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Multicomponent Geothermometers | Open Energy Information
Open Energy Info (EERE)
Multicomponent Geothermometers Multicomponent Geothermometers Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Multicomponent Geothermometers Details Activities (0) Areas (0) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Geochemical Techniques Exploration Sub Group: Geochemical Data Analysis Parent Exploration Technique: Liquid Geothermometry Information Provided by Technique Lithology: Stratigraphic/Structural: Hydrological: Thermal: Dictionary.png Multicomponent Geothermometers: The multicomponent geothermometry method consists of using full chemical analyses of water samples to compute the saturation indices (log(Q/K)) of reservoir minerals over a range of temperatures. The saturation indices are graphed as a function of temperature, and the clustering of log(Q/K) curves
Silica Geothermometers | Open Energy Information
Silica Geothermometers Silica Geothermometers Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Silica Geothermometers Details Activities (0) Areas (0) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Geochemical Techniques Exploration Sub Group: Geochemical Data Analysis Parent Exploration Technique: Liquid Geothermometry Information Provided by Technique Lithology: Stratigraphic/Structural: Hydrological: Thermal: Used to estimate reservoir temperatures. Dictionary.png Silica Geothermometers: No definition has been provided for this term. Add a Definition Introduction Some experts have stated that the factor that changes the risk assessment of a geothermal prospect the fastest is obtaining attractive chemical confirmation (geothermometry, gas analyses) that a thermal resource exists
Definition: Multicomponent Geothermometers | Open Energy Information
Multicomponent Geothermometers Multicomponent Geothermometers Jump to: navigation, search Dictionary.png Multicomponent Geothermometers The multicomponent geothermometry method consists of using full chemical analyses of water samples to compute the saturation indices (log(Q/K)) of reservoir minerals over a range of temperatures. The saturation indices are graphed as a function of temperature, and the clustering of log(Q/K) curves near zero at any specific temperature (for a group of certain reservoir minerals) is used to infer the reservoir temperature.[1] References ↑ Berkeley Lab Earth Sciences Division Website: GeoT: A Computer Program for Multicomponent Geothermometry and Geochemical Speciation Ret LikeLike UnlikeLike You like this.Sign Up to see what your friends like. rieved from
A BASIC program for calculating subsurface water temperatures using chemical geothermometers�implication to geothermal reservoir estimation
Science Conference Proceedings (OSTI)
Keywords: BASIC, Na-K-Ca geothermometer, Na/K ratio, geothermometer, silica geothermometer, subsurface temperature
Ali El-Naqa; Nasser Abu Zeid
CO/sub 2/-silica geothermometer for low temperature geothermal resource assessment, with application to resources in the Safford Basin, Arizona
DOE Green Energy (OSTI)
This study investigates silica-water reactions in low-temperature geothermal water in areas near Safford, southeastern Arizona, and derives a pCO2 correction for conductive silica geothermometers. Use and limitations of the technique are also discussed. Data collection, interpretation approach, and basic geochemistry, as it applies to this study, are outlined. In addition, the geology, thermal regime, geohydrology, and gross geochemistry of the Safford area are reviewed. Finally, geothermal potential, as indicated by this study and previous studies is discussed.
Witcher, J.C.; Stone, C.
A CO2-Silica Geothermometer for Low Temperature Geothermal Resource Assessment, with Application to Resources in the Safford Basin, Arizona
Geothermics is the study of the earth's heat energy, it's affect on subsurface temperature distribution, it's physical and chemical sources, and it's role in dynamic geologic processes. The term, geothermometry, is applied to the determination of equilibrium temperatures of natural chemical systems, including rock, mineral, and liquid phases. An assemblage of minerals or a chemical system whose phase composition is a function of temperature and pressure can be used as a geothermometer. Thus a geothermometer is useful to determine the formation temperature of rock or the last equilibrium temperature of a flowing aqueous solution such as ground water and hydrothermal fluids.
Witcher, James C.; Stone, Claudia
Cation Geothermometers | Open Energy Information
Cation Geothermometers Cation Geothermometers Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Cation Geothermometers Details Activities (0) Areas (0) Regions (0) NEPA(0) Exploration Technique Information Exploration Group: Geochemical Techniques Exploration Sub Group: Geochemical Data Analysis Parent Exploration Technique: Liquid Geothermometry Information Provided by Technique Lithology: Stratigraphic/Structural: Hydrological: Thermal: Used to estimate reservoir temperatures. Dictionary.png Cation Geothermometers: No definition has been provided for this term. Add a Definition Introduction Some experts have stated that the factor that changes the risk assessment of a geothermal prospect the fastest is obtaining attractive chemical confirmation (geothermometry, gas analyses) that a thermal resource exists
Chemical Geothermometers And Mixing Models For Geothermal Systems | Open
Geothermometers And Mixing Models For Geothermal Systems Geothermometers And Mixing Models For Geothermal Systems Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Chemical Geothermometers And Mixing Models For Geothermal Systems Details Activities (1) Areas (1) Regions (0) Abstract: Qualitative chemical geothermometers utilize anomalous concentrations of various "indicator" elements in groundwaters, streams, soils, and soil gases to outline favorable places to explore for geothermal energy. Some of the qualitative methods, such as the delineation of mercury and helium anomalies in soil gases, do not require the presence of hot springs or fumaroles. However, these techniques may also outline fossil thermal areas that are now cold. Quantitative chemical geothermometers and mixing models can provide information about present probable minimum
Application Of An Artificial Neural Network Model To A Na-K Geothermometer
Application Of An Artificial Neural Network Model To A Na-K Geothermometer Application Of An Artificial Neural Network Model To A Na-K Geothermometer Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: Application Of An Artificial Neural Network Model To A Na-K Geothermometer Details Activities (3) Areas (2) Regions (0) Abstract: A new geothermometer model is proposed by applying data obtained from a known Na-K geothermometer to an artificial neural network. In this model, Na and K values were implemented as input signals and geothermometers as the output signal. Multi-layer perceptrons and back propagation were used as training algorithms for the artificial neural network. Reservoir temperatures of some geothermal fields in Turkey determined by this method are in accord with those determined from other methods.
New Improved Equations For Na-K, Na-Li And Sio2 Geothermometers...
Improved Equations For Na-K, Na-Li And Sio2 Geothermometers By Outlier Detection And Rejection Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: New...
Physicochemical basis of the Na-K-Ca geothermometer
Regular changes in solution composition were observed experimentally during granite reaction with dilute NaCl (+CaCl/sub 2/) solutions; these changes closely follow the empirical Na-K-Ca geothermometer relationship. Initial minerals forming the granite (quartz, plagioclase, K-feldspar, and biotite) were etched by the reactions. Alteration phases formed include calcium-zeolite at <300/sup 0/C, feldspar overgrowths at >300/sup 0/C, and minor amounts of clay and calcsilicate at all temperatures. Amphibole overgrowths were also found at 340/sup 0/C. Quartz is near saturation in all experiments, and preliminary calculations of aqueous species distributions and mineral affinities indicate that the solutions achieve super-saturation with feldspars as the temperature increase. A consistent variation attributable to pH differences was observed in the empirical geothermometer relationship for all experimental data. At 340/sup 0/C, the experimental solutions appear to have deviated slightly from the empirical Na-K-Ca relationship. Such deviations may also be found in natural systems that attain such temperatures.
Janecky, D.R.; Charles, R.W.; Bayhurst, G.K.; Benjamin, T.M.
A New Improved Na-K Geothermometer By Artificial Neural Networks | Open
Improved Na-K Geothermometer By Artificial Neural Networks Improved Na-K Geothermometer By Artificial Neural Networks Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: A New Improved Na-K Geothermometer By Artificial Neural Networks Details Activities (0) Areas (0) Regions (0) Abstract: A new Na/K geothermometer equation has been developed. The temperature function is:Concentrations are in mg/kg. The new improved geothermometer equation was developed by artificial neural networks. The normalized mean square error (NMSE) used in the new improved Na/K equation for temperatures ranging from 94 to 345°C is 0.179, which is lower than the corresponding NMSE 0.226, 0.598, 0.656, 0.268, 0.328 and 0.225 for the equations of Arnorsson et al. (1983; Geochim. Cosmochim. Acta 47, 567-577), Truesdell (1975; Proc. 2nd UN Symposium), Tonani (1980; Proc. Adv. Eur.
New Improved Equations For Na-K, Na-Li And Sio2 Geothermometers By Outlier
Improved Equations For Na-K, Na-Li And Sio2 Geothermometers By Outlier Improved Equations For Na-K, Na-Li And Sio2 Geothermometers By Outlier Detection And Rejection Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: New Improved Equations For Na-K, Na-Li And Sio2 Geothermometers By Outlier Detection And Rejection Details Activities (1) Areas (1) Regions (0) Abstract: We present new improved equations for three still widely used Na/K, Na/Li and SiO2 geothermometers (obtained by statistical treatment of the data and application of outlier detection and rejection as well as theory of error propagation) and compare them with those by Fournier and others. New equations are also developed for estimating errors associated with the use of these new geothermometric equations and comparing them with the performance of the original equations. The errors in the use of the new
An Empirical Na-K-Ca Geothermometer For Natural Waters | Open Energy
Empirical Na-K-Ca Geothermometer For Natural Waters Empirical Na-K-Ca Geothermometer For Natural Waters Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: An Empirical Na-K-Ca Geothermometer For Natural Waters Details Activities (0) Areas (0) Regions (0) Abstract: An empirical method of estimating the last temperature of water-rock interaction has been devised. It is based upon molar Na, K and Ca concentrations in natural waters from temperature environments ranging from 4 to 340°C. The data for most geothermal waters cluster near a straight line when plotted as the function vs reciprocal of absolute temperature, where Β is either or depending upon whether the water equilibrated above or below 100°C. For most waters tested, the method gives better results than the methods suggested by other workers. The ratio
Improved silica geothermometer for low temperature geothermal resource assessment. Monthly progress report No. 2, February-March, 1983
Progress is reported on: literature search, collection of available lithologic and driller's logs, construction of geologic cross sections, and collection of water samples. (MHR)
Not Available
Silica Sand
NLE Websites -- All DOE Office Websites (Extended Search)
the molds and cores in foundries that make steel castings, and for casting gray iron, brass, aluminum and magnesium metals. Since silica sand has a very high melting point, it is...
Geochemical Techniques | Open Energy Information
Geochemical Techniques Geochemical Techniques Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Technique: Geochemical Techniques Details Activities (0) Areas (0) Regions (0) NEPA(1) Exploration Technique Information Exploration Group: Geochemical Techniques Exploration Sub Group: None Parent Exploration Technique: Exploration Techniques Information Provided by Technique Lithology: Stratigraphic/Structural: Hydrological: Thermal: Dictionary.png Geochemical Techniques: No definition has been provided for this term. Add a Definition Related Techniques Geochemical Techniques Geochemical Data Analysis Geothermometry Gas Geothermometry Isotope Geothermometry Liquid Geothermometry Cation Geothermometers Multicomponent Geothermometers Silica Geothermometers Thermal Ion Dispersion
Quasichemical Models of Multicomponent Nonlinear Diffusion
E-Print Network (OSTI)
Diffusion preserves the positivity of concentrations, therefore, multicomponent diffusion should be nonlinear if there exist non-diagonal terms. The vast variety of nonlinear multicomponent diffusion equations should be ordered and special tools are needed to provide the systematic construction of the nonlinear diffusion equations for multicomponent mixtures with significant interaction between components. We develop an approach to nonlinear multicomponent diffusion based on the idea of the reaction mechanism borrowed from chemical kinetics. Chemical kinetics gave rise to very seminal tools for the modeling of processes. This is the stoichiometric algebra supplemented by the simple kinetic law. The results of this invention are now applied in many areas of science, from particle physics to sociology. In our work we extend the area of applications onto nonlinear multicomponent diffusion. We demonstrate, how the mechanism based approach to multicomponent diffusion can be included into the general thermodynamic ...
Gorban, A N; Wahab, H A
Geothermal: Sponsored by OSTI -- Multicomponent Equilibrium Models...
Office of Scientific and Technical Information (OSTI)
GEOTHERMAL TECHNOLOGIES LEGACY COLLECTION - Sponsored by OSTI -- Multicomponent Equilibrium Models for Testing Geot Geothermal Technologies Legacy Collection HelpFAQ | Site Map |...
Visibly photoluminescent silica aerogels
Visibly photoluminescent silica aerogels Title Visibly photoluminescent silica aerogels Publication Type Journal Article Year of Publication 1997 Authors Ayers, Michael R., and...
Multicomponent fuel vaporization at high pressures.
We extend our multicomponent fuel model to high pressures using a Peng-Robinson equation of state, and implement the model into KIVA-3V. Phase equilibrium is achieved by equating liquid and vapor fugacities. The latent heat of vaporization and fuel enthalpies are also corrected for at high pressures. Numerical simulations of multicomponent evaporation are performed for single droplets for a diesel fuel surrogate at different pressures.
Torres, D. J. (David J.); O'Rourke, P. J. (Peter J.)
Modelling the Properties of Multi-Component Commercial Alloys
Materials Genomics Past & Future: From CALPHAD to Flight � Modelling the Properties of Multi-Component Commercial Alloys � Molecular Dynamics�...
Isotopic Interdiffusion Analysis and its Application in Multicomponent ...
Presentation Title, Isotopic Interdiffusion Analysis and its Application in Multicomponent ... Calorimetric studies of lithium ion cells and their constructing materials.
Electron-acoustic vortices in multicomponent magnetoplasma
Linear and nonlinear properties of electron-acoustic waves in a multicomponent magnetoplasma comprising of cold and beam electrons and two species of thermal unmagnetized ions are investigated here. It is found that the electron beam velocity, electron Debye length, electron Larmor radius, and concentration of the cold and beam electrons affect the linear dispersion characteristics of electron-acoustic wave. It is also found that such a multicomponent plasma admits dipolar and vortex street type structures for the normalized electrostatic potential PHIgeomagnetic tail, etc. is also pointed out.
Haque, Q. [Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad 45320 (Pakistan); Mirza, Arshad M. [Department of Physics, Theoretical Plasma Physics Group, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Nargis, Shahida [Department of Mathematics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)
Phase Stability of Multicomponent NAPLs Containing PAHs
natural or engineered process that acts to selectively extract compounds will alter NAPL composition examines the relationship between NAPL composition and liquid phase stability for mixtures of polycyclic as a subsurface environmental contaminant at sites of former manufactured gas plants (1). Multicomponent NAPLs
Peters, Catherine A.
Silica Scaling Removal Process
Silica Scaling Removal Process Silica Scaling Removal Process Silica Scaling Removal Process Scientists at Los Alamos National Laboratory have developed a novel technology to remove both dissolved and colloidal silica using small gel particles. Available for thumbnail of Feynman Center (505) 665-9090 Email Silica Scaling Removal Process Applications: Cooling tower systems Water treatment systems Water evaporation systems Potential mining applications (produced water) Industry applications for which silica scaling must be prevented Benefits: Reduces scaling in cooling towers by up to 50% Increases the number of cycles of concentration substantially Reduces the amount of antiscaling chemical additives needed Decreases the amount of makeup water and subsequent discharged water (blowdown) Enables considerable cost savings derived from reductions in
applications for which silica scaling must be prevented Benefits: Reduces scaling in cooling towers by up to 50% Increases the number of cycles of concentration substantially...
systems Water treatment systems Water evaporation systems Potential mining applications (produced water) Industry applications for which silica scaling must be prevented Benefits:...
Multicomponent Modified Boltzmann Equation and Thermalization
The existence of stationary distributions in a multicomponent Boltzmann equation using a non-additive kinetic energy composition rule for binary collisions is discussed. It is found that detailed balance is not achieved when -- in contrast to the case of a single rule -- several different composition rules are considered. The long-time behaviour of a simple momentum space model is explored numerically: saturating, heating and cooling solutions are presented.
M. Horv�th; T. S. Bir�
Discontinuous Galerkin formulation for multi-component multiphase flow.
??The understanding of multiphase multi-component transport in capillary porous media plays an important role in scientific and engineering disciplines such as the petroleum and environmental� (more)
Ho, Christina
Hydrogen separation using silica membranes
Silica membranes were synthesized on tubular supports of alumina by dipping in silica colloidal solutions. The quality and the performance of the silica membranes were tested by experiments on single gas permeation and gas separation of mixed N2, ... Keywords: Knudsen diffusion, colloidal solution, gas permeation, hydrogen separation, silica membranes
Salvador Alfaroa; Miguel A. Valenzuelaa; Pedro Bosch
Silica Embedded Metal Hydrides
A method to produce silica embedded metal hydride was developed. The product is a composite in which metal hydride particles are embedded in a matrix of silica. The silica matrix is highly porous. Hydrogen gas can easily reach the embedded metal hydride particles. The pores are small so that the metal hydride particles cannot leave the matrix. The porous matrix also protects the metal hydride particles from larger and reactive molecules such as oxygen, since the larger gas molecules cannot pass through the small pores easily. Tests show that granules of this composite can absorb hydrogen readily and withstand many cycles without making fines.
Heung, L.K. [Westinghouse Savannah River Company, AIKEN, SC (United States); Wicks, G.G.
I I I . Isotherm al Multicomponent Systems
Nonequilibrium C ontrib ution to the Rate o f R eaction Nonequilibrium C ontrib ution to the Rate o f R eaction I I I . Isotherm al Multicomponent Systems t B. S h izg a l* Department o f C hem istry, Harvard U n iv e r sity Cambridge, M assachusetts and Lorentz I n s t it u t e fo r T h e o r e tic a l P h y sics L eid en , N etherlands and M. Karplus Department o f C hem istry, Harvard U n iv e r sity Cambridge, M assachusetts ----------------------------- L E G A L N O T I C E -----------------------------
Kinetics of silica polymerization
The polymerization of silicic acid in geothermal brine-like aqueous solutions to produce amorphous silica in colloidal form has been studied experimentally and theoretically. A large amount of high quality experimental data has been generated over the temperature rang 23 to 100{sup 0}C. Wide ranges of dissolved silica concentration, pH, and sodium chloride concentration were covered. The catalytic effects of fluoride and the reaction inhibiting effects of aluminum and boron were studied also. Two basic processes have been separately studied: the formation of new colloidal particles by the homogeneous nucleation process and the deposition of dissolved silica on pre-existing colloidal particles. A rigorous theory of the formation of colloidal particles of amorphous silica by homogeneous nucleation was developed. This theory employs the Lothe-Pound formalism, and is embodied in the computer code SILNUC which quantitatively models the homogeneous nucleation and growth of colloidal silica particles in more than enough detail for practical application. The theory and code were extensively used in planning the experimental work and analyzing the data produced. The code is now complete and running in its final form. It is capable of reproducing most of the experimental results to within experimental error. It is also capable of extrapolation to experimentally inaccessible conditions, i.e., high temperatures, rapidly varying temperature and pH, etc.
Weres, O.; Yee, A.; Tsao, L.
From Multi-Component Gas Streams Opportunity
Separation of CO Separation of CO 2 From Multi-Component Gas Streams Opportunity Research is active on the patent-pending technology, titled "Apparatus and Process for the Separation of Gases Using Supersonic Expansion and Oblique Shock Wave Compression." This technology is available for licensing and/or further collaborative research from the U.S. Department of Energy's National Energy Technology Laboratory. Overview The separation of a gaseous mixture into constituent gases has proven to be useful for a variety of industrial and commercial applications. Currently CO 2 can be separated from multi- component gas streams using compression and refrigeration techniques in order to condense the CO 2 out of a vapor phase so that it can be mechanically separated from the stream.
Dynamic Component Extension: a Strategy for Performance Improvement in Multicomponent Applications
Multicomponent application paradigms have gained prominence in many significant multidisciplinary scientific applications. In this work, we propose a software strategy called dynamic component extension for multicomponent applications to improve application ... Keywords: coupled climate models, idling, load balancing, multicomponent applications, temporal load imbalances
Sundari M. Sivagama; Sathish S. Vadhiyar; Ravi S. Nanjundiah
Numerical Simulation of Multicomponent Ion Beam from Ion Sources
A program library for numerical simulation of a multicomponent charged particle beam from ion sources is presented. The library is aimed for simulation of high current, low energy multicomponent ion beam from ion source through beamline and realized under the Windows user interface for the IBM PC. It is used for simulation and optimization of beam dynamics and based on successive and consistent application of two methods: the momentum method of distribution function (RMS technique) and particle in cell method. The library has been used to simulate and optimize the transportation of tantalum ion beam from the laser ion source (CERN) and calcium ion beam from the ECR ion source (JINR, Dubna).
Alexandrov, V S; Kazarinov, Yu M; Shevtsov, V P; Shirkov, G D
The Single Pass Multi-component Harvester
SciTech Connect
The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily reflect the official position of the American Society of Agricultural Engineers (ASAE), and its printing and distribution does not constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review process by ASAE editorial committees; therefore, they are not to be presented as refereed publications. Citation of this work should state that it is from an ASAE meeting paper. EXAMPLE: Author's Last Name, Initials. 2004. Title of Presentation. ASAE Paper No. 04xxxx. St. Joseph, Mich.: ASAE. For information about securing permission to reprint or reproduce a technical presentation, please contact ASAE at email@example.com or 269-429-0300 (2950 Niles Road, St. Joseph, MI 49085-9659 USA). Abstract. In order to meet the U. S. government�s goal of supplementing the energy available from petroleum by increasing the production of energy from renewable resources, increased production of bioenergy has become one of the new goals of the United States government and our society. U.S. Executive Orders and new Federal Legislation have mandated changes in government procedures and caused reorganizations within the government to support these goals. The Biomass Research and Development Initiative is a multi-agency effort to coordinate and accelerate all U.S. Federal biobased products and bioenergy research and development. The Initiative is managed by the National Biomass Coordination Office, which is staffed by both the DOE and the USDA. One of the most readily available sources of biomass from which to produce bioenergy is an agricultural crop residue, of which straw from small grains is the most feasible residue with which to start. For the straw residue to be used its collection must be energy efficient and its removal must not impact the sustainability of the growing environment. In addition, its collection must be economically advantageous to the producer. To do all that, a single pass multi-component harvester system is most desirable. Results from our first prototype suggest that current combines probably do adequate threshing and that a separate chassis can be developed that does additional separation and that is economically feasible.
Reed Hoskinson; John R. Hess
Silica aerogel: synthesis and applications
Silica aerogels have drawn a lot of interest both in science and technology because of their low bulk density (up to 95% of their volume is air), hydrophobicity, low thermal conductivity, high surface area, and optical transparency. Aerogels are synthesized ...
Jyoti L. Gurav; In-Keun Jung; Hyung-Ho Park; Eul Son Kang; Digambar Y. Nadargi
Sample Desorption/Ionization From Mesoporous Silica
Sample Desorption/Ionization From Mesoporous Silica Sample Desorption/Ionization From Mesoporous Silica Sample Desorption/Ionization From Mesoporous Silica Mesoporous silica is shown to be a sample holder for laser desorption/ionization of mass spectrometry. Available for thumbnail of Feynman Center (505) 665-9090 Email Sample Desorption/Ionization From Mesoporous Silica Mesoporous silica is shown to be a sample holder for laser desorption/ionization of mass spectrometry. Supported mesoporous silica was prepared by coating an ethanolic silicate solution having a removable surfactant onto a substrate to produce a self-assembled, ordered, nanocomposite silica thin film. The surfactant was chosen to provide a desired pore size between about 1 nanometer diameter and 50 nanometers diameter. Removal of the surfactant resulted in a mesoporous silica thin
Synergism in Multicomponent Self-Propagating Molecular Assemblies
Multicomponent self-propagating molecular assemblies (SPMAs) have been generated from an organic chromophore, a redox-active polypyridyl complex, and PdCl{sub 2}. The structure of the multicomponent SPMA is not a linear combination of two assemblies generated with a single molecular constituent. Surface-confined assemblies formed from only the organic chromophore and PdCl{sub 2} are known to follow linear growth, whereas the combination of polypyridyl complexes and PdCl{sub 2} results in exponential growth. The present study demonstrates that an iterative deposition of both molecular building blocks with PdCl{sub 2} results in an exponentially growing assembly. The nature of the assembly mechanism is dictated by the polypyridyl complex and overrides the linear growth process of the organic component. Relatively smooth, multicomponent SPMAs have been obtained with a thickness of {approx}20 nm on silicon, glass, and indium-tin oxide (ITO) coated glass. Detailed information of the structure and of the surface-assembly chemistry were obtained using transmission optical (UV/Vis) spectroscopy, ellipsometry, atomic force microscopy (AFM), synchrotron X-ray reflectivity (XRR), and electrochemistry.
L Motiei; M Sassi; R Kaminker; G Evmenenko; P Dutta; M Iron; M van der Boom
Multicomponent seismic monitoring of strain due to CO2 injection at Delhi field, Louisiana.
??Time-lapse, multicomponent seismic data are used in this thesis to monitor geomechanical changes within the reservoir and in the overburden layers at Delhi Field, Louisiana.� (more)
Bishop, John E.
Copper-Based Multi-Component Alloys by Vacuum Distillation to ...
The result of experiment indicated the practicability of vacuum distillation dealing with copper base complex multi-component alloy to separating lead and silver,�...
Stabilized fuel with silica support structure
DOE Patents (OSTI)
This report describes a stabilized fuel which is supported by a silica support structure. The silica support structure provides a low density, high porosity vehicle for safely carrying hydrocarbon fuels. The silica support structure for hydrocarbon fuel does not produce toxic material residues on combustion which would pose environmentally sensitive disposal problems. The silica stabilized fuel composition is useful as a low temperature, continuous burning fire starter for wood or charcoal.
Poco, J.F.; Hrubesh, L.W.
Removal of dissolved and colloidal silica
Small amorphous silica particles are used to provide a relatively large surface area upon which silica will preferentially adsorb, thereby preventing or substantially reducing scaling caused by deposition of silica on evaporative cooling tower components, especially heat exchange surfaces. The silica spheres are contacted by the cooling tower water in a sidestream reactor, then separated using gravity separation, microfiltration, vacuum filtration, or other suitable separation technology. Cooling tower modifications for implementing the invention process have been designed.
Midkiff, William S. (Ruidoso, NM)
Form of multicomponent Fickian diffusion coefficients matrix J. Wambui Mutoru, Abbas Firoozabadi
and natural processes. However, experimental determinations of multicomponent diffu- sion coefficients that composition variation in multicomponent mixtures may differ markedly from binary mixtures due to cross that in ideal gas mixtures, all molecular diffusion coefficients are non-negative. Standart et al. [10
Firoozabadi, Abbas
A comparison study of multi-component Lattice Boltzmann models for flow in porous media applications
A comparison study of three different multi-component Lattice Boltzmann models is carried out to explore their capability of describing binary immiscible fluid systems. The Shan-Chen pseudo potential model, the Oxford free energy model and the colour ... Keywords: Binary fluids, Lattice Boltzmann, Multi-component models
Jianhui Yang; Edo S. Boek
Elevated Silica Project at Palisades -- Final Report
Silica concentrations as high as 2-5 ppm in the primary water during startup at some pressurized water reactor (PWR) plants exceed the prevailing industry diagnostic limit of 1 ppm and raise concerns about the possible formation of tenacious silicate deposits on the fuel. To minimize the costs of removing excess silica at fuel outages, EPRI initiated an investigation on the effect of silica on fuel performance. This report documents the final stage of this research, a fuel surveillance project at Palisad...
PWR RCS Elevated Silica - Fuel Surveillance
Many PWR plants have recently experienced silica concentration as high as 2-5 ppm in the primary water at startup. That level exceeds the prevailing industry diagnostic limit of 1 ppm for safeguarding fuel from potential deposition of tenacious silicates. The high silica experience is primarily limited to plants using silica-containing Boroflex storage racks, which tend to decay in the intense radiation environment in the storage pool. Some plants using recycled boric acid have also experienced high star...
Cellular membrane trafficking of mesoporous silica nanoparticles
This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulf some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine the specific organelle that mesoporous silica nanoparticles could approach via the identification of harvested proteins from exocytosis process. Based on the study of endo- and exocytosis behavior of mesoporous silica nanoparticle materials, we can design smarter drug delivery vehicles for cancer therapy that can be effectively controlled. The destination, uptake efficiency and the cellular distribution of mesoporous silica nanoparticle materials can be programmable. As a result, release mechanism and release rate of drug delivery systems can be a well-controlled process. The deep investigation of an endo- and exocytosis study of mesoporous silica nanoparticle materials promotes the development of drug delivery applications.
Fang, I-Ju
Analysis of gas centrifuge cascade for separation of multicomponent isotopes and optimal feed position
Analysis of the concentration distribution in a gas centrifuge cascade for separation of multicomponent isotope mixtures is different from that in a cascade for separation of two-component mixtures. This paper presents the governing equations for a multicomponent isotope separation cascade. Numerically predicted separation factors for the gas centrifuge cascade agree well with the experimental data. A theoretical optimal feed position is derived for a short square cascade for a two-component mixture in a close-separation case. The optimal feed position for a gas centrifuge cascade for separation of multicomponent mixture is discussed.
Chuntong Ying; Hongjiang Wu; Mingsheng Zhou; Yuguang Nie; Guangjun Liu [Tsinghua Univ., Beijing (China)
Multi-component Removal in Flue Gas by Aqua Ammonia
component Removal in Flue Gas by Aqua Ammonia component Removal in Flue Gas by Aqua Ammonia Opportunity The Department of Energy's National Energy Technology Laboratory is seeking licensing partners interested in implementing United States Patent Number 7,255,842 entitled "Multi-component Removal in Flue Gas by Aqua Ammonia." This patent discloses a method for the removal of potential environmental-impacting compounds from flue gas streams. The method oxidizes some or all of the acid precursors such as sulfur dioxide (SO 2 ) and nitric oxides (NO x ) into sulfur trioxide and nitrogen dioxide, respectively. Following this step, the gas stream is then treated with aqua ammonia or ammonium hydroxide to capture the compounds via chemical absorption through acid-base or neutralization reactions where a fertilizer is formed.
Text of The Solubility of Silica in Calcium Ferrite Slags
To successfully use lime flux, the dissolution of silica in calcium-ferrite slags must ... samples were chemically analyzed by standard methods for calcium, silica,�...
Synthesis and properties of chitosan-silica hybrid aerogels
Synthesis and properties of chitosan-silica hybrid aerogels Title Synthesis and properties of chitosan-silica hybrid aerogels Publication Type Journal Article Year of Publication...
Synthesis and properties of Chitosan-silica hybrid aerogels
chitosan-silica composite aerogels can be easily synthesizedphysical properties of these aerogels. These materials may1. Top: Chitosan-silica aerogel (sample 4), Bottom: Same
Ayers, Michael R.; Hunt, Arlon J.
Investigations of silica alcogel aging using coherent light
Investigations of silica alcogel aging using coherent light Title Investigations of silica alcogel aging using coherent light Publication Type Journal Article Year of Publication...
Shepard and Hardy Multiquadric Interpolation Methods for Multicomponent Aerosol�Cloud Parameterization
This paper presents a novel method based on the application of interpolation techniques to the multicomponent aerosol�cloud parameterization for global climate modeling. Quantifying the aerosol indirect effect still remains a difficult task, and ...
Alexandru Rap; Satyajit Ghosh; Michael H. Smith
Soap Manufacturing TechnologyChapter 12 Manufacture of Multicolored and Multicomponent Soaps
Soap Manufacturing Technology Chapter 12 Manufacture of Multicolored and Multicomponent Soaps Surfactants and Detergents eChapters Surfactants - Detergents Press Downloadable pdf of\tChapter 12 Manufacture of Mult
Multicomponent Transport of Contaminants Released into the Environment following the Application of Phosphogypsum.
??The fate of radioactive contaminants released from phosphogypsum, a by-product of the phosphate fertilizer industry, was studied using the multicomponent transport modeling program HP-1. HP-1� (more)
Ebbers, B.
Conservative numerical simulation of multi-component transport in two-dimensional unsteady shallow water flow
An explicit finite volume model to simulate two-dimensional shallow water flow with multi-component transport is presented. The governing system of coupled conservation laws demands numerical techniques to avoid unrealistic values of the transported ... Keywords: ?-? model, 35L65, 65M06, 65M12, 76M12, 76M20, Coupled system, Multi-component transport, Reactive source terms, Shallow flow, Solute constraints, Turbulence, Variable domain, Well-balanced approach
J. Murillo; P. Garc�a-Navarro; J. Burguete
Pressure Drops Due to Silica Scaling
Experience with reinjection returns in many geothermal fields has prompted a move towards injecting waste fluids at some distance from the production field. This means that often, reinjection pipelines cover very long distances. If the waste water in the pipelines is supersaturated with respect to amorphous silica, then the deposition of silica in these pipelines is almost certain. Although the deposit may be of negligible thickness, the inner surface characteristics of the pipe will be different to those of clean mild steel. During a silica scaling experiment. geothermal brine was passed through a series of pipes of different sizes and over a period of three weeks, silica scale formed on the inner surface. The pressure drop along a distance of approximately 5m was measured by a water manometer in all test pipe sections. Significant pressure drop was observed during this time and can be correlated with the increase in the friction factor of the pipe walls due to silica scaling.
Brown, K.L.; Freeston, D.H.; Dimas, Z.O.; Slatter, A.
Sputter deposition for multi-component thin films
Ion beam sputter-induced deposition using a single ion beam and a multicomponent target is capable of reproducibly producing thin films of arbitrary composition, including those which are close to stoichiometry. Using a quartz crystal deposition monitor and a computer controlled, well-focused ion beam, this sputter-deposition approach is capable of producing metal oxide superconductors and semiconductors of the superlattice type such as GaAs-AlGaAs as well as layered metal/oxide/semiconductor/superconductor structures. By programming the dwell time for each target according to the known sputtering yield and desired layer thickness for each material, it is possible to deposit composite films from a well-controlled sub-monolayer up to thicknesses determined only by the available deposition time. In one embodiment, an ion beam is sequentially directed via a set of X-Y electrostatic deflection plates onto three or more different element or compound targets which are constituents of the desired film. In another embodiment, the ion beam is directed through an aperture in the deposition plate and is displaced under computer control to provide a high degree of control over the deposited layer. In yet another embodiment, a single fixed ion beam is directed onto a plurality of sputter targets in a sequential manner where the targets are each moved in alignment with the beam under computer control in forming a multilayer thin film. This controlled sputter-deposition approach may also be used with laser and electron beams.
Krauss, Alan R. (Plainfield, IL); Auciello, Orlando (Cary, NC)
Fladmark. Parallel simulation of multiphase/multicomponent flow models
Summary. The simulation of flow in porous media is a computationally demanding task. Thermodynamical equilibrium calculations and complex, heterogeneous geological structures normally gives a multiphysics/multidomain problem to solve. Thus, efficient solution methods are needed. The research simulator Athena is a 3D, multiphase, multicomponent, porous media flow simulator. A parallel version of the simulator was developed based on a non-overlapping domain decomposition strategy, where the domains are defined a-priori from e.g. geological data. Selected domains are refined with locally matching grids, giving a globally non-matching, unstructured grid. In addition to the space domain, novel algorithms for parallel processing in time based on a predictor-corrector strategy has been successfully implemented. We discuss how the domain decomposition framework can be used to include different physical and numerical models in selected sub-domains. Also we comment on how the two-level solver relates to multiphase upscaling techniques. Adding communication functionality enables the original serial version to run on each sub-domain in parallel. Motivated by the need for larger time steps, an implicit formulation of the mass transport equations has been formulated and implemented in the existing parallel framework. Further, as the Message Passing Interface (MPI) is used for communication, the simulator is highly portable. Through benchmark experiments, we test the new formulation on platforms ranging from commercial super-computers to heterogeneous networks of workstations. 1
Erlend �ian; Magne S. Espedal; I. Garrido; G. E. Fladmark
Silica-coated liposomes for insulin delivery
Liposomes coated with silica were explored as protein delivery vehicles for their enhanced stability and improved encapsulation efficiency. Insulin was encapsulated within the fluidic phosphatidylcholine lipid vesicles by thin film hydration at pH 2.5, ...
Neelam Dwivedi; M. A. Arunagirinathan; Somesh Sharma; Jayesh Bellare
S.S. , "Coherent Expanded Aerogels," J. of Phys. Chern.Production of Silica Aerogel," Physica Scripta 23, Nicolaon,S.J. , "Preparation des aerogels de silice a partir
Hunt, A.J.
Interpreting multicomponent seismic data in the Gulf of Mexico for shallow sedimentary properties: methodology and case history
OTC 15118 Interpreting multicomponent seismic data in the Gulf of Mexico for shallow sedimentary of multicomponent data analysis for the detection of gas hydrate prospects in the northern Gulf of Mexico. Methane and pressure conditions in the region. In many regions of North America, including the southern Gulf of Mexico
Texas at Austin, University of
Chemistry of silica in Cerro Prieto brines
The precipitation of amorphous silica from synthetic geothermal brines which resemble the flashed brine at Cerro Prieto has been studied. It was found that part of the dissolved silica quickly polymerizes to form suspended colloidal silica. The colloidal silica flocculates and settles slowly at unmodified brine pH values near 7.35. Raising the pH of the brine to about 7.8 by adding base and stirring for a few minutes causes rapid and complete flocculation and settling. These results have been confirmed in the field using actual Cerro Prieto brine. Both in the laboratory and in the field quaternary amines were found to be effective with some brine compositions but not with others. Polyacrylamides do not work at all. These results suggest the following simple preinjection brine treatment process: age the brine for 10 to 20 minutes in a covered holding tank, add 20 to 30 ppM lime (CaO), stir for 5 minutes, and separate the flocculated silica from the brine using a conventional clarifier. The brine coming out of such a process will be almost completely free of suspended solids. The pilot plant tests needed to reduce this conceptual process to practice are discussed. The rate of deposition of silica scale from synthetic brines was separately studied. It was found that a modest decrease in pH could significantly reduce the scaling rate at a reasonable cost. The equilibrium chemistry of Cerro Prieto brine was studied theoretically. These calculations indicate that increasing the brine pH to remove silica might cause some precipitation of carbonate minerals, but also that this problem could easily be eliminated at a reasonable cost if it did arise.
Weres, O.; Tsao, L.; Iglesias, E.
Chemistry of Silica in Cerro Prieto Brines
The precipitation of amorphous silica from synthetic geothermal, brines which resemble the flashed brine at Cerro Prieto has been studied. It was found that part of the dissolved silica quickly polymerizes to form suspended colloidal silica. The colloidal silica flocculates and settles slowly at unmodified brine pH values near 7.35. Raising the pH of the brine to about 7.8 by adding base and stirring for a few minutes causes rapid and complete flocculation and settling. these results have been confirmed in the field using actual Cerro Prieto brine. Both in the laboratory and in the field quaternary amines were found to be effective with some brine compositions but not with others. Polyacrylamides do not work at all. These results suggest the following simple preinjection brine treatment process: age the brine for 10-20 minutes in a covered holding tank, add 20-30 ppm lime (CaO), stir for 5 minutes, and separate the flocculated silica from the brine using a conventional clarifier. The brine coming out of such a process will be almost completely free of suspended solids. The pilot plant tests needed to reduce this conceptual process to practice are discussed. The rate of deposition of silica scale from synthetic brines was separately studied. It was found that a modest decrease in pH could significantly reduce the scaling rate at a reasonable cost. The equilibrium chemistry of Cerro Prieto brine was studied theoretically. These calculations indicate that increasing the brine pH to remove silica might cause some precipitation of carbonate minerals, but also that this problem could easily be eliminated at a reasonable cost if it did arise.
Weres, Oleh; Iglesias, Eduardo; Tsao, Leon
Expanding Conventional Seismic Stratigrphy into the Multicomponent Seismic Domain
Multicomponent seismic data are composed of three independent vector-based seismic wave modes. These wave modes are, compressional mode (P), and shear modes SV and SH. The three modes are generated using three orthogonal source-displacement vectors and then recorded using three orthogonal vector sensors. The components travel through the earth at differing velocities and directions. The velocities of SH and SV as they travel through the subsurface differ by only a few percent, but the velocities of SV and SH (Vs) are appreciably lower than the P-wave velocity (Vp). The velocity ratio Vp/Vs varies by an order of magnitude in the earth from a value of 15 to 1.5 depending on the degree of sedimentary lithification. The data used in this study were acquired by nine-component (9C) vertical seismic profile (VSP), using three orthogonal vector sources. The 9C vertical seismic profile is capable of generating P-wave mode and the fundamental S-wave mode (SH-SH and SV-SV) directly at the source station and permits the basic components of elastic wavefield (P, SH-SH and SV-SV) to be separated from one another for the purposes of imaging. Analysis and interpretations of data from the study area show that incident full-elastic seismic wavefield is capable of reflecting four different wave modes, P, SH , SV and C which can be utilized to fully understand the architecture and heterogeneities of geologic sequences. The conventional seismic stratigraphy utilizes only reflected P-wave modes. The notation SH mode is the same as SH-SH; SV mode means SV-SV and C mode which is a converted shear wave is a special SV mode and is the same as P-SV. These four wave modes image unique geologic stratigraphy and facies and at the same time reflect independent stratal surfaces because of the unique orientation of their particle-displacement vectors. As a result of the distinct orientation of individual mode's particle-displacement vector, one mode may react to a critical subsurface sequence more than the other. It was also observed that P-wave and S-wave do not always reflect from the same stratal boundaries. The utilization of full-elastic seismic wavefield needs to be maximized in oil and gas explorations in order to optimize the search for hydrocarbons.
Innocent Aluka
High resolution patterning of silica aerogels
Three-dimensional metallic structures are fabricated with high spatial resolution in silica aerogels. In our method, silica hydrogels are prepared with a standard base-catalyzed route, and exchanged with an aqueous solution typically containing Ag{sup +} ions (1 M) and 2-propanol (0.2 M). The metal ions are reduced photolytically with a table-top ultraviolet lamp, or radiolytically, with a focused X-ray beam. We fabricated dots and lines as small as 30 x 70 {micro}m, protruding for several mm into the bulk of the materials. The hydrogels are eventually supercritically dried to yield aerogels, without any measurable change in the shape and spatial resolution of the lithographed structures. Transmission electron microscopy shows that illuminated regions are composed by Ag clusters with a size of several {micro}m, separated by thin layers of silica.
Bertino, M.F.; Hund, J.F.; Sosa, J.; Zhang, G.; Sotiriou-Leventis, C.; Leventis, N.; Tokuhiro, A.T.; Terry, J. (UMR-MUST); (IIT)
Safety Bulletin 2007-08 Silica Dust Exposure
minerals. Potential work exposure to airborne crystalline silica includes abrasive blasting, sandblasting, rock cutting, chipping, drilling, grinding, jack hammering, concrete...
Multicomponent reactive transport modeling at the Ratones uranium mine, Cceres (Spain)
management. The Ratones uranium mine was abandoned and flooded in 1974. Due to its reducing undergroundMulticomponent reactive transport modeling at the Ratones uranium mine, Cáceres (Spain) Modelación/06/05 / Accepted: 02/10/05 Abstract Flooding of abandoned mines may have a major impact in groundwater quality
Politècnica de Catalunya, Universitat
Driving force and composition for multicomponent gas hydrate nucleation from supersaturated aqueous solutions
Driving force and composition for multicomponent gas hydrate nucleation from supersaturated aqueous.1063/1.1817999 I. INTRODUCTION Gas hydrate crystallization from mixtures of natural gases and water is of interest for both the prevention of hy- drate formation in natural gas production and for promotion of hydration
Measurement of muonium emission from silica aerogel
Emission of muonium ($\\mu^{+}e^{-}$) atoms from silica aerogel into vacuum was observed. Characteristics of muonium emission were established from silica aerogel samples with densities in the range from 29 mg cm$^{-3}$ to 178 mg cm$^{-3}$. Spectra of muonium decay times correlated with distances from the aerogel surfaces, which are sensitive to the speed distributions, follow general features expected from a diffusion process, while small deviations from a simple room-temperature thermal diffusion model are identified. The parameters of the diffusion process are deduced from the observed yields.
Bakule, P; Contreras, D; Esashi, M; Fujiwara, Y; Fukao, Y; Hirota, S; Iinuma, H; Ishida, K; Iwasaki, M; Kakurai, T; Kanda, S; Kawai, H; Kawamura, N; Marshall, G M; Masuda, H; Matsuda, Y; Mibe, T; Miyake, Y; Okada, S; Olchanski, K; Olin, A; Onishi, H; Saito, N; Shimomura, K; Strasser, P; Tabata, M; Tomono, D; Ueno, K; Yokoyama, K; Yoshida, S
P. Bakule; G. A. Beer; D. Contreras; M. Esashi; Y. Fujiwara; Y. Fukao; S. Hirota; H. Iinuma; K. Ishida; M. Iwasaki; T. Kakurai; S. Kanda; H. Kawai; N. Kawamura; G. M. Marshall; H. Masuda; Y. Matsuda; T. Mibe; Y. Miyake; S. Okada; K. Olchanski; A. Olin; H. Onishi; N. Saito; K. Shimomura; P. Strasser; M. Tabata; D. Tomono; K. Ueno; K. Yokoyama; S. Yoshida
A threshold Cherenkov detector for K separation using silica aerogel
A threshold Cherenkov detector for Kþ =pþ separation using silica aerogel R. Siudak a,b , A August 2008 Keywords: Threshold Cherenkov detector Silica aerogel Reaction pp ! Kþ ðLp�? Kþ =pþ separation in the focal plane of a magnetic spectrograph. Silica aerogel with refractive index of n ¼ 1:05 is applied
Magiera, Andrzej
Characterization of vanadium/silica and copper/silica aerogel catalysts
Vanadium/silica and copper/silica aerogels have been prepared using the sol-gel method followed by CO{sub 2} exchange and supercritical extraction. Structural properties of samples supercritically dried, oxidized and used in reactions studies conducted with a feed representing the average composition of automobile exhaust from a lean burn engine were investigated using laser Raman spectroscopy and temperature-programmed reduction. No evidence of crystalline V{sub 2}O{sub 5} was found for the vanadium/silica aerogel, freshly extracted, oxidized or following exposure to reaction conditions using these techniques. However, results obtained for the copper/silica sample indicate that changes in the structure of the copper species had occurred as the sample was oxidized and exposed to reaction conditions.
Owens, L.; Tillotson, T.M.; Hair, L.M. [Lawrence Livermore National Lab., CA (United States). Chemistry and Materials Science Dept.
Molecular sieving silica membrane fabrication process
A process for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the at least one organic constituent of the hybrid organic-inorganic polymer, forming a porous film.
Raman, Narayan K. (400 Maple St. SE., Apartment 112, Albuquerque, NM 87106); Brinker, Charles Jeffrey (14 Eagle Nest Dr., NE., Albuquerque, NM 87122)
Raman, Narayan K. (Monroeville, PA); Brinker, Charles Jeffrey (Albuquerque, NM)
Significant Silica Solubility in Geothermal Steam
Although it is widely believed that silica solubility in low pressure (5 to 10 bar) geothermal steam is negligible, when one takes into account steam flows exceeding 10 million tonnes a year--at Wairakei, for instance--it is found that the amount transmitted in the vapor has the potential to give significant deposits on turbine nozzles and blades. A 150 MWe power station, when based on flows from a hot water reservoir at (a) 250 C or (b) 315 C, and with separator pressures of 6 bar, is found to carry about 100 and 200 kg/year respectively in the steam phase. In the case of a similar sized station exploiting a dry steam reservoir such as The Geysers, equivalent silica flows are obtained, dissolved in steam and carried as dust--the latter as solid particles precipitating from the vapor en route from source to turbine, and not preexisting in the formations as is commonly considered. Choking or coating of subterranean rock near such dry steam wells due to exsolving silica, may be the principal cause of declining steam discharge under production. Silica from completely dry or superheated steam can also seal the cap and sides of steam reservoirs when expanding below the criticus temperature (236 C) in a way previously thought possible only by hot water or wet steam.
