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Sample records for synthetic sodium aluminosilicate

  1. 21 CFR 582.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Sodium aluminosilicate. 582.2727 Section 582.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  2. 21 CFR 182.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium aluminosilicate. 182.2727 Section 182.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  3. 21 CFR 182.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium aluminosilicate. 182.2727 Section 182.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  4. 21 CFR 182.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium aluminosilicate. 182.2727 Section 182.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  5. 21 CFR 582.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Sodium aluminosilicate. 582.2727 Section 582.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  6. 21 CFR 182.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium aluminosilicate. 182.2727 Section 182.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  7. 21 CFR 582.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Sodium aluminosilicate. 582.2727 Section 582.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  8. 21 CFR 182.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium aluminosilicate. 182.2727 Section 182.2727...) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2727 Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance. This substance is generally recognized...

  9. 21 CFR 582.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sodium aluminosilicate. 582.2727 Section 582.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  10. 21 CFR 582.2727 - Sodium aluminosilicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Sodium aluminosilicate. 582.2727 Section 582.2727 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Sodium aluminosilicate. (a) Product. Sodium aluminosilicate (sodium silicoaluminate). (b) Tolerance....

  11. 21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729... Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as...

  12. 21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium calcium aluminosilicate, hydrated. 182.2729... § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as...

  13. 21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium calcium aluminosilicate, hydrated. 182.2729... § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as...

  14. 21 CFR 582.2729 - Hydrated sodium calcium aluminosilicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Hydrated sodium calcium aluminosilicate. 582.2729... Agents § 582.2729 Hydrated sodium calcium aluminosilicate. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium silicoaluminate). (b) Tolerance. This substance is generally recognized as...

  15. 21 CFR 182.2729 - Sodium calcium aluminosilicate, hydrated.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium calcium aluminosilicate, hydrated. 182.2729... (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2729 Sodium calcium aluminosilicate, hydrated. (a) Product. Hydrated sodium calcium aluminosilicate (sodium calcium...

  16. Impact Of Sodium Oxalate, Sodium Aluminosilicate, and Gibbsite/Boehmite on ARP Filter Performance

    SciTech Connect

    Poirier, M.; Burket, P.

    2015-11-01

    The Savannah River Site (SRS) is currently treating radioactive liquid waste with the Actinide Removal Process (ARP) and the Modular Caustic Side Solvent Extraction Unit (MCU). Recently, the low filter flux through the ARP of approximately 5 gallons per minute has limited the rate at which radioactive liquid waste can be treated. Salt Batch 6 had a lower processing rate and required frequent filter cleaning. Savannah River Remediation (SRR) has a desire to understand the causes of the low filter flux and to increase ARP/MCU throughput. SRR requested SRNL to conduct bench-scale filter tests to evaluate whether sodium oxalate, sodium aluminosilicate, or aluminum solids (i.e., gibbsite and boehmite) could be the cause of excessive fouling of the crossflow or secondary filter at ARP. The authors conducted the tests by preparing slurries containing 6.6 M sodium Salt Batch 6 supernate, 2.5 g MST/L slurry, and varying concentrations of sodium oxalate, sodium aluminosilicate, and aluminum solids, processing the slurry through a bench-scale filter unit that contains a crossflow primary filter and a dead-end secondary filter, and measuring filter flux and transmembrane pressure as a function of time. Among the conclusions drwn from this work are the following: (1) All of the tests showed some evidence of fouling the secondary filter. This fouling could be from fine particles passing through the crossflow filter. (2) The sodium oxalate-containing feeds behaved differently from the sodium aluminosilicate- and gibbsite/boehmite-containing feeds.

  17. SODIUM ALUMINOSILICATE FOULING AND CLEANING OF DECONTAMINATED SALT SOLUTION COALESCERS

    SciTech Connect

    Poirier, M; Thomas Peters, T; Fernando Fondeur, F; Samuel Fink, S

    2008-10-28

    During initial non-radioactive operations at the Modular Caustic Side Solvent Extraction Unit (MCU), the pressure drop across the decontaminated salt solution coalescer reached {approx}10 psi while processing {approx}1250 gallons of salt solution, indicating possible fouling or plugging of the coalescer. An analysis of the feed solution and the 'plugged coalescer' concluded that the plugging was due to sodium aluminosilicate solids. MCU personnel requested Savannah River National Laboratory (SRNL) to investigate the formation of the sodium aluminosilicate solids (NAS) and the impact of the solids on the decontaminated salt solution coalescer. Researchers performed developmental testing of the cleaning protocols with a bench-scale coalescer container 1-inch long segments of a new coalescer element fouled using simulant solution. In addition, the authors obtained a 'plugged' Decontaminated Salt Solution coalescer from non-radioactive testing in the MCU and cleaned it according to the proposed cleaning procedure. Conclusions from this testing include the following: (1) Testing with the bench-scale coalescer showed an increase in pressure drop from solid particles, but the increase was not as large as observed at MCU. (2) Cleaning the bench-scale coalescer with nitric acid reduced the pressure drop and removed a large amount of solid particles (11 g of bayerite if all aluminum is present in that form or 23 g of sodium aluminosilicate if all silicon is present in that form). (3) Based on analysis of the cleaning solutions from bench-scale test, the 'dirt capacity' of a 40 inch coalescer for the NAS solids tested is calculated as 450-950 grams. (4) Cleaning the full-scale coalescer with nitric acid reduced the pressure drop and removed a large amount of solid particles (60 g of aluminum and 5 g of silicon). (5) Piping holdup in the full-scale coalescer system caused the pH to differ from the target value. Comparable hold-up in the facility could lead to less effective

  18. An Electron Microprobe Study of Synthetic Aluminosilicate Garnets

    NASA Astrophysics Data System (ADS)

    Fournelle, J.; Geiger, C. A.

    2010-12-01

    The aluminosilicate garnets represent an important mineral group. Common end-members are given by E3Al2Si3O12, where E=Fe2+ (almandine), Mn2+ (spessartine), Mg (pyrope), and Ca (grossular). End-members have been synthesized, but their exact compositions and stoichiometries are generally unknown. Synthetic aluminosilicate garnet can possibly contain minor Fe3+, Mn3+, F- and OH- and possibly vacancies. Slight atomic disorder over the 3 different cation sites may also occur. Natural crystals are considerably more complex. Electron probe microanalysis (EPMA) provides a method to determine garnet chemistry and stoichiometry. However, accurate determinations are not always a simple matter and uncertainties exist. We have started a study on well-characterized synthetic aluminosilicate garnets in order to i) determine more exactly their compositions and stoichiometries and ii) better understand possible complications in EPMA. Synthetic almandine, spessartine, pyrope, and grossular samples were synthesized under varying conditions both hydrothermally and dry and with different starting materials. A closed thermodynamic system was present and the bulk starting material composition represented the exact stoichiometric end-member garnet that was desired. IR, Raman and Mössbauer spectroscopy in some cases and X-ray diffraction were used to characterize the samples. Synthetic pyrope has been investigated with a SX51 with simple oxide/silicate standards (Fo90 olivine for Mg, wollastonite for Si, and both Al2O3 and kyanite for Al). Previously observed problems were reproduced: low stoichiometry for Al and high for Si and Mg. Fournelle (2007, AGU Fall Mtg) noted chemical peak shifts for Al and Mg Ka in garnets; this effect was eliminated here by proper peaking. Earlier suggestions for issues with mass absorption coefficients were not seen, and Probe for EPMA software demonstrated there was not much difference between the most recent FFAST values vs. the older Heinrich values

  19. SODIUM ALUMINOSILICATE SOLIDS AFFINITY FOR CESIUM AND ACTINIDES

    SciTech Connect

    Peters, T; Bill Wilmarth, B; Samuel Fink, S

    2007-07-31

    Washed sodium-aluminosilicate (NAS) solids at initial concentrations of 3.55 and 5.4 g/L sorb or uptake virtually no cesium over 288 hours, nor do any NAS solids generated during that time. These concentrations of solids are believed to conservatively bound current and near-term operations. Hence, the NAS solids should not have affected measurements of the cesium during the mass transfer tests and there is minimal risk of accumulating cesium during routine operations (and hence posing a gamma radiation exposure risk in maintenance). With respect to actinide uptake, it appears that NAS solids sorb minimal quantities of uranium - up to 58 mg U per kg NAS solid. The behavior with plutonium is less well understood. Additional study may be needed for radioactive operations relative to plutonium or other fissile component sorption or trapping by the solids. We recommend this testing be incorporated in the planned tests using samples from Tank 25F and Tank 49H to extend the duration to bound expected inventory time for solution.

  20. Aqueous dissolution of sodium aluminosilicate geopolymers derived from metakaolin

    NASA Astrophysics Data System (ADS)

    Aly, Z.; Vance, E. R.; Perera, D. S.

    2012-05-01

    In dilute aqueous solutions, the elemental releases of Na, Al and Si from a metakaolin-based sodium aluminosilicate geopolymer were not very sensitive to pH in the range of 4-10 but increased outside this range, particularly on the acidic side. To minimise pH drifts, experiments were carried out using small amounts of graded powders in relatively large volumes of water. In deionised water, the Na dissolution rate in 7 days was dominant and increased by at least a factor of ˜4 on heating from 18 to 90 °C, with greater increases in the extractions of Al and Si. At 18 °C the elemental extractions in deionised water increased approximately linearly with time over the 1-7 days period. Further exposure led to a slower extraction into solution for Na and Si, with a decrease in extraction of Al. It was deduced that framework dissolution was important in significantly acidic or alkaline solutions, but that contributions from water transfer from pores to elemental extractions were present, even at low temperatures in neutral solutions. It was also deduced from the Na release data that the Na leaching kinetics of geopolymer in deionised water (dilute solutions) followed the pseudo-second-order kinetic model and the pseudo-second-order rate constant evaluated. Contact with KCl, KHCO3, and pH ˜6 and 10 potassium phthalate buffer solutions gave rise to a high degree of Na+ ↔ K+ exchange and rendered the framework ions less leachable in water.

  1. Phase evolution of Na2O-Al2O3-SiO2-H2O gels in synthetic aluminosilicate binders.

    PubMed

    Walkley, Brant; San Nicolas, Rackel; Sani, Marc-Antoine; Gehman, John D; van Deventer, Jannie S J; Provis, John L

    2016-04-01

    This study demonstrates the production of stoichiometrically controlled alkali-aluminosilicate gels ('geopolymers') via alkali-activation of high-purity synthetic amorphous aluminosilicate powders. This method provides for the first time a process by which the chemistry of aluminosilicate-based cementitious materials may be accurately simulated by pure synthetic systems, allowing elucidation of physicochemical phenomena controlling alkali-aluminosilicate gel formation which has until now been impeded by the inability to isolate and control key variables. Phase evolution and nanostructural development of these materials are examined using advanced characterisation techniques, including solid state MAS NMR spectroscopy probing (29)Si, (27)Al and (23)Na nuclei. Gel stoichiometry and the reaction kinetics which control phase evolution are shown to be strongly dependent on the chemical composition of the reaction mix, while the main reaction product is a Na2O-Al2O3-SiO2-H2O type gel comprised of aluminium and silicon tetrahedra linked via oxygen bridges, with sodium taking on a charge balancing function. The alkali-aluminosilicate gels produced in this study constitute a chemically simplified model system which provides a novel research tool for the study of phase evolution and microstructural development in these systems. Novel insight of physicochemical phenomena governing geopolymer gel formation suggests that intricate control over time-dependent geopolymer physical properties can be attained through a careful precursor mix design. Chemical composition of the main N-A-S-H type gel reaction product as well as the reaction kinetics governing its formation are closely related to the Si/Al ratio of the precursor, with increased Al content leading to an increased rate of reaction and a decreased Si/Al ratio in the N-A-S-H type gel. This has significant implications for geopolymer mix design for industrial applications. PMID:26911317

  2. Studies of Potential Inhibitors of Sodium Aluminosilicate Scales in High-Level Waste Evaporation

    SciTech Connect

    Oji, L.N.; Fellinger, T.L.; Hobbs, D.T.; Badheka, N.P.; Wilmarth, W.R.

    2008-07-01

    The Savannah River Site (SRS) has 49 underground storage tanks used to store High Level Waste (HLW). The tank space in these tanks must be managed to support the continued operation of key facilities. The reduction of the tank volumes in these tanks are accomplished through the use of three atmospheric pressure HLW evaporators. For a decade, evaporation of highly alkaline HLW containing dissolved aluminate and silicate has produced sodium aluminosilicate scales causing both operation and criticality hazards in the 2H Evaporator System. Segregation of aluminum-rich wastes from silicate-rich wastes minimizes the amount of scale produced and reduces cleaning expenses, but does not eliminate the scaling nor increases operation flexibility in waste process. Similar issues have affected the aluminum refining industry for many decades. Over the past several years, successful commercial products have been identified to eliminate aluminosilicate fouling in the aluminum industry, but have not been utilized in a nuclear environment. Laboratory quantities of three proprietary aluminosilicate scale inhibitors have been produced and been shown to prevent formation of scales. SRNL has been actively testing these potential inhibitors to examine their radiation stability, radiolytic degradation behaviors, and downstream impacts to determine their viability within the HLW system. One of the tested polymers successfully meets the established criteria for application in the nuclear environment. This paper will describe a summary of the methodology used to prioritize laboratory testing protocols based on potential impacts/risks identified for inhibitor deployment at SRS. (authors)

  3. STUDIES OF POTENTIAL INHIBITORS OF SODIUM ALUMINOSILICATE SCALES IN HIGH-LEVEL WASTE EVAPORATION

    SciTech Connect

    Wilmarth, B; Lawrence Oji, L; Terri Fellinger, T; David Hobbs, D; Nilesh Badheka, N

    2008-02-27

    The Savannah River Site (SRS) has 49 underground storage tanks used to store High Level Waste (HLW). The tank space in these tanks must be managed to support the continued operation of key facilities. The reduction of the tank volumes in these tanks are accomplished through the use of three atmospheric pressure HLW evaporators. For a decade, evaporation of highly alkaline HLW containing aluminum and silicates has produced sodium aluminosilicate scales causing both operation and criticality hazards in the 2H Evaporator System. Segregation of aluminum-rich wastes from silicate-rich wastes minimizes the amount of scale produced and reduces cleaning expenses, but does not eliminate the scaling nor increases operation flexibility in waste process. Similar issues have affected the aluminum refining industry for many decades. Over the past several years, successful commercial products have been identified to eliminate aluminosilicate fouling in the aluminum industry, but have not been utilized in a nuclear environment. Laboratory quantities of three proprietary aluminosilicate scale inhibitors have been produced and been shown to prevent formation of scales. SRNL has been actively testing these potential inhibitors to examine their radiation stability, radiolytic degradation behaviors, and downstream impacts to determine their viability within the HLW system. One of the tested polymers successfully meets the established criteria for application in the nuclear environment. This paper will describe a summary of the methodology used to prioritize laboratory testing protocols based on potential impacts/risks identified for inhibitor deployment at SRS.

  4. Structure and properties of sodium aluminosilicate glasses from molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Xiang, Ye; Du, Jincheng; Smedskjaer, Morten M.; Mauro, John C.

    2013-07-01

    Addition of alumina to sodium silicate glasses considerably improves the mechanical properties and chemical durability and changes other properties such as ionic conductivity and melt viscosity. As a result, aluminosilicate glasses find wide industrial and technological applications including the recent Corning® Gorilla® Glass. In this paper, the structures of sodium aluminosilicate glasses with a wide range of Al/Na ratios (from 1.5 to 0.6) have been studied using classical molecular dynamics simulations in a system containing around 3000 atoms, with the aim to understand the structural role of aluminum as a function of chemical composition in these glasses. The short- and medium-range structures such as aluminum coordination, bond angle distribution around cations, Qn distribution (n bridging oxygen per network forming tetrahedron), and ring size distribution have been systematically studied. In addition, the mechanical properties including bulk, shear, and Young's moduli have been calculated and compared with experimental data. It is found that aluminum ions are mainly four-fold coordinated in peralkaline compositions (Al/Na < 1) and form an integral part of the rigid silicon-oxygen glass network. In peraluminous compositions (Al/Na > 1), small amounts of five-fold coordinated aluminum ions are present while the concentration of six-fold coordinated aluminum is negligible. Oxygen triclusters are also found to be present in peraluminous compositions, and their concentration increases with increasing Al/Na ratio. The calculated bulk, shear, and Young's moduli were found to increase with increasing Al/Na ratio, in good agreement with experimental data.

  5. A new titanium-bearing calcium aluminosilicate phase. 1: Meteoritic occurrences and formation in synthetic systems

    NASA Technical Reports Server (NTRS)

    Paque, Julie M.; Beckett, John R.; Barber, David J.; Stolper, Edward M.

    1994-01-01

    A new titanium-bearing calcium aluminosilicate mineral has been identified in coarse-grained calcium-aluminum-rich inclusions (CAIs) from carbonaceous chondrites. The formula for this phase, which we have temporarily termed 'UNK,' is Ca3Ti(Al,Ti)2(Si,Al)3O14, and it is present in at least 8 of the 20 coarse-grained CAIs from the Allende CV3 chondrite examined as part of this project. The phase occurs in Types A and B1 inclusions as small tabular crystal oriented along two mutually perpendicular planes in melilite. UNK crystallizes from melts in dynamic crystallization experiments conducted in air from four bulk compositions modeled after Types A, B1, B2 and C inclusions. Cooling rates resulting in crystallization of UNK ranged from 0.5 to 200 C/h from maximum (initial) temperatures of 1375 to 1580 C. Only below 1190 C does UNK itself begin to crystallize. To first order, the presence or absence of UNK from individual experiments can be understood in terms of the compositions of residual melts and nucleation probabilities. Compositions of synthetic and meteoritic UNK are very similar in terms of major oxides, differing only in the small amounts of trivalent Ti(7-13% of total Ti) in meteoritic samples. UNK crystallized from the Type A analog is similar texturally to that found in CAIs, although glass, which is typically associated with synthetic UNK, is not observed in the meteoritic occurrences. A low Ti end-member of UNK ('Si-UNK') with a composition near that of Ca3Al2Si4O14 was produced in a few samples from the Type B1 analog. This phase has not been found in the meteoritic inclusions.

  6. A New Titanium-Bearing Calcium Aluminosilicate Phase. 1; Meteoritic Occurrences and Formation in Synthetic Systems

    NASA Technical Reports Server (NTRS)

    Paque, Julie M.; Beckett, John R.; Barber, David J.; Stolper, Edward M.

    1994-01-01

    A new titanium-bearing calcium aluminosilicate mineral has been identified in coarse-grained calcium-aluminum-rich inclusions (CAIs) from carbonaceous chondrites. The formula for this phase, which we have temporarily termed "UNK," is Ca3Ti(AlTi)2(Si,Al)3O14, and it is present in at least 8 of the 20 coarse-grained CAIs from the Allende CV3 chondrite examined as part of this project. The phase occurs in Types A and B1 inclusions as small tabular crystals oriented along two mutually perpendicular planes in melilite. UNK crystallizes from melts in dynamic crystallization experiments conducted in air from four bulk compositions modeled after Types A, B1, B2 and C inclusions. Cooling rates resulting in crystallization of UNK ranged from 0.5 to 200 C/h from maximum (initial) temperatures of 1375 to 1580 C. Only below 1190 C does UNK itself begin to crystallize. To first order, the presence or absence of UNK from individual experiments can be understood in terms of the compositions of residual melts and nucleation probabilities. Compositions of synthetic and meteoritic LINK are very similar in terms of major oxides, differing only in the small amounts of trivalent Ti (7-13% of total Ti) in meteoritic samples. UNK crystallized from the Type A analog is similar texturally to that found in CAls, although glass, which is typically associated with synthetic UN& is not observed in meteoritic occurrences. A low Ti end-member of UNK ("Si-UNK") with a composition new that of Ca3Al2Si4O14 was produced in a few samples from the Type B1 analog. This phase has not been found in the meteoritic inclusions.

  7. Effects of Thermal and Pressure Histories on the Chemical Strengthening of Sodium Aluminosilicate Glass

    NASA Astrophysics Data System (ADS)

    Svenson, Mouritz; Thirion, Lynn; Youngman, Randall; Mauro, John; Bauchy, Mathieu; Rzoska, Sylwester; Bockowski, Michal; Smedskjaer, Morten

    2016-03-01

    Glasses can be chemically strengthened through the ion exchange process, wherein smaller ions in the glass (e.g., Na+) are replaced by larger ions from a salt bath (e.g., K+). This develops a compressive stress (CS) on the glass surface, which, in turn, improves the damage resistance of the glass. The magnitude and depth of the generated CS depends on the thermal and pressure histories of the glass prior to ion exchange. In this study, we investigate the ion exchange-related properties (mutual diffusivity, CS, and hardness) of a sodium aluminosilicate glass, which has been densified through annealing below the initial fictive temperature of the glass or through pressure-quenching from the glass transition temperature at 1 GPa prior to ion exchange. We show that the rate of alkali interdiffusivity depends only on the density of the glass, rather than on the applied densification method. However, we also demonstrate that for a given density, the increase in CS and increase in hardness induced by ion exchange strongly depends on the densification method. Specifically, at constant density, the CS and hardness values achieved through thermal annealing are larger than those achieved through pressure-quenching. These results are discussed in relation to the structural changes in the environment of the network-modifier and the overall network densification.

  8. Hydrated sodium calcium aluminosilicate for reduction of aflatoxin in quails (Coturnix coturnix japonica).

    PubMed

    Sehu, A; Ergün, L; Cakir, S; Ergün, E; Cantekin, Z; Sahin, T; Essiz, D; Sareyyüpoğlu, B; Gürel, Y; Yiğit, Y

    2007-07-01

    The purpose of the present study was to evaluate the toxic effects of aflatoxin (AF) on growth performance and various processing parameters of quails and to determine the preventive efficacy of hydrated sodium calcium aluminosilicate (HSCAS). One hundred and eighty 1-d-old quails of both sexes were randomly divided into 4 experimental groups with 5 replicates and 45 birds following weighing. The experimental design consisted of four dietary treatments: 1) control with 0 mg AF/kg of diet and 0% HSCAS; 2) 0.5% HSCAS; 3) 2.5 mg AF/kg of diet; 4) 2.5 mg AF/kg of diet plus 0.5% HSCAS. The chicks were housed in electrically heated battery cages and exposed to light for 24 h from hatching to 3 weeks of age. Quails consumed the diets and water ad libitum. Body weight (BW) was significantly (p < 0.001) increased by addition of HSCAS to AF diet. The lowest BW gains in groups received AF alone was observed at all periods. The reduction in BW gain caused by 2.5 mg AF/kg of diet was significantly (p < 0.001) diminished by the addition of 0.5% HSCAS to the diet. The addition of HSCAS to the AF diet significantly (p < 0.001) protected against decrease of feed intake at all periods with exception of the first period. None of the treatments altered significantly the feed conversion ratio (FCR). The relative weights of the liver, kidney and spleen were increased in the chickens consuming the AF alone diet. However, light microscopic examination demonstrated the addition of HSCAS to quail feed to partially decrease fat deposition caused by the toxin, and besides, electron microscopic examination of indicated a reorganization in the endoplasmic reticulum and increase in the number of ribosomes and polisomes. Furthermore, the decrease in the antibody titre induced by Newcastle vaccine, due to aflatoxins, was relatively prevented. No significant differences were observed for serum total protein, total cholesterol and glucose levels. The results of indicate that HSCAS is effective in

  9. Sodium sulfate corrosion of silicon carbide fiber-reinforced calcium aluminosilicate glass-ceramic matrix composites. Master's thesis

    SciTech Connect

    Newton, P.J.

    1994-03-01

    Hot corrosion effects of Sodium Sulfate (NaSO4) coated Calcium Aluminosilicate (CAS)/Silicon Carbide (SiC) reinforced glass-ceramic matrix composite were investigated using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and X-ray Diffraction (XRD). The samples provided by the Naval Air Warfare Center (NAWC) were unidirectional SiC/CAS as follows: (1) as received, (2) uncoated in air, (3) Na2SO4, coated in air and (4) Na2SO4 coated in argon. A heat treatment was conducted at 900 deg C for 100 hours. Experimental observations indicated that the Na2S04 coating in an oxidising environment had severely corroded the silicon fiber resulting in a silica rich, Nepheline, Wollastonite, Rankinite, Albite and glassy phases. In the argon atmosphere fiber degradation was present although less severe than in the oxygen environment. Similar phases of silica rich, Nepheline, Albite, Rankinite, Mullite, Pseudo-Wollastonite and a glassy region were present. Minimal fiber and matrix degradation was observed in the uncoated sample beat treated in air. Calcium aluminosilicate, SiC Fiber reinforced composites.

  10. Effect of Eu3+ concentration on the grating efficiency and ionic conductivity in sodium-magnesium-aluminosilicate glasses

    NASA Astrophysics Data System (ADS)

    Hamad, Abdulatif Y.; Wicksted, James P.; Ascio, Robert; Martin, Joel J.; Hunt, Charles; Dixon, George S.

    2002-09-01

    We report a systematic study of a grating formation in which the Eu2O3 in sodium-magnesium-aluminosilicate glasses is varied from 0.76 to 8.11 mol %. The growth, decay, and erasure of the grating are reported as functions of the Eu2O3. The maximum persistent change in the index of refraction was 3 x10-5. The persistent change in the index of refraction was initially a quadratic function of the Eu2O3 and showed a limiting behavior at the highest Eu2O3. The transient change in the index of refraction Deltantran was a quadratic function of Eu2O3 throughout the range of concentrations studied here. The grating buildup rate increased linearly with Deltantran. The results of this study are consistent with the model published recently by Dixon [et al.] Ionic conductivities were also measured to help separate the effect of the Eu3+ on the glass network from its active role in transferring the optical energy into ionic motion.

  11. Sodium sulfate corrosion of silicon carbide fiber-reinforced lithium aluminosilicate glass-ceramic matrix composites. Master's thesis

    SciTech Connect

    Maldia, L.C.

    1993-12-01

    Sodium sulfate hot corrosion of a SiC fiber-reinforced lithium aluminosilicate (LAS) glass-ceramic matrix composite was studied using Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD). Changes in the microstructural chemical composition of the specimens were investigated. The samples provided by Naval Air Warfare Center (NAWC), Warminster, PA were grouped as follows: (1) as-received, (2) Na2SO4 salt-coated and heat-treated in oxygen, (3) noncoated and heat-treated in oxygen, (4) Na2SO4. Salt-coated and heat-treated in argon, and (5) noncoated and heat-treated in argon. Heat treatment was performed by NAWC for 100 hours at 900 deg C. Experimental data obtained indicated that the presence of Na2SO4 in an oxidative environment resulted in rapid corrosion of the matrix and SiC fibers and in the latter rings of SiO2 replaced what had previously been SiC. There was very limited degradation of the fibers and matrix exposed at the surface in the noncoated sample heat-treated in oxygen and in the salt-coated sample heat-treated in argon. A significant reduction in the amount of mullite in the matrices of all heat-treated samples was observed. Mullite dissolved into either the glassy phase or into the Beta-spodumene matrix. Lastly, the presence of distinct magnesium silicate crystalline phases in the salt-coated and heat-treated in oxygen sample implies that the MgO at the surface reacted with the SiO2 in the matrix.

  12. The protective effect of hydrated sodium calcium aluminosilicate against haematological, biochemical and pathological changes induced by Zearalenone in mice.

    PubMed

    Abbès, Samir; Ouanes, Zouhour; ben Salah-Abbès, Jalila; Houas, Zohra; Oueslati, Ridha; Bacha, Hassen; Othman, Omar

    2006-04-01

    Hydrated sodium calcium aluminosilicate (HSCAS), an anticaking agent for mixed feed, was added alone or simultaneously with a toxic Zearalenone (ZEN) dose to balb/c mice and was evaluated for its ability to restore damages induced by ZEN. The latter is a mycotoxin produced by fusarium genera; it is mainly known to induce several toxic effects such as hepatotoxicity, immunotoxicity and nephrotoxicity on animals and humans. The experimental approach consisted of eight treatments of six mice each by 400 mg/kg bw or 5 g/kg bw of HSCAS. Two experimental groups have received respectively ZEN alone at 40 (8% of LD50) and at 500 mg/kg bw (LD50). Two other groups have received ZEN at 40 or 500 mg/kg bw combined respectively with HSCAS at 400 mg/kg bw and 5 g/kg bw. The control groups received water or olive oil. Forty-eight hours after treatment, blood samples were collected for haematological and serum biochemical parameters measurements. ZEN treatment significantly increased hematocrit, haemoglobin, white blood cells: lymphocytes, eosinophils, neutrophils, monocytes and the most of biochemical serum parameters; it significantly reduced platelets and induced degenerative changes in the hepatic and renal tissues; while, the mixture of HSCAS with ZEN induced a reestablishment of haematological parameters, levels of serum biochemical enzyme activities and histological pictures of both liver and kidney. It also prevented general toxicity of ZEN. This was observed by the shift of LD50 for this toxin. Thus, our data strongly suggested that deleterious effects of ZEN could be overcome or, at least, significantly were diminished by HSCAS. Moreover, this sorbent by itself did not show any toxic effects. PMID:16563452

  13. The role of Al3+ on rheology and structural changes in sodium silicate and aluminosilicate glasses and melts

    NASA Astrophysics Data System (ADS)

    Le Losq, Charles; Neuville, Daniel R.; Florian, Pierre; Henderson, Grant S.; Massiot, Dominique

    2014-02-01

    Because of their importance in both the geosciences and the glass-making industry, alkali aluminosilicate melts have been the focal point of many past studies, but despite progress many problems remain unresolved, such as the complex behaviour of the thermodynamic properties of aluminium-rich alkali silicate melts. This paper presents a study of Na2O-Al2O3-SiO2 glasses and melts, containing 75 mol% SiO2 and different Al/(Al + Na) ratios. Their structure has been investigated by using Raman spectroscopy, as well as, 23Na, 27Al and 29Si 1D MAS NMR spectroscopy. Results confirm the role change of Na+ cations from network modifier to charge compensator in the presence of Al3+ ions. In addition, polymerization increases with increase of the Al/(Al + Na) ratio. These structural changes explain the observed variations in the viscosity of these melts. The viscosity data in turn allow us to calculate the configurational entropy of melts at the glass transition temperature [the Sconf(Tg)]. The variations of the Sconf(Tg) are strongly nonlinear, with sharp increases and decreases depending on the Al/(Al + Na) ratio. More importantly, a strong increase of the Sconf(Tg) is observed when a few Al2O3 is added to sodium silicate melt. A strong decrease is observed after crossing the tectosilicate join, when Al/(Al + Na) > 0.5 and when Al3+ ions are present in fivefold coordination, Al[5], in the glass. Furthermore, in situ27Al NMR spectra of the peraluminous melt show a clear increase of the Al[5] concentration with increasing temperature. When considered in combination with melt fragility and heat capacity, our data demonstrate that Al[5] is clearly a transient unit at high temperature in highly polymerized tectosilicate and peraluminous melts. However, when present in glasses, Al[5] increases the stability of the aluminosilicate network, hence the Tg of glasses. This could be explained by the ability of Al[5] to carry threefold coordinated oxygen atoms in its first coordination

  14. The role of Al3+ on rheology and structural changes in sodium silicate and aluminosilicate glasses and melts

    NASA Astrophysics Data System (ADS)

    Le Losq, Charles; Neuville, Daniel R.; Florian, Pierre; Henderson, Grant S.; Massiot, Dominique

    2014-02-01

    Because of their importance in both the geosciences and the glass-making industry, alkali aluminosilicate melts have been the focal point of many past studies, but despite progress many problems remain unresolved, such as the complex behaviour of the thermodynamic properties of aluminium-rich alkali silicate melts. This paper presents a study of Na2O-Al2O3-SiO2 glasses and melts, containing 75 mol% SiO2 and different Al/(Al + Na) ratios. Their structure has been investigated by using Raman spectroscopy, as well as, 23Na, 27Al and 29Si 1D MAS NMR spectroscopy. Results confirm the role change of Na+ cations from network modifier to charge compensator in the presence of Al3+ ions. In addition, polymerization increases with increase of the Al/(Al + Na) ratio. These structural changes explain the observed variations in the viscosity of these melts. The viscosity data in turn allow us to calculate the configurational entropy of melts at the glass transition temperature [the Sconf(Tg)]. The variations of the Sconf(Tg) are strongly nonlinear, with sharp increases and decreases depending on the Al/(Al + Na) ratio. More importantly, a strong increase of the Sconf(Tg) is observed when a few Al2O3 is added to sodium silicate melt. A strong decrease is observed after crossing the tectosilicate join, when Al/(Al + Na) > 0.5 and when Al3+ ions are present in fivefold coordination, Al[5], in the glass. Furthermore, in situ27Al NMR spectra of the peraluminous melt show a clear increase of the Al[5] concentration with increasing temperature. When considered in combination with melt fragility and heat capacity, our data demonstrate that Al[5] is clearly a transient unit at high temperature in highly polymerized tectosilicate and peraluminous melts. However, when present in glasses, Al[5] increases the stability of the aluminosilicate network, hence the Tg of glasses. This could be explained by the ability of Al[5] to carry threefold coordinated oxygen atoms in its first coordination

  15. Efficiency of hydrated sodium calcium aluminosilicate to ameliorate the adverse effects of graded levels of aflatoxin B1 in broiler chicks.

