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Sample records for cation selective glass

  1. Mixed cation effect in sodium aluminosilicate glasses

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Mauro, John C.

    , network structure, and the resistances associated with the deformation processes in mixed cation glasses by partially substituting magnesium for calcium and calcium for lithium in sodium aluminosilicate glasses. We use Raman and 27Al NMR spectroscopies to obtain insights into the structural...

  2. An investigation of mixed cation oxide glasses

    International Nuclear Information System (INIS)

    Brook, H.C.

    1999-02-01

    This study has been undertaken with several purposes in mind. Firstly, the author wished to ascertain whether EXAFS would show the mixed alkali (MAE) in a mixed alkali glass in shell parameters other than those for the first shell, as well as being a structural probe. Secondly, it was desired to see whether borate glasses show the MAE in EXAFS. Thirdly, the author attempted to ascertain whether cations of different charges would show an effect similar to the MAE. Fourthly, to use NMR as a second structure probe in an attempt to gain a better understanding of the structure. Fifthly, to perform electrical conductivity experiments to try to link the conductivity behaviour with structural changes. Finally, to attempt to develop a generalised explanation of the origins of the MAE and the variations in physical properties in glasses. (author)

  3. Chemical bonding and structural ordering of cations in silicate glasses

    International Nuclear Information System (INIS)

    Calas, G.; Cormier, L.; Galoisy, L.; Ramos, A.; Rossano, St.

    1997-01-01

    The specific surrounding of cations in multicomponent silicate glasses is briefly presented. Information about interatomic distances and site geometry may be gained by using spectroscopic methods among which x-ray absorption spectroscopy may be used for the largest number of glass components. Scattering of x-rays and neutrons may also be used to determine the importance of medium range order around specific cations. All the existing data show that cations occur in sites with a well-defined geometry, which are in most cases connected to the silicate polymeric network. Medium range order has been detected around cations such as Ti, Ca and Ni, indicating that these elements have an heterogeneous distribution within the glassy matrix. (authors)

  4. Inward Cationic Diffusion and Percolation Transition in Glass-Ceramics

    DEFF Research Database (Denmark)

    Smedsklaer, Morten Mattrup; Yue, Yuanzheng; Mørup, Steen

    2010-01-01

    We show the quantitative correlation between the degree of crystallization and the cationic diffusion extent in iron-containing diopside glass–ceramics at the glass transition temperature. We find a critical degree of crystallization, above which the diffusion extent sharply drops with the degree...... of crystallization. Below the critical value, the diffusion extent decreases only slightly with the degree of crystallization. No cationic diffusion is observed in the fully crystalline materials. The critical value might be associated with a percolation transition from an interconnected to a disconnected glass...

  5. Selective crystallization of cations with crown ethers

    International Nuclear Information System (INIS)

    Heffels, Dennis Egidius

    2014-01-01

    The aim of this work was to study the selectivity and preferences of the incorporation of differently sized cations in the cavities of various crown ethers and the characterization of the resulting compounds. The coordination preferences of crown ethers with different cavities have long been known, and the impact of other effects on the structure formation have increasingly become the focus of attention. In this work a comparative overview of the coordination preferences depending on various factors was undertaken. The focus was mainly on the variation of the cavity of the crown ether in the presence of differently sized cations. In addition, the effects of the solvent and differently coordinating anions have been investigated. Within the framework of this work, basic coordination preferences could be detected with rare earth nitrates, which are affected particularly by the choice of the solvent. The formation of different types of structures could be controlled by varying the conditions such that the incorporation of the cation in the cavity of the crown ether was influenced and the formation of a particular type of structure can be influenced partly by the choice of solvent. In this case no direct preferences for the incorporation into the cavity of the crown ether in relation to the cation size were observed for rare earth cations. However, the coordination of the crown ether leads in each case - for lanthanides - to rather high coordination numbers. A total of five new rare earth complexes and two structural variants could be observed with crown ethers. In the study of the selectivity of the incorporation into the cavity, known structures were also reproduced and further structures were characterized but the crystal structures not entirely solved. With the use of monovalent cations such as potassium, lithium or silver a total of nine new compounds could be synthesized, while no clear preferences for the incorporation of certain cations were detected. The

  6. Mozart, dice, and glass selection

    Science.gov (United States)

    Tesar, John C.

    2000-10-01

    In a perfect world a good starting point should not be required. A Genetic Algorithm in powerful lens design software should find an optimum solution for us. As a practical matter a good starting point does matter. Time and resources may not be sufficient to generate a good design in a global optimizer quickly. In lens design a small glass catalog combined with the Hammer algorithm in ZEMAX moves the glass selection process in a search around the glass map forcing the design to consider many radically different forms in a short amount of time. From this starting point an expanded search can be undertaken by conventional design methods or in a global search algorithm. There are precedents in other fields for a narrow search method that still yields near infinite numbers of solutions. Mozart invented a game that narrows a search from a blank sheet paper and a set of notes to a single voice minuet by rolling dice. The results can be played and the dynamics manipulated to form the starting points for future compositions. Music composition software has, like lens design software, incorporated many powerful algorithms and search techniques. A simple comparison will be made. It is a long way from a protoplasm to Christie Brinkley. A good starting point means a lot whether you are an optical designer, a composer, or running the universe.

  7. Diffusion of sodium cations and water stability of glasses for immobilization of middle-active wastes

    International Nuclear Information System (INIS)

    Ivanov, I.A.; Gulin, A.N.; Stefanovskij, S.V.

    1991-01-01

    Sodium cations diffusion coefficients in three model alumoborosilicate silicate and five alumophosfate glasses, including sulfate containing ones, are determined by method of integral residual activity. It is astablished that sodium cation mobilities within the investigated temperature range in glasses of the first group are by 1-3 orders lower than in the second one. Data on rates of sodium leaching from glasses by distilled water are obtained. It is shown that there exist some deviations from symbate character of changing diffusion coefficients and sodium leaching rates. It is found that it is possible to include much more sulfate containing wastes in alumophosphate glasses than in alumoborosilicate ones

  8. Adsorption of Cationic Peptides to Solid Surfaces of Glass and Plastic

    DEFF Research Database (Denmark)

    Kristensen, Kasper; Henriksen, Jonas Rosager; Andresen, Thomas Lars

    2015-01-01

    , that the peptides adsorb to solid surfaces of glass and plastic. Specifically, we use analytical HPLC to systematically quantify the adsorption of the three cationic membraneactive peptides mastoparan X, melittin, and magainin 2 to the walls of commonly used glass and plastic sample containers. Our results show...

  9. Modification of magnetic anisotropy in metallic glasses using high ...

    Indian Academy of Sciences (India)

    ... ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe40Ni40B20 and Fe40Ni38Mo4B18 metallic glass ribbons. 90 MeV 127I beam was used for the irradiations.

  10. Impact of Redox on Glass Durability: The Glass Selection Process

    International Nuclear Information System (INIS)

    PEELER, DAVID

    2004-01-01

    Recent glass formulation activities have focused on developing alternative frit compositions for use with specific sludge batches to maximize melt rate and/or waste throughput. The general trend has been to increase the total alkali content in the glass through the use of a high alkali based frit, a less washed sludge, or a combination of the two. As a result, predictions of durability have become a limiting factor in defining the projected operating windows for the Defense Waste Processing Facility (DWPF) for certain systems. An additional issue for these high alkali glasses has been the effect of REDuction/OXidation (REDOX) on the durability of the glass. Recent analyses have indicated that the application of the durability model's value without consideration of the overall glass composition may lead to a more significant shift (larger magnitude) than needed. Therefore, activation of the REDOX term in the Product Composition Control System (PCCS) may have a significant impact on the predicted operational windows based on model predictions, but may not represent the realistic impact on the measured durability. In this report, two specific issues are addressed. First, a review of the data used to develop PCCS (in particular the durability model) showed the potential for a REDOX interaction that is not accounted for. More specifically, three terms were added to the current model and were found to be statistically significant at a confidence level of 95 per cent. These results suggest a possible interaction between REDOX and glass composition that is not accurately captured leading to potentially conservative decisions regarding the durability of reduced glasses. The second issue addressed in this report is the development of a 45 glass test matrix to assess the effect of REDOX on durability as well as to provide insight into specific interactive compositional effects on durability. The glasses were selected to support the assessment of the following specific

  11. Impact of cationic diffusion on properties of iron-bearing glass fibres

    DEFF Research Database (Denmark)

    Smedskjaer, Morten M.; Yue, Yuanzheng; Deubener, Joachim

    2010-01-01

    A silica-rich surface layer of Fe3+-containing aluminosilicate glass fibres is created by means of an inward diffusion process of divalent network modifying cations. The latter is caused by the reduction of Fe3+ to Fe2+ when the fibres undergo a heat treatment at temperatures around the glass...... transition temperature (Tg) in a reducing H2/N2 atmosphere. The thickness of the surface layer can be adjusted by varying the temperature or the duration of the heat treatment. The reduction process has a significant impact on the glass transition and crystallization behaviour, high temperature stability...

  12. Selective oxidation of propane over cation exchanged zeolites

    NARCIS (Netherlands)

    Xu, J.

    2005-01-01

    This thesis focuses on investigation of the fundamental knowledge on a new method for selective oxidation of propane with O2 at low temperature (< 100°C). The relation between propane catalytic selective oxidation and physicochemical properties of cation exchanged Y zeolite has been studied. An

  13. Selective functionalization of patterned glass surfaces

    NARCIS (Netherlands)

    Ploetz, E.; Visser, B.; Slingenbergh, W.; Evers, K.; Martinez-Martinez, D.; Pei, Y. T.; Feringa, B. L.; De Hosson, J. Th. M.; Cordes, T.; van Dorp, W. F.

    2014-01-01

    Tailored writing and specific positioning of molecules on nanostructures is a key step for creating functional materials and nano-optical devices, or interfaces for synthetic machines in various applications. We present a novel approach for the selective functionalization of patterned glass surfaces

  14. Selective Facet Reactivity During Cation Exchange in Cadmium Sulfide Nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Sadtler, Bryce; Demchenko, Denis; Zheng, Haimei; Hughes, Steven; Merkle, Maxwell; Dahmen, Ulrich; Wang, Lin-Wang; Alivisatos, A. Paul

    2008-12-18

    The partial transformation of ionic nanocrystals through cation exchange has been used to synthesize nanocrystal heterostructures. We demonstrate that the selectivity for cation exchange to take place at different facets of the nanocrystal plays an important role in determining the resulting morphology of the binary heterostructure. In the case of copper I (Cu+) cation exchange in cadmium sulfide (CdS) nanorods, the reaction starts preferentially at the ends of the nanorods such that copper sulfide (Cu2S) grows inwards from either end. The resulting morphology is very different from the striped pattern obtained in our previous studies of silver I (Ag+) exchange in CdS nanorods where non-selective nucleation of silver sulfide (Ag2S) occurs. From interface formation energies calculated for several models of epitaxialconnections between CdS and Cu2S or Ag2S, we infer the relative stability of each interface during the nucleation and growth of Cu2S or Ag2S within the CdS nanorods. The epitaxial connections of Cu2S to the end facets of CdS nanorods minimize the formation energy, making these interfaces stable throughout the exchange reaction. However, as the two end facets of wurtzite CdS nanorods are crystallographically nonequivalent, asymmetric heterostructures can be produced.

  15. Glass–water interaction: Effect of high-valence cations on glass structure and chemical durability

    Energy Technology Data Exchange (ETDEWEB)

    Hopf, J.; Kerisit, Sebastien N.; Angeli, F.; Charpentier, Thibault M.; Icenhower, Jonathan P.; McGrail, Bernard P.; Windisch, Charles F.; Burton, Sarah D.; Pierce, Eric M.

    2016-05-15

    Borosilicate glass is a durable solid, but it dissolves when in contact with aqueous fluids. The dissolution mechanism, which involves a variety of sequential reactions that occur at the solid-fluid interface, has important implications for the corrosion resistance of industrial and nuclear waste glasses. In this study, spectroscopic measurements, dissolution experiments, and Monte Carlo simulations were performed to investigate the effect of high–valence cations (HVC) on the mechanisms of glass dissolution under dilute and near-saturated conditions. Raman and NMR spectroscopy were used to determine the structural changes that occur in glass, specifically network formers (e.g., Al, Si, and B), with the addition of the HVC element hafnium in the Na2O–Al2O3–B2O3–HfO2–SiO2 system (e.g., Na/[Al+B] = 1.0 and HfO2/SiO2 from 0.0 to 0.42). Spectroscopic measurements revealed that increasing hafnium content decreases N4 (tetrahedral boron/total boron) and increases the amount of Si—O—Hf moieties in the glass. Results from flow–through experiments conducted under dilute and near–saturated conditions show a decrease of approximately 100× or more in the dissolution rate over the series from 0 to 20 mol% HfO2. Comparing the average steady-state rates obtained under dilute conditions to the rates obtained for near-saturated conditions reveals a divergence in the magnitude between the average steady state rates measured in these different conditions. The reason for this divergence was investigated more thoroughly using Monte Carlo simulations. Simulations indicate that the divergence in glass dissolution behavior under dilute and near-saturated conditions result from the stronger binding of Si sites that deposit on the surface from the influent when Hf is present in the glass. As a result, the residence time at the glass surface of these newly-formed Si sites is longer in the presence of Hf, which increases the density of anchor sites from which altered layers

  16. Dropping and semimicrotest glass reactions on beryllium, lenthanum, vanadyl and uranyl cations with synthetic organic dyes and their mutual determination in binary mixtures

    International Nuclear Information System (INIS)

    Shemyakin, F.M.; Novikova, A.A.; Reshetnyak, V.Yu.; Teplyakov, G.K.; Nekrasov, E.L.

    1978-01-01

    Coloured reactions for beryllium, lanthanum, vanadyl and uranyl cations with a number of organic dyes, have been studied. These reactions are used in dropping analysis on papers, impregnated with relevant dyes, and for semimicro-test glass reactions on the above cations. Sensitivity and maximum permissible dilution have been determined for each of the reactions. Mutual determinations of relevant couples of the above cations have been performed. It is shown, that such binary mixtures enable to freely open relevant cations

  17. An FPGA Implementation to Detect Selective Cationic Antibacterial Peptides

    Science.gov (United States)

    Polanco González, Carlos; Nuño Maganda, Marco Aurelio; Arias-Estrada, Miguel; del Rio, Gabriel

    2011-01-01

    Exhaustive prediction of physicochemical properties of peptide sequences is used in different areas of biological research. One example is the identification of selective cationic antibacterial peptides (SCAPs), which may be used in the treatment of different diseases. Due to the discrete nature of peptide sequences, the physicochemical properties calculation is considered a high-performance computing problem. A competitive solution for this class of problems is to embed algorithms into dedicated hardware. In the present work we present the adaptation, design and implementation of an algorithm for SCAPs prediction into a Field Programmable Gate Array (FPGA) platform. Four physicochemical properties codes useful in the identification of peptide sequences with potential selective antibacterial activity were implemented into an FPGA board. The speed-up gained in a single-copy implementation was up to 108 times compared with a single Intel processor cycle for cycle. The inherent scalability of our design allows for replication of this code into multiple FPGA cards and consequently improvements in speed are possible. Our results show the first embedded SCAPs prediction solution described and constitutes the grounds to efficiently perform the exhaustive analysis of the sequence-physicochemical properties relationship of peptides. PMID:21738652

  18. Ion-selective chalcogenide electrodes for a number of cations.

    Science.gov (United States)

    Hirata, H; Higashiyama, K

    1972-04-01

    Ion-selective chalcogenide disc electrodes have been developed which are responsive to cations such as silver, lead, chromium(III), nickel, cobalt(II), cadmium, zinc, copper(II) and manganese(II) ions. Each was prepared by using the corresponding metal chalcogenide with silver sulphide. An electrode was assembled with both a compacted and a sintered disc. The sintered electrodes were more sensitive and stable than the compacted ones. Response to silver ion was 59.5 mV pAg , to lead, nickel, cadmium, zinc and copper(II) 29.5 mV pM and to chromium(III) 20 mV pM . Cobalt(II) and manganese(II) electrodes had a non-Nernstian response of 25 mV pM . Both selenides and tellurides can be used for potentiometric determination, but the manganese(II) electrode serves as an analytical tool only when the disc consists of manganese(II) telluride and silver sulphide.

  19. Short- and medium-range structural order around cations in glasses: amultidisciplinary approachOrdre local à courte et moyenne distance autour des cations dans les verres: une approche pluridisciplinaire

    Science.gov (United States)

    Cormier, Laurent; Galoisy, Laurence; Delaye, Jean-Marc; Ghaleb, Dominique; Calas, Georges

    2001-03-01

    The structural environment of cations at a short- and medium-range scale may be investigated either by spectroscopic methods or by radiation diffraction giving either a description of the geometry and symmetry of the cationic site, including the nature of the chemical bond, or a chemically resolved radial distribution function. Cations exhibit several original structural properties in oxide glasses. Short-range order is characterized by unusual coordination numbers, such as five-coordinated sites or tetrahedral sites which are in a network forming position, with the relative proportion of these sites depending on glass composition. Oxide glasses can also exhibit elements with unusual oxidation states, such as pentavalent uranium. The determination of the sites occupied by the elements in their different oxidation states allows to rationalize the chemical dependence of redox equilibria, which is the way to predict Fe behavior in magmatic silicate systems. Several experimental data lend support that cations are located in domains extending up to more than 8 Å radius, in which cationic polyhedra may be linked together either by edges or by corners. In low alkali borate glasses, transition elements such as Co, Ni, Zn exist in peculiar highly ordered domains corresponding to the presence of rigid borate units. Strong differences are observed between modifying and charge compensating cations, either concerning site geometry or medium-range organization. The use of numerical models for experimental data inversion allows to rationalize the structural behavior of the various glass components.

  20. Antibacterial activity of selected glass ionomer cements

    Directory of Open Access Journals (Sweden)

    Elżbieta Łuczaj-Cepowicz

    2014-01-01

    Full Text Available Introduction: The aim of the paper was to determine the antibacterial activity of four glass ionomer cements against bacteria of the genera Streptococcus and Lactobacillus. Material and methods: Four capsulated glass ionomer cements were applied in the study: Fuji Triage (GC, Fuji IX (GC, Ketac Molar (3M Espe and Ketac Silver (3M Espe. Four standard bacterial strains were used to assess the antibacterial activity of the studied cements: Streptococcus mutans, S. sanguis, S. salivarius and Lactobacillus casei. The antibacterial activity was determined by the agar diffusion method. The bacterial suspension was spread with a cotton swab on TSA plates. For each material six wells (7 mm diameter, 5 mm deep were made with a cork borer. Each well was then filled with freshly prepared cements. The results were obtained by measuring the bacterial growth inhibition zone after 1, 2, 3 and 7 days. Results: Fuji Triage cement inhibited the growth of all bacterial strains. Fuji IX cement demonstrated the most potent antibacterial activity against S. sanguis. Ketac Molar showed antibacterial activity against S. sanguis and S. salivarius, whereas Ketac Silver was efficient against S. mutans as well. Neither of the Ketac cements inhibited growth of the standard L. casei strain. Discussion: Antibacterial activity of glass ionomer cements has attracted the interest of scientists in recent years. Most authors, including us, carried out experiments using the agar diffusion method and demonstrated antibacterial activity of glass ionomer cements. Different antibacterial activity of glass ionomer cements, observed in our study and studies of other authors, depended on the evaluated cement, bacterial strain and period of evaluation.

  1. Antibacterial activity of selected glass ionomer cements

    Directory of Open Access Journals (Sweden)

    Elżbieta Łuczaj-Cepowicz

    2014-01-01

    Full Text Available Introduction: The aim of the paper was to determine the antibacterial activity of four glass ionomer cements against bacteria of the genera Streptococcus and Lactobacillus.Material and methods: Four capsulated glass ionomer cements were applied in the study: Fuji Triage (GC, Fuji IX (GC, Ketac Molar (3M Espe and Ketac Silver (3M Espe. Four standard bacterial strains were used to assess the antibacterial activity of the studied cements: Streptococcus mutans, S. sanguis, S. salivarius and Lactobacillus casei. The antibacterial activity was determined by the agar diffusion method. The bacterial suspension was spread with a cotton swab on TSA plates. For each material six wells (7 mm diameter, 5 mm deep were made with a cork borer. Each well was then filled with freshly prepared cements. The results were obtained by measuring the bacterial growth inhibition zone after 1, 2, 3 and 7 days. Results: Fuji Triage cement inhibited the growth of all bacterial strains. Fuji IX cement demonstrated the most potent antibacterial activity against S. sanguis. Ketac Molar showed antibacterial activity against S. sanguis and S. salivarius, whereas Ketac Silver was efficient against S. mutans as well. Neither of the Ketac cements inhibited growth of the standard L. casei strain. Discussion: Antibacterial activity of glass ionomer cements has attracted the interest of scientists in recent years. Most authors, including us, carried out experiments using the agar diffusion method and demonstrated antibacterial activity of glass ionomer cements. Different antibacterial activity of glass ionomer cements, observed in our study and studies of other authors, depended on the evaluated cement, bacterial strain and period of evaluation.

  2. Free volume of mixed cation borosilicate glass sealants elucidated by positron annihilation lifetime spectroscopy and its correlation with glass properties

    Science.gov (United States)

    Ojha, Prasanta K.; Rath, Sangram K.; Sharma, Sandeep K.; Sudarshan, Kathi; Pujari, Pradeep K.; Chongdar, Tapas K.; Gokhale, Nitin M.

    2015-01-01

    The role of La+3/Sr+2 ratios, which is varied from 0.08 to 5.09, on density, molar volume, packing fraction, free volume, thermal and electrical properties in strontium lanthanum aluminoborosilicate based glass sealants intended for solid oxide fuel cell (SOFC) applications is evaluated. The studies reveal expansion of the glass network evident from increasing molar volume and decreasing packing fraction of glasses with progressive La+3 substitutions. The molecular origin of these macroscopic structural features can be accounted for by the free volume parameters measured from positron annihilation lifetime spectroscopy (PALS). The La+3 induced expanded glass networks show increased number of subnanoscopic voids with larger sizes, as revealed from the ortho-positronium (o-Ps) lifetime and its intensity. A remarkably direct correspondence between the molar volume and fractional free volume trend is established with progressive La2O3 substitution in the glasses. The effect of these structural changes on the glass transition temperature, softening temperature, coefficient of thermal expansion, thermal stability as well as electrical conductivity has been studied.

  3. Voltammetric ion-selective electrodes for the selective determination of cations and anions.

    Science.gov (United States)

    Zhang, Jie; Harris, Alexander R; Cattrall, Robert W; Bond, Alan M

    2010-03-01

    A general theory has been developed for voltammetric ion sensing of cations and anions based on the use of an electrode coated with a membrane containing an electroactive species, an ionophore, and a supporting electrolyte dissolved in a plasticizer. In experimental studies, a membrane coated electrode is fabricated by the drop coating method. In one configuration, a glassy carbon electrode is coated with a poly(vinyl chloride) based membrane, which contains the electroactive species, ionophore, plasticizer and supporting electrolyte. In the case of a cation sensor, ionophore facilitated transfer of the target cation from the aqueous solution to the membrane phase occurs during the course of the reduction of the electroactive species present in the membrane in order to maintain charge neutrality. The formal potential is calculated from the cyclic voltammogram as the average of the reduction and oxidation peak potentials and depends on the identity and concentration of the ion present in the aqueous solution phase. A plot of the formal potential versus the logarithm of the concentration exhibits a close to Nernstian slope of RT/F millivolts per decade change in concentration when the concentration of K(+) and Na(+) is varied over the concentration range of 0.1 mM to 1 M when K(+) or Na(+) ionophores are used in the membrane. The slope is close to RT/2F millivolts for a Ca(2+) voltammetric ion-selective electrode fabricated using a Ca(2+) ionophore. The sensor measurement time is only a few seconds. Voltammetric sensors for K(+), Na(+), and Ca(2+) constructed in this manner exhibit the sensitivity and selectivity required for determination of these ions in environmentally and biologically important matrixes. Analogous principles apply to the fabrication of anion voltammetric sensors.

  4. Inward Cationic Diffusion and Formation of Silica-Rich Surface Nanolayer of Glass

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Deubener, Joachim; Yue, Yuanzheng

    2009-01-01

    This paper reports a chemical approach for obtaining a silica-rich nanolayer on the surface of a vanadium-bearing silicate glass. The approach involves depletion of earth alkaline ions (Mg2+ and Ca2+) from the glass surface by means of inward diffusion of those ions, i.e., diffusion from the surf......This paper reports a chemical approach for obtaining a silica-rich nanolayer on the surface of a vanadium-bearing silicate glass. The approach involves depletion of earth alkaline ions (Mg2+ and Ca2+) from the glass surface by means of inward diffusion of those ions, i.e., diffusion from...

  5. Ion-Selective Detection with Glass Nanopipette for Living Cells

    Science.gov (United States)

    Takami, T.; Son, J. W.; Kang, E. J.; Deng, X. L.; Kawai, T.; Lee, S.-W.; Park, B. H.

    2013-05-01

    We developed a method to probe local ion concentration with glass nanopipette in which poly(vinyl chloride) membrane containing ionophore for separate ion detection is prepared. Here we demonstrate how ion-selective detections are available for living cells such as HeLa cell, rat vascular myocyte, and neuron cell.

  6. Electromagnetic Properties of Substituted Ba - Ferrites by Selected Cations

    Directory of Open Access Journals (Sweden)

    Anna Gruskova

    2004-01-01

    Full Text Available The powdered samples of barium hexaferrite BaFe12-2x(Me1Me2 with x varying from 0.0 to 0.6 were prepared by citrate precursor method. The cation preference of mainly four-valence Me1=(Zr, Ti, Sn ions and two-valence Me2=(Co, Ni, Zn ions and their combinations in substituted Ba ferrites were investigated by the thermomagnetic analysis, Mossbauer spectroscopy and measurement of the magnetic properties. Mossbaur studies reveal that Zr4+, Sn4+ and less Co2+, Zn2+ ions have a strong preference to occupy 2b position, this position has the greatest contribution to the magnetocrystalline anisotropy. The La3+, Ti4+, Ni2+ ions preferently enter 4f2 sites and Zn2+, Co2+ ions also prefer to occupy 4f1 tetrahedral sites. The specific saturation magnetic polarisation Js-m and remanence Js-r increased with small x due to th substitution of non-magnetic and less magnetic ions in 4f1 and 4f2 sites. The coercivity Hc was casily controllable by the sustituions level x.

  7. Infrared spectroscopy of network and cation dynamics in binary and mixed alkali borate glasses

    NARCIS (Netherlands)

    Verhoef, A.H; Hartog, H.W.den

    Infrared reflectance spectra of twenty different glasses of the type (B2O3)(1-x-y)(Li2O)(x)(Cs2O)(y) have been measured in the frequency range of 10-5000 cm(-1). From these spectra, infrared absorbance and dielectric spectra have been calculated using the Kramers-Kronig inversion technique. The

  8. Vibrational spectra and antimicrobial activity of selected bivalent cation benzoates

    Science.gov (United States)

    Borawska, M. H.; Koczoń, P.; Piekut, J.; Świsłocka, R.; Lewandowski, W.

    2009-02-01

    Selected bands of FT-IR spectra of Mg(II), Ca(II), Cu(II) and Zn(II) benzoates of both solid state and water solution, were assigned to appropriate molecular vibrations. Next evaluation of electronic charge distribution in both carboxylic anion and aromatic ring of studied compounds was performed. Classical plate tests and turbidimetry measurements, monitoring growth of bacteria Escherichia coli, Bacillus subtilis and yeasts Pichia anomala and Saccharomyces cerevisiae during 24 h of incubation, in optimal growth conditions (control) and in medium with addition of studied benzoate (concentration of 0.01% expressed as the concentration of benzoic acid), proved antimicrobial activity of studied compounds against investigated micro-organisms. PLS (partially least square) and PCR (principal component regression) techniques were applied to build a model, correlating spectral data reflecting molecular structure of studied compounds, with degree of influence of those compounds on growth of studied micro-organisms. Statistically significant correlation within cross validation diagnostic of PLS-1 calibration was found, when log 1/T of selected spectral regions of water solution samples were used as input data. The correlation coefficients between predicted with PLS calibration based on created 1, 2 or 3 factor models, and actual values of antimicrobial activity were: 0.70; 0.76, 0.81 for P. anomala, B. subtilis, and E. coli, respectively. Log(PRESS) values of appropriate models were 2.10, 2,39 and 3.23 for P. anomala, B. subtilis, and E. coli, respectively.

  9. Impact of cationic diffusion on properties of iron-bearing glass fibres

    DEFF Research Database (Denmark)

    Smedskjaer, Morten M.; Yue, Yuanzheng; Deubener, Joachim

    2010-01-01

    transition temperature (Tg) in a reducing H2/N2 atmosphere. The thickness of the surface layer can be adjusted by varying the temperature or the duration of the heat treatment. The reduction process has a significant impact on the glass transition and crystallization behaviour, high temperature stability...... (HTS), and chemical durability of the fibres. The reduction deteriorates the HTS of the fibres in argon due to the decrease of Tg and increase of the crystallization temperatures. However, the crystallization behaviour and HTS in air are not affected by the reduction. This is because a re...

  10. Cluster formation of network-modifier cations in cesium silicate glasses

    Science.gov (United States)

    Jardón-Álvarez, Daniel; Sanders, Kevin J.; Phyo, Pyae; Baltisberger, Jay H.; Grandinetti, Philip J.

    2018-03-01

    Natural abundance 29Si two-dimensional magic-angle flipping (2D MAF) NMR spectra were measured in a series of ten cesium silicate glass compositions xCs2O.(1 - x)SiO2, where x is 0.067, 0.113, 0.175, 0.179, 0.218, 0.234, 0.263, 0.298, 0.31, and 0.36. The Q3 shielding anisotropy decreases with increasing Cs content—interpreted as an increase in the non-bridging oxygen (NBO) bond length from increasing Cs coordination (clustering) around the NBO. The 29Si 2D MAF spectra for four glass compositions x = 0.218, 0.234, 0.263, 0.298 exhibit a second co-existing and distinctly smaller shielding anisotropy corresponding to a significantly longer Si-NBO length arising from a higher degree of Cs clustering around the NBO. This second Q3 site appears at a Cs2O mole fraction close to the critical mole fraction of x = 0.24 associated with the percolation threshold of non-bridging oxygen in random close packing of oxygen, thus suggesting that the longer Si-NBO length is associated with an infinite size spanning cluster while the sites with larger anisotropies are associated with shorter Si-NBO lengths and belong to finite size clusters. The equilibrium constant of the Q3 disproportionation reaction was determined as k3 = 0.005, indicating a Qn anionic species distribution close to a binary model as expected for a low field strength modifier such as cesium. It is also found that evolution of the isotropic Q4 and line shapes with increasing Cs content are consistent with a random connectivity model between Qn of differing number of bridging oxygen, n.

