusion of the binary as well as single materials were obtained from the DSC (Mettler DSC-4000 system) from which the entropy of fusion, enthalpy of mixing, Jackson's roughness parameter, excess thermodynamic functions, interfacial energy and radius of the critical nucleus were calculated. The optical microphotographs of the eutectic and monotectic show their characteristic features.
Fondeur, F
The Modular Caustic-Side Solvent Extraction (CSSX) Unit (MCU) plans to use several new materials of construction not previously used with CSSX solvent. SRNL researchers tested seven materials proposed for service in seal and gasket applications. None of the materials leached detectable amounts of components into the CSSX solvent during 96 hour tests. All are judged acceptable for use based on their effect on the solvent. However, some of the materials adsorbed solvent or changed dimensions during contact with solvent. Consultation with component and material vendors with regard to performance impact and in-use testing of the materials is recommended. Polyetheretherketone (PEEK), a material selected for use in contactor bearing seals, did not gain weight or change dimensions on contact with CSSX solvent. Analysis of the solvent contacted with this material showed no impurities and the standard dispersion test gave acceptable phase separation results. The material contains a leachable hydrocarbon substance, detectable on exposed surfaces, that did not adversely contaminate the solvent within the limits of the testing. We recommend contacting the vendor to determine the source and purpose of this component, or, alternatively, pursue the infrared analysis of the PEEK in an effort to better define potential impacts.
Wide electrochemical window solvents for use in electrochemical devices and electrolyte solutions incorporating such solvents
Angell, Charles Austen (Mesa, AZ); Zhang, Sheng-Shui (Tucson, AZ); Xu, Kang (Tempe, AZ)
The present invention relates to electrolyte solvents for use in liquid or rubbery electrolyte solutions. Specifically, this invention is directed to boron-containing electrolyte solvents and boron-containing electrolyte solutions.
Quantitation of buried contamination by use of solvents. [degradation of silicone polymers by amine solvents
NASA Technical Reports Server (NTRS)
Pappas, S. P.; Hsiao, Y. C.; Hill, L. W.
Spore recovery form cured silicone potting compounds using amine solvents to degrade the cured polymers was investigated. A complete list of solvents and a description of the effect of each on two different silicone polymers is provided.
Recovery of Mn 2+, Co 2+ and Ni 2+ from manganese nodules by redox leaching and solvent extraction
Yong-feng SHEN; Wen-ying XUE; Wei LI; Shan-de LI; Xiang-hua LIU
The recovery of Mn, Co and Ni from deep-sea manganese nodules was conducted by acid oxidative leaching and solvent extraction. The results indicate that pyrrhotite used during leaching can effectively facilitate the leaching out of manganese, cobalt and nickel. The leaching behaviors of Mn, Ni and Co were determined and the influences of temperature, leaching time and sulphuric acid concentration
The influence of solvent type on solvent-pesticide interactions in bioassays
Glenn W. Stratton
The effect of solvent type on solvent-pesticide interactions was examined by interacting the fungicide captan with the solvents acetone, ethanol, methanol, hexane, dimethyl sulfoxide (DMSO), andN,N-dimethylformamide (DMF), using growth of the fungiPythium ultimum, Sclerotinia homeocarpa, andPestalotia sp. as a toxicity criterion. DMF, ethanol, and methanol were generally the most toxic solvents tested, yielding EC50 values from 0.51 to 2.29% (v\\/v).
Desorption of chlorine organic solvents
Petrova, N.I.; Nikolaev, K.M.
Adsorption methods are being used more and more widely to treat gaseous discharges containing chlorohydrocarbons. However, recovery of the chlorohydrocarbons has not been studied sufficiently, and the desorption of the solvents with steam is particularly understudied. We investigated desorption of a number of solvents from industrial active carbon AR-3. Desorption was done with live steam in the 105 to 150/sup 0/C. It can be seen from the data that with an increase of the molecular weight of the chlorohydrocarbon, the process of desorption slows down. This is clearly due to the fact that with an increase of the number of chlorine atoms in the molecule there is an increase of dispersion interaction (size of parachors) and latent heat of vaporization, which cause a decrease of the degree of desorption. The rate of desorption increases with an increase in temperature, but most of the investigated chlorine derivatives detach a chlorine ion at elevated temperature in the presence of water and carbon, with formation of HCl, which causes severe equipment corrosion. In addition, phosgene (in the decomposition of C/sub 2/HCl/sub 3/), chlorine organic acids and certain other toxic compounds may be produced. Thus, to reduce the rate of hydrolysis in the desorption of chlorohydrocarbons, especially polychlorinated ones, one should use steam with minimum possible temperature (no more than 110/sup 0/C) with a desorption time of no more than 30 minutes for poorly adsorbable compounds and no more than 45 to 60 minutes for readily absorbable ones. Here the degree of desorption of poorly absorbed compounds is about 100% while that of the readily absorbed ones is from 50 to 75%. The results were used in the design of units for recovery of methylene chloride, dichloroethane and trichloroethylene.