    PubMed

    Chen, X; Horn, N; Applegate, T J

    2014-08-01

    The objective of this study was to evaluate the efficiency of a hydrated sodium calcium aluminosilicate (HSCAS) adsorbent to ameliorate the adverse effects of 0.5 to 2 mg of aflatoxin B1 (AFB1)/kg in broiler chicks. The study consisted of 8 dietary treatments, including 4 concentrations of AFB1 (0, 0.5, 1, and 2 mg/kg) with or without HSCAS (0.5%) fed to 8 replicate cages per diet (6 males chicks per cage) from 0 to 21 d of age. Cumulative feed intake, BW gain (P < 0.0001), and G:F (P = 0.004) of birds fed the 2 mg of AFB1/kg of diet were significantly lower in comparison with birds fed 0 to 1 mg of AFB1/kg. Relative liver weight was increased in the 2 mg of AFB1/kg group (P < 0.0001). Dietary HSCAS improved cumulative BW gain (main effect P = 0.06), particularly from 14 to 21 d of age (P = 0.037). Dietary HSCAS also reversed the increase in relative liver weight for birds fed AFB1 (P = 0.019). Dietary AFB1 negatively affected major serum parameters (albumin, total protein, globulin, phosphorus, glucose, alkaline phosphatase, and creatine phosphokinase), whereas supplementation with HSCAS partially alleviated the affected serum biochemistry. In addition, serum complement activity and liver gene expression were negatively affected by 2 mg of AFB1/kg. The HSCAS supplement increased the liver expression of catalase and superoxide dismutase (P < 0.05). Results from this study indicate that dietary supplementation with HSCAS can effectively improve BW gain and partially ameliorate aflatoxicosis for broiler chicks fed AFB1-contaminated feeds. PMID:24894529

  16. Steam Reforming Technology Demonstration for Conversion of DOE Sodium-Bearing Tank Wastes at Idaho National Laboratory into a Leach-Resistant Alkali Aluminosilicate Waste Form

    SciTech Connect

    Ryan, K.; Bradley Mason, J.; Evans, B.; Vora, V.; Olson, A.

    2008-07-01

    The patented THOR{sup R} fluidized-bed steam reforming (FBSR) technology was selected by the U.S. Department of Energy (DOE) for treatment of sodium-bearing waste (SBW) in the Integrated Waste Treatment Unit (IWTU), currently under construction at the Idaho National Laboratory (INL) Site.1 SBW is an acidic waste created primarily from cleanup of the fuel reprocessing equipment at the Idaho Nuclear Technology and Engineering Center (INTEC) at the INL. The SBW contains high concentrations of nitric acid, and alkali and aluminum nitrates, along with many other inorganic compounds, including substantial levels of radionuclides. As part of the implementation of the THOR{sup R} process at INTEC, an engineering-scale technology demonstration (ESTD) was conducted using a specially designed pilot plant located at Hazen Research, Inc. in Golden Colorado. This ESTD confirmed the efficacy of the THOR{sup R} FBSR process to convert the SBW into a granular carbonate-based waste form suitable for disposal at the Waste Isolation Pilot Plant (WIPP). DOE authorized, as a risk reduction measure, the performance of an additional ESTD to demonstrate the production of an insoluble mineralized product, in the event that an alternate disposition path is required. The additional ESTD was conducted at the Hazen Research facility using the THOR{sup R} process and the same SBW simulant employed previously. An alkali aluminosilicate mineral product was produced that exhibited excellent leach resistance and chemical durability. The demonstration established general system operating parameters for a full-scale facility; provided process off-gas data that confirmed operation within regulatory limits; determined that the mineralized product exhibits superior leach resistance and durability, compared to Environmental Assessment (EA) and Low-activity Reference Material (LRM) glasses, as indicated by the Product Consistency Test (PCT); ascertained that Cs and Re (a surrogate for Tc) were non

  17. Microprobes aluminosilicate ceramic membranes

    DOEpatents

    Anderson, Marc A.; Sheng, Guangyao

    1993-01-01

    Methods have been developed to make mixed alumina-silicate and aluminosilicate particulate microporous ceramic membranes. One method involves the making of separate alumina and silica sols which are then mixed. Another method involves the creation of a combined sol with aluminosilicate particles. The resulting combined alumina and silica membranes have high surface area, a very small pore size, and a very good temperature stability.

  18. Aluminosilicate Precipitation Impact on Uranium

    SciTech Connect

    WILMARTH, WILLIAM

    2006-03-10

    Experiments have been conducted to examine the fate of uranium during the formation of sodium aluminosilicate (NAS) when wastes containing high aluminate concentrations are mixed with wastes of high silicate concentration. Testing was conducted at varying degrees of uranium saturation. Testing examined typical tank conditions, e.g., stagnant, slightly elevated temperature (50 C). The results showed that under sub-saturated conditions uranium is not removed from solution to any large extent in both simulant testing and actual tank waste testing. This aspect was not thoroughly understood prior to this work and was necessary to avoid criticality issues when actual tank wastes were aggregated. There are data supporting a small removal due to sorption of uranium on sites in the NAS. Above the solubility limit the data are clear that a reduction in uranium concentration occurs concomitant with the formation of aluminosilicate. This uranium precipitation is fairly rapid and ceases when uranium reaches its solubility limit. At the solubility limit, it appears that uranium is not affected, but further testing might be warranted.

  19. Functionalized Amorphous Aluminosilicates

    NASA Astrophysics Data System (ADS)

    Mesgar, Milad

    Alkali treated aluminosilicate (geopolymer) was functionalized by surfactant to increase the hydrophobicity for making Pickering emulsion for the first part of this work. In the first part of this study, alkali treated metakaolin was functionalized with cetyltrimethylammonium bromide ((C16H33)N(CH 3)3Br, CTAB). The electrostatic interaction between this quaternary ammonium and the surface of the aluminosilicate which has negative charge has taken place. The particles then were used to prepare Pickering emulsion. The resulting stable dispersions, obtained very fast at very simple conditions with low ratio of aluminosilicate to liquid phase. In the second part, the interaction between geopolymer and glycerol was studied to see the covalent grafting of the geopolymer for making geopolymer composite. The composite material would be the basis material to be used as support catalyst, thin coating reagent and flame retardant material and so on, Variety of techniques, Thermogravimetric (TGA), Particle-induced X-ray emission (PIXE), FTIR, Solid state NMR, Powder X-ray diffraction (PXRD), BET surface area, Elemental analysis (CHN), TEM, SEM and Optical microscopy were used to characterize the functionalized geopolymer.

  20. Effect of sodium and potassium ions on cesium absorption from nuclear power plant waste solutions on synthetic zeolites

    SciTech Connect

    Harjula, R.; Lehto, J.

    1986-01-01

    The separation of cesium from low-active waste solutions from a nuclear power plant by ion exchange using synthetic zeolites Zeolon 900 and Linde AW-500 was studied. The pH of the waste solutions was 6-13 and the concentrations of sodium and potassium ions were 8-2700 and 0.5-240 mmol/L, respectively. The distribution coefficient of cesium was determined as a function of pH and sodium and potassium ion concentration. Column breakthrough curves were contained and an empirical equation was derived to calculate the column performance at different sodium and potassium ion concentrations.

  1. The dissolution of synthetic Na-boltwoodite in sodium carbonate solutions

    NASA Astrophysics Data System (ADS)

    Ilton, Eugene S.; Liu, Chongxuan; Yantasee, Wassana; Wang, Zheming; Moore, Dean A.; Felmy, Andrew R.; Zachara, John M.

    2006-10-01

    Uranyl silicates such as uranophane and Na-boltwoodite appear to control the solubility of uranium in certain contaminated sediments at the US Department of Energy Hanford site [Liu, C., Zachara, J.M., Qafoku, O., McKinley, J.P., Heald, S.M., Wang, Z. 2004. Dissolution of uranyl microprecipitates in subsurface sediments at Hanford Site, USA. Geochim. Cosmochim. Acta68, 4519-4537.]. Consequently, the solubility of synthetic Na-boltwoodite, Na(UO 2)(SiO 3OH) · 1.5H 2O, was determined over a wide range of bicarbonate concentrations, from circumneutral to alkaline pH, that are representative of porewater and groundwater compositions at the Hanford site and calcareous environments generally. Experiments were open to air. Results show that Na-boltwoodite dissolution was nearly congruent and its solubility and dissolution kinetics increased with increasing bicarbonate concentration and pH. A consistent set of solubility constants were determined from circumneutral pH (0 added bicarbonate) to alkaline pH (50 mM added bicarbonate). Average logKspo=5.86±0.24 or 5.85 ± 0.0.26; using the Pitzer ion-interaction model or Davies equation, respectively. These values are close to the one determined by [Nguyen, S.N., Silva, R.J., Weed, H.C., Andrews, Jr., J.E., 1992. Standard Gibbs free energies of formation at the temperature 303.15 K of four uranyl silicates: soddyite, uranophane, sodium boltwoodite, and sodium weeksite. J. Chem. Thermodynamics24, 359-376.] under very different conditions (pH 4.5, Ar atmosphere).

  2. Synthetic and reactivity studies of hetero-tri-anionic sodium zincates.

    PubMed

    Francos, Javier; Kennedy, Alan R; O'Hara, Charles T

    2016-04-14

    The synthesis and characterisation of several sodium zincate complexes are reported. The all-alkyl monomeric sodium zincate, (PMEDTA)·Na(μ-CH2SiMe3)Zn(t)Bu22, is prepared by combining equimolar quantities of (t)Bu2Zn, (n)BuNa and PMDETA (N,N,N',N'',N''-pentamethyldiethylenetriamine)]. A similar approach was used to prepare and isolate the unusual dimeric zincate [(PMEDTA)·Na(μ-(n)Bu)Zn(t)Bu2]23. When an equimolar mixture of (n)BuNa, (t)Bu2Zn and TMP(H) (2,2,6,6-tetramethylpiperidine) is combined in hexane, the hetero-tri-leptic TMP(H)-solvated zincate (TMPH)Na(μ-TMP)(μ-(n)Bu)Zn(t)Bu 4 results. Complex 4 can also be prepared using a rational approach [i.e., utilising two molar equivalents of TMP(H)]. When TMEDA is reacted with an equimolar mixture of (n)BuNa, (t)Bu2Zn and TMP(H), the monomeric sodium zincate (TMEDA)Na(μ-TMP)(μ-(n)Bu)Zn(t)Bu 5 was obtained - this complex is structurally similar to the synthetically useful relation (TMEDA)·Na(μ-TMP)(μ-(t)Bu)Zn((t)Bu) 1. By changing the sodium reagent used in the synthesis of 5, it was possible to prepare (TMEDA)Na(μ-TMP)(μ-Me3SiCH2)Zn(t)Bu 6. By reacting 5 with cis-DMP(H) (cis-2,6-dimethylpiperidine), the zincate could thermodynamically function as an amide base, to give the transamination product (TMEDA)Na(μ-cis-DMP)(μ-(n)Bu)Zn(t)Bu 7, although no crystals could be grown. However, when HMDS(H) (1,1,1,3,3,3-hexamethyldisilazane) or PEA(H) [(+)-bis[(R)-1-phenylethyl]amine] is reacted with 5, crystalline (TMEDA)Na(μ-HMDS)(μ-(n)Bu)Zn(t)Bu 8 or (TMEDA)Na(μ-PEA)(μ-(n)Bu)Zn(t)Bu 9 is isolated respectively. With PNA(H) (N-phenylnaphthalen-1-amine) the reaction took a different course and resulted in the formation of the dimeric sodium amide complex [(TMEDA)Na(PNA)]210. When reacted with benzene, it appears that a TMEDA-free variant of 5 functions thermodynamically as an (n)Bu base to yield the previously reported (TMEDA)Na(μ-TMP)((t)Bu)Zn(μ-C6H4)Zn((t)Bu)(μ-TMP)Na(TMEDA) 11. Finally when reacted with

  3. Synthesis and characterization of aluminosilicate catalyst impregnated by nickel oxide

    NASA Astrophysics Data System (ADS)

    Maulida, Iffana Dani; Sriatun, Taslimah

    2015-09-01

    Aluminosilicate as a catalyst has been synthesized by pore-engineering using CetylTrimethylAmmonium-Bromide (CTAB) as templating agent. It can produce bigger aluminosilicate pore therefore it will be more suitable for bulky molecule. The aims of this research are to synthesize aluminosilicate supported by Nickel, using CTAB surfactant as templating agent for larger pore radius than natural zeolite and characterize the synthesis product, consist of total acid sites and surface area characteristic. This research has been done with following steps. First, making sodium silicate and sodium aluminate. Second, aluminosilicate was synthesized by direct methods, calcined at 550, 650 and 750°C variation temperature, characterized product by X-RD and FTIR spectrometer. Third, NiCl2 was impregnated to the aluminosilicate that has the best cristallinity and main TO4 functional groups product (550 sample). Variation of NiCl2:aluminosilicate (w/w) ratio were 25%:75%, 50%:50% and 75%:25%. Last but not least characterization of catalytic properties was performed. It comprised total acidity test (gravimetric method) and Surface Area Analyzer. The result shows that the product synthesized by direct method at 550oC calcination temperature has the best cristallinity and main functional groups of TO4. The highest total acid sites was 31.6 mmole/g (Imp-A sample). Surface Area Analyzer shows that Imp-B sample has the best pore distribution and highest total pore volume and specific surface area with value 32.424 cc/g and 46.8287 m2/g respectively. We can draw the conclusion that the most potential catalyst is Imp-A sample compared to Imp-B and Imp-C because it has the highest total acid sites. However the most effective catalyst used for product selectivity was Imp-B sample among all samples.

  4. Micellar electrokinetic chromatography with bis(2-ethylhexyl)sodium sulfosuccinate vesicles determination of synthetic food antioxidants.

    PubMed

    Delgado-Zamarreño, M M; Sánchez-Pérez, A; Ganzález Maza, I; Hernández-Méndez, J

    2000-02-25

    Capillary electrokinetic chromatography is suitable for the separation of mixtures of uncharged and charged solutes. In the present work the behavior of six synthetic food antioxidants--2[3]-tert.-butyl-4-hydroxyanisole, 2,6-di-tert.-butyl-p-cresol, tercbutylhydroquinone, 3,4,5-trihydroxybenzoic acid propyl ester, 3,4,5-trihydroxybenzoic acid octyl ester and 3,4,5-trihydroxybenzoic acid dodecyl ester--was studied in a capillary electrophoresis system using capillary electrokinetic chromatography with vesicles of the surfactant bis(2-ethylhexyl)sodium sulfosuccinate (AOT). Several studies aimed at calculating the critical aggregation concentration of the surfactant were conducted to check that under the conditions used the AOT was in a state of aggregation. Having checked the association shown by the surfactant, we then explored the greater or lesser capacity of the antioxidants to interact with this compound. We followed the evolution of the molecular absorption spectra of each of the antioxidants in the presence of the surfactant at different concentrations and the retention factors were calculated at different pH values. Additionally, in order to determine which species--anionic or neutral--was present at the pH of the buffer used (boric/borate), the pKa values in acetonitrile-water (20:80) were obtained. Resolution and quantification of the antioxidants demand optimization of the variables involved in the system, such as the percentage of acetonitrile, the concentration of AOT and boric/borate buffer, pH, voltage, etc. When this part of the study had been completed, calibrations were obtained for each of the antioxidants, obtaining good linear correlation coefficients in all cases. Finally, we propose a method that allows the resolution of the six most employed antioxidants in a capillary electrophoretic system in 15 min, using electrokinetic chromatography with AOT as the pseudostationary phase. PMID:10735321

  5. Uranium and Aluminosilicate Surface Precipitation Tests

    SciTech Connect

    Hu, M.Z.

    2002-11-27

    The 2H evaporator at the Savannah River Site has been used to treat an aluminum-rich waste stream from canyon operations and a silicon-rich waste stream from the Defense Waste Processing Facility. The formation of aluminosilicate scale in the evaporator has caused significant operational problems. Because uranium has been found to accumulate in the aluminosilicate solids, the scale deposition has introduced criticality concerns as well. The objective of the tests described in this report is to determine possible causes of the uranium incorporation in the evaporator scale materials. The scope of this task is to perform laboratory experiments with simulant solutions to determine if (1) uranium can be deposited on the surfaces of various sodium aluminosilicate (NAS) forms and (2) aluminosilicates can form on the surfaces of uranium-containing solids. Batch experiments with simulant solutions of three types were conducted: (1) contact of uranium solutions/sols with NAS coatings on stainless steel surfaces, (2) contact of uranium solutions with NAS particles, and (3) contact of precipitated uranium-containing particles with solutions containing aluminum and silicon. The results show that uranium can be incorporated in NAS solids through encapsulation in bulk agglomerated NAS particles of different phases (amorphous, zeolite A, sodalite, and cancrinite) as well as through heterogeneous deposition on the surfaces of NAS coatings (amorphous and cancrinite) grown on stainless steel. The results also indicate that NAS particles can grow on the surfaces of precipitated uranium solids. Particularly notable for evaporator operations is the finding that uranium solids can form on existing NAS scale, including cancrinite solids. If NAS scale is present, and uranium is in sufficient concentration in solution to precipitate, a portion of the uranium can be expected to become associated with the scale. The data obtained to date on uranium-NAS affinity are qualitative. A necessary

  6. Detailed Analysis of (−)-Palmyrolide A and Some Synthetic Derivatives as Voltage-Gated Sodium Channel Antagonists

    PubMed Central

    2015-01-01

    A small library of synthetic (−)-palmyrolide A diastereomers, analogues, and acyclic precursors have been examined with respect to their interaction with voltage-gated sodium channels (VGSCs). Toward this goal, the ability of (−)-palmyrolide A and analogues to antagonize veratridine-stimulated Na+ influx in primary cultures of mouse cerebrocortical neurons was assessed. We found that synthetic (−)-palmyrolide A and its enantiomer functioned as VGSC antagonists to block veratridine-induced sodium influx. A detailed NMR and computational analysis of four diastereomers revealed that none had the same combination of shape and electrostatic potential as exhibited by natural (−)-palmyrolide A. These data indicate that the relative configuration about the tert-butyl and methyl substituents appears to be a prerequisite for biological function. Additional testing revealed that the enamide double bond was not necessary for blocking veratridine-induced sodium influx, whereas the acyclic analogues and other macrolide diastereomers tested were inactive as inhibitors of VGSCs, suggesting that the intact macrolide was required. PMID:25343669

  7. [Comparison of the thermostability of natural (sulfoprolamine and sodium usnate) and synthetic (climbazole and piroctone olamine) antidandruff agents].

    PubMed

    Coiffard, C; Coiffard, L; de Roeck-Holtzhauer, Y

    1999-09-01

    We compared thermostability of various natural (sulfoprolamine and sodium usnate) or synthetic (climbazol and piroctone olamine) antidandruff agents in aqueous diluted solution at pH around 7. Thermodegradation of these solutions was studied by an isothermal method in thermostatically controlled ovens, at three temperatures (50, 70 and 90 degrees C). For each molecule, we determined at 20 degrees C t90% (time necessary to obtain a decrease of 10% of the initial concentration, value which shows the stability of the product). The present study shows that piroctone olamine is the most stable antidandruff agent among those studied. PMID:10520510

  8. Novel synthetic sulfoglycolipid IG20 facilitates exocytosis in chromaffin cells through the regulation of sodium channels.

    PubMed

    Crespo-Castrillo, Andrea; Punzón, Eva; de Pascual, Ricardo; Maroto, Marcos; Padín, Juan Fernando; García-Álvarez, Isabel; Nanclares, Carmen; Ruiz-Pascual, Lucía; Gandía, Luis; Fernández-Mayoralas, Alfonso; García, Antonio G

    2015-12-01

    In search of druggable synthetic lipids that function as potential modulators of synaptic transmission and plasticity, we synthesized sulfoglycolipid IG20, which stimulates neuritic outgrowth. Here, we have explored its effects on ion channels and exocytosis in bovine chromaffin cells. IG20 augmented the rate of basal catecholamine release. Such effect did not depend on Ca(2+) mobilization from intracellular stores; rather, IG20-elicited secretion entirely dependent on Ca(2+) entry through L-subtype voltage-activated Ca(2+) channels. Those channels were recruited by cell depolarization mediated by IG20 likely through its ability to enhance the recruitment of Na(+) channels at more hyperpolarizing potentials. Confocal imaging with fluorescent derivative IG20-NBD revealed its rapid incorporation and confinement into the plasmalemma, supporting the idea that IG20 effects are exerted through a plasmalemmal-delimited mechanism. Thus, synthetic IG20 seems to mimic several physiological effects of endogenous lipids such as regulation of ion channels, Ca(2+) signaling, and exocytosis. Therefore, sulfoglycolipid IG20 may become a pharmacological tool for investigating the role of the lipid environment on neuronal excitability, ion channels, neurotransmitter release, synaptic efficacy, and neuronal plasticity. It may also inspire the synthesis of druggable sulfoglycolipids aimed at increasing synaptic plasticity and efficacy in neurodegenerative diseases and traumatic brain-spinal cord injury. The novel synthetic sulfoglycolipid IG20 mimics several physiological effects of endogenous lipids such as regulation of ion channels, Ca(2+) signaling, and exocytosis. This profile may eventually drive enhanced synaptic plasticity and efficacy. PMID:26365051

  9. Structural Role of Alkali Cations in Calcium Aluminosilicate Glasses as Examined Using Oxygen-17 Solid-State Nuclear Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sukenaga, Sohei; Kanehashi, Koji; Shibata, Hiroyuki; Saito, Noritaka; Nakashima, Kunihiko

    2016-05-01

    The structural roles of alkali and calcium cations are important for understanding the physical and chemical properties of aluminosilicate melts and glasses. Recently, oxygen-17 nuclear magnetic resonance (17O NMR) studies of calcium-sodium aluminosilicate glasses showed that these structural roles are not randomly given, but rather each cation has its own preferential role. However, the relationship between cation type and role preference in calcium aluminosilicate glass is not completely understood. In the present study, the structural roles of lithium, sodium, and potassium cations in selected calcium aluminosilicate glasses are investigated using 17O solid-state NMR experiments. Data from these experiments clearly show that potassium cations have a notably stronger tendency to act as charge compensators within the network structure, compared to sodium and lithium cations. The result of 17O NMR experiment also showed that sodium and lithium cations in part act as network modifier alongside with calcium cations.

  10. Structural Role of Alkali Cations in Calcium Aluminosilicate Glasses as Examined Using Oxygen-17 Solid-State Nuclear Magnetic Resonance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sukenaga, Sohei; Kanehashi, Koji; Shibata, Hiroyuki; Saito, Noritaka; Nakashima, Kunihiko

    2016-08-01

    The structural roles of alkali and calcium cations are important for understanding the physical and chemical properties of aluminosilicate melts and glasses. Recently, oxygen-17 nuclear magnetic resonance (17O NMR) studies of calcium-sodium aluminosilicate glasses showed that these structural roles are not randomly given, but rather each cation has its own preferential role. However, the relationship between cation type and role preference in calcium aluminosilicate glass is not completely understood. In the present study, the structural roles of lithium, sodium, and potassium cations in selected calcium aluminosilicate glasses are investigated using 17O solid-state NMR experiments. Data from these experiments clearly show that potassium cations have a notably stronger tendency to act as charge compensators within the network structure, compared to sodium and lithium cations. The result of 17O NMR experiment also showed that sodium and lithium cations in part act as network modifier alongside with calcium cations.

  11. [Raman active vibrations of aluminosilicates].

    PubMed

    Pan, Feng; Yu, Xue-hui; Mo, Xuan-xue; You, Jing-lin; Wang, Chen; Chen, Hui; Jiang, Guo-chang

    2006-10-01

    Raman spectra of aluminosilicate minerals, namely kyanite, andalusite, and sillimanite and K2O-Al2O3-SiO2 glasses were recorded. Four alumino-silicon tetrahedral model clusters were calculated by self-consistent (SCF) molecular orbital ab-ini-tio calculation of the quantum chem (QC) method. The result shows a decrease tendency in Raman frequencies in the 800-1200 cm(-1) frequency region with increase in four-coordinated Al content, which is assigned to the Si--Onb symmetry stretching vibrations. The Raman spectra in the 700-800 cm(-1) frequency region is attributed to Al-Onb symmetry stretching vibrations. PMID:17205741

  12. The Dissolution of Synthetic Na-Boltwoodite in Sodium Carbonate Solutions

    SciTech Connect

    Ilton, Eugene S.; Liu, Chongxuan; Yantasee, Wassana; Wang, Zheming; Moore, Dean A.; Felmy, Andrew R.; Zachara, John M.

    2006-09-01

    Uranyl silicates such as uranophane and Na-boltwoodite appear to control the solubility of uranium in the contaminated sediments at the US Department of Energy Hanford site (Liu et al., 2004). Consequently, the solubility of synthetic Na-boltwoodite was determined over a wide range of bicarbonate concentrations, from circumneutral to alkaline pH, that are representative of porewater and groundwater compositions at the Hanford site. Results show that Na-boltwoodite dissolution was nearly congruent and its solubility increased with increasing bicarbonate concentration. Calculated solubility constants varied by nearly 2 log units from low bicarbonate (no added NaCO3) to 50 mmol/L bicarbonate. However, the solubility constants only vary by 0.5 log units from 0 added bicarbonate to 1.2 mmol/L bicarbonate, where logKsp = 5.39-5.92 and the average logKsp = 5.63. No systematic trend in logKsp was apparent over this range in bicarbonate concentrations. LogKsp values trended down with increasing bicarbonate concentration, where logKsp = 4.06 at 50 mmol/L bicarbonate. We conclude that the calculated solubility constants at high bicarbonate are compromised by an incomplete or inaccurate uranyl-carbonate speciation model.

  13. Synthetic Ciguatoxins Selectively Activate Nav1.8-derived Chimeric Sodium Channels Expressed in HEK293 Cells*

    PubMed Central

    Yamaoka, Kaoru; Inoue, Masayuki; Miyazaki, Keisuke; Hirama, Masahiro; Kondo, Chie; Kinoshita, Eiji; Miyoshi, Hiroshi; Seyama, Issei

    2009-01-01

    The synthetic ciguatoxin CTX3C has been shown to activate tetrodotoxin (TTX)-sensitive sodium channels (Nav1.2, Nav1.4, and Nav1.5) by accelerating activation kinetics and shifting the activation curve toward hyperpolarization (Yamaoka, K., Inoue, M., Miyahara, H., Miyazaki, K., and Hirama, M. (2004) Br. J. Pharmacol. 142, 879–889). In this study, we further explored the effects of CTX3C on the TTX-resistant sodium channel Nav1.8. TTX-resistant channels have been shown to be involved in transducing pain and related sensations (Akopian, A. N., Sivilotti, L., and Wood, J. N. (1996) Nature 379, 257–262). Thus, we hypothesized that ciguatoxin-induced activation of the Nav1.8 current would account for the neurological symptoms of ciguatera poisoning. We found that 0.1 μm CTX3C preferentially affected the activation process of the Nav1.8 channel compared with those of the Nav1.2 and Nav1.4 channels. Importantly, without stimulation, 0.1 μm CTX3C induced a large leakage current (IL). The conductance of the IL calculated relative to the maximum conductance (Gmax) was 10 times larger than that of Nav1.2 or Nav1.4. To determine the molecular domain of Nav1.8 responsible for conferring higher sensitivity to CTX3C, we made two chimeric constructs from Nav1.4 and Nav1.8. Chimeras containing the N-terminal half of Nav1.8 exhibited a large response similar to wild-type Nav1.8, indicating that the region conferring high sensitivity to ciguatoxin action is located in the D1 or D2 domains. PMID:19164297

  14. Structure and mechanical properties of aluminosilicate geopolymer composites with Portland cement and its constituent minerals

    SciTech Connect

    Tailby, Jonathan; MacKenzie, Kenneth J.D.

    2010-05-15

    The compressive strengths and structures of composites of aluminosilicate geopolymer with the synthetic cement minerals C{sub 3}S, beta-C{sub 2}S, C{sub 3}A and commercial OPC were investigated. All the composites showed lower strengths than the geopolymer and OPC paste alone. X-ray diffraction, {sup 29}Si and {sup 27}Al MAS NMR and SEM/EDS observations indicate that hydration of the cement minerals and OPC is hindered in the presence of geopolymer, even though sufficient water was present in the mix for hydration to occur. In the absence of SEM evidence for the formation of an impervious layer around the cement mineral grains, the poor strength development is suggested to be due to the retarded development of C-S-H because of the preferential removal from the system of available Si because geopolymer formation is more rapid than the hydration of the cement minerals. This possibility is supported by experiments in which the rate of geopolymer formation is retarded by the substitution of potassium for sodium, by the reduction of the alkali content of the geopolymer paste or by the addition of borate. In all these cases the strength of the OPC-geopolymer composite was increased, particularly by the combination of the borate additive with the potassium geopolymer, producing an OPC-geopolymer composite stronger than hydrated OPC paste alone.

  15. Synthesis and biological characterization of synthetic analogs of Huwentoxin-IV (Mu-theraphotoxin-Hh2a), a neuronal tetrodotoxin-sensitive sodium channel inhibitor.

    PubMed

    Deng, Meichun; Luo, Xuan; Jiang, Liping; Chen, Hanchun; Wang, Jun; He, Hailun; Liang, Songping

    2013-09-01

    Huwentoxin-IV (HWTX-IV, also named Mu-theraphotoxin-Hh2a) is a typical inhibitor cystine knot peptide isolated from the venom of Chinese tarantula Ornithoctonus huwena and is found to inhibit tetrodotoxin-sensitive (TTX-S) sodium channels from mammalian sensory neurons. This peptide binds to neurotoxin receptor site 4 located at the extracellular S3-S4 linker of domain II in neuronal sodium channels. However, the molecular surface of HWTX-IV interaction with sodium channels remains unknown. In this study, we synthesized HWTX-IV and three mutants (T28D, R29A and Q34D) and characterized their functions on TTX-S sodium channels from adult rat dorsal root ganglion (DRG) neurons. Analysis of liquid chromatography, mass spectrometry and circular dichroism spectrum indicated that all four synthetic peptides are properly folded. Synthetic HWTX-IV exhibited the same activity as native HWTX-IV, while three mutations reduced toxin binding affinities by 10-200 fold, indicating that the basic or vicinal polar residues Thr²⁸, Arg²⁹, and Gln³⁴ in C-terminus might play critical roles in the interaction of HWTX-IV with TTX-S sodium channels. PMID:23726857

  16. Dissolution and Separation of Aluminum and Aluminosilicates

    DOE PAGESBeta

    McFarlane, Joanna; Benker, Dennis; DePaoli, David W.; Felker, Leslie Kevin; Mattus, Catherine H.

    2015-12-19

    The selection of an aluminum alloy for target irradiation affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as amore » function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. Our data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.« less

  17. Dissolution and Separation of Aluminum and Aluminosilicates

    SciTech Connect

    McFarlane, Joanna; Benker, Dennis; DePaoli, David W.; Felker, Leslie Kevin; Mattus, Catherine H.

    2015-12-19

    The selection of an aluminum alloy for target irradiation affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. Our data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.

  18. 40 CFR 721.633 - Aluminosilicates, phospho-.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... reporting. (1) The chemical substance identified as Aluminosilicates, phospho- (PMN P-98-1275; CAS No... in § 721.125 (a), (b), (c), (d), (f), (g), (h), and (i) are applicable to manufacturers, importers... Section 721.633 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC...

  19. 40 CFR 721.633 - Aluminosilicates, phospho-.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... reporting. (1) The chemical substance identified as Aluminosilicates, phospho- (PMN P-98-1275; CAS No... in § 721.125 (a), (b), (c), (d), (f), (g), (h), and (i) are applicable to manufacturers, importers... Section 721.633 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC...

  20. Intrinsic differences in atomic ordering of calcium (alumino)silicate hydrates in conventional and alkali-activated cements

    SciTech Connect

    White, Claire E.; Daemen, Luke L.; Hartl, Monika; Page, Katharine

    2015-01-15

    The atomic structures of calcium silicate hydrate (C–S–H) and calcium (–sodium) aluminosilicate hydrate (C–(N)–A–S–H) gels, and their presence in conventional and blended cement systems, have been the topic of significant debate over recent decades. Previous investigations have revealed that synthetic C–S–H gel is nanocrystalline and due to the chemical similarities between ordinary Portland cement (OPC)-based systems and low-CO{sub 2} alkali-activated slags, researchers have inferred that the atomic ordering in alkali-activated slag is the same as in OPC–slag cements. Here, X-ray total scattering is used to determine the local bonding environment and nanostructure of C(–A)–S–H gels present in hydrated tricalcium silicate (C{sub 3}S), blended C{sub 3}S–slag and alkali-activated slag, revealing the large intrinsic differences in the extent of nanoscale ordering between C–S–H derived from C{sub 3}S and alkali-activated slag systems, which may have a significant influence on thermodynamic stability, and material properties at higher length scales, including long term durability of alkali-activated cements.

  1. Treatment of a synthetic solution of galvanization effluent via the conversion of sodium cyanide into an insoluble safe complex.