  11. The non-selective monovalent cationic channels TRPM4 and TRPM5.

    Science.gov (United States)

    Guinamard, Romain; Sallé, Laurent; Simard, Christophe

    2011-01-01

    Transient Receptor Potential (TRP) proteins are non-selective cationic channels with a consistent Ca(2+)-permeability, except for TRPM4 and TRPM5 that are not permeable to this ion. However, Ca(2+) is a major regulator of their activity since both channels are activated by a rise in internal Ca(2+). Thus TRPM4 and TRPM5 are responsible for most of the Ca(2+)-activated non-selective cationic currents (NSC(Ca)) recorded in a large variety of tissues. Their activation induces cell-membrane depolarization that modifies the driving force for ions as well as activity of voltage gated channels and thereby strongly impacts cell physiology. In the last few years, the ubiquitously expressed TRPM4 channel has been implicated in insulin secretion, the immune response, constriction of cerebral arteries, the activity of inspiratory neurons and cardiac dysfunction. Conversely, TRPM5 whose expression is more restricted, has until now been mainly implicated in taste transduction.

  12. Selective crystallization of cations with crown ethers; Selektive Kristallisation von Kationen mit Kronenethern

    Energy Technology Data Exchange (ETDEWEB)

    Heffels, Dennis Egidius

    2014-07-04

    The aim of this work was to study the selectivity and preferences of the incorporation of differently sized cations in the cavities of various crown ethers and the characterization of the resulting compounds. The coordination preferences of crown ethers with different cavities have long been known, and the impact of other effects on the structure formation have increasingly become the focus of attention. In this work a comparative overview of the coordination preferences depending on various factors was undertaken. The focus was mainly on the variation of the cavity of the crown ether in the presence of differently sized cations. In addition, the effects of the solvent and differently coordinating anions have been investigated. Within the framework of this work, basic coordination preferences could be detected with rare earth nitrates, which are affected particularly by the choice of the solvent. The formation of different types of structures could be controlled by varying the conditions such that the incorporation of the cation in the cavity of the crown ether was influenced and the formation of a particular type of structure can be influenced partly by the choice of solvent. In this case no direct preferences for the incorporation into the cavity of the crown ether in relation to the cation size were observed for rare earth cations. However, the coordination of the crown ether leads in each case - for lanthanides - to rather high coordination numbers. A total of five new rare earth complexes and two structural variants could be observed with crown ethers. In the study of the selectivity of the incorporation into the cavity, known structures were also reproduced and further structures were characterized but the crystal structures not entirely solved. With the use of monovalent cations such as potassium, lithium or silver a total of nine new compounds could be synthesized, while no clear preferences for the incorporation of certain cations were detected. The

  13. Cation selectivity of the plasma membrane of tobacco protoplasts in the electroporated state.

    Science.gov (United States)

    Wegner, Lars H

    2013-08-01

    Cation selectivity of the cellular membrane of tobacco culture cells (cell line 'bright yellow-2') exposed to pulsed electric fields in the millisecond range was investigated. The whole cell configuration of the patch clamp technique was established on protoplasts prepared from these cells. Ion selectivity of the electroporated membrane was investigated by measuring the reversal potential of currents passing through field-induced pores. To this end the membrane was hyper- or depolarized for 10ms (prepulse); subsequently the voltage was driven to opposite polarity at a constant rate (+40 or -40mV/ms, respectively). The experiment was started by polarizing the membrane to moderately negative or positive voltages (prepulse potential ±150mV) that would not induce pore formation. Subsequently, an extended voltage range was scanned in the porated state of the membrane (prepulse potential ±600mV). IV curves in the porated and the non-porated state (obtained at the same prepulse polarity) were superimposed to determine the voltage at which both curves intersected ('Intersection potential'). Using a modified version of the Goldmann-Hodgkin-Katz equation relative permeabilities to Ca(2+) and various monovalent alkali and organic cations were calculated. Pores were found to be fairly cation selective, with a selectivity sequence determined to be Ca(2+)>Li(+)>Rb(+)≈K(+)≈Na(+)>TEA(+)≈TBA(+)>Cl(-). Relative permeability to monovalent cations was inversely related to the ionic diameter. By fitting a formalism suggested by Dwyer at al. (J. Gen. Physiol. 75 (1980), 469-492) the effective average diameter of field induced pores was estimated to be about 1.8nm. Implications of these results for biotechnology and electroporation theory are discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. A cationic surfactant assisted selective etching strategy to hollow mesoporous silica spheres.

    Science.gov (United States)

    Fang, Xiaoliang; Chen, Cheng; Liu, Zhaohui; Liu, Pengxin; Zheng, Nanfeng

    2011-04-01

    Hollow mesoporous silica spheres have recently attracted increasing attention. However, effective synthesis of uniform hollow mesoporous spheres with controllable well-defined pore structures for fundamental research and practical applications has remained a significant challenge. In this work, a straightforward and effective "cationic surfactant assisted selective etching" synthetic strategy was developed for the preparation of high-quality hollow mesoporous silica spheres with either wormhole-like or oriented mesoporous shell. The as-prepared hollow mesoporous silica spheres have large surface area, high pore volume, and controllable structure parameters. Our experiments demonstrated that cationic surfactant plays critical roles in forming the hollow mesoporous structure. A formation mechanism involving the etching of solid SiO(2) accelerated by cationic surfactant followed by the redeposition of dissolved silica species directed by cationic surfactant is proposed. Furthermore, the strategy can be extended as a general strategy to transform silica-coated composite materials into yolk-shell structures with either wormhole-like or oriented mesoporous shell.

  15. Cationization increases brain distribution of an amyloid-beta protofibril selective F(ab')2 fragment

    OpenAIRE

    Syvänen, Stina; Edén, Desireé; Sehlin, Dag

    2017-01-01

    Antibodies and fragments thereof are, because of high selectivity for their targets, considered as potential therapeutics and biomarkers for several neurological disorders. However, due to their large molecular size, antibodies/fragments do not easily penetrate into the brain. The aim of the present study was to improve the brain distribution via adsorptive-mediated transcytosis of an amyloid-beta (A beta) protofibril selective F(ab')2 fragment (F(ab')2-h158). F(ab')2-h158 was cationized to d...

  16. The effect of salt adaptation on the permeability and cation selectivity of the goldfish intestinal epithelium.

    Science.gov (United States)

    Ellory, J C; Nibelle, J; Smith, M W

    1973-05-01

    1. The short-term uptake of Na by the goldfish mucosa was compared using both inulin and choline as markers of extracellular space. The results were virtually identical, the distribution of both choline and inulin increasing rapidly to measure a space at 1 min which then remained nearly constant during a following 4 min incubation.2. Using inulin as space marker, the uptake of various alkali metal cations was determined from a 1 min contact with the mucosa. The relative rates of uptake were Tl > K > Rb > Cs > Na > Li, with a low selectivity ratio, the range of permeabilities being no greater than 5.3. The selectivity sequence was the same in both salt and fresh-water adapted fish. Of the alkali metal cations tested, only Na showed a significantly decreased uptake on adaptation to salt.4. Isolated intestinal preparations from salt-adapted fish showed a reduced short-circuit current compared with fish adapted to fresh water, the values being 12.3 +/- 1.2 and 35.7 +/- 1.5 muA cm(-2) respectively. In both cases the short-circuit current was equivalent to the net transport of Na measured isotopically.5. In Krebs-Henseleit medium, the measured tissue resistance was approximately 100 Omega cm(-2) for both salt and fresh-water adapted fish.6. It is concluded that regulation of cation transport in goldfish intestinal epithelium is specific for Na and mediated primarily through cellular rather than extracellular pathways.

  17. TRPM5 is a voltage-modulated and Ca(2+)-activated monovalent selective cation channel.

    Science.gov (United States)

    Hofmann, Thomas; Chubanov, Vladimir; Gudermann, Thomas; Montell, Craig

    2003-07-01

    The TRPM subfamily of mammalian TRP channels displays unusually diverse activation mechanisms and selectivities. One member of this subfamily, TRPM5, functions in taste receptor cells and has been reported to be activated through G protein-coupled receptors linked to phospholipase C. However, the specific mechanisms regulating TRPM5 have not been described. Here, we demonstrate that TRPM5 is a monovalent-specific cation channel with a 23 pS unitary conductance. TRPM5 does not display constitutive activity. Rather, it is activated by stimulation of a receptor pathway coupled to phospholipase C and by IP(3)-mediated Ca(2+) release. Gating of TRPM5 was dependent on a rise in Ca(2+) because it was fully activated by Ca(2+). Unlike any previously described mammalian TRP channel, TRPM5 displayed voltage modulation and rapid activation and deactivation kinetics upon receptor stimulation. The most closely related protein, the Ca(2+)-activated monovalent-selective cation channel TRPM4b, also showed voltage modulation, although with slower relaxation kinetics than TRPM5. Taken together, the data demonstrate that TRPM5 and TRPM4b represent the first examples of voltage-modulated, Ca(2+)-activated, monovalent cation channels (VCAMs). The voltage modulation and rapid kinetics provide TRPM5 with an excellent set of properties for participating in signaling in taste receptors and other excitable cells.

  18. Diphtheria toxin-induced channels in Vero cells selective for monovalent cations

    International Nuclear Information System (INIS)

    Sandvig, K.; Olsnes, S.

    1988-01-01

    Ion fluxes associated with translocation of diphtheria toxin across the surface membrane of Vero cells were studied. When cells with surface-bound toxin were exposed to low pH to induce toxin entry, the cells became permeable to Na+, K+, H+, choline+, and glucosamine+. There was no increased permeability to Cl-, SO4(-2), glucose, or sucrose, whereas the uptake of 45 Ca2+ was slightly increased. The influx of Ca2+, which appears to be different from that of monovalent cations, was reduced by several inhibitors of anion transport and by verapamil, Mn2+, Co2+, and Ca2+, but not by Mg2+. The toxin-induced fluxes of N+, K+, and protons were inhibited by Cd2+. Cd2+ also protected the cells against intoxication by diphtheria toxin, suggesting that the open cation-selective channel is required for toxin translocation. The involvement of the toxin receptor is discussed

  19. STRESS RELAXATION CHARACTERISTICS OF SELECTED COMMERCIALLY PRODUCED GLASSES

    Directory of Open Access Journals (Sweden)

    Chocholoušek J.

    2013-06-01

    Full Text Available This paper describes a quantitative method of stress relaxation measurement in prismatic glass samples during two different time-temperature regimes using the Sénarmont compensator. Four types of glass (Barium crystal glass, Eutal, Simax, and Container glass were subjected to observation in an assembled measuring device. Results will be used for parameterization of the Tool-Narayanaswamy-Mazurin model and consequently implemented in a finite element method code.

  20. Study on selective laser sintering of glass fiber reinforced polystyrene

    Science.gov (United States)

    Yang, Laixia; Wang, Bo; Zhou, Wenming

    2017-12-01

    In order to improve the bending strength of Polystyrene (PS) sintered parts by selective laser sintering, Polystyrene/glass fiber (PS/GF) composite powders were prepared by mechanical mixing method. The size distribution of PS/GF composite powders was characterized by laser particle size analyzer. The optimum ratio of GF was determined by proportioning sintering experiments. The influence of process parameters on the bending strength of PS and PS/GF sintered parts was studied by orthogonal test. The result indicates that the particle size of PS/GF composite powder is mainly distributed in 24.88 μm~139.8 μm. When the content of GF is 10%, it has better strengthen effect. Finally, the article used the optimum parameter of the two materials to sinter prototype, it is found that the PS/GF prototype has the advantages of good accuracy and high strength.

  1. Women's participation in parliament: 'Glass ceiling' syndrome and party selection

    Directory of Open Access Journals (Sweden)

    Čičkarić Lilijana

    2014-01-01

    Full Text Available The impact of 'glass ceiling' syndrome and party selection on participation of women in parliament and other political institutions are examined in this article. 'Glass ceiling' syndrome, which means invisible, but almost impenetrable border that women face in professional life, keeping them away from positions of influence and progress in career, is the main reason for the small number of women involved in politics. According to the focus of the research, there are three groups of barriers to women's political participation. Most researchers examine the influence of the political system, institutional and legal mechanisms, the question of their transparency and functional improvement. Significantly less frequent approach came from authors who are concentrated on the social and economic barriers, financial conditions and the broader social context. The third group consists of those who are considering the ideological and psychological barriers, patriarchal cultural patterns, traditional gender roles, self-confidence, ambition and women's desire to be involved in politics. Political parties are key actors in the process of discrimination against women, because they do not allow them to be selected in a number of political functions. There are many factors that determine that the issue of gender equality is variously interpreted in political parties. The most present are contextual and ideological factors, referring to a different definition of the status of women on the political agenda, the social climate in terms of gender equality and respect for human rights, the level of social development and political freedom. Then come organizational factors pertaining to the structure of parties, the manner in which the leadership is elected, whether there are internal women's pressure groups and lobbying, and are women leaders are visible on high positions in decision-making process. Finally, there are institutional-legal factors, which include the type

  2. Glass and Glass-Ceramic Materials from Simulated Composition of Lunar and Martian Soils: Selected Properties and Potential Applications

    Science.gov (United States)

    Ray, C. S.; Sen, S.; Reis, S. T.; Kim, C. W.

    2005-01-01

    In-situ resource processing and utilization on planetary bodies is an important and integral part of NASA's space exploration program. Within this scope and context, our general effort is primarily aimed at developing glass and glass-ceramic type materials using lunar and martian soils, and exploring various applications of these materials for planetary surface operations. Our preliminary work to date have demonstrated that glasses can be successfully prepared from melts of the simulated composition of both lunar and martian soils, and the melts have a viscosity-temperature window appropriate for drawing continuous glass fibers. The glasses are shown to have the potential for immobilizing certain types of nuclear wastes without deteriorating their chemical durability and thermal stability. This has a direct impact on successfully and economically disposing nuclear waste generated from a nuclear power plant on a planetary surface. In addition, these materials display characteristics that can be manipulated using appropriate processing protocols to develop glassy or glass-ceramic magnets. Also discussed in this presentation are other potential applications along with a few selected thermal, chemical, and structural properties as evaluated up to this time for these materials.

  3. Selective adsorption and release of cationic organic dye molecules on mesoporous borosilicates

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Manidipa; Pal, Nabanita; Bhaumik, Asim, E-mail: msab@iacs.res.in

    2012-08-01

    Mesoporous materials can play a pivotal role as a host material for delivery application to a specific part of a system. In this work we explore the selective adsorption and release of cationic organic dye molecules such as safranine T (ST) and malachite green (MG) on mesoporous borosilicate materials. The mesoporous silica SBA-15 and borosilicate materials (MBS) were prepared using non-ionic surfactant Pluronic P123 as template via evaporation induced self-assembly (EISA) method. After template removal the materials show high surface areas and in some cases ordered mesopores of dimensions ca. 6-7 nm. High surface area, mesoporosity and the presence of heteroatom (boron) help this mesoporous borosilicate material to adsorb high amount of cationic dye molecules at its surface from the respective aqueous solutions. Furthermore, the mesoporous borosilicate samples containing higher percentage adsorbed dyes show excellent release of ST or MG dye in simulated body fluid (SBF) solution at physiological pH = 7.4 and temperature 310 K. The adsorption and release efficiency of mesoporous borosilicate samples are compared with reference boron-free mesoporous pure silica material to understand the nature of adsorbate-adsorbent interaction at the surfaces. - Graphical abstract: Highly ordered 2D-hexagonal mesoporous borosilicate materials have been synthesized by using Pluronic P123 as template. The materials show very good adsorption and release of organic cationic dye molecules under physiological conditions. Highlights: Black-Right-Pointing-Pointer Highly ordered 2D-hexagonal mesoporous borosilicate. Black-Right-Pointing-Pointer Nonionic Pluoronic P123 templated mesoporous material. Black-Right-Pointing-Pointer Adsorption of organic dyes at the mesopore surface. Black-Right-Pointing-Pointer Controlled release of dyes under physiological pH and temperature. Black-Right-Pointing-Pointer Release of safranine T (ST) and malachite green (MG) dyes in simulated body fluids.

  4. Selected anionic and cationic surface active agents: case study on the Kłodnica sediments

    Directory of Open Access Journals (Sweden)

    Olkowska Ewa

    2017-03-01

    Full Text Available Surface active agents (surfactants are a group of chemical compounds, which are used as ingredients of detergents, cleaning products, cosmetics and functional products. After use, wastes containing surfactants or their degradation products are discharged to wastewater treatment plants or directly into surface waters. Due to their specific properties of SAAs, compounds are able to migrate between different environmental compartments such as soil, sediment, water or even living organisms and accumulate there. Surfactants can have a harmful effect on living organisms. They can connect with bioactive molecules and modify their function. Additionally, they have the ability to migrate into cells and cause their damage or death. For these reasons investigation of individual surfactants should be conducted. The presented research has been undertaken to obtain information about SAA contamination of sediment from the River Kłodnica catchment caused by selected anionic (linear alkylbenzene sulfonates (LAS C10-C13 and cationic (alkylbenzyldimethylammonium (BDMA-C12-16, alkyl trimethyl ammonium (DTMA, hexadecyl piridinium chloride (HP chlorides surfactants. This river flows through an area of the Upper Silesia Industrial Region where various companies and other institutions (e.g. coal mining, power plants, metallurgy, hospitals are located. To determine their concentration the following analytical tools have been applied: accelerated solvent extraction– solid phase extraction – high performance liquid chromatography – UV-Vis (anionic SAAs and conductivity (cationic SAAs detectors. In all sediments anionic SAAs have been detected. The concentrations of HTMA and BDMA-C16 in tested samples were higher than other cationic analytes. Generally, levels of surfactants with longer alkyl chains were higher and this observation can confirm their higher susceptibility to sorption on solid surfaces.

  5. Spectroscopy `outside the box': Towards wider application of NMR to minerals and glasses with abundant paramagnetic cations - Fe, Ni, Co, and Cu silicates

    Science.gov (United States)

    Stebbins, J. F.

    2017-12-01

    Since the early applications of solid-state NMR (Nuclear Magnetic Resonance) to silicates in the early 1980's, this powerful method has been widely applied to problems of short- to medium-range structure, particularly for materials in which order/disorder is critical, such as crystalline solid solutions, glasses, and even melts. However, almost all such work has been on materials with low (battery materials (C. Grey and others), and with some serendipitous discovery plus persistence to look far outside of "normal" parameter space, we have recently shown that high resolution, structurally informative spectra can actually be obtained for silicate, oxide, and phosphate solid solutions with moderate (0.1 up to 10%) contents of paramagnetic cations such as Fe2+, Ni2+, Co2+ and REE3+. Very recently we have extended this to observe some of the first quantitative NMR spectra of silicate minerals in which a paramagnetic transition metal is the major cation, obtaining useful data for a series of Cu2+ silicates, fayalite (Fe2SiO4) and Ni- and Co- equivalents of diopside (CaMSi2O6). New data for glasses of the latter compositions may be the first such accurate results for any transition metal-rich glass. Although we are still far from a detailed theoretical understanding of these data, the spectra for the glasses are quite different from those of the crystals, suggesting the possibility of medium-range ordering and clustering of NiO and CoO-rich regions. If this conclusion holds up, it may have major implications for thermodynamic models of activities of such components in melts, which in turn are important for a number of geothermometers and barometers based on mineral-melt partitioning.

  6. Glasses

    DEFF Research Database (Denmark)

    Dyre, Jeppe

    2004-01-01

    The temperature dependence of the viscosity of most glassforming liquids is known to depart significantly from the classical Arrhenius behaviour of simple fluids. The discovery of an unexpected correlation between the extent of this departure and the Poisson ratio of the resulting glass could lead...... to new understanding of glass ageing and viscous liquid dynamics....

  7. glasses

    Indian Academy of Sciences (India)

    composed of VO5 pyramids. The vanadates-based glasses show semiconducting ..... the composition 1 mol% of CeO2. The AC conductivity obeys a power law. The glass samples exhibit typical inor- ganic semiconducting behaviour. The activation energy and conductivity at room temperature were found to be 0.09 eV ...

  8. Overcharging below the nanoscale: Multivalent cations reverse the ion selectivity of a biological channel

    Science.gov (United States)

    García-Giménez, Elena; Alcaraz, Antonio; Aguilella, Vicente M.

    2010-02-01

    We report charge inversion within a nanoscopic biological protein ion channel in salts of multivalent ions. The presence of positive divalent and trivalent counterions reverses the cationic selectivity of the OmpF channel, a general diffusion porin located in the outer membrane of E. coli. We discuss the conditions under which charge inversion can be inferred from the change in sign of the measured quantity, the channel zero current potential. By comparing experimental results in protein channels whose charge has been modified after site-directed mutagenesis, the predictions of current theories of charge inversion are critically examined. It is emphasized that charge inversion does not necessarily increase with the bare surface charge density of the interface and that even this concept of surface charge density may become meaningless in some biological ion channels. Thus, any theory based on electrostatic correlations or chemical binding should explicitly take into account the particular structure of the charged interface.

  9. Aluminium and hydrogen ions inhibit a mechanosensory calcium-selective cation channel

    Science.gov (United States)

    Ding, J. P.; Pickard, B. G.

    1993-01-01

    The tension-dependent activity of mechanosensory calcium-selective cation channels in excised plasmalemmal patches from onion bulb scale epidermis is modulated by pH in the physiologically meaningful range between 4.5 and 7.2. It is rapidly lowered by lowering pH and rapidly raised by raising pH. Channel activity is effectively inhibited by low levels of aluminium ions and activity can be partially restored by washing for a few minutes. We suggest that under normal conditions the sensitivity of the mechanosensory channels to pH of the wall free space plays important roles in regulation of plant activities such as growth. We further suggest that, when levels of acid and aluminium ions in the soil solution are high, they might inhibit similar sensory channels in cells of the root tip, thus contributing critically to the acid soil syndrome.

  10. Qualitative and quantitative analysis of cations and anions using ion selective detectors in capillary electrophoresis

    International Nuclear Information System (INIS)

    Nann, A.

    1994-01-01

    The present work reports on the application of ion-selective microelectrodes as potentiometric detectors for the qualitative and quantitative analysis of cations and anions separated by capillary electrophoresis. Due to the high internal resistance of microelectrodes, their potentials are strongly affected by external electrical fields. Therefore, the influence of the electrophoretic field on the electrode response had to be kept at a minimum. With the electrode tip inserted in the capillary aperture (on-column detection), heavy drifts and noise of the signals were observed, mainly because the electrophoretic potential is superimposed on the Nernstian electrode response. As the potential inside the capillary is site-dependent, already minor movements and vibrations not perceptible under the light microscopy cause unacceptable disturbances of the electrode signal. One possibility to solve the problem consists in post- or off-column detection, i.e., with the detector located outside the influence of the electrophoretic field. If quantitative analyses with maximum resolution are to be achieved, only on-column detection is suitable because outside the capillary, the separation efficiency drops drastically. By etching the detector-side capillary end to a conical aperture, the field strength in the last 10 μm fell approximately 1/25 as compared with that in a cylindrical one. Thus, potential drifts and noise were reduced correspondingly so that on-column detection can also be used for potentiometric detection. To obtain quantitative results, the signals of the ion-selective detector were first delogarithmized and then integrated over time. Thus, it was possible to quantify cations and anions with a coefficient of variations ≤5%. (author) figs., tabs., 179 refs

  11. GLASS SELECTION STRATEGY: DEVELOPMENT OF US AND KRI TEST MATRICIES

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K; Tommy Edwards, T; David Peeler, D

    2007-02-06

    High-level radioactive wastes are stored as liquids in underground storage tanks at the Department of Energy's (DOE) Savannah River Site (SRS) and Hanford Reservation. These wastes are to be prepared for permanent disposition in a geologic repository by vitrification with glass forming additives (e.g., frit), creating a waste form with long-term durability. Wastes at SRS are being vitrified in the Defense Waste Processing Facility (DWPF). Vitrification of the wastes stored at Hanford is planned for the Waste Treatment and Immobilization Plant (WTP) when completed. Some of the wastes at SRS, and particularly those at Hanford, contain high concentrations of aluminum, chromium and sulfate. These elements make it more difficult to produce a waste glass with a high waste loading (WL) without crystallization occurring in the glass (either within the melter or upon cooling of the glass), potentially exceeding the solubility limit of critical components, having negative impacts on durability, and/or resulting in the formation of a sulfate salt layer on the molten glass surface. Although the overall scope of the task is focused on all three critical, chemical components, the current work will primarily address the potential for crystallization (e.g., nepheline and/or spinel) in high level waste (HLW) glasses. Recent work at the Savannah River National Laboratory (SRNL) and by other groups has shown that nepheline (NaAlSiO{sub 4}), which is likely to crystallize in high-alumina glasses, has a detrimental effect on the durability of the glass. The objective of this task is to develop glass formulations for specific SRS and Hanford waste streams to avoid nepheline formation while meeting waste loading and waste throughput expectations, as well as satisfying critical process and product performance related constraints. Secondary objectives of this task are to assess the sulfate solubility limit for the DWPF composition and spinel settling for the WTP composition. SRNL has

  12. Selectivity of externally facing ion-binding sites in the Na/K pump to alkali metals and organic cations.

    Science.gov (United States)

    Ratheal, Ian M; Virgin, Gail K; Yu, Haibo; Roux, Benoît; Gatto, Craig; Artigas, Pablo

    2010-10-26

    The Na/K pump is a P-type ATPase that exchanges three intracellular Na(+) ions for two extracellular K(+) ions through the plasmalemma of nearly all animal cells. The mechanisms involved in cation selection by the pump's ion-binding sites (site I and site II bind either Na(+) or K(+); site III binds only Na(+)) are poorly understood. We studied cation selectivity by outward-facing sites (high K(+) affinity) of Na/K pumps expressed in Xenopus oocytes, under voltage clamp. Guanidinium(+), methylguanidinium(+), and aminoguanidinium(+) produced two phenomena possibly reflecting actions at site III: (i) voltage-dependent inhibition (VDI) of outwardly directed pump current at saturating K(+), and (ii) induction of pump-mediated, guanidinium-derivative-carried inward current at negative potentials without Na(+) and K(+). In contrast, formamidinium(+) and acetamidinium(+) induced K(+)-like outward currents. Measurement of ouabain-sensitive ATPase activity and radiolabeled cation uptake confirmed that these cations are external K(+) congeners. Molecular dynamics simulations indicate that bound organic cations induce minor distortion of the binding sites. Among tested metals, only Li(+) induced Na(+)-like VDI, whereas all metals tested except Na(+) induced K(+)-like outward currents. Pump-mediated K(+)-like organic cation transport challenges the concept of rigid structural models in which ion specificity at site I and site II arises from a precise and unique arrangement of coordinating ligands. Furthermore, actions by guanidinium(+) derivatives suggest that Na(+) binds to site III in a hydrated form and that the inward current observed without external Na(+) and K(+) represents cation transport when normal occlusion at sites I and II is impaired. These results provide insights on external ion selectivity at the three binding sites.

  13. Structure-Selective Cation Exchange in the Synthesis of Zincblende MnS and CoS Nanocrystals.

    Science.gov (United States)

    Fenton, Julie L; Schaak, Raymond E

    2017-06-01

    The ability to selectively form one crystal structure among several options in a polymorphic system is an important goal in solid-state synthesis. Nanocrystal cation exchange, which proceeds rapidly under mild conditions, can retain key structural features and yield otherwise inaccessible phases, but the extent to which crystal structure can be retained and therefore selectively targeted during such reactions has been limited. Here, we show that nanocrystals of digenite Cu 2-x S transform to zincblende MnS and CoS upon cation exchange. Zincblende MnS and CoS, which are metastable in bulk, retain both the tetrahedral cation coordination and cubic close packed anion sublattice of digenite Cu 2-x S. Comparison with wurtzite MnS and CoS, which have been accessed previously through analogous cation exchange of roxbyite Cu 2-x S, demonstrates the selective formation of the related zincblende vs. wurtzite polymorphs by cation exchange of structurally distinct templates. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Energy Saving Glass Lamination via Selective Radio-Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Shulman, Holly S.; Allan, Shawn M.

    2009-11-11

    This Inventions and Innovations program supported the technical and commercial research and development needed to elevate Ceralink's energy saving process for flat glass lamination from bench scale to a self-supporting technology with significant potential for growth. Radio-frequency heating was any un-explored option for laminating glass prior to this program. With significant commercial success through time and energy savings in the wood, paper, and plastics industries, RF heating was found to have significant promise for the energy intensive glass lamination industry. A major technical goal of the program was to demonstrate RF lamination across a wide range of laminate sizes and materials. This was successfully accomplished, dispelling many skeptics' concerns about the abilities of the technology. Ceralink laminated panels up to 2 ft x 3 ft, with four sets processed simultaneously, in a 3 minute cycle. All major categories of interlayer materials were found to work with RF lamination. In addition to laminating glass, other materials including photovoltaic silicon solar cells, light emitting diodes, metallized glass, plastics (acrylic and polycarbonate), and ceramics (alumina) were found compatible with the RF process. This opens up a wide range of commercial opportunities beyond the initially targeted automotive industry. The dramatic energy savings reported for RF lamination at the bench scale were found to be maintained through the scale up of the process. Even at 2 ft x 3 ft panel sizes, energy savings are estimated to be at least 90% compared to autoclaving or vacuum lamination. With targeted promotion through conference presentations, press releases and internet presence, RF lamination has gained significant attention, drawing large audiences at American Ceramic Society meetings. The commercialization success of the project includes the establishment of a revenue-generating business model for providing process development and demonstrations for

  15. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Allan, Shawn M.

    2012-02-27

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North

  16. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Allan, Shawn M; Baranova, Inessa; Poley, Joseph; Reis, Henrique

    2012-02-27

    This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North

  17. Energy Saving Glass Lamination via Selective Radio Frequency Heating

    Energy Technology Data Exchange (ETDEWEB)

    Shawn M. Allan; Patricia M. Strickland; Holly S. Shulman

    2009-11-11

    Ceralink Inc. developed FastFuse™, a rapid, new, energy saving process for lamination of glass and composites using radio frequency (RF) heating technology. The Inventions and Innovations program supported the technical and commercial research and development needed to elevate the innovation from bench scale to a self-supporting technology with significant potential for growth. The attached report provides an overview of the technical and commerical progress achieved for FastFuse™ during the course of the project. FastFuse™ has the potential to revolutionize the laminate manufacturing industries by replacing energy intensive, multi-step processes with an energy efficient, single-step process that allows higher throughput. FastFuse™ transmits RF energy directly into the interlayer to generate heat, eliminating the need to directly heat glass layers and the surrounding enclosures, such as autoclaves or vacuum systems. FastFuse™ offers lower start-up and energy costs (up to 90% or more reduction in energy costs), and faster cycles times (less than 5 minutes). FastFuse™ is compatible with EVA, TPU, and PVB interlayers, and has been demonstrated for glass, plastics, and multi-material structures such as photovoltaics and transparent armor.

