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Vacuum casting of thick polymeric films
NASA Technical Reports Server (NTRS)
Bubble formation and layering, which often plague vacuum-evaporated films, are prevented by properly regulating process parameters. Vacuum casting may be applicable to forming thick films of other polymer/solvent solutions.
Cuddihy, E. F.; Moacanin, J.
Some properties of films cast from polyurethane aqueous dispersions of polyether-based anionomer extended with hydrazine
Microsoft Academic Search
Polyurethanes as aqueous dispersions were synthesized and some mechanical properties of the casted films were analysed. Anionomers prepolymers were prepared in bulk by the reaction of poly(propylene oxide), 4,4?-dicyclohexylmethane diisocyanate and dimethylolpropionic acid. The acid group's neutralization was carried out with triethylamine. The prepolymer was divided into two parts and to one of them acetone was added. The prepolymer was
F. M. B. Coutinho; M. C. Delpech
Fractal structures in casting films from chlorophyll
NASA Astrophysics Data System (ADS)
Chlorophyll (Chl) molecules are important because they can act as natural light-harvesting devices during the photosynthesis. In addition, they have potential for application as component of solar cell. In this work, we have prepared casting films from chlorophyll (Chl) and demonstrated the occurrence of fractal structures when the films were submitted to different concentrations. By using optical microscopy and the box-count method, we have found that the fractal dimension is Df = 1.55. This value is close to predicted by the diffusion-limited aggregation (DLA) model. This suggests that the major mechanism ¢ which determines the growth of the fractal structures from Chl molecules ¢ is the molecular diffusion. Since the efficiencies of solar cells depend on the morphology of their interfaces, these finds can be useful to improve this kind of device.
Pedro, G. C.; Gorza, F. D. S.; de Souza, N. C.; Silva, J. R.
Non-equilibrium behavior of spin-cast films
The behavior of polystyrene films cast from various solvents using an electric field to weakly perturb the free surface of the polymer melt was examined. The effective viscosity and residual stresses of the as-spun films strongly depend on the casting solvent. As-cast films had a substantially reduced viscosity compared to annealed films, with the greatest reduction in films cast from solutions near ?-temperature. The reduced viscosity is explained in terms of non-equilibrium effects from the film formation process; rapid quenching during spin-coating results in a lower entanglement density of chains compared to an equilibrium melt. The difference in films spun from the various solvents is explained by changes in chain conformations in the initial solutions and the vitrification point. The wavelength of the instabilities in as-cast films was higher than expected, indicating a weak stabilizing pressure. This is attributed to frozen-in normal stresses resulting from an asymmetric deformation of the chains due to evaporation of residual solvent after vitrification. The results show the non-equilibrium nature of as-cast polymer films and that processing conditions strongly influence their behavior.
Thomas, Katherine
Land-based turbine casting initiative
SciTech Connect
To meet goals for the ATS program, technical advances developed for aircraft gas turbine engines need to be applied to land-based gas turbines. These advances include directionally solidified and single crystal castings, alloys tailored to exploit these microstructures, complex internal cooling schemes, and coatings. The proposed program to scale aircraft gas turbine casting technology up to land based gas turbine size components is based on low sulfur alloys, casting process development, post-cast process development, and establishing casting defect tolerance levels. The inspection side is also discussed.
Mueller, B.A.; Spicer, R.A. [Howmet Corp., Whitehall, MI (United States)
Emulsion based cast booster - a priming system
This paper explores the potential of emulsion based cast booster to be used as primer to initiate bulk delivered emulsion explosives used in mines. An attempt has been made for comparative study between conventional cast booster and emulsion based cast booster in terms of the initiation process developed and their capability to develop and maintain the stable detonation process in the column explosives. The study has been conducted using a continuous velocity of detonation (VOD) measuring instrument. During this study three blasts have been monitored. In each blast two holes have been selected for study, the first hole being initiated with conventional cast booster while the other one with emulsion based cast booster. The findings of the study advocates that emulsion based cast booster is capable of efficient priming of bulk delivered column explosive with stable detonation process in the column. Further, the booster had advantages over the conventional PETN/TNT based cast booster. 5 refs., 2 figs., 1 tab., 1 photo.
Gupta, R.N.; Mishra, A.K. [National Institute of Rock Mechanics, KGF (India)
Bifilm Defects in Ni-Based Alloy Castings
The Ni-base superalloys, which are normally melted and cast in a vacuum, entrain their surface-oxide film during turbulent pouring of the melt; unfortunately at this time, this process is universally practiced for investment castings of these materials. The entrained film becomes a bifilm crack automatically, so that cast alloys have a large population of cracks that controls their failure behavior. The problems of the growth of single crystals and the welding of polycrystalline alloys are reviewed to illustrate the central role of bifilms in the cracking of turbine blades, the heat-affected zones of welds, and the reliability of properties. It has been demonstrated that improved gravity pouring systems can reduce these problems significantly, but only countergravity filling of molds is expected to result in defect-free castings. Recent cases in which turbine blades failed in service are examined, and the central role of bifilm defects in these failures is discussed.
Campbell, John; Tiryakio?lu, Murat
Tape Casting and Partial Melting of Bi-2212 Thick Films.
National Technical Information Service (NTIS)
To produce Bi-2212 thick films with high critical current densities tape casting and partial melting is a promising fabrication method. Bi-2212 powder and organic additives were mixed into a slurry and tape casted onto glass by the doctor blade tape casti...
Photophysical Studies of Spin-Cast Polymer Films.
Spin casting is a commonly used technique for producing thin, uniform polymer films, especially for semiconductor fabrication. There has been little attention given to the response of the polymers at the molecular level, however. We have reviewed previous...
L. L. Kosbar S. W. Kuan C. W. Frank R. F. Pease
Instability of cast film and its relevance to membrane morphology
The instability of a solution film cast on a solid support to form a membrane can lead to holes or other defects periodically on the membrane surface and these defects may reduce membrane performances. It was found that there are two reasons which can cause the film instability. One is very steep concentration gradient near the liquid¢gas interface, another is
Zhi Wang; Shichang Wang
Interfacial glass transition profiles in ultrathin, spin cast polymer films
Interfacial glass transition temperature (Tg) profiles in spin cast, ultrathin films of polystyrene and derivatives were investigated using shear-modulated scanning force microscopy. The transitions were measured as a function of film thickness (?), molecular weight, and crosslinking density. The Tg(?) profiles were nonmonotonic and exhibited two regimes: (a) a sublayer extending about 10 nm from the substrate, with Tg values lowered up to ~10 ░C below the bulk value, and (b) an intermediate regime extending over 200 nm beyond the sublayer, with Tg values exceeding the bulk value by up to 10 ░C. Increasing the molecular weight was found to shift the Tg(?) profiles further from the substrate interface, on the order of 10 nm/kDa. Crosslinking the precast films elevated the absolute Tg values, but had no effect on the spatial length scale of the Tg(?) profiles. These results are explained in the context of film preparation history and its influence on molecular mobility. Specifically, the observed rheological anisotropy is interpreted based on the combined effects of shear-induced structuring and thermally activated interdiffusion.
Sills, Scott; Overney, Renķ M.; Chau, Wilson; Lee, Victor Y.; Miller, Robert D.; Frommer, Jane
Interfacial glass transition profiles in ultrathin, spin cast polymer films.
Interfacial glass transition temperature (T(g)) profiles in spin cast, ultrathin films of polystyrene and derivatives were investigated using shear-modulated scanning force microscopy. The transitions were measured as a function of film thickness (delta), molecular weight, and crosslinking density. The T(g)(delta) profiles were nonmonotonic and exhibited two regimes: (a) a sublayer extending about 10 nm from the substrate, with T(g) values lowered up to approximately 10 degrees C below the bulk value, and (b) an intermediate regime extending over 200 nm beyond the sublayer, with T(g) values exceeding the bulk value by up to 10 degrees C. Increasing the molecular weight was found to shift the T(g)(delta) profiles further from the substrate interface, on the order of 10 nm/kDa. Crosslinking the precast films elevated the absolute T(g) values, but had no effect on the spatial length scale of the T(g)(delta) profiles. These results are explained in the context of film preparation history and its influence on molecular mobility. Specifically, the observed rheological anisotropy is interpreted based on the combined effects of shear-induced structuring and thermally activated interdiffusion. PMID:15267406
Sills, Scott; Overney, Renķ M; Chau, Wilson; Lee, Victor Y; Miller, Robert D; Frommer, Jane
A Universal Nucleation Mechanism for Solvent Cast Polymer Film Rupture
It is shown that the intrinsic stress in solvent cast polymer coatings plays a key role in the nucleation of holes in the film. Nucleation is important because it is meanwhile clear that heterogeneous nucleation is the only relevant rupture mechanism for the technologically relevant thickness regime well above 100 nm. The most striking feature is that in contrast to
Daniel Podzimek; Annemarie Saier; Ralf Seemann; Karin Jacobs; Stephan Herminghaus
Modeling flow induced crystallization in film casting of polypropylene
Data from iPP film casting experiments served as a basis to model the effect of flow on polymer crystallization kinetics. These data describe the temperature, width, velocity and crystallinity distributions along the drawing direction under conditions permitting crystallization along the draw length. In order to model the effect of flow on crystallization kinetics, a modification of a previously defined quiescent
Giuseppe Titomanlio; Gaetano Lamberti
On the membrane approximation in isothermal film casting
In this work, a one-dimensional model for isothermal film casting is studied. Film casting is an important engineering process to manufacture thin films and sheets from a highly viscous polymer melt. The model equations account for variations in film width and film thickness, and arise from thinness and kinematic assumptions for the free liquid film. The first aspect of our study is a rigorous discussion of the existence and uniqueness of stationary solutions. This objective is approached via the argument principle, exploiting the homotopy invariance of a family of analytic functions. As our second objective, we analyze the linearization of the governing equations about stationary solutions. It is shown that solutions for the associated boundary-initial value problem are given by a strongly continuous semigroup of bounded linear operators. To reach this result, we cast the relevant Cauchy problem in a more accessible form. These transformed equations allow us insight into the regularity of the semigroup, thus yielding the validity of the spectral mapping theorem for the semigroup and the spectrally determined growth property.
Hagen, Thomas
NSDL National Science Digital Library
The Council for Agricultural Science and Technology (CAST) was formed in 1972 as a result of a meeting sponsored by the National Academy of Sciences' National Research Council. CAST's mission is to "assemble, interpret, and communicate credible science-based information regionally, nationally, and internationally to legislators, regulators, policymakers, the media, the private sector and the public." Visitors will find the Education tab near the top of the page to be particularly helpful for those who want to pursue agricultural careers or learn about agricultural education, such as 4-H or Future Farmers of America. The CAST Videos section has a number of PowerPoint presentations on current topics of importance in agriculture, such as "The Science and Regulation of Food from Genetically Engineered Animals," "Food Safety and Fresh Produce," and "Probiotics in Human Health." A number of the papers that accompany the PowerPoint presentations are available for free.
Tape casting and partial melting of Bi-2212 thick films
To produce Bi-2212 thick films with high critical current densities tape casting and partial melting is a promising fabrication method. Bi-2212 powder and organic additives were mixed into a slurry and tape casted onto glass by the doctor blade tape casting process. The films were cut from the green tape and partially molten on Ag foils during heat treatment. We obtained almost single-phase and well-textured films over the whole thickness of 20 microns. The orientation of the (a,b)-plane of the grains was parallel to the substrate with a misalignment of less than 6 deg. At 77 K/0T a critical current density of 15, 000 A/sq cm was reached in films of the dimension 1 cm x 2 cm x 20 microns (1 micron V/cm criterion, resistively measured). At 4 K/0T the highest value was 350,000 A/sq cm (1 nV/cm criterion, magnetically measured).
Buhl, D.; Lang, Th.; Heeb, B.; Gauckler, L. J.
Buhl, D.; Lang, TH.; Heeb, B.; Gauckler, L. J.
Numerical modelling of entrainment of oxide film defects in filling of aluminium alloy castings
Recent advances in understanding the filling process during casting have indicated that metal flow conditions play key roles in controlling the quality of the casting.2,15 Inappropriate filling of castings usually cause surface oxide films to be folded into the bulk liquid or broken due to a higher liquid metal kinematic energy, resulting in so-called \\
Xiaogang Yang; Xiaobing Huang; Xiaojun Dai; John Campbell; Joe Tatler
Study of anisotropy of spin cast and vapor deposited polyimide films using internal reflection techniques
We have compared anisotropy of spin cast and vapor deposited polyimide (VDP) films, using internal reflection infrared spectroscopy. The films were deposited directly on the internal reflection element. We find that spin cast films are more anisotropic than their VDP counterparts, with the polyimide chains tending to align parallel to the substrate. Both films are found to contain more and less ordered regions. Within the ordered regions, the plane of the phenyl ring tends to align parallel to the substrate.
Liberman, V.
Solution based-spin cast processed organic bistable memory device
A two terminal organic bistable memory was fabricated by solution based spin casting of thin films of poly-[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene] (MEHPPV):ZnO nanoparticles onto ITO coated glass. The morphology of the thin films were characterized by Raman and FTIR spectroscopies. The electrical characterization showed that the two-terminal device exhibited excellent switching characteristics with ON/OFF ratio greater than 1 ū 104 when the voltage was swept between -1 V and +1 V. The device maintained its state even after removal of the bias voltage. The device exhibited stable performance at various performance tests. Two distinct capacitance states with hysteresis were observed and we suggest that the switching mechanism involved could be attributed to trapping and detrapping of electrons.
Ramana, CH. V. V.; Moodley, M. K.; Kannan, V.; Maity, A.
High-mobility spin-cast organic thin film transistors
We report high-mobility organic thin film transistors (OTFTs) with good uniformity using the small molecule organic semiconductor 2,8-difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene (diF-TESADT). diF-TESADT was spin cast to form OTFTs with a carrier mobility of more than 1.5 cm2/V s and shows a useful differential microstructure on or near pentaflorobenzenethiol (PFBT) treated Au source/drain electrodes compared to untreated Au or gate dielectric areas with improved molecular order observed on PFBT treated Au electrodes. For short channel length devices diF-TESADT crystal grains extend between the source and drain electrodes, resulting in increasing OTFT field effect mobility for decreasing gate length.
Park, Sung Kyu; Mourey, Devin A.; Subramanian, Sankar; Anthony, John E.; Jackson, Thomas N.
Aqueous suspensions for tape-casting based on acrylic binders
The use of water-based systems represents an interesting alternative to the widespread non-aqueous tape-casting but the low strength of water-based binders generally limits their applicability. A tape-casting slurry is a complex system where each organic component has a substantial effect on the rheological behaviour. In this study the effect of the dispersant and binders in alumina aqueous tape-casting slurries were
C. Pagnoux; T. Chartier; M. de F. Granja; F. Doreau; J. M. Ferreira; J. F. Baumard
Characterization of Bimetallic Castings with an Austenitic Working Surface Layer and an Unalloyed Cast Steel Base
The paper presents the technology of bimetallic castings based on the founding method of layer coating directly in the cast process of the so-called method of mold cavity preparation. The prepared castings consist of two fundamental parts, i.e., the base and the working surface layer. The base part of the bimetallic casting is typical foundry material, i.e., unalloyed cast steel, whereas the working layer is a plate of austenitic alloy steel sort X2CrNi 18-9. The quality of the joint between the base part and the working layer was evaluated on the basis of ultrasonic non-destructive testing and structure examinations containing metallographic macro- and microscopic studies with the use of a light microscope (LOM) with microhardness measurements and a scanning electron microscope (SEM) with microanalysis of the chemical composition (energy dispersive spectroscopyŚEDS). On the basis of the obtained results it was confirmed that the decisive phenomena needed to create a permanent joint between the two components of the bimetallic casting are carbon and heat transport in the direction from the high-carbon and hot base material which was poured into the mold in the form of liquid metal to the low-carbon and cold material of the working layer which was placed in the mold cavity in the form of a monolithic insert.
Wr¾bel, Tomasz
Electroconductive PET/SWNT Films by Solution Casting
The market for electrically conductive polymers is rapidly growing, and an emerging pathway for attaining these materials is via polymer-carbon nanotube (CNT) nanocomposites, because of the superior properties of CNTs. Due to their excellent electrical properties and anisotropic magnetic susceptibility, we expect CNTs could be easily aligned to maximize their effectiveness in imparting electrical conductivity to the polymer matrix. Single-walled carbon nanotubes (SWNT) were dispersed in a polyethylene terephthalate (PET) matrix by solution blending then cast onto a glass substrate to create thin, flexible films. Various SWNT loading concentrations were implemented (0.5, 1.0, and 3.0 wt.%) to study the effect of additive density. The processing method was repeated to produce films in the presence of magnetic fields (3 and 9.4 Tesla). The SWNTs showed a high susceptibility to the magnetic field and were effectively aligned in the PET matrix. The alignment was characterized with Raman spectroscopy. Impedance spectroscopy was utilized to study the electrical behavior of the films. Concentration and dispersion seemed to play very important roles in improving electrical conductivity, while alignment played a secondary and less significant role. The most interesting result proved to be the effect of a magnetic field during processing. It appears that a magnetic field may improve dispersion of unmodified SWNTs, which seems to be more important than alignment. It was concluded that SWNTs offer a good option as conductive, nucleating filler for electroconductive polymer applications, and the utilization of a magnetic field may prove to be a novel method for CNT dispersion that could lead to improved nanocomposite materials.
Steinert, Brian W.; Dean, Derrick R.
Morphological characterization of ╬▓ phase in poly-(vinylidenefluoride) film prepared by spin cast method
Poly-(Vinylidene fluoride) PVDF film was prepared by spin casting method to control the pore size of the matrix. The morphological spherulitic structure was confirmed Scanning Electron Microscopy (SEM) after gold sputtering and the presence of ? phase was ensured in spin cast PVDF film by the FTIR spectroscopy. The ? phase is very important in the application because it improve the properties like piezoelectricity by modifying PVDF crystallinity.
Mehtani, Hitesh Kumar; Kumar, Rishi; Raina, K. K.
Storage stability and antibacterial activity against Escherichia coli O157:H7 of carvacrol in edible apple films made by two different casting methods.
The antimicrobial activities against Escherichia coli O157:H7 as well as the stability of carvacrol, the main constituent of oregano oil, were evaluated during the preparation and storage of apple-based edible films made by two different casting methods, continuous casting and batch casting. Antimicrobial assays of films and high-performance liquid chromatography (HPLC) analysis of film extracts following storage up to 49 days at 5 and 25 degrees C revealed that (a) optimum antimicrobial effects were apparent with carvacrol levels of approximately 1.0% added to the purees prior to film preparation, (b) carvacrol in the films and film weights remained unchanged over the storage period of up to 7 weeks, and (c) casting methods affected carvacrol concentration, bactericidal activity, physicochemical properties, and colors of the apple films. Carvacrol addition to the purees used to prepare the films reduced water vapor and oxygen permeability of apple films. The results indicate that carvacrol has a dual benefit. It can be used to both impart antimicrobial activities and enhance barrier properties of edible films. The cited observations facilitate relating compositional and physicochemical properties of apple puree films containing volatile plant antimicrobials to their use in foods. PMID:18366181
Du, Wen-Xian; Olsen, Carl W; Avena-Bustillos, Roberto J; McHugh, Tara H; Levin, Carol E; Friedman, Mendel
Oxide films, pores and the fatigue lives of cast aluminum alloys
In the absence of gross defects such as cold shuts, the fatigue properties of castings are largely determined by the sizes of microstructural defects, particularly pores and oxide films. In contrast, the effects of grain size, second-phase particles, and nonmetallic inclusions are insignificant. The authors review the fatigue properties of castings made by gravity die casting, sand casting, lost-foam casting, squeeze casting, and semisolid casting, and compare A356/357 alloys with 319-type alloys. The application of fracture mechanics enables the properties to be rationalized in terms of the defects that are characteristic of each casting process, noting both the sizes and types of defect. The differences in the properties of castings are entirely attributed to their different defect populations. No single process is inherently superior. For defects of the same size (in terms of projected area normal to the loading direction), oxide films are less detrimental to fatigue life than pores. Areas of current controversy are highlighted and suggestions for further work are made.
Wang, Q. G.; Crepeau, P. N.; Davidson, C. J.; Griffiths, J. R.
Grain Refinement of Permanent Mold Cast Copper Base Alloys
Grain refinement is a well established process for many cast and wrought alloys. The mechanical properties of various alloys could be enhanced by reducing the grain size. Refinement is also known to improve casting characteristics such as fluidity and hot tearing. Grain refinement of copper-base alloys is not widely used, especially in sand casting process. However, in permanent mold casting of copper alloys it is now common to use grain refinement to counteract the problem of severe hot tearing which also improves the pressure tightness of plumbing components. The mechanism of grain refinement in copper-base alloys is not well understood. The issues to be studied include the effect of minor alloy additions on the microstructure, their interaction with the grain refiner, effect of cooling rate, and loss of grain refinement (fading). In this investigation, efforts were made to explore and understand grain refinement of copper alloys, especially in permanent mold casting conditions.
M.Sadayappan; J.P.Thomson; M.Elboujdaini; G.Ping Gu; M. Sahoo
Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey
56. DETAIL OF BASE OF STEEL WINDMILL TOWER WITH CAST IRON HAND PUMP OVER WELL HEAD ON HIGHWAY L44 IN IOWA JUST EAST OF NEBRASKA CITY, NEBRASKA. - Kregel Windmill Company Factory, 1416 Central Avenue, Nebraska City, Otoe County, NE
10. DETAIL OF CAST IRON COLUMN BASE ON FIRST FLOOR STOREFRONT, SHOWING MANUFACTURER'S STAMP: IOWA IRON WOKS CO. DUBUQUE. VIEW TO SOUTHWEST. - Commercial & Industrial Buildings, Dubuque Seed Company Warehouse, 169-171 Iowa Street, Dubuque, Dubuque County, IA
DETAIL VIEW OF BASE OF CAST IRON TOWER SHOWING THE FABRICATING MARK OF STARBUCK IRON WORKS, TROY, NY - Bidwell Bar Suspension Bridge & Stone Toll House, Near Lake Oroville (moved from fork of Feather River), Oroville, Butte County, CA
The interplay of membrane formation and drug release in solution-cast films of polylactide polymers.
The interplay of phase inversion and drug release has been studied for films of several biodegradable polylactide polymers cast from solutions containing polymer, solvent, and drug (naproxen). Variables studied included polymer type and concentration, solvent type, and film casting conditions (i.e. free or forced convection, humidity). Film morphologies and thermal properties indicate that reduction of the T(g) of the amorphous poly (lactide-co-glycolide) (PLGA) and poly (d, l-lactide) (PDLLA) systems caused by the drug, inhibits stabilization of a porous, structure, regardless of dry casting conditions and drug loads. Porous membranes could be formed by wet casting; however, drug loss during casting, makes this a non-viable process. For semi-crystalline PLLA, membrane morphologies could be varied by controlling the mass transfer path to form a single-phase dense film by polymer crystallization or a liquid-liquid two-phase structure followed by locking-in by polymer crystallization. However, the lack of drug solubility in the crystalline phase leads to unfavorable drug distributions most often leading to a burst release. Release profiles for all three polymers were found to follow a two-stage release model, with a first stage diffusive release followed by zero-order release in the second stage due to polymer erosion. PMID:20025948
Ma, Decheng; McHugh, Anthony J
Undulation instability in drop-cast poly(3-hexylthiophene) film originated from self-assembly
In this study, we characterize the undulated structures which appear at the edge of drop-cast regio-regular poly(3-hexylthiophene) (rr-P3HT, head-to-tail > 95%) film using optical microscopy and atomic force microscopy. We propose that these periodic structures originate from the undulations of the layered structure of liquid crystal-air interface. Evidence of rr-P3HT solution forming liquid crystalline phases at higher concentrations was obtained by the observation of distinct birefringence and characteristic textures under crossed polarizers using an optical microscope. Synchrotron x-ray diffraction pattern provides additional structural information at the undulated area compared with those at the area without undulated pattern. Based on these experimental results, we propose rr-P3HT solution can form a lyotropic liquid crystal at specific concentrations. This work was partially supported by NSF funding (DMR-0706235).
Park, Min Sang; Aiyar, Avishek; Park, Jung Ok; Reichmanis, Elsa; Srinivasarao, Mohan
Conductivity mechanism of polyaniline organic films: the effects of solvent type and casting temperature
In this work, we report a study of the effect of the solvent type and the casting temperature on the electrical properties of pure fully doped conducting polymer films (polyaniline, PANI). PANI was dispersed in two different solvents (dichloroacetic acid (DCAA), and a mixture of dichloro-acetic acid and formic acid (DCAA-FA)). Previous work showed that at around 318 K, a second order liquid-liquid structural transition occurs in the dispersions. Consequently, we have chosen three different casting temperatures (298 'room temperature', 318 and 353 K). The electrical properties of the cast films were investigated in the frequency range 100 Hz-1 MHz. The temperature was varied between 20 and 300 K. We found that the dc conductivity is governed by Mott's three-dimensional variable range hopping model for the PANI/DCAA films and by a fluctuation induced tunnelling model (FIT) for the PANI/DCAA-FA films. The different Mott and FIT parameters have been evaluated. The dependence of such values on the processing parameters is discussed. The x-ray diffraction technique was also used. A reasonable correlation between microstructure and electrical properties was found. Furthermore, the films cast at the structural transition temperature had the lowest conductivity.
Bohli, Nadra; Gmati, Fethi; Belhadj Mohamed, Abdellatif; Vigneras, Valķrie; Miane, Jean-Louis
High Resolution XPS of Crystalline and Amorphous Poly(ethylene terephthalate): A Study of Biaxially Oriented Film, Spin Cast Film and Polymer Melt.
High resolution monochromated x-ray photoelectron spectroscopy (XPS) (core line and valence band) was used to study poly(ethylene terephthalate) (PET) as biaxially oriented crystalline film, spin cast amorphous film and amorphous polymer melt. On going fr...
G. Beamson D. T. Clark N. W. Hayes D. S. L. Law V. Siracusa A. Recca
Using 'cling film' to protect lower limb plaster casts in babies with club foot.
Clubfoot or congenital talipes equinovarus is a common condition affecting babies and non-surgical treatment involves serial manipulation and plaster casting for many weeks. The casts are susceptible to soiling during this time, which makes management and child care even more challenging. The authors report initial experience in a typical district general hospital clubfoot clinic where the parents of a baby used conventional cling film to cover the casts and provide a low-cost, effective and well-tolerated method of protection. Informal reports received from these parents were very positive and encouraging throughout the duration of treatment. The authors believe parents with babies undergoing such treatment for clubfoot could be advised of the benefits of using cling film to protect plaster casts. More formal analysis of feedback from parents and collaborative experience with other hospitals is required before widespread use is recommended. There may also be scope for using cling film to protect lower limb casts used in managing developmental dysplasia of the hip or fractures in children and potentially adults. PMID:18073686
Patel, Nirav K; Jeer, P J S; Cornell, Mark S
Cast thermally stable high temperature nickel-base alloys and casting made therefrom
A cast thermally stable high temperature nickel-base alloy characterized by superior oxidation resistance, sustainable hot strength and retention of ductility on aging is provided by maintaining the alloy chemistry within the composition molybdenum 13.7% to 15.5%; chromium 14.7% to 16.5%; carbon up to 0.1%, lanthanum in an effective amount to provide oxidation resistance up to 0.08%; boron up to 0.015%;
D. A. Acuncius; R. B. Herchenroeder; R. W. Kirchner; W. L. Silence
Effects of solid substrate on structure and properties of casting waterborne polyurethane\\/carboxymethylchitin films
We prepared two series of semiinterpenetrating polymer network (semi-IPN) films from cross-linked waterborne polyurethane (WPU) and carboxymethylchitin (CMCH) in the aqueous solution on the glass and Teflon as the hydrophilic and hydrophobic substrates, respectively, by casting method. The chemical compositions, structure and morphologies of the films were examined by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron
Ming Zeng; Lina Zhang; Yuxiang Zhou
Radial Dependence of Spin-Cast Polymer/Clay Nanocomposite Film Thickness
The thickness of spin-cast PS (polystyrene), PMMA (polymethylmethacrylate), and PB (polybutadiene) films on silicon wafers are examined as a function of solvent concentration, concentration of clay (Cloisite 6A) filler, and spin rate. A strong radial dependence of film thickness is observed in the clay composite films. As film thickness is a competition between evaporation rate and viscous flow, these properties are independently measured. Evaporation is determined by weight loss measurements, while viscosity vs. shear rate is measured in an ARES rheometer. Film thickness for composite films is determined by measuring scratch depths with a Dektak surface profilometer. Clay orientation within the film is examined by transmission electron microscopy. The viscosity and evaporation rate data are fed into a simple computer algorithm, which provides a semi-quantitative description of the data obtained. The radial dependence predicted by this simple physical model is too weak, however, most probably owing to the effects of clay platelet alignment during the spinning process.
Li, Jun; Singh, Avtar; Schiffman, Scott; Kapoor, Deepak; Schwarz, Steven; Sokolov, Jonathan; Rafailovich, Miriam
Solution Casting and Transfer Printing Single-Walled Carbon Nanotube Films
This paper presents methods for solution casting and transfer printing collections of individual single-walled carbon nanotubes (SWNTs) onto a wide range of substrates, including plastic sheets. The deposition involves introduction of a solvent that removes surfactant from a suspension of SWNTs as it is applied to a substrate. The subsequent controlled flocculation (cF) produces films of SWNTs with densities that
Matthew A. Meitl; Yangxin Zhou; Anshu Gaur; Seokwoo Jeon; Monica L. Usrey; Michael S. Strano; John A. Rogers
Effect of transglutaminase treatment on the properties of cast films of soy protein isolates.
The objective of this work was to investigate the effect of microbial transglutaminase (MTGase) treatment on the properties and microstructures of soy protein isolate (SPI) films cast with 0.6 plasticizer per SPI (gg(-1)) of glycerol, sorbitol and 1:1 mixture of glycerol and sorbitol, respectively. Tensile strength (TS), elongation at break (EB), water vapor transmission rate (WVTR) or water vapor permeability (WVP), moisture content (MC), total soluble matter (TSM), lipid barrier property and surface hydrophobicity of control and MTGase-treated films were evaluated after conditioning film specimens at 25 degrees C and 50% relative humidity (RH) for 48 h. The treatment by 4 units per SPI (Ug(-1)) of MTGase increased the TS and surface hydrophobicity by 10-20% and 17-56%, respectively, and simultaneously significantly (P< or =0.05) decreased the E, MC and transparency. The WVTR or TSM of SPI films seemed to be not significantly affected by enzymatic treatment (P>0.05). The MTGase treatment also slowed down the moisture loss rate of film-forming solutions with various plasticizers during the drying process, which was consistent with the increase of surface hydrophobicity of SPI films. Microstructural analyses indicated that the MTGase-treated films of SPI had a rougher surface and more homogeneous or compact cross-section compared to the controls. These results suggested that the MTGase treatment of film-forming solutions of SPI prior to casting could greatly modify the properties and microstructures of SPI films. PMID:16084619
Tang, Chuan-He; Jiang, Yan; Wen, Qi-Biao; Yang, Xiao-Quan
Reducing disk flutter by improving aerodynamic design of base castings
The purpose of this paper is to present two aerodynamically designed base castings that could substantially reduce disk flutter due to turbulent excitations in high-speed disk drives. The first design includes aerodynamic brackets to smooth the shroud contour and an extended shroud to reduce the shroud opening. The second design is a Velcro treatment to modify turbulence generation. Experimental results
Baekho Heo; I. Y. Shen; James J. Riley
Surface energy modification by spin-cast, large-area graphene film for block copolymer lithography.
We demonstrate a surface energy modification method exploiting graphene film. Spin-cast, atomic layer thick, large-area reduced graphene film successfully played the role of surface energy modifier for arbitrary surfaces. The degree of reduction enabled the tuning of the surface energy. Sufficiently reduced graphene served as a neutral surface modifier to induce surface perpendicular lamellae or cylinders in a block copolymer nanotemplate. Our approach integrating large-area graphene film preparation with block copolymer lithography is potentially advantageous in creating semiconducting graphene nanoribbons and nanoporous graphene. PMID:20738125
Kim, Bong Hoon; Kim, Ju Young; Jeong, Seong-Jun; Hwang, Jin Ok; Lee, Duck Hyun; Shin, Dong Ok; Choi, Sung-Yool; Kim, Sang Ouk
Functional properties of chitosan-based films.
Chitosan-based films plasticized with glycerol were prepared by casting with the aim to obtain environmentally friendly materials for packaging applications. Different contents of glycerol were incorporated into chitosan solutions to improve mechanical properties and all films obtained were flexible and transparent. It was observed that the transparency and good behaviour of the films against UV radiation were not affected by chitosan molecular weight or glycerol content. Moreover, chitosan-based films exhibited excellent barrier properties against water vapour and oxygen, even with the addition of glycerol. The effect of the plasticizer on the properties has been explained using Fourier transform infrared (FTIR) spectroscopic analysis. The changes observed in the intensity of the bands showed that glycerol interacts with chitosan, which could be confirmed by total soluble matter (TSM). PMID:23465939
Leceta, I; Guerrero, P; de la Caba, K
Effect of carboxymethyl cellulose concentration on physical properties of biodegradable cassava starch-based films
BACKGROUND: Cassava starch, the economically important agricultural commodity in Thailand, can readily be cast into films. However, the cassava starch film is brittle and weak, leading to inadequate mechanical properties. The properties of starch film can be improved by adding plasticizers and blending with the other biopolymers. RESULTS: Cassava starch (5%w\\/v) based films plasticized with glycerol (30 g\\/100 g starch)
Wirongrong Tongdeesoontorn; Lisa J Mauer; Sasitorn Wongruong; Pensiri Sriburi; Pornchai Rachtanapun
Fatty acid-based polyurethane films for wound dressing applications
Fatty acid-based polyurethane films were prepared for use as potential wound dressing material. The polymerization reaction\\u000a was carried out with or without catalyst. Polymer films were prepared by casting-evaporation technique with or without crosslink-catalyst.\\u000a The film prepared from uncatalyzed reaction product with crosslink-catalyst gave slightly higher crosslink density. The mechanical\\u000a tests showed that, the increase in the tensile strength and
Guncem Gultekin; Cigdem Atalay-Oral; Sibel Erkal; Fikret Sahin; Djursun Karastova; S. Birgul Tantekin-Ersolmaz; F. Seniha Guner
Fatty acid-based polyurethane films were prepared for use as potential wound dressing material. The polymerization reaction was carried out with or without catalyst. Polymer films were prepared by casting-evaporation technique with or without crosslink-catalyst. The film prepared from uncatalyzed reaction product with crosslink-catalyst gave slightly higher crosslink density. The mechanical tests showed that, the increase in the tensile strength and
G. Gultekin; C. Ataly-Oral; S. Erkai; F. Sahin; D. Karastova; S. Tatntekin-Ersolmaz; F. Guner
Preparation of Na-beta?-alumina film by tape casting process
This study focused on the preparation of Na-beta?-alumina film by a tape casting process. The effects of solvent, dispersant, binder, plasticizer contents, as well as milling time on the rheological properties of the slurry were investigated. The dispersion of the ceramic powder in the slurry was optimized by ball milling an azeotropic mixture of methyethylketone (MEK) and ethanol (EtOH) as
Ning Li; Zhaoyin Wen; Yu Liu; Xiaogang Xu; Jiu Lin; Zhonghua Gu
Nonsolvent effects on morphology of cellulose acetate films prepared by dry-cast process
Cellulose acetate (CA) porous films were prepared by a dry-cast process from CA\\/acetone\\/nonsolvent systems. Isopropanol, ethanol and water were used as the nonsolvent and their effects on the formation of the porous structure of the CA matrix were investigated. As acetone evaporated from the solution, the mass ratios of both CA and the nonsolvent increased, finally inducing a porous structure
C. F. Wang; Y. An; Q. H. Li; S. J. Wan; W. X. Chen; X. D. Liu
Dense polymer film and membrane formation via the dry-cast process part I. Model development
The dry-cast membrane-formation process is a major phase-inversion technique by which asymmetric membranes are manufactured. In this paper a fully predictive model which incorporates coupled heat and mass transfer is developed to describe the evaporation of both solvent and nonsolvent from an ini- tially homogeneous polymer\\/solvent\\/nonsolvent system. This unsteady-state, one-dimensional, coupled heat- and mass-transport model allows for local film shrinkage
Saeed S. Shojaie; William B. Krantz; Alan R. Greenberg
Cast iron-base alloy for cylinder/regenerator housing
NASACC-1 is a castable iron-base alloy designed to replace the costly and strategic cobalt-base X-40 alloy used in the automotive Stirling engine cylinder/generator housing. Over 40 alloy compositions were evaluated using investment cast test bars for stress-rupture testing. Also, hydrogen compatibility and oxygen corrosion resistance tests were used to determine the optimal alloy. NASACC-1 alloy was characterized using elevated and room temperature tensile, creep-rupture, low cycle fatigue, heat capacity, specific heat, and thermal expansion testing. Furthermore, phase analysis was performed on samples with several heat treated conditions. The properties are very encouraging. NASACC-1 alloy shows stress-rupture and low cycle fatigue properties equivalent to X-40. The oxidation resistance surpassed the program goal while maintaining acceptable resistance to hydrogen exposure. The welding, brazing, and casting characteristics are excellent. Finally, the cost of NASACC-1 is significantly lower than that of X-40.
Witter, Stewart L.; Simmons, Harold E.; Woulds, Michael J.
Application in casting defect lossless examination based on surf
Based on the study of measures of the algorithm casting defect lossless examination and characteristics of X-ray imaging, a new automatic detection based on SURF is presented. Firstly, the algorithm detects the interested points of specifically component model in the standard image samples by SURF. Then the interested points of inspection produce are detected when the rotary worktable makes one revolution, at the same time, the interested points between model and produce are matched. The number of matched points is the basis for whether the product contains the component. Experimental results show that this method is effective in determining the component model well or not, which provides a novel method for casting defect lossless examination.
Fan, Youchen; Sun, Huayan; Wang, Haoxiang
Method of casting pitch based foam
A process for producing molded pitch based foam is disclosed which minimizes cracking. The process includes forming a viscous pitch foam in a container, and then transferring the viscous pitch foam from the container into a mold. The viscous pitch foam in the mold is hardened to provide a carbon foam having a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts.
Klett, James W. (Knoxville, TN)
Fluid casting of particle-based articles
A method for the production of articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is introduced into an immiscible, heated fluid. The slurry sets or hardens into a shape determined by the physical characteristics of the fluid and the manner of introduction of the slurry into the fluid. For example, the slurry is pulse injected into the fluid to provide spherical articles. The hardened spheres may then be sintered to consolidate the particles and provide a high density product.
Menchhofer, Paul (Oak Ridge, TN)
A method is disclosed for the production of articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is introduced into an immiscible, heated fluid. The slurry sets hardens into a shape determined by the physical characteristics of the fluid and the manner of introduction of the slurry into the fluid. For example, the slurry is pulse injected into the fluid to provide spherical articles. The hardened spheres may then be sintered to consolidate the particles and provide a high density product. 1 figure.
Menchhofer, P.
Casting of particle-based hollow shapes
A method for the production of hollow articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is coated onto a prewarmed continuous surface in a relatively thin layer so that the slurry is substantially uniformly coated on the surface. The heat of the prewarmed surface conducts to the slurry to initiate a reaction which causes the slurry to set or harden in a shape conforming to the surface. The hardened configurations may then be sintered to consolidate the particles and provide a high density product.
A method is disclosed for the production of hollow articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is coated onto a prewarmed continuous surface in a relatively thin layer so that the slurry is substantially uniformly coated on the surface. The heat of the prewarmed surface conducts to the slurry to initiate a reaction which causes the slurry to set or harden in a shape conforming to the surface. The hardened configurations may then be sintered to consolidate the particles and provide a high density product. 9 figs.
A rule-based expert system approach to process selection for cast components
A knowledge-based expert system at the discretion of casting product designers can be employed as a real-time expert advisor to assist product designers to achieve the correct casting design and select the most appropriate casting process for a given component. This paper proposes a rule-based expert system approach for casting process selection, and describes an ongoing rule prototype development. The
Er Ahmet; R. Dias
The cracking behavior of anodic films on cast aluminum alloy after heating in the temperature range up to 300Ā░C
The cracking behavior of sealed anodic films on cast aluminum alloy after heating in the temperature range up to 300Ā░C was studied and the effects of anodizing temperature, heating temperature and heating rate on cracking behavior were investigated. The results showed that before heating some micro-cracks were present in sealed anodic films on the aluminum alloy tested. After heating between
Weihua Liu; Yu Zuo; Yuming Tang; Xuhui Zhao
Preparation and characterization of solution cast films of PET, reorganized PET and their MWNT nanocomposites
The samples of polyethylene terephthalate (PET), reorganized PET (r-PET) and their nanocomposites with 0.05 wt % and 0.1 wt % multi walled carbon nanotubes (MWNT) were prepared by standard solution casting method using trifluoroacetic acid (TFA) as a solvent. Reorganization of PET was obtained by precipitation method using TFA as a solvent and acetone as an antisolvent. Structural and morphological properties of the films were investigated by Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Differential Scanning Calorimetry (DSC) was used to study the thermal properties of the films. Bulk resistivity of the prepared samples was studied using LCR meter. The results show better dispersion of MWNT in r-PET than in PET. Better dispersion is attributed to the morphological changes in r-PET. The films obtained were conductive and transparent even after addition of MWNT signifying their use as a flexible solar substrate.
Singh, Arvind R.; Deshpande, Vineeta D.
Fatty acid-based polyurethane films for wound dressing applications.
Fatty acid-based polyurethane films were prepared for use as potential wound dressing material. The polymerization reaction was carried out with or without catalyst. Polymer films were prepared by casting-evaporation technique with or without crosslink-catalyst. The film prepared from uncatalyzed reaction product with crosslink-catalyst gave slightly higher crosslink density. The mechanical tests showed that, the increase in the tensile strength and decrease in the elongation at break is due to the increase in the degree of crosslinking. All films were flexible, and resisted to acid solution. The films prepared without crosslink-catalyst were more hydrophilic, absorbed more water. The highest permeability values were generally obtained for the films prepared without crosslink catalyst. Both the direct contact method and the MMT test were applied for determination of cytotoxicity of polymer films and the polyurethane film prepared from uncatalyzed reaction product without crosslink-catalyst showed better biocompatibility property, closest to the commercial product, Opsite. PMID:18839285
Gultekin, Guncem; Atalay-Oral, Cigdem; Erkal, Sibel; Sahin, Fikret; Karastova, Djursun; Tantekin-Ersolmaz, S Birgul; Guner, F Seniha
Cast Fe-base cylinder/regenerator housing alloy
The development of an iron-base alloy that can meet the requirements of automotive Stirling engine cylinders and regenerator housings is described. Alloy requirements are as follows: a cast alloy, stress for 5000-hr rupture life of 200 MPa (29 ksi) at 775 C (1427 F), oxidation/corrosion resistance comparable to that of N-155, compatibility with hydrogen, and an alloy cost less than or equal to that of 19-9DL. The preliminary screening and evaluation of ten alloys are described.
Larson, F.; Kindlimann, L.
Evaporation-induced ordering in solution-cast block copolymer thin films
Block copolymer thin films are currently being investigated for a wide variety of applications, ranging from separation membranes to organic photovoltaics and lithographic masks. Over the last decade or so, there has been mounting interest in using solvent casting techniques to control morphology selection in thin films either through spin coating, drop casting, or simple annealing under a mixture of solvent vapors. While these added degrees of freedom and process variables offer the promise of enhanced morphology control, they necessarily add extra dimensions and inter-dependencies between parameters that must be sorted out before this control can be effectively exercised. To this end, we have adapted a dynamical extension of Self-Consistent Field Theory to study the dynamics of ordering from a dilute copolymer solution to a dry, ordered thin film. This talk will offer a visual summary of the range in behavior available to a single copolymer + neutral solvent system in both 2D (lamella-forming) and 3D (cylinder-forming) environments. In addition, a brief analysis will be presented on the competing time scales, equilibrium, and non-equilibrium effects that appear to govern the initiation event and propagation of evaporation-induced ordering fronts.
Paradiso, Sean; Delaney, Kris; Ceniceros, Hector; Garcia-Cervera, Carlos; Fredrickson, Glenn
Influence of plasticiser on the barrier, mechanical and grease resistance properties of alginate cast films.
Alginate cast films were plasticised by two plasticisers - glycerol and sorbitol - in different concentrations. As a function of the plasticiser type and concentration, the following parameters were investigated: equilibrium moisture content (EMC), colour measurement, microscopic analysis by SEM, grease resistance, oxygen permeability (OP), water vapour transmission rate (WVTR) and the mechanical properties. Both plasticisers have a positive influence on the mechanical properties but differ in their effect on the barrier properties. Whilst an increasing concentration of glycerol increases the permeability of alginate films to oxygen and water vapour, sorbitol did not influence the barrier properties to oxygen or water vapour. The behaviour of glycerol is in accordance with the free volume theory. The effect of sorbitol is assumed to be due to the good steric fit of sorbitol into the alginate network. The good embedding of sorbitol between the alginate polymer chains means it can lower the intermolecular bonding while still offering bonding possibilities. Therefore the flexibility of the cast films is increased while maintaining the barrier properties. PMID:24906761
Jost, Verena; Kobsik, Karin; Schmid, Markus; Noller, Klaus
Sensor-based assessment of cast placement and removal.