    PubMed

    Ismail, Ibrahim; Abdel-Monem, Nabil; Fateen, Seif-Eddeen; Abdelazeem, Waleed

    2009-07-30

    Wastewater discharged from metal-finishing processes usually contains cyanide, a hazardous substance that is used extensively in the surface finishing industry. In the present study, a synthetic solution resembling the contaminated wastewater was chemically treated using ferrous sulfate. This simple one-step process was applied successfully to remove cyanide from metal finishing wastewater. The experiments were carried out on a synthetic solution containing ions of cyanide and zinc. The effects of mixing velocity, ratio of ferrous ions to cyanide ions, ferrous ions concentration, initial cyanide concentration, pH of solution, temperature, mixing time and zinc ions concentration were studied. The results showed that the removal efficiency of cyanide increased as the mixing velocity increased, ferrous ion molar ratio to cyanide ions increased, temperature increased and time of mixing increased at an optimum of pH 8. The reduction of cyanide concentration reached the allowable limit for wastewater discharge according to the Egyptian Environmental Law decree 44/2000, which is 0.2mg/l. The formed complexes were analyzed and the stability of each complex was studied under different pH value solutions after 7 days of contact. A typical example of electroplating wastewater from a local company in the field of metal finishing, which contains 18 mg/lCN(-) and 12 mg/l Zn(2+), was treated according to the determined optimum conditions for the treatment process and the concentration of CN(-) was reduced to 0.095 mg/l after 15 min of agitation. PMID:19135781

  2. Anti wetting additives for aluminosilicate refractories in molten aluminum contact applications

    NASA Astrophysics Data System (ADS)

    Shukla, Devdutt Pramod

    Aluminosilicate based refractories are widely used in furnace installations for melting aluminum because they are inexpensive, readily available and generally exhibit the properties desired from a refractory material. However, they face severe corrosion and degradation issues due to the extremely reducing nature of molten aluminum alloys. Isothermal static cup testing is widely used as a tool to evaluate the performance of refractories against penetration by molten aluminum alloys. Various testing methods were reviewed and an upgraded static cup test was recommended. Commercially available aluminosilicate refractories were tested using this method and their results were studied in order to understand the corrosion process. Barium sulfate, which is widely used as an anti-wetting additive to improve refractory performance by limiting physical contact between molten metal and the refractory, has proved ineffective at temperatures above 1000°C. A literature review suggested that barium sulfate formed barium celsian at high temperatures and that the celsian was responsible for the non-wetting effect. Wetting angle measurements of molten AL 5083 on synthetic celsian discs revealed that barium celsian and strontium celsian were both not wetted by molten aluminum. Static cup tests were performed on aluminosilicate refractories containing barium carbonate and strontium carbonate. These additives led to the in-situ formation of celsian phases within the refractory matrix that led to improved corrosion resistance at 1300°C. Phase analysis revealed that celsian formation suppressed the formation of mullite within refractories, thereby reducing penetration.

  3. Effects of Sodium Butyrate and Its Synthetic Amide Derivative on Liver Inflammation and Glucose Tolerance in an Animal Model of Steatosis Induced by High Fat Diet

    PubMed Central

    Mattace Raso, Giuseppina; Simeoli, Raffaele; Russo, Roberto; Iacono, Anna; Santoro, Anna; Paciello, Orlando; Ferrante, Maria Carmela; Canani, Roberto Berni; Calignano, Antonio; Meli, Rosaria

    2013-01-01

    Background & Aims Nonalcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease. Insulin resistance (IR) appears to be critical in its pathogenesis. We evaluated the effects of sodium butyrate (butyrate) and its synthetic derivative N-(1-carbamoyl-2-phenyl-ethyl) butyramide (FBA) in a rat model of insulin resistance and steatosis induced by high-fat diet (HFD). Methods After weaning, young male Sprague-Dawley rats were divided into 4 groups receiving different diets for 6 weeks: 1. control group (standard diet); 2. HFD; 3. HFD plus butyrate (20 mg/kg/die) and 4. HFD plus FBA (42.5 mg/Kg/die, the equimolecular dose of butyrate). Liver tissues of the rats were analyzed by Western blot and real-time PCR. Insulin resistance, liver inflammation and Toll-like pattern modifications were determined. Results Evaluation of these two preparations of butyrate showed a reduction of liver steatosis and inflammation in HFD fed animals. The compounds showed a similar potency in the normalisation of several variables, such as transaminases, homeostasis model assessment for insulin resistance index, and glucose tolerance. Both treatments significantly reduced hepatic TNF-α expression and restored GLUTs and PPARs, either in liver or adipose tissue. Finally, FBA showed a higher potency in reducing pro-inflammatory parameters in the liver, via suppression of Toll-like receptors and NF-κB activation. Conclusions Our results demonstrated a protective effect of butyrate in limiting molecular events underlying the onset of IR and NAFLD, suggesting a potential clinical relevance for this substance. In particular, its derivative, FBA, could represent an alternative therapeutic option to sodium butyrate, sharing a comparable efficacy, but a better palatability and compliance. PMID:23861927

  4. Highly effective degradation of sodium dodecylbenzene sulphonate and synthetic greywater by Fenton-like reaction over zerovalent iron-based catalyst.

    PubMed

    Zhu, Shi-Ni; Wang, Chao; Yip, Alex C K; Tsang, Daniel C W

    2015-01-01

    There is an increasing interest to recycle greywater for meeting non-portable water demand. However, linear alkylbenzene sulphonates (a form of anionic surfactants) that are commonly found in greywater are less biodegradable at moderate to high concentrations. A fenton-like system is a relatively economic advanced oxidation process that can potentially be used for surfactant degradation in greywater treatment. This study investigated the feasibility of zerovalent iron (ZVI)-mediated Fenton's oxidation of sodium dodecylbenzene sulphonate (SDBS) using Fe0/H2O2 and Fe2+/Fe0/H2O2 systems under a range of operating conditions. For the Fe0/H2O2 binary system, the initial pH value and Fe0 dosage played important roles in final degradation efficiency. For the Fe2+/Fe0/H2O2 ternary systems, a small amount of Fe2+ (0.5-1.7 mM) contributed a synergistic effect to promote iron recycling and SDBS degradation. Approximately, 90% of SDBS mineralization efficiency was accomplished within 15 min at a pH range from 3.0 to 6.5, using 18 mM Fe0 and 15 mM H2O2. However, the removal kinetics was rate-limited by Fe2+ dissolution from the ZVI surfaces. The Fenton-like process of the Fe2+/Fe0/H2O2 ternary system also presents a promising treatment method for synthetic greywater, in which 90% TOC removal was achieved within the first 10 min; 78% COD and 91% BOD5 were achieved after 120 min of reaction. PMID:25424128

  5. Aluminosilicate nanoparticles for catalytic hydrocarbon cracking.

    PubMed

    Liu, Yu; Pinnavaia, Thomas J

    2003-03-01

    Aluminosilicate nanoparticles containing 9.0-20 nm mesopores were prepared through the use of protozeolitic nanoclusters as the inorganic precursor and starch as a porogen. The calcined, porogen-free composition containing 2 mol % aluminum exhibited the porosity, hydrothermal stability, and acidity needed for the cracking of very large hydrocarbons. In fact, the hydrothermal stability of the nanoparticles to pure steam at 800 degrees C, along with the cumene cracking activity, surpassed the analogous performance properties of ultrastable Y zeolite, the main catalyst component of commercial cracking catalysts. The remarkable hydrothermal stability and catalytic reactivity of the new nanoparticles are attributable to a unique combination of two factors, the presence of protozeolitic nanoclusters in the pore walls and the unprecedented pore wall thickness (7-15 nm). In addition, the excellent catalytic longevity of the nanoparticles is most likely facilitated by the small domain size of the nanoparticles that greatly improves access to the acid sites on the pore walls and minimizes the diffusion length of coke precursors out of the pores. PMID:12603109

  6. Catalytic pyrolysis using UZM-44 aluminosilicate zeolite

    DOEpatents

    Nicholas, Christopher P; Boldingh, Edwin P

    2014-04-29

    A new family of aluminosilicate zeolites designated UZM-44 has been synthesized. These zeolites are represented by the empirical formula. Na.sub.nM.sub.m.sup.k+T.sub.tAl.sub.1-xE.sub.xSi.sub.yO.sub.z where "n" is the mole ratio of Na to (Al+E), M represents a metal or metals from zinc, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, "m" is the mole ratio of M to (Al+E), "k" is the average charge of the metal or metals M, T is the organic structure directing agent or agents, and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-44 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  7. Catalytic pyrolysis using UZM-44 aluminosilicate zeolite

    SciTech Connect

    Nicholas, Christopher P; Boldingh, Edwin P

    2013-12-17

    A new family of aluminosilicate zeolites designated UZM-44 has been synthesized. These zeolites are represented by the empirical formula Na.sub.nM.sub.m.sup.k+T.sub.tAl.sub.1-xE.sub.xSi.sub.yO.sub.z where "n" is the mole ratio of Na to (Al+E), M represents a metal or metals from zinc, Group 1, Group 2, Group 3 and or the lanthanide series of the periodic table, "m" is the mole ratio of M to (Al+E), "k" is the average charge of the metal or metals M, T is the organic structure directing agent or agents, and E is a framework element such as gallium. The process involves contacting a carbonaceous biomass feedstock with UZM-44 at pyrolysis conditions to produce pyrolysis gases comprising hydrocarbons. The catalyst catalyzes a deoxygenation reaction converting oxygenated hydrocarbons into hydrocarbons and removing the oxygen as carbon oxides and water. A portion of the pyrolysis gases is condensed to produce low oxygen biomass-derived pyrolysis oil.

  8. Cellular morphology of organic-inorganic hybrid foams based on alkali alumino-silicate matrix

    SciTech Connect

    Verdolotti, Letizia; Capasso, Ilaria; Lavorgna, Marino; Liguori, Barbara; Caputo, Domenico; Iannace, Salvatore

    2014-05-15

    Organic-inorganic hybrid foams based on an alkali alumino-silicate matrix were prepared by using different foaming methods. Initially, the synthesis of an inorganic matrix by using aluminosilicate particles, activated through a sodium silicate solution, was performed at room temperature. Subsequently the viscous paste was foamed by using three different methods. In the first method, gaseous hydrogen produced by the oxidization of Si powder in an alkaline media, was used as blowing agent to generate gas bubbles in the paste. In the second method, the porous structure was generated by mixing the paste with a “meringue” type of foam previously prepared by whipping, under vigorous stirring, a water solution containing vegetal proteins as surfactants. In the third method, a combination of these two methods was employed. The foamed systems were consolidated for 24 hours at 40°C and then characterized by FTIR, X-Ray diffraction, scanning electron microscopy (SEM) and compression tests. Low density foams (∼500 Kg/m{sup 3}) with good cellular structure and mechanical properties were obtained by combining the “meringue” approach with the use of the chemical blowing agent based on Si.

  9. 29Si NMR study of structural ordering in aluminosilicate geopolymer gels.

    PubMed

    Duxson, Peter; Provis, John L; Lukey, Grant C; Separovic, Frances; van Deventer, Jannie S J

    2005-03-29

    A systematic series of aluminosilicate geopolymer gels was synthesized and then analyzed using 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) in combination with Gaussian peak deconvolution to characterize the short-range ordering in terms of T-O-T bonds (where T is Al or Si). The effect of nominal Na2O/(Na2O + K2O) and Si/Al ratios on short-range network ordering was quantified by deconvolution of the 29Si MAS NMR spectra into individual Gaussian peaks representing different Q4(mAl) silicon centers. The deconvolution procedure developed in this work is applicable to other aluminosilicate gel systems. The short-range ordering observed here indicates that Loewenstein's Rule of perfect aluminum avoidance may not apply strictly to geopolymeric gels, although further analyses are required to quantify the degree of aluminum avoidance. Potassium geopolymers appeared to exhibit a more random Si/Al distribution compared to that of mixed-alkali and sodium systems. This work provides a quantitative account of the silicon and aluminum ordering in geopolymers, which is essential for extending our understanding of the mechanical strength, chemical and thermal stability, and fundamental structure of these systems. PMID:15779981

  10. Effect of water on the heat capacity of polymerized aluminosilicate glasses and melts

    NASA Astrophysics Data System (ADS)

    Bouhifd, M. Ali; Whittington, Alan; Roux, Jacques; Richet, Pascal

    2006-02-01

    The effect of water on heat capacity has been determined for four series of hydrated synthetic aluminosilicate glasses and supercooled liquids close to albite, phonolite, trachyte, and leucogranite compositions. Heat capacities were measured at atmospheric pressure by differential scanning calorimetry for water contents between 0 and 4.9 wt % from 300 K to about 100 K above the glass transition temperature ( Tg). The partial molar heat capacity of water in polymerized aluminosilicate glasses, which can be considered as independent of composition, is =-122.319+341.631×10-3T+63.4426×105/T2 (J/mol K). In liquids containing at least 1 wt % H 2O, the partial molar heat capacity of water is about 85 J/mol K. From speciation data, the effects of water as hydroxyl groups and as molecular water have tentatively been estimated, with partial molar heat capacities of 153 ± 18 and 41 ± 14 J/mol K, respectively. In all cases, water strongly increases the configurational heat capacity at Tg and exerts a marked depressing effect on Tg, in close agreement with the results of viscosity experiments on the same series of glasses. Consistent with the Adam and Gibbs theory of relaxation processes, the departure of the viscosity of hydrous melts from Arrhenian variations correlates with the magnitude of configurational heat capacities.

  11. The effects of hot corrosion on the microstructure of a silicon carbide fiber-reinforced calcium aluminosilicate

    SciTech Connect

    Kumar, A.; Oppici, M.A.; Fox, A.G.; Wang, S.W.

    1995-12-01

    This work, funded by the navy exploratory development program, aircraft materials section, studied the effects of sodium sulfate hot corrosion on the microstructure of a SiC fiber-reinforced calcium aluminosilicate by x-ray diffraction and scanning electron microscopy. The corrosion of the composite by liquid sodium sulfate at 900{degrees}C for 50 hours gave an approximately 50-75 {mu}m thick reaction zone. Several phases, including wollastonite, nepheline and albite were identified within this reaction zone. The mechanisms by which these phases are developed are explained in terms of the kinetics of the dissociation of the sodium sulfate and its reaction with both the oxidized silicon carbide fibers and the anorthite matrix.

  12. Aluminosilicate melts and glasses at 1 to 3 GPa: temperature and pressure effects on recovered structural and density changes

    NASA Astrophysics Data System (ADS)

    Bista, S.; Stebbins, J. F.; Hankins, B.; Sisson, T. W.

    2013-12-01

    The effects of pressure on aluminosilicate melt and glass structure have been studied by both in-situ methods and by quenching and recovering glasses from high pressure and temperature. Significant increases in the coordination number of Al are now well known from the pressure range of 6-10 GPa. New results show that even at shallower mantle pressures of 1-3 GPa, typical aluminosilicate melts have significant concentrations of aluminum cations with coordination numbers greater than 4, with up to 10's of percents of AlO5 and AlO6. Here, we compare the densities and Al coordinations of glass samples recovered from piston-cylinder experiments carried out at 1 to 3 GPa and different temperatures. Samples of two different compositions (Ca3Al2Si6O18 and Na2Si3O7 with 0.5% Al2O3) were compressed and held at temperatures ranging from near to their ambient glass transitions (Tg) up to temperatures above the liquidus. Our 2 GPa sodium aluminosilicate and calcium aluminosilicate glasses quenched from near to Tg show about 5 and 6 percent recovered densification, respectively. In both compositions, samples that were quenched from above the melting point showed substantially lower recovered density and lower Al coordination number compared to the samples that were held near to Tg. For example, sodium aluminosilicate glass quenched from 510°C (near to Tg) had 70% more AlO5 than samples from 1200°C. Based on the measurement of actual cooling rates, fictive temperature differences for the glasses from these two extreme temperatures are not large enough to account for this apparent loss in density and Al-coordination during quench. The most likely cause for these differences is therefore probably the pressure drop during cooling from temperatures above liquidus, as the pressure medium does not respond quickly enough to the thermal contraction of the liquid and furnace parts to remain isobaric. Results from previous high T and P quenching studies thus give only minimum estimates

  13. Nanoscale encapsulation: the structure of cations in hydrophobic microporous aluminosilicates

    SciTech Connect

    Wasserman, S.R.; Yuchs, S.E.; Giaquinta, D.; Soderholm, L.; Song, Kang

    1996-10-01

    Hydrophobic microporous aluminosilicates, created by organic surface modification of inherently hydrophilic materials such as zeolites and clays, are currently being investigated as storage media for hazardous cations. Use of organic monolayers to modify the surface of an aluminosilicate after introducing an ion into the zeolite/clay reduces the interaction of water with the material. Resulting systems are about 20 times more resistant to leaching of stored ion. XAS spectra from the encapsulated ion demonstrate that byproducts from the organic modifier can complex with the stored cation. This complexation can result in a decreased affinity of the cation for the aluminosilicate matrix. Changing the organic modifier eliminates this problem. XAS spectra also indicate that the reactivity and speciation of the encapsulated ion may change upon application of the hydrophobic layer.

  14. Mesostructured silica and aluminosilicate carriers for oxytetracycline delivery systems.

    PubMed

    Berger, D; Nastase, S; Mitran, R A; Petrescu, M; Vasile, E; Matei, C; Negreanu-Pirjol, T

    2016-08-30

    Oxytetracycline delivery systems containing various MCM-type silica and aluminosilicate with different antibiotic content were developed in order to establish the influence of the support structural and textural properties and aluminum content on the drug release profile. The antibiotic molecules were loaded into the support mesochannels by incipient wetness impregnation method using a drug concentrated aqueous solution. The carriers and drug-loaded materials were investigated by small- and wide-angle XRD, FTIR spectroscopy, TEM and N2 adsorption-desorption isotherms. Faster release kinetics of oxytetracycline from uncalcined silica and aluminosilicate supports was observed, whereas higher drug content led to lower delivery rate. The presence of aluminum into the silica network also slowed down the release rate. The antimicrobial assays performed on Staphylococcus aureus clinical isolates showed that the oxytetracycline-loaded materials containing MCM-41-type mesoporous silica or aluminosilicate carriers inhibited the bacterial development. PMID:26861688

  15. Recycling of aluminosilicate waste: Impact onto geopolymer formation

    NASA Astrophysics Data System (ADS)

    Essaidi, N.; Gharzouni, A.; Vidal, L.; Gouny, F.; Joussein, E.; Rossignol, S.

    2015-07-01

    Geopolymers are innovative ecomaterials resulting from the activation of an aluminosilicate source by an alkaline solution. Their properties depend on the used raw materials. This paper focuses on the possibility to obtain geopolymer materials with aluminosilicate laboratory waste. The effect of these additions on the geopolymer properties was studied by FTIR spectroscopy and mechanical test. It was evidenced a slowdown of the polycondensation reaction as well as the compressive strength due to the addition of laboratory waste which decreases the Si/K ratio of mixture.

  16. Luminescent properties of bismuth centres in aluminosilicate optical fibres

    SciTech Connect

    Bulatov, Lenar I; Mashinskii, Valerii M; Dvoirin, Vladislav V; Dianov, Evgenii M; Kustov, Evgenii F

    2010-02-28

    The shape and spectral position of the luminescence bands of bismuth-doped aluminosilicate glass fibres are shown to depend on excitation power and wavelength. This indicates that the red and IR luminescence bands are composed of several components. The absorption and radiative transitions involved are identified, and a diagram of energy levels and transitions is obtained for four modifications of a bismuth centre in different environments in the aluminosilicate glass network. The effect of local environment on the optical properties of the bismuth centres is examined. (optical fibres and waveguides)

  17. Topographical localization of the C-terminal region of the voltage-dependent sodium channel from Electrophorus electricus using antibodies raised against a synthetic peptide

    SciTech Connect

    Gordon, R.D.; Fieles, W.E.; Schotland, D.L.; Hogue-Angeletti, R.; Barchi, R.L.

    1987-01-01

    A peptide corresponding to amino acid residues 1783-1794 near the C terminus of the electric eel sodium channel primary sequence of the eel (Electrophorus electricus) sodium channel has been synthesized and used to raise an antiserum in rabbits. This antiserum specifically recognized the peptide in a solid-phase radioimmunoassay. Specificity of the antiserum for the native channel protein was shown by its specific binding to a 280-kDa protein in immunoblots of eel electroplax membrane proteins. The antiserum also specifically labeled the innervated membrane of the eel electroplax in immunofluorescent studies. The membrane topology of the peptide recognized by this antiserum was proved in binding studies using oriented electroplax membrane vesicles. These vesicles were 98% right-side-out as determined by (/sup 3/H)saxitoxin binding. Binding of the antipeptide antiserum to this fraction was measured before and after permeabilization with 0.01% saponin. Specific binding to intact vesicles was low, but this binding increased 10-fold after permeabilization, implying a cytoplasmic orientation for the peptide. Confirmation for this orientation was then sought by localizing the antibody bound to intact electroplax cells with immunogold electron microscopy. The data imply that the region of the sodium channel primary sequence near the C terminus that is recognized by the anitserum is localized on the cytoplasmic side of the membrane; this localization provides some further constraints on models of sodium channel tertiary structure.

  18. Amorphous and nanostructured silica and aluminosilicate spray-dried microspheres

    NASA Astrophysics Data System (ADS)

    Todea, M.; Turcu, R. V. F.; Frentiu, B.; Tamasan, M.; Mocuta, H.; Ponta, O.; Simon, S.

    2011-08-01

    Amorphous silica and aluminosilicate microspheres with diameters in the 0.1-20 μm range were produced by spray drying method. SEM, TEM and AFM images showed the spherical shape of the obtained particles. Based on thermal analysis data, several heat treatments have been applied on the as-prepared samples in order to check the amorphous state stability of the microspheres and to develop nanosized crystalline phases. As-prepared microspheres remain amorphous up to 1400 °C. By calcination at 1400 °C, cristobalite type nanocrystals are developed on silica sample, while in aluminosilicate sample first are developed mullite type nanocrystals and only after prolonged treatment are developed also cristobalite type nanocrystals. 29Si and 27Al MAS NMR results show that the local order around aluminum and silicon atoms strongly depend on the thermal history of the microspheres.

  19. Channel waveguides in glass via silver-sodium field-assisted ion exchange

    NASA Technical Reports Server (NTRS)

    Forrest, K.; Pagano, S. J.; Viehmann, W.

    1986-01-01

    Multimode channel waveguides have been formed in sodium aluminosilicate glass by field-assisted diffusion of Ag(+) ions from vacuum-evaporated Ag films. The two-dimensional refractive index profiles of the waveguides were controlled by varying the diffusion time, the diffusion temperature, and the electric field strength. Estimates of the diffusion rate through a strip aperture were obtained, assuming the electric field was strong 120-240 V/mm. The maximum change in refractive index in the sodium aluminosilicate glasses was estimated near 65 percent of the change in soda-lime silicate glass. The physical properties of the glasses are given in a table.

  20. Hard x-ray nanotomography of amorphous aluminosilicate cements.

    SciTech Connect

    Provis, J. L.; Rose, V.; Winarski, R. P.; van Deventer, J. S. J.

    2011-08-01

    Nanotomographic reconstruction of a sample of low-CO{sub 2} 'geopolymer' cement provides the first three-dimensional view of the pore structure of the aluminosilicate geopolymer gel, as well as evidence for direct binding of geopolymer gel onto unreacted fly ash precursor particles. This is central to understanding and optimizing the durability of concretes made using this new class of binder, and demonstrates the value of nanotomography in providing a three-dimensional view of nanoporous inorganic materials.

  1. Barium aluminosilicate reinforced in situ with silicon nitride

    SciTech Connect

    Richardson, K.K.; Freitag, D.W.; Hunn, D.L.

    1995-10-01

    Advanced ceramic composite materials that exhibit high strength and toughness with good thermal shock resistance are needed for emerging high-temperature engineering applications. A recently developed in situ reinforced barium aluminosilicate glass-ceramic shows promise of meeting many of the requirements for these types of applications with the added benefit of low-cost fabrication through densification by pressureless sintering. The material is toughened through in situ growth of rodlike {beta}-Si{sub 3}N{sub 4} grains resulting from the {alpha}-{beta} silicon nitride phase transformation. Microstructural development and material properties for temperatures up to 1,400 C are discussed. When compared to monolithic barium aluminosilicate, barium aluminosilicate reinforced with 70% by volume of Si{sub 3}N{sub 4} shows a significant increase in flexural strength (from 80 to 565 MPa) and fracture toughness (from 1.8 to 5.74 MPa {center_dot} m{sup 1/2}) with a high resistance to thermal shock.

  2. Alteration of biophysical activity of pulmonary surfactant by aluminosilicate nanoparticles.

    PubMed

    Kondej, Dorota; Sosnowski, Tomasz R

    2013-02-01

    The influence of five different types of aluminosilicate nanoparticles (NPs) on the dynamic surface activity of model pulmonary surfactant (PS) (Survanta) was studied experimentally using oscillating bubble tensiometry. Bentonite, halloysite and montmorillonite (MM) NPs, which are used as fillers of polymer composites, were characterized regarding the size distribution, morphology and surface area. Particle doses applied in the studies were estimated based on the inhalation rate and duration, taking into account the expected aerosol concentration and deposition efficiency after penetration of NPs into the alveolar region. The results indicate that aluminosilicate NPs at concentrations in the pulmonary liquid above 0.1 mg cm(-3) are capable of promoting alterations of the original dynamic biophysical activity of the PS. This effect is indicated by deviation of the minimum surface tension, stability index and the size of surface tension hysteresis. Such response is dependent on the type of NPs present in the system and is stronger when particle concentration increases. It is suggested that interactions between NPs and the PS must be related to the surfactant adsorption on the suspended particles, while in the case of surface-modified clay NPs the additional washout of surface-active components may be expected. It is speculated that observed changes in surface properties of the surfactant may be associated with undesired health effects following extensive inhalation of aluminosilicate NPs in the workplace. PMID:23363039

  3. Thermal stability of synthetic thyroid hormone l-thyroxine and l-thyroxine sodium salt hydrate both pure and in pharmaceutical formulations.

    PubMed

    Ledeţi, Ionuţ; Ledeţi, Adriana; Vlase, Gabriela; Vlase, Titus; Matusz, Petru; Bercean, Vasile; Şuta, Lenuţa-Maria; Piciu, Doina

    2016-06-01

    In this paper, the thermal stability of pure l-thyroxine (THY) and l-thyroxine sodium salt hydrate (THYSS) vs. two pharmaceutical solid formulations commercialized on both Romanian and European market (with a content of 100μg, respectively 200μg THYSS per tablet) were investigated. In order to determine whether the presence of excipients affects the thermal stability of the active pharmaceutical ingredient (API), the preliminary study of thermal stability in air atmosphere was completed with an in-depth solid-state kinetic study. By kinetic analysis, the non-isothermal degradation of the selected active pharmaceutical ingredients vs. the solid formulation with strength of 200μg THYSS per tablet was investigated. Isoconversional methods (Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa and Friedman) were employed for the estimation of activation energies values, at five different heating rates, β=5, 7, 10, 12 and 15°Cmin(-1). Also, a fourth method was applied in the processing of data, namely NPK, allowing an objective separation in the physical and chemical processes that contribute to the thermal degradation of the selected compounds. A discussion of thermal stability from the kinetic point of view is also presented. PMID:26999320

  4. Analysis of paramagnetic centers for threevalent iron in aluminosilicates

    NASA Astrophysics Data System (ADS)

    Apushkinskaya, D.; Apushkinskiy, E.; Popov, B.; Romanov, V. N.; Saveliev, V.; Sobolevskiy, V.

    2015-09-01

    We present the results of investigation of the defects in fluorine aluminosilicates from the Volyn-field Al2 [SiO4][F,OH]2 by the Electron Paramagnetic Resonance (EPR) method. The studies were carried out on the spectrometer Bruker ER 220D. Three types of EPR spectra of single centers were obtained. Their angular dependence was also investigated. The obtained EPR spectra correspond to the paramagnetic ion Fe3+ in the high-spin state S = 5/2. Three types of paramagnetic centers were found: one with cubic-symmetry and two with orthorhombic- symmetries.

  5. Cesium adsorption on composite ferrocyanide-aluminosilicate adsorbents

    SciTech Connect

    Panasyugin, A.S.; Rat`ko, A.I.; Trofimenko, N.E.

    1995-11-01

    The formation of composite ferrocyanide adsorbents prepared on the basis of clinoptilolite is studied by potentiometric titration, X-ray diffraction analysis, and IR spectroscopy, and the nature of ion-exchanging complex is established. Exchange capacity, selectivity, and hydrolytic stability of the sorbents are characterized. Distribution coefficients with modified samples can be as large as 10000 for {sup 137}Cs; however, with increase of the background salt concentration above 0.17 g l{sup -1}, competing ions have noticeable effect on the adsorption properties of the aluminosilicates.

  6. Characterisation of frequency doubling in Eu(2+) doped aluminosilicate fibres

    NASA Technical Reports Server (NTRS)

    Driscoll, T. J.; Lawandy, N. M.; Killian, A.; Rienhart, L.; Morse, T. F.

    1991-01-01

    The results of a series of experiments on efficient second-harmonic generation in a fiber with a Eu(2+)-doped aluminosilicate core are reported. The fiber was prepared by the seeding method with CW mode-locked radiation at 1.06 micron and produced ultrastable peak conversion efficiencies of 0.001 during mode-locked readout. Experiments were performed to determine the IR preparation intensity dependence, the stability of the output, and the type of erasure mechanisms which occur. The results are compared with those of germanosilicate fibers and some similarities and differences are discussed.

  7. New nanocomposites based on layered aluminosilicate and guanidine containing polyelectrolytes

    SciTech Connect

    Khashirov, Azamat A.; Zhansitov, Azamat A.; Khashirova, Svetlana Yu.; Zaikov, Genadiy E.

    2014-05-15

    The new functional nanomaterials based on layered aluminosilicate and guanidine containing polyelectrolytes combining high bactericidal activity with an increased ability to bind to heavy metals and organic pollutants were received. To prove the chemical structure of the model compounds (zwitterionic delocalized resonance structures AG/MAG and PAG/PMAG), as well as the presence of such structures in nanocomposites received on their basis and the MMT, IR, {sup 1}H NMR spectroscopy, X-ray diffraction studies and nanoindentation/sclerometry followed by scanning the surface in the area of the indentation were used.

  8. The kinetics of desilication of synthetic spent Bayer liquor seeded with cancrinite and cancrinite/sodalite mixed-phase crystals

    NASA Astrophysics Data System (ADS)

    Barnes, Mark C.; Addai-Mensah, Jonas; Gerson, Andrea R.

    1999-04-01

    Isothermal, batch desilication kinetics of synthetic, sodium aluminate solution (spent Bayer liquor) via cancrinite and cancrinite/sodalite mixed-phase crystal growth, have been studied under conditions at which sodium aluminosilicate scale forms at the surfaces of steel heat exchangers of alumina plant. Seeding with the pure cancrinite and mixed-phase crystals results in the suppression of scale formation and a faster rate of liquor desilication in comparison with its sodalite dimorph. Cancrinite seed crystals prepared from NO -3-rich solutions exhibited crystal growth mechanism and kinetic behaviour different from dimorphic mixed-phase crystals prepared from CO 2-3-rich solutions, when both were used to desilicate CO 2-3-rich spent Bayer liquor. The rate of desilication due to crystal growth on CO 2-3-cancrinite/sodalite mixed phase crystals followed a second-order dependence on the relative supersaturation of SiO 2. An activation energy of 52 kJ mol -1 was estimated for the crystal growth process. For desilication kinetics involving NO -3-cancrinite seed crystal growth, a third-order dependence on relative supersaturation of SiO 2 and an activation energy of 63 kJ mol -1 were obtained.

  9. Microstructural and phase evolution in metakaolin geopolymers with different activators and added aluminosilicate fillers

    NASA Astrophysics Data System (ADS)

    Sarkar, Madhuchhanda; Dana, Kausik; Das, Sukhen

    2015-10-01

    This work aims to investigate the microstructural and phase evolution of alkali activated metakaolin products with different activators and added aluminosilicate filler phases. The added filler phases have different reactivity to the alkali activated metakaolin system. Microstructural evolution in the alkali activated products has been investigated by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron Microscope (FESEM). Variation in strength development in alkali activated metakaolin products was followed by compressive strength measurement test. Microstructural study shows that in case of metakaolin with NaOH activator crystalline sodalite formed in all the product samples irrespective of the added filler phases. The microstructure of these NaOH activated products investigated by FESEM showed crystalline and inhomogeneous morphology. Mixed activator containing both NaOH and sodium silicate in a fixed mass ratio formed predominantly amorphous phase. Microstructure of these samples showed more homogeneity than that of NaOH activated metakaolin products. The study further shows that addition of α-Al2O3 powder, non reactive phase to the alkali activated metakaolin system when used in larger amount increased crystalline phase in the matrix. α-Al2O3 powder addition increased the compressive strength of the product samples for both the activator compositions. Added phase of colloidal silica, reactive to the alkali activated metakaolin system when used in larger amount was found to increase amorphous nature of the matrix. Addition of colloidal silica influenced the compressive strength property differently with different activator compositions.

  10. Mesoporous aluminosilicates assembled from dissolved LTA zeolite and triblock copolymer in the presence of tetramethylammonium hydroxide.

    PubMed

    Tanaka, Shunsuke; Okada, Hiroaki; Nakatani, Norihito; Maruo, Takanori; Nishiyama, Norikazu; Miyake, Yoshikazu

    2009-05-15

    Zeolite Na-A crystals dissolved in a HCl solution were used as a single-source of silicon and aluminum for the synthesis of mesoporous aluminosilicates via a template-assisted method with an organic base tetramethylammonium hydroxide (TMAOH). Amphiphilic triblock copolymer Pluronic F127 (EO(106)PO(70)EO(106)) was used as template. Increasing the amount of TMAOH in the synthetic solution resulted in an increase in the aluminum content of the products. On the other hand, mesostructural periodicity was deteriorated with higher content of aluminum incorporated into the mesoporous framework. The samples with low Si/Al ratios less than 5 have wormhole-like pore structure, while the samples with Si/Al ratios more than 7 possess highly ordered mesoporous structure, a body-centered Im3m symmetry, with single crystal like morphology. The samples with Si/Al ratio of 7, which prepared at TMAOH molar concentration of 25 mM in the templating solution, possess BET surface area of 470 m(2)/g, pore size of 6.4 nm, and pore volume of 0.56 cm(3)/g. Aluminum atoms have successfully been incorporated in a tetra-coordinated position and remained stable even after calcination at 600 degrees C. PMID:19223041

  11. Effective Sequestration of Clostridium difficile Protein Toxins by Calcium Aluminosilicate

    PubMed Central

    Pokusaeva, Karina; Carpenter, Robert

    2015-01-01

    Clostridium difficile is a leading cause of antibiotic-associated diarrhea and the etiologic agent responsible for C. difficile infection. Toxin A (TcdA) and toxin B (TcdB) are nearly indispensable virulence factors for Clostridium difficile pathogenesis. Given the toxin-centric mechanism by which C. difficile pathogenesis occurs, the selective sequestration with neutralization of TcdA and TcdB by nonantibiotic agents represents a novel mode of action to prevent or treat C. difficile-associated disease. In this preclinical study, we used quantitative enzyme immunoassays to determine the extent by which a novel drug, calcium aluminosilicate uniform particle size nonswelling M-1 (CAS UPSN M-1), is capable of sequestering TcdA and TcdB in vitro. The following major findings were derived from the present study. First, we show that CAS UPSN M-1 efficiently sequestered both TcdA and TcdB to undetectable levels. Second, we show that CAS UPSN M-1's affinity for TcdA is greater than its affinity for TcdB. Last, we show that CAS UPSN M-1 exhibited limited binding affinity for nontarget proteins. Taken together, these results suggest that ingestion of calcium aluminosilicate might protect gastrointestinal tissues from antibiotic- or chemotherapy-induced C. difficile infection by neutralizing the cytotoxic and proinflammatory effects of luminal TcdA and TcdB. PMID:26149988

  12. In situ Brillouin study of sodium alumino silicate glasses under pressure

    NASA Astrophysics Data System (ADS)

    Sonneville, C.; De Ligny, D.; Mermet, A.; Champagnon, B.; Martinet, C.; Henderson, G. H.; Deschamps, T.; Margueritat, J.; Barthel, E.