  18. glasses

    Indian Academy of Sciences (India)

    materials and electrochemical batteries.8 Rare earth metal ions when added to borate act as network modifiers and change the properties of glasses. In rare earth ... room temperature to 600◦C. For electrical measurements, samples were polished and conducting silver paste was deposited on both sides. The sample area ...

  19. A New Microfluidic Polymer Chip with an Embedded Cationic Surfactant Ion-selective Optode as a Detector for the Determination of Cationic Surfactants.

    Science.gov (United States)

    Ashagre, Mekonnen Abiyot; Masadome, Takashi

    2018-01-01

    A new microfluidic polymer chip with an embedded cationic surfactant (CS) ion-selective optode (CS-optode) as a detector of flow-injection analysis (FIA) for the determination of CSs was developed. The optode sensing membrane is based on a poly(vinyl chloride) membrane plasticized with 2-nitrophenyl octyl ether containing tetrabromophenolphthalein ethyl ester. Under the optimal flow conditions of the FIA system, the CS-optode showed a good linear relationship between the peak heights in the absorbance, and the concentrations of CS in a concentration range from 50 to 400 μmol dm -3 . The sample throughput of the present system for the determination of a CS ion (300 μmol dm -3 zephiramine) was ca. 11 samples h -1 . The proposed FIA system was applied to determine the level of CS in dental rinses.

  20. Glass

    OpenAIRE

    Parker, K

    2010-01-01

    Audio recording of the sea from the breakwater in Plymouth Sound, by Stuart Moore. Presentations and exhibitions of the film Glass include: Finding Place exhibition, Plymouth (3 > 26 February 2010); University of the West of England's Radical British Screens symposium (3 September 2010); Plymouth University Festival of Research: Materiality and Technology film programme presented by the Centre for Media Art and Design Research (MADr), Jill Craigie Cinema, Plymouth University (14 March 2011); ...

  1. An on-line monitor for cation exchange elution chromatography using lithium silicate glass beads as solid scintillator

    International Nuclear Information System (INIS)

    Zhu Rongbao; Yang Liucheng; Wei Liansheng; Ji Liqiang; Zhang Zengrui

    1988-03-01

    A new type of on-line monitoring system used to monitor radioactive nuclides with α or soft β radiation in the effluent from a high pressure ion exchange column is described. The beads made of cerium-impregnated lithium silicate glass are used as scientillation material. They are filled into a quartz glass tube to form a flow cell. By reducing the diameter of glass beads to more closly approximate the average range of α or soft β radiation in solution, the absolute counting efficiency for 241 Am, 242 Cm α radiation have reached and 85.8% and 92.8% respectively, for 14 C, 90 Sr- 90 Y β radiation, 62.1% and 88.6% respectively. These values can be comparable to those achieved with on-line liquid scientillation technique. When the total amount of 241 Am added into column is decreased to 7.4 Bq it is still possible to obtain a clear chromatography peak (half peak width = 0.22 mL)

  2. Radiation impact on the characteristics of optical glasses test results on a selected set of materials

    Science.gov (United States)

    Fruit, Michel; Gussarov, Andrei; Berghmans, Francis; Doyle, Dominic; Ulbrich, Gerd

    2017-11-01

    It is well known within the Space optics community that radiation may significantly affect transmittance of glasses. To overcome this drawback, glass manufacturers have developed Cerium doped counterparts of classical glasses. This doped glasses display much less transmittance sensitivity to radiation. Still, the impact of radiation on refractive index is less known and may affect indifferently classical or Cerium doped glasses. ESTEC has initialised an R&D program with the aim of establishing a comprehensive data base gathering radiation sensitivity data, called Dose coefficients, for all the glass optical parameters (transmittance / refractive index / compaction……). The first part of this study, to define the methodology for such a data base, is run by ASTRIUM SAS in co-operation with SCK CEN. This covers theoretical studies associated to testing of a selected set of classical and "radiation hardened" glasses. It is proposed here to present first the theoretical backgrounds of this study and then to give results which have been obtained so far.

  3. Solvent-Free Selective Oxidation of Toluene with O2 Catalyzed by Metal Cation Modified LDHs and Mixed Oxides

    Directory of Open Access Journals (Sweden)

    Xiaoli Wang

    2016-01-01

    Full Text Available A series of metal cation modified layered-double hydroxides (LDHs and mixed oxides were prepared and used to be the selective oxidation of toluene with O2. The results revealed that the modified LDHs exhibited much higher catalytic performance than their parent LDH and the modified mixed oxides. Moreover, the metal cations were also found to play important roles in the catalytic performance and stabilities of modified catalysts. Under the optimal reaction conditions, the highest toluene conversion reached 8.7% with 97.5% of the selectivity to benzyldehyde; moreover, the catalytic performance remained after nine catalytic runs. In addition, the reaction probably involved a free-radical mechanism.

  4. Selective Antimicrobial Activities and Action Mechanism of Micelles Self-Assembled by Cationic Oligomeric Surfactants.

    Science.gov (United States)

    Zhou, Chengcheng; Wang, Fengyan; Chen, Hui; Li, Meng; Qiao, Fulin; Liu, Zhang; Hou, Yanbo; Wu, Chunxian; Fan, Yaxun; Liu, Libing; Wang, Shu; Wang, Yilin

    2016-02-17

    This work reports that cationic micelles formed by cationic trimeric, tetrameric, and hexameric surfactants bearing amide moieties in spacers can efficiently kill Gram-negative E. coli with a very low minimum inhibitory concentration (1.70-0.93 μM), and do not cause obvious toxicity to mammalian cells at the concentrations used. With the increase of the oligomerization degree, the antibacterial activity of the oligomeric surfactants increases, i.e., hexameric surfactant > tetrameric surfactant > trimeric surfactant. Isothermal titration microcalorimetry, scanning electron microscopy, and zeta potential results reveal that the cationic micelles interact with the cell membrane of E. coli through two processes. First, the integrity of outer membrane of E. coli is disrupted by the electrostatic interaction of the cationic ammonium groups of the surfactants with anionic groups of E. coli, resulting in loss of the barrier function of the outer membrane. The inner membrane then is disintegrated by the hydrophobic interaction of the surfactant hydrocarbon chains with the hydrophobic domains of the inner membrane, leading to the cytoplast leakage. The formation of micelles of these cationic oligomeric surfactants at very low concentration enables more efficient interaction with bacterial cell membrane, which endows the oligomeric surfactants with high antibacterial activity.

  5. Development of phosphate glass microspheres containing holmium for selective internal radiotherapy

    International Nuclear Information System (INIS)

    Barros Filho, Eraldo Cordeiro

    2016-01-01

    The selective internal radiotherapy is an alternative for some kinds of cancer as the hepatocellular carcinoma (HCC) or primary liver cancer treatment. In this treatment, glass or polymer microspheres containing radionuclides inside their structure are introduced in the liver through hepatic artery and trapped at the arterioles that feed the tumor. In this work, the development of phosphate glasses containing holmium for production of microspheres and their application in Brazil are proposed. The developed glasses presented suitable chemical durability, density of 2,7(3) g/cm 3 , high thermal stability and the impurities contained therein do not preclude the treatment. The microspheres were produced by the flame method and the gravitational fall method, and were characterized by means of several techniques to evaluate shape, average particle size, activity and biocompatibility suitable for selective internal radiotherapy. Based in the main results, the submission to in vivo tests is proposed. (author)

  6. Enhanced fluorescence of selected cationic dyes adsorbed on reduced-charge montmorillonite

    Czech Academy of Sciences Publication Activity Database

    Pustková, P.; Klika, Z.; Preclíková, J.; Matys Grygar, Tomáš

    2011-01-01

    Roč. 46, č. 1 (2011), s. 93-103 ISSN 0009-8558 Institutional research plan: CEZ:AV0Z40320502 Keywords : cationic dye * crystal violet * Nile blue * rhodamine B * reduced-charge montmorillonite * visible spectrophotometry * fluorescence Subject RIV: DD - Geochemistry Impact factor: 1.053, year: 2011

  7. Correction: A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide.

    Science.gov (United States)

    Ng, Chee Koon; Wu, Jie; Hor, T S Andy; Luo, He-Kuan

    2016-12-22

    Correction for 'A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide' by Chee Koon Ng et al., Chem. Commun., 2016, 52, 11842-11845.

  8. Synthesis and characterization of two new tetrapyrazolic macrocycles for the selective extraction of cesium cation

    Czech Academy of Sciences Publication Activity Database

    Harit, T.; Malek, F.; El Bali, B.; Dušek, Michal; Kučeráková, Monika

    2016-01-01

    Roč. 72, č. 27-28 (2016), s. 3966-3973 ISSN 0040-4020 R&D Projects: GA MŠk LO1603; GA ČR(CZ) GA14-03276S EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:68378271 Keywords : cesium cation * liquid–liquid extraction * macrocycle * pyrazole * crystal structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.651, year: 2016

  9. Pressure-Induced Amorphization of Small Pore Zeolites-the Role of Cation-H2O Topology and Anti-glass Formation.

    Science.gov (United States)

    Chan Hwang, Gil; Joo Shin, Tae; Blom, Douglas A; Vogt, Thomas; Lee, Yongjae

    2015-10-12

    Systematic studies of pressure-induced amorphization of natrolites (PIA) containing monovalent extra-framework cations (EFC) Li(+), Na(+), K(+), Rb(+), Cs(+) allow us to assess the role of two different EFC-H2O configurations within the pores of a zeolite: one arrangement has H2O molecules (NATI) and the other the EFC (NATII) in closer proximity to the aluminosilicate framework. We show that NATI materials have a lower onset pressure of PIA than the NATII materials containing Rb and Cs as EFC. The onset pressure of amorphization (PA) of NATII materials increases linearly with the size of the EFC, whereas their initial bulk moduli (P1 phase) decrease linearly. Only Cs- and Rb-NAT reveal a phase separation into a dense form (P2 phase) under pressure. High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) imaging shows that after recovery from pressures near 25 and 20 GPa long-range ordered Rb-Rb and Cs-Cs correlations continue to be present over length scales up to 100 nm while short-range ordering of the aluminosilicate framework is significantly reduced-this opens a new way to form anti-glass structures.

  10. ENHANCED DOE HIGH LEVEL WASTE MELTER THROUGHPUT STUDIES: SRNL GLASS SELECTION STRATEGY

    Energy Technology Data Exchange (ETDEWEB)

    Raszewski, F; Tommy Edwards, T; David Peeler, D

    2008-01-23

    The Department of Energy has authorized a team of glass formulation and processing experts at the Savannah River National Laboratory (SRNL), the Pacific Northwest National Laboratory (PNNL), and the Vitreous State Laboratory (VSL) at Catholic University of America to develop a systematic approach to increase high level waste melter throughput (by increasing waste loading with minimal or positive impacts on melt rate). This task is aimed at proof-of-principle testing and the development of tools to improve waste loading and melt rate, which will lead to higher waste throughput. Four specific tasks have been proposed to meet these objectives (for details, see WSRC-STI-2007-00483): (1) Integration and Oversight, (2) Crystal Accumulation Modeling (led by PNNL)/Higher Waste Loading Glasses (led by SRNL), (3) Melt Rate Evaluation and Modeling, and (4) Melter Scale Demonstrations. Task 2, Crystal Accumulation Modeling/Higher Waste Loading Glasses is the focus of this report. The objective of this study is to provide supplemental data to support the possible use of alternative melter technologies and/or implementation of alternative process control models or strategies to target higher waste loadings (WLs) for the Defense Waste Processing Facility (DWPF)--ultimately leading to higher waste throughputs and a reduced mission life. The glass selection strategy discussed in this report was developed to gain insight into specific technical issues that could limit or compromise the ability of glass formulation efforts to target higher WLs for future sludge batches at the Savannah River Site (SRS). These technical issues include Al-dissolution, higher TiO{sub 2} limits and homogeneity issues for coupled-operations, Al{sub 2}O{sub 3} solubility, and nepheline formation. To address these technical issues, a test matrix of 28 glass compositions has been developed based on 5 different sludge projections for future processing. The glasses will be fabricated and characterized based on

  11. Electrofluidics fabricated by space-selective metallization in glass microfluidic structures using femtosecond laser direct writing.

    Science.gov (United States)

    Xu, Jian; Wu, Dong; Hanada, Yasutaka; Chen, Chi; Wu, Sizhu; Cheng, Ya; Sugioka, Koji; Midorikawa, Katsumi

    2013-12-07

    Space-selective metallization of the inside of glass microfluidic structures using femtosecond laser direct-write ablation followed by electroless plating is demonstrated. Femtosecond laser direct writing followed by thermal treatment and successive chemical etching allows us to fabricate three-dimensional microfluidic structures inside photosensitive glass. Then, femtosecond laser ablation followed by electroless metal plating enables flexible deposition of patterned metal films on desired locations of not only the top and bottom walls but also the sidewalls of fabricated microfluidic structures. A volume writing scheme for femtosecond laser irradiation inducing homogeneous ablation on the sidewalls of microfluidic structures is proposed for sidewall metallization. The developed technique is used to fabricate electrofluidics in which microelectric components are integrated into glass microchannels. The fabricated electrofluidics are applied to control the temperature of liquid samples in the microchannels for the enhancement of chemical reactions and to manipulate the movement of biological samples in the microscale space.

  12. Characterization of a C-type natriuretic peptide (CNP-39)-formed cation-selective channel from platypus (Ornithorhynchus anatinus) venom

    Science.gov (United States)

    Kourie, Joseph I

    1999-01-01

    The lipid bilayer technique is used to characterize the biophysical and pharmacological properties of a novel, fast, cation-selective channel formed by incorporating platypus (Ornithorhynchus anatinus) venom (OaV) into lipid membranes.A synthetic C-type natriuretic peptide OaCNP-39, which is identical to that present in platypus venom, mimics the conductance, kinetics, selectivity and pharmacological properties of the OaV-formed fast cation-selective channel. The N-terminal fragment containing residues 1-17, i.e. OaCNP-39(1-17), induces the channel activity.The current amplitude of the TEACl-insensitive fast cation-selective channel is dependent on cytoplasmic K+, [K+]cis. The increase in the current amplitude, as a function of increasing [K+]cis, is non-linear and can be described by the Michaelis-Menten equation. At +140 mV, the values of γmax and KS are 63·1 pS and 169 mM, respectively, whereas at 0 mV the values of γmax and KS are 21·1 pS and 307 mM, respectively. γmax and KS are maximal single channel conductance and concentration for half-maximal γ, respectively. The calculated permeability ratios, PK:PRb:PNa: PCs:PLi, were 1:0·76:0·21:0·09:0·03, respectively.The probability of the fast channel being open, Po, increases from 0·15 at 0 mV to 0·75 at +140 mV. In contrast, the channel frequency, Fo, decreases from 400 to 180 events per second for voltages between 0 mV and +140. The mean open time, To, increases as the bilayer is made more positive, between 0 and +140 mV. The mean values of the voltage-dependent kinetic parameters, Po, Fo, To and mean closed time (Tc), are independent of [KCl]cis between 50 and 750 mM (P > 0·05).It is proposed that some of the symptoms of envenomation by platypus venom may be caused partly by changes in cellular functions mediated via the OaCNP-39-formed fast cation-selective channel, which affects signal transduction. PMID:10381585

  13. Glass sealing

    Energy Technology Data Exchange (ETDEWEB)

    Brow, R.K.; Kovacic, L.; Chambers, R.S. [Sandia National Labs., Albuquerque, NM (United States)

    1996-04-01

    Hernetic glass sealing technologies developed for weapons component applications can be utilized for the design and manufacture of fuel cells. Design and processing of of a seal are optimized through an integrated approach based on glass composition research, finite element analysis, and sealing process definition. Glass sealing procedures are selected to accommodate the limits imposed by glass composition and predicted calculations.

  14. Non-selective cation channels and oxidative stress- induced cell swelling

    Directory of Open Access Journals (Sweden)

    FELIPE SIMON

    2002-01-01

    Full Text Available Necrosis is considered as a non-specific form of cell death that induces tissue inflammation and is preceded by cell swelling. This increase in cell volume has been ascribed mainly to defective outward pumping of Na+ caused by metabolic depletion and/or to increased Na+ influx via membrane transporters. A specific mechanism of swelling and necrosis driven by the influx of Na+ through nonselective cation channels has been recently proposed (Barros et al., 2001a. We have characterized further the properties of the nonselective cation channel (NSCC in HTC cells. The NSCC shows a conductance of ~18 pS, is equally permeable to Na+ and K+, impermeant to Ca2+, requires high intracellular Ca2+ as well as low intracellular ATP for activation and is inhibited by flufenamic acid. Hydrogen peroxide induced a significant increase in cell volume that was dependent on external Na+. We propose that the NSCC, which is ubiquitous though largely inactive in healthy cells, becomes activated under severe oxidative stress. The ensuing Na+ influx initiates via positive feedback a series of metabolic and electrolytic disturbances, resulting in cell death by necrosis

  15. A Molecular Dynamics Study on Selective Cation Depletion from an Ionic Liquid Droplet under an Electric Field

    Science.gov (United States)

    Yang, Yudong; Ahn, Myungmo; Im, Dojin; Oh, Jungmin; Kang, Inseok

    2017-11-01

    General electrohydrodynamic behavior of ionic liquid droplets under an electric field is investigated using MD simulations. Especially, a unique behavior of ion depletion of an ionic liquid droplet under a uniform electric field is studied. Shape deformation due to electric stress and ion distributions inside the droplet are calculated to understand the ionic motion of imidazolium-based ionic liquid droplets with 200 ion pairs of 2 kinds of ionic liquids: EMIM-NTf2 and EMIM-ES. The intermolecular force between cations and anions can be significantly different due to the nature of the structure and charge distribution of the ions. Together with an analytical interpretation of the conducting droplet in an electric field, the MD simulation successfully explains the mechanism of selective ion depletion of an ionic liquid droplet in an electric field. The selective ion depletion phenomenon has been adopted to explain the experimentally observed retreating motion of a droplet in a uniform electric field. The effect of anions on the cation depletion phenomenon can be accounted for from a direct approach to the intermolecular interaction. This research was supproted by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP) (No. 2017R1D1A1B05035211).

  16. Development of a novel bioactive glass for air-abrasion to selectively remove orthodontic adhesives.

    Science.gov (United States)

    Taha, Ayam A; Hill, Robert G; Fleming, Padhraig S; Patel, Mangala P

    2018-05-01

    To develop a novel, bioactive glass for removing residual orthodontic adhesive via air-abrasion, following bracket debonding, and to evaluate its effectiveness against a proprietary bioactive glass 45S5(Sylc™)-air-abrasion, and a slow-speed tungsten carbide (TC) bur. Three glasses were prepared and their bioactivity was proved. One novel glass (QMAT3) was selected due to its appropriate hardness, lower than that of enamel/45S5(Sylc™). Sixty extracted human premolars were randomly assigned to adhesive removal using: (a) QMAT3-air-abrasion, (b) 45S5(Sylc™)-air-abrasion, and (c) TC bur, which were further subdivided (n = 10) based on the adhesive used (Transbond XT™ or Fuji Ortho LC™). Enamel roughness was assessed using scanning electron microscopy (SEM) and non-contact profilometry before bracket bonding, after removing residual adhesive following bracket debonding and after polishing. QMAT3 formed apatite faster (6 h) than 45S5(Sylc™) (24 h) in Tris solution. QMAT3-air-abrasion gave the lowest enamel roughness (Ra) after removing the adhesives. SEM images showed a pitted, roughened enamel surface in the TC bur group and to a lesser extent with 45S5(Sylc™), while a virtually smooth surface without any damage was observed in the QMAT3-air-abrasion group. The time taken for adhesive removal with QMAT3 was comparable to 45S5(Sylc™) but was twice as long with the TC bur. QMAT3-air-abrasion is a promising technique for selective removal of adhesives without inducing tangible enamel damage. A novel bioactive glass has been developed as an alternative to the use of TC burs for orthodontic adhesive removal.

  17. ESR and electronic spectra of alkane radical cations formed in γ-irradiated 3-methylpentane and 3-methylhexane glasses containing alkane solutes

    International Nuclear Information System (INIS)

    Ichikawa, T.; Ohta, N.

    1987-01-01

    Electron spin resonance (ESR) and optical difference spectra of photobleaching are measured, and the radical cations from some higher alkanes (C 9 -C 11 ) and some methyl-branched butanes are found to be trapped in 3-methylpentane or 3-methylhexane matrices at 77 K. The ESR spectra show close agreement with those of radical cations produced in CCl 2 FCClF 2 matrices. The cations of methyl-branched butanes give the absorption bands with λ/sub max/ ranging from 300 to 260 nm and the bands are attributed to σ-localized cations, while the higher alkane cation bands appearing in the near-IR region are ascribed to σ-delocalized cations. The cations of higher alkanes are found to be mobilized by light with λ > 900 nm to recombine with the negative ions formed by electron scavenging

  18. Selective adsorption and ion exchange of metal cations and anions with silico-titanates and layered titanates

    International Nuclear Information System (INIS)

    Anthony, R.G.; Philip, C.V.

    1993-01-01

    Metal ions may be removed from aqueous wastes from metal processing plants and from refineries. They may also be used in concentrating radioactive elements found in dilute, aqueous, nuclear wastes. A new series of silico-titanates and alkali titanates are shown to have specific selectivity for cations of lead, mercury, and cadmium and the dichromate anion in solutions with low and high pH. Furthermore, one particular silico-titanate, TAM-5, was found to be highly selective for Cs + and Sr 2+ in solutions of 5.7 M Na + and 0.6 M Oh - . A high potential exists for these materials for removing Cs + and Sr 2+ from radioactive aqueous wastes containing high concentrations of Na + at high and low pH

  19. Aqueous corrosion of french R7T7 nuclear waste glass: selective then congruent dissolution by pH increase

    International Nuclear Information System (INIS)

    Advocat, T.; Vernaz, E.; Crovisier, J.L.

    1991-01-01

    A study of the corrosion of a borosilicate nuclear glass shows the strong effect of the pH on the dissolution mechanism. Acidic media lead to selective extraction of the glass modifier elements (Li, Na, Ca) as well as B, while dissolution is congruent under alkaline conditions. The silica dissolution rate significantly increases with increasing pH [fr

  20. Selection of the Composition with High Glass Forming Ability in Zr-Cu-Ni-Al Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Yajuan Sun

    2014-01-01

    Full Text Available Three new Zr-Cu-Ni-Al bulk metallic glasses were developed through appropriate mixing of three binary eutectics Zr38.2Cu61.8, Zr51Al49, and Zr64Ni36. By suppressing solidification of competing crystalline phases, a new glass forming alloy Zr51Cu24.22Ni14.06Al10.72 with the critical diameter of up to 10 mm is obtained.

  1. Selective adsorption of cationic dyes from aqueous solution by polyoxometalate-based metal–organic framework composite

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaoxia; Gong, Wenpeng; Luo, Jing; Zou, Chentao; Yang, Yun; Yang, Shuijin, E-mail: yangshuijin@163.com

    2016-01-30

    Graphical abstract: Selective adsorption ability of H{sub 6}P{sub 2}W{sub 18}O{sub 62}/MOF-5 toward MO (a), Rhb (b) and the removal rate of Rhb, MO and MB (c). - Highlights: • Using metal–organic framework (MOF) composite as an adsorbent was investigated. • Selective adsorption ability of the composite towards cationic dyes was proposed. • The removal rate of MOF was raised greatly by the modification of polyoxometalate. • The adsorption kinetic and isotherm were used to describe the adsorption process. • The thermodynamic parameters of the composite were investigated in detail. - Abstract: A novel environmental friendly adsorbent H{sub 6}P{sub 2}W{sub 18}O{sub 62}/MOF-5 was synthesized by a simple one-step reaction under solvothermal conditions and characterized by XRD, FTIR, thermogravimetric analyses (TGA) and N{sub 2} adsorption–desorption isotherms. The removal rate of H{sub 6}P{sub 2}W{sub 18}O{sub 62}/MOF-5 was quite greater (85%) than that of MOF-5 (almost zero), showing that the adsorption performance of porous MOF-5 can be improved through the modification of H{sub 6}P{sub 2}W{sub 18}O{sub 62}. Further study revealed that H{sub 6}P{sub 2}W{sub 18}O{sub 62}/MOF-5 exhibited a fast adsorption rate and selective adsorption ability towards the cationic dyes in aqueous solution. The removal rate was up to 97% for cationic dyes methylene blue (MB) and 68% for rhodamine B(Rhb) within 10 min. However, anionicdye methyl orange(MO) can only reach to 10%. The influences including initial concentration, contact time, initial solution pH and temperature of MB adsorption onto H{sub 6}P{sub 2}W{sub 18}O{sub 62}/MOF-5 were investigated in detail. The kinetic study indicated that the adsorption of MB onto H{sub 6}P{sub 2}W{sub 18}O{sub 62}/MOF-5 followed the pseudo second-order model well. The isotherm obtained from experimental data fitted the Langmuir model, yielding maximum adsorption capacity of 51.81 mg/g. The thermodynamic parameters analysis

  2. Development and evaluation of holmium doped phosphate glass microspheres for selective internal radiotherapy

    International Nuclear Information System (INIS)

    Barros Filho, Eraldo C.; Martinelli, Jose Roberto; Squair, Peterson L; Osso Junior, Joao A.; Sene, Frank Ferrer

    2013-01-01

    Selective Internal Radiotherapy is used to treat hepatocellular carcinoma. In this treatment 90 Y -doped aluminosilicate glass microspheres are introduced in the hepatic artery and they migrate to the liver near to the tumor where they are trapped in the arterioles. The radiation β- emitted by the decay of 90 Y annihilates the cancer cells. A macroaggregate of albumin containing technetium is previously used to monitor the lung shunt and to prevent the spreading of 90 Y during the treatment. In the present work, 165 Ho- doped phosphate glass microspheres were developed aiming that application. 165 Ho has high cross section for neutron capture (64 bars) and 166 Ho decays emitting β- radiation with appropriate energy for killing cancer cells, and gamma rays with low energy which can be used to obtain images of the microspheres location and to check possible occurrence of lung shunt. Holmium also is highly paramagnetic and can be used to obtain images whereby NMR. The glass matrix consists of (P 2 O 5 ) tetrahedrons and can be produced by a relatively lower melting temperature of chemical compounds. The 31 P decays by emitting β- radiation and contributes to the absorbed dose, helping to annihilate the cancer cells. The microspheres were produced by using two methods: the flame and the gravitation falling methods to obtain microspheres with appropriate properties. (author)

  3. Modeling of cesium sorption on biotite using cation exchange selectivity coefficients

    Energy Technology Data Exchange (ETDEWEB)

    Kylloenen, Jarkko; Hakanen, Martti; Harjula, Risto; Lehto, Jukka [Helsinki Univ. (Finland). Lab. of Radiochemistry; Lindberg, Antero [Geological Survey of Finland, Espoo (Finland); Vehkamaeki, Marko [Helsinki Univ. (Finland). Lab. of Inorganic Chemistry

    2014-07-01

    For the modeling of cesium sorption on biotite, samples of natural biotite separated from gneissic rocks were converted into monoionic potassium, sodium, and calcium forms, and sorption isotherms for Cs/K, Cs/Na and Cs/Ca exchange were determined at pH 6 and 8 in 10{sup -4}-10{sup -8} M Cs solutions. Selectivity coefficients for Cs/K, Cs/Na, and Cs/Ca ion exchange reactions were calculated from the isotherm data, using the Gaines-Thomas convention. At Cs loadings below 1% of the total ion exchange capacity, the overall selectivity coefficient for Cs/Ca exchange was approximately five and seven orders of magnitude higher than those for Cs/Na and Cs/K exchange, respectively. Based on the selectivity coefficients, the ion exchange isotherms were modeled with the U.S. Geological Survey PhreeqC program, assuming three different types of ion exchange site: sites on the basal planes on biotite crystal surfaces with 95% site abundance, probable interlayer sites on crystal edges [frayed edge sites (FESs)] (0.02%) and third-type sites (5%), the physical background of which is unclear. Of these three types, the FES sites were superior in Cs selectivity, while the planar sites exhibited the lowest selectivity, and the third-type sites had selectivity between these two. The functionality of the model was successfully verified by modeling the Cs sorption isotherms on crushed mica gneiss rock in saline groundwater. Determination of the exchangeable ions K, Na, Ca, and Cs on the basal plane and edge surfaces by scanning electron microscopy-energy-dispersive x-ray spectroscopy (SEM-EDX) supports the results of modeling: edge sites highly prefer Cs ions and also Ca and Na ions but not K ions.

  4. Polyacrylonitrile (PAN)/crown ether composite nanofibers for the selective adsorption of cations

    NARCIS (Netherlands)

    Tas, Sinem; Kaynan, Ozge; Ozden-Yenigun, Elif; Nijmeijer, Dorothea C.

    2016-01-01

    In this study, we prepared electrospun polyacrylonitrile (PAN) nanofibers functionalized with dibenzo-18-crown-6 (DB18C6) crown ether and showed the potential of these fibers for the selective recovery of K+ from other both mono- and divalent ions in aqueous solutions. Nanofibers were characterized

  5. Actinide cation-cation complexes

    International Nuclear Information System (INIS)

    Stoyer, N.J.; Seaborg, G.T.