Appropriate pressure during the application of a cast is critical to provide adequate stabilization of fractures. Force-sensing resistors (FSR) were used to measure pressure during cast placement and removal. The data demonstrated a signature pattern of skin pressure during the different steps of cast placement and removal. This reproducible signal provides validity evidence for our model. PMID:24732518
Maag, Anne-Lise D; Laufer, Shlomi; Kwan, Calvin; Cohen, Elaine R; Lenhart, Rachel L; Stork, Natalie C; Halanski, Matthew A; Pugh, Carla M
Sensor-Based Assessment of Cast Placement and Removal
PubMed Central
Appropriate pressure during the application of a cast is critical to provide adequate stabilization of fractures. Force-sensing resistors (FSR) were used to measure pressure during cast placement and removal. The data demonstrated a signature pattern of skin pressure during the different steps of cast placement and removal. This reproducible signal provides validity evidence for our model.
MAAG, Anne-Lise D.; LAUFER, Shlomi; KWAN, Calvin; COHEN, Elaine R.; LENHART, Rachel L.; STORK, Natalie C.; HALANSKI, Matthew A.; PUGH, Carla M.
Starch-Based Semipermeable Films.
While cellulose-based films have achieved prominence as semipermeable membranes, starch-based films have not been available that would withstand prolonged exposure to water. Starch and cellulose are high polymers composed of D-glucose units. Starch readil...
F. H. Otey R. P. Westhoff
Comparative characterization of aqueous dispersions and cast films of different chitin nanowhiskers/nanofibers.
Water dispersions of TEMPO-oxidized ?-chitin nanowhisker (TOChN), partially deacetylated ?-chitin nanowhisker/nanofiber mixture (DEChN), HCl-hydrolyzed chitin nanowhisker (HHChN) and squid-pen ?-chitin nanofiber (SQChN) were prepared, and the properties of nano-dispersions and their cast films were characterized between the four chitin nano-samples. Because SQChN has the highest aspect ratio, its 0.1% dispersion had the highest shear stress and viscosity at the same shear rate in the four chitin nano-samples, and showed gel-like behavior in the whole shear rate range from 10(-3) to 10(3) s(-1). AFM images of the self-standing films showed that film surfaces consisted of characteristic chitin nano-elements with different morphologies and degrees of orientation between the four chitin samples, whereas all chitin nanowhisker/nanofiber films had similar thermal degradation points at ~200░C. The DEChN film had the highest tensile strength of ~140 MPa, elongation at break of ~10% and light-transmittance of 87% at 400 nm. In contrast, the SQChN film had the lowest tensile strength, Young's modulus and light-transmittance. All chitin nanowhisker/nanofiber films had similar oxygen permeabilities of ~1 mL ?m m(-2) day(-1) kPa(-1), which was clearly lower than that (184 mL ?m m(-2) day(-1) kPa(-1)) of a poly(lactic acid) film. PMID:22001722
Fan, Yimin; Fukuzumi, Hayaka; Saito, Tsuguyuki; Isogai, Akira
The Simulation of Magnesium Wheel Low Pressure Die Casting Based on PAM-CASTÖ
Magnesium is the lightest metal commonly used in engineering, with various excellent characteristics such as high strength and electromagnetic interference shielding capability. Particularly, the usage of magnesium in automotive industry can meet better the need to reduce fuel consumption and CO2 emissions. Nowadays, most current magnesium components in automobiles are made by die casting. In this paper, commercial software for die casting, PAM-CASTÖ, was utilized to simulate the low pressure die casting process of magnesium wheel. Through calculating temperature field and velocity field during filling and solidification stages, the evolution of temperature distribution and liquid fraction was analyzed. Then, the potential defects including the gas entrapments in the middle of the spokes, shrinkages between the rim and the spokes were forecasted. The analytical results revealed that the mold geometry and die casting parameters should be improved in order to get the sound magnesium wheel. The reasons leading to these defects were also analyzed and the solutions to eliminate them were put forward. Furthermore, through reducing the pouring velocity, the air gas entrapments and partial shrinkages were eliminated effectively.
Peng, Yinghong; Wang, Yingchun; Li, Dayong; Zeng, Xiaoqin
One- and two-photon induced birefringence in Salen dye cast films
In this paper, we present the one- and two-photon optically induced birefringence in cast films of amorphous poly(methyl methacrylate) (PMMA), containing a new series of organometallic azoaromatic compounds, referred to as Salen dyes, which may be used in optical storage applications. For the one-photon optically induced birefringence, longer writing times were required for the organometallic compounds in comparison with the nonmetal one, probably due to the higher degree of aggregation in the azoaromatic moieties that precludes molecular orientation. Furthermore, as a novelty concerning optical storage, two-photon optically induced birefringence could be achieved in the Salen dyes guest-host films, which allows their application in three-dimensional optical memories.
Cardoso, M. R.; Neves, U. M.; Misoguti, L.; Ye, Zhihong; Bu, Xiu R.; Mendonńa, C. R.
MultiPeerCast: A Tree-Mesh-Hybrid P2P Live Streaming Scheme Design and Implementation Based on PeerCast
In this paper, we firstly analyze the mechanism of PeerCast as a P2P live streaming solution. An then, based on the shortcoming analysis of tree-based PeerCast, we propose a improved tree-mesh-hybrid scheme-MultiPeerCast, including Multi-thread media transmission, multiple-to-one overlay network reconstruct, optimized buffer design, media retrieving style changing from push mode to pull mode. As part of experiment work, we discuss
Lv Zhihui; You Li; Jie Wu; Shiyong Zhang; Yiping Zhong
Microstructural evolution in a strip-cast Ni-base superalloy
Microstructure and mechanical properties of the strip-cast Ni-base superalloy(Hastelloy-X) alloy have been compared with those\\u000a of a conventionally ingot-cast alloy. As-cast strip shows a fine columnar dendritic structure as a result of a relatively\\u000a high cooling rate of 102 -104 K\\/sec during the process. The alloying elements, such as Cr and Fe, are homogeneously distributed in the ? matrix of
D. K. Kim; D. H. Kim; D. K. Choo; H. K. Moon
A method for surface quality assessment of die-castings based on laser triangulation
This paper presents a new method for the surface quality assessment of safety-critical die-castings. We have developed a measurement system that measures the surface of a die-casting and provides quantitative surface quality assessment within a die-casting cycle of 70 s. The measurement system, based on the laser triangulation principle, has an asymmetrical measuring range and is capable of high-resolution measurements
Drago Bracun; Valter Gruden; Janez Mozina
Enhancement of Third-Order Optical Susceptibility in Polythiophene Thin Films Fabricated by Drop Casting Using Anhydrous Solvent
To maximize the potential of poly(3-hexylthiophene) (P3HT) as a nonlinear optical material, we examined the conditions for fabricating thin films. The results indicate that the third-order optical susceptibility chi(3), which was determined by electroabsorption spectroscopy, is fourfold enhanced when thin films are drop cast from an anhydrous chloroform solution in an inert atmosphere, compared with the chi(3) of spin-coated thin
Takashi Kobayashi; Toshiyuki Endo; Wataru Shinke; Takashi Nagase; Shuichi Murakami; Hiroyoshi Naito
Modelling of liquid metal flow and oxide film defects in filling of aluminium alloy castings
The liquid metal flow behaviours in different runner system designs have important effects on the mechanical strength of aluminium alloy castings. In this paper, a new model has been developed which is a two-dimensional program using a finite difference technique and the Marker and Cell (MAC) method to simulate the flow of liquid metal during filling a mould. In the program the Eulerian method has been used for the liquid metal flow, while the Oxide Film Entrainment Tracking Algorithm (OFET) method (a Lagrangian method) has been used to simulate the movement of the oxide film on the liquid metal surface or in the liquid metal flow. Several examples have been simulated and tested and the relevant results were obtained. These results were compared with measured bending strengths. It was found that the completed program was capable of simulating effectively the filling processes of different runner systems. The simulation results are consistent with the experiment. In addition, the program is capable of providing clearer images for predicting the distribution of the oxide film defects generated during filling a mould.
Dai, X.; Jolly, M.; Yang, X.; Campbell, J.
Coccidioidomycosis among cast and crew members at an outdoor television filming event - california, 2012.
In March 2013, the California Department of Public Health (CDPH) identified two Doctor's First Reports of Occupational Injury or Illness (DFRs) regarding Los Angeles County residents who had worked at the same jobsite in January 2012 and had been evaluated for possible work-associated coccidioidomycosis (valley fever). Occupational exposure to Coccidioides, the causative fungi, typically is associated with soil-disrupting activities. The physicians noted that both workers were cast or crew members filming a television series episode, and the site of possible exposure was an outdoor set in Ventura County, California. On the basis of their job titles, neither would have been expected to have been engaged in soil-disrupting activities. Los Angeles County Department of Public Health (LACDPH) conducted an outbreak investigation by using CDPH-provided occupational surveillance records, traditional infectious disease surveillance, and social media searches. This report describes the results of that investigation, which identified a total of five laboratory-confirmed and five probable cases linked to this filming event. The employer and site manager were interviewed. The site manager stated that they would no longer allow soil-disruptive work at the site and would incorporate information about the potential risk for Coccidioides exposure onsite into work contracts. Public health professionals, clinicians, and the television and film industry should be aware that employees working outdoors in areas where Coccidioides is endemic (e.g., central and southern California), even those not engaged in soil-disruptive work, might be at risk for coccidioidomycosis. PMID:24739339
Wilken, Jason A; Marquez, Patricia; Terashita, Dawn; McNary, Jennifer; Windham, Gayle; Materna, Barbara
The Influence of Cast Structure on Thermal Fatigue of Some Nickel-Base Superalloys.
A fluidized-bed thermal fatigue test used to determine the influence of foundry variables on cast structure and thermal fatigue resistance of four nickel-base superalloys (M 21, 713 LC, IN 738 LC and IN 939) indicates that specimens cast under conditions ...
J. C. Ashworth K. J. Williams
Improved mechanical properties of solution-cast silicone film reinforced with electrospun polyurethane nanofiber containing carbon nanotubes
In this study, we describe the enhancing ability of electrospun polyurethane (PU) nanofibers containing carbon nanotubes (CNTs) as nanofillers for silicone film in improving the physico-mechanical properties of the composite material. We prepared the samples combining two simple techniques: solution casting and electrospinning. Neat PU nanofibers alone are good reinforcing materials but the presence of CNTs inside the PU nanofibers has drastically improved the mechanical properties of the silicone composite film. The silicone film increased its tensile strength by 226% and its tensile modulus by more than 14-fold when CNT/PU nanofibers were incorporated.
Tijing, Leonard D.; Park, Chan-Hee; Kang, Seung-Ji; Amarjargal, Altangerel; Kim, Tae-Hyung; Pant, Hem Raj; Kim, Han Joo; Lee, Dong Hwan; Kim, Cheol Sang
High solids loading for water-based tape casting
Tape Casting is a low cost process for making large-area, thin, flat ceramics, which traditionally utilizes organic solvents to allow fast drying.sp{1-4} However, some of the volatile organic compounds (VOC), such as toluene, methylethyl ketone (MEK), and cyclohexanone, are hazardous air pollutants, and their emissions need to be regulated. Therefore, using water as a solvent is desirable to avoid the need of trapping VOCs. Although water is of low cost, nonflammable and safe to the environment, its heat of vaporization is high, 540 kca/g, compared to that of toluene, 74 kca/g.sp7 This makes the drying slow when water is used. The use of water in a tape casting formulation has previously been practical just for applications which require very thin tape, 100-200 mum. A high solids loading of above 50 vol% is an alternative approach to obtain sufficiently rapid drying for a thicker tape (up to 0.8 mm) since the water content is originally minimized. In order to obtain a high solids loading, the dispersants and binder systems were carefully tailored during the present research project. Low molecular weight polyelectrolytes, such as polyacrylic acid PAA (M.W. 1800) and citric acid, were found to be effective for high solids loading of Alsb2Osb3 (A-16SG), for which the electrosteric stabilization played an important role to the stability of the suspension. The viscosity and flow behavior of the suspension strongly depended on pH and the amount of polyelectrolyte, which could be related to the configuration of the polyelectrolyte molecules on the powder surface. The high solids loading of 64.5 vol% could be obtained for the fine A-16SG powder which had a surface area of 9.3 msp2/g. For the coarser powder, A-152SG, the dilatancy was a major problem that obstructed a further rise in solids loading. The dilatancy could be minimized by modifying the size distribution with A-152SG plus A-16SG and using a proper pH and amount of dispersants. An extremely high solids loading of 71-73 vol% could be reached in an aqueous system for the size-modified powder, before binder addition. An emulsion binder (Duramaxsp{TM} B-1001) aided the reduction in viscosity of the high solids loading suspension, while the soluble binder aggravated the agglomeration and drastically raised the viscosity. The emulsion binder used also had high polymer content and, therefore, less water. The final solids loadings obtained were 55.7 vol% for A-16SG and 63 vol% for mixed A-152SG and A-16SG powder. The drying time was reduced by one third for the 63 vol% formulation compared to the 55.7 vol% formulation. Water-based tape casting of A1N was possible in a buffer solution. Polyacrylic acid, PAA (M.W. 1800), aided dispersion and also minimized hydrolysis of A1N in water. Poly(vinyl pyrrolidone), PVP (M.W. 160,000), gave a lower viscosity to suspension compared to poly(vinyl alcohol) and cellulose ether, and had less bubble formation. The suspension could be processed for more than 72 h without degradation. With optimization of dispersant and binder, a high solids loading formulation of 52 vol% could be obtained. When the organic components were burned out in the air, AlN with 3wt% Ysb2Osb3 could be sintered at 1800sp░C for 1 h without degradation. The thermal conductivity was up to 153 W/m.K.
Suwannasiri, Thitima
Real-time measurement system for tracking birefringence, weight, thickness, and surface temperature during drying of solution cast coatings and films.
This paper describes the design and performance of a new instrument to track temporal changes in physical parameters during the drying behavior of solutions, as well as curing of monomers. This real-time instrument follows in-plane and out-of-plane birefringence, weight, thickness, and surface temperature during the course of solidification of coatings and films through solvent evaporation and thermal or photocuring in a controlled atmosphere. It is specifically designed to simulate behavior of polymer solutions inside an industrial size, continuous roll-to-roll solution casting line and other coating operations where resins are subjected to ultraviolet (UV) curing from monomer precursors. Controlled processing parameters include air speed, temperature, initial cast thickness, and solute concentration, while measured parameters are thickness, weight, film temperature, in-plane and out-of-plane birefringence. In this paper, we illustrate the utility of this instrument with solution cast and dried poly (amide-imide)?DMAc (Dimethylacetamide) solution, water based black paint, and organo-modified clay?NMP (N-Methylpyrrolidone) solution. In addition, the physical changes that take place during UV photo polymerization of a monomer are tracked. This instrument is designed to be generic and it can be used for tracking any drying?swelling?solidification systems including paper, foodstuffs such as; grains, milk as well as pharmaceutical thin paste and slurries. PMID:22380132
Unsal, E; Drum, J; Yucel, O; Nugay, I I; Yalcin, B; Cakmak, M
Real-time measurement system for tracking birefringence, weight, thickness, and surface temperature during drying of solution cast coatings and films
This paper describes the design and performance of a new instrument to track temporal changes in physical parameters during the drying behavior of solutions, as well as curing of monomers. This real-time instrument follows in-plane and out-of-plane birefringence, weight, thickness, and surface temperature during the course of solidification of coatings and films through solvent evaporation and thermal or photocuring in a controlled atmosphere. It is specifically designed to simulate behavior of polymer solutions inside an industrial size, continuous roll-to-roll solution casting line and other coating operations where resins are subjected to ultraviolet (UV) curing from monomer precursors. Controlled processing parameters include air speed, temperature, initial cast thickness, and solute concentration, while measured parameters are thickness, weight, film temperature, in-plane and out-of-plane birefringence. In this paper, we illustrate the utility of this instrument with solution cast and dried poly (amide-imide)/DMAc (Dimethylacetamide) solution, water based black paint, and organo-modified clay/NMP (N-Methylpyrrolidone) solution. In addition, the physical changes that take place during UV photo polymerization of a monomer are tracked. This instrument is designed to be generic and it can be used for tracking any drying/swelling/solidification systems including paper, foodstuffs such as; grains, milk as well as pharmaceutical thin paste and slurries.
Unsal, E.; Drum, J.; Yucel, O.; Nugay, I. I.; Yalcin, B.; Cakmak, M.
Effectiveness of silane monomer and gamma radiation on chitosan films and PCL-based composites
Chitosan films were prepared by casting from its 1% (w/w) solution. Tensile strength (TS) and tensile modulus (TM) of chitosan films were found to be 30 MPa and 450 MPa, respectively. Silane monomer (3-aminopropyl tri-methoxysilane) (0.25%, w/w) was added into the chitosan solution (1%, w/w) and films were casted. Then films were exposed to gamma radiation (5-25 kGy) and mechanical properties were investigated. It was found that at 10 kGy, the values of TS and TM were improved significantly. Silane grafted chitosan film reinforced poly(caprolactone) (PCL)-based tri-layer composites were prepared by compression molding. Silane improved interfacial adhesion between chitosan and PCL in composites. Surface of the films was investigated by scanning electron microscope (SEM) and found better morphology for silane grafted films.
Sharmin, Nusrat; Khan, Ruhul A.; Dussault, Dominic; Salmieri, Stephane; Akter, Nousin; Lacroix, Monique
Mechanism-based thermomechanical fatigue life prediction of cast iron. Part II: Comparison of model predictions with experiments
In the present paper, predictions of mechanism-based models for cast iron are compared to experimental results obtained for the nodular cast iron EN-GJS-700, the vermicular cast iron EN-GJV-450 and the lamellar cast iron EN-GJL-250. A strategy is proposed to efficiently identify the model parameters based on isothermal experiments. In particular, complex low cycle fatigue (LCF) tests, tension tests and compression
T. Seifert; G. Maier; A. Uihlein; K.-H. Lang; H. Riedel
Influence of S. mutans on base-metal dental casting alloy toxicity.
We have highlighted that exposure of base-metal dental casting alloys to the acidogenic bacterium Streptococcus mutans significantly increases cellular toxicity following exposure to immortalized human TR146 oral keratinocytes. With Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), S. mutans-treated nickel-based (Ni-based) and cobalt-chromium-based (Co-Cr-based) dental casting alloys were shown to leach elevated levels of metal ions compared with untreated dental casting alloys. We targeted several biological parameters: cell morphology, viable cell counts, cell metabolic activity, cell toxicity, and inflammatory cytokine expression. S. mutans-treated dental casting alloys disrupted cell morphology, elicited significantly decreased viable cell counts (p < 0.0001) and cell metabolic activity (p < 0.0001), and significantly increased cell toxicity (p < 0.0001) and inflammatory cytokine expression (p < 0.0001). S. mutans-treated Ni-based dental casting alloys induced elevated levels of cellular toxicity compared with S. mutans-treated Co-Cr-based dental casting alloys. While our findings indicated that the exacerbated release of metal ions from S. mutans-treated base-metal dental casting alloys was the likely result of the pH reduction during S. mutans growth, the exact nature of mechanisms leading to accelerated dissolution of alloy-discs is not yet fully understood. Given the predominance of S. mutans oral carriage and the exacerbated cytotoxicity observed in TR146 cells following exposure to S. mutans-treated base-metal dental casting alloys, the implications for the long-term stability of base-metal dental restorations in the oral cavity are a cause for concern. PMID:23103633
McGinley, E L; Dowling, A H; Moran, G P; Fleming, G J P
Advanced Turbine Engine Gas Generator (ATEGG) Fractography of Cast Nickel Base Superalloys.
This report documents Teledyne CAE's efforts to correlate the fracture surfaces of cast nickel-base superalloys to known conditions of low cycle fatigue testing (strain range partitioning). Rene' 80 and In-100 low cycle fatigue test specimens (supplied by...
D. F. Gray
Three-dimensional microstructure simulation of Ni-based superalloy investment castings
An integrated macro and micro multi-scale model for the three-dimensional microstructure simulation of Ni-based superalloy investment castings was developed, and applied to industrial castings to investigate grain evolution during solidification. A ray tracing method was used to deal with the complex heat radiation transfer. The microstructure evolution was simulated based on the Modified Cellular Automaton method, which was coupled with three-dimensional nested macro and micro grids. Experiments for Ni-based superalloy turbine wheel investment casting were carried out, which showed a good correspondence with the simulated results. It is indicated that the proposed model is able to predict the microstructure of the casting precisely, which provides a tool for the optimizing process.
Pan, Dong; Xu, Qingyan; Liu, Baicheng
Pectin- and gelatin-based film: effect of gamma irradiation on the mechanical properties and biodegradation
Agricultural by-products, pectin and gelatin, were used to prepare a biodegradable film. The film casting solution including the pectin and gelatin was irradiated at 0, 10, 20, and 30 kGy to investigate the irradiation effect on the mechanical properties of the film. The tensile strength of the 10 kGy-irradiated film was the highest among the treatments but the elongation at break, water vapour permeability, and swelling ratio were the lowest. Hunter color L*- and a*-values decreased but the b*-value increased as the irradiation dose increased. The total organic carbon content produced from the Paenibacillus polymyxa and Pseudomonas aeruginosa also showed that the film of 10 kGy-irradiated was lower than those of 0, 20, and 30 kGy-irradiated films. In conclusion, irradiation of the film casting solution at 10 kGy increased the mechanical properties of the pectin and gelatin based film. To manufacture the film by agricultural by-products, however, the irradiation dose of the film casting solution should be determined to achieve better mechanical properties.
Jo, Cheorun; Kang, Hojin; Lee, Na Young; Kwon, Joong Ho; Byun, Myung Woo
Percolation enhancement of conductivity in polyaniline films cast from volatile solvents
There are numerous applications that could benefit from the use of conducting polymers. While great progress has been made in broadening the choice of materials and improving their transport properties, one is still rather limited in choices by the needs for both procesability and environmental stability. These requirements tend to narrow the choice of materials to various forms of polyaniline (PANI). Polyaniline can be solution processed retaining its conductivity after exposure to ambient conditions for exended periods. Although films cast from a CSA-PANI in m-cresol solution exhibit conductivities ranging from 100-200 S/cm, this solvent is unacceptable not only due to the high temperatures required for its removal but overall safety concerns due to operator exposure. We report on work to aliviate some of these issues by loading the PANI with highly conducting dispersable solids. The overall matrix can exhibit large enhancements of the conductivity with appropriate choice of the loading material and control of the dispersion properties. This allows one to obtain a highly conducting environmentally stable percolated matrix formed from appropriate solvents satisfying the needs of many applications.
Blanchet, Graciela; Fincher, Curtis; Gao, Feng; Hsu, Che
Structural, absorption and optical dispersion characteristics of rhodamine B thin films prepared by drop casting technique
The drop casting technique has been successfully used to deposit highly uniform and good adhesion rhodamine B (Rh.B) thin films. The structural and morphological properties of Rh.B were studied by X-ray diffraction (XRD), and transmission electron microscopy (TEM), respectively. The molecular structure and electronic transitions of Rh.B were investigated by Fourier-transform infrared (FTIR) and ultraviolet-visible-near infrared (UV-VIS-NIR) spectra, respectively. The calculated Stokes shift between the excitation and emission of Rh.B reflects the displacement in potential surface between the ground and the excited states. The important absorption parameters such as molar extinction coefficient ( ?molar), the oscillator strength ( f), and the electric dipole strength ( q2) were also reported. The analysis of the spectral behavior of the absorption coefficient in the intrinsic absorption region reveals an indirect allowed transition with a band gap of 1.97 eV and associated phonons of 75 meV. The dispersion of the refractive index is discussed in terms of the single oscillator Wemple-Didomenico (WD) model. The single oscillator energy ( Eo), the dispersion energy ( Ed), the high frequency dielectric constant ( ??), the lattice dielectric constant ( ?L) and the ratio of the free charge carrier concentration to the effective mass ( N / m*) were estimated. From the optical constants analysis, the optical conductivity, volume and surface energy loss functions could also be calculated.
Farag, A. A. M.; Yahia, I. S.
Electrical transport and grain growth in solution-cast, chloride-terminated cadmium selenide nanocrystal thin films.
We report the evolution of electrical transport and grain size during the sintering of thin films spin-cast from soluble phosphine and amine-bound, chloride-terminated cadmium selenide nanocrystals. Sintering of the nanocrystals occurs in three distinct stages as the annealing temperature is increased: (1) reversible desorption of the organic ligands (?150 ░C), (2) irreversible particle fusion (200-300 ░C), and (3) ripening of the grains to >5 nm domains (>200 ░C). Grain growth occurs at 200 ░C in films with 8 atom % Cl(-), while films with 3 atom % Cl(-) resist growth until 300 ░C. Fused nanocrystalline thin films (grain size = 4.5-5.5 nm) on thermally grown silicon dioxide gate dielectrics produce field-effect transistors with electron mobilities as high as 25 cm(2)/(Vs) and on/off ratios of 10(5) with less than 0.5 V hysteresis in threshold voltage without the addition of indium. PMID:24960255
Norman, Zachariah M; Anderson, Nicholas C; Owen, Jonathan S
To maximize the potential of poly(3-hexylthiophene) (P3HT) as a nonlinear optical material, we examined the conditions for fabricating thin films. The results indicate that the third-order optical susceptibility ?(3), which was determined by electroabsorption spectroscopy, is fourfold enhanced when thin films are drop cast from an anhydrous chloroform solution in an inert atmosphere, compared with the ?(3) of spin-coated thin films prepared in an ambient atmosphere. Fabricating the thin films in an O2- and water-free environment is essential for obtaining large ?(3) values. Under these conditions, we determined the maximum value of the imaginary part of ?(3) for P3HT to be 2.2 ū 10-9 esu.
Kobayashi, Takashi; Endo, Toshiyuki; Shinke, Wataru; Nagase, Takashi; Murakami, Shuichi; Naito, Hiroyoshi
Caste-, work-, and descent-based discrimination as a determinant of health in social epidemiology.
Social epidemiology explores health in the context of broad social determinants of health, where the boundary lines between health and politics appear increasingly blurred. Social determinants of health such as caste, discrimination, and social exclusion are inherently political in nature, hence it becomes imperative to look at health through a broader perspective of political philosophy, ideology, and caste that imposes enormous obstacles to a person's full attainment of civil, political, economic, social, and cultural rights. Caste is descent based and hereditary in nature. It is a characteristic determined by one's birth into a particular caste, irrespective of the faith practiced by the individual. Caste denotes a system of rigid social stratification into ranked groups defined by descent and occupation. Under various caste systems throughout the world, caste divisions also dominate in housing, marriage, and general social interaction divisions that are reinforced through the practice and threat of social ostracism, economic boycotts, and even physical violence-all of which undermine health equality. PMID:24871772
Patil, Rajan R
Rule-based quotation costing of pressure die casting moulds
An actual analysis in the tool and mould making sector showed that methods and programs insufficiently support the manufacturers\\u000a of pressure die casting moulds in the quotation costing process. The primary aim of quotation costing is to generate many\\u000a first-class bids in order to gain a high quantity of profitable orders. For this purpose companies have to achieve a high
B. Denkena; L.-E. Lorenzen; J. Sch³rmeyer
Heat flux transients at the casting\\/chill interface during solidification of aluminum base alloys
Heat flow at the metal\\/chill interface of bar-type castings of aluminum base alloys was modeled as a function of thermophysical\\u000a properties of the chill material and its thickness. Experimental setup for casting square bars of Al-13.2 pct Si eutectic\\u000a and Al-3 pet Cu-4.5 pct Si long freezing range alloys with chill at one end exposed to ambient conditions was fabricated.
T. S. Prasanna Kumar; K. Narayan Prabhu
Conical surface structures on model thin-film electrodes and tape-cast electrode materials for lithium-ion batteries
Three-dimensional structures in cathode materials for lithium-ion batteries were investigated in this study. For this purpose, laser structuring of lithium cobalt oxide was investigated at first for a thin-film model system and in a second step for conventional tape-cast electrode materials. The model thin-film cathodes with a thickness of 3 ?m were deposited using RF magnetron sputtering on stainless steel substrates. The films were structured via excimer laser radiation with a wavelength of 248 nm. By adjusting the laser fluence, self-organized conical microstructures were formed. Using conventional electrodes, tape-cast cathodes made of LiCoO2 with a film thickness of about 80 ?m on aluminum substrates were studied. It was shown that self-organizing surface structures could be formed by adjustment of the laser parameters. To investigate the formation mechanisms of the conical topography, the element composition was studied by time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy. Electrochemical cycling using a lithium anode and conventional electrolyte was applied to study the influence of the laser processing procedures on cell performance. For the model electrode system, a significantly higher discharge capacity of 80 mAh/g could be obtained after 110 cycles by laser structuring compared to 8 mAh/g of the unstructured thin film. On conventional tape-cast electrodes self-organized surface structures could also increase the cycling stability resulting in an 80 % increase in capacity after 110 cycles in comparison to the unstructured electrode.
Kohler, R.; Proell, J.; Bruns, M.; Ulrich, S.; Seifert, H. J.; Pfleging, W.
Physicochemical properties of the amorphous drug, cast films, and spray dried powders to predict formulation probability of success for solid dispersions: etravirine.
Solid dispersion technology represents an enabling approach to formulate poorly water-soluble drugs. While providing for a potentially increased oral bioavailability secondary to an increased drug dissolution rate, amorphous dispersions can be limited by their physical stability. The ability to assess formulation risk in this regard early in development programs can not only help in guiding development strategies but can also point to critical design elements in the configuration of the dosage form. Based on experience with a recently approved solid dispersion-based product, Intelence« (etravirine), a three part strategy is suggested to predict early formulate-ability of these systems. The components include an assessment of the amorphous form, a study of binary drug/carrier cast films and the evaluation of a powder of the drug and polymer processed in a manner relevant to the intended final dosage form. A variety of thermoanalytical, spectroscopic, and spectrophotometric approaches were applied to study the prepared materials. The data suggest a correlation between the glass forming ability and stability of the amorphous drug and the nature of the final formulation. Cast films can provide early information on miscibility and stabilization and assessment of processed powders can help define requirements and identify issues with potential final formulations. PMID:20575005
Weuts, Ilse; Van Dycke, Frederic; Voorspoels, Jody; De Cort, Steve; Stokbroekx, Sigrid; Leemans, Ruud; Brewster, Marcus E; Xu, Dawei; Segmuller, Brigitte; Turner, Ya Tsz A; Roberts, Clive J; Davies, Martyn C; Qi, Sheng; Craig, Duncan Q M; Reading, Mike
Evaporation-induced formation of self-organized gradient concentric rings on sub-micron pre-cast PMMA films.
A "particle-on-film" template is developed to fabricate self-organized surface patterns through solvent evaporation on initially featureless, sub-micron PMMA films. The small particle placed on the pre-cast PMMA film is able to confine a toluene droplet and influence the evaporative process. Well-ordered gradient concentric rings are formed around the particle due to the unconventional "advancing-receding" motion of the contact line in the "stick" state on the surface of the PMMA films. Both the center-to-center distance between adjacent rings (wavelength) and the height of the rings (amplitude) are strongly dependent on the particle size and the film thickness, and decrease with the decrease of the distance to the center of the particle. A linear dependence of the amplitude of the rings on the wavelength is observed under experimental conditions. The results demonstrate that the "particle-on-film" template has the potential to fabricate highly-ordered surface patterns economically and efficiently. PMID:24803223
Sun, Wei; Yang, Fuqian
Antimicrobial and physical-mechanical properties of agar-based films incorporated with grapefruit seed extract.
The use of synthetic petroleum based packaging films caused serious environmental problems due to their difficulty in recycling and poor biodegradability. Therefore, present study was aimed to develop natural biopolymer-based antimicrobial packaging films as an alternative for the synthetic packaging films. As a natural antimicrobial agent, grapefruit seed extract (GSE) has been incorporated into agar to prepare antimicrobial packaging film. The films with different concentrations of GSE were prepared by a solvent casting method and the resulting composite films were examined physically and mechanically. In addition, the films were characterized by FE-SEM, XRD, FT-IR and TGA. The incorporation of GSE caused increase in color, UV barrier, moisture content, water solubility and water vapor permeability, while decrease in surface hydrophobicity, tensile strength and elastic modulus of the films. As the concentration of GSE increased from 0.6 to 13.3 ?g/mL, the physical and mechanical properties of the films were affected significantly. The addition of GSE changed film microstructure of the film, but did not influence the crystallinity of agar and thermal stability of the agar-based films. The agar/GSE films exhibited distinctive antimicrobial activity against three test food pathogens, such as Listeria monocytogenes, Bacillus cereus and Escherichia coli. These results suggest that agar/GSE films have potential to be used in an active food packaging systems for maintaining food safety and extending the shelf-life of the packaged food. PMID:24507339
Kanmani, Paulraj; Rhim, Jong-Whan
Spectral response of solvent-cast polyvinyl chloride (PVC) thin film used as a long-term UV dosimeter.
The spectral response of solvent-cast polyvinyl chloride (PVC) thin film suitable for use as a long-term UV dosimeter has been determined by measuring the UV induced change in the 1064 cm(-1) peak intensity of the PVC's infrared (IR) spectra as a function of the wavelength of the incident radiation. Measurements using cut-off filters, narrow band-pass filters and monochromatic radiation showed that the 16 ?m PVC film responds mainly to the UVB band. The maximum response was at 290 nm and decreasing exponentially with wavelength up to about 340 nm independent of temperature and exposure dose. The most suitable concentration (W/V%) of PVC/Tetrahydrofuran solution was found to be 10% and the best thickness for the dosimeter was determined as 16 ?m. PMID:23811159
Amar, Abdurazaq; Parisi, Alfio V
Casting Technology.
ERIC Educational Resources Information Center
Three articles discuss (1) casting technology as it relates to industry, with comparisons of shell casting, shell molding, and die casting; (2) evaporative pattern casting for metals; and (3) high technological casting with silicone rubber. (JOW)
Wright, Michael D.; And Others
Efficacy of powder-based three-dimensional printing (3DP) technologies for rapid casting of light alloys
The aim of the present research was to compare the efficacy of two powder based 3D printing technologies for rapid casting\\u000a of light alloys. The technologies of ZCast process and investment casting were employed to cast aluminium A356 alloy and zinc\\u000a ZA-12 alloy. The split pattern shells were printed in ZCast501 powder and used directly as mould with outside sand
Simranpreet Singh Gill; Munish Kaplas
Facile preparation and thermoelectric properties of Bi?Te? based alloy nanosheet/PEDOT:PSS composite films.
Bi2Te3 based alloy nanosheet (NS)/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) composite films were prepared separately by spin coating and drop casting techniques. The drop cast composite film containing 4.10 wt % Bi2Te3 based alloy NSs showed electrical conductivity as high as 1295.21 S/cm, which is higher than that (753.8 S/cm) of a dimethyl sulfoxide doped PEDOT:PSS film prepared under the same condition and that (850-1250 S/cm) of the Bi2Te3 based alloy bulk material. The composite film also showed a very high power factor value, ?32.26 ?Wm(-1) K(-2). With the content of Bi2Te3 based alloy NSs increasing from 0 to 4.10 wt %, the electrical conductivity and Seebeck coefficient of the composite films increase simultaneously. PMID:24666341
Du, Yong; Cai, K F; Chen, Song; Cizek, Pavel; Lin, Tong
Structure of continuously cast Ni-based superalloy Inconel 713C
In this work, we characterised the structure of continuously cast Ni-based superalloy IN 713C (? 10 mm, water cooled Cu¢Be mould, argon atmosphere) using several microstructural characterization techniques (LM, SEM, TEM, EDS, XRD). The structure consisted of columnar dendritic ?-grains with apparently fully coherent and rather uniformly distributed ?? precipitates (size ?50 nm), primary MC carbide and MC\\/? eutectic. The
F Zupani?; T Bon?ina; A Kri×man; F. D Tichelaar
Microstructural constituents of the Ni-based superalloy GMR 235 in the as-cast condition
The Ni-based superalloy GMR 235 was investigated in different as-cast conditions. It consisted of the ? matrix with ?? precipitates, and of three minor constituents: M3B2, MC and Ti(C,N). The cooling rate influenced the size and morphology of microstructural constituents, and the composition and lattice constants of M3B2 and MC.
F. Zupani?; T. Bon?ina; A. Kri×man; B. Markoli; S. Spai?
Utility and Stability Measures for Agent-Based Dynamic Scheduling of Steel Continuous Casting
This paper describes a new model for robust predictive\\/reactive scheduling of steel continuous casting based on the use of multi-agents, tabu search and heuristic approaches. A continuous caster agent generates a predictive production schedule taking into account manufacturing requirements and local constraints using tabu search. The predictive schedule is modified so as to minimise deviation between the performance measure values
D. Quelhadj; Peter I. Cowling; Sanja Petrovic
Morphological, Mechanical and Thermal Study of ZnO Nanoparticle Reinforced Chitosan Based Transparent Biocomposite Films
Chitosan based biocomposite transparent films reinforced with zinc oxide (ZnO) nanoparticles at different loading i.e. 2, 4 and 6 wt% were successfully prepared by solution casting method. Shape, size and geometry of the zinc oxide nanoparticles were characterized by scanning electron microscopy (SEM). The biocomposite films were subjected to mechanical characterization, thermal analysis, morphology study and moisture uptake behaviour. The characterization tools used here include wide angle X-ray diffraction study, scanning electron microscopic analysis, differential scanning calorimetric analysis and also UV-visible transmittance behavior. SEM micrographs revealed uniformly dispersed ZnO nanoparticles in biocomposite films. Improvement of the tensile strength about 133 % was observed significantly in case of 4 wt% loaded chitosan/ZnO films with respect to the neat chitosan film. 43 % higher transparency was observed in case of 2 wt% ZnO loaded biocomposites films, thus indicating the best combination of properties of 2 wt% ZnO loaded biocomposite films.
Das, Kunal; Maiti, Sonakshi; Liu, Dagang
Reversible Photoinduced Switching of Permeability in a Cast Non-Porous Film Comprising Azobenzene Liquid Crystalline Polymer.
Permeation characteristics of an azobenzene-containing liquid crystalline (LC) non-porous film are investigated using a metallic corrosion method. Thin films (300?nm) are fabricated by the solution casting of an azobenzene side-chain LC polymer on freshly polished carbon steel coupons. Coated coupons are treated under the following conditions: a) gradual annealing at a cooling rate lower than 1?░C?Ę?min(-1) from 150?░C (above its T(g) ) to room temperature, and b) irradiation at 465?nm (20 mW?Ę?cm(-2) ) with either circularly polarized light (CPL) or non-polarized light (NPL). The morphology of these films is characterized using X-ray diffraction, polarized optical microscopy, and transmission measurements. The results suggest that the annealing treatment resulted in the formation of a polydomain structure consisting of locally ordered small smectic domains that lack mutual orientation. Ordered micro domains are surrounded by disordered phases. CPL and NPL irradiation generates a monodomain orientated structure and an isotropic liquid crystal glass, respectively. The permeability of these non-porous films treated by CPL, NPL, and annealing are found to be 6.14?ū?10(-4) , 1.92?ū?10(-2) , and 1.56?ū?10(-3) cm(3) ?Ę?m(-2) ?Ę?d(-1) . An orientation-dependent structure model is constructed to explain the permeation phenomenon, considering the ordered phase is impermeable, only the disordered phase is accessible to penetrating molecules. Fast switching of gas permeation is demonstrated by alternative irradiation of the film with CPL and NPL, which results in an approximately 30-fold difference in the permeability of the non-porous film. PMID:21786360
Liu, Jian; Wang, Mingle; Dong, Mingling; Gao, Liude; Tian, Jingjing
Mathematical modeling and optimization strategies (genetic algorithm and knowledge base) applied to the continuous casting of steel
The control of quality in continuous casting products cannot be achieved without a knowledge base which incorporates parameters and variables of influence such as: equipment characteristics, steel, each component of the system and operational conditions. This work presents the development of a computational algorithm (software) applied to maximize the quality of steel billets produced by continuous casting. A mathematical model
C. A. Santos; J. A. Spim; A. Garcia
Capsules with prolonged action. III. Release of active ingredients from cast films
In the preceding paper we described a gelation process and the development of sustained-release soft gelatin capsules containing codeine or theophylline. Applying this process to indomethacin and nifedipine as active ingredients led to insufficient release rates of the products. To investigate this phenomenon two simple membrane models were used, i.e., a cast drug-free membrane composed of different ratios of polyethylene
Peter C. Schmidt; B. Stockebrand
Micro construction of poly(epsilon-caprolactone)/poly(L-lactic acid) blend film by solution casting under microwave irradiation.
The micro construction of poly(epsilon-caprolactone) (PCL) and poly(L-lactic acid) (PLLA) blend films fabricated by solution casting under microwave irradiation was investigated by selective enzymatic degradation and scanning electron microscopy (SEM). The results were totally different from the blends obtained by conventional methods. The blend was more homogeneous and the PCL continuous phase more compact as no spherulites and tiny zone separation were observed from the film surface and no PCL network was observed inside the film, and the degradation of a PCL plank by Pseudomonas lipase was significantly retarded. The distributed PLLA micro spheres were enlarged and amorphous. The thermal behavior of the blend by microwave heating revealed that PCL and PLLA underwent a melting process, which induced the variations of the PCL phase and PLLA spheres. The weight loss caused by degradation of the PCL/PLLA blend obtained by conventional methods (B50c) is greater than that of the blend obtained by microwave methods (B50m), which reflects the change in morphology from a loose PCL network (B50c) to a dense PCL plank (B50m). PMID:15468259
Jin, Wei; Liu, Lijian
Development of high strength nickel-base cast superalloy with superior creep rupture life
Elevating the operating temperature is considered to be the most effective for increasing the thermal efficiency of power generators or chemical plants. For this reason, the development of materials exhibiting superior creep strength and corrosion resistance is required. Directionally solidification (DS) and single crystal (SC) superalloys have been developed for advanced commercial and military applications. Owing to the difficulties to produce DS and SC alloys and the high casting cost, it is necessary to develop conventional casting superalloys with excellent properties similar to those of DS and SC alloys. For this purpose, a program to design and develop cast nickel-base superalloys was initiated in this investigation. Some methods, so called PHACOMP-Nv or NEW-PHACOMP-Md, allow one to estimate the phase stability of alloys, and eventually to improve it by modification of the composition. In fact these methods do not have a strong physical basis but are rather based on empirical correlations. In this paper, six compositions were calculated according to the conventional PHACOMP parameter calculation and based on the inventions Ni-Cr-W-Al-Ti-Ta system. Among them an alloy with high strength and superior creep rupture properties was determined. The phase stability was discussed using NEW-PHACOMP-Md concept.
Yao, X. [Shanghai Jiao Tong Univ. (China). Dept. of Materials Science] [Shanghai Jiao Tong Univ. (China). Dept. of Materials Science; Kim, H.; Choi, J. [Korea Inst. of Science and Technology, Cheongryang, Seoul (Korea, Republic of). Div. of Metals] [Korea Inst. of Science and Technology, Cheongryang, Seoul (Korea, Republic of). Div. of Metals
Covalent cum noncovalent functionalizations of carbon nanotubes for effective reinforcement of a solution cast composite film.
Although carbon nanotubes have impressive tensile properties, exploiting these properties in composites, especially those made by the common solution casting technique, seems to be elusive thus far. The reasons could be partly due to the poor nanotube dispersion and the weak nanotube/matrix interface. To solve this dual pronged problem, we combine noncovalent and covalent functionalizations of nanotubes in a single system by the design and application of a novel dispersant, hydroxyl polyimide-graft-bisphenol A diglyceryl acrylate (PI(OH)-BDA), and use them with epoxidized single-walled carbon nanotubes (O-SWNTs). Our novel PI(OH)-BDA dispersant functionalizes the nanotubes noncovalently to achieve good dispersion of the nanotubes because of the strong ?-? interaction due to main chain and steric hindrance of the BDA side chain. PI(OH)-BDA also functionalizes O-SWNTs covalently because it reacts with epoxide groups on the nanotubes, as well as the cyanate ester (CE) matrix used. The resulting solution-cast CE composites show 57%, 71%, and 124% increases in Young's modulus, tensile strength, and toughness over neat CE. These values are higher than those of composites reinforced with pristine SWNTs, epoxidized SWNTs, and pristine SWNTs dispersed with PI(OH)-BDA. The modulus and strength increase per unit nanotube weight fraction, i.e., dE/dW(NT) and d?/dW(NT), are 175 GPa and 7220 MPa, respectively, which are significantly higher than those of other nanotube/thermosetting composites (22-70 GPa and 140-3540 MPa, respectively). Our study indicates that covalent cum noncovalent functionalization of nanotubes is an effective tool for improving both the nanotube dispersion and nanotube/matrix interfacial interaction, resulting in significantly improved mechanical reinforcement of the solution-cast composites. PMID:22432973
Yuan, Wei; Chan-Park, Mary B
Moving through the phase diagram: morphology formation in solution cast polymer-fullerene blend films for organic solar cells.