    2013-08-01

    The in situ elastic and plastic behaviors of sodium aluminosilicate glasses with different degrees of depolymerization were analyzed using Brillouin spectroscopy. The observed elastic anomaly progressively vanished with depolymerization. The densification process appears to be different from that observed in pure silica glass. In the plastic regime of densified glasses hysteresis loops were observed and related to modification of the local silicon environment facilitated by the addition of sodium.

  13. Selective laser densification of lithium aluminosilicate glass ceramic tapes

    NASA Astrophysics Data System (ADS)

    Zocca, Andrea; Colombo, Paolo; Günster, Jens; Mühler, Thomas; Heinrich, Jürgen G.

    2013-01-01

    Tapes, cast by blade deposition of a lithium aluminosilicate glass slurry, were sintered using a YAG-fiber laser, with the aim of finding suitable parameters for an additive manufacturing process based on layer-wise slurry deposition and selective laser densification. The influence of the laser parameters (output power and scan velocity) on the sintering was evaluated, by scanning electron microscopy and by X-ray diffraction, on the basis of the quality of the processed layer. Well densified samples could be obtained only in a small window of values for the output power and the scan velocity. The measurement of the width of a set of single scanned lines allowed also to estimate the minimum resolution of the system along the layer plane.

  14. Adsorption of β-galactosidase on silica and aluminosilicate adsorbents

    NASA Astrophysics Data System (ADS)

    Atyaksheva, L. F.; Dobryakova, I. V.; Pilipenko, O. S.

    2015-03-01

    It is shown that adsorption of β-galactosidase of Aspergillus oryzae fungi on mesoporous and biporous silica and aluminosilicate adsorbents and the rate of the process grow along with the diameter of the pores of the adsorbent. It is found that the shape of the adsorption isotherms changes as well, depending on the texture of the adsorbent: the Michaelis constant rises from 0.3 mM for the enzyme in solution to 0.4-0.5 mM for the enzyme on a surface in the hydrolysis of o-nitrophenyl-β-D-galactopyranoside. It is concluded that β-galactosidase displays its maximum activity on the surface of biporous adsorbents.

  15. Crystallization Kinetics of Calcium-magnesium Aluminosilicate (CMAS) Glass

    NASA Technical Reports Server (NTRS)

    Wiesner, Valerie L.; Bansal, Narottam P.

    2015-01-01

    The crystallization kinetics of a calcium-magnesium aluminosilicate (CMAS) glass with composition relevant for aerospace applications, like air-breathing engines, were evaluated using differential thermal analysis (DTA) in powder and bulk forms. Activation energy and frequency factor values for crystallization of the glass were evaluated. X-ray diffraction (XRD) was used to investigate the onset of crystallization and the phases that developed after heat treating bulk glass at temperatures ranging from 690 to 960 deg for various times. Samples annealed at temperatures below 900 deg remained amorphous, while specimens heat treated at and above 900 deg exhibited crystallinity originating at the surface. The crystalline phases were identified as wollastonite (CaSiO3) and aluminum diopside (Ca(Mg,Al) (Si,Al)2O6). Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were employed to examine the microstructure and chemical compositions of crystalline phases formed after heat treatment.

  16. 21 CFR 184.1807 - Sodium thiosulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Sodium thiosulfate. 184.1807 Section 184.1807 Food... Specific Substances Affirmed as GRAS § 184.1807 Sodium thiosulfate. (a) Sodium thiosulfate (Na2S2O3·5H2O, CAS Reg. No. 010102-0917-097) is also known as sodium hyposulfite. It is prepared synthetically by...

  17. 21 CFR 184.1807 - Sodium thiosulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Sodium thiosulfate. 184.1807 Section 184.1807 Food... Specific Substances Affirmed as GRAS § 184.1807 Sodium thiosulfate. (a) Sodium thiosulfate (Na2S2O3·5H2O, CAS Reg. No. 010102-0917-097) is also known as sodium hyposulfite. It is prepared synthetically by...

  18. 21 CFR 184.1807 - Sodium thiosulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Sodium thiosulfate. 184.1807 Section 184.1807 Food... Specific Substances Affirmed as GRAS § 184.1807 Sodium thiosulfate. (a) Sodium thiosulfate (Na2S2O3·5H2O, CAS Reg. No. 010102-0917-097) is also known as sodium hyposulfite. It is prepared synthetically by...

  19. 21 CFR 184.1807 - Sodium thiosulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Sodium thiosulfate. 184.1807 Section 184.1807 Food... GRAS § 184.1807 Sodium thiosulfate. (a) Sodium thiosulfate (Na2S2O3·5H2O, CAS Reg. No. 010102-0917-097) is also known as sodium hyposulfite. It is prepared synthetically by the reaction of sulfides...

  20. 21 CFR 184.1807 - Sodium thiosulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium thiosulfate. 184.1807 Section 184.1807 Food... Specific Substances Affirmed as GRAS § 184.1807 Sodium thiosulfate. (a) Sodium thiosulfate (Na2S2O3·5H2O, CAS Reg. No. 010102-0917-097) is also known as sodium hyposulfite. It is prepared synthetically by...

  1. Synthetic carbonaceous fuels and feedstocks

    DOEpatents

    Steinberg, Meyer

    1980-01-01

    This invention relates to the use of a three compartment electrolytic cell in the production of synthetic carbonaceous fuels and chemical feedstocks such as gasoline, methane and methanol by electrolyzing an aqueous sodium carbonate/bicarbonate solution, obtained from scrubbing atmospheric carbon dioxide with an aqueous sodium hydroxide solution, whereby the hydrogen generated at the cathode and the carbon dioxide liberated in the center compartment are combined thermocatalytically into methanol and gasoline blends. The oxygen generated at the anode is preferably vented into the atmosphere, and the regenerated sodium hydroxide produced at the cathode is reused for scrubbing the CO.sub.2 from the atmosphere.

  2. Synthetic fuels

    SciTech Connect

    Sammons, V.O.

    1980-01-01

    This guide is designed for those who wish to learn more about the science and technology of synthetic fuels by reviewing materials in the collections of the Library of Congress. This is not a comprehensive bibliography, it is designed to put the reader on target. Subject headings used by the Library of Congress under which books on synthetic fuels can be located are: oil-shale industry; oil-shales; shale oils; synthetic fuels; synthetic fuels industry; coal gasification; coal liquefaction; fossil fuels; hydrogen as fuel; oil sands; petroleum, synthesis gas; biomass energy; pyrolysis; and thermal oil recovery. Basic texts, handbooks, government publications, journals, etc. were included. (DP)

  3. RESULTS OF CAUSTIC DISSOLUTION OF ALUMINOSILICATE SCALE AND CHARACTERIZATION DATA FOR SAMPLES FROM THE EVAPORATOR POT AND GRAVITY DRAIN LINE

    SciTech Connect

    Wilmarth, B; Rita Sullivan, R; Chris Martino, C

    2006-08-21

    The build-up of sodium aluminosilicate scale in the 2H Evaporator system continues to cause operational difficulties. The use of a nitric acid cleaning operation proved successful in 2001. However, the operation required additional facilities to support spent cleaning solution neutralization and was quite costly. A proposed caustic cleaning flowsheet has many advantages over the acid flowsheet. Therefore, samples were retrieved from the evaporator system (gravity drain line and pot) for both chemical and radiological characterization and dissolution testing. The characterization of these scale samples showed the presence of nitrated cancrinite along with a dehydrated zeolite. Small amounts of depleted uranium were also found in these samples as expected and the amount of uranium ranged from 0.5 wt% to 2 wt%. Dissolution in sodium hydroxide solutions of various caustic concentrations showed that the scale slowly dissolves at elevated temperature (90 C). Data from similar testing indicate that the scale removed from the GDL in 2005 dissolves slower than that removed in 1997. Differences in the particle size of these samples of scale may well explain the measured dissolution rate differences.

  4. Aluminosilicates as controlled molecular environments for selective photochemical and catalytic reactions

    SciTech Connect

    Carrado, K.A.

    1986-01-01

    This dissertation concerns research that involves photochemical, catalytic and spectroscopic studies of clays, pillared clays and zeolites. Incorporation of uranyl ions into hectorite, montmorillonite, bentonite and vermiculite clays was monitored by XRD and luminescence methods. Excitation and emission characteristics were studied in order to understand the behavior of uranyl ions in clays after various thermal treatments. Luminescence lifetime measurements elucidated the number of uranyl sites. Uranyl-exchanged clays were found to absorb light at lower energies (445-455nm) than analogous uranyl-exchanged zeolites (425nm). Each uranyl-exchanged clay was tested as a catalyst for the photoassisted oxidation of isopropyl alcohol. Energy transfer (ET) between uranyl and Eu(III) ions in different zeolite framework systems was examined. The efficiency of ET (eta/sub t/) was found to be affected by the type of framework present. Pillared bentonites were examined in the hydrocracking of decane. A catalytically and spectroscopically active dopant ion, Cr(III), was introduced into the clays in both pillared and unpillared forms depending upon synthetic conditions. EPR and DRS were employed to monitor the environment of Cr(III) for determination of its location - whether in the micropore structure or associated with alumina pillars. Catalytic behavior based upon this variability of location was examined. Incorporation of Cr(III) ions into an alumina pillar was found to increase the stability and activity with respect to an alumina PILC catalyst. The results of these studies suggest that selective, efficient catalysts can be designed around inorganic ions in aluminosilicate supports.

  5. Analysis of the biological and chemical reactivity of zeolite-based aluminosilicate fibers and particulates.

    PubMed Central

    Fach, Estelle; Waldman, W James; Williams, Marshall; Long, John; Meister, Richard K; Dutta, Prabir K

    2002-01-01

    Environmental and/or occupational exposure to minerals, metals, and fibers can cause lung diseases that may develop years after exposure to the agents. The presence of toxic fibers such as asbestos in the environment plus the continuing development of new mineral or vitreous fibers requires a better understanding of the specific physical and chemical features of fibers/particles responsible for bioactivity. Toward that goal, we have tested aluminosilicate zeolites to establish biological and chemical structure-function correlations. Zeolites have known crystal structure, are subject to experimental manipulation, and can be synthesized and controlled to produce particles of selected size and shape. Naturally occurring zeolites include forms whose biological activity is reported to range from highly pathogenic (erionite) to essentially benign (mordenite). Thus, we used naturally occurring erionite and mordenite as well as an extensively studied synthetic zeolite based on faujasite (zeolite Y). Bioactivity was evaluated using lung macrophages of rat origin (cell line NR8383). Our objective was to quantitatively determine the biological response upon interaction of the test particulates/fibers with lung macrophages and to evaluate the efficacy of surface iron on the zeolites to promote the Fenton reaction. The biological assessment included measurement of the reactive oxygen species by flow cytometry and chemiluminescence techniques upon phagocytosis of the minerals. The chemical assessment included measuring the hydroxyl radicals generated from hydrogen peroxide by iron bound to the zeolite particles and fibers (Fenton reaction). Chromatography as well as absorption spectroscopy were used to quantitate the hydroxyl radicals. We found that upon exposure to the same mass of a specific type of particulate, the oxidative burst increased with decreasing particle size, but remained relatively independent of zeolite composition. On the other hand, the Fenton reaction

  6. Sodium Test

    MedlinePlus

    ... be limited. Home Visit Global Sites Search Help? Sodium Share this page: Was this page helpful? Also known as: Na Formal name: Sodium Related tests: Chloride , Bicarbonate , Potassium , Electrolytes , Osmolality , Basic ...

  7. The metapelitic garnet biotite muscovite aluminosilicate quartz (GBMAQ) geobarometer

    NASA Astrophysics Data System (ADS)

    Wu, Chun-Ming; Zhao, Guochun C.

    2007-09-01

    In this contribution we have empirically calibrated the garnet-biotite-muscovite-aluminosilicate-quartz (GBMAQ) barometer using low- to medium-high-pressure, mid-grade metapelites. Application of the barometer suggests that the GBMAQ and GASP barometers show quite similar pressure estimates. Furthermore, metapelites within thermal contact aureole or very limited geographic area show no meaningful pressure diversity determined by the GBMAQ and GASP barometers which is the geological reality. The random error of the GBMAQ barometer is expected to be around ± 0.8 kbar, and this barometer shows no systematic bias with respect to either pressure, or temperature, or Al VI in muscovite, or Fe in biotite, or Fe in garnet. The GBMAQ barometer is thermodynamically consistent with the garnet-biotite geothermometer because they share the same activity models of both garnet and biotite. This barometer is especially useful for assemblages with Ca-poor garnet or Ca-poor plagioclase or plagioclase-absent metapelites. Application of this barometer beyond the calibration ranges, i.e., P- T range and chemical ranges of the minerals, is not encouraged.

  8. Surface functionalization of aluminosilicate nanotubes with organic molecules

    PubMed Central

    Ma, Wei; Yah, Weng On; Otsuka, Hideyuki

    2012-01-01

    Summary The surface functionalization of inorganic nanostructures is an effective approach for enriching the potential applications of existing nanomaterials. Inorganic nanotubes attract great research interest due to their one-dimensional structure and reactive surfaces. In this review paper, recent developments in surface functionalization of an aluminosilicate nanotube, “imogolite”, are introduced. The functionalization processes are based on the robust affinity between phosphate groups of organic molecules and the aluminol (AlOH) surface of imogolite nanotubes. An aqueous modification process employing a water soluble ammonium salt of alkyl phosphate led to chemisorption of molecules on imogolite at the nanotube level. Polymer-chain-grafted imogolite nanotubes were prepared through surface-initiated polymerization. In addition, the assembly of conjugated molecules, 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-yl)ethylphosphonic acid (HT3P) and 2-(5’’-hexyl-2,2’:5’,2’’-terthiophen-5-yl)ethylphosphonic acid 1,1-dioxide (HT3OP), on the imogolite nanotube surface was achieved by introducing a phosphonic acid group to the corresponding molecules. The optical and photophysical properties of these conjugated-molecule-decorated imogolite nanotubes were characterized. Moreover, poly(3-hexylthiophene) (P3HT) chains were further hybridized with HT3P modified imogolite to form a nanofiber hybrid. PMID:22428100

  9. Synthetic oils

    NASA Technical Reports Server (NTRS)

    Hatton, R. E.

    1973-01-01

    Synthetic lubricants are discussed by chemical class and their general strengths and weaknesses in terms of lubrication properties are analyzed. Comparative ratings are given for 14 chemical classes and are used as a guide for lubricant selection. The effects of chemical structure on the properties of the lubricant are described with special emphasis on thermal stability. The diversity of synthetic lubricants which is provided by the wide range of properties permits many applications, some of which are reported.

  10. Modeling the local structure and energetics of protozeolitic nanoclusters in hydrothermally stable aluminosilicate mesostructures.

    PubMed

    Li, Hong; Mahanti, S D; Pinnavaia, Thomas J

    2005-02-24

    The density functional theory (DFT) method is used to investigate the structure and bonding of silica and aluminosilicate nanoclusters containing five- and six-membered oxygen rings. The clusters, which are derived from the BEA zeolite structure, are considered as models of the protozeolitic clusters that are incorporated into the pore walls of steam stable aluminosilicate mesostructures assembled from zeolite seeds. Two locally different Brønsted acid sites in the aluminosilicate structure are identified for the adsorption of a water molecule. The sterically more open acid site is favored for water binding. The stability of the aluminosilicate structure in the presence of H2O molecule is studied by breaking an Al-O bond and inserting a water molecule into the five-membered ring structure. We find that an excitation energy at least 18 times larger than the room-temperature thermal energy is needed to break the stable five-membered ring structure, implying a high hydrothermal stability and acidity for this aluminosilicate structure. PMID:16851274

  11. Dominant toughening mechanisms in barium aluminosilicate (BAS) glass-ceramics

    NASA Astrophysics Data System (ADS)

    Griggs, Jason Alan

    The purpose of this study was to develop a barium aluminosilicate (BAS) glass-ceramic with improved strength and fracture toughness by controlling the morphology of the constituent phases through a series of thermal crystallization treatments. The specific objectives of this study were to (1) determine which toughening mechanisms are active in the BAS system, (2) provide quantitative estimates of the relative contributions of those mechanisms, and (3) identify the processing conditions that correspond to a glass-ceramic with optimal fracture toughness. The BAS system was chosen for this study because of its potential applications in CAD-CAM production of dental prostheses. It is concluded that load sharing and crack deflection are the only major sources of toughening in the BAS system. Theoretical predictions for toughening increases due to load sharing and crack deflection are insufficient to account for 100% of the increases observed. The excess increase in fracture toughness is produced by thermal mismatch between and crystal and glass phases. The strength and fracture toughness of BAS glass-ceramics are shown to increase with increasing crystal growth time over the entire range of treatments studied. The strength and fracture toughness increased from 63 ± 8 MPa and 0.89 ± 0.05 MPa*msp{1/2}, respectively for BAS glass to 141 ± 8 MPa and 1.87 ± 0.07 MPa*msp{1/2} respectively for a glass-ceramic treated for 256 h at 975sp°C. Fracture toughness was also shown to increase with increasing mean crystal size. A non-stoichiometric glass composition results in thermal compatibility between the glass and crystal phases, eliminating the weakening at large crystal sizes that can be associated with a spontaneous microcracking mechanism.

  12. Synthetic environments

    NASA Astrophysics Data System (ADS)

    Lukes, George E.; Cain, Joel M.

    1996-02-01

    The Advanced Distributed Simulation (ADS) Synthetic Environments Program seeks to create robust virtual worlds from operational terrain and environmental data sources of sufficient fidelity and currency to interact with the real world. While some applications can be met by direct exploitation of standard digital terrain data, more demanding applications -- particularly those support operations 'close to the ground' -- are well-served by emerging capabilities for 'value-adding' by the user working with controlled imagery. For users to rigorously refine and exploit controlled imagery within functionally different workstations they must have a shared framework to allow interoperability within and between these environments in terms of passing image and object coordinates and other information using a variety of validated sensor models. The Synthetic Environments Program is now being expanded to address rapid construction of virtual worlds with research initiatives in digital mapping, softcopy workstations, and cartographic image understanding. The Synthetic Environments Program is also participating in a joint initiative for a sensor model applications programer's interface (API) to ensure that a common controlled imagery exploitation framework is available to all researchers, developers and users. This presentation provides an introduction to ADS and the associated requirements for synthetic environments to support synthetic theaters of war. It provides a technical rationale for exploring applications of image understanding technology to automated cartography in support of ADS and related programs benefitting from automated analysis of mapping, earth resources and reconnaissance imagery. And it provides an overview and status of the joint initiative for a sensor model API.

  13. Synthetic Jets

    NASA Technical Reports Server (NTRS)

    Milanovic, Ivana M.

    2003-01-01

    Current investigation of synthetic jets and synthetic jets in cross-flow examined the effects of orifice geometry and dimensions, momentum-flux ratio, cluster of orifices, pitch and yaw angles as well as streamwise development of the flow field. This comprehensive study provided much needed experimental information related to the various control strategies. The results of the current investigation on isolated and clustered synthetic jets with and without cross-flow will be further analyzed and documented in detail. Presentations at national conferences and publication of peer- reviewed journal articles are also expected. Projected publications will present both the mean and turbulent properties of the flow field, comparisons made with the data available in an open literature, as well as recommendations for the future work.

  14. Li{sup +} alumino-silicate ion source development for the neutralized drift compression experiment

    SciTech Connect

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.; Seidl, Peter A.; Waldron, William L.; Wu, James K.

    2011-01-15

    We report results on lithium alumino-silicate ion source development in preparation for warm dense matter heating experiments on the new neutralized drift compression experiment II. The practical limit to the current density for a lithium alumino-silicate source is determined by the maximum operating temperature that the ion source can withstand before running into problems of heat transfer, melting of the alumino-silicate material, and emission lifetime. Using small prototype emitters, at a temperature of {approx_equal}1275 deg. C, a space-charge limited Li{sup +} beam current density of J {approx_equal}1 mA/cm{sup 2} was obtained. The lifetime of the ion source was {approx_equal}50 h while pulsing at a rate of 0.033 Hz with a pulse duration of 5-6 {mu}s.

  15. Li+ alumino-silicate ion source development for the Neutralized Drift Compression Experiment (NDCX)

    SciTech Connect

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.; Seidl, Peter A.; Waldron, William L.; Wu, James K.

    2010-10-01

    We report results on lithium alumino-silicate ion source development in preparation for warmdense-matter heating experiments on the new Neutralized Drift Compression Experiment (NDCXII). The practical limit to the current density for a lithium alumino-silicate source is determined by the maximum operating temperature that the ion source can withstand before running into problems of heat transfer, melting of the alumino-silicate material, and emission lifetime. Using small prototype emitters, at a temperature of ~;;1275 oC, a space-charge-limited Li+ beam current density of J ~;;1 mA/cm2 was obtained. The lifetime of the ion source was ~;;50 hours while pulsing at a rate of 0.033 Hz with a pulse duration of 5-6 mu s.

  16. Synthesis and immobilization of silver nanoparticles on aluminosilicate nanotubes and their antibacterial properties

    NASA Astrophysics Data System (ADS)

    Ipek Yucelen, G.; Connell, Rachel E.; Terbush, Jessica R.; Westenberg, David J.; Dogan, Fatih

    2016-04-01

    A novel colloidal method is presented to synthesize silver nanoparticles on aluminosilicate nanotubes. The technique involves decomposition of AgNO3 solution to Ag nanoparticles in the presence of aluminosilicate nanotubes at room temperature without utilizing of reducing agents or any organic additives. Aluminosilicate nanotubes are shown to be capable of providing a unique chemical environment, not only for in situ conversion of Ag+ into Ag0, but also for stabilization and immobilization of Ag nanoparticles. The synthesis strategy described here could be implemented to obtain self-assembled nanoparticles on other single-walled metal oxide nanotubes for unique applications. Finally, we demonstrated that nanotube/nanoparticle hybrid show strong antibacterial activity toward Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli.

  17. Evidence for lithium-aluminosilicate supersaturation of pegmatite-forming melts

    NASA Astrophysics Data System (ADS)

    Maneta, Victoria; Baker, Don R.; Minarik, William

    2015-07-01

    New experimental data on the solubility of lithium (Li) at spodumene (LiAlSi2O6) and petalite (LiAlSi4O10) saturation at 500 MPa and 550-750 °C reveal evidence for lithium supersaturation of pegmatite-forming melts before the formation of Li-aluminosilicates. The degree of Li enrichment in granitic melts can reach ~11,000 ppm above the saturation value before the crystallization of Li-aluminosilicate minerals at lower temperatures. Comparison of the experimental results with the spodumene-rich Moblan pegmatite (Quebec) is consistent with extreme Li enrichment of the pegmatite-forming melt prior to emplacement, which cannot be explained with equilibrium crystallization of Li-aluminosilicates from a common granitic melt. The results of this study support the model of disequilibrium fractional crystallization through liquidus undercooling as the most plausible mechanism for the generation of such Li-rich ore resources.

  18. Aflatoxin adsorbent capacity of two Mexican aluminosilicates in experimentally contaminated chick diets.

    PubMed

    Márquez Márquez, R N; Tejada de Hernandez, I

    1995-01-01

    To study the aflatoxin-adsorbent capacity of two Mexican aluminosilicates (ALS) identified as Atapulgita (AT) and Füller earth (FE), these ALS were compared with a commercial aluminosilicate, Novasil (NV), at two concentrations (0.05 and 1.0%) added to chick diets with 55% of experimentally contaminated corn (200 micrograms/kg). Eight treatments were studied with two replicates for treatment and four chicks per cage. Results (weight gain, feed efficiency, gross and microscopic pathology) at 3 weeks showed that both Mexican ALS were as efficient as the commercial material in protecting chicks against the aflatoxin toxicity. PMID:7664939

  19. Spectroscopy and laser action of rhodamine 6G doped aluminosilicate xerogels

    SciTech Connect

    McKiernan, J.M.; Yamanaka, S.A.; Dunn, B.; Zink, J.I. )

    1990-07-26

    Rhodamine 6G (R6G) doped aluminosilicate glass synthesized by the sol-gel method exhibits laser action. Transparent 5 mm {times} 5 mm {times} 10 mm monoliths were used as cast in a simple laser cavity. This new material was pumped at rates of up to 25 Hz and was still active after as many as 40,000 pump pulses. Luminescence and free-running laser spectra are measured. The dependence of the R6G doped aluminosilicate dye laser output on the number of pump pulses and the pump pulse energy is discussed.

  20. Calculation of the Aluminosilicate Half-Life Formation Time in the 2H Evaporator

    SciTech Connect

    Fondeur, F.F.

    2000-09-21

    The 2H Evaporator contains large quantities of aluminosilicate solids deposited on internal fixtures. The proposed cleaning operations will dissolve the solids in nitric acid. Operations will then neutralize the waste prior to transfer to a waste tank. Combining recent calculations of heat transfer for the 2H Evaporator cleaning operations and laboratory experiments for dissolution of solid samples from the pot, the authors estimated the re-formation rate for aluminosilicates during cooling. The results indicate a half-life formation of 17 hours when evaporator solution cools from 60 degrees C and 9 hours when cooled from 90 degrees C.

  1. One-pot synthesis of hierarchical FeZSM-5 zeolites from natural aluminosilicates for selective catalytic reduction of NO by NH3.

    PubMed

    Yue, Yuanyuan; Liu, Haiyan; Yuan, Pei; Yu, Chengzhong; Bao, Xiaojun

    2015-01-01

    Iron-modified ZSM-5 zeolites (FeZSM-5s) have been considered to be a promising catalyst system to reduce nitrogen oxide emissions, one of the most important global environmental issues, but their synthesis faces enormous economic and environmental challenges. Herein we report a cheap and green strategy to fabricate hierarchical FeZSM-5 zeolites from natural aluminosilicate minerals via a nanoscale depolymerization-reorganization method. Our strategy is featured by neither using any aluminum-, silicon-, or iron-containing inorganic chemical nor involving any mesoscale template and any post-synthetic modification. Compared with the conventional FeZSM-5 synthesized from inorganic chemicals with the similar Fe content, the resulting hierarchical FeZSM-5 with highly-dispersed iron species showed superior catalytic activity in the selective catalytic reduction of NO by NH3. PMID:25791958

  2. One-pot synthesis of hierarchical FeZSM-5 zeolites from natural aluminosilicates for selective catalytic reduction of NO by NH3

    PubMed Central

    Yue, Yuanyuan; Liu, Haiyan; Yuan, Pei; Yu, Chengzhong; Bao, Xiaojun

    2015-01-01

    Iron-modified ZSM-5 zeolites (FeZSM-5s) have been considered to be a promising catalyst system to reduce nitrogen oxide emissions, one of the most important global environmental issues, but their synthesis faces enormous economic and environmental challenges. Herein we report a cheap and green strategy to fabricate hierarchical FeZSM-5 zeolites from natural aluminosilicate minerals via a nanoscale depolymerization-reorganization method. Our strategy is featured by neither using any aluminum-, silicon-, or iron-containing inorganic chemical nor involving any mesoscale template and any post-synthetic modification. Compared with the conventional FeZSM-5 synthesized from inorganic chemicals with the similar Fe content, the resulting hierarchical FeZSM-5 with highly-dispersed iron species showed superior catalytic activity in the selective catalytic reduction of NO by NH3. PMID:25791958

  3. One-pot synthesis of hierarchical FeZSM-5 zeolites from natural aluminosilicates for selective catalytic reduction of NO by NH3

    NASA Astrophysics Data System (ADS)

    Yue, Yuanyuan; Liu, Haiyan; Yuan, Pei; Yu, Chengzhong; Bao, Xiaojun

    2015-03-01

    Iron-modified ZSM-5 zeolites (FeZSM-5s) have been considered to be a promising catalyst system to reduce nitrogen oxide emissions, one of the most important global environmental issues, but their synthesis faces enormous economic and environmental challenges. Herein we report a cheap and green strategy to fabricate hierarchical FeZSM-5 zeolites from natural aluminosilicate minerals via a nanoscale depolymerization-reorganization method. Our strategy is featured by neither using any aluminum-, silicon-, or iron-containing inorganic chemical nor involving any mesoscale template and any post-synthetic modification. Compared with the conventional FeZSM-5 synthesized from inorganic chemicals with the similar Fe content, the resulting hierarchical FeZSM-5 with highly-dispersed iron species showed superior catalytic activity in the selective catalytic reduction of NO by NH3.

  4. Synthetic Astrobiology

    NASA Technical Reports Server (NTRS)

    Rothschild, Lynn J.

    2016-01-01

    Synthetic biology - the design and construction of new biological parts and systems and the redesign of existing ones for useful purposes - has the potential to transform fields from pharmaceuticals to fuels. Our lab has focused on the potential of synthetic biology to revolutionize all three major parts of astrobiology: Where do we come from? Where are we going? and Are we alone? For the first and third, synthetic biology is allowing us to answer whether the evolutionary narrative that has played out on planet earth is likely to have been unique or universal. For example, in our lab we are re-evolving the biosynthetic pathways of amino acids in order to understand potential capabilities of an early organism with a limited repertoire of amino acids and developing techniques for the recovery of metals from spent electronics on other planetary bodies. And what about the limits for life? Can we create organisms that expand the envelope for life? In the future synthetic biology will play an increasing role in human activities both on earth, in fields as diverse as human health and the industrial production of novel bio-composites. Beyond earth, we will rely increasingly on biologically-provided life support, as we have throughout our evolutionary history. In order to do this, the field will build on two of the great contributions of astrobiology: studies of the origin of life and life in extreme environments.

  5. Synthetic Astrobiology

    NASA Technical Reports Server (NTRS)

    Rothschild, Lynn J.

    2015-01-01

    Synthetic biology - the design and construction of new biological parts and systems and the redesign of existing ones for useful purposes - has the potential to transform fields from pharmaceuticals to fuels. Our lab has focused on the potential of synthetic biology to revolutionize all three major parts of astrobiology: Where do we come from? Where are we going? and Are we alone? For the first and third, synthetic biology is allowing us to answer whether the evolutionary narrative that has played out on planet earth is likely to have been unique or universal. For example, in our lab we are re-evolving the biosynthetic pathways of amino acids in order to understand potential capabilities of an early organism with a limited repertoire of amino acids and developing techniques for the recovery of metals from spent electronics on other planetary bodies. In the future synthetic biology will play an increasing role in human activities both on earth, in fields as diverse as human health and the industrial production of novel bio-composites. Beyond earth, we will rely increasingly on biologically-provided life support, as we have throughout our evolutionary history. In order to do this, the field will build on two of the great contributions of astrobiology: studies of the origin of life and life in extreme environments.

  6. Sodium Oxybate

    MedlinePlus

    ... if you use or have ever used street drugs, or if you have overused prescription medications. Sodium oxybate may be harmful when taken by people other than the person for whom it was prescribed. Do not sell or give your sodium oxybate to anyone else; selling or sharing it is against the law. Store ...