    1994-12-01

    The +5 oxidation state of U, Np, Pu, and Am is a linear dioxo cation (AnO 2 + ) with a formal charge of +1. These cations form complexes with a variety of other cations, including actinide cations. Other oxidation states of actinides do not form these cation-cation complexes with any cation other than AnO 2 + ; therefore, cation-cation complexes indicate something unique about AnO 2 + cations compared to actinide cations in general. The first cation-cation complex, NpO 2 + ·UO 2 2+ , was reported by Sullivan, Hindman, and Zielen in 1961. Of the four actinides that form AnO 2 + species, the cation-cation complexes of NpO 2 + have been studied most extensively while the other actinides have not. The only PuO 2 + cation-cation complexes that have been studied are with Fe 3+ and Cr 3+ and neither one has had its equilibrium constant measured. Actinides have small molar absorptivities and cation-cation complexes have small equilibrium constants; therefore, to overcome these obstacles a sensitive technique is required. Spectroscopic techniques are used most often to study cation-cation complexes. Laser-Induced Photacoustic Spectroscopy equilibrium constants for the complexes NpO 2 + ·UO 2 2+ , NpO 2 + ·Th 4+ , PuO 2 + ·UO 2 2+ , and PuO 2 + ·Th 4+ at an ionic strength of 6 M using LIPAS are 2.4 ± 0.2, 1.8 ± 0.9, 2.2 ± 1.5, and ∼0.8 M -1

  6. First-principles calculation study of mechanism of cation adsorption selectivity of zeolites. A guideline for effective removal of radioactive cesium

    International Nuclear Information System (INIS)

    Nakamura, Hiroki; Okumura, Masahiko; Machida, Masahiko

    2013-01-01

    Zeolites have attracted attention in the reprocessing of radioactive nuclear waste because of their high selective affinity for radioisotopes of Cs. Very recently, their useful properties have been widely utilized in decontamination after the accident at the Fukushima Daiichi Nuclear Power Plants. In this study, we study the high selectivity in the Cs adsorption of zeolites using first-principles calculations and clarify the mechanism of the cation selectivity of zeolites. We obtain energy surfaces on all capture locations for Cs/Na ions inside the micropores of a zeolite, 'mordenite', and find three crucial conditions for the highly ion-selective exchange of Na for Cs: 1) micropores with a radius of ∼3 Å, 2) a moderate Al/Si ratio, and 3) a uniform distribution of Al atoms around each micropore. These insights suggest a guideline for developing zeolites with high Cs selectivity and for enhancing the cation selectivity in more general situations. (author)

  7. Selective extraction of metal cations by calixarenes: theoretical and experimental investigations

    International Nuclear Information System (INIS)

    Lamare, V.

    1999-07-01

    The author gives an overview of some research works she performed within the frame of researches aimed at the volume and harmfulness reduction of radioactive liquid wastes produced by spent nuclear fuel reprocessing operations. More precisely, her works dealt with the selective separation of minor radio-elements by using micro-cyclic organic molecules which enable a good chemical and radiochemical stability, and whose selectivity can be adjusted with respect to the radio-element to be removed. The chosen extracting molecules are calixarenes which are functionalized by chemical functions known for their affinity with the radio-element to be removed, and therefore enable the desired hydrophobicity to be obtained, as well as an important reorganization effect which renders these extractors much more efficient

  8. Study of the spheroidization process of glass particles for selective internal radiotherapy

    International Nuclear Information System (INIS)

    Barros Filho, Eraldo Cordeiro

    2012-01-01

    The selective internal radiotherapy is an alternative method to treat hepatocellular carcinoma. Glass microspheres containing radionuclides are introduced in the liver through the hepatic artery, and they are housed preferentially in the region where the cancer cells are located. The microspheres are trapped in the arterioles which feed the tumors, and the β - particles annihilate the cancer cells. When these particles simultaneously emit γ rays, they can also be used to provide images of the tumor. The glass particles must be spherical to avoid unnecessary bleeding, and the particle size must be restricted to a range which is appropriated to trap them and avoid the migration to other parts of the body. Furthermore, they must have a good chemical durability and be nontoxic. The particle size distribution of microspheres is not easily predicted based on the original irregular particles since the variation of the aspect ratio and the presence of agglomerates can influence the final result. In the present work, the spheroidization process to obtain microspheres for radiotherapy treatment was studied. The glass microspheres were characterized by X-rays diffraction, Energy Dispersive X-rays Fluorescence Spectroscopy, Differential Scanning Calorimetry, Specific Superficial Area and cytotoxicity test. The dissolution rate in distilled water at 90 degree C (DR∼10 -8 g.cm - 2.min -1 ), density (2.79g.cm -3 ), viscosity, and size particle distribution were determined. The surface morphological aspect was evaluated by Scanning Electron Microscopy before and after the chemical durability tests in SBF and after the neutron irradiation. It is proposed that the produced material should be sieved to select the most suitable microspheres

  9. Selective Interaction of a Cationic Polyfluorene with Model Lipid Membranes: Anionic versus Zwitterionic Lipids

    Directory of Open Access Journals (Sweden)

    Zehra Kahveci

    2014-03-01

    Full Text Available This paper explores the interaction mechanism between the conjugated polyelectrolyte {[9,9-bis(6'-N,N,N-trimethylammoniumhexyl]fluorene-phenylene}bromide (HTMA-PFP and model lipid membranes. The study was carried out using different biophysical techniques, mainly fluorescence spectroscopy and microscopy. Results show that despite the preferential interaction of HTMA-PFP with anionic lipids, HTMA-PFP shows affinity for zwitterionic lipids; although the interaction mechanism is different as well as HTMA-PFP’s final membrane location. Whilst the polyelectrolyte is embedded within the lipid bilayer in the anionic membrane, it remains close to the surface, forming aggregates that are sensitive to the physical state of the lipid bilayer in the zwitterionic system. The different interaction mechanism is reflected in the polyelectrolyte fluorescence spectrum, since the maximum shifts to longer wavelengths in the zwitterionic system. The intrinsic fluorescence of HTMA-PFP was used to visualize the interaction between polymer and vesicles via fluorescence microscopy, thanks to its high quantum yield and photostability. This technique allows the selectivity of the polyelectrolyte and higher affinity for anionic membranes to be observed. The results confirmed the appropriateness of using HTMA-PFP as a membrane fluorescent marker and suggest that, given its different behaviour towards anionic and zwitterionic membranes, HTMA-PFP could be used for selective recognition and imaging of bacteria over mammalian cells.

  10. Radiochemical investigation of processes responsible for ion sensitivity of cadmium-selective electrodes on the basis of chalcogenide glass

    International Nuclear Information System (INIS)

    Vlasov, Yu.G.; Miloshova, M.S.; Moreno, R.A.; Bychkov, E.A.; Antonov, P.P.

    1988-01-01

    Using 115m Cd radioactive isotope the exchange of cadmium ions between solution and cadmium-containing chalcogenide glass of cadmium iodide - silver sulfide - arsenic sulfide system, used as a membrane of ion-selective electrodes, is studied. It is shown that the exchange of cadmium ions obeys the same regularities both in the case of labelled glass and in the case of solution, containing radioactive cadmium nitrate. Exchange of cadmium ions is proportional to Cd(NO 3 ) 2 concentration is solution

  11. Aqueous self-assembly and cation selectivity of cobaltabisdicarbollide dianionic dumbbells.

    Science.gov (United States)

    Tarrés, Màrius; Viñas, Clara; González-Cardoso, Patricia; Hänninen, Mikko M; Sillanpää, Reijo; Dorďovič, Vladimír; Uchman, Mariusz; Teixidor, Francesc; Matějíček, Pavel

    2014-05-26

    The anion [3,3'-Co(C2B9H11)2](-) ([COSAN](-)) produces aggregates in water. These aggregates are interpreted to be the result of C-H⋅⋅⋅H-B interactions. It is possible to generate aggregates even after the incorporation of additional functional groups into the [COSAN](-) units. The approach is to join two [COSAN](-) anions by a linker that can adapt itself to act as a crown ether. The linker has been chosen to have six oxygen atoms, which is the ideal number for K(+) selectivity in crown ethers. The linker binds the alkaline metal ions with different affinities; thus showing a distinct degree of selectivity. The highest affinity is shown towards K(+) from a mixture containing Li(+), Na(+), K(+), Rb(+) and Cs(+); this can be indicative of pseudo-crown ether performance of the dumbbell. One interesting possibility is that the [COSAN](-) anions at the two ends of the linker can act as a hook-and-loop fastener to close the ring. This facet is intriguing and deserves further consideration for possible applications. The distinct affinity towards alkaline metal ions is corroborated by solubility studies and isothermal calorimetry thermograms. Furthermore, cryoTEM micrographs, along with light scattering results, reveal the existence of small self-assemblies and compact nanostructures ranging from spheres to single-/multi-layer vesicles in aqueous solutions. The studies reported herein show that these dumbbells can have different appearances, either as molecules or aggregates, in water or lipophilic phases; this offers a distinct model as drug carriers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Biophysical studies of the interaction of squalamine and other cationic amphiphilic molecules with bacterial and eukaryotic membranes: importance of the distribution coefficient in membrane selectivity.

    Science.gov (United States)

    Di Pasquale, Eric; Salmi-Smail, Chanaz; Brunel, Jean-Michel; Sanchez, Patrick; Fantini, Jacques; Maresca, Marc

    2010-02-01

    The interaction of squalamine (SQ) with eukaryotic and prokaryotic membranes was studied and compared with the interaction of two other cationic amphipathic antimicrobials (CAAs), i.e. the antibiotic polymyxin B (PMB) and the detergent hexadecyltrimethylammonium bromide (CTAB). Whole cell experiments showed that the three CAA have in common the ability to interact with lipopolysaccharide-containing membranes through a divalent cation sensitive process. Differences were found regarding their kinetics of membrane permeabilisation and their selectivity for bacteria, with a preferential permeabilisation of bacteria by PMB>SQ and no selectivity for CTAB. Experiments with lipid monolayers and bilayers showed that this selectivity did not correlate with a preferential interaction of the CAAs with lipids but rather relies on differences in their ability to penetrate lipid bilayers and to cause electrically active lesions. Incidentally, our results also suggest that the distribution coefficient of CAAs could be used to predict their selectivity for bacteria.

  13. Location and valence state of strontium cations on the framework of a carbon dioxide selective porous silicoaluminophosphate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Li; Rivera-Ramos, Milton E.; Hernández-Maldonado, Arturo J. (Puerto Rico)

    2014-05-28

    A Sr{sup 2+}-SAPO-34 material that displays superior CO2 adsorption selectivity and capacity was characterized via XPS and UV-vis spectroscopy to elucidate the valence state of strontium cations and framework silicon environment. Most importantly, the location of the strontium has been estimated from a Rietveld refinement analysis of synchrotron diffraction data. The XPS analysis indicated that the apparent valence state of the strontium is less than 2, an indication of its interaction with the large anionic framework. Furthermore, UV-vis tests pointed to changes in the silicon environment, plausibly related to this valence state or framework faulting. For the refinement, the analysis found that strontium occupied two unique sites: a site Sr1 slightly displaced from six-membered rings and a site Sr2 positioned at the top or bottom of the eight-membered rings. The latter position favors the interaction of the alkaline earth metal with CO{sub 2}, probably resulting in an enhanced electric field-quadrupole moment interaction.

  14. Hydrolytically Stable Luminescent Cationic Metal Organic Framework for Highly Sensitive and Selective Sensing of Chromate Anions in Natural Water Systems.

    Science.gov (United States)

    Liu, Wei; Wang, Yanlong; Bai, Zhuanling; Li, Yuxiang; Wang, Yaxing; Chen, Lanhua; Xu, Lin; Diwu, Juan; Chai, Zhifang; Wang, Shuao

    2017-05-17

    Effective detection of chromate anions in aqueous solution is highly desirable because of their high solubility, environmental mobility, carcinogenicity, and bioaccumulation effect. A new strategy for precise detection of chromate anions in the presence of a large excess of other anions, such as Cl - , NO 3 - , and HCO 3 - , in drinking water and natural water systems remains a challenge. Herein, a hydrolytically stable cationic luminescent europium(III)-based metal organic framework (MOF), 1, was successfully synthesized and investigated as a luminescent sensor that exhibits instant and selective luminescence quenching properties toward chromate ions in aqueous solutions. Moreover, 1 can be introduced into high-ionic-strength water system (e.g., seawater) for chromate detection as a consequence of the excellent sensing selectivity. The real environmental application of 1 as a chromate probe is studied in deionized water, lake water, and seawater. The detection limits in these aqueous media are calculated to be 0.56, 2.88, and 1.75 ppb, respectively. All of these values are far below the maximum contamination standard of Cr(VI) in drinking water of 100 ppb, defined by the U.S. Environmental Protection Agency. This excellent chromate sensing capability originates from the fast enrichment of chromate ions in solids of 1 from solutions, followed by efficient energy transfer from the MOF skeleton to the chromate anion, as demonstrated by solution absorption spectroscopy, X-ray diffraction, and chromate uptake kinetics and isotherm investigations. To the best of our knowledge, 1 possesses the lowest chromate detection limit among all reported MOFs up to date and is the only MOF material reported for chromate sensing application under environmentally relevant conditions with high ionic strengths.

  15. Four Cation-Selective Transporters Contribute to Apical Uptake and Accumulation of Metformin in Caco-2 Cell Monolayers

    Science.gov (United States)

    Han, Tianxiang (Kevin); Proctor, William R.; Costales, Chester L.; Cai, Hao; Everett, Ruth S.

    2015-01-01

    Metformin is the frontline therapy for type II diabetes mellitus. The oral bioavailability of metformin is unexpectedly high, between 40 and 60%, given its hydrophilicity and positive charge at all physiologic pH values. Previous studies in Caco-2 cell monolayers, a cellular model of the human intestinal epithelium, showed that during absorptive transport metformin is taken up into the cells via transporters in the apical (AP) membrane; however, predominant transport to the basolateral (BL) side occurs via the paracellular route because intracellular metformin cannot egress across the BL membrane. Furthermore, these studies have suggested that the AP transporters can contribute to intestinal accumulation and absorption of metformin. Transporter-specific inhibitors as well as a novel approach involving a cocktail of transporter inhibitors with overlapping selectivity were used to identify the AP transporters that mediate metformin uptake in Caco-2 cell monolayers; furthermore, the relative contributions of these transporters in metformin AP uptake were also determined. The organic cation transporter 1, plasma membrane monoamine transporter (PMAT), serotonin reuptake transporter, and choline high-affinity transporter contributed to approximately 25%, 20%, 20%, and 15%, respectively, of the AP uptake of metformin. PMAT-knockdown Caco-2 cells were constructed to confirm the contribution of PMAT in metformin AP uptake because a PMAT-selective inhibitor is not available. The identification of four intestinal transporters that contribute to AP uptake and potentially intestinal absorption of metformin is a significant novel finding that can influence our understanding of metformin pharmacology and intestinal drug-drug interactions involving this highly prescribed drug. PMID:25563903

  16. Coordination Environments of Highly Charged Cations (Ti, Cr, and Light REE's) in Borosilicate Glass/Melts to 1120C

    Energy Technology Data Exchange (ETDEWEB)

    Farges, Francois; /Museum Natl. Hist. Natur. /Stanford U., Geo. Environ. Sci.; Brown, Gordon E., Jr.; /Stanford U., Geo. Environ Sci. /SLAC, SSRL

    2007-01-02

    The local environments around Ti, Cr, and several light rare-earth elements (La, Ce, and Nd) were investigated by in-situ XANES spectroscopy in a number of complex borosilicate glasses and melts (to 1120 C) that are used for nuclear waste storage. Examination of the high-resolution XANES spectra at the Ti K-edge shows that the average coordination of Ti changes from {approx}5 to {approx}4.5. Cr is dominantly trivalent in the melts studied. However, its average coordination is probably lower in the melt (tetrahedral ?) as revealed by the more intense Cr-K pre-edge feature. Ce also changes its average valence from dominantly +4 to +3.5 upon glass melting. These changes are reversible at T{sub g}, the glass transition temperature ({approx}500-550 C for these glasses). In contrast, the local environments of Nd, Pr, and La are unaffected by melting. Therefore, structural reorganization of these borosilicate glass/melts above T{sub g} is variable, not only in terms of valence (as for Ce) but also speciation (Ti and Cr). Both the ability of B to adopt various coordination geometries (triangular and tetrahedral) and the chemical complexity of the glass/melts explain these changes.

  17. Synthesis and Ion-Exchange Properties of Graphene Th(IV) Phosphate Composite Cation Exchanger: Its Applications in the Selective Separation of Lead Metal Ions.

    Science.gov (United States)

    Rangreez, Tauseef Ahmad; Asiri, Abdullah M; Alhogbi, Basma G; Naushad, Mu

    2017-07-24

    In this study, graphene Th(IV) phosphate was prepared by sol-gel precipitation method. The ion-exchange behavior of this cation-exchanger was studied by investigating properties like ion-exchange capacity for various metal ions, the effect of eluent concentration, elution behavior, and thermal effect on ion-exchange capacity (IEC). Several physicochemical properties as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) study, thermal studies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies were also carried out. The material possessed an IEC of 1.56 meq·dry·g -1 of the exchanger and was found to be nano-composite. The selectivity studies showed that the material is selective towards Pb(II) ions. The selectivity of this cation-exchanger was demonstrated in the binary separation of Pb(II) ions from mixture with other metal ions. The recovery was found to be both quantitative and reproducible.

  18. Phase selection and microstructure in directional solidification of glass forming Pd-Si-Cu alloys

    Science.gov (United States)

    Huo, Yang

    Phase selection and microstructure formation during the rapid solidification of alloy melts has been a topic of substantial interest over the last several decades, attributed mainly to the access to novel structures involving metastable crystalline and non-crystalline phases. In this work, Bridgeman type directional solidification was conducted in Pd-Si-Cu glass forming system to study such cooling rate dependent phase transition and microstructure formation. The equilibrium state for Pd-Si-Cu ternary system was investigated through three different works. First of all, phase stabilities for Pd-Si binary system was accessed with respects of first-principles and experiments, showing Pd5Si, Pd9Si2, Pd3Si and Pd 2Si phase are stable all way to zero Kevin while PdSi phase is a high temperature stable phase, and Pd2Si phase with Fe2P is a non-stoichiometry phase. A thermodynamic database was developed for Pd-Si system. Second, crystal structures for compounds with ternary compositions were studied by XRD, SEM and TEM, showing ordered and disordered B2/bcc phases are stable in Pd-rich part. At last, based on many phase equilibria and phase transitions data, a comprehensive thermodynamic discrption for Pd-Si-Cu ternary system was first time to be developed, from which different phase diagrams and driving force for kinetics can be calculated. Phase selection and microstructure formation in directional solidification of the best glass forming composition, Pd 77.5Si16.5Cu6, in this system with growth velocities from 0.005 to 7.5mm/s was systematically studied and the solidification pathways at different conditions were interpreted from thermodynamic simulation. The results show that for growth velocities are smaller than 0.1mm/s Pd 3Si phase is primary phase and Pd9Si2 phase is secondary phase, the difficulty for Pd9Si2 phase nucleation gives rise to the formation of two different eutectic structure. For growth velocities between 0.4 and 1mm/s, instead of Pd3Si phase, Pd9Si2

  19. High Specific Selectivity and Membrane-Active Mechanism of Synthetic Cationic Hybrid Antimicrobial Peptides Based on the Peptide FV7.

    Science.gov (United States)

    Tan, Tingting; Wu, Di; Li, Weizhong; Zheng, Xin; Li, Weifen; Shan, Anshan

    2017-02-06

    Hybrid peptides integrating different functional domains of peptides have many advantages, such as remarkable antimicrobial activity, lower hemolysis and ideal cell selectivity, compared with natural antimicrobial peptides. FV7 (FRIRVRV-NH₂), a consensus amphiphilic sequence was identified as being analogous to host defense peptides. In this study, we designed a series of hybrid peptides FV7-LL-37 (17-29) (FV-LL), FV7-magainin 2 (9-21) (FV-MA) and FV7-cecropin A (1-8) (FV-CE) by combining the FV7 sequence with the small functional sequences LL-37 (17-29) (LL), magainin 2 (9-21) (MA) and cecropin A (1-8) (CE) which all come from well-described natural peptides. The results demonstrated that the synthetic hybrid peptides, in particular FV-LL, had potent antibacterial activities over a wide range of Gram-negative and Gram-positive bacteria with lower hemolytic activity than other peptides. Furthermore, fluorescent spectroscopy indicated that the hybrid peptide FV-LL exhibited marked membrane destruction by inducing outer and inner bacterial membrane permeabilization, while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrated that FV-LL damaged membrane integrity by disrupting the bacterial membrane. Inhibiting biofilm formation assays also showed that FV-LL had similar anti-biofilm activity compared with the functional peptide sequence FV7. Synthetic cationic hybrid peptides based on FV7 could provide new models for combining different functional domains and demonstrate effective avenues to screen for novel antimicrobial agents.

  20. A Decision Support Concept for a construction design project – selecting the type of glass façade

    Directory of Open Access Journals (Sweden)

    Franjo Šimić

    2017-01-01

    Full Text Available The paper describes research into the possibility of developing a concept for supporting decisions in planning construction projects (one of the most important stages of construction project management. The focus is on supporting decisions in selecting the type of and solution for the glass façade in the main design. Materials and types of soluteons for a glass façade were analyzed and alternative solutions were obtained. The concept was developed in that it included relevant stakeholders in the decision-making process during the construction design. These stakeholders were the investor, architect, and construction contractor. The analysis was carried out and a hierarchical structure of objectives was formed as a goal tree. The criteria at the last hierarchical level were used to evaluate alternative solutions for the glass façade, and their weights were determined by all stakeholders using the AHP method (Analytic Hierarchy Process. Using PROMETHEE (Preference Ranking Method for Enrichment Evaluation, a comparison of alternative solutions for the glass façade was conducted and the alternatives were ranked according to the priorities for inclusion into the main design. The concept was tested by selecting a type of glass façade on a residential-commercial building in the city of Rijeka, Croatia.

  1. Yttrium-90 selective internal radiation therapy with glass microspheres for hepatocellular carcinoma: Current and updated literature review

    International Nuclear Information System (INIS)

    Lee, Edward Wolfgang; Alanic, Lourdes; Cho, Sung Ki; Saab, Sammy

    2016-01-01

    Hepatocellular carcinoma is the most common primary liver cancer and it represents the majority of cancer-related deaths in the world. More than 70% of patients present at an advanced stage, beyond potentially curative options. Ytrrium-90 selective internal radiation therapy (Y90-SIRT) with glass microspheres is rapidly gaining acceptance as a potential therapy for intermediate and advanced stage primary hepatocellular carcinoma and liver metastases. The technique involves delivery of Y90 infused glass microspheres via the hepatic arterial blood flow to the appropriate tumor. The liver tumor receives a highly concentrated radiation dose while sparing the healthy liver parenchyma due to its preferential blood supply from portal venous blood. There are two commercially available devices: TheraSphere® and SIR-Spheres®. Although, Y90-SIRT with glass microspheres improves median survival in patients with intermediate and advanced hepatocellular carcinoma and has the potential to downstage hepatocellular carcinoma so that the selected candidates meet the transplantable criteria, it has not gained widespread acceptance due to the lack of large randomized controlled trials. Currently, there are various clinical trials investigating the use of Y90-SIRT with glass microspheres for treatment of hepatocellular carcinoma and the outcomes of these trials may result in the incorporation of Y90-SIRT with glass microspheres into the treatment guidelines as a standard therapy option for patients with intermediate and advanced stage hepatocellular carcinoma

  2. Yttrium-90 Selective Internal Radiation Therapy with Glass Microspheres for Hepatocellular Carcinoma: Current and Updated Literature Review.

    Science.gov (United States)

    Lee, Edward Wolfgang; Alanis, Lourdes; Cho, Sung-Ki; Saab, Sammy

    2016-01-01

    Hepatocellular carcinoma is the most common primary liver cancer and it represents the majority of cancer-related deaths in the world. More than 70% of patients present at an advanced stage, beyond potentially curative options. Ytrrium-90 selective internal radiation therapy (Y90-SIRT) with glass microspheres is rapidly gaining acceptance as a potential therapy for intermediate and advanced stage primary hepatocellular carcinoma and liver metastases. The technique involves delivery of Y90 infused glass microspheres via the hepatic arterial blood flow to the appropriate tumor. The liver tumor receives a highly concentrated radiation dose while sparing the healthy liver parenchyma due to its preferential blood supply from portal venous blood. There are two commercially available devices: TheraSphere® and SIR-Spheres®. Although, Y90-SIRT with glass microspheres improves median survival in patients with intermediate and advanced hepatocellular carcinoma and has the potential to downstage hepatocellular carcinoma so that the selected candidates meet the transplantable criteria, it has not gained widespread acceptance due to the lack of large randomized controlled trials. Currently, there are various clinical trials investigating the use of Y90-SIRT with glass microspheres for treatment of hepatocellular carcinoma and the outcomes of these trials may result in the incorporation of Y90-SIRT with glass microspheres into the treatment guidelines as a standard therapy option for patients with intermediate and advanced stage hepatocellular carcinoma.

  3. Yttrium-90 Selective Internal Radiation Therapy with Glass Microspheres for Hepatocellular Carcinoma: Current and Updated Literature Review

    International Nuclear Information System (INIS)

    Lee, Edward Wolfgang; Alanis, Lourdes; Cho, Sung-Ki; Saab, Sammy

    2016-01-01

    Hepatocellular carcinoma is the most common primary liver cancer and it represents the majority of cancer-related deaths in the world. More than 70% of patients present at an advanced stage, beyond potentially curative options. Ytrrium-90 selective internal radiation therapy (Y90-SIRT) with glass microspheres is rapidly gaining acceptance as a potential therapy for intermediate and advanced stage primary hepatocellular carcinoma and liver metastases. The technique involves delivery of Y90 infused glass microspheres via the hepatic arterial blood flow to the appropriate tumor. The liver tumor receives a highly concentrated radiation dose while sparing the healthy liver parenchyma due to its preferential blood supply from portal venous blood. There are two commercially available devices: TheraSphere® and SIR-Spheres®. Although, Y90-SIRT with glass microspheres improves median survival in patients with intermediate and advanced hepatocellular carcinoma and has the potential to downstage hepatocellular carcinoma so that the selected candidates meet the transplantable criteria, it has not gained widespread acceptance due to the lack of large randomized controlled trials. Currently, there are various clinical trials investigating the use of Y90-SIRT with glass microspheres for treatment of hepatocellular carcinoma and the outcomes of these trials may result in the incorporation of Y90-SIRT with glass microspheres into the treatment guidelines as a standard therapy option for patients with intermediate and advanced stage hepatocellular carcinoma

  4. Yttrium-90 selective internal radiation therapy with glass microspheres for hepatocellular carcinoma: Current and updated literature review

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Edward Wolfgang; Alanic, Lourdes [Div. of Interventional Radiology, Dept. of Radiology, UCLA Medical Center, David Geffen School of Medicine at UCLA, Los Angeles (United States); Cho, Sung Ki [Div. of Interventional Radiology, Dept. of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Saab, Sammy [Div. of Hepatology, Dept. of Medicine, Pfleger Liver Institute, University of California at Los Angeles, Los Angeles (United States)

    2016-07-15

    Hepatocellular carcinoma is the most common primary liver cancer and it represents the majority of cancer-related deaths in the world. More than 70% of patients present at an advanced stage, beyond potentially curative options. Ytrrium-90 selective internal radiation therapy (Y90-SIRT) with glass microspheres is rapidly gaining acceptance as a potential therapy for intermediate and advanced stage primary hepatocellular carcinoma and liver metastases. The technique involves delivery of Y90 infused glass microspheres via the hepatic arterial blood flow to the appropriate tumor. The liver tumor receives a highly concentrated radiation dose while sparing the healthy liver parenchyma due to its preferential blood supply from portal venous blood. There are two commercially available devices: TheraSphere® and SIR-Spheres®. Although, Y90-SIRT with glass microspheres improves median survival in patients with intermediate and advanced hepatocellular carcinoma and has the potential to downstage hepatocellular carcinoma so that the selected candidates meet the transplantable criteria, it has not gained widespread acceptance due to the lack of large randomized controlled trials. Currently, there are various clinical trials investigating the use of Y90-SIRT with glass microspheres for treatment of hepatocellular carcinoma and the outcomes of these trials may result in the incorporation of Y90-SIRT with glass microspheres into the treatment guidelines as a standard therapy option for patients with intermediate and advanced stage hepatocellular carcinoma.

  5. Yttrium-90 Selective Internal Radiation Therapy with Glass Microspheres for Hepatocellular Carcinoma: Current and Updated Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Edward Wolfgang; Alanis, Lourdes [Division of Interventional Radiology, Department of Radiology, UCLA Medical Center, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 (United States); Cho, Sung-Ki [Division of Interventional Radiology, Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351 (Korea, Republic of); Saab, Sammy [Division of Hepatology, Department of Medicine, Pfleger Liver Institute, University of California at Los Angeles, Los Angeles, CA 90024 (United States)

    2016-11-01

    Hepatocellular carcinoma is the most common primary liver cancer and it represents the majority of cancer-related deaths in the world. More than 70% of patients present at an advanced stage, beyond potentially curative options. Ytrrium-90 selective internal radiation therapy (Y90-SIRT) with glass microspheres is rapidly gaining acceptance as a potential therapy for intermediate and advanced stage primary hepatocellular carcinoma and liver metastases. The technique involves delivery of Y90 infused glass microspheres via the hepatic arterial blood flow to the appropriate tumor. The liver tumor receives a highly concentrated radiation dose while sparing the healthy liver parenchyma due to its preferential blood supply from portal venous blood. There are two commercially available devices: TheraSphere® and SIR-Spheres®. Although, Y90-SIRT with glass microspheres improves median survival in patients with intermediate and advanced hepatocellular carcinoma and has the potential to downstage hepatocellular carcinoma so that the selected candidates meet the transplantable criteria, it has not gained widespread acceptance due to the lack of large randomized controlled trials. Currently, there are various clinical trials investigating the use of Y90-SIRT with glass microspheres for treatment of hepatocellular carcinoma and the outcomes of these trials may result in the incorporation of Y90-SIRT with glass microspheres into the treatment guidelines as a standard therapy option for patients with intermediate and advanced stage hepatocellular carcinoma.

  6. A binary catalyst system of a cationic Ru-CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide.

    Science.gov (United States)

    Ng, Chee Koon; Wu, Jie; Hor, T S Andy; Luo, He-Kuan

    2016-09-27

    Binary catalyst systems comprising a cationic Ru-CNC pincer complex and an alkali metal salt were developed for selective hydroboration of CO 2 utilizing pinacolborane at r.t. and 1 atm CO 2 , with the combination of [Ru(CNC Bn )(CO) 2 (H)][PF 6 ] and KOCO 2 t Bu producing formoxyborane in 76% yield. A bicyclic catalytic mechanism was proposed and discussed.

  7. Ordered and disordered models of local structure around Ag cations in silver borate glasses based on x-ray absorptio n near-edge structure spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Šipr, Ondřej; Dalba, G.; Rocca, F.

    2004-01-01

    Roč. 69, - (2004), 134201/1-134201/16 ISSN 0163-1829 R&D Projects: GA ČR GA202/02/0841 Institutional research plan: CEZ:AV0Z1010914 Keywords : disordered systems * structural analysis * XANES * silver * borate glass es Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.075, year: 2004

  8. Liquidus temperature and chemical durability of selected glasses to immobilize rare earth oxides waste

    Science.gov (United States)

    Mohd Fadzil, Syazwani; Hrma, Pavel; Schweiger, Michael J.; Riley, Brian J.