The efficiency of organic bulk heterojunction solar cells strongly depends on the multiscale morphology of the interpenetrating polymer-fullerene network. Understanding the molecular assembly and the identification of influencing parameters is essential for a systematic optimization of such devices. Here, we investigate the molecular ordering during the drying of doctor-bladed polymer-fullerene blends on PEDOT:PSS-coated substrates simultaneously using in situ grazing incidence X-ray diffraction (GIXD) and laser reflectometry. In the process of blend crystallization, we observe the nucleation of well-aligned P3HT crystallites in edge-on orientation at the interface at the instant when P3HT solubility is crossed. A comparison of the real-time GIXD study at ternary blends with the binary phase diagrams of the drying blend film gives evidence of strong polymer-fullerene interactions that impede the crystal growth of PCBM, resulting in the aggregation of PCBM in the final drying stage. A systematic dependence of the film roughness on the drying time after crossing P3HT solubility has been shown. The highest efficiencies have been observed for slow drying at low temperatures which showed the strongest P3HT interchain ?-?-ordering along the substrate surface. By adding the "unfriendly" solvent cyclohexanone to a chlorobenzene solution of P3HT:PCBM, the solubility can be crossed prior to the drying process. Such solutions exhibit randomly orientated crystalline structures in the freshly cast film which results in a large crystalline orientation distribution in the dry film that has been shown to be beneficial for solar cell performance. PMID:22004659
Schmidt-Hansberg, Benjamin; Sanyal, Monamie; Klein, Michael F G; Pfaff, Marina; Schnabel, Natalie; Jaiser, Stefan; Vorobiev, Alexei; M³ller, Erich; Colsmann, Alexander; Scharfer, Philip; Gerthsen, Dagmar; Lemmer, Uli; Barrena, Esther; Schabel, Wilhelm
Paper Casting.
Describes an art project, based on the work of artist Chew Teng Beng, in the molding of wet paper on a plaster cast to create embossed paper designs. The values of such a project are outlined, including a note that its tactile approach makes it suitable to visually handicapped students. (SJL)
Arrasjid, Dorine A.
Capsules with prolonged action. III. Release of active ingredients from cast films.
In the preceding paper we described a gelation process and the development of sustained-release soft gelatin capsules containing codeine or theophylline. Applying this process to indomethacin and nifedipine as active ingredients led to insufficient release rates of the products. To investigate this phenomenon two simple membrane models were used, i.e., a cast drug-free membrane composed of different ratios of polyethylene glycol 400 in a matrix of 5% ethylcellulose, 10% sesame oil, and 57 to 69% citric acid triethyl ester and a cast drug-containing membrane with the same excipients. Codeine and indomethacin were able to penetrate drug-free membranes. The amount of drug diffused through the membrane correlates with the solubility data. Theophylline, which is insoluble in the matrix system, does not penetrate through a drug-free matrix. Nifedipine is enriched within the matrix because of its high partition coefficient into the matrix material, and therefore, little release is observed. From a drug-containing matrix, theophylline and nifedipine were released according to Higuchi's equation [J. Pharm. Sci. 52:1145-1149 (1963)], although the absolute amount of nifedipine released is limited because of its high solubility in the membrane material. For codeine and indomethacin there was no linear relationship between the amount of drug released and the square root of time. These results agree with the findings for capsules obtained from the gelation process. PMID:24271588
Schmidt, P C; Stockebrand, B
Film Analysis through Linguistic Base
Studies made in the last few years show that using films in language classrooms is an effective way in teaching a foreign language. Well-chosen films can serve as a valuable pedagogical aid, both for classroom use and self-study. This article is about using films in language classrooms through a specially designed course, whose outline descriptionģ
Tanriverdi, Belgin
LineCast: line-based distributed coding and transmission for broadcasting satellite images.
In this paper, we propose a novel coding and transmission scheme, called LineCast, for broadcasting satellite images to a large number of receivers. The proposed LineCast matches perfectly with the line scanning cameras that are widely adopted in orbit satellites to capture high-resolution images. On the sender side, each captured line is immediately compressed by a transform-domain scalar modulo quantization. Without syndrome coding, the transmission power is directly allocated to quantized coefficients by scaling the coefficients according to their distributions. Finally, the scaled coefficients are transmitted over a dense constellation. This line-based distributed scheme features low delay, low memory cost, and low complexity. On the receiver side, our proposed line-based prediction is used to generate side information from previously decoded lines, which fully utilizes the correlation among lines. The quantized coefficients are decoded by the linear least square estimator from the received data. The image line is then reconstructed by the scalar modulo dequantization using the generated side information. Since there is neither syndrome coding nor channel coding, the proposed LineCast can make a large number of receivers reach the qualities matching their channel conditions. Our theoretical analysis shows that the proposed LineCast can achieve Shannon's optimum performance by using a high-dimensional modulo-lattice quantization. Experiments on satellite images demonstrate that it achieves up to 1.9-dB gain over the state-of-the-art 2D broadcasting scheme and a gain of more than 5 dB over JPEG 2000 with forward error correction. PMID:24474371
Wu, Feng; Peng, Xiulian; Xu, Jizheng
Pattern formation in soft elastic films cast on periodically corrugated surfacesŚa linear stability and finite element analysis
Length scales of instabilities exhibited by soft, thin elastic films cast on smooth and sharp corrugated surfaces and in adhesive contact with an external contactor are investigated by means of linear stability analysis (LSA) and non-linear finite element analysis. The instability length scales are found to decrease with either an increase in the amplitude ? or a decrease in the wavelength ?p of the substrate pattern. For same substrate parameters, a step-patterned surface with higher RMS roughness is generally found to engender smaller length scales. The linear stability analysis with sinusoidally patterned substrates shows a reduced scaling of critical wavelength with substrate amplitude: ?c = 2.96(1 ? ?)h, where h is the mean film thickness. The largest substrate amplitudes explored with finite element analysis are limited to ? = 0.7, which is found to beget instability length scales of 0.89h, that are much smaller than the 3h length scale that is obtained with flat substrates. This suggests that an increase in substrate roughness via patterning can prove to be an attractive route for the production of miniaturized patterns.
Annepu, Hemalatha; Sarkar, Jayati; Basu, Sumit
Microwave transmittance in gelatin-based films
Biopolymers are alternative materials used in the production of edible and/or biodegradable films. A very important restriction factor concerning the films is their sensitivity to environmental conditions, such as temperature and relative humidity. The production of films based on gelatin and polyvinyl alcohol blends can be an alternative solution in order to reduce the sensitivity to the humidity. Thus, the aim of this work was to apply the microwave transmittance technique to measure qualitative effects of the presence of glycerol and polyvinyl alcohol on the moisture content of gelatin-based films. The results show that the films with glycerol, conditioned for one week in NaBr, revealed visible changes between 11 and 13 GHz as the plasticizer concentration increased. For gelatin films containing PVA, the results revealed very low microwave insertion losses. Thus, this behaviour was attributed to the presence of water molecules in gelatin films.
Bergo, P.; Carvalho, R. A.; Sobral, P. J. A.; Bevilacqua, F. R. S.; Pinto, J. K. C.; Souza, J. P.
A level set based method for the optimization of cast part
A cast part is formed via casting process in which molten liquid is poured into and solidifies in a cavity enclosed by molds.\\u000a Then, one obtains the cast part when the molds are removed. An important issue in the casting process is that a cast part\\u000a should have a proper geometry so that the molds can actually be removed. Accordingly,
Qi Xia; Tielin Shi; Michael Yu Wang; Shiyuan Liu
Corrosion behavior of cast and forged cobalt-based alloys for double-alloy joint endoprostheses.
An ideal combination of mechanical and corrosion properties of long-term implants such as joint endoprostheses has yet to be found. Besides being resistant to pitting and crevice attack, which can lead to corrosion fatigue and stress corrosion cracking failures, the implant material must be highly resistant to wear and abrasion. Two cobalt-based alloys, wrought CoNiMoTi and air-cast CoCrMo, were subjected to a number of selected in vitro electrochemically and chemically accelerated corrosion tests in chloride-containing solutions with wrought AISI-316L used as a reference alloy. A limited number of immersion tests in FeCl3 and acidified FeCl3 solutions were also conducted. It is found that the mechanical properties of wrought CoNiCrMoTi alloy qualify it as a substitute for cast CoCrMo alloy and wrought AISI-316L in anchorage shaft production for all types of joint endoprostheses. Wrought CoNiCrMoTi has a higher resistance to fatigue cracking compared with cast CoCrMo and is as resistant to selective corrosion phenomena such as stress corrosion cracking. PMID:701305
S³ry, P; Semlitsch, M
Morphological development in solvent-cast polystyrene(PS)-polybutadiene(PB)-polystyrene (SBS) triblock copolymer thin films
The morphological characteristics of block copolymers have been under intensive research, because of the rich polymer-physics questions they raise and because of the need for better understanding required by adhesive, compatibilizer, and template applications. In this research, the morphological transformations in solvent-cast polystyrene (PS)/polybutadiene (PB)/polystyrene (SBS)(30 wt% PS, Mw = 112,000) triblock copolymer thin films have been studied by transmission electron microscopy (TEM) as a function of solvent evaporation rate and post-evaporation annealing. Evaporation at: (i) ś200 nl/sec produces a microphase-separated microstructure with no long-range order; (ii) ś5 nl/sec generates hexagonally packed PS cylinders in a PB matrix with the cylinder axis perpendicular to the film plane; (iii) ś1.5 nl/sec leads to a duplex microstructure of PS cylinders with domains of either vertical or in-plane cylinders; (iv) ś0.2 nl/sec produces a fully in-plane cylinder microstructure. Post-evaporation annealing converts the duplex morphology into one with only in-plane PS cylinders. The equilibrium morphology of in-plane cylinders with PB-rich surface layers is generated when films are given relatively long exposure to high solvent concentration or elevated temperature. However, alternate and metastable morphologies are generated including ones with two-phase surface structure under kinetically constrained conditions. Cross-sectional TEM indicates that the surface microstructures vary with evaporation and annealing treatment. These results are interpreted in terms of the kinetics and thermodynamics of microphase separation.
Kim, Ginam
Composite edible films based on hydroxypropyl methylcellulose reinforced with microcrystalline cellulose nanoparticles.
It has been stated that hydroxypropyl methyl cellulose (HPMC) based films have promising applications in the food industry because of their environmental appeal, low cost, flexibility and transparency. Nevertheless, their mechanical and moisture barrier properties should be improved. The aim of this work was to enhance these properties by reinforcing the films with microcrystalline cellulose (MCC) at the nano scale level. Three sizes of MCC nanoparticles were incorporated into HPMC edible films at different concentrations. Identical MCC nanoparticles were lipid coated (LC) prior to casting into HPMC/LC-MCC composite films. The films were examined for mechanical and moisture barrier properties verifying how the addition of cellulose nanoparticles affected the water affinities (water adsorption/desorption isotherms) and the diffusion coefficients. The expected reinforcing effect of the MCC was observed: HPMC/MCC and HPMC/LC-MCC films showed up to 53% and 48% increase, respectively, in tensile strength values in comparison with unfilled HPMC films. Furthermore, addition of unmodified MCC nanoparticles reduced the moisture permeability up to 40% and use of LC-MCC reduced this value up to 50%. Water vapor permeability was mainly influenced by the differences in water solubility of different composite films since, in spite of the increase in water diffusivity values with the incorporation of MCC to HPMC films, better moisture barrier properties were achieved for HPMC/MCC and HPMC/LC-MCC composite films than for HPMC films. PMID:20187652
Bilbao-Sßinz, Cristina; Avena-Bustillos, Roberto J; Wood, Delilah F; Williams, Tina G; McHugh, Tara H
Mechanical and thermal properties of irradiated films based on Tilapia ( Oreochromis niloticus) proteins
Proteins are considered potential material in natural films as alternative to traditional packaging. When gamma radiation is applied to protein film forming solution it resulted in an improvement in mechanical properties of whey protein films. The objective of this work was the characterization of mechanical and thermal properties of irradiated films based on muscle proteins from Nile Tilapia ( Oreochromis niloticus). The films were prepared according to a casting technique with two levels of plasticizer: 25% and 45% glycerol and irradiated in electron accelerator type Radiation Dynamics, 0.550 MeV at dose range from 0 to 200 kGy. Thermal properties and mechanical properties were determined using a differential scanning calorimeter and a texture analyzer, respectively. Radiation from electron beam caused a slightly increase on its tensile strength characteristic at 100 kGy, while elongation value at this dose had no reduction.
Sabato, S. F.; Nakamurakare, N.; Sobral, P. J. A.
Photoactivated chlorophyllin-based gelatin films and coatings to prevent microbial contamination of food products.
The aim of this work was to develop antimicrobial photosensitizer-containing edible films and coatings based on gelatin as the polymer matrix, incorporating sodium magnesium chlorophyllin (E-140) and sodium copper chlorophyllin (E-141). Chlorophyllins were incorporated into the gelatin film-forming solution and the inhibiting effect of the cast films was tested against Staphylococcus aureus and Listeria monocytogenes. The results demonstrated that water soluble sodium magnesium chlorophyllin and water soluble sodium copper chlorophyllin reduced the growth of S. aureus and L. monocytogenes by 5 log and 4 log respectively. Subsequently, the activity of self-standing films and coatings containing E-140 was assessed on cooked frankfurters inoculated with S. aureus and L. monocytogenes. These tests showed that it was possible to reduce microorganism growth in cooked frankfurters inoculated with S. aureus and L. monocytogenes by covering them with sodium magnesium chlorophyllin-gelatin films and coatings. PMID:18555550
L¾pez-Carballo, G; Hernßndez-Mu±oz, P; Gavara, R; Ocio, M J
Modification of the microstructural and physical properties of konjac glucomannan-based films by alkali and sodium carboxymethylcellulose
Edible films were cast from konjac glucomannan (KGM) solutions, with or without added alkali (KOH) and\\/or sodium carboxymethylcellulose (CMC). Four types of KGM-based films (KGM, KGM¢KOH, KGM¢CMC and KGM¢CMC¢KOH) were produced and characterized by scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), moisture sorption, water vapour permeability (WVP), and tensile tests. Tensile properties were studied as a function of water
L. H. Cheng; A. Abd Karim; M. H. Norziah; C. C. Seow
Organic Thin-Film Transistors Based On Conjugated Polymer and Carbon Nanotube Composites
In this paper we report on thin film transistors based on poly(3-hexylthiophene) (P3HT) and carbon nanotubes (CNTs) composite active materials. Single walled CNTs were dispersed into P3HT chloroform solution. By drop casting, the composite solution was deposited onto the pre-fabricated device and formed thin active layer. The effect of different concentrations of CNTs to the charge carrier mobility of the
Ye Gan; Chang Ming Li
Preparation, surface modification and characterisation of solution cast starch PVA blended films
Several blends have been prepared of polyvinyl alcohol, starch and glycerol. The blend containing 20% polyvinyl alcohol has been modified by application of chitosan to the surface. The blend, and its modified form have been characterised by atomic force microscopy, x-ray diffraction, Fourier transform infra-red spectroscopy, contact angle measurements, 13C-NMR spectroscopy and scanning electron microscopy. The blended films were flexible
R Jayasekara; I Harding; I Bowater; G. B. Y Christie; G. T Lonergan
Sliding wear and friction characteristics of six Zn-based die-casting alloys
The friction and wear characteristics of zinc-based alloys in warm, oil-lubricated, sliding contact against mild steel were investigated. The alloys, their compositions, and their microstructures included: pure Zn (100% Zn, ? zinc), Zamak 3 (Zn?4Al?0.1Cu, ? zinc plus ?? eutectic), ZA 27 (Zn?31Al?2.3Cu, ? aluminum plus ?ga eutectic), ACuZinc 5 (Zn?3.0Al?5Cu) in die cast form, and ACuZinc 10 (Zn?3.5Al?10Cu, epsilon
M. D. Hanna; J. T. Carter; M. S. Rashid
Investigation on the dissolution of ? phase in a cast Ni-based superalloy
The dissolution behavior of ? phase has been investigated in a cast Ni-based superalloy. The results showed that the platelets and blocks of ? phase were formed within the interdendritic regions of the microstructure. Applying standard solution annealing at 1150-1160░C for a period of 4 h did not result in the complete dissolution of ? phase. For the complete dissolution of ? phase without residual incipient melting, a 2-step solution annealing has been recommended. After dissolution at high temperatures, the ? phase transforms to two MC-type carbides: one is enriched in Ti, Nb, and Ta, and the other is of (Zr,Ti)C type.
Jahangiri, M. R.; Arabi, H.; Boutorabi, S. M. A.
Novel composite films based on amidated pectin for cationic dye adsorption.
Pectin, with its tendency to gel in the presence of metal ions has become a widely used material for capturing the metal ions from wastewaters. Its dye-capturing properties have been much less investigated, and this paper is the first to show how films based on amidated pectin can be used for cationic dye adsorption. In the present study amidated pectin/montmorillonite composite films were synthesized by membrane casting, and they are stable in aqueous solution both below and above pectin pKa. FTIR, thermogravimetry and SEM-EDAX have confirmed the presence of montmorillonite in the cast films and the interactions between the two constituents. In order to evaluate the cationic dye adsorption of these films Basic Yellow 28 was used, showing that the films have higher adsorption capacity compared to the others reported in the literature. The results were fitted into Langmuir, Freundlich and Temkin isotherms indicating an exothermic process and setting the optimum amount of montmorillonite in the films to 30% of pectin mass. According to the Langmuir isotherm the maximum adsorption capacity is 571.4 mg/g. PMID:24268651
Nesic, Aleksandra R; Velickovic, Sava J; Antonovic, Dusan G
Classification techniques based on AI application to defect classification in cast aluminum
This paper describes the Artificial Intelligent techniques applied to the interpretation process of images from cast aluminum surface presenting different defects. The whole process includes on-line defect detection, feature extraction and defect classification. These topics are discussed in depth through the paper. Data preprocessing process, as well as segmentation and feature extraction are described. At this point, algorithms employed along with used descriptors are shown. Syntactic filter has been developed to modelate the information and to generate the input vector to the classification system. Classification of defects is achieved by means of rule-based systems, fuzzy models and neural nets. Different classification subsystems perform together for the resolution of a pattern recognition problem (hybrid systems). Firstly, syntactic methods are used to obtain the filter that reduces the dimension of the input vector to the classification process. Rule-based classification is achieved associating a grammar to each defect type; the knowledge-base will be formed by the information derived from the syntactic filter along with the inferred rules. The fuzzy classification sub-system uses production rules with fuzzy antecedent and their consequents are ownership rates to every defect type. Different architectures of neural nets have been implemented with different results, as shown along the paper. In the higher classification level, the information given by the heterogeneous systems as well as the history of the process is supplied to an Expert System in order to drive the casting process.
Platero, Carlos; Fernandez, Carlos; Campoy, Pascual; Aracil, Rafael
Fuzzy rule based classification and quantification of graphite inclusions from microstructure images of cast iron.
The quantification of three classes of graphite inclusions in cast iron, namely, nodular, flake, and irregular, is the most important process in the foundry industry. This classification is based on the ISO 945 proposed morphology of graphite inclusions. This work presents a novel solution for automatic quantitative analysis of graphite inclusions into the three mentioned classes. The proposed work comprises three stages, namely, preprocessing of micrographs, classification of graphite inclusions, and then quantification of inclusions in each class. An effort has been made in this work to propose a minimum set of features to represent graphite inclusion morphology. The method employs just two geometric shape descriptors: the diameter ratio and the area ratio. A fuzzy rule based classifier is built using known feature values that are efficient in the classification of the three classes of graphite inclusions. The proposed method is automatic, fast, and provides the basis for determining many more morphological parameters that can be determined with the least effort. The results obtained by the proposed method are compared with the manual method. It is observed that the results obtained from the proposed method are useful in the optimization of cast iron manufacturing in the foundry industry. PMID:22053909
Prakash, Pattan; Mytri, V D; Hiremath, P S
Cooling Slope Casting Process for Synthesis of Bulk Metallic Glass Based Composites with Semisolid Structure
A process combining cooling slope casting and suction casting was developed to generate a semisolid structure in a Zr-based bulk metallic glass matrix composite. The melt was injected onto a cooling slope and subsequently vacuum sucked into a cylindrical copper mold placed at the end of the slope. The structure obtained for 4-mm-diameter specimens of composition Zr66.4Nb6.4Cu10.5Ni8.7Al8 consists of a dispersion of spheroidal and rosettelike bcc crystals in a glassy matrix. Various slope angles, slope lengths, and injection pressures were tested. The coarsest and most spheroidal crystal structure was obtained at short slope lengths and high injection pressures. Microstructure analysis suggests that the slope is the location of extensive crystal nucleation and possible fragmentation, while the microstructureÆs morphological evolution seems to occur mainly in the mold. The semisolid structure is expected to confer improved mechanical properties and ductility to the composite material.
Makaya, Advenit; Tamura, Takuya; Miwa, Kenji
Microstructure-based fatigue life prediction for cast A356-T6 aluminum-silicon alloys
Fatigue life prediction and optimization is becoming a critical issue affecting the structural applications of cast aluminum-silicon alloys in the aerospace and automobile industries. In this study, a range of microstructure and porosity populations in A356 alloy was created by controlling the casting conditions and by applying a subsequent hot isostatic pressing (ōhippingö) treatment. The microstructure and defects introduced during the processing were then quantitatively characterized, and their effects on the fatigue performance were examined through both experiment and modeling. The results indicated that whenever a pore is present at or near the surface, it initiates fatigue failure. In the absence of large pores, a microcell consisting of ?-Al dendrites and associated Si particles was found to be responsible for crack initiation. Crack initiation life was quantitatively assessed using a local plastic strain accumulation model. Moreover, the subsequent crack growth from either a pore or a microcell was found to follow a small-crack propagation law. Based on experimental observation and finite-element analysis, a unified model incorporating both the initiation and small crack growth stages was developed to quantitatively predict the dependency of fatigue life on the microstructure and porosity. Good agreement was obtained between the model and experiment.
Yi, J. Z.; Gao, Y. X.; Lee, P. D.; Lindley, T. C.
Context-based user grouping for multi-casting in heterogeneous radio networks
Along with the rise of sophisticated smartphones and smart spaces, the availability of both static and dynamic context information has steadily been increasing in recent years. Due to the popularity of social networks, these data are complemented by profile information about individual users. Making use of this information by classifying users in wireless networks enables targeted content and advertisement delivery as well as optimizing network resources, in particular bandwidth utilization, by facilitating group-based multi-casting. In this paper, we present the design and implementation of a web service for advanced user classification based on user, network, and environmental context information. The service employs simple and advanced clustering algorithms for forming classes of users. Available service functionalities include group formation, context-aware adaptation, and deletion as well as the exposure of group characteristics. Moreover, the results of a performance evaluation, where the service has been integrated in a simulator modeling user behavior in heterogeneous wireless systems, are presented.
Mannweiler, C.; Klein, A.; Schneider, J.; Schotten, H. D.
Background Cassava starch, the economically important agricultural commodity in Thailand, can readily be cast into films. However, the cassava starch film is brittle and weak, leading to inadequate mechanical properties. The properties of starch film can be improved by adding plasticizers and blending with the other biopolymers. Results Cassava starch (5%w/v) based films plasticized with glycerol (30 g/100 g starch) were characterized with respect to the effect of carboxymethyl cellulose (CMC) concentrations (0, 10, 20, 30 and 40%w/w total solid) and relative humidity (34 and 54%RH) on the mechanical properties of the films. Additionally, intermolecular interactions were determined by Fourier transform infrared spectroscopy (FT-IR), melting temperature by differential scanning calorimetry (DSC), and morphology by scanning electron microscopy (SEM). Water solubility of the films was also determined. Increasing concentration of CMC increased tensile strength, reduced elongation at break, and decreased water solubility of the blended films. FT-IR spectra indicated intermolecular interactions between cassava starch and CMC in blended films by shifting of carboxyl (C = O) and OH groups. DSC thermograms and SEM micrographs confirmed homogeneity of cassava starch-CMC films. Conclusion The addition of CMC to the cassava starch films increased tensile strength and reduced elongation at break of the blended films. This was ascribed to the good interaction between cassava starch and CMC. Cassava starch-CMC composite films have the potential to replace conventional packaging, and the films developed in this work are suggested to be suitable for low moisture food and pharmaceutical products.
Synthesis of nano cellulose fibers and effect on thermoplastics starch based films.
Starch based films limit their application due to highly hydrophilic nature and poor mechanical properties. This problem was sought to be overcome by forming a nanocomposite of Thermoplastic starch (TPS) and Nano-Cellulose fibers (NCF). NCF was successfully synthesised from short stable cotton fibres by a chemo-mechanical process. TPS/NCF composite films were prepared by solution casting method, and their characterizations were done in terms of differential scanning calorimeter (DSC), morphology (SEM), water vapor permeability (WVTR), oxygen transmission rate (OTR), X-ray diffractograms, light transmittance and tensile properties. At very low concentration of NCF filled TPS composite film showed improvement in properties. The 0.4wt% NCF loaded TPS films showed 46.10% improved tensile strength than by base polymer film, beyond that 0.5wt% concentration tensile strength starts to deteriorate. WVTR and OTR results showed improved water vapor barrier property of TPS matrix. The DSC thermograms of TPS and composite films did not show any significant effect on the melting point of composite film to the base polymer TPS. PMID:24750616
Savadekar, N R; Mhaske, S T
Properties of triticale flour protein based films
Triticale flour proteins based films were developed. Solubility in water, water vapor permeability (WVP), and mechanical properties of triticale films are presented. The effects of thermal treatments and glycerol concentration were also evaluated. WVP values were in the range 0.10¢4.22ĀūĀ10?10ĀgĀm?1Ās?1ĀPa?1. Tensile strength (TS) and percentage of elongation (%E) were in the range 2.9¢0.20ĀMPa and 250¢110% respectively. Total soluble matter (TSM),
A. Aguirre; R. Borneo; A. E. Le¾n
Synthesis and evaluation of rosin-based polymers as film coating materials.
Rosin-based polymers (R-1 and R-2) were synthesized and characterized for physicochemical properties, molecular weight (Mw), polydispersity (Mw/Mn), glass transition temperature (Tg), and thermogravimetry (TGA). Films of the polymers were cast on a mercury substrate by solvent evaporation technique. Free films were characterized for surface topography by scanning electron microscopy (SEM), water vapor transmission rate (WVTR), tensile strength, percentage elongation, and modulus of elasticity. The polymers were further evaluated as film coating materials by evaluating drug release from coated pellets with diclofenac sodium as a model drug. Drug was loaded on non-pareil seeds by a solution-layering technique and coated with varying concentrations of polymer solutions. Sustained release of the drug was observed from coated pellets. The newly synthesized rosin-based polymers promise considerable utility for pharmaceutical coating. PMID:12056531
Satturwar, P M; Mandaogade, P M; Fulzele, S V; Darwhekar, G N; Joshi, S B; Dorle, A K
Microstructure and stress rupture properties of polycrystal and directionally solidified castings of nickel-based superalloys
A new directionally solidified Ni-based superalloy DZ24, which is a modification of K24 alloy without rare and expensive elemental additions, such as Ta and Hf, was studied in this paper. The microstructure and stress rupture properties of conventionally cast and directionally solidified superalloys were comparatively analyzed. It is indicated that the microstructure of K24 alloy is composed of ?, ?', ?/?' eutectics and MC carbides. Compared with the microstructure of K24 polycrystalline alloy, ?/?' eutectic completely dissolves into the ? matrix, the fine and regular ?' phase reprecipitates, and MC carbides decompose to M6C/M23C6 carbides after heat treatment in DZ24 alloy. The rupture life of DZ24 alloy is two times longer than that of K24 alloy. The more homogeneous the size of ?' precipitate, the longer the rupture life. The coarsening and rafting behaviors of ?' precipitates are observed in DZ24 alloy after the stress-rupture test.
Wu, Bao-ping; Li, Lin-han; Wu, Jian-tao; Wang, Zhen; Wang, Yan-bin; Chen, Xing-fu; Dong, Jian-xin; Li, Jun-tao
Improvement of the mechanical and barrier properties of methylcellulose-based films by treatment with HEMA and silane monomers under gamma radiation
Methylcellulose (MC)-based films were prepared by casting from its 1% aqueous solution containing 0.5% vegetable oil, 0.25% glycerol and 0.025% Tween«-80. Puncture strength (PS), puncture deformation (PD) and water vapor permeability (WVP) of the films were found to be 147 N/mm, 3.46 mm, and 6.34 g mm/m2 day kPa, respectively. The monomer, 2-hydroxyethyl methacrylate (HEMA) (0.1-1%, w/w) was incorporated into the MC-based solution and films were prepared by casting. Films were then exposed to gamma radiation (5-25 kGy) and it revealed that 1% HEMA containing films showed the highest PS values (282 N/mm at 10 kGy). Silane monomer (3-aminopropyl tri-ethoxy silane) (0.1-1%, w/w) was also added into the MC-based films and were found to improve the strength of the films significantly. In comparison between HEMA and silane treatment onto MC-based films, it was observed that silane performed better strength and barrier properties. Surface morphology of the monomer treated films was examined by scanning electron microscopy and suggested better appearance than MC-based film.
Khan, Ruhul A.; Dussault, Dominic; Salmieri, Stephane; Safrany, Agnes; Lacroix, Monique
Development of NZP ceramic based {open_quotes}cast-in-place{close_quotes} diesel engine port liners
BSX (Ba{sub 1+x}Zr{sub 4}P{sub 6-2x}Si{sub 2x}O{sub 24}) and CSX (Ca{sub l-x}Sr{sub x}Zr{sub 4}P{sub 6}O{sub 24}) type NZP ceramics were fabricated and characterized for: (i) thermal properties viz., thermal conductivity, thermal expansion, thermal stability and thermal shock resistance; (ii) mechanical properties viz., flexure strength and elastic modulus; and (iii) microstructures. Results of these tests and analysis indicated that the BS-25 (x=0.25 in BSX) and CS-50 (x=0.50 in CSX) ceramics had the most desirable properties for casting metal with ceramic in place. Finite element analysis (FEA) of metal casting (with ceramic in place) was conducted to analyze thermomechanical stresses generated and determine material property requirements. Actual metal casting trials were also conducted to verify the results of finite element analysis. In initial trials, the ceramic cracked because of the large thermal expansion mismatch (hoop) stresses (predicted by FEA also). A process for introduction of a compliant layer between the metal and ceramic to alleviate such destructive stresses was developed. The compliant layer was successful in preventing cracking of either the ceramic or the metal. In addition to these achievements, pressure slip casting and gel-casting processes for fabrication of NZP components; and acoustic emission and ultrasonics-based NDE techniques for detection of microcracks and internal flaws, respectively, were successfully developed.
Nagaswaran, R.; Limaye, S.Y.
[Cast structures and mechanical properties of Ir added to Ag-based alloys. (Part 1) (author's transl)].
The effect of very small quantity of Ir added to pure Agb or Ab-based casting alloys on the mechanical properties were investigated by microstructure observation, tensile test, XMA (electron probe micro analysis) and electrical resistivity measurement. 1) An addition of 0.005% Ir to pure Ag caused grain refinement, increased elongation, yield point, tensile strength. However, the refinement effect did not proportionally increase to the amount of additional Ir. 2) An addition of Ir to Ag alloy containing 7% Cu caused to finely dispersed beta phase in the as cast alloy and degraded the dendrite structure. As a result, homogenization and aging were accelerated. Mechanical properties i. e. elongation, yield point and tensile strength increased in castings and homogeneous state and yield point increased in aging state. The addition of about 0.05% Ir appeared optimum. 3) An addition of Ir to an Ag alloy containing 15% Cu caused grain refinement of the alloy as cast but its effect on the mechanical properties of the alloy was not clarified owing to casting defects. 4) 0.05% Ir added to an Ag alloy containing 20% Pd and 7% Cu did not show an apparent refinement effect. The optimum quantity of Ir is assumed to differ depending on the amount of Pd content. PMID:7033415
Honma, H; Iijima, K
Search for promising compositions for developing new multiphase casting alloys based on Al-Zn-Mg matrix using thermodynamic calculations and mathematic simulation
The search for promising systems of alloying for developing new casting alloys based on a thermally improved Al-Zn-Mg matrix with poorly soluble additives of eutectic-forming elements has been performed. Alloy compositions with a necessary complex of mechanical and casting properties have been chosen based on thermodynamic calculations and mathematic simulation.
Zolotorevskii, V. S.; Pozdnyakov, A. V.; Churyumov, A. Yu.
High Throughput Prioritization for Integrated Toxicity Testing Based on ToxCast Chemical Profiling
EPA Science Inventory
The rational prioritization of chemicals for integrated toxicity testing is a central goal of the U.S. EPA?s ToxCast? program (http://epa.gov/ncct/toxcast/). ToxCast includes a wide-ranging battery of over 500 in vitro high-throughput screening assays which in Phase I was used to...
Plasmonic films based on colloidal lithography.
This paper reviews recent advances in the field of plasmonic films fabricated by colloidal lithography. Compared with conventional lithography techniques such as electron beam lithography and focused ion beam lithography, the unconventional colloidal lithography technique with advantages of low-cost and high-throughput has made the fabrication process more efficient, and moreover brought out novel films that show remarkable surface plasmon features. These plasmonic films include those with nanohole arrays, nanovoid arrays and nanoshell arrays with precisely controlled shapes, sizes, and spacing. Based on these novel nanostructures, optical and sensing performances can be greatly enhanced. The introduction of colloidal lithography provides not only efficient fabrication processes but also plasmonic films with unique nanostructures, which are difficult to be fabricated by conventional lithography techniques. PMID:24321859
Ai, Bin; Yu, Ye; M÷hwald, Helmuth; Zhang, Gang; Yang, Bai
Si-based multilayered print circuit board for MEMS packaging fabricated by Si deep etching, bonding, and vacuum metal casting
In our previous works, metal injection technique into small diameter (10 -100micrometers ) through holes was developed and applied for fabrication of Si based print circuit board. In the present work, we present the metal filling technology by vacuum casting into 3 dimensional through holes and trenches structure fabricated in stacked layered Si wafers prepared by fusion bonding of ICP
Yoichi Murakoshi; Kotaro Hanada; Yaomin Li; Kazuyoshi Uchino; Takaaki Suzuki; Ryutaro Maeda
Creep-Rupture Behavior of a Developmental Cast-Iron-Base Alloy for Use Up to 800 deg C.
As part of the DOE/NASA Stirling Engine Systems Project, an iron-base cast alloy was developed, designated NASAUT 4G-Al. Its nominal composition, in percent by weight, is Fe-15Mn-15Cr-2Mo-1.5C-1Nb-1Si. This report presents the results of a study of this a...
R. H. Titran C. M. Scheuermann
The fabrication and characterisation of low- k cordierite-based glass¢ceramics by aqueous tape casting
In this work, cordierite-based glass ceramic tapes were prepared by tape casting from suspensions containing different solids loading and different average particle sizes (PS). Three different empirical models were used to fit the experimental data from relative viscosity measured at a fixed shear rate (500 s?1) versus solids loading. The green tapes were characterised by using scanning electron microscopy (SEM)
Sen Mei; Juan Yang; Josķ M. F. Ferreira
Properties and cyclic fatigue of glass infiltrated tape cast alumina cores produced using a water-based solvent
ObjectiveThe purpose of this study was to investigate the properties of tape cast alumina composite produced using a water-based solvent and its possible clinical use as an all ceramic crown system in a fixed partial denture. Durability of the system will be measured by fatigue test to simulate the masticating conditions of the oral cavity.
Nam-Sik Oh; Dae-Joon Kim; Joo L. Ong; Ho-Young Lee; Keun-Woo Lee
Effects of Composition and Testing Conditions on Oxidation Behavior of Four Cast Commercial Nickel-Base Superalloys.
Four cast nickel-base superalloys were oxidized at 1000 and 1100 C for times up to 100 hr in static air and a Mach 1 gas stream. The oxidation resistance was judged by weight change, metal thickness loss, depletion-zone formation, and oxide formation and ...
C. E. Lowell H. B. Probst
Enhanced Performance Consistency in Nanoparticle/TIPS Pentacene-Based Organic Thin Film Transistors
In this study, inorganic silica nanoparticles are used to manipulate the morphology of 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS pentacene) thin films and the performance of solution-processed organic thin-film transistors (OTFTs). This approach is taken to control crystal anisotropy, which is the origin of poor consistency in TIPS pentacene based OTFT devices. Thin film active layers are produced by drop-casting mixtures of SiO{sub 2} nanoparticles and TIPS pentacene. The resultant drop-cast films yield improved morphological uniformity at {approx}10% SiO{sub 2} loading, which also leads to a 3-fold increase in average mobility and nearly 4 times reduction in the ratio of measured mobility standard deviation ({mu}{sub Stdev}) to average mobility ({mu}{sub Avg}). Grazing-incidence X-ray diffraction, scanning and transmission electron microscopy as well as polarized optical microscopy are used to investigate the nanoparticle-mediated TIPS pentacene crystallization. The experimental results suggest that the SiO{sub 2} nanoparticles mostly aggregate at TIPS pentacene grain boundaries, and 10% nanoparticle concentration effectively reduces the undesirable crystal misorientation without considerably compromising TIPS pentacene crystallinity.
He, Zhengran [ORNL] [ORNL; Xiao, Kai [ORNL] [ORNL; Durant, William Mark [ORNL] [ORNL; Anthony, John E. [University of Kentucky, Lexington] [University of Kentucky, Lexington; Kilbey, II, S Michael [ORNL; Chen, Jihua [ORNL] [ORNL; Li, Dawen [ORNL] [ORNL
Poly(vinyl alcohol)-Based Film Potentially Suitable for Antimicrobial Packaging Applications.
This work aimed at developing a thin and water-resistant food-grade poly(vinyl alcohol) (PVOH)-based matrix able to swell when in contact with high moisture content food products without rupturing to release antimicrobial agents onto the food surface. This film was prepared by blending PVOH and 7.20% (wt/wt of PVOH) of poly(ethylene glycol) (PEG) with citric acid as crosslinking agent. The film-forming solution was then casted onto a flat surface and the obtained film was 60 ?m in thickness and showed a good transparency (close to T = 100%) in the visible region (400 to 700 nm). After immersion in water for 72 h at room temperature, the crosslinked matrix loses only 19.2% of its original weight (the percentage includes the amount of unreacted crosslinking agent, antimicrobial in itself). Water content, degree of swelling, and crosslinking density of the film prove that the presence of PEG diminishes the hydrophilic behavior of the material. Also the mechanical properties of the wet and dry film were assessed. Alongside this, 2.5% (wt/wt of dry film) of grapefruit seed extract (GSE), an antimicrobial agent, was added to the film-forming solution just before casting and the ability of the plastic matrix to release the additive was then evaluated in vitro against 2 GSE-susceptible microorganisms, Salmonella enteritidis and Listeria innocua. The results indicate that the developed matrix may be a promising food-grade material for the incorporation of active substances. PMID:24611868
Musetti, Alessandro; Paderni, Katia; Fabbri, Paola; Pulvirenti, Andrea; Al-Moghazy, Marwa; Fava, Patrizia
Preparation of nano cellulose fibers and its application in kappa-carrageenan based film.
Bio-based nanocomposite films were successfully developed using nanofibrillated cellulose (NFC) as the reinforcing phase and kappa-carrageenan (KCRG) as the matrix. NFC was successfully synthesis from short stable cotton fibers by chemo-mechanical process. The bionanocomposites were prepared by incorporating 0.1, 0.2, 0.3, 0.4, 0.5, and 1wt% of the NFC into a KCRG matrix using a solution casting method there characterization was done in terms of thermal properties (DSC), morphology (SEM), water vapor transmission rate (WVTR), oxygen transmission rate (OTR), X-ray diffractograms (XRD), and tensile properties. The main conclusion arising from the analysis of the result is that the bionanocomposites containing 0.4wt% of NFC exhibited the highest enhancement in tensile strength it is almost 44% improvement. WVTR and OTR results showed improvement of all nanocomposite film compare to control KCRG film. PMID:22940239
Savadekar, N R; Karande, V S; Vigneshwaran, N; Bharimalla, A K; Mhaske, S T
Development of model for barrier and optical properties of tapioca starch based edible films.
The film forming solutions composed of tapioca (cassava) starch (1-3 g), glycerol (0.5-1.0 ml), agar (0.5-1.0 g) and span 80 (0.1-0.5 ml) were prepared according to a three-level, four-factor Box-Behnken response surface experimental design. The films were obtained by casting method and they are homogenous and transparent. The influence of film composition (tapioca starch, glycerol, agar and span80) on the barrier and optical properties of the tapioca starch based edible films was evaluated. The results showed that, hydrophilic nature and plasticizing effect of glycerol increases the water vapor permeability, oxygen permeability, moisture content, solubility and swelling capacity of the films. But surfactant (span80) incorporation reduces the mobility of the polysaccharide matrix and decreases the barrier properties of the films. Transparency of the films was influenced by plasticizer and surfactant concentration due to the dilution effect of glycerol and span80. The results were analyzed by Pareto analysis of variance (ANOVA) and second-order polynomial models were developed using multiple regression analysis. The models developed from the experimental design were predictive and good fit with the experimental data with high coefficient of determination (R(2)) values (more than 0.95). The optimized conditions were obtained were tapioca starch of 1.95 g, glycerol of 0.8 ml, agar of 0.7 g and span 80 of 0.3 ml, respectively. PMID:23399163
Maran, J Prakash; Sivakumar, V; Sridhar, R; Thirugnanasambandham, K
A comparative study on microgap of premade abutments and abutments cast in base metal alloys.
The study compared the marginal accuracy of premade and cast abutments. Premade titanium, stainless steel, and gold abutments formed the control groups. Plastic abutments were cast in nickel-chromium, cobalt-chromium and grade IV titanium. The abutment/implant interface was analyzed. Analysis of variance and Duncan's multiple range test revealed no significant difference in mean marginal microgap between premade gold and titanium abutments and between premade stainless steel and cast titanium abutments. Statistically significant differences (P < .001) were found among all other groups. PMID:24914909
Lalithamma, Jaini Jaini; Mallan, Sreekanth Anantha; Murukan, Pazhani Appan; Zarina, Rita
Effect of grain refinement on the room-temperature ductility of as-cast Fe(sub 3)Al-based alloys.
Fe(sub 3)Al-based alloys exhibit poor room temperature ductility in the as-cast condition. In this study, the effect of grain refinement of the as-cast alloy on room-temperature ductility was investigated. Small melts of Fe-28 at. % Al-5 at. % Cr were ino...
S. Viswanathan V. K. Andleigh C. G. McKamey
-Based Mold Flux and Their Effects on In-Mold Performance during High-Aluminum TRIP Steels Continuous Casting
Crystallization behaviors of the newly developed lime-alumina-based mold fluxes for high-aluminum transformation induced plasticity (TRIP) steels casting were experimentally studied, and compared with those of lime-silica-based mold fluxes. The effects of mold flux crystallization characteristics on heat transfer and lubrication performance in casting high-Al TRIP steels were also evaluated. The results show that the crystallization temperatures of lime-alumina-based mold fluxes are much lower than those of lime-silica-based mold fluxes. Increasing B2O3 addition suppresses the crystallization of lime-alumina-based mold fluxes, while Na2O exhibits an opposite effect. In continuous cooling of lime-alumina-based mold fluxes with high B2O3 contents and a CaO/Al2O3 ratio of 3.3, faceted cuspidine precipitates first, followed by needle-like CaOĘB2O3 or 9CaOĘ3B2O3ĘCaF2. In lime-alumina-based mold flux with low B2O3 content (5.4 mass pct) and a CaO/Al2O3 ratio of 1.2, the formation of fine CaF2 takes place first, followed by blocky interconnected CaOĘ2Al2O3 as the dominant crystalline phase, and rod-like 2CaOĘB2O3 precipitates at lower temperature during continuous cooling of the mold flux. In B2O3-free mold flux, blocky interconnected 3CaOĘAl2O3 precipitates after CaF2 and 3CaOĘ2SiO2 formation, and takes up almost the whole crystalline fraction. The casting trials show that the mold heat transfer rate significantly decreases near the meniscus during the continuous casting using lime-alumina-mold fluxes with higher crystallinity, which brings a great reduction of surface depressions on cast slabs. However, excessive crystallinity of mold flux causes poor lubrication between mold and solidifying steel shell, which induces various defects such as drag marks on cast slab. Among the studied mold fluxes, lime-alumina-based mold fluxes with higher B2O3 contents and a CaO/Al2O3 ratio of 3.3 show comparatively improved performance.
Shi, Cheng-Bin; Seo, Myung-Duk; Cho, Jung-Wook; Kim, Seon-Hyo
Haemocompatibility of carbon based thin films
Haemocompatibility is one of the most important properties that determine the biocompatibility of the artificial implants. The haemocompatibility testing is to look for possible undesirable effects (e.g., haemolysis, thrombus formation, alterations in coagulation) in the blood, caused by a medical device or by chemicals leaching from a device. Carbon based thin films, such as amorphous carbon (a-C) and amorphous hydrogenated
S. Logothetidis
Machine Casting of Ferrous Alloys.
A series of iron, nickel, and cobalt base alloys were permanent mold cast under varying conditions to evaluate techniques for improving the integrity of die casting. By appropriate control of heat flow it is possible to achieve permanent mold casting with...
M. F. X. Gigliotti
Conformation of polyaniline: Effect of mechanical shaking and spin casting
We find from diffuse reflectance Vis\\/UV spectral studies of polyaniline (emeraldine base; EB) powder doped with camphorsulfonic acid (HCSA) that the free carrier tail characteristic of an extended coil conformation appears and increases gradually on mechanical shaking with KBr powder. We also find that the forces present during spin-casting of EB films have a signifigant effect on the value of
J. Feng; A. G. MacDiarmid; A. J. Epstein
Biphasic calcium phosphate coating on cobalt-base surgical alloy during investment casting.