James, Russell
A process is described for producing a molecular sieve silica membrane comprising depositing a hybrid organic-inorganic polymer comprising at least one organic constituent and at least one inorganic constituent on a porous substrate material and removing at least a portion of the at least one organic constituent of the hybrid organic-inorganic polymer, forming a porous film. 11 figs.
Raman, N.K.; Brinker, C.J.
Moisture transport in silica gel particle beds
A theoretical and experimental study of the performance of silica gel packed particle beds is described. A bench-scale test rig was used to obtain data for parameter values pertinent to solar air-conditioning applications. Both adsorption and desorption experiments were performed for Regular Density (RD) silica gel for a wide range of particle size. Adsorption data were also obtained for Intermediate Density (ID) gel. A model of heat and mass transfer in the bed was developed with special attention paid to the modeling of solid side resistance. For this latter purpose an extensive review of the available literature on moisture adsorption and moisture transport in silica gel was made. Both Knudsen and surface diffusion are found to be important mechanisms of moisture transport in Intermediate Density gels while surface diffusion is dominant in Regular Density gels. A general equation for moisture transport in a spherical silica gel particle was developed and was incorporated into the model equations governing heat and mass transfer between the gel particles and air flowing through a packed particle bed. A computer code DESICCANT was written to solve the coupled set of partial differential equations using a finite difference numerical method. The agreement between theory and experiment for adsorption on RD gel is satisfactory, and is somewhat better for the outlet water vapor concentration than for the outlet air temperature. The agreement for desorption from RD gel and adsorption to ID gel is satisfactory, but not as good as for adsorption on RD gel.
Pesaran, A.A.
Conversion of geothermal waste to commercial products including silica
A process for the treatment of geothermal residue includes contacting the pigmented amorphous silica-containing component with a depigmenting reagent one or more times to depigment the silica and produce a mixture containing depigmented amorphous silica and depigmenting reagent containing pigment material; separating the depigmented amorphous silica and from the depigmenting reagent to yield depigmented amorphous silica. Before or after the depigmenting contacting, the geothermal residue or depigmented silica can be treated with a metal solubilizing agent to produce another mixture containing pigmented or unpigmented amorphous silica-containing component and a solubilized metal-containing component; separating these components from each other to produce an amorphous silica product substantially devoid of metals and at least partially devoid of pigment. The amorphous silica product can be neutralized and thereafter dried at a temperature from about 25.degree. C. to 300.degree. C. The morphology of the silica product can be varied through the process conditions including sequence contacting steps, pH of depigmenting reagent, neutralization and drying conditions to tailor the amorphous silica for commercial use in products including filler for paint, paper, rubber and polymers, and chromatographic material.
Premuzic, Eugene T. (East Moriches, NY); Lin, Mow S. (Rocky Point, NY)
Simulation of Cloud Microphysical and Chemical Processes Using a Multicomponent Framework. Part I: Description of the Microphysical Model
A detailed microphysical and chemical cloud model has been developed to investigate the redistribution of atmospheric trace substances through cloud processes. A multicomponent categorization scheme is used to group cloud particles into different ...
Jen-Ping Chen; Dennis Lamb
Three-dimensional model for multi-component reactive transport with variable density groundwater flow
PHWAT is a new model that couples a geochemical reaction model (PHREEQC-2) with a density-dependent groundwater flow and solute transport model (SEAWAT) using the split-operator approach. PHWAT was developed to simulate multi-component reactive transport ... Keywords: Cation exchange, Coastal groundwater flow and chemical transport/reaction, Density-dependent flow, MODFLOW, MT3DMS, PHREEQC-2, PHWAT, SEAWAT, Seawater intrusion, Snow-plough effect
X. Mao; H. Prommer; D. A. Barry; C. D. Langevin; B. Panteleit; L. Li
Carbon nanomaterials in silica aerogel matrices
Silica aerogels are ultra low-density, high surface area materials that are extremely good thermal insulators and have numerous technical applications. However, their mechanical properties are not ideal, as they are brittle and prone to shattering. Conversely, single-walled carbon nanotubes (SWCNTs) and graphene-based materials, such as graphene oxide, have extremely high tensile strength and possess novel electronic properties. By introducing SWCNTs or graphene-based materials into aerogel matrices, it is possible to produce composites with the desirable properties of both constituents. We have successfully dispersed SWCNTs and graphene-based materials into silica gels. Subsequent supercritical drying results in monolithic low-density composites having improved mechanical properties. These nanocomposite aerogels have great potential for use in a wide range of applications.
Hamilton, Christopher E [Los Alamos National Laboratory; Chavez, Manuel E [Los Alamos National Laboratory; Duque, Juan G [Los Alamos National Laboratory; Gupta, Gautam [Los Alamos National Laboratory; Doorn, Stephen K [Los Alamos National Laboratory; Dattelbaum, Andrew M [Los Alamos National Laboratory; Obrey, Kimberly A D [Los Alamos National Laboratory
(129)Xe NMR of Mesoporous Silicas
The porosities of three mesoporous silica materials were characterized with {sup 129}Xe NMR spectroscopy. The materials were synthesized by a sol-gel process with r = 0, 25, and 70% methanol by weight in an aqueous cetyltrimethylammonium bromide solution. Temperature dependent chemical shifts and spin lattice relaxation times reveal that xenon does not penetrate the pores of the largely disordered (r= 70%) silica. For both r = 0 and 25%, temperature dependent resonances corresponding to physisorbed xenon were observed. An additional resonance for the r = 25% sample was attributed to xenon between the disordered cylindrical pores. 2D NMR exchange experiments corroborate the spin lattice relaxation data which show that xenon is in rapid exchange between the adsorbed and the gas phase.
Anderson, M.T.; Asink, R.A.; Kneller, J.M.; Pietrass, T.
Interaction of silica nano-particles with a flat silica surface through neutron reflectometry
Neutron reflectometry (NR) was employed to study the interaction of nanosized silica particles with a flat silica surface in aqueous solutions. Unlike other experimental tools that are used to study surface interactions, NR can provide information on the particle density profile in the solution near the interface. Two types of silica particles (25 and 100 nm) were suspended in aqueous solutions of varying ionic strength. Theoretical calculations of the surface interaction potential between a particle and a flat silica surface using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory were compared to the experimental data. The theory predicts that the potential energy is highly dependent on the ionic strength. In high ionic strength solutions, NR reveals a high concentration of particles near the flat silica surface. Under the same conditions, theoretical calculations show an attractive force between a particle and a flat surface. For low ionic strength solutions, the particle concentration near the surface obtained from NR is the same as the bulk concentration, while depletion of particles near the surface is expected because of the repulsion predicted by the DLVO theory.
Chung, Eunhyea [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Halbert, Candice E [ORNL; Ankner, John Francis [ORNL; Wang, Wei [ORNL; Tsouris, Costas [ORNL
Recent progress in silica aerogel Cherenkov radiator
In this paper, we present recent progress in the development of hydrophobic silica aerogel as a Cherenkov radiator. In addition to the conventional method, the recently developed pin-drying method for producing high-refractive-index aerogels with high transparency was studied in detail. Optical qualities and large tile handling for crack-free aerogels were investigated. Sufficient photons were detected from high-performance aerogels in a beam test.
Tabata, Makoto; Kawai, Hideyuki; Kubo, Masato; Sato, Takeshi
Analytic Structure of the SCFT Energy Functional of Multicomponent Block Copolymers
This paper concerns the analytic structure of the self-consistent field theory (SCFT) energy functional of multicomponent block copolymer systems which contain more than two chemically distinct blocks. The SCFT has enjoyed considered success and wide usage in investigation of the complex phase behavior of block copolymers. It is well-known that the physical solutions of the SCFT equations are saddle points, however, the analytic structure of the SCFT energy functional has received little attention over the years. A recent work by Fredrickson and collaborators [see the monograph by Fredrickson, The Equilibrium Theory of Inhomogeneous Polymers, (2006), pp. 203-209] has analysed the mathematical structure of the field energy functional for polymeric systems, and clarified the index-1 saddle point nature of the problem produced by the incompressibility constraint. In this paper, our goals are to draw further attention to multicomponent block copolymers utilizing the Hubbard-Stratonovich transformation used by Fredrickson and co-workers. We first show that the saddle point character of the SCFT energy functional of multicomponent block copolymer systems may be high index, not only produced by the incompressibility constraint, but also by the Flory-Huggins interaction parameters. Our analysis will be beneficial to many theoretical studies, such as the nucleation theory of ordered phases, the mesoscopic dynamics. As an application, we then utilize the discovery to develop the gradient-based iterative schemes to solve the SCFT equations, and illustrate its performance through several numerical experiments taking ABC star triblock copolymers as an example.
Kai Jiang; Weiquan Xu; Pingwen Zhang
A combustion model for IC engine combustion simulations with multi-component fuels
Reduced chemical kinetic mechanisms for the oxidation of representative surrogate components of a typical multi-component automotive fuel have been developed and applied to model internal combustion engines. Starting from an existing reduced mechanism for primary reference fuel (PRF) oxidation, further improvement was made by including additional reactions and by optimizing reaction rate constants of selected reactions. Using a similar approach to that used to develop the reduced PRF mechanism, reduced mechanisms for the oxidation of n-tetradecane, toluene, cyclohexane, dimethyl ether (DME), ethanol, and methyl butanoate (MB) were built and combined with the PRF mechanism to form a multi-surrogate fuel chemistry (MultiChem) mechanism. The final version of the MultiChem mechanism consists of 113 species and 487 reactions. Validation of the present MultiChem mechanism was performed with ignition delay time measurements from shock tube tests and predictions by comprehensive mechanisms available in the literature. A combustion model was developed to simulate engine combustion with multi-component fuels using the present MultiChem mechanism, and the model was applied to simulate HCCI and DI engine combustion. The results show that the present multi-component combustion model gives reliable performance for combustion predictions, as well as computational efficiency improvements through the use of reduced mechanism for multi-dimensional CFD simulations. (author)
Ra, Youngchul; Reitz, Rolf D. [Engine Research Center, University of Wisconsin-Madison (United States)
Modelin combustion of multicomponent fuel droplets: formulation and application to transportation fuels
The quasi-steady, spherically symmetric combustion of multicomponent isolated fuel droplets has been modeled using modified Shvab-Zeldovich variable mechanism. Newly developed modified Shvab-Zeldovich equations have been used to describe the gas phase reactions. Vapor-liquid equilibrium model has been applied to describe the phase change at the droplet surface. Constant gas phase specific heats are assumed. The liquid phase is assumed to be of uniform composition and temperature. Radiative heat transfer between the droplet and surroundings is neglected. The results of evaporation of gasoline with discrete composition of hydrocarbons have been presented. The evaporation rates seem to follow the pattern of volatility differentials. The evaporation rate constant was obtained as 0.344mm2/sec which compared well with the unsteady results of Reitz et al. The total evaporation time of the droplet at an ambience of 1000K was estimated to be around 0.63 seconds. Next, the results of evaporation of representative diesel fuels have been compared with previously reported experimental data. The previous experiments showed sufficient liquid phase diffusional resistance in the droplet. Numerical results are consistent with the qualitative behavior of the experiments. The quantitative deviation during the vaporization process can be attributed to the diffusion time inside the droplet which is unaccounted for in the model. Transient evaporation results have also been presented for the representative diesel droplets. The droplet temperature profile indicates that the droplet temperature does not reach an instantaneous steady state as in the case of single-component evaporation. To perform similar combustion calculations for multicomponent fuel droplets, no simple model existed prior to this work. Accordingly, a new simplified approximate mechanism for multicomponent combustion of fuel droplets has been developed and validated against several independent data sets. The new mechanism is simple enough to be used for computational studies of multicomponent droplets. The new modified Shvab-Zeldovich mechanism for multicomponent droplet combustion has been used to model the combustion characteristics of a binary alcohol-alkane droplet and validated against experimental data. Burn rate for the binary droplet of octanol-undecane was estimated to be 1.17mm2/sec in good concurrence with the experimental value of 0.952mm2/sec obtained by Law and Law. The model has then been used to evaluate the combustion characteristics of diesel fuels assuming only gas phase reactions. Flame sheet approximation has been invoked in the formulation of the model.
Vittilapuram Subramanian, Kannan
Mesoporous Silica-Supported Rhodium Nanocatalysts for Selective...
Mesoporous Silica-Supported Rhodium Nanocatalysts for Selective Production of Ethanol From Syngas and Conversion of Ethanol to Hydrogen Description Coal will likely play a major...
Feasibility of using silica aerogel as insulation for buildings.
?? For recent years, silica aerogel has attracted great attention and been extensively used in different technical fields owning to its remarkable properties in optics,� (more)
Huang, Lang
Heat Transfer through Materials: Application to Silica Aerogels...
Heat Transfer through Materials: Application to Silica Aerogels and Building Envelopes Speaker(s): Brangre Lartigue Date: December 19, 2005 - 12:00pm Location: Bldg. 90 After...
Thermal Conductivity of Cubic and Hexagonal Mesoporous Silica Thin Films
K.L. Fang, �Anisotropic thermal conductivity of nanoporousmesoporous silica as a thermal isolation layer�, Ceramicsand V. Wittwer, �Some thermal and optical properties of a
Coquil, Thomas; Richman, Eric K.; Hutchinson, Neal J.; Tolbert, S H; Pilon, Laurent
Dynamic performance characterization of bound, porous silica gel desiccant
Drying of air with silica gel is a well established procedure. However, for the specific use of silica gel in a novel desiccant air conditioning system, which continually cools the silica gel and utilizes solar energy for silica gel regeneration, conventional packed bed devices are not suitable. For this system to operate effectively the silica gel must not rise in its temperature or its capacity will be greatly diminished. Dynamic dehumidificatuion performance was investigted for a silica gel desiccant fabricated in bound, porous paper-like sheets. Sheets of various thickness (0.7 to 3 mm) were fabricated and tested under several dynamic flow conditions in a flat rectangular channel apparatus. During each experiment conditions of inlet moisture, air flowrate, and sheet temperature were maintained constant. Comparisons were also made with conventional silica gel pellets and with other forms of bound silica gel. The sheets show superior utilization of silica gel in short times (30 minutes or less). Tests were also made to examine the sheet structure in order to explore the effect of temperature on the porous structure, and to obtain pore size distributions.
Onischak, M.; Gidaspow, D.; Perkari, S.; Sasaki, T.
Dual-Layer Asymmetric Microporous Silica Membranes
We report a novel sol-gel dip-coating process to form dual-layer microporous silica membranes with improved membrane performance and reproducibility. First, we deposit a surfactant-templated silica (STS) intermediate layer on top of a commercial {gamma}-alumina support both to improve its ''surface finish'' and to prevent a subsequently deposited microporous overlayer from penetrating into the support. Second, membranes are processed under clean room conditions to avoid dust contamination and, third, membranes are vacuum-calcined to promote further pore shrinkage and impart surface hydrophobicity. The resulting asymmetric membrane exhibits a gradual change in pore diameter from 50{angstrom} ({gamma}-alumina support layer) to 10-12{angstrom} (STS intermediate layer), and then to 3-4{angstrom} (30nm thick, ultramicroporous silica top-layer). Compared to a single-layer process using only the microporous overlayer, the dual-layer process improves both flux and selectivity. For the industrially important problem of natural gas purification, the combined CO{sub 2} flux [(3{approx} 0.5) x 10{sup {minus}4} cm{sup 3}(STP)/(s{center_dot}cm{sup 2}{center_dot}cm-Hg)] and CO{sub 2}/CH{sub 4} separation factors [200{approx}600] are superior to all previously reported values for separation of a 50/50 (v/v) CO{sub 2}/CH{sub 4} gas mixture. In addition, the membrane selectively separated hydrogen from a simulated reformate from partial oxidation of methanol as evidenced by a high concentration of hydrogen recovery.
Fibrous composites comprising carbon nanotubes and silica
Fibrous composite comprising a plurality of carbon nanotubes; and a silica-containing moiety having one of the structures: (SiO).sub.3Si--(CH.sub.2).sub.n--NR.sub.1R.sub.2) or (SiO).sub.3Si--(CH.sub.2).sub.n--NCO; where n is from 1 to 6, and R.sub.1 and R.sub.2 are each independently H, CH.sub.3, or C.sub.2H.sub.5.
Peng, Huisheng (Shanghai, CN); Zhu, Yuntian Theodore (Cary, NC); Peterson, Dean E. (Los Alamos, NM); Jia, Quanxi (Los Alamos, NM)
Hydrophobic silica aerogel production at KEK
We present herein a characterization of a standard method used at the High Energy Accelerator Research Organization (KEK) to produce hydrophobic silica aerogels and expand this method to obtain a wide range of refractive index (n = 1.006-1.14). We describe in detail the entire production process and explain the methods used to measure the characteristic parameters of aerogels, namely the refractive index, transmittance, and density. We use a small-angle X-ray scattering (SAXS) technique to relate the transparency to the fine structure of aerogels.
Tabata, Makoto; Kawai, Hideyuki; Sumiyoshi, Takayuki; Yokogawa, Hiroshi
Makoto Tabata; Ichiro Adachi; Hideyuki Kawai; Takayuki Sumiyoshi; Hiroshi Yokogawa
Silica scaling in simulated geothermal brines
A 6.3 1/sec (100 GPM) titanium corrosion test loop was modified to provide a dynamic facility for studying the formation of silica deposits, their properties and fates, as a function of brine composition, temperature, and flow conditions. Scale formation was studied in a segmented heat exchanger operating under realistic conditions; the segmented design permitted examination of scale formations in five temperature regimes. The program was terminated after minimal exploratory operation because of reduced sponsor perceptions of the need for concern with scaling problems. The runs which were completed dealt cursorily with brine concentration and pH effects. Results are presented.
Bohlmann, E.G.; Shor, A.J.; Berlinski, P.; Mesmer, R.E.
Community Geothermal Technology Program: Silica bronze project. Final report
Objective was to incorporate waste silica from the HGP-A geothermal well in Pohoiki with other refractory materials for investment casting of bronze sculpture. The best composition for casting is about 50% silica, 25% red cinders, and 25% brick dust; remaining ingredient is a binder, such as plaster and water.
Bianchini, H.
Silica-Coated Titania and Zirconia Colloids for Subsurface Transport
, Environmental Engineering Program, Yale University, New Haven, Connecticut 06520-8286, and Department of Civil transport experiments. Electrophoretic mobility measurements showed that coating with silica imparted electrophoretic mobility and size (by dynamic light scattering) over a 90-day period showed that the silica
Elimelech, Menachem
Functionalization of silica nanoparticles for polypropylene nanocomposite applications
Synthetic silica nanospheres of 20 and 100nm diameter were produced via the sol-gel method to be used as filler in polypropylene (PP) composites. Modification of the silica surface was further performed by reaction with organic chlorosilanes in order ...
Diego Bracho, Vivianne N. Dougnac, Humberto Palza, Ra�l Quijada
Simulations Reveal That Earth's Silica Is Predominantly Superficial - NERSC
Reveal Reveal Earth's Silica Is Predominantly Superficial Simulations Reveal Earth's Silica Is Predominantly Superficial May 24, 2010 Silica is one of the most common minerals on Earth. Not only does it make up two-thirds of our planet's crust, it is also used to create a variety of materials from glass to ceramics, computer chips and fiber optic cables. Yet new quantum mechanics results generated by a team of physicists from Ohio State University (OSU) show that this mineral only populates our planet superficially-in other words, silica is relatively uncommon deep within the Earth. Cross-section of the Earth Using several of the largest supercomputers in the nation, including the National Energy Research Scientific Computing Center's (NERSC) Cray XT4 "Franklin" system, the team simulated the behavior of silica in
The Liquid-Gas Phase Transitions in a Multicomponent Nuclear System with Coulomb and Surface Effects
The liquid-gas phase transition is studied in a multi-component nuclear system using a local Skyrme interaction with Coulomb and surface effects. Some features are qualitatively the same as the results of Muller and Serot which uses relativistic mean field without Coulomb and surface effects. Surface tension brings the coexistance binodal surface to lower pressure. The Coulomb interaction makes the binodal surface smaller and cause another pair of binodal points at low pressure and large proton fraction with less protons in liquid phase and more protons in gas phase.
S. J. Lee; A. Z. Mekjian
A Symmetric Free Energy Based Multi-Component Lattice Boltzmann Method
We present a lattice Boltzmann algorithm based on an underlying free energy that allows the simulation of the dynamics of a multicomponent system with an arbitrary number of components. The thermodynamic properties, such as the chemical potential of each component and the pressure of the overall system, are incorporated in the model. We derived a symmetrical convection diffusion equation for each component as well as the Navier Stokes equation and continuity equation for the overall system. The algorithm was verified through simulations of binary and ternary systems. The equilibrium concentrations of components of binary and ternary systems simulated with our algorithm agree well with theoretical expectations.
Qun Li; A. J. Wagner
Multi-Component NLS Models on Symmetric Spaces: Spectral Properties versus Representations Theory
The algebraic structure and the spectral properties of a special class of multi-component NLS equations, related to the symmetric spaces of {\\bf BD.I}-type are analyzed. The focus of the study is on the spectral theory of the relevant Lax operators for different fundamental representations of the underlying simple Lie algebra $\\mathfrak{g}$. Special attention is paid to the structure of the dressing factors in spinor representation of the orthogonal simple Lie algebras of ${\\bf B}_r\\simeq so(2r+1,{\\mathbb C})$ type.
Vladimir S. Gerdjikov; Georgi G. Grahovski
Gerdjikov, Vladimir S; 10.3842/SIGMA.2010.044
Water dynamics in controlled pore silica glasses
Water in porous silica glass is a suitable system for investigating the effect of confinement on translational diffusion. These systems are important because of their relevance in catalytic and separation processes. Two factors are to be considered in the case of confined water: (1) the effects of hydrophilic and hydrophobic surfaces on interfacial water and (2) how the dynamics of the hydrogen bond network changes due to the volume of confinement. Here quasi-elastic neutron scattering experiments at room temperature on water filled controlled pore glasses with radius of 15, 24 and 32 {angstrom}, are presented and analyzed using the random-jump diffusion model. Both the average residence time and the mean jump distance increase with decreasing pore radius.
Bordallo, H. N.; Herwig, K. W.; Dozier, W. D.; Drake, F.
Ambient-pressure silica aerogel films
Very highly porous (aerogel) silica films with refractive index in the range 1.006--1.05 (equivalent porosity 98.5--88%) were prepared by an ambient-pressure process. It was shown earlier using in situ ellipsometric imaging that the high porosity of these films was mainly attributable to the dilation or `springback` of the film during the final stage of drying. This finding was irrefutably reconfirmed by visually observing a `springback` of >500% using environmental scanning electron microscopy (ESEM). Ellipsometry and ESEM also established the near cent per cent reversibility of aerogel film deformation during solvent intake and drying. Film thickness profile measurements (near the drying line) for the aerogel, xerogel and pure solvent cases are presented from imaging ellipsometry. The thickness of these films (crack-free) were controlled in the range 0.1-3.5 {mu}m independent of refractive index.
Prakash, S.S. [New Mexico Univ., Albuquerque, NM (United States); Brinker, C.J. [New Mexico Univ., Albuquerque, NM (United States)]|[Sandia National Labs., Albuquerque, NM (United States); Hurd, A.J. [Sandia National Labs., Albuquerque, NM (United States)
Laser Damage Precursors in Fused Silica
There is a longstanding, and largely unexplained, correlation between the laser damage susceptibility of optical components and both the surface quality of the optics, and the presence of near surface fractures in an optic. In the present work, a combination of acid leaching, acid etching, and confocal time resolved photoluminescence (CTP) microscopy has been used to study laser damage initiation at indentation sites. The combination of localized polishing and variations in indentation loads allows one to isolate and characterize the laser damage susceptibility of densified, plastically flowed and fractured fused silica. The present results suggest that: (1) laser damage initiation and growth are strongly correlated with fracture surfaces, while densified and plastically flowed material is relatively benign, and (2) fracture events result in the formation of an electronically defective rich surface layer which promotes energy transfer from the optical beam to the glass matrix.
Miller, P; Suratwala, T; Bude, J; Laurence, T A; Shen, N; Steele, W A; Feit, M; Menapace, J; Wong, L
Final report on LDRD project: A phenomenological model for multicomponent transport with simultaneous electrochemical reactions in concentrated solutions
A phenomenological model was developed for multicomponent transport of charged species with simultaneous electrochemical reactions in concentrated solutions, and was applied to model processes in a thermal battery cell. A new general framework was formulated and implemented in GOMA (a multidimensional, multiphysics, finite-element computer code developed and being enhanced at Sandia) for modeling multidimensional, multicomponent transport of neutral and charged species in concentrated solutions. The new framework utilizes the Stefan-Maxwell equations that describe multicomponent diffusion of interacting species using composition-insensitive binary diffusion coefficients. The new GOMA capability for modeling multicomponent transport of neutral species was verified and validated using the model problem of ternary gaseous diffusion in a Stefan tube. The new GOMA-based thermal battery computer model was verified using an idealized battery cell in which concentration gradients are absent; the full model was verified by comparing with that of Bernardi and Newman (1987) and validated using limited thermal battery discharge-performance data from the open literature (Dunning 1981) and from Sandia (Guidotti 1996). Moreover, a new Liquid Chemkin Software Package was developed, which allows the user to handle manly aspects of liquid-phase kinetics, thermodynamics, and transport (particularly in terms of computing properties). Lastly, a Lattice-Boltzmann-based capability was developed for modeling pore- or micro-scale phenomena involving convection, diffusion, and simplified chemistry; this capability was demonstrated by modeling phenomena in the cathode region of a thermal battery cell.
Synthesis of Monolithic Iron Incorporated Silica Aerogels by Ambient ...
With the Fe to Si molar ratio not exceeding 0.10, the bulk density of iron incorporated silica aerogels increased to 0.55g/cm3, while the porosity reduced to 76%�...
Mesoporous-silica films, fibers, and powders by evaporation
This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).
Bruinsma, Paul J. (Kennewick, WA); Baskaran, Suresh (Kennewick, WA); Bontha, Jagannadha R. (Richland, WA); Liu, Jun (West Richland, WA)
Silica Extraction at the Mammoth Lakes Geothermal Site
The purpose of this project is to develop a cost-effective method to extract marketable silica (SiO{sub 2}) from fluids at the Mammoth Lakes, California geothermal power plant. Marketable silica provides an additional revenue source for the geothermal power industry and therefore lowers the costs of geothermal power production. The use of this type of ''solution mining'' to extract resources from geothermal fluids eliminates the need for acquiring these resources through energy intensive and environmentally damaging mining technologies. We have demonstrated that both precipitated and colloidal silica can be produced from the geothermal fluids at Mammoth Lakes by first concentrating the silica to over 600 ppm using reverse osmosis (RO). The RO permeate can be used in evaporative cooling at the plant; the RO concentrate is used for silica and potentially other (Li, Cs, Rb) resource extraction. Preliminary results suggest that silica recovery at Mammoth Lakes could reduce the cost of geothermal electricity production by 1.0 cents/kWh.
Bourcier, W; Ralph, W; Johnson, M; Bruton, C; Gutierrez, P
Correlation between surface chemistry and ion energy dependence of the etch yield in multicomponent oxides etching
The influence of surface chemistry in plasma etching of multicomponent oxides was investigated through measurements of the ion energy dependence of the etch yield. Using pulsed-laser-deposited Ca{sub x}Ba{sub (1-x)}Nb{sub 2}O{sub 6} (CBN) and SrTiO{sub 3} thin films as examples, it was found that the etching energy threshold shifts toward values larger or smaller than the sputtering threshold depending on whether or not ion-assisted chemical etching is the dominant etching pathway and whether surface chemistry is enhancing or inhibiting desorption of the film atoms. In the case of CBN films etched in an inductively coupled Cl{sub 2} plasma, it is found that the chlorine uptake is inhibiting the etching reaction, with the desorption of nonvolatile NbCl{sub 2} and BaCl{sub 2} compounds being the rate-limiting step.
Berube, P.-M.; Poirier, J.-S.; Margot, J.; Stafford, L. [Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-ville, Montreal, Quebec H3C 3J7 (Canada); Ndione, P. F.; Chaker, M.; Morandotti, R. [INRS-EMT, 1650 Boulevard Lionel Boulet, Varennes, Quebec J3X 1S2 (Canada)
An Experimental Verification, with Krypton, of the Theory of the Thermal Diffusion Column for Multicomponent Systems
The extended form of the Jones and Furry theory, which describes the behavior of a multicomponent heavy isotopic gas in a Clusius-Dickel thermal diffusion column, is tested. Experimental and theoretical values of the thermal diffusion column transport equation coefficients Hsub{ik},Ksub{c}, and Ksub{d}, are determined for krypton, a heavy isotopic gas with six isotopes. The experiments are carried out in a column of the hotwire type, at three wire temperatures: Tsub{H}=350 degrees C, 500 degrees C and 800 degrees C. Good agreement is found between the theoretical and experimental values of the coefficients. Seven of nine of the experimentally determined values of the coefficients agree within +- 10% with the corressponding theoretical values. The remaining two experimental values agree within +- 20% with the corresponding theoretical values.
Roos, W. J.
Multicomponent, Multiphase Thermodynamics of Swelling Porous Media with Electroquasistatics: I. Macroscale Field Equations
A systematic development of the macroscopic field equations (conservation of mass, linear and angular momentum, energy, and Maxwell�s equations) for a multiphase, multicomponent medium is presented. It is assumed that speeds involved are much slower than the speed of light and that the magnitude of the electric field significantly dominates over the magnetic field so that the electroquasistatic form of Maxwell�s equations applies. A mixture formulation is presented for each phase and then averaged to obtain the macroscopic formulation. Species electric fields are considered, however it is assumed that it is the total electric field which contributes to the electrically induced forces and energy. The relationships between species and bulk phase variables and the macroscopic and microscopic variables are given explicitly. The resulting field equations are of relevance to many practical applications including, but not limited to, swelling clays (smectites), biopolymers, biological membranes, pulsed electrophoresis, and chromatography.
Lynn Schreyer Bennethum; John H. Cushman
LDRD final report: Physical simulation of nonisothermal multiphase multicomponent flow in porous media
This document reports on the accomplishments of a laboratory-directed research and development (LDRD) project whose objective was to initiate a research program for developing a fundamental understanding of multiphase multicomponent subsurface transport in heterogeneous porous media and to develop parallel processing computational tools for numerical simulation of such problems. The main achievement of this project was the successful development of a general-purpose, unstructured grid, multiphase thermal simulator for subsurface transport in heterogeneous porous media implemented for use on massively parallel (MP) computers via message-passing and domain decomposition techniques. The numerical platform provides an excellent base for new and continuing project development in areas of current interest to SNL and the DOE complex including, subsurface nuclear waste disposal and cleanup, groundwater availability and contamination studies, fuel-spill transport for accident analysis, and DNAPL transport and remediation.
Martinez, M.J.; Hopkins, P.L.; Shadid, J.N.
Controlled drug release from bifunctionalized mesoporous silica
Serial of trimethylsilyl-carboxyl bifunctionalized SBA-15 (TMS/COOH/SBA-15) have been studied as carriers for controlled release of drug famotidine (Famo). To load Famo with large capacity, SBA-15 with high content of carboxyl groups was successfully synthesized by one-pot synthesis under the assistance of KCl. The mesostructure of carboxyl functionalized SBA-15 (COOH/SBA-15) could still be kept even though the content of carboxyl groups was up to 57.2%. Increasing carboxyl content could effectively enhance the loading capacity of Famo. Compared with pure SBA-15, into which Famo could be hardly adsorbed, the largest drug loading capacity of COOH/SBA-15 could achieve 396.9 mg/g. The release of Famo from mesoporous silica was studied in simulated intestine fluid (SIF, pH=7.4). For COOH/SBA-15, the release rate of Famo decreased with narrowing pore size. After grafting TMS groups on the surface of COOH/SBA-15 with hexamethyldisilazane, the release of Famo was greatly delayed with the increasing content of TMS groups. - Graphical abstract: Trimethylsilyl-carboxyl bifunctionalized SBA-15 has been studied as carrier for controlled release of drug famotidine. To load drug with large capacity, SBA-15 with high content of carboxyl groups was successfully synthesized. After grafting trimethylsilyl groups on the surface of carboxyl functionalized SBA-15, the release of Famo was greatly delayed with the increasing content of TMS groups.
Xu Wujun; Gao Qiang [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Xu Yao [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China)], E-mail: email@example.com; Wu Dong; Sun Yuhan [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China); Shen Wanling [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Deng Feng [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China)
Silica gel sorption properties under adiabatic conditions
The SERI Sorption Test Facility was modified from isothermal operation to adiabatic operating conditions so that we could measure the adsorption/desorption characteristics of silica-gel-coated, parallel-channel geometry as a function of operating conditions and aspect ratio under adiabatic conditions. We performed single-blow experiments on two single-passage test cells with different aspect ratios, air flow rates, and inlet conditions. Both adsorption and desorption runs were performed. As the air flow rate and aspect ratio increase when other parameters are kept constant, the desiccant matrix loses its sorption capacity faster. The test cell operated near isothermal conditions rather than adiabatically because the cell walls had a large thermal mass compared with the amount of desiccant used. Since constructing single-passage test cells with small thermal masses that can be operated adiabatically at the Sorption Test Facility is difficult, further testing at this facility will be primarily for isothermal operation. The adiabatic experiments can best be done with multipassage test cells having small thermal masses relative to desiccant mass. A single-blow test facility for performing experiments with multipassage test cells was fabricated in FY 1984, and experiments were performed in an FY 1985 desiccant project.
Pesaran, A.A.; Choudhury, K.
Silica recovery and control in Hawaiian geothermal fluids
A series of experiments was performed to investigate methods of controlling silica in waste geothermal brines produced at the HGP-A Generator Facility. Laboratory testing has shown that the rate of polymerization of silica in the geothermal fluids is highly pH dependent. At brine pH values in excess of 8.5 the suspension of silica polymers flocculated and rapidly precipitated a gelatinous silica mass. Optimum flocculation and precipitation rates were achieved at pH values in the range of 10.5 to 11.5. The addition of transition metal salts to the geothermal fluids similarly increased the rate of polymerization as well as the degree of precipitation of the silica polymer from suspension. A series of experiments performed on the recovered silica solids demonstrated that methanol extraction of the water in the gels followed by critical point drying yielded surface areas in excess of 300 M{sup 2}/g and that treatment of the dried solids with 2 N HCl removed most of the adsorbed impurities in the recovered product. A series of experiments tested the response of the waste brines to mixing with steam condensate and non-condensable gases.The results demonstrated that the addition of condensate and NCG greatly increased the stability of the silica in the geothermal brines. They also indicated that the process could reduce the potential for plugging of reinjection wells receiving waste geothermal fluids from commercial geothermal facilities in Hawaii. Conceptual designs were proposed to apply the gas re-combination approach to the disposal of geothermal waste fluids having a range of chemical compositions. Finally, these designs were applied to the geothermal fluid compositions found at Cerro Prieto, Ahuachapan, and Salton Sea.
Thomas, D.M.
Silica recovery and control in Hawaiian geothermal fluids. Final report
Silica-polystyrene nanocomposite particles synthesized by nitroxide-mediated polymerization and their encapsulation through miniemulsion polymerization
Polystyrene (PS) chains with molecular weights comprised between 8000 and 64000 g?mol-1and narrow polydispersities were grown from the surface of silica nanoparticles (Aerosil A200 fumed silica and St�ber silica, resp.) through nitroxide-mediated ...
B�rang�re Bailly; Anne-Carole Donnenwirth; Christ�le Bartholome; Emmanuel Beyou; Elodie Bourgeat-Lami
Molecular oxygen sensors based on photoluminescent silica aerogels
Molecular oxygen sensors based on photoluminescent silica aerogels Molecular oxygen sensors based on photoluminescent silica aerogels Title Molecular oxygen sensors based on photoluminescent silica aerogels Publication Type Journal Article Year of Publication 1998 Authors Ayers, Michael R., and Arlon J. Hunt Journal Journal of Non-Crystalline Solids Volume 225 Pagination 343-347 Keywords aerogel, air pressure, oxygen concentration, oxygen molecules, photoluminescence Abstract Photoluminescent silica aerogel acts as the active element of an optical sensor for molecular oxygen. The luminescent aerogel is prepared by the action of energized reducing gases on a standard silica aerogel. Intensity of aerogel photoluminescence decreases as the collision frequency between oxygen molecules and the luminescent carriers in the aerogel matrix increases. This behavior is a characteristic of many photoluminescent materials and arises from a transfer of energy from the aerogel to surrounding oxygen molecules. A sensor for oxygen concentration or air pressure can therefore be simply constructed utilizing an ultraviolet source for excitation and a suitable detector for the emitted visible signal. Stern-Volmer quenching constants for the aerogel sensing element are 1.55×10-2 Torr-1 for hydrophilic aerogel and 2.4×10-3 Torr-1 for hydrophobic aerogel.
We report the discovery of two supernova silica (SiO{sub 2}) grains in the primitive carbonaceous chondrites LaPaZ 031117 and Grove Mountains 021710. Only five presolar silica grains have been previously reported from laboratory measurements but they all exhibit enrichments in {sup 17}O relative to solar, indicating origins in the envelopes of asymptotic giant branch stars. The two SiO{sub 2} grains identified in this study are characterized by moderate enrichments in {sup 18}O relative to solar, indicating that they originated in Type II supernova ejecta. If compared to theoretical models, the oxygen isotopic compositions of these grains can be reproduced by mixing of different supernova zones. While both theoretical models of grain condensation and recent NASA Spitzer Space Telescope observations have suggested the presence of silica in supernova ejecta, no such grains had been identified, until now, in meteorites. The discovery of these two silica grains provides definitive evidence of the condensation of silica dust in supernova ejecta.
Haenecour, Pierre; Floss, Christine; Zinner, Ernst [Laboratory for Space Sciences, McDonnell Center for the Space Sciences and Physics Department, Washington University, One Brookings Drive, St. Louis, MO 63130-4899 (United States); Zhao Xuchao; Lin Yangting, E-mail: email@example.com [Key Laboratory of the Earth's Deep Interior, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029 (China)
Kinetics of silica deposition from simulated geothermal brines
Supersaturated brines were passed through columns packed with several forms of silica (crystalline ..cap alpha.. quartz, polycrystalline ..cap alpha.. quartz, and porous Vycor). Also, silica deposition on ThO/sub 2/ microspheres and titanium powder was studied under controlled conditions of supersaturation, pH, temperature, and salinity. The residence time was varied by adjustments of flow rate and column length. The silica contents of the input and effluent solutions were determined colorimetrically by a molybdate method which does not include polymers without special pretreatment. Essentially identical deposition behavior was observed once the substrate was thoroughly coated with amorphous silica and the BET surface area of the coated particles was taken into account. The reaction rate is not diffusion limited in the columns. The silica deposition is a function of the monomeric Si(OH)/sub 4/ concentration in the brine. The deposition on all surfaces examined was spontaneously nucleated. The dependence on the supersaturation concentration, hydroxide ion concentration, surface area, temperature and salinity were examined. Fluoride was shown to have no effect at pH 5.94 and low salinity. The empirical rate law which describes the data in 1 m NaCl in the pH range 5-7 and temperatures from 60 to 120/sup 0/C is given.
Bohlmann, E.G.; Mesmer, R.E.; Berlinski, P.
Methods to quantify contamination effects on silica gel samples
This report describes a study to establish methods for measuring sorption degradation of contaminated solid desiccants and determining the identity and nature of the contaminants. A literature search was conducted to determine how contaminants affect the sorption properties of silica gel and advanced solid desiccant materials; the search yielded 73 papers. Silica gel was chosen for the contamination study; nine samples from various batches and suppliers were tested. Methods were established (1) to measure the degradation of desiccant adsorption capacity caused by regeneration processes and/or exposure to contaminants and (2) to determine the nature of these contaminants. Sorption measurements on a limited number of fresh silica gel samples showed that the water adsorption capacity varied about +-10%. The silica gel sample regenerated with electric heaters exhibited a maximum capacity degradation of 7%. Silica gel samples processed in other ways lost between 20% and 47% capacity, depending on the age and cycle of regeneration. The contaminants found were silicon, oxygen, carbon, and nitrogen using x-ray photoelectron spectroscopy. Contamination can degrade the water sorption capacity of desiccants.
Pesaran, A.A.; Thomas, T.M.; Penney, T.R.; Czanderna, A.W.
Dewetting of silica surfaces upon reactions with supercritical CO2 and brine: Pore-scale studies in micromodels
Influence of Compressed Carbon Dioxide on the Capillarity ofof supercritical carbon dioxide on silica. Langmuir 2001,Silica Surfaces and the Carbon Dioxide Molecule. J Phys Chem
Kim, Y.
Silica membranes for hydrogen separation from coal gas. Final report
This project is a continuation of a previous DOE-UCR project (DE-FG22- 89PC89765) dealing with the preparation of silica membranes highly permselective to hydrogen at elevated temperatures, suitable for hydrogen separation from coal gas. The membranes prepared in the previous project had very high selectivity but relatively low permeance. Therefore, the general objectives of this project were to improve the permeance of these membranes and to obtain fundamental information about membrane structure and properties. The specific objectives were: (1) to explore new silylation reagents and reaction conditions with the purpose of reducing the thickness and increasing the permeance of silica membranes prepared by chemical vapor deposition (CVD), (2) to characterize the membrane structure, (3) to delineate mechanism and kinetics of deposition, (4) to measure the permeability of silica layers at different extents of deposition, and (5) to mathematically model the relationship between structure and deposition kinetics.
Gavalas, G.R.
We report a class of core-shell nanomaterials that can be used as efficient surface-enhancement Raman scattering (SERS) substrates. The core consists of silver nanowires, prepared through a chemical reduction process, that are used to capture 4- mercaptobenzoic acid (4-MBA), a model analyte. The shell was prepared through a modified St�ber method and consists of patchy or full silica coats. The formation of silica coats was monitored via transmission electron microscopy, UV-visible spectroscopy and phase-analysis light scattering for measuring effective surface charge. Surprisingly, the patchy silica coated silver nanowires are better SERS substrate than silver nanowires; nanomolar concentration of 4-MBA can be detected. In addition, �nano-matryoshka� configurations were used to quantitate/explore the effect of the electromagnetic field at the tips of the nanowire (�hot spots�) in the Raman scattering experiment.
Murph, S.; Murphy, C.
The dissociation of liquid silica at high pressure and temperature
Liquid silica at high pressure and temperature is shown to undergo significant structural modifications and profound changes in its electronic properties. Temperature measurements on shock waves in silica at 70-1000 GPa indicate that the specific heat of liquid SiO{sub 2} rises well above the Dulong-Petit limit, exhibiting a broad peak with temperature that is attributable to the growing structural disorder caused by bond-breaking in the melt. The simultaneous sharp rise in optical reflectivity of liquid SiO{sub 2} indicates that dissociation causes the electrical and therefore thermal conductivities of silica to attain metallic-like values of 1-5 x 10{sup 5} S/m and 24-600 W/m.K respectively.
Hicks, D; Boehly, T; Eggert, J; Miller, J; Celliers, P; Collins, G
A multi-component partitioning model to predict organic leaching from stabilized/solidified oily wastes
Stabilization/Solidification (S/S) is an established remediation process in hazardous waste management. Recently this process has been applied to hazardous organic wastes with mixed results. These results have prompted further studies to examine the effectiveness of this process in containing organic contaminants. The primary goal of S/S is to contain the contaminants in a solidified form, removing them from the environment. This is accomplished by decreasing the contaminant surface area and chemically converting the waste by reducing the contaminant solubility. The most common S/S processes utilize the chemical reactions achieved in cement-based and pozzolanic mixes. The effectiveness of this process is determined by the degree to which contaminants will leach from the waste end-product. Leach models, therefore, are an effective way to predict the leaching of contaminants and to describe the immobilization and binding mechanisms that take place. The multi-component nature of oily wastes requires that a multi-component approach be taken to describe the partitioning between the aqueous and non-aqueous phases. The heterogeneous nature of these wastes precludes analysis of partitioning of all chemical species. Thus a pseudo-component model has been developed that describes the partitioning of TOC as caused by the partitioning of a small number of pseudo-components. A pseudo-component is used to represent a group of chemical species that have similar tendencies to partition between the aqueous and non-aqueous phases. A linear partitioning relationship is used to develop the partitioning model, with the values of the partitioning coefficients chosen to represent strongly sorbed, moderately sorbed, and weakly sorbed components. The partitioning characteristics of the waste were determined in a series of sequential experiments in which different amounts of water were added. After each addition, the system was allowed to equilibrate, the added water removed by centrifugation and its TOC measured. The model predicts that the measured concentrations of TOC are due to the sum of all pseudo-components in the aqueous or mobile phase.
O'Cleirigh, Declan Ronan
Electrospinning of silica nanofibers: characterization and application to biosensing
Electrospinning is a technique to achieve nanometer scale fibers. Similar to the conventional spin methods of making fabric, the viscous polymer solution is ejected from a spinneret; stretched and solidified in the air, the solution forms the fibers. The different part of electrospinning among others is that the fibers are driven by the electrostatic force, which induces the repulsion inside the liquid and further reduces the diameter. The resultant product is a non-woven membrane, which is porous; and the pore size is around several nanometers to a micrometer wide. In this work, the relationship between the diameter of electrospun silica fibers, experimental parameters such as concentration and voltage, and between pore size of the fiber membrane and experimental time were studied. Materials used in the process are Polyvinylpyrrolidone (PVP), butanol and spin-on-glass coating solution, which act as polymer carrier, solvent, and silica-precursor, respectively. Polymer/silica precursor composite fibers were ejected from the needle of a plastic syringe when an electrical field, as high as several kV/cm, was applied. Then silica fibers were achieved by baking the composite ones at 773 oK for 12 h. Electrospun silica nanofibers were characterized as a function of polymer solution parameters. The calcined fibers were examined by using a field emission scanning electron microscope. The results showed that the fiber diameters decrease with decreasing proportion of polymer and silica precursor, and increase with a higher electric field. Pore sizes, defined as the grid areas enclosed by fibers on nearby layers, were also examined and showed no time-dependent tendency when the electrospin time was between 1-5 min. Fiber membranes were then used as the platform for protein detection. The results were compared with the control, which used glass slides as the platform. The results make it possible to make a more sensitive biosensing device.
Tsou, Pei-Hsiang
Potential Health Effects of Crystalline Silica Exposures from Coal Fly Ash: A Literature Review
The amount of crystalline silica in coal fly ash (CFA) depends on a variety of factors, including the amount of silica in the pre-combustion coal, the combustion process, and emission control technologies among others. Occupational exposures to crystalline silica in CFA are related to these factors as well as activities associated with exposures and durations of exposure. This review summarizes the occupational and environmental health literature relevant to the presence of crystalline silica in CFA from...