    2015-10-01

    Pyroprocessing is are processing method for managing and reusing used nuclear fuel (UNF) by dissolving it in an electrorefiner with a molten alkali or alkaline earth chloride salt mixture while avoiding wet reprocessing. Pyroprocessing UNF with a LiCl-KCl eutectic salt releases the fission products from the fuel and generates a variety of metallic and salt-based species, including rare earth (RE) chlorides. If the RE-chlorides are converted to oxides, borosilicate glass is a prime candidate for their immobilization because of its durability and ability to dissolve almost any RE waste component into the glass matrix at high loadings. Crystallization that occurs in waste glasses as the waste loading increases may complicate glass processing and affect the product quality. This work compares three types of borosilicate glasses in terms of liquidus temperature (TL): the International Simple Glass designed by the International Working Group, sodium borosilicate glass developed by Korea Hydro and Nuclear Power, and the lanthanide aluminoborosilicate (LABS) glass established in the United States. The LABS glass allows the highest waste loadings (over 50 mass% RE2O3) while possessing an acceptable chemical durability.

  9. Study of the spheronization process of glass particles by the gravitational falling process for internal selective radiotherapy

    International Nuclear Information System (INIS)

    Barros Filho, E.C.; Martinelli, J.R.; Sene, F.F.

    2011-01-01

    The internal selective radiotherapy is an alternative to treat hepatocellular carcinoma. Glass microspheres containing β - emitter radionuclide are introduced in the liver, and they are housed preferentially in the region where the cancer cells are located. The microspheres are trapped in the arterioles which feed the tumors, and the β - particles annihilate the cancer cells. The glass particles must be spherical to avoid unnecessary bleeding, and the particle size must be restricted to a range which optimizes the blocking effect and avoid the migration to other parts of the human body. The particle size distribution of microspheres is not easily predicted since the variation of the aspect ratio and the presence of agglomerates can influence the resulting particle size distribution. In the present work, the spheronization process to obtain microspheres from irregular shape glass particles with suitable diameter and shape for radiotherapy treatment is studied. (author)

  10. Importance of non-selective cation channel TRPV4 interaction with cytoskeleton and their reciprocal regulations in cultured cells.

    Directory of Open Access Journals (Sweden)

    Chandan Goswami

    non-selective cation channels and cytoskeleton at multiple levels. These cross talks may help us to understand the molecular basis of the Taxol-induced neuropathic pain development commonly observed in cancer patients.

  11. Evaluation of the Seismic Characterision of Select Engineered Nanoparticles in Saturated Glass Beads

    Science.gov (United States)

    A laboratory testing apparatus was developed for the study of seismic body wave propagation through nanoparticles dispersed in pore fluid that is essentially saturating glass beads. First, the responses of water-saturated glass bead specimens were studied to establish baseline si...

  12. Preparation and characterization of monovalent ion selective cation exchange membranes based on sulphonated poly(ether ether ketone)

    NARCIS (Netherlands)

    Balster, J.H.; Krupenko, O.; Krupenko, O.; Punt, Ineke G.M.; Stamatialis, Dimitrios; Wessling, Matthias

    2005-01-01

    This paper analyses the separation properties of various commercial cation exchange membranes (CEMs) and tailor made membranes based on sulphonated poly(ether ether ketone) and poly(ether sulphone) for binary electrolyte solutions containing protons and calcium ions. All membranes are thoroughly

  13. Selectivity of plasma membrane calcium ATPase (PMCA)-mediated extrusion of toxic divalent cations in vitro and in cultured cells.

    Science.gov (United States)

    Ferreira-Gomes, Mariela S; Mangialavori, Irene C; Ontiveros, Mallku Q; Rinaldi, Debora E; Martiarena, Jorge; Verstraeten, Sandra V; Rossi, Juan Pablo F C

    2018-01-01

    In the recent years, the toxicity of certain divalent cations has been associated with the alteration of intracellular Ca 2+ homeostasis. Among other mechanisms, these cations may affect the functionality of certain Ca 2+ -binding proteins and/or Ca 2+ pumps. The plasma membrane calcium pump (PMCA) maintains Ca 2+ homeostasis in eukaryotic cells by mediating the efflux of this cation in a process coupled to ATP hydrolysis. The aim of this work was to investigate both in vitro and in cultured cells if other divalent cations (Sr 2+ , Ba 2+ , Co 2+ , Cd 2+ , Pb 2+ or Be 2+ ) could be transported by PMCA. Current results indicate that both purified and intact cell PMCA transported Sr 2+ with kinetic parameters close to those of Ca 2+ transport. The transport of Pb 2+ and Co 2+ by purified PMCA was, respectively, 50 and 75% lower than that of Ca 2+ , but only Co 2+ was extruded by intact cells and to a very low extent. In contrast, purified PMCA-but not intact cell PMCA-transported Ba 2+ at low rates and only when activated by limited proteolysis or by phosphatidylserine addition. Finally, purified PMCA did not transport Cd 2+ or Be 2+ , although minor Be 2+ transport was measured in intact cells. Moreover, Cd 2+ impaired the transport of Ca 2+ through various mechanisms, suggesting that PMCA may be a potential target of Cd 2+ -mediated toxicity. The differential capacity of PMCA to transport these divalent cations may have a key role in their detoxification, limiting their noxious effects on cell homeostasis.

  14. Glass fabrication and analysis literature review and method selection for WTP waste feed qualification

    International Nuclear Information System (INIS)

    Peeler, D.

    2013-01-01

    The waste feed qualification program is being developed to protect the Hanford Tank Waste Treatment and Immobilization Plant (WTP) safety basis, technical basis, and design by assuring waste acceptance requirements are met for each staged waste feed Campaign prior to transfer from the Hanford Tank Farm to the WTP. The three components of waste feed qualification include: Demonstrate compliance with the waste acceptance criteria; Determine waste processability; and, Demonstrate unit operations at laboratory scale. This literature review addresses the final step of unit operations testing of radioactive Tank Farm samples – the glass fabrication unit operation. Based on Savannah River National Laboratory’s review, the following apparatus are needed by the waste feed qualification laboratory: A high speed, low shear remotable mixer such as the LabRAM or similar to mix the feed and ensure homogenous and representative samples can be obtained to support compositional and rheology measurements; A remotable Haake M5/RV30 rotoviscometer or similar to perform rheological measurements of the melter feed streams; A resistance heated remotable laboratory furnace such as a CM Bottom loaded, elevator furnace (Model 1708 BL) or similar to fabricate the glass coupons; and, Platinum or platinum-alloy crucibles (100 or 250 mL with reinforced rims) to fabricate the glass coupons. The following measurements are recommended: Compositional analysis of waste sample to identify types and quantities of glass former materials; Hydrogen generation rate of waste sample before or after addition of glass former materials; Rheology of waste sample prior to addition of glass former materials; Rheology of waste sample after addition of glass former materials; Compositional analysis of waste sample after addition of glass former materials; and, Visual observation of glass coupon. It should be noted that use of cooling curves to evaluate nepheline formation (or any other forms of crystallization

  15. Selectivity and stoichiometry boosting of beta-cyclodextrin in cationic/anionic surfactant systems: when host-guest equilibrium meets biased aggregation equilibrium.

    Science.gov (United States)

    Jiang, Lingxiang; Yu, Caifang; Deng, Manli; Jin, Changwen; Wang, Yilin; Yan, Yun; Huang, Jianbin

    2010-02-18

    Cationic surfactant/anionic surfactant/beta-CD ternary aqueous systems provide a platform for the coexistence of the host-guest (beta-CD/surfactant) equilibrium and the biased aggregation (monomeric/aggregated surfactants) equilibrium. We report here that the interplay between the two equilibria dominates the systems as follows. (1) The biased aggregation equilibrium imposes an apparent selectivity on the host-guest equilibrium, namely, beta-CD has to always selectively bind the major surfactant (molar fraction > 0.5) even if binding constants of beta-CD to the pair of surfactants are quite similar. (2) In return, the host-guest equilibrium amplifies the bias of the aggregation equilibrium, that is, the selective binding partly removes the major surfactant from the aggregates and leaves the aggregate composition approaching the electroneutral mixing stoichiometry. (3) This composition variation enhances electrostatic attractions between oppositely charged surfactant head groups, thus resulting in less-curved aggregates. In particular, the present apparent host-guest selectivity is of remarkably high values, and the selectivity stems from the bias of the aggregation equilibrium rather than the difference in binding constants. Moreover, beta-CD is defined as a "stoichiometry booster" for the whole class of cationic/anionic surfactant systems, which provides an additional degree of freedom to directly adjust aggregate compositions of the systems. The stoichiometry boosting of the compositions can in turn affect or even determine microstructures and macroproperties of the systems.

  16. A partially substituted calix[4]resorcarene receptor and its selective recognition for soft metal cations (silver and mercury).

    Science.gov (United States)

    Danil de Namor, Angela F; Chaaban, Jinane K

    2008-02-21

    A partially substituted calix[4]resorcarene receptor, namely, 5,17-ethylthiomethylated calix[4]resorcarene, 1, has been synthesized and characterized by 1H NMR in CD3OD, CDCl3, and CD3CN and 13C NMR in CD3OD, as well as by 2D NMR. Partition data in the methanol-hexane and acetonitrile-hexane solvent systems show that the monomeric species are predominant in these solvents. The solubility of 1 in various solvents was determined at 298.15 K. These data were used to calculate the standard solution Gibbs energy of 1 in these solvents. Taking hexane as the reference solvent, the standard transfer Gibbs energy of 1 to various solvents was calculated. Good agreement is found between the DeltatG(o) values in the hexane-methanol and hexane-acetonitrile and the DeltapG(o) values of this ligand in these solvent systems. The higher partition constant of 1 in the hexane-methanol relative to the hexane-acetonitrile solvent system contrasts with corresponding data for the fully functionalized receptor, 2. This is explained in terms of the solvation differences of these receptors in these solvents as reflected in the DeltatG(o) values. The cation complexing properties of this receptor were investigated through 1H NMR, conductance, calorimetric, and potentiometric methods. Among the metal cations (alkali, alkaline earth, heavy, and transition), 1 interacts only with Ag+ in methanol and Hg2+ in propylene carbonate, acetonitrile, methanol, and N,N-dimethylformamide. While 1 forms a 1:1 complex with Ag+ in methanol, the hosting ability of the receptor for the mercury cation is enhanced in methanol, acetonitrile, and N,N-diethylformamide. Thus, Hg2+ complexes of 1:2 (ligand:metal cation) stoichiometry are found in these solvents. In moving to propylene carbonate, the composition of the mercury complex is altered from 1:2 to 1:1. The results are compared with corresponding data for 2 and these metal cations in the appropriate solvents. The lack of stability observed for 2 and Hg2+ in

  17. Generation of mercury and cadmium cationic complexes from oxidation processes observed in the presence of dimethylmercury and dimethylcadmium at mercury, platinum, and glass carbon electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Bond, A.M.; McLachian, N.M.

    1988-03-01

    Electrochemical oxidation processes at mercury, platinum, and glassy carbon electrodes in the presence of Me/sub 2/Hg generate a mercury-rich cationic complex that is believed to be (Me/sub 2/Hg/sub 3/)/sup 2 +/ or a closely related species. At mercury electrodes, direct participation of the electrode is involved in the electrochemical reaction, which is postulated to occur according to Me/sub 2/Hg + 2Hg ..-->.. (Me/sub 2/Hg/sub 3/)/sup 2 +/ + 2e/sup -/. Reduction of the mercury-rich cation (Me/sub 2/Hg/sub 3/)/sup 2 +/ at a platinum electrode leads to deposition of elemental mercury and regeneration of Me/sub 2/Hg at the mercury-plated platinum electrode: (Me/sub 2/Hg/sub 3/)/sup 2 +/ + 2e/sup -/ ..-->.. Me/sub 2/Hg + 2Hg. At platinum and glassy carbon electrodes, (Me/sub 2/Hg/sub 3/)/sup 2 +/ is also produced as a product of controlled potential electrolysis experiments. In this case, the initially generated (Me/sub 2/Hg)/sup +/ complex is formed at very positive potentials. (Me/sub 2/Hg)/sup +/ then reacts rapidly to generate the cationic methyl mercury complex. The overall process at platinum and glassy carbon electrodes is proposed as 3Me/sub 2/Hg ..-->.. (Me/sub 2/Hg/sub 3/)/sup 2 +/ + 4Me/sup ./ + 2e/sup -/. Oxidation processes associated with the presence of Me/sub 2/Cd are also electrode-dependent. At mercury electrode, alkyl and metal exchange occurs via a bimetallic alkylcadmium-mercury intermediate: Me/sub 2/Cd + Hg ..-->.. Me/sub 2/Hg + Cd/sup 2 +/ + 2e/sup -/. At platinum and glassy carbon electrodes the reaction occurs at more positive potentials than at mercury electrodes and generates inorganic cadmium ions: Me/sub 2/Cd ..-->.. Cd/sup 2 +/ + 2Me/sup ./ + 2e/sup -/.

  18. Fundamental chemistry and materials science of americium in selected immobilization glasses

    Energy Technology Data Exchange (ETDEWEB)

    Haire, R.G. [Oak Ridge National Lab., TN (United States); Stump, N.A. [Winston-Salem State Univ., NC (United States). Dept. of Physical Sciences

    1996-12-01

    We have pursued some of the fundamental chemistry and materials science of Am in 3 glass matrices, two being high-temperature (850 and 1400 C mp) silicate-based glasses and the third a sol-gel glass. Optical spectroscopy was the principal tool. One aspect of this work was to determine the oxidation state exhibited by Am in these matrices, as well as factors that control or may alter this state. A correlation was noted between the oxidation state of the f-elements in the two high-temperature glasses with their high-temperature oxide chemistries. One exception was Am: although AmO{sub 2} is the stable oxide encountered in air, when this dioxide was incorporated into the high-temperature glasses, only trivalent Am was found in the products. When Am(III) was used to prepare the sol-gel glasses at ambient temperature, and after these products were heated in air to 800 C, only Am(III) was observed. Potential explanations for the unexpected Am behavior is offered in the context of its basic chemistry. Experimental spectra, spectroscopic assignments, etc. are discussed.

  19. Selection of a glass-ceramic formulation to immobilize fluorinel- sodium calcine

    Energy Technology Data Exchange (ETDEWEB)

    Staples, B.A.; Wood, H.C.

    1994-12-01

    One option for immobilizing calcined high level wastes produced by nuclear fuel reprocessing activities at the Idaho Chemical Processing Plant (ICPP) is conversion to a glass-ceramic form through hot isostatic pressing. Calcines exist in several different chemical compositions, and thus candidate formulations have been developed for converting each to glass-ceramic forms which are potentially resistant to aqueous corrosion and stable enough to qualify for repository storage. Fluorinel/Na, a chemically complex calcine type, is one of the types being stored at ICPP, and development efforts have identified three formulations with potential for immobilizing it. These are a glass forming additive that uses aluminum metal to enhance reactivity, a second glass forming additive that uses titanium metal to enhance reactivity and a third that uses not only a combination of silicon and titanium metals but enough phosphorous pentoxide to form a calcium phosphate host phase in the glass-ceramic product. Glass-ceramics of each formulation performed well in restricted characterization tests. However, none of the three was subjected to rigorous testing that would provide information on whether each was processable, that is able to retain favorable characteristics over a practical range of processing conditions.

  20. Physical properties and chemical durability of selected zirconia containing silicate glasses

    Directory of Open Access Journals (Sweden)

    ELEONÓRA GAŠPÁREKOVÁ

    2011-12-01

    Full Text Available Density, thermal expansion, glass transition temperature, refractive index, molar refractivity and chemical durability of five- and six-component glasses with as weighted composition xNa2O·(15-xK2O·yCaO∙(10-yZnO∙zZrO2∙(75-zSiO2 (x = 0, 7.5, 15; y = 0, 5, 10; z = 5, 7 were measured. The obtained experimental data were merged together with the previous results obtained for analogous glasses with lower zirconia content. The full set of glasses enabled the quantitative statistical estimation of possible mixed-oxide effects. The results of the multilinear regression analysis pointed out the ideal behavior of molar volume and molar refractivity. The strongest influence of mutual oxide interactions was found for chemical durability and glass transition temperature. The regression analysis of compositional dependence of metastable melt thermal expansion coefficient practically failed. The need of property-composition study based on the thermodynamic model was pointed out. Qualitatively the obtained results confirmed those previously obtained for the analogous glasses with zirconia content reaching up to 3 mol. %.

  1. Fundamental chemistry and materials science of americium in selected immobilization glasses

    International Nuclear Information System (INIS)

    Haire, R.G.; Stump, N.A.

    1996-01-01

    We have pursued some of the fundamental chemistry and materials science of Am in 3 glass matrices, two being high-temperature (850 and 1400 C mp) silicate-based glasses and the third a sol-gel glass. Optical spectroscopy was the principal tool. One aspect of this work was to determine the oxidation state exhibited by Am in these matrices, as well as factors that control or may alter this state. A correlation was noted between the oxidation state of the f-elements in the two high-temperature glasses with their high-temperature oxide chemistries. One exception was Am: although AmO 2 is the stable oxide encountered in air, when this dioxide was incorporated into the high-temperature glasses, only trivalent Am was found in the products. When Am(III) was used to prepare the sol-gel glasses at ambient temperature, and after these products were heated in air to 800 C, only Am(III) was observed. Potential explanations for the unexpected Am behavior is offered in the context of its basic chemistry. Experimental spectra, spectroscopic assignments, etc. are discussed

  2. A cell shrinkage-induced non-selective cation conductance with a novel pharmacology in Ehrlich-Lettre-ascites tumour cells

    DEFF Research Database (Denmark)

    Lawonn, Peter; Hoffmann, Else K; Hougaard, Charlotte

    2003-01-01

    In whole-cell recordings on Ehrlich-Lettre-ascites tumour (ELA) cells, the shrinkage-induced activation of a cation conductance with a selectivity ratio P(Na):P(Li):P(K):P(choline):P(NMDG) of 1.00:0.97:0.88:0.03:0.01 was observed. In order of potency, this conductance was blocked by Gd(3+)=benzam......-sensitive and -insensitive channels. In addition, because of its pharmacological profile, it may possibly be related to epithelial Na+ channels (ENaCs)....

  3. A selective stepwise heme oxygenase model system: an iron(IV)-oxo porphyrin π-cation radical leads to a verdoheme-type compound via an isoporphyrin intermediate.

    Science.gov (United States)

    Garcia-Bosch, Isaac; Sharma, Savita K; Karlin, Kenneth D

    2013-11-06

    The selective oxidation of the α-position of two heme-Fe(III) tetraarylporphryinate complexes occurs when water(hydroxide) attacks their oxidized Cmpd I-type equivalents, high-valent Fe(IV)═O π-cation radical species ((P(+•))Fe(IV)═O). Stepwise intermediate formation occurs, as detected by UV-vis spectroscopic monitoring or mass spectrometric interrogation, being iron(III) isoporphyrins, iron(III) benzoyl-biliverdins, and the final verdoheme-like products. Heme oxygenase (HO) enzymes could proceed through heterolytic cleavage of an iron(III)-hydroperoxo intermediate to form a transient Cmpd I-type species.

  4. Modification of the glass surface induced by redox reactions and internal diffusion processes

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Deubener, Joachim; Yue, Yuanzheng

    In this paper we report a novel way to modify the glass surface in favor of some physical performances. The main step is to perform iso-thermal treatments on the selected silicate glasses containing transition metal at temperatures near the glass transition temperature for various durations under...... different gases. As a result, we have observed a striking phenomenon, i.e., the outward diffusion of divalent cations occurs not only under an oxidizing atmosphere of heat-treatment, but also under nitrogen, even under reducing atmospheres like H2/N2 (10/90). The extent of the cationic diffusion depends...... on temperature and duration of heat-treatments. The mechanism of the diffusion depends on the type of the gases used for the heat-treatments. In this paper we propose several possible models describing mechanisms of the cationic diffusion, and hence, of the formation of the nano-layer. We also report the effect...

  5. Radical cations in condensed phases

    Energy Technology Data Exchange (ETDEWEB)

    Symons, M.C.R. (Leicester Univ. (UK). Dept. of Chemistry)

    The subject is covered in sections, entitled: introduction (scope of present Review); preparative procedures; alkane and cycloalkane cations; alkene and cyclic alkene cations; alkyl-halide cations; alcohol and ether cations; carbonyl cations (aldehyde, ketone and ester cations); sulphur-centred cations; selenium-centred cations; nitrogen-centred cations; phosphorus-centred cations; tin- and lead-centred cations; aromatic cations; five membered hetero-aromatic cations; vinyl cations; inorganic cations.

  6. Effect of the nature of alkali and alkaline-earth oxides on the structure and crystallization of an alumino-borosilicate glass developed to immobilize highly concentrated nuclear waste solutions

    International Nuclear Information System (INIS)

    Quintas, A.; Caurant, D.; Majerus, O.; Charpentier, T.; Dussossoy, J.L.

    2008-01-01

    A complex rare-earth rich alumino-borosilicate glass has been proved to be a good candidate for the immobilization of new high level radioactive wastes. A simplified seven-oxides composition of this glass was selected for this study. In this system, sodium and calcium cations were supposed in other works to simulate respectively all the other alkali (R + = Li + , Rb + , Cs + ) and alkaline-earth (R 2+ = Sr 2+ , Ba 2+ ) cations present in the complex glass composition. Moreover, neodymium or lanthanum are used here to simulate all the rare-earths and actinides occurring in waste solutions. In order to study the impact of the nature of R + and R 2+ cations on both glass structure and melt crystallization tendency during cooling, two glass series were prepared by replacing either Na + or Ca 2+ cations in the simplified glass by respectively (Li + , K + , Rb + , Cs + ) or (Mg 2+ , Sr 2+ , Ba 2+ ) cations. From these substitutions, it was established that alkali ions are preferentially involved in the charge compensation of (AlO 4 ) - entities in the glass network comparatively to alkaline-earth ions. The glass compositions containing calcium give way to the crystallization of an apatite silicate phase bearing calcium and rare-earth ions. The melt crystallization tendency during cooling strongly varies with the nature of the alkaline-earth. (authors)

  7. Devitrification kinetics and phase selection mechanisms in Cu-Zr metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kalay, Ilkay [Iowa State Univ., Ames, IA (United States)

    2010-01-01

    Metallic glasses have been a promising class of materials since their discovery in the 1960s. Indeed, remarkable chemical, mechanical and physical properties have attracted considerable attention, and several excellent reviews are available. Moreover, the special group of glass forming alloys known as the bulk metallic glasses (BMG) become amorphous solids even at relatively low cooling rates, allowing them to be cast in large cross sections, opening the scope of potential applications to include bulk forms and net shape structural applications. Recent studies have been reported for new bulk metallic glasses produced with lower cooling rates, from 0.1 to several hundred K/s. Some of the application products of BMGs include sporting goods, high performance springs and medical devices. Several rapid solidification techniques, including melt-spinning, atomization and surface melting have been developed to produce amorphous alloys. The aim of all these methods is to solidify the liquid phase rapidly enough to suppress the nucleation and growth of crystalline phases. Furthermore, the production of amorphous/crystalline composite (ACC) materials by partial crystallization of amorphous precursor has recently given rise to materials that provide better mechanical and magnetic properties than the monolithic amorphous or crystalline alloys. In addition, these advances illustrate the broad untapped potential of using the glassy state as an intermediate stage in the processing of new materials and nanostructures. These advances underlie the necessity of investigations on prediction and control of phase stability and microstructural dynamics during both solidification and devitrification processes. This research presented in this dissertation is mainly focused on Cu-Zr and Cu-Zr-Al alloy systems. The Cu-Zr binary system has high glass forming ability in a wide compositional range (35-70 at.% Cu). Thereby, Cu-Zr based alloys have attracted much attention according to fundamental

  8. Intraligand Charge Transfer Sensitization on Self-Assembled Europium Tetrahedral Cage Leads to Dual-Selective Luminescent Sensing toward Anion and Cation.

    Science.gov (United States)

    Liu, Cui-Lian; Zhang, Rui-Ling; Lin, Chen-Sheng; Zhou, Li-Peng; Cai, Li-Xuan; Kong, Jin-Tao; Yang, Song-Qiu; Han, Ke-Li; Sun, Qing-Fu

    2017-09-13

    Luminescent supramolecular lanthanide edifices have many potential applications in biology, environments, and materials science. However, it is still a big challenge to improve the luminescent performance of multinuclear lanthanide assemblies in contrast to their mononuclear counterparts. Herein, we demonstrate that combination of intraligand charge transfer (ILCT) sensitization and coordination-driven self-assembly gives birth to bright Eu III tetrahedral cages with a record emission quantum yield of 23.1%. The ILCT sensitization mechanism has been unambiguously confirmed by both time-dependent density functional theory calculation and femtosecond transient absorption studies. Meanwhile, dual-responsive sensing toward both anions and cations has been demonstrated making use of the ILCT transition on the ligand. Without introduction of additional recognition units, high sensitivity and selectivity are revealed for the cage in both turn-off luminescent sensing toward I - and turn-on sensing toward Cu 2+ . This study offers important design principles for the future development of luminescent lanthanide molecular materials.

  9. Investigations of glass structure using fluorescence line narrowing and moleuclar dynamics simulations

    International Nuclear Information System (INIS)

    Weber, M.J.; Brawer, S.A.

    1982-01-01

    The local structure at individual ion sites in simple and multicomponent glasses is simulated using methods of molecular dynamics. Computer simulations of fluoroberyllate glasses predict a range of ion separations and coordination numbers that increases with increasing complexity of the glass composition. This occurs at both glass forming and glass modifying cation sites. Laser-induced fluorescence line-narrowing techniques provide a unique probe of the local environments of selected subsets of ions and are used to measure site to site variations in the electronic energy levels and transition probabilities of rare earth ions. These and additional results from EXAFS, neutron and x-ray diffraction, and NMR experiments are compared with simulated glass structures

  10. Complexing and analysis of cation selectivity of neutral phosphoryl-containing tripodaud of tris((0-diphenyl-phosphinoylmethyl)phenoxyethyl)amine to lithium sodium and potassium, in acetonitrile. Lithium selectivity and polymeclear compleses

    International Nuclear Information System (INIS)

    Baulin, V.E.; Solov'ev, V.P.; Strakhova, N.N.; Kazachenko, V.P.

    1996-01-01

    A new phosphoryl-containing tripodand-tris-[(0-diphenyl-phosphinoylmethyl)phenoxyethyl] amine-was synthesized. Constants of stability, enthalpy and entropy of reactions of tripodond complexing with lithium, sodium, potassium thiocyanates in acetonitrile at 298 k were determined. Investigation of complexing by the methods of calorimetry, 7 Li and 23 Na NMR, mass-spectrometry enabled to conclude that ligand formed polynuclear complexes with lithium thiocyanate of 2/1 and 3/1 composition along with 1/1 complex. High selectivity of podand to lithium cation in acetonitrile was conditioned by formation of polynuclear complexes. Refs. 29, figs. 3

  11. Preparation and characterization of electrically conducting polypyrrole Sn(IV phosphate cation-exchanger and its application as Mn(II ion selective membrane electrode

    Directory of Open Access Journals (Sweden)

    A.A. Khan

    2011-10-01

    Full Text Available Polypyrrole Sn(IV phosphate, an organic–inorganic composite cation-exchanger was synthesized via sol-gel mixing of an organic polymer, polypyrrole, into the matrices of the inorganic precipitate of Sn(IV phosphate. The physico-chemical properties of the material were determined using Atomic Absorption Spectrometry (AAS, CHN elemental analysis (inductively coupled plasma mass spectrometry, ICP-MS, UV–VIS spectrophotometry, FTIR (Fourier Transform Infra-Red, SEM (Scanning Electron Microscopy, TGA–DTA (Thermogravimetric Analysis–Differential Thermal Analysis, and XRD (X-ray diffraction. Ion-exchange behavior was observed to characterize the material. On the basis of distribution studies, the material was found to be highly selective for toxic heavy metal ion Mn2+. Due to its selective nature, the material was used as an electroactive component for the construction of an ion-selective membrane electrode. The proposed electrode shows fairly good discrimination of mercury ion over several other inorganic ions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations for Mn(II in water.

  12. K+/Na+ Selectivity in Toy Cation Binding Site Models Is Determined by the ‘Host’

    Science.gov (United States)

    Bostick, David L.; Arora, Karunesh; Brooks, Charles L.

    2009-01-01

    The macroscopic ion-selective behavior of K+ channels is mediated by a multitude of physiological factors. However, considering the carbonyl-lined binding site of a conductive K+ channel as a canonical eightfold coordinated construct can be useful in understanding the principles that correlate the channel's structure with its function. We probe the effects of structure and chemical composition on the K+/Na+ selectivity provided by a variety of simplified droplet-like ion binding site models. We find that when carbonyl- and water-based models capture the qualitative structural features of the K+ channel binding site, a selective preference for K+ emerges. Thus our findings suggest that the preference for K+ over Na+ exhibited by such models is principally built-in, and is not due to a unique K+-selective property of carbonyl functional groups. This suggestion is confirmed by a general thermodynamic assessment, which provides a basis for using simplified models to study the design principles underlying the molecular evolution of K+ channels. PMID:19450462

  13. Identifi cation of Sectarianism

    Directory of Open Access Journals (Sweden)

    Martinovich Vladimir

    2016-03-01

    Full Text Available «New religious movements and society» is traditionally one of the most sophisticated topics in the area of new religions studies. Its problem field is so huge that up to now by far not all important research themes where even touched by scientists from all over the world. The problem of the process of the identification of sectarianism by diff erent societal institutions is one of such untouched themes that is taken as the main subject of this article. This process by itself is an inseparable part of the every societal deliberate reaction to the very existence of unconventional religiosity, its unstructured and mainly structured types. The focal point of the article is step-by-step analysis of the general structure elements of the process of the identification of sectarianism without any reference to the specific time and place of its flow. Special attention is paid to the analysis of the subjects of the identification of sectarianism, to the criteria for religious groups to be qualified as new religious movements, and to the specific features of the process of documents filtration. The causes of selective perception of sectarianism are disclosed. Some main consequences and unpredictable outcomes of the process of the identification of sectarianism are described.

  14. A new cationic porphyrin derivative (TMPipEOPP with large side arm substituents: a highly selective G-quadruplex optical probe.