The biphasic calcium phosphate (BCP) yields higher bioactivity and efficiency than the Hydroxyapatite (HA) alone. The HA/?-TCP ratio significantly affects BCP bioactivity as well as the extent of BCP resorption. In this study, the BCP coating on ASTM F-75 cobalt base alloy during the investment casting process was investigated. For this purpose, molten metal was poured at 1,470░C into previously coated investment molds preheated to 750, 850, 950, 1,050░C in order to investigate the effect of mold preheating temperatures on coating phase transformations. For in vitro evaluation, samples were immersed in the simulated body fluid (SBF) at 37░C for 4 weeks and characterized by XRD, SEM, EDS, and optical microscopy. The weight percentages of HA and ?-TCP of the specimens were calculated to find that the HA/?-TCP ratio significantly depended on the mold preheating temperature as it caused changes in the dissolution behavior of BCP coating and the bone-like apatite precipitation on coating during in vitro evaluation. PMID:21894538
Minouei, H; Meratian, M; Fathi, M H; Ghazvinizadeh, H
Infrared spectroscopic study of molecular interaction of tacticity-controlled poly(N-isopropylacrylamide) in a cast film deposited on a solid substrate.
Analytical results of a series of poly(N-isopropylacrylamide) (PNiPA) with different tacticities using infrared spectroscopy are presented for studying the influence of the solvation and molecular interactions between the polymeric chains. Infrared spectra of solid matter samples of the compounds exhibit a systematic band intensity change for three band components at 1,680, 1,659, and 1,628 cm(-1) involved in the amide I band. The three components correspond to the free, half, and full hydrogen bondings of the secondary amide group, which reflect the molecular configuration depending on the tacticity. When cast films of the compounds prepared on a solid surface are analyzed by infrared transmission spectrometry, another factor of the solvent used for the film preparation is found to be another factor which plays an important role in determining the molecular architecture in the films. This molecular imprint mechanism after the solvation is confirmed by measuring infrared multiple-angle incidence resolution spectra of annealed films. The molecular interactions in the polymeric samples have been revealed by the use of infrared spectroscopy and the tacticity-controlled samples. PMID:20740277
Hasegawa, Takeshi; Tatsuta, Shuntaro; Katsumoto, Yukiteru
Biodegradable packages development from starch based heat sealable films
Heat sealing capacity of native and acetylated corn starch based films was evaluated to develop biodegradable packages, such as bags. Thermo-mechanical properties were analyzed since they condition their handling and applications. Acetylated starch addition reinforced 80% sealing resistance of starch films. Unplasticized heat-sealed films presented adhesive failures while those containing glycerol showed a rupture near the zip. Unplasticized films exhibited
Olivia V. L¾pez; Carlos J. Lecot; NoemĒ E. Zaritzky; MarĒa A. GarcĒa
High-cycle fatigue-life of the cast nickel base-superalloys in 738 LC and IN 939
The high cycle fatigue (HCF) properties of two cast nickel base-superalloys, IN 738 LC and IN 939, were investigated using\\u000a both fracture mechanics samples and smooth specimens. The crack propagation behavior was studied in terms of linear fracture\\u000a mechanics at RT and at 850 C. In addition to the influence of temperature, the influences of frequency, mean stress, and\\u000a environment
W. Hoffelner
Aqueous tape casting processing of low dielectric constant cordierite-based glass-ceramicsŚselection of binder
In this paper, four different binders were investigated in the process of aqueous tape casting of cordierite-based glass-ceramics and their effects on the rheological behaviour of the suspensions and on the microstructures of the green tapes were compared. Meanwhile, a good compatibility between the dispersant and binder was found to be a predominant factor to obtain an optimised cordierite glass-ceramic
Sen Mei; Juan Yang; Xin Xu; Sandra Quaresma; Simeon Agathopoulos; Josķ M. F. Ferreira
Thick Co-based coating on cast iron by side laser cladding: Analysis of processing conditions and coating properties
The objective of this work was to create Co-based coatings (compositionally close to Stellite 6) on compacted graphite and gray cast iron substrates with a high power laser (2ĀkW continuous Nd:YAG) cladding process. The relationships between the relevant laser cladding parameters (i.e. laser beam scanning speed, laser power and powder feeding rate) and the main geometrical characteristics of a single
V. OcelĒk; U. de Oliveira; M. de Boer; J. Th. M. de Hosson
Structurally Based Assessment of the Influence of Fluorides on the Characteristics of Continuous Casting Powder Slags
The use of fluorides in continuous casting powder leads to the desired reduction of melting temperature to less than 1573 K (1300 ░C) as well as to lowering the viscosity below 10 dPas. With an equilateral use of alkalis, the tendency to form volatile fluorine compounds rises. The effect of these components on the structure of the casting slags can be described with the NBO/T-ratio. Should the full effect of fluorides to be used for structural modification of the slags, the other components have to be inhibited by compound formation so as to prevent them from forming gaseous fluoride. If the fluoride content in the continuous casting slag is represented by means of fluorspar, the influence on the NBO/T-ratio can be described with the impact factor 4.0.
Schulz, Tilo; Lychatz, Bernd; Haustein, Nicole; Janke, Dieter
Probabilistic simulation of hydrogen gas porosity formation in A356 base hypoeutectic alloy castings
Microporosity in cast aluminum alloy can be classified as gas porosity and/or shrinkage porosity. In prior research, two dimensional simulation programs employing a probabilistic modeling approach and cellular automaton method were developed to predict microporosity in cast aluminum alloys. In this research the 2D models were statistically compared with experimental data. Additionally, we investigated size and morphology distribution of grains and porosity in A356 alloy castings under variable hydrogen content and alloy treatment condition, i.e. eutectic phase modification and grain refinement. In order to improve the accuracy of the prediction method, new simulation models including a two and half dimensional analysis and a two phase evolution model were developed in the present body of work. The new models were statistically compared with experimental results changing silicon and hydrogen content and alloy treatment conditions. The new simulation technique exhibits improved agreement with experimental data tracking the morphology of gas porosities and the grain size distribution.
Asada, Jo
Siloxane-based biocatalytic films and paints for use as reactive coatings.
We have developed a new methodology for preparing films and paints suitable for use as biocatalytic coatings. The hydrolytic enzymes pronase and alpha-chymotrypsin were immobilized by either sol-gel entrapment or by covalent attachment into a polydimethylsiloxane (PDMS) matrix and cast into thin films or incorporated into an oil-based paint formulation. All of the coatings retained enzymatic activity and adhered to several different materials. The enzymatic films and paints also exhibited higher thermostability than enzyme free in solution or covalently attached to the outer surface of PDMS. A porous membrane based on a PDMS-immobilized enzyme was also prepared by an immersion precipitation process. Protein adsorption measurements showed that the enzyme-containing films and paints adsorbed less protein than enzyme-free controls, and that protein adsorption decreased with increasing proteolytic activity of the coating. These coatings thus provide the means to apply a stable enzymatic surface to a wide range of materials, and may be generally useful as biocatalytic paints and films. PMID:11180067
Kim, Y; Dordick, J; Clark, D
Potentiometric biosensors based on polyaniline semiconductor films
Application of polyaniline (PAn) semiconductor films for potentiometric biosensor development provides certain advantages compared with the known systems. For enzyme immobilisation a pH sensitive matrix was used, which could improve sensor sensitivity. Indeed the limiting response value of the PAn based trypsin electrode in 1 mM buffer was 270 mV. The maximal slope of the calibration curve in semilogarithmic coordinates
Arkady A. Karyakin; Oksana A. Bobrova; Lylia V. Lukachova; Elena E. Karyakina
Preparation and Characterization of Anode-Supported YSZ Thin Film Electrolyte by Co-Tape Casting and Co-Sintering Process
In this study, a co-tape casting and co-sintering process has been developed to prepare yttria-stabilized zirconia (YSZ) electrolyte films supported on Ni-YSZ anode substrates in order to substantially reduce the fabrication cost of solid oxide fuel cells (SOFC). Through proper control of the process, the anode/electrolyte bilayer structures with a size of 7.8cm ū 7.8cm were achieved with good flatness. Scanning electron microscopy (SEM) observation indicated that the YSZ electrolyte film was about 16 ?m in thickness, highly dense, crack free and well-bonded to the anode support. The electrochemical properties of the prepared anode-supported electrolyte film was evaluated in a button cell mode incorporating a (LaSr)MnO3-YSZ composite cathode. With humidified hydrogen as the fuel and stationary air as the oxidant, the cell demonstrated an open-circuit voltage of 1.081 V and a maximum power density of 1.01 W/cm2 at 800░C. The obtained results represent the important progress in the development of anode-supported intermediate temperature SOFC with reduced fabrication cost.
Liu, Q. L.; Fu, C. J.; Chan, S. H.; Pasciak, G.
Complex hemimaxillary rehabilitation with a prefabricated fibula flap and cast-based vacuum-formed surgical template.
This report describes a complex, surgical, and prosthodontic hemimaxillary rehabilitation with a prefabricated vascularized free fibula graft. The treatment was based on 3-dimensional skull and fibula models but avoided software-based virtual planning of the reconstructive procedure or the implant positions. Cast-based surgical guides were used for implant placement during prefabrication of the fibula graft and for the positioning of the prefabricated graft in the maxilla during the reconstructive procedure. This procedure allowed the definitive prosthesis to be attached to the implants of the reconstructed maxilla during the inpatient period. PMID:24360016
Nkenke, Emeka; Eitner, Stephan
ALEXSYS - A Prototype Knowledge Based Expert System for the Quality Assurance of High Pressure Die Castings
The ALEXSYS System is aimed to be used as an industrial tool for the identification, assessment and correction of defects in the aluminium high pressure die casting industry. ALEXSYS consists of three modules: the Diagnostic Module, the Machine Parameters Module and the Design Module. The expert system is tested within a real industrial environment, where a robotic cell fully equipped
C. A. G. Webster; M. Weller; M. M. Sfantsikopoulos; V. D. Tsoukalas
Assessing the Robustness of Chemical Prioritizations Based on ToxCast Chemical Profiling
A central goal of the U.S. EPA?s ToxCast? program is to provide empirical, scientific evidence to aid in prioritizing the toxicity testing of thousands of chemicals. The agency has developed a prioritization approach, the Toxicological Prioritization Index (ToxPi?), that calculat...
Microstructure-based multistage fatigue modeling of a cast AE44 magnesium alloy
The multistage fatigue model developed by McDowell et al. was modified to study the fatigue life of a magnesium alloy AE44 for automobile applications. The fractographic examination indicated three distinct stages of fatigue damage in the high cycle fatigue loading regime: crack incubation, microstructurally small crack growth, and long crack growth. Cracks incubated almost exclusively at the cast pores that
Y. Xue; M. F. Horstemeyer; D. L. McDowell; H. El Kadiri; J. Fan
Graphene oxide-based waveguide polariser: From thin film to quasi-bulk.
We have demonstrated a broadband waveguide polariser with high extinction ratio on a polymer optical waveguide coated with graphene oxide via the drop-casting method. The highest extinction ratio of nearly 40 dB is measured at 1590 nm, with a variation of 4.5 dB across a wavelength range from 1530 nm to 1630 nm, a ratio that is (to our knowledge) the highest reported for graphene-based waveguide polarisers to date. This result is achieved with a graphene oxide coating length along the propagation direction of only 1.3 mm and a bulk film thickness of 2.0 Ąm. The underlying principles of the strongly polarisation dependent propagation loss demonstrated have been studied and are attributed to the anisotropic complex dielectric function of graphene oxide bulk film. PMID:24921807
Lim, W H; Yap, Y K; Chong, W Y; Pua, C H; Huang, N M; De La Rue, R M; Ahmad, H
Clean Metal Casting
The objective of this project is to develop a technology for clean metal processing that is capable of consistently providing a metal cleanliness level that is fit for a given application. The program has five tasks: Development of melt cleanliness assessment technology, development of melt contamination avoidance technology, development of high temperature phase separation technology, establishment of a correlation between the level of melt cleanliness and as cast mechanical properties, and transfer of technology to the industrial sector. Within the context of the first task, WPI has developed a standardized Reduced Pressure Test that has been endorsed by AFS as a recommended practice. In addition, within the context of task1, WPI has developed a melt cleanliness sensor based on the principles of electromagnetic separation. An industrial partner is commercializing the sensor. Within the context of the second task, WPI has developed environmentally friendly fluxes that do not contain fluorine. Within the context of the third task, WPI modeled the process of rotary degassing and verified the model predictions with experimental data. This model may be used to optimize the performance of industrial rotary degassers. Within the context of the fourth task, WPI has correlated the level of melt cleanliness at various foundries, including a sand casting foundry, a permanent mold casting foundry, and a die casting foundry, to the casting process and the resultant mechanical properties. This is useful in tailoring the melt cleansing operations at foundries to the particular casting process and the desired properties of cast components.
Makhlouf M. Makhlouf; Diran Apelian
Use of gamma-irradiation technology in the manufacture of biopolymer-based packaging films for shelf-stable foods
Gamma irradiation is an alternative method for the manufacture of sterilized packaging with increased storage stability and microbiological safety. Biopolymer-based packaging films are a potential solution to many environmental problems that have emerged from the production and accumulation of significant amounts of synthetic polymeric waste. This work was undertaken to verify the effectiveness of low-dose gamma-irradiation in obtaining biopolymer-based packaging films for shelf-stable foods. PHB polyester poly(3-hydroxybutyrate) is an interesting biodegradable polymer that has been intensely investigated as cast and sheet films, with applications in the food industry and medicine. The films obtained are, however, typically brittle, and many scientists have attempted to reduce this brittleness by blending PHB with other polymers. In the present work, PHB was blended with PEG (polyethyleneglycol) to obtain films by the casting method that were then irradiated at a dose rate of 5.72 kGy/h with a 60Co source. Samples were melted at 200 ░C and quenched to 0 ░C in order to evaluate film crystallinity levels by differential scanning calorimetry (DSC). DSC analyses were performed with the samples (10 mg) under N2 atmosphere, heating from -50 to 200 ░C (10 ░C min-1), cooling from 200 to -50 ░C (10 ░C min-1); and heating from -50 to 200 ░C (10 ░C min-1). The thermal and mechanical resistances of the films after irradiation at low doses (5, 10, 20 kGy) are discussed. Water vapour transmission decreased with increasing irradiation dose, indicating that the films' performance as water vapour barrier had improved. Critical loss of the mechanical properties was observed at 40 kGy.
Parra, Duclerc F.; Rodrigues, Juliana A. F. R.; LugŃo, Ademar B.
Preparation and characterization of bionanocomposite films based on potato starch/halloysite nanoclay.
In this research casting method was used to prepare potato starch based bio-nanocomposite films with halloysite nanoclay as the reinforcing materials. The composition included potato starch with 40% (w/w) of a mixture of sorbitol/glycerol (weight ratio of 3 to 1as plasticizer) with nanoclay (0-5% w/w). The films were dried under controlled conditions. Physicochemical properties such as solubility in water, water absorption capacity (WAC), water vapour permeability (WVP), oxygen permeability, and mechanical properties of the films were measured. Results showed that by increasing the concentration of nanoclay, mechanical properties of films were improved. Tensile strength was increased from 7.33 to 9.82MPa, and elongation at break decreased from 68.0 to 44.0%. Solubility in water decreased from 35 to 23%, and heat seal strength increased from 375 to 580N/m. Also incorporation of clay nanoparticles in the structure of biopolymer decreased permeability of the gaseous molecules. In summary, addition of halloysite nanoclay, improve the barrier and mechanical properties of potato starch films and this bionanocomposites have high potential to be used for food packaging purposes. PMID:24747380
Sadegh-Hassani, Fatemeh; Mohammadi Nafchi, Abdorreza
Polyelectrolyte films based on chitosan/olive oil and reinforced with cellulose nanocrystals.
Composite films designed as potentially edible food packaging were prepared by casting film-forming emulsions based on chitosan/glycerol/olive oil containing dispersed cellulose nanocrystals (CNs). The combined use of cellulose nanoparticles and olive oil proved to be an efficient method to reduce the inherently high water vapor permeability of plasticized chitosan films, improving at the same time their tensile behavior. At the same time, it was found that the water solubility slightly decreased as the cellulose content increased, and further decreased with oil addition. Unexpectedly, opacity decreased as cellulose content increased, which balanced the reduced transparency due to lipid addition. Contact angle decreased with CN addition, but increased when olive oil was incorporated. Results from dynamic mechanical tests revealed that all films present two main relaxations that could be ascribed to the glycerol- and chitosan-rich phases, respectively. The response of plasticized chitosan-nanocellulose films (without lipid addition) was also investigated, in order to facilitate the understanding of the effect of both additives. PMID:24299870
Pereda, Mariana; Dufresne, Alain; Aranguren, Mirta I; Marcovich, Norma E
The use of fluidized sand bed as an innovative technique for heat treating aluminum based castings
The current study was carried out to arrive at a better understanding of the influences of the fluidized sand bed heat treatment on the tensile properties and quality indices of A356.2 and B319.2 casting alloys. For the purposes of validating the use of fluidized sand bed furnaces in industrial applications for heat treatment of 356 and 319 castings, the tensile properties and the quality indices of these alloys were correlated with the most common metallurgical parameters, such as strontium modification, grain refining, solutionizing time, aging parameters and quenching media. Traditional heat treatment technology, employing circulating air convection furnaces, was used to establish a relevant comparison with fluidized sand beds for the heat treatment of the alloys investigated, employing T6 continuous aging cycles or multi-temperature aging cycles. Quality charts were used to predict and/or select the best heat treatment conditions and techniques to be applied in industry in order to obtain the optimum properties required for particular engineering applications. The results revealed that the strength values achieved in T6-tempered 319 and 356 alloys are more responsive to fluidized bed (FB) heat treatment than to conventional convection furnace (CF) treatment for solution treatment times of up to 8 hours. Beyond this solution time, no noticeable difference in properties is observed with the two techniques. A significant increase in strength is observed in the FB heat-treated samples after short aging times of 0.5 and 1 hour, the trend continuing up to 5 hours. The 319 alloys show signs of overaging after 8 hours of aging using a conventional furnace, whereas with a fluidized bed, overaging occurs after 12 hours. Analysis of the tensile properties in terms of quality index charts showed that both modified and non-modified 319 and 356 alloys display the same, or better, quality, after only a 2-hr treatment in an FB compared to 10 hours when using a CF. The quality values of the 356 alloys are more responsive to the FB technique than 319 alloys through long aging times of up to 5 hours. The 319 alloys heat-treated in an FB, however, show better quality values after 0.5 hour of aging and for solution treatment times of up to 5 hours than those treated using a CF. With regard to the quality charts of 319 alloys, heat-treated samples show that increasing the aging time up to peak-strength, i.e. 8 and 12 hours in a CF and an FB, respectively, results in increasing in the alloy strength with a decrease in the quality values, for each of the solution heat treatment times used. The statistical analysis of the results reveals that modification and heating rate of the heat treatment technique have the greatest positive effects on the quality values of the 356 alloys. The use of a fluidized sand bed for the direct quenching-aging treatment of A356.2 and B319.2 casting alloys yields greater UTS and YS values compared to conventional furnace quenched alloys. The strength values of T6 tempered A356 and B319 alloys are greater when quenched in water compared to those quenched in an FB or CF. For the same aging conditions (170░C/4h), the fluidized bed quenched-aged 319 and 356 alloys show nearly the same or better strength values than those quenched in water and then aged in a CF or an FB. Based on the quality charts developed for alloys subjected to different quenching media, higher quality index values are obtained by water-quenched T6-tempered A356 alloys, and conventional furnace quenched-aged T6-tempered B319 alloys, respectively. The modification factor has the most significant effect on the quality results of the alloys investigated, for all heat treatment cycles, as compared to other metallurgical parameters. The results of alloys subjected to multi-temperature aging cycles reveal that the strength results obtained after the T6 continuous aging treatment of A356 alloys are not improved by means of multi-temperature aging cycles, indicating therefore that the optimum properties are obtained using a T6 aging treatment. The optimu
Ragab, Khaled
Fabrication of x-ray absorption gratings via micro-casting for grating-based phase contrast imaging
Grating-based x-ray differential phase contrast (DPC) imaging has shown huge potential. For broad applications, it is essential that the key components are low-cost, especially the absorption gratings. We therefore proposed and developed a micro-casting process for fabricating x-ray absorption gratings with bismuth. This process is feasible for mass production at low cost, with a large format, and a high aspect ratio. To develop this kind of absorption grating, an array with deep trenches was fabricated by photo-assisted electrochemical etching in a silicon wafer. The trenches were then filled with bubble-free, molten bismuth via capillary action and surface tension. Bismuth was attractive as a filling material because of its great mass absorption coefficient, low cost and broad environmental compatibility. Furthermore, our micro-casting process provided bismuth absorption gratings with a clean surface and no need for post treatment. To test their performance in x-ray DPC imaging, two bismuth absorption gratings, one as a periodic source and another as the analyzer, were used with periods of 42 and 3 Ąm and depths of 110 and 150 Ąm, respectively. The acquired phase-contrast images demonstrated that the micro-casting process produces qualified gratings for x-ray DPC imaging.
Lei, Yaohu; Du, Yang; Li, Ji; Zhao, Zhigang; Liu, Xin; Guo, Jinchuan; Niu, Hanben
Creep deformation mechanisms in high-pressure die-cast magnesium-aluminum-base alloys
Creep of die-cast Mg alloys is described as an integral part of their plastic deformation behavior in terms of stress-strain-rate-strain\\u000a relations. Creep tests yield information on yield stress, work hardening, maximum deformation resistance (minimum creep rate),\\u000a and work softening. Testing in compression avoids influences by fracture. Data on the alloy AJ52 (5Al, 2Sr) in the temperature\\u000a range between 135 ░C
W. Blum; Y. J. Li; X. H. Zeng; P. Zhang; B. von Gro▀mann; C. Haberling
Spray cast Al-Si base alloys for stiffness and fatigue strength requirements
SUMMARY Hypereutectic AlSiFe spray-cast alloys exhibit properties similar to those of metal-matrix composite (MMC's) : high Young's modulus and a low coefficient of thermal expansion. These physical properties can be adjusted by changing the Si content of the alloy. The refinement of the microstructure is produced by formation of a large amount of nuclei in the spray. Consolidation done by
Starch-based Antimicrobial Films Incorporated with Lauric Acid and Chitosan
Antimicrobial (AM) packaging is one of the most promising active packaging systems. Starch-based film is considered an economical material for antimicrobial packaging. This study aimed at the development of food packaging based on wheat starch incorporated with lauric acid and chitosan as antimicrobial agents. The purpose is to restrain or inhibit the growth of spoilage and/or pathogenic microorganisms that are contaminating foods. The antimicrobial effect was tested on B. substilis and E. coli. Inhibition of bacterial growth was examined using two methods, i.e. zone of inhibition test on solid media and liquid culture test (optical density measurements). The control and AM films (incorporated with chitosan and lauric acid) were produced by casting method. From the observations, AM films exhibited inhibitory zones. Interestingly, a wide clear zone on solid media was observed for B. substilis growth inhibition whereas inhibition for E. coli was not as effective as B. substilis. From the liquid culture test, the AM films clearly demonstrated a better inhibition against B. substilis than E. coli.
Salleh, E.; Muhamad, I. I.
A projection display based on a bacteriorhodopsin thin film
A novel laser-projection display utilizing an optically addressed spatial light modulator (OASLM) is presented. The OASLM is based on the photochro- mic protein, bacteriorhodopsin (BR), immobilized in a thin gelatin film (80 mm). The photochromism of this material facilitates the light-induced switching of the optical absorption properties of the film. In this manner, the film can dynamically be switched between
Lars Lindvold; H. Lausen
Polyox and carrageenan based composite film dressing containing anti-microbial and anti-inflammatory drugs for effective wound healing.
Polyethylene oxide (Polyox) and carrageenan based solvent cast films have been formulated as dressings for drug delivery to wounds. Films plasticised with glycerol were loaded with streptomycin (30%, w/w) and diclofenac (10%, w/w) for enhanced healing effects in chronic wounds. Blank and drug loaded films were characterised by texture analysis (for mechanical and mucoadhesive properties), scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and Fourier transform infrared spectroscopy. In addition, swelling, in vitro drug release and antibacterial studies were conducted to further characterise the films. Both blank and drug loaded films showed a smooth, homogeneous surface morphology, excellent transparency, high elasticity and acceptable tensile (mechanical) properties. The drug loaded films showed a high capacity to absorb simulated wound fluid and significant mucoadhesion force which is expected to allow effective adherence to and protection of the wound. The films showed controlled release of both streptomycin and diclofenac for 72 h. These drug loaded films produced higher zones of inhibition against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli compared to the individual drugs zones of inhibition. Incorporation of streptomycin can prevent and treat chronic wound infections whereas diclofenac can target the inflammatory phase of wound healing to relieve pain and swelling. PMID:23228898
Boateng, Joshua S; Pawar, Harshavardhan V; Tetteh, John
Optimization of excess Bi doping to enhance ferroic orders of spin casted BiFeO3 thin film
Multiferroic Bismuth Ferrite (BiFeO3) thin films with varying excess bismuth (Bi) concentration were grown by chemical solution deposition technique. Room temperature multiferroic properties (ferromagnetism, ferroelectricity, and piezoelectricity) of the deposited BiFeO3 thin films have been studied. High resolution X-ray diffraction and Raman spectroscopy studies reveal that the dominant phases formed in the prepared samples change continuously from a mixture of BiFeO3 and Fe2O3 to pure BiFeO3 phase and, subsequently, to a mixture of BiFeO3 and Bi2O3 with increase in the concentration of excess Bi from 0% to 15%. BiFeO3 thin films having low content (0% and 2%) of excess Bi showed the traces of ferromagnetic phase (?-Fe2O3). Deterioration in ferroic properties of BiFeO3 thin films is also observed when prepared with higher content (15%) of excess Bi. Single-phased BiFeO3 thin film prepared with 5% excess Bi concentration exhibited the soft ferromagnetic hysteresis loops and ferroelectric characteristics with remnant polarization 4.2 ?C/cm2 and saturation magnetization 11.66 emu/g. The switching of fine spontaneous domains with applied dc bias has been observed using piezoresponse force microscopy in BiFeO3 thin films having 5% excess Bi. The results are important to identify optimum excess Bi concentration needed for the formation of single phase BiFeO3 thin films exhibiting the improved multiferroic properties.
Gupta, Surbhi; Tomar, Monika; Gupta, Vinay; James, A. R.; Pal, Madhuparna; Guo, Ruyan; Bhalla, Amar
Creep-rupture behavior of a developmental cast-iron-base alloy for use up to 800 deg C
A promising iron-base cast alloy is being developed as part of the DOE/NASA Stirling Engine Systems Project under contract DEN 3-282 with the United Technologies Research Center. This report presents the results of a study at the Lewis Research Center of the alloy's creep-rupture properties. The alloy was tested under a variety of conditions and was found to exhibit the normal 3-stage creep response. The alloy compared favorably with others being used or under consideration for the automotive Stirling engine cylinder/regenerator housing.
Titran, Robert H.; Scheuermann, Coulson M.
A Winning Cast
Howmet Research Corporation was the first to commercialize an innovative cast metal technology developed at Auburn University, Auburn, Alabama. With funding assistance from NASA's Marshall Space Flight Center, Auburn University's Solidification Design Center (a NASA Commercial Space Center), developed accurate nickel-based superalloy data for casting molten metals. Through a contract agreement, Howmet used the data to develop computer model predictions of molten metals and molding materials in cast metal manufacturing. Howmet Metal Mold (HMM), part of Howmet Corporation Specialty Products, of Whitehall, Michigan, utilizes metal molds to manufacture net shape castings in various alloys and amorphous metal (metallic glass). By implementing the thermophysical property data from by Auburn researchers, Howmet employs its newly developed computer model predictions to offer customers high-quality, low-cost, products with significantly improved mechanical properties. Components fabricated with this new process replace components originally made from forgings or billet. Compared with products manufactured through traditional casting methods, Howmet's computer-modeled castings come out on top.
Automated flaw detection in aluminum castings based on the tracking of potential defects in a radioscopic image sequence
Presents a method for inspecting aluminum castings automatically from a sequence of radioscopic images taken at different positions of the casting. The classic image-processing methods for flaw detection of aluminum castings use a bank of filters to generate an error-free reference image. This reference image is compared with the real radioscopic image, and flaws are detected at the pixels where
Domingo Mery; Dieter Filbert
High-dose film dosimeters based on bromophenol blue or xylenol orange dyed polyvinyl alcohol
Dyed poly(vinyl alcohol) (PVA) films, prepared by a simple technique of casting acqueous solutions of PVA containing bromophenol blue (BPB) or xylenol orange (XYO) on a horizontal glass plate, are useful as routine high-dose dosimeters. These flexible plastic film dosimeters are bleached when exposed to ?-ray photons. Absorbed doses should not exceed 20 kGy for BPB\\/PVA film and 90 kGy
A. A. Abdel-Fattah; S. Ebraheem; M. El-Kelany; F. Abdel-Rehim
Herein, time-dependent scanning Kelvin probe microscopy of solution processed organic thin film transistors (OTFTs) reveals a correlation between film microstructure and OTFT device performance with the location of trapped charge within the device channel. The accumulation of the observed trapped charge is concurrent with the decrease in I{sub SD} during operation (V{sub G}=-40 V, V{sub SD}= -10 V). We discuss the charge trapping and dissipation dynamics as they relate to the film structure and show that application of light quickly dissipates the observed trapped charge.
Teague, L.; Moth, M.; Anthony, J.
Influence of film structure and light on charge trapping and dissipation dynamics in spun-cast organic thin-film transistors measured by scanning Kelvin probe microscopy
Herein, time-dependent scanning Kelvin probe microscopy of solution processed organic thin film transistors (OTFTs) reveals a correlation between film microstructure and OTFT device performance with the location of trapped charge within the device channel. The accumulation of the observed trapped charge is concurrent with the decrease in ISD during operation (VG = -40 V, VSD = -10 V). We discuss the charge trapping and dissipation dynamics as they relate to the film structure and show that application of light quickly dissipates the observed trapped charge.
Teague, L. C.; Loth, M. A.; Anthony, J. E.
Polyvinyl acetate-based film coatings.
Polyvinyl acetate-based colloidal aqueous polymer dispersion Kollicoat(«) SR 30 D results in coatings characterized by moderate swelling behaviour, lipophilicity, pH-independent permeability for actives and high flexibility to withstand mechanical stress and is therefore used for controlled release coating. The colloidal aqueous polymer dispersion of Kollicoat(«) SR 30 D can be easily processed due to an optimal low minimum film forming temperature (MFT) of 18 ░C without plasticizer addition and a thermal after-treatment (curing) of coated pellets. The drug release from Kollicoat(«) SR 30 D coated pellets was almost pH independent. Drug release could be easily adjusted by coating level or addition of soluble pore forming polymers. Physically stable Kollicoat(«) SR 30 D dispersions were obtained with the water-soluble polymers Kollidon(«) 30 and Kollicoat(«) IR up to 50% w/w. The addition of only 10% w/w triethyl citrate as plasticizer improved the flexibility of the films significantly and allowed compaction of the pellets. The drug release was almost independent of the compression force and the pellet content of the tablets. The inclusion of various tableting excipients slightly affected the drug release, primarily because of a different disintegration rate of the tablets. A combination of Kollicoat(«) SR 30 D and Kollicoat(«) IR with higher coating levels>10 mg/cm(2) is a relatively new alternative to OROS system which does not require drilling. PMID:24076229
Kolter, K; Dashevsky, A; Irfan, Muhamad; Bodmeier, R
Special Casting Techniques (Chapter 9).
Special casting techniques are progressive production methods. These casting techniques include the following: metal mold casting (chill mold casting), shell-mold casting, investment casting, centrifugal casting, and others. Each of these methods of casti...
N. P. Dubinin
Creep of die-cast Mg alloys is described as an integral part of their plastic deformation behavior in terms of stress-strain-rate-strain relations. Creep tests yield information on yield stress, work hardening, maximum deformation resistance (minimum creep rate), and work softening. Testing in compression avoids influences by fracture. Data on the alloy AJ52 (5Al, 2Sr) in the temperature range between 135 ░C and 190 ░C are presented and compared to those for AZ91 and AS21. Die-cast Mg-Al alloys consist of fine grains with a grain boundary region containing intermetallic precipitates. Transmission electron microscopic observations indicate that basal glide is the dominant mechanism of deformation being supplemented by nonbasal glide and twinning to maintain compatiblity between the grains. The deformation resistance can be modeled with a composite approach assuming that the grain boundary region is relatively hard due to precipitation of intermetallic phases. The differences in long-term creep resistance at low stress are explained in terms of different strength and stability of precipitates in the different alloys.
Blum, W.; Li, Y. J.; Zeng, X. H.; Zhang, P.; von Gro▀mann, B.; Haberling, C.
Precipitation of ?-Al5FeSi Phase Platelets in Al-Si Based Casting Alloys
The aim of the present work has been to investigate the factors affecting the precipitation of the ?-Al5FeSi iron intermetallic phase of directionally solidified A356- and 319-type alloys as a function of the iron content, a Sr addition of ~250 ppm, and superheating or cooling rates. The iron levels selected varied from 0.12 to 0.8 wt pct and cover the range of Fe levels in commercial casting alloys. The use of an end-chill mold provided different cooling rates along the height of the same casting, with dendritic arm spacing values that varied from ~15 to 85 ?m, corresponding to levels of 5, 10, 30, 50, and 100 mm above the chill end. The microstructure and phase identification were monitored using optical microscopy, scanning electron microscopy (SEM), thermal analysis, and electron probe microanalysis (EPMA) techniques. An image analyzer was used in conjunction with the optical microscope for quantification purposes. The results showed that, for the range of cooling rates covered in the present study, the highest cooling rate (at a 5-mm distance from the chill) is the more significant parameter in controlling the size and distribution of the ?-Al2FeSi intermetallic phase in the nonmodified 319 and 356 alloys. The addition of strontium leads to fragmentation of coeutectic or posteutectic ? platelets. This effect diminishes with an increase in the iron concentration, and further strontium addition leads to the precipitation of Al2Si2Sr phase particles, instead.
Liu, L.; Mohamed, A. M. A.; Samuel, A. M.; Samuel, F. H.; Doty, H. W.; Valtierra, S.
Instant Casting Movie Theater: The Future Cast System
We have developed a visual entertainment system called ōFuture Castö which enables anyone to easily participate in a pre-recorded or pre-created film as an instant CG movie star. This system provides audiences with the amazing opportunity to join the cast of a movie in real-time. The Future Cast System can automatically perform all the processes required to make this possible, from capturing participants' facial characteristics to rendering them into the movie. Our system can also be applied to any movie created using the same production process. We conducted our first experimental trial demonstration of the Future Cast System at the Mitsui-Toshiba pavilion at the 2005 World Exposition in Aichi Japan.
Maejima, Akinobu; Wemler, Shuhei; Machida, Tamotsu; Takebayashi, Masao; Morishima, Shigeo
Properties of MEH-PPV films prepared by slow solvent evaporation
Because of various macromolecules conformations, solution-casted conjugated polymers films demonstrate a wide spectrum of intermolecular interactions which strongly influence essential electronic properties. Using poly[2-methoxy-5-(2?-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and different solvents, we studied polymer films prepared by dip-coating, spin\\/drop-casting and by a method based on slow solvent evaporation (SSE) from solution. The SSE films exhibit some redder photoluminescence (PL) and optical absorption
S. A. Arnautov; E. M. Nechvolodova; A. A. Bakulin; S. G. Elizarov; A. N. Khodarev; D. S. Martyanov; D. Yu. Paraschuk
MEMS-based thick film PZT vibrational energy harvester
We present a MEMS-based unimorph silicon\\/PZT thick film vibrational energy harvester with an integrated proof mass. We have developed a process that allows fabrication of high performance silicon based energy harvesters with a yield higher than 90%. The process comprises a KOH etch using a mechanical front side protection of an SOI wafer with screen printed PZT thick film. The
A. Lei; R. Xu; A. Thyssen; A. C. Stoot; T. L. Christiansen; K. Hansen; R. Lou-Moller; E. V. Thomsen; K. Birkelund
The high cycle fatigue (HCF) properties of two cast nickel base-superalloys, IN 738 LC and IN 939, were investigated using both fracture mechanics samples and smooth specimens. The crack propagation behavior was studied in terms of linear fracture mechanics at RT and at 850 ░C. In addition to the influence of temperature, the influences of frequency, mean stress, and environment (vacuum, air, sulfidizing atmosphere) were studied. At 850 ░C, the fatigue thresholds were found to be higher in air than in vacuum. This could be explained by crack branching. The high scatter of fatigue crack propagation rates could be related also to this phenomenon. The S/N curves at 850 ░C can be predicted treating crack growth from casting pores as the predominant failure mechanism. At RT the same method is not as successful. The reason for this may be that crack growth laws measured on long, branched cracks are not applicable to short, unbranched cracks. At RT, no significant influence of frequency on S/N-curves and fatigue crack growth rates was observed for frequencies up to 20 kHz.
Hoffelner, W.
Cooling Process and Cast Structure of Zr-Al-Ni-Cu-Based Bulk Metallic Glasses Produced in Various Atmospheres
Cooling process in the production of Zr65Al7.5Ni10Cu17.5-based bulk metallic glasses (BMGs) was investigated in various chamber atmospheres in Cu mold casting. Two different cooling modes, consisting of the direct heat transfer between the melt and Cu mold in the high temperature and indirect transfer via cavity in the low-temperature regions, are suggested. In the later case, the cooling effect should depend on the chamber atmosphere, which results in the formation of glassy structure with large relaxation enthalpy casting under the ambient Ar and He atmospheres due to a good thermal conductivity. The less relaxed BMGs produced by an improved cooling effect are also expected to contain a large amount of free volume for significant deformability. Actually, it is clarified that the compressive plastic deformation is improved with an increase of the relaxation enthalpy. The present study indicates a necessity of development of the glassy structure, i.e., relaxation state, and provides a new technique of the formation of less relaxed glassy structure for the improvement of plasticity in BMGs.
Saida, J.; Setyawan, A. D.; Kato, H.; Inoue, A.
Cells studies on PEO\\/PEG\\/NaClO 3 thin-film electrolyte system based on composite V 2 O 5 electrode
The thin-film solid polymer electrolyte based on polyethylene oxide (PEO) with sodium chlorite (NaClO3) has been prepared by a solution-cast technique. The electrolyte was characterized by X-ray diffraction (XRD), infrared (IR),\\u000a cyclic voltammetry, alternating current conductivity, and WagnerÆs polarization studies. The complexation of NaClO3 with PEO was confirmed through the XRD and IR studies. The transference number measurement has shown
R. Chandrasekaran; R. Sathiyamoorthi; S. Selladurai
Bioinspired material based on femtosecond laser machining of cast sheet micromolding as a pattern transfer process.
We present herein a simple, fast, and easy-to-use process to replicate poly(methyl methacrylate) (PMMA) plates generating surface effects. First, a femtosecond laser has been used to fabricate, with sufficient accuracy, a periodic pattern on a glass plate at the microscale. This glass plate, used as a master, can be structured on a large distance with a good control of its roughness. Then, the polymer plates were obtained by bulk polymerization without any solvents with a good replication from the cast sheet process, which has been industrially performed for years. Thus, the modification of this process, environmentally friendly, lets us foresee new applications for commodity polymers by introducing visual iridescent properties and hydrophobicity exaltation. PMID:21309506
Sarrat, B; Pķcheyran, C; Bourrigaud, S; Billon, L
Gasochromic tungsten oxide-based film structures
Tungsten oxide thin films were produced by reactive sputter deposition which is an advantageous method because of the opportunity to influence the properties of the films by several parameters. This work focuses on the influence of the oxygen content during the sputtering process and on mixed tungsten and molybdenum oxide films. The oxygen content has a great influence on the film growth velocity and leads to significant differences in crystal symmetry as a function of oxygen partial pressure. Additionally an influence of oxygen content on the gasochromic behaviour was observed. The mixed tungsten molybdenum oxide thin films show no change in the velocity of the gasochromic colouration but the fact that the coloured films show high absorption all over the visible region of the optical spectrum is a significant advantage.
Nowoczin, J.; Shanak, H.; Ziebert, C.; Schmitt, H.; Ehses, K. H.
Morphology-dependent exciton emission and energy transfer in fluorene-polymer-related fluorescent and phosphorescent composite films spin cast from a mixture of two dissimilar organic solvents
We report morphology-dependent exciton emission and energy transfer in fluorene-conjugated polymer poly(9,9-dioctylfluorenyl-2,7-diyl)-related fluorescent and phosphorescent materials by using a mixture of two dissimilar organic solvents for spin-cast film formation. The electron microscopic characterizations revealed that the mixture of a high-boiling-point orthodichlorobenzene and a low-boiling-point chloroform results in a formation of both crystalline and amorphous morphological structures in fluorene-conjugated polymers. The UV-visible absorption and photoluminescence studies indicated that the low-energy crystalline phase domains, randomly distributed in the continuous high-energy amorphous phase, function as potential quantum wells. As a consequence, the mixture of two dissimilar organic solvents significantly affects the exciton emission from fluorescent fluorene-conjugated polymer and the energy transfer in phosphorescent composite of fluorene polymer and iridium complex molecules, presenting a pathway to control fluorescent and phosphorescent processes in polymer light-emitting materials.
Wu, Yue [University of Tennessee, Knoxville (UTK); Hu, Bin [University of Tennessee, Knoxville (UTK); Howe, Jane Y [ORNL
Carbon nanotube based nanostructured thin films: preparation and application
Hybrid thin films of multi-walled carbon nanotube (MWCNT) and titania were fabricated on quartz slides by alternatively depositing MWCNT and titanium(IV) bis(ammonium lactato) dihydroxide (TALH) via a solution based layer-by-layer (LbL) self-assembly method followed by calcination to convert TALH to crystalline titania. The multilayer film build-up was monitored by UV-vis spectroscopy which indicated the linear growth of the film with the bilayer number. XRD confirmed the formation of anantase titania after heat treatment. The photocatalytic property of the hybrid thin film was evaluated by its capacity to degrade rhodamine B under the UV illumination. Compared with pure TiO2 film, experiments showed that the MWCNT/TiO2 hybrid film had a much higher photocatalytic activity under the same conditions. The first order rate constant of photocatalysis of 30 bilayers of hybrid film was approximately 8-fold higher than that of 30 bilayers of pure TiO2 film. In addition, the degradation efficiency of MWCNT/TiO2 hybrid thin film increased with its thickness while pure titania film remained unchanged. A 30 bilayers hybrid thin film that contains about 0.2 mg MWCNT/TiO2 catalyst was capable of completely degrading 10 mL of 2 mg/L Rh B solution within 5 hours. The results also indicated that the hybrid catalyst could be reused for several cycles.
Fu, Li; Yu, Aimin
Microstructure of a Base Metal Thick Film System.
A base metal thick film conductor system using glass frits with base metal oxide additions was investigated as metallization for hybrid microcircuits. Application of previous work on wetting and chemical bonding was made to this system. The observation of...
D. E. Mentley
Interferometric measurement method of thin film thickness based on FFT
The kernel of modern interferometry is to obtain necessary surface shape and parameter by processing interferogram with reasonable algorithm. The paper studies the basic principle of interferometry involving 2-D FFT, proposes a new method for measuring thin film thickness based on FFT: by CCD receiving and acquired card collecting with the help of Twyman-Green interferometer, can a fringe interferogram of the measured thin film be obtained. Based on the interferogram processing knowledge, an algorithm processing software/program can be prepared to realize identification of the edge films, regional extension, filtering, unwrapping the wrapped phase etc. And in this way can the distribution of film information-coated surface be obtained and the thickness of thin film samples automatically measured. The findings indicate the PV value and RMS value of the measured film samples are 0.256 ? and 0.068 ? respectively and prove the new method has high precision.