Analysis of the elastic behaviour of silica aerogels taken as a percolating system
289 Analysis of the elastic behaviour of silica aerogels taken as a percolating system T. Woignier of silica aerogels are performed using the three points flexural technique. The elastic behaviour is studied measurement - for silica aerogels. These highly porous materials are obtained from a sol-gel process. Solvent
Paris-Sud XI, Université de
Composition and cycle life of multicomponent AB{sub 5} hydride electrodes
Multicomponent AB{sub 5} hydrides are attractive replacements for the cadmium electrode in nickel -- cadmium batteries. The archetype compound of the AB{sub 5} alloy class is LaNi{sub 5}, but in a typical battery electrode mischmetal is substituted for La and Ni is substituted in part by variety of metals. While the effects of Ni substitution have been widely studied, relatively little effort has focused on the effect of La substitution. This paper deals with the effect on cycle life due to the increasing presence of Ce in the alloy series La{sub 1-x}Ce{sub x}Ni{sub 3.55}Co{sub .75}Mn{sub .4}Al{sub .3}. Alloys were characterized by the determination of pressure-composition relationships, molar volume of H and electrode cycle life. The effects due to lattice expansion are taken into account. It was concluded that the rate of loss of electrochemical capacity per charge/discharge cycle was significantly decreased due to the presence of Ce.
Adzic, G.D.; Johnson, J.R.; Reilly, J.J.; McBreen, J.; Mukerjee, S. [Brookhaven National Lab., Upton, NY (United States); Kumar, M.P.S.; Zhang, W.; Srinivasan, S. [Texas A and M Univ., College Station, TX (United States). Center for Electrochemical Systems and Hydrogen Research
Coagulation chemistries for silica removal from cooling tower water.
The formation of silica scale is a problem for thermoelectric power generating facilities, and this study investigated the potential for removal of silica by means of chemical coagulation from source water before it is subjected to mineral concentration in cooling towers. In Phase I, a screening of many typical as well as novel coagulants was carried out using concentrated cooling tower water, with and without flocculation aids, at concentrations typical for water purification with limited results. In Phase II, it was decided that treatment of source or make up water was more appropriate, and that higher dosing with coagulants delivered promising results. In fact, the less exotic coagulants proved to be more efficacious for reasons not yet fully determined. Some analysis was made of the molecular nature of the precipitated floc, which may aid in process improvements. In Phase III, more detailed study of process conditions for aluminum chloride coagulation was undertaken. Lime-soda water softening and the precipitation of magnesium hydroxide were shown to be too limited in terms of effectiveness, speed, and energy consumption to be considered further for the present application. In Phase IV, sodium aluminate emerged as an effective coagulant for silica, and the most attractive of those tested to date because of its availability, ease of use, and low requirement for additional chemicals. Some process optimization was performed for coagulant concentration and operational pH. It is concluded that silica coagulation with simple aluminum-based agents is effective, simple, and compatible with other industrial processes.
Nyman, May Devan; Altman, Susan Jeanne; Stewart, Tom
High temperature thermographic measurements of laser heated silica
In situ spatial and temporal surface temperature profiles of CO{sub 2} laser-heated silica were obtained using a long wave infrared (LWIR) HgCdTe camera. Solutions to the linear diffusion equation with volumetric and surface heating are shown to describe the temperature evolution for a range of beam powers, over which the peak surface temperature scales linearly with power. These solutions were used with on-axis steady state and transient experimental temperatures to extract thermal diffusivity and conductivity for a variety of materials, including silica, spinel, sapphire, and lithium fluoride. Experimentally-derived thermal properties agreed well with reported values and, for silica, thermal conductivity and diffusivity are shown to be approximately independent of temperature between 300 and 2800K. While for silica our analysis based on a temperature independent thermal conductivity is shown to be accurate, for other materials studied this treatment yields effective thermal properties that represent reasonable approximations for laser heating. Implementation of a single-wavelength radiation measurement in the semi-transparent regime is generally discussed, and estimates of the apparent temperature deviation from the actual outer surface temperature are also presented. The experimental approach and the simple analysis presented yield surface temperature measurements that can be used to validate more complex physical models, help discriminate dominant heat transport mechanisms, and to predict temperature distribution and evolution during laser-based material processing.
Elhadj, S; Yang, S T; Matthews, M J; Cooke, D J; Bude, J D; Johnson, M; Feit, M; Draggoo, V; Bisson, S E
Fabrication of magnetite/silica/titania core-shell nanoparticles
Fe3O4/SiO2/TiO2 core-shell nanoparticles were synthesized via a sol-gel method with the aid of sonication. Fe3O4 nanoparticles were being encapsulated within discrete silica nanospheres, ...
Suh Cem Pang; Sze Yun Kho; Suk Fun Chin
Fractal Studies on Titanium-Silica Aerogels using SMARTer
Power-law scattering approximation has been employed to reveal the fractal structures of solid-state titanium-silica aerogel samples. All small-angle neutron scattering (SANS) measurements were performed using 36 meters SANS BATAN spectrometer (SMARTer) at the neutron scattering laboratory (NSL) in Serpong, Indonesia. The mass fractal dimension of titanium-silica aerogels at low scattering vector q range increases from -1.4 to -1.92 with the decrease of acid concentrations during sol-gel process. These results are attributed to the titanium-silica aerogels that are growing to more polymeric and branched structures. At high scattering vector q range the Porod slope of -3.9 significantly down to -2.24 as the roughness of particle surfaces becomes higher. The cross over between these two regimes decreases from 0.4 to 0.16 nm{sup -1} with the increase of acid concentrations indicating also that the titanium-silica aerogels are growing.
Putra, E. Giri Rachman; Ikram, A.; Bharoto; Santoso, E. [Neutron Scattering Laboratory, BATAN, Kawasan Puspiptek Serpong, Tangerang 15314 (Indonesia); Fang, T. Chiar; Ibrahim, N. [Department of Physics, Faculty of Science Universiti Teknologi Malaysia (UTM), 81310 Skudai, Johor (Malaysia); Mohamed, A. Aziz [Materials Technology Group, Industrial Technology Division Agensi Nuklear Malaysia, 43000 Kajang (Malaysia)
Capacity degradation of field-tested silica gel samples
Researchers at the Solar Energy Research Institute (SERI) have begun preliminary studies to quantify the effect of contamination of silica gel used in dehumidification processes of desiccant cooling systems. Sorption capacity degradation of field tested samples was measured, and the source of degradation was quantified using surface analysis experimental methods.
Penney, T.R.; Pesaran, A.A.; Thomas, T.M.
Flue gas injection control of silica in cooling towers.
Injection of CO{sub 2}-laden flue gas can decrease the potential for silica and calcite scale formation in cooling tower blowdown by lowering solution pH to decrease equilibrium calcite solubility and kinetic rates of silica polymerization. Flue gas injection might best inhibit scale formation in power plant cooling towers that use impaired makeup waters - for example, groundwaters that contain relatively high levels of calcium, alkalinity, and silica. Groundwaters brought to the surface for cooling will degas CO{sub 2} and increase their pH by 1-2 units, possibly precipitating calcite in the process. Recarbonation with flue gas can lower the pHs of these fluids back to roughly their initial pH. Flue gas carbonation probably cannot lower pHs to much below pH 6 because the pHs of impaired waters, once outgassed at the surface, are likely to be relatively alkaline. Silica polymerization to form scale occurs most rapidly at pH {approx} 8.3 at 25 C; polymerization is slower at higher and lower pH. pH 7 fluids containing {approx}220 ppm SiO{sub 2} require > 180 hours equilibration to begin forming scale whereas at pH 8.3 scale formation is complete within 36 hours. Flue gas injection that lowers pHs to {approx} 7 should allow substantially higher concentration factors. Periodic cycling to lower recoveries - hence lower silica concentrations - might be required though. Higher concentration factors enabled by flue gas injection should decrease concentrate volumes and disposal costs by roughly half.
Brady, Patrick Vane; Anderson, Howard L., Jr.; Altman, Susan Jeanne
Development of a Multicomponent Prediction Model for Acute Esophagitis in Lung Cancer Patients Receiving Chemoradiotherapy
Purpose: To construct a model for the prediction of acute esophagitis in lung cancer patients receiving chemoradiotherapy by combining clinical data, treatment parameters, and genotyping profile. Patients and Methods: Data were available for 273 lung cancer patients treated with curative chemoradiotherapy. Clinical data included gender, age, World Health Organization performance score, nicotine use, diabetes, chronic disease, tumor type, tumor stage, lymph node stage, tumor location, and medical center. Treatment parameters included chemotherapy, surgery, radiotherapy technique, tumor dose, mean fractionation size, mean and maximal esophageal dose, and overall treatment time. A total of 332 genetic polymorphisms were considered in 112 candidate genes. The predicting model was achieved by lasso logistic regression for predictor selection, followed by classic logistic regression for unbiased estimation of the coefficients. Performance of the model was expressed as the area under the curve of the receiver operating characteristic and as the false-negative rate in the optimal point on the receiver operating characteristic curve. Results: A total of 110 patients (40%) developed acute esophagitis Grade {>=}2 (Common Terminology Criteria for Adverse Events v3.0). The final model contained chemotherapy treatment, lymph node stage, mean esophageal dose, gender, overall treatment time, radiotherapy technique, rs2302535 (EGFR), rs16930129 (ENG), rs1131877 (TRAF3), and rs2230528 (ITGB2). The area under the curve was 0.87, and the false-negative rate was 16%. Conclusion: Prediction of acute esophagitis can be improved by combining clinical, treatment, and genetic factors. A multicomponent prediction model for acute esophagitis with a sensitivity of 84% was constructed with two clinical parameters, four treatment parameters, and four genetic polymorphisms.
De Ruyck, Kim, E-mail: email@example.com [Department of Basic Medical Sciences, Ghent University, Ghent (Belgium); Sabbe, Nick [Department of Applied Mathematics, Biometrics and Process Control, Ghent University, Ghent (Belgium); Oberije, Cary [Department of Radiation Oncology (MAASTRO Clinic), Research Institute of Growth and Development, Maastricht University Medical Center, Maastricht (Netherlands); Vandecasteele, Katrien [Department of Radiation Oncology, Ghent University Hospital, Ghent (Belgium); Thas, Olivier [Department of Applied Mathematics, Biometrics and Process Control, Ghent University, Ghent (Belgium); De Ruysscher, Dirk; Lambin, Phillipe [Department of Radiation Oncology (MAASTRO Clinic), Research Institute of Growth and Development, Maastricht University Medical Center, Maastricht (Netherlands); Van Meerbeeck, Jan [Department of Respiratory Medicine, Ghent University Hospital, Ghent (Belgium); De Neve, Wilfried [Department of Radiation Oncology, Ghent University Hospital, Ghent (Belgium); Thierens, Hubert [Department of Basic Medical Sciences, Ghent University, Ghent (Belgium)
A sequential partly iterative approach for multicomponent reactive transport with CORE2D
CORE{sup 2D} V4 is a finite element code for modeling partly or fully saturated water flow, heat transport and multicomponent reactive solute transport under both local chemical equilibrium and kinetic conditions. It can handle coupled microbial processes and geochemical reactions such as acid-base, aqueous complexation, redox, mineral dissolution/precipitation, gas dissolution/exsolution, ion exchange, sorption via linear and nonlinear isotherms, sorption via surface complexation. Hydraulic parameters may change due to mineral precipitation/dissolution reactions. Coupled transport and chemical equations are solved by using sequential iterative approaches. A sequential partly-iterative approach (SPIA) is presented which improves the accuracy of the traditional sequential noniterative approach (SNIA) and is more efficient than the general sequential iterative approach (SIA). While SNIA leads to a substantial saving of computing time, it introduces numerical errors which are especially large for cation exchange reactions. SPIA improves the efficiency of SIA because the iteration between transport and chemical equations is only performed in nodes with a large mass transfer between solid and liquid phases. The efficiency and accuracy of SPIA are compared to those of SIA and SNIA using synthetic examples and a case study of reactive transport through the Llobregat Delta aquitard in Spain. SPIA is found to be as accurate as SIA while requiring significantly less CPU time. In addition, SPIA is much more accurate than SNIA with only a minor increase in computing time. A further enhancement of the efficiency of SPIA is achieved by improving the efficiency of the Newton-Raphson method used for solving chemical equations. Such an improvement is obtained by working with increments of log-concentrations and ignoring the terms of the Jacobian matrix containing derivatives of activity coefficients. A proof is given for the symmetry and non-singularity of the Jacobian matrix. Numerical analyses performed with synthetic examples confirm that these modifications improve the efficiency and convergence of the iterative algorithm.
Samper, J.; Xu, T.; Yang, C.
Vaporization modeling of petroleum-biofuel drops using a hybrid multi-component approach
Numerical modeling of the vaporization characteristics of multi-component fuel mixtures is performed in this study. The fuel mixtures studied include those of binary components, biodiesel, diesel-biodiesel, and gasoline-ethanol. The use of biofuels has become increasingly important for reasons of environmental sustainability. Biofuels are often blended with petroleum fuels, and the detailed understanding of the vaporization process is essential to designing a clean and efficient combustion system. In this study, a hybrid vaporization model is developed that uses continuous thermodynamics to describe petroleum fuels and discrete components to represent biofuels. The model is validated using the experimental data of n-heptane, n-heptane-n-decane mixture, and biodiesel. Since biodiesel properties are not universal due to the variation in feedstock, methods for predicting biodiesel properties based on the five dominant fatty acid components are introduced. Good levels of agreement in the predicted and measured drop size histories are obtained. Furthermore, in modeling the diesel-biodiesel drop, results show that the drop lifetime increases with the biodiesel concentration in the blend. During vaporization, only the lighter components of diesel fuel vaporize at the beginning. Biodiesel components do not vaporize until some time during the vaporization process. On the other hand, results of gasoline-ethanol drops indicate that both fuels start to vaporize once the process begins. At the beginning, the lighter components of gasoline have a slightly higher vaporization rate than ethanol. After a certain time, ethanol vaporizes faster than the remaining gasoline components. At the end, the drop reduces to a regular gasoline drop with heavier components. Overall, the drop lifetime increases as the concentration of ethanol increases in the drop due to the higher latent heat. (author)
Zhang, Lei; Kong, Song-Charng [Department of Mechanical Engineering, Iowa State University, 2025 Black Engineering Building, Ames, IA 50011 (United States)
Multi-component gas transport in CANDU fuel rods during severe accidents.
The multi-component transport of steam, hydrogen and stable fission gas in the fuel-to-clad gap of defective CANDU fuel rods, during severe accident conditions, is investigated. Based on a general Stefan-Maxwell treatment this work considers how incoming steam will diffuse into a breached rod against a counter-current flow of non-condensable fission gases and out-flowing hydrogen that is produced from the internal reaction of steam with the Zircaloy cladding or urania. The ability of the oxidized clad to act as a physical barrier to either hydrogen or oxygen diffusion was further investigated in the current work with a molecular-dynamics approach, with the interactions between atoms represented by a Modified Embedded Atom Method. During the initial Zircaloy oxidation phase in the CRL experiments, the model was able to predict the reduced fission product release kinetics as well as the timing for the completion of the clad-oxidation process. In this simulation, the model (with an effective gap size of 20 {micro}m) was able to successfully predict whether singlesided or double-sided oxidation had occurred in accordance with the metallographic examination. However, in order to account for the observed release kinetics after the completion of clad oxidation, it was necessary to assume a greater atmospheric exchange due to possible cracking of the brittle oxide layer. With the assumption of cracking (by assuming a reduced path length for gas transport), the model was successfully able to reproduce the fission product release kinetics and the final fuel stoichiometry as determined from end-of-test weight gain measurements. This analysis particularly shows that local hydrogen production (from the internal fuel oxidation process) will result in a reduced local oxygen potential in the fuel-to-clad gap compared to that which occurs in the bulk coolant.
Szpunar, B; Lewis, B. J.; Arimescu, V. I.; Dickson, R. S.; Dickson, L. W.; Baskes, M. I. (Michael I.)
Method for dissolution and stabilization of silica-rich fibers
This invention is comprised of a method for dissolving silica-rich fibers such as borosilicate fibers, fiberglass and asbestos to stabilize them for disposal. The method comprises (1) immersing the fibers in hot, five-weight-percent sodium hydroxide solution until the concentration of dissolved silica reaches equilibrium and a only a residue is left (about 48 hours), then immersing the residue in hot, five-weight-percent nitric acid until the residue dissolves (about 96 hours). After adjusting the pH of the dissolved fibers to be caustic, the solution can then be added to a waste vitrification stream for safe disposal. The method is useful in disposing contaminated HEME and HEPA filters.
Jantzen, C.M.
Molecular engineering of porous silica using aryl templates
A process for manipulating the porosity of silica using a series of organic template groups covalently incorporated into the silicate matrix. The templates in the bridged polysilsesquioxanes are selectively removed from the material by oxidation with oxygen plasma or other means, leaving engineered voids or pores. The size of these pores is dependent upon the length or size of the template or spacer. The size of the templates is measured in terms of Si-Si distances which range from about 0.67 nm to 1.08 nm. Changes introduced by the loss of the templates result in a narrow range of micropores (i.e. <2 nm). Both aryl and alkyl template groups are used as spacers. Novel microporous silica materials useful as molecular seives, dessicants, and catalyst supports are produced.
Loy, Douglas A. (Albuquerque, NM); Shea, Kenneth J. (Irvine, CA)
Fluorescent Functionalized Mesoporous Silica for Radioactive Material Extraction
Mesoporous silica with covalently bound salicylic acid molecules incorporated in the structure was synthesized with a one-pot, co-condensation reaction at room temperature. The as-synthesized material has a large surface area, uniform particle size, and an ordered pore structure as determined by characterization with transmission electron microscopy, thermal gravimetric analysis, and infrared spectra, etc. Using the strong fluorescence and metal coordination capability of salicylic acid, functionalized mesoporous silica (FMS) was developed to track and extract radionuclide contaminants, such as uranyl [U(VI)] ions encountered in subsurface environments. Adsorption measurements showed a strong affinity of the FMS toward U(VI) with a Kd value of 105 mL/g, which is four orders of magnitude higher than the adsorption of U(VI) onto most of the sediments in natural environments. The new materials have a potential for synergistic environmental monitoring and remediation of the radionuclide U(VI) from contaminated subsurface environments.
Li, Juan; Zhu, Kake; Shang, Jianying; Wang, Donghai; Nie, Zimin; Guo, Ruisong; Liu, Chongxuan; Wang, Zheming; Li, Xiaolin; Liu, Jun
A method is described for dissolving silica-rich fibers such as borosilicate fibers, fiberglass and asbestos to stabilize them for disposal. The method comprises (1) immersing the fibers in hot, five-weight-percent sodium hydroxide solution until the concentration of dissolved silica reaches equilibrium and a only a residue is left (about 48 hours), then immersing the residue in hot, five-weight-percent nitric acid until the residue dissolves (about 96 hours). After adjusting the pH of the dissolved fibers to be caustic, the solution can then be added to a waste vitrification stream for safe disposal. The method is useful in disposing contaminated HEME and HEPA filters. 1 fig.
A process is described for manipulating the porosity of silica using a series of organic template groups covalently incorporated into the silicate matrix. The templates in the bridged polysilsesquioxanes are selectively removed from the material by oxidation with oxygen plasma or other means, leaving engineered voids or pores. The size of these pores is dependent upon the length or size of the template or spacer. The size of the templates is measured in terms of Si-Si distances which range from about 0.67 nm to 1.08 nm. Changes introduced by the loss of the templates result in a narrow range of micropores (i.e. <2 nm). Both aryl and alkyl template groups are used as spacers. Novel microporous silica materials useful as molecular sieves, desiccants, and catalyst supports are produced. 3 figs.
Loy, D.A.; Shea, K.J.
Laser supported solid state absorption fronts in silica
We develop a model based on simulation and experiment that explains the behavior of solid-state laser-supported absorption fronts generated in fused silica during high intensity (up to 5GW/cm{sup 2}) laser exposure. We find that the absorption front velocity is constant in time and is nearly linear in laser intensity. Further, this model can explain the dependence of laser damage site size on these parameters. This behavior is driven principally by the temperature-activated deep sub band-gap optical absorptivity, free electron transport and thermal diffusion in defect-free silica for temperatures up to 15,000K and pressures < 15GPa. The regime of parameter space critical to this problem spans and extends that measured by other means. It serves as a platform for understanding general laser-matter interactions in dielectrics under a variety of conditions.
Carr, C W; Bude, J D
Plutonium complexation by phosphonate-functionalized mesoporous silica
MCM-41-type mesoporous silica functionalized with the CMPO-based 'Ac-Phos' silane has been reported in the literature (1) to show good capacity as an acftinide sorbent material, with potential applications in environmental sequestration, aqueous waste separation and/or vitrification, and chemical sensing of actinides in solution. The study explores the complexation of Pu(IV and VI) and other selected actinides and lanthanides by SBA-15 type mesoporous silica functionalized with Ac-Phos. The Pu binding kinetics and binding capacity were determined for both the Ac-Phos functionalized and unmodified SBA-15. They analyzed the binding geometry and redox behavior of Pu(VI) by X-ray absorption spectroscopy (XAS). They discuss the synthesis and characterization of the functionalized mesoporous material, batch sorption experiments, and the detailed analyses of the actinide complexes that are formed. Structural measurements are paired with high-level quantum mechanical modeling to elucidate the binding mechanisms.
Parsons-Moss, T; Schwaiger, L K; Hubaud, A; Hu, Y J; Tuysuz, H; Yang, P; Balasubramanian, K; Nitsche, H
Functionalized bimodal mesoporous silicas as carriers for controlled aspirin delivery
The bimodal mesoporous silica modified with 3-aminopropyltriethoxysilane was performed as the aspirin carrier. The samples' structure, drug loading and release profiles were characterized with X-ray diffraction, scanning electron microscopy, N{sub 2} adsorption and desorption, Fourier transform infrared spectroscopy, TG analysis, elemental analysis and UV-spectrophotometer. For further exploring the effects of the bimodal mesopores on the drug delivery behavior, the unimodal mesoporous material MCM-41 was also modified as the aspirin carrier. Meantime, Korsmeyer-Peppas equation f{sub t}=kt{sup n} was employed to analyze the dissolution data in details. It is indicated that the bimodal mesopores are beneficial for unrestricted drug molecules diffusing and therefore lead to a higher loading and faster releasing than that of MCM-41. The results show that the aspirin delivery properties are influenced considerably by the mesoporous matrix, whereas the large pore of bimodal mesoporous silica is the key point for the improved controlled-release properties. - Graphical abstract: Loading (A) and release profiles (B) of aspirin in N-BMMs and N-MCM-41 indicated that BMMs have more drug loading capacity and faster release rate than that MCM-41. Highlights: > Bimodal mesoporous silicas (BMMs) and MCM-41 modified with amino group via post-treatment procedure. > Loading and release profiles of aspirin in modified BMMs and MCM-41. > Modified BMMs have more drug loading capacity and faster release rate than that modified MCM-41.
Gao Lin [Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China); Sun Jihong, E-mail: email@example.com [Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China); Li Yuzhen [Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China)
Silica aerogel: An intrinsically low dielectric constant material
Silica aerogels are highly porous solids having unique morphologies in wavelength of visible which both the pores and particles have sizes less than the wavelength of visible light. This fine nanostructure modifies the normal transport mechanisms within aerogels and endows them with a variety of exceptional physical properties. For example, aerogels have the lowest measured thermal conductivity and dielectric constant for any solid material. The intrinsically low dielectric properties of silica aerogels are the direct result of the extremely high achievable porosities, which are controllable over a range from 75% to more than 99.8 %, and which result in measured dielectric constants from 2.0 to less than 1.01. This paper discusses the synthesis of silica aerogels, processing them as thin films, and characterizing their dielectric properties. Existing data and other physical characteristics of bulk aerogels (e.g., thermal stablity, thermal expansion, moisture adsorption, modulus, dielectric strength, etc.), which are useful for evaluating them as potential dielectrics for microelectronics, are also given.
Hrubesh, L.W.
This report describes an experimental investigation designed to identify binary and multicomponent mixture systems that may be for increasing the overall efficiency of a coal fired unit by extracting heat from flue gases. While ammonia-water mixtures have shown promise for increasing cycle efficiencies in a Kalina cycle, the costs and associated range of thermal conditions involved in a heat recovery system may prohibit its use in a relatively low temperature heat recovery system. This investigation considered commercially available non-azeotropic binary mixtures with a boiling range applicable to a flue gas initially at 477.6 K (400 F) and developed an experimental database of boiling heat transfer coefficients for those mixtures. In addition to their potential as working fluids for increasing cycle efficiency, cost, ease of handling, toxicity, and environmental concerns were considered in selection of the mixture systems to be examined experimentally. Based on this review, water-glycol systems were identified as good candidates. However, previous investigations of mixture boiling have focused on aqueous hydrocarbon mixtures, where water is the heaviest component. There have been few studies of water-glycol systems, and those that do exist have investigated boiling on plain surfaces only. In water-glycol systems, water is the light component, which makes these systems unique compared to those that have been previously examined. This report examines several water-glycol systems, and documents a database of experimental heat transfer coefficients for these systems. In addition, this investigation also examines the effect of an enhanced surface on pool boiling in water-glycol mixtures, by comparing boiling on a smooth surface to boiling on a Turbo IIIB. The experimental apparatus, test sections, and the experimental procedures are described. The mixture systems tested included water-propylene glycol, water-ethylene glycol, and water-diethylene glycol. All experimental data were obtained at atmospheric pressure with the test section oriented horizontally. The effect of subcooling in pool boiling of mixtures is another area that has received limited attention. Therefore, experimental data were obtained for the water-propylene glycol and water-ethylene glycol systems for subcoolings ranging from 0 to 30 C. The experimental data showed that boiling heat transfer coefficients were found to have significant degradation due to the mixture effect for each of the water-glycol systems examined. This result is consistent with previous studies which examined water-hydrocarbon mixtures with large boiling ranges. The Turbo BIII surface was found to significantly increase heat transfer in each mixture and pure component in comparison to that for the smooth surface.
Stephen M Bajorek; J. Schnelle
Multimodality Imaging with Silica-Based Targeted Nanoparticle Platforms
Objectives: To synthesize and characterize a C-Dot silica-based nanoparticle containing 'clickable' groups for the subsequent attachment of targeting moieties (e.g., peptides) and multiple contrast agents (e.g., radionuclides with high specific activity) [1,2]. These new constructs will be tested in suitable tumor models in vitro and in vivo to ensure maintenance of target-specificity and high specific activity. Methods: Cy5 dye molecules are cross-linked to a silica precursor which is reacted to form a dye-rich core particle. This core is then encapsulated in a layer of pure silica to create the core-shell C-Dot (Figure 1) [2]. A 'click' chemistry approach has been used to functionalize the silica shell with radionuclides conferring high contrast and specific activity (e.g. 64Cu and 89Zr) and peptides for tumor targeting (e.g. cRGD and octreotate) [3]. Based on the selective Diels-Alder reaction between tetrazine and norbornene, the reaction is bioorthogonal, highyielding, rapid, and water-compatible. This radiolabeling approach has already been employed successfully with both short peptides (e.g. octreotate) and antibodies (e.g. trastuzumab) as model systems for the ultimate labeling of the nanoparticles [1]. Results: PEGylated C-Dots with a Cy5 core and labeled with tetrazine have been synthesized (d = 55 nm, zeta potential = -3 mV) reliably and reproducibly and have been shown to be stable under physiological conditions for up to 1 month. Characterization of the nanoparticles revealed that the immobilized Cy5 dye within the C-Dots exhibited fluorescence intensities over twice that of the fluorophore alone. The nanoparticles were successfully radiolabeled with Cu-64. Efforts toward the conjugation of targeting peptides (e.g. cRGD) are underway. In vitro stability, specificity, and uptake studies as well as in vivo imaging and biodistribution investigations will be presented. Conclusions: C-Dot silica-based nanoparticles offer a robust, versatile, and multi-functional platform to enhance in vivo detection sensitivity and non-invasively assay receptor expression/status of tumor cellular targets, including those of low abundance, using nuclear-NIR fluorescence imaging approaches [2]. Improvements in molecular diagnostics, refined by the availability of nanotechnology platforms, will be a key determinant in driving early-stage disease detection and prevention, ultimately leading to decreases in mortality.
Jason S. Lewis
Preparation of silica stabilized biological templates for the production of metal and layered nanoparticles
The present invention relates to a system and method providing for increased silica growth on a bio-template, wherein the bio-template is pretreated with aniline to produce a uniform silica attractive surface and yielding a significant silica layers of at least 10 nm, and more preferably at least 20 nm in thickness, thereby providing for a high degree of stability to the bio-template.
Culver, James N; Royston, Elizabeth; Brown, Adam; Harris, Michael
XAS of uranium(VI) sorbed onto silica, alumina, and montmorillonite
The purpose of this work is to determine the speciation (oxidation state and molecular structure) of uranium sorbed onto surfaces of silica
E. R. Sylwester; P. G. Allen; E. A. Hudson
Luminescent organosilicon polymers and sol-gel synthesis of nano-structured silica
sol-�?gel �synthesis �of �nano-�?structured �silica � � by �a � Malvern �Zetasizer �Nano �series �instrument. �Zeta �of � aggregates � of � nano-�?C60. � Aquatic � Toxicol. �
Martinez, H. Paul
Cellular Effect of High Doses of Silica-Coated Quantum Dot ...
Cellular Effect of High Doses of Silica-Coated Quantum Dot Profiled with High Throughput Gene Expression Analysis and High Content Cellomics ...
Synthesis of Mesocellular Silica Foams with Tunable Window and Cell Dimensions
Polystyrene microspheres coated with cationic surfactants are easily prepared by micro- emulsion templates. These silica foams resemble dense aerogels. Introduction Because of their greatly enhanced pore
Yang, Peidong
Silicon Surface Texturing by Electro-Deoxidation of a Thin Silica ...
Presentation Title, Silicon Surface Texturing by Electro-Deoxidation of a Thin Silica Layer in Molten Salt. Author(s), Eimutis Juzeliunas, Antony Cox, Derek Fray
Synthesis and new structure shaping mechanism of silica particles formed at high pH
For the sol-gel synthesis of silica particles under high pH catalytic conditions (pH>12) in water/ethanol solvent, we have deduced that the competing dynamics of chemical etching and sol-gel process can explain the types of silica particles formed and their morphologies. We have demonstrated that emulsion droplets that are generated by adding tetraethyl orthosilicate (TEOS) to a water-ethanol solution serve as soft templates for hollow spherical silica (1-2 {mu}m). And if the emulsion is converted by the sol-gel process, one finds that suspended solid silica spheres of diameter of {approx}900 nm are formed. Moreover, several other factors are found to play fundamental roles in determining the final morphologies of silica particles, such as by variation of the pH (in our case, using OH{sup -}) to a level where condensation dominates; by changing the volume ratios of water/ethanol; and using an emulsifier (specifically, CTAB) - Graphical abstract: 'Local chemical etching' and sol-gel process have been proposed to interpret the control of morphologies of silica particles through varying initial pHs in syntheses. Highlights: Black-Right-Pointing-Pointer Different initial pHs in our syntheses provides morphological control of silica particles. Black-Right-Pointing-Pointer 'Local chemical etching' and sol-gel process describes the formation of silica spheres. Black-Right-Pointing-Pointer The formation of emulsions generates hollow silica particles.
Zhang, Henan; Zhao, Yu [Department of Chemistry, The City College of The University of New York, 160 Convent Avenue, New York, NY 10031 (United States)] [Department of Chemistry, The City College of The University of New York, 160 Convent Avenue, New York, NY 10031 (United States); Akins, Daniel L., E-mail: email@example.com [Department of Chemistry, The City College of The University of New York, 160 Convent Avenue, New York, NY 10031 (United States)
Silica Exposure Assessment of Oil And Gas Drilling Workers During Hydraulic Fracking Process.
??The problem investigated in this study was that of identifying the silica exposure to the employees of an oil gas company during the fracking process� (more)
Li, Jigang
Thermal annealing of laser damage precursors on fused silica surfaces
Previous studies have identified two significant precursors of laser damage on fused silica surfaces at fluenes below {approx} 35 J/cm{sup 2}, photoactive impurities in the polishing layer and surface fractures. In the present work, isothermal heating is studied as a means of remediating the highly absorptive, defect structure associated with surface fractures. A series of Vickers indentations were applied to silica surfaces at loads between 0.5N and 10N creating fracture networks between {approx} 10{micro}m and {approx} 50{micro}m in diameter. The indentations were characterized prior to and following thermal annealing under various times and temperature conditions using confocal time-resolved photo-luminescence (CTP) imaging, and R/1 optical damage testing with 3ns, 355nm laser pulses. Significant improvements in the damage thresholds, together with corresponding reductions in CTP intensity, were observed at temperatures well below the glass transition temperature (T{sub g}). For example, the damage threshold on 05.N indentations which typically initiates at fluences <8 J/cm{sup 2} could be improved >35 J/cm{sup 2} through the use of a {approx} 750 C thermal treatment. Larger fracture networks required longer or higher temperature treatment to achieve similar results. At an annealing temperature > 1100 C, optical microscopy indicates morphological changes in some of the fracture structure of indentations, although remnants of the original fracture and significant deformation was still observed after thermal annealing. This study demonstrates the potential of using isothermal annealing as a means of improving the laser damage resistance of fused silica optical components. Similarly, it provides a means of further understanding the physics associated with optical damage and related mitigation processes.
Shen, N; Miller, P E; Bude, J D; Laurence, T A; Suratwala, T I; Steele, W A; Feit, M D; Wang, L L
Previous studies have identified two significant precursors of laser damage on fused silica surfaces at fluenes below {approx} 35 J/cm{sup 2}, photoactive impurities in the polishing layer and surface fractures. In the present work, isothermal heating is studied as a means of remediating the highly absorptive, defect structure associated with surface fractures. A series of Vickers indentations were applied to silica surfaces at loads between 0.5N and 10N creating fracture networks between {approx} 10{micro}m and {approx} 50{micro}m in diameter. The indentations were characterized prior to and following thermal annealing under various times and temperature conditions using confocal time-resolved photo-luminescence (CTP) imaging, and R/1 optical damage testing with 3ns, 355nm laser pulses. Significant improvements in the damage thresholds, together with corresponding reductions in CTP intensity, were observed at temperatures well below the glass transition temperature (T{sub g}). For example, the damage threshold on 05.N indentations which typically initiates at fluences 35 J/cm{sup 2} through the use of a {approx} 750 C thermal treatment. Larger fracture networks required longer or higher temperature treatment to achieve similar results. At an annealing temperature > 1100 C, optical microscopy indicates morphological changes in some of the fracture structure of indentations, although remnants of the original fracture and significant deformation was still observed after thermal annealing. This study demonstrates the potential of using isothermal annealing as a means of improving the laser damage resistance of fused silica optical components. Similarly, it provides a means of further understanding the physics associated with optical damage and related mitigation processes.
Optical and radiographical characterization of silica aerogel for Cherenkov radiator
We present optical and X-ray radiographical characterization of silica aerogels with refractive index from 1.05 to 1.07 for a Cherenkov radiator. A novel pin-drying method enables us to produce highly transparent hydrophobic aerogels with high refractive index by shrinking wet-gels. In order to investigate the uniformity in the density (i.e., refractive index) of an individual aerogel monolith, we use the laser Fraunhofer method, an X-ray absorption technique, and Cherenkov imaging by a ring imaging Cherenkov detector in a beam test. We observed an increase in density at the edge of the aerogel tiles, produced by pin-drying.
Tabata, Makoto; Hatakeyama, Yoshikiyo; Kawai, Hideyuki; Morita, Takeshi; Nishikawa, Keiko
Measurement of Radiation Damage on Silica Aerogel \\v Cerenkov Radiator
We measured the radiation damage on silica aerogel \\v Cerenkov radiators originally developed for the $B$-factory experiment at KEK. Refractive index of the aerogel samples ranged from 1.012 to 1.028. The samples were irradiated up to 9.8~MRad of equivalent dose. Measurements of transmittance and refractive index were carried out and these samples were found to be radiation hard. Deteriorations in transparency and changes of refractive index were observed to be less than 1.3\\% and 0.001 at 90\\% confidence level, respectively. Prospects of using aerogels under high-radiation environment are discussed.
S. K. Sahu et al
Calculation of activities and solubilities of alkali metal perchlorates at high ionic strengths in multicomponent aqueous systems
The equations of Nyvlt, of Bromley, and of Pitzer for the representation of activity coefficients of electrolytes in multicomponent ionic systems have been used to fit solubility data for some alkali metal perchlorates and ammonium perchlorate in mixture with other electrolytes at ionic strengths varying from 0.08 mol-kg/sup -1/ to as high as 24 mol-kg/sup -1/. Only the Pitzer equations can be used reliably to fit the solubility data over the whole range of ionic strengths encountered for ternary systems but there are certain limitations and certain assumptions which have to be made concerning the Pitzer ionic interaction parameters. A method is also proposed for the calculation of the Pitzer single electrolyte parameters, ..beta../sup 0/, ..beta../sup 1/, and C/sup phi/, for the less soluble perchlorates from fitting their solubility data over a wide range of high ionic strengths.
Chan, C.; Khoo, K.H.
Preparation of silica aerogels with improved mechanical properties and extremely low thermal conductivities through modified sol-gel process
Reported silica aerogels have a thermal conductivity as low as 15 mW/mK. The fragility of silica aerogels, however, makes them impractical for structural applications. The purpose of the study is to improve the ductility ...
Zuo, Yanjia
Synthesis of silica nanoparticles by sol-gel: size-dependent properties, surface modification, and applications in silica-polymer nanocomposites � a review
Application of silica nanoparticles as fillers in the preparation of nanocomposite of polymers has drawnmuch attention, due to the increased demand for new materials with improved thermal, mechanical, physical, and chemical properties. Recent developments ...
Ismail Ab Rahman; Vejayakumaran Padavettan
Electrochromic nanocomposite of silica/polyaniline prepared from a water-in-oil microemulsion solution
A composite nanoparticle of silica/polyaniline was synthesized from a microemulsion and it was tested as an electrochromic film. The compositions for the stable microemulsion system was selected as 65.4 wt% cyclohexane, 30.4 wt% surfactant and 4.2 wt% ... Keywords: electrochromic, inorganic-organic hybrid, nanoparticle, operation life time, polyaniline, silica
Taejin Hwang; Heung Yeol Lee; Hohyeong Kim; Gyuntak Kim
Young's modulus evaluation by SAWs for porous silica low-k film with cesium doping
Young's moduli of porous silica low-k films with cesium (Cs) doping are determined by surface acoustic waves (SAWs) in this study. Four low-k samples doped with 0-30ppmwt% Cs in the precursor solution are investigated to check the mechanical promotion ... Keywords: Cesium doping, Low-k film, Porous silica, Surface acoustic waves, Young's modulus
X. Xiao; X. M. Shan; Y. Kayaba; K. Kohmura; H. Tanaka; T. Kikkawa
Mechanism of silica precipitation by lowering pH in chemi-thermomechanical pulping black liquors
Black liquor is a complex colloidal system obtained by chemical pulping process. It comprises of lignin, nearly 50% of the total organic and Silica approx. 2-3% (OD basis) of the total inorganic components. Black liquor is fed to chemical recovery plant ... Keywords: black liquors, desilication and concentrators, lignin, silica
Muhammad Ikram Aujla; Ishtiaq-Ur-Rehman Ishtiaq-Ur-Rehman; Asad Javaid
Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Jiangquan Zhang and D. Grischkowsky*
Terahertz Time-Domain Spectroscopy Study of Silica Aerogels and Adsorbed Molecular Vapors Jiangquan time-domain spectroscopy (THz-TDS) study of hydrophobic and hydrophilic silica aerogels, and the adsorption of several molecular vapors in the hydrophilic silica aerogel. The hydrophobic and hydrophilic
Oklahoma State University
Encapsulated in silica: genome, proteome and physiology of the thermophilic bacterium Anoxybacillus flavithermus
Gram-positive bacteria of the genus Anoxybacillus have been found in diverse thermophilic habitats, such as geothermal hot springs and manure, and in processed foods such as gelatin and milk powder. Anoxybacillus flavithermus is a facultatively anaerobic bacterium found in super-saturated silica solutions and in opaline silica sinter. The ability of A. flavithermus to grow in super-saturated silica solutions makes it an ideal subject to study the processes of sinter formation, which might be similar to the biomineralization processes that occurred at the dawn of life. We report here the complete genome sequence of A. flavithermus strain WK1, isolated from the waste water drain at the Wairakei geothermal power station in New Zealand. It consists of a single chromosome of 2,846,746 base pairs and is predicted to encode 2,863 proteins. In silico genome analysis identified several enzymes that could be involved in silica adaptation and biofilm formation, and their predicted functions were experimentally validated in vitro. Proteomic analysis confirmed the regulation of biofilm-related proteins and crucial enzymes for the synthesis of long-chain polyamines as constituents of silica nanospheres. Microbial fossils preserved in silica and silica sinters are excellent objects for studying ancient life, a new paleobiological frontier. An integrated analysis of the A. flavithermus genome and proteome provides the first glimpse of metabolic adaptation during silicification and sinter formation. Comparative genome analysis suggests an extensive gene loss in the Anoxybacillus/Geobacillus branch after its divergence from other bacilli.
Saw, Jimmy H [Los Alamos National Laboratory; Mountain, Bruce W [NEW ZEALAND; Feng, Lu [NANKAI UNIV; Omelchenko, Marina V [NCBI/NLM/NIH; Hou, Shaobin [UNIV OF HAWAII; Saito, Jennifer A [UNIV OF HAWAII; Stott, Matthew B [NEW ZEALAND; Li, Dan [NANKAI UNIV; Zhao, Guang [NANKAI UNIV; Wu, Junli [NANKAI UNIV; Galperin, Michael Y [NCBI/NLM/NIH; Koonin, Eugene V [NCBI/NLM/NIH; Makarova, Kira S [NCBI/NLM/NIH; Wolf, Yuri I [NCBI/NLM/NIH; Rigden, Daniel J [UNIV OF LIVERPOOL; Dunfield, Peter F [UNIV OF CALGARY; Wang, Lei [NANKAI UNIV; Alam, Maqsudul [UNIV OF HAWAII
Problems of Silica Scaling at Cerro Prieto Geothrmal Power Station
In the Cerro Prieto Geothermal field, where the predominant fluid in the reservoir is water, they have had problems with silica and other deposits in the first exploration wells as well as in production wells. Scaling problems have also been encountered in silencers, cyclone separators, drains, water pipes, etc. Some scale problems have also been encountered in the turbine blades of the geothermal electric plant. Most of these problems have been solved by corrective procedures which, in some cases, have turned into routine. Scale deposition is a problem that certainly diminishes the useful capacity of geothermal fluids with water predominance, but it does not actually endanger the installations, since this problem is under control.
Mercado, S.; Guiza, J.
Preparation of silica or alumina pillared crystalline titanates
Layered crystalline titanates (CT) [Anthony and Dosch, US Patent 5 177 045 (1993)] are pillared with tetraethyl orthosilicate, 3-aminopropyltrimethoxysilane, and aluminum acetylacetonate to prepare porous and high surface area supports for sulfided NiMo catalyst. Tetra-ethyl orthosilicate or aluminum acetylacetonate intercalated CT are prepared by stepwise intercalation. First, the basal distance is increased by n-alkylammonium ions prior to intercalation with inorganic compounds. However, an aqueous solution of 3-aminopropyltrimethoxysilane could directly pillar CT without first swelling the titanate with n-alkylamine. The catalytic activities for hydrogenation of pyrene of sulfided NiMo supported silica or alumina pillared CT were higher than those of commercial catalysts (Shell324 and Amocat1C). The silicon and aluminum contents of the pillared CT, used as supports, have a considerable effect on the catalytic activities and physical properties of the supports.
Udomsak, S.; Nge, R.; Dufner, D.C.; Anthony, R.G. [Texas A and M Univ., College Station, TX (United States); Lott, S.E. [Sandia National Labs., Albuquerque, NM (United States)
Hydrogen and oxygen adsorption stoichiometries on silica supported ruthenium nanoparticles
Treatment under H{sub 2} at 300 C of Ru(COD)(COT) dispersed on silica yields 2 nm ruthenium nanoparticles, [Ru{sub p}/SiO{sub 2}], according to EXAFS, HRTEM and XPS. H{sub 2} adsorption measurements on [Ru{sub p}/SiO{sub 2}] in the absence of O{sub 2} show that Ru particles adsorb up to ca. 2 H per surface ruthenium atoms (2H/Ru{sub s}) on various samples; this technique can therefore be used to measure the dispersion of Ru particles. In contrast, O{sub 2} adsorption on [Ru{sub p}/SiO{sub 2}] leads to a partial oxidation of the bulk at 25 C, to RuO{sub 2} at 200 C and to sintering upon further reduction under H{sub 2}, showing that O{sub 2} adsorption cannot be used to measure the dispersion of Ru particles.
Berthoud, Romain; Delichere, Pierre; Gajan, David; Lukens, Wayne; Pelzer, Katrin; Basset, Jean-Marie; Candy, Jean-Pierre; Coperet, Christophe
Performance predictions of silica-gel desiccant dehumidifiers
The analysis of a cross-cooled desiccant dehumidifier using silica gel in the form of sheets is described. This unit is the principal component of solar powered desiccant air conditioning system. The mathematical model has first been formulated describing the dynamics of the dehumidifier. The model leads to a system of nonlinear coupled heat and mass transfer equations for the sorption processes and linear heat transfer equations for the purging processes. The model accounts for the gas film resistance and for the moisture diffusion in the desiccant. The governing equations are solved by a finite difference scheme to obtain periodic steady state solutions. The accuracy of the theoretical predictions is ascertained by comparing them with the experimental results. The performance of the dehumidifier, for a chosen set of initial conditions and dehumidifier parameters, has also been given.
Mathiprakasam, B.; Lavan, Z.
Determination of silica deposition rates and thresholds applied towards protection of injection reservoirs
This program was instituted to quantify certain aspects of silica scaling deposition processes at the Miravalles Geothermal Field, Costa Rica. The program objective was to identify the highest temperature at which silica scale will develop from partially evaporated and significantly cooled geothermal liquid under operating conditions. Integral to the study objective was the quantification of certain aspects of silica deposition processes at the Miravalles Geothermal Field, Costa Rica. There, the objective was to reduce the scaling risk associated with adding a bottoming-cycle to generate more electricity from the liquids already being produced.
Geothermal Development Associates; Don Michels Associates
Improved Predictions of Carbon Tetrachloride Contaminant Flow and Transport: Implementation of Kinetic Volatilization and Multicomponent NAPL Behavior
Carbon tetrachloride (CT) was discharged to waste sites that are included in the 200-PW-1 Operable Unit in Hanford 200 West Area. Fluor Hanford, Inc. is conducting a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) remedial investigation/feasibility study (RI/FS) for the 200-PW-1 Operable Unit. The RI/FS process and remedial investigations for the 200-PW-1, 200 PW-3, and 200-PW-6 Operable Units are described in the Plutonium/Organic-Rich Process Condensate/Process Waste Groups Operable Unit RI/FS Work Plan. As part of this overall effort, Pacific Northwest National Laboratory (PNNL) was contracted to improve the STOMP simulator (White and Oostrom, 2006) by incorporating kinetic volatilization of nonaqueous phase liquids (NAPL) and multicomponent flow and transport. This work supports the U.S. Department of Energy's (DOE's) efforts to characterize the nature and distribution of CT in the 200 West Area and subsequently select an appropriate final remedy. Previous numerical simulation results with the STOMP simulator have overestimated the effect of soil vapor extraction (SVE) on subsurface CT, showing rapid removal of considerably more CT than has actually been recovered so far. These previous multiphase simulations modeled CT mass transfer between phases based on equilibrium partitioning. Equilibrium volatilization can overestimate volatilization because mass transfer limitations present in the field are not considered. Previous simulations were also conducted by modeling the NAPL as a single component, CT. In reality, however, the NAPL mixture disposed of at the Hanford site contained several non-volatile and nearly insoluble organic components, resulting in time-variant fluid properties as the CT component volatilized or dissolved over time. Simulation of CT removal from a DNAPL mixture using single-component DNAPL properties typically leads to an overestimation of CT removal. Other possible reasons for the discrepancy between observed and simulated CT mass removal during SVE are differences between the actual and simulated (1) SVE flow rates, (2) fluid-media properties, and (3) disposal history (volumes, rates, and timing). In this report, numerical implementation of kinetic volatilization and multicomponent DNAPL flow and transport into the STOMP simulator (White and Oostrom, 2006) is described. The results of several test cases are presented and explained. The addition of these two major code enhancements increases the ability of the STOMP simulator to model complex subsurface flow and transport processes involving CT at the Hanford site.