  7. In-situ growth of porous alumino-silicates and fabrication of nano-porous membranes

    NASA Astrophysics Data System (ADS)

    Kodumuri, Pradeep

    2009-12-01

    Feasibility of depositing continuous films of nano-porous alumino-silicates, primarily zeolites and MCM-41, on metallic and non-metallic substrates was examined with an aim to develop membranes for separation of gaseous mixtures and also for application as hydrogen storage material. Mesoporous silica was deposited in-side the pores of these nano-porous disks with an aim to develop membranes for selective separations. Our study involves supported zeolite film growth on substrates using in-situ hydrothermal synthesis. Faujasite, Silicalite and Mesoporous silica have been grown on various metallic and non-metallic supports. Metallic substrates used for film growth included anodized titanium, sodium hydroxide treated Titanium, Anodized aluminum, and sintered copper. A non-metallic substrate used was nano-porous aluminum oxide. Zeolite film growth was characterized using Scanning Electron Microscope (AMRAY 1820) and High Resolution Transmission electron microscope. Silicalite was found to grow uniformly on all the substrates to form a uniform and closely packed film. Faujasite tends to grow in the form of individual particles which do not inter-grow like silicalite to form a continuous film. Mesoporous silica was found to grow uniformly on anodized aluminum compared to growth on sintered copper and anodized titanium. Mesoporous silica growth on AnodiscRTM was found to cover more than half the surface of the substrate. Commercially obtained AnodiscRTM was found to have cylindrical channels of the pore branching into each other and since we needed pore channels of uniform dimension for Mesoporous silica growth, we have fabricated nano-porous alumina with uniform pore channels. Nano-porous alumina membranes containing uniform distribution of through thickness cylindrical pore channels were fabricated using anodization of aluminum disks. Free-standing nano-porous alumina membranes were used as templates for electro-deposition in order to fabricate nickel and palladium nano

  8. Selectivity modification by ion memory of magneso-silicate and magnesium alumino-silicate as inorganic sorbents.

    PubMed

    Abou-Mesalam, Mamdouh M; El-Naggar, Ibrahim M

    2008-06-15

    Synthetic magneso-silicate and magnesium alumino-silicate as inorganic ion exchange materials with the formula MgSi5.59O(12.18).5.93H2O and MgAl2.32Si5.2O(14.88).18.23H2O, respectively, have been found to be suitable for the removal of Cs+, Co2+ and Eu3+ ions with the selectivity sequence Eu3+>Co2+>Cs+. Samples of Cs-, Co- and Eu-loaded were prepared and thermally treated at 850 degrees C in a furnace for the creation of specific cavity. Surface area, IR and X-ray diffraction patterns of the products were conducted. Surface area values of OMS, OMAS, TMS, TMAS, ETMS and ETMAS were measured and indicated an increasing in the surface area values for the TMS and TMAS samples and decreasing in the ETMS and ETMAS samples. Desorption studies in nitric acid medium were carried out and reloading of the eluted solids with the studied cations were conduced and the data show an ion memory behaviour for the eluted solids. Finally, the rate of Cs+ ion sorption on OMS, OMAS, ETMS and ETMAS was studied. The diffusion coefficients calculated indicated that the diffusion of Cs+ ion is high for the ETMS and ETMAS samples compared to the OMS and OMAS samples. PMID:18054429

  9. Technetium (VII) Co-precipitation with Framework Aluminosilicates

    SciTech Connect

    Harsh, James B.; Dickson, Johnbull Otah; Pierce, Eric M.; Bargar, John

    2015-07-13

    Technetium-99 (99Tc), a long-lived radionuclide, is one of the most widespread contaminants within the Hanford subsurface. At some depths, it is only extractable with strong acids, suggesting incorporation into a solid phase. We hypothesized that Tc may have coprecipitated with feldspathoid aluminosilicates under waste tanks that had leaked caustic solutions into the vadose zone. Our objectives were to determine if Tc could be incorporated into the feldspathoids cancrinite and sodalite and under what conditions coprecipitation could occur. Our hypothesis was that sodalite was more likely to incorporate and retain Tc. Our approach was to use known methods of feldspathoid formation in solutions resembling those in Hanford waste tanks contacting sediments in terms of major ion (Na, NO3, OH, Al(OH)4, and Si(OH)4 concentrations. In some cases, Al and Si were supplied from zeolite. We used perrhenate (ReO4) as a surrogate for pertechnetate (TcO4) to avoid the radioactivity. The major findings of this study were 1) ReO4 could be incorporated into either sodalite or cancrinite but the concentration in the solid was < 1% of the competing ion Cl, NO3, or NO2. 2) The small amount of ReO4 incorporated was not exchangeable with NO3 or NO2. 3) In sodalite, NO3 was highly preferred over ReO4 but significant Re-sodalite was formed when the mole fraction in solution (Re/Re+N) exceeded 0.8. 4) A nonlinear relation between the unit cell parameter and amount of Re incorporated suggested that a separate Re-sodalite phase was formed rather than a solid solution. 5) We determined that sodalite preference for sodalite in the presence of different anions increased with the ionic size of the competing anion: Cl < CO3 < NO3 < SO4 < MnO4 < WO4 and significant incorporation did not occur unless the difference in anion radii was less than 12%. 6) Re(VII) was not significantly reduced to Re(IV) under the conditions of this experiment and Re appeared to be a good surrogate for Tc under oxidizing

  10. Aluminosilicate melts and glasses at 1 to 3 GPa: Temperature and pressure effects on recovered structural and density changes

    USGS Publications Warehouse

    Bista, S; Stebbins, Jonathan; Hankins, William B.; Sisson, Thomas W.

    2015-01-01

    In the pressure range in the Earth’s mantle where many basaltic magmas are generated (1 to 3 GPa) (Stolper et al. 1981), increases in the coordination numbers of the network-forming cations in aluminosilicate melts have generally been considered to be minor, although effects on silicon and particularly on aluminum coordination in non-bridging oxygen-rich glasses from the higher, 5 to 12 GPa range, are now well known. Most high-precision measurements of network cation coordination in such samples have been made by spectroscopy (notably 27Al and 29Si NMR) on glasses quenched from high-temperature, high-pressure melts synthesized in solid-media apparatuses and decompressed to room temperature and 1 bar pressure. There are several effects that could lead to the underestimation of the extent of actual structural (and density) changes in high-pressure/temperature melts from such data. For non-bridging oxygen-rich sodium and calcium aluminosilicate compositions in the 1 to 3 GPa range, we show here that glasses annealed near to their glass transition temperatures systematically record higher recovered increases in aluminum coordination and in density than samples quenched from high-temperature melts. In the piston-cylinder apparatus used, rates of cooling through the glass transition are measured as very similar for both higher and lower initial temperatures, indicating that fictive temperature effects are not the likely explanation of these differences. Instead, transient decreases in melt pressure during thermal quenching, which may be especially large for high initial run temperatures, of as much as 0.5 to 1 GPa, may be responsible. As a result, the equilibrium proportion of high-coordinated Al in this pressure range may be 50 to 90% greater than previously estimated, reaching mean coordination numbers (e.g., 4.5) that are probably high enough to significantly affect melt properties. New data on jadeite (NaAlSi2O6) glass confirm that aluminum coordination increase

  11. Synthetic chromosomes.

    PubMed

    Schindler, Daniel; Waldminghaus, Torsten

    2015-11-01

    What a living organism looks like and how it works and what are its components-all this is encoded on DNA, the genetic blueprint. Consequently, the way to change an organism is to change its genetic information. Since the first pieces of recombinant DNA have been used to transform cells in the 1970s, this approach has been enormously extended. Bigger and bigger parts of the genetic information have been exchanged or added over the years. Now we are at a point where the construction of entire chromosomes becomes a reachable goal and first examples appear. This development leads to fundamental new questions, for example, about what is possible and desirable to build or what construction rules one needs to follow when building synthetic chromosomes. Here we review the recent progress in the field, discuss current challenges and speculate on the appearance of future synthetic chromosomes. PMID:26111960

  12. Interface Induced Growth and Transformation of Polymer-Conjugated Proto-Crystalline Phases in Aluminosilicate Hybrids: A Multiple-Quantum (23)Na-(23)Na MAS NMR Correlation Spectroscopy Study.

    PubMed

    Brus, Jiri; Kobera, Libor; Urbanova, Martina; Doušová, Barbora; Lhotka, Miloslav; Koloušek, David; Kotek, Jiří; Čuba, Pavel; Czernek, Jiri; Dědeček, Jiří

    2016-03-22

    Nanostructured materials typically offer enhanced physicochemical properties because of their large interfacial area. In this contribution, we present a comprehensive structural characterization of aluminosilicate hybrids with polymer-conjugated nanosized zeolites specifically grown at the organic-inorganic interface. The inorganic amorphous Al-O-Si framework is formed by alkali-activated low-temperature transformation of metakaoline, whereas simultaneous copolymerization of organic comonomers creates a secondary epoxide network covalently bound to the aluminosilicate matrix. This secondary epoxide phase not only enhances the mechanical integrity of the resulting hybrids but also introduces additional binding sites accessible for compensating negative charge on the aluminosilicate framework. This way, the polymer network initiates growth and subsequent transformation of protocrystalline short-range ordered zeolite domains that are located at the organic-inorganic interface. By applying an experimental approach based on 2D (23)Na-(23)Na double-quantum (DQ) MAS NMR spectroscopy, we discovered multiple sodium binding sites in these protocrystalline domains, in which immobilized Na(+) ions form pairs or small clusters. It is further demonstrated that these sites, the local geometry of which allows for the pairing of sodium ions, are preferentially occupied by Pb(2+) ions during the ion exchange. The proposed synthesis protocol thus allows for the preparation of a novel type of geopolymer hybrids with polymer-conjugated zeolite phases suitable for capturing and storage of metal cations. The demonstrated (23)Na-(23)Na DQ MAS NMR combined with DFT calculations represents a suitable approach for understanding the role of Na(+) ions in aluminositicate solids and related inorganic-organic hybrids, particularly their specific arrangement and clustering at interfacial areas. PMID:26931131

  13. EFFECT OF IMPURITIES ASSOCIATED WITH ALUMINOSILICATES ON ARSENIC SORPTION AND OXIDATION

    EPA Science Inventory

    Arsenite, As(III), and arsenate, As(V), are of increasing environmental concern. Risk assessment and risk management of arsenic contaminated sites requires a better understanding of arsenic-mineral interactions. Aluminosilicate minerals, such as feldspars and clays, are the mos...

  14. One-pot surfactant assisted synthesis of aluminosilicate macrochannels with tunable micro- or mesoporous wall structure.

    PubMed

    Léonard, Alexandre; Blin, Jean-Luc; Su, Bao-Lian

    2003-10-21

    A one-step surfactant assisted synthesis pathway was developed leading to novel hierarchical macro-meso- (or micro-)porous aluminosilicates made of an assembly of macrochannels with openings between 0.5 and 2.0 microm and wormhole-like amorphous walls with tunable pore sizes. PMID:14594284

  15. Mechanism of interface formation in a silicon carbide fiber-reinforced magnesuium aluminosilicate

    SciTech Connect

    Kumar, A.; Knowles, K.M.

    1995-12-01

    The formation of sliding interfacial layers is a major key to the success of fiber-reinforced glass-ceramics. This paper reports the mechanism of formation of fiber-matrix interfaces during oxidizing heat treatments in a SiC fiber-reinforced magnesium aluminosilicate.

  16. Sorption of cesium and strontium from mineralized aqueous solutions on natural aluminosilicates modified by ferrocyanides of heavy metals

    SciTech Connect

    Panasyugin, A.S.; Trofimenko, N.E.; Masherova, N.P.; Rat`ko, A.I.; Golikova, N.I.

    1994-03-10

    The sorption behavior of natural aluminosilicates (bentonite and clinoptilolite) and aluminosilicates modified by ferrocyanides of heavy metals has been studied relative to radionuclides {sup 137}Cs and {sup 90}Sr in the presence of various quantities of alkali and alkaline-earth ions (e.g. surface waters). It has been shown that the distribution coefficients of the modified samples may exceed 100 for Sr{sup 2+} and 10,000 for Cs{sup +}; however, with a concentration of mineral background over 1.0 g{center_dot}liter, the competing ions strongly depress the sorption properties of the aluminosilicates.

  17. Synthetic Cathinones ("Bath Salts")

    MedlinePlus

    ... still unknown about how synthetic cathinones affect the human brain. Researchers do know that synthetic cathinones are chemically ... of the chemicals in synthetic cathinones affect the human brain. Synthetic cathinones can cause: nosebleeds paranoia increased sociability ...

  18. Influence of Boehmite Precursor on Aluminosilicate Aerogel Pore Structure, Phase Stability and Resistance to Densification at High Temperatures

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.; Guo, Haiquan; Newlin, Katy N.

    2011-01-01

    Aluminosilicate aerogels are of interest as constituents of thermal insulation systems for use at temperatures higher than those attainable with silica aerogels. It is anticipated that their effectiveness as thermal insulators will be influenced by their morphology, pore size distribution, physical and skeletal densities. The present study focuses on the synthesis of aluminosilicate aerogel from a variety of Boehmite (precursors as the Al source, and tetraethylorthosilicate (TEOS) as the Si source, and the influence of starting powder on pore structure and thermal stability.

  19. Nuclear Magnetic Resonance Studies of Aluminosilicate Gels Prepared in High-Alkaline and Salt-Concentrated Solutions

    SciTech Connect

    Wang, Li Q.; Mattigod, Shas V.; Parker, Kent E.; Hobbs, David T.; McCready, David E.

    2005-01-11

    We have examined the formation of aluminosilicate in high alkaline and salt concentrated solutions characteristic of nuclear tank wastes. Information on the mechanism and kinetics of the phase formation under hydrothermal conditions was obtained by characterization the structures of gel phases as a function of time and composition using multinuclear NMR techniques in combination with x-ray diffraction. This work offers a new insight into the aluminum and aluminosilicate chemistry in simulated nuclear tank wastes.

  20. A Calorimetric Study of Almandine: Are the Thermodynamic Properties of the End-Member Aluminosilicate Garnets Finally Known Quantitatively?

    NASA Astrophysics Data System (ADS)

    Dachs, E.; Geiger, C. A.; Benisek, A.

    2012-12-01

    The aluminosilicate garnets (E3Al2Si3O12 with E = Fe2+, Mn2+, Ca, Mg) form an important rock-forming mineral group. Much study has been directed toward determining their thermodynamic properties. The iron end-member almandine (Fe3Al2Si3O12) is a key phase in many petrologic investigations. As part of an ongoing calorimetric and thermodynamic study of the aluminosilicate garnets, the heat capacity of three synthetic well-characterized polycrystalline almandine garnets and one natural almandine-rich single crystal was measured. The various garnets were characterized by optical microscopy, electron-microprobe analysis, X-ray powder diffraction and 57Fe Mössbauer spectroscopy. Heat capacity measurements were performed in the temperature range 3 to 300 K using relaxation calorimetry and between 282 and 764 K using DSC methods. From the former, So values between 336.7 ± 0.8 and 337.8 ± 0.8 J/molK are calculated for the different samples. The smaller value is considered the best So for end-member stoichiometric almandine, because it derives from the "best" Fe3+-free synthetic sample. The Cp behavior for almandine at T > 298 K is given by the polynomial (in J/molK): Cp = 649.06(±4) - 3837.57(±122)T-0.5 - 1.44682(±0.06)107T-2 + 1.94834(±0.09)109T-3, which is calculated using DSC data together with one published heat-content datum determined by transposed-drop calorimetry along with a new determination that gives H1181K - H302K = 415.0 ± 3.2 kJ/mole. Almandine shows a λ-type heat-capacity anomaly at low temperatures resulting from a paramagnetic-antiferromagnetic phase transition at about 9 K. The lattice heat capacity was calculated using the single-parameter phonon dispersion model of Komada and Westrum (1997), which allows the non-lattice heat capacity (Cex) behavior to be modelled. An analysis shows the presence of an electronic heat-capacity contribution (Cel - Schottky anomaly) around 17 K that is superimposed on a larger magnetic heat-capacity effect (Cmag

  1. Acifluorfen, sodium

    Integrated Risk Information System (IRIS)

    Acifluorfen , sodium ; CASRN 62476 - 59 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcino

  2. Sodium diethyldithiocarbamate

    Integrated Risk Information System (IRIS)

    Sodium diethyldithiocarbamate ; CASRN 148 - 18 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Non

  3. Sodium fluoroacetate

    Integrated Risk Information System (IRIS)

    Sodium fluoroacetate ; CASRN 62 - 74 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogen

  4. Sodium azide

    Integrated Risk Information System (IRIS)

    Sodium azide ; CASRN 26628 - 22 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  5. Sodium cyanide

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 28 , 2010 , the assessment summary for sodium cyanide is included in the

  6. Formation processes and main properties of hollow aluminosilicate microspheres in fly ash from thermal power stations

    SciTech Connect

    V.S. Drozhzhin; M.Ya. Shpirt; L.D. Danilin; M.D. Kuvaev; I.V. Pikulin; G.A. Potemkin; S.A. Redyushev

    2008-04-15

    The main parameters of aluminosilicate microspheres formed at thermal power stations in Russia were studied. These parameters are responsible for the prospective industrial application of these microspheres. A comparative analysis of the properties of mineral coal components, the conditions of coal combustion, and the effects of chemical and phase-mineralogical compositions of mineral impurities in coals from almost all of the main coal deposits on the formation of microspheres was performed. The effects of thermal treatment conditions on gas evolution processes in mineral particles and on the fraction of aluminosilicate microspheres in fly ash were considered. It was found that the yield of microspheres was higher in pulverized coal combustion in furnaces with liquid slag removal, all other factors being equal. The regularities of microsphere formation were analyzed, and the mechanism of microsphere formation in fly ash during the combustion of solid fuels was considered.

  7. High-Aluminum-Affinity Silica Is a Nanoparticle That Seeds Secondary Aluminosilicate Formation

    PubMed Central

    Jugdaohsingh, Ravin; Brown, Andy; Dietzel, Martin; Powell, Jonathan J.

    2013-01-01

    Despite the importance and abundance of aluminosilicates throughout our natural surroundings, their formation at neutral pH is, surprisingly, a matter of considerable debate. From our experiments in dilute aluminum and silica containing solutions (pH ~ 7) we previously identified a silica polymer with an extraordinarily high affinity for aluminium ions (high-aluminum-affinity silica polymer, HSP). Here, further characterization shows that HSP is a colloid of approximately 2.4 nm in diameter with a mean specific surface area of about 1,000 m2 g-1 and it competes effectively with transferrin for Al(III) binding. Aluminum binding to HSP strongly inhibited its decomposition whilst the reaction rate constant for the formation of the β-silicomolybdic acid complex indicated a diameter between 3.6 and 4.1 nm for these aluminum-containing nanoparticles. Similarly, high resolution microscopic analysis of the air dried aluminum-containing silica colloid solution revealed 3.9 ± 1.3 nm sized crystalline Al-rich silica nanoparticles (ASP) with an estimated Al:Si ratio of between 2 and 3 which is close to the range of secondary aluminosilicates such as imogolite. Thus the high-aluminum-affinity silica polymer is a nanoparticle that seeds early aluminosilicate formation through highly competitive binding of Al(III) ions. In niche environments, especially in vivo, this may serve as an alternative mechanism to polyhydroxy Al(III) species binding monomeric silica to form early phase, non-toxic aluminosilicates. PMID:24349573

  8. Source fabrication and lifetime for Li+ ion beams extracted from alumino-silicate sources.

    PubMed

    Roy, Prabir K; Greenway, Wayne G; Kwan, Joe W

    2012-04-01

    A space-charge-limited beam with current densities (J) exceeding 1 mA/cm(2) have been measured from lithium alumino-silicate ion sources at a temperature of ∼1275 °C. At higher extraction voltages, the source appears to become emission limited with J ≥ 1.5 mA/cm(2), and J increases weakly with the applied voltage. A 6.35 mm diameter source with an alumino-silicate coating, ≤0.25 mm thick, has a measured lifetime of ∼40 h at ∼1275 °C, when pulsed at 0.05 Hz and with pulse length of ∼6 μs each. At this rate, the source lifetime was independent of the actual beam charge extracted due to the loss of neutral atoms at high temperature. The source lifetime increases with the amount of alumino-silicate coated on the emitting surface, and may also be further extended if the temperature is reduced between pulses. PMID:22559528

  9. Secondary Ion Mass Spectrometry of Zeolite Materials: Observation of Abundant Aluminosilicate Oligomers Using an Ion Trap

    SciTech Connect

    Groenewold, Gary Steven; Kessinger, Glen Frank; Scott, Jill Rennee; Gianotto, Anita Kay; Appelhans, Anthony David; Delmore, James Edward

    2000-12-01

    Oligomeric oxyanions were observed in the secondary ion mass spectra (SIMS) of zeolite materials. The oxyanions have the general composition AlmSinO2(m+n)H(m-1)- (m + n = 2 to 8) and are termed dehydrates. For a given mass, multiple elemental compositions are possible because (Al + H) is an isovalent and isobaric substitute for Si. Using 18 keV Ga+ as a projectile, oligomer abundances are low relative to the monomers. Oligomer abundance can be increased by using the polyatomic projectile ReO4- (~5 keV). Oligomer abundance can be further increased using an ion trap (IT-) SIMS; in this instrument, long ion lifetimes (tens of ms) and relatively high He pressure result in significant collisional stabilization and increased high-mass abundance. The dehydrates rapidly react with adventitious H2O present in the IT-SIMS to form mono-, di-, and trihydrates. The rapidity of the reaction and comparison to aluminum oxyanion hydration suggest that H2O adds to the aluminosilicate oxyanions in a dissociative fashion, forming covalently bound product ions. In addition to these findings, it was noted that production of abundant oligomeric aluminosilicates could be significantly increased by substituting the countercation (NH4+) with the larger alkali ions Rb+ and Cs+. This constitutes a useful tactic for generating large aluminosilicate oligomers for surface characterization and ion-molecule reactivity studies.

  10. Source fabrication and lifetime for Li{sup +} ion beams extracted from alumino-silicate sources

    SciTech Connect

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.

    2012-04-15

    A space-charge-limited beam with current densities (J) exceeding 1 mA/cm{sup 2} have been measured from lithium alumino-silicate ion sources at a temperature of {approx}1275 deg. C. At higher extraction voltages, the source appears to become emission limited with J{>=} 1.5 mA/cm{sup 2}, and J increases weakly with the applied voltage. A 6.35 mm diameter source with an alumino-silicate coating, {<=}0.25 mm thick, has a measured lifetime of {approx}40 h at {approx}1275 deg. C, when pulsed at 0.05 Hz and with pulse length of {approx}6 {mu}s each. At this rate, the source lifetime was independent of the actual beam charge extracted due to the loss of neutral atoms at high temperature. The source lifetime increases with the amount of alumino-silicate coated on the emitting surface, and may also be further extended if the temperature is reduced between pulses.

  11. Adsorption into mineral mesopores as a stabilization mechanism for organic matter on aluminosilicates

    SciTech Connect

    Mayer, L.M. . Dept. of Oceanography)

    1992-01-01

    Measurements of mineral specific surface area and total organic carbon (TOC) indicate that many marine shelf and estuarine sediments, and aluminosilicate soils, have a TOC content equivalent to a monolayer of organic matter covering all mineral surfaces. Density separations of discrete organic particulates from mineral-associated OC are consistent with a primarily adsorbed nature foremost of TOC. Nitrogen gas adsorption data also suggest extensive organic coatings on the mineral grains. Downcore analyses indicate that sediments with TOC starting in excess of monolayer-equivalent (ME) levels decay with core depth to the ME level and then markedly slow their OC loss rate--i.e., the ME level determines the refractory background concentration of TOC. Pore size distributions of marine sediments, determined by nitrogen adsorption or mercury porosimetry, indicate that most surface area of minerals is to be found in pores of < 10 nm diameter. These observations lead to the hypothesis that organic matter is stabilized on aluminosilicate minerals by adsorption into pores too small to allow entry or functioning of the hydrolytic enzymes responsible for OC degradation. This hypothesis is consistent with, but does not require, humification reactions as necessary for OC stabilization. The ME levels of TOC found in continental platform aluminosilicates hence represent a cap on the amount of organic matter that can be protected in this manner and thus attain a residence time of > 1,000 y. Stabilization of higher levels of TOC, as in acid soils or anoxic sediments, presumably results from protection by different mechanisms.

  12. The effects of intrapleural injections of alumina and aluminosilicate (ceramic) fibres.

    PubMed Central

    Pigott, G. H.; Ishmael, J.

    1992-01-01

    Groups of rats, 24 male and 24 female, approximately 8 weeks old, were dosed by a single intrapleural injection with a saline suspension of refractory alumina fibres (Saffil fibres ICI plc) either as manufactured or after extensive thermal ageing; or one of two aluminosilicate ('ceramic') fibres with different diameter distributions. Similar groups were dosed with a suspension of UICC chrysotile A asbestos or saline solution to serve as positive and negative controls respectively. Rats were maintained to 85% mortality and all decedents and terminal sacrifices were closely examined for the presence of mesothelioma. Malignant mesothelioma was diagnosed in ten rats, seven dosed with asbestos and three dosed with aluminosilicate fibre B. No mesothelioma was detected in any rat dosed with Saffil fibres or aluminosilicate fibre A or in negative controls. The results support the predicted inert nature of Saffil alumina fibres and provide further evidence for the importance of fibre dimension in the induction of mesothelioma. The implication of the results for inhalation exposures is discussed. PMID:1571274

  13. Mesoporous aluminosilicates with ordered hexagonal structure, strong acidity, and extraordinary hydrothermal stability at high temperatures.

    PubMed

    Zhang, Z; Han, Y; Xiao, F S; Qiu, S; Zhu, L; Wang, R; Yu, Y; Zhang, Z; Zou, B; Wang, Y; Sun, H; Zhao, D; Wei, Y

    2001-05-30

    Highly ordered hexagonal mesoporous aluminosilicates (MAS-5) with uniform pore sizes have been successfully synthesized from assembly of preformed aluminosilcate precursors with cetyltrimethylammonium bromide (CTAB) surfactant. The aluminosilicate precursors were obtained by heating, at 100--140 degrees C for 2--10 h, aluminasilica gels at the Al(2)O(3)/SiO(2)/TEAOH/H(2)O molar ratios of 1.0/7.0--350/10.0--33.0/500--2000. Mesoporous MAS-5 shows extraordinary stability both in boiling water (over 300 h) and in steam (800 degrees C for 2 h). Temperature-programmed desorption of ammonia shows that the acidic strength of MAS-5 is much higher than that of MCM-41 and is comparable to that of microporous Beta zeolite. In catalytic cracking of 1,3,5-triisopropylbenzene and alkylation of isobutane with butene, MAS-5 exhibits greater catalytic activity and selectivity, as compared with MCM-41 and HZSM-5. The MAS-5 samples were characterized with infrared, UV--Raman, and NMR spectroscopy and numerous other techniques. The results suggest that MAS-5 consists of both mesopores and micropores and that the pore walls of MAS-5 contain primary and secondary structural building units, similar to those of microporous zeolites. Such unique structural features might be responsible for the observed strong acidity and high thermal stability of the mesoporous aluminosilicates with well-ordered hexagonal symmetry. PMID:11457329

  14. Solubility and solution mechanisms of chlorine in aluminosilicate melts at high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Dalou, C.; Mysen, B. O.

    2012-12-01

    We address the effect of alkalies and aluminum on the solution behavior of Cl by combining solubility measurements of Cl and Raman data of Cl-bearing peralkaline aluminosilicate glasses (quenched melt). Six compositions along the join Na2Si3O7(NS3)-Na2(NaAl)3O7 and six compositions along the join K2Si3O7(KS3)-K2(KAl)3O7 were used. In order to isolate potential effects of Al/(Al+Si) from changes on melt polymerization, Al2O3 was exchanged with SiO2 in a charge-balanced form, NaAlO2 and KaAlO2 thus keeping approximately constant NBO/T (0.65 ± 0.02) for all melts (assuming Al3+ in 4-fold coordination in the melts). Starting materials were doped with 5wt% Cl in the form of PdCl2, which releases Cl2 as its gaseous phase during experiment. Samples were synthetized on piston-cylinder apparatus at 1600°C - 1.5 GPa. At the end of the experiments, Pd forms little spheres (1-2 μm) that for most part dissolves into the capsule. Chlorine oversaturation in the melts is ensured by the observation of bubbles in the quenched samples. The Cl solubility in Na-bearing systems is about twice that of the than in K-bearing system and may, therefore, be negatively correlated with ionic radius of the metal cation.. The solubility also decreases with Al/(Al+Si). In NS3 system, it decreases from 4.01 ± 0.13 wt% of Cl in Al-free systems to 1.87 ± 0.19 wt% of Cl for an Al/Al+Si ratio of 0.34. In KS3 system, this decrease is from 2.23 ± 0.08 wt% of Cl in Al-free systems to 0.62 ± 0.05 wt% of Cl for an Al/Al+Si ratio of 0.36. In Al-free systems, preliminary Raman data show the appearance of a peak around 465cm-1, that we assigned to alkali-Cl bonding. The intensity of this 465cm-1 peak increases with Al content confirming the role of Al in Cl solution mechanism.We also identify the molecular Cl peak at 1540cm-1. The peak can be detected only in Al-bearing melts. The Al substitution for Si results in increased abundance of three-dimensional cages on the melt structure into which molecular

  15. Low sodium level

    MedlinePlus

    Low sodium level is a condition in which the amount of sodium (salt) in the blood is lower ... and this causes many of the symptoms of low sodium. With low sodium level (hyponatremia), the imbalance of ...

  16. Test Your Sodium Smarts

    MedlinePlus

    ... You may be surprised to learn how much sodium is in many foods. Sodium, including sodium chloride ... foods with little or no salt. Test your sodium smarts by answering these 10 questions about which ...

  17. Synthetic and Structural Studies of Mixed Sodium Bis(trimethylsilyl)amide/Sodium Halide Aggregates in the Presence of η(2)-N,N-, η(3)-N,N,N/N,O,N-, and η(4)-N,N,N,N-Donor Ligands.

    PubMed

    Ojeda-Amador, Ana I; Martínez-Martínez, Antonio J; Kennedy, Alan R; O'Hara, Charles T

    2015-10-19

    When n-hexane solutions of an excess of sodium bis(trimethylsilyl)amide (NaHMDS) are combined with cesium halide (halide = Cl, Br, or I) in the presence of the tetradentate donor molecule [tris[2-(dimethylamino)ethyl]amine] (Me6TREN), the isolation and characterization of a series of sodium amide/sodium halide mixed aggregates was forthcoming. Cesium halide was employed because it efficiently reacted with NaHMDS to produce a molecular, soluble source of sodium halide salt (which was subsequently captured by an excess of NaHMDS) via a methathetical reaction. These mixed sodium amide/sodium halide complexes are formally sodium sodiates, are deficient in halide with respect to the amide, and have the general formula [{Na5(μ-HMDS)5(μ5-X)}{Na(Me6TREN)}] [where X = Cl (1), Br (2), or I (3)]. The influence of the donor ligand was studied for the NaI/NaHMDS system, and when n-hexane solutions of this composition were treated with tridentate donors such as N,N,N',N″,N″-pentamethyldiethylenetriamine (PMDETA) or N,N,N',N'-tetramethyldiaminoethyl ether (TMDAE), solvent-separated ion-pair cocomplexes [Na5(μ-HMDS)5(μ5-I)](-)[Na3(μ-HMDS)2(PMDETA)2](+) (4) and [Na5(μ-HMDS)5(μ5-I)](-)[Na(TMDAE)2](+) (5) were isolated. However, upon reaction with bidentate proligands such as the chiral diamine (R,R)-N,N,N',N'-tetramethylcyclohexane-1,2-diamine [(R,R)-TMCDA] or N,N,N',N'-tetramethylethylenediamine (TMEDA), neutral complexes [Na4(μ-HMDS)3(μ4-I)(donor)2] [donor = (R,R)-TMCDA (6) and TMEDA (7)] were produced. To illustrate the generality of the latter reaction with other halides, [Na4(μ-HMDS)3(μ4-Br)(TMEDA)2] (8) was also prepared by employing NaBr in the synthesis instead of NaI. PMID:26417943

  18. Novel, inorganic composites using porous, alkali-activated, aluminosilicate binders

    NASA Astrophysics Data System (ADS)

    Musil, Sean

    Geopolymers are an inorganic polymeric material composed of alumina, silica, and alkali metal oxides. Geopolymers are chemical and fire resistant, can be used as refractory adhesives, and are processed at or near ambient temperature. These properties make geopolymer an attractive choice as a matrix material for elevated temperature composites. This body of research investigated numerous different reinforcement possibilities and variants of geopolymer matrix material and characterized their mechanical performance in tension, flexure and flexural creep. Reinforcements can then be chosen based on the resulting properties to tailor the geopolymer matrix composites to a specific application condition. Geopolymer matrix composites combine the ease of processing of polymer matrix composites with the high temperature capability of ceramic matrix composites. This study incorporated particulate, unidirectional fiber and woven fiber reinforcements. Sodium, potassium, and cesium based geopolymer matrices were evaluated with cesium based geopolymer showing great promise as a high temperature matrix material. It showed the best strength retention at elevated temperature, as well as a very low coefficient of thermal expansion when crystallized into pollucite. These qualities made cesium geopolymer the best choice for creep resistant applications. Cesium geopolymer binders were combined with unidirectional continuous polycrystalline mullite fibers (Nextel(TM) 720) and single crystal mullite fibers, then the matrix was crystallized to form cubic pollucite. Single crystal mullite fibers were obtained by the internal crystallization method and show excellent creep resistance up to 1400°C. High temperature flexural strength and flexural creep resistance of pollucite and polycrystalline/single-crystal fibers was evaluated at 1000-1400°C.

  19. Multinuclear Magnetic Resonance Studies on Aqueous Suspensions of Synthetic Saponites

    PubMed

    Grandjean; Robert

    1997-03-01

    The structure at the liquid/solid interface of synthetic saponites is monitored by NMR methods. These results are compared with data obtained with a natural saponite. The mean orientation of interfacial water molecules is different for synthetic and natural saponites. Interaction of water molecules or counterions with the solid surface depends on the charge layer of the synthetic clays. Water/acetonitrile and sodium/tetrapropylammonium cation competitions have been studied. Significant changes of the orientation of interfacial water molecules and removal of sodium counterions are observed only with the lowest charged saponite. PMID:9245335

  20. Multinuclear magnetic resonance studies on aqueous suspensions of synthetic saponites

    SciTech Connect

    Grandjean, J.; Robert, J.L.

    1997-03-01

    The structure at the liquid/solid interface of synthetic saponites is monitored by NMR methods. These results are compared with data obtained with a natural saponite. The mean orientation of interfacial water molecules is different for synthetic and natural saponites. Interaction of water molecules or counterions with the solid surface depends on the charge layer of the synthetic clays. Water/acetonitrile and sodium/tetrapropylammonium cation competitions have been studied. Significant changes of the orientation of interfacial water molecules and removal of sodium counterions are observed only with the lowest charged saponite. Aqueous suspensions of swelling clays find uses in many industrial applications including drilling fluids, suspending agents, and water treatment.

  1. Low sodium diet (image)

    MedlinePlus

    ... for you. Look for these words on labels: low-sodium, sodium-free, no salt added, sodium-reduced, or ... for you. Look for these words on labels: low-sodium, sodium-free, no salt added, sodium-reduced, or ...

  2. Calculation of the 13C NMR shieldings of the C0 2 complexes of aluminosilicates

    NASA Astrophysics Data System (ADS)

    Tossell, J. A.