Shuai, Gaolong; Su, Junhong; Yang, Lihong; Xu, Junqi
Development of Stronger and More Reliable Cast Austenitic Stainless Steels (H-Series) Based on Scientific Design Methodology
The goal of this program was to increase the high-temperature strength of the H-Series of cast austenitic stainless steels by 50% and upper use temperature by 86 to 140 F (30 to 60 C). Meeting this goal is expected to result in energy savings of 38 trillion Btu/year by 2020 and energy cost savings of $185 million/year. The higher strength H-Series of cast stainless steels (HK and HP type) have applications for the production of ethylene in the chemical industry, for radiant burner tubes and transfer rolls for secondary processing of steel in the steel industry, and for many applications in the heat-treating industry. The project was led by Duraloy Technologies, Inc. with research participation by the Oak Ridge National Laboratory (ORNL) and industrial participation by a diverse group of companies. Energy Industries of Ohio (EIO) was also a partner in this project. Each team partner had well-defined roles. Duraloy Technologies led the team by identifying the base alloys that were to be improved from this research. Duraloy Technologies also provided an extensive creep data base on current alloys, provided creep-tested specimens of certain commercial alloys, and carried out centrifugal casting and component fabrication of newly designed alloys. Nucor Steel was the first partner company that installed the radiant burner tube assembly in their heat-treating furnace. Other steel companies participated in project review meetings and are currently working with Duraloy Technologies to obtain components of the new alloys. EIO is promoting the enhanced performance of the newly designed alloys to Ohio-based companies. The Timken Company is one of the Ohio companies being promoted by EIO. The project management and coordination plan is shown in Fig. 1.1. A related project at University of Texas-Arlington (UT-A) is described in Development of Semi-Stochastic Algorithm for Optimizing Alloy Composition of High-Temperature Austenitic Stainless Steels (H-Series) for Desired Mechanical and Corrosion Properties (ORNL/TM-2005/81/R1). The final report on another related project at the University of Tennessee by George Pharr, Easo George, and Michael Santella has been published as Development of Combinatorial Methods for Alloy Design and Optimization (ORNL/TM-2005-133). The goal of the project was to increase the high-temperature strength by 50% and upper use temperature by 86 to 140 F (30 to 60 C) of H-Series of cast austenitic stainless steels. Meeting such a goal is expected to result in energy savings of 38 trillion Btu/year by 2020 and energy cost savings of $185 million/year. The goal of the project was achieved by using the alloy design methods developed at ORNL, based on precise microcharacterization and identification of critical microstructure/properties relationships and combining them with the modern computational science-based tools that calculate phases, phase fractions, and phase compositions based on alloy compositions. The combined approach of microcharacterization of phases and computational phase prediction would permit rapid improvement of the current alloy composition of an alloy and provide the long-term benefit of customizing alloys within grades for specific applications. The project was appropriate for the domestic industry because the current H-Series alloys have reached their limits both in high-temperature-strength properties and in upper use temperature. The desire of Duraloy's industrial customers to improve process efficiency, while reducing cost, requires that the current alloys be taken to the next level of strength and that the upper use temperature limit be increased. This project addressed a specific topic from the subject call: to develop materials for manufacturing processes that will increase high-temperature strength, fatigue resistance, corrosion, and wear resistance. The outcome of the project would benefit manufacturing processes in the chemical, steel, and heat-treating industries.
Muralidharan, G.; Sikka, V.K.; Pankiw, R.I.
Development, processing, and characterization of cellulose nanocrystal neat films
Methods for processing quality cellulose nanocrystal (CNC) suspensions using sulfuric acid hydrolysis of microcrystalline cellulose were developed and optimized. The resulting suspensions were used to develop shear-based methods for casting neat CNC films. These methods were used to produce oriented CNC films from the Purdue-made (long crystals, CNC-L) and FPL-made (short crystals, CNC-S) CNC suspensions. Increased casting shear rate increased
Alexander B. Reising
Development of CZTS-based thin film solar cells
The low cost, environmental harmless Cu2ZnSnS4 (CZTS)-based thin film solar cells are fabricated by using abundant materials. The CZTS film possesses promising characteristic optical properties; band-gap energy of about 1.5ĀeV and large absorption coefficient in the order of 104Ācm?1. All constituents of this CZTS film, which are abundant in the crust of the earth, are non-toxic. Therefore, if we can
Hironori Katagiri; Kazuo Jimbo; Win Shwe Maw; Koichiro Oishi; Makoto Yamazaki; Hideaki Araki; Akiko Takeuchi
New Switchable Mirror Based on Magnesium-Niobium Thin Film
We found that palladium-capped magnesium-niobium alloy thin films show a good optical switching property when they are exposed to a hydrogen-containing atmosphere. A switchable mirror based on a magnesium-niobium thin film was prepared on a glass substrate by cosputtering of Mg and Nb targets. Mg1-xNbx thin films with a 4 nm Pd overlayer can be switched reversibly between shiny mirror
Shanhu Bao; Yasusei Yamada; Kazuki Tajima; Masahisa Okada; Kazuki Yoshimura
Switchable mirrors based on nickel-magnesium films
An electrochromic mirror electrode based on reversible uptake of hydrogen in nickel magnesium alloy films is reported. Thin, magnesium-rich Ni-Mg films prepared on glass substrates by co-sputtering from Ni and Mg targets are mirror-like in appearance and have low visible transmittance. Upon exposure to hydrogen gas or on cathodic polarization in alkaline electrolyte, the films take up hydrogen and become
Thomas J. Richardson; Jonathan L. Slack; Robert D. Armitage; Robert Kostecki; Baker Farangis; Michael D. Rubin
Switchable mirrors based on nickel¢magnesium films
An electrochromic mirror electrode based on reversible uptake of hydrogen in nickel magnesium alloy films is reported. Thin, magnesium-rich Ni¢Mg films prepared on glass substrates by co-sputtering from Ni and Mg targets are mirror-like in appearance and have low visible transmittance. Upon exposure to hydrogen gas or on cathodic polarization in alkaline electrolyte, the films take up hydrogen and become
T. J. Richardson; J. L. Slack; R. D. Armitage; R. Kostecki; B. Farangis; M. D. Rubin
Characteristics of PVdF-HFP\\/TiO 2 composite membrane electrolytes prepared by phase inversion and conventional casting methods
Porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)-based polymer membranes filled with various contents of titania (TiO2) nanocrystalline particles are prepared by phase inversion technique and, along with conventional casting method for comparison. N-methyl-2-pyrrolidone (NMP) as a solvent is used to dissolve the polymer and to make the slurry with TiO2. Cast film is obtained by spreading the slurry and evaporating NMP in a
Kwang Man Kim; Nam-Gyu Park; Kwang Sun Ryu; Soon Ho Chang
Holographic interfermetry based on fulgide film
Holographic interfermetry was realized in a 3-indolyŁ benzylfulgimide\\/ PMMA film by using double exposure method and single exposure method for the first time. The structures of an optical wedge and an optical axicon, the rotation angle of the optical wedge and the movement distance of the optical axicon were successfully measured. It is proved that fulgide films can be used
Ke Ji; Neimule Menke; Baoli Yao; Yingli Wang; Yi Chen
Slip casting under pressure
The addition of a pressure during slip casting increases the rate of material deposition and enables larger pieces to be fabricated. In this study, this process has been further developed using monolithic Al2O3 and Al2O3-SiC composites. Slip casting formulations based on both dispersed and coagulated slurries have been analyzed. Excellent results are achieved using coagulated slurries, with no cracking present after drying. The effect of pressure is to increase the green density with a consequent increase in the fired density. In addition, homogeneous microstructures are achieved in the composite system, despite the large difference in particle size used.
Grazzini, H. H.; Wilkinson, D. S.
Sensitivity of linear CCD array based film scanners used for film dosimetry
Film dosimetry is commonly performed by using linear CCD array transmission optical densitometers. However, these devices suffer from a variation in response along the detector array. If not properly corrected for, this nonuniformity may lead to significant overestimations of the measured dose as one approaches regions close to the edges of the scanning region. In this note, we present measurements of the spatial response of an AGFA Arcus II document scanner used for radiochromic film dosimetry. Results and methods presented in this work can be generalized to other CCD based transmission scanners used for film dosimetry employing either radiochromic or radiographic films.
Devic, Slobodan; Wang Yizhen; Tomic, Nada; Podgorsak, Ervin B. [Medical Physics Department, McGill University Health Centre, Montreal, Quebec (Canada)
Sensitivity of linear CCD array based film scanners used for film dosimetry.
Film dosimetry is commonly performed by using linear CCD array transmission optical densitometers. However, these devices suffer from a variation in response along the detector array. If not properly corrected for, this nonuniformity may lead to significant overestimations of the measured dose as one approaches regions close to the edges of the scanning region. In this note, we present measurements of the spatial response of an AGFA Arcus II document scanner used for radiochromic film dosimetry. Results and methods presented in this work can be generalized to other CCD based transmission scanners used for film dosimetry employing either radiochromic or radiographic films. PMID:17153378
Devic, Slobodan; Wang, Yi-Zhen; Tomic, Nada; Podgorsak, Ervin B
Cellulose nanofibril based graft conjugated polymer films act as a chemosensor for nitroaromatic.
A cellulose nanofibril film is modified by chemical assembly of boronate-terminated conjugated polymer chains at its specific sites, C-6 carboxyl groups. The modified cellulose nanofibril film is used as a fluorescent sensor for nitroaromatic vapor. Thanks to the specific reactive sites, numerous loose cavities or pathways located in the film sensor's out-layer have been formed, and the fraction of easily accessible cavities of the novel fluorescent film sensor is up to 0.97, which could benefit the penetration and diffusion of analyte vapor. Therefore, the novel fluorescent film sensor exhibits high sensitivity toward nitroaromatic vapor with a fast response. The fluorescence quenching efficiency of the chemical-assembly film sensor is about 3 times larger than that of the spin-cast film sensor using the same conjugated polymer for 600 s exposure to DNT vapor. In addition, the novel fluorescent film sensor shows good reversibility. PMID:24906727
Niu, Qingyuan; Gao, Kezheng; Wu, Wenhui
ShakeCast Manual
USGS Publications Warehouse
ShakeCast is a freely available, post-earthquake situational awareness application that automatically retrieves earthquake shaking data from ShakeMap, compares intensity measures against users? facilities, and generates potential damage assessment notifications, facility damage maps, and other Web-based products for emergency managers and responders.
Lin, Kuo-Wan; Wald, David J.
Development of a novel antimicrobial film based on chitosan with LAE (ethyl-N(?)-dodecanoyl-l-arginate) and its application to fresh chicken.
Chitosan (CS) films incorporating the antimicrobial compound ethyl-N(?)-dodecanoyl-l-arginate (LAE) were developed for food packaging applications. Cast chitosan films were made with 1, 5 or 10% LAE and 20% glycerol in the film forming solution. Optical properties, release of LAE and antimicrobial activity of developed films was determined. The minimum inhibitory concentration (MIC) and the minimum biocide concentration (MBC) of LAE were determined. CS films with LAE were transparent and uniform, without discontinuities or visible particles and no visual differences could be perceived between CS and CS-LAE films. When in contact with an aqueous food simulant, the agent was fully released following a Fickian behavior in a few hours at 4 and 28░C. Antimicrobial activity of films against mesophiles, psychrophiles, Pseudomonas spp., colifoms, lactic acid bacteria, hydrogen sulfide-producing bacteria, yeast and fungi, was evaluated at two, six and eight days for its application on chicken breast fillets. Films were active against bacteria, yeasts and fungi in liquid and solid media. CS films evidenced antimicrobial activity in the range 0.47-2.96 log reductions, while CS-5%LAE film produced 1.78-5.81 log reduction. Results highlighted that LAE incorporation in a chitosan-based packaging structure may provide a relevant antimicrobial activity that could improve the stability of fresh poultry products. PMID:23816804
Higueras, Laura; L¾pez-Carballo, Gracia; Hernßndez-Mu±oz, Pilar; Gavara, Rafael; Rollini, Manuela
Casting methods
A casting device includes a covered crucible having a top opening and a bottom orifice, a lid covering the top opening, a stopper rod sealing the bottom orifice, and a reusable mold having at least one chamber, a top end of the chamber being open to and positioned below the bottom orifice and a vacuum tap into the chamber being below the top end of the chamber. A casting method includes charging a crucible with a solid material and covering the crucible, heating the crucible, melting the material, evacuating a chamber of a mold to less than 1 atm absolute through a vacuum tap into the chamber, draining the melted material into the evacuated chamber, solidifying the material in the chamber, and removing the solidified material from the chamber without damaging the chamber.
Marsden, Kenneth C.; Meyer, Mitchell K.; Grover, Blair K.; Fielding, Randall S.; Wolfensberger, Billy W.
Langmuir films from antibodies based on amphiphilic polyelectrolytes.
A technique for forming Langmuir films from antibodies based on an amphiphilic polyelectrolyte was developed. The physicochemical and immunochemical properties of the Langmuir films obtained were studied. The interaction of HBsAg with the films was found to be described by a model with one binding site, whereas that of HBsAg with antibodies adsorbed on a polystyrene plate, by a model with a positive cooperativity. The use of the novel Langmuir films from antibodies increases the sensitivity of the immunoenzyme assay. PMID:9231367
Babitskaya, J I; Budashov, I A; Chernov, S F; Kurochkin, I N; Doroshenko, N V; Zubov, S V
A poly vinylidene fluoride (PVF2) piezoelectric film based accelerometer
The paper presents an accelerometer built by means of a piezoelectric film, poly vinylidene fluoride-PVF2. The piezoelectric effect of this is explored and shown to have better mechanical sensitivity than piezoelectric ceramics due to the short thickness of the film. The design is based on a typical piezoelectric ceramic seismic system, which uses the sensitiveness of the piezoelectric element through
R. F. M. Marcal; J. L. Kovaleski; A. A. Suzim
Genetic Affinity Between Two Ethnically Diverse Caste Groups of North India: A Study Based Upon 15 Microsatellite Loci
KEYWORDS Genetic affinity; Jat and Kurmi; caste; average heterozygosity, geographical proximity ABSTRACT This study attempts to understand the genetic structure and affinity among two major ethnic caste groups viz., Jat and Kurmi of north India in order to examine the effect of geographical as well as occupational proximity among these groups and their genetic relationship with two other predominant populations
M. Tandon; T. S. Vasulu; R. Trivedi; V. K. Kashyap
Chitosan and gelatin based edible films: state diagrams, mechanical and permeation properties
Films of chitosan and gelatin were prepared by casting their aqueous solutions (pH?4.0) at 60░C and evaporating at 22 or 60░C (low- and high-temperature methods, respectively). The physical (thermal, mechanical and gas\\/water permeation) properties of these composite films, plasticized with water or polyols, were studied. An increase in the total plasticizer content resulted in a considerable decrease of elasticity modulus
Ioannis S. Arvanitoyannis; Atsuyoshi Nakayama; Sei-ichi Aiba
Studies on PEO-based sodium ion conducting composite polymer films
A sodium ion conducting composite polymer electrolyte (CPE) prepared by solution-caste technique by dispersion of an electrochemically\\u000a inert ceramic filler (SnO2) in the PEO¢salt complex matrix is reported. The effect of filler concentration on morphological, electrical, electrochemical,\\u000a and mechanical stability of the CPE films has been investigated and analyzed. Composite nature of the films has been confirmed\\u000a from X-ray diffraction
Saumya R. Mohapatra; Awalendra K. Thakur; R. N. P. Choudhary
Film bulk acoustic-wave resonator based ultraviolet sensor
This letter described ultraviolet (UV) radiation sensing with ZnO based film bulk acoustic-wave resonator (FBAR). The resonant frequency upshifted when there was UV illumination on the FBAR. For 365 nm UV light, the frequency upshift was 9.8 kHz with an intensity of 600 ?W/cm2, and the detection limit of the sensor was 6.5 nW. The frequency increase in the FBAR UV sensor was proposed to be due to the density decrease in ZnO film upon UV illumination. When UV was incident on the ZnO film, it can cause oxygen desorption from the ZnO surface, resulting in density decrease in the film. This study has proven the feasibility of detection of low intensity UV using ZnO film based FBAR.
Qiu, X.; Zhu, J.; Oiler, J.; Yu, C.; Wang, Z.; Yu, H.
Cementite Solidification in Cast Iron
Two hypereutectic cast irons (5.01 pct Cr and 5.19 pct V) were cast and the polished surfaces of test pieces were deep-etched and analyzed via scanning electron microscopy. The results show that graphite lamellae intersect the cementite and a thin austenite film nucleates and grows on the cementite plates. For both compositions, graphite and cementite can coexist as equilibrium phases, with the former always nucleating and growing first. The eutectic carbides grow from the austenite dendrites in a direction perpendicular to the primary plates.
Coronado, J. J.; Sinatora, A.; Albertin, E.
Model-Based Simulations to Engineer Nanoporous Thin Films.
A model-based simulation (MBS) capability for tailoring the fabrication processes and the properties of wide band gap semiconductors thin films (TF) with engineered nanoscale porosity has been achieved in two ways: (1) By using molecular dynamics simulati...
F. Costanzo
Preparation of refractive index matching polymer film alternative to oil for use in a portable surface-plasmon resonance phenomenon-based chemical sensor method.
In order to simplify the procedure for assembling a surface-plasmon resonance (SPR) sensor, a refractive index matching polymer film was prepared as an alternative to the conventionally used matching oil. The refractive index matching polymer film, the refractive index of which was nearly equal to the prism and sensor chip material (a cover glass) of the SPR sensor, was prepared by casting a tetrahydrofuran solution of poly (vinyl chloride) (PVC) containing equal weights of dioctyl phthalate and tricresyl phosphate. The refractive index matching polymer film was found to have a refractive index of 1.516, which is identical to that of the prism and the cover glass used for the present SPR sensor. The utility of the matching polymer film for the SPR sensor was confirmed by the detection of anti-human albumin, based on an antigen-antibody reaction. PMID:12110971
Masadome, Takashi; Asano, Yasukazu; Imato, Toshihiko; Ohkubo, Satoshi; Tobita, Tatsuya; Tabei, Hisao; Iwasaki, Yuzuru; Niwa, Osamu; Fushinuki, Yoshito
Bead-based DNA Microarray Fabricated on Porous Polymer Films
By attaching different biomolecule probes to surface-modified microspheres, a large number of complementary targets labeled\\u000a with fluorophores can be interrogated simultaneously using the bead-based microarray format. In this work, a new bead-based\\u000a DNA microarray was fabricated on a porous polymer film with well-ordered array of pores. The well-ordered porous polymer film\\u000a was prepared using the non-lithographic breath figure method. Different
J. T. Cheng; J. Li; N. G. Chen; P. Gopalakrishnakone; Y. Zhang
Casting materials
A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.
Chaudhry, Anil R. (Xenia, OH); Dzugan, Robert (Cincinnati, OH); Harrington, Richard M. (Cincinnati, OH); Neece, Faurice D. (Lyndurst, OH); Singh, Nipendra P. (Pepper Pike, OH)
Preparation, characterization and in vitro evaluation of a polyvinyl alcohol/sodium alginate based orodispersible film containing sildenafil citrate.
In this work, we developed a sildenafil citrate (SC)-loaded polyvinyl alcohol (PVA)/sodium alginate (ALG-Na) based orodispersible film (ODF) using a solvent casting method. Formulation factors such as the type and amount of plasticizers and disintegrants were optimized on the basis of characteristics of blank ODF, including the disintegration time, elastic modulus (EM) and percentage of elongation (E%). SC-loaded ODF with a loading capacity up to 25 mg in an area of 6 cm2 was prepared and evaluated in terms of mechanical properties, disintegration time and dissolution rate. The surface morphology of ODF was visualized under a scanning electron microscope (SEM). The physicochemical properties of ODF were investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). The blank ODF composed of PVA, polyethylene glycol 400 (PEG 400) and ALG-Na (20:5:2, w/w) had a remarkably short disintegration time of about 20 s. However, the loading of drug extended the disintegration time (100 s) of ODF, while it still maintained satisfactory mechanical properties. SC was homogenously dispersed throughout the films and the crystalline form of drug changed, with strong hydrogen bonding between the drug and carriers. The PVA/ALG-Na based ODF containing SC prepared by the simple solvent casting method might be an alternative to conventional SC tablets for the treatment of male erectile dysfunction. PMID:24855822
Shi, Li-Li; Xu, Wei-Juan; Cao, Qing-Ri; Yang, Mingshi; Cui, Jing-Hao
Optimization of Gating System Design for Die Casting of Thin Magnesium Alloy-Based Multi-Cavity LCD Housings
High-pressure die casting is the preferred process for manufacturing Mg-alloy components used for numerous applications. High-pressure die casting is suitable for mass production and has the advantage of also being suitable for accurately fashioning objects of complicated shapes. One disadvantage of high-speed die casting is the occurrence of defects such as shrinkage or air entrainment. Gating system design must be very effective in actual manufacturing facilities to avoid the occurrence of such defects. The objective of this study is to present a methodology for obtaining optimal designs of 4-cavity thin electronic component housings. The fluid behavior and amount of air entrainment caused by the overflows and air vent designs were analyzed using a computer fluid dynamics (CFD) simulator. The effectiveness of the proposed system was demonstrated through CFD simulations and experiments using an actual manufacturing process. Also, the effect of vacuum systems on the porosity and mechanical properties of the castings was studied. The volume of porosity in the casting was found to be significantly reduced using vacuum assistance during die casting. As a result, the tensile strength and the elongation of the die casting products are improved.
Lee, B. D.; Baek, U. H.; Han, J. W.
Effect of gamma radiation on the mechanical and barrier properties of HEMA grafted chitosan-based films
Chitosan films were prepared by dissolving 1% (w/v) chitosan powder in 2% (w/v) aqueous acetic acid solution. Chitosan films were prepared by solution casting. The values of puncture strength (PS), viscoelasticity coefficient and water vapor permeability (WVP) of the films were found to be 565 N/mm, 35%, and 3.30 g mm/m2 day kPa, respectively. Chitosan solution was exposed to gamma irradiation (0.1-5 kGy) and it was revealed that PS values were reduced significantly (p?0.05) after 1 kGy dose and it was not possible to form films after 5 kGy. Monomer, 2-hydroxyethyl methacrylate (HEMA) solution (0.1-1%, w/v) was incorporated into the chitosan solution and the formulation was exposed to gamma irradiation (0.3 kGy). A 0.1% (w/v) HEMA concentration at 0.3 kGy dose was found optimal-based on PS values for chitosan grafting. Then radiation dose (0.1-5 kGy) was optimized for HEMA grafting. The highest PS values (672 N/mm) were found at 0.7 kGy. The WVP of the grafted films improved significantly (p?0.05) with the rise of radiation dose.
Khan, Avik; Huq, Tanzina; Khan, Ruhul A.; Dussault, Dominic; Salmieri, Stephane; Lacroix, Monique
Porphyrin-based honeycomb films and their antibacterial activity.
Micrometer-sized porous honeycomb-patterned thin films based on hybrid complexes formed via electrostatic interaction between Mn(III) meso-tetra(4-sulfonatophenyl) porphine chloride (an acid form, {MnTPPS}) and dimethyldioctadecylammonium bromide (DODMABr). The morphology of the microporous thin films can be well regulated by controlling the concentration of MnTPPS-DODMA complexes, DODMABr, and polystyrene (PS), respectively. The formation of the microporous thin films was largely influenced by different solvents. The well-ordered microporous films of MnTPPS-DODMA complexes exhibit a more efficient antibacterial activity under visible light than those of hybrid complexes of nanoparticles modified with DODMABr, implying that well-ordered microporous films containing porphyrin composition can improve photochemical activity and more dominance in applications in biological medicine fields. PMID:24846091
Wang, Yanran; Liu, Yan; Li, Guihua; Hao, Jingcheng
Conducting transparent thin films based on Carbon Nanotubes - Conducting Polymers
The present work reports on the characterization and optimization of thin transparent and electrically conducting films (from 120 to 180 nm thick) based on single walled carbon nanotubes (CNT) and conducting polymers, polypyrrole (PPy) or polyaniline (PA). We obtained a number of different CNT-PPy doped with PTS or PF6 and CNT-PA under different parameters (electrodeposition time, density current or voltage) and analyzed the required properties, electrical conductivity and transparency, and other significant properties: Raman Spectroscopy, and AFM, from which we can estimate the film thickness. The electrochemical conditions for the polymer thin film deposition were studied in order to improve their conductivity and transparency. Compared to the well known transparent conducting oxides like ITO, the best of our composite thin films are from 10 to 100 times less conductive and highly transparent. As a great possibility, these conducting films could be prepared on a flexible substrate with a continuous deposition procedure.
Ferrer-Anglada, N.; Gomis, V.; El-Hachemi, Z.; Kaempgen, M.; Roth, S.
p-channel thin-film transistors based on spray-coated Cu2O films
Thin films of cuprous oxide (Cu2O) were grown using solution-based spray pyrolysis in ambient air and incorporated into hole-transporting thin-film transistors. The phase of the oxide was confirmed by X-ray diffraction measurements while the optical band gap of the films was determined to be ~2.57 eV from optical transmission measurements. Electrical characterization of Cu2O films was performed using bottom-gate, bottom-contact transistors based on SiO2 gate dielectric and gold source-drain electrodes. As-prepared devices show clear p-channel operation with field-effect hole mobilities in the range of 10-4-10-3 cm2 V-1 s-1 with some devices exhibiting values close to 1 ū 10-2 cm2 V-1 s-1.
Pattanasattayavong, Pichaya; Thomas, Stuart; Adamopoulos, George; McLachlan, Martyn A.; Anthopoulos, Thomas D.
Elevated Temperature Tensile and Creep Properties of M-252 (Bar), Inconel 700 (Bar), and Inconel 713 (Cast) Nickel Base Alloys.
Room and elevated temperature tensile and elevated temperature creep properties to 1000 hours were determined at three representative application temperatures for M-252 (bar), Inconel 700 (bar), and Inconel 713 (cast). Tabulated tensile and creep data, de...
S. O. Davis
Superhydrophobic cellulose-based bionanocomposite films from Pickering emulsions
Inherently superhydrophobic and flexible cellulose-based bionanocomposites were fabricated from solid stabilized (Pickering) emulsions. Emulsions were formed by dispersing cyclosiloxanes in water stabilized by layered silicate particles and were subsequently modified by blending into a zinc oxide nanofluid. The polymer matrix was a blend of cellulose nitrate and fluoroacrylic polymer (Zonyl 8740) precompatibilized in solution. Coatings were spray cast onto aluminum substrates from polymer blends dispersed in modified Pickering emulsions. No postsurface treatment was required to induce superhydrophobicity. Effect of antiseptic additives on bionanocomposite superhydrophobicity is also discussed. Replacing cellulose nitrate with commercial liquid bandage solutions produced identical superhydrophobic coatings.
Bayer, Ilker S.; Steele, Adam; Martorana, Philip J.; Loth, Eric; Miller, Lance
High-temperature superconducting thin-film-based electronic devices
This the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project involved optimization of processing of Y123 and Tl-2212 thin films deposited on novel substrates for advanced electronic devices. The Y123 films are the basis for development of Josephson Junctions to be utilized in magnetic sensors. Microwave cavities based on the Tl-2212 films are the basis for subsequent applications as communication antennas and transmitters in satellites.
Wu, X.D; Finokoglu, A.; Hawley, M.; Jia, Q.; Mitchell, T.; Mueller, F.; Reagor, D.; Tesmer, J.
Ultra-sensitive strain sensors based on piezoresistive nanographene films
Graphene shows promise on strain sensor applications, but the piezoresistive sensitivity of perfect graphene is low due to its weak electrical conductivity response upon structural deformation. In this paper, we used nanographene films for ultra-sensitive strain sensors. The piezoresistive sensitivity of nanographene films with different thicknesses and conductivities was systematically investigated and a nearly inverse proportional correlation was found. A gauge factor over 300, the highest so far for graphene-based strain sensors, was achieved. A charge tunneling model was used to explain the piezoresistive characteristics of nanographene films, which indicates our results provide a different rout toward ultra-sensitive strain sensors.
Zhao, Jing; He, Congli; Yang, Rong; Shi, Zhiwen; Cheng, Meng; Yang, Wei; Xie, Guibai; Wang, Duoming; Shi, Dongxia; Zhang, Guangyu
Mechanical and Ferroelectric Behavior of PZT-Based Thin Films
The mechanical and ferroelectric behavior of freestanding lead zirconate titanate (PZT) -based thin film uni- morph structures for microelectromechanical systems was in- vestigated with uniaxial tension specimens of SiO2-TiPt-PZT-Pt, SiO2-TiPt-PZT, SiO2-TiPt, and individual SiO2 and Pt films. Full-field strains obtained with digital image correlation were used to compute the stress versus strain curves for each film combina- tion and the
Sivakumar Yagnamurthy; Ioannis Chasiotis; John Lambros; Ronald G. Polcawich; Jeffrey S. Pulskamp; Madan Dubey
Linear Microbolometric Array Based on VOx Thin Film
In this paper, a linear microbolometric array based on VOx thin film is proposed. The linear microbolometric array is fabricated by using micromachining technology, and its thermo-sensitive VOx thin film has excellent infrared response spectrum and TCR characteristics. Integrated with CMOS circuit, an experimentally prototypical monolithic linear microbolometric array is designed and fabricated. The testing results of the experimental linear array show that the responsivity of linear array can approach 18KV/W and is potential for infrared image systems.
Chen, Xi-Qu
Optical switch based on vanadium dioxide thin films
In this letter, novel optical switches based on VO2 thin film on substrates of silicon (100) has been fabricated. The vanadium dioxide thin films were deposited by reactive ion beam sputtering followed by a post-annealing. Testing shows the insertion loss of the optical switches is 1¢2 dB, and the extinction ratio up to 26 dB. The speed of the switches
Sihai Chen; Hong Ma; Xinjian Yi; Hongcheng Wang; Xiong Tao; Mingxiang Chen; Xiongwei Li; Caijun Ke
Nickel-based air-firable thick-film conductors
The evolution of microstructure\\/composition of nickel-based thick films prepared from airfirable pastes has been investigated. Through the use of several analytical techniques it has been found that the pastes contain elemental boron and\\/or a boron-rich component which effectively competes with the oxidation of nickel grains. The evolution of the electrical properties of the film has also been studied. Even when
F. Sirotti; M. Prudenziati; T. Manfredini; B. Giardullo; W. Anzolin
Ion-based methods for optical thin film deposition
The optical properties of the dielectric oxide films SiO2, Al2O3, TiO2, ZrO2, CeO2 and Ta2O5 produced by ion-based techniques have been reviewed. The influence of ion bombardment during deposition is discussed in some detail and the various production techniques are described. Recent results on the deposition and properties of diamond-like carbon films are also reviewed. Finally, some examples of the
P. J. Martin
USGS ShakeCast
Automating, Simplifying, and Improving the Use of ShakeMap for Post-Earthquake Decisionmaking and Response. ShakeCast is a freely available, post-earthquake situational awareness application that automatically retrieves earthquake shaking data from ShakeMap, compares intensity measures against users facilities, and generates potential damage assessment notifications, facility damage maps, and other Web-based products for emergency managers and responders.
Wald, David; Lin, Kuo-Wan
Effects of composition and testing conditions on oxidation behavior of four cast commercial nickel-base superalloys
Four cast nickel-base superalloys were oxidized at 1000 and 1100 C for times up to 100 hr in static air and a Mach 1 gas stream. The oxidation resistance was judged by weight change, metal thickness loss, depletion-zone formation, and oxide formation and morphology. The alloys which formed mostly nickel aluminate (NiAl2O4) and aluminum oxide (Al2O3) (B-1900, VIA, and to a lesser extent 713C) were more oxidation resistant. Poorer oxidation resistance was associated with the appearance of chromium sesquioxide (Cr2O3) and chromite spinel (738X). Refractory metal content had little effect on oxidation resistance. Refractory metals appeared in the scale as tapiolite (NiM2O6, where M represents the refractory metal). Thermal cycling in static air appeared to supply sufficient data for the evaluation of oxidation resistance, especially for alloys which form oxides of low volatility. For alloys of higher chromium levels with high propensities toward forming a chromium-bearing scale of higher volatility, testing under conditions of high gas velocity is necessary to assess fully the behavior of the alloy.
Lowell, C. E.; Probst, H. B.
A space imaging concept based on a 4m structured spun-cast borosilicate monolithic primary mirror
Lockheed Martin Corporation (LMC) tasked The University of Arizona Steward Observatory (UASO) to conduct an engineering study to examine the feasibility of creating a 4m space telescope based on mature borosilicate technology developed at the UASO for ground-based telescopes. UASO has completed this study and concluded that existing launch vehicles can deliver a 4m monolithic telescope system to a 500 km circular orbit and provide reliable imagery at NIIRS 7-8. An analysis of such an imager based on a lightweight, high-performance, structured 4m primary mirror cast from borosilicate glass is described. The relatively high CTE of this glass is used to advantage by maintaining mirror shape quality with a thermal figuring method. Placed in a 290 K thermal shroud (similar to the Hubble Space Telescope), the orbit averaged figure surface error is 6nm rms when earth-looking. Space-looking optical performance shows that a similar thermal conditioning scheme combined with a 270 K shroud achieves primary mirror distortion of 10 nm rms surface. Analysis shows that a 3-point bipod mount will provide launch survivability with ample margin. The primary mirror naturally maintains its shape at 1g allowing excellent end-to-end pre-launch testing with e.g. the LOTIS 6.5m Collimator. The telescope includes simple systems to measure and correct mirror shape and alignment errors incorporating technologies already proven on the LOTIS Collimator. We have sketched a notional earth-looking 4m telescope concept combined with a wide field TMA concept into a DELTA IV or ATLAS 552 EELV fairing. We have combined an initial analysis of launch and space performance of a special light-weighted honeycomb borosilicate mirror (areal density 95 kg/m2) with public domain information on the existing launch vehicles.
West, S. C.; Bailey, S. H.; Bauman, S.; Cuerden, B.; Granger, Z.; Olbert, B. H.
SUBTLEX-ESP: Spanish Word Frequencies Based on Film Subtitles
Recent studies have shown that word frequency estimates obtained from films and television subtitles are better to predict performance in word recognition experiments than the traditional word frequency estimates based on books and newspapers. In this study, we present a subtitle-based word frequency list for Spanish, one of the most widely spokenģ
Cuetos, Fernando; Glez-Nosti, Maria; Barbon, Analia; Brysbaert, Marc
A sensor of alcohol vapours based on thin polyaniline base film and quartz crystal microbalance
Thin films of polyaniline base, emeraldine base (EB), coating on the quartz crystal microbalance (QCM) electrode were used as a sensitive layer for the detection of a number of primary aliphatic alcohols such as ethanol, methanol, 2-propanol and 1-propanol vapours. The frequency shifts (?f) of the QCM were increased due to the vapour adsorption into the EB film. ?f were
Mohamad M. Ayad; Gad El-Hefnawey; Nagy L. Torad
Thin Wall Iron Castings
Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified.
J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka
Flexible and transparent electrothermal film heaters based on graphene materials.
High-performance and novel graphene-based electrothermal films are fabricated through a simple yet versatile solution process. Their electrothermal performances are studied in terms of applied voltage, heating rate, and input power density. The electrothermal films annealed at high temperature show high transmittance and display good heating performance. For example, the graphene-based film annealed at 800 ░C, which shows transmittance of over 80% at 550 nm, can reach a saturated temperature of up to 42 ░C when 60 V is applied for 2 min. Graphene-based films annealed at 900 and 1000 ░C can exhibit high steady-state temperatures of 150 and 206 ░C under an applied voltage of 60 V with a maximum heating rate of over 7 ░C s(-1) . For flexible heating films patterned on polyimide, a steady-state temperature of 72 ░C could be reached in less than 10 s with a maximum heating rate exceeding 16 ░C s(-1) at 60 V. These excellent results, combined with the high chemical stability and mechanical flexibility of graphene, indicate that graphene-based electrothermal elements hold great promise for many practical applications, such as defrosting and antifogging devices. PMID:21990210
Sui, Dong; Huang, Yi; Huang, Lu; Liang, Jiajie; Ma, Yanfeng; Chen, Yongsheng
A casting based process to fabricate 3D alginate scaffolds and to investigate the influence of heat transfer on pore architecture during fabrication
The fabrication of 3-dimensional (3D) tissue scaffolds is a competitive approach to engineered tissues. An ideal tissue scaffold must be highly porous, biocompatible, biodegradable, easily processed and cost-effective, and have adequate mechanical properties. A casting based process has been developed in this study to fabricate 3D alginate tissue scaffolds. The alginate\\/calcium gluconate hydrogel was quenched in a glass mold and
W. M. Parks; Y. B. Guo
A pi-stacking terthiophene-based quinodimethane is an n-channel conductor in a thin film transistor.
A terthiophene-based quinodimethane, 3',4'-dibutyl-5,5' '-bis(dicyanomethylene)-5,5' '-dihydro-2,2':5',2' '-terthiophene (1) was synthesized and crystallized. Compound 1 has a planar quinoid geometry that is stabilized by dicyanomethylene groups at each end of the molecule. In the crystal each molecule is part of a dimerized face-to-face pi-stack, with intermolecular spacings of 3.47 and 3.63 A, respectively. Cyclic voltammetry showed that 1 could be reversibly reduced and oxidized in methylene chloride solution. Thin film transistors (TFTs) were prepared by vacuum evaporation of 1 onto SiO2(300 nm)/Si substrates, followed by evaporation of Ag source and drain contacts. The doped Si substrate served as the gate electrode. X-ray diffraction and atomic force microscopy indicate the films are polycrystalline, with the long axes of the molecules approximately perpendicular to the substrate. The TFT measurements revealed n-channel conduction in films of 1, with room-temperature electron field effect mobilities as high as 0.005 cm2/Vs. The butyl side chains give 1 appreciable solubility in a range of common solvents, and preliminary TFT results on films cast from chlorobenzene show electron mobility as high as 0.002 cm2/Vs. These results indicate that pi-stacked quinoidal thiophene oligomers are a promising new class of soluble n-channel organic semiconductors. PMID:11960427
Pappenfus, Ted M; Chesterfield, Reid J; Frisbie, C Daniel; Mann, Kent R; Casado, Juan; Raff, Jonathan D; Miller, Larry L
36 CFR 1237.30 - How do agencies manage records on nitrocellulose-base and cellulose-acetate base film?
Code of Federal Regulations, 2010 CFR
...manage records on nitrocellulose-base and cellulose-acetate base film? 1237.30 Section...manage records on nitrocellulose-base and cellulose-acetate base film? (a) The...base). (b) Agencies must inspect cellulose-acetate film periodically for...
Diagnostic accuracy of monoclonal antibody based serum immunoglobulin free light chain immunoassays in myeloma cast nephropathy
Background The development of serum immunoassays for the measurement of immunoglobulin free light chains has led to a paradigm shift in the diagnosis, assessment and monitoring of patients with plasma cell dyscrasias. The impact of these immunoassays which employ polyclonal antibodies was most notable for those patients who were previously classified as non-secretory multiple myeloma. Recently new monoclonal antibody based assays have become available. The purpose of this study was to compare the diagnostic sensitivity of these new assays with those already in clinical practice. Methods Sera from 30 patients who present with severe acute kidney injury and multiple myeloma were identified for analysis. A head to head comparison of the two commercially available free light chains assays was then undertaken to determine if their diagnostic sensitivity and specificity were comparable. Results In this first assessment of the utility of these new assays, we found that one of 17 patients with a lambda monoclonal free light chain resulting in acute kidney injury were not identified and a further 12% of patients were wrongly classified as having levels below those associated with disease specific acute kidney injury. Conclusion These results suggest that caution should be applied to the use of new free light chain assays in the assessment of patients with a monoclonal gammopathy.
Informing Selection of Nanomaterial Concentrations for ToxCast in Vitro Testing Based on Occupational Exposure Potential
Background: Little justification is generally provided for selection of in vitro assay testing concentrations for engineered nanomaterials (ENMs). Selection of concentration levels for hazard evaluation based on real-world exposure scenarios is desirable. Objectives: Our goal was to use estimates of lung deposition after occupational exposure to nanomaterials to recommend in vitro testing concentrations for the U.S. Environmental Protection AgencyÆs ToxCastÖ program. Here, we provide testing concentrations for carbon nanotubes (CNTs) and titanium dioxide (TiO2) and silver (Ag) nanoparticles (NPs). Methods: We reviewed published ENM concentrations measured in air in manufacturing and R&D (research and development) laboratories to identify input levels for estimating ENM mass retained in the human lung using the multiple-path particle dosimetry (MPPD) model. Model input parameters were individually varied to estimate alveolar mass retained for different particle sizes (5¢1,000 nm), aerosol concentrations (0.1 and 1 mg/m3), aspect ratios (2, 4, 10, and 167), and exposure durations (24 hr and a working lifetime). The calculated lung surface concentrations were then converted to in vitro solution concentrations. Results: Modeled alveolar mass retained after 24 hr is most affected by activity level and aerosol concentration. Alveolar retention for Ag and TiO2 NPs and CNTs for a working-lifetime (45 years) exposure duration is similar to high-end concentrations (~ 30¢400 ?g/mL) typical of in vitro testing reported in the literature. Conclusions: Analyses performed are generally applicable for providing ENM testing concentrations for in vitro hazard screening studies, although further research is needed to improve the approach. Understanding the relationship between potential real-world exposures and in vitro test concentrations will facilitate interpretation of toxicological results.
Brown, James S.; Wang, Amy; Houck, Keith A.; Dix, David J.; Kavlock, Robert J.; Hubal, Elaine A. Cohen
Improved motion analysis system for film-based data reduction
Traditional 16mm and 35mm high-speed film-based data analysis is significantly improved with the introduction of a new generation, low-cost and fully integrated rear projection motion analyzer. The X-Y data are digitized and collected by an operator using a hand-held cursor. However, all film handling functions are fully automated under the control of a built-in microprocessor and/or external host computer by way of a bi-directional RS-232 port. A companion PC-based software package integrates the data collection task, minimizes operator stress and provides complete solution data. This new analyzer system provides scientists and engineers with a much faster means of digitizing and greater system accuracy when compared to existing film readers in the field.
Pendley, Gilbert J.
Reactively sputtered Fe3O4-based films for spintronics
Half metallic polycrystalline, epitaxial Fe3O4 films and Fe3O4-based heterostructures for spintronics were fabricated by DC reactive magnetron sputtering. Large tunneling magnetoresistance was found in the polycrystalline Fe3O4 films and attributed to the insulating grain boundaries. The pinning effect of the moments at the grain boundaries leads to a significant exchange bias. Frozen interfacial/surface moments induce weak saturation of the high-field magnetoresistance. The films show a moment rotation related butterfly-shaped magnetoresistance. It was found that in the films, natural growth defects, antiphase boundaries, and magnetocrystalline anisotropy play important roles in high-order anisotropic magnetoresistance. Spin injection from Fe3O4 films to semiconductive Si and ZnO was measured to be 45% and 28.5%, respectively. The positive magnetoresistance in the Fe3O4-based heterostructures is considered to be caused by a shift of the Fe3O4 eg ? band near the interface. Enhanced magnetization was observed in Fe3O4/BiFeO3 heterostructures experimentally and further proved by first principle calculations. The enhanced magnetization can be explained by spin moments of the thin BiFeO3 layer substantially reversing into a ferromagnetic arrangement under a strong coupling that is principally induced by electronic orbital reconstruction at the interface.
Li, Peng; Jin, Chao; Mi, Wen-Bo; Bai, Hai-Li
Simulation-based selection of optimum pressure die-casting process parameters using neural nets and genetic algorithms
Pressure die-casting condition selection mainly relies on the experience and expertise of individuals working in production industries. Systematic knowledge accumulation regarding the manufacturing process is essential in order to obtain optimal process conditions. It is not safe a priori to presume that rules of thumb, which are widely used on the shop floor, always lead to fast prototype production calibration
A. Krimpenis; P. G. Benardos; G.-C. Vosniakos; A. Koukouvitaki
Ultrathin calix(n)arene-based Langmuir-Blodgett films for gas separations
Gas separation composite membranes consisting of ultrathin amphiphilic calix[n]arene (C[n]A) monolayers deposited on highly permeable poly[1-(trimethylsilyl)-1-propyne] (PTMSP) support were fabricated and characterized. A series of calix[n]arene-based surfactants was studied, which consisted of various number of units in the macrocycle (e.g., n = 4, 5 and 6), hydrophilic head groups on the "upper-rim" [e.g., amidoxime (AO), boronic acid and acetyl (MK) head groups] and alkyl chains on the "lower rim" [e.g., n-octyl, n-dodecyl (C12) and n-hexadecyl ( C16) tails]. For purposes of comparison, conventional surfactants such as arachidic acid, stearoamidoxime (SA), heptadecylboronic acid and poly(1-octadecene-co-maleic anhydride) (POM) were also investigated. The surfactants were characterized by determining their monolayer properties at the air-water interface, which included surface pressure-area isotherm and surface viscosity behavior. Composite membranes were fabricated using Langmuir-Blodgett (LB) and self-assembly methods and characterized by He and N2 gas permeation properties, X-ray photoelectron spectroscopy, FTIR spectroscopy, ellipsometry, goniometry and electronic imaging. Composites consisting of LB monolayers of amphiphilic calix[n]arene, polymeric and single straight-chain surfactants on PTMSP cast film exhibit significant, modest and no increases in permeation selectivity as compared to the parent support, respectively; e.g., composites consisting of four LB monolayers of C16C[6]AAO, C12C[6]AAO, C16C[6]AMK, POM and SA on PTMSP and bare PTMSP exhibit He/N2 selectivities of ca. 200, 100, 24, 5, 0.9 and 0.9, respectively. Evidence for the causes of these dramatic differences in properties are reported and discussed. It has been found that important criteria for forming highly gas selective surfactant films include: (1) the individual surfactants must be large enough to span the individual holes of the support and (2) strong intermolecular forces between neighboring calix[n]arenes (e.g., via H-bonding and hydrophobic interactions) are necessary to form tightly-packed and robust LB films. The implications of these results, in terms of the further development of LB films as membranes for gas separations and comparisons between industrial membrane materials are discussed. A LB film of C16C[6]AAO represents the "world's thinnest" membrane separator, achieving high He/N2 selectivity.
Hendel, Robert Ashley
Optical properties of a long dynamic range chemical UV dosimeter based on solvent cast polyvinyl chloride (PVC).