Oostrom, Martinus; Zhang, Z. F.; Freedman, Vicky L.; Tartakovsky, Guzel D.
The research focussed on fundamental problems in the conversion of light to stored chemical energy. Specifically, work was completed on the design, synthesis and study of multi-component super- and supramolecular systems for photoinduced charge separation, one of the key steps in artificial photosynthesis, and on the use of these and related systems for the photochemical generation of H2 from water. At the center of these systems are chromophores comprised of square planar coordinated Pt(II) ions with arylacetylide and either diimine or terpyridyl ligands. Previous work had shown that the chromophores are photoluminescent in fluid solution with long-lived metal-to-ligand charge transfer (3MLCT) excited states that are necessarily directional. An advance which set the stage for a number of proposed studies was the light-driven production of hydrogen from water using a Pt(terpyridyl)(arylacetylide)+ chromophore and a sacrificial electron donor. The reaction is catalytic and appears to rival previously reported ruthenium bipyridyl systems in terms of H2 production. Variation of system components and mechanistic studies were conducted to understand better the individual steps in the overall process and how to improve its efficiency. Success with light driven H2 generation was employed as a key probe as new systems were constructed consisting of triads for photoinduced charge separation placed in close proximity to the H2 generating catalyst - a Pt colloid - through direct linkage or supramolecular interactions with the polymer used to stabilize the colloid. In order to prepare new donor-chromophore-acceptor (D-C-A) triads and associated D-C and C-A dyads, new ligands were synthesized having functional groups for different coupling reactions such as simple amide formation and Pd-catalyzed coupling. In these systems, the donor was attached to the arylacetylide ligands and the acceptor was linked to the diimine or terpyridyl chelate. Research under the contract proved successful in the development of synthetic methodologies to make multi-component systems designed so as to maintain electronic communication between components held in a defined spatial arrangement. Systems effective for light driven H2 generation were examined by photophysical methods including transient absorption spectroscopy to observe charge-separated states and chart their dynamics. Quantum yields for hydrogen production were also measured. Additional studies examined the effectiveness of these systems for H2 generation and involved the development of new catalysts and systems based thereon. From these studies, a better understanding of initial steps in the light driven generation of hydrogen were obtained.
Professor Richard Eisenberg
COMMIX-PPC: A three-dimensional transient multicomponent computer program for analyzing performance of power plant condensers
The COMMIX-PPC computer pregrain is an extended and improved version of earlier COMMIX codes and is specifically designed for evaluating the thermal performance of power plant condensers. The COMMIX codes are general-purpose computer programs for the analysis of fluid flow and heat transfer in complex Industrial systems. In COMMIX-PPC, two major features have been added to previously published COMMIX codes. One feature is the incorporation of one-dimensional equations of conservation of mass, momentum, and energy on the tube stile and the proper accounting for the thermal interaction between shell and tube side through the porous-medium approach. The other added feature is the extension of the three-dimensional conservation equations for shell-side flow to treat the flow of a multicomponent medium. COMMIX-PPC is designed to perform steady-state and transient. Three-dimensional analysis of fluid flow with heat transfer tn a power plant condenser. However, the code is designed in a generalized fashion so that, with some modification, it can be used to analyze processes in any heat exchanger or other single-phase engineering applications. Volume I (Equations and Numerics) of this report describes in detail the basic equations, formulation, solution procedures, and models for a phenomena. Volume II (User's Guide and Manual) contains the input instruction, flow charts, sample problems, and descriptions of available options and boundary conditions.
Chien, T.H.; Domanus, H.M.; Sha, W.T.
Luminescence properties of mesoporous silica nanoparticles encapsulating different europium complexes: application for biolabelling
In this work we have synthesized and characterized new hybrid nanoplatforms for luminescent biolabeling based on the concept of Eu3+ complexes encapsulation in mesoporous silica nanoparticles (?100 nm). Eu complexes have been selected ...
S. Lechevallier, J. Jorge, R. M. Silveira, N. Ratel-Ramond, D. Neumeyer, M. J. Menu, M. Gressier, A. L. Mar�al, A. L. Rocha, M. A. U. Martines, E. Magdeleine, J. Dexpert-Ghys, M. Verelst
Mesoporous silica SBA-16 functionalized with alkoxysilane groups: preparation, characterization, and release profile study
A mesoporous material sphere based on silica, SBA-16, was chemically modified with alkoxysilane using two different solvents: methanol and toluene. The influence of the chemical modification of the matrix on the release rate of a model drug was also ...
Gracielle Ferreira Andrade; Daniel Cristian Ferreira Soares; Ramon Kenned de Sousa Almeida; Ed�sia Martins Barros Sousa
Method for inhibiting silica precipitation and scaling in geothermal flow systems
A method for inhibiting silica scaling and precipitation in geothermal flow systems by on-line injection of low concentrations of cationic nitrogen-containing compounds, particularly polymeric imines, polymeric amines, and quaternary ammonium compounds.
Harrar, Jackson E. (Castro Valley, CA); Lorensen, Lyman E. (Orinda, CA); Locke, Frank E. (Lafayette, CA)
A method for inhibiting silica scaling and precipitation in geothermal flow systems by on-line injection of low concentrations of cationic nitrogen-containing compounds, particularly polymeric imines, polymeric amines, and quaternary ammonium compounds is described.
Harrar, J.E.; Lorensen, L.E.; Locke, F.E.
Suitability of Silica Gel to Process INEEL Sodium Bearing Waste - Letter Report
The suitability of using the silica gel process for Idaho National Engineering and Environmental Laboratory (INEEL) sodium bearing waste was investigated during fiscal year 2000. The study was co-funded by the Tanks Focus Area as part of TTP No. ID-77WT-31 and the High Level Waste Program. The task also included the investigation of possible other absorbents. Scoping tests and examination of past work showed that the silica gel absorption/adsorption and drying method was the most promising; thus only silica gel was studied and not other absorbents. The documentation on the Russian silica gel process provided much of the needed information but did not provide some of the processing detail so these facts had to be inferred or gleaned from the literature.
Kirkham, Robert John; Herbst, Alan Keith
Assessment of Methods to Consolidate Iodine-Loaded Silver-Functionalized Silica Aerogel
The U.S. Department of Energy is currently investigating alternative sorbents for the removal and immobilization of radioiodine from the gas streams in a nuclear fuel reprocessing plant. One of these new sorbents, Ag0-functionalized silica aerogels, shows great promise as a potential replacement for Ag-bearing mordenites because of its high selectivity and sorption capacity for iodine. Moreover, a feasible consolidation of iodine-loaded Ag0-functionalized silica aerogels to a durable SiO2-based waste form makes this aerogel an attractive choice for sequestering radioiodine. This report provides a preliminary assessment of the methods that can be used to consolidate iodine-loaded Ag0-functionalized silica aerogels into a final waste form. In particular, it focuses on experimental investigation of densification of as prepared Ag0-functionalized silica aerogels powders, with or without organic moiety and with or without sintering additive (colloidal silica), with three commercially available techniques: 1) hot uniaxial pressing (HUP), 2) hot isostatic pressing (HIP), and 3) spark plasma sintering (SPS). The densified products were evaluated with helium gas pycnometer for apparent density, with the Archimedes method for apparent density and open porosity, and with high-resolution scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) for the extent of densification and distribution of individual elements. The preliminary investigation of HUP, HIP, and SPS showed that these sintering methods can effectively consolidate powders of Ag0-functionalized silica aerogel into products of near-theoretical density. Also, removal of organic moiety and adding 5.6 mass% of colloidal silica to Ag0-functionalized silica aerogel powders before processing provided denser products. Furthermore, the ram travel data for SPS indicated that rapid consolidation of powders can be performed at temperatures below 950�C.
Matyas, Josef; Engler, Robert K.
Synthesis of SiC ceramics by the carbothermal reduction of mineralized wood with silica
This paper describes the synthesis of SiC by the carbothermal reduction of mineralized wood with silica in acidic condition. The biomorphic cellular SiC ceramics were prepared by controlling the amount of silica and the size of SiC nanoparticles. Up to 20wt% of SiO2 was mineralized into wood cellular structures and the hierarchical structures such as cells, lumen, and pits were mainly retained after the thermal treatment at 1400 C.
Shin, Yongsoon; Wang, Chong M.; Exarhos, Gregory J.
Dispersion Morphology of Poly(methyl acrylate)/Silica Nanocomposites
Nearly monodisperse poly(methyl acrylate) (PMA) and spherical SiO{sub 2} nanoparticles (NP, d = 14 {+-} 4 nm) were co-cast from 2-butanone, a mutually good solvent and a displacer of adsorbed PMA from silica. The effects of NP content and post-casting sample history on the dispersion morphology were found by small-angle X-ray scattering supplemented by transmission electron microscopy. Analysis of the X-ray results show that cast and thermally annealed samples exhibited a nearly random particle dispersion. That the same samples, prior to annealing, were not well-dispersed is indicative of thermodynamic miscibility during thermal annealing over the range of NP loadings studied. A simple mean-field thermodynamic model suggests that miscibility results primarily from favorable polymer segment/NP surface interactions. The model also indicates, and experiments confirm, that subsequent exposure of the composites to the likely displacer ethyl acetate results in entropic destabilization and demixing into NP-rich and NP-lean phases.
D Janes; J Moll; S Harton; C Durning
Assistant template and co-template agents in modeling mesoporous silicas and post-synthesizing organofunctionalizations
Mesoporous SBA-16 silicas were synthesized through a direct methodology using the template (F127) combined with co-templates (ethanol and n-butanol), with tetraethylorthosilicate as the silica source. These ordered mesoporous silica were characterized by elemental analyses, infrared spectroscopy, solid-state nuclear magnetic resonance for {sup 13}C (CP/MAS) and {sup 29}Si (HP/DEC) nuclei, nitrogen sorption/desorption processes, small angle X-ray analyses (SAXS) and transmission electron microscopy (TEM). SAXS and TEM results confirmed the space group Im3m and cubic 3D symmetry, typical for highly ordered SBA-16. The sorption/desorption data for SBA-16 and when functionalized gave type IV isotherms, with hysteresis loop H2. Surface areas of 836; 657 and 618 m{sup 2} g{sup -1} and average pore diameters of 7.99; 8.10 and 9.85 nm, for SBA-16A, SBA-16B and SBA-16C were obtained, respectively. When functionalized the silicas presented a reduction in surface area, pore volume and pore diameter due to the pendant chains that interfere with nitrogen sorption in these measurements. The co-template ethanol favors the ordered mesopores with highest wall thicknesses. - Graphical Abstract: The mesoporous SBA-16 can be synthesized from binary (F127/TEOS) or ternary (F127/alcohol/TEOs) systems to give well-ordered mesoporous silicas. The co-templates ethanol or butanol gave the final material with highest wall thickness, mainly with ethanol. After these syntheses the pores were successfully organofunctionalized to give a good incorporation of the silylating agents. The final silicas presented of well-arranged solid characteristics as expressing by three distinct peaks, as indexed by the corresponding planes. Highlights: Black-Right-Pointing-Pointer Syntheses of mesoporous silicas by using ternary (F127/agent/TEOS) and binary (F127/TEOS) systems. Black-Right-Pointing-Pointer Use of co-templates to synthesize mesoporous silicas with larger wall thicknesses. Black-Right-Pointing-Pointer Immobilization of pendant chains inside the porous silicas. Black-Right-Pointing-Pointer Ordered mesoposous silicas as new materials for possible applications on sorption and delivering drug systems.
Oliveira, Vaeudo V. [Institute of Chemistry, University of Campinas, UNICAMP, PO Box 6154, 13084-971 Campinas, SP (Brazil)] [Institute of Chemistry, University of Campinas, UNICAMP, PO Box 6154, 13084-971 Campinas, SP (Brazil); Airoldi, Claudio, E-mail: firstname.lastname@example.com [Institute of Chemistry, University of Campinas, UNICAMP, PO Box 6154, 13084-971 Campinas, SP (Brazil)] [Institute of Chemistry, University of Campinas, UNICAMP, PO Box 6154, 13084-971 Campinas, SP (Brazil)
Silica precipitation and scaling in a dynamic loop system. [Design and testing of titanium corrosion test loop
A titanium corrosion test loop was modified to provide a dynamic facility for studying the formation of silica precipitates and scale from simulated geothermal brines as a function of composition, temperature, and flow conditions. A schematic of the modified loop system is presented. The principal components and connecting piping are all constructed of commercially pure titanium. These components include a centrifugal pump, silica saturator column, segmented heat exchanger, reheat heat exchanger, and a high pressure feed pump (stainless steel). The system is designed to circulate simulated geothermal brines saturated with silica to approximately 300/sup 0/C for study of silica scaling. Data obtained from a test run are included. (JGB)
Bohlmann, E.G.; Shor, A.J.; Berlinski, P.
Thin film nanoporous silica and graphene based biofuel cells (iBFCs) for low-power implantable medical device applications.
??This thesis describes the fabrication and characterization of an inorganic catalyst based glucose Biofuel cell using nanoporous (mesoporous) silica thin-film as a functional membrane. The� (more)
Sharma, Tushar
Direct encapsulation of water-soluble drug into silica microcapsules for sustained release applications
Direct encapsulation of water-soluble drug into silica microcapsules was facilely achieved by a sol-gel process of tetraethoxysilane (TEOS) in W/O emulsion with hydrochloric acid (HCl) aqueous solution containing Tween 80 and drug as well as cyclohexane solution containing Span 80. Two water-soluble drugs of gentamicin sulphate (GS) and salbutamol sulphate (SS) were chosen as model drugs. The characterization of drug encapsulated silica microcapsules by scanning electronic microscopy (SEM), FTIR, thermogravimetry (TG) and N{sub 2} adsorption-desorption analyses indicated that drug was successfully entrapped into silica microcapsules. The as-prepared silica microcapsules were uniform spherical particles with hollow structure, good dispersion and a size of 5-10 {mu}m, and had a specific surface area of about 306 m{sup 2}/g. UV-vis and thermogravimetry (TG) analyses were performed to determine the amount of drug encapsulated in the microcapsules. The BJH pore size distribution (PSD) of silica microcapsules before and after removing drug was examined. In vitro release behavior of drug in simulated body fluid (SBF) revealed that such system exhibited excellent sustained release properties.
Wang Jiexin; Wang Zhihui [Key Lab for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Chen Jianfeng [Key Lab for Nanomaterials, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029 (China); Research Center of the Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing 100029 (China)], E-mail: firstname.lastname@example.com; Yun, Jimmy [Nanomaterials Technology Pte. Ltd., 28 Ayer Rajah Crescent 03-03, Singapore 139959 (Singapore)
Solubility of Gases in Glass. II. He, Ne, and H2 in Fused Silica
The statistical thermodynamics of the gas?in?glass system provides a basic model of both physical and chemical solubility. The physical solubility result is essentially equivalent to that for monatomic solubility. The chemical solubility result is dependent upon the specific system involved. The model was compared with experiment for a variety of systems. Helium and neon in fused silica were examples of the physical solubility of monatomic gases. Variations of the thermal history of the fused silica did not appear to have a measurable effect on physical solubility as evidenced in the helium data. Hydrogen in fused silica was an example of the physical solubility of polyatomic gases. Physical solubility was measured by a modified Seiverts technique and was characterized by a linear dependence on pressure. Binding energies for the physically dissolved species were of the order expected for van der Waals bonding. Vibrational frequencies were on the order of 1013 sec?1 with the heavier species having the lower frequencies. Hydrogen in fused silica was also an example of the chemical solubility of polyatomic gases. The literature gave data for the chemical solution of hydrogen in fused silica
James F. Shackelford; Perry L. Studt; Richard M. Fulrath
Synthesis of palladium-doped silica nanofibers by sol-gel reaction and electrospinning process
Nanofiber is drawing great attention nowadays with their high surface area per volume and flexibility in surface functionalities that make them favorable as a proton exchange membrane in fuel cell application. In this study, incorporation of palladium nanoparticles in silica nanofibers was prepared by combination of a tetraorthosilane (TEOS) sol-gel reaction with electrospinning process. This method can prevent the nanoparticles from aggregation by direct mixing of palladium nanoparticles in silica sol. The as-produced electrospun fibers were thermally treated to remove poly(vinyl pyrrolidone) (PVP) and condensation of silanol in silica framework. PVP is chosen as fiber shaping agent because of its insulting and capping properties for various metal nanoparticles. Scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the silica fibers and Pd nanoparticles on the fibers. Spun fibers with average diameter ranged from 100nm to 400nm were obtained at optimum operating condition and distribution of Pd nanoparticles on silica fibers was investigated.
San, Thiam Hui; Daud, Wan Ramli Wan; Kadhum, Abdul Amir Hassan; Mohamad, Abu Bakar; Kamarudin, Siti Kartom; Shyuan, Loh Kee; Majlan, Edy Herianto [Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia and Department of Chemical and Process Engineering, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia); Fuel Cell Institute, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)
Solidification of Acidic, High Nitrate Nuclear Wastes by Grouting or Absorption on Silica Gel
The use of grout and silica gel were explored for the solidification of four types of acidic, high nitrate radioactive wastes. Two methods of grouting were tested: direct grouting and pre-neutralization. Two methods of absorption on silica gel were also tested: direct absorption and rotary spray drying. The waste simulant acidity varied between 1 N and 12 N. The waste simulant was neutralized by pre-blending calcium hydroxide with Portland cement and blast furnace slag powders prior to mixing with the simulant for grout solidification. Liquid sodium hydroxide was used to partially neutralize the simulant to a pH above 2 and then it was absorbed for silica gel solidification. Formulations for each of these methods are presented along with waste form characteristics and properties. Compositional variation maps for grout formulations are presented which help determine the optimum "recipe" for a particular waste stream. These maps provide a method to determine the proportions of waste, calcium hydroxide, Portland cement, and blast furnace slag that provide a waste form that meets the disposal acceptance criteria. The maps guide researchers in selecting areas to study and provide an operational envelop that produces acceptable waste forms. The grouts both solidify and stabilize the wastes, while absorption on silica gel produces a solid waste that will not pass standard leaching procedures (TCLP) if required. Silica gel wastes can be made to pass most leach tests if heated to 600�C.
A. K. Herbst; S. V. Raman; R. J. Kirkham
Characterization of Dry-Air Aged Granules of Silver-Functionalized Silica Aerogel
This is a letter report to complete level 3 milestone "Assess aging characteristics of silica aerogels" for DOE FCRD program. Recently, samples of Ag0-functionalized silica aerogel were aged in flowing dry air for up to 6 months and then loaded with iodine. This dry-air aging simulated the impact of long-term exposure to process gases during process idling. The 6-month aged sample exhibited an iodine sorption capacity of 32 mass%, which was 9 mass % lower than that for an un-aged Ag0-functionalized silica aerogel. In an attempt to understand this decrease in sorption capacity, we characterized physical properties of the aged samples with Brunauer-Emmett-Teller (BET) nitrogen adsorption, X-ray diffraction (XRD), and high resolution scanning electron microscopy (SEM). The results showed no impact of aging on the aerogel microstructure or the silver nanoparticles in the aerogel, including their spatial distribution and morphology.
Matyas, Josef; Fryxell, Glen E.; Robinson, Matthew J.
Very large-scale structures in sintered silica aerogels as evidenced by atomic force microscopy and ultra-small angle
Very large-scale structures in sintered silica aerogels as evidenced by atomic force microscopy of silica aerogels has been extensively studied mainly by scattering techniques (neutrons, X-rays, light) and atomic force microscopy (AFM) experiments have been carried out on aerogels at dierent steps of densi
Demouchy, Sylvie
Mercury Binding Sites in Thiol-Functionalized Mesostructured Silica
Thiol-functionalized mesostructured silica with anhydrous compositions of (SiO{sub 2}){sub 1-x}(LSiO{sub 1.5}){sub x}, where L is a mercaptopropyl group and x is the fraction of functionalized framework silicon centers, are effective trapping agents for the removal of mercuric(II) ions from water. In the present work, we investigate the mercury-binding mechanism for representative thiol-functionalized mesostructures by atomic pair distribution function (PDF) analysis of synchrotron X-ray powder diffraction data and by Raman spectroscopy. The mesostructures with wormhole framework structures and compositions corresponding to x = 0.30 and 0.50 were prepared by direct assembly methods in the presence of a structure-directing amine porogen. PDF analyses of five mercury-loaded compositions with Hg/S ratios of 0.50-1.30 provided evidence for the bridging of thiolate sulfur atoms to two metal ion centers and the formation of chain structures on the pore surfaces. We find no evidence for Hg-O bonds and can rule out oxygen coordination of the mercury at greater than the 10% level. The relative intensities of the PDF peaks corresponding to Hg-S and Hg-Hg atomic pairs indicate that the mercury centers cluster on the functionalized surfaces by virtue of thiolate bridging, regardless of the overall mercury loading. However, the Raman results indicate that the complexation of mercury centers by thiolate depends on the mercury loading. At low mercury loadings (Hg/S {le} 0.5), the dominant species is an electrically neutral complex in which mercury most likely is tetrahedrally coordinated to bridging thiolate ligands, as in Hg(SBu{sup t}){sub 2}. At higher loadings (Hg/S 1.0-1.3), mercury complex cations predominate, as evidenced by the presence of charge-balancing anions (nitrate) on the surface. This cationic form of bound mercury is assigned a linear coordination to two bridging thiolate ligands.
Billinge, Simon J.L.; McKimmey, Emily J.; Shatnawi, Mouath; Kim, HyunJeong; Petkov, Valeri; Wermeille, Didier; Pinnavaia, Thomas J. (MSU); (CMU); (Iowa State)
Theoretical study of the light scattering from two alternating concentric double silica-gold nanoshell
The cross section of two alternating concentric double silica-gold nanoshell (DSGNS) is obtained as a function of wavelength. Numerical calculations show that two alternating concentric DSGNSs display two separated scattering peaks that the intensity and position of the scattering peaks depend on two gold shells thicknesses and silica layer thickness between them. By varying thicknesses of the layers of the gold shells, two alternating concentric DSGNS can be designed with the scattering peak from the visible to infrared regions of the spectrum.
Khosravi, H. [Department of Physics, Kermanshah Azad University, Kermanshah, 67189-97551 (Iran, Islamic Republic of); Daneshfar, N. [Department of Physics, Razi University, Kermanshah, 67149-67346 (Iran, Islamic Republic of); Bahari, A. [Department of Physics, Lorestan University, Lorestan, 68137-17133 (Iran, Islamic Republic of)
Permeability reduction of unconsolidated media due to stress-induced silica dissolution
Permeability measurements were made on both glass beads and Ottowa sand under uniform confining stress conditions. Extreme permeability reduction (95%) of the glass beads was observed at temperatures exceeding 150/sup 0/C and confining pressures of 13.8 MPa with distilled water as the flowing fluid. Permeability reduction in the Ottowa sand (40%) was also observed at high temperature and confining pressure. Effluent analysis revealed high concentrations of silica. Subsequent 300 hour experiments with Ottowa sand exhibited a steady decrease in permeability with time. SEM photographs of post experiment cores, indicate that the permeability reduction is mainly due to stress induced silica dissolution at grain contacts.
Udell, K.S.; Lofy, J.D.
Qrtzgeotherm: An ActiveX component for the quartz solubility geothermometer
An ActiveX component, QrtzGeotherm, to calculate temperature and vapor fraction in a geothermal reservoir using quartz solubility geothermometry was written in Visual Basic 6.0. Four quartz solubility equations along the liquid-vapor saturation curve: ... Keywords: ActiveX component, Computer program, QrtzGeotherm, QrtzGeothrm, Quartz geothermometry, Solubility equations, Visual Basic 6.0
Mahendra P. Verma
Multiphase and Multicomponent Materials
The microstructure of the adhered material consisted of oxide ligaments ( nanowires, NWs) that served to attach the debris to tool steel surface as revealed by�...
Silica-alumina trihydrate filled epoxy castings resistant to arced SF.sub.6
A cured, insulating, casting composition, having a coefficient of linear thermal expansion of below about 38 .times. 10.sup.-6 in./in./.degree. C and being resistant to arced sulfur hexafluoride gas, in contact with a metal surface in a sulfur hexafluoride gas environment, is made from hydantoin epoxy resin, anhydride curing agent and a filler combination of fused silica and alumina trihydrate.
Chenoweth, Terrence E. (Monroeville, PA); Yeoman, Frederick A. (Murrysville, PA)
Facile and sensitive epifluorescent silica nanoparticles for the rapid screening of EHEC
This study was to develop antibodies conjugated fluorescent dye-doped silica nanoparticles (FDS-NPs) aiming to increase signals for the rapid detection of Escherichia coli O157:H7 with glass slide method. The FDS-NPs were produced with microemulsion/solgel ...
Pravate Tuitemwong, Nut Songvorawit, Kooranee Tuitemwong
Effects of Surface Modification Conditions on Hydrophobicity of Silica-based Coating Additives
Superhydrophobic silica (SHS) powders are being evaluated as a potential additive to the polyurethane topcoats used in Chemical Agent Resistant Coating (CARC) systems, with the goal of improving water repellency and corrosion protection characteristics. The current generation of CARC topcoats is already highly loaded with solids, and thus there is a premium on minimization of the total SHS powder required to achieve the desired properties. Therefore, efficient surface modification of the silica and proper dispersion in the coating will be required. The effect of a dispersant on the surface modification of silica particles by chlorosilanes was addressed in this study. The properties of various SHS powders were characterized by thermogravimetric analysis and mass spectroscopy. Correlations between powder modification conditions and the ultimate effects of the modified particles on hydrophobicity of CARC topcoats were assessed. The use of contact and rolling angle measurements along with scanning electron microscopy are discussed as they pertain to the ability to quantify the effects of modified silicas on corrosion prevention coatings. Furthermore, a systematic approach to modifying and testing both powders and top coats of corrosion prevention systems is presented.
Armstrong, Beth L [ORNL; Pawel, Steven J [ORNL; Hunter, Scott Robert [ORNL; Haynes, James A [ORNL; Hillesheim, Daniel A [ORNL
TESLA-FEL 2004-01 Silica Aerogel Radiators for Bunch Length
TESLA-FEL 2004-01 Silica Aerogel Radiators for Bunch Length Measurements J. B¨ahr a , V. Djordjadze aerogel are used to measure the electron bunch length at the photo injector test facility at DESY Zeuthen by the usage of aerogel is calculated analytically and Monte Carlo simulations are performed. It is shown
Refractive index and density in F- and Cl-doped silica glasses
The refractive index and density of fluorine- and chlorine-doped silica glasses were measured as functions of fictive temperature. The halogen concentrations were observed to have a refractive index or density that is independent of the fictive temperature were found. This implies that these properties are not affected by any heat-treatment conditions.
Kakiuchida, Hiroshi; Shimodaira, Noriaki; Sekiya, Edson H.; Saito, Kazuya; Ikushima, Akira J. [Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya, Aichi 468-8511 (Japan); Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya, Aichi 468-8511, Japan and Research Center, Asahi Glass Co., Ltd., 1150 Hazawa-cho, Kanagawa, Yokohama, Kanagawa 221-8755 (Japan); Research Center for Advanced Photon Technology, Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya, Aichi 468-8511 (Japan)
Silica control and materials tests at the Salton Sea geothermal field
The Lawrence Livermore Laboratory maintains and operates a test facility near Niland, California, in the Imperial Valley for field studies on SSGF brine chemistry, scale and solids control, materials, and injection. Recent work in silica control and materials testing is reviewed.
Quong, R.; Harrar, J.E.; McCright, R.D.; Locke, R.D.; Lorensen, L.E.; Tardiff, G.E.
Coupling of Advanced Oxidation and Adsorption Processes onto Silica-Titania Composites for Low Level
was mercury adsorption onto calcium sulfate (CaSO4), a byproduct of the flue gas desulfurization (FGD) wet., Powers K.W., and Pitoniak E.R. (2004) Method for Purifying Flue Gases from Combustion Sources. PatentCoupling of Advanced Oxidation and Adsorption Processes onto Silica-Titania Composites for Low
Choate, Paul M.
Lithium/V6O13 cells using silica nanoparticle-based composite electrolyte
Lithium/V6O13 cells using silica nanoparticle-based composite electrolyte Yangxing Li, Peter S) both in liquid electrolyte consisting of oligomeric poly(ethyleneglycol)dimethylether'/lithium bis of suppressing lithium dendrite growth due to the rigidity and immobility of the electrolyte structure
Khan, Saad A.
Inhibition of Lithium Dendrites by Fumed Silica-Based Composite Electrolytes
Inhibition of Lithium Dendrites by Fumed Silica-Based Composite Electrolytes Xiang-Wu Zhang State University, Raleigh, North Carolina 27695-7905, USA Lithium dendrite formation is investigated via in situ microscopy in a liquid electrolyte containing polyethylene glycol dimethyl ether lithium bis
Determination of silica scale deposition rates and thresholds applied toward protection of injection reservoirs. Quarterly progress report, July 1--September 30, 1998
The program objective aims to identify the highest temperature at which silica scale will develop from partially evaporated and significantly cooled geothermal liquid. The approach involves tracking deposition of silica scale by monitoring the apparent electrical conductivity of the geothermal liquid in an isolation chamber. A decrease in apparent conductivity occurs because silica deposited on electrode surfaces is less conductive than the geothermal liquid. The major technical hurdle is building a conductivity monitoring system that is sensitive enough to distinguish between no silica deposition and almost no silica deposition, while accounting for other factors which also affect conductivity, such as temperature and varying fluid composition.
Determination of silica scale deposition rates and thresholds applied toward protection of injection reservoirs. Quarterly progress report, January 1, 1988--March 31, 1998
The program objective aims to identify the highest temperature at which silica scale will develop from partially evaporated and significantly cooled geothermal liquid. The approach involves tracking deposition of silica scale by monitoring the apparent electrical conductivity of the geothermal liquid in an isolation chamber. A decrease in apparent conductivity occurs because the deposited silica is less conductive than the geothermal liquid. The major technical hurdle is building a conductivity monitoring system that is sensitive enough to distinguish between no silica deposition and almost no silica deposition, while accounting for other factors which also affect conductivity, such as temperature and varying fluid composition.
Determination of silica scale deposition rates and thresholds applied toward protection of injection reservoirs. Quarterly progress report, April 1--June 30, 1998
This report describes the results made in fulfillment of contract DE-FG26-02NT15451, ''Multicomponent Seismic Analysis and Calibration to Improve Recovery from Algal Mounds: Application to the Roadrunner/Towaoc Area of the Paradox Basin, Ute Mountain Ute Reservation, Colorado'', for the Second Biennial Report covering the time period May 1, 2003 through October 31, 2003. During this period, the project achieved two significant objectives: completion of the acquisition and processing design and specifications 3D9C seismic acquisition and the 3D VSP log; and completion of the permitting process involving State, Tribal and Federal authorities. Successful completion of these two major milestones pave the way for field acquisition as soon as weather permits in the Spring of 2004. This report primarily describes the design and specifications for the VSP and 3D9C surveys.
Paul La Pointe; Claudia Rebne; Steve Dobbs
Extreme Chromatography: Faster, Hotter, SmallerChapter 5 High-efficiency Liquid Chromatography Separations Achieved by Monolithic Silica Columns
Extreme Chromatography: Faster, Hotter, Smaller Chapter 5 High-efficiency Liquid Chromatography Separations Achieved by Monolithic Silica Columns Methods and Analyses eChapters Methods - Analyses Books AOCS Press Downloada
Interstitial BiO molecule as a center of broadband IR luminescence in bismuth-doped silica glass
IR luminescence and absorption in bismuth-doped silica glass-core fibers observed recently (see [arXiv:1106.2969v1 [physics.optics]) are argued to be caused by transitions in interstitial BiO molecules
Sokolov, V O; Dianov, E M
Flow cytometric analysis of respiratory tract cells exposed to oil shale and silica particulates. [Hamsters
Flow cytometric techniques were used to measure the cytological and biochemical damage to respiratory tract cells in animals exposed to particulates. Hamsters were exposed to raw and spent oil shale particulates and silica by intratracheal instillation. Exfoliated lung cells were obtained by sacrificing the animals and lavaging the respiratory tract posterior to the trachea with saline. Cell samples were fixed in ethanol and stained with mithramycin for fluorescence analysis of DNA content. DNA content distributions from hamsters exposed to spent oil shale and silica particulates showed atypical changes 28 to 35 days later. Cell counts and total numbers of macrophages, leukocytes, and epithelial cells in the lavage fluid also showed marked changes related to time after exposure.
Steinkamp, J.A.; Wilson, J.S.
Petrography study on altered flint aggregate by alkali-silica reaction
The aim of our study is to improve our understanding of an alkali-silica reaction (ASR) via petrography. We used a chemical concrete subsystem: flint aggregate, portlandite and KOH. The altered flint aggregate is followed by optical microscopy and scanning electron microscopy (SEM) before and after acid treatment at different intervals. After acid treatment, the observations showed an increase in aggregate porosity and revealed internal degradation of the aggregate. This degradation created amorphous zones. Before acid treatment, the analyses on polished sections by scanning electron microscopy coupled with energy dispersive spectroscopy (EDS) enabled visualization of K{sup +} and Ca{sup 2+} penetration into the aggregate. The appearance of amorphous zones and penetration of positive ions into the aggregate are correlated with the increase in the molar fraction of silanol sites. This degradation is specific to the alkali-silica reaction.
Bulteel, D. [Departement Genie Civil de l'Ecole Nationale Superieure des Techniques Industrielles et des Mines de Douai, 941 rue Charles Bourseul, B.P. 838, F-59508, DOUAI Cedex (France)]. E-mail: firstname.lastname@example.com; Rafai, N. [Laboratoire d'Etude et de Recherches des Materiaux a Arles, F-13631 ARLES (France); Degrugilliers, P. [Departement Genie Civil de l'Ecole Nationale Superieure des Techniques Industrielles et des Mines de Douai, 941 rue Charles Bourseul, B.P. 838, F-59508, DOUAI Cedex (France); Garcia-Diaz, E. [Departement Genie Civil de l'Ecole Nationale Superieure des Techniques Industrielles et des Mines de Douai, 941 rue Charles Bourseul, B.P. 838, F-59508, DOUAI Cedex (France)
Study of a Threshold Cherenkov Counter Based on Silica Aerogels with Low Refractive Indices ?
To identify ? � and K � in the region of 1.0 ? 2.5 GeV/c, a threshold Cherenkov counter equipped with silica aerogels has been investigated. Silica aerogels with a low refractive index of 1.013 have been successfully produced using a new technique. By making use of these aerogels as radiators, we have constructed a Cherenkov counter and have checked its properties in a test beam. The obtained results have demonstrated that our aerogel was transparent enough to make up for loss of the Cherenkov photon yield due to a low refractive index. Various configurations for the photon collection system and some types of photomultipliers, such as the fine-mesh type, for a read out were also tested. From these studies, our design of a Cherenkov counter dedicated to ?/K separation up to a few GeV/c with an efficiency greater than 90 % was considered. 1
I. Adachi; T. Sumiyoshi; K. Hayashi; N. Iida; R. Enomoto; K. Tsukada; R. Suda; S. Matsumoto; K. Natori; M. Yokoyama; H. Yokogawa
Mesoporous silica film from a solution containing a surfactant and methods of making same
The present invention is a mesoporous silica film having a low dielectric constant and method of making having the steps of combining a surfactant in a silica precursor solution, spin-coating a film from this solution mixture, forming a partially hydroxylated mesoporous film, and dehydroxylating the hydroxylated film to obtain the mesoporous film. It is advantageous that the small polyoxyethylene ether surfactants used in spin-coated films as described in the present invention will result in fine pores smaller on average than about 20 nm. The resulting mesoporous film has a dielectric constant less than 3, which is stable in moist air with a specific humidity. The present invention provides a method for superior control of film thickness and thickness uniformity over a coated wafer, and films with low dielectric constant.
Liu, Jun (West Richland, WA); Domansky, Karel (Cambridge, MA); Li, Xiaohong (Richland, WA); Fryxell, Glen E. (Kennewick, WA); Baskaran, Suresh (Kennewick, WA); Kohler, Nathan J. (Richland, WA); Thevuthasan, Suntharampillai (Kennewick, WA); Coyle, Christopher A. (Richland, WA); Birnbaum, Jerome C. (Richland, WA)
Modified Murnaghan equation of state applied to shock compression of silica, basalt, and dolomite
An equation of state previously used by the author is developed further and applied to geologic media. The equation is of the same form as the Murnaghan equation of state, but with the elastic constant terms replaced by the cohesive energy density (internal pressure), and the exponential term given as a sum of the Gruneisen parameter and the gaseous adiabatic exponent. Data for shock compression of silica, basalt, and dolomite are analyzed according to the equation.
Rogers, L.A.
A New Concept for the Fabrication of Hydrogen Selective Silica Membranes
We are attempting to fabricate H{sub 2}-selective silica-based films by ''layer-by-layer'' deposition as a new approach for thin films. A sonication-assisted deposition method was mainly used for ''layer-by-layer'' deposition. In addition, other approaches such as a dip-coating and the use of a polymer matrix with a layered silicate were contrived as well. This report shows the progress done during the 2nd Year of this award.
Michael Tsapatsis
Sulfate Fining Chemistry in Oxidized and Reduced Soda-Lime-Silica Glasses
Various reducing agents were used and their additions were varied to (1) increase glass quality through eliminating defects from silica scum, (2) decrease SOx emissions through changing the kind and quantity of reducing agents, and (3) improve production efficiency through increased flexibility of glass redox control during continuous processing. The work included measuring silica sand dissolution and sulfate decomposition in melts from glass batches. Glass batches were heated at a temperature-increase rate deemed similar to that experienced in the melting furnace. The sulfate decomposition kinetics was investigated with thermogravimetric analysis-differential thermal analysis and evolved gas analysis. Sulfur concentrations in glasses quenched at different temperatures were determined using X-ray fluorescence spectroscopy. The distribution of residual sand (that which was not dissolved during the initial batch reactions) in the glass was obtained as a function of temperature with optical microscopy in thin-sections of melts. The fraction of undissolved sand was measured with X-ray diffraction. The results of the present study helped Visteon Inc. reduce the energy consumption and establish the batch containing 0.118 mass% of graphite as the best candidate for Visteon glass production. The improved glass batch has a lower potential for silica scum formation and for brown fault occurrence in the final glass product. It was established that bubbles trapped in the melt even at 1450 C have a high probability to be refined when reaching the hot zone in the glass furnace. Furthermore, silica sand does not accumulate at the glass surface and dissolves faster in the batch with graphite than in the batch with carbocite.
Matyas, Josef; Hrma, Pavel R.
The Role of High Calcium Fly Ashes in Controlling Alkali-Silica Reactions in Concrete
The alkali-silica reaction (ASR) is a deleterious chemical reaction that can result in the deterioration of concrete structures. This report builds upon the results of a research and development study, funded by a broadly-based multi-national industry consortium, that is developing an engineering database on the long-term effectiveness of Class F fly ash and other supplementary cementing materials (SCMs) in counteracting ASR in concrete.
In-depth survey report of silica flour dust during packing, transfer, and shipping at the Central Silica Company, Glass Rock Plant, Glass Rock, Ohio
A visit was made to the Central Silica Company, Glass Rock, Ohio to evaluate methods used to control employee exposure to silica dust. The control methods at this company included careful handling and transfer of damp materials, exhaust ventilation, good housekeeping procedures, and the use of respiratory protection. Evaluations were made of the packing area, transfer point, inside loading trucks, and ambient air at sections of the flour building. Control systems included a good exhaust-ventilation system and four ventilation hoods. Evaluations were made of samples collected by an MSA gravimeter dust sampler, the Del High volume electrostatic precipitation, and bulk and rafter samples. Dust control methods appeared to be effective due to the existence of good engineering controls, good work practices, and an effective respiratory protection program. Additional control measures included the handling of the ore as a damp material, thus reducing the generation of dust particles. Outside dust sources were being reduced. Most of the product was shipped in bulk. Plastic wrapping was used around pallet loads to reduce bag breakage and dust dispersion. A filtered air system controlled low dust levels in the Pebble Mill control room. Enclosed screens operated under negative pressure separated fine from coarse product at the process building.
Caplan, P.E.; Reed, L.D.; Amendola, A.A.; Cooper, T.C.
On the calculation of equilibrium thermodynamic properties and the establishment of statistical-thermodynamically-consistent finite bound-state partition functions in nonideal multicomponent plasma mixtures within the chemical model
The problem of the calculation of equilibrium thermodynamic properties and the establishment of statistical-thermodynamically consistent finite bound-state partition functions in nonideal multicomponent plasma systems is revised within the chemical picture. The present exploration accompanied by the introduction of a generalized consistent formulation, in terms of the solution of the inverse problem, clears ambiguities and gives a better understanding of the problem on top of pointing out weaknesses and inaccuracies/inconsistencies buried in widely used models in literature.
Zaghloul, Mofreh R. [Department of Physics, College of Sciences, United Arab Emirates University, Al-Ain, 177551 (United Arab Emirates)
Multiscale Filler Structure in Simplified Industrial Nanocomposite Silica/SBR Systems Studied by SAXS and TEM
Simplified silica (Zeosil 1165 MP) and SBR (140k carrying silanol end-groups) nanocomposites have been formulated by mixing of a reduced number of ingredients with respect to industrial applications. The thermo-mechanical history of the samples during the mixing process was monitored and adjusted to identical final temperatures. The filler structure on large scales up to micrometers was studied by transmission electron microscopy (TEM) and very small-angle X-ray scattering (SAXS). A complete quantitative model extending from the primary silica nanoparticle (of radius \\approx 10 nm), to nanoparticles aggregates, up to micrometer-sized branches with typical lateral dimension of 150 nm is proposed. Image analysis of the TEM-pictures yields the fraction of zones of pure polymer, which extend between the branches of a large-scale filler network. This network is compatible with a fractal of average dimension 2.4 as measured by scattering. On smaller length scales, inside the branches, small silica aggregates are present. Their average radius has been deduced from a Kratky analysis, and it ranges between 35 and 40 nm for all silica fractions investigated here (\\phi_si = 8-21% vol.). A central piece of our analysis is the description of the interaggregate interaction by a simulated structure factor for polydisperse spheres representing aggregates. A polydispersity of 30% in aggregate size is assumed, and interactions between these aggregates are described with a hard core repulsive potential. The same distribution in size is used to evaluate the polydisperse form factor. Comparison with the experimental intensity leads to the determination of the average aggregate compacity (assumed identical for all aggregates in the distribution, between 31% and 38% depending on \\phi_si), and thus aggregation number (ca. 45, with a large spread). Because of the effect of aggregate compacity and of pure polymer zones, the volume fraction of aggregates is higher in the branches than \\phi_si. The repulsion between aggregates has a strong effect on the apparent isothermal compressibility: it leads to a characteristic low-q depression, which cannot be interpreted as aggregate mass decrease in our data. In addition, the reinforcement effect of these silica structures in the SBR-matrix is characterized with oscillatory shear and described with a model based on the same aggregate compacity. Finally, our results show that it is possible to analyze the complex structure of interacting aggregates in nanocomposites of industrial origin in a self-consistent and quantitative manner.
Guilhem Baeza; ANNE-CAROLINE GENIX; Christophe Degrandcourt; Laurent Petitjean; J�r�mie Gummel; Marc Couty; Julian OBERDISSE
Geochemical studies at four northern Nevada hot spring areas. [Kyle Hot Springs, Leach Hot Springs, Buffalo Hot Springs, and Beowave Hot Springs
Water samples from both hot and cold sources in the hydrologic areas surrounding the hot springs were collected and analyzed. Analyses of major, trace, and radio-element abundances of the water samples and of associated rock samples are presented. From this study it is possible that trace- and major-element abundances and/or ratios may be discerned which are diagnostic as chemical geothermometers, complementing those of silica and alkali elements that are presently used. Brief discussions of mixing calculations, possible new chemical geothermometers, and interelement relationships are also included.
Wollenberg, H.; Bowman, H.; Asaro, F.
COMMIX-PPC: A three-dimensional transient multicomponent computer program for analyzing performance of power plant condensers. Volume 1, Equations and numerics
The COMMIX-PPC computer pregrain is an extended and improved version of earlier COMMIX codes and is specifically designed for evaluating the thermal performance of power plant condensers. The COMMIX codes are general-purpose computer programs for the analysis of fluid flow and heat transfer in complex Industrial systems. In COMMIX-PPC, two major features have been added to previously published COMMIX codes. One feature is the incorporation of one-dimensional equations of conservation of mass, momentum, and energy on the tube stile and the proper accounting for the thermal interaction between shell and tube side through the porous-medium approach. The other added feature is the extension of the three-dimensional conservation equations for shell-side flow to treat the flow of a multicomponent medium. COMMIX-PPC is designed to perform steady-state and transient. Three-dimensional analysis of fluid flow with heat transfer tn a power plant condenser. However, the code is designed in a generalized fashion so that, with some modification, it can be used to analyze processes in any heat exchanger or other single-phase engineering applications. Volume I (Equations and Numerics) of this report describes in detail the basic equations, formulation, solution procedures, and models for a phenomena. Volume II (User`s Guide and Manual) contains the input instruction, flow charts, sample problems, and descriptions of available options and boundary conditions.