    Directory of Open Access Journals (Sweden)

    Li-Na Zhu

    Full Text Available The discovery of uncommon DNA structures and speculation about their potential functions in genes has brought attention to specific DNA structure recognition. G-quadruplexes are four-stranded nucleic acid structures formed by G-rich DNA (or RNA sequences. G-rich sequences with a high potential to form G-quadruplexes have been found in many important genomic regions. Porphyrin derivatives with cationic side arm substituents are important G-quadruplex-binding ligands. For example, 5,10,15,20-Tetrakis(N-methylpyridinium-4-yl-21H,23H-porphyrin (TMPyP4, interacts strongly with G-quadruplexes, but has poor selectivity for G-quadruplex versus duplex DNA. To increase the G-quadruplex recognition specificity, a new cationic porphyrin derivative, 5,10,15,20-tetra-{4-[2-(1-methyl-1-piperidinylethoxy]phenyl} porphyrin (TMPipEOPP, with large side arm substituents was synthesized, and the interactions between TMPipEOPP and different DNA structures were compared. The results show that G-quadruplexes cause large changes in the UV-Vis absorption and fluorescence spectra of TMPipEOPP, but duplex and single-stranded DNAs do not, indicating that TMPipEOPP can be developed as a highly specific optical probe for discriminating G-quadruplex from duplex and single-stranded DNA. Visual discrimination is also possible. Job plot and Scatchard analysis suggest that a complicated binding interaction occurs between TMPipEOPP and G-quadruplexes. At a low [G-quadruplex]/[TMPipEOPP] ratio, one G-quadruplex binds two TMPipEOPP molecules by end-stacking and outside binding modes. At a high [G-quadruplex]/[TMPipEOPP] ratio, two G-quadruplexes bind to one TMPipEOPP molecule in a sandwich-like end-stacking mode.

  15. Amperometric Ion-Selective Electrode for Alkali Metal Cations Based on a Room-Temperature Ionic Liquid Membrane

    Czech Academy of Sciences Publication Activity Database

    Langmaier, Jan; Trojánek, Antonín; Samec, Zdeněk

    2009-01-01

    Roč. 21, 17-18 (2009), s. 1977-1983 ISSN 1040-0397 R&D Projects: GA MŠk ME08098; GA AV ČR IAA400400704 Institutional research plan: CEZ:AV0Z40400503 Keywords : room-temperature ionic liquid * alkali metals * Crown ether * cyclic voltammetry * amperometric ion-selective elkectrode Subject RIV: CG - Electrochemistry Impact factor: 2.630, year: 2009

  16. Evaluation of selectivity and thermodynamic characteristics of doubly charged cations on zirconium titanate from aqueous and alcoholic solutions

    International Nuclear Information System (INIS)

    Zakaria, E.S.; Ali, I.M.; El-Naggar, I.M.

    2005-01-01

    The ion exchange of Ni 2+ /H + and Co 2+ /H + have been determined using solution of 0.1 ionic strength for both forward and backward reactions at 25 degree C by batch technique. The thermodynamic equilibrium constants for the exchange process have been calculated using Gains Thomas equation. The preference series Ni 2+ >Co 2+ was determined. The ion exchange selectivity for exchange of Ni 2 + and Co 2+ ions with hydrogen ions on zirconium titanate have been investigated for aqueous and 25% of methanol and ethanol solutions. The values of thermodynamic functions for the studied systems have been calculated

  17. Effect of ionic strength and cationic DNA affinity binders on the DNA sequence selective alkylation of guanine N7-positions by nitrogen mustards

    International Nuclear Information System (INIS)

    Hartley, J.A.; Forrow, S.M.; Souhami, R.L.

    1990-01-01

    Large variations in alkylation intensities exist among guanines in a DNA sequence following treatment with chemotherapeutic alkylating agents such as nitrogen mustards, and the substituent attached to the reactive group can impose a distinct sequence preference for reaction. In order to understand further the structural and electrostatic factors which determine the sequence selectivity of alkylation reactions, the effect of increase ionic strength, the intercalator ethidium bromide, AT-specific minor groove binders distamycin A and netropsin, and the polyamine spermine on guanine N7-alkylation by L-phenylalanine mustard (L-Pam), uracil mustard (UM), and quinacrine mustard (QM) was investigated with a modification of the guanine-specific chemical cleavage technique for DNA sequencing. The result differed with both the nitrogen mustard and the cationic agent used. The effect, which resulted in both enhancement and suppression of alkylation sites, was most striking in the case of netropsin and distamycin A, which differed from each other. DNA footprinting indicated that selective binding to AT sequences in the minor groove of DNA can have long-range effects on the alkylation pattern of DNA in the major groove

  18. A new set of Cd(ii)-coordination polymers with mixed ligands of dicarboxylate and pyridyl substituted diaminotriazine: selective sorption towards CO2and cationic dyes.

    Science.gov (United States)

    Chand, Santanu; Elahi, Syed Meheboob; Pal, Arun; Das, Madhab C

    2017-08-01

    On the basis of a mixed ligand system of L(NH 2 ) 2 (6-(pyridin-4-yl)-1,3,5-triazine-2,4-diamine) and dicarboxylic acids, three new Cd(ii) coordination polymers viz. {[Cd 0.5 (tdc) 0.5 (L(NH 2 ) 2 ) 0.5 (H 2 O)]·DMF·H 2 O} n (1), {[Cd 0.5 (bdc) 0.5 (L(NH 2 ) 2 )(H 2 O)]·DMF·H 2 O} n (2), and {[Cd(ipa)(L(NH 2 ) 2 )(DMF)]·H 2 O} n (3) (tdcH 2 = thiophene-2,5-dicarboxylic acid, bdcH 2 = benzene-1,4-dicarboxylic acid, ipaH 2 = benzene-1,3-dicarboxylic acid) were synthesized under diverse reaction conditions and characterized by single crystal X-ray diffraction, PXRD, elemental analysis, IR spectroscopy and TGA. While 1 and 2 revealed 1D chain structures, 3 acquired a 2D square net structural arrangement. Gas adsorption measurements of the desolvated framework 3 showed a moderate uptake of CO 2 under ambient conditions with good selectivity over N 2 and CH 4 . The solid state luminescence properties were studied for all three coordination polymers. Moreover, a dye adsorption study on 3 exhibited selective adsorption towards a cationic dye.

  19. Asymmetric cation-binding catalysis

    DEFF Research Database (Denmark)

    Oliveira, Maria Teresa; Lee, Jiwoong

    2017-01-01

    solvents, thus increasing their applicability in synthesis. The expansion of this concept to chiral polyethers led to the emergence of asymmetric cation-binding catalysis, where chiral counter anions are generated from metal salts, particularly using BINOL-based polyethers. Alkali metal salts, namely KF...... and KCN, are selectively bound to the catalyst, providing exceptionally high enantioselectivities for kinetic resolutions, elimination reactions (fluoride base), and Strecker synthesis (cyanide nucleophile). Asymmetric cation-binding catalysis was recently expanded to silicon-based reagents, enabling...

  20. Synthesis and characterisation of nitrogen poly-heterocyclic molecules using as selective complexing agents of metallic cations

    International Nuclear Information System (INIS)

    Alphonse, F.A.

    2003-12-01

    Separation of actinides (III) from lanthanides (III) is a crucial problem in the reprocessing of used nuclear fuels. Experimental results shown that soft donor extractants such as nitrogen polydentate heterocycles containing a NCCNCCN coordination site are potentials ligands for selective extraction of actinides (III). In those cases, two types of liquid-liquid extractions are employed: synergistic combination with lipophilic acid extractants and direct extraction. On the basis of the Hard and Soft Acids and Bases theory and basicity evaluation, new extractants were defined. We have first studied the synthesis of potential 1,3,5-triazine ligands designed for extraction in synergy with α-bromodecanoic acid. Secondly, we have examined the synthesis of bis-triazinyl-pyridine ligands for direct extraction studies. Extraction tests were carried out and perspectives of synthesis were deducted from those extraction results. (author)

  1. pH triggered superior selective adsorption and separation of both cationic and anionic dyes and photocatalytic activity on a fully exfoliated titanate layer-natural polymer based nanocomposite.

    Science.gov (United States)

    Sarkar, Amit Kumar; Saha, Arka; Panda, Asit Baran; Pal, Sagar

    2015-11-18

    A fully exfoliated titanate layer-natural polymer amylopectin based nanocomposite, with pH responsive superior selective adsorption, separation of both cationic (MB: 599 mg g(-1) at pH 9) and anionic (MO: 558 mg g(-1) at pH 3) dyes and photodegradation properties, has been realized through simultaneous in situ layered titanate formation, exfoliation and polymerization.

  2. Bio-active glass air-abrasion has the potential to remove resin composite restorative material selectively

    International Nuclear Information System (INIS)

    Milly, Hussam; Andiappan, Manoharan; Thompson, Ian; Banerjee, Avijit

    2014-01-01

    The aims of this study were to assess: (a) the chemistry, morphology and bioactivity of bio-active glass (BAG) air-abrasive powder, (b) the effect of three air-abrasion operating parameters: air pressure, powder flow rate (PFR) and the abrasive powder itself, on the selective removal of resin composite and (c) the required “time taken”. BAG abrasive particles were characterised using scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and Fourier-transform infrared spectroscopy (FTIR). Standardised resin composite restorations created within an enamel analogue block (Macor™) in vitro, were removed using air-abrasion undersimulated clinical conditions. 90 standardised cavities were scanned before and after resin composite removal using laser profilometry and the volume of the resulting 3D images calculated. Multilevel linear model was used to identify the significant factors affecting Macor™ removal. BAG powder removed resin composite more selectively than conventional air-abrasion alumina powder using the same operating parameters (p < 0.001) and the effect of altering the unit's operating parameters was significant (p < 0.001). In conclusion, BAG powder is more efficient than alumina in the selective removal of resin composite particularly under specific operating parameters, and therefore may be recommended clinically as a method of preserving sound enamel structure when repairing and removing defective resin composite restorations.

  3. Bio-active glass air-abrasion has the potential to remove resin composite restorative material selectively

    Energy Technology Data Exchange (ETDEWEB)

    Milly, Hussam [Biomaterials, Biomimetics and Biophotonics Research Group, Kings College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom); Andiappan, Manoharan [Unit of Dental Public Health, Kings College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom); Thompson, Ian [Biomaterials, Biomimetics and Biophotonics Research Group, Kings College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom); Banerjee, Avijit, E-mail: avijit.banerjee@kcl.ac.uk [Biomaterials, Biomimetics and Biophotonics Research Group, Kings College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom); Unit of Conservative Dentistry, King' s College London Dental Institute at Guy' s Hospital, King' s Health Partners, London (United Kingdom)

    2014-06-01

    The aims of this study were to assess: (a) the chemistry, morphology and bioactivity of bio-active glass (BAG) air-abrasive powder, (b) the effect of three air-abrasion operating parameters: air pressure, powder flow rate (PFR) and the abrasive powder itself, on the selective removal of resin composite and (c) the required “time taken”. BAG abrasive particles were characterised using scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX) and Fourier-transform infrared spectroscopy (FTIR). Standardised resin composite restorations created within an enamel analogue block (Macor™) in vitro, were removed using air-abrasion undersimulated clinical conditions. 90 standardised cavities were scanned before and after resin composite removal using laser profilometry and the volume of the resulting 3D images calculated. Multilevel linear model was used to identify the significant factors affecting Macor™ removal. BAG powder removed resin composite more selectively than conventional air-abrasion alumina powder using the same operating parameters (p < 0.001) and the effect of altering the unit's operating parameters was significant (p < 0.001). In conclusion, BAG powder is more efficient than alumina in the selective removal of resin composite particularly under specific operating parameters, and therefore may be recommended clinically as a method of preserving sound enamel structure when repairing and removing defective resin composite restorations.

  4. Cation-selective extraction column study for the conception of nuclear medical radionuclide generators; Untersuchung kationenselektiver Extraktionssaeulen zur Konzeption nuklearmedizinischer Radionuklidgeneratoren

    Energy Technology Data Exchange (ETDEWEB)

    Streng, Roman

    2012-07-09

    The topic of the present work is the conception of a Yttrium-90 radionuclide generator for nuclear medicine applications. Due to its physical properties Yttrium-90 is considered as one of the most useful nuclides for radiotherapeutic cancer treatment. The parent nuclide Strontium-90 is gained during reprocessing of fission products. Thus, the sustained availability of large quantities of Yttrium-90 is limited to a number of research facilities. A radionuclide generator provides an independent Yttrium-90 source and enhances the capacities for radiopharmaceutical research and biomedical applications. The present work focussed on the identification of appropriate column materials for the separation of Strontium and Yttrium. The results for two materials are reported: AnaLig {sup registered} Sr-01 and crystalline antimonic acid. Based on the mode of operation of the Technetium-99m generator the aim was to enable the construction of a compact, enclosed apparatus. The projected device comprises a reservoir for the eluant, the ion-exchange column, pipings and radiation shielding. Elution of Yttrium-90 could then be easily performed by connecting evacuated vials to the outlet tube. The prospected concept involves physical and chemical confinements that exclude most of the known processes for Strontium-Yttrium separation. For example no ligands, no oxidizing reactants (e.g. nitric acid) and no organic solvents are to be used, but small volumes of isotonic or buffer solutions and dilute acids respectively. AnaLig {sup registered} Sr-01 is a commercially available resin used in extraction chromatography. Its high selectivity for Strontium cations results from the strictly defined cavity of the imbedded cryptand. Determination of weight distribution coefficients, elution studies and pre-generator experiments were carried out. Quantitative separation of Yttrium from Strontium and Zirconium is possible using small volumes of 0,05 M hydrochloric acid as eluant. Furthermore, high

  5. Evaluation of the cytotoxicity of selected conventional glass ionomer cements on human gingival fibroblasts.

    Science.gov (United States)

    Marczuk-Kolada, Grażyna; Łuczaj-Cepowicz, Elżbieta; Pawińska, Małgorzata; Hołownia, Adam

    2017-10-01

    Dentistry materials are the most frequently used substitutes of human tissues. Therefore, an assessment of dental filling materials should cover not only their chemical, physical, and mechanical characteristics, but also their cytotoxicity. To compare the cytotoxic effects of 13 conventional glass ionomer cements on human gingival fibroblasts. The assessment was conducted using the MTT test. Six samples were prepared for each material. Culture plates with cells and inserts with the materials were incubated at 37°C, 5% CO2, and 95% humidity for 24 h. Then the inserts were removed, 1 mL of MTT was added in the amount of 0.5 mg/1 mL of the medium, and the samples were incubated in the described conditions without light for 2 h. The optical density was measured with an absorption spectrophotometer at a wavelength of 560 nm. The cytotoxic effects of the Argion Molar was significantly stronger than the Fuji Triage (p = 0.007), Chemfil Molar (p Quick (p IX GP and Fuji IX Extra had a significantly stronger adverse effect than the Chemfil Molar (p = 0.014, p = 0.029, respectively) and Ionofil Molar AC Quick (p = 0.017, p = 0.034, respectively). The cements from the low cytotoxicity group were significantly more toxic vs materials whose presence resulted in fibroblast growth (p < 0.001). The research conducted indicates that, although the materials studied may belong to the same group, they are characterized by low, yet not uniform, cytotoxicity on human gingival fibroblasts. The toxic effects should not be assigned to a relevant group of materials, but each dentistry product should be evaluated individually.

  6. Development of phosphate glass microspheres containing holmium for selective internal radiotherapy; Desenvolvimento de microesferas de vidro fosfato contendo holmio para uso em radioterapia interna seletiva

    Energy Technology Data Exchange (ETDEWEB)

    Barros Filho, Eraldo Cordeiro

    2016-11-01

    The selective internal radiotherapy is an alternative for some kinds of cancer as the hepatocellular carcinoma (HCC) or primary liver cancer treatment. In this treatment, glass or polymer microspheres containing radionuclides inside their structure are introduced in the liver through hepatic artery and trapped at the arterioles that feed the tumor. In this work, the development of phosphate glasses containing holmium for production of microspheres and their application in Brazil are proposed. The developed glasses presented suitable chemical durability, density of 2,7(3) g/cm{sup 3}, high thermal stability and the impurities contained therein do not preclude the treatment. The microspheres were produced by the flame method and the gravitational fall method, and were characterized by means of several techniques to evaluate shape, average particle size, activity and biocompatibility suitable for selective internal radiotherapy. Based in the main results, the submission to in vivo tests is proposed. (author)

  7. Site-selective spectroscopy in Sm(3+)-doped sol-gel-derived nano-glass-ceramics containing SnO(2) quantum dots.

    Science.gov (United States)

    Yanes, A C; Velázquez, J J; Del-Castillo, J; Méndez-Ramos, J; Rodríguez, V D

    2008-07-23

    Nano-glass-ceramics of composition 95SiO(2)-5SnO(2) doped with 0.4 Sm(3+) (mol%) were synthesized by the thermal treatment of precursor sol-gel glasses. Structural and luminescence measurements were carried out. The precipitated SnO(2) nanocrystals in the glass matrix constitute a wide bandgap quantum-dot system with size comparable to the bulk exciton Bohr radius. A site-selective excitation, by energy transfer from the semiconductor host, reveals that a fraction of the Sm(3+) ions are incorporated in the SnO(2) nanocrystals, whereas the rest remains in the silica glassy phase. An evolution in the Sm(3+) emission spectra has been observed when the SnO(2) nanocrystals are excited with different UV wavelengths, which has been ascribed to selective excitation of nanocrystal sets with predetermined size.

  8. Changes in cationic selectivity of the nicotinic channel at the rat ganglionic synapse: a role for chloride ions?

    Directory of Open Access Journals (Sweden)

    Oscar Sacchi

    Full Text Available The permeability of the nicotinic channel (nAChR at the ganglionic synapse has been examined, in the intact rat superior cervical ganglion in vitro, by fitting the Goldman current equation to the synaptic current (EPSC I-V relationship. Subsynaptic nAChRs, activated by neurally-released acetylcholine (ACh, were thus analyzed in an intact environment as natively expressed by the mature sympathetic neuron. Postsynaptic neuron hyperpolarization (from -40 to -90 mV resulted in a change of the synaptic potassium/sodium permeability ratio (P(K/P(Na from 1.40 to 0.92, corresponding to a reversible shift of the apparent acetylcholine equilibrium potential, E(ACh, by about +10 mV. The effect was accompanied by a decrease of the peak synaptic conductance (g(syn and of the EPSC decay time constant. Reduction of [Cl(-](o to 18 mM resulted in a change of P(K/P(Na from 1.57 (control to 2.26, associated with a reversible shift of E(ACh by about -10 mV. Application of 200 nM αBgTx evoked P(K/P(Na and g(syn modifications similar to those observed in reduced [Cl(-](o. The two treatments were overlapping and complementary, as if the same site/mechanism were involved. The difference current before and after chloride reduction or toxin application exhibited a strongly positive equilibrium potential, which could not be explained by the block of a calcium component of the EPSC. Observations under current-clamp conditions suggest that the driving force modification of the EPSC due to P(K/P(Na changes represent an additional powerful integrative mechanism of neuron behavior. A possible role for chloride ions is suggested: the nAChR selectivity was actually reduced by increased chloride gradient (membrane hyperpolarization, while it was increased, moving towards a channel preferentially permeable for potassium, when the chloride gradient was reduced.

  9. Changes in cationic selectivity of the nicotinic channel at the rat ganglionic synapse: a role for chloride ions?

    Science.gov (United States)

    Sacchi, Oscar; Rossi, Maria Lisa; Canella, Rita; Fesce, Riccardo

    2011-02-25

    The permeability of the nicotinic channel (nAChR) at the ganglionic synapse has been examined, in the intact rat superior cervical ganglion in vitro, by fitting the Goldman current equation to the synaptic current (EPSC) I-V relationship. Subsynaptic nAChRs, activated by neurally-released acetylcholine (ACh), were thus analyzed in an intact environment as natively expressed by the mature sympathetic neuron. Postsynaptic neuron hyperpolarization (from -40 to -90 mV) resulted in a change of the synaptic potassium/sodium permeability ratio (P(K)/P(Na)) from 1.40 to 0.92, corresponding to a reversible shift of the apparent acetylcholine equilibrium potential, E(ACh), by about +10 mV. The effect was accompanied by a decrease of the peak synaptic conductance (g(syn)) and of the EPSC decay time constant. Reduction of [Cl(-)](o) to 18 mM resulted in a change of P(K)/P(Na) from 1.57 (control) to 2.26, associated with a reversible shift of E(ACh) by about -10 mV. Application of 200 nM αBgTx evoked P(K)/P(Na) and g(syn) modifications similar to those observed in reduced [Cl(-)](o). The two treatments were overlapping and complementary, as if the same site/mechanism were involved. The difference current before and after chloride reduction or toxin application exhibited a strongly positive equilibrium potential, which could not be explained by the block of a calcium component of the EPSC. Observations under current-clamp conditions suggest that the driving force modification of the EPSC due to P(K)/P(Na) changes represent an additional powerful integrative mechanism of neuron behavior. A possible role for chloride ions is suggested: the nAChR selectivity was actually reduced by increased chloride gradient (membrane hyperpolarization), while it was increased, moving towards a channel preferentially permeable for potassium, when the chloride gradient was reduced.

  10. Selective entrapment of the cationic form of norfloxacin within anionic sodium dodecyl sulfate micelles at physiological pH and its effect on the drug photodecomposition.

    Science.gov (United States)

    Sortino, Salvatore

    2006-01-01

    The binding of the photosensitizing fluoroquinolone (FQ) antibiotic norfloxacin (NX) to sodium dodecyl sulfate (SDS) micelles and the photoreactivity of the NX/SDS complex under physiological pH conditions are investigated by means of absorption and emission spectroscopy, steady-state and laser flash photolysis. It is shown that the photolabile zwitterionic form of NX, which is dominant at physiological pH, is not the most abundant species in the presence of SDS micelles. This medium exhibits a high preference for the cationic form of the drug, which is selectively and successfully entrapped within the micellar cage (K(ass) = 6 x 10(4) M(-1) +/- 3000), becoming the largely dominant species at neutral pH. The effect of this trapping is drastically reflected on both efficiency and nature of the drug photodecomposition. It is observed that the photostability of NX incorporated in the micellar pseudophase increases of more than one order of magnitude if compared to that of the "free" drug. Furthermore, the radical photodecomposition mechanism occurring in phosphate buffered solution is suppressed by the micellar medium and the low photodegradation observed seems to take place preferentially through an ionic pathway. Hopefully, the results presented herein may contribute to a better understanding of the bio-distribution of NX in biological systems and provide helpful and stimulating information in order to get the control of FQ photoreactivity under physiological pH conditions.

  11. Selective sorption of lead, cadmium and zinc ions by a polymeric cation exchanger containing nano-Zr(HPO3S)2.

    Science.gov (United States)

    Zhang, Qingrui; Pan, Bingcai; Pan, Bingjun; Zhang, Weiming; Jia, Kun; Zhang, Quanxing

    2008-06-01

    A novel polymeric hybrid sorbent, namely ZrPS-001, was fabricated for enhanced sorption of heavy metal ions by impregnating Zr(HPO3S)2 (i.e., ZrPS) nanoparticles within a porous polymeric cation exchanger D-001. The immobilized negatively charged groups bound to the polymeric matrix D-001 would result in preconcentration and permeation enhancement of target metal ions prior to sequestration, and ZrPS nanoparticles are expected to sequester heavy metals selectively through an ion-exchange process. Highly effective sequestration of lead, cadmium, and zinc ions from aqueous solution can be achieved by ZrPS-001 even in the presence of competing calcium ion at concentration several orders of magnitude greater than the target species. The exhausted ZrPS-001 beads are amenable to regeneration with 6 M HCI solution for repeated use without any significant capacity loss. Fixed-bed column treatment of simulated waters containing heavy metals at high or trace levels was also performed. The content of heavy metals in treated effluent approached or met the WHO drinking water standard.

  12. Differential effects of lysophosphatidylcholine and ACh on muscarinic K(+),non-selective cation and Ca(2+) currents in guinea-pig atrial cells.

    Science.gov (United States)

    Li, Libing; Matsuoka, Isao; Sakamoto, Kazuho; Kimura, Junko

    2016-06-08

    We compared the effects of lysophosphatidylcholine (LPC) and acetylcholine (ACh) on IK(ACh), ICa and a non-selective cation current (INSC) in guinea-pig atrial myocytes to clarify whether LPC and ACh activate similar Gi/o-coupled effector systems. IK(ACh), ICa and INSC were analyzed in single atrial myocytes by the whole cell patch-clamp. LPC induced INSC in a concentration-dependent manner in atrial cells. ACh activated IK(ACh), but failed to evoke INSC. LPC also activated IK(ACh) but with significantly less potency than ACh. The effects of both ligands on IK(ACh) were inhibited by intracellular loading of pre-activated PTX. This treatment also inhibited LPC-induced INSC, indicating that IK(ACh) and INSC induced by LPC are both mediated by Gi/o. LPC and ACh had similar potencies in inhibiting ICa, which was pre-augmented by forskolin, indicating that LPC and ACh activate similar amounts of α-subunits of Gi/o. The different effects of LPC and ACh on IK(ACh) and INSC may suggest that LPC and ACh activate Gi/o having different types of βγ subunits, and that LPC-induced INSC may be mediated by βγ subunits of Gi/o, which are less effective in inducing IK(ACh).

  13. Differential effects of lysophosphatidylcholine and ACh on muscarinic K+, non-selective cation and Ca2+ currents in guinea-pig atrial cells

    Science.gov (United States)

    Li, Libing; Matsuoka, Isao; Sakamoto, Kazuho; Kimura, Junko

    2016-01-01

    Abstract We compared the effects of lysophosphatidylcholine (LPC) and acetylcholine (ACh) on IK(ACh), ICa and a non-selective cation current (INSC) in guinea-pig atrial myocytes to clarify whether LPC and ACh activate similar Gi/o-coupled effector systems. IK(ACh), ICa and INSC were analyzed in single atrial myocytes by the whole cell patch-clamp. LPC induced INSC in a concentration-dependent manner in atrial cells. ACh activated IK(ACh), but failed to evoke INSC. LPC also activated IK(ACh) but with significantly less potency than ACh. The effects of both ligands on IK(ACh) were inhibited by intracellular loading of pre-activated PTX. This treatment also inhibited LPC-induced INSC, indicating that IK(ACh) and INSC induced by LPC are both mediated by Gi/o. LPC and ACh had similar potencies in inhibiting ICa, which was pre-augmented by forskolin, indicating that LPC and ACh activate similar amounts of α-subunits of Gi/o. The different effects of LPC and ACh on IK(ACh) and INSC may suggest that LPC and ACh activate Gi/o having different types of βγ subunits, and that LPC-induced INSC may be mediated by βγ subunits of Gi/o, which are less effective in inducing IK(ACh). PMID:26911304

  14. Site-selective photochemistry and vibrational analysis of matrix-isolated 1,3,5,7-octatetraene radical cations in different conformations

    International Nuclear Information System (INIS)

    Bally, T.; Nitsche, S.; Roth, K.

    1986-01-01

    Upon ionization by x irradiation, all-trans 1,3,5,7-octatetraene (OT) gives an electronic absorption (EA) spectrum which indicates the formation of at least five different (peri)planar conformations (''rotamers'') of OT/sup +/ next to the parent cation. Some of these undergo specific photochemical interconversions which are discussed on the basis of a complete scheme of OT/sup +/ rotamers and their connections via single bond-rotation processes. None of these photoreactions lead to any other than the initially observed six species which seem to form a distinguished set within the 20 possible OT/sup +/ rotamers. By very narrow bandwidth irradiation, interconversions can be induced to take place in a site-selective fashion. The resulting well-resolved difference spectra allow an analysis of the site dependence of the different ion's first two EA bands. Surprisingly, the extent of this site dependence varies greatly between different OT/sup +/ rotamers and between different electronic transitions of a given rotamer. Finally, a detailed vibrational analysis of the first two absorption bands of all-trans OT/sup +/ is given

  15. Determination of Nicotine in Tobacco by Chemometric Optimization and Cation-Selective Exhaustive Injection in Combination with Sweeping-Micellar Electrokinetic Chromatography

    Directory of Open Access Journals (Sweden)

    Yi-Hui Lin

    2015-01-01

    Full Text Available Nicotine is a potent chemical that excites the central nervous system and refreshes people. It is also physically addictive and causes dependence. To reduce the harm of tobacco products for smokers, a law was introduced that requires tobacco product containers to be marked with the amount of nicotine as well as tar. In this paper, an online stacking capillary electrophoresis (CE method with cation-selective exhaustive injection sweeping-micellar electrokinetic chromatography (CSEI-sweeping-MEKC is proposed for the optimized analysis of nicotine in tobacco. A higher conductivity buffer (160 mM phosphate buffer (pH 3 zone was injected into the capillary, allowing for the analytes to be electrokinetically injected at a voltage of 15 kV for 15 min. Using 50 mM sodium dodecyl sulfate and 25% methanol in the sweeping buffer, nicotine was detected with high sensitivity. Thus, optimized conditions adapted from a chemometric approach provided a 6000-fold increase in the nicotine detection sensitivity using the CSEI-sweeping-MEKC method in comparison to normal CZE. The limits of detection were 0.5 nM for nicotine. The stacking method in combination with direct injection which matrix components would not interfere with assay performance was successfully applied to the detection of nicotine in tobacco samples.

  16. Complexation of trivalent cationic lanthanides by N.O donor ligands: physico-chemical studies of the association and selectivity in solution

    International Nuclear Information System (INIS)

    Bravard, F.

    2004-01-01

    The aim of this work is to study the complexation of f-elements in solution by ligands incorporating N-heterocyclic donors. These ligands display interesting properties for the selective separation of An(III)/Ln(III) have been studied to obtain a better understanding of the coordination properties with f-elements and to develop more selective extractants. The hepta-dentate ligand tpaam shows an affinity for Ln(III) similar to the tetradentate ligand tpa in water even when the three additional amide groups are bonded to the metal. Even though the complexation with tpa is exothermic, that with tpaam is endothermic with a more positive entropy. The dehydration of the cation disfavours the formation of Ln(III) complexes with ligands containing weak donors. The analysis of the solution paramagnetic relaxation times of the tpaam complexes is in agreement with data in the solid-state. There is little difference between the formation constants of the Ln 3+ complexes with different ligands (tpaam, tpzen, tpa and tpza) as determined by UV-vis spectrophotometry in anhydrous acetonitrile. The limitations encountered during this study are intrinsic to the ligands studied. The preliminary study of two tetrapodal ligands containing acid and pyridine groups (L py )or pyrazine (L pz ) show the formation of 1:1 complexes in water. Analysis of the formation constants of the corresponding Gd(III) complexes shows that replacement of a pyridine group by pyrazine result in a loss of stability of 1.6 logarithmic units. (author) [fr

  17. Radiochemical investigation of the processes which determine the ionic sensitivity of cadmium-selective electrodes based on chalcogenide glasses. I. Exchange of cadmium ions

    International Nuclear Information System (INIS)

    Vlasov, Yu.G.; Miloshova, M.S.; Moreno, R.A.; Bychkov, E.A.; Antonov, P.P.