The dosimetric properties of the recently introduced UV dosimeter based on 16 ?m PVC film have been fully characterised. Drying the thin film in air at 50 ░C for at least 28 days was found to be necessary to minimise the temperature effects on the dosimeter response. This research has found that the dosimeter response, previously reported to be mainly to UVB, has no significant dependence on either exposure temperature or dose rate. The dosimeter has negligible dark reaction and responds to the UV radiation with high reproducibility. The dosimeter angular response was found to have a similar pattern as the cosine function but deviates considerably at angles larger than 70░. Dose response curves exhibit monotonically increasing shape and the dosimeter can measure more than 900 SED. This is about 3 weeks of continuous exposure during summer at subtropical sites. Exposures measured by the PVC dosimeter for some anatomical sites exposed to solar radiation for twelve consecutive days were comparable with those concurrently measured by a series of PPO dosimeters and were in line with earlier results reported in similar studies. PMID:24084259
Synthesis and mechanical properties of quaternary salts of chitosan-based films for food application
A novel method is described to synthesize quaternary salts of chitosan with dimethylsulfate and subsequently cast films. In an attempt to improve both mechanical and hydrophobic characteristics, the chitosan was previously modified by N-alkylation, introducing 4, 8 and 12 carbons moieties into the polymeric chain. Analysis by FTIR and solid-state CP-MAS 13C NMR spectroscopy confirmed the success of both alkylation
Douglas de Britto; Odilio B. G. de Assis
Usefulness of gel-casting method in the fabrication of nonstoichiometric CaZrO{sub 3}-based electrolytes for high temperature application
Hydrogels obtained from lower toxicity monomers of N-(hydroxymethyl)acrylamide and N,N'-methylenebisacrylamide were applied to form nonstoichiometric CaZrO{sub 3}-based electrolytes. A coprecipitation-calcination method with ((NH{sub 4}){sub 2}C{sub 2}O{sub 4}) in concentrated NH{sub 3} aqueous solution was used to synthesise CaZrO{sub 3} involving 51 mol.% CaO (CZ-51) powder. The gas-tight CaZrO{sub 3}-based rods were prepared by the gel-casting method with 45 vol.% suspension and then sintered at 1500 deg. C-2 h. It was found that in low oxygen partial pressure, the nonstoichiometric CaZrO{sub 3} obtained by gel-casting method were pure oxide ion conductors. These samples exhibited comparable electrical conductivity values to isostatically compressed pellets starting from the same powder. The results of experiments on thermochemical stability of CZ-51 gel-cast shapes at high temperatures in air or gas mixtures involving 2-50 vol.% H{sub 2}, as well as the corrosion resistance in exhaust gases from a self-ignition engine were also presented and discussed. The thermal resistance of CaZrO{sub 3} obtained rods against molten nickel or iron was also examined. Based upon these investigations, it is evident that only in hydrogen-rich gas atmospheres can the stability of CaZrO{sub 3} shapes be limited due to the presence of CaO precipitation as a second phase. The nonstoichiometric CaZrO{sub 3} (CZ-51) gel-cast materials were also tested in solid galvanic cells, designed to study thermodynamic properties of oxide materials, important for SOFC and energy technology devices. In this way, the Gibbs energy of NiM{sub 2}O{sub 4}, M = Cr, Fe, at 650-1000 deg. C was determined. The CaZrO{sub 3} involving 51 mol.% CaO gel-cast sintered shapes seems to be promising solid electrolytes for electrochemical oxygen probes in control of metal processing and thermodynamic studies of materials important for the development of the energy industry.
Dudek, Magdalena [AGH - University of Science and Technology, Faculty of Energy and Fuels, 30-059 Cracow (Poland)
Biomimetic membrane arrays on cast hydrogel supports.
Lipid bilayers are intrinsically fragile and require mechanical support in technical applications based on biomimetic membranes. Tethering the lipid bilayer membranes to solid substrates, either directly through covalent or ionic substrate-lipid links or indirectly on substrate-supported cushions, provides mechanical support but at the cost of small molecule transport through the membrane-support sandwich. To stabilize biomimetic membranes while allowing transport through a membrane-support sandwich, we have investigated the feasibility of using an ethylene tetrafluoroethylene (ETFE)/hydrogel sandwich as the support. The sandwich is realized as a perforated surface-treated ETFE film onto which a hydrogel composite support structure is cast. We report a simple method to prepare arrays of lipid bilayer membranes with low intrinsic electrical conductance on the highly permeable, self-supporting ETFE/hydrogel sandwiches. We demonstrate how the ETFE/hydrogel sandwich support promotes rapid self-thinning of lipid bilayers suitable for hosting membrane-spanning proteins. PMID:21526805
Roerdink Lander, Monique; Ibragimova, Sania; Rein, Christian; Vogel, J÷rg; Stibius, Karin; Geschke, Oliver; Perry, Mark; Hķlix-Nielsen, Claus
INTERIOR VIEW WITH CASTING MACHINE AND CASTING FOREMAN OBSERVING OPERATION TO ENSURE MAXIMUM PRODUCTION AND QUALITY. - McWane Cast Iron Pipe Company, Pipe Casting Area, 1201 Vanderbilt Road, Birmingham, Jefferson County, AL
A new type of electrochromic mirror electrode based on reversible uptake of hydrogen in nickel magnesium alloy films is reported. Thin,magnesium-rich Ni-Mg films prepared on glass substrates by cosputtering from Ni and Mg targets are mirror-like in appearance and have low visible transmittance. Upon exposure to hydrogen gas or on reduction in alkaline electrolyte, the films take up hydrogen and become transparent. When hydrogen is removed, the mirror properties are recovered. The transition is believed to result from reversible formation of Mg2NiH4 and MgH2. A thin overlayer of palladium was found to enhance the kinetics of hydrogen insertion and extraction,and to protect the metal surface against oxidation.
Richardson,Thomas J.; Slack, Jonathan L.; Armitage, Robert D.; Kostecki, Robert; Farangis, Baker; Rubin, Michael D.
Usefulness of gel-casting method in the fabrication of nonstoichiometric CaZrO 3-based electrolytes for high temperature application
Hydrogels obtained from lower toxicity monomers of N-(hydroxymethyl)acrylamide and N,N?-methylenebisacrylamide were applied to form nonstoichiometric CaZrO3-based electrolytes. A coprecipitation-calcination method with ((NH4)2C2O4) in concentrated NH3 aqueous solution was used to synthesise CaZrO3 involving 51mol.% CaO (CZ-51) powder. The gas-tight CaZrO3-based rods were prepared by the gel-casting method with 45vol.% suspension and then sintered at 1500░C¢2h. It was found that in
Magdalena Dudek
Humidity sensors based on polymer thin films
Studies on humidity sensors fabricated with organic polymers for the last 10 years are reviewed. Several useful methods for improving the characteristics of humidity sensors based on polymers are proposed. In the case of a resistive-type sensor, cross-linking of hydrophilic polymers or formation of interpenetrated polymer networks with a hydrophobic polymer makes the hydrophilic polymers durable at high humidities. Graft
Y Sakai; Y Sadaoka; M Matsuguchi
Ammonia sensors based on sensitive polyaniline films
We propose a new type of ammonia sensor with polyaniline (electroconducting polymer) as the sensitive element. Such sensors are characterized by high sensitivity, wide range of measured concentrations (1¢2000 ppm) and high stability of electrical parameters. The use of polyaniline ensures high chemical stability of the sensors in oxidizing ambients. A sensor design based on a silicon chip custom-packed into
A. L. Kukla; Yu. M. Shirshov; S. A. Piletsky
High Performance Castings.
The report delineates the factors influencing the characteristics, design, and properties of high-performance castings and the outstanding problems that must be resolved to enhance the reliability and use of these castings. It suggests a number of program...
Slip Casting of ?-Sialon/AlN/BN Powder Carbothermally Prepared by Boron-rich Slag-based Mixture
With boron-rich slag, silica fume, bauxite chalmette and carbon black as starting materials, ?-Sialon/AlN/BN powder was prepared by carbothermal reduction-nitridation. The powder was attrition milled to submicron size and suspended in water. The effects of yttrium oxide as a sintering aid, pH, and addition of deflocculant on the suspensions were study. Optimum slip casting properties, i.e. lowest viscosity values, the highest absolute zeta potential values, the smallest floc size and sediment volume were found at pH 10 for the powder. The suspensions were used to slip cast discs which were sintered in a nitrogen atmosphere at 1700░C for 2h. The strength was about 230MPa, the toughness 3.6 MPaĘm1/2 and the hardness about 13.8GPa.
Jun-bin, Wu; Xiang-xin, Xue; Tao, Jiang; Qing, Zhang
Development of Stronger and More Reliable Cast Austenitic Stainless Steels (H-Series) Based on Scientific and Design Methodology
The goal of this project was to increase the high-temperature strength of the H-Series of cast austenitic stainless steels by 50% and the upper use temperature by 86 to 140 degrees fahrenheit (30 to 60 degrees celsius). Meeting this goal is expected to result in energy savings of 35 trillion Btu/year by 2020 and energy cost savings of approximately $230 million/year. The higher-strength H-Series cast stainless steels (HK and HP type) have applications for the production of ethylene in the chemical industry, for radiant burner tubes and transfer rolls for secondary processing of steel in the steel industry, and for many applications in the heat treating industry, including radiant burner tubes. The project was led by Duraloy Technologies, Inc., with research participation by Oak Ridge National Laboratory (ORNL) and industrial participation by a diverse group of companies.
Pankiw, Roman I; Muralidharan, G. (Murali); Sikka, Vinod K.
Thin film porous membranes based on sol-gel chemistry for catalytic sensors
Nanoporous sol-gel based films are finding a wide variety of uses including gas separations and supports for heterogeneous catalysts. The films can be formed by spin or dip coating, followed by relatively low temperature annealing. The authors used several types of these films as coatings on the Pd alloy thin film sensors they had previously fabricated and studied. The sol-gel
R. C. Hughes; S. V. Patel; M. W. Jenkins; T. J. Boyle; T. J. Gardner; C. J. Brinker
An electron metallographic study of pressure die-cast commercial zinc¢aluminium-based alloy ZA27
The microstructure of ZA27 pressure die-castings was examined by scanning and transmission electron microscopy after ageing\\u000a for 5 years at ambient temperatures. Solidification began with the formation of compact aluminium-rich ?? dendrites and tiny\\u000a rounded ?? particles, followed by the peritectic reaction whereby a zinc-rich ? phase formed around the edges of the primary\\u000a phases. The extremely high cooling rate
Humidity sensors based on aluminum phthalocyanine chloride thin films
In present paper, the fabrication and humidity sensing properties of aluminum phthalocyanine chloride (AlPcCl) thin film based sensors have been presented. AlPcCl thin films with nominal thickness of 50-100 nm are deposited on glass substrates between pre-deposited 50 nm thick aluminum electrodes. The gap between the electrodes is 50 ?m. It is observed that the sensing mechanism is based on the variation of resistance with change in humidity. For change in relative humidity (RH) from 20% to 92%, the change in resistance is 22.2ū102 and 13.3ū102 times respectively for the sensors having 50 nm and 100 nm thick AlPcCl films, while the 1 h annealing of these samples at 100 ░C results in increase in average sensitivity up to 30% and 40% respectively. The consequence of measuring frequency and absorption-desorption behavior of the humidity sensor are also discussed in detail. It is also observed that annealing results in minimization of hysteresis and reduction of recovery time (?rec) up to 63% and 70% in sensors with 50 nm and 100 nm thick organic film respectively, while the response (?res) time is 10 s for both the sensors.
Chani, Muhammad Tariq Saeed; Karimov, Kh. S.; Ahmad Khalid, F.; Raza, Kabeer; Umer Farooq, Muhammad; Zafar, Qayyum
LLNL casting technology
Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US compentiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience casting metals and nonmetals; advanced measurement and instrumentation systems. Department of Energy (DOE) funding provides the leverage for LLNL to collaborate with industrial partners to share this advanced casting expertise and technology. At the same time, collaboration with industrial partners provides LLNL technologists with broader insights into casting industry issues, casting process data, and the collective, experience of industry experts. Casting R&D is also an excellent example of dual-use technology; it is the cornerstone for increasing US industrial competitiveness and minimizing waste nuclear material in weapon component production. Annual funding for casting projects at LLNL is $10M, which represents 1% of the total LLNL budget. Metal casting accounts for about 80% of the funding. Funding is nearly equally divided between development directed toward US industrial competitiveness and weapon component casting.
Shapiro, A.B.; Comfort, W.J. III [eds.
Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US competiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience casting metals and nonmetals; advanced measurement and instrumentation systems. Department of Energy (DOE) funding provides the leverage for LLNL to collaborate with industrial partners to share this advanced casting expertise and technology. At the same time, collaboration with industrial partners provides LLNL technologists with broader insights into casting industry issues, casting process data, and the collective experience of industry experts. Casting R&D is also an excellent example of dual-use technology; it is the cornerstone for increasing US industrial competitiveness and minimizing waste nuclear material in weapon component production. Annual funding for casting projects at LLNL is $10M, which represents 1% of the total LLNL budget. Metal casting accounts for about 80% of the funding. Funding is nearly equally divided between development directed toward US industrial competitiveness and weapon component casting.
Shapiro, A. B.; Comfort, W. J., III
The "flatback" cast.
A properly applied above-elbow cast in a child presents difficulties not seen in adults. Because of the differences in anatomy, physiology, and compliance, children can benefit from modification of the standard above-elbow cast. We report on a method of application of the "flatback" cast to address these concerns. PMID:8421630
Black, G B; Klippenstein, N L
Casting and Molding
This activity was designed for blind learners, but all types of learners can explore the process used to cast and mold molten metal, glass, and plastics. Using gelatin, the learner will work with a variety of molds to create castings. When the shapes are unmolded, the learner can tactually explore the casts.
Blind, Perkins S.
Advanced Cast Aluminum Alloys.
A recent advancement in cast aluminum alloys has demonstrated that complex shapes can be cast from a microalloyed Al-Cu alloy in dry sand molds with chills and that these castings can be heat treated to produce mechanical and physical properties nearly co...
A. P. Druschitz J. Griffin
Grease for Casting Aluminum Alloys under Pressure.
A grease is described for use with die casting molds and adjacent hot parts of casting machines consisting of an oxidized petrolatum (containing smaller than or equal to 16% hydroxy acids) base material aluminum powder 1.5-1.7, flaky graphite 0.5-3.0, and...
A. I. Dintses G. B. Solomonik N. N. Belousov R. N. Osher T. M. Komissarova
Yield Improvement in Steel Casting (Yield II)
This report presents work conducted on the following main projects tasks undertaken in the Yield Improvement in Steel Casting research program: Improvement of Conventional Feeding and Risering Methods, Use of Unconventional Yield Improvement Techniques, and Case Studies in Yield Improvement. Casting trials were conducted and then simulated using the precise casting conditions as recorded by the participating SFSA foundries. These results present a statistically meaningful set of experimental data on soundness versus feeding length. Comparisons between these casting trials and casting trials performed more than forty years ago by Pellini and the SFSA are quite good and appear reasonable. Comparisons between the current SFSA feeding rules and feeding rules based on the minimum Niyama criterion reveal that the Niyama-based rules are generally less conservative. The niyama-based rules also agree better with both the trials presented here, and the casting trails performed by Pellini an d the SFSA years ago. Furthermore, the use of the Niyama criterion to predict centerline shrinkage for horizontally fed plate sections has a theoretical basis according to the casting literature reviewed here. These results strongly support the use of improved feeding rules for horizontal plate sections based on the Niyama criterion, which can be tailored to the casting conditions for a given alloy and to a desired level of soundness. The reliability and repeatability of ASTM shrinkage x-ray ratings was investigated in a statistical study performed on 128 x-rays, each of which were rated seven different times. A manual ''Feeding and Risering Guidelines for Steel Castings' is given in this final report. Results of casting trials performed to test unconventional techniques for improving casting yield are presented. These use a stacked arrangement of castings and riser pressurization to increase the casting yield. Riser pressurization was demonstrated to feed a casting up to four time s the distance of a non-pressurized riser, and can increase casting yield by decreasing the required number of risers. All case studies for this projects were completed and compiled into an SFSA Technical Report that is submitted part of this Final Report
Richard A. Hardin; Christoph Beckermann; Tim Hays
Fluorescent detection of an anthrax biomarker based on PVA film.
Due to the dangerous nature of anthrax, the development of a cost-effective, sensitive and field-portable sensor for the anthrax biomarker--calcium dipicolinate (CaDPA)--is of exceptional significance for both military and civilian use. Herein, a flexible polymer-film-based ratiometric sensor for detecting CaDPA was demonstrated. A reference dye and a probe ligand were covalently immobilized onto the film surface through a highly selective and efficient "click chemistry" reaction. The reference dye, whose fluorescence intensity does not change with varying amounts of CaDPA, offers a non-interfering internal calibration. The ethylenediaminetetraacetic acid (EDTA)-based ligand binds with Eu(III) and serves as the probe. In the absence of CaDPA, the film sensor exhibited almost no red fluorescence because the Eu(III) ions themselves give no emission without sensitization by CaDPA owing to the small molar absorption coefficients of Eu(III) ions. The presence of CaDPA induces a significantly enhanced emission intensity of the sensor, and thereby enables the film as a ratiometric sensor for CaDPA. This sensor can selectively detect CaDPA in water with a detection limit of 100 nM. Moreover, this sensor exhibited strong anti-interfering capability, it can not only be used in milieus that contain various amino acids and some biologically-abundant cations, but can also be usable in some biological fluids such as urine and serum. This test-paper-like film sensor is suitable for portable field analysis and needs no extra protective measures during transport due to its flexibility, and it can easily be separated from the analyte solution after the detection. PMID:21796290
Ma, Boling; Zeng, Fang; Zheng, Fangyuan; Wu, Shuizhu
Thermal behavior of hafnium-based ultrathin films on silicon
We report here on the thermodynamical stability of ultrathin, hafnium-based dielectric films, namely hafnium oxide (HfO2), silicate (HfSixOy), and aluminum silicate (AlHfxSiyOz), deposited on silicon. These materials are promising candidates to replace the well established silicon oxide and oxynitride as gate dielectric materials in advanced Si-based complementary metal-oxide-semiconductor technology. Since there are mandatory requirements on the gate dielectric material, hafnium oxide is currently being modified, by adding silicon and aluminum into the matrix, increasing its thermal stability, and improving its electrical properties. Diffusion-reaction during thermal processing was investigated using isotopic substitution together with ion beam techniques such as Rutherford backscattering spectrometry, narrow nuclear resonance profiling, and nuclear reaction analysis. The chemical changes in the films were accessed by x-ray photoelectron spectroscopy.
Pezzi, R. P.; Morais, J.; Dahmen, S. R.; Bastos, K. P.; Miotti, L.; Soares, G. V.; Baumvol, I. J. R.; Freire, F. L.
Edible films made from gelatin, soluble starch and polyols, Part 3
The thermal and mechanical properties of edible films based on blends of gelatin with soluble starch plasticized with water, glycerol or sugars were investigated. Two different methods, known as æthe high temperatureÆ and æthe low temperatureÆ methods, consisting of casting aqueous solutions of blends at 60 and 20 ░C, respectively, were employed for the preparation of films. With increasing water,
I. Arvanitoyannis; E. Psomiadou; A. Nakayama; S. Aiba; N. Yamamoto
Influence of plasticizers and crosslinking on the properties of biodegradable films made from sodium caseinate
Plasticized protein films were prepared by the casting method from water solution of sodium caseinate and plasticizers with the aim to obtain environmentally friendly materials for packaging applications. Mechanical properties (tensile strength, elongation and YoungÆs modulus) of caseinate based films were determined versus ratio of protein to plasticizer, plasticizer type and relative humidity conditions. Among the different polyol-type plasticizers tested,
Jean-Luc Audic; Bernard Chaufer
Antibacterial activity against E. coli O157:H7, physical properties, and storage stability of novel carvacrol-containing edible tomato films.
Edible films containing plant antimicrobials are gaining importance as potential treatment to extend product shelf life and reduce risk of pathogen growth on contaminated food surfaces. The main objective of the present study was to evaluate the antimicrobial activities, storage stabilities, and physical-chemical-mechanica1 properties of novel edible films made from tomatoes containing carvacrol, the main constituent of oregano oil. The antimicrobial activities against E. coli O157:H7 and the stability of carvacrol were evaluated during the preparation and storage of tomato-based films made by 2 different casting methods, continuous casting and batch casting. Antimicrobial assays of tomato films indicated that optimum antimicrobial effects occurred with carvacrol levels of approximately 0.75% added to tomato purees before film preparation. HPLC analysis of the films indicated that the carvacrol concentrations and bactericidal effect of the films remained unchanged over the storage period of up to 98 d at 5 and 25 degrees C. Carvacrol addition to the tomato puree used to prepare the films increased water vapor permeability of tomato films. The continuous method for casting of the films appears more suitable for large-scale use than the batch method. This 1st report on tomato-based edible antimicrobial tomato films suggests that these films have the potential to prevent adverse effects of contaminated food and promote human health associated with the consumption of tomatoes. PMID:18803723
Du, W-X; Olsen, C W; Avena-Bustillos, R J; McHugh, T H; Levin, C E; Friedman, Mendel
Immunosensor systems with the Langmuir-film-based fluorescence detection
A method is developed for detecting protein antigens for fluorescent immunoassay using a model system based on the technique for preparation of Langmuir films. Fluorescein isothiocyanate and donor-acceptor energy-transfer pairs of markers (the Yb complex of tetraphenyl porphyrin - benzoyl trifluoroacetoneisothiocyanate and derivatives of tetra(carboxyphenyl) porphyrin - cyanine dye containing a five-membered polyene chain), which were nor studied earlier, were used as markers for detecting the binding of an antigen on the surface of Langmuir films of antibodies. Fluorescence was detected in the near-IR region (for the first pair) and in the visible spectral range (for the second pair). To reduce the nonspecific sorption of a protein (antigen), a method was proposed for the preparation of a nonpolar surface by applying an even number of layers of stearic acid as a substrate for the Langmuir - Blodgett film. A high sensitivity of model systems to a protein antigen in solution was achieved ({approx}10{sup -11} M), the assay time being 6 - 8 min. The model system with the first donor - acceptor pair was tested in analysis of the blood plasma. The fluorescence of the Dy{sup 3+}, Tm{sup 3+}, and Yb{sup 3+} complexes of tetraphenyl porphyrin sensitised by diketonate complexes of lanthanides was studied for the first time and the enhancement of the IR fluorescence of these complexes in a Langmuir film was demonstrated. (papers devoted to the memory of academician a m prokhorov)
Chudinova, G K; Nagovitsyn, I A; Savranskii, V V [Natural Science Center, A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Karpov, R E [Photochemistry Center, Russian Academy of Sciences, Moscow (Russian Federation)
Biosensors based on the thin-film magnetoresistive sensors
The review considered the state-of-the-art in the development of devices for detection of the agents of disease on the basis\\u000a of the Lab on a chip (LOC) biosensors whose detecting element is a matrix of thin-film anisotropic magnetoresistive (AMR),\\u000a magnetoresistive (GMR), or spin-tunnel magnetoresistive (STMR) magnetic field sensors based on the multi-chip planar technology.\\u000a Data were presented on the nanospherical
S. I. Kasatkin; N. P. VasilÆeva; A. M. MuravÆev
Acetone sensor based on Film Bulk Acoustic Resonator
This paper described acetone sensing using ZnO based Film Bulk Acoustic Resonator (FBAR). The resonant frequency of the FBAR increased as the concentration of acetone increased. The detection limit of acetone was around 4 ppm. The density decrease of the ZnO induced by releasing carbon dioxide generated from the reaction between acetone and the adsorbed oxygen ions on the ZnO
Xiaotun Qiu; Rui Tang; Jie Zhu; Hongyu Yu; Jon Oiler; Ziyu Wang
Film Bulk Acoustic-Wave Resonator based radiation sensor
This paper describes a high-energy electromagnetic wave radiation detection device using zinc oxide (ZnO) based Film Bulk Acoustic-Wave Resonator (FBAR). The resonant frequency of the FBAR decreased after gamma radiation, with the peak sensitivity of 9.3 kHz\\/krad and minimum detectable dosage of 218 rad occurring at the lowest experimental dose of 20 krad (all dosages are calibrated with ZnO), while
Jonathon Oiler; Xiaotun Qiu; Jie Zhu; Ziyu Wang; Cunjiang Yu; Hugh Barnaby; Keith Holbert; Hongyu Yu
Biosensors based on immobilization of biomolecules by electrogenerated polymer films
The concept and potentialities of electrochemical procedures of biomolecule immobilization are described. The entrapment of\\u000a biomolecules within electropolymerized films consists of the application of an appropriate potential to an electrode soaked\\u000a in an aqueous solution containing monomer and biomolecules. This method of biosensor construction is compared with a two-step\\u000a procedure based on the adsorption of an aqueous amphiphilic pyrrole monomer-biomolecule
Serge Cosnier
A Novel Potentiometric Glucose Biosensor Based on Polyaniline Semiconductor Films
Application of polyaniline semiconductor films to potentiometric biosensor development provides certain advantages comparing with the known systems. Using self-doped polyaniline instead of common polymer as pH transducer the stable potentiometric response of 70 mV\\/pH was obtained. Taking as an example glucose biosensor we showed that polyaniline based electrode possessed three-four fold increased potential shift than glucose-sensitive field-effect transistor did. One
Elena E. Karyakina; Lylia V. Neftyakova; Arkady A. Karyakin
Electrical and thermal transport in nanotube based thin film transistors
Thin-film transistors (TFTs) based on networks of carbon nanotubes (CNTs) or silicon nanowires (NW) promise improved performance and novel applications in microelectronics and macroelectronics. Network transistors suggest the possibility of low voltage, highly reliable, high-speed (>GHz) flexible plastic electronics with potential applications in displays, e-paper, e-clothing, biological and chemical sensing, conformal radar, and others. Despite many promising experimental demonstrations, a
Satish Kumar
Biochemical sensors based on thin-film waveguide
Biochemical sensors based on thin-film waveguide are proposed which can measure the concentration of sample solutions. In order to investigate the applicability of these sensors to Ca2+ and glucose measurement, the waveguide was fabricated with 3 layers: the substrate (pyrex glass), the waveguide layer (sputtered with Corning 7059 glass) and sample layer having PVC sensing membrane and\\/or sample chamber. We
Haruyuki MINAMITANI; Kyungho KIM; Kunihiro MATSUMOTO
A comparison of mechanical properties of all-ceramic alumina dental crowns prepared from aqueous- and non-aqueous-based tape casting.
Alumina-glass dental composites were prepared by aqueous- and non-aqueous-based tape casting and sintering at 1120 degrees C, followed by glass infiltration at 1100 degrees C. Flexural strength and fracture toughness of the composites were investigated in terms of influence of tape constituents, namely, alumina powder, binder, and plasticizer on the mechanical properties. For the alumina-glass composites prepared from the aqueous-based tapes, both strength and toughness increased with increasing alumina fraction ratio in tape constituents including organic substances, a/a+o, and binder content ratio in binder/binder + plasticizer mixture, b/b+p. For the composites prepared from the non-aqueous-based tapes, on the other hand, both strength and toughness increased with increasing the a/a+o ratio but decreased with increasing the b/b+p ratio. These observations were consistent with influence of the constituents on mean alumina particle distance in tapes, suggesting that high strength of the glass infiltrated alumina composites is related to toughening by crack bowing. The optimized strength of the aqueous and nonaqueous tape cast composites was 559 and 508 MPa, and the fracture toughness was 3.3 and 3.1 MPam(1/2), respectively. PMID:10898872
Kim, D J; Lee, M H; Lee, D Y; Han, J S
Antimicrobial food packaging film based on the release of LAE from EVOH.
The aim of this work was to develop antimicrobial films for active packaging applications containing the natural antimicrobial compound LAE (lauramide arginine ethyl ester) in EVOH copolymers with different mol % ethylene contents (i.e. EVOH-29 and EVOH-44). EVOH-29 and EVOH-44 films were made by casting and incorporating 0.25%, 1%, 5%, and 10% LAE in the film forming solution (w/w with respect to polymer weight). Previously, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of LAE against Listeria monocytogenes, Escherichia coli, and Salmonella enterica were determined by a microdilution assay. The antimicrobial activity of the resulting films was tested in vitro against these microorganisms in liquid culture media. The activity of the films was also evaluated over time. The results showed that films containing 5% and 10% LAE produced total growth inhibition and viable counts decreased with 0.25% and 1% LAE. Finally, the effectiveness of the films was tested by applying them to an infant formula milk inoculated with L. monocytogenes and S. enterica and stored for 6 days at 4░C. The application of films with LAE to infant formula milk inoculated with L. monocytogenes reduced at the end of storage period about 4 log in case of 10% LAE and with S. enterica reduced 3.74 log and 3.95 log with EVOH 29 5% and 10%, respectively, and EVOH-44 5% and 10% LAE reduced 1 log and 3.27 log, respectively, at the end of storage. The antimicrobial capacity of EVOH-29 films was greater than that of EVOH-44 films in all the cases tested. In general, the films were more effective in inhibiting the growth of L. monocytogenes than S. enterica, this inhibition being more acute at the end of the storage time. PMID:22640726
Muriel-Galet, Virginia; L¾pez-Carballo, Gracia; Gavara, Rafael; Hernßndez-Mu±oz, Pilar
Thermal Aging Effects on the Mechanical Properties of As-Cast Ni3Al-based Alloy
A series of tensile tests were conducted at room and elevated temperatures on specimens of the alloy known as IC221M (Ni-8.2Al-7.6Cr-1.5Mo-2.1Zr, wt%). Specimens were tested in the as-cast condition or after aging in either air or Ar for up to 1000 h at 900-1100 XC. Room temperature yield strength decreased continuously with aging time at 900 XC from the as-cast value of 530 MPa to 320 MPa after 1000 h. A similar trend was found for hardness. The strength reductions with aging time at 900 XC were similar for aging in either air or Ar. For aging at 1050 XC and 1100 XC, aging in air caused significant strength loss that was attributed to aggressive oxidation. The room temperature yield strength of specimens aged in Ar increased for aging at 1050 XC and 1100 XC. Microhardness testing also showed that specimens aged at 1100 XC had higher hardness than those aged at 900 XC. Analysis using equilibrium thermodynamics suggested that the increases of yield strength and hardness resulted from increasing the amount of fine S precipitation in the alloy matrix. For testing at elevated temperatures, the as-cast alloy had room temperature yield strength of 530 MPa that increased continuously up to a value of 650 MPa at 700 XC. Aging in Ar for 1000 h at 900 XC resulted in a room temperature yield strength of 320 MPa that increased to 560 MPa at 700 XC and decrease slightly to 550 MPa at 900 XC. Aging in Ar for 1000 h at 1100 XC produced room temperature yield strength of 435 MPa that increased to 550 MPa at 500 XC and decreased continuously at high test temperatures. The behavior of these specimens was also rationalized using equilibrium thermodynamics to estimate the fractions of coarse and fine S particles in the microstructures.
Lee, Dongyun [ORNL; Santella, Michael L [ORNL
The effects of Cr, Co, Al, Mo and Ta on the cyclic oxidation behavior of a prototype cast Ni-base superalloy based on a 2 sup 5 composite statistically designed experiment
A series of cast Ni-base ╬│\\/╬│Ō▓ Superalloys with nominally fixed levels of 1 w\\/o Ti, 2w\\/o W, 1 w\\/o Nb, .10 w\\/o Zr, .12 w\\/o C and .01B w\\/o were systematically varied at selected levels of Co, Cr, Mo, Ta, and Al. The alloy compositions were based on a full 2ŌüĄ-fractional statistical design supplemented by 5 x 2 star point
Measurement of Thermoelectric Properties of Amorphous Silicon Based Thin Films
It is important to understand thermal transport behavior in materials for technological and fundamental physics applications. Many efforts have been made in the past for explaining thermal conduction in solids. It has been observed that thermal transport properties may change with reducing size of the sample, especially as sample size approaches the nanoscale regime. The deviation in these properties, mainly in thermal conductivity, may change the choice of the material for different applications such as thermoelectricity. Thermoelectric materials are a possible source of sustainable energy and can play an important role in the fight against the present energy crisis. Recently, better thermoelectric materials have become available in bulk form as compared to thin film form, with higher figure of merit (ZT = alpha2sigma T=k). ZT is a dimensionless quantity which is used to characterize the performance of thermoelectric materials in terms of the efficiency. Figure of merit (ZT) depends on three fundamental properties including thermal conductivity (k) which is challenging to measure for thin films. This is due to several reasons such as large or more than one background contribution and radiation heating above 100 K. Precise measurements of thermopower (alpha) also become critical for thin films in order to calculate ZT and the efficiency. For devices which rely on thin film technology it is important to have an accurate knowledge of how a material behaves as a thin film in a wide range of temperature. All three of these properties are a function of charge carrier concentration as well as of temperature. In my thesis, I will present novel experimental techniques and measurements of thermoelectric properties in amorphous based thin films over a wide range of temperature. Amorphous Si alloys are expected to have high efficiency for thermoelectric purposes because of their low thermal conductivity and the fact that we can control the charge carrier concentration for optimized thermopower(alpha) and electrical conductivity(sigma) by controlling the dopant concentration. Thermal properties of pure amorphous thin films are also potentially useful in micro- or nano fabrication techniques such as electrically insulating integrated devices. ii
Sultan, Rubina
Effect of Pressure Difference on the Quality of Titanium Casting
In casting titanium using a two-compartment casting machine, Her° et al. (1993) reported that the pressure difference between the melting chamber and the mold chamber affected the soundness of the castings. This study tested the hypothesis that differences in pressure produce castings with various amounts of porosity and different mechanical properties values. Plastic dumbbell-shaped patterns were invested with an alumina-based,
I. Watanabe; J. H. Watkins; H. Nakajima; M. Atsuta; T. Okabe
Sulfonated and crosslinked polyphosphazene-based proton-exchange membranes
Proton-exchange membranes, for possible use in H2\\/O2 and direct methanol fuel cells have been fabricated from poly[bis(3-methylphenoxy)phosphazene] by first sulfonating the base polymer with SO3 and then solution-casting thin films. The ion-exchange capacity of the membrane was 1.4mmol\\/g. Polymer crosslinking was carried out by dissolving benzophenone photoinitiator in the membrane casting solution and then exposing the resulting films after solvent
Qunhui Guo; Peter N. Pintauro; Hao Tang; Sally O'Connor
Effect of acid and alkaline solubilization on the properties of surimi based film
Prodpran, T. and Benjakul, S. Effect of acid and alkaline solubilization on the properties of surimi based film Songklanakarin J. Sci. Technol., 2005, 27(3) : 563-574 The effect of acid and alkaline solubilizing processes on the properties of the protein based film from threadfin bream surimi was investigated. Surimi films prepared from both processes had the similar light transmission, tensile
Thummanoon Prodpran; Soottawat Benjakul
The production and evaluation of metal-matrix composite castings produced by a pressure-assisted investment casting process
A process for the production of aluminium alloy metal-matrix composites (MMCs) by the liquid metal infiltration route is presented. This process was based on investment casting to enhance its ability to cast complex shapes by the fibre preform infiltration method. Squeeze casting has been the most popular route for producing such composites due to its ability to provide high positive
C. S. Lim; A. J. Clegg
Naphthacene Based Organic Thin Film Transistor With Rare Earth Oxide
Naphthacene based organic thin film transistors (OTFTs) have been fabricated using La{sub 2}O{sub 3}, as the gate insulator. All the OTFTs have been fabricated by the process of thermal evaporation in vacuum on perfectly cleaned glass substrates with aluminium as source-drain and gate electrodes. The naphthacene film morphology on the glass substrate has been studied by XRD and found to be polycrystalline in nature. The field effect mobility, output resistance, amplification factor, transconductance and gain bandwidth product of the OTFTs have been calculated by using theoretical TFT model. The highest value of field effect mobility is found to be 0.07x10{sup -3} cm{sup 2}V{sup -1}s{sup -1} for the devices annealed in vacuum at 90 deg. C for 5 hours.
Konwar, K. [Department of Physics, Digboi College, Digboi-786171, Assam (India); Baishya, B. [Department of Physics, Dibrugarh University, Dibrugarh-786004, Assam (India)
Naphthacene based organic thin film transistors (OTFTs) have been fabricated using La2O3, as the gate insulator. All the OTFTs have been fabricated by the process of thermal evaporation in vacuum on perfectly cleaned glass substrates with aluminium as source-drain and gate electrodes. The naphthacene film morphology on the glass substrate has been studied by XRD and found to be polycrystalline in nature. The field effect mobility, output resistance, amplification factor, transconductance and gain bandwidth product of the OTFTs have been calculated by using theoretical TFT model. The highest value of field effect mobility is found to be 0.07ū10-3 cm2V-1s-1 for the devices annealed in vacuum at 90░ C for 5 hours.
Konwar, K.; Baishya, B.
Polycrystalline Silicon Films and Thin-Film Transistors Using Solution-Based Metal-Induced Crystallization
Polycrystalline silicon (poly-Si) films consisting of dish-like and wadding-like domains were obtained with solution-based metal-induced crystallization (SMIC) of amorphous silicon. The Hall mobility of poly-Si was much higher in dish-like domains than in wadding-like domains. Thin-film transistors (TFTs) have been prepared using those two kinds of poly-Si films as the active layer, followed by the phosphosilicate glass (PSG) nickel gettering. The field effect mobility of dish-like domain poly-Si TFTs and wadding-like poly-Si TFTs were 70 ~ 80 cm2/V Ę s and 40 ~ 50 cm2/V Ę s, respectively. With a multi-gate structure, the leakage current of poly-Si TFTs was reduced by 1 to 2 orders of magnitude. In addition, the gate-induced drain leakage current (GIDL) and uniformity of the drain current distribution were also improved. P-type TFTs fabricated using SMIC exhibited excellent reliability.
Meng, Zhiguo; Zhao, Shuyun; Wu, Chunya; Zhang, Bo; Wong, Man; Kwok, Hoi-Sing
Wet etching of sputtered tantalum thin films in NaOH and KOH based solutions
In this paper, a wet chemical etching technique to selectively etch tantalum thin film in sodium hydroxide and potassium hydroxide\\u000a based solutions was developed. Tantalum thin films were deposited by a DC-magnetron sputtering technique on silica and yttria-stabilized\\u000a zirconia (YSZ) substrates. After deposition, the films were etched in hot NaOH\\/ H2O2 and KOH\\/H2O2 based solutions with Au\\/Cr film as a
S. Sood; R. Peelamedu; K. B. Sundaram; E. Dein; R. M. Todi
Process Modeling of Low-Pressure Die Casting of Aluminum Alloy Automotive Wheels
Although on initial inspection, the aluminum alloy automotive wheel seems to be a relatively simple component to cast based on its shape, further insight reveals that this is not the case. Automotive wheels are in a select group of cast components that have strict specifications for both mechanical and aesthetic characteristics due to their important structural requirements and their visibility on a vehicle. The modern aluminum alloy automotive wheel continues to experience tightened tolerances relating to defects to improve mechanical performance and/or the physical appearance. Automotive aluminum alloy wheels are assessed against three main criteria: wheel cosmetics, mechanical performance, and air tightness. Failure to achieve the required standards in any one of these categories will lead to the wheel either requiring costly repair or being rejected and remelted. Manufacturers are becoming more reliant on computational process modeling as a design tool for the wheel casting process. This article discusses and details examples of the use of computational process modeling as a predictive tool to optimize the casting process from the standpoint of defect minimization with the emphasis on those defects that lead to failure of aluminum automotive wheels, namely, macroporosity, microporosity, and oxide films. The current state of applied computational process modeling and its limitations with regard to wheel casting are discussed.
Reilly, C.; Duan, J.; Yao, L.; Maijer, D. M.; Cockcroft, S. L.
Improving Metal Casting Process
Don Sirois, an Auburn University research associate, and Bruce Strom, a mechanical engineering Co-Op Student, are evaluating the dimensional characteristics of an aluminum automobile engine casting. More accurate metal casting processes may reduce the weight of some cast metal products used in automobiles, such as engines. Research in low gravity has taken an important first step toward making metal products used in homes, automobiles, and aircraft less expensive, safer, and more durable. Auburn University and industry are partnering with NASA to develop one of the first accurate computer model predictions of molten metals and molding materials used in a manufacturing process called casting. Ford Motor Company's casting plant in Cleveland, Ohio is using NASA-sponsored computer modeling information to improve the casting process of automobile and light-truck engine blocks.
Study of carbon nanotubes based Polydimethylsiloxane composite films
Thanks to their remarkable characteristics, carbon nanotubes (CNTs) have fields of applications which are growing every day. Among them, the use of CNTs as filler for polymers is one of the most promising. In this work we report on Polydimethylsiloxane (PDMS) composites with different weight percentages (0.0% to 3.0%) of multiwall carbon nanotubes (MWCNTs) having diameter 10-30 nm and length 20-30 ?m. To achieve optimum dispersion of CNTs in PDMS matrix, high speed mechanical stirring and ultrasonication were performed. By using the doctor blade technique, 70 ?m thick uniform films were produced on glass. They were subsequently thermally cured and detached from the glass to get flexible and self standing films. The surface morphological study done by FESEM, shows that CNTs are well dispersed in the PDMS. Raman spectroscopy and FTIR were used to investigate the possible structural changes in the polymer composite. To examine the optical behavior UV-VIS spectroscopy was employed in both specular and diffused modes. A linear increase in absorption coefficient is found with the increasing percentage of CNTs while the transmittance decreases exponentially. The results confirm the dependence of optical limiting effect on the quantity of MWCNTs. Based on optical study, MWCNTs/PDMS composite films can be a promising material to extend performances of optical limiters against laser pulses, which is often required in lasing systems.
Shahzad, M. I.; Giorcelli, M.; Shahzad, N.; Guastella, S.; Castellino, M.; Jagdale, P.; Tagliaferro, A.
Die-casting powdery mold releasing agent
US Patent & Trademark Office Database
A die-casting powdery mold releasing agent according to this invention is a mold releasing agent comprising a mixture of powdery or granulated mold releasing base material composed of an inorganic compound as used for lubricant in a solid form and an organic compound giving adhesive property to the mold releasing agent, the both having powdery or granulated configurations, or configurations in which the organic compound is covered on the mold releasing base material. The mold releasing agent allows production of castings of high quality, in the die-casting method with good workability and without worsening environmental situations.
Functional properties and antifungal activity of films based on gliadins containing cinnamaldehyde and natamycin.
Gliadin films cross-linked with cinnamaldehyde (1.5, 3, and 5%) and incorporated with natamycin (0.5%) were prepared by casting, and their antifungal activity, water resistance, and barrier properties were characterized. Incorporation of natamycin gave rise to films with greater water uptake, weight loss and diameter gain, and higher water vapor and oxygen permeabilities. These results may be associated to a looser packing of the protein chains as a consequence of the presence of natamycin. The different cross-linking degree of the matrices influenced the natamycin migration to the agar test media, increasing from 13.3 to 23.7 (?g/g of film) as the percentage of cinnamaldehyde was reduced from 5% to 1.5%. Antifungal activity of films was assayed against common food spoilage fungi (Penicillium species, Alternaria solani, Colletotrichum acutatum). The greatest effectiveness was obtained for films containing natamycin and treated with 5% of cinnamaldehyde. The level of cinnamaldehyde reached in the head-space of the test assay showed a diminishing trend as a function of time, which was in agreement with fungal growth and cinnamaldehyde metabolization. Developed active films were used in the packaging of cheese slices showing promising results for their application in active packaging against food spoilage. PMID:24412960
Balaguer, Mari Pau; Fajardo, Paula; Gartner, Hunter; Gomez-Estaca, Joaquin; Gavara, Rafael; Almenar, Eva; Hernandez-Munoz, Pilar
Caste and Language in Jaffna Society.
Caste and language in the Jaffna Hindu Tamil society were correlated based on data collected from sample villages in the Jaffna peninsula, where the political and economic ascendancy of the landlords was very dominant in the recent past. (SW)
Suseendirarajah, S.
Effects of Vanadium Doping on Resistive Switching Characteristics and Mechanisms of Based Memory Films
The effects of vanadium doping on resistive switching (RS) characteristics and mechanisms of RF-sputtered SrZrO3 (SZO)-based thin films are investigated in this paper. The physical and electrical properties of SZO-based thin films are modulated by vanadium doping due to the Zr4+ ion replaced by V5+, further affecting the RS parameters of SZO-based thin films. The conduction mechanisms of SZO-based thin
Meng-Han Lin; Ming-Chi Wu; Chen-Hsi Lin; Tseung-Yuen Tseng
Optical switch based on nanocrystalline VOx thin film
An optical switch is fabricated based on nanocrystalline vanadium oxide (VOx) thin film using micromachining technology. An "on" state with semiconducting phase to an "off" state with metallic phase is controlled by applying a DC power to Aurum electrodes of the optical switch. The optical switching performance for the fabricated device is investigated at optical communication wavelength of 1.55?m. The heater power requires to achieve switching action is about 15mW. The testing results show that the extinction ratio and switching response time are 14dB and 2ms, respectively.