Multicomponent Seismic Analysis and Calibration to Improve Recovery from Algal Mounds: Application to the Roadrunner/Towaoc area of the Paradox Basin, UTE Mountain UTE Reservation, Colorado
The goals of this project were: (1) To enhance recovery of oil contained within algal mounds on the Ute Mountain Ute tribal lands. (2) To promote the use of advanced technology and expand the technical capability of the Native American Oil production corporations by direct assistance in the current project and dissemination of technology to other Tribes. (3) To develop an understanding of multicomponent seismic data as it relates to the variations in permeability and porosity of algal mounds, as well as lateral facies variations, for use in both reservoir development and exploration. (4) To identify any undiscovered algal mounds for field-extension within the area of seismic coverage. (5) To evaluate the potential for applying CO{sub 2} floods, steam floods, water floods or other secondary or tertiary recovery processes to increase production. The technical work scope was carried out by: (1) Acquiring multicomponent seismic data over the project area; (2) Processing and reprocessing the multicomponent data to extract as much geological and engineering data as possible within the budget and time-frame of the project; (3) Preparing maps and data volumes of geological and engineering data based on the multicomponent seismic and well data; (4) Selecting drilling targets if warranted by the seismic interpretation; (5) Constructing a static reservoir model of the project area; and (6) Constructing a dynamic history-matched simulation model from the static model. The original project scope covered a 6 mi{sup 2} (15.6 km{sup 2}) area encompassing two algal mound fields (Towaoc and Roadrunner). 3D3C seismic data was to acquired over this area to delineate mound complexes and image internal reservoir properties such as porosity and fluid saturations. After the project began, the Red Willow Production Company, a project partner and fully-owned company of the Southern Ute Tribe, contributed additional money to upgrade the survey to a nine-component (3D9C) survey. The purpose of this upgrade to nine components was to provide additional shear wave component data that might prove useful in delineating internal mound reservoir attributes. Also, Red Willow extended the P-wave portion of the survey to the northwest of the original 6 mi{sup 2} (15.6 km{sup 2}) 3D9C area in order to extend coverage further to the northwest to the Marble Wash area. In order to accomplish this scope of work, 3D9C seismic data set covering two known reservoirs was acquired and processed. Three-dimensional, zero-offset vertical seismic profile (VSP) data was acquired to determine the shear wave velocities for processing the sh3Dseismic data. Anisotropic velocity, and azimuthal AVO processing was carried out in addition to the conventional 3D P-wave data processing. All P-, PS- and S-wave volumes of the seismic data were interpreted to map the seismic response. The interpretation consisted of conventional cross-plots of seismic attributes vs. geological and reservoir engineering data, as well as multivariate and neural net analyses to assess whether additional resolution on exploration and engineering parameters could be achieved through the combined use of several seismic variables. Engineering data in the two reservoirs was used to develop a combined lithology, structure and permeability map. On the basis of the seismic data, a well was drilled into the northern mound trend in the project area. This well, Roadrunner No.9-2, was brought into production in late April 2006 and continues to produce modest amounts of oil and gas. As of the end of August 2007, the well has produced approximately 12,000 barrels of oil and 32,000 mcf of gas. A static reservoir model was created from the seismic data interpretations and well data. The seismic data was tied to various markers identified in the well logs, which in turn were related to lithostratigraphy. The tops and thicknesses of the various units were extrapolated from well control based upon the seismic data that was calibrated to the well picks. The reservoir engineering properties were available from a number of wel
Joe Hachey
Quartz dissolution and silica deposition in hot-dry-rock geothermal systems
The kinetics of quartz dissolution control the produced fluid dissolved silica concentration in geothermal systems in which the downhole residence time is finite. The produced fluid of the Phase I, Run Segment 5 experimental Hot Dry Rock (HDR) geothermal system at Fenton Hill, NM, was undersaturated with respect to quartz in one pass through the reservoir, suggesting that the rate of granite dissolution governed the outlet dissolved silica concentration in this system. The literature data for the rate of quartz dissolution in water from 65 to 625/sup 0/C is correlated using an empirical rate law which is first order in quartz surface area and degree of undersaturation of the fluid. The Arrhenius plot (ln k vs T/sup -1/) is linear over eight orders of magnitude of the rate constant, verifying the validity of the proposed rate expression. Carefully performed quartz dissolution experiments in the present study duplicated the literature data and completed the data base in the temperature range from 150 to 250/sup 0/C. Identical experiments using crushed granite indicate that the rate of quartz dissolution in the presence of granite could be as much as 1 to 2 orders of magnitude faster than the rates observed in the pure quartz experiments. A temperature dependent HDR reservoir model incorporates the quartz dissolution rate law to simulate the dissolved silica behavior during the Fenton Hill Run Segment 5 experiment. For this low-permeability, fracture-dominated reservoir, the assumptions of one-dimensional plug flow through a vertically-inclined rectangular fracture and one-dimensional rock heat conduction perpendicular to the direction of flow are employed. These simplifications lead to an analytical solution for the temperature field in the reservoir.
Robinson, B.A.
Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) technology of mercury removal and stabilization
This paper explains the technology developed to produce Self-Assembled Mercaptan on Mesoporous Silica (SAMMS) for mercury removal from aqueous wastewater and from organic wastes. The characteristics of SAMMS materials, including physical characteristics and mercury loading, and its application for mercury removal and stabilization are discussed. Binding kinetics and binding speciations are reported. Preliminary cost estimates are provided for producing SAMMS materials and for mercury removal from wastewater. The characteristics of SAMMS in mercury separation were studied at PNNL using simulated aqueous tank wastes and actual tritiated pump oil wastes from Savannah River Site; preliminary results are outlined. 47 refs., 16 figs., 16 tabs.
Feng, Xiangdong; Liu, Jun; Fryxell, G.E. [and others
Mesoporous Silica Nanomaterials for Applications in Catalysis, Sensing, Drug Delivery and Gene Transfection
The central theme of this dissertation is represented by the versatility of mesoporous silica nanomaterials in various applications such as catalysis and bio-applications, with main focus on biological applications of Mesoporous Silica Nanospheres (MSN). The metamorphosis that we impose to these materials from catalysis to sensing and to drug and gene delivery is detailed in this dissertation. First, we developed a synthetic method that can fine tune the amount of chemically accessible organic functional groups on the pores surface of MSN by exploiting electrostatic and size matching between the cationic alkylammonium head group of the cetyltrimethylammonium bromide (CTAB) surfactant and various anionic organoalkoxysilane precursors at the micelle-water interface in a base-catalyzed condensation reaction of silicate. Aiming nature imitation, we demonstrated the catalytic abilities of the MSNs, We utilized an ethylenediamine functional group for chelating Cu{sup 2+} as a catalytic functional group anchored inside the mesopores. Thus, a polyalkynylene-based conducting polymer (molecular wire) was synthesized within the Cu-functionalized MSNs silica catalyst. For sensing applications, we have synthesized a poly(lactic acid) coated mesoporous silica nanosphere (PLA-MSN) material that serves as a fluorescence sensor system for detection of amino-containing neurotransmitters in neutral aqueous buffer. We exploited the mesoporosity of MSNs for encapsulating pharmaceutical drugs. We examined bio-friendly capping molecules such as polyamidoamine dendrimers of generations G2 to G4, to prevent the drug leaching. Next, the drug delivery system employed MSNs loaded with Doxorubicin, an anticancer drug. The results demonstrated that these nano-Trojan horses have ability to deliver Doxorubicin to cancer cells and induce their death. Finally, to demonstrate the potential of MSN as an universal cellular transmembrane nanovehicle, we anchored positively charged dendrimers on the surface of MSN and utilize them to complex cationic DNA. The p-EGFP-CI gene-coated MSN nanocomposite was able to transfect cancer cell lines, such as human HeLa and CHO cancer cell lines. The gene carrier ability of MSNs was further proved by transfecting primary cells and cotransfecting of two different genes in cancer cell lines. In sum, MSN are versatile partners in several types of applications.
Daniela Rodica Radu
Acidity and catalytic activity of zeolite catalysts bound with silica and alumina
Zeolites ZSM-5 (SiO2/Al2O3=30~280) and Y(SiO2/Al2O3=5.2~80) are bound with silica gel (Ludox HS-40 and Ludox AS-40) and alumina (?- Al2O3 and boehmite) by different binding methods, namely, gel-mixing, powder-mixing and powder-wet-mixing methods. The acidities of the bound catalysts and the zeolite powder are determined by NH3-TPD and FTIR. The textures of these catalysts are analyzed on a BET machine with nitrogen as a probe molecule. The micropore surface area and micropore volume are determined by t-plot method. Micropore volume distribution is determined by Horvath-Kawazoe approach with a cylindrical pore model. Mesopore volume distribution is determined by BJH method from the nitrogen desorption isotherm. Silica from the binder may react with extra-framework alumina in zeolites to form a new protonic acid. SiO2-bound catalysts have less strong acidity, Bronsted acidity and Lewis acidity than the zeolite powder. Also, the strength of strong acid sites of the zeolites is reduced when silica is embedded. Micropore surface area and micropore volume are reduced by about 19% and 18%, respectively, indicating some micropores of ZSM-5 are blocked on binding with silica. SiO2-bound ZSM-5 catalysts have less catalytic activity for butane transformation (cracking and disproportionation) and ethylene oligomerization than ZSM-5 powder. When alumina is used as a binder, both the total acid sites and Lewis acid sites are increased. Micropore surface area and micropore volume of ZSM-5 powder are reduced by 26% and 23%, respectively, indicating some micropores of ZSM-5 are blocked by the alumina binder. Alumina-bound catalysts showed a lower activity for butane transformation and ethylene oligomerization than ZSM-5 powder. Alkaline metals content in the binder is a crucial factor that influences the acidity of a bound catalyst. The metal cations neutralize more selectively Bronsted acid sites than Lewis acid sites. Alkaline metal cations in the binder and micropore blockage cause the bound catalysts to have a lower catalytic activity than the zeolite powder.
Wu, Xianchun
Silica Deposition in Field and Laboratory Thermal Tests of Yucca Mountain Tuff
A field thermal test was conducted by the Yucca Mountain Site Characterization Project to observe changes in the Topopah Spring Tuff middle nonlithophysal zone geohydrologic system due to thermal loading. A laboratory-scale crushed-tuff hydrothermal column test was used to investigate the tuff as a potential construction material within a nuclear-waste repository. Results of similar column tests have been cited as indications that silica deposition would plug the rock fractures above a repository and create unfavorable drainage conditions. Data from field and laboratory tests are used here to predict the magnitude of fracture sealing. For the crushed-tuff column test, a one-meter-high column was packed with crushed tuff to a porosity of about 50%. Water filling the lowermost 10 cm of the column was boiled and the vapor condensed at the top of the column, percolating down to the boiling zone. After 100 days, intergranular pore space in the saturated portion of the column was almost filled with amorphous silica. The Drift Scale Test at Yucca Mountain is a heating test in the unsaturated zone. It consists of a four-year heating phase, now complete, followed by a four-year cooling phase. Heaters in a 60-m-long drift and in the adjacent rock have heated the drift walls to 200 C. As the rock was heated, fluids naturally present in the rock migrated away from the heat sources. A boiling zone now separates an inner dry-out zone from an outer condensation zone. A heat-pipe region exists in the outer margin of the boiling zone above the heated drift. Amorphous silica coatings up to a few micrometers thick were deposited in this region. Deposits were observed in less than 10% of the fractures in the heat pipe region. Drift-scale test results yield a silica deposition rate of about 250 {micro}m/1000 years in 10% of the fractures in the heat-pipe region. We did not calculate deposition rates from our column test, but a rate of 9.1 mm/1000 years in all fractures of the heat-pipe region is predicted by Sun and Rimstidt (2002) from the results of a similar test. We believe the rate based on field-test observations is a better prediction because the field test more closely resembles the expected environment in a repository. Rates based on column-test results may be reasonable for local zones of preferred fluid flow.
S.S. Levy; S.J. Chipera; M.G. Snow
Femtosecond laser pulse filamentation under anomalous dispersion in fused silica. Part 1. Numerical investigation
We report the results of investigation of femtosecond laser pulse filamentation in fused silica by varying the wavelength in the range from 800 to 2300 nm. It is shown that in the case of the anomalous group-velocity dispersion, a sequence of 'light bullets' with a high spatial and temporal localisation of the light field is formed along the filament. The relation of the formation and propagation of light bullets with the formation of an isolated anti-Stokes wing of the supercontinuum spectrum is established. (nonlinear optical phenomena)
Smetanina, E O; Kompanets, V O; Chekalin, Sergei V; Kandidov, V P
Atomic structure of Au-nanoparticles on silica support by X-ray PDF study
We investigated the atomic structure of gold nanoparticles with an average size of 5 nm in diameter, supported by silica. We used high-energy X-ray diffraction and the atomic pair distribution function (PDF) to probe the local atomic structure. Measurements were performed from 25 to 950 C. The structure is approximately fcc in average but exhibits small distortions. The structural distortion increases with the temperature and could be related to the catalytic activity of gold nanoparticles. Above 425 C, rapid particle growth and coalescence were observed.
Dmowski, W. [University of Tennessee, Knoxville (UTK); Yin, Hongfeng [ORNL; Dai, Sheng [ORNL; Overbury, Steven {Steve} H [ORNL; Egami, T. [University of Tennessee, Knoxville (UTK)
Atomic Structure of Au Nanoparticles on a Silica Support by an X-ray PDF Study
We investigated the atomic structure of gold nanoparticles with an average size of {approx}5 nm in diameter, supported by silica. We used high-energy X-ray diffraction and the atomic pair distribution function (PDF) to probe the local atomic structure. Measurements were performed from 25 to 950 C. The structure is approximately fcc in average but exhibits small distortions. The structural distortion increases with the temperature and could be related to the catalytic activity of gold nanoparticles. Above 425 C, rapid particle growth and coalescence were observed.
Dmowski, Wojtek; Yin, Hongfeng; Dai, Sheng; Overbury, Steven H.; Egami, Takeshi (Tennessee-K); (ORNL)
Characterization of the polymer-filler interface in (gamma)-irradiated silica-reinforced polysiloxane composites
The changes in hydrogen bonding at the interface of silica-reinforced polysiloxane composites due to aging in gamma radiation environments were examined in this study. Solvent swelling was utilized to determine the individual contributions of the matrix polymer and polymer-filler interactions to the overall crosslink density. The results show how the polymer-filler hydrogen bonding dominates the overall crosslink density of the material. Air irradiated samples displayed decreased hydrogen bonding at the polymer-filler interface, while vacuum irradiation revealed the opposite effect.
Chien, A T; Balazs, B; LeMay, J
Comparison of artificial neural network and fuzzy logic models for prediction of long-term compressive strength of silica fume concrete
In this study, an artificial neural network (ANN) and fuzzy logic (FL) study were developed to predict the compressive strength of silica fume concrete. A data set of a laboratory work, in which a total of 48 concretes were produced, was utilized in ... Keywords: Compressive strength, Concrete, Fuzzy logic, Neural networks, Silica fume
Fatih �zcan; Cengiz D. Ati?; Okan Karahan; Erdal Uncuo?lu; Harun Tanyildizi
Highly ordered Zn-doped mesoporous silica: An efficient catalyst for transesterification reaction
Designing highly ordered material with nanoscale periodicity is of great significance in the field of solid state chemistry. Herein, we report the synthesis of highly ordered 2D-hexagonal mesoporous zinc-doped silica using a mixture of anionic and cationic surfactants under hydrothermal conditions. Powder XRD, N{sub 2} sorption, TEM analysis revealed highly ordered 2D-hexagonal arrangements of the pores with very good surface area (762 m{sup 2} g{sup -1}) in this Zn-rich mesoporous material. Chemical analysis shows very high loading of zinc (ca. 12.0 wt%) in the material together with retention of hexagonal pore structure. Interestingly, high temperature calcination resulted into zinc silicate phase, unlike any ZnO phase, which otherwise is expected under heat treatments. High surface area together with Zn loading in this mesoporous material has been found useful for the catalytic activity of the materials in the acid-catalyzed transesterification reactions of various esters under mild liquid phase conditions. - Graphical abstract: Zn-rich 2D-hexagonal mesoporous materials are synthesized hydrothermally, which show very good catalytic activity in the transesterification reaction under mild liquid phase reaction conditions. Highlights: > Zn-rich 2D-hexagonal mesoporous silica. > High surface area material. > Efficient catalyst in liquid phase transesterification reaction. > Biodiesel production.
Pal, Nabanita; Paul, Manidipa [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Bhaumik, Asim, E-mail: firstname.lastname@example.com [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)
Power scaling analysis of fiber lasers and amplifiers based on non-silica materials
A developed formalism for analyzing the power scaling of diffraction limited fiber lasers and amplifiers is applied to a wider range of materials. Limits considered include thermal rupture, thermal lensing, melting of the core, stimulated Raman scattering, stimulated Brillouin scattering, optical damage, bend induced limits on core diameter and limits to coupling of pump diode light into the fiber. For conventional fiber lasers based upon silica, the single aperture, diffraction limited power limit was found to be 36.6kW. This is a hard upper limit that results from an interaction of the stimulated Raman scattering with thermal lensing. This result is dependent only upon physical constants of the material and is independent of the core diameter or fiber length. Other materials will have different results both in terms of ultimate power out and which of the many limits is the determining factor in the results. Materials considered include silica doped with Tm and Er, YAG and YAG based ceramics and Yb doped phosphate glass. Pros and cons of the various materials and their current state of development will be assessed. In particular the impact of excess background loss on laser efficiency is discussed.
Dawson, J W; Messerly, M J; Heebner, J E; Pax, P H; Sridharan, A K; Bullington, A L; Beach, R J; Siders, C W; Barty, C P; Dubinskii, M
Highly ordered magnetic mesoporous silicas for effective elimination of carbon monoxide
Catalysts based on crystalline nanoparticles of Fe metal supported on mesoporous silica have been developed. The synthetic process involves hydrogen reduction processing for high abundant Fe metal nanoparticles within the mesopores, in which impregnated Fe salt in the inner nanopores of mesoporous silica is thermally treated under hydrogen at 500 Degree-Sign C. Detailed characterization was achieved by XRD, XPS, BET, and HR-TEM techniques. The catalytic efficiency was demonstrated as a function of the used amounts and reaction time. The results show that more than 90% of the carbon monoxide was eliminated at room temperature during a period 80 min with 0.5 g of catalyst. - Graphical abstract: Strategy for the preparation of highly abundant Fe nanoparticle embedded MS catalyst by hydrogen reduction process and HR-TEM images of cross-sectional and top view. Highlights: Black-Right-Pointing-Pointer MS based heterogeneous catalyst with Fe nanoparticles were demonstrated for CO elimination. Black-Right-Pointing-Pointer Highly Fe nanoparticle embedded MS catalyst prepared by hydrogen reduction process. Black-Right-Pointing-Pointer Systematic characterization was achieved by XRD, XPS, BET, and HR-TEM analyses. Black-Right-Pointing-Pointer More than 90% of the CO was eliminated at RT during 80 min with 0.5 g of catalyst.
Lee, Jiho [Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of); Department of Chemistry, Inha University, Incheon 402-751 (Korea, Republic of); Ho Chang, Jeong, E-mail: firstname.lastname@example.com [Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of)
High resolution transmission electron microscopy of melamine-formaldehyde aerogels and silica aerogels
The goal of the high resolution transmission electron microscopy (HRTEM) was to image the structure of two tetramethyl orthosilicate (TMOS) and two melamine-formaldehyde (MF) aerogels at the single polymer chain level{sup 1,2}. With this level of structural resolution we hoped to interrelate each aerogel's structure with its physical properties and its method of synthesis. Conventional single-step base catalysed TMOS aerogels show strings of spheroidal particles linked together with minimal necking. The spheroidal particles range from 86--132 {Angstrom} and average 113{plus minus}10 {Angstrom} in diameter{sup 2}. In contrast the TMOS aerogels reported on here were made by a two step method. After extended silica chains are grown in solution under acidic conditions with a substoichiometric amount of water, the reaction is stopped and the methanol hydrolysed from TMOS is removed. Then base catalysis and additional water are added to cause gel formation is a nonalcoholic solvent. The MF aerogels were prepared for HRTEM by fracturing them on a stereo microscope stage with razor knife so that fractured pieces with smooth flat surfaces could be selected for platinum-carbon replication. The two silica (TMOS) aerogels were both transparent and difficult to see. These aerogels were fractured on a stereo microscope stage with tweezers. 6 refs., 4 figs.
Ruben, G.C. (Dartmouth Coll., Hanover, NH (United States). Dept. of Biological Sciences)
Study of a Threshold Cherenkov Counter Based on Silica Aerogels with Low Refractive Indices
To identify $\\pi^{\\pm}$ and $K^{\\pm}$ in the region of $1.0\\sim 2.5$ GeV/c, a threshold Cherenkov counter equipped with silica aerogels has been investigated. Silica aerogels with a low refractive index of 1.013 have been successfully produced using a new technique. By making use of these aerogels as radiators, we have constructed a Cherenkov counter and have checked its properties in a test beam. The obtained results have demonstrated that our aerogel was transparent enough to make up for loss of the Cherenkov photon yield due to a low refractive index. Various configurations for the photon collection system and some types of photomultipliers, such as the fine-mesh type, for a read out were also tested. From these studies, our design of a Cherenkov counter dedicated to $\\pi / K$ separation up to a few GeV/c %in the momentum range of $1.0 \\sim 2.5$ GeV/c with an efficiency greater than $90$ \\% was considered.
I. Adachi et al
Fractures and fracture networks are the principal pathways for migration of water and contaminants in groundwater systems, fluids in enhanced geothermal systems (EGS), oil and gas in petroleum reservoirs, carbon dioxide leakage from geological carbon sequestration, and radioactive and toxic industrial wastes from underground storage repositories. When dealing with EGS fracture networks, there are several major issues to consider, e.g., the minimization of hydraulic short circuits and losses of injected geothermal fluid to the surrounding formation, which in turn maximize heat extraction and economic production. Gel deployments to direct and control fluid flow have been extensively and successfully used in the oil industry for enhanced oil recovery. However, to the best of our knowledge, gels have not been applied to EGS to enhance heat extraction. In-situ gelling systems can either be organic or inorganic. Organic polymer gels are generally not thermostable to the typical temperatures of EGS systems. Inorganic gels, such as colloidal silica gels, however, may be ideal blocking agents for EGS systems if suitable gelation times can be achieved. In the current study, we explore colloidal silica gelation times and rheology as a function of SiO{sub 2} concentration, pH, salt concentration, and temperature, with preliminary results in the two-phase field above 100 C. Results at 25 C show that it may be possible to choose formulations that will gel in a reasonable and predictable amount of time at the temperatures of EGS systems.
Hunt, J D; Ezzedine, S M; Bourcier, W; Roberts, S
Geothermometry At Long Valley Caldera Area (Sorey, Et Al., 1991) | Open
Long Valley Caldera Area (Sorey, Et Long Valley Caldera Area (Sorey, Et Al., 1991) Exploration Activity Details Location Long Valley Caldera Area Exploration Technique Geothermometry Activity Date Usefulness could be useful with more improvements DOE-funding Unknown Notes Silica-geothermometer temperature estimates for the Casa Diablo and RDO-8 well samples ( 196-202 degrees C) are lower than the corresponding cation-geothermometer temperature estimates, indicating loss of silica with declining reservoir temperature or dilution with low-silica waters. At shallow depths in the caldera References Michael L. Sorey, Gene A. Suemnicht, Neil C. Sturchio, Gregg A. Nordquist (1991) New Evidence On The Hydrothermal System In Long Valley Caldera, California, From Wells, Fluid Sampling, Electrical Geophysics, And
Durability of LDPE nanocomposites with clay, silica, and zinc oxide: part I: mechanical properties of the nanocomposite materials
Three types of LDPE-based nanocomposites with montmorillonite clay, silica, and zinc oxide were prepared by melt blending the nanofiller with the resin. As a prelude to studying their durability, the extent of reinforcement of the LDPE matrix by the ...
Halim Hamid Redhwi, Mohammad Nahid Siddiqui, Anthony L. Andrady, Syed Hussain
Formation Over a 1.01; Ru/A1 o Catalyst at 498K H/CO P (atm)a silica-supported Ru catalyst Fig. 2 Effect of feed flowan alumina-supported Ru catalyst Fig. 3 Effect of reaction
Kellner, C.Stephen
Silver nanoparticles confined in SBA-15 mesoporous silica and the application as a sensor for detecting hydrogen peroxide
Silver nanoparticles within the pore channels of selectively grafted mesoporous silica SBA-15 were synthesized. Silanols on the external surface of as-SBA-15 were first capped by -Si(CH3)3 groups. After removal of the template of ...
Dong-Hai Lin; Yan-Xia Jiang; Ying Wang; Shi-Gang Sun
Reducing Logistics Footprints and Replenishment Demands: Nano-engineered Silica Aerogels a Proven Method for Water Treatment
Rapid deployment and the use of objective force aggressively reduce logistic footprints and replenishment demands. Maneuver Sustainment requires that Future Combat Systems be equipped with water systems that are lightweight, have small footprints, and are highly adaptable to a variety of environments. Technologies employed in these settings must be able to meet these demands. Lawrence Livermore National Laboratory has designed and previously field tested nano-engineered materials for the treatment of water. These materials have been either based on silica aerogel materials or consist of composites of these aerogels with granular activated carbon (GAC). Recent tests have proven successful for the removal of contaminants including uranium, hexavalent chromium, and arsenic. Silica aerogels were evaluated for their ability to purify water that had been spiked with the nerve agent VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate). These results demonstrated that silica aerogels were able to remove the VX from the supply water and were nearly 30 times more adsorbent than GAC. This performance could result in REDUCING CHANGEOUT FREQUENCY BY A FACTOR OF 30 or DECREASING the VOLUME of adsorbent BY A FACTOR OF 30; thereby significantly reducing logistic footprints and replenishment demands. The use of the nano-engineered Silica Aerogel/GAC composites would provide a water purification technology that meets the needs of Future Combat Systems.
Daily, W; Coleman, S; Love, A; Reynolds, J; O'Brien, K; Gammon, S
Molecular Dynamics Studies on the Effects of Water Speciation on Interfacial Structure and Dynamics in Silica-Filled PDMS Composites
Significant changes in materials properties of siloxane based polymers can be obtained by the addition of inorganic fillers. In silica-filled polydimethylsiloxane (PDMS) based composites the mechanism of this reinforcing behavior is presumably hydrogen bonding between surface hydroxyls and backbone siloxane species. We have chosen to investigate in detail the effect of chemisorbed and physisorbed water on the interfacial structure and dynamics in silica-filled PDMS based composites. Toward this end, we have combined molecular dynamics simulations and experimental studies employing DMA and Nh4R analysis. Our results suggest that the polymer-silica contact distance and the mobility of interfacial polymer chains significantly decreased as the hydration level at the interface was reduced. The reduced mobility of the PDMS chains in the interfacial domain reduced the overall, bulk, motional properties of the polymer, thus causing an effective ''stiffening'' of the polymer matrix. The role of the long-ranged Coulombic interactions on the structural features and chain dynamics of the polymer were also examined. Both are found to be strongly influenced by the electrostatic interactions as identified by the bond orientation time correlation function and local density distribution functions. These results have important implications for the design of nanocomposite silica-siloxane materials.
Gee, R H; Maxwell, R S; Dinh, L N; Balazs, B
Performance predictions of silica-gel desiccant dehumidifiers. Technical report No. 3
Development of transparent silica aerogel over a wide range of densities
We have succeeded in developing hydrophobic silica aerogels over a wide range of densities (i.e. refractive indices). A pinhole drying method was invented to make possible producing highly transparent aerogels with entirely new region of refractive indices of 1.06-1.26. Obtained aerogels are more transparent than conventional ones, and the refractive index is well controlled in the pinhole drying process. A test beam experiment was carried out in order to evaluate the performance of the pinhole-dried aerogels as a Cherenkov radiator. A clear Cherenkov ring was successfully observed by a ring imaging Cherenkov counter. We also developed monolithic and hydrophobic aerogels with a density of 0.01 g/cm^3 (a low refractive index of 1.0026) as a cosmic dust capturer for the first time. Consequently, aerogels with any refractive indices between 1.0026 and 1.26 can be produced freely.
Makoto Tabata; Ichiro Adachi; Yoshikazu Ishii; Hideyuki Kawai; Takayuki Sumiyoshi; Hiroshi Yokogawa
Tanpopo cosmic dust collector: Silica aerogel production and bacterial DNA contamination analysis
Hydrophobic silica aerogels with ultra-low densities have been designed and developed as cosmic dust capture media for the Tanpopo mission which is proposed to be carried out on the International Space Station. Glass particles as a simulated cosmic dust with 30 \\mu m in diameter and 2.4 g/cm^3 in density were successfully captured by the novel aerogel at a velocity of 6 km/s. Background levels of contaminated DNA in the ultra-low density aerogel were lower than the detection limit of a polymerase chain reaction assay. These results show that the manufactured aerogel has good performance as a cosmic dust collector and sufficient quality in respect of DNA contamination. The aerogel is feasible for the biological analyses of captured cosmic dust particles in the astrobiological studies.
Tabata, Makoto; Yokobori, Shin-ichi; Kawai, Hideyuki; Takahashi, Jun-ichi; Yano, Hajime; Yamagishi, Akihiko
Tabata, Makoto; Ishii, Yoshikazu; Kawai, Hideyuki; Sumiyoshi, Takayuki; Yokogawa, Hiroshi; 10.1016/j.nima.2010.02.241
X-ray radiographic technique for measuring density uniformity of silica aerogel
This paper proposes a new X-ray radiographic technique for measuring density uniformity of silica aerogels used as radiator in proximity-focusing ring-imaging Cherenkov detectors. To obtain high performance in a large-area detector, a key characteristic of radiator is the density (i.e. refractive index) uniformity of an individual aerogel monolith. At a refractive index of n = 1.05, our requirement for the refractive index uniformity in the transverse plane direction of an aerogel tile is |\\delta (n - 1)/(n - 1)| aerogels from a trial production and that of Panasonic products (SP-50) as a reference, and to confirm they have sufficient density uniformity within \\pm 1% along the transverse plane direction. The measurement results show that the proposed technique can quantitatively estimate the density uniformity of aerogels.
Makoto Tabata; Yoshikiyo Hatakeyama; Ichiro Adachi; Takeshi Morita; Keiko Nishikawa
Post-Harvest Processing Methods for Reduction of Silica and Alkali Metals in Wheat Straw
Silica and alkali metals in wheat straw limit its use for bioenergy and gasification. Slag deposits occur via the eutectic melting of SiO2 with K2O, trapping chlorides at surfaces and causing corrosion. A minimum melting point of 950�C is desirable, corresponding to SiO2:K2O of about 3:1. Mild chemical treatments were used to reduce Si, K, and Cl, while varying temperature, concentration, %-solids, and time. Dilute acid was more effective at removing K and Cl, while dilute alkali was more effective for Si. Reduction of minerals in this manner may prove economical for increasing utilization of the straw for combustion or gasification.
Thompson, David Neal; Lacey, Jeffrey Alan; Shaw, Peter Gordon
New CoNCept for the fAbriCAtioN of New CoNCept for the fAbriCAtioN of hydrogeN SeleCtive SiliCA MeMbrANeS Background As stated in the National Research Council report on Novel Approaches to Carbon Management, a novel membrane is needed that can achieve the separation of carbon dioxide (CO 2 ) and hydrogen (H 2 ) at a high temperature and pressure. Extensive efforts over the last several decades have explored high temperature H 2 -selective membranes made of silicon dioxide (SiO 2 ) and other oxides, palladium (Pd) and other metals or alloys and, more recently, various zeolites and non-aluminosilicate molecular sieves. Although promising separation results have been reported for many of them, these technologies, they all suffer from high production costs for membrane fabrication and from long term stability problems. This project revisits
Robust conductive mesoporous carbon?silica composite films with highly ordered and oriented orthorhombic structures from triblock-copolymer template co-assembly
In this work, we describe a facile approach to improve the robustness of conductive mesoporous carbon-based thin films by the addition of silica to the matrix through the triconstituent organic-inorganic-organic co-assembly of resol (carbon precursor) and tetraethylorthosilicate (silica precursor) with triblock-copolymer Pluronic F127. The pyrolysis of the resol-silica-pluronic F127 film yields a porous composite thin film with well-defined mesostructure. X-Ray diffraction (XRD), grazing incidence small angle X-ray scattering (GISAXS), and electron microscopy measurements indicate that the obtained carbon-based thin films have a highly ordered orthorhombic mesostructure (Fmmm) with uniform large pore size ({approx}3 nm). The orthorhombic mesostructure is oriented and the (010) plane is parallel to the silicon wafer substrate. The addition of silica to the matrix impacts the pore size, surface area, porosity, modulus and conductivity. For composite films with approximately 40 wt% silica, the conductivity is decreased by approximately an order of magnitude in comparison to a pure carbon mesoporous film, but the conductivity is comparable to typical printed carbon inks used in electrochemical sensing, {approx}10 S cm{sup -1}. The mechanical properties of these mesoporous silica-carbon hybrid films are similar to the pure carbon analogs with a Young's modulus between 10 GPa and 15 GPa, but the material is significantly more porous. Moreover, the addition of silica to the matrix appears to improve the adhesion of the mesoporous film to a silicon wafer. These mesoporous silica-carbon composite films have appropriate characteristics for use in sensing applications.
Song, Lingyan; Feng, Dan; Campbell, Casey G.; Gu, Dong; Forster, Aaron M.; Yager, Kevin G.; Fredin, Nathaniel; Lee, Hae-Jeong; Jones, Ronald L.; Zhao, Dongyuan; Vogt, Bryan D. (AZU)
An AC phase measuring interferometer for measuring dn/dT of fused silica and calcium fluoride at 193 nm
A novel method for the measurement of the change in index of refraction vs. temperature (dn/dT) of fused silica and calcium fluoride at the 193 nm wavelength has been developed in support of thermal modeling efforts for the development of 193 nm-based photolithographic exposure tools. The method, based upon grating lateral shear interferometry, uses a transmissive linear grating to divide a 193 nm laser beam into several beam paths by diffraction which propagate through separate identical material samples. One diffracted order passing through one sample overlaps the undiffracted beam from a second sample and forms interference fringes dependent upon the optical path difference between the two samples. Optical phase delay due to an index change from heating one of the samples causes the interference fringes to change sinusoidally with phase. The interferometer also makes use of AC phase measurement techniques through lateral translation of the grating. Results for several samples of fused silica and calcium fluoride are demonstrated.
Shagam, R.N.
Effect of high silica content on scale deposition and pipe-wall loss in oilfield steam generators
Studies were conducted on site in the Coalinga, Belridge, and Midway Sunset fields in California to research the cause of metal losses detected in the radiant section return bends and immediate piping downstream form the stem generators. This paper reports on the surveillance of silica content in the influent and effluent streams of the selected steam generators and the results of X-ray inspection of bends, elbows, welds, and pipings which indicated that a correlation is likely to exist between the silica and bicarbonate concentration in the feedwater and the silicate scale buildup, and incident rate of wall loss and the cause of wall loss/pipe failures is a combination of corrosion and erosion mechanisms accelerated at higher steam qualities.
Khatib, Z.I.; Olson, E.E.; Place, M.C. Jr. (Shell Development Co., Houston, TX (United States))
Electron-beam induced electric-hydraulic expansion in a silica-shelled gallium microball-nanotube structure
Heteroshape-heteroscale structure of silica-shelled Ga microball-nanotube was fabricated. Under in situ electron-beam irradiation, an abnormally large and fast expansion of Ga was observed. Failed by a sole routine heating effect of electron-beam, the expansion was explained by an electric-hydraulic expansion effect taking into account a huge inner pressure induced by the repelling Coulomb force of positively charged Ga ions on the Ga microball surface. The ions were accumulated due to knocking-out of Ga electrons under irradiation and shielding effect of a silica shell which prevents the charge balance restoration. A circuit model is proposed to calculate the accumulation of Ga ions.
Gao, Y. H.; Sun, M.; Su, J. [Wuhan National Laboratory for Optoelectronics (WNLO), School of Physics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology (HUST), LuoyuRoad 1037, Wuhan 430074 (China); Zhi, C. Y.; Golberg, D.; Bando, Y. [International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba, Ibaraki 305-0044 (Japan); Duan, X. F. [Institute of Physics, Beijing National Laboratory of Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190 (China)
Multicomponent Seismic Technology Assessment of
Geology, Austin, Texas, U.S.A. H. H. Roberts Louisiana State University, Baton Rouge, Louisiana, U.S.A. W, and R. Boswell, eds., Natural gas hydrates--Energy resource potential and associated geologic hazards
Silane Modification of Glass and Silica Surfaces to Obtain Equally Oil-Wet Surfaces in Glass-Covered Silicon Micromodel Applications
The wettability of silicon and glass surfaces can be modified by silanization. However, similar treatments of glass and silica surfaces using the same silane do not necessarily yield the same wettability as determined by the oil-water contact angle. In this technical note, surface cleaning pretreatments were investigated to determine conditions that would yield oil-wet surfaces on glass with similar wettability to silica surfaces treated with the same silane, and both air-water and oil-water contact angles were determined. Air-water contact angles were less sensitive to differences between silanized silica and glass surfaces, often yielding similar values while the oil-water contact angles were quite different. Borosilicate glass surfaces cleaned with standard cleaning solution 1 (SC1) yield intermediate-wet surfaces when silanized with hexamethyldisilazane, while the same cleaning and silanization yields oil-wet surfaces on silica. However, cleaning glass in boiling concentrated nitric acid creates a surface that can be silanized to obtain oil-wet surfaces using HDMS. Moreover, this method is effective on glass with prior thermal treatment at an elevated temperature of 400oC. In this way, silica and glass can be silanized to obtain equally oil-wet surfaces using HMDS. It is demonstrated that pretreatment and silanization is feasible in silicon-silica/glass micromodels previously assembled by anodic bonding, and that the change in wettability has a significant observable effect on immiscisble fluid displacements in the pore network.
Grate, Jay W.; Warner, Marvin G.; Pittman, Jonathan W.; Dehoff, Karl J.; Wietsma, Thomas W.; Zhang, Changyong; Oostrom, Martinus
Eighth CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete
The nine papers in this CD are collected by the U. S. Advisory Committee for presentation at the Eighth CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete, May 23�29, 2004, Las Vegas, Nevada. They are being published by EPRI, Palo Alto, CA to make them available to all attendees, and other interested people, in a compact form for future reference and use.
Cr(VI) adsorption on functionalized amorphous and mesoporous silica from aqueous and non-aqueous media
A mesoporous silica (SBA-15) and amorphous silica (SG) have been chemically modified with 2-mercaptopyridine using the homogeneous route. This synthetic route involved the reaction of 2-mercaptopyridine with 3-chloropropyltriethoxysilane prior to immobilization on the support. The resulting material has been characterized by powder X-ray diffraction, nitrogen gas sorption, FT-IR and MAS NMR spectroscopy, thermogravimetry and elemental analysis. The solid was employed as a Cr(VI) adsorbent from aqueous and non-aqueous solutions at room temperature. The effect of several variables (stirring time, pH, metal concentration and solvent polarity) has been studied using the batch technique. The results indicate that under the optimum conditions, the maximum adsorption value for Cr(VI) was 1.83 {+-} 0.03 mmol/g for MP-SBA-15, whereas the adsorption capacity of the MP-SG was 0.86 {+-} 0.02 mmol/g. On the basis of these results, it can be concluded that it is possible to modify chemically SBA-15 and SG with 2-mercaptopyridine and to use the resulting modified silicas as effective adsorbents for Cr(VI)
Perez-Quintanilla, Damian [Departamento de Quimica Inorganica y Analitica, E.S.C.E.T, Universidad Rey Juan Carlos, C/Tulipan s/n, 28933 Mostoles, Madrid (Spain)]. E-mail: email@example.com; Hierro, Isabel del [Departamento de Quimica Inorganica y Analitica, E.S.C.E.T, Universidad Rey Juan Carlos, C/Tulipan s/n, 28933 Mostoles, Madrid (Spain); Fajardo, Mariano [Departamento de Quimica Inorganica y Analitica, E.S.C.E.T, Universidad Rey Juan Carlos, C/Tulipan s/n, 28933 Mostoles, Madrid (Spain); Sierra, Isabel [Departamento de Quimica Inorganica y Analitica, E.S.C.E.T, Universidad Rey Juan Carlos, C/Tulipan s/n, 28933 Mostoles, Madrid (Spain)]. E-mail: firstname.lastname@example.com
It is attempted to synthesize hydrogen selective silica-based membranes through a novel thin film deposition concept. This report describes the progress made during the 1st Year of this award. All project Tasks, for Year 1, were completed and the first thin films were prepared and characterized. The goal of this work is to use crystalline layered silicates to form hydrogen selective membranes for use in high temperature hydrogen/carbon dioxide separations. It was proposed to: (A) Synthesize layered silicate materials; (B) Prepare dispersions of as synthesized or delaminated layered silicates; (C) Prepare membranes by coating the layered silicates on macro-mesoporous supports; and (D) Test the membranes for H{sub 2}/CO{sub 2} selectivity at high temperature and pressures and for structural and functional stability at high temperature in the presence of water vapor. All Year 1 project Tasks are completed. Layered silicate particles were synthesized hydrothermally. Crystal shape and size was optimized for the formation of thin films. Calcination procedures that avoid particle agglomeration were developed and suspensions of the calcined silicate particles were prepared. The silicate particles and suspensions were characterized by X-Ray Diffraction, Electron Microscopy and Dynamic Light Scattering. The characterization data indicate that plate like morphology, large aspect ratio and good dispersion have been achieved. A deposition process that leads to uniform, high-coverage ({approx}100%) coating of the layered silicate particles on porous alpha-alumina supports was developed.
The effect of particle-particle interaction forces on the flow properties of silica slurries
Preliminary work has been completed to investigate the effect of particle-particle interaction forces on the flow properties of silica slurries. Classically hydro-transport studies have focused on the flow of coarse granular material in Newtonian fluids. However, with current economical and environmental pressures, the need to increase solid loadings in pipe flow has lead to studies that examine non-Newtonian fluid dynamics. The flow characteristics of non-Newtonian slurries can be greatly influenced through controlling the solution chemistry. Here we present data on an 'ideal' slurry where the particle size and shape is controlled together with the solution chemistry. We have investigated the effect of adsorbed cations on the stability of a suspension, the packing nature of a sediment and the frictional forces to be overcome during re-slurrying. A significant change in the criteria assessed was observed as the electrolyte concentration was increased from 0.1 mM to 1 M. In relation to industrial processes, such delicate control of the slurry chemistry can greatly influence the optimum operating conditions of non-Newtonian pipe flows. (authors)
Harbottle, David; Fairweather, Michael; Biggs, Simon [Institute of Particle Science and Engineering, School of Process, Environmental and Materials Engineering, University of Leeds, UK, LS2 9JT (United Kingdom); Rhodes, Dominic [Nexia Solutions, Sellafield, Cumbria (United Kingdom)
Tuning the properties of Ge-quantum dots superlattices in amorphous silica matrix through deposition conditions
In this work, we investigate the structural properties of Ge quantum dot lattices in amorphous silica matrix, prepared by low-temperature magnetron sputtering deposition of (Ge+SiO{sub 2})/SiO{sub 2} multilayers. The dependence of quantum dot shape, size, separation, and arrangement type on the Ge-rich (Ge + SiO{sub 2}) layer thickness is studied. We show that the quantum dots are elongated along the growth direction, perpendicular to the multilayer surface. The size of the quantum dots and their separation along the growth direction can be tuned by changing the Ge-rich layer thickness. The average value of the quantum dots size along the lateral (in-plane) direction along with their lateral separation is not affected by the thickness of the Ge-rich layer. However, the thickness of the Ge-rich layer significantly affects the quantum dot ordering. In addition, we investigate the dependence of the multilayer average atomic composition and also the quantum dot crystalline quality on the deposition parameters.
Pinto, S. R. C.; Ramos, M. M. D.; Gomes, M. J. M. [University of Minho, Centre of Physics and Physics Department, Braga 4710-057 (Portugal); Buljan, M. [Ruder Boskovic Institute, Bijenicka cesta 54, Zagreb 10000 (Croatia); Chahboun, A. [University of Minho, Centre of Physics and Physics Department, Braga 4710-057 (Portugal); Physics Department, FST Tanger, Tanger BP 416 (Morocco); Roldan, M. A.; Molina, S. I. [Departamento de Ciencia de los Materiales e Ing. Metalurgica y Q. I., Universidad de Cadiz, Cadiz (Spain); Bernstorff, S. [Sincrotrone Trieste, SS 14 km163, 5, Basovizza 34012 (Italy); Varela, M.; Pennycook, S. J. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Barradas, N. P.; Alves, E. [Instituto Superior Tecnico e Instituto Tecnologico e Nuclear-, EN10, Sacavem 2686-953 (Portugal)
Pinto, S. [University of Minho, Portugal; Roldan Gutierrez, Manuel A [ORNL; Ramos, M. M.D. [University of Minho, Portugal; Gomes, M.J.M. [University of Minho, Portugal; Molina, S. I. [Universidad de Cadiz, Spain; Pennycook, Stephen J [ORNL; Varela del Arco, Maria [ORNL; Buljan, M. [R. Boskovic Institute, Zagreb, Croatia; Barradas, N. [Instituto Tecnologico e Nuclear (ITN), Lisbon, Portugal; Alves, E. [Instituto Tecnologico e Nuclear (ITN), Lisbon, Portugal; Chahboun, A. [FST Tanger, Morocco; Bernstorff, S. [Sincrotrone Trieste, Basovizza, Italy
Pyrolysis and hydropyrolysis of diphenylmethane and sulphur-containing compounds immobilised on silica
The use of high pressures and dispersed catalysts, such as sulphided molybdenum (Mo) in fixed-bed hydropyrolysis of coals give rise to increased tar yields. In order to improve our understanding of these phenomena, Particularly in relation to cleavage of C-C and C-S bonds, experiments have been conducted on samples of silica-immobilised benzene, diphenylmethane, thioanisole and dibenzothiophene (DBT). These model substrates have the inherent advantage that they do not soften and thus stay in the reactor. Moreover, for the surface-immobilized benzene, the SiO-C bond linking the substrate to the surface is reasonably stable and does not show significant cleavage until 550{degrees}C (peak maximum) with a high yield of benzene being achieved at 150 bar hydrogen pressure. For the diphenylmethane substrate, the use of 150 bar hydrogen pressure and the Mo catalyst both reduced the peak evolution temperatures for benzene and toluene clearly demonstrating their separate contributions to promoting C-C bond cleavage. Desulphurisation of the DBT substrate occurred only in hydrogen and the thermal decomposition of the thioanisole substrate was altered markedly by the Mo catalyst.
Mitchell, S.C.; Lafferty, C.J.; Garcia, R.; Ismail, K.; Snape, C.E. [Strathclyde Univ., Glasgow (United Kingdom). Dept. of Pure and Applied Chemistry; Buchanan, A.C. III; Britt, P.F. [Oak Ridge National Lab., TN (United States); Klavetter, E. [Sandia National Labs., Albuquerque, NM (United States); en
Thermal and solar-optical properties of silica aerogel for use in insulated windows
Silica aerogel is a porous insulating material that is transport to solar radiation. To understand its insulating performance in a window system, it is necessary to first study component heat transfer paths. Aerogel's absorption coefficient, a measure of the attenuation of radiation heat transfer, was determined over the spectral range 1-200 ..mu..m. Although radiation heat transfer is negligible over much of this region, there is a transmission window between 3-6 ..mu..m. At ambient temperatures, for aerogel thicknesses of 0.5-5.0 cm, radiation heat transfer through an unmodified aerogel window is less than 15% of the total heat flux. For evacuated or high-temperature furnace windows, this contribution can be over 50%. Thermal radiative transfer can be somewhat decreased by allowing the aerogel to absorb moisture, but solar transmission and optical clarity are sacrificed. Absorption of water vapor over time causes irreversible structural changes that increase scattering in the solar spectrum. Aerogel's thermal performance can be improved by replacing the pore gas with one of lower conductivity or by evacuating the aerogel to pressure below 0.1 atm. A hypothetical evacuated aerogel window has a calcuated U-Value of approx. =0.5 W/m/sup 2/-K for a gap spacing of 12.5 mm, which is four times better than currently available low-emissivity gas-filled units of similar size. 8 refs., 9 figs.
Hartmann, J.; Rubin, M.; Arasteh, D.
Elastic properties of silica aerogels from a new rapid supercritical extraction process
Silica aerogels were produced by a new process from Tetramethoxysilane (TMOS) with ammonia as base catalyst. the process involves pouring the liquid sol in a stainless steel mold and immediately heating it to supercritical conditions. Gelation and aging occurs during heating and reaction rates are high die to high average temperatures. the gel fills the container completely, which enables relatively fast venting of the supercritical fluid by providing a constraint for swelling and failure of the gel monolith. The whole process can be completed in 6 h or less. Longitudinal and shear moduli were measured in the dried aerogels by ultrasonic velocity measurements both as a function of chemical composition of the original sol and of position in the aerogel. It was found that the sound velocity exhibits marked maxima on the surface of the cylindrical specimens and specifically close to the ends, where the fluid left during venting. Specimens with high catalyst concentration and high water:TMOS ratio exhibited higher average moduli.