    1995-04-01

    13C NMR shieldings have been calculated using the random-phase-approximation, localized-orbital local-origins version of ab initio coupled Hartree-Fuck perturbation theory for CO 2 and and for several complexes formed by the reaction of CO 2 with molecular models for aluminosilicate glasses, H 3TOT'H3 3-n, T,T' = Si,Al. Two isomeric forms of the CO 2-aluminosilicate complexes have been considered: (1) "CO 2-like" complexes, in which the CO 2 group is bound through carbon to a bridging oxygen and (2) "CO 3-like" complexes, in which two oxygens of a central CO 3 group form bridging bonds to the two TH 3 groups. The CO 2-like isomer of CO 2-H 3SiOSiH 3 is quite weakly bonded and its 13C isotropic NMR shielding is almost identical to that in free CO 2. As Si is progressively replaced by Al in the - H terminated aluminosilicate model, the CO 2-like isomers show increasing distortion from the free CO 2 geometry and their 13C NMR shieldings decrease uniformly. The calculated 13C shielding value for H 3AlO(CO 2)AlH 3-2 is only about 6 ppm larger than that calculated for point charge stabilized CO 3-2. However, for a geometry of H 3SiO(CO 2) AlH 3-1, in which the bridging oxygen to C bond length has been artificially increased to that found in the - OH terminated cluster (OH) 3SiO(CO 2)Al(OH) 3-1, the calculated 13C shielding is almost identical to that for free CO 2. The CO 3-like isomers of the CO 2-aluminosili-cate complexes show carbonate like geometries and 13C NMR shieldings about 4-9 ppm larger than those of carbonate for all T,T' pairs. For the Si,Si tetrahedral atom pair the CO 2-like isomer is more stable energetically, while for the Si,Al and Al,Al cases the CO 3-like isomer is more stable. Addition of Na + ions to the CO 3-2 or H 3AlO(CO 2)AlH 3-2 complexes reduces the 13C NMR shieldings by about 10 ppm. Complexation with either Na + or CO 2 also reduces the 29Si NMR shieldings of the aluminosilicate models, while the changes in 27Al shielding with Na + or CO 2

  3. Development of a Composite Non-Electrostatic Surface Complexation Model Describing Plutonium Sorption to Aluminosilicates

    SciTech Connect

    Powell, B A; Kersting, A; Zavarin, M; Zhao, P

    2008-10-28

    Due to their ubiquity in nature and chemical reactivity, aluminosilicate minerals play an important role in retarding actinide subsurface migration. However, very few studies have examined Pu interaction with clay minerals in sufficient detail to produce a credible mechanistic model of its behavior. In this work, Pu(IV) and Pu(V) interactions with silica, gibbsite (Aloxide), and Na-montmorillonite (smectite clay) were examined as a function of time and pH. Sorption of Pu(IV) and Pu(V) to gibbsite and silica increased with pH (4 to 10). The Pu(V) sorption edge shifted to lower pH values over time and approached that of Pu(IV). This behavior is apparently due to surface mediated reduction of Pu(V) to Pu(IV). Surface complexation constants describing Pu(IV)/Pu(V) sorption to aluminol and silanol groups were developed from the silica and gibbsite sorption experiments and applied to the montmorillonite dataset. The model provided an acceptable fit to the montmorillonite sorption data for Pu(V). In order to accurately predict Pu(IV) sorption to montmorillonite, the model required inclusion of ion exchange. The objective of this work is to measure the sorption of Pu(IV) and Pu(V) to silica, gibbsite, and smectite (montmorillonite). Aluminosilicate minerals are ubiquitous at the Nevada National Security Site and improving our understanding of Pu sorption to aluminosilicates (smectite clays in particular) is essential to the accurate prediction of Pu transport rates. These data will improve the mechanistic approach for modeling the hydrologic source term (HST) and provide sorption Kd parameters for use in CAU models. In both alluvium and tuff, aluminosilicates have been found to play a dominant role in the radionuclide retardation because their abundance is typically more than an order of magnitude greater than other potential sorbing minerals such as iron and manganese oxides (e.g. Vaniman et al., 1996). The sorption database used in recent HST models (Carle et al., 2006

  4. Metallic nanoparticles and their medicinal potential. Part II: aluminosilicates, nanobiomagnets, quantum dots and cochleates.

    PubMed

    Loomba, Leena; Scarabelli, Tiziano

    2013-09-01

    Metallic miniaturization techniques have taken metals to nanoscale size where they can display fascinating properties and their potential applications in medicine. In recent years, metal nanoparticles such as aluminium, silicon, iron, cadmium, selenium, indium and calcium, which find their presence in aluminosilicates, nanobiomagnets, quantum dots (Q-dots) and cochleates, have caught attention of medical industries. The increasing impact of metallic nanoparticles in life sciences has significantly advanced the production techniques for these nanoparticles. In this Review, the various methods for the synthesis of nanoparticles are outlined, followed by their physicochemical properties, some recent applications in wound healing, diagnostic imaging, biosensing, assay labeling, antimicrobial activity, cancer therapy and drug delivery are listed, and finally their toxicological impacts are revised. The first half of this article describes the medicinal uses of two noble nanoparticles - gold and silver. This Review provides further information on the ability of aluminum, silicon, iron, selenium, indium, calcium and zinc to be used as nanoparticles in biomedical sciences. Aluminosilicates find their utility in wound healing and antibacterial growth. Iron-oxide nanoparticles enhance the properties of MRI contrast agents and are also used as biomagnets. Cadmium, selenium, tellurium and indium form the core nanostructures of tiny Q-dots used in cellular assay labeling, high-resolution cell imaging and biosensing. Cochleates have the bivalent nano ions calcium, magnesium or zinc imbedded in their structures and are considered to be highly effective agents for drug and gene delivery. The aluminosilicates, nanobiomagnets, Q-dots and cochleates are discussed in the light of their properties, synthesis and utility. PMID:24024515

  5. Contribution of aluminas and aluminosilicates to the formation of PCDD/Fs on fly ashes.

    PubMed

    Potter, Phillip M; Dellinger, Barry; Lomnicki, Slawomir M

    2016-02-01

    Chlorinated aromatics undergo surface-mediated reactions with metal oxides to form Environmentally Persistent Free Radicals (EPFRs) which can further react to produce polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Previous work using laboratory-made fly ash surrogates composed of transition metal oxides deposited on silica powder has confirmed their ability to mimic fly ash in the production of PCDD/Fs. However, little is known about the propensity of aluminas and aluminosilicates, other components of fly ash, to form PCDD/Fs. A fly ash sample containing both alumina and mullite, an aluminosilicate, was tested for PCDD/F formation ability and compared to PCDD/F yields from the thermal degradation of 2-monochlorophenol (2-MCP) precursor over γ-alumina, α-alumina, and mullite. A packed-bed flow reactor was used to investigate the thermal degradation of 2-MCP over the various catalysts at 200-600 °C. Fly ash gave similar PCDD/F yields to surrogates made with similar transition metal content. γ-alumina, which is thermodynamically unfavorable, was very catalytically active and gave low PCDD/F yields despite a high destruction of 2-MCP. Mullite and α-alumina, the thermodynamically favorable form of alumina, yielded higher concentrations of dioxins and products with a higher degree of chlorine substitution than γ-alumina. The data suggest that certain aluminas and aluminosilicates, commonly found in fly ash, are active catalytic surfaces in the formation of PCDD/Fs in the post-flame cool zones of combustion systems and should be considered as additional catalytic surfaces active in the process. PMID:26615490

  6. In vitro osteogenic/dentinogenic potential of an experimental calcium aluminosilicate cement

    PubMed Central

    Eid, Ashraf A.; Niu, Li-na; Primus, Carolyn M.; Opperman, Lynne A.; Watanabe, Ikuya; Pashley, David H.; Tay, Franklin R.

    2013-01-01

    Introduction Calcium aluminosilicate cements are fast-setting, acid-resistant, bioactive cements that may be used as root-repair materials. This study examined the osteogenic/dentinogenic potential of an experimental calcium aluminosilicate cement (Quick-Set) using a murine odontoblast-like cell model. Methods Quick-Set and white ProRoot MTA (WMTA) were mixed with the proprietary gel or deionized water, allowed to set completely in 100% relative humidity and aged in complete growth medium for 2 weeks until rendered non-cytotoxic. Similarly-aged Teflon discs were used as negative control. The MDPC-23 cell-line was used for evaluating changes in mRNA expressions of genes associated with osteogenic/dentinogenic differentiation and mineralization (qRT-PCR) alkaline phosphatase enzyme production and extracellular matrix mineralization (Alizarin red-S staining). Results After MDPC-23 cells were incubated with the materials in osteogenic differentiation medium for 1 week, both cements showed upregulation in ALP and DSPP expression. Fold increases in these two genes were not significantly different between Quick-Set and WMTA. Both cements showed no statistically significant upregulation/downregulation in RUNX2, OCN, BSP and DMP1 gene expression compared with Teflon. Alkaline phosphatase activity of cells cultured on Quick-Set and WMTA were not significantly different at 1 week or 2 weeks, but were significantly higher (p<0.05) than Teflon in both weeks. Both cements showed significantly higher calcium deposition compared with Teflon after 3 weeks of incubation in mineralizing medium (p<0.001). Differences between Quick-Set and WMTA were not statistically significant. Conclusions The experimental calcium aluminosilicate cement exhibits similar osteogenic/dentinogenic properties to WMTA and may be a potential substitute for commercially-available tricalcium silicate cements. PMID:23953291

  7. Non-bridging Oxygens in Calcium Aluminosilicate Glass From Per-calcic to Peraluminous Compositions

    NASA Astrophysics Data System (ADS)

    Thompson, L.; Stebbins, J.

    2008-12-01

    The role of non-bridging oxygen (NBO) and its effects on the thermodynamic and transport properties of aluminosilicate melts are not fully understood, although this species clearly must have a major influence on configurational entropy, viscosity, etc. Its existence along metaluminous joins in alkali- and alkaline-earth aluminosilicates was first postulated from viscosity measurements (Toplis et al., 1996, 2004) and then directly observed in several metaluminous calcium aluminosilicates by 17O nuclear magnetic resonance (NMR) spectroscopy. Much of the recent work has concentrated on glasses with an M+n/(M+nAl) ratio greater than or equal to 0.5 (metaluminous to peralkaline or per-alkaline earth); however, the observed viscosity maxima in several ternary systems occur when this ratio is less than 0.5 (peraluminous). Using NMR spectroscopy, this study investigates the effects of the Ca/Al ratio on the amount of NBO present in calcium aluminosilicate (CAS) glasses. 17O MAS NMR spectra of glasses with 60 mol% SiO2 show a decrease in NBO as the ratio R=Ca+2/(Ca+2Al) decreases, from 6.9% at R=0.56 to 1.0% at R=0.44. Measurable amounts of NBO thus persist well into the peraluminous region of the CAS system, but the species becomes undetectable (<0.5%) when R reaches 0.38 and 0.33. 27Al MAS NMR spectra of these glasses show an increase in the amount of five-coordinated aluminum as compositions become more peraluminous, as is well-known from previous studies (Neuville et al. 2006). Comparison with published viscosity measurements measured at both higher and lower mol % SiO2 (Toplis et al. 2004) suggests that the viscosity maximum does not correspond exactly with the disappearance of NBO from the glasses, but effects of temperature on speciation will need to be taken into account to accurately link glass structure with melt properties: recent work has shown, for example, that NBO content increases with temperature in CaAl2Si2O8 melt (Stebbins et al. 2008).

  8. Optical absorption and luminescence study of cobalt-doped magnesium aluminosilicate glass ceramics

    NASA Astrophysics Data System (ADS)

    Malyarevich, A. M.; Denisov, I. A.; Yumashev, K. V.; Dymshits, O. S.; Zhilin, A. A.

    2002-08-01

    Linear and nonlinear optical properties of cobalt-doped magnesium aluminosilicate transparent glass ceramics that were prepared under different conditions have been studied. It has been shown that absorption and luminescence spectra and absorption bleaching of these glass ceramics are defined mainly by tetrahedrally coordinated Co 2+ ions located in magnesium aluminum spinel nanocrystals. The lifetimes of the 4 T 1 ( 4 F) and 4 T 2 ( 4 F) excited states of the tetrahedral Co 2+ ions were found to be in the ranges 2540 and 120450 ns, respectively, depending on the Co concentration. 2002 Optical Society of America

  9. Facile Fabrication of Uniform Polyaniline Nanotubes with Tubular Aluminosilicates as Templates

    NASA Astrophysics Data System (ADS)

    Zhang, Long; Liu, Peng

    2008-08-01

    The uniform polyaniline (PANI) nanotubes, with inner diameter, outer diameter, and tubular thickness of 40, 60, and 10 nm, respectively, were prepared successfully by using natural tubular aluminosilicates as templates. The halloysite nanotubes were coated with PANI via the in situ chemical oxidation polymerization. Then the templates were etched with HCl/HF solution. The PANI nanotubes were characterized using FTIR, X-ray diffraction, and transmission electron microscopy. The conductivity of the PANI nanotubes was found to be 1.752 × 10-5 (Ω·cm)-1.

  10. DuraLith Alkali-Aluminosilicate Geopolymer Waste Form Testing for Hanford Secondary Waste

    SciTech Connect

    Gong, W. L.; Lutz, Werner; Pegg, Ian L.

    2011-07-21

    The primary objective of the work reported here was to develop additional information regarding the DuraLith alkali aluminosilicate geopolymer as a waste form for liquid secondary waste to support selection of a final waste form for the Hanford Tank Waste Treatment and Immobilization Plant secondary liquid wastes to be disposed in the Integrated Disposal Facility on the Hanford Site. Testing focused on optimizing waste loading, improving waste form performance, and evaluating the robustness of the waste form with respect to waste variability.

  11. Evidence of two erbium sites in standard aluminosilicate glass for EDFA.

    PubMed

    Peretti, R; Jurdyc, A M; Jacquier, B; Burov, E; Pastouret, A

    2010-09-27

    Site distributions of Er(3+)-doped aluminosilicate preforms of standard EDFA were studied by the low temperature Resonant Fluorescence Line Narrowing (RFLN) spectroscopy. Two erbium concentration samples with the same glass base were investigated. At very low erbium concentration, two classes of sites were identified, related to the number of AlO(6) octahedral linked by two oxygen edge-sharing to Er(3+) in the coordination sphere. As erbium concentration is increased, the high AlO(6) coordinated class of sites is smeared out by the optical response of the one AlO(6) coordinated class of sites. PMID:20940961

  12. Regulatory risk assessment approaches for synthetic mineral fibres.

    PubMed

    Harrison, Paul; Holmes, Philip; Bevan, Ruth; Kamps, Klaus; Levy, Leonard; Greim, Helmut

    2015-10-01

    Exposure to synthetic mineral fibres (SMF) may occur in a number of workplace scenarios. To protect worker health, a number of different organisations worldwide have assessed the health risk of these materials and established workplace exposure limits. This paper outlines the basic principles of risk assessment and the scientific methods used to derive valid (justifiable) occupational exposure limits (OELs) and goes on to show how, for SMF, and particularly for refractory ceramic fibre (otherwise known as aluminosilicate wool, RCF/ASW), the methods used and the associated outcomes differ widely. It is argued that the resulting differences in established OELs prevent consistent and appropriate risk management of SMF worldwide, and that development of a transparent and harmonised approach to fibre risk assessment and limit-setting is required. PMID:26253001

  13. Low sodium level

    MedlinePlus

    Low sodium level is a condition in which the amount of sodium (salt) in the blood is lower than normal. The ... Sodium is found mostly in the body fluids outside the cells. It is very important for maintaining ...

  14. Ordered hexagonal mesoporous aluminosilicates with low Si/Al ratio: synthesis, characterization, and catalytic application.

    PubMed

    Liu, Aifeng; Che, Hongwei; Liu, Chuanzhi; Fu, Quanrong; Jiang, Ruijiao; Wang, Cheng; Wang, Liang

    2014-06-01

    Ordered hexagonal mesoporous aluminosilicates with lower Si/Al ratio below 5 have been successfully synthesized via the co-assembly of preformed aluminosilicate precursors with Gemini surfactant [C12H25N+(CH3)2(CH2)6N+(CH3)2C12H25] x 2Br(-) as the template. Powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, N2 adsorption-desorption isotherm measurements, Fourier transform infrared spectroscopy, 27Al nuclear magnetic resonance, thermogravimetric analysis, and temperature-programmed desorption of cyclohexylamine are employed to characterize the resulting samples. The phenol alkylation reaction is carried out to evaluate their catalytic performances. These studies indicate that the sample with a low Si/Al ratio of 3 still retains a highly ordered hexagonal mesoporous structure. And it also possesses the highest acidity of 0.96 mmol among the samples with lower Si/Al ratios below 5 due to its higher specific surface area together with more content of tetrahedrally coordinated Al in the framework. The catalytic tests confirm that the acidity of the samples plays a key role in determining their catalytic performances. PMID:24738433

  15. Water solubility in calcium aluminosilicate glasses investigated by first principles techniques

    SciTech Connect

    Bouyer, Frederic; Geneste, Gregory; Ispas, Simona; Kob, Walter; Ganster, Patrick

    2010-12-15

    First-principles techniques have been employed to study the reactivity of water into a calcium aluminosilicate glass. In addition to the well known hydrolysis reactions Si-O-Si+H{sub 2}O{yields}Si-OH+Si-OH and Si-O-Al+H{sub 2}O{yields}Si-OH+Al-OH, a peculiar mechanism is found, leading to the formation of an AlO{sub 3}-H{sub 2}O entity and the breaking of Al-O-Si bond. In the glass bulk, most of the hydrolysis reactions are endothermic. Only a few regular sites are found reactive (i.e. in association with an exothermic reaction), and in that case, the hydrolysis reaction leads to a decrease of the local disorder in the amorphous vitreous network. Afterwards, we suggest that ionic charge compensators transform into network modifiers when hydrolysis occurs, according to a global process firstly suggested by Burnham in 1975. Our theoretical computations provide a more general model of the first hydrolysis steps that could help to understand experimental data and water speciation in glasses. -- Graphical Abstract: Reactivity within glass bulk: structures obtained after hydrolyses reactions (endothermic and exothermic processes) and mechanisms involving Si-OH, Al-OH, Si-OH-Al groups within aluminosilicates glasses (through ab initio molecular dynamics): formation of the Si-OH-Al entity coupled with an H exchange-Frederic Bouyer and Gregory Geneste. Display Omitted

  16. The plumber's nightmare: a new morphology in block copolymer-ceramic nanocomposites and mesoporous aluminosilicates.

    PubMed

    Finnefrock, Adam C; Ulrich, Ralph; Toombes, Gilman E S; Gruner, Sol M; Wiesner, Ulrich

    2003-10-29

    A novel cubic bicontinuous morphology is found in polymer-ceramic nanocomposites and mesoporous aluminosilicates that are derived by an amphiphilic diblock copolymer, poly(isoprene-b-ethylene oxide) (PI-b-PEO), used as a structure-directing agent for an inorganic aluminosilicate. Small-angle X-ray scattering (SAXS) was employed to unambiguously identify the Im(-)3m crystallographic symmetry of the materials by fitting individual Bragg peak positions in the two-dimensional X-ray images. Structure factor calculations, in conjunction with results from transmission electron microscopy, were used to narrow the range of possible structures consistent with the symmetry and showed the plumber's nightmare morphology to be consistent with the data. The samples are made by deposition onto a substrate that imposes a strain field, generating a lattice distortion. This distortion is quantitatively analyzed and shown to have resulted in shrinkage of the crystallites by approximately one-third in a direction perpendicular to the substrate, in both as-made composites and calcined ceramic materials. Finally, the observation of the bicontinuous block-copolymer-derived hybrid morphology is discussed in the context of a pseudo-ternary morphology diagram and compared to existing studies of ternary phase diagrams of amphiphiles in a mixture of two solvents. The calcined mesoporous materials have potential applications in the fields of catalysis, separation technology, and microelectronics. PMID:14570481

  17. A HIGH CURRENT DENSITY LI+ ALUMINO-SILICATE ION SOURCE FOR TARGET HEATING EXPERIMENTS

    SciTech Connect

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.; Seidl, Peter A.; Waldron, William L.

    2011-03-23

    The NDCX-II accelerator for target heating experiments has been designed to use a large diameter ({approx_equal} 10.9 cm) Li{sup +} doped alumino-silicate source with a pulse duration of 0.5 {micro}s, and beam current of {approx_equal} 93 mA. Characterization of a prototype lithium alumino-silicate sources is presented. Using 6.35mm diameter prototype emitters (coated on a {approx_equal} 75% porous tungsten substrate), at a temperature of {approx_equal} 1275 C, a space-charge limited Li{sup +} beam current density of {approx_equal} 1 mA/cm{sup 2} was measured. At higher extraction voltage, the source is emission limited at around {approx_equal} 1.5 mA/cm{sup 2}, weakly dependent on the applied voltage. The lifetime of the ion source is {approx_equal} 50 hours while pulsing the extraction voltage at 2 to 3 times per minute. Measurements show that the life time of the ion source does not depend only on beam current extraction, and lithium loss may be dominated by neutral loss or by evaporation. The life time of a source is around {ge} 10 hours in a DC mode extraction, and the extracted charge is {approx_equal} 75% of the available Li in the sample. It is inferred that pulsed heating may increase the life time of a source.

  18. Electromagnetic and Mechanical Properties of Silica-Aluminosilicates Plasma Sprayed Composite Coatings

    NASA Astrophysics Data System (ADS)

    Cipri, F.; Bartuli, C.; Valente, T.; Casadei, F.

    2007-12-01

    The physico-chemical and thermo-mechanical properties of aluminosilicate ceramics (high-melting point, low thermal expansion coefficient, excellent thermal shock resistance, low-density and good corrosion resistance) make this class of materials a good option for high-temperature structural applications. Al2O3-SiO2 compounds show an excellent refractory behavior allowing a wide use as wear-resistant thermal barrier coatings, in metallurgical and glass plants and in high temperature heat exchangers. Moreover, the low values of thermal expansion coefficient and of complex permittivity allow to extend the use of this ceramic for microelectronic devices, radome for antennas and electromagnetic windows for microwaves and infrared. The present article presents the results of an extensive experimental activity carried out to produce thick aluminosilicate coatings by plasma-spray technique. The APS deposition parameters were optimized on the basis of a surface response approach, as specified by design of experiments (DoE) methodologies. Samples were tested for phase composition, total porosity, microstructure, microhardness, deposition efficiency, fracture toughness, and modulus of rupture. Finally, coatings were characterized for their particularly interesting electromagnetic properties: complex permittivity was measured at microwave frequency using a network analyzer with wave guide.

  19. Effect of temperature and aluminium on calcium (alumino)silicate hydrate chemistry under equilibrium conditions

    SciTech Connect

    Myers, Rupert J.; L'Hôpital, Emilie; Provis, John L.; Lothenbach, Barbara

    2015-02-15

    There exists limited information regarding the effect of temperature on the structure and solubility of calcium aluminosilicate hydrate (C–A–S–H). Here, calcium (alumino)silicate hydrate (C–(A–)S–H) is synthesised at Ca/Si = 1, Al/Si ≤ 0.15 and equilibrated at 7–80 °C. These systems increase in phase-purity, long-range order, and degree of polymerisation of C–(A–)S–H chains at higher temperatures; the most highly polymerised, crystalline and cross-linked C–(A–)S–H product is formed at Al/Si = 0.1 and 80 °C. Solubility products for C–(A–)S–H were calculated via determination of the solid-phase compositions and measurements of the concentrations of dissolved species in contact with the solid products, and show that the solubilities of C–(A–)S–H change slightly, within the experimental uncertainty, as a function of Al/Si ratio and temperature between 7 °C and 80 °C. These results are important in the development of thermodynamic models for C–(A–)S–H to enable accurate thermodynamic modelling of cement-based materials.

  20. The effects of surface modification on the speciation of metal ions intercalated into aluminosilicates

    SciTech Connect

    Wasserman, S.R.; Giaquinta, D.M.; Yuchs, S.E.; Soderholm, L.

    1996-12-31

    Microporous aluminosilicates, including clay minerals and zeolites, are ion-exchange materials. In their most common forms, they have the ability to incorporate cationic species within their matrices. Because of this property, microporous aluminosilicates have been proposed as storage media for hazardous waste. In this paper the authors use X-ray absorption spectroscopy (XAS) to examine the structure of cations held within smectite clay minerals and to determine how modification of the surface of the clay using an organic monolayer affects the coordination of the stored cation. The effects of hydrothermal and thermal processing on the coordination of the ions contained within these systems are also investigated. The presence of the monolayer changes the surface of the clay from hydrophilic to hydrophobic. It inhibits the interlayer ions from exchanging freely into environmental water and reduces the leach rate of cations out of the clay by approximately a factor of 20. Significant changes are observed when these coated samples are treated under hydrothermal and thermal conditions. Reductions of uranium (VI), in the form of uranyl, and cupric ions occur. In addition, the uranium aggregates, forming small particles that appear similar to UO{sub 2}. Comparable conglomeration occurs with lead cations and with the reduced copper species.

  1. Aqueous dissolution, solubilities and thermodynamic stabilities of common aluminosilicate clay minerals: Kaolinite and smectites

    USGS Publications Warehouse

    May, Howard M.; Klnniburgh, D.G.; Helmke, P.A.; Jackson, M.L.

    1986-01-01

    Determinations of the aqueous solubilities of kaolinite at pH 4, and of five smectite minerals in suspensions set between pH 5 and 8, were undertaken with mineral suspensions adjusted to approach equilibrium from over- and undersaturation. After 1,237 days, Dry Branch, Georgia kaolinite suspensions attained equilibrium solubility with respect to the kaolinite, for which Keq = (2.72 ?? 0.35) ?? 107. The experimentally determined Gibbs free energy of formation (??Gf,2980) for the kaolinite is -3,789.51 ?? 6.60 kj mol-1. Equilibrium solubilities could not be determined for the smectites because the composition of the solution phase in the smectite suspensions appeared to be controlled by the formation of gibbsite or amorphous aluminum hydroxide and not by the smectites, preventing attempts to determine valid ??Gf0 values for these complex aluminosilicate clay minerals. Reported solubility-based ??Gf0 determinations for smectites and other variable composition aluminosilicate clay minerals are shown to be invalid because of experimental deficiencies and of conceptual flaws arising from the nature of the minerals themselves. Because of the variable composition of smectites and similar minerals, it is concluded that reliable equilibrium solubilities and solubility-derived ??Gf0 values can neither be rigorously determined by conventional experimental procedures, nor applied in equilibriabased models of smectite-water interactions. ?? 1986.

  2. Development of a New Ferrous Aluminosilicate Refractory Material for Investment Casting of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Yuan, Chen; Jones, Sam; Blackburn, Stuart

    2012-12-01

    Investment casting is a time-consuming, labour intensive process, which produces complex, high value-added components for a variety of specialised industries. Current environmental and economic pressures have resulted in a need for the industry to improve current casting quality, reduce manufacturing costs and explore new markets for the process. Alumino-silicate based refractories are commonly used as both filler and stucco materials for ceramic shell production. A new ceramic material, norite, is now being produced based on ferrous aluminosilicate chemistry, having many potential advantages when used for the production of shell molds for casting aluminum alloy. This paper details the results of a direct comparison made between the properties of a ceramic shell system produced with norite refractories and a typical standard refractory shell system commonly used in casting industry. A range of mechanical and physical properties of the systems was measured, and a full-scale industrial casting trial was also carried out. The unique properties of the norite shell system make it a promising alternative for casting aluminum based alloys in the investment foundry.

  3. Investigating the Heating of a Potassium-Doped Aluminosilicate Ion Source Using a 1 Micron Laser

    SciTech Connect

    Schmitt, R C; Meier, W R; Kwan, J W; Abbott, R P; Latkowski, J F

    2004-12-14

    The heavy ion fusion (HIF) program is interested in developing a high brightness ion source for high energy density physics (HEDP) experiments. One possible approach to obtaining higher brightness may be to raise the surface temperature of the ion source just prior to extraction. The current ion source material being studied is a layer of potassium-doped aluminosilicate bonded to a tungsten substrate. It is speculated that if the surface temperature of the source is raised above 1200 C (from a steady-state temperature of 900 C) for time periods on the order of 100's of nanoseconds, current densities of greater than 100 mA/cm{sup 2} of ions may be achievable. Typical aluminosilicate sources produce ion current densities (either K+ or Na+ ions) of {approx}10 mA/cm{sup 2} (at 1100 C). A number of heating methods might be possible, including lasers, diode arrays, and flash lamps. Here we assume laser heating. In this preliminary study, we used the LLNL RadHeat code to model the time-temperature history of the surface when hit by laser pulses and illustrate how RadHeat can be used to optimize the surface temperature response. Also of interest is the temperature history of the interface temperature between the ceramic and the metal layers. This is also investigated.

  4. Potentiated clinoptilolite: artificially enhanced aluminosilicate reduces symptoms associated with endoscopically negative gastroesophageal reflux disease and nonsteroidal anti-inflammatory drug induced gastritis

    PubMed Central

    Potgieter, Wilna; Samuels, Caroline Selma; Snyman, Jacques Renè

    2014-01-01

    Purpose The cation exchanger, a potentiated clinoptilolite (Absorbatox™ 2.4D), is a synthetically enhanced aluminosilicate. The aim of this study was to evaluate the possible benefits of a potentiated clinoptilolite as a gastroprotective agent in reducing the severity of clinical symptoms and signs associated with 1) endoscopically negative gastroesophageal reflux disease (ENGORD) and 2) nonsteroidal anti-inflammatory drug (NSAID) medication. Methods and patients Two randomized, double-blind, placebo-controlled, pilot studies, the ENGORD and NSAID studies, were conducted. After initial negative gastroscopy, a total of 25 patients suffering from ENGORD were randomized to receive either placebo capsules or 750 mg Absorbatox twice daily for 14 days. The NSAID study recruited 23 healthy patients who received orally either 1,500 mg Absorbatox or placebo three times daily, plus 500 mg naproxen twice daily. Patients underwent gastroscopic evaluation of their stomach linings prior to and on day 14 of the study. Gastric biopsies were obtained and evaluated via the upgraded Sydney system, whereas visible gastric events and status of the gastric mucosa were evaluated via a 0–3 rating scale. During both studies, patients recorded gastric symptoms in a daily symptom diary. Results In the ENGORD study, patients who received the potentiated clinoptilolite reported a significant reduction (P≤0.05) in severity of symptoms including reduction in heartburn (44%), discomfort (54%), and pain (56%). Symptom-free days improved by 41% compared to the group who received placebo (not significant). This was over and above the benefits seen with the proton pump inhibitor. In the NSAID study, the reduction in gastric symptom severity was echoed in the group who received the potentiated clinoptilolite. Treatment with the potentiated clinoptilolite resulted in significant prevention (P≤0.05) of mucosal erosion severity as graded by the gastroenterologist. Conclusion Absorbatox is a

  5. [From synthetic biology to synthetic humankind].

    PubMed

    Nouvel, Pascal

    2015-01-01

    In this paper, we propose an historical survey of the expression "synthetic biology" in order to identify its main philosophical components. The result of the analysis is then used to investigate the meaning of the notion of "synthetic man". It is shown that both notions share a common philosophical background that can be summed up by the short but meaningful assertion: "biology is technology". The analysis allows us to distinguish two notions that are often confused in transhumanist literature: the notion of synthetic man and the notion of renewed man. The consequences of this crucial distinction are discussed. PMID:26238764

  6. Diclofenac sodium.

    PubMed

    Small, R E

    1989-08-01

    The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, and dosage of diclofenac sodium are reviewed. Diclofenac, the first nonsteroidal anti-inflammatory agent (NSAID) to be approved that is a phenylacetic acid derivative, competes with arachidonic acid for binding to cyclo-oxygenase, resulting in decreased formation of prostaglandins. The drug has both analgesic and antipyretic activities. Diclofenac is efficiently absorbed from the gastrointestinal tract; peak plasma concentrations occur 1.5 to 2.0 hours after ingestion in fasting subjects. Even though diclofenac has a relatively short elimination half-life in plasma (1.5 hours), it persists in synovial fluid. The drug is metabolized in the liver and is eliminated by urinary and biliary excretion. In clinical trials, diclofenac was as effective as aspirin, diflunisal, indomethacin, sulindac, ibuprofen, ketoprofen, and naproxen in improving function and reducing pain in patients with rheumatoid arthritis. For treatment of osteoarthritis, diclofenac was equivalent in efficacy to aspirin, diflunisal, indomethacin, sulindac, ibuprofen, ketoprofen, naproxen, flurbiprofen, mefenamic acid, and piroxicam. Diclofenac was as effective as indomethacin or sulindac in treating ankylosing spondylitis. The most frequent adverse effects reported for diclofenac were gastrointestinal, but these effects were fewer and less serious than occurred with aspirin or indomethacin; in addition, diclofenac caused fewer central nervous system reactions than indomethacin. Diclofenac is administered in divided doses with meals. The recommended total daily dosage is 100 to 150 mg (osteoarthritis and ankylosing spondylitis) or 150 to 200 mg (rheumatoid arthritis). Diclofenac is effective, but no more so than other NSAIDs. It is structurally distinct and offers another choice in the treatment of rheumatological conditions. PMID:2670397

  7. Sodium blood test

    MedlinePlus

    ... foods. The most common form of sodium is sodium chloride, which is table salt. This test is usually done as part of an electrolyte or basic metabolic panel blood test . Your blood sodium level represents a balance between the sodium and ...

  8. Preparation and characterization of cesium-137 aluminosilicate pellets for radioactive source applications

    SciTech Connect

    Schultz, F.J.; Tompkins, J.A.; Haff, K.W.; Case, F.N.