    1988-01-01

    The exchange of cadmium ions between solutions and a cadmium-containing chalcogenide glass of the cadmium iodide-silver sulfide-arsenic sulfide system, which is used as a membrane in ion-selective electrodes, was studied by means of the radioactive 115m Cd isotope. It was shown that the exchange of cadmium ions obeys identical relationships both in the case of the labeled glass and in the case of the solution containing radioactive cadmium nitrate. The exchange of cadmium ions is proportional to the concentration of cadmium nitrate in the solution

  18. Weeping Glass: The Identification of Ionic Species on the Surface of Vessel Glass Using Ion Chromatography

    NARCIS (Netherlands)

    Verhaar, G.; van Bommel, M.R.; Tennent, N.H.; Roemich, H.; Fair, L.

    2016-01-01

    Aqueous films on the surface of unstable vessel glass were analysed. Five cation and eight anion species from eleven glass items in the Rijksmuseum, Amsterdam, the Hamburg Museum and the Corning Museum of Glass have been quantified by ion chromatography. Sodium, potassium, magnesium and calcium

  19. ADSORPTION METHOD FOR SEPARATING METAL CATIONS

    Science.gov (United States)

    Khym, J.X.

    1959-03-10

    The chromatographic separation of fission product cations is discussed. By use of this method a mixture of metal cations containing Zr, Cb, Ce, Y, Ba, and Sr may be separated from one another. Mentioned as preferred exchange adsorbents are resins containing free sulfonic acid groups. Various eluants, such as tartaric acid, HCl, and citric acid, used at various acidities, are employed to effect the selective elution and separation of the various fission product cations.

  20. ACh-induced depolarization in inner ear artery is generated by activation of a TRP-like non-selective cation conductance and inactivation of a potassium conductance.

    Science.gov (United States)

    Ma, Ke-Tao; Guan, Bing-Cai; Yang, Yu-Qin; Zhao, Hui; Jiang, Zhi-Gen

    2008-05-01

    Adequate cochlear blood supply by the spiral modiolar artery (SMA) is critical for normal hearing. ACh may play a role in neuroregulation of the SMA but several key issues including its membrane action mechanisms remain poorly understood. Besides its well-known endothelium-dependent hyperpolarizing action, ACh can induce a depolarization in vascular cells. Using intracellular and whole-cell recording techniques on cells in guinea pig in vitro SMA, we studied the ionic mechanism underlying the ACh-depolarization and found that: (1) ACh induced a DAMP-sensitive depolarization when intermediate conductance KCa channels were blocked by charybdotoxin or nitrendipine. The ACh-depolarization was associated with a decrease in input resistance (R(input)) in high membrane potential (V(m)) ( approximately -40 mV) cells but with no change or an increase in R input in low Vm ( approximately -75 mV) cells. ACh-depolarization was attenuated by background membrane depolarization from approximately -70 mV in the majority of cells; (2) ACh-induced inward current in smooth muscle cells embedded in a SMA segment often showed a U-shaped I/V curve, the reversal potential of its two arms being near EK and 0 mV, respectively; (3) ACh-depolarization was reduced by low Na+, zero K+ or 20mM K+ bath solutions; (4) ACh-depolarization was inhibited by La3+ in all cells tested, by 4-AP and flufenamic acid in low Vm cells, but was not sensitive to Cd2+, Ni2+, nifedipine, niflumic acid, DIDS, IAA94, linopirdine or amiloride. We conclude that ACh-induced vascular depolarization was generated mainly by activation of a TRP-like non-selective cation channel and by inactivation of an inward rectifier K+ channel.

  1. Liquid-solid extraction of cationic metals by cationic amphiphiles

    International Nuclear Information System (INIS)

    Muller, W.

    2010-01-01

    In the field of selective separation for recycling of spent nuclear fuel, liquid-liquid extraction processes are widely used (PUREX, DIAMEX..) in industrial scale. In order to guarantee a sustainable nuclear energy for the forthcoming generations, alternative reprocessing techniques are under development. One of them bases on the studies from Heckmann et al in the 80's and consists in selectively precipitating actinides from aqueous waste solutions by cationic surfactants (liquid-solid extraction). This technique has some interesting advantages over liquid-liquid extraction techniques, because several steps are omitted like stripping or solvent washing. Moreover, the amount of waste is decreased considerably, since no contaminated organic solvent is produced. In this thesis, we have carried out a physico-chemical study to understand the specific interactions between the metallic cations with the cationic surfactant. First, we have analysed the specific effect of the different counter-ions (Cl - , NO 3 - , C 2 O 4 2- ) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu 2+ , Zn 2+ , UO 2 2+ , Fe 3+ , Nd 3+ , Eu 3+ , Th 4+ ) were considered; we have concluded that depending on the anionic complex of these metals formed in acidic media, we can observe either an adsorption at the micellar interface or not. This adsorption has a large influence of the surfactant aggregation properties and determines the limits of the application in term of ionic strength, temperature and surfactant concentration. (author) [fr

  2. Surface patterning of Zr-based metallic glass by laser irradiation induced selective thermoplastic extrusion in nitrogen gas

    Science.gov (United States)

    Huang, Hu; Yan, Jiwang

    2017-07-01

    Hierarchical surface structures on metallic glass (MG) are useful for enhancing the material’s functions. In this paper, surface patterning of Zr-based MG was realized by nanosecond pulsed laser irradiation in nitrogen gas. Experimental results showed that three kinds of surface structures, namely, micro grooves, cross-shaped protrusions, and nanoparticles, were generated on the MG surface under specific laser scanning speeds and various laser power intensities and pulse overlap rates. In particular, the formation of cross-shaped protrusions has never been reported in the literature before. The formation mechanism for each kind of surface structure was investigated. In a nitrogen gas environment, cracks are easily generated and the cracked regions have higher laser absorption and localized thermal resistivity than those of the bulk material. Accordingly, the cross-shaped protrusions were ascribed to the selective thermoplastic extrusion of MG material out of the cracks and the laser pulse tracks formed by the preceding laser scans. It was found that the hierarchical surface structures significantly improved the surface hydrophobicity.

  3. Mixed hemimicelles solid-phase extraction based on sodium dodecyl sulfate-coated nano-magnets for selective adsorption and enrichment of illegal cationic dyes in food matrices prior to high-performance liquid chromatography-diode array detection detection.

    Science.gov (United States)

    Qi, Ping; Liang, Zhi-An; Wang, Yu; Xiao, Jian; Liu, Jia; Zhou, Qing-Qiong; Zheng, Chun-Hao; Luo, Li-Ni; Lin, Zi-Hao; Zhu, Fang; Zhang, Xue-Wu

    2016-03-11

    In this study, mixed hemimicelles solid-phase extraction (MHSPE) based on sodium dodecyl sulfate (SDS) coated nano-magnets Fe3O4 was investigated as a novel method for the extraction and separation of four banned cationic dyes, Auramine O, Rhodamine B, Basic orange 21 and Basic orange 22, in condiments prior to HPLC detection. The main factors affecting the extraction of analysts, such as pH, surfactant and adsorbent concentrations and zeta potential were studied and optimized. Under optimized conditions, the proposed method was successful applied for the analysis of banned cationic dyes in food samples such as chili sauce, soybean paste and tomato sauce. Validation data showed the good recoveries in the range of 70.1-104.5%, with relative standard deviations less than 15%. The method limits of determination/quantification were in the range of 0.2-0.9 and 0.7-3μgkg(-1), respectively. The selective adsorption and enrichment of cationic dyes were achieved by the synergistic effects of hydrophobic interactions and electrostatic attraction between mixed hemimicelles and the cationic dyes, which also resulted in the removal of natural pigments interferences from sample extracts. When applied to real samples, RB was detected in several positive samples (chili powders) within the range from 0.042 to 0.177mgkg(-1). These results indicate that magnetic MHSPE is an efficient and selective sample preparation technique for the extraction of banned cationic dyes in a complex matrix. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Selecting polymers for two-phase partitioning bioreactors (TPPBs): Consideration of thermodynamic affinity, crystallinity, and glass transition temperature.

    Science.gov (United States)

    Bacon, Stuart L; Peterson, Eric C; Daugulis, Andrew J; Parent, J Scott

    2015-01-01

    Two-phase partitioning bioreactor technology involves the use of a secondary immiscible phase to lower the concentration of cytotoxic solutes in the fermentation broth to subinhibitory levels. Although polymeric absorbents have attracted recent interest due to their low cost and biocompatibility, material selection requires the consideration of properties beyond those of small molecule absorbents (i.e., immiscible organic solvents). These include a polymer's (1) thermodynamic affinity for the target compound, (2) degree of crystallinity (wc ), and (3) glass transition temperature (Tg ). We have examined the capability of three thermodynamic models to predict the partition coefficient (PC) for n-butyric acid, a fermentation product, in 15 polymers. Whereas PC predictions for amorphous materials had an average absolute deviation (AAD) of ≥16%, predictions for semicrystalline polymers were less accurate (AAD ≥ 30%). Prediction errors were associated with uncertainties in determining the degree of crystallinity within a polymer and the effect of absorbed water on n-butyric acid partitioning. Further complications were found to arise for semicrystalline polymers, wherein strongly interacting solutes increased the polymer's absorptive capacity by actually dissolving the crystalline fraction. Finally, we determined that diffusion limitations may occur for polymers operating near their Tg , and that the Tg can be reduced by plasticization by water and/or solute. This study has demonstrated the impact of basic material properties that affects the performance of polymers as sequestering phases in TPPBs, and reflects the additional complexity of polymers that must be taken into account in material selection. © 2015 American Institute of Chemical Engineers.

  5. Glass Microspheres 90Y Selective Internal Radiation Therapy and Chemotherapy as First-Line Treatment of Intrahepatic Cholangiocarcinoma.

    Science.gov (United States)

    Edeline, Julien; Du, Fanny Le; Rayar, Michel; Rolland, Yan; Beuzit, Luc; Boudjema, Karim; Rohou, Tanguy; Latournerie, Marianne; Campillo-Gimenez, Boris; Garin, Etienne; Boucher, Eveline

    2015-11-01

    Intrahepatic cholangiocarcinoma's incidence is increasing. We studied the efficacy of Y selective internal radiation therapy (SIRT) as first-line treatment, with chemotherapy, and compared with the results of chemotherapy alone. We retrospectively studied data from patients treated at our institution with glass microspheres SIRT for intrahepatic cholangiocarcinoma as part of first-line treatment in combination with chemotherapy. We compared results with those of similar patients treated in the ABC-02 study (a study in advanced biliary tract cancer that defined the current standard chemotherapy), assessed as not progressing after the first evaluation. We assessed progression-free survival (PFS) and overall survival (OS). Twenty-four patients were treated with SIRT. Chemotherapy was given concomitantly in 10 (42%), as induction before SIRT in 13 (54%) or after SIRT in 1 (4%). Grade 3 adverse events were reported in 1 (4%). Median PFS after SIRT was 10.3 months. Longer PFS was observed when chemotherapy was given concomitantly than when chemotherapy was given before SIRT, with respective median of 20.0 versus 8.8 months (P = 0.001). Median OS after SIRT was not reached. Eleven patients went to surgery (46%). Thirty-three patients in ABC-02 had locally advanced nonextrahepatic cholangiocarcinoma, not progressing after first evaluation. From the start of any treatment, the median PFS was 16.0 months in our cohort versus 11.3 months in ABC-02 (P = 0.25), whereas the median OS was significantly higher in our cohort, not reached versus 17.9 months, respectively (P = 0.026). Selective internal radiation therapy combined with concomitant chemotherapy seems a promising strategy as first-line treatment for unresectable intrahepatic cholangiocarcinoma.

  6. Information-theoretical feature selection using data obtained by Scanning Electron Microscopy coupled with and Energy Dispersive X-ray spectrometer for the classification of glass traces

    International Nuclear Information System (INIS)

    Ramos, Daniel; Zadora, Grzegorz

    2011-01-01

    Highlights: → A selection of the best features for multivariate forensic glass classification using SEM-EDX was performed. → The feature selection process was carried out by means of an exhaustive search, with an Empirical Cross-Entropy objective function. → Results show remarkable accuracy of the best variables selected following the proposed procedure for the task of classifying glass fragments into windows or containers. - Abstract: In this work, a selection of the best features for multivariate forensic glass classification using Scanning Electron Microscopy coupled with an Energy Dispersive X-ray spectrometer (SEM-EDX) has been performed. This has been motivated by the fact that the databases available for forensic glass classification are sparse nowadays, and the acquisition of SEM-EDX data is both costly and time-consuming for forensic laboratories. The database used for this work consists of 278 glass objects for which 7 variables, based on their elemental compositions obtained with SEM-EDX, are available. Two categories are considered for the classification task, namely containers and car/building windows, both of them typical in forensic casework. A multivariate model is proposed for the computation of the likelihood ratios. The feature selection process is carried out by means of an exhaustive search, with an Empirical Cross-Entropy (ECE) objective function. The ECE metric takes into account not only the discriminating power of the model in use, but also its calibration, which indicates whether or not the likelihood ratios are interpretable in a probabilistic way. Thus, the proposed model is applied to all the 63 possible univariate, bivariate and trivariate combinations taken from the 7 variables in the database, and its performance is ranked by its ECE. Results show remarkable accuracy of the best variables selected following the proposed procedure for the task of classifying glass fragments into windows (from cars or buildings) or containers

  7. Lap shear strength of selected adhesives (epoxy, varnish, B-stage glass cloth) in liquid nitrogen and at room temperature

    International Nuclear Information System (INIS)

    Froelich, K.J.; Fitzpatrick, C.M.

    1976-12-01

    The adhesives included several epoxy resins, a varnish, and a B-stage glass cloth (a partially cured resin in a fiberglass cloth matrix). Several parameters critical to bond strength were varied: adhesive and adherend differences, surface preparation, coupling agents, glass cloth, epoxy thickness, fillers, and bonding pressure and temperature. The highest lap shear strengths were obtained with the B-shear glass cloth at both liquid nitrogen and room temperatures with values of approximately 20 MPa (3000 psi) and approximately 25.5 MPa (3700 psi) respectively

  8. Sorption by cation exchange

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.

    1994-04-01

    A procedure for introducing exchange into geochemical/surface complexation codes is described. Beginning with selectivity coefficients, K c , defined in terms of equivalent fractional ion occupancies, a general expression for the molar based exchange code input parameters, K ex , is derived. In natural systems the uptake of nuclides onto complex sorbents often occurs by more than one mechanism. The incorporation of cation exchange and surface complexation into a geochemical code therefore enables sorption by both mechanisms to be calculated simultaneously. The code and model concepts are tested against sets of experimental data from widely different sorption studies. A proposal is made to set up a data base of selectivity coefficients. Such a data base would form part of a more general one consisting of sorption mechanism specific parameters to be used in conjunction with geochemical/sorption codes to model and predict sorption. (author) 6 figs., 6 tabs., 26 refs

  9. A Ferrocene-Quinoxaline Derivative as a Highly Selective Probe for Colorimetric and Redox Sensing of Toxic Mercury(II Cations

    Directory of Open Access Journals (Sweden)

    Antonio Caballero

    2010-12-01

    Full Text Available A new chemosensor molecule 3 based on a ferrocene-quinoxaline dyad recognizes mercury (II cations in acetonitrile solution. Upon recognition, an anodic shift of the ferrocene/ferrocenium oxidation peaks and a progressive red-shift (Δλ = 140 nm of the low-energy band, are observed in its absorption spectrum. This change in the absorption spectrum is accompanied by a colour change from orange to deep green, which can be used for a “naked-eye” detection of this metal cation.

  10. Baseline LAW Glass Formulation Testing

    Energy Technology Data Exchange (ETDEWEB)

    Kruger, Albert A. [USDOE Office of River Protection, Richland, WA (United States); Mooers, Cavin [The Catholic University of America, Washington, DC (United States). Vitreous State Lab.; Bazemore, Gina [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Pegg, Ian L. [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Hight, Kenneth [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Lai, Shan Tao [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Buechele, Andrew [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Rielley, Elizabeth [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Gan, Hao [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Muller, Isabelle S. [The Catholic University of America, Washington, DC (United States). Vitreous State Lab; Cecil, Richard [The Catholic University of America, Washington, DC (United States). Vitreous State Lab

    2013-06-13

    The major objective of the baseline glass formulation work was to develop and select glass formulations that are compliant with contractual and processing requirements for each of the LAW waste streams. Other objectives of the work included preparation and characterization of glasses with respect to the properties of interest, optimization of sulfate loading in the glasses, evaluation of ability to achieve waste loading limits, testing to demonstrate compatibility of glass melts with melter materials of construction, development of glass formulations to support ILAW qualification activities, and identification of glass formulation issues with respect to contract specifications and processing requirements.

  11. Isomerization of propargyl cation to cyclopropenyl cation ...

    Indian Academy of Sciences (India)

    step) for isomerization of the linear propargyl cation to the aromatic cyclopropenyl cation, also probing the phenomenon of solvation of this reaction by simple lone pair donors (NH3, H2O, H2S and HF) which bind to the substrate at two sites.

  12. Information-theoretical feature selection using data obtained by scanning electron microscopy coupled with and energy dispersive X-ray spectrometer for the classification of glass traces.

    Science.gov (United States)

    Ramos, Daniel; Zadora, Grzegorz

    2011-10-31

    In this work, a selection of the best features for multivariate forensic glass classification using Scanning Electron Microscopy coupled with an Energy Dispersive X-ray spectrometer (SEM-EDX) has been performed. This has been motivated by the fact that the databases available for forensic glass classification are sparse nowadays, and the acquisition of SEM-EDX data is both costly and time-consuming for forensic laboratories. The database used for this work consists of 278 glass objects for which 7 variables, based on their elemental compositions obtained with SEM-EDX, are available. Two categories are considered for the classification task, namely containers and car/building windows, both of them typical in forensic casework. A multivariate model is proposed for the computation of the likelihood ratios. The feature selection process is carried out by means of an exhaustive search, with an Empirical Cross-Entropy (ECE) objective function. The ECE metric takes into account not only the discriminating power of the model in use, but also its calibration, which indicates whether or not the likelihood ratios are interpretable in a probabilistic way. Thus, the proposed model is applied to all the 63 possible univariate, bivariate and trivariate combinations taken from the 7 variables in the database, and its performance is ranked by its ECE. Results show remarkable accuracy of the best variables selected following the proposed procedure for the task of classifying glass fragments into windows (from cars or buildings) or containers, obtaining high (almost perfect) discriminating power and good calibration. This allows the proposed models to be used in casework. We also present an in-depth analysis which reveals the benefits of the proposed ECE metric as an assessment tool for classification models based on likelihood ratios. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Selective formation of GaN-based nanorod heterostructures on soda-lime glass substrates by a local heating method

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Young Joon; Kim, Yong-Jin [Department of Materials Science and Engineering, POSTECH, Pohang, Gyeongbuk 790-784 (Korea, Republic of); Jeon, Jong-Myeong; Kim, Miyoung; Choi, Jun Hee [Department of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of); Baik, Chan Wook; Kim, Sun Il; Park, Sung Soo; Kim, Jong Min [Frontier Research Laboratory, Samsung Advanced Institute of Technology, PO Box 111, Kiheung 446-712 (Korea, Republic of); Yi, Gyu-Chul, E-mail: joonie.choi@samsung.com, E-mail: gcyi@snu.ac.kr [National Creative Research Initiative Center for Semiconductor Nanorods, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2011-05-20

    We report on the fabrication of high-quality GaN on soda-lime glass substrates, heretofore precluded by both the intolerance of soda-lime glass to the high temperatures required for III-nitride growth and the lack of an epitaxial relationship with amorphous glass. The difficulties were circumvented by heteroepitaxial coating of GaN on ZnO nanorods via a local microheating method. Metal-organic chemical vapor deposition of ZnO nanorods and GaN layers using the microheater arrays produced high-quality GaN/ZnO coaxial nanorod heterostructures at only the desired regions on the soda-lime glass substrates. High-resolution transmission electron microscopy examination of the coaxial nanorod heterostructures indicated the formation of an abrupt, semicoherent interface. Photoluminescence and cathodoluminescence spectroscopy was also applied to confirm the high optical quality of the coaxial nanorod heterostructures. Mg-doped GaN/ZnO coaxial nanorod heterostructure arrays, whose GaN shell layers were grown with various different magnesocene flow rates, were further investigated by using photoluminescence spectroscopy for the p-type doping characteristics. The suggested method for fabrication of III-nitrides on glass substrates signifies potentials for low-cost and large-size optoelectronic device applications.

  14. Extended-range order in glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ellison, A.J.G.; Price, D.L.; Saboungi, M.L. [Argonne National Lab., IL (United States); Egami, T.; Hu, Rui-Zhong [Pennsylvania Univ., Philadelphia, PA (United States); Howells, W.S. [Rutherford Appleton Lab., Chilton (United Kingdom)

    1994-03-01

    A new type of order is identified in complex glasses, characterized by diffraction peaks at values of the wave vector below those typical of intermediate-range order. Combined neutron and anomalous x-ray diffraction studies of one glass exhibiting this behavior, vitreous rubidium germanate, indicate it to be associated with chemical ordering of the two cations with respect to each other.

  15. Synthesis and Ion-Exchange Properties of Graphene Th(IV) Phosphate Composite Cation Exchanger: Its Applications in the Selective Separation of Lead Metal Ions

    OpenAIRE

    Rangreez, Tauseef Ahmad; Inamuddin,; Asiri, Abdullah M.; Alhogbi, Basma G.; Naushad, Mu.

    2017-01-01

    In this study, graphene Th(IV) phosphate was prepared by sol?gel precipitation method. The ion-exchange behavior of this cation-exchanger was studied by investigating properties like ion-exchange capacity for various metal ions, the effect of eluent concentration, elution behavior, and thermal effect on ion-exchange capacity (IEC). Several physicochemical properties as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) study, thermal studies, scanning electron microscopy ...

  16. Selective Transport of Silver(I) Cation Across a Bulk Liquid Membrane Containing Bis-β-enamino Ester as Ion Carrier

    OpenAIRE

    Tarahomi,Somayeh; Rounaghi,Gholam Hossein; Eshghi,Hossein; Daneshvar,Leili; Chamsaz,Mahmoud

    2017-01-01

    Facilitated transport of silver(I) cation across a bulk liquid membrane by two synthesized ligands, bis-β-enamino ester (BBEE) and bis(benzoic acid) trioxaheptane (BBAT), as carriers dissolved in dichloromethane has been investigated. BBEE was used as a specific ion carrier for the transport of silver(I) ion. The influence of experimental parameters affecting the transport efficiency of silver(I) ion have been studied. In the presence of thiosulfate as a suitable metal ion acceptor in th...

  17. Antibacterial activity of the human host defence peptide LL-37 and selected synthetic cationic lipids against bacteria associated with oral and upper respiratory tract infections.

    Science.gov (United States)

    Leszczynska, Katarzyna; Namiot, Dorota; Byfield, Fitzroy J; Cruz, Katrina; Zendzian-Piotrowska, Malgorzata; Fein, David E; Savage, Paul B; Diamond, Scott; McCulloch, Christopher A; Janmey, Paul A; Bucki, Robert

    2013-03-01

    We aim to develop antibacterial peptide mimics resistant to protease degradation, with broad-spectrum activity at sites of infection. The bactericidal activities of LL-37, ceragenins CSA-13, CSA-90 and CSA-92 and the spermine-conjugated dexamethasone derivative D2S were evaluated using MIC and MBC measurements. Gingival fibroblast counting, interleukin-8 (IL-8) and lactate dehydrogenase (LDH) release from keratinocytes (HaCat) were used to determine effects on cell growth, pro-inflammatory response and toxicity. All tested cationic lipids showed stronger bactericidal activity than LL-37. Incubation of Staphylococcus aureus with half the MIC of LL-37 led to the appearance of bacteria resistant to its bactericidal effects, but identical incubations with CSA-13 or D2S did not produce resistant bacteria. Cathelicidin LL-37 significantly increased the total number of gingival fibroblasts, but ceragenins and D2S did not alter gingival fibroblast growth. Cationic lipids showed no toxicity to HaCat cells at concentrations resulting in bacterial killing. These data suggest that cationic lipids such as ceragenins warrant further testing as potential novel antibacterial agents.

  18. Selective Internal Radiation Therapy With Yttrium-90 Glass Microspheres: Biases and Uncertainties in Absorbed Dose Calculations Between Clinical Dosimetry Models.

    Science.gov (United States)

    Mikell, Justin K; Mahvash, Armeen; Siman, Wendy; Baladandayuthapani, Veera; Mourtada, Firas; Kappadath, S Cheenu

    2016-11-15

    To quantify differences that exist between dosimetry models used for 90 Y selective internal radiation therapy (SIRT). Retrospectively, 37 tumors were delineated on 19 post-therapy quantitative 90 Y single photon emission computed tomography/computed tomography scans. Using matched volumes of interest (VOIs), absorbed doses were reported using 3 dosimetry models: glass microsphere package insert standard model (SM), partition model (PM), and Monte Carlo (MC). Univariate linear regressions were performed to predict mean MC from SM and PM. Analysis was performed for 2 subsets: cases with a single tumor delineated (best case for PM), and cases with multiple tumors delineated (typical clinical scenario). Variability in PM from the ad hoc placement of a single spherical VOI to estimate the entire normal liver activity concentration for tumor (T) to nontumoral liver (NL) ratios (TNR) was investigated. We interpreted the slope of the resulting regression as bias and the 95% prediction interval (95%PI) as uncertainty. MC NL single represents MC absorbed doses to the NL for the single tumor patient subset; other combinations of calculations follow a similar naming convention. SM was unable to predict MC T single or MC T multiple (p>.12, 95%PI >±177 Gy). However, SM single was able to predict (p<.012) MC NL single , albeit with large uncertainties; SM single and SM multiple yielded biases of 0.62 and 0.71, and 95%PI of ±40 and ± 32 Gy, respectively. PM T single and PM T multiple predicted (p<2E-6) MC T single and MC T multiple with biases of 0.52 and 0.54, and 95%PI of ±38 and ± 111 Gy, respectively. The TNR variability in PM T single increased the 95%PI for predicting MC T single (bias = 0.46 and 95%PI = ±103 Gy). The TNR variability in PM T multiple modified the bias when predicting MC T multiple (bias = 0.32 and 95%PI = ±110 Gy). The SM is unable to predict mean MC tumor absorbed dose. The PM is statistically correlated with mean MC, but the

  19. Nepheline Formation Potential in Sludge Batch 4 (SB4) and Its Impact on Durability: Selecting Glasses for a Phase 2 Study

    International Nuclear Information System (INIS)

    Peeler, D

    2005-01-01

    frits whose operating windows (i.e., waste loading intervals that meet Product Composition Control System (PCCS) Measurement Acceptability Region (MAR) criteria) are robust to and/or selectively optimal for these sludge options. The primary or key frits that appear attractive on paper (i.e., down selected via the paper study) will be transferred into SRNL's experimental studies supporting SB4; specifically, the melt-rate studies, chemical process cell flowsheet runs and, if needed, a glass variability study

  20. Effect of the nature of alkali and alkaline-earth oxides on the structure and crystallization of an alumino-borosilicate glass developed to immobilize highly concentrated nuclear waste solutions

    Energy Technology Data Exchange (ETDEWEB)

    Quintas, A.; Caurant, D.; Majerus, O. [Laboratoire de Chimie de la Matiere Condensee de Paris (UMR 7574), Ecole Nationale Superieure de Chimie de Paris - ENSCP, ParisTech, Paris, 75005 (France); Charpentier, T. [CEA Saclay, Laboratoire de Structure et Dynamique par Resonance Magnetique, DSM/DRECAM/SCM - CEA CNRS URA 331, Gif-sur-Yvette, 91191 (France); Dussossoy, J.L. [Laboratoire d' Etude de Base sur les Verres, CEA Valrho, DEN/DTCD/SCDV/LEBV, Bagnols-sur-Ceze, 30207 (France)

    2008-07-01

    A complex rare-earth rich alumino-borosilicate glass has been proved to be a good candidate for the immobilization of new high level radioactive wastes. A simplified seven-oxides composition of this glass was selected for this study. In this system, sodium and calcium cations were supposed in other works to simulate respectively all the other alkali (R{sup +} = Li{sup +}, Rb{sup +}, Cs{sup +}) and alkaline-earth (R{sup 2+} = Sr{sup 2+}, Ba{sup 2+}) cations present in the complex glass composition. Moreover, neodymium or lanthanum are used here to simulate all the rare-earths and actinides occurring in waste solutions. In order to study the impact of the nature of R{sup +} and R{sup 2+} cations on both glass structure and melt crystallization tendency during cooling, two glass series were prepared by replacing either Na{sup +} or Ca{sup 2+} cations in the simplified glass by respectively (Li{sup +}, K{sup +}, Rb{sup +}, Cs{sup +}) or (Mg{sup 2+}, Sr{sup 2+}, Ba{sup 2+}) cations. From these substitutions, it was established that alkali ions are preferentially involved in the charge compensation of (AlO{sub 4}){sup -} entities in the glass network comparatively to alkaline-earth ions. The glass compositions containing calcium give way to the crystallization of an apatite silicate phase bearing calcium and rare-earth ions. The melt crystallization tendency during cooling strongly varies with the nature of the alkaline-earth. (authors)

  1. Low-Li2O Frits: Selecting Glasses that Support the Melt Rate Studies and Challenge the Current Durability Model

    International Nuclear Information System (INIS)

    Peeler, D. K.; Edwards, T. B.