Gross, J.; Coronado, P.R.; Hair, L.M.; Hrubesh, L.W.
Corrugation of Phase-Separated Lipid Bilayers Supported by Nanoporous Silica Xerogel Surfaces
Lipid bilayers supported by substrates with nanometer-scale surface corrugations holds interest in understanding both nanoparticle-membrane interactions and the challenges of constructing models of cell membranes on surfaces with desirable properties, e.g. porosity. Here, we successfully form a two-phase (gel-fluid) lipid bilayer supported by nanoporous silica xerogel. Surface topology, diffusion, and lipid density in comparison to mica-supported lipid bilayers were characterized by AFM, FRAP, FCS, and quantitative fluorescence microscopy, respectively. We found that the two-phase lipid bilayer follows the xerogel surface contours. The corrugation imparted on the lipid bilayer results in a lipid density that is twice that on a flat mica surface. In direct agreement with the doubling of actual bilayer area in a projected area, we find that the lateral diffusion coefficient (D) of lipids on xerogel ({approx}1.7 {micro}m{sup 2}/s) is predictably lower than on mica ({approx}4.1 {micro}m{sup 2}/s) by both FRAP and FCS techniques. Furthermore, the gel-phase domains on xerogel compared to mica were larger and less numerous. Overall, our results suggest the presence of a relatively defect-free continuous two-phase bilayer that penetrates approximately midway into the first layer of {approx}50 nm xerogel beads.
Goksu, E I; Nellis, B A; Lin, W; Satcher Jr., J H; Groves, J T; Risbud, S H; Longo, M L
Helium Adsorption in Silica Aerogel near the Liquid-Vapor Critical Point
We have investigated the adsorption and desorption of helium near its liquid-vapor critical point in silica aerogels with porosities between 95 % and 98%. We used a capacitive measurement technique which allowed us to probe the helium density inside the aerogel directly, even though the samples were surrounded by bulk helium. The aerogel�s very low thermal conductivity resulted in long equilibration times so we monitored the pressure and the helium density, both inside the aerogel and in the surrounding bulk, and waited at each point until all had stabilized. Our measurements were made at temperatures far from the critical point, where a well defined liquid-vapor interface exists, and at temperatures up to the bulk critical point. Hysteresis between adsorption and desorption isotherms persisted to temperatures close to the liquid-vapor critical point and there was no sign of an equilibrium liquid-vapor transition once the hysteresis disappeared. Many features of our isotherms can be described in terms of capillary condensation, although this picture becomes less applicable as the liquid-vapor critical point is approached and it is unclear how it can be applied to aerogels, whose tenuous structure includes a wide range of length scales. I.
Tobias Herman; James Day; John Beamish
Compressed Silica Aerogels for the Study of Superfluid [superscript 3]He
We have performed Small Angle X-ray Scattering (SAXS) on uniaxially strained aerogels and measured the strain-induced structural anisotropy. We use a model to connect our SAXS results to anisotropy of the {sup 3}He quasiparticle mean free path in aerogel. Measurements of the low temperature phase diagram of superfluid {sup 3}He in 98% aerogel indicate a stable B-phase and a metastable A-like phase. Vicente et al. proposed that the relative stability of these phases can be attributed to local anisotropic scattering of the 3He quasiparticles by the aerogel network. This network consists of silica strands with a diameter of {approx} 30 {angstrom} and average separation {zeta}{sub a} {approx} 300 {angstrom}. Vicente et al. also proposed using uniaxial strain of the aerogel to produce global anisotropy. We have performed SAXS on two uniaxially strained aerogels and found that strain introduces anisotropy on the {approx}100 {angstrom} length scale. We relate this to anisotropy of the quasiparticle mean free path, {lambda}.
Pollanen, J.; Choi, H.; Davis, J.P.; Blinstein, S.; Lippman, T.M.; Lurio, L.B.; Mulders, N.; Halperin, W.P. (NIU); (Delaware); (NWU)
To support the future expansion of nuclear energy, an effective method is needed to capture and safely store radiological iodine-129 released during reprocessing of spent nuclear fuel. Various materials have been investigated to capture and immobilize iodine. In most cases, however, the materials that are effective for capturing iodine cannot subsequently be sintered/densified to create a stable composite that could be a viable waste form. We have developed chemically modified, highly porous, silica aerogels that show sorption capacities higher than 440 mg of I2 per gram at 150 C. An iodine uptake test in dry air containing 4.2 ppm of iodine demonstrated no breakthrough after 3.5 h and indicated a decontamination factor in excess of 310. Preliminary densification tests showed that the I2-loaded aerogels retained more than 92 wt% of I2 after thermal sintering with pressure assistance at 1200 C for 30 min. These high capture and retention efficiencies for I2 can be further improved by optimizing the functionalization process and the chemistry as well as the sintering conditions.
Matyas, Josef; Fryxell, Glen E.; Busche, Brad J.; Wallace, Krys; Fifield, Leonard S.
Helium adsorption in silica aerogel near the liquid-vapor critical point
We have investigated the adsorption and desorption of helium near its liquid-vapor critical point in silica aerogels with porosities between 95% and 98%. We used a capacitive measurement technique which allowed us to probe the helium density inside the aerogel directly, even though the samples were surrounded by bulk helium. The aerogel's very low thermal conductivity resulted in long equilibration times so we monitored the pressure and the helium density, both inside the aerogel and in the surrounding bulk, and waited at each point until all had stabilized. Our measurements were made at temperatures far from the critical point, where a well defined liquid-vapor interface exists, and at temperatures up to the bulk critical point. Hysteresis between adsorption and desorption isotherms persisted to temperatures close to the liquid-vapor critical point and there was no sign of an equilibrium liquid-vapor transition once the hysteresis disappeared. Many features of our isotherms can be described in terms of capillary condensation, although this picture becomes less applicable as the liquid-vapor critical point is approached and it is unclear how it can be applied to aerogels, whose tenuous structure includes a wide range of length scales.
Enzymatic Conversion of CO2 to Bicarbonate in Functionalized Mesoporous Silica
We report here that carbonic anhydrase (CA), the fastest enzyme that can covert carbon dioxide to bicarbonate, can be spontaneously entrapped in functionalized mesoporous silica (FMS) with super-high loading density (up to 0.5 mg of protein/mg of FMS) due to the dominant electrostatic interaction. The binding of CA to HOOC-FMS can result in the protein�s conformational change comparing to the enzyme free in solution, but can be overcome with increased protein loading density. The higher the protein loading density, the less conformational change, hence the higher enzymatic activity and the higher enzyme immobilization efficiency. The electrostatically bound CA can be released by changing pH. The released enzyme still displayed the native conformational structure and the same high enzymatic activity as that prior to the enzyme entrapment. This work opens up a new approach converting carbon dioxide to biocarbonate in a biomimetic nanoconfiguration that can be integrated with the other part of biosynthesis process for the assimilation of carbon dioxide.
Yu, Yuehua; Chen, Baowei; Qi, Wen N.; Li, Xiaolin; Shin, Yongsoon; Lei, Chenghong; Liu, Jun
Synthesis of Novel Polypeptide-Silica Hybrid Materials through Surface-Initiated N-carboxyanhydride Polymerization
There is an increasing demand for materials that are physically robust, easily recovered, and able to perform a wide variety of chemical functions. By combining hard and soft matter synergistically, organic-inorganic hybrid materials are potentially useful for a number of applications (e.g. catalysis, separations, sensing). In this respect, organic/ordered mesoporous silica (OMS) hybrids have attracted considerable attention, with an increasing emphasis on complex organic moieties achieved through multi-step reactions and polymerizations. It is on this front that we have focused our work, specifically in regard to polypeptides. Polypeptides are well suited organic components for hybrids as they provide a wide range of possible side chain chemistries (NH2, -SH, -COOH, -OH, etc.), chirality, and have conformations that are known to be responsive to external stimuli (pH, electrolytes, solvents, etc.). Our work has shown that N-carboxyanhydride chemistry offers a facile single step approach to the incorporation of dense polypeptide brushes in OMS. Modifying the initiator loading, pore size, pore topology, and monomer identity significantly impacted the properties of the obtained composites and peptide brush layers. Extending this work, a synthesis paradigm for preferentially grafting poly-L-lysine to the external and internal surfaces of SBA-15, a widely used OMS material, was developed. We observed that the pores of these hybrids could be opened and closed by the reversible swelling of the polypeptide layer. Similarly, novel bifunctional hybrids were synthesized by grafting polypeptides to the external surface of monodisperse OMS spheres that contain a thiol-functionalized core. The accessibility of the internal thiols to a fluorescent dye shows the potential of these hybrids for applications such as controlled uptake/release.
Lunn, Jonathan D.
Corrections for Measurements of Tritium in Subterranean Vapor using Silica Gel
Hazardous contaminants buried within vadose zones can accumulate in soil gas. The concentrations and spatial extent of these contaminants are measured to evaluate potential transport to ground water for public risk evaluation. Tritium is an important contaminant found in and monitored for in vadose zones across numerous sites within the United States nuclear weapons complex, including Los Alamos National Laboratory. The extraction, collection, and laboratory analysis of tritium from subterranean soil gas presents numerous technical challenges that have not been fully studied. Particularly, the lack of soil moisture in the soil gas in the vadose zone makes it difficult to obtain enough sample moisture (e.g., > 5 g) to provide for the required sensitivity, and often, only small amounts of moisture can be collected. Further, although silica gel has high affinity for water vapor and is prebaked prior to sampling, there is still sufficient residual moisture in the prebaked gel to dilute the relatively small amount of sampled moisture; thereby, significantly lowering the 'true' tritium concentration in the soil gas. This paper provides an evaluation of the magnitude of the bias from dilution, provides methods to correct past measurements by applying a correction factor (CF), and evaluates the uncertainty of the CF values. For this, ten-thousand Monte Carlo calculations were perfonned and distribution parameters of CF values were detennined and evaluated. The mean and standard deviation of the distribution of CF values were 1.53 {+-} 0.36, and the minimum, median, and maximum values were 1.14, 1.43, and 5.27, respectively.
Whicker, Jeffrey [Los Alamos National Laboratory; Dewart, Jean M [Los Alamos National Laboratory; Allen, Shannon P [Los Alamos National Laboratory; Eisele, William F [Los Alamos National Laboratory; Mcnaughton, Michael C [Los Alamos National Laboratory; Green, Andrew A [Los Alamos National Laboratory
Pore size effects on the sorption of supercritical carbon dioxide in mesoporous CPG-10 silica
Excess sorption isotherms of supercritical carbon dioxide in mesoporous CPG-10 silica glasses with nominal pore sizes of 75 (7.5 nm) and 350 (35 nm) were measured gravimetrically at 35 C and 50 C and pressures of 0-200 bar. Formation of broad maxima in the excess sorption was observed at fluid densities below the bulk critical density. Positive values of excess sorption were measured at bulk densities below about 0.65-0.7 g/cm3, whereas zero and negative values were obtained at higher densities, indicating that the interfacial fluid becomes less dense than the corresponding bulk fluid at high fluid densities. A shift of the excess sorption peak position to higher fluid density is found with increasing pore width. The excess sorption of CO2 normalized to the specific surface area is higher for the 35 nm pore size material, suggesting pore confinement effects. Conversely, the pore volume normalized excess sorption is higher for the 7.5 nm pore size material. Assessment of mean pore density reveals regions of constant pore fluid density, located between the excess sorption peak and the adsorption/depletion transition. Both materials exhibit such regions of constant mean pore fluid density as a function of bulk CO2 density at the lower temperature of 35 C, but not at 50 C. The results of this study suggest that the CO2 storage capacity in quartz-rich reservoirs is higher for sites with low temperature and rock textures characterized by narrow pores with high surface to volume ratios.
Rother, Gernot [ORNL; Krukowski, Elizabeth G [ORNL; Wallacher, Dirk [Helmholtz-Zentrum Berlin; Grimm, Nico [Helmholtz-Zentrum Berlin; Bodnar, Robert J [ORNL; Cole, David [Ohio State University
The Deep-Sea Natural Products, Biogenic Polyphosphate (Bio-PolyP) and Biogenic Silica (Bio-Silica), as Biomimetic Scaffolds for Bone Tissue Engineering: Fabrication of a Morphogenetically-Active Polymer
Abstract: Bone defects in human, caused by fractures/nonunions or trauma, gain increasing impact and have become a medical challenge in the present-day aging population. Frequently, those fractures require surgical intervention which ideally relies on autografts or suboptimally on allografts. Therefore, it is pressing and likewise challenging to develop bone substitution materials to heal bone defects. During the differentiation of osteoblasts from their mesenchymal progenitor/stem cells and of osteoclasts from their hemopoietic precursor cells, a lineage-specific release of growth factors and a trans-lineage homeostatic cross-talk via signaling molecules take place. Hence, the major hurdle is to fabricate a template that is functioning in a way mimicking the morphogenetic, inductive role(s) of the native extracellular matrix. In the last few years, two naturally occurring polymers that are produced by deep-sea sponges, the biogenic polyphosphate (bio-polyP) and biogenic silica (bio-silica) have also been identified as promoting morphogenetic on both osteoblasts andMar. Drugs 2013, 11 719
Xiaohong Wang; Heinz C. Schr�der; Qingling Feng; Florian Draenert; Werner E. G. M�ller
The Effects of Using Alkali-Silica Reaction Affected Recycled Concrete Aggregate in Hot Mix Asphalt
The effects of using alkali-silica reaction (ASR) affected recycled concrete aggregate (ASR-RCA) in hot mix asphalt (HMA) were investigated in this study. Dilatometer and modified beam tests were performed to determine the possibility of new ASR occurring in reactive aggregates within the HMA or re-expansion of existing gel. The Lottman test and micro-calorimeter were used to determine the moisture susceptibility of HMA made with ASR-RCA. A differential scanning calorimeter (DSC) with thermogravimetric analysis (TGA) was used to evaluate the drying of an artificial gel and x-ray diffraction (XRD) was used to check for the potential presence of gel in the filler fraction of the ASR-RCAs. Micro-deval and freeze-thaw tests were evaluated for their potential to indicate the presence of excess micro-cracks or ASR gel. Expansion testing indicated that both ASR-RCAs were still reactive with 0.5 N NaOH solution saturated with calcium hydroxide (CH) at 60 degrees C. Dilatometer testing of HMA specimens in NaOH CH solution at 60 degrees C indicated a reaction between the asphalt binder and the solution, but little, if any, ASR. The lack of expansion in the modified beam test supports the binder-solution interaction. However, dilatometer testing in deicer solution at the same temperature indicated that some ASR may have occurred along with the primary binder-solution interaction. The volume change characteristics associated with the binder-solution interaction with and without ASR was supported by the change in pH and alkali concentration of the test solution. DSC/TGA testing indicated that the artificial gel dehydrated at approximately 100 degrees C. XRD analysis of the filler indicated that some gel may have accumulated in this fraction. Moisture damage testing indicated good resistance to moisture damage by HMA mixtures made with ASR-RCA especially compared to a virgin siliceous aggregate. Micro-deval and freeze-thaw tests can detect the presence of micro-cracks due to ASR in ASR-RCAs as higher mass loss than the virgin aggregate. The potential distress mechanisms that may occur when using ASR-RCA in an HMA pavement were identified. Results obtained using accelerated laboratory conditions were extrapolated based on anticipated field conditions. Guidelines for the mitigation of potential distresses in HMA made with ASR-RCA are presented.
Geiger, Brian James
Structural Assessment of D-Regions Affected by Alkali-Silica Reaction/Delayed Ettringite Formation
A combined experimental and analytical program was conducted to investigate the effects of Alkali-Silica Reaction (ASR) and Delayed Ettringite Formation (DEF) on D-regions in reinforced concrete (RC) bridge bents. Four large-scale RC specimens, which represent cantilever and straddle bents in Texas bridges in each specimen, were constructed. The first specimen represented the unexposed control specimen, while the other three were conditioned in the field with supplemental watering to promote ASR/DEF and served as the exposed specimens. The control and two exposed specimens with various levels of ASR/DEF, after eight months and two years of field conditioning, were load tested to failure. The last specimen remains in field with additional exposure to promote ASR/DEF and will be load tested in future studies. The width and length of preload-induced cracks and developing cracks that initiated in the exposed specimens and grew over time, indicating concrete expansion due to ASR/DEF mechanisms, were measured. Petrographic analysis results of concrete cores extracted from the exposed specimens after their load testing confirmed the formation of ASR gel and minimum accumulation of ettringite. The structural testing results showed that the failure mechanism in all three tested specimens was due to a brittle shear failure in the beam-column joint. However, slightly greater stiffness, strength, and ductility were observed in the exposed specimens as a result of the activation of the reinforcing steel in the specimens due to the expansion of the concrete primarily from ASR, which effectively prestressed and confined the core concrete. Sectional analysis and Strut-and-Tie Modeling (STM) of the experimental specimens were applied. Three-dimensional nonlinear Finite Element Analyses (FEA) were also conducted to numerically simulate the overall structural performance, internal response, and out-of-plane behavior of the experimental specimens. The effects of varying constitutive relations of the concrete in tension on models of the specimens were compared with the measured experimental response. A method to mimic ASR/DEF effects on exposed specimens was proposed and incorporated into the FEA approach. As a result, forces that prestress and confine the core concrete were effectively applied through the reinforcing steel prior to subsequent structural loading. The three-dimensional FEA approach was able to simulate the out-of-plane behavior of the beam-column joint and the proposed method yielded comparable results with the measured overall and internal behavior of specimens.
Liu, Shih-Hsiang 1979-
Experimental and numerical study of the effective thermal conductivity of silica nanocomposites with thermal boundary resistance
The thermal interface resistance at the macro scale is mainly described by the physical gap between two interfaces and constriction resistance due to this gap. The small gaps between the two material faces makes up the majority of thermal interface resistance at the macro scale. So, most of the studies have been focused on characterizing effect of surface geometry and material properties to thermal interface resistance. This resistance is more widely known as thermal contact resistance, represented with Rc. There are various models to predict thermal contact resistance at macro scale. These models predict thermal resistance Rc for given two materials by utilizing their bulk thermomechanical properties. Although, Rc represents thermal resistance accurately for macro size contacts between two metals, it is not suitable to describe interface resistance of particles in modern TIMs, aka particulate composites. The particles inside recently available TIMs are micron size and with effort to further increase surface area this particle size is approaching nano scale. At this small scale, Rc does not accurately predict thermal interface, as it is very difficult to characterize the surface topography. The thermal discontinuity at perfectly bonded interface of two dissimilar materials is termed as thermal boundary resistance (Rb) or Kapitza resistance. The macroscopic assumptions that thermal discontinuity only exists due to gaps and surface geometry leads to substantial error in determining interface thermal properties at micron and nano scale. The phenomenon of thermal boundary resistance is an inherent material property and arises due to fundamental mechanism of thermal transport. For metal-matrix particulate composites, Rb plays more important role than Rc. The free flowing nature of the polymer would eliminate most of the gaps between the two materials at their interface. This means almost all of the thermal resistance at particle/matrix interface would occur due to Rb. The current study presents experimental study of thermal boundary resistance for silica nano particles embedded inside epoxy resin. The bulk conductivity of the sample is measured and Rc is back calculated using Hasselman-Johnson s (H-J) equation. The numerical validation of the equation is also presented, including extrapolation study to predict effective conductivity of the nanocomposite TIM.
Kothari, Rushabh M [ORNL; Dinwiddie, Ralph Barton [ORNL; Wang, Hsin [ORNL
Compressive Creep Performance and High Temperature Dimensional Stability of Conventional Silica Refractories
Furnace designers and refractory engineers recognize that optimized furnace superstructure design and refractory selection are needed as glass production furnaces are continually striving toward greater output and efficiencies. Harsher operating conditions test refractories to the limit, while changing production technology (such as the conversion to oxy-fuel from traditional air-fuel firing) can alter the way the materials perform. Refractories for both oxy- and air-fuel fired furnace superstructures are subjected to high temperatures during service that may cause them to excessively creep or subside if the refractory material is not creep resistant, or if it is subjected to high stress, or both. Furnace designers can ensure that superstructure structural integrity is maintained if the creep behavior of the refractory material is well understood and well represented by appropriate engineering creep models. Several issues limit the abilities of furnace designers to (1) choose the optimum refractory for their applications, (2) optimize the engineering design, or (3) predict the service mechanical integrity of their furnace superstructures. Published engineering creep data are essentially non-existent for almost all commercially available refractories used for glass furnace superstructures. The limited data that do exist are supplied by the various refractory suppliers. Unfortunately, these suppliers generally have different ways of conducting their mechanical testing and they also interpret and report their data differently; this makes it hard for furnace designers to draw fair comparisons between competing grades of candidate refractories. Furthermore, the refractory supplier's data are often not available in a form that can be readily used for furnace design and for the prediction and design of long-term structural integrity of furnace superstructures. With the aim of providing such comparable data, the US DOE's Office of Industrial Technology and its Advanced Industrial Materials program is sponsoring work to conduct creep testing and analysis on refractories of interest to the glass industry. An earlier stage of the project involved identifying which refractories to test and this is described elsewhere. Conventional silica was one such identified refractory category, and the present report describes the creep behavior of this class of refractories. To portray a more complete understanding of how these refractories perform at service temperatures, their fundamental corrosion resistances, dimensional stabilities, and microstructure were characterized as well.
Karakus, M.; Kirkland, T.P.; Liu, K.C.; Moore, R.E.; Pint, B.A.; Wereszczak, A.A.
Cathodoluminescence microscopy and petrographic image analysis of aggregates in concrete pavements affected by alkali-silica reaction
Various microscopic techniques (cathodoluminescence, polarizing and electron microscopy) were combined with image analysis with the aim to determine a) the modal composition and degradation features within concrete, and b) the petrographic characteristics and the geological types (rocks, and their provenance) of the aggregates. Concrete samples were taken from five different portions of Highway Nos. D1, D11, and D5 (the Czech Republic). Coarse and fine aggregates were found to be primarily composed of volcanic, plutonic, metamorphic and sedimentary rocks, as well as of quartz and feldspar aggregates of variable origins. The alkali-silica reaction was observed to be the main degradation mechanism, based upon the presence of microcracks and alkali-silica gels in the concrete. Use of cathodoluminescence enabled the identification of the source materials of the quartz aggregates, based upon their CL characteristics (i.e., color, intensity, microfractures, deformation, and zoning), which is difficult to distinguish only employing polarizing and electron microscopy. - Highlights: Black-Right-Pointing-Pointer ASR in concrete pavements on the Highways Nos. D1, D5 and D11 (Czech Republic). Black-Right-Pointing-Pointer Cathodoluminescence was combined with various microscopic techniques and image analysis. Black-Right-Pointing-Pointer ASR was attributed to aggregates. Black-Right-Pointing-Pointer Source materials of aggregates were identified based on cathodoluminescence characteristics. Black-Right-Pointing-Pointer Quartz comes from different volcanic, plutonic and metamorphic parent rocks.
Stastna, A., E-mail: firstname.lastname@example.com [Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Praha 2 (Czech Republic); Sachlova, S.; Pertold, Z.; Prikryl, R. [Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Praha 2 (Czech Republic); Leichmann, J. [Department of Geological Sciences, Faculty of Science, Masaryk University in Brno, Kotlarska 267/2, 611 37 Brno (Czech Republic)
Nanoporous Polytetrafluoroethylene/Silica Composite Separator as a High-Performance All-Vanadium Redox Flow Battery Membrane
Driven by the motivation of searching for low-cost membrane alternatives, a novel nanoporous polytetrafluoroethylene/silica composite separator has been prepared and evaluated for its use in all-vanadium mixed-acid redox flow battery. This separator consisting of silica particles enmeshed in a polytetrafluoroethylene fibril matrix has no ion exchange capacity and is featured with unique nanoporous structures, which function as the ion transport channels in redox flow battery operation, with an average pore size of 38nm and a porosity of 48%. This separator has produced excellent electrochemical performance in the all-vanadium mixed-acid system with energy efficiency delivery comparable to Nafion membrane and superior rate capability and temperature tolerance. The separator also demonstrates an exceptional capacity retention capability over extended cycling, offering additional operational latitude towards conveniently mitigating the capacity decay that is inevitable for Nafion. Because of the inexpensive raw materials and simple preparation protocol, the separator is particularly low-cost, estimated to be at least an order of magnitude more inexpensive than Nafion. Plus the proven chemical stability due to the same backbone material as Nafion, this separator possesses a good combination of critical membrane requirements and shows great potential to promote market penetration of the all-vanadium redox flow battery by enabling significant reduction of capital and cycle costs.
Wei, Xiaoliang; Nie, Zimin; Luo, Qingtao; Li, Bin; Chen, Baowei; Simmons, Kevin L.; Sprenkle, Vincent L.; Wang, Wei
Experimental study of the performance of a laminar flow silica gel desiccant packing suitable for solar air conditioning application
An experimental study of the performance of a low pressure drop silica gel desiccant packing has been carried out. The packing is in the form of narrow passages lined with a single layer of small silica gel particles. A near optimum particle size of 0.25 mm, and a range of passage widths of 1.46 to 3.75 mm were chosen based on the predictions of a computer simulation model. A test chamber was constructed with sufficient thermal insulation to allow close to adiabatic conditions for the 12 cm x 12 cm cross section of packing. Step change adsorption and desorption tests were performed for various plate spacings, air flow rates, air inlet conditions, and gel initial water contents. Air outlet moisture content and temperature, as well as pressure drop were measured. The experimental results were compared with predictions of the computer simulation model: This model is based on gas side controlled heat and mass transfer, with the small solid side mass transfer resistance incorporated in a crude manner, and heat transfer into the packing handled as a lumped thermal capacitance. Reasonable agreement was obtained between theoretical prediction and experiment. The match was found to improve with increased passage width. The discrepancies are chiefly attributed to an excessive air bypass, and to inaccurate accounting for heat transfer from the sides of the unit. Use of the computer code for prototype scale design purposes is recommended.
Biswas, P.
Mesoporous Silica with Site-Isolated Amine and Phosphotungstic Acid Groups: A Solid Catalyst with Tunable Antagonistic Functions for One-Pot Tandem Reactions
A bifunctional solid catalyst is prepared by combining acid and base functions on mesoporous silica supports. The co-existence of these functions is shown by a two-step reaction sequence in one pot. Excellent product yields, which cannot be obtained by separated acid and base functions in one pot, show the validity of our concept.
Shiju N. R.; Syed K.; Alberts A.; Brown D. and Rothenberg G.
Aerogels: stiff foams composed of up to 99.8% air Silica aerogel is the world's lowest-density solid: 1 mg/cm3
#12;Aerogels: stiff foams composed of up to 99.8% air Silica aerogel is the world's lowest-density solid: 1 mg/cm3 Aerogels hold 15 different records for material properties, including best insulator 2.38 g piece of aerogel supports a 2.5 kg brick. #12;#12;#12;l = m �? n unit vector in orbital space
Fominov, Yakov
Formation of mesoporous materials from silica dissolved in various NaOH concentrations: effect of pH and ionic strength
We describe the effects of NaOH/SiO2 ratio and pH on the formation of mesoporous materials, which was synthesized via an alkalimetal hydroxide fusion method, from amorphous silica dissolved in NaOH. Physical properties (e.g., specific surface ...
Jayhyun Park; Yosep Han; Hyunjung Kim
The sorption of thorium, protacintium and plutonium onto silica particles in the presence of a colloidal third phase
The fate of actinides in the environment is of interest for a several reasons. In oceanic surface waters actinides such as thorium and protactinium, and in particular their ratio, are used as tracers of processes such as boundary scavenging and paleocirculation. Thorium is also used to estimate residence times and particle and colloid fluxes from the euphotic zone, which is useful in global carbon budgets used to assess effects of global warming. Terrestrially, contaminated areas in need of remediation, such as former nuclear weapons production facilities, remain as repositories for no longer needed actinide stockpiles or waste by-products such as plutonium. All three of these actinides: thorium, protactinium, and plutonium are known to be particle-reactive but the extent to which they sorb to immobile particles and mobile colloids can vary with environmental conditions. Understanding controls on adsorption is important in understanding uses and any limitations of these radioactive tracers caused by colloids. Often laboratory studies to understand actinide behavior are conducted at concentrations (micro- to millimolar), which are orders of magnitude higher than they are found in the environment (femto- to picomolar). Colloids, a size class of particles operationally defined as 1 nm to 1 �m in size, are ubiquitous in aquatic systems. The effect colloids have on actinide particle association, i.e. competitive or enhancing, can have a profound influence on the ultimate behavior of the actinide. The overall aim of this study is to assess sorption of thorium, protactinium and plutonium onto silica particles as a proxy for inorganic particles found in surface or ocean waters. In addition to the binary system of actinide/silica, the ternary system actinide/ organic colloid/ silica were also carried out to determine the affect of the organic colloid has on particle association. In particular, extracellular polymeric substances (EPS) extracted from laboratory grown bacteria and phytoplankton cultures were utilized as they too are ubiquitous in aquatic systems and have shown to strongly complex actinide ions, with EPS involved in oceanic scavenging of Th, as well as immobilization/mobilization of Pu in contaminated areas on land.
Roberts, Kimberly Ann
Drug delivery from hydrophobic-modified mesoporous silicas: Control via modification level and site-selective modification
Dimethylsilyl (DMS) modified mesoporous silicas were successfully prepared via co-condensation and post-grafting modification methods. The post-grafting modification was carried out by the reaction of the as-synthesized MCM-41 material (before CTAB removal) with diethoxydimethylsinale (DEDMS). N{sub 2} adsorption-desorption and {sup 29}Si MAS NMR characterization demonstrated that different amount of DMS groups were successfully incorporated into the co-condensation modified samples, and the functional DMS groups were placed selectively on the pore openings and external pore surfaces in the post-grafting modified samples. Subsequently, the controlled drug delivery properties from the resulting DMS-modified mesoporous silicas were investigated in detail. The drug adsorption experiments showed that the adsorption capacities were mainly depended on the content of silanol group (CSG) in the corresponding carriers. The in vitro tests exhibited that the incorporation of DMS groups greatly retarded the ibuprofen release rate. Moreover, the ibuprofen release profiles could be well modulated by varying DMS modification levels and site-selective distribution of functional groups in mesoporous carriers. - The distribution of DMS groups on the pore surfaces of the mesostructures strongly affects the drug release rate. The P-M41-1 and the P-M41-2 possess the close DMS modification levels as the C-M41-10, but the ibuprofen release rates from the P-M41-1 and P-M41-2 are much slower than that from the C-M41-10.
Tang Qunli, E-mail: firstname.lastname@example.com [College of Materials Science and Engineering, and Center for High-Resolution Electron Microscopy, Hunan University, Changsha 410082 (China); State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China); Chen Yuxi; Chen Jianghua; Li Jin [College of Materials Science and Engineering, and Center for High-Resolution Electron Microscopy, Hunan University, Changsha 410082 (China); Xu Yao; Wu Dong; Sun Yuhan [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001 (China)
Comparison of laser-based mitigation of fused silica surface damage using mid- versus far-infrared lasers
Laser induced growth of optical damage can limit component lifetime and therefore operating costs of large-aperture fusion-class laser systems. While far-infrared (IR) lasers have been used previously to treat laser damage on fused silica optics and render it benign, little is known about the effectiveness of less-absorbing mid-IR lasers for this purpose. In this study, they quantitatively compare the effectiveness and efficiency of mid-IR (4.6 {micro}m) versus far-IR (10.6 {micro}m) lasers in mitigating damage growth on fused silica surfaces. The non-linear volumetric heating due to mid-IR laser absorption is analyzed by solving the heat equation numerically, taking into account the temperature-dependent absorption coefficient {alpha}(T) at {lambda} = 4.6 {micro}m, while far-IR laser heating is well-described by a linear analytic approximation to the laser-driven temperature rise. In both cases, the predicted results agree well with surface temperature measurements based on infrared radiometry, as well as sub-surface fictive temperature measurements based on confocal Raman microscopy. Damage mitigation efficiency is assessed using a figure of merit (FOM) relating the crack healing depth to laser power required, under minimally-ablative conditions. Based on their FOM, they show that for cracks up to at least 500 {micro}m in depth, mitigation with a 4.6 {micro}m mid-IR laser is more efficient than mitigation with a 10.6 {micro}m far-IR laser. This conclusion is corroborated by direct application of each laser system to the mitigation of pulsed laser-induced damage possessing fractures up to 225 {micro}m in depth.
Yang, S T; Matthews, M J; Elhadj, S; Cooke, D; Guss, G M; Draggoo, V G; Wegner, P J
A density functional theory study of the oxidation of methanol to formaldehyde over vanadia supported on silica, titania, and zirconia
Density functional theory was used to investigate the mechanism and kinetics of methanol oxidation to formaldehyde over vanadia supported on silica, titania, and zirconia. The catalytically active site was modeled as an isolated VO{sub 4} unit attached to the support. The calculated geometry and vibrational frequencies of the active site are in good agreement with experimental measurements both for model compounds and oxide-supported vanadia. Methanol adsorption is found to occur preferentially with the rupture of a V-O-M bond (M = Si, Ti, Zr) and with preferential attachment of a methoxy group to V. The vibrational frequencies of the methoxy group are in good agreement with those observed experimentally as are the calculated isobars. The formation of formaldehyde is assumed to occur via the transfer of an H atom of a methoxy group to the O atom of the V=O group. The activation energy for this process is found to be in the range of 199-214 kJ/mol and apparent activation energies for the overall oxidation of methanol to formaldehyde are predicted to lie in the range of 112-123 kJ/mol, which is significantly higher than that found experimentally. Moreover, the predicted turnover frequency (TOF) for methanol oxidation is found to be essentially independent of support composition, whereas experiments show that the TOF is 10{sup 3} greater for titania- and zirconia-supported vanadia than for silica-supported vanadia. Based on these findings, it is proposed that the formation of formaldehyde from methoxy groups may require pairs of adjacent VO{sub 4} groups or V{sub 2}O{sub 7} dimer structures.
Khaliullin, Rustam Z.; Bell, Alexis T.
Geothermometry At Raft River Geothermal Area (1980) | Open Energy
Geothermometry At Raft River Geothermal Area (1980) Geothermometry At Raft River Geothermal Area (1980) Exploration Activity Details Location Raft River Geothermal Area Exploration Technique Geothermometry Activity Date 1980 Usefulness not indicated DOE-funding Unknown Notes Geothermometer temperatures of shallow samples suggest significant re-equilibration at temperatures below those found in the deep wells. Silica geothermometer temperatures of water samples from the deep wells are in reasonable agreement with measured temperatures, whereas Na-K-Ca temperatures are significantly higher than measured temperatures. The chemical characteristics of the water, as indicated by chloride concentration, are extremely variable in shallow and deep samples. Chloride concentrations of the deep samples range from 580 to 2200 mg/kg.
Geothermometry At Desert Queen Area (Garchar & Arehart, 2008) | Open Energy
Queen Area (Garchar & Arehart, 2008) Queen Area (Garchar & Arehart, 2008) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Geothermometry At Desert Queen Area (Garchar & Arehart, 2008) Exploration Activity Details Location Desert Queen Area Exploration Technique Geothermometry Activity Date Usefulness not indicated DOE-funding Unknown Notes Temperatures of the reservoir at depth are estimated to be between 92-141 degrees C and were calculated using the δ18O(SO4-H2O) geothermometer. It is unclear whether these temperatures reflect waters from the outflow zone of the Desert Peak geothermal system, or waters from a different reservoir at Desert Queen. Quartz, chalcedony, amorphous silica, Na-K-Ca, and δ18O(SO4-H2O) geothermometer calculations were performed.
SERI Desiccant Cooling Test Facility. Status report. Preliminary data on the performance of a rotary parallel-passage silica-gel dehumidifier
This report describes the SERI Desiccant Cooling Test Facility. The facility can test bench-scale rotary dehumidifiers over a wide range of controlled conditions. We constructed and installed in the test loop a prototype parallel-passage rotary dehumidifier that has spirally wound polyester tape coated with silica gel. The initial tests gave satisfactory results indicating that approximately 90% of the silica gel was active and the overall Lewis number of the wheel was near unity. The facility has several minor difficulties including an inability to control humidity satisfactorily and nonuniform and highly turbulent inlet velocities. To completely validate the facility requires a range of dehumidifier designs. Several choices are available including constructing a second parallel-passage dehumidifier with the passage spacing more uniform.
Schultz, K.J.
Remaining Sites Verification Package for the 100-F-44:4, Discovery Pipeline in Silica Gel Pit, Waste Site Reclassification Form 2008-030
The 100-F-44:4, Discovery Pipeline in Silica Gel Pit subsite is located in the 100-FR-1 Operable Unit of the Hanford Site, near the location of the former 110-F Gas Storage Tanks structure. The 100-F-44:4 subsite is a steel pipe discovered October 17, 2004, during trenching to locate the 118-F-4 Silica Gel Pit. Based on visual inspection and confirmatory investigation sampling data, the 100-F-44:4 subsite is a piece of non-hazardous electrical conduit debris. The 100-F-44:4 subsite supports unrestricted future use of shallow zone soil and is protective of groundwater and the Columbia River. No residual contamination exists within the deep zone. Therefore, no deep zone institutional controls are required.
J. M. Capron
On-line tests of organic additives for the inhibition of the precipitation of silica from hypersaline geothermal brine IV. Final tests of candidate additives
The Lawrence Livermore Laboratory Brine Treatment Test System at Niland, Imperial Valley, California, has been used to evaluate a number of cationic polymers and surfactants as scale control agents. An initial group of compounds was narrowed to four on the basis of their activity as silica precipitation inhibitors. Three of these and certain combinations of compounds were then given a 40-h test to determine their effectiveness in retarding scales formed at 220, 125, and 90/sup 0/C. The best single compound was Corcat P-18 (Cordova Chemical Co. polyethylene imine, M.W. approx. = 1800). It had no effect on the scale at 220/sup 0/C, but it reduced the scales at 125 and 90/sup 0/C by factors of 4 and 18, respectively, and it also has activity as a corrosion inhibitor. Other promising compounds are PAE HCl (Dynapol poly(aminoethylene, HCl salt)), which also somewhat reduces the 220/sup 0/C scale; Ethoquad 18/25 (Armak methyl polyoxyethylene(15) octadecylammonium chloride); and Mirapol A-15 (a Miranol Chemical polydiquaternary compound). The best additive formulation for the brines of the Salton Sea Geothermal Field appears to be a mixture of one of these silica precipitation inhibitors with a small amount of hydrochloric acid and a phosphonate crystalline deposit inhibitor. Speculations are presented as to the mechanism of inhibition of silica precipitation and recommendations for further testing of these additives.
Harrar, J.E.; Locke, F.E.; Otto, C.H. Jr.; Lorensen, L.E.; Frey, W.P.; Snell, E.O.
Visible Light Absorption of Binuclear TiOCoII Charge-Transfer UnitAssembled in Mesoporous Silica
Grafting of CoII(NCCH3)2Cl2 onto mesoporous Ti-MCM-41 silicain acetonitrile solution affords binuclear Ti-O-CoII sites on the poresurface under complete replacement of the precursor ligands byinteractions with anchored Ti centers and the silica surface. The CoIIligand field spectrum signals that the Co centers are anchored on thepore surface in tetrahedral coordination. FT-infrared action spectroscopyusing ammonia gas adsorption reveals Co-O-Si bond modes at 831 and 762cm-1. No Co oxide clusters are observed in the as-synthesized material.The bimetallic moieties feature an absorption extending from the UV intothe visible to about 600 nm which is attributed to the TiIV-O-CoII?3TiIII-O-CoIII metal-to-metal charge-transfer (MMCT) transition. Thechromophore is absent in MCM-41 containing Ti and Co centers isolatedfrom each other; this material was synthesized by grafting CoII onto aTi-MCM-41 sample with the Ti centers protected by a cyclopentadienylligand. The result indicates that the appearance of the charge-transferabsorption requires that the metal centers are linked by an oxo bridge,which is additionally supported by XANES spectroscopy. The MMCTchromophore of Ti-O-CoII units has sufficient oxidation power to serve asvisible light electron pump for driving multi-electron transfer catalystsof demanding uphill reactions such as water oxidation.
Han, Hongxian; Frei, Heinz
Trace element and REE composition of five samples of the Yucca Mountain calcite-silica deposits. Special report No. 8
The attached materials document the results of part of a recent effort of geochemical sampling and analysis at Yucca Mountain and nearby regions. The efforts come as a result of interest in comprehensive analyses of rare earth elements (REE), lanthanum (La) through lutecium (Lu). Several additional, non-REE analyses were obtained as well. Commercially available REE analyses have proved to be insufficiently sensitive for geochemical purposes. Dr. Roman Schmitt at the Radiation Center at Oregon State University in Corvallis was sent five samples as a trial effort. The results are very encouraging. The purpose of compiling Dr. Schmitt`s report and the other materials is to inform the sponsor of his independent observations of these results and other information that sent to him. To provide a more complete appreciation of the utility of REE analyses a copy of Dave Vaniman`s recent article is included in which he notes that REE analyses from Yucca Mountain indicate the occurrence of two distinctly different REE patterns as do several other chemical parameters of the calcite-silica deposits. Our four samples with high equivalent CaCO{sub 3} were collected from sites we believe to be spring deposits. One sample, 24D, is from southern Crater Flat which is acknowledged by U.S.G.S. investigators to be a spring deposit. All four of these samples have REE patterns similar to those from the saturated zone reported by Vaniman.
Livingston, D.
Synthesis of Through-bond Energy Transfer Cassettes and Their Encapsulation in Silica and Calcium Phosphate Nanoparticles
Water-soluble fluorescent probes with emission in the 600-800 nm region have significant potential in biological applications such as cell imaging. Most fluorescent probes however suffer from limited fluorescence brightness in aqueous media due to aggregation and self-quenching. Their photostability in animal models for an extended period of time is also a concern. One way of improving their photophysical properties is to encapsulate them in a protective matrix to form fluorescent nanoparticles. We have synthesized a set of six through-bond energy transfer cassettes which emit in the 600-800 nm region with Fluorescein or BODIPY as donor and benzophenoxazine dye Nile Red or cyanine dye Cy5 as acceptor. Their photophysical properties in organic and aqueous media were evaluated. Some of these cassettes were encapsulated in silica or calcium phosphate nanoparticles (20 nm in diameter) to improve their solubility and photophysical properties in aqueous media. We also synthesized some water-soluble benzophenoxazine based fluorophores and the impact of different water-soluble groups on their emission characteristics in aqueous media was studied. Selected fluorophores were used for in vitro cellular imaging studies.
Jose, Jiney
Quantitative planar laser-induced fluorescence imaging of multi-component fuel/air mixing in a firing gasoline-direct-injection engine: Effects of residual exhaust gas on quantitative PLIF
A study of in-cylinder fuel-air mixing distributions in a firing gasoline-direct-injection engine is reported using planar laser-induced fluorescence (PLIF) imaging. A multi-component fuel synthesised from three pairs of components chosen to simulate light, medium and heavy fractions was seeded with one of three tracers, each chosen to co-evaporate with and thus follow one of the fractions, in order to account for differential volatility of such components in typical gasoline fuels. In order to make quantitative measurements of fuel-air ratio from PLIF images, initial calibration was by recording PLIF images of homogeneous fuel-air mixtures under similar conditions of in-cylinder temperature and pressure using a re-circulation loop and a motored engine. This calibration method was found to be affected by two significant factors. Firstly, calibration was affected by variation of signal collection efficiency arising from build-up of absorbing deposits on the windows during firing cycles, which are not present under motored conditions. Secondly, the effects of residual exhaust gas present in the firing engine were not accounted for using a calibration loop with a motored engine. In order to account for these factors a novel method of PLIF calibration is presented whereby 'bookend' calibration measurements for each tracer separately are performed under firing conditions, utilising injection into a large upstream heated plenum to promote the formation of homogeneous in-cylinder mixtures. These calibration datasets contain sufficient information to not only characterise the quantum efficiency of each tracer during a typical engine cycle, but also monitor imaging efficiency, and, importantly, account for the impact of exhaust gas residuals (EGR). By use of this method EGR is identified as a significant factor in quantitative PLIF for fuel mixing diagnostics in firing engines. The effects of cyclic variation in fuel concentration on burn rate are analysed for different fuel injection strategies. Finally, mixture distributions for late injection obtained using quantitative PLIF are compared to predictions of computational fluid dynamics calculations. (author)
Williams, Ben; Ewart, Paul [Department of Physics, Oxford University, Parks Road, Oxford OX1 3PU (United Kingdom); Wang, Xiaowei; Stone, Richard [Department of Engineering Science, Oxford University, Parks Road, Oxford OX1 3PJ (United Kingdom); Ma, Hongrui; Walmsley, Harold; Cracknell, Roger [Shell Global Solutions (UK), Shell Research Centre Thornton, P. O. Box 1, Chester, CH1 3SH (United Kingdom); Stevens, Robert; Richardson, David; Fu, Huiyu; Wallace, Stan [Jaguar Cars, Engineering Centre, Abbey Road, Whitley, Coventry, CV3 4LF (United Kingdom)
Combining Multicomponent Seismic Attributes, New Rock Physics Models, and In Situ Data to Estimate Gas-Hydrate Concentrations in Deep-Water, Near-Seafloor Strata of the Gulf of Mexico
The Bureau of Economic Geology was contracted to develop technologies that demonstrate the value of multicomponent seismic technology for evaluating deep-water hydrates across the Green Canyon area of the Gulf of Mexico. This report describes the methodologies that were developed to create compressional (P-P) and converted-shear (P-SV) images of near-seafloor geology from four-component ocean-bottom-cable (4C OBC) seismic data and the procedures used to integrate P-P and P-SV seismic attributes with borehole calibration data to estimate hydrate concentration across two study areas spanning 16 and 25 lease blocks (or 144 and 225 square miles), respectively. Approximately 200 km of two-dimensional 4C OBC profiles were processed and analyzed over the course of the 3-year project. The strategies we developed to image near-seafloor geology with 4C OBC data are unique, and the paper describing our methodology was peer-recognized with a Best Paper Award by the Society of Exploration Geophysicists in the first year of the project (2006). Among the valuable research findings demonstrated in this report, the demonstrated ability to image deep-water near-seafloor geology with sub-meter resolution using a standard-frequency (10-200 Hz) air gun array on the sea surface and 4C sensors on the seafloor has been the accomplishment that has received the most accolades from professional peers. Our study found that hydrate is pervasive across the two study areas that were analyzed but exists at low concentrations. Although our joint inversion technique showed that in some limited areas, and in some geologic units across those small areas, hydrates occupied up to 40-percent of the sediment pore space, we found that when hydrate was present, hydrate concentration tended to occupy only 10-percent to 20-percent of the pore volume. We also found that hydrate concentration tended to be greater near the base of the hydrate stability zone than it was within the central part of the stability zone.
Bureau of Economic Geology
Laser damage by ns and sub-ps pulses on hafnia/silica anti-reflection coatings on fused silica double-sided polished using zirconia or ceria and washed with or without an alumina wash step.