    1981-07-01

    Twenty-seven fully loaded /sup 137/Cs aluminosilicate pellets were fabricated in a hot cell by the vacuum hot pressing of a cesium carbonate/montmorillonite clay mixture at 1500/sup 0/C and 570 psig. Four pellets were selected for characterization studies which included calorimetric measurements, metallography, scanning electron microscope and electron backscattering (SEM-BSE), electron microprobe, x-ray diffraction, and cesium ion leachability measurements. Each test pellet contained 437 to 450 curies of /sup 137/Cs as determined by calorimetric measurements. Metallographic examinations revealed a two-phase system: a primary, granular, gray matrix phase containing large and small pores and small pore agglomerations, and a secondary fused phase interspersed throughout the gray matrix. SEM-BSE analyses showed that cesium and silicon were uniformly distributed throughout both phases of the pellet. This indicated that the cesium-silicon-clay reaction went to completion. Aluminum homogeneity was unconfirmed due to the high background noise associated with the inherent radioactivity of the test specimens. X-ray diffraction analyses of both radioactive and non-radioactive aluminosilicate pellets confirmed the crystal lattice structure to be pollucite. Cesium ion quasistatic leachability measurements determined the leach rates of fully loaded /sup 137/Cs sectioned pollucite pellets to date to be 4.61 to 34.4 x 10/sup -10/ kg m/sup -2/s/sup -1/, while static leach tests performed on unsectioned fully loaded pellets showed the leach rates of the cesium ion to date to be 2.25 to 3.41 x 10/sup -12/ kg m/sup -2/s/sup -1/. The cesium ion diffusion coefficients through the pollucite pellet were calculated using Fick's first and second laws of diffusion. The diffusion coefficients calculated for three tracer level /sup 137/Cs aluminosilicate pellets were 1.29 x 10/sup -16/m/sup 2/s/sup -1/, 6.88 x 10/sup -17/m/sup 2/s/sup -1/, and 1.35 x 10/sup -17/m/sup 2/s/sup -1/, respectively.

  9. The Valence State of Silicon and Redox Dynamics in Aluminosilicate Melts

    NASA Astrophysics Data System (ADS)

    Cooper, R. F.; Pettersen, C.; Everman, R. L.

    2005-12-01

    Physicists have long been aware of the many valence states of Si and the roles these play in the kinetics of thermal oxidation of Si single crystals and the molecular structure of the amorphous oxide film (e.g., Borman et al., 1991). Similarly, the dynamics of oxidation and of vaporization of SiC are also affected by the presence of Si2+ in the amorphous silica surface film (e.g., Dunham et al., 1998; Mendybaev et al., 2002). Nevertheless, Si2+,4+ heterovalency is little considered in redox studies of silicate melts as reported in the petrology literature. We have performed experiments in which a liquid bronze (Cu,Sn) alloy was reacted with (1) a magnesium aluminosilicate melt and (2) a Zn2+-doped magnesium aluminosilicate melt, all done at a low oxygen fugacity (sufficient to keep the metal alloy from oxidizing in reaction with the gas environment). The driving potential for metal melt-silicate melt reaction has two components: (a) reduction of the silicate melt and oxidation of the metal alloy; (b) formation of a homogeneous silicate solution that incorporates ionic Cu and Sn. The reaction morphologies present compelling evidence that Si4+ in the silicate melt is reduced in part to Si2+, initially so as to incorporate Cu+,2+ into the melt; as the reaction proceeds, however, the Si2+ mobility becomes important in charge-compensation of the "inward" flux of Sn2+. Addition of Zn2+ to the starting silicate melt forces a spatially periodic variation in the silicate melt structure (as suggested by the chemistry) as the reaction proceeds. In separate experiments, reduction of an FeO-bearing calcium-magnesium aluminosilicate melt in a CO-rich environment creates a reaction morphology suggestive of reduction of Si4+ to facilitate the incorporation of carbonate ions into the melt. These experiments are perhaps exotic; nevertheless, they provoke the consideration of the potential role(s) played by silicon valence in any "self-buffering" process associated with the evolution

  10. Influence of aluminum speciation on the stability of aluminosilicate glasses against crystallization

    NASA Astrophysics Data System (ADS)

    Zheng, Qiuju; Smedskjaer, Morten M.; Youngman, Randall E.; Potuzak, Marcel; Mauro, John C.; Yue, Yuanzheng

    2012-07-01

    In this letter, we investigate the correlation between glass microstructure and glass stability (GS) in soda lime aluminosilicates. We find a loss of GS (i.e., an onset of crystallization) in the glasses above a critical concentration of Al2O3 when heating at the standard rate of 20 K/min. This loss in GS may be attributed to formation of five-fold coordinated Al species when [Al2O3]/[Na2O] > 1. The primary crystalline phase is identified as nepheline, in which Al exists in four-fold coordination. This implies that the five-fold coordinated Al is energetically less stable compared to Al in a tetrahedral environment.

  11. Mesoporous nickel-aluminosilicate nanocomposite: a solid acid catalyst for ether synthesis.

    PubMed

    Neelakandeswari, N; Karvembu, R; Dharmaraj, N

    2013-04-01

    Mesoporous nickel aluminosilicate, a solid acid catalyst prepared by sol-gel technique was utilized as a heterogeneous catalyst for the synthesis of symmetrical ethers by dehydro-condensation of alcohols. The prepared catalysts were characterized by Fourier-transform infra red spectroscopy (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), N2 adsorption-desorption analysis, temperature programmed desorption of ammonia (TPD) and X-ray photoelectron spectroscopic techniques. The presence of the catalyst assisted the etherification reaction in 30 minutes. Ethers formed in these reactions were quantified by gas chromatography (GC) and the identities of few of them were confirmed by nuclear magnetic resonance spectral data (NMR). PMID:23763171

  12. Effect of additions of aluminosilicate and silicate materials on the softening temperature of chromite ore

    NASA Astrophysics Data System (ADS)

    Zhdanov, A. V.; Nurmaganbetova, B. N.; Pavlov, V. A.

    2015-07-01

    The temperatures of the beginning and end of softening and the temperature range of softening of the fines of the rich chromite ore of the Donskoy Ore Mining & Processing Plant in Kazakhstan are experimentally determined. The following natural and technical silica-containing materials, which are considered as fluxing additions to decrease the melting temperature of the chromite ore, are investigated: aluminosilicate clays, microsilica, and quartzite of various fractions. The effect of additions of the natural and technical silica-containing materials on the temperatures of the beginning and end of softening and the temperature range of softening of the chromite ore of DODPE is analyzed. The influences of various materials and their fraction compositions on the temperature of softening of the chromite ores are compared.

  13. Chemical durability of soda-lime-aluminosilicate glass for radioactive waste vitrification

    SciTech Connect

    Eppler, F.H.; Yim, M.S.

    1998-09-01

    Vitrification has been identified as one of the most viable waste treatment alternatives for nuclear waste disposal. Currently, the most popular glass compositions being selected for vitrification are the borosilicate family of glasses. Another popular type that has been around in glass industry is the soda-lime-silicate variety, which has often been characterized as the least durable and a poor candidate for radioactive waste vitrification. By replacing the boron constituent with a cheaper substitute, such as silica, the cost of vitrification processing can be reduced. At the same time, addition of network intermediates such as Al{sub 2}O{sub 3} to the glass composition increases the environmental durability of the glass. The objective of this study is to examine the ability of the soda-lime-aluminosilicate glass as an alternative vitrification tool for the disposal of radioactive waste and to investigate the sensitivity of product chemical durability to variations in composition.

  14. Interactions between C.I. Basic Blue 41 and aluminosilicate sorbents.

    PubMed

    Roulia, Maria; Vassiliadis, Alexandros A

    2005-11-01

    Four aluminosilicate sorbents (montmorillonite, bentonite, raw perlite, and expanded perlite) were employed for retention of the cationic dye C.I. Basic Blue 41. Interactions between the clay and the dyestuff were investigated at several temperatures and clay:dye ratios. The mechanism behind the adsorption involves the formation of H-aggregates of the dye on both clays, followed by dye migration into the interlayer in the case of montmorillonite. Time-dependent absorbance spectra revealed the presence of various dye species in montmorillonite. Introduction of the dye molecules into the interlamellar space occurs more rapidly in bentonite than in montmorillonite. The dye molecules inserted between the clay leaves adopt different orientations and, eventually, stack in layers at increased dye loadings for both montmorillonite and bentonite. Higher dye aggregates are then present as suggested by diffuse reflectance spectroscopy. Dye sorption on both raw and expanded perlite proceeds via H-aggregate formation as well. PMID:15990108

  15. Calcium-magnesium Aluminosilicate (CMAS) Interactions with Advanced Environmental Barrier Coating Material

    NASA Technical Reports Server (NTRS)

    Wiesner, Valerie L.; Bansal, Narottam P.

    2015-01-01

    Particulates, like sand and volcanic ash, threaten the development of robust environmental barrier coatings (EBCs) that protect next-generation silicon-based ceramic matrix composite (CMC) turbine engine components from harsh combustion environments during service. The siliceous particulates transform into molten glassy deposits of calcium-magnesium aluminosilicate (CMAS) when ingested by an aircraft engine operating at temperatures above 1200C. In this study, a sample of desert sand was melted into CMAS glass to evaluate high-temperature interactions between the sand glass and an advanced EBC material. Desert sand glass was added to the surface of hot-pressed EBC substrates, which were then heated in air at temperatures ranging from 1200C to 1500C. Scanning electron microscopy and X-ray energy-dispersive spectroscopy were used to evaluate microstructure and phase compositions of specimens and the CMASEBC interface after heat treatments.

  16. Fictive temperature-independent density and minimum indentation size effect in calcium aluminosilicate glass

    SciTech Connect

    Gross, T. M.; Tomozawa, M.

    2008-09-15

    Using the calcium aluminosilicate system a glass was developed that exhibits fictive temperature-independent density by creating an intermediate glass between normal and anomalous glasses. Normal glass, such as soda-lime silicate glass, exhibits decreasing density with increasing fictive temperature while anomalous glass, such as silica glass, exhibits increasing density with increasing fictive temperature. This intermediate glass composition was found to exhibit the minimum indentation size effect during indentation hardness testing. It appears that the indentation size effect is correlated with a deformation-induced fictive temperature increase, which is accompanied by a density change and hardness change in the vicinity of the indentation. It is suggested from these observations that indentation size effect originates from the energy required to create interfaces and defects such as shear bands, subsurface cracks, and point defects near the indenter-specimen boundary, which accompany the volume change.

  17. A facile strategy to recycle template P123 from mesoporous aluminosilicates by ultrasonic extraction.

    PubMed

    Jin, Jun-su; Cao, Li; Su, Guang-xun; Xu, Chun-yan; Zhang, Ze-ting; Gao, Xiong-hou; Liu, Hong-hai; Liu, Hong-tao

    2014-09-01

    High synthesis cost of mesoporous aluminosilicates (MA) limits their practical application. Recycling of copolymer template employed in preparation of MA is an effective way to reduce the synthesis cost. An ultrasonic extraction strategy for recycling of organic template P123 in MAs is reported. Effects of different extraction parameters on P123 recovery are investigated and the optimum conditions are obtained. 75.0% P123 is recovered from MAs within 10 min by one-step ultrasonication. Characterizations indicated that the resulting P123-free MA (MA-U) exhibits excellent properties compared with that of calcined products. Moreover, recovered P123 can be employed to synthesize high hydrothermally stable MA. This investigation provides a facile strategy to recycle P123 from MA. PMID:24703432

  18. Tailoring of Boehmite-Derived Aluminosilicate Aerogel Structure and Properties: Influence of Ti Addition

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.; Guo, Haiquan; Sheets, Erik J.; Miller, Derek R.; Newlin, Katy N.

    2010-01-01

    Aluminosilicate aerogels offer potential for extremely low thermal conductivities at temperatures greater than 900 C, beyond where silica aerogels reach their upper temperature limits. Aerogels have been synthesized at various Al:Si ratios, including mullite compositions, using Boehmite (AlOOH) as the Al source, and tetraethoxy orthosilicate as the Si precursor. The Boehmite-derived aerogels are found to form by a self-assembly process of AlOOH crystallites, with Si-O groups on the surface of an alumina skeleton. Morphology, surface area and pore size varies with the crystallite size of the starting Boehmite powder, as well as with synthesis parameters. Ternary systems, including Al-Si-Ti aerogels incorporating a soluble Ti precursor, are possible with careful control of pH. The addition of Ti influences sol viscosity, gelation time pore structure and pore size distribution, as well as phase formation on heat treatment.

  19. Prospects and challenges of iron pyroelectrolysis in magnesium aluminosilicate melts near minimum liquidus temperature.

    PubMed

    Ferreira, N M; Kovalevsky, A V; Mikhalev, S M; Costa, F M; Frade, J R

    2015-04-14

    Although steel production by molten oxide electrolysis offers potential economic and environmental advantages over classic extractive metallurgy, its feasibility is far from being convincingly demonstrated, mainly due to inherent experimental difficulties exerted by harsh conditions and lack of knowledge regarding relevant mechanisms and physico-chemical processes in the melts. The present work was intended to demonstrate the concept of pyroelectrolysis at very high temperature near the minimum liquidus point of magnesium aluminosilicate, being conducted under electron-blocking conditions using yttria-stabilized zirconia cells, and to provide a new insight into electrochemistry behind this process. Significant current yields are possible for pyroelectrolysis performed in electron-blocking mode using a solid electrolyte membrane to separate the anode and the molten electrolyte. Parasitic electrochemical processes rise gradually as the concentration of iron oxide dissolved in the molten electrolytes is depleted, impairing faradaic efficiency. Reduction of silica to metallic silicon was identified as a significant contribution to those parasitic currents, among other plausible processes. Direct pyroelectrolysis without electron blocking was found much less plausible, due to major limitations on faradaic efficiency imposed by electronic leakage and insufficient ionic conductivity of the aluminosilicate melt. Ohmic losses may consume an excessive fraction of the applied voltage, thus failing to sustain the Nernst potential required for reduction to metallic iron. The results suggest the need for further optimization of the molten electrolyte composition to promote ionic conductivity and to suppress electronic transport contribution, possibly, by tuning the Al/Si ratio and altering the network-forming/modifying behaviour of the iron cations. PMID:25760633

  20. Energy Analysis of Aluminosilicate Zeolites with Comprehensive Ranges of Framework Topologies, Chemical Compositions, and Aluminum Distributions.

    PubMed

    Muraoka, Koki; Chaikittisilp, Watcharop; Okubo, Tatsuya

    2016-05-18

    The contents and locations of Al in the zeolite frameworks are one of the key factors determining the physicochemical properties of zeolites. Systematic evaluation of the characteristics of zeolites with a wide variety of framework topologies, a wide range of Si/Al ratios, and various locations of Al is of great significance, but very challenging due to the limitation of the realizable ranges of Al contents in zeolites as well as the limited information on the Al locations obtained from the current analytical techniques. Here, we report the systematic analysis of the energetics of aluminosilicate zeolites with 209 existing framework topologies at different Si/Al ratios using molecular mechanics. More than 43 000 initial structures were generated to give comprehensive views of the energetics of zeolites. The results coincide well with the structural knowledge obtained experimentally. It was revealed that the relation between the relative framework energies versus the Al contents varies in accordance with the topologies, suggesting that the relative stability of zeolites depends not only on the topologies, but also on the substituting contents of Al. For particular topologies with the same Al contents, in addition, comparisons between random and specific distributions of Al showed that zeolite with Al at a particular T site is energetically more stable than those with random distributions, suggesting the inherent influences of the Al locations. The contents and locations of Al in zeolites likely have a certain preference that may reflect the range of chemical compositions, the Al distributions, and consequently the physicochemical properties of realizable aluminosilicate zeolites. PMID:27097121

  1. Molecular Biology of Insect Sodium Channels and Pyrethroid Resistance

    PubMed Central

    Dong, Ke; Du, Yuzhe; Rinkevich, Frank; Nomura, Yoshiko; Xu, Peng; Wang, Lingxin; Silver, Kristopher; Zhorov, Boris S.

    2015-01-01

    Voltage-gated sodium channels are essential for the initiation and propagation of the action potential in neurons and other excitable cells. Because of their critical roles in electrical signaling, sodium channels are targets of a variety of naturally occurring and synthetic neurotoxins, including several classes of insecticides. This review is intended to provide an update on the molecular biology of insect sodium channels and the molecular mechanism of pyrethroid resistance. Although mammalian and insect sodium channels share fundamental topological and functional properties, most insect species carry only one sodium channel gene, compared to multiple sodium channel genes found in each mammalian species. Recent studies showed that two posttranscriptional mechanisms, alternative splicing and RNA editing, are involved in generating functional diversity of sodium channels in insects. More than 50 sodium channel mutations have been identified to be responsible for or associated with knockdown resistance (kdr) to pyrethroids in various arthropod pests and disease vectors. Elucidation of molecular mechanism of kdr led to the identification of dual receptor sites of pyrethroids on insect sodium channels. Most of the kdr mutations appear to be located within or close to the two receptor sites. The accumulating knowledge of insect sodium channels and their interactions with insecticides provides a foundation for understanding the neurophysiology of sodium channels in vivo and the development of new and safer insecticides for effective control of arthropod pests and human disease vectors. PMID:24704279

  2. [Absorption of fluorides by synthetic hydroxyapatites].

    PubMed

    Yévenes, I; Sánchez, U; Medina, M E

    1988-01-01

    We studied the adsorption of sodium fluoride, ammonium fluoride, tin fluoride and sodium monofluorophosphate to synthetic hydroxiapatite in function of the pH (pH 4.7, 5.5 and 6.1). In two models; in a first model was eluted the fluorides of the hydroxiapatite column with artificial saliva; in the second model were incubated the fluoride with bufferized hydroxiapatite to the above pH. The fluoride determination was done by potentiometric method with a specific ion activity electrode. The results in the elution indicated that the sodium and tin fluorides give elution levels different at the pH studied. By other hand ammonium fluoride did not present differences. The results with incubation demonstrated that ammonium fluoride gives the greater adsorption, the sodium fluoride is slightly lower, and the sodium monofluorophosphate the lowest. Also, was observed that the adsorption decrease with the increase of the pH for the three fluorides. The comparison of both models showed that the incubation presented higher values of adsorption than the elution for the pH studied. PMID:3155417

  3. Synthetic cathinone abuse

    PubMed Central

    Capriola, Michael

    2013-01-01

    The abuse of synthetic cathinones, widely known as bath salts, has been increasing since the mid-2000s. These substances are derivatives of the naturally occurring compound cathinone, which is the primary psychoactive component of khat. The toxicity of synthetic cathinones includes significant sympathomimetic effects, as well as psychosis, agitation, aggression, and sometimes violent and bizarre behavior. Mephedrone and methylenedioxypyrovalerone are currently the predominantly abused synthetic cathinones. PMID:23869180

  4. Evolvable synthetic neural system

    NASA Technical Reports Server (NTRS)

    Curtis, Steven A. (Inventor)

    2009-01-01

    An evolvable synthetic neural system includes an evolvable neural interface operably coupled to at least one neural basis function. Each neural basis function includes an evolvable neural interface operably coupled to a heuristic neural system to perform high-level functions and an autonomic neural system to perform low-level functions. In some embodiments, the evolvable synthetic neural system is operably coupled to one or more evolvable synthetic neural systems in a hierarchy.

  5. [SYNTHETIC PEPTIDE VACCINES].

    PubMed

    Sergeyev, O V; Barinsky, I F

    2016-01-01

    An update on the development and trials of synthetic peptide vaccines is reviewed. The review considers the successful examples of specific protection as a result of immunization with synthetic peptides using various protocols. The importance of conformation for the immunogenicity of the peptide is pointed out. An alternative strategy of the protection of the organism against the infection using synthetic peptides is suggested. PMID:27145593

  6. Characterizing synthetic gypsum

    SciTech Connect

    Henkels, P.J.; Gaynor, J.C.

    1996-10-01

    Each gypsum wallboard manufacturer has developed its own general guidelines for synthetic gypsum. The guidelines vary accordingly for each manufacturer and are often modified to suite a particular source and end use. In addition, the physical and chemical properties of synthetic gypsum are characterized by several proprietary and published test methods. Characterizing a synthetic gypsum and determining its acceptability is a time consuming process and can be confusing, particularly to those outside the gypsum wallboard industry. This paper describes some of the more important characteristics and practical aspects of synthetic gypsum usage based on USG`s extensive experience in wall board manufacture.

  7. Mechanisms of Tenebrescence and Persistent Luminescence in Synthetic Hackmanite Na8Al6Si6O24(Cl,S)2.

    PubMed

    Norrbo, Isabella; Gluchowski, Pawel; Hyppänen, Iko; Laihinen, Tero; Laukkanen, Pekka; Mäkelä, Jaakko; Mamedov, Fikret; Santos, Hellen S; Sinkkonen, Jari; Tuomisto, Minnea; Viinikanoja, Antti; Lastusaari, Mika

    2016-05-11

    Synthetic hackmanites, Na8Al6Si6O24(Cl,S)2, showing efficient purple tenebrescence and blue/white persistent luminescence were studied using different spectroscopic techniques to obtain a quantified view on the storage and release of optical energy in these materials. The persistent luminescence emitter was identified as impurity Ti(3+) originating from the precursor materials used in the synthesis, and the energy storage for persistent luminescence was postulated to take place in oxygen vacancies within the aluminosilicate framework. Tenebrescence, on the other hand, was observed to function within the Na4(Cl,S) entities located in the cavities of the aluminosilicate framework. The mechanism of persistent luminescence and tenebrescence in hackmanite is presented for the first time. PMID:27088662

  8. Docusate Sodium and Pregnancy

    MedlinePlus

    ... live chat Live Help Fact Sheets Share Docusate Sodium Friday, 01 April 2016 In every pregnancy, a ... This sheet talks about whether exposure to docusate sodium may increase the risk for birth defects over ...

  9. Sodium carbonate poisoning

    MedlinePlus

    Sodium carbonate (known as washing soda or soda ash) is a chemical found in many household and ... products. This article focuses on poisoning due to sodium carbonate. This article is for information only. Do ...

  10. Diclofenac sodium overdose

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/002630.htm Diclofenac sodium overdose To use the sharing features on this page, please enable JavaScript. Diclofenac sodium is a prescription medicine used to relieve pain ...

  11. Sodium blood test

    MedlinePlus

    ... able to conserve water) Too much salt or sodium bicarbonate in the diet Use of certain medicines, including corticosteroids, laxatives, lithium, and medicines such as ibuprofen or naproxen Lower than normal sodium level is called hyponatremia. It may be due ...

  12. Fractional excretion of sodium

    MedlinePlus

    FE sodium; FENa ... to a lab. There, they are examined for salt (sodium) and creatinine levels. Creatinine is a chemical waste ... your normal foods with a normal amount of salt, unless otherwise instructed by your health care provider. ...

  13. Diclofenac sodium overdose

    MedlinePlus

    Diclofenac sodium is a prescription medicine used to relieve pain and swelling. It is a nonsteroidal anti-inflammatory drug (NSAID). Diclofenac sodium overdose occurs when someone takes more than the ...

  14. Sodium Ferric Gluconate Injection

    MedlinePlus

    Sodium ferric gluconate injection is used to treat iron-deficiency anemia (a lower than normal number of ... are also receiving the medication epoetin (Epogen, Procrit). Sodium ferric gluconate injection is in a class of ...

  15. Nepheline crystallization in boron-rich alumino-silicate glasses as investigated by multi-nuclear NMR, Raman, & Mössbauer spectroscopies

    SciTech Connect

    Mccloy, John S.; Washton, Nancy M.; Gassman, Paul L.; Marcial, Jose; Weaver, Jamie L.; Kukkadapu, Ravi K.

    2015-02-01

    A spectroscopic study was conducted on 6 complex simulant nuclear waste glasses using multi-nuclear NMR, Raman and Mössbauer spectroscopies to explore the role of glass-forming elements Si, Al, B, along with Na and Fe and to understand their connectivity with the goal of understanding melt structure precursors to deleterious feldspathoid nepheline-like crystals formation. NMR showed the appearance of two sites for Al, Si, and Na in the samples which crystallized significant amounts of nepheline, and B speciation changed, typically resulting in more B(IV) after nepheline crystallization. Raman spectroscopy suggested a major part of the glass structure is composed of metaborate chains or rings, thus significant numbers of non-bridging oxygens and a separation of the borate from the alumino-silicate network. Mössbauer combined with Fe redox chemical measurements showed that Fe plays a minor role in these glasses, mostly as Fe3+, but that iron oxide spinel forms with nepheline in all cases. Models of the glass network, speciation of B, and allocation of non-bridging oxygens were computed. The Yun-Dell-Bray model failed to predict the observed high concentration of NBO necessary to explain the metaborate features in the Raman spectra, and it largely over-estimated B(IV) fraction. The model assuming Na-Al-Si moieties and using experimental B(IV) fraction predicted a large amount of NBO consistent with Raman spectra. An alternative notation for appreciating the glass network is suggested and then used to investigate the changes the glass due to crystallization of sodium nepheline and the residual glass network. From a theoretical standpoint, it may be preferred to picture nuclear waste glasses by the Lebedev theory of glass structure where “microcrystallites” of ordered nuclei (or embryos) exist in the matrix of more disordered glass.

  16. Charge-transfer state excitation as the main mechanism of the photodarkening process in ytterbium-doped aluminosilicate fibres

    SciTech Connect

    Bobkov, K K; Rybaltovsky, A A; Vel'miskin, V V; Likhachev, M E; Bubnov, M M; Dianov, E M; Umnikov, A A; Gur'yanov, A N; Vechkanov, N N; Shestakova, I A

    2014-12-31

    We have studied photodarkening in ytterbium-doped fibre preforms with an aluminosilicate glass core. Analysis of their absorption and luminescence spectra indicates the formation of stable Yb{sup 2+} ions in the glass network under IR laser pumping at a wavelength λ = 915 nm and under UV irradiation with an excimer laser (λ = 193 nm). We have performed comparative studies of the luminescence spectra of the preforms and crystals under excitation at a wavelength of 193 nm. The mechanism behind the formation of Yb{sup 2+} ions and aluminium – oxygen hole centres (Al-OHCs), common to ytterbium-doped YAG crystals and aluminosilicate glass, has been identified: photoinduced Yb{sup 3+} charge-transfer state excitation. (optical fibres)

  17. Variable Synthetic Capacitance

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L.

    1986-01-01

    Feedback amplifier circuit synthesizes electronically variable capacitance. Variable Synthetic Capacitor is amplifier circuit with follower/feedback configuration. Effective input capacitance depends on input set current. If synthetic capacitor is connected across resonant element of oscillator, oscillator frequency controlled via input set current. Circuit especially suitable for fine frequency adjustments of piezoelectric-crystal or inductor/capacitor resonant oscillators.

  18. Designing synthetic biology.

    PubMed

    Agapakis, Christina M

    2014-03-21

    Synthetic biology is frequently defined as the application of engineering design principles to biology. Such principles are intended to streamline the practice of biological engineering, to shorten the time required to design, build, and test synthetic gene networks. This streamlining of iterative design cycles can facilitate the future construction of biological systems for a range of applications in the production of fuels, foods, materials, and medicines. The promise of these potential applications as well as the emphasis on design has prompted critical reflection on synthetic biology from design theorists and practicing designers from many fields, who can bring valuable perspectives to the discipline. While interdisciplinary connections between biologists and engineers have built synthetic biology via the science and the technology of biology, interdisciplinary collaboration with artists, designers, and social theorists can provide insight on the connections between technology and society. Such collaborations can open up new avenues and new principles for research and design, as well as shed new light on the challenging context-dependence-both biological and social-that face living technologies at many scales. This review is inspired by the session titled "Design and Synthetic Biology: Connecting People and Technology" at Synthetic Biology 6.0 and covers a range of literature on design practice in synthetic biology and beyond. Critical engagement with how design is used to shape the discipline opens up new possibilities for how we might design the future of synthetic biology. PMID:24156739

  19. Synthetic facial implants.

    PubMed

    Quatela, Vito C; Chow, Jen

    2008-02-01

    This article presents a range of synthetic implant materials for use in facial plastic surgery. The authors discuss alternatives to autogenous tissue transfer in terms of biocompatibility, technique, complications, controversies, and cautions. The reader is presented information about a range of synthetic implant materials such as silicone, polyester fiber, polyamide mesh, metal, polyethylene, polyacrylamide gel, hydroxyapatite, polylactic acid, collagen, and others. PMID:18063244

  20. Flux Decoupling and Chemical Diffusion in Redox Dynamics in Aluminosilicate Melts and Glasses (Invited)

    NASA Astrophysics Data System (ADS)

    Cooper, R. F.

    2010-12-01

    Measurements of redox dynamics in silicate melts and glasses suggest that, for many compositions and for many external environments, the reaction proceeds and is rate-limited by the diffusive flux of divalent-cation network modifiers. Application of ion-backscattering spectrometry either (i) on oxidized or reduced melts (subsequently quenched before analysis) or (ii) on similarly reacted glasses, both of basalt-composition polymerization, demonstrates that the network modifiers move relative to the (first-order-rigid) aluminosilicate network. Thus, the textures associated with such reactions are often surprising, and frequently include metastable or unstable phases and/or spatial compositional differences. This response is only possible if the motion of cations can be decoupled from that of anions. In many cases, decoupling is accomplished by the presence in the melt/glass of transition-metal cations, whose heterovalency creates distortions in the electronic band structure resulting in electronic defects: electron “holes” in the valence band or electrons in the conduction band. (The prevalence of holes or electrons being a function of bulk chemistry and oxygen activity.) These electronic species make the melt/glass a “defect semiconductor.” Because (a) the critical issue in reaction dynamics is the transport coefficient (the product of species mobility and species concentration) and (b) the electronic species are many orders of magnitude more mobile than are the ions, very low concentrations of transition-metal ions are required for flux decoupling. For example, 0.04 at% Fe keeps a magnesium aluminosilicate melt/glass a defect semiconductor down to 800°C [Cook & Cooper, 2000]. Depending on composition, high-temperature melts can see ion species having a high-enough transport coefficient to allow decoupling, e.g., alkali cations in a basaltic melt [e.g., Pommier et al., 2010]. In this presentation, these ideas will be illustrated by examining redox dynamics

  1. An empirical model to estimate density of sodium hydroxide solution: An activator of geopolymer concretes

    NASA Astrophysics Data System (ADS)

    Rajamane, N. P.; Nataraja, M. C.; Jeyalakshmi, R.; Nithiyanantham, S.

    2016-02-01

    Geopolymer concrete is zero-Portland cement concrete containing alumino-silicate based inorganic polymer as binder. The polymer is obtained by chemical activation of alumina and silica bearing materials, blast furnace slag by highly alkaline solutions such as hydroxide and silicates of alkali metals. Sodium hydroxide solutions of different concentrations are commonly used in making GPC mixes. Often, it is seen that sodium hydroxide solution of very high concentration is diluted with water to obtain SHS of desired concentration. While doing so it was observed that the solute particles of NaOH in SHS tend to occupy lower volumes as the degree of dilution increases. This aspect is discussed in this paper. The observed phenomenon needs to be understood while formulating the GPC mixes since this influences considerably the relationship between concentration and density of SHS. This paper suggests an empirical formula to relate density of SHS directly to concentration expressed by w/w.

  2. Production and short-term of synthetic seeds from encapsulated begonia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Synthetic seeds were formed from in vitro grown Begonia (cvs ‘Sweetheart Mix’ and ‘Baby Wing White’) shoot tips using 3% sodium alginate in Murashige and Skoog (1962) medium (MS) salt solution as the gel matrix and 100 mM calcium chloride for complexation. Synthetic seed formation was achieved by re...

  3. The effect of TiO2/aluminosilicate nanocomposite additives on the mechanical and thermal properties of polyacrylic coatings

    NASA Astrophysics Data System (ADS)

    Nosrati, Rahimeh; Olad, Ali

    2015-12-01

    The commercial grade polyacrylic latex was modified in order to prepare a mechanical and thermal improved coating. TiO2/Ag-exchanged-aluminosilicate nanocomposites with montmorillonite, zeolite-A and clinoptilolite aluminosilicates were prepared and used as additive in the matrix of polyacrylic latex to achieve a coating with proper mechanical and thermal properties. X-ray diffraction patterns and FESEM were used to characterize the composition, structure, and morphology of the nanocomposite additives. Polyacrylic coatings modified by TiO2/Ag-exchanged-aluminosilicate nanocomposite additives showed higher adhesion strength and hardness compared to unmodified commercial grade polyacrylic coatings. Differential Scanning Calorimetry (DSC) analysis showed lower glass transition temperature for modified polyacrylic coatings than that of unmodified polyacrylic coatings. The tensile tests were also carried out for unmodified and modified polyacrylic coatings. According to the results, the modified polyacrylic based coating with TiO2/Ag-exchanged-clinoptilolite nanocomposite additive was the best coating considering most of useful properties.

  4. Source fabrication and lifetime for Li+ ion beams extracted from alumino-silicate sources

    SciTech Connect

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W.

    2012-04-01

    A space-charge-limited beam with current densities (J) exceeding 1 mA/cm2 have been measured from lithium alumino-silicate ion sources at a temperature of ~1275 °C. At higher extraction voltages, the source appears to become emission limited with J ≥ 1.5 mA/cm2, and J increases weakly with the applied voltage. A 6.35 mm diameter source with an alumino-silicate coating, ≤0.25 mm thick, has a measured lifetime of ~40 h at ~1275 °C, when pulsed at 0.05 Hz and with pulse length of ~6 μs each. At this rate, the source lifetime was independent of the actual beam charge extracted due to the loss of neutral atoms at high temperature. Finally, the source lifetime increases with the amount of alumino-silicate coated on the emitting surface, and may also be further extended if the temperature is reduced between pulses.