A Finite-Element-Based Methodology for Evaluating Solder Electromigration Current Limits of Sn\\/Pb Eutectic Solder Bumps
Walter Dauksher; Dennis H. Eaton; James D. Rowatt
This paper investigates the effect of current distribution to the bump and current crowding on the electromigration (EM) of Sn\\/Pb eutectic solder bumps. The peak current density in the bump is found to have a significant effect on the EM lifetime of the tested structures and, thus, impacts the maximum allowable bump current. A finite-element model is developed which accurately
Tensile Strength and Microstructure of Al2O3-ZrO2 Hypo-Eutectic Fibers Studied
NASA Technical Reports Server (NTRS)
Farmer, Serene C.; Sayir, Ali
Oxide eutectics offer high-temperature strength retention and creep resistance in oxidizing environments. Al2O3-ZrO2 eutectic strengths have been studied since the 1970's. Directionally solidified oxide eutectics exhibit improved resistance to slow crack growth and excellent strength retention at high temperatures up to 1400 C. Materials studied typically contain Y2O3 to metastably retain the high-temperature cubic and tetragonal polymorphs at room temperature. Al2O3-ZrO2 is of fundamental interest for creep studies because it combines a creep-resistant material, Al2O3, with a very low creep resistance material, ZrO2. Results on mechanical properties and microstructures of these materials will be used to define compositions for creep testing in future work. Substantial variations from the eutectic alumina to zirconia ratio can be tolerated without a loss in room-temperature strength. The effect of increasing Y2O3 addition on the room-temperature tensile strength of an Al2O3-ZrO2 material containing excess Al2O3 was examined at the NASA Glenn Research Center, where the materials were grown using Glenn's world-class laser growth facilities.
Influence of additives on the microstructure and tensile properties of near-eutectic Al¢10.8%Si cast alloy
A. M. A. Mohamed; A. M. Samuel; F. H. Samuel; H. W. Doty
The continuing quest for aluminum castings with enhanced mechanical properties for applications in the automotive industries has intensified the interest in aluminum¢silicon alloys. In Al¢Si alloys, the properties are influenced by the shape and distribution of the eutectic silicon particles in the matrix, as also by the iron intermetallics and copper phases that occur upon solidification. The detailed microstructure and
Mechanical properties of ZrC-ZrBŌ and ZrC-TiBŌ directionally solidified eutectics
Lamellar ZrC-ZrBŌ and Chinese-script ZrC-TiBŌ eutectics were directionally solidified using the floating-zone method of crystal growth. The Knoop microhardness, fracture toughness, and wear resistance were investigated as a function of the phase spacing. Nearly all of the directionally solidified specimens exhibited superior mechanical properties when compared with the individual constituents.
Effect of thermal cycling on structure and properties of a Co, Cr, Ni--TaC directionally solidified eutectic composite
F. M. Dunlevey; J. F. Wallace
The effect of thermal cycling on the structure and properties of a ; cobalt, chromium, nickel, tantalum carbide directionally solidified eutectic ; composite is reported. It was determined that the stress rupture properties of ; the alloy were decreased by the thermal cycling. The loss in stress rupture ; properties varied with the number of cycles with the loss in
Nanophase diagram of binary eutectic Au-Ge nanoalloys for vapor-liquid-solid semiconductor nanowires growth.
Lu, Haiming; Meng, Xiangkang
Although the vapor-liquid-solid growth of semiconductor nanowire is a non-equilibrium process, the equilibrium phase diagram of binary alloy provides important guidance on the growth conditions, such as the temperature and the equilibrium composition of the alloy. Given the small dimensions of the alloy seeds and the nanowires, the known phase diagram of bulk binary alloy cannot be expected to accurately predict the behavior of the nanowire growth. Here, we developed a unified model to describe the size- and dimensionality-dependent equilibrium phase diagram of Au-Ge binary eutectic nanoalloys based on the size-dependent cohesive energy model. It is found that the liquidus curves reduce and shift leftward with decreasing size and dimensionality. Moreover, the effects of size and dimensionality on the eutectic composition are small and negligible when both components in binary eutectic alloys have the same dimensionality. However, when two components have different dimensionality (e.g. Au nanoparticle-Ge nanowire usually used in the semiconductor nanowires growth), the eutectic composition reduces with decreasing size. PMID:26053237