Sandia's Large Optics Coating Operation has extensive results of laser induced damage threshold (LIDT) testing of its anti-reflection (AR) and high reflection coatings on substrates pitch polished using ceria and washed in a process that includes an alumina wash step. The purpose of the alumina wash step is to remove residual polishing compound to minimize its role in laser damage. These LIDT tests are for multi longitudinal mode, ns class pulses at 1064 nm and 532 nm (NIF-MEL protocol) and mode locked, sub-ps class pulses at 1054 nm (Sandia measurements), and show reasonably high and adequate laser damage resistance for coatings in the beam trains of Sandia's Z-Backlighter terawatt and petawatt lasers. An AR coating in addition to coatings of our previous reports confirms this with LIDTs of 33.0 J/cm{sup 2} for 3.5 ns pulses and 1.8 J/cm{sup 2} for 350 fs pulses. In this paper, we investigate both ceria and zirconia in doublesided polishing (common for large flat Z-Backlighter laser optics) as they affect LIDTs of an AR coating on fused silica substrates washed with or without the alumina wash step. For these AR coated, double-sided polished surfaces, ceria polishing in general affords better resistance to laser damage than zirconia polishing and laser damage is less likely with the alumina wash step than without it. This is supported by specific results of laser damage tests with 3.5 ns, multi longitudinal mode, single shot pulses at 1064 nm and 532 nm, with 7.0 ns, single and multi longitudinal mode, single and multi shot pulses at 532 nm, and with 350 fs, mode-locked, single shot pulses at 1054 nm.
Bellum, John Curtis; Rambo, Patrick K.; Schwarz, Jens; Kletecka, Damon; Atherton, Briggs W.; Kimmel, Mark W.; Smith, Ian Craig; Smith, Douglas (Plymouth Grating Laboratory, Carver, MA); Hobbs, Zachary (Sydor Optics, Inc., Rochester, NY)
Synthesis of Silica Supported AuCu Nanoparticle Catalysts and the Effects of Pretreatment Conditions for the CO Oxidation Reaction
Supported gold nanoparticles have generated an immense interest in the field of catalysis due to their extremely high reactivity and selectivity. Recently, alloy nanoparticles of gold have received a lot of attention due to their enhanced catalytic properties. Here we report the synthesis of silica supported AuCu nanoparticles through the conversion of supported Au nanoparticles in a solution of Cu(C{sub 2}H{sub 3}O{sub 2}){sub 2} at 300 C. The AuCu alloy structure was confirmed through powder XRD (which indicated a weakly ordered alloy phase), XANES, and EXAFS. It was also shown that heating the AuCu/SiO{sub 2} in an O{sub 2} atmosphere segregated the catalyst into a Au-CuO{sub x} heterostructure between 150 C to 240 C. Heating the catalyst in H{sub 2} at 300 C reduced the CuO{sub x} back to Cu{sup 0} to reform the AuCu alloy phase. It was found that the AuCu/SiO{sub 2} catalysts were inactive for CO oxidation. However, various pretreatment conditions were required to form a highly active and stable Au-CuO{sub x}/SiO{sub 2} catalyst to achieve 100% CO conversion below room-temperature. This is explained by the in situ FTIR result, which shows that CO molecules can be chemisorbed and activated only on the Au-CuOx/SiO{sub 2} catalyst but not on the AuCu/SiO{sub 2} catalyst.
J Bauer; D Mullins; M Li; Z Wu; E Payzant; S Overbury; S Dai
Preliminary study of lead isotopes in the carbonate-silica veins of Trench 14, Yucca Mountain, Nevada
The sub-vertical carbonate-silica veins filling the Bow Ridge Fault, where exposed in Trench 14 on the east side of Yucca Mountain, carry a lead isotopic signature that can be explained in terms of local sources. Two isotopically distinguishable--silicate and carbonate--fractions of lead are recognized within the vein system as well as in overlying surficial calcrete deposits. The acid-insoluble silicate fraction is contributed largely from the decomposing Miocene volcanic tuff, which forms the wall rock of the fault zone and is a ubiquitous component of the overlying soil. Lead contained in the silicate fraction approaches in isotopic composition that of the Miocene volcanic rocks of Yucca Mountain, but diverges from it in some samples by being more enriched in uranogenic isotopes. The carbonate fraction of lead in both vein and calcrete samples resides dominantly in the HCl- and CH{sub 3}COOH-soluble calcite. HCl evidently also attacks and removes lead from silicate phases, but the milder CH{sub 3}COOH dissolution procedure oftentimes identifies a significantly more radiogenic lead in the calcite. Wind-blown particulate matter brought to the area from Paleozoic and Late Proterozoic limestones in surrounding mountains may be the ultimate source of the calcite. Isotopically more uniform samples suggest that locally the basaltic ash and other volcanic rock have contributed most of the lead to both fractions of the vein system. An important finding of this study is that the data does not require the more exotic mechanisms or origins that have been proposed for the veins. Instead, the remarkably similar lead isotopic properties of the veins to those of the soil calcretes support their interpretation as a surficial, pedogenic phenomenon.
Zartman, R.E.; Kwak, L.M.
Mass fractal characteristics of silica sonogels as determined by small-angle x-ray scattering and nitrogen adsorption
A sample series of silica sonogels was prepared using different water-tetraethoxysilane molar ratio (r{sub w}) in the gelation step of the process in order to obtain aerogels with different bulk densities after the supercritical drying. The samples were analyzed by means of small-angle x-ray-scattering (SAXS) and nitrogen-adsorption techniques. Wet sonogels exhibit mass fractal structure with fractal dimension D increasing from {approx}2.1 to {approx}2.4 and mass-fractal correlation length {xi} diminishing from {approx}13 nm to {approx}2 nm, as r{sub w} is changed in the nominal range from 66 to 6. The process of obtaining aerogels from sonogels and heat treatment at 500 deg. C, in general, increases the mass-fractal dimension D, diminishes the characteristic length {xi} of the fractal structure, and shortens the fractal range at the micropore side for the formation of a secondary structured particle, apparently evolved from the original wet structure at a high resolution level. The overall mass-fractal dimension D of aerogels was evaluated as {approx}2.4 and {approx}2.5, as determined from SAXS and from pore-size distribution by nitrogen adsorption, respectively. The fine structure of the 'secondary particle' developed in the obtaining of aerogels could be described as a surface-mass fractal, with the correlated surface and mass-fractal dimensions decreasing from {approx}2.4 to {approx}2.0 and from {approx}2.7 to {approx}2.5, respectively, as the aerogel bulk density increases from 0.25 (r{sub w}=66) up to 0.91 g/cm{sup 3} (r{sub w}=6)
Donatti, D.A.; Vollet, D.R.; Ibanez Ruiz, A.; Mesquita, A.; Silva, T.F.P. [Unesp-Universidade Estadual Paulista, IGCE, Departamento de Fisica, P.O. Box 178 CEP, 13500-970 Rio Claro, Sao Paulo (Brazil)
On-line tests of organic additives for the inhibition of the precipitation of silica from hypersaline geothermal brine II. Tests of nitrogen-containing compounds, silanes, and additional ethoxylated compounds
Several new classes of organic compounds have been screened as potential geothermal scale control agents by examining their effect on the precipitation of silica from Magmamax No. 1 brine. The substances were tested using the Lawrence Livermore Laboratory Brine Treatment Test System at the Niland, California, Test Site. Solutions of the test substances were injected into flowing brine at 210{sup 0}C, the brine was flashed to 125{sup 0}C, and then the kinetics of solids and silica precipitation from effluent brine held at 90{sup 0}C were measured. Three new types of compounds were shown to have activity as precipitation inhibitors: polyethylene imines, polyethyloxazalines, and quaternary ammonium compounds containing polyoxyethylene. Among the latter, Ethoquad 18/25, which is methyl-polyoxyethylene(15) octadecylammonium chloride, is the leading candidate antiscalant. It is a more powerful inhibitor of silica precipitation than the pure polyoxyethylene polymers, and it apparently has no high temperature solubility limitations. Measurements were made of the concentrations of monomeric silica and the effect of addition of inhibitor at various points in the Brine Treatment Test System. Five different silane compounds showed no activity toward silica.
Harrar, J.E.; Locke, F.E.; Otto, C.H. Jr.; Lorensen, L.E.; Frey, W.P.
Nature of =~SiOCrO(2)CI And (=~SiO)(2)CrO(2) Sites Prepared By Grafting CrO(2)CI(2) Onto Silica
The room-temperature reaction between chromyl chloride and Sylopol 952 silicas pretreated at 200, 450, and 800 C was investigated using IR, XANES, and EXAFS spectroscopy, as well as by DFT modeling. On the silicas pretreated at 200 and 450 C, the structurally uniform sites formed by the reaction with one surface hydroxyl group are described as {triple_bond}SiOCrO{sub 2}Cl. Unreacted silanols persist on these silicas even in the presence of excess CrO{sub 2}Cl{sub 2}, and on the silica pretreated at 200 C some participate in hydrogen bonding with the grafted monochlorochromate sites. On the silica pretreated at 800 C, both {triple_bond}SiOCrO{sub 2}Cl and ({triple_bond}SiO){sub 2}CrO{sub 2} sites are formed. The latter are produced despite the absence of hydrogen-bonded hydroxyl pairs on the support. The origin of the chromate sites is proposed to be the reaction between CrO{sub 2}Cl{sub 2} and hydroxyl-substituted siloxane 2-rings. These rings are likely formed at 800 C by condensation between a pair of vicinal silanols in which one of the silanols is also a member of a geminal pair.
Demmelmaier, C.A.; White, R.E.; Bokhoven, J.A.van; Scott, S.L.
Spreadsheets for Geothermal Water and Gas Geochemistry | Open...
and plots four common ternaries, three3 "YT" gas geothermometer grids and two gas ratio geothermometer grids, mainly derived from the work of Werner Giggenbach. Typical...
Spinodal decomposition in multicomponent polymer blends
... 10091, Ref. 28. 53 In previous studies by the Exxon/Princeton group on blends of ethylene� butene copolymers, Ref. 54 it ...
Reliable Thermodynamic Descriptions for Multicomponent Systems
Materials Genomics Past & Future: From CALPHAD to Flight � Microstructure Stability of Multi-Materials Systems with Adaptive Microstructures � Modeling of�...
The Thermodynamic Modeling of Multicomponent Phase Equilibria
Such identification does not imply recommendation or endorsement by the National ... In order to overcome the problem of the multidimensionality posed by a�...
Modeling TLP Bonding in Multicomponent Systems
... prior to bonding as well as the application of large loads during bonding. .... The profile given in equation (1) is thus appropriate for each of the solutes in the �...
Ductile Crack Investigation in Multicomponent Materials
At this stage of the research Authors proposed two scale numerical model. ... Optimization of Thermal Cycle for Rails with Respect to the Wear Resistance.
Optical characterization of n=1.03 silica aerogel used as radiator in the RICH of E. Aschenauer 9 , N. Bianchi 4 , G.P. Capitani 4 , P. Carter 3 , C Casalino 2 , E. Cisbani 6 , C. Coluzza 7 , R. De Leo 2;a ,
Optical characterization of n=1.03 silica aerogel used as radiator in the RICH of HERMES E Abstract The optical properties of silica aerogel tiles with a refractive index of 1.03 and dimensions 11, is completely interpretable as backscattering from inside the aerogel, revealing an absence of light reflection
Performance-based approach to evaluate alkali-silica reaction potential of aggregate and concrete using dilatometer method
The undesirable expansion of concrete because of a reaction between alkalis and certain type of reactive siliceous aggregates, known as alkali-silica reactivity (ASR), continues to be a major problem across the entire world. The renewed interest to minimize distress resulting from ASR has emphasized the need to develop predictable modeling of concrete ASR behavior under field conditions. Current test methods are either incapable or need long testing periods in which to only offer rather limited predictive estimates of ASR behavior in a narrow and impractical band of field conditions. Therefore, an attempt has been made to formulate a robust performance approach based upon basic properties of aggregate and concrete ASR materials derived from dilatometry and a kinetic-based mathematical expressions for ASR behavior. Because ASR is largely an alkali as well as a thermally activated process, the use of rate theory (an Arrhenius relationship between temperature and the alkali solution concentration) on the dilatometer time-expansion relationship, provides a fundamental aggregate ASR material property known as �activation energy.� Activation energy is an indicator of aggregate reactivity which is a function of alkalinity, particle size, crystallinity, calcium concentration, and others. The studied concrete ASR material properties represent a combined effects of mixture related properties (e.g., water-cementitious ratio, porosity, presence of supplementary cementitious materials, etc.) and maturity. Therefore, the proposed performance-based approach provides a direct accountability for a variety of factors that affect ASR, such as aggregate reactivity (activation energy), temperature, moisture, calcium concentration, solution alkalinity, and water-cementitious material ratio. Based on the experimental results, the following conclusion can be drawn concerning the performance-based approach to evaluate ASR potential of aggregate and concrete using dilatometer method; (i) the concept of activation energy can be used to represent the reactivity of aggregate subjected to ASR, (ii) the activation energy depends on the reactivity of aggregate and phenomenological alkalinity of test solution, and (iii) The proposed performance-based model provides a means to predict ASR expansion development in concrete.
Shon, Chang Seon
Dynamics of Propane in Silica Mesopores Formed upon PropyleneHydrogenation over Pt Nanoparticles by Time-Resolved FT-IRSpectroscopy
Propylene hydrogenation over Pt nanoparticles supported onmesoporous silica type SBA-15 was monitored by time-resolved FT-IRspectroscopy at 23 ms resolution using short propylene gas pulses thatjoined a continuous flow of hydrogen in N2 (1 atm total pressure).Experiments were conducted in the temperature range 323-413 K. Propanewas formed within 100 milliseconds or faster. The CH stretching regionrevealed distinct bands for propane molecules emerging inside thenanoscale channels of the silica support. Spectral analysis gave thedistribution of the propane product between support and surrounding gasphase as function of time. Kinetic analysis showed that the escape ofpropane molecules from the channels occurred within hundreds ofmilliseconds (3.1 + 0.4 s-1 at 383 K). A steady state distribution ofpropane between gas phase and mesoporous support is established as theproduct is swept from the catalyst zone by the continuous flow ofhydrogen co-reactant. This is the first direct spectroscopic observationof emerging products of heterogeneous catalysis on nanoporous supportsunder reaction conditions.
Waslylenko, Walter; Frei, Heinz
Quantifying Silica Reactivity in Subsurface Environments: Reaction Affinity and Solute Matrix Controls on Quartz and SiO2 Glass Dissolution Kinetics
During the three years of this project, Professor Dove's laboratory made tremendous progress in understanding controls on amorphous silica dissolution kinetics in aqueous solutions. Our findings have already received considerable attention. In hydrothermal and low temperature studies, the work focused on determining quantitative and mechanistic controls on the most abundant silica polymorphs in Earth environments--quartz and amorphous silica. Our studies achieved goals set forth in the original proposal to establish a new quantitative understanding of amorphous silica dissolution. This support has resulted in 10 journal, 12 abstracts and 2 thesis publications. The PI and students were also recognized with 6 awards during this period. The 1998 EMSP conference in Chicago was an important meeting for our project. The symposium, enabled P.I. Dove to establish valuable contacts with ''users'' having specific needs for the findings of our EMSP project related to the urgency of problems in the Tanks Focus Area (TFA). Since that time, our working relations developed as Dove interacted with TFA scientists and engineers on the problems of waste glass properties. These interactions refined our experimental objectives to better meet their needs. Dove presented the results of EMSP research findings to a TFA subgroup at a Product Acceptance Workshop held in Salt Lake City during December 1998. The travel costs to attend this unanticipated opportunity were paid from EMSP project funds. In January 2000, Dove also attended a similar meeting in Atlanta with PNNL, SRL and BNF scientists/engineers to discuss new issues and make another level of decisions on the Product Acceptance goals. Our EMSP-funded research interfaced very well with the ongoing studies of Dr. Pete McGrail and colleagues in the Applied Geochemistry Group at PNNL. The value of our work to ''users'' was further demonstrated when Dove's EMSP-funded Postdoc, Dr. Jonathan Icenhower was hired by the same PNNL group. With the Icenhower move from postdoc in the Dove lab to a senior scientist position at PNNL, we directly facilitated information transfer from the ''university to user'' environment. Icenhower brought experience in silica-water reactivity and the experimental expertise in high-quality methods of mineral-water reaction kinetics to the PNNL waste clean-up effort. In a further interaction, M.S. student Troy Lorier was hired at the Savannah River Laboratory for a staff position with the Bill Holtzcheiter glass group. His research meshed well with on-going efforts at SRL. In short, our EMSP project went well beyond the academic goals of producing high quality scientific knowledge to establish connections with on-site users to solve problems in TFA. This project also produced new talent for the waste immobilization effort. This EMSP project was highly successful and we thank our sponsors for the opportunity to advance scientific knowledge in this important area of research.
Patricia M. Dove
Kinetics of Silica Polymerization
All toge tion and energy conversion system design strategiesthe overall energy extraction and conversion system must beenergy conversion process may be tailored to reduce or eliminate The benefits of a binary system
Weres, Oleh
Preparation of silica aerogel using ionic liquids as solvents Sheng Dai,*a Y. H. Ju,ac H. J. Gao,b J. S. Lin,b S. J. Pennycookb and C. E. Barnesc
Preparation of silica aerogel using ionic liquids as solvents Sheng Dai,*a Y. H. Ju,ac H. J. Gaord December 1999 Ionic liquids have been used as effective solvents to synthesize aerogels; a long aging time can be used to produce stable aerogel structures without the need for supercritical drying
Gao, Hongjun
Numerical simulation study of silica and calcite dissolution around a geothermal well by injecting high pH solutions with chelating agent.
Dissolution of silica, silicate, and calcite minerals in the presence of a chelating agent (NTA) at a high pH has been successfully performed in the laboratory using a high-temperature flow reactor. The mineral dissolution and porosity enhancement in the laboratory experiment has been reproduced by reactive transport simulation using TOUGHREACT. The chemical stimulation method has been applied by numerical modeling to a field geothermal injection well system, to investigate its effectiveness. Parameters from the quartz monzodiorite unit at the Enhanced Geothermal System (EGS) site at Desert Peak (Nevada) were used. Results indicate that the injection of a high pH chelating solution results in dissolution of both calcite and plagioclase minerals, and avoids precipitation of calcite at high temperature conditions. Consequently reservoir porosity and permeability can be enhanced especially near the injection well.
Xu, Tianfu; Rose, Peter; Fayer, Scott; Pruess, Karsten
Time-resolved x-ray imaging of high-power laser-irradiated under-dense silica aerogels and agar foams
This paper presents the results of experiments in which a high-power laser was used to irradiate low density (4 - 9 mg/cm{sup 3}) silica aerogel and agar foam targets. The laser-solid interaction and energy transport through the material were monitored with time-resolved imaging diagnostics, and the data show the production and propagation of an x-ray emission front in the plasma. The emission-front trajectory data are found to be in significant disagreement with detailed simulations, which predict a much more rapid heating of the cold material, and the data suggest that this discrepancy is not explainable by target inhomogeneities. Evidence suggests that energy transport into the cold material may be dominated by thermal conduction; however, no completely satisfactory explanation for the discrepancies is identified, and further experimental and theoretical research is necessary in order to resolve this important problem in laser-plasma interaction physics.
Koch, J.A.; Estabrook, K.G.; Bauer, J.D. [and others
Mass spectrometric study of high-temperature dehydroxylation of disperse silicas and the interpretation of their IR spectra in the region of Si-O stretching vibrations
Field-desorption mass spectrometry has been used to determine the lower boundary of the temperature interval for the removal of surface hydroxyl groups of aerosil. Both in the regime of cation desorption and in the regime of anion desorption, at temperatures above 900/sup 0/K, OH ions of the corresponding sign are registered. It is concluded that the thermal decomposition of the surface bonds triple bond Si-OH is homolytic in character. A mechanism is proposed for the dehydroxylation of SiO/sub 2/, according to which the initially formed radical centers triple bond Si and triple bond SiO change into ions: triple bond Si/sup +/ (I) and triple bond SiO/sup -/ (II). The bands at 888 and 908 cm/sup -1/ in the IR spectra of silicas obtained at high temperatures are assigned to vibrations of Si-O bonds in I and II, respectively.
Nazarenko, V.A.; Furman, V.I.; Guzikevich, A.G.; Gorlov, Yu.I.
Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning 13C and 29Si NMR Enhanced by Dynamic Nuclear Polarization
We show that dynamic nuclear polarization (DNP) can be used to enhance NMR signals of 13C and 29Si nuclei located in mesoporous organic/inorganic hybrid materials, at several hundreds of nanometers from stable radicals (TOTAPOL) trapped in the surrounding frozen disordered water. The approach is demonstrated using mesoporous silica nanoparticles (MSN), functionalized with 3-(N-phenylureido)propyl (PUP) groups, filled with the surfactant cetyltrimethylammonium bromide (CTAB). The DNP-enhanced proton magnetization is transported into the mesopores via 1H�1H spin diffusion and transferred to rare spins by cross-polarization, yielding signal enhancements ?on/off of around 8. When the CTAB molecules are extracted, so that the radicals can enter the mesopores, the enhancements increase to ?on/off ? 30 for both nuclei. A quantitative analysis of the signal enhancements in MSN with and without surfactant is based on a one-dimensional proton spin diffusion model. The effect of solvent deuteration is also investigated.
Lafon, Olivier [Universite de Lille Nord de France; Thankamony, Aany S. Lilly [Universite de Lille Nord de France; Kokayashi, Takeshi [Ames Laboratory; Carnevale, Diego [Ecole Polytechnique Federale de Lausanne; Vitzthum, Veronika [Ecole Polytechnique Federale de Lausanne; Slowing, Igor I. [Ames Laboratory; Kandel, Kapil [Ames Laboratory; Vezin, Herve [Universite de Lille Nord de France; Amoureux, Jean-Paul [Universite de Lille Nord de France; Bodenhausen, Geoffrey [Ecole Polytechnique Federale de Lausanne; Pruski, Marek [Ames Laboratory
Model of gypsum, calcite and silica solubilities for application to geothermal waters over a wide range of temperature, P/sub CO/sub 2// and ionic strength. Final technical report, October 1, 1983-September 30, 1984
This report describes the construction of a high temperature (25 to 250/sup 0/C), variable P/sub CO/sub 2// (1 to 40 atm), chemical model of mineral (including gypsum, calcite and amorphous silica) solubilities in the system: Na-K-Ca-H-Cl-SO/sub 4/-HCO/sub 3/-CO/sub 3/-CO/sub 2/-SiO/sub 2/-H/sub 2/O. This model was designed to support geothermal energy production needs.
A comparison study of carbon dioxide adsorption on polydimethylsiloxane, silica gel, and Illinois No. 6 coal using in situ infrared spectroscopy
Adsorption of supercritical carbon dioxide (CO{sub 2}) on polydimethylsiloxane (PDMS), silica gel (SiO{sub 2}), and Illinois No. 6 coal was compared using in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy at pressures up to 14 MPa and temperatures at 40{sup o}C and 50{sup o}C. Only physical adsorption of CO{sub 2} was recorded for PDMS, SiO{sub 2}, and Illinois no. 6. There was no evidence of the formation of carbonic acid, bicarbonates, carbonates, or any other reaction product between CO{sub 2} and PDMS, SiO{sub 2}, and Illinois No. 6 coal. Carbon dioxide adsorption on PDMS and SiO{sub 2} produced a linear isotherm while a typical Langmuir-like isotherm was observed for Illinois No. 6 coal. Attempts to measure CO{sub 2} induced swelling of the three materials was unsuccessful due to the design of the ATR-FTIR cell. 51 refs., 7 figs., 1 tab.
A.L. Goodman [U.S. Department of Energy, Pittsburgh, PA (USA). National Energy Technology Laboratory
Synthesis of sulfated titania supported on mesoporous silica using direct impregnation and its application in esterification of acetic acid and n-butanol
A new method has been developed for the preparation of sulfated titania (S-TiO{sub 2}) supported on mesoporous silica. The use of direct exchange of metal containing precursors for the surfactants in the as-synthesized MCM-41 substrate produced a product with high sulfur content without serious blockage of the pore structure of MCM-41. The pore sizes and volumes of the resultant S-TiO{sub 2}/MCM-41 composites were found to vary markedly with the loading of TiO{sub 2}. The strong acidic character of the composites obtained was examined by using them as catalysts for the esterification of acetic acid and n-butanol. - Abstract: XRD profiles of the composites of S-TiO{sub 2}/MCM-41 with different TiO{sub 2} contents. The low angle peaks indicate the MCM-41-like structure retained and a TiO{sub 2} phase appeared at high angle region. Display Omitted
Wang Yuhong, E-mail: email@example.com [Research Institute of Applied Catalysis, School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 200235 (China); Gan Yunting [Research Institute of Applied Catalysis, School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 200235 (China); Whiting, Roger [School of Applied Science, Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland (New Zealand); Lu Guanzhong [Research Institute of Applied Catalysis, School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 200235 (China)
Amorphisation mechanism of a flint aggregate during the alkali-silica reaction: X-ray diffraction and X-ray absorption XANES contributions
Flint samples at different stages of the Alkali-Silica Reaction were prepared and analyzed by X-ray diffraction (XRD) and silicon K-edge X-ray absorption near edge structure techniques (XANES). The results are compared to those of measurements performed on alpha quartz c-SiO{sub 2} and rough flint aggregate. The molar fraction of Q{sub 3} sites is determined as a function of the time of reaction. Up to 14 h of attack, the effect of the reaction seems of little importance. From 30 to 168 h, we showed an acceleration of the effect of the reaction on the crystal structure of the aggregate resulting in an amorphisation of the crystal. During this period, the amorphous fraction increases linearly with the number of Q{sub 3} sites. The results of the XANES confirm the amorphisation of the aggregate during the reaction and show the presence of silicon in a tetrahedral environment of oxygen whatever the time of attack.
Verstraete, J.; Khouchaf, L.; Bulteel, D.; Garcia-Diaz, E.; Flank, A.M; Tuilier, M.H
Research and Development of a New Silica-Alumina Based Cementitious Material Largely Using Coal Refuse for Mine Backfill, Mine Sealing and Waste Disposal Stabilization
Coal refuse and coal combustion byproducts as industrial solid waste stockpiles have become great threats to the environment. To activate coal refuse is one practical solution to recycle this huge amount of solid waste as substitute for Ordinary Portland Cement (OPC). The central goal of this project is to investigate and develop a new silica-alumina based cementitious material largely using coal refuse as a constituent that will be ideal for durable construction, mine backfill, mine sealing and waste disposal stabilization applications. This new material is an environment-friendly alternative to Ordinary Portland Cement. The main constituents of the new material are coal refuse and other coal wastes including coal sludge and coal combustion products (CCPs). Compared with conventional cement production, successful development of this new technology could potentially save energy and reduce greenhouse gas emissions, recycle vast amount of coal wastes, and significantly reduce production cost. A systematic research has been conducted to seek for an optimal solution for enhancing pozzolanic reactivity of the relatively inert solid waste-coal refuse in order to improve the utilization efficiency and economic benefit as a construction and building material.
Henghu Sun; Yuan Yao
Methanol Decomposition over Palladium Particles Supported on Silica: Role of Particle Size and Co-Feeding Carbon Dioxide on the Catalytic Properties
Monodisperse palladium particles of six distinct and controlled sizes between 4-16 nm were synthesized in a one-pot polyol process by varying the molar ratios of the two palladium precursors used, which contained palladium in different oxidation states. This difference permitted size control by regulation of the nucleation rate because low oxidation state metals ions nucleate quickly relative to high oxidation state ions. After immobilization of the Pd particles on silica by mild sonication, the catalysts were characterized by X-ray absorption spectroscopy and applied toward catalytic methanol decomposition. This reaction was determined as structure sensitive with the intrinsic activity (turnover frequency) increasing with increasing particle size. Moreover, observed catalytic deactivation was linked to product (carbon monoxide) poisoning. Co-feeding carbon dioxide caused the activity and the amount of deactivation to decrease substantially. A reaction mechanism based on the formation of the {pi}-bond between carbon and oxygen as the rate-limiting step is in agreement with antipathetic structure sensitivity and product poisoning by carbon monoxide.
Hokenek, Selma; Kuhn, John N. (USF)
Prediction and prevention of silica scaling at low levels of oversaturation: Case studies, and calculations for Uenotai Geothermal Field, Akita Prefecture, Japan
Production system design studies often include site-specific silica scaling field experiments, conducted because the onset and rate of scaling are believed difficult to predict, particularly at relatively low levels of oversaturation such as may exist in separators, flowlines, and injection wells. However, observed scaling occurrences (Cerro Prieto, Dixie Valley, Svartsengi, Otake, Hatchobaru, Milos, experimental work) actually conform fairly well to existing theory and rate equations. It should be possible to predict low level scaling with sufficient confidence for production and injection system design and, in cases where oversaturation is allowed, to design systems with foresight to suppress or manage the scale which develops. A promising suppression technology is fluid pH reduction by mixing with non-condensible gases and/or condensate. Calculations for injection lines at Uenotai geothermal field indicate molecular deposition at rates of 0.1 to 1 mm/yr, and some potential for particle deposition at points of turbulence, which can be suppressed by an order of magnitude with about 500 ppm CO{sub 2}. Further improvements of predictive technique will benefit from more uniformity in designing experiments, reporting results, and reporting measurements of scaling in actual production systems.
Klein, Christopher W.; Iwata, Shun; Takeuchi, Rituo; Naka, Tohsaku
Mixed-Matric Membranes for CO2 and H2 Gas Separations Using Metal-Organic Framework and Mesoporus Hybrid Silicas
In this work, we have investigated the separation performance of polymer-based mixed-matrix membranes containing metal-organic frameworks and mesoporous hybrid silicas. The MOF/Matrimid{reg_sign} and MOP-18/Matrimid{reg_sign} membranes exhibited improved dispersion and mechanical strength that allowed high additive loadings with reduced aggregation, as is the case of the 80 wt% MOP-18/Matrimid{reg_sign} and the 80% (w/w) Cu-MOF/Matrimid{reg_sign} membranes. Membranes with up to 60% (w/w) ZIF-8 content exhibited similar mechanical strength and improved dispersion. The H{sub 2}/CO{sub 2} separation properties of MOF/Matrimid{reg_sign} mixed-matrix membranes was improved by either keeping the selectivity constant and increasing the permeability (MOF-5, Cu-MOF) or by improving both selectivity and permeability (ZIF-8). In the case of MOF-5/Matrimid{reg_sign} mixed-matrix membranes, the H{sub 2}/CO{sub 2} selectivity was kept at 2.6 and the H{sub 2} permeability increased from 24.4 to 53.8 Barrers. For the Cu-MOF/Matrimid{reg_sign} mixed-matrix membranes, the H{sub 2}/CO{sub 2} selectivity was kept at 2.05 and the H{sub 2} permeability increased from 17.1 to 158 Barrers. These two materials introduced porosity and uniform paths that enhanced the gas transport in the membranes. When ZIF-8/Matrimid{reg_sign} mixed-matrix membranes were studied, the H{sub 2}/CO{sub 2} selectivity increased from 2.9 to 4.4 and the permeability of H{sub 2} increased from 26.5 to 35.8 Barrers. The increased H{sub 2}/CO{sub 2} selectivity in ZIF-8/Matrimid{reg_sign} membranes was explained by the sieving effect introduced by the ZIF-8 crystals (pore window 0.34 nm) that restricted the transport of molecules larger than H{sub 2}. Materials with microporous and/or mesoporous cavities like carbon aerogel composites with zeolite A and zeolite Y, and membranes containing mesoporous ZSM-5 showed sieving effects for small molecules (e.g. H{sub 2} and CO{sub 2}), however, the membranes were most selective for CO{sub 2} due to the strong interaction of the zeolites with CO{sub 2}. For example, at 30 wt% ZSM-5 loading, the CO{sub 2}/CH{sub 4} selectivity increased from 34.7 (Matrimid{reg_sign}) to 56.4. The large increase in selectivity was the result of the increase in CO{sub 2} permeability from 7.3 (Matrimid{reg_sign}) to 14.6 Barrers. At 30 wt% ZSM-5 loading, the H{sub 2}/CH{sub 4} separation was also improved from 83.3 (Matrimid{reg_sign}) to 136.7 with an increase in H{sub 2} permeability from 17.5 (Matrimid{reg_sign}) to 35.3 Barrers. The 10% carbon aerogel-zeolite A and -zeolite Y composite/Matrimid{reg_sign} membranes exhibited an increase in the CO{sub 2}/CH{sub 4} separation from 34.7 to 71.5 (zeolite A composite) and to 57.4 (zeolite Y composite); in addition, the membrane exhibited an increase in the CO{sub 2}/N{sub 2} separation from 33.1 to 50 (zeolite A composite) and to 49.4 (zeolite Y composite), indicating that these type of materials have affinity for CO{sub 2}. The inclusion of mesoporosity enhanced the dispersion of the additive allowing loadings of up to 30% (w/w) without the formation of non-selective voids.
Inga Musselman; Kenneth Balkus, Jr.; John Ferraris
Precipitation in Multi-Component Ni-Base Superalloys
superalloys using the phase-field method, the Gibbs free energy of the ? and ?' ... free energy curve and phase equilibrium compositions in this work showed�...
Multicomponent Metal-Carbon Junctions in 1-D Geometry
... microscopy, and cyclic voltammetry (CV) and ac electrochemical impedance spectroscopy (EIS). ... Application of Carbon Nanotubes � Energy to Bioelectronic Sensor ... Raman Studies of Hybrid Nanostructures for Solar Energy Applications.
Efficient Discovery of Novel Multicomponent Mixtures for Hydrogen...
below 85 o C. The research will combine first-principles calculations of reaction thermodynamics and kinetics with material and catalyst synthesis, testing, and characterization....
Modelling spreading, vaporisation and dissolution of multi-component pools.
??The present work describes the fundamental extension of an integral pool spreading, vaporisation and dissolution model, part of the Process Hazard Assessment Tool (Phast) software.� (more)
Fernandez, MI
Elastic Properties of Multi-Component Nickel Solid Solutions
The integration in the Brillion zone was performed by using. Monkhorst Pack .... and 4, the calculated total energies of supercell systems are independent on the
Large Scale Simulations of Single and Multi-Component Flow ...
... research. Fontainebleau sandstone images were prepared by John Dunsmuir of Exxon Research & Engineering Co. in ...
perchloric acid and 75% acetic acid to sharp needle-shaped specimens initially, with subsequent treatment in 2% perchloric acid in butoxyethanol. Atom-probe�...
Multi-component removal in flue gas by aqua ammonia
A new method for the removal of environmental compounds from gaseous streams, in particular, flue gas streams. The new method involves first oxidizing some or all of the acid anhydrides contained in the gas stream such as sulfur dioxide (SO.sub.2) and nitric oxide (NO) and nitrous oxide (N.sub.2O) to sulfur trioxide (SO.sub.3) and nitrogen dioxide (NO.sub.2). The gas stream is subsequently treated with aqua ammonia or ammonium hydroxide which captures the compounds via chemical absorption through acid-base or neutralization reactions. The products of the reactions can be collected as slurries, dewatered, and dried for use as fertilizers, or once the slurries have been dewatered, used directly as fertilizers. The ammonium hydroxide can be regenerated and recycled for use via thermal decomposition of ammonium bicarbonate, one of the products formed. There are alternative embodiments which entail stoichiometric scrubbing of nitrogen oxides and sulfur oxides with subsequent separate scrubbing of carbon dioxide.
Yeh, James T. (Bethel Park, PA); Pennline, Henry W. (Bethel Park, PA)
Viscosity of Multicomponent Glasses as a Function of Temperature ...
... of Fluidized Bed Steam Reforming (FBSR) with Hanford Low Activity Wastes ... Level Waste at the Defense Waste Processing Facility through Sludge Batch 7b.
Phase Evolution Characterization of a Multi-Component Oxide ...
... deposited with a Self-shielded flux cored arc welding (FCAW-S) process has ... Experimental Observations and Analyses from Diffusion Studies for U-Mo Nuclear Fuel ... Phase Field Modeling of Microstructure Engineering in Spinodal- Type�...
Geothermometry At Upper Hot Creek Ranch Area (Benoit & Blackwell, 2006) |
Geothermometry At Upper Hot Creek Ranch Area (Benoit & Blackwell, 2006) Geothermometry At Upper Hot Creek Ranch Area (Benoit & Blackwell, 2006) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Geothermometry At Upper Hot Creek Ranch Area (Benoit & Blackwell, 2006) Exploration Activity Details Location Upper Hot Creek Ranch Area Exploration Technique Geothermometry Activity Date Usefulness useful DOE-funding Unknown Notes Ten water samples were collected for chemical analysis and interpretation. Analyses of three samples of the UHCR thermal give predicted subsurface temperatures ranging from 317 to 334 oF from the Na-K-Ca, silica (quartz), and Na-Li geothermometers. The fact that all three thermometers closely agree gives the predictions added credibility. References Dick Benoit, David Blackwell (2006) Exploration Of The Upper Hot
Role of the nature of the support (alumina or silica), of the support porosity, and of the Pt dispersion in the selective reduction of NO by C{sub 3}H{sub 6} under lean-burn conditions
During selective reduction of NO{sub x} under lean-burn conditions, a Pt particle size dependency has previously been observed with various supports. In this study, the authors have examined the influence of various parameters over a large range of initial metal dispersion: nature of the support (silica or alumina), support porosity, presence of impurities (particularly chlorine or sulfur), nature of the platinum precursor salt, and Pt particle size distribution. Furthermore, the authors have considered the mean particle size after sintering under the reactant mixture up to 773 K. Of the factors considered, only the Pt dispersion is of key importance. The intrinsic activity increases with decreasing dispersion (measured initially or after reaction) for each of the main reactions: reduction of NO into N{sub 2} or N{sub 2}O, oxidation of NO into NO{sub 2}, or oxidation of C{sub 3}H{sub 6} into CO{sub 2}. The dispersion does not clearly affect the selectivity.
Denton, P.; Giroir-Fendler, A.; Praliaud, H.; Primet, M.
Lithology, fault displacement, and origin of secondary calcium carbonate and opaline silica at Trenches 14 and 14D on the Bow Ridge Fault at Exile Hill, Nye County, Nevada
Yucca Mountain, a proposed site for a high-level nuclear-waste repository, is located in southern Nevada, 20 km east of Beatty, and adjacent to the southwest comer of the Nevada Test Site (NTS) (fig. 1). Yucca Mountain is located within the Basin and Range province of the western United States. The climate is semiarid, and the flora is transitional between that of the Mojave Desert to the south and the Great Basin Desert to the north. As part of the evaluation, hydrologic conditions, especially water levels, of Yucca Mountain and vicinity during the Quaternary, and especially the past 20,000 years, are being characterized. In 1982, the US Geological Survey, in cooperation with the US Department of Energy (under interagency agreement DE-A104-78ET44802), excavated twenty-six bulldozer and backhoe trenches in the Yucca Mountain region to evaluate the nature and frequency of Quaternary faulting (Swadley and others, 1984). The trenches were oriented perpendicular to traces of suspected Quaternary faults and across projections of known bedrock faults into Quaternary deposits. Trench 14 exposes the Bow Ridge Fault on the west side of Exile Hill. Although the original purpose of the excavation of trench 14 was to evaluate the nature and frequency of Quaternary faulting on the Bow Ridge Fault, concern arose as to whether or not the nearly vertical calcium carbonate (the term ``carbonate`` in this study refers to calcium carbonate) and opaline silica veins in the fault zone were deposited by ascending waters (ground water). These veins resemble in gross morphology veins commonly formed by hydrothermal processes.
Taylor, E.M.; Huckins, H.E.
Silicon Nitride Nanowire Papers Synthesized by Silica ...
Aerosol Jet� Material Deposition for High Resolution Printed Electronic Applications ... Carbon Nanotube Coatings Laser Power and Energy Measurements ... Rational Tailoring of 1-D (Nanowires), 2-D (Graphene) and 3-D (Ceramic/Carbon�...
Physiochemical Properties of Cryolite-Silica Melts
It is thus essential to develop a method for synthesis of solar silicon which is ... Case Study of the Development of a Light Weighted Refuse Collection Unit.
Electrophoretic Deposition of Silica on Stainless Steel
Long-Term Surface Restoration Effect Introduced by Advanced Lubricant Additive � Nanocomposite Thermal Spray Coatings. New Hardfacing Overlay Claddings�...
Functional Composites: Fluorescent Carbon Nanotubes in Silica ...
About this Abstract. Meeting, Materials Science & Technology 2012. Symposium, Functional and Innovative Composites. Presentation Title, Functional�...
Deformation of Silica Aerogel During Fluid Adsorption
Aerogels are very compliant materials - even small stresses can lead to large deformations. In this paper we present measurements of the linear deformation of high porosity aerogels during adsorption of low surface tension fluids, performed using a Linear Variable Differential Transformer (LVDT). We show that the degree of deformation of the aerogel during capillary condensation scales with the surface tension, and extract the bulk modulus of the gel from the data. Furthermore we suggest limits on safe temperatures for filling and emptying low density aerogels with helium.
Manufacturing complex silica aerogel target components
Aerogel is a material used in numerous components in High Energy Density Physics targets. In the past these components were molded into the proper shapes. Artifacts left in the parts from the molding process, such as contour irregularities from shrinkage and density gradients caused by the skin, have caused LANL to pursue machining as a way to make the components.
Defriend Obrey, Kimberly Ann [Los Alamos National Laboratory; Day, Robert D [Los Alamos National Laboratory; Espinoza, Brent F [Los Alamos National Laboratory; Hatch, Doug [Los Alamos National Laboratory; Patterson, Brian M [Los Alamos National Laboratory; Feng, Shihai [Los Alamos National Laboratory
van de Hulst, H.C. , Light Scattering by Small Particles,A New Polarization-Modulated Light Scattering Instrument,"and interpretation of light scattering effects in aerogels.
Lithiation of Silica through Partial Reduction
We demonstrate the reversible lithiation of SiO{sub 2} up to 2/3 Li per Si, and propose a mechanism for it based on molecular dynamics and density functional theory simulations. Our calculations show that neither interstitial Li (no reduction), nor the formation of Li{sub 2}O clusters and Si-Si bonds (full reduction) are energetically favorable. Rather, two Li effectively break a Si-O bond and become stabilized by oxygen, thus partially reducing the SiO{sub 2} anode: this leads to increased anode capacity when the reduction occurs at the Si/SiO{sub 2} interface. The resulting Li{sub x}SiO{sub 2} (x < 2/3) compounds have band-gaps in the range of 2.0-3.4 eV.
Ban, C.; Kappes, B. B.; Xu, Q.; Engtrakul, C.; Ciobanu, C. V.; Dillon, A. C.; Zhao, Y.
Understanding Silica-Kaolinite Composite Sintering
Field Assisted Sintering of Oxide Ceramics: New Mechanisms � High-Speed Compaction of Powder Materials at High Voltage Electric Discharge Consolidation.
Biomimetic oxidation studies. 11: Alkane functionalization in aqueous solution utilizing in situ formed [Fe{sub 2}O({eta}{sup 1}-H{sub 2}O)({eta}{sup 1}-OAc)(TPA){sub 2}]{sup 3+}, as an MMO model precatalyst, embedded in surface-derivatized silica and contained in micelles
The biomimetic, methane monooxygenase enzyme (MMO) precatalyst, [Fe{sub 2}O({eta}{sup 1}-H{sub 2}O)({eta}{sup 1}-OAc)(TPA){sub 2}]{sup 3+} (TPA = tris[(2-pyridyl)methyl]amine), 1, formed in situ at pH 4.2 from [Fe{sub 2}O({mu}-OAc)(TPA){sub 2}]{sup 3+}, 2, was embedded in an amorphous silicate surface modified by a combination of hydrophilic poly(ethylene oxide) and hydrophobic poly(propylene oxide). The resulting catalytic assembly was found to be a biomimetic model for the MMO active site within a hydrophobic macroenvironment, allowing alkane functionalization with tert-butyl hydroperoxide (TBHP)/O{sub 2} in an aqueous reaction medium (pH 4.2). For example, cyclohexane was oxidized to a mixture of cyclohexanone, cyclohexanol, and cyclohexyl-tert-butyl peroxide, in a ratio of {approximately}3:1:2. The balance between poly(ethylene oxide) and poly(propylene oxide), tethered on the silica surface, was crucial for maximizing the catalytic activity. The silica-based catalytic assembly showed reactivity somewhat higher in comparison to an aqueous micelle system utilizing the surfactant, cetyltrimethylammonium hydrogen sulfate at its critical micelle concentration, in which functionalization of cyclohexane with TBHP/O{sub 2} in the presence of 1 was also studied at pH 4.2 and was found to provide similar products: cyclohexanol, cyclohexanone, and cyclohexyl-tert-butyl peroxide, in a ratio of {approximately}2:3:1. Moreover, the mechanism for both the silica-based catalytic assembly and the aqueous micelle system was found to occur via the Haber-Weiss process, in which redox chemistry between 1 and TBHP provides both the t-BuO{sup {sm_bullet}} and t-BuOO{sup {sm_bullet}} radicals. The t-BuO{sup {sm_bullet}} radical initiates the C-H functionalization reaction to form the carbon radical, followed by O{sub 2} trapping, to provide cyclohexyl hydroperoxide, which produces the cyclohexanol and cyclohexanone in the presence of 1, whereas the coupling product emanates from t-BuOO{sup {sm_bullet}} and cyclohexyl radicals. A discussion concerning both approaches for alkane functionalization in water will be presented.
Neimann, K.; Neumann, R. [Hebrew Univ., Jerusalem (Israel); Rabion, A. [Lawrence Berkeley National Lab., CA (United States)]|[Groupement de Recherche de Lacq, Artix (France); Buchanan, R.M. [Univ. of Louisville, KY (United States). Dept. of Chemistry; Fish, R.H. [Lawrence Berkeley National Lab., CA (United States)
Tough2_MP: A parallel version of TOUGH2
multiphase flow and multicomponent transport in porous andmultiphase, multicomponent heat and fluid flows in porous
Zhang, Keni; Wu, Yu-Shu; Ding, Chris; Pruess, Karsten
Massively parallel computing simulation of fluid flow in the unsaturated zone of Yucca Mountain, Nevada
flows of multiphase, multicomponents in porous and fracturedmultiphase flow and multicomponent transport in porous and
Zhang, Keni; Wu, Yu-Shu; Bodvarsson, G.S.
Geothermometry At Central Nevada Seismic Zone Region (Shevenell...
DOE-funding Unknown References Lisa Shevenell, Ted De Rocher (2005) Evaluation Of Chemical Geothermometers For Calculating Reservoir Temperatures At Nevada Geothermal Power...
Geothermometry At Walker-Lane Transitional Zone Region (Shevenell...
Sorption of metal ions from multicomponent aqueous solutions by activated carbons produced from waste
Activated carbons produced by thermal treatment of a mixture of sunflower husks, low-grade coal, and refinery waste were studied as adsorbents of transition ion metals from aqueous solutions of various compositions. The optimal conditions and the mechanism of sorption, as well as the structure of the sorbents, were studied.
Tikhonova, L.P.; Goba, V.E.; Kovtun, M.F.; Tarasenko, Y.A.; Khavryuchenko, V.D.; Lyubchik, S.B.; Boiko, A.N. [National Academy of Science Ukraine, Kiev (Ukraine). Institute of Coal Chemistry
Numerical Simulation of Multicomponent Shock Accelerated Flows and Mixing using Localized
.S. Department of Energy's Office of Science, the Argonne Leadership Computing Facility (ALCF) works hand in hand at the ALCF are broadly applicable, thereby providing critical support for dramatic advances in American industry, medicine, and science. Since its founding in 2006, the ALCF has provided more than 4 billion
Kawai, Soshi
Multicomponent Transport through Realistic Zeolite Membranes: Characterization & Transport in Nanoporous Networks
These research studies focused on the characterization and transport for porous solids which comprise both microporosity and mesoporosity. Such materials represent membranes made from zeolites as well as for many new nanoporous solids. Several analytical sorption techniques were developed and evaluated by which these multi-dimensional porous solids could be quantitatively characterized. Notably an approach by which intact membranes could be studied was developed and applied to plate-like and tubular supported zeolitic membranes. Transport processes were studied experimentally and theoretically based on the characterization studies.