Chen, Xiqu; Dai, Jun
Predicting initial treatment failure of fiberglass casts in pediatric distal radius fractures: utility of the second metacarpal-radius angle
Purpose Recent literature comparing the effectiveness of above-elbow and below-elbow plaster casts appears to suggest that either cast type offers adequate immobilization for distal radius and ulna fractures. The idea that an appropriate mold placed on the cast is the most significant determinant of successful immobilization and, thereby, patient outcome has also been elucidated. The purpose of this study was to compare the effectiveness of above-elbow versus below-elbow fiberglass casts in maintaining distal radius/ulna fracture reduction and to identify factors associated with treatment failures. Methods We reviewed the radiographs and clinical data of 253 children with distal third forearm fractures requiring reduction under conscious sedation or a hematoma block. Outcome measures included rates of re-manipulation, loss of reduction, and cast complications. Results One hundred and nineteen children were treated with below-elbow fiberglass casts and 134 were treated with above-elbow fiberglass casts based on a clinical pathway created before the study period. There were no differences between the two groups in age, weight, fracture pattern, percentage of both-bone fractures, and initial fracture angulation. Of the 253 fractures in the study, 38 (15%) were considered to have less than ideal outcomes. There were no differences between the æidealÆ and ænon-idealÆ groups in age, fracture pattern, presence of ulna fracture, cast index, or cast type. All immediate post-reduction measures (anterior-posterior [AP] and lateral displacement/angulation) were significantly correlated with treatment outcome, except angulation on AP films. The magnitude of reduction as measured by a newly described variable, the angle between the second metacarpal and long axis of the radius in the AP projection, was significantly correlated with treatment failure (rĀ=Ā?0.139, PĀ=Ā0.027). Binary logistic regression was performed and demonstrated that the success of the reduction, as determined by the AP radiograph second metacarpal-radius angle, was a significant predictor of treatment success (odds ratio 1.6, PĀ<Ā0.001). Also, the change in lateral view angulation post-reduction was a significant predictor of treatment failure based on regression (odds ratio 1.2, PĀ=Ā0.004). The above-elbow cast group had a slightly greater cast index (0.80) compared to the below-elbow cast group (0.77) (PĀ=Ā0.003). Whereas below-elbow fiberglass casts appear to be equally effective in immobilizing pediatric distal third forearm fractures as above-elbow fiberglass casts, it seems that they have an increased risk for poor molding, particularly with regards to ulnar deviation. We did not find an association between the treatment æfailureÆ and cast index, likely because the number of poor molds (cast index >0.8) was nearly equal in each group (above-elbow with 61 and below-elbow with 45). However, the mold seen on the AP radiograph as determined by the second metacarpal-radius angle was a reproducible radiographic predictor of treatment success. If molded with ulnar deviation (second metacarpal-radius angle >0░), the outcome was considered to be ideal in 86.7% of cases compared to only 74.4% when it was <0░. Conclusion We agree with prior studies suggesting the equal efficacy of below-elbow versus above-elbow casts in distal radius and ulna fracture treatment using either plaster or fiberglass, but wish to emphasize the importance of not only the cast index, but also the ulnar deviation mold (for most dorsally displaced fractures), as measured by the second metacarpal-radius angle.
Edmonds, Eric W.; Capelo, Roderick M.; Stearns, Philip; Bastrom, Tracey P.; Wallace, C. Douglas
Growth-Induced Optical Birefringence in LPE-Grown Bi-Based Iron Garnet Films
A growth-induced optical birefringence has been observed in Bi-based iron garnet films grown by LPE method. The lattice misfit dependence of the birefringence, which is estimated from the phase mismatch between TE and TM modes in the garnet thin film waveguide, shows the existence of optical anisotropy that can not be attributed to the stress in the film. This birefringence
Koji Ando; Naoki Koshizuka; Takashi Okuda; Yuko Yokoyama
High-Frequency Permeability of Isotropic Co-Based Amorphous Films
The dependence of soft magnetic properties on the annealing conditions of Co-based amorphous films of different thicknesses was investigated in detail, in order to obtain films with a high isotropic initial permeability at high frequencies. It was found that the microscopic anisotropy of films annealed in a rotating field was increased isotropically by field-free annealing below the Curie temperature (Tc).
S. Muraoka; K. Takahashi; H. Sakakima
The Role of Residual Casting Solvent in Determining the Lithographic and Dissolution Behavior of Poly(methyl Methacrylate), a Positive Electron Beam Resist.
The effect of the pre-exposure bake and the choice of casting solvent on the sensitivity and contrast of PMMA has been documented to an extent not previously reported in the literature. PMMA films were spin cast onto clean silicon substrates from chlorobenzene and tri-chloroethylene solutions. The temperature of the pre-bake was varied over the range of 59^circ to 170^circC using a convection oven with pre-bake times ranging from 30 to 90 minutes. At the end of the designated bake time, the films were removed from the oven and allowed to cool in a temperature and humidity controlled environment. They were promptly exposed to a 15 KeV electron beam, then developed, with mild agitation, in a 1:1 mixture of MIBK and IPA at 22.5^ circC. Film thickness profiles were determined with an alpha-step profilometer. Films baked at temperatures below T_{rm glass} (the temperature which marks the onset of long-range, coordinated molecular motion), exhibited improved sensitivity and poorer contrast when compared to those baked above T_{rm glass }. Unique to this work is the finding that the lithographic performance depends on the choice of casting solvent, even at pre-bake temperatures significantly above T_{rm glass}. The relative concentrations of the casting solvents remaining in the baked films was determined from UV absorption spectra. The dissolution rates of exposed films were also measured and compared to the fragmented molecular weight model of development. Energy depositions were calculated from the empirical model of Everhart and Hoff. Cross-correlation of these results indicate that the pre-bake temperature more strongly correlates with the observed improvement in sensitivity than the presence of residual casting solvent. Residual casting solvent changes the density of the film, thus changing the energy deposition and dissolution behavior. Calculations based on the aforementioned models indicate that the observed lithographic and dissolution behavior can not be accounted for by this change in density. Arguments are presented to support the conclusion that the observed behavior is associated with film morphology. Comparison of results from films cast from TCE and chlorobenzene and baked above T_{rm glass} further support this conclusion.
Criss, Robert Randolph, Jr.
The taper of cast post preparation measured using innovative image processing technique
BACKGROUND: No documentation in the literature about taper of cast posts. This study was conducted to measure the degree of cast posts taper, and to evaluate its suitability based on the anatomy aspects of the common candidate teeth for post reconstruction. METHODS: Working casts for cast posts, prepared using Gates Glidden drills, were collected. Impressions of post spaces were made
Khaled Q Al Hamad; Faruq A Al-Omari; Ahmad S Al Hyiasat
A sensor of alcohol vapours based on thin polyaniline base film and quartz crystal microbalance.
Thin films of polyaniline base, emeraldine base (EB), coating on the quartz crystal microbalance (QCM) electrode were used as a sensitive layer for the detection of a number of primary aliphatic alcohols such as ethanol, methanol, 2-propanol and 1-propanol vapours. The frequency shifts (Deltaf) of the QCM were increased due to the vapour adsorption into the EB film. Deltaf were found to be linearly correlated with the concentrations of alcohols vapour in part per million (ppm). The sensitivity of the sensor was found to be governed by the chemical structure of the alcohol. The sensor shows a good reproducibility and reversibility. The diffusions of different alcohols vapour were studied and the diffusion coefficients (D) were calculated. It is concluded that the diffusion of the vapours into the EB film follows Fickian kinetics. PMID:19264405
Ayad, Mohamad M; El-Hefnawey, Gad; Torad, Nagy L
The general purpose of the first six months' work was to identify techniques which will produce sound castings in reusable chill molds - techniques which are compatible with an automated machine casting process. To do this, castings made in permanent chil...
Films Based on Biopolymer from Conventional and Non-Conventional Sources
Edible films are thin materials based on biopolymers. These films are also biodegradable and because of that, these materials\\u000a have attracted the attention of the food science academic community in the last decades. The main biopolymers used in the\\u000a edible films production are polysaccharides (Nisperos-Carriedo, 1994) and proteins (Gennadios et al., 1996).\\u000a \\u000a The polysaccharide most used in edible film technology
P. Sobral; J. D. Alvarado; N. E. Zaritzky; J. B. Laurindo; C. G¾mez-Guillķn; M. C. A±¾n; P. Montero; G. Denavi; S. Molina OrtĒz; A. Mauri; A. Pinotti; M. GarcĒa; M. N. Martino; R. Carvalho
The influence of high thermal gradient casting, hot isostatic pressing and alternate heat treatment on the structure and properties of a single crystal nickel base superalloy
A development program has been conducted to improve the cyclic properties of the PWA 1480 single-crystal superalloy by reducing or entirely eliminating casting porosity at fatigue-initiation sites, through the use of improved casting process parameters and HIPing; potential mechanical property improvements in a high-pressure hydrogen environment were also sought in alternatives to the standard coating and heat-treatment cycle. High thermal gradient casting was found to yield a reduction in overall casting porosity density and pore sizes. The most dramatic mechanical property improvement resulted from HIPing.
Fritzemeier, L. G.
Tribological behaviors of lanthanum-based phosphonate 3-aminopropyltriethoxysilane self-assembled films
Lanthanum-based thin films deposited on the phosphonate 3-aminopropyltriethoxysilane (APTES) self-assembled monolayer (SAM) were prepared on the hydroxylated glass substrate by a self-assembling process from specially formulated solution. Chemical compositions of the films and chemical state of the elements were detected by X-ray photoelectron spectrometry (XPS). The thickness of the films was determined with an ellipsometer, while the morphologies of the original and worn surfaces of the samples were analyzed by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. The tribological properties of the films sliding against GCr15 steel ball were evaluated on a UMT-2MT reciprocating friction and wear tester. As the results, the target film was obtained and reaction may have taken place between the film and the glass substrate. The tribological results show that lanthanum-based thin films are superior in reducing friction and resisting wear compared with APTES-SAM and phosphorylated APTES-SAM. SEM observation of the morphologies of worn surfaces indicates that the wear of APTES-SAM and the phosphorylated APTES-SAM is characteristic of brittle fracture and severe abrasion. Differently, slight abrasion and micro-crack dominate the wear of lanthanum-based thin films. The superior friction reduction and wear resistance of lanthanum-based thin films are attributed to the enhanced load-carrying capacity of the inorganic lanthanum particles in the lanthanum-based thin films as well as good adhesion of the films to the substrate.
Gu, Qinlin; Cheng, Xianhua
Paper-based transparent flexible thin film supercapacitors
Paper-based transparent flexible thin film supercapacitors were fabricated using CNF-[RGO]n hybrid paper as an electrode material and charge collector. Owing to the self-anti-stacking of distorted RGO nanosheets and internal electrolyte nanoscale-reservoirs, the device exhibited good electrochemical performance (about 1.73 mF cm-2), and a transmittance of about 56% (at 550 nm).Paper-based transparent flexible thin film supercapacitors were fabricated using CNF-[RGO]n hybrid paper as an electrode material and charge collector. Owing to the self-anti-stacking of distorted RGO nanosheets and internal electrolyte nanoscale-reservoirs, the device exhibited good electrochemical performance (about 1.73 mF cm-2), and a transmittance of about 56% (at 550 nm). Electronic supplementary information (ESI) available: Experimental, TEM image, IR spectra, and XRD spectra of cellulose nanofibers, TEM image, and XRD spectra of RGO, graphite, GO nanosheets, CNF paper, and CNF-[RGO]20 hybrid paper, high-resolution C1s spectra of GO, Raman spectra of GO nanosheets, cross-sectional FESEM image of CNF-[RGO]20 hybrid paper and stress-strain curve of T-SC-20. See DOI: 10.1039/c3nr00674c
Gao, Kezheng; Shao, Ziqiang; Wu, Xue; Wang, Xi; Zhang, Yunhua; Wang, Wenjun; Wang, Feijun
Casting Footprints for Eternity
Apollo 11 Astronaut Buzz Aldrin has his footprints casted during the dedication ceremony of the rocket fountain at Building 4200 at Marshall Space Flight Center. The casts of Aldrin's footprints will be placed in the newly constructed Von Braun courtyard representing the accomplishments of the Apollo 11 lunar landing.
Computer cast blast modelling
Cast blasting can be designed to utilize explosive energy effectively and economically for coal mining operations to remove overburden material. The more overburden removed by explosives, the less blasted material there is left to be transported with mechanical equipment, such as draglines and trucks. In order to optimize the percentage of rock that is cast, a higher powder factor than
S. Chung; M. McGill; D. S. Preece
Biodegradability and mechanical properties of starch films from Andean crops.
Different Andean crops were used to obtain starches not previously reported in literature as raw material for the production of biodegradable polymers. The twelve starches obtained were used to prepare biodegradable films by casting. Water and glycerol were used as plasticizers. The mechanical properties of the starch based films were assessed by means of tensile tests. Compost tests and FTIR tests were carried out to assess biodegradability of films. The results show that the mechanical properties (UTS, Young's modulus and elongation at break) of starch based films strongly depend on the starch source used for their production. We found that all the starch films prepared biodegrade following a three stage process and that the weight loss rate of all the starch based films tested was higher than the weight loss rate of the cellulose film used as control. PMID:21300087
Torres, F G; Troncoso, O P; Torres, C; DĒaz, D A; Amaya, E
PVDF-PZT nanocomposite film based self-charging power cell.
A novel PVDF-PZT nanocomposite film has been proposed and used as a piezoseparator in self-charging power cells (SCPCs). The structure, composed of poly(vinylidene fluoride) (PVDF) and lead zirconate titanate (PZT), provides a high piezoelectric output, because PZT in this nanocomposite film can improve the piezopotential compared to the pure PVDF film. The SCPC based on this nanocomposite film can be efficiently charged up by the mechanical deformation in the absence of an external power source. The charge capacity of the PVDF-PZT nanocomposite film based SCPC in 240 s is ?0.010 ?A h, higher than that of a pure PVDF film based SCPC (?0.004 ?A h). This is the first demonstration of using PVDF-PZT nanocomposite film as a piezoseparator for SCPC, and is an important step for the practical applications of SCPC for harvesting and storing mechanical energy. PMID:24531887
Zhang, Yan; Zhang, Yujing; Xue, Xinyu; Cui, Chunxiao; He, Bin; Nie, Yuxin; Deng, Ping; Lin Wang, Zhong
Near real-time estimation of tropospheric water vapour content from ground based GNSS data and its potential contribution to weather now-casting in Austria
The importance of high resolution meteorological analysis of the atmosphere increased over the past years. A detailed analysis of the humidity field is an important precondition for a better monitoring of local and regional extreme precipitation events and for forecasts with improved spatial resolution. For this reason, the Austrian Meteorological Agency (ZAMG) is operating the spatial and temporal high resolution INCA system (Integrated Now-casting through Comprehensive Analysis) since begin of 2005. Errors in this analysis occur mainly in the areas of rapidly changing and hard to predict weather conditions or rugged topography with extreme differences in height such as the alpine area of Austria. The aim of this work is to provide GNSS based measurements of the tropospheric water vapour content with a temporal resolution of 1 h and a temporal delay of less than 1 h to assimilate these estimates into the INCA system. Additional requirement is an accuracy of better than 1 mm of the precipitable water (PW) estimates.
Karabati?, Ana; Weber, Robert; Haiden, Thomas
Erosive Wear Behavior of Nickel-Based High Alloy White Cast Iron Under Mining Conditions Using Orthogonal Array
Nihard Grade-4, a nickel-bearing cast iron widely used in slurry pumps and hydrodynamic components, is evaluated for its erosive wear response under mining conditions using a statistical approach. Experiments were conducted by varying the factors namely velocity, slurry concentration, angle of impingement, and pH in three levels, using L9 orthogonal array. Analysis of variance was used to rank the factors influencing erosive wear. The results indicate that velocity is the most influencing factor followed by the angle of impingement, slurry concentration, and pH. Interaction effects of velocity, slurry concentration, angle of impingement, and pH on erosion rate have been discussed. Wear morphology was also studied using SEM characterization technique. At lower angle (30░) of impingement, the erosion of material is by micro fracture and shallow ploughing with the plastic deformation of the ductile austenitic matrix. At the normal angle (90░) of impingement, the material loss from the surface is found because of deep indentation, forming protruded lips which are removed by means of repeated impact of the erodent.
Yoganandh, J.; Natarajan, S.; Babu, S. P. Kumaresh
Polyhydroxyalkanoate-based natural synthetic hybrid copolymer films: A small-angle neutron scattering study
Polyhydroxyalkanoates have attracted attention as biodegradable alternatives to conventional thermoplastics and as biomaterials. Through modification of their biosynthesis using Pseudomonas oleovorans, we have manipulated the material properties of these biopolyesters and produced a natural-synthetic hybrid copolymer of polyhydroxyoctanoate- block-diethylene glycol (PHO- b-DEG). A mixture of PHO and PHO-DEG were solvent cast from analytical grade chloroform and analysed using small-angle neutron scattering. A scattering pattern, easily distinguished above the background, was displayed by the films with a diffraction ring at q?0.12 ┼ -1. This narrow ring of intensity is suggestive of a highly ordered system. Analysis of the diffraction pattern supported this concept and showed a d-spacing of approximately 50 ┼. In addition, conformation of the hybrid polymer chains can be manipulated to support their self-assembly into ordered microporous films.
Foster, L. John R.; Knott, Robert; Sanguanchaipaiwong, Vorapat; Holden, Peter J.
Effect of Gamma Radiation on the Physico- and ThermoMechanical Properties of Gelatin-Based Films Using 2-Hydroxyethyl Methacrylate (HEMA)
Gelatin films were prepared from gelatin granules in aqueous medium by casting. Tensile strength, tensile modulus, elongation at break and the glass point of the gelatin films were found to be 27ĀMPa, 100ĀMPa, 4% and 51.7░C, respectively. After irradiated with gamma radiation tensile properties were increased due to denser network structure. Gelatin films were soaked in five different formulations containing
Sabrina Sultana; Ruhul A. Khan; Mubarak A. Khan; A. I. Mustafa; M. A. Gafur
Renewable liquid film-based electrochemical sensor for gaseous hydroperoxides.
Electrochemical sensors for hydroperoxides based on thin flowing films were investigated. The sensor is composed of two segments of Nafion tubing put on a silver wire. A small portion of the silver wire is exposed and is chloridized to function as the reference electrode. One Nafion segment has a Pt-wire coil wrapped on it to function as the counter electrode and the other has a similar Pt-Rh wire coil that functions as the working electrode. A collection solution flows as a thin film on the sensor surface and also functions as the collection medium. Hydrogen peroxide and cumene hydroperoxide were examined as test compounds. The former can be oxidatively determined with a Pt-Rh electrode over a large range (ppb-ppm) without any significant influence of relative humidity. By using a technique to stop the liquid flow, the sensitivity can be further improved. Cumene hydroperoxide, an industrially important hydroperoxide, can be determined easily with a relative precision of better than 5% in the vapor phase over simulated process reaction mixtures containing percentage levels of the analyte by reduction on a Pd electrode. The sensor is simple and inexpensive to fabricate and requires only a suitably equipped personal computer for operation. PMID:18966780
Huang, H; Dasgupta, P K
Crack width monitoring of concrete structures based on smart film
Due to its direct link to structural security, crack width is thought to be one of the most important parameters reflecting damage conditions of concrete structures. However, the width problem is difficult to solve with the existing structural health monitoring methods. In this paper, crack width monitoring by means of adhering enameled copper wires with different ultimate strains on the surface of structures is proposed, based on smart film crack monitoring put forward by the present authors. The basic idea of the proposed method is related to a proportional relationship between the crack width and ultimate strain of the broken wire. Namely, when a certain width of crack passes through the wire, some low ultimate strain wires will be broken and higher ultimate strain wires may stay non-broken until the crack extends to a larger scale. Detection of the copper wire condition as broken or non-broken may indicate the width of the structural crack. Thereafter, a multi-layered stress transfer model and specimen experiment are performed to quantify the relationship. A practical smart film is then redesigned with this idea and applied to Chongqing Jiangjin Yangtze River Bridge.
Zhang, Benniu; Wang, Shuliang; Li, Xingxing; Zhang, Xu; Yang, Guang; Qiu, Minfeng
Room temperature operating ammonia sensor based on tellurium thin films
Tellurium thin films were studied for its use as ammonia gas sensors operable at room temperature. The films showed a reversible increase in resistance when exposed to ammonia and the response was found to be linear in the range of 0¢100ppm. The interaction of ammonia with tellurium film was investigated using Raman, XPS and impedance spectroscopy techniques. The results showed
Shashwati Sen; K. P. Muthe; Niraj Joshi; S. C. Gadkari; S. K. Gupta; Jagannath; M. Roy; S. K. Deshpande; J. V. Yakhmi
Template based nanofabrication: mechanical characterization of film-substrate interface
This paper presents the results of investigations of thin film alumina templates fabricated on silicon and other substrates. Such templates are of significant interest for the low-cost implementation of semiconductor and metal nanostructure arrays. In addition, thin film alumina templates on silicon have the potential for nanostructure integration with silicon electronics. Formation of thin film alumina templates on silicon substrates
Biswajit Das; Pavan Singaraju
Casting Alloys: Side-Effects
Side-effects from dental materials are a minor problem, but should be recognized. In recent questionnaire surveys about side-effects, the incidence was estimated to be 1:300 in periodontics and 1:2600 in pedodontics. None of these reactions was related to dental casting alloys. In prosthodontics, the incidence was calculated to be about 1:400, and about 27% were related to base-metal alloys forremovable
Arne Hensten-Pettersen
Methods for processing quality cellulose nanocrystal (CNC) suspensions using sulfuric acid hydrolysis of microcrystalline cellulose were developed and optimized. The resulting suspensions were used to develop shear-based methods for casting neat CNC films. These methods were used to produce oriented CNC films from the Purdue-made (long crystals, CNC-L) and FPL-made (short crystals, CNC-S) CNC suspensions. Increased casting shear rate increased the degree of CNC orientation as quantified by Hermans order parameter, S. The highest shear rate (100Ęs-1) produced maximum orientation, with resulting Hermans order parameter of S = 0.36 in the CNC-S film. Elastic modulus, ultimate tensile strength, and elongation at failure were measured with respect to film casting direction and CNC orientation. Elastic modulus in CNC films scaled directly with orientation and reached a maximum average of 23 GPa. Tensile strength did not scale with orientation, but was strongly linked to CNC length, where a maximum strength of 196 MPa was measured. In addition to CNC length and shear rate, suspension pH and heat treatment also affected film properties. As the pH of casting suspensions was increased from ś3 to ś7, orientation retention in films was increased, and a new maximum modulus of 30 GPa was observed at S = 0.53 for the CNC-S film. The mechanical properties of all neutral pH films were further enhanced through heat treatment, in which a 1-4 GPa increase in elastic modulus was observed, as well as a 40-80 MPa increase in tensile strength for all axially oriented films.
Reising, Alexander B.
Microstructure and Stress-Rupture Life of Polycrystal, Directionally Solidified, and Single Crystal Castings of Nickel-Based IN 939 Superalloy
A comparative investigation of microstructural and mechanical properties (stress-rupture life) in conventionally cast, directionally solidified, and single crystal IN 939 superalloy has been undertaken. Directional castings possess only a few columnar grains, all oriented in the crystallographic direction, whereas only one grain is present in a single crystal. Single crystals are characterized by the highest values of stress-rupture life, much
M. T. Jovanovi?; Z. MiÜkovi?; B. Luki?
Fatigue of Iron Base Alloys HY-80 Steel Cast Tees Butt Welded to Rolled Section Single and Double Weld Joint Design.
The average fatigue life of 1 5/8 in. thick cast tee butt welded to rolled plate is approximately the same as that of cast plate butt welded to rolled plate and rolled plate butt welded to rolled plate. At 80,000 psi nominal stress range the fatigue life ...
Graphene-based electrodes for enhanced organic thin film transistors based on pentacene.
This paper presents 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) and pentacene-based organic thin film transistors (OTFTs) with monolayer graphene source-drain (S-D) electrodes. The electrodes are patterned using conventional photolithographic techniques combined with reactive ion etching. The monolayer graphene film grown by chemical vapor deposition on Cu foil was transferred on a Si dioxide surface using a polymer-supported transfer method to fabricate bottom-gate, bottom-contact OTFTs. The pentacene OTFTs with graphene S-D contacts exhibited superior performance with a mobility of 0.1 cm(2) V(-1) s(-1) and an on-off ratio of 10(5) compared with OTFTs with Au-based S-D contacts, which had a mobility of 0.01 cm(2) V(-1) s(-1) and an on-off ratio of 10(3). The crystallinity, grain size, and microscopic defects (or the number of layers of graphene films) of the TIPS-pentacene/pentacene films were analyzed by X-ray diffraction spectroscopy, atomic force microscopy, and Raman spectroscopy, respectively. The feasibility of using graphene as an S-D electrode in OTFTs provides an alternative material with high carrier injection efficiency, chemical stability, and excellent interface properties with organic semiconductors, thus exhibiting improved device performance of C-based electronic OTFTs at a reduced cost. PMID:25000388
Basu, Sarbani; Lee, Mu Chen; Wang, Yeong-Her
Co-based nanogranular thin films on flexible substrate for gigahertz applications
The Co-based granular thin films were deposited on the flexible substrate (Kapton) by magnetron sputtering. The films comprise of Co nanocrystallites and small amount of amorphous (Al,O)-rich inter-granular phase and have the electric resistivities in the range 50-120 ?? cm, depending on the composition and thickness. The as-deposited films with thickness <80 nm have low coercivity (<20 Oe along hard direction), high permeability (up to 500) and resonance frequency up to 2.5 GHz. Compared to the rigid films, the flexible films have relatively higher coercivity and lower resonance frequency. A comparison between Co-based granular films and FeTaN continuous films has also been discussed.
Liu, Z. W.; Liu, Y.; Ma, Y. G.; Tan, C. Y.; Ong, C. K.
INTERIOR VIEW WITH LARGE PIPE CASTING MACHINE CASTING A 48' PIPE OPERATOR SPRAYING A POWDER TO HELP SOLIDIFY THE PIPE BEING CENTRIFUGALLY CAST. - United States Pipe & Foundry Company Plant, Pipe Casting & Testing Area, 2023 St. Louis Avenue at I-20/59, Bessemer, Jefferson County, AL
Optimum cast plan for steelmaking-continuous casting production scheduling
A planning method of cast for steelmaking continuous casting production scheduling in CIMS is studied. The cast plan model is established. An adaptive operator genetic algorithm is proposed to solve the optimum cast plan problem. The computation with practical data shows that the model and the solving method are very effective.
Yuncan Xue; Qiwen Yang; Huihe Shao
A Simple Model of the Mold Boundary Condition in Direct-Chill (DC) Casting of Aluminum Alloys
An accurate thermofluids model of aluminum direct-chill (DC) casting must solve the heat-transfer equations in the ingot with realistic external boundary conditions. These boundary conditions are typically separated into two zones: primary cooling, which occurs inside the water-cooled mold, and secondary cooling, where a film of water contacts the ingot surface directly. Here, a simple model for the primary cooling boundary condition of the steady-state DC casting process was developed. First, the water-cooled mold was modeled using a commercial computational fluid dynamics (CFD) package, and its effective heat-transfer coefficient was determined. To predict the air-gap formation between the ingot and mold and to predict its effect on the primary cooling, a simple density-based shrinkage model of the solidifying shell was developed and compared with a more complex three-dimensional (3-D) thermoelastic model. DC casting simulations using these two models were performed for AA3003 and AA4045 aluminum alloys at two different casting speeds. A series of experiments was also performed using a laboratory-scale rectangular DC caster to measure the thermal history and sump shape of the DC cast ingots. Comparisons between the simulations and experimental results suggested that both models provide good agreement for the liquid sump profiles and the temperature distributions within the ingot. The density-based shrinkage model, however, is significantly easier to implement in a CFD code and is more computationally efficient.
Baserinia, Amir R.; Ng, H.; Weckman, D. C.; Wells, M. A.; Barker, S.; Gallerneault, M.
Preparation and characterization of oxadiazole based electron transporting thin films
To study the effect of aggregation of the 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) molecule in solid state, thin films of PBD have been prepared by the thermal evaporation technique onto glass and quartz substrates under different experimental conditions. These films have been studied for their structural, optical and electrical properties. AFM investigations of the films revealed that the films were smooth, dense and crack free with RMS roughness of 11-14 nm. XRD measurements indicate that films deposited on quartz are more crystalline than films deposited on glass substrate. Both absorption and reflectance spectra over the wavelength range 200-800 nm have been recorded to find optical parameters, namely, absorption, extinction coefficient, refractive index and dielectric constants. The inter-band transition energies are found to lie within the range 3.45-3.49 eV. Optical studies of the films indicate that PBD molecules preferred J-aggregation. A prominent single emission peak in the range of 370-390 nm has been observed which confirms that the fluorescent property of this molecule is not quenched in the thin film state. The electrical conductivity results for the evaporated films exhibited semiconductor behaviour within the investigated field and temperature range. The nature of the substrate is found to be a useful tool to modify the film morphology and for enhancing the charge transport within the films.
Mahajan, Aman; Aulakh, Ramanpreet Kaur; Bedi, R. K.
Hydrazine-based deposition route for device-quality CIGS films
A simple solution-based approach for depositing CIGS (Cu¢In¢Ga¢Se\\/S) absorber layers is discussed, with an emphasis on film characterization, interfacial properties and integration into photovoltaic devices. The process involves incorporating all metal and chalcogenide components into a single hydrazine-based solution, spin coating a precursor film, and heat treating in an inert atmosphere, to form the desired CIGS film with up to
David B. Mitzi; Min Yuan; Wei Liu; Andrew J. Kellock; S. Jay Chey; Lynne Gignac; Alex G. Schrott
Mechanical, water vapor barrier and thermal properties of gelatin based edible films
Edible films are thin materials based on a biopolymer. The objectives of this work were to determine the water vapor permeability and the mechanical and thermal properties of edible films based on bovine hide and pigskin gelatins. These films were prepared with 1g of gelatin\\/100ml of water; 15¢65g sorbitol\\/100g gelatin; and at natural pH. The samples were conditioned at 58%
P. J. A. Sobral; F. C. Menegalli; M. D. Hubinger; M. A. Roques
A micromachined carbon nanotube film cantilever-based energy cell.
This paper reports a new type of energy cell based on micromachined carbon nanotube film (CNF)-lead zirconate titanate cantilevers that is fabricated on silicon substrates. Measurements found that this type of micro-energy cell generates both AC voltages due to the self-reciprocation of the microcantilevers and DC voltages due to the thermoelectric effect upon exposure to light and thermal radiation, resulting from the unique optical and thermal properties of the CNF. Typically the measured power density of the micro-energy cell can be from 4 to 300Ā?WĀcm(-2) when it is exposed to sunlight under different operational conditions. It is anticipated that hundreds of integrated micro-energy cells can generate power in the range of milliwatts, paving the way for the construction of self-powered micro-Āor nanosystems. PMID:22842491
Gong, Zhongcheng; He, Yuan; Tseng, Yi-Hsuan; O'Neal, Chad; Que, Long
Temperature effect on field emission properties and microstructures of polymer-based carbon films
We investigated the field emission properties and resistivity of polymer-based carbon films prepared from poly ethyl-co-phenyl carbyne polymer precursors after treatment at different temperatures. As the heat-treatment temperature increased from 40 to 1200 ░C, the emission threshold field decreased from 12.4 to 2.1 V/?m, the emission current density increased from 0.1 to 6.1 mA/cm2, and the film resistivity decreased from 108 to 102 ? cm. The structural changes of the polymer films during the heat-treatment process were analyzed by Raman spectroscopy and atomic force microscopy. Raman analysis of these polymer-based carbon films suggests that the hydrogen content decreased while the sp2 carbon phase increased as the heat-treatment temperature increased. The dependence of the field emission properties of the polymer-based carbon films on the film structures (such as sp3, sp2 phases), film surface morphology and film resistivity is discussed. The enhancement of field emission from polymer-based carbon films was related to the increase of sp2/sp3 ratio, film conductivity, and surface roughness with the heat-treatment temperature.
Guo, P. S.; Sun, Z.; Huang, S. M.; Sun, Y.
Effects of Li2O and Na2O on the Crystallization Behavior of Lime-Alumina-Based Mold Flux for Casting High-Al Steels
With the development of advanced high strength steel (AHSS), a large amount of aluminum was added into steels. The reaction between aluminum in the molten steel and silica based mold flux in the continuous-casting process would tend to cause a series of problems and influence the quality of slabs. To solve the above problems caused by the slag-steel reaction, nonreactive lime-alumina-based mold flux system has been proposed. In this article, the effect of Li2O and Na2O on the crystallization behavior of the lime-alumina-silica-based mold flux has been studied by using the single hot thermocouple technology (SHTT) and double hot thermocouple technology (DHTT). The results indicated that Li2O and Na2O in the above mold flux system play different roles as they behaved in traditional lime-silica based mold flux, which would tend to inhibit general mold flux crystallization by lowering the initial crystallization temperature and increasing incubation time, especially in the high-temperature region. However, when their content exceeds a critical value, the crystallization process of mold fluxes in low temperature zone would be greatly accelerated by the new phase formation of LiAlO2 and Na x Al y Si z O4 crystals, respectively. The crystalline phases precipitated in all samples during the experiments are discussed in the article.
Lu, Boxun; Chen, Kun; Wang, Wanlin; Jiang, Binbin
Research on the measurement of thin film thickness based on phaseshift interferometry
Only by solving the problem of accurate measurement of thin film thickness, will it be possible to solve the problem of thin film preparation. A novel measurement method of thin film thickness based on phase-shift interferometry is presented in the paper. Taking advantage of Twyman-Green interferometer, the multi-frame interferogram measured the thin film can be obtained by receiving the interference fringes of thin film by means of CCD and using digital acquisition card to collect interferogram and with the help of computer control PZT driver and modulation piezoelectric regulator to promote reference mirror uniformly-spaced movement. After the gained interferogram were disposed of phase unwrapped, 3D wavefront containing the information of thin film thickness can be obtained. According to the characteristics between the thin film thickness and the unwrapping phase, taking advantage of the overlapping 4-frame average algorithm, corresponding relationships between the quantification phase information and thin film thickness of each point has been established to realize the thin film thickness accurate measurement. The results show that this method has the advantage of non-contact, the high accuracy, not only has testified the feasibility of film thickness measurement with phase-shift interferometry, but also has further ensured research and optimization of the thin film preparation technics. The PV and RMS value of the measured thin film thickness are 0.162?m and 0.043?m respectively.
Shi, Yi-Lei; Su, Jun-Hong; Yang, Li-Hong; Xu, Jun-Qi
Laminating Polyimide Films
Thermoplastic polyimide adhesive is used to bond polyimide sheets into flexible laminates. Films are first primed with polyimide adhesive, then bonded together under heat and pressure. Adhesive is cast on separate surface, then sandwiched between polyimide and/or metal films for final assembly. Objectives of process are to improve bonding of high-temperature polyimide film, prepare flexible, large-area, void-free laminates from polyimide film, and laminate polyimide film not only to itself but to metal surfaces.
St. Clair, A. K.; St. Clair, T. L.; Robinson, P. D.
Air-Flow Navigated Crystal Growth for TIPS Pentacene-Based Organic Thin-Film Transistors
6,13-bis(triisopropylsilylethynyl)pentacene (TIPS pentacene) is a promising active channel material of organic thin-film transistors (OTFTs) due to its solubility, stability, and high mobility. However, the growth of TIPS pentacene crystals is intrinsically anisotropic and thus leads to significant variation in the performance of OTFTs. In this paper, air flow is utilized to effectively reduce the TIPS pentacene crystal anisotropy and enhance performance consistency in OTFTs, and the resulted films are examined with optical microscopy, grazing-incidence X-ray diffraction, and thin-film transistor measurements. Under air-flow navigation (AFN), TIPS pentacene drop-cast from toluene solution has been observed to form thin films with improved crystal orientation and increased areal coverage on substrates, which subsequently lead to a four-fold increase of average hole mobility and one order of magnitude enhancement in performance consistency defined by the ratio of average mobility to the standard deviation of the field-effect mobilities.
He, Zhengran [ORNL] [ORNL; Chen, Jihua [ORNL] [ORNL; Sun, Zhenzhong [ORNL] [ORNL; Szulczewski, Greg [University of Alabama, Tuscaloosa] [University of Alabama, Tuscaloosa; Li, Dawen [ORNL] [ORNL
Concrete Casting Machine.
The machine is for casting, on a production line basis, articulated concrete revetment mats employed to protect riverbanks and flood control levees from hydraulic erosion. The apparatus includes a moving conveyor system which carries flat pallets to a cas...
J. I. Boswell T. Burks G. F. Dixon G. S. Lee
Baked starch\\/pulp foams were prepared from formulations containing zero to 25 weight percent of processed Alaskan fish by-products that consisted mostly of salmon heads, pollock heads, and pollock frames (bones and associated remains produced in the filleting operation). Fish by-products thermoformed well along with starch and pulp fiber, and the foam product (panels) exhibited useful mechanical properties. Foams with all
Syed H. Imam; Bor-Sen Chiou; Delilah Woods; Justin Shey; Gregory M. Glenn; William J. Orts; Robert J. Avena-Bustillos; Tara H. McHugh; Alberto Pantoja; Peter J. Bechtel
Cast changes: synthetic versus plaster.
A review of the changes in casting since the introduction of improved synthetic casting materials in the 1970s is presented. There is very little in the literature on nursing implications regarding the newer casting materials. Improvements in synthetic materials used in the casting of children include a fiberglass-free, latex-free casting polymer, with child-friendly prints now available. Though the use of synthetic casting predominates the market, plaster of Paris is still the mainstay for serial casting and casting requiring superior moldability and conformability. The advantages and disadvantages of synthetic and plaster of Paris casting, as well as nursing care of the child in each type of cast are summarized. PMID:9282058
Adkins, L M
Amorphous Silicon(aSi:H) Thin Film Based Omnidirectional Control Solar Powered Vehicle
Through the paper, our goal is to drive a car with the help of thin film based solar cell. Mechanical and Electrical parts are assembled thereby. The main objective of this project is to collect maximum solar energy from the solar spectrum and use that solar energy to drive the car. Amorphous silicon based thin film solar panel has been
Abdullah Moinuddin; Jony C. Sarker; Akhter Zia
Casting Characteristics of Aluminum Die Casting Alloys
The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.
Method of casting aerogels
The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm[sup 3] to 0.6 g/cm[sup 3]. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of aerogel which occurs during the drying step of supercritical extraction of solvent. 2 figures.
Poco, J.F.
The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm.sup.3 to 0.6 g/cm.sup.3. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of alcogel which occurs during the drying step of supercritical extraction of solvent.
Poco, John F. (Livermore, CA)
Bence Jones Cast Nephropathy
Patients with Bence Jones cast nephropathy usually present with acute renal failure (less commonly with chronic renal failure)\\u000a and Bence Jones proteinuria. It has been known for many years that intravenous radiocontrast media, dehydration, infections,\\u000a and the use of nonsteroidal antiin- fl ammatory drugs may induce the precipitation of renal tubular light chain casts and\\u000a result in acute renal failure,
Arthur H. Cohen
Elevated temperature mechanical properties and residual tensile properties of two cast superalloys and several nickel-base oxide dispersion strengthened alloys
The elevated temperature tensile, stress-rupture and creep properties and residual tensile properties after creep straining have been determined for two cast superalloys and several wrought Ni-16Cr-4Al-yttria oxide dispersion strengthened (ODS) alloys. The creep behavior of the ODS alloys is similar to that of previously studied ODS nickel alloys. In general, the longitudinal direction is stronger than the long transverse direction, and creep is at least partially due to a diffusional creep mechanism as dispersoid-free zones were observed after creep-rupture testing. The tensile properties of the nickel-base superalloy B-1900 and cobalt-base superalloy MAR-M509 are not degraded by prior elevated temperature creep straining (at least up to 1 pct) between 1144 and 1366 K. On the other hand, the room temperature tensile properties of ODS nickel-base alloys can be reduced by prior creep strains of 0.5 pct or less between 1144 and 1477 K, with the long transverse direction being more susceptible to degradation than the longitudinal direction.
Whittenberger, J. D.
Optical Sensors Based on Single Arm Thin Film Waveguide Interferometer
Single-arm double-mode double-order optical waveguide interferometer utilizes interference between two propagating modes of different orders. Sensing effect results from the change in propagation conditions of the modes caused by the environment. The waveguide is made as an open asymmetric slab structure containing a dye-doped polymer film onto a fused quartz substrate. It is more sensitive to the change of environment than its conventional polarimetric analog using orthogonal modes (TE and TM) of the same order. The sensor still preserves the option of operating in polarimetric regime using a variety of mode combinations such as TE(sub 0)/TM(sub 0) (conventional), TE(sub 0)/TM(sub 1), TE(sub 1)/TM(sub 0), or TE(sub 1)/TM(sub 1) but can also work in nonpolarimetric regime using combinations TE(sub 0)/TM(sub 1) or TE(sub 0)/TM(sub 1). Utilization of different mode combinations simultaneously makes the device more versatile. Application of the sensor to gas sensing is based on doping polymer film with an organic indicator dye sensitive to a particular gas. Change of optical absorption spectrum of the dye caused by the gaseous pollutant results change of the reactive index of the dye-doped polymer film that can be detected by the sensor. As an indicator dyes, we utilize Bromocresol Purple doped into polymer poly(methyl) methacrylate, which shows a reversible growth of the absorption peak neat 600 nm after exposure to wet ammonia. We have built a breadboard prototype of the sensor with He-Ne laser as a light source and with a single mode fiber input and a multimode fiber output. The prototype showed sensitivity to temperature change of the order of 2 C per one full oscillation of the signal. The sensitivity of the sensor to the presence of wet ammonia is 200 ppm per one full oscillation of the signal. The further improvements include switching to a longer wavelength laser source (750-nm semiconductor laser), substitution of poly(methyl) methacrylate with hydrophilic high-temperature polyimide, and increase the doping rate of indicator dye. All these improvements are expected to bring sensitivity to 10 ppm of ammonia per one full oscillation of signal independent on the humidity of ambient air. The proposed sensor can be used as a robust and inexpensive stand-alone instrument for continuous environment pollution monitoring.
Sarkisov, S. S.; Diggs, D.; Curley, M.; Adamovsky, Grigory (Technical Monitor)
Predicting Pattern Tooling and Casting Dimensions for Investment Casting - Phase II
The investment casting process allows the production of complex-shape parts and close dimensional tolerances. One of the most important phases in the investment casting process is the design of the pattern die. Pattern dies are used to create wax patterns by injecting wax into dies. The wax patterns are used to create a ceramic shell by the application of a series of ceramic coatings, and the alloy is cast into the dewaxed shell mold (Fig. 1.1). However, the complexity of shape and the close dimensional tolerances required in the final casting make it difficult to determine tooling dimensions. The final linear dimension of the casting depends on the cumulative effects of the linear expansions or contractions in each step of the investment casting process (Fig. 1.2). In most cases, the mold geometry or cores restrict the shrinkage of the pattern or the cast part, and the final casting dimensions may be affected by time-dependent processes such as viscoelastic deformation of the wax, and viscoplastic creep and plastic deformations of the shell and alloy. The pattern die is often reworked several times to produce castings whose dimensions are within acceptable tolerances. To date, investment casting technology has been based on hands-on training and experience. Technical literature is limited to experimental, phenomenological studies aimed at obtaining empirical correlations for quick and easy application in industry. The goal of this project was to predict casting dimensions for investment castings in order to meet blueprint nominal during the first casting run. Several interactions have to be considered in a coupled manner to determine the shrinkage factors: these are the die-wax, wax-shell, and shell-alloy interactions (as illustrated in Fig. 1.3). In this work, the deformations of the die-wax and shell-alloy systems were considered in a coupled manner, while the coupled deformation of the wax-shell system was not considered. Future work is needed in order to deliver to industry a computer program in which all three systems are coupled for determining the dimensions of the wax pattern, the shell mold, and casting in a sequential but coupled manner.
Sabau, Adrian S [ORNL
Hg-based superconducting films prepared by spray pyrolysis technique
Hg-Ba-Ca-Cu-O films have been prepared on silver substrates using a spray pyrolysis technique, following a two step procedure; first Ba-Ca-Cu-O films were prepared at a 350 C substrate temperature and annealed at 780 C for 6 hours to obtain a Ba-Ca-Cu-O precursor. Secondly, Hg-Ba-Ca-O films were prepared by spraying HgC{ell}{sub 2} on a Ba-Ca-Cu-O precursor at a 250 C substrate temperature. These films were then oxidized at 250 C for 10 hours in an oxygen atmosphere. Films thus obtained were characterized by studying their microphotography, X-ray diffraction pattern and electrical properties. These films show super conductivity below 87 K.
Pawar, S.H.; Pawaskar, P.N. [Shivaji Univ., Kolhapur (India). Energy Studies Lab.] [Shivaji Univ., Kolhapur (India). Energy Studies Lab.
Microstructure and stress-rupture life of polycrystal, directionally solidified, and single crystal castings of nickel-based IN 939 superalloy
A comparative investigation of microstructural and mechanical properties (stress-rupture life) in conventionally cast, directionally solidified, and single crystal IN 939 superalloy has been undertaken. Directional castings possess only a few columnar grains, all oriented in the <100> crystallographic direction, whereas only one grain is present in a single crystal. Single crystals are characterized by the highest values of stress-rupture life, much higher than those of directionally solidified and, especially, polycrystal castings, which is accounted for by the absence of grain boundaries.