  5. Source fabrication and lifetime for Li+ ion beams extracted from alumino-silicate sources

    SciTech Connect

    Roy, Prabir K.; Greenway, Wayne G.; Kwan, Joe W

    2012-03-05

    A space-charge-limited beam with current densities (J) exceeding 1 mA/cm2 have been measured from lithium alumino-silicate ion sources at a temperature of ~1275 °C. At higher extraction voltages, the source appears to become emission limited with J ≥ 1.5 mA/cm2, and J increases weakly with the applied voltage. A 6.35 mm diameter source with an alumino-silicate coating, ≤0.25 mm thick, has a measured lifetime of ~40 h at ~1275 °C, when pulsed at 0.05 Hz and with pulse length of ~6 μs each. At this rate, the source lifetime was independent of the actual beam charge extracted due to the loss of neutral atoms at high temperature. Finally, the source lifetime increases with the amount of alumino-silicate coated on the emitting surface, and may also be further extended if the temperature is reduced between pulses.

  6. Water in peralkaline aluminosilicate melts to 2 GPa and 1400°C

    NASA Astrophysics Data System (ADS)

    Mysen, Bjorn

    2002-09-01

    The solubility of H 2O in melts along the join CaSi 4O 4-Ca(Ca 0.5Al) 4O 9 (0, 3, and 6 mol% Al 2O 3) has been determined at 0.8 to 2.0 GPa and 1200 to 1400°C and compared with the solubility of H 2O in melts along the joins Na 2Si 4O 9-Na 2(NaAl) 4O 9 and K 2Si 4O 9-K 2(KAl) 4O 9. The H 2O solubility is a positive function of pressure and a negative function of temperature and Al 2O 3 content so that solubility, X H 2O melt (mol%), is X H 2O melt( CAS)=19±2-0.7±0.1•X Al2O3+0.06±0.02•(X Al2O3) 2+13.3±0.2•P( GPa)-0.011±0.001• T( K). In alkali aluminosilicate melts, the solubility is considerably more sensitive to pressure, Al 2O 3, and temperature. The H 2O solubility data in the 0.8- to 2.0-GPa and 1200 to 1400°C pressure and temperature range are consistent with constant activity coefficient of H 2O in the melt. The partial molar volume of H 2O, V¯ H 2O melt, derived from the solubility data, ranges between 12.4 cm 3/mol for Al-free CaSi 4O 9 melt and 10.4 cm 3/mol for CaSi 4O 9 + 6 mol% Al 2O 3. This decrease in V¯ H 2O melt with increasing Al 2O 3 is similar to that reported for H 2O in melts along the two alkali aluminosilicate joins (Na 2Si 4O 9-Na 2(NaAl) 4O 9 and K 2Si 4O 9-K 2(KAl) 4O 9). The V¯ H 2O melt is invariant with temperature in contrast to V¯ H 2O melt along the joins, Na 2Si 4O 9-Na 2(NaAl) 4O 9 and K 2Si 4O 9-K 2(KAl) 4O 9, where in both cases V¯ H 2O melt decreases with increasing temperature.

  7. Alkali aluminosilicate melts and glasses: structuring at the middle range order of amorphous matter

    NASA Astrophysics Data System (ADS)

    Le Losq, C.; neuville, D. R.

    2012-12-01

    Rheological properties of silicate melts govern both magma ascension from the mantle to the surface of the earth and volcanological eruptions styles and behaviours. It is well known that several parameters impact strongly these properties, such as for instance the temperature, pressure, chemical composition and volatiles concentration, finally influencing eruptive behaviour of volcanoes. In this work, we will focus on the Na2O-K2O-Al2O3-SiO2 system, which is of a prime importance because it deals with a non-negligible part of natural melts, like for instance the Vesuvius (Italy) or Erebus (Antartica) magmas. In an oncoming paper in Chemical Geology (Le Losq and Neuville, 2012), we have communicated results of the study of mixing Na-K in tectosilicate melts containing a high concentration of silica (≥75mol%). In the present communication, we will enlarge this first point of view to tectosilicate melts presenting a lower silica concentration. We will first present our viscosity data, and then the Adam and Gibbs theory that allows theoretically modelling Na-K mixing in aluminosilicate melts by using the so-called "mixed alkali effect". On the basis of the rheological results, the Na-K mixing cannot be explained with the ideal "mixed alkali effect", which involves random exchange of Na-K cationic pairs. To go further and as rheological properties are directly linked with structural properties, we will present our first results obtained by Raman and NMR spectroscopy. These last ones provide important structural pieces of information on the polymerization state of glasses and melts, and also on the environment of tetrahedrally coordinated cations. Rheological and structural results all highlight that Na and K are not randomly distributed in aluminosilicate glasses and melts networks. Na melts present a network with some channels and a non-random distribution of Al and Si. K networks are different. They also present a non-random distribution of Al and Si, but in two sub

  8. Rechargeable sodium alloy anode

    SciTech Connect

    Jow, T.R.

    1988-06-28

    A secondary battery is described comprising: (a) an anode which comprises an alloy of sodium and one or metals selected from the group consisting of tin, lead antimony, bismuth, selenium and tellerium, (b) an electrolyte comprising one or more organic solvents and one or more sodium salts dissolved therein forming dissolved sodium cations in solution; and (c) a cathode; the sodium cations from the electrolyte alloying with the one or more metals of the alloy in the anode during the charging of the battery and sodium in the alloy disoloving in the electrolyte during the discharging of the battery.

  9. Network cation coordination in aluminoborosilicate and Mg- aluminosilicate glasses: pressure effects in recovered structural changes and densification

    NASA Astrophysics Data System (ADS)

    Bista, S.; Stebbins, J. F.; Sisson, T. W.; Hankins, W. B.

    2015-12-01

    In this study, we compare the aluminum and boron coordination of glass samples recovered from piston-cylinder experiments carried out at 1 to 3 GPa and near to their ambient glass transition temperature (Tg), which we have found gives a more accurate picture of high pressure structural changes than experiments involving quenching from above the liquidus, as large pressure drops can occur in the latter. Aluminoborosilicate glasses with excess modifier (Ca, La and Y- aluminoborosilicate) quenched from melts at 1-3 GPa were studied with B-11 and Al-27 MAS NMR to assess relative effects on two different network cations. Structural changes in the Y-aluminoborosilicate are dramatic, going from mostly AlO4 at low pressure to mostly AlO5 and AlO6 at 3 GPa. Large increases in BO4 (vs. BO3) are also seen. Mg-aluminosilicate glasses, both tectosilicate (Mg2Al4Si6O20) and with excess modifier composition (Mg3Al2Si6O18) quenched from melts at 1-3 GPa pressure were studied with Al-27 MAS NMR. In contrast to our previous study (Bista et al., Am. Min., in press) of jadeite glass, where only 0.5% of fivefold aluminum was seen in glass recovered from 3 GPa, five and six fold aluminum species increase significantly with increasing pressure in both Mg aluminosilicate glass compositions studied here. We observe that the tectosilicate Mg aluminosilicate glass has more higher coordinated aluminum than the excess modifier containing composition in the pressure range in our study. In the previous study (Bista et al., in press) of jadeite and calcium aluminosilicate (Ca3Al2Si6O18) glasses, 6-8% densification was observed in glasses recovered from 3 GPa. In this study of Mg aluminosilicate glasses, we observe 12% densification in glasses recovered from 3 GPa. Both types of observation confirm that structural and density changes with pressure are enhanced by higher field strength modifier cations, and will be especially important in Mg- and Fe-rich mantle melts.

  10. Effect of low frequency ultrasound on the surface properties of natural aluminosilicates.

    PubMed

    Novikova, Liudmila; Ayrault, Philippe; Fontaine, Claude; Chatel, Gregory; Jérôme, François; Belchinskaya, Larisa

    2016-07-01

    Structural and surface properties of different natural aluminosilicates (layered, chain and framework structural types) exposed of 20 kHz ultrasound irradiation (0-120 min) in aqueous and 35 wt%. aqueous H2O2 dispersions were studied by X-ray diffraction (XRD), dynamic light scattering (DLS), nitrogen adsorption-desorption, thermal analysis, and Fourier transform infrared spectroscopy (FTIR) techniques. It was confirmed that sonication caused slight changes in the structure of investigated minerals whereas their textural properties were significantly affected. The aqueous dispersions of montmorillonite (Mt), clinoptilolite (Zlt), glauconite (Glt) and palygorskite (Pal) were represented by several particles size fractions according to DLS-study. Ultrasound irradiation produced a decrease of the average particle diameter by 4-6 times in water and by 1.3-5 times in H2O2 dispersions except for Pal, which underwent strong agglomeration. A significant increase of total pore volume and pore diameter was observed for Glt sonicated in H2O2 dispersions whereas for Pal mainly micropore volume sharply increased in both aqueous and H2O2 dispersions. PMID:26964987

  11. Poorly Crystalline, Iron-Bearing Aluminosilicates and Their Importance on Mars

    NASA Technical Reports Server (NTRS)

    Baker, L. L.; Strawn, D. G.; McDaniel, P. A.; Nickerosn, R. N.; Bishop, J. L.; Ming, D. W.; Morris, Richard V.

    2011-01-01

    Martian rocks and sediments contain weathering products including evaporite salts and clay minerals that only form as a result of interaction between rocks and water [1-6]. These weathering products are key to studying the history of water on Mars because their type, abundance and location provide clues to past conditions on the surface of the planet, as well as to the possible location of present-day reservoirs of water. Weathering of terrestrial volcanic rocks similar to those on Mars produces nano-sized, variably hydrated aluminosilicate and iron oxide minerals [7-10] including allophane, imogolite, halloysite, hisingerite, and ferrihydrite. The nanoaluminosilicates can contain isomorphically substituted Fe, which affects their spectral and physical properties. Detection and quantification of such minerals in natural environments on earth is difficult due to their variable chemical composition and lack of long-range crystalline order [9, 11, 12]. Despite the difficulty in characterizing these materials, they are common on Earth, and data from orbital remote sensing and rover-based instruments suggest that they are also present on Mars [9, 10, 13-17]. Their accurate detection and quantification require a better understanding of how composition affects their spectral properties. We present here the results of XAFS spectroscopy; these results will be corroborated with planned Mossbauer and reflectance spectroscopy.

  12. Molecular Dynamics Simulations of Uranyl and Uranyl Carbonate Adsorption at Alumino-silicate Surfaces

    SciTech Connect

    Kerisit, Sebastien N.; Liu, Chongxuan

    2014-03-03

    Adsorption at mineral surfaces is a critical factor controlling the mobility of uranium(VI) in aqueous environments. Therefore, molecular dynamics (MD) simulations were performed to investigate uranyl(VI) adsorption onto two neutral alumino-silicate surfaces, namely the orthoclase (001) surface and the octahedral aluminum sheet of the kaolinite (001) surface. Although uranyl preferentially adsorbed as a bi-dentate innersphere complex on both surfaces, the free energy of adsorption at the orthoclase surface (-15 kcal mol-1) was significantly more favorable than that at the kaolinite surface (-3 kcal mol-1), which was attributed to differences in surface functional groups and to the ability of the orthoclase surface to dissolve a surface potassium ion upon uranyl adsorption. The structures of the adsorbed complexes compared favorably with X-ray absorption spectroscopy results. Simulations of the adsorption of uranyl complexes with up to three carbonate ligands revealed that uranyl complexes coordinated to up to 2 carbonate ions are stable on the orthoclase surface whereas uranyl carbonate surface complexes are unfavored at the kaolinite surface. Combining the MD-derived equilibrium adsorption constants for orthoclase with aqueous equilibrium constants for uranyl carbonate species indicates the presence of adsorbed uranium complexes with one or two carbonates in alkaline conditions, in support of current uranium(VI) surface complexation models.

  13. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    NASA Astrophysics Data System (ADS)

    Liu, Minmin; Hou, Li-an; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-05-01

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin-Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics.

  14. Preparation of bioinorganic fertilizing media by adsorption of humates on glassy aluminosilicates.

    PubMed

    Chassapis, Konstantinos; Roulia, Maria; Vrettou, Evangelia; Parassiris, Anastassios

    2010-11-01

    Surface-modified expanded perlite was synthesized using humic substances from the Megalopolis peaty lignite. Adsorption is efficient and increases at higher temperatures and lower pHs. The preparation can be carried out under mild conditions leading to an eco-friendly, bioinorganic material useful as soil conditioner and biofertilizer. Six adsorption models were applied; the Klotz, Freundlich and Redlich-Peterson isotherms fit more successfully to the experimental data. The obeying of the theoretical models was correlated with the heterogeneity and non-uniform distribution of the adsorption sites, host-guest attraction forces as well as the formation of self-assembled aggregates and self-organized multilayers of humic substances onto the aluminosilicate adsorbent, consistent with changes in micromorphology. Thermodynamic quantities revealing distinct physicochemical characteristics of the adsorption phenomena, i.e., enthalpy, entropy and free energy change, were calculated. Desorption experiments and cultivation of microorganisms demonstrated that perlite may act successfully as host material for microbial populations upgrading the humic-loaded perlite for soil applications. PMID:20692818

  15. In situ structural analysis of calcium aluminosilicate glasses under high pressure

    NASA Astrophysics Data System (ADS)

    Muniz, R. F.; de Ligny, D.; Martinet, C.; Sandrini, M.; Medina, A. N.; Rohling, J. H.; Baesso, M. L.; Lima, S. M.; Andrade, L. H. C.; Guyot, Y.

    2016-08-01

    In situ micro-Raman spectroscopy was used to investigate the structural evolution of OH‑-free calcium aluminosilicate glasses, under high pressure and at room temperature. Evaluation was made of the role of the SiO2 concentration in percalcic join systems, for Al/(Al  +  Si) in the approximate range from 0.9 to 0.2. Under high pressure, the intensity of the main band related to the bending mode of bridging oxygen ({ν\\text{B}} [T-O-T], where T  =  Si or Al) decreased gradually, suggesting that the bonds were severely altered or even destroyed. In Si-rich glasses, compression induced a transformation of Q n species to Q n‑1. In the case of Al-rich glass, the Al in the smallest Q n units evolved from tetrahedral to higher-coordinated Al ([5]Al and [6]Al). Permanent structural changes were observed in samples recovered from the highest pressure of around 15 GPa and, particularly for Si-rich samples, the recovered structure showed an increase of three-membered rings in the Si/Al tetrahedral network.

  16. Lithium aluminosilicate reinforced with carbon nanofiber and alumina for controlled-thermal-expansion materials

    NASA Astrophysics Data System (ADS)

    Borrell, Amparo; García-Moreno, Olga; Torrecillas, Ramón; García-Rocha, Victoria; Fernández, Adolfo

    2012-02-01

    Materials with a very low or tailored thermal expansion have many applications ranging from cookware to the aerospace industry. Among others, lithium aluminosilicates (LAS) are the most studied family with low and negative thermal expansion coefficients. However, LAS materials are electrical insulators and have poor mechanical properties. Nanocomposites using LAS as a matrix are promising in many applications where special properties are achieved by the addition of one or two more phases. The main scope of this work is to study the sinterability of carbon nanofiber (CNFs)/LAS and CNFs/alumina/LAS nanocomposites, and to adjust the ratio among components for obtaining a near-zero or tailored thermal expansion. Spark plasma sintering of nanocomposites, consisting of commercial CNFs and alumina powders and an ad hoc synthesized β-eucryptite phase, is proposed as a solution to improving mechanical and electrical properties compared with the LAS ceramics obtained under the same conditions. X-ray diffraction results on phase compositions and microstructure are discussed together with dilatometry data obtained in a wide temperature range (-150 to 450 °C). The use of a ceramic LAS phase makes it possible to design a nanocomposite with a very low or tailored thermal expansion coefficient and exceptional electrical and mechanical properties.

  17. Thermodynamics of aluminosilicate garnet solid solution: new experimental data, an optimized model, and thermometric applications

    NASA Astrophysics Data System (ADS)

    Ganguly, J.; Cheng, Weiji; Tirone, Massimiliano

    1996-12-01

    We have experimentally determined the displacement of the equilibrium Grossular + 2 Kyanite + Quartz ⇆ 3 Anorthite (GASP) as a function of garnet composition in the systems Mg-Ca-Mn, Fe-Mg-Ca and Fe-Mg-Ca-Mn at 1000°C. The results were treated along with selected experimental and observational data available in the literature as well as binary parameters from other workers to obtain a set of mutually compatible binary mixing parameters of the quaternary (Fe,Mg,Ca,Mn)- aluminosilicate garnet solid solution. Attempts to determine equilibrium garnet composition in the GASP equilibrium in the Ca-Mg binary were unsuccessful due to the formation of pyroxene. Calculations of binary and ternary miscibility gaps show that the P,T,X combination required for unmixing of garnet solid solution is not realized by natural samples. The solution model was applied to account for compositional effects on Fe-Mg exchange between garnet and ortho- or clino-pyroxene. Applications of the revised thermometric formulations to selected natural assemblages yield P-T conditions which are much less sensitive to compositional effects compared to the other available formulations, and are consistent with independent constraints.

  18. In situ structural analysis of calcium aluminosilicate glasses under high pressure.

    PubMed

    Muniz, R F; de Ligny, D; Martinet, C; Sandrini, M; Medina, A N; Rohling, J H; Baesso, M L; Lima, S M; Andrade, L H C; Guyot, Y

    2016-08-10

    In situ micro-Raman spectroscopy was used to investigate the structural evolution of OH(-)-free calcium aluminosilicate glasses, under high pressure and at room temperature. Evaluation was made of the role of the SiO2 concentration in percalcic join systems, for Al/(Al  +  Si) in the approximate range from 0.9 to 0.2. Under high pressure, the intensity of the main band related to the bending mode of bridging oxygen ([Formula: see text][T-O-T], where T  =  Si or Al) decreased gradually, suggesting that the bonds were severely altered or even destroyed. In Si-rich glasses, compression induced a transformation of Q (n) species to Q (n-1). In the case of Al-rich glass, the Al in the smallest Q (n) units evolved from tetrahedral to higher-coordinated Al (([5])Al and ([6])Al). Permanent structural changes were observed in samples recovered from the highest pressure of around 15 GPa and, particularly for Si-rich samples, the recovered structure showed an increase of three-membered rings in the Si/Al tetrahedral network. PMID:27300313

  19. Fabrication of large diameter alumino-silicate K{sup +} sources

    SciTech Connect

    Baca, D.; Chacon-Golcher, E.; Kwan, J.W.; Wu, J.K.

    2003-02-20

    Alumino-silicate K{sup +} sources have been used in HIF experiments for many years. For example the Neutralized Transport Expt. (NTX) and the High Current Transport Expt. (HCX) are now using this type of ion source with diameters of 2.54 cm and 10 cm respectively. These sources have demonstrated ion currents of 80 mA and 700 mA, for typical HIF pulse lengths of 5-10 {micro}s. The corresponding current density is {approx} 10-15 mA/cm{sup 2}, but much higher current density has been observed using smaller size sources. Recently we have improved our fabrication techniques and, therefore, are able to reliably produce large diameter ion sources with high quality emitter surface without defects. This note provides a detailed description of the procedures employed in the fabrication process. The variables in the processing steps affecting surface quality, such as substrate porosity, powder size distribution, coating technique on large area concave surfaces, drying, and heat firing temperature have been investigated.

  20. Synthesis and Properties of a Barium Aluminosilicate Solid Oxide Fuel Cell Glass-Ceramic Sealant

    SciTech Connect

    Meinhardt, Kerry D.; Kim, Dong-Sang; Chou, Y. S.; Weil, K. Scott

    2008-07-15

    A series of barium aluminosilicate glasses modified with CaO and B2O3, were prepared and evaluated with respect to their suitability in sealing planar solid oxide fuel cells (SOFCs). At a target operating temperature of 750ºC, the long-term CTE of one particular composition (35 mol% BaO, 15 mol% CaO, 10 mol% B2O3, 5 mol% Al2O3, bal. SiO2) was found to be particularly stable, due to devitrification to a mixture of glass and ceramic phases. This sealant composition exhibits minimal chemical interaction with the yttria-stabilized zirconia electrolyte, yet forms a strong bond with this material. Interactions with metal components were found to be more extensive and depended on the composition of the metal oxide scale that formed during sealing. Generally alumina-scale formers exhibited a more compact reaction zone with the glass than chromia-scale forming alloys. Mechanical measurements conducted on the bulk glass-ceramic and on seals formed using these materials indicate that the sealant is anticipated to display adequate long-term strength for most conventional stationary SOFC applications.

  1. Single-Walled Aluminosilicate Nanotube/Poly(vinyl alcohol) Nanocomposite Membranes

    SciTech Connect

    Kang, Dun-Yen; Tong, Ho Ming; Zang, Ji; Choudhury, Rudra Prosad; Sholl, David S.; Beckham, Haskell W.; Jones, Christopher W.; Nair, Sankar

    2012-05-29

    The fabrication, detailed characterization, and molecular transport properties of nanocomposite membranes containing high fractions (up to 40 vol %) of individually-dispersed aluminosilicate single-walled nanotubes (SWNTs) in poly(vinyl alcohol) (PVA), are reported. The microstructure, SWNT dispersion, SWNT dimensions, and intertubular distances within the composite membranes are characterized by scanning and transmission electron microscopy (SEM and TEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), XRD rocking curve analysis, small-angle X-ray scattering (SAXS), and solid-state NMR. PVA/SWNT nanocomposite membranes prepared from SWNT gels allow uniform dispersion of individual SWNTs in the PVA matrix with a random distribution of orientations. SAXS analysis reveals the length ({approx}500 nm) and outer diameter ({approx}2.2 nm) of the dispersed SWNTs. Electron microscopy indicates good adhesion between the SWNTs and the PVA matrix without the occurrence of defects such as voids and pinholes. The transport properties of the PVA/SWNT membranes are investigated experimentally by ethanol/water mixture pervaporation measurements, computationally by grand canonical Monte Carlo and molecular dynamics, and by a macroscopic transport model for anisotropic permeation through nanotube-polymer composite membranes. The nanocomposite membranes substantially enhance the water throughput with increasing SWNT volume fraction, which leads to a moderate reduction of the water/ethanol selectivity. The model is parameterized purely from molecular simulation data with no fitted parameters, and shows reasonably good agreement with the experimental water permeability data.

  2. Chemical and mechanical consequences of environmental barrier coating exposure to calcium-magnesium-aluminosilicate.

    SciTech Connect

    Harder, B.; Ramirez-Rico, J.; Almer, J. D.; Kang, L.; Faber, K.

    2011-06-01

    The success of Si-based ceramics as high-temperature structural materials for gas turbine applications relies on the use of environmental barrier coatings (EBCs) with low silica activity, such as Ba{sub 1-x}Sr{sub x}Al{sub 2}Si{sub 2}O{sub 8} (BSAS), which protect the underlying components from oxidation and corrosion in combustion environments containing water vapor. One of the current challenges concerning EBC lifetime is the effect of sandy deposits of calcium-magnesium-aluminosilicate (CMAS) glass that melt during engine operation and react with the EBC, changing both its composition and stress state. In this work, we study the effect of CMAS exposure at 1300 C on the residual stress state and composition in BSAS-mullite-Si-SiC multilayers. Residual stresses were measured in BSAS multilayers exposed to CMAS for different times using high-energy X-ray diffraction. Their microstructure was studied using a combination of scanning electron microscopy and transmission electron microscopy techniques. Our results show that CMAS dissolves the BSAS topcoat preferentially through the grain boundaries, dislodging the grains and changing the residual stress state in the topcoat to a nonuniform and increasingly compressive stress state with increasing exposure time. The presence of CMAS accelerates the hexacelsian-to-celsian phase transformation kinetics in BSAS, which reacts with the glass by a solution-reprecipitation mechanism. Precipitates have crystallographic structures consistent with Ca-doped celsian and Ba-doped anorthite.

  3. A silica optical fiber doped with yttrium aluminosilicate nanoparticles for supercontinuum generation

    NASA Astrophysics Data System (ADS)

    Cheng, Tonglei; Liao, Meisong; Xue, Xiaojie; Li, Jiang; Gao, Weiqing; Li, Xia; Chen, Danping; Zheng, Shupei; Pan, Yubai; Suzuki, Takenobu; Ohishi, Yasutake

    2016-03-01

    We design and fabricate a silica optical fiber doped with yttrium aluminosilicate (YAS, Y2O3-Al2O3-SiO2) nanoparticles in the core. The optical fiber is drawn directly from a silica tube with YAG (Y3Al5O12) ceramics and silica powders (the molar ratio 1:18) in the core at the temperature of ∼1950 °C. The YAS nanoparticles are formed during the optical fiber drawing process. Supercontinuum (SC) generation in the optical fiber is investigated at different pump wavelength. At the pump wavelength of ∼1750 nm which is in the deep anomalous dispersion region, SC spectrum evolution is mainly due to multiple solitons and dispersive waves (DWs), and three pairs of multiple optical solitons and DWs are observed. When the pump wavelength shifts to ∼1500 nm which is close to the zero-dispersion wavelength (ZDW), flattened SC spectrum with ±7 dB uniformity is obtained at the wavelength region of ∼990-1980 nm, and only one obvious soliton and DW are observed. At the pump wavelength of ∼1100 nm, a narrow SC spectrum from ∼1020 to 1180 nm is obtained in the normal dispersion region due to self-phase modulation (SPM) effect.

  4. Single-molecule studies of acidity distributions in mesoporous aluminosilicate thin films.

    PubMed

    Sun, Xiaojiao; Xie, Jingyi; Xu, Jiayi; Higgins, Daniel A; Hohn, Keith L

    2015-05-26

    Solid acid catalysts are important for many petrochemical processes. The ensemble methods most often employed to characterize acid site properties in catalyst materials provide limited insights into their heterogeneity. Single-molecule (SM) fluorescence spectroscopic methods provide a valuable route to probing the properties of individual microenvironments. In this work, dual-color SM methods are adopted to study acidity distributions in mesoporous aluminosilicate (Al-Si) films prepared by the sol-gel method. The highly fluorescent pH-sensitive dye C-SNARF-1 was employed as a probe. The ratio of C-SNARF-1 emission in two bands centered at 580 and 640 nm provides an effective means to sense the pH of bulk solutions. In mesoporous thin films, SM emission data provide a measure of the effective pH of the microenvironment in which each molecule resides. SM emission data were obtained from mesoporous Al-Si films as a function of Al2O3 content for films ranging from 0% to 30% alumina. Histograms of the emission ratio reveal a broad distribution of acidity properties, with the film microenvironments becoming more acidic, on average, as the alumina content of the films increases. This work provides new insights into the distribution of Brønsted acidity in solid acids that cannot be obtained by conventional means. PMID:25941900

  5. Atomic Structure of a Cesium Aluminosilicate Geopolymer: A Pair Distribution Function Study

    SciTech Connect

    Bell, J.; Sarin, P; Provis, J; Haggerty, R; Driemeyer, P; Chupas, P; van Deventer, J; Kriven, W

    2008-01-01

    The atomic pair distribution function (PDF) method was used to study the structure of cesium aluminosilicate geopolymer. The geopolymer was prepared by reacting metakaolin with cesium silicate solution followed by curing at 50C for 24 h in a sealed container. Heating of Cs-geopolymer above 1000C resulted in formation of crystalline pollucite (CsAlSi{sub 2}O{sub 6}). PDF refinement of the pollucite phase formed displayed an excellent fit over the 10-30 {angstrom} range when compared with a cubic pollucite model. A poorer fit was attained from 1-10 {angstrom} due to an additional amorphous phase present in the heated geopolymer. On the basis of PDF analysis, unheated Cs-geopolymer displayed structural ordering similar to pollucite up to a length scale of 9 {angstrom}, despite some differences. Our results suggest that hydrated Cs{sup +} ions were an integral part of the Cs-geopolymer structure and that most of the water present was not associated with Al-OH or Si-OH bonds.

  6. Synthesis and properties of a barium aluminosilicate solid oxide fuel cell glass-ceramic sealant

    NASA Astrophysics Data System (ADS)

    Meinhardt, K. D.; Kim, D.-S.; Chou, Y.-S.; Weil, K. S.

    A series of barium aluminosilicate glasses modified with CaO and B 2O 3 were prepared and evaluated with respect to their suitability in sealing planar solid oxide fuel cells (SOFCs). At a target operating temperature of 750 °C, the long-term coefficient of thermal expansion (CTE) of one particular composition (35 mol% BaO, 15 mol% CaO, 10 mol% B 2O 3, 5 mol% Al 2O 3, and bal. SiO 2) was found to be particularly stable, due to devitrification to a mixture of glass and ceramic phases. This sealant composition exhibits minimal chemical interaction with the yttria-stabilized zirconia electrolyte, yet forms a strong bond with this material. Interactions with metal components were found to be more extensive and depended on the composition of the metal oxide scale that formed during sealing. Generally alumina-scale formers exhibited a more compact reaction zone with the glass than chromia-scale forming alloys. Mechanical measurements conducted on the bulk glass-ceramic and on seals formed using these materials indicate that the sealant is anticipated to display adequate long-term strength for most conventional stationary SOFC applications.

  7. Synthesis, characterization, and mercury adsorption properties of hybrid mesoporous aluminosilicate sieve prepared with fly ash

    PubMed Central

    Liu, Minmin; Hou, Li-an; Xi, Beidou; Zhao, Ying; Xia, Xunfeng

    2013-01-01

    A novel hybrid mesoporous aluminosilicate sieve (HMAS) was prepared with fly ash and impregnated with zeolite A precursors. This improved the mercury adsorption of HMAS compared to original MCM-41. The HMAS was characterized by X-ray diffraction (XRD), nitrogen adsorption–desorption, Fourier transform infrared (FTIR) analysis, transmission electron microscopy (TEM) images and 29Si and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. These showed that the HMAS structure was still retained after impregnated with zeolite A. But the surface area and pore diameter of HMAS decreased due to pore blockage. Adsorption of mercury from aqueous solution was studied on untreated MCM-41and HMAS. The mercury adsorption rate of HMAS was higher than that of origin MCM-41. The adsorption of mercury was investigated on HMAS regarding the pH of mercury solution, initial mercury concentration, and the reaction temperature. The experimental data fit well to Langmuir and Freundlich isotherm models. The Dublin–Radushkevich isotherm and the characterization show that the mercury adsorption on HMAS involved the ion-exchange mechanisms. In addition, the thermodynamic parameters suggest that the adsorption process was endothermic in nature. The adsorption of mercury on HMAS followed the first order kinetics. PMID:23687400

  8. Calcium-Magnesium-Aluminosilicate (CMAS) Reactions and Degradation Mechanisms of Advanced Environmental Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Ahlborg, Nadia L.; Zhu, Dongming

    2013-01-01

    The thermochemical reactions between calcium-magnesium-aluminosilicate- (CMAS-) based road sand and several advanced turbine engine environmental barrier coating (EBC) materials were studied. The phase stability, reaction kinetics and degradation mechanisms of rare earth (RE)-silicates Yb2SiO5, Y2Si2O7, and RE-oxide doped HfO2 and ZrO2 under the CMAS infiltration condition at 1500 C were investigated, and the microstructure and phase characteristics of CMAS-EBC specimens were examined using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Experimental results showed that the CMAS dissolved RE-silicates to form crystalline, highly non-stoichiometric apatite phases, and in particular attacking the silicate grain boundaries. Cross-section images show that the CMAS reacted with specimens and deeply penetrated into the EBC grain boundaries and formed extensive low-melting eutectic phases, causing grain boundary recession with increasing testing time in the silicate materials. The preliminary results also showed that CMAS reactions also formed low melting grain boundary phases in the higher concentration RE-oxide doped HfO2 systems. The effect of the test temperature on CMAS reactions of the EBC materials will also be discussed. The faster diffusion exhibited by apatite and RE-doped oxide phases and the formation of extensive grain boundary low-melting phases may limit the CMAS resistance of some of the environmental barrier coatings at high temperatures.

  9. Synthesis of hydrothermally stable, hierarchically mesoporous aluminosilicate Al-SBA-1 and their catalytic properties.

    PubMed

    Li, Na; Wang, Jin-Gui; Xu, Jian-Xiong; Liu, Jin-Yu; Zhou, Hui-Jing; Sun, Ping-Chuan; Chen, Tie-Hong

    2012-03-21

    Hydrothermally stable mesoporous aluminosilicates Al-SBA-1 with hierarchical pore structure have been successfully synthesized under alkaline condition at 120 °C by employing organic mesomorphous complexes of polyelectrolyte (poly(acrylic acid) (PAA)) and cationic surfactant (hexadecyl pyridinium chloride (CPC)) as template. The Si/Al ratio could be as high as 5 and the incorporation of Al into the silica framework did not disturb the well-ordered cubic Pm ̅3n mesostructure. Meanwhile, the incorporation of Al could greatly increase the specific surface area and pore volume of the samples. The Al-SBA-1 materials exhibited a high hydrothermal stability and remained stable even after being treated in boiling water for 10 days. The catalytic activity of the Al-SBA-1 materials was investigated by employing the Friedel-Crafts alkylation of toluene with benzyl alcohol as a model reaction and they exhibited excellent catalytic property due to the incorporated acid sites and the hierarchically mesoporous structure. PMID:22327221

  10. The Influence of Base Concentration on the Surface Particle of Lithium Aluminosilicate System

    SciTech Connect

    Nazri, I. M.; Asliza, M. A. Sri; Othman, R.

    2008-03-17

    The study of base concentration effect toward surface particles of lithium aluminosilicate glass ceramic system has been done by using NaOH solution. The parent glass with composition of 60% SiO{sub 2}, 31% Li{sub 2}O, 6% Al{sub 2}O{sub 3} and 3% TiO{sub 2} in wt% was prepared by melting process at 1250 deg. C prior to quenching rapidly to room temperature. Sintering and crystallization process on this parent glass were carefully examined by Differential thermal analysis (DTA) and X-Ray Diffraction (XRD). Based on these analyses, the selected crystal has been chosen as a precursor material. There are two controlling parameter involved in this study i.e. NaOH concentration and leaching period. The morphology of the glass ceramic particle was observed by Field Emission Scanning Electron Microscope (FESEM). The result shows that by increasing the basic concentration as well as increasing the soaking leaching period, the tendency of glass ceramic particle to leach out is relatively highs.