William C. Conner
Miscible, multi-component, diesel fuels and methods of bio-oil transformation
Briefly described, embodiments of this disclosure include methods of recovering bio-oil products, fuels, diesel fuels, and the like are disclosed.
Adams, Thomas (Athens, GA); Garcia, Manuel (Quebec, CA); Geller, Dan (Athens, GA); Goodrum, John W. (Athens, GA); Pendergrass, Joshua T. (Jefferson, GA)
Estimating shallow shear velocities with marine multi-component seismic data
of hundreds of meters, this information remains largely unexploited in oil and gas exploration o shore. We, for exploration seismologists these models would help to improve the shear wave static correction needed in oil and gas exploration e.g., Mari, 1984; Marsden, 1993. This need has grown in impor- tance as multi
Ritzwolle, Mike
Multicomponent Radial Flow Chromatography T. Gu', G-J. Tsai2, and G. T. Tsao3
, catalytic reforming, and vapor phase desulfurization (Balakotaiah and Luss. 1981; Strauss and Budde, 1978
Gu, Tingyue
Nonlinear interaction and parametric instability of kinetic Alfven waves in multicomponent plasmas
Nonlinear couplings among kinetic Alfven waves are investigated for a three-component plasma consisting of electrons, protons, and heavy ions. The parametric instability is investigated, and the growth rate is obtained. In the kinetic regime, the growth rate for the parallel decay instability increases with the heavy ion content, but the growth rate for the reverse decay is independent of the latter since the perpendicular wavelength is much larger than the ion gyroradius. It decreases with the heavy ion content when the perpendicular wavelength is of the order of the ion gyroradius. It is also found that in the short perpendicular wavelength limit, the growth rate is only weakly affected by the heavy ions. On the other hand, in the inertial regime, for both parallel and reverse decay cases, the growth rate decreases as the number of heavy ions becomes large.
Zhao, J. S.; Yang, L. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China); Wu, D. J. [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Lu, J. Y. [College of Mathematics and Statistics, Nanjing University of Information Science and Technology, Nanjing 210044 (China); National Center for Space Weather, China Meteorology Administration, Beijing 100081 (China)
Multicomponent Synthetic Polymers with Viral-Mimetic Chemistry for Nucleic Acid Delivery
7.3 (Bruker Nano), or SPIP version 3.3.6 (Image Metrology A/S, Denmark). Fluorescence Microscopy plasmid DNA was complexed as previously described. For the fluorescence microscopy (FM) experiments, 12 to fluorescence microscopy investigation. For nuclei staining, 1 drop of DAPI standard stain solution was added
Li, Jingpeng
, Cray T3E at NERSC, IBM SP at ANL, and Convex Exemplar SPP2000 at NCSA. The following table shows Center (NERSC), and the National Center for Su- percomputing Applications (NCSA). The authors thank Dr. Pat Worely of ORNL for his assistance in the T3E runs at NERSC. REFERENCES E F G H I P Q P H R S T U V
Mahinthakumar, Kumar
Device For Determining Therophysical Properties Of A Multi-Component Gas At Arbitrary Temperature And Pressure
A computer product for determining thermodynamic properties of a natural gas hydrocarbon, when the speed of sound in the gas is known at an arbitrary temperature and pressure. Thus, the known parameters are the sound speed, temperature, pressure, and concentrations of any dilute components of the gas. The method uses a set of reference gases and their calculated density and speed of sound values to estimate the density of the subject gas. Additional calculations can be made to estimate the molecular weight of the subject gas, which can then be used as the basis for mass flow calculations, to determine the speed of sound at standard pressure and temperature, and to determine various thermophysical characteristics of the gas.
Morrow, Thomas B. (San Antonio, TX); Behring, II, Kendricks A. (Gilbert, AZ)
Final Report for: "Bis-pi-allylpalladium Complexes in Catalysis of Multicomponent Reactions"
The research project involved the development of new and functionally improved Pd(II) catalyst for a three-component reaction of boronic acids, allenes and imines to afford homoallylic amines that are useful in synthesis of biologically active heterocycles. Furthermore, insights into the reaction mechanism and the structure and reactivity of the catalytically active intermediates involved in this process were sought. As a result of this work, a new type of Pd-catalysts possessing an auxiliary ligand attached to the Pd center via a C-Pd and N-Pd bonds were identified, and found to be more active than the traditional catalysts derived from Pd(OAc)2. The new catalysts provided an access to a broader range of homoallylic amine products. Although the final unequivocal evidence regarding the structure of the Pd(II) complex involved in the nucleophilic transfer of the allyl fragment from the palladium center to the imine could not be obtained, mechanistic insights into the events that are detrimental to the activity of the originally reported Pd(OAc)2-based catalytic systems were uncovered.
Malinakova, H. C.; Shiota, Atsushi
Benchmarking a Visual-Basic based multi-component one-dimensional reactive transport modeling tool
We present the details of a comprehensive numerical modeling tool, RT1D, which can be used for simulating biochemical and geochemical reactive transport problems. The code can be run within the standard Microsoft EXCEL Visual Basic platform, and it does ... Keywords: Bioremediation, Geochemical transport, Groundwater models, Numerical model, Reactive transport
Jagadish Torlapati; T. Prabhakar Clement
AlMnCrCuFeNi Multicomponent Alloy with Superior Hardness and ...
The optical and electronic microscopy analysis of the remelted alloy indicated a dendritic ... Processing and Mechanical Behavior of Unalloyed Plutonium.
Plugging micro-leaks in multi-component, ceramic tubesheets with material leached therefrom
Cracks, in ceramic wall members, on the order of 1 micron or less in width are plugged helium-tight by selectively leaching a component of the wall member with a solvent, letting the resultant leach form a liquid bridge within the crack, removing the solvent and sintering the resultant residue. This method is of particular value for remedying microcracks or channels in a cell member constituting a tubesheet in a hollow fiber type, high temperature battery cell, such as a sodium/sulfur cell, for example. 1 fig.
Bieler, B.H.; Tsang, F.Y.
Vp/Vs ESTIMATION FROM MULTICOMPONENT SEISMIC DATA FOR IMPROVED CHARACTERIZATION OF A TIGHT
for the fluid flowing though the sand matrix a13 tortuosity for the sand flowing though the clay matrix a31 tortuosity for the clay flowing though the sand matrix B friction matrix b11 friction coefficient between the sand matrix and the fluid b13 friction coefficient between the sand and the clay matrices b33 friction
Multicomponent seismic data registration for subsurface characterization in the shallow Gulf of Mexico
Gulf of Mexico Sergey Fomel, Milo M. Backus, Michael V. DeAngelo, Paul E. Murray, Bob A. Hardage with application to subsurface characterization in the shallow Gulf of Mexico. In this study, we extend-S images. Application of this technique to data from the Gulf of Mexico reveals the structure of sediments
Variably Saturated Flow and Multicomponent Biogeochemical Reactive Transport Modeling of a Uranium Bioremediation Field Experiment
Field experiments at a former uranium mill tailings site have identified the potential for stimulating indigenous bacteria to catalyze the conversion of aqueous uranium in the +6 oxidation state to immobile solid-associated uranium in the +4 oxidation state. This effectively removes uranium from solution resulting in groundwater concentrations below actionable standards. Three-dimensional, coupled variably-saturated flow and biogeochemical reactive transport modeling of a 2008 in situ uranium bioremediation field experiment is used to better understand the interplay of transport rates and biogeochemical reaction rates that determine the location and magnitude of key reaction products. A comprehensive reaction network, developed largely through previous 1-D modeling studies, was used to simulate the impacts on uranium behavior of pulsed acetate amendment, seasonal water table variation, spatially-variable physical (hydraulic conductivity, porosity) and geochemical (reactive surface area) material properties. A principal challenge is the mechanistic representation of biologically-mediated terminal electron acceptor process (TEAP) reactions whose products significantly alter geochemical controls on uranium mobility through increases in pH, alkalinity, exchangeable cations, and highly reactive reduction products. In general, these simulations of the 2008 Big Rusty acetate biostimulation field experiment in Rifle, Colorado confirmed previously identified behaviors including (1) initial dominance by iron reducing bacteria that concomitantly reduce aqueous U(VI), (2) sulfate reducing bacteria that become dominant after {approx}30 days and outcompete iron reducers for the acetate electron donor, (3) continuing iron-reducer activity and U(VI) bioreduction during dominantly sulfate reducing conditions, and (4) lower apparent U(VI) removal from groundwater during dominantly sulfate reducing conditions. New knowledge on simultaneously active metal and sulfate reducers has been incorporated into the modeling. In this case, an initially small population of slow growing sulfate reducers is active from the initiation of biostimulation. Three-dimensional, variably saturated flow modeling was used to address impacts of a falling water table during acetate injection. These impacts included a significant reduction in aquifer saturated thickness and isolation of residual reactants and products, as well as unmitigated uranium, in the newly unsaturated vadose zone. High permeability sandy gravel structures resulted in locally high flow rates in the vicinity of injection wells that increased acetate dilution. In downgradient locations, these structures created preferential flow paths for acetate delivery that enhanced local zones of TEAP reactivity and subsidiary reactions. Conversely, smaller transport rates associated with the lower permeability lithofacies (e.g., fine) and vadose zone were shown to limit acetate access and reaction. Once accessed by acetate, however, these same zones limited subsequent acetate dilution and provided longer residence times that resulted in higher concentrations of TEAP products when terminal electron donors and acceptors were not limiting. Finally, facies-based porosity and reactive surface area variations were shown to affect aqueous uranium concentration distributions; however, the ranges were sufficiently small to preserve general trends. Large computer memory and high computational performance were required to simulate the detailed coupled process models for multiple biogeochemical components in highly resolved heterogeneous materials for the 110-day field experiment and 50 days of post-biostimulation behavior. In this case, a highly-scalable subsurface simulator operating on 128 processor cores for 12 hours was used to simulate each realization. An equivalent simulation without parallel processing would have taken 60 days, assuming sufficient memory was available.
Yabusaki, Steven B.; Fang, Yilin; Williams, Kenneth H.; Murray, Christopher J.; Ward, Anderson L.; Dayvault, Richard; Waichler, Scott R.; Newcomer, Darrell R.; Spane, Frank A.; Long, Philip E.
Thermal springs in the Salmon River basin, central Idaho
The Salmon River basin within the study area occupies an area of approximately 13,000 square miles in central Idaho. Geologic units in the basin are igneous, sedimentary, and metamorphic rocks; however, granitic rocks of the Idaho batholith are predominant. Water from thermal springs ranges in temperature from 20.5/sup 0/ to 94.0/sup 0/ Celsius. The waters are slightly alkaline and are generally a sodium carbonate or bicarbonate type. Dissolved-solids concentrations are variable and range from 103 to 839 milligrams per liter. Estimated reservoir temperatures determined from the silicic acid-corrected silica, sodium-potassium-calcium, and sulfate-water isotope geothermometers range from 30/sup 0/ to 184/sup 0/ Celsius. Tritium concentrations in sampled thermal waters are near zero and indicate the waters are at least 100 years old. Stable-isotope data indicate it is unlikely that a single hot-water reservoir supplies hot springs in the basin. Thermal springs discharged at least 15,800 acre-feet of water in 1980. Associated convective heat flux is 2.7 x 10/sup 7/ calories per second.
Young, H.W.; Lewis, R.E.
Exploration of the Upper Hot Creek Ranch Geothermal Resource, Nye County, Nevada
The Upper Hot Creek Ranch (UHCR) geothermal system had seen no significant exploration activity prior to initiation of this GRED III project. Geochemical geothermometers calculated from previously available but questionable quality analyses of the UHCR hot spring waters indicated possible subsurface temperatures of +320 oF. A complex Quaternary and Holocene faulting pattern associated with a six mile step over of the Hot Creek Range near the UHCR also indicated that this area was worthy of some exploration activity. Permitting activities began in Dec. 2004 for the temperature-gradient holes but took much longer than expected with all drilling permits finally being received in early August 2005. The drilling and geochemical sampling occurred in August 2005. Ten temperature gradient holes up to 500� deep were initially planned but higher than anticipated drilling and permitting costs within a fixed budget reduced the number of holes to five. Four of the five holes drilled to depths of 300 to 400� encountered temperatures close to the expected regional thermal background conditions. These four holes failed to find any evidence of a large thermal anomaly surrounding the UHCR hot springs. The fifth hole, located within a narrow part of Hot Creek Canyon, encountered a maximum temperature of 81 oF at a depth of 105� but had cooler temperatures at greater depth. Temperature data from this hole can not be extrapolated to greater depths. Any thermal anomaly associated with the UHCR geothermal system is apparently confined to the immediate vicinity of Hot Creek Canyon where challenges such as topography, a wilderness study area, and wetlands issues will make further exploration time consuming and costly. Ten water samples were collected for chemical analysis and interpretation. Analyses of three samples of the UHCR thermal give predicted subsurface temperatures ranging from 317 to 334 oF from the Na-K-Ca, silica (quartz), and Na-Li geothermometers. The fact that all three thermometers closely agree gives the predictions added credibility. Unfortunately, the final result of this exploration is that a moderate temperature geothermal resource has been clearly identified but it appears to be restricted to a relatively small area that would be difficult to develop.
Dick Benoit; David Blackwell
Investigation of Mechanical Properties of Silica/Epoxy Nano ...
Application of Biomass Waste Materials in the Nano Mineral Synthesis ... Effect of Initial Microstructure on the Processing of Titanium Using Equal ... of Ferroelectric Poly(Vinylidene Fluoride-Trifluoroethylene) Copolymer Films ... Sonochemistry as a Tool for Synthesis of Ion-Substituted Calcium Phosphate Nanoparticles.
Methods for globally treating silica optics to reduce optical damage
A method for preventing damage caused by high intensity light sources to optical components includes annealing the optical component for a predetermined period. Another method includes etching the optical component in an etchant including fluoride and bi-fluoride ions. The method also includes ultrasonically agitating the etching solution during the process followed by rinsing of the optical component in a rinse bath.
Miller, Philip Edward; Suratwala, Tayyab Ishaq; Bude, Jeffrey Devin; Shen, Nan; Steele, William Augustus; Laurence, Ted Alfred; Feit, Michael Dennis; Wong, Lana Louie
Chitosan�silica Hybrid Materials for Biomedical Applications
Microstructural Characteristics of Nano Calcium Phosphates Doped with Fluoride and Titanium Ions � Microwave Assisted Synthesis of Nano Hydroxyapatite�...
Effects of Incorporation of Silica and Zirconia Nanoparticles on the ...
Composites with weak interface showed essentially no change in Tg and damping or even ... On the other hand, incorporation of the particles did not alter the thermal ... of a Novel Hybrid Bimodal Network Elastomer with Inorganic Cross
Preparation of Silica Encapsulated Stearic Acid as Composite ...
Conference Tools for 2014 TMS Annual Meeting & Exhibition ... Symposium, Energy Technologies and Carbon Dioxide Management. Presentation Title ... Corrosion Behavior of Differently Heat Treated Steels in CCS Environment with Supercritical CO2 ... Life Cycle Assessment of Different Gold Extraction Process.
Titania Coated Silica Microspheres for High Efficiency Dye ...
These microspheres, if used in DSSCs, can boost the efficiency of solar cell ... In- situ Characterization of Intercalation-induced Damage of High Purity Graphite�...
Uptake of Organic Pollutants by Silica-Polycation-Immobilized
-3780. Surfactant Effects on Alpha Factors in Full-Scale Wastewater Aeration Systems, Water Research, in press (Stenstrom and Gilbert, 1981). This is because surfactants are more effective at low interfacial velocity. Objective of this work is to quantify the effects of surfactant accumulation at bubble interfaces. Datasets
Dubin, Paul D.
Deep NLD Plasma Etching of Fused Silica and Borosilicate Glass
, 92697 Email: email@example.com Abstract-- In this paper, we report development of deep plasma etching
Tang, William C
Tritium Removal from Tritiated Water Using Mesoporous Silica
Detritiation and Isotope Separation / Proceedings of the Ninth International Conference on Tritium Science and Technology (Part 2)
A. Taguchi; R. Akai; M. Saito; Y. Torikai; M. Matsuyama; M. Ogura; S. Uchida
Size-dependent Elasticity of Amorphous Silica Nanowire
Ion Exchanged Mixed Glass Cullet Proppants for Stimulation of Oil and Natural Gas Bearing Shales � Modeling the Electrical Conductivity in Glass Melts.
Flame-Retardant Mechanism of Silica: Effects of Resin ...
... During the collapse of the mound, numerous white, thin flakes were formed, as ... loss rate (burning rate) curves (not shown) were very close to those ...
Development of Silica/Vanadia/ Titania Catalysts for Removal of
(subbituminous or lignite) coals. Therefore, need exists for a low cost Hg oxidation/capturing process. Activated power plants. However, the incremental cost of Hg control via ACI is estimated to range from $3810. This superior oxidation capability is advantageous to power plants equipped with wet-scrubbers where oxidized Hg
Li, Ying
Synthesis and Characterization of Magnetic Silica Nanoparticles for ...
Atomic -Scale Characterization of Nb-Doped SrTiO?3 Nanostructures for .... Metal Oxide Nanofibers Produced by a ForceSpinning Method for Battery Electrodes.
Fluorescent single walled nanotube/silica composite materials
Fluorescent composites of surfactant-wrapped single-walled carbon nanotubes (SWNTs) were prepared by exposing suspensions of surfactant-wrapped carbon nanotubes to tetramethylorthosilicate (TMOS) vapor. Sodium deoxycholate (DOC) and sodium dodecylsulphate (SDS) were the surfactants. No loss in emission intensity was observed when the suspension of DOC-wrapped SWNTs were exposed to the TMOS vapors, but about a 50% decrease in the emission signal was observed from the SDS-wrapped SWNTs nanotubes. The decrease in emission was minimal by buffering the SDS/SWNT suspension prior to forming the composite. Fluorescent xerogels were prepared by adding glycerol to the SWNT suspensions prior to TMOS vapor exposure, followed by drying the gels. Fluorescent aerogels were prepared by replacing water in the gels with methanol and then exposing them to supercritical fluid drying conditions. The aerogels can be used for gas sensing.
Dattelbaum, Andrew M.; Gupta, Gautam; Duque, Juan G.; Doorn, Stephen K.; Hamilton, Christopher E.; DeFriend Obrey, Kimberly A.
Devitrification of Fused Silica into Cristobalite in Sintered Powder ...
A History of the Theories of Glass Structure: Can We Really Believe What is ... Field Assisted Viscous Flow and Crystallization in a Sodium Aluminosilicate Glass ... Mechanisms of the Conversion Reaction in FeF2 Cathodes Exposed to Li in�...
Superhydrophobic Coatings Using Double-Silane Treated Silica ...
Disclosure Number 201202928 Technology Summary This invention relates to superhydrophobic coatings and more specifically to durability improvements. ...
Consolidation of Silica/Graphene Oxide Composite by Spark ...
Synthesis and Characterization of Plasma Polymerized Thin Films Deposited from Benzene and Hexamethyldisiloxane Using (PECVD) Method � Synthesis and�...
Incorporation of silica into baroplastic core-shell nanoparticles
Core-shell baroplastics are nanophase materials that exhibit pressure-induced flow at low temperatures and high pressures. Core-shell baroplastics used in this work are comprised of a low Tg poly(butyl acrylate) (PBA) core ...
Hewlett, Sheldon A
A Microporous Silica Membrane for CO 2 Capture: Relating Gas ...
New and Improved Refractory Materials for Gasifiers using Flexible Feedstock � On pursuit of high performance and low cost of anode-supported SOFC.
Statistical analysis of a silica gel rotary dehumidifier
A regression analysis was conducted on experimental data obtained during the testing of a solid desiccant dehumidifier at the Solar Energy Research Institute (SERI has since been renamed the National Renewable Energy Laboratory). The data obtained was studied using statistical techniques to determine the regression equation for the temperature and humidity at the processed air outlet of the dehumidifier. These variables determine the cooling capacity and efficiency (Coefficient of Performance) of any desiccant cooling cycle. The analysis is used to determine the relative impact the input parameters have on the outlet temperature and humidity.
Kini, A.; Waugaman, D.G.; Kettleborough, C.F. (Texas A and M Univ., College Station (United States))
Preparation of ?-Diketone Modified Silica Gel and its Application to ...
Biosorption Characteristics of Pb(II) from Aqueous Solution onto Poplar Cotton � Characterization of Aluminum Cathode Sheets Used for Zinc Electrowinning.
under Contract DE-AC52-07NA27344. Acknowledgment This work was sponsored by the Geothermal Technologies Office in the Department of Energy. 4 TABLE OF CONTENTS 1. Project...
Thermal dependence of electrical characteristics of micromachined silica microchannel plates
Thermal dependence of electrical characteristics ofresults of our studies on the thermal properties of silicatemperature with a negative thermal coefficient of -0.036
Tremsin, A S; Vallerga, J V; Siegmund, OHW; Beetz, C P; Boerstler, R W
Experimental study of an advanced silica gel dehumidifier
This report contains results of work done to experimentally characterize the performance of an advanced, rotary, desiccant dehumidifier and to develop and validate analytical methods for evaluating its performance in air-conditioning systems. A facility, the Cyclic Test Facility, and a test and analysis procedure were developed to evaluate the performance of the dehumidifier. A series of tests was undertaken to understand the simultaneous heat- and mass-transfer processes. An advanced dehumidifier test article was tested under cyclic operation to fully characterize its performance. Brief accounts of this facility, with its hardware and instrumentation, and detailed accounts of the test data and data reduction and analysis methods are presented. The data provide an engineering data base for evaluating rotary dehumidifiers for cooling applications. The dehumidifier's performance, as measured by the effectiveness, agreed with theory to within plus or minus 10%. 16 refs., 16 figs., 1 tab.
Bharathan, D.; Parsons, J.M.; Maclaine-cross, I.L.
Iron(III)-doped, silica : biodegradable, self-targeting nanoparticles
Mixtures Worksheet� Answer Key for �Solutions and MixturesSolutions and Mixtures (Answer Key) Purpose: Today you will
Mitchell, Kristina Kalani Pohaku
Functionalized Mesoporous Silica: An Effective Adsorbent for the ...
Gold thiosulfate, however, is not well-adsorbed by activated charcoal, making industrial scale use of thiosulfate for gold leaching impractical at present. Because�...
Simulations Reveal That Earth's Silica Is Predominantly Superficial...
from glass to ceramics, computer chips and fiber optic cables. Yet new quantum mechanics results generated by a team of physicists from Ohio State University (OSU) show that...
Lidar characterization of crystalline silica generation and gravel plant
W.E. Eichinger, Elastic Lidar: Theory, Practice and AnalysisApplication of elastic e lidar to PM 10 emissions fromg m ?3 ) QTZ (?g m ?3 ) The lidar horizontal scans collected
Trzepla-Nabaglo, K.; Shiraki, R.; Holm'en, B. A.
A CFD simulation on how the different sizes of silica gel will affect the adsorption performance of silica gel
The application of computational fluid dynamics (CFD) in the area of porous media and adsorption cooling system is becoming more practical due to the significant improvement in computer power. The results from previous studies have shown that CFD can ...
John White
Phosphine-Mediated Multi-Component ?-Umpolung/Aldol/Wittig Cascade Reaction for the Synthesis of Functionalized Naphthalenes
84% yield) as a pale yellow oil; IR (film) ? max 3252, 2927,99% yield) as a pale yellow oil; IR (film) ? max 3277, 3031,87% yield) as a colorless oil; IR (film) ? max 3300, 3058,
Zhang, Kui
Simulation of Cloud Microphysical and Chemical Processes Using a Multicomponent Framework. Part II: Microphysical Evolution of a Wintertime Orographic Cloud
A detailed microphysical model is used to simulate the formation of wintertime orographic clouds in a two-dimensional domain under steady-state conditions. Mass contents and number concentrations of both liquid- and ice-phase cloud particles are ...
CO2 gas/oil ratio prediction in a multi-component reservoir by combined seismic and electromagnetic imaging
partitioning of CO 2 between oil and gas phase. In additionC 0 are the grain, oil, gas and CO 2 densities respectivelyPower Systems; Office of Oil, Gas and Shale Technologies,
Hoversten, G.M.; Gritto, Roland; Washbourne, John; Daley, Tom
Development and anlysis of fast, approximate 3D Algorithms for interpretation of multi-component induction logging data
This report addresses the effects of electrical anisotropy on the 3D inversion of single-well induction logging data when anisotropy is not considered. Of concern are possible artifacts that may lead to an incorrect interpretation of the formation about the borehole. Comparison is made of 3D isotropic inversion on a suite of model data, with and without anisotropy, consisting of an infinite layer and layer terminated at the borehole. In both cases, the layer dip (or well deviation) is varied. Inversion of the anisotropic data result in an overestimate of the layer conductivity, and the lateral extent of the layer about the borehole.
David L. Alumbaugh
Multi-Component Copper Catalyzed Methods to Access Highly-Substituted Amine-Bearing Carbon Centers from Simple Starting Materials
Knochel, P. Angewandte Chemie International Edition 2002,T. ; Ishii, Y. Angewandte Chemie International Edition 2001,Larsen, C. H. Angewandte Chemie International Edition 2012,
Pierce, Conor John
A System And Method To Determine Thermophysical Properties Of A Multi-Component Gas At Arbitrary Temperature And Pressure
A method to determine thermodynamic properties of a natural gas hydrocarbon, when the speed of sound in the gas is known at an arbitrary temperature and pressure. Thus, the known parameters are the sound speed, temperature, pressure, and concentrations of any dilute components of the gas. The method uses a set of reference gases and their calculated density and speed of sound values to estimate the density of the subject gas. Additional calculations can be made to estimate the molecular weight of the subject gas, which can then be used as the basis for mass flow calculations, to determine the speed of sound at standard pressure and temperature, and to determine various thermophysical characteristics of the gas.
Morrow, Thomas E. (San Antonio, TX); Behring, II, Kendricks A. (Gilbert, AZ)
Multicomponent seismic reservoir characterization of a steam-assisted gravity drainage (SAGD) heavy oil project, Athabasca oil sands, Alberta.
??Steam-assisted gravity drainage (SAGD) is an in situ heavy oil recovery method involving the injection of steam in horizontal wells. Time-lapse seismic analysis over a� (more)
Schiltz, Kelsey Kristine
Geology, characteristics, and resource potential of the low-temperature geothermal system near Midway, Wasatch County, Utah. Report of Investigation No. 142
To evaluate the geothermal energy potential of the hot springs system near Midway, Wasatch Co., Utah, consideration was given to heat flow, water chemistry, and structural controls. Abnormal heat flow was indicated qualitatively by snow-melt patterns and quantitatively by heat-flow measurements that were obtained from two of four temperature-gradient wells drilled in the area. These measurements indicated that the area north of the town of Midway is characterized by heat flow equal to 321.75 MW/m/sup 2/, which is over four times the value generally considered as normal heat flow. Chemical analyses of water from six selected thermal springs and wells were used in conjunction with the silica and Na-K-Ca geothermometers to estimate the reservoir temperature of the thermal system. Because the calculated temperature was more than 25/sup 0/C above the maximum observed temperature, a mixing model calculation was used to project an upper limit for the reservoir temperature. Based on these calculations, the system has a reservoir temperature ranging from 46 to 125/sup 0/C. Structural information obtained from published geologic maps of the area and from an unpublished gravity survey, enabled two models to be developed for the system. The first model, based on geologic relationships in the mountains to the north and west of Midway, assumes that the heat for the thermal system comes from a relatively young intrusive or related hydrothermal convection system in the vicinity of the Mayflower mine. Meteoric waters would be heated as they approach the heat source and then move laterally to the south through faults and fractures in the rocks. These thermal waters then rise to the surface through fractures in the crest of an anticline underneath the Midway area. The second model, based on the gravity survey, assumes an igneous intrusion directly beneath Midway as the heat source.
Kohler, J.F.
Optimization of Cell Spaces Simulation for the Modeling of Fire Spreading
This paper presents a simulation performance improvementof the application of the Multicomponent Discrete TimeSystem Specification (MultiDTSS) formalism to a firespread. Multicomponent choice is explained through bothMulticomponent systems and networks ...
Alexandre Muzy; Eric Innocenti; Jean-Fran�ois Santucci; David R. C. Hill
A unified numerical framework model for simulating flow, transport, and heat transfer in porous and fractured media
or chemical species in a multiphase porous medium system canand radiation in a multiphase, multicomponent, porous mediummultiphase flow, multicomponent transport, and heat transfer in porous
Wu, Yu-Shu
Advanced Vadose Zone Simulations Using TOUGH
multiphase flow and multicomponent transport in porous andmultiphase, multicomponent fluids in permeable (fractured and porous)multiphase fluid flow, heat transfer, and deformation in fractured porous
Quantifying Silica Reactivity in Subsurface Environments: An Integrated Experimental Study of Quartz and Amorphous Silica to Establish a baseline for Glass Durability
An immediate EM science need is a reliable kinetic model that predicts long-term waste glass performance.
Patricia Dove; Nizhou Han; Y. Thomas He
Stopping the growth of particles to silica-supported mono-nuclear Ru hydride surface species by tuning silica with surface silanes
chemical grafting of Ru(COD)(COT) through a covalent Ru-Siof a pentane solution of Ru(COD)(COT) under 3 bars of H 2 inhigh temperatures of grafted Ru(COD)(COT), leading to stable
Berthoud, Romain
Thermodynamics Software/Codes - TMS
FORUMS > THERMODYNAMICS SOFTWARE/CODES, Replies, Views, Originator ... Thermodynamic calculations in multicomponent systems, 0, 1887, Cathy�...
The TOUGH codes - a family of simulation tools for multiphase flow and transport processes in permeable media
Multiphase Tracer Transport in Heterogeneous Fractured PorousMultiphase Flow and Multicomponent Transport in Porous and
Pruess, Karsten
A truncated Levenberg-Marquardt algorithm for the calibration of highly parameterized nonlinear models
models of multiphase flow through porous media. The newmultiphase, multicomponent flow in fractured-porous media.
Finsterle, S.
On Water Flow in Hot Fractured Rock -- A Sensitivity Study on the Impact of Fracture-Matrix Heat Transfer
of multiphase, multicomponent fluid mixtures in porous andmultiphase heat and mass flow in unsaturated fractured porous
Birkholzer, Jens T.; Zhang, Yingqi
A Parallel Second-Order Adaptive Mesh Algorithm for Incompressible Flow in Porous Media
solving multiphase, incompressible ?ows in porous media. Wemultiphase, multicomponent incompressible ?ow in hetero- geneous porous
Pau, George Shu Heng
Advanced simulation capability for environmental management (ASCEM): An overview of initial results
Essentials of multiphase flow and transport in porous media.multiphase, multicomponent flows in heterogeneous porous
Williamson, M.
Mathematical models of thermal and chemical transport in geologic media
Semi-analytical and numerical methods are used to investigate thermal and chemical transport processes in geologic media. The work is divided into two parts: (1) development of semi-analytical models for the analysis of uncoupled isothermal and nonisothermal fluid flow in naturally fractured media, and (2) development of a high resolution numerical code to address coupled nonisothermal chemical transport in geologic media. A semi-analytical model is developed for well test data analysis in naturally fractured reservoirs. A simple approximate analytical solution for pressure buildup and drawdown tests is developed. Methods based on the approximate solution are developed for the evaluation of important reservoir properties. Type curves for nonisothermal fluid flow in naturally fractured media are developed to design injection systems for maximum energy in hydrothermal systems. An accurate finite difference method for the solution of a convection-diffusion type equation is developed. The method is incorporated in a two-dimensional code to investigate free convection in a porous slab and kinetic silica-water reactions in geothermal systems. A multicomponent model considering the variations of pressure, temperature and silica concentration is developed to interpret the evolution of geothermal systems during exploitation.
Lai, C.-H.
Multicomponent seismic monitoring of the effective stimulated volume associated with hydraulic fracture stimulations in a shale reservoir, Pouce Coupe field, Alberta, Canada.
??The Reservoir Characterization Project in conjunction with Talisman Energy Inc., have been investigating a time-lapse data set acquired during hydraulic fracture stimulations of two horizontal� (more)
Steinhoff, Christopher
The Evolution of Multicomponent Systems at High Pressures: VI. The Thermodynamic Stability of the Hydrogen-Carbon System: The Genesis of Hydrocarbons and the Origin of Petroleum
The spontaneous genesis of hydrocarbons which comprise natural petroleum have been analyzed by chemical thermodynamic stability theory. The constraints imposed upon chemical evolution by the second law of thermodynamics are briefly reviewed; and the effective prohibition of transformation, in the regime of temperatures and pressures characteristic of the near-surface crust of the Earth, of biological molecules into hydrocarbon molecules heavier than methane is recognized. A general, first-principles equation of state has been developed by extending scaled particle theory (SPT) and by using the technique of the factored partition function of the Simplified Perturbed Hard Chain Theory (SPHCT). The chemical potentials, and the respective thermodynamic Affinity, have been calculated for typical components of the hydrogen-carbon (H-C) system over a range pressures between 1-100 kbar, and at temperatures consistent with those of the depths of the Earth at such pressures. The theoretical analyses establish that the ...
Kenney, J F; Bendeliani, N A; Alekseev, V A; Kutcherov, Vladimir G.; Bendeliani, Nikolai A.; Alekseev, Vladimir A.
WATER RESOURCES RESEARCH, VOL. 29, NO. 11, PAGES 3727-3740, NOVEMBER 1993 Modeling of Multiphase Transport of Multicomponent Organic Contaminants
in dispersed two-pahse flow", ANL-79-105, NUREG/CR- 1230, 1979. [14] G. B. Wallis, One-dimensional two
Patzek, Tadeusz W.
Ion Partitioning at the liquid/vapor interface of a multi-component alkali halide solution: A model for aqueous sea salt aerosols
model for aqueous sea salt aerosols Sutapa Ghosal, 1 Matthewwith sea salt ice and aerosols has been implicated in theof aqueous sea salt aerosols and particles have been
Ghosal, Sutapa
Charging of silica particles in an argon dusty plasma Edward Thomas, Jr.a)
and the National Science Foundation. 1 C. K. Goertz, Rev. Geophys. 27, 271 1989 . 2 M. Horanyi and D. A. Mendis. Aucillo and D. Flamm Academic, Boston, 1989 , p. 113. 14 E. C. Whipple, T. G. Northrop, and D. A. Mendis
Thomas Jr., Edward
Hierarchical and size dependent mechanical properties of silica and silicon nanostructures inspired by diatom algae
Biology implements fundamental principles that allow for attractive mechanical properties, as observed in biomineralized structures. For example, diatom algae contain nanoporous hierarchical silicified shells that provide ...
Garc�a, Andre Phillip�
245 Oxidation Behaviors of Silica Coated Mo-Si-B Alloys
021 Radiation Interactions in Biologically Important Materials ... 050 Investigation of ZnO:N and ZnO:(Al,N) Films for Solar Driven Hydrogen Production ... 070 A Phenomenological Thermodynamic Potential of CaTiO3 Single Crystals.
Linear and Nonlinear Spectroscopic Probing of Solute Interactions with Chemically Modified Silica Surfaces
Solar energy conversion through biology would provide a renewable and nonpolluting abundance of energy. The bacterium Halobacterium salinarum converts solar to electrical energy by virtue of a transmembrane protein, bacteriorhodopsin. This transmembrane protein pumps protons across a nonconducting bilayer upon irradiation with green light. The bacterium evolved to perform this function inefficiently. If we were able to understand this process to engineer this protein for efficiency, then inexpensive energy production could be achieved. There are tens of thousands of different types of halobacteria, giving the opportunity to study different efficiencies and relating these to the protein structures. Technology does not yet exist to perform such screening. The goal of this research is to generate new separation technology that can ultimately enable such screening. This involves creating a method for separating oriented and functional transmembrane proteins that remain in an electrically insulating lipid bilayer, with aqueous solutions on either side of the bilayer. A pH change across the lipid bilayer upon irradiation of a known concentration of proteins would probe function. Differences in proton pumping efficiency for different proteins variants would provide structure-function information for engineering the proteins. A schematic diagram from the original proposal is shown here. The idea is that (a) a lipid bilayer supported on a hydrophilic polymer film will make the bilayer fluid, and (b) applying an electric field will cause electrophoretic migration of the transmembrane proteins. We demonstrated this concept experimentally in a paper that was published just after this new grant period started (Lipid Bilayers on Polyacrylamide Brushes for Inclusion of Membrane Proteins, Emily A. Smith, Jason W. Coym, Scott M. Cowell, Victor J. Hruby, Henry I. Yamamura, Mary J. Wirth, Langmuir, 21, 9644-9650, 2005). The electrophoretic mobility was slow (10{sup -8} cm{sup 2}/Vs), and we project that a two order of magnitude increase would make this a practical tool. We are investigating two ways of improving electrophoretic mobility: better polymer supports, and a novel nanoporous medium that suspends the bilayer over free solution.
Wirth, Mary J
Mesoporous silica as a membrane for ultra-thin implantable direct glucose Tushar Sharma,a
failure warning systems, glucose and electrolyte sensors with systems such as an automated implantable car-linked hydro- gels, sulfonated polypropylene and cuprophan,2022 have been used to facilitate glucose diffusion and separate the electrodes. Rao et al.20,23 and Atanasov and Wilkins24 have used hydro- phobic membranes
Kaolinite Effects on Sintering of Freeze-Cast Kaolinite-Silica ...
Structural Characterization of Germanium and Gold - Germanium Nanoclusters Embedded in Silica
X-ray diffraction at SSRL. I would also like to thankexperiments were performed at SSRL, a national user facilityRadiation Lightsource (SSRL) to assess the crystal structure
Guzman, Julian
Persuance of Silica on Morphology and CO2/CH4 Gas Permeation ...
... in order to prevent condensation of water in the flat sheet membrane module. ... Mechanical and Physical Properties of Roof Tile Manufacturing from Red Mud.
Structure sensitive adsorption of hydrogen on ruthenium and ruthenium-silver catalysts supported on silica
Supported metal catalysts typically consist of particles with sizes less than 10 nm, and because of the small crystallite size, low coordination number sites (edges and corners) represent a significant fraction of all surface sites. Furthermore, it has been demonstrated that adsorption rates can be much greater at these low coordination sites than on basal plane sites. What has not been generally appreciated, however, is that preferential adsorption at edge and corner sites may explain the mechanism by which a promoter, or the addition of a second metal to form a bimetallic, can alter the selectivity and rate of reaction. For example, the measurements of hydrogen adsorption onto supported Ru-Ag catalysts show marked decreases in the amount of hydrogen adsorbed relative to the amount adsorbed on Ru catalysts. Although it is known that Ag does not dissociatively adsorb hydrogen, this decrease cannot be explained by a simple one-to-one site blocking mechanism unless Ag preferentially populates edges and corners, thereby reducing the number of Ru edge sites. Indeed, Monte Carlo simulations of Ru-Group IB metal catalysts predict that Group IB metal atoms preferentially populate corner and edge sites of ruthenium crystals. This evidence, taken together, suggests that adsorption occurs preferentially at Ru corner and edge sites, which act as portals onto basal planes. A model based on this portal theory for hydrogen adsorption onto supported ruthenium bimetallic catalysts has been developed using a rate equation approach. Specifically, the model accounts for the following features: (1) preferential adsorption through portals, (2) basal plane site-energy multiplicity, and (3) hydrogen spillover onto the support. A comparison of model predictions with experiment is presented for different concentration of Ag in Ru-Ag catalysts. The portal model of hydrogen adsorption can explain the observed decreased in the amount of hydrogen adsorbed on Ru-Ag catalysts. The model can be applied to understand the kinetics of ethane hydrogenolysis on Ru-Ag catalysts. The model is able to explain the change in the apparent order of hydrogenolysis reaction with respect to hydrogen from {minus}1.4 to {minus}2.4 when Ag is added to Ru/SiO{sub 2} catalyst.
Kumar, N.
Synthesis of attrition-resistant heterogeneous catalysts using templated mesoporous silica
The present invention relates to catalysts in mesoporous structures. In a preferred embodiment, the invention comprises a method for encapsulating a dispersed insoluble compound in a mesoporous structure comprising combining a soluble oxide precursor, a solvent, and a surfactant to form a mixture; dispersing an insoluble compound in the mixture; spray-drying the mixture to produce dry powder; and calcining the powder to yield a porous structure comprising the dispersed insoluble compound.
Pham, Hien N. (Albuquerque, NM); Datye, Abhaya K. (Albuquerque, NM)
A Well-Defined, Silica-Supported Tungsten Imido Alkylidene Olefin Metathesis Catalyst
olefin metathesis catalyst. Bouchra Rhers, a Alain Salameh,active propene metathesis catalyst, which can achieve 16000W-based olefin metathesis catalyst through the reaction of [
Nanostructured Cobalt Oxide Clusters in Mesoporous Silica as Efficient Oxygen-Evolving Catalysts
as Efficient Oxygen- Evolving Catalysts Feng Jiao and Heinzof efficient and robust catalysts for the chemicaltransformations. Catalysts need to exhibit turnover
Jiao, Feng
Synthesis, characterization, and evaluation of silica and polymer supported catalysts for the production of fine chemicals .
??Catalysis is an important field of study in chemical engineering and chemistry due to its application in a vast number of chemical transformations. Traditionally, catalysts� (more)
Shiels, Rebecca Anne
Water Diffusion and Interaction in Nano-porous Silica from First ...
Effect of Residual Tritiated Water on Air Detritiation Dryer Packed with Silica Gel
ITER Systems / Proceedings of the Nineteenth Topical Meeting on the Technology of Fusion Energy (TOFE) (Part 1)
Yasunori Iwai; Toshihiko Yamanishi
Vertical flux, ecology and dissolution of radiolaria in tropical oceans : implications for the silica cycle
Radiolarians which settle through the oceanic water column were recovered from three stations (western Tropical Atlantic-Station E, central Tropical Pacific-P1 and Panama Basin-PB) using PARFLUX sediment traps in moored ...
Takahashi, Kozo
Brief Communication Liposome encapsulation of fluorescent nanoparticles: Quantum dots and silica
nanoparticles Chien-Sheng Chen1 , Jie Yao2 and Richard A. Durst1, * 1 Department of Food Science & Technology & Durst, 2000; Esch et al., 2001; Ahn-Yoon et al., 2003; Baeumner et al., 2004; Ho et al., 2004
Chen, Chien-Sheng
Ostwald ripening of platinum nanoparticles confined in a carbon nanotube/silica-templated cylindrical space
Sintering of nanoparticles mediated by an Ostwald ripening mechanism is generally assessed examining the final particle size distributions. Based on this methodology, a general approach for depositing platinum nanoparticles onto carbon nanotubes in solution ...
Cintia Mateo-Mateo, Carmen V�zquez-V�zquez, Mois�s P�rez-Lorenzo, Ver�nica Salgueiri�o, Miguel A. Correa-Duarte
Mechanical properties of surface modified silica low-k thin films
The surface modification of sol-gel deposited low-k thin films has been carried out successfully by trimethylchlorosilane (TMCS) using wet chemical treatment method. Ellipsometer is used to determine the thickness of films. The changes in chemical structure ... Keywords: Contact angle, Hydrophobic, Nano-indentation, Sol-gel, Surface modification
Yogesh S. Mhaisagar, Bhavana N. Joshi, Ashok M. Mahajan
Atomic layer deposition of ZnO on ultralow-density nanoporous silica aerogel monoliths
We report on atomic layer deposition of an ? 2 -nm-thick ZnO layer on the inner surface of ultralow-density ( ? 0.5 % of the full density) nanoporoussilica aerogel monoliths with an extremely large effective aspect ratio of ? 10 5 (defined as the ratio of the monolith thickness to the average pore size). The resultant monoliths are formed by amorphous- SiO 2 core/wurtzite-ZnO shell nanoparticles which are randomly oriented and interconnected into an open-cell network with an apparent density of ? 3 % and a surface area of ? 10 0 m 2 g ? 1 . Secondary ion mass spectrometry and high-resolution transmission electron microscopy imaging reveal excellent uniformity and crystallinity of ZnO coating. Oxygen K -edge and Zn L 3 -edge soft x-ray absorption near-edge structure spectroscopy shows broadened O p - as well as Zn s - and d -projected densities of states in the conduction band.
S. O. Kucheyev; J. Biener; Y. M. Wang; T. F. Baumann; K. J. Wu; T. van Buuren; A. V. Hamza; J. H. Satcher Jr.; J. W. Elam; M. J. Pellin
Mesoporous silica nanoparticles as smart and safe devices for regulating blood biomolecule levels
Stimuli-responsive end-capped MSN materials are promising drug carriers that securely deliver a large payload of drug molecules without degradation or premature release. A general review of the recent progress in this field is presented, including a summary of a series of hard and soft caps for drug encapsulation and a variety of internal and external stimuli for controlled release of different therapeutics, a discussion of the biocompatibility of MSN both in vitro and in vivo, and a description of the sophisticated stimuli-responsive systems with novel capping agents and controlled release mechanism. The unique internal and external surfaces of MSN were utilized for the development of a glucose-responsive double delivery system end-capped with insulin. This unique system consists of functionalized MSNs capable of releasing insulin when the concentration of sugar in blood exceeds healthy levels. The insulin-free nanoparticles are then up taken by pancreatic cells, and release inside of them another biomolecule that stimulates the production of more insulin. The in vivo application of this system for the treatment of diabetes requires further understanding on the biological behaviors of these nanoparticles in blood vessels. The research presented in this dissertation demonstrated the size and surface effects on the interaction of MSNs with red blood cell membranes, and discovered how the surface of the nanoparticles can be modified to improve their compatibility with red blood cells and avoid their dangerous side effects. In order to optimize the properties of MSN for applying them as efficient intracellular drug carriers it is necessary to understand the factors that can regulate their internalization into and exocytosis out of the cells. The correlation between the particle morphology and aggregation of MSNs to the effectiveness of cellular uptake is discussed and compared with different cell lines. The differences in the degree of exocytosis of MSNs between healthy and cancer cells is reported and found to be responsible for the asymmetric transfer of the particles between both cell types. The fundamental studies on the hemocompatibility, endo- and exocytosis of MSN along with its ability to sequentially release multiple therapeutics in response to different stimuli, allow us to propose MSN as an intravascular vehicle with a great potential for various biomedical applications.
Zhao, Yan
Low Frequency Acoustic Resonance Studies of the Liquid-Vapor Transition in Silica Aerogel
Fluid phase transitions in porous media are a powerful probe of the effect of confinement and disorder on phase transitions. Aerogel may provide a model system in which to study the effect of dilute impurities on a variety of phase transitions. In this paper we present a series of low frequency acoustic experiments on the effect of aerogel on the liquid-vapor phase transition. Acoustic resonators were used to study the liquid-vapor transition in two fluids (helium and neon) and in two different porosity aerogels (95% and 98%). While effective coexistence curves could be mapped out, the transition was sometimes difficult to pinpoint, leading to doubt as to whether this transition can be treated as an equilibrium macroscopic phase transition at all.
Tobias Herman; John Beamish