Jovanovic, M.T.; Miskovic, Z.; Lukic, B. [Inst. of Nuclear Sciences Vinca, Belgrade (Yugoslavia). Dept. of Materials Science] [Inst. of Nuclear Sciences Vinca, Belgrade (Yugoslavia). Dept. of Materials Science
Effects of high-pressure homogenization on the properties of starch-plasticizer dispersions and their films
The properties of starch-plasticizer (glycerol:xylitol=1:1) dispersions obtained with and without high-pressure homogenization and their corresponding films were investigated. The fully gelatinized dispersions with or without homogenization were subsequently converted into films using solution casting. The apparent viscosity of the dispersions with or without homogenization was determined. The water vapor permeability, opacity, crystalline\\/amorphous nature, and mechanical properties of these starch-based films
Zong-qiang Fu; Li-jun Wang; Dong Li; Qing Wei; Benu Adhikari
A hydrogen sensor based on Mg Pd alloy thin film
We report on the hydrogen sensing property of Pd-capped Mg-Pd alloy thin films which were prepared by dc magnetron sputtering. Pd-capped Mg0.9Pd0.1 films of thicknesses 10 nm Pd and 40 nm Mg-Pd show a good hydrogen sensing property for hydrogen-containing atmosphere at room temperature. Their sensing range is from 40 ppm to 4% hydrogen in Ar. These films are supposed
K. Yoshimura; S. Nakano; S. Uchinashi; S. Yamaura; H. Kimura; A. Inoue
A microwave phase shifter based on a planar ferrite-ferroelectric thin-film structure
Microwave phase shifters employing slot transmission lines based on thin ferroelectric films of barium strontium titanate and thin single-crystalline films of yttrium iron garnet ferrite have been experimentally studied for the first time. The phase shifters admit double electronic control based upon the phenomenon of hybridization of the electromagnetic wave propagating in a slot delay line on the ferroelectric film and the spin wave propagating in the ferrite film. At a bias voltage of 150 V applied to electrodes of the slot lines with 50- and 150-?m-wide slots, the phase shift amounted to 53░ and 26░, respectively.
Nikitin, A. A.; Ustinov, A. B.; Semenov, A. A.; Kalinikos, B. A.
Facile one-pot synthesis of a polyvinylpyrrolidone-based self-crosslinked fluorescent film.
A polyvinylpyrrolidone (PVP)-based fluorescent film with stable optical properties is successfully prepared in one pot without any additive. The reaction mechanism of ring-opening and self-crosslinking of linear PVP is proposed and demonstrated. The morphologies and the nanostructures of the fluorescent film as well as the unmodified film are investigated. The dye is incorporated into the film networks via covalent linkages, thus leading to the highly stable optical properties. The facile and effective synthesis approach opens a new way for the design of other multi-functional composite materials based on linear PVP. PMID:23401022
Yin, Meizhen; Ye, Yong; Sun, Mengmeng; Kang, Naiwen; Yang, Wantai
Microwave permeability of laminates with thin Fe-based films
The permeability of layered composites (laminates) is measured at frequencies 0.1-10 GHz. The laminates consist of alternating iron and Mylar films. The continuous or patterned iron films 0.1-1 ?m thick are produced by magnetron sputtering. The intrinsic permeability spectra of metal inclusion are parametrically reconstructed. The obtained parameters of magnetic resonance are compared to the theoretical constrains derived for a perfect infinite film. The effect of film thickness upon the permeability of the laminate is discussed. The microwave permeability of the laminates under study is comparable with that of composites filled with carbonyl iron.
Iakubov, I. T.; Lagarkov, A. N.; Maklakov, S. A.; Osipov, A. V.; Rozanov, K. N.; Ryzhikov, I. A.; Starostenko, S. N.
Cellulose triacetate, thin film dielectric capacitor
Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 microns in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.
Yen, Shiao-Ping S. (inventor); Jow, T. Richard (inventor)
Reduced graphene oxide based silver sulfide hybrid films formed at a liquid/liquid interface
Free-standing, ultra-thin films of silver sulfide and reduced graphene oxide (RGO) based silver sulfide hybrids are prepared at a liquid/liquid interface employing in situ chemical reaction strategy. Ag2S and RGO-Ag2S hybrid films are characterized by various techniques such as UV-visible and photo luminescence spectroscopy, X-ray diffraction and scanning electron microscopy. The morphology of hybrid films consists of Ag2S nanocrystals on RGO surface while Ag2S films contains branched network of dendritic structures. RGO-Ag2S exhibit interesting optical and electrical properties. The hybrid films absorb in the region 500-650 nm and show emission in the red region. A higher conductance is observed for the hybrid films arising from the RGO component. This simple low cost method can be extended to prepare other RGO based metal sulfides.
Bramhaiah, K.; John, Neena S.
Tape casting of lanthanum chromite
Solid oxide fuel cells (SOFCs) are currently being developed for a variety of applications such as stationary on-site power plants and cogeneration. The effects of process additives, ball milling, and solids loading were evaluated for tape casting suspensions of glycine-nitrate-synthesized La{sub 0.7}Ca{sub 0.31}CrO{sub 3} powder. An optimized formulation was obtained based on rheological characterization, electrokinetic sonic amplitude measurements, qualitative examination of green tapes, and the sintered microstructure. The tape casting formulation incorporated 66:34 methyl ethyl ketone/ethyl alcohol solvent, an aliphatic phosphate ester dispersant, and 80 wt% (35 vol%) solids. The best binder/plasticizer system was 12 wt% (15 vol%) poly(isobutyl methacrylate) and 5 wt% (6.3 vol%) benzyl butyl phthalate plasticizer (binder:plasticizer = 2.3). Cast tapes were sintered at 1300 C for 2 h, producing a bulk density of 96.2% theoretical, with linear shrinkage of 22% and an approximate grain size of 1.3 {micro}m.
Murphy, M.W.; Armstrong, T.R.; Smith, P.A. [Pacific Northwest National Lab., Richland, WA (United States)
Evaluation and improvement in the accuracy of a charge-coupled-device-based pyrometer for temperature field measurements of continuous casting billets
This paper presents a radiometric high-temperature field measurement model based on a charge-coupled-device (CCD). According to the model, an intelligent CCD pyrometer with a digital signal processor as the core is developed and its non-uniformity correction algorithm for reducing the differences in accuracy between individual pixel sensors is established. By means of self-adaptive adjustment for the light-integration time, the dynamic range of the CCD is extended and its accuracy in low-temperature range is improved. The non-uniformity correction algorithm effectively reduces the accuracy differences between different pixel sensors. The performance of the system is evaluated through a blackbody furnace and an integrating sphere, the results of which show that the dynamic range of 400 K is obtained and the accuracy in low temperature range is increased by 7 times compared with the traditional method based on the fixed light-integration time. In addition, the differences of accuracy between the on-axis pixel and the most peripheral pixels are decreased from 19.1 K to 2.8 K. Therefore, this CCD pyrometer ensures that the measuring results of all pixels tend to be equal-accuracy distribution across the entire measuring ranges. This pyrometric system has been successfully applied to the temperature field measurements in continuous casting billets.
Bai, Haicheng; Xie, Zhi; Zhang, Yuzhong; Hu, Zhenwei
Evaluation and improvement in the accuracy of a charge-coupled-device-based pyrometer for temperature field measurements of continuous casting billets.
This paper presents a radiometric high-temperature field measurement model based on a charge-coupled-device (CCD). According to the model, an intelligent CCD pyrometer with a digital signal processor as the core is developed and its non-uniformity correction algorithm for reducing the differences in accuracy between individual pixel sensors is established. By means of self-adaptive adjustment for the light-integration time, the dynamic range of the CCD is extended and its accuracy in low-temperature range is improved. The non-uniformity correction algorithm effectively reduces the accuracy differences between different pixel sensors. The performance of the system is evaluated through a blackbody furnace and an integrating sphere, the results of which show that the dynamic range of 400 K is obtained and the accuracy in low temperature range is increased by 7 times compared with the traditional method based on the fixed light-integration time. In addition, the differences of accuracy between the on-axis pixel and the most peripheral pixels are decreased from 19.1 K to 2.8 K. Therefore, this CCD pyrometer ensures that the measuring results of all pixels tend to be equal-accuracy distribution across the entire measuring ranges. This pyrometric system has been successfully applied to the temperature field measurements in continuous casting billets. PMID:23822369
Effects of copper-based dental casting alloys on two lymphocyte cell lines and the secretion of interleukin 2 and IgG.
In the oral environment, gingival lymphocytes are involved in maintaining the local immune defense of periodontal tissues. The corrosion rates of copper-based dental casting alloys and the accumulation of corrosion products in host gingiva raise concerns about the effects of these corrosion products on immune responses in the oral cavity. The aim of this study ws to investigate the hypothesis that immune function may be altered by copper dental alloy corrosion products. In vitro cell culture studies were used to analyze the effects of three copper-based dental alloys on a T-cell and B-cell line and their secretion of soluble immune mediators (IL-2) and effectors (IgG), respectively. Results of this study revealed that corrosion products released from copper alloys in 24 h have the ability to reduce cellular viability, alter proliferation, and modulate the production of soluble immune mediators. These results support the hypothesis that copper dental ally corrosion products may alter immune responses and thereby contribute to a variety of dental pathological conditions. PMID:8595847
Bumgardner, J D; Lucas, L C; Alverson, M W; Tilden, A B
Preparation of nanocrystalline titania films with different porosity by water-based chemical solution deposition
This study describes the synthesis of nanocrystalline titania layers on silicon and glass substrates by chemical solution\\u000a deposition, using a water-based citratoperoxo-Ti(IV) precursor solution. The same aqueous solution¢gel precursor is used for\\u000a deposition of, both, thin dense layers by spin-coating and thicker porous layers by tape-casting. In the latter, the precursor\\u000a solution is modified by the addition of polyvinyl alcohol
Ine Truijen; Marlies K. Van Bael; Heidi Van den Rul; Jan DÆHaen; Jules Mullens
Dielectric structure pyrotechnic initiator realized by integrating Ti\\/CuO-based reactive multilayer films
A dielectric structure pyrotechnic initiator was proposed and the initiator samples were designed and realized by integrating Ti\\/CuO-based reactive multilayer films on ceramic substrate. The dielectric structure consists of essentially two titanium films separated by a copper oxide (CuO) film, which is just like as a capacitor guaranteeing the initiator will not be discharged until the external voltage has exceeded
Peng Zhu; Ruiqi Shen; N. N. Fiadosenka; Yinghua Ye; Yan Hu
The Co-based granular thin films were deposited on the flexible substrate (Kapton) by magnetron sputtering. The films comprise of Co nanocrystallites and small amount of amorphous (Al,O)-rich inter-granular phase and have the electric resistivities in the range 50 120 muOmega cm, depending on the composition and thickness. The as-deposited films with thickness <80 nm have low coercivity (<20 Oe along
Z. W. Liu; Y. Liu; Y. G. Ma; C. Y. Tan; C. K. Ong
The Co-based granular thin films were deposited on the flexible substrate (Kapton) by magnetron sputtering. The films comprise of Co nanocrystallites and small amount of amorphous (Al,O)-rich inter-granular phase and have the electric resistivities in the range 50¢120??cm, depending on the composition and thickness. The as-deposited films with thickness <80nm have low coercivity (<20Oe along hard direction), high permeability (up
Electronic and structural properties of graphene-based transparent and conductive thin film electrodes
We demonstrate that graphene-based transparent and conductive thin films (GTCFs), fabricated by thermal reduction of graphite\\u000a oxide, have very similar electronic and structural properties as highly oriented pyrolytic graphite (HOPG). Electron spectroscopy\\u000a results suggest that the GTCFs are also semi-metallic and that the individual graphene sheets of the film are predominantly\\u000a oriented parallel to the substrate plane. These films may
A. Vollmer; X. L. Feng; X. Wang; L. J. Zhi; K. M³llen; N. Koch; J. P. Rabe
Junctionless Flexible Oxide-Based Thin-Film Transistors on Paper Substrates
Junctionless flexible oxide-based electric-double-layer thin-film transistors (TFTs) are fabricated on paper substrates at room temperature. Channel and source\\/drain electrodes are realized by an indium¢tin¢oxide (ITO) film without any source\\/drain junction. Effective field-effect modulation of drain current can be obtained when the thickness of the top ITO film is decreased to 20 nm. These junctionless paper TFTs show a good device
Jie Jiang; Jia Sun; Wei Dou; Qing Wan
Development of FeCo-based thin films for gigahertz applications
For improving high-frequency characteristics and soft magnetic properties of (Fe7Co3)B-based thin films, the effects of Ni addition and an oblique deposition method on the microstructures have been examined. The Ni addition to (Fe7Co3)B films was found to enhance B segregation on grain boundaries, which resulted in the formation of a well-defined columnar structure and the increase of film resistivity. Utilizing
Eunji Yu; Jong Sik Shim; Inyoung Kim; Jongryoul Kim; Suk Hee Han; Hi Jung Kim; Ki Hyeon Kim; Masahiro Yamaguchi
Solution-processed flexible transparent conductors based on carbon nanotubes and silver grid hybrid films.
In a simple, cost-effective, and solution-based process, a thin-film of single-walled carbon nanotubes is hybridized on a PET film which has been patterned with solution self-assembled Ag nanoparticles. Such a flexible and transparent electrode exhibits a sheet resistance down to ?5.8 ? sq(-1) at ?83.7% optical transmittance. The hybrid films are stable under ambient conditions and offer excellent bendability. PMID:24675812
Wang, Jing; Zhang, Jintao; Sundramoorthy, Ashok Kumar; Chen, Peng; Chan-Park, Mary B
Influence of annealing on the absorption of Bi-based iron garnet films
Annealing of LPE-grown iron garnet films in reducing atmosphere changes their optical absorption and their electrical conductivity. In Bi-based films where the dominant impurity, lead reaches 0.35 mole%, both the conductivity and the absorption below 2.4 eV decrease after annealing. Annealing experiments were performed on films approximated as (Bi.6Pb.06Tm22.34)(Fe4Ga1)12. The maximum observed decrease in absorption was of the order of
A. Akselrad; R. E. Novak; D. L. Patterson
Properties of composite film based on bigeye snapper surimi protein and lipids
Prodpran, T., Chinabhark, K. and Benjakul, S. Properties of composite film based on bigeye snapper surimi protein and lipids Songklanakarin J. Sci. Technol., Dec. 2005, 27(Suppl. 3) : 775-788 Lipids were incorporated into bigeye snapper surimi protein films through emulsification using Tween-20 as a surfactant to form protein\\/lipid composite films. The effects of lipid types (palm oil, butter or shortening)
Thummanoon Prodpran; Krittabhart Chinabhark
Advanced electrochromic devices based on WO 3 thin films
We present work on the development of advanced materials suitable for use as electrochromic thin films (EC), ion storage layers and transparent conductors (TC) in electrochromic devices. These thin film layers were prepared in our laboratory by thermal evaporation and electron gun deposition. They were incorporated into electrochromic devices, which were subsequently characterized by optical and electrochemical techniques such as
S Papaefthimiou; G Leftheriotis; P Yianoulis
Biopolymer composite films based on ?-carrageenan and chitosan
Bioploymer composite films of ?-carrageenan and chitosan were prepared by co-dissolving ?-carrageenan and chitosan in several different organic acids. Tensile strength (TS), elongation (E), and water vapor permeability (WVP) were determined as a function of ascorbic acid added. Ascorbic acid tends to increase the properties of the films from all acids. Malic acid exhibited largest increase in tensile strength and
Sun Y. Park; Burtrand I. Lee; Soon T. Jung; Hyun J. Park
Molecular and Culture-Based Analyses of Prokaryotic Communities from an Agricultural Soil and the Burrows and Casts of the Earthworm Lumbricus rubellus
The microbial populations in no-till agricultural soil and casts of the earthworm Lumbricus rubellus were examined by culturing and molecular methods. Clone libraries of the 16S rRNA genes were prepared from DNA isolated directly from the soil and earthworm casts. Although no single phylum dominated the soil library of 95 clones, the largest numbers of clones were from Acidobacteria (14%),
Michelle A. Furlong; David R. Singleton; David C. Coleman; William B. Whitman
Titan Casts Revealing Shadow
A rare celestial event was captured by NASA's Chandra X-ray Observatory as Titan -- Saturn's largest moon and the only moon in the Solar System with a thick atmosphere -- crossed in front of the X-ray bright Crab Nebula. The X-ray shadow cast by Titan allowed astronomers to make the first X-ray measurement of the extent of its atmosphere. On January 5, 2003, Titan transited the Crab Nebula, the remnant of a supernova explosion that was observed to occur in the year 1054. Although Saturn and Titan pass within a few degrees of the Crab Nebula every 30 years, they rarely pass directly in front of it. "This may have been the first transit of the Crab Nebula by Titan since the birth of the Crab Nebula," said Koji Mori of Pennsylvania State University in University Park, and lead author on an Astrophysical Journal paper describing these results. "The next similar conjunction will take place in the year 2267, so this was truly a once in a lifetime event." Animation of Titan's Shadow on Crab Nebula Animation of Titan's Shadow on Crab Nebula Chandra's observation revealed that the diameter of the X-ray shadow cast by Titan was larger than the diameter of its solid surface. The difference in diameters gives a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere. The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. "Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may account for some of this atmospheric expansion," said Hiroshi Tsunemi of Osaka University in Japan, one of the coauthors on the paper. The X-ray brightness and extent of the Crab Nebula made it possible to study the tiny X-ray shadow cast by Titan during its transit. By using Chandra to precisely track Titan's position, astronomers were able to measure a shadow one arcsecond in diameter, which corresponds to the size of a dime as viewed from about two and a half miles. Illustration of Crab, Titan's Shadow and Chandra Illustration of Crab, Titan's Shadow and Chandra Unlike almost all of Chandra's images which are made by focusing X-ray emission from cosmic sources, Titan's X-ray shadow image was produced in a manner similar to a medical X-ray. That is, an X-ray source (the Crab Nebula) is used to make a shadow image (Titan and its atmosphere) that is recorded on film (Chandra's ACIS detector). Titan's atmosphere, which is about 95% nitrogen and 5% methane, has a pressure near the surface that is one and a half times the Earth's sea level pressure. Voyager I spacecraft measured the structure of Titan's atmosphere at heights below about 300 miles (500 kilometers), and above 600 miles (1000 kilometers). Until the Chandra observations, however, no measurements existed at heights in the range between 300 and 600 miles. Understanding the extent of Titan's atmosphere is important for the planners of the Cassini-Huygens mission. The Cassini-Huygens spacecraft will reach Saturn in July of this year to begin a four-year tour of Saturn, its rings and its moons. The tour will include close flybys of Titan that will take Cassini as close as 600 miles, and the launching of the Huygens probe that will land on Titan's surface. Chandra's X-ray Shadow of Titan Chandra's X-ray Shadow of Titan "If Titan's atmosphere has really expanded, the trajectory may have to be changed." said Tsunemi. The paper on these results has been accepted and is expected to appear in a June 2004 issue of The Astrophysical Journal. Other members of the research team were Haroyoski Katayama (Osaka University), David Burrows and Gordon Garmine (Penn State University), and Albert Metzger (JPL). Chandra observed Titan from 9:04 to 18:46 UT on January 5, 2003, using its Advanced CCD Imaging Spectrometer instrument. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the Office of Space Science, NASA Headquarters,
Characterization of antioxidant methylcellulose film incorporated with ?-tocopherol nanocapsules.
Biodegradable and antioxidant films based on methylcellulose (MC) and ?-tocopherol nanocapsule suspension (NCs) were developed. MC and NCs films were prepared by a casting method in three different proportions. The mechanical, wettability, colour, light transmission, antioxidant and release characteristics of the films were studied. The addition of NCs to MC films decreased the tensile strength (TS) and the elastic modulus (EM) (p<0.05) but increased the percentage elongation at break (%E) and thickness (p<0.05). NCs films showed a higher hydrophobicity when compared to that of film control. Lightness and yellowish color were intensified in the NCs films which, in their turn, demonstrated high antioxidant activity and excellent barrier properties against UV and visible light. A burst and prolonged release of ?-tocopherol to food simulant was also reported. PMID:24767092
Noronha, Carolina Montanheiro; de Carvalho, Sabrina Matos; Lino, Renata Calegari; Barreto, Pedro Luiz Manique
Silver nanowire-based transparent, flexible, and conductive thin film
The fabrication of transparent, conductive, and uniform silver nanowire films using the scalable rod-coating technique is described in this study. Properties of the transparent conductive thin films are investigated, as well as the approaches to improve the performance of transparent silver nanowire electrodes. It is found that silver nanowires are oxidized during the coating process. Incubation in hydrogen chloride (HCl) vapor can eliminate oxidized surface, and consequently, reduce largely the resistivity of silver nanowire thin films. After HCl treatment, 175 ?/sq and approximately 75% transmittance are achieved. The sheet resistivity drops remarkably with the rise of the film thickness or with the decrease of transparency. The thin film electrodes also demonstrated excellent flexible stability, showing < 2% resistance change after over 100 bending cycles.
Mechanical, physicochemical and color properties of chitosan based-films as a function of Aloe vera gel incorporation
The objective of the present study was to investigate the effect of Aloe vera gel incorporation at different proportions on chitosan-based films. Consequently, the thickness of films was affected significantly by the addition of the gel and decreased from F0 (plain chitosan film) to F50 (the film containing 50% gel). The gel incorporation did not have a considerable effect on
Sadegh Khoshgozaran-Abras; Mohammad Hossein Azizi; Zohreh Hamidy; Niloofar Bagheripoor-Fallah
Establishing relationship between the base metal properties and friction stir welding process parameters of cast aluminium alloys
In friction stir welding (FSW), the material under the rotating action of non-consumable tool has to be stirred properly to get defect free welds in turn it will improve the strength of the welded joints. The welding conditions and parameters are differing based on the mechanical properties of base materials such as tensile strength, ductility and hardness which control the
M. Jayaraman; R. Sivasubramanian; V. Balasubramanian
Lockheed Martin Corporation (LMC) tasked The University of Arizona Steward Observatory (UASO) to conduct an engineering study to examine the feasibility of creating a 4m space telescope based on mature borosilicate technology developed at the UASO for ground-based telescopes. UASO has completed this study and concluded that existing launch vehicles can deliver a 4m monolithic telescope system to a 500
S. C. West; S. H. Bailey; S. Bauman; B. Cuerden; Z. Granger; B. H. Olbert
Transparent chitosan films reinforced with a high content of nanofibrillated cellulose
This paper reports the preparation and characterization of nanocomposite films based on different chitosan matrices and nanofibrillated cellulose (NFC) for the purpose of improving strength properties. The nanocomposite films were prepared by a simple procedure of casting a water-based suspension of chitosan and NFC, and were characterized by several techniques: namely SEM, X-ray diffraction, visible spectrophotometry, TGA, tensile and dynamic-mechanical
Susana C. M. Fernandes; Carmen S. R. Freire; Armando J. D. Silvestre; Carlos Pascoal Neto; Alessandro Gandini; Lars A. Berglund; Lennart Salmķn
Versatile fluoride substrates for Fe-based superconducting thin films
We demonstrate the growth of Co-doped BaFe2As2 (Ba-122) thin films on CaF2 (001), SrF2 (001), and BaF2 (001) single crystal substrates using pulsed laser deposition. All films are grown epitaxially despite of a large misfit of -10.6% for BaF2 substrate. For all films, a reaction layer is formed at the interface confirmed by X-ray diffraction and for the films grown on CaF2 and BaF2 additionally by transmission electron microscopy. The superconducting transition temperature of the film on CaF2 is around 27 K, whereas the corresponding values of the films on SrF2 and BaF2 are around 22 K and 21 K, respectively. The Ba-122 on CaF2 shows almost identical crystalline quality and superconducting properties as films on Fe-buffered MgO.
Kurth, F.; Reich, E.; Hõnisch, J.; Ichinose, A.; Tsukada, I.; H³hne, R.; Trommler, S.; Engelmann, J.; Schultz, L.; Holzapfel, B.; Iida, K.
Water vapor adsorption isotherms of agar-based nanocomposite films.
Adsorption isotherms of agar and agar/clay nanocomposite films prepared with different types of nanoclays, that is, a natural montmorillonite (Cloisite Na(+) ) and 2 organically modified montmorillonites (Cloisite 30B and Cloisite 20A), were determined at 3 different temperatures (10, 25, and 40 ░C). The water vapor adsorption behavior of the nanocomposite films was found to be greatly influenced with the type of clay. The Guggenheim-Anderson-de Boer (GAB) isotherm model parameters were estimated by using both polynomial regression and nonlinear regression methods and it was found that the GAB model fitted adequately for describing experimental adsorption isotherm data for the film samples. The monolayer moisture content (m(o) ) of the film samples was also greatly affected by the type of nanoclay used, that is, m(o) of nanocomposite films was significantly lower than that of the neat agar film. Nanocomposite films prepared with hydrophobic nanoclays (Cloisite 30B and Cloisite 20A) exhibited lower m(o) values than those prepared with hydrophilic nanoclay (Cloisite Na(+) ). PMID:22417601
Rhim, Jong-Whan
Infrared optics applications of thin polyaniline emeraldine base films
The use of polyaniline emeraldine base films as antireflection coating for near and middle IR optics elements was studied. The optical quality of ZnSe substrates spin-coated with thin PANI EB layers were studied using a Linnik interferometer. The spectral properties of PANI coated ZnSe plates were investigated in broad IR band with FTIR spectrometer. It was shown that PANI coating allows a significant decrease of Fresnel losses in the near and middle IR bands (1.0-6.25 ?m). The coating allowed continuous transmission of high power density of IR radiation produced by CO2 laser. The transmission coefficient doesn't depend on the incident laser beam power density (up to 3 W/mm2). The laser irradiation damage threshodl of the PNAI EB coating was studied at a wavelength of 1.5 ?m and established as high as 0.1 GW/mm2 (?=12 10-9s) for PANI EB coating wtih a thickness of 150 nm. Microhardness of the PANI EB coated ZnSe plates was established as satisfactory.
Bormashenko, Edward; Pogreb, Roman; Sutovski, Semion; Shulzinger, Alexander; Sheshnev, Avigdor; Izakson, Gregory; Katzir, Abraham
Transmission type color filter incorporating a silver film based etalon.
Transmission type color filters based on a thin film Ag-SiO(2)-Ag etalon were built on a quartz substrate, enabling the infrared suppressed transmission and large effective area. They were designed by taking into account the influence of the dispersion characteristics and the thickness of the silver metal. Three different color filters were devised: The cavity length for the red, green and blue filter was 160 nm, 130 nm, and 100 nm respectively, while the metal layer was fixed at 25 nm. The observed spectral pass band was centered at 650 nm, 555 nm, and 480 nm for the red, green, and blue device; the corresponding bandwidth was about 120 nm, 100 nm, and 120 nm; and the peak transmission was all ~60%. For the oblique light incidence the angular dependence of the peak relative transmission was measured to be approximately 1%/degree. The spectral response of the device was also analyzed for two different polarizations as the tilt angle varied up to 12(o), and it was found to be hardly polarization dependent. Finally, as for the positional dependence the relative transmission and the center wavelength were found to vary within 10% and 5 nm respectively over an effective area of 4x4 cm(2). PMID:20389548
Yoon, Yeo-Taek; Lee, Sang-Shin
Electromechanical characteristics of hybrid transparent conductive films based on graphene with a silver grid
A systematic study of the electromechanical properties of graphene films with a silver (Ag) grid is presented for a flexible transparent electrode. Two hybrid structures of a graphene film with a Ag grid, where the silver grid is parallel or aligned at 45░ to the direction of bending, were synthesized on polyethylene terephthalate (PET) substrates. The optical transmittance of the graphene/Ag grid was 90.4%, and the sheet resistance was 29.4 ?/square. The electromechanical properties of the hybrid films were investigated using an inner/outer bending test system. Compared to the film with Ag grid parallel to the direction of bending, the hybrid film with the Ag grid aligned 45░ to the direction of bending showed superior electromechanical properties. Additionally, the linear resistance of the hybrid structure of a graphene film and a Ag grid was measured. The linear resistance of the hybrid film changed slightly while that of the graphene film increased considerably with increasing distance between the two metal electrodes. The results provide useful electromechanical properties for hybrid transparent conductive films based on a graphene film and a Ag grid for the development of flexible optoelectronics.
Kim, Sung Man; Kang, Seong Jun
Antimicrobial and in vitro wound healing properties of novel clay based bionanocomposite films.
The present study investigates the development of methyl cellulose (MC)-sodium alginate (SA)-montmorillonite (MMT) clay based bionanocomposite films with interesting wound healing properties. The differential scanning calorimetry analysis of the composite films revealed presence of single glass transition temperature (Tg) confirming the miscible nature of the ternary blended films. The increase in MMT ratio in the composite films reduced the mobility of biopolymer chains (MC/SA) which increased the Tg of the film. Thermogravimetric analysis showed that dispersion of clay (MMT) at nano level significantly delayed the weight loss that correlated with higher thermal stability of the composite films. It was observed that the developed films were able to exhibit antimicrobial activity against four typical pathogenic bacteria found in the presence of wound. The developed films were able to significantly inhibit (10Āmg/ml) the growth of Enterococcus faecium and Pseudomonas aeruginosa. In vitro scratch assay indicated potential wound closure activities of MC-2-4 bionanocomposite films at their respective highest subtoxic doses. In conclusion, these ternary bionanocomposite films were found to be promising systems for wound healing applications. PMID:24831081
Mishra, R K; Ramasamy, K; Lim, S M; Ismail, M F; Majeed, A B A
An investigation into the effect of solidification shrinkage on distortion of casting and flexure strength of various solders for base metal alloys. A laboratory study.
This study was undertaken to determine the distortion due to solidification shrinkage and to evaluate the flexure strength properties of soldered joints between combination of three commercially available base metal alloys and solders. Ninety rectangular bars were cast using three commercially available alloys for soldering (30 bars of each alloys). Ten bars of each alloy were soldered using electrical soldering unit and solder recommended by respective manufacturers, twenty bars (ten pairs each) were soldered using other solders. Length between the references markings on the specimen were measured using a vernier caliper and travelling microscope to check the possible solidification shrinkage. The specimens were then subjected to flexure strength evaluation using a universal testing machine. Statistical comparison of dimensional changes due to solidification shrinkage and flexure strength evaluation of soldered joints was done using analysis of variance test. Recommended Ni-Cr solders showed less shrinkage compared to that of the Co-Cr solders from the tested specimens and superior flexure strength was found in Co-Cr alloy specimen (P value P > .001) soldered with Co-Cr alloy solders. PMID:11307248
Harikesh, P; Shetty, P; Patil, N P; Jagdish, H G
The role of iron in the formation of porosity in Al-Si-Cu-based casting alloys. Part 3: A microstructural model
Iron has been shown to have a significant effect on the formation of porosity and shrinkage defects in Al-Si-Cu-based foundry alloys. This is not simply a direct consequence of the physical presence of the {beta}-Al{sub 5}FeSi platelets in the microstructure, but is also due to the effect that these platelets have on the nucleation and growth of eutectic silicon. The alloy-dependent critical iron content determines when the {beta} phase first solidifies and, hence, when it can participate in the silicon nucleation event. At critical iron contents, the {beta} phase solidifies as the initial component of the ternary eutectic. However, at supercritical iron contents, the {beta} phase solidifies as the initial component of the ternary eutectic solidification begins, while, at subcritical iron contents, the {beta} phase forms as a component of the ternary eutectic only after the binary Al-Si eutectic is well established. Each of these paths of microstructural evolution leads to different variations in microstructural permeability and, hence, interdendritic feedability and porosity formation. The actual porosity-forming response to these alloy-induced microstructural changes is influenced by the solidification conditions in the casting.
Taylor, J.A.; Schaffer, G.B.; StJohn, D.H. [Univ. of Queensland, Brisbane, Queensland (Australia)
Architectural optimization of an epoxy-based hybrid sol-gel coating for the corrosion protection of a cast Elektron21 magnesium alloy
An epoxy-based hybrid sol-gel coating was prepared in various architectural configurations has been studied for the corrosion protection of a cast Elektron21 magnesium alloy. The creation of a single layer of this coating presents defects consisting of macro-pores and protuberances, which opens access for corrosive species to reach the metallic substrate. These defects are suspected to result from the high reactivity of the substrate, as well as to the irregular topography of the substrate disrupted by the microstructure of the own magnesium alloy. Hence, a sol-gel coating in bilayer architecture is proposed, where the first layer would ōinertö the surface of the magnesium substrate, and the second layer would cover the defects of the first layer and also thickening the coating. The morphological characteristics of the sol-gel coatings were analyzed by scanning electron microscopy (SEM), and their corrosion behavior was evaluated by OCP (open circuit potential) monitoring and electrochemical impedance spectroscopy (EIS) in chloride media. It is shown that both the architectural arrangement and the individual thickness of the first and second layers have an important influence on the anticorrosion performances of the protective system, just as much as its global thickness.
Murillo-Gutiķrrez, N. V.; Ansart, F.; Bonino, J.-P.; Kunst, S. R.; Malfatti, C. F.
Plastic reference electrodes and plastic potentiometric cells with dispersion cast poly(3,4-ethylenedioxythiophene) and poly(vinyl chloride) based membranes.
A simple procedure of preparing low cost, planar and disposable reference electrodes for potentiometric applications is presented. This method is essentially the same as used for obtaining all-plastic ion-selective electrodes and thus promising for simple fabrication of complete cells. Commercially available aqueous dispersion of poly(3,4-ethylenedioxythiophene) doped by poly(4-styrenesulfonate) ions (PEDOT-PSS, Baytron P) is simply cast on a non-conducting plastic support (transparent foil for laser printers). This layer is covered by a non-selective poly(vinyl chloride) based membrane containing solid AgCl and KCl, added to obtain a stable potential. The conducting polymer layer plays a double role, of electrical contact and ion-to-electron transducer, enhancing the potential stability. The reference electrodes obtained exhibit independence of the kind and concentration of electrolyte applied as well as very low sensitivity to interferences: redox reactants and H+ ions; they are also characterized by both potential stability and low polarisability, sufficient for potentiometric applications. Cells of plastic electrodes (indicator and reference ones) are tested using an arrangement with Pb2+ or Ca2+ selective sensors. Potentiometric characteristic of such cells is satisfactory, well comparable with that using a classical electrode arrangement. PMID:17107827
Kisiel, Anna; Michalska, Agata; Maksymiuk, Krzysztof
Thermovoltaic effect in thin-film samarium-sulfide-based structures
We report the first observation of a thermovoltaic effect in thin films of samarium sulfide (SmS). According to this, a voltage of ś1.1 V appeared in a thin-film SmS-based sandwich structure heated to temperatures in the 360 428 K interval.
Kaminski?, V. V.; Kazanin, M. M.
Comparison of palladium thin films used in a transmission based optical fibre hydrogen sensor
Results are presented of a comparison between two palladium films of different thicknesses used as the sensing element in a transmission based optical fiber hydrogen sensor. The palladium films, 16nm and 26nm thick, were deposited onto glass substrates using thermal vacuum evaporation. The absorption and desorption of hydrogen causes the optical properties of palladium to change depending on the concentration
K. Gleeson; E. Lewis
Magnetic sensor based on side-polished fiber Bragg grating coated with iron film
A novel optical fiber magnetic sensor based on a side-polished fiber Bragg grating (FBG) coated with thin iron film was investigated. The sensor consists of a side-polished 10 mm FBG and two-layer thin iron films deposited on an interaction section 20 mum in diameter.
C. Tien; C. Hung; H. Chen; W. Liu; S. Lin
High temperature strain gages based on reactively sputtered AlN x thin films
Thin film strain sensors based on reactively sputtered aluminum nitride are being developed for a variety of advanced aerospace applications, where the measurement of both static and dynamic strain is required at elevated temperatures. The non-stoichiometric AlNx thin films are particularly attractive for strain sensor applications at elevated temperatures since they exhibit a relatively large gage factor G, and a
Otto J. Gregory; Arnout Bruins Slot; Paul S. Amons; Everett E. Crisman
Characterisation of gelatin¢fatty acid emulsion films based on blue shark ( Prionace glauca) skin gelatin
Incorporation of fatty acids (stearic and oleic) into edible films based on blue shark (Prionace glauca) skin gelatin was investigated to modify properties such as water vapour barrier and flexibility due to their hydrophobicity and plasticizing effect, respectively. Addition of stearic acid from 0% to 100% of protein concentration in the film-forming solution considerably decreased water vapour permeability of gelatin¢fatty
Kanokrat Limpisophon; Munehiko Tanaka; Kazufumi Osako
Residual stress and fracture in thick tetraethylorthosilicate (TEOS) and silane-based PECVD oxide films
This paper reports residual stress measurements and fracture analysis in thick tetraethylorthosilicate (TEOS) and silane-based plasma enhanced chemical vapor deposition (PECVD) oxide films. The measured residual stress depended strongly on thermal process parameters; dissolved hydrogen gases played an important role in governing intrinsic stress. The tendency to form cracks was found to be a strong function of film thickness and
X. Zhang; K.-S. Chen; R. Ghodssi; A. A. Ay¾n; S. M. Spearing
Achromatic circular polarizer in the 482-535 nm range based on polypropylene films
We present a design for an achromatic circular polarizer based on polypropylene films. The circular polarizer, having eccentricity ?0.92 in the 482-535 nm range and ideally circular for the wavelength of ~505 nm, is obtained by combining BOPP C2-25 and BOPP C2-35 films of thickness 23 m and 33 ?m.
Muravsky, Al. A.; Murauski, An. A.; Agabekov, V. E.; Chuvasheva, O. O.; Ivanova, N. A.
Properties of composites based on polyvinyl alcohol containing biologically active substances and films made of them
The effect of the composition of spinning composites based on polyvinyl alcohol containing biologically active substances on their rheological properties and the structure of films fabricated from these composites by the dry method was investigated. It was shown that addition of protein and antimicrobial substances to the composite and alteration of the spinning temperature result in films of different structure
N. R. Kil'deeva; S. P. Trusova; N. S. Pilevskaya; A. D. Virnik
Oligocarbazole-based chromophores for efficient thin-film dye-sensitized solar cells.
Carb your enthusiasm: Carbazole-based sensitizers with high extinction coefficients are synthesized for application in dye-sensitized solar cells (DSCs). The dyes perform efficiently with both iodine and cobalt electrolytes, showing power conversion efficiencies of up to 5.8% on TiO? films of 15 ?m thickness, and retaining 90% of their efficiency in devices with thinner films. PMID:23674249
De Sousa, Samuel; Olivier, Cķline; Ducasse, Laurent; Le Bourdon, Gwenaļlle; Hirsch, Lionel; Toupance, Thierry
Tensile properties of as-cast iron-aluminide alloys
Room-temperature tensile properties of as-cast Fe{sub 3}Al-based FA-129 alloy were investigated. Tensile properties were obtained in the as-cast condition in air, oxygen, and water-vapor environments, and after homogenization at 700, 900, and 1200{degrees}C. Transmission electron microscopy (MM) was used to characterize ordered phases and dislocation structure, and optical metallography and scanning electron microscopy (SEM) were used to characterize the grain microstructure and fracture morphology. Tensile properties in the as-cast condition exhibited an environmental effect; tensile ductilities in oxygen atmosphere were greater than those obtained in laboratory air. Homogenized samples of FA-129 alloy exhibited almost twice the ductility found in the as-cast condition. Microstructural characterization of the homogenized samples and comparison of the as-cast and homogenized microstructures provided clues that helped to explain the poor ductility in the as-cast state.
Viswanathan, S.; McKamey, C.G.; Maziasz, P.J.
Ammonia sensor based on WO3 thin films
WO3 thin films deposited using a simple method of vacuum evaporation has been investigated for their NH3 sensing properties. Effect of process parameters namely operating temperature, film thickness and amount of Au in the WO3 host matrix have been investigated and correlated with the observed sensitivity values to obtain the optimum sensor with improved sensing characteristics towards NH3. Pure WO3 films with thickness of 600 nm and the Au incorporated WO3 containing 0.034 wt.% Au were observed to exhibit a superior sensing property towards NH3.
Ramgir, Niranjan; Datta, Niyanta; Kaur, Manmeet; Kailasaganapati, S.; Debnath, A. K.; Aswal, D. K.; Gupta, S. K.
Electrodeposited Fe-Co films prepared from a citric-acid-based plating bath
Electrodeposited Fe-Co films are commonly prepared in a boric-acid-based bath. In this research, we applied citric acid instead of boric acid for the plating of Fe-Co films because boron in the waste bath is restricted by environmental-protection regulations in Japan. We evaluated the effect of citric acid on the magnetic and structural properties of the films. The saturation magnetization of the Fe-Co films slightly increased while the Fe content in the Fe-Co films decreased with increasing citric acid concentration. The lowest coercivity value of 240 A/m was obtained at a citric acid concentration of 100 g/L. The plating bath with this citric acid concentration enabled us to obtain Fe-Co films with high saturation magnetizations and smooth surface morphologies.
Yanai, T.; Uto, H.; Shimokawa, T.; Nakano, M.; Fukunaga, H.; Suzuki, K.
Synthesis of carbon films in a plasma-chemical reactor based on beam-plasma discharge
A modification of the plasma-chemical reactor based on beam-plasma discharge is developed for the deposition of carbon (including diamond-like carbon (DLC)) films. The reactor differs from the existing devices by the simplicity of the procedure that makes it possible to control the energy characteristics of the ion beam incident on the film in the course of deposition. A method for the computer simulation of the parameters of the ion flux on an electrically insulated surface upon the modulation of the plasma potential is proposed. The method allows the prediction of the ion energy and ion flux that acts upon the deposited film. DLC films on metal substrates are produced. The charge deep-level transient spectroscopy is used to reveal the effect of the adsorbed water and alcohol vapors on the electrophysical properties of the films, which indicates that the films can be used as active adsorbing materials in chemical sensors.
Shustin, E. G.; Isaev, N. V.; Klykov, I. L.; Peskov, V. V.; Polyakov, V. I.; Rukovishnikov, A. I.; Temiryazeva, M. P.
Quartz ceramic nozzles for casting steel on continuous casting plant
Conclusions A technology was developed for making steel casting nozzles for the continuous casting of steel with different versions of lateral input of metal into the crystallizer. In laboratory conditions we made nozzles 600¢650 mm long.
R. S. Churakova; E. P. Fedorova; Yu. A. Polonskii; E. I. Ermolaeva; A. M. Pozhivanov; N. D. Karpov
Properties of blend film based on cuttlefish (Sepia pharaonis) skin gelatin and mungbean protein isolate.
Blend films based on cuttlefish (Sepia pharaonis) ventral skin gelatin (CG) and mungbean protein isolate (MPI) at different blend ratios (CG/MPI=10:0, 8:2, 6:4, 4:6, 2:8 and 0:10, w/w) prepared at pH 11 using 50% glycerol (based on total protein) as plasticizer were characterized. CG films incorporated with MPI at increasing amounts had the decreases in tensile strength (TS) (p<0.05). The increases in elongation at break (EAB) were observed when CG/MPI ratios of 6:4 or 4:6 were used (p<0.05). Decreased water vapor permeability (WVP) was obtained for films having the increasing proportion of MPI (p<0.05). CG/MPI blend films with higher MPI proportion had lower film solubility and L*-values (lightness) but higher b*-values (yellowness) and ?E*-values (total color difference) (p<0.05). Electrophoretic study revealed that disulfide bond was present in MPI and CG/MPI blend films. However, hydrogen bonds between CG and MPI in the film matrix were dominant, as elucidated from FTIR spectroscopic analysis. Moreover, thermal stability of CG/MPI blend film was improved as compared to that of films from respective single proteins. Differential scanning calorimetry result suggested solid-state morphology of CG/MPI (6:4) blend film that consisted of amorphous phase of partially miscible CG/MPI mixture and the coexisting two different order phases of individual CG and MPI domains. Thus, the incorporation of MPI into gelatin film could improve the properties of resulting blend film, which were governed by CG/MPI ratio. PMID:21762722
Hoque, Md Sazedul; Benjakul, Soottawat; Prodpran, Thummanoon; Songtipya, Ponusa
Characterization of polymer, DNA-based, and silk thin film resistivities and of DNA-based films prepared for enhanced electrical conductivity
DC resistivity studies were carried out on biopolymer films of DNA-CTMA and silk fibroin, and on selected traditional polymer films, including PMMA and APC. Films of DNA-CTMA versus molecular weight and with conductive dopants PCBM, BAYTRON P and ammonium tetrachloroplatinate are reported. The films were spin coated on glass slides configured for measurements of volume dc resistance. The measurements used the alternating polarity method to record the applied voltage-dependent current independent of charging and background currents. The Arrhenius equation plus a constant was fitted to the conductivity versus temperature data of the polymers and the non-doped DNA-based biopolymers with activation energies ranging from 0.8 to 1.4 eV.
Yaney, Perry P.; Ouchen, Fahima; Grote, James G.
Optimisation of parameters for aqueous tape-casting of cordierite-based glass ceramics by Taguchi method
Aqueous suspensions of cordierite-based glass ceramics were prepared by using four types of dispersants and binders and different solids loading. The experiments were designed according to the Taguchi method, which shows great advantages in optimising more than two factors that need to be considered in an experimental design. Different parameters such as the type and concentration of the dispersants and
Sen Mei; Juan Yang; Josķ Maria F Ferreira; Rodrigo Martins
SWNT/PAN Composite Film based SuperCapacitors
Activated carbon powder and activated carbon fiber, due to their high specific surface area, porous characteristics, relatively high electrical conductivity and good chemical resistance, have been extensively investigated as the electrode materials for an electrochemical supercapacitor. In the present study, a core-shell structured SWNT/Polyacrylonitrile (PAN) composite film has been produced with 30 nm in diameter SWNT bundles as the core and 10 nm thick PAN polymers as the shell. SEM was used to investigate the evolution of the porous structure of S