    2005-01-01

    During the progressive development of the cold cap model (as it applies to a potential melt rate predictive tool), the formation of an Al-Li-silicate phase was identified as an intermediate reaction phase that could possibly hinder melt rate for SB4. To test this theory, six glasses were designed (using Frit 320's composition as the baseline) to maintain a constant 20 wt% sum of alkali content (in frit) by varying Na 2 O to Li 2 O ratios. The Li 2 O concentration ranged from 8 wt% down to 0% in either 2% or 1% increments with the differences being accounted for by an increase in Na 2 O concentration. Although the primary objective of the ''lower Li 2 O'' frits was to evaluate the potential for melt rate improvements, assessments of durability (as measured by the Product Consistency Test (PCT)) were also performed. The results suggest that durable glasses can be produced with these ''lower Li 2 O'' frits should it be necessary to pursue this option for improving melt rate. In addition to the series of glasses to support melt rate assessments, a series of frits were also developed to challenge the current durability model based on the limits proposed by Edwards et al. (2004). Although the ''new'' limits allow access into compositional regions of interest (i.e., higher alkali systems) which can improve melt rate and/or waste loading, there may still be ''additional'' conservatism. In this report, two series of glasses were developed to challenge the ''new'' durability limits for the SB4 system. In the first series, the total alkali of the Frit 320-based glasses (designed to support the melt rate program) was increased from 20 wt% to 21 wt% (in the frit), but the series also evaluated the possible impact of various Na 2 O and Li 2 O mass ratio differences. The second series pushed the alkali limit in the frit even further with frits containing either 22 or 24 wt% total alkali as well as various Na 2 O and Li 2 O mass ratios. The results of the PCT evaluation indicated

  2. Selective Transport of Silver(I) Cation Across a Bulk Liquid Membrane Containing Bis-β-enamino Ester as Ion Carrier

    OpenAIRE

    Tarahomi, Somayeh; Rounaghi, Gholam Hossein; Eshghi, Hossein; Daneshvar, Leili; Chamsaz, Mahmoud

    2017-01-01

    Facilitated transport of silver(I) cation across a bulk liquid membrane by two synthesized ligands, bis-β-enamino ester (BBEE) and bis(benzoic acid) trioxaheptane (BBAT), as carriers dissolved in dichloromethane has been investigated. BBEE was used as a specific ion carrier for the transport of silver(I) ion. The influence of experimental parameters affecting the transport efficiency of silver(I) ion have been studied. In the presence of thiosulfate as a suitable metal ion acceptor in the rec...

  3. Synthesis and characterisation of nitrogen poly-heterocyclic molecules using as selective complexing agents of metallic cations; Synthese et caracterisation de molecules polyheterocycliques azotees utilisables en tant que complexants selectifs de cations metalliques

    Energy Technology Data Exchange (ETDEWEB)

    Alphonse, F.A

    2003-12-15

    Separation of actinides (III) from lanthanides (III) is a crucial problem in the reprocessing of used nuclear fuels. Experimental results shown that soft donor extractants such as nitrogen polydentate heterocycles containing a NCCNCCN coordination site are potentials ligands for selective extraction of actinides (III). In those cases, two types of liquid-liquid extractions are employed: synergistic combination with lipophilic acid extractants and direct extraction. On the basis of the Hard and Soft Acids and Bases theory and basicity evaluation, new extractants were defined. We have first studied the synthesis of potential 1,3,5-triazine ligands designed for extraction in synergy with {alpha}-bromodecanoic acid. Secondly, we have examined the synthesis of bis-triazinyl-pyridine ligands for direct extraction studies. Extraction tests were carried out and perspectives of synthesis were deducted from those extraction results. (author)

  4. Isomerization of propargyl cation to cyclopropenyl cation ...

    Indian Academy of Sciences (India)

    step) for isomeri- zation of the linear propargyl cation to ..... C3, C4 and C5. The ZPE corrections in each case are derived from the. B3LYP calculations. ..... the converse of which gives the relative capacity of the. LPD's to stabilize TS6 with respect ...

  5. Properties Of Soda/Yttria/Silica Glasses

    Science.gov (United States)

    Angel, Paul W.; Hann, Raiford E.

    1994-01-01

    Experimental study of glass-formation compositional region of soda/ yttria/silicate system and of selected physical properties of glasses within compositional region part of continuing effort to identify glasses with high coefficients of thermal expansion and high softening temperatures, for use as coatings on superalloys and as glass-to-metal seals.

  6. Development of a ceramic membrane from a lithian spinel, Li1+xMyMn2-yO4 (M=trivalent or tetravalent cations) for a Li ion-selective electrode

    Science.gov (United States)

    Yoon, H.; Venugopal, N.; Rim, T.; Yang, B.; Chung, K.; Ko, T.

    2010-12-01

    Recently a few lithium containing ceramics are reported as promising cathodes for application in lithium batteries. Among them, a spinel-type lithium manganate (LM) exhibits an exceptionally high ion selectivity at room temperature. Thus, LM could have a great potential as an ion selective membrane material for screening interfering ions from lithium ion for the determination of lithium ion in salt solution. In this study, we developed an ion-selective electrode based on LM as a membrane material and investigated its lithium ion selectivity by varying the content of M in composition. A sol-gel process was successfully applied for preparing LM films without resorting to calcination at a high temperature. The LM thin film-type membranes exhibit a high selectivity for Li ion over other cations, a wide operation detection range of 10-5 ~ 10-2 M, and a fast response time less than 60 s. Furthermore, our result demonstrates a linear potentiometric response over a wide range of lithium concentration, which is compared to that of a lithium ion-selective electrode based on an ionophore. Acknowledgements: This research was supported by a grant from the Development of Technology for Extraction of Resources Dissolved in Sea Water Program funded by Ministry of Land Transport and Maritime Affairs in Korean Government (2010).

  7. Colloidal glasses

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Colloidal glasses. Glassy state is attained when system fails to reach equilibrium due to crowding of constituent particles. In molecular glasses, glassy state is reached by rapidly lowering the temperature. In colloidal glasses, glassy state is reached by increasing the ...

  8. Radioresistance of inorganic glasses

    International Nuclear Information System (INIS)

    Vorob'ev, A.A.; Zavadovskaya, E.K.; Fedorov, B.V.; Starodubtsev, V.A.

    1977-01-01

    Regularities are considered in the variation of properties of glass due to irradiations. On the basis of previous theoretical statements and experimental investigations, it is inferred that the irradiation resistance of glasses of the same type, synthesis conditions, content of impurities and amount of imperfections, is a function of the ''element-oxygen'' bond energy. The irradiation resistance depends on the number and the nature of glass structure imperfections. The averaged level of bonding forces is indicative of the glass formation temperature; the imperfections in glasses are formed in structure elements whose amount predominates as compared to the others. Electric charges which accumulate on the crack surface tend to increase its size, thus lessening even further the electric strength of the dielectric. The greater the irradiation time, the greater the number of irradiation imperfections causing a drop in the electric strength of glass. When choosing a glass for service in a radiation field, it is necessary to select those of a highest temperature of glass formation and with a least amount of imperfections

  9. Cobalt bis(dicarbollide) ions with covalently bonded CMPO groups as selective extraction agents for lanthanide and actinide cations from highly acidic nuclear waste solutions

    International Nuclear Information System (INIS)

    Gruner, B.; Plesek, J.; Baca, J.; Cisarova, I.; Dozol, J.F.; Rouquette, H.; Vinas, C.; Selucky, P.; Rais, J.

    2002-01-01

    A new series of boron substituted cobalt bis(dicarbollide)(1-) ion (1) derivatives of the general formula [(8-CMPO-(CH 2 -CH 2 O) 2 -1,2-C 2 B 9 H 10 )(1',2'-C 2 B 9 H 11 )-3,3'-Co] - (CMPO = Ph 2 P(O)-CH 2 C(O)NR, R = C 4 H 9 (3b), -C 12 H 25 (4b), -CH 2 -C 6 H 5 (5b)) was prepared by ring cleavage of the 8-dioxane-cobalt bis(dicarbollide) (2) bi-polar compound by the respective primary amines and by subsequent reaction of the resulting amino derivatives (3a-5a) with the nitrophenyl ester of diphenyl-phosphoryl-acetic acid. The compounds were synthesized with the aim to develop a new class of more efficient extraction agents for liquid/liquid extraction of polyvalent cations, i.e. lanthanides and actinides, from high-level activity nuclear waste. All compounds were characterized by a combination of 11 B NMR, 1 H high field NMR, Mass Spectrometry with Electro-spray and MALDI TOF ionisation, HPLC and other techniques. The molecular structure of the supramolecular Ln 3+ complex of the anion 5b was determined by single crystal X-ray diffraction analysis. Crystallographic results proved that the Ln(m) atom is bonded to three functionalized cobalt bis(dicarbollide) anions in a charge compensated complex. The cation is tightly coordinated by six oxygen atoms of the CMPO terminal groups (two of each ligand) and by three water molecules completing the metal coordination number to 9. Atoms occupying the primary coordination sphere form a tri-capped trigonal prismatic arrangement. Very high liquid-liquid extraction efficiency of all anionic species was observed. Moreover, less polar toluene can be applied as an auxiliary solvent replacing the less environmentally friendly nitro- and chlorinated solvents used in the current dicarbollide liquid-liquid extraction process. The extraction coefficients are sufficiently high for possible technological applications. (authors)

  10. Boosted selective internal radiation therapy with 90Y-loaded glass microspheres (B-SIRT) for hepatocellular carcinoma patients: a new personalized promising concept

    International Nuclear Information System (INIS)

    Garin, E.; Lenoir, L.; Edeline, J.; Laffont, S.; Mesbah, H.; Poree, P.; Sulpice, L.; Boudjema, K.; Mesbah, M.; Guillygomarc'h, A.; Quehen, E.; Pracht, M.; Raoul, J.L.; Clement, B.; Rolland, Y.; Boucher, E.

    2013-01-01

    To evaluate the impact of dosimetry based on MAA SPECT/CT for the prediction of response, toxicity and survival, and for treatment planning in patients with hepatocellular carcinoma (HCC) treated with 90 Y-loaded glass microspheres (TheraSphere registered). TheraSphere registered was administered to 71 patients with inoperable HCC. MAA SPECT/CT quantitative analysis was used for the calculation of the tumour dose (TD), healthy injected liver dose (HILD), and total injected liver dose. Response was evaluated at 3 months using EASL criteria. Time to progression (TTP) and overall survival (OS) were evaluated using the Kaplan-Meier method. Factors potentially associated with liver toxicity were combined to construct a liver toxicity score (LTS). The response rate was 78.8 %. Median TD were 342 Gy for responding lesions and 191 Gy for nonresponding lesions (p 205 Gy (p = 0.0015 and not significant). Among patients with portal vein thrombosis (PVT) (n = 33), the median TTP and OS were 4.5 months (2-7 months) and 5 months (2-8 months), respectively, in patients with TD 205 Gy (p = 0.039 and 0.005). The median OS was 24.5 months (18-28.5 months) in PVT patients with TD >205 Gy and good PVT targeting on MAA SPECT/CT. The LTS was able to detect severe liver toxicity (n = 6) with a sensitivity of 83 % and overall accuracy of 97 %. Dosimetry based on MAA SPECT/CT was able to accurately predict response and survival in patients treated with glass microspheres. This method can be used to adapt the injected activity without increasing liver toxicity, thus defining a new concept of boosted selective internal radiation therapy (B-SIRT). This new concept and LTS enable fully personalized treatment planning with glass microspheres to be achieved. (orig.)

  11. Boosted selective internal radiation therapy with 90Y-loaded glass microspheres (B-SIRT) for hepatocellular carcinoma patients: a new personalized promising concept.

    Science.gov (United States)

    Garin, E; Lenoir, L; Edeline, J; Laffont, S; Mesbah, H; Porée, P; Sulpice, L; Boudjema, K; Mesbah, M; Guillygomarc'h, A; Quehen, E; Pracht, M; Raoul, J L; Clement, B; Rolland, Y; Boucher, E

    2013-07-01

    To evaluate the impact of dosimetry based on MAA SPECT/CT for the prediction of response, toxicity and survival, and for treatment planning in patients with hepatocellular carcinoma (HCC) treated with (90)Y-loaded glass microspheres (TheraSphere®). TheraSphere® was administered to 71 patients with inoperable HCC. MAA SPECT/CT quantitative analysis was used for the calculation of the tumour dose (TD), healthy injected liver dose (HILD), and total injected liver dose. Response was evaluated at 3 months using EASL criteria. Time to progression (TTP) and overall survival (OS) were evaluated using the Kaplan-Meier method. Factors potentially associated with liver toxicity were combined to construct a liver toxicity score (LTS). The response rate was 78.8%. Median TD were 342 Gy for responding lesions and 191 Gy for nonresponding lesions (p 205 Gy (p = 0.0015 and not significant). Among patients with portal vein thrombosis (PVT) (n = 33), the median TTP and OS were 4.5 months (2-7 months) and 5 months (2-8 months), respectively, in patients with TD 205 Gy (p = 0.039 and 0.005). The median OS was 24.5 months (18-28.5 months) in PVT patients with TD >205 Gy and good PVT targeting on MAA SPECT/CT. The LTS was able to detect severe liver toxicity (n = 6) with a sensitivity of 83% and overall accuracy of 97%. Dosimetry based on MAA SPECT/CT was able to accurately predict response and survival in patients treated with glass microspheres. This method can be used to adapt the injected activity without increasing liver toxicity, thus defining a new concept of boosted selective internal radiation therapy (B-SIRT). This new concept and LTS enable fully personalized treatment planning with glass microspheres to be achieved.

  12. Silicate glasses

    International Nuclear Information System (INIS)

    Lutze, W.

    1988-01-01

    Vitrification of liquid high-level radioactive wastes has received the greatest attention, world-wide, compared to any other HLW solidification process. The waste form is a borosilicate-based glass. The production of phosphate-based glass has been abandoned in the western world. Only in the Soviet Union are phosphate-based glasses still being developed. Vitrification techniques, equipment and processes and their remote operation have been developed and studied for almost thirty years and have reached a high degree of technical maturity. Industrial demonstration of the vitrification process has been in progress since 1978. This chapter is a survey of world-wide research and development efforts in nuclear waste glasses and its production technology. The principal glasses considered are silicate glasses which contain boron, i.e., borosilicate glasses

  13. Cation Exchange Water Softeners

    Science.gov (United States)

    WaterSense released a notice of intent to develop a specification for cation exchange water softeners. The program has made the decision not to move forward with a spec at this time, but is making this information available.

  14. Glass Durability Modeling, Activated Complex Theory (ACT)

    International Nuclear Information System (INIS)

    CAROL, JANTZEN

    2005-01-01

    atomic ratios is shown to represent the structural effects of the glass on the dissolution and the formation of activated complexes in the glass leached layer. This provides two different methods by which a linear glass durability model can be formulated. One based on the quasi- crystalline mineral species in a glass and one based on cation ratios in the glass: both are related to the activated complexes on the surface by the law of mass action. The former would allow a new Thermodynamic Hydration Energy Model to be developed based on the hydration of the quasi-crystalline mineral species if all the pertinent thermodynamic data were available. Since the pertinent thermodynamic data is not available, the quasi-crystalline mineral species and the activated complexes can be related to cation ratios in the glass by the law of mass action. The cation ratio model can, thus, be used by waste form producers to formulate durable glasses based on fundamental structural and activated complex theories. Moreover, glass durability model based on atomic ratios simplifies HLW glass process control in that the measured ratios of only a few waste components and glass formers can be used to predict complex HLW glass performance with a high degree of accuracy, e.g. an R 2 approximately 0.97

  15. Cation exchange applications of synthetic tobermorite for the ...

    Indian Academy of Sciences (India)

    Immobilization and solidification of hazardous cations like Cs137 and Sr90 are required while handling the radioactive waste of nuclear power plants. Efforts are on to find a fail proof method of safe disposal of nuclear wastes. In this context, various materials like borosilicate glass, zeolites, cements and synthetic rocks have ...

  16. Glass Membrane For Controlled Diffusion Of Gases

    Science.gov (United States)

    Shelby, James E.; Kenyon, Brian E.

    2001-05-15

    A glass structure for controlled permeability of gases includes a glass vessel. The glass vessel has walls and a hollow center for receiving a gas. The glass vessel contains a metal oxide dopant formed with at least one metal selected from the group consisting of transition metals and rare earth metals for controlling diffusion of the gas through the walls of the glass vessel. The vessel releases the gas through its walls upon exposure to a radiation source.

  17. Cation-cation interaction in neptunyl(V) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Krot, N.N. [Russian Academy of Sciences, Institute of Physical Chemistry (Russian Federation); Saeki, Masakatsu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    The original manuscript was prepared by Professor N.N. Krot of Institute of Physical Chemistry, Russian Academy of Sciences, in 1997. Saeki tried to translate that into Japanese and to add some new data since 1997. The contents include the whole picture of cation-cation interactions mainly in 5-valence neptunium compounds. Firstly, characteristic structures of neptunium are summarized of the cation-cation bonding in compounds. Secondly, it is mentioned how the cation-cation bonding affects physical and chemical properties of the compounds. Then, characterization-methods for the cation-cation bonding in the compounds are discussed. Finally, the cation-cation interactions in compounds of other actinide-ions are shortly reviewed. (author)

  18. Effects of adding barium-borosilicate glass to a simplified etch-and-rinse adhesive on radiopacity and selected properties.

    Science.gov (United States)

    Martins, Gislaine Cristine; Meier, Marcia Margarete; Loguercio, Alessandro Dourado; Reis, Alessandra; Gomes, João Carlos; Gomes, Osnara Maria

    2014-04-01

    To evaluate the radiopacity, ultimate tensile strength (UTS), microhardness (KHN), degree of conversion (DC), water sorption (WS) and solubility (SL) of experimental adhesives. Five experimental adhesives with different concentrations of barium-borosilicate oxide microfillers [0% (R0), 30% (R30), 40% (R40), 50% (R50), 60% (R60)] were formulated based on the adhesive system Ambar (FGM). The adhesive Adper Single Bond 2 (SB, 3M ESPE) was used as commercial reference. For the radiopacity (n = 5), KHN (n = 5), WS (n = 10), and SL (n = 10) tests, adhesive disks were constructed (5.0 mm in diameter and 1.0 mm thick), while for UTS (n = 5), hourglass-shaped specimens with a cross-sectional area of 0.8 mm2 were used. The FTIR spectra of unpolymerized and polymerized adhesives were used to determine the DC. Data were submitted to a one-way ANOVA and Tukey's test (α = 0.05). All experimental adhesives showed radiopacity similar to enamel, except those of R0 and SB. Filler addition did not jeopardize the UTS, KHN, or WS of the filled adhesives in comparison with the unfilled version. Except for R40, filler addition reduced the SL. The filled adhesives showed lower DC when compared with R0, but the DC was similar or higher when compared with SB. The addition of barium-borosilicate glass up to 50% did not jeopardize the mechanical properties of the adhesive layer and seems to reduce its solubility.

  19. Ion selectivity of the cation transport system of isolated intact cattle rod outer segments: evidence for a direct communication between the rod plasma membrane and the rod disk membranes.

    Science.gov (United States)

    Schnetkamp, P P

    1980-05-08

    The ion selectivity of cation transport through the plasma membrane of isolated intact cattle rod outer segments (rods) is investigated by means of 45Ca-exchange experiments and light-scattering experiments. These techniques appear to provide complementary information: the 45Ca experiments (45Ca fluxes in rods) describe electroneutral antiport, whereas the light-scattering experiments (shrinkage and swelling of rods upon hypertonic shocks with various electrolytes) reveal electrogenic uniport. Electroneutral symport of ions (salt transport) does not take place without addition of external ionophores and application of salts of weak acids. 1. Intact rods recover from a hypertonic shock in the presence of FCCP when lithium, sodium and potassium acetate are applied, but not when ammonium chloride, calcium and magnesium acetate are used. This indicates that the plasma membrane of isolated intact cattle rods is relatively permeable to net transport of Na+, Li+ and K+, and relatively impermeable to net transport of Cl-, Mg2+ and Ca2+ under conditions that do not give rise to diffusion potentials. 2. Rapid (t1/2 exchange diffusion of internal 45Ca with external Na+, Ca2+, Sr2+ and Ba2+, respectively. 3. All tested cations lower the rate of 45Ca uptake. The latter can be described by a single rate constant indicating a homogeneous rod preparation and a homogeneous endogenous Ca2+ pool. However, only those cations which stimulate 45Ca efflux from preloaded rods lower the final equilibrium of 45Ca uptake. Except for the effects of K+, Rb+ and Cs+ the reduction of the rate of 45Ca uptake by external cations appears to arise from competition for a common site on the plasms membrane. The observed affinities for this site do not correlate with actual transport (as indicated by the ability to stimulate 45Ca efflux). 4. K+ increases the affinity of the exchange diffusion system to Ca2+ from 1 microM to 0.15 microM and changes the relative affinities with respect to Ca2+ for the

  20. Mixed mobile ion effect in fluorozincate glasses

    International Nuclear Information System (INIS)

    Ghosh, S; Ghosh, A

    2005-01-01

    The mixed mobile ion effect has been investigated for the first time in zinc fluoride glasses where in addition to alkali cations fluorine anions also participate in the diffusion process, unlike mixed alkali oxide glasses. The minimum in the conductivity, conductivity relaxation frequency, crossover frequency and decoupling index indicates the existence of the mixed mobile ion effect in these fluoride glasses. It has been observed that the non-exponential parameter and the frequency exponent are independent of temperature. It has been established that alkali ions and fluorine anions exhibit lower dimensionality of the conduction pathways in mixed alkali zinc fluoride glasses than that in the single alkali lithium based zinc fluoride glasses while they are migrating. From the scaling of the conductivity spectra, it has been established that the relaxation dynamics in mixed alkali zinc fluoride glasses is independent of temperature and composition

  1. Recycle Glass in Foam Glass Production

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

    The foam glass industry turn recycle glass into heat insulating building materials. The foaming process is relative insensitive to impurities in the recycle glass. It is therefore considered to play an important role in future glass recycling. We show and discuss trends of use of recycled glasses...... in foam glass industry and the supply sources and capacity of recycle glass....

  2. Cosmos & Glass

    DEFF Research Database (Denmark)

    Beim, Anne

    1996-01-01

    The article unfolds the architectural visions of glass by Bruno Taut. It refers to inspirations by Paul Sheerbart and litterature and the Crystal Chain, also it analyses the tectonic univers that can be found in the glass pavillion for the Werkbund exposition in Cologne.......The article unfolds the architectural visions of glass by Bruno Taut. It refers to inspirations by Paul Sheerbart and litterature and the Crystal Chain, also it analyses the tectonic univers that can be found in the glass pavillion for the Werkbund exposition in Cologne....

  3. Selective hydroboration of catalyzed olephynes by new cationic complex of Rh(I) heterogeniated over zeolites; Hidroboracion selective de olefinas catalizada por nuevos complejos cationicos de Rh(I) heterogeneizador sobre zeolitas

    Energy Technology Data Exchange (ETDEWEB)

    Corma, A.; Dios, M.I.; Iglesias, M.; Sanchez, F. [Instituto de Quimica Organica, CSIC, Madrid (Spain)

    1995-12-01

    The synthesis and characterization of new cationic Rh(I) complexes with NN-ligands (1a,1b) and NP-ligands (2a-2b) are reported. The complexes bearing the triethoxysilil group were covalently bonded to a modified USY zeolite to give heterogeniated catalysts. The reaction of 1-decene, cyclohexene and styrene with catechol borane in presence of 1% mol of new prepared homogeneous and heterogenized Rh catalysts proceed regiselectively to give, after oxidation, 1-decanol, cyclohexanol and 1-phenylethanol respectively in excellent yields, whilts the more bulky 1-methylstyrene did not react at the same operations conditions. 11 refs.

  4. Super ionic conductive glass

    Science.gov (United States)

    Susman, S.; Volin, K.J.

    Described is an ionically conducting glass for use as a solid electrolyte in a power or secondary cell containing an alkali metal-containing anode and a cathode separated by an alkali metal ion conducting glass having an ionic transference number of unity and the general formula: A/sub 1 + x/D/sub 2-x/3/Si/sub x/P/sub 3 - x/O/sub 12 - 2x/3/, wherein A is a network modifier for the glass and is an alkali metal of the anode, D is an intermediate for the glass and is selected from the class consisting of Zr, Ti, Ge, Al, Sb, Be, and Zn and X is in the range of from 2.25 to 3.0. Of the alkali metals, Na and Li are preferred and of the intermediate, Zr, Ti and Ge are preferred.

  5. Glass Glimpsed

    DEFF Research Database (Denmark)

    Lock, Charles

    2015-01-01

    Glass in poetry as it reflects the viewer and as its power of reflection are both reduced and enhanced by technology.......Glass in poetry as it reflects the viewer and as its power of reflection are both reduced and enhanced by technology....

  6. Boosted selective internal radiation therapy with {sup 90}Y-loaded glass microspheres (B-SIRT) for hepatocellular carcinoma patients: a new personalized promising concept

    Energy Technology Data Exchange (ETDEWEB)

    Garin, E.; Lenoir, L. [Comprehensive Cancer Center, Institute Eugene Marquis, Department of Nuclear Medicine, CS 44229, Rennes (France); University of Rennes 1, Rennes (France); INSERM, U-991, Liver Metabolisms and Cancer, Rennes (France); Edeline, J. [University of Rennes 1, Rennes (France); Comprehensive Cancer Center, Institute Eugene Marquis, Department of Medical Oncology, CS 44229, Rennes (France); Laffont, S. [Comprehensive Cancer Center, Institute Eugene Marquis, Department of Nuclear Medicine, CS 44229, Rennes (France); Mesbah, H.; Poree, P. [Comprehensive Cancer Center, Institute Eugene Marquis, Department of Medical Informatics, CS 44229, Rennes (France); Sulpice, L. [INSERM, U-991, Liver Metabolisms and Cancer, Rennes (France); Centre Hospitalier Universitaire Pontchaillou, Department of Digestive Surgery, Rennes (France); Boudjema, K. [University of Rennes 1, Rennes (France); INSERM, U-991, Liver Metabolisms and Cancer, Rennes (France); Centre Hospitalier Universitaire Pontchaillou, Department of Digestive Surgery, Rennes (France); Mesbah, M. [University of Pierre et Marie Curie, Paris (France); Guillygomarc' h, A. [Centre Hospitalier Universitaire Pontchaillou, Department of Hepatology, Rennes (France); Quehen, E. [Centre Hospitalier Universitaire Pontchaillou, Department of Radiology, Rennes (France); Pracht, M. [Comprehensive Cancer Center, Institute Eugene Marquis, Department of Medical Oncology, CS 44229, Rennes (France); Raoul, J.L. [Comprehensive Cancer Center, Institute Paoli Calmette, Department of Medical Oncology, Marseille (France); Clement, B. [INSERM, U-991, Liver Metabolisms and Cancer, Rennes (France); Rolland, Y. [Comprehensive Cancer Center, Institute Eugene Marquis, Department of Medical Imaging, CS 44229, Rennes (France); Boucher, E. [INSERM, U-991, Liver Metabolisms and Cancer, Rennes (France); Comprehensive Cancer Center, Institute Eugene Marquis, Department of Medical Oncology, CS 44229, Rennes (France)

    2013-07-15

    able to accurately predict response and survival in patients treated with glass microspheres. This method can be used to adapt the injected activity without increasing liver toxicity, thus defining a new concept of boosted selective internal radiation therapy (B-SIRT). This new concept and LTS enable fully personalized treatment planning with glass microspheres to be achieved. (orig.)

  7. Spin glasses

    CERN Document Server

    Bovier, Anton

    2007-01-01

    Spin glass theory is going through a stunning period of progress while finding exciting new applications in areas beyond theoretical physics, in particular in combinatorics and computer science. This collection of state-of-the-art review papers written by leading experts in the field covers the topic from a wide variety of angles. The topics covered are mean field spin glasses, including a pedagogical account of Talagrand's proof of the Parisi solution, short range spin glasses, emphasizing the open problem of the relevance of the mean-field theory for lattice models, and the dynamics of spin glasses, in particular the problem of ageing in mean field models. The book will serve as a concise introduction to the state of the art of spin glass theory, usefull to both graduate students and young researchers, as well as to anyone curious to know what is going on in this exciting area of mathematical physics.

  8. Surface degradation behaviour of sodium borophosphate glass in ...

    Indian Academy of Sciences (India)

    Administrator

    corrosion mechanism were different in acid and alkali media. Keywords. Borophosphate glass; surface degradation; aqueous media. 1. Introduction. Phosphate glasses and glass–ceramics are useful for appli- cations such as bone transplantation, glass–to–metal seals, containment of radioactive wastes, fast ion conduc-.

  9. Single glass nanopore-based regenerable sensing platforms with a non-immobilized polyglutamic acid probe for selective detection of cupric ions.

    Science.gov (United States)

    Chen, Lizhen; He, Haili; Xu, Xiaolong; Jin, Yongdong

    2015-08-19

    A single glass capillary nanopore-based sensing platform for rapid and selective detection of cupric ions is demonstrated by utilizing polyglutamic acid (PGA) as a non-immobilized probe. The detection is based on the significant decrease of ionic current through nanopore and the reversal of ion current rectification responses induced by the chelated cupric ions on the probes when in the presence of cupric ions. PGA shows high selectivity for detecting cupric ions rather than other metal ions. The sensitivity of the sensing platform can be improved about 1-2 orders of magnitude by employing asymmetric salt gradients during the measurements. And the PGA-based nanopore sensing platform shows excellent regenerability for Cu(2+) sensing applications. In addition, the method is found effective and reliable for the detection of cupric ions in real samples with small volume down to 20 μL. This nanopore-based sensing platform will find promising practical applications for the detection of cupric ions. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Diffusion of radionuclides in glasses simulating radioactive wastes

    International Nuclear Information System (INIS)

    Ivanov, I.A.; Sedov, V.M.; Gulin, A.N.; Stefanovskij, S.V.; Shatkov, V.M.

    1991-01-01

    By the method of integral residual activity diffusion coefficients of 22 Na, 90 Sr, 137 Cs, 237 Np, 239 Pu, 241 Am radionuclides in two model glasses of each of the classes mentioned were determined. Sodium cations proved the most mobile ones in the glasses. Strontium and cesium diffusion coefficients are 4-5 orders of value lower than those of sodium. Actinides are the least mobile in the glasses. Variation of composition of both alumoborosilicate and alumophosphate glasses affects but slightly the value of the radionuclide diffusion coefficients. Data shown that diffusion coefficients of the radionuclides in alumophosphate glasses at 673 K are higher than in alumoborosilicate ones at 773 K

  11. Structure peculiarities of mixed alkali silicate glasses

    International Nuclear Information System (INIS)

    Bershtein, V.A.; Gorbachev, V.V.; Egorov, V.

    1980-01-01

    The thermal porperties and structure of alkali and mixed alkali (Li, Na, K) silicate glasses by means of differential scanning calorimetry (DSC), the positron annihilation method, X-ray fluorescence and infrared (300-30 cm -1 ) spectroscopy were studied. Introduction of different alkali cations in glass results in nonadditive change in their electron structure (bond covalence degree growth) and the thermal behaviour. The different manifestations of mixed alkali effect can be explained by the lessening of long distance Coulomb interactions and strengthening the short-range forces in the mixed alkali glasses. (orig.)

  12. Tailored cationic palladium(II) compounds as catalysts for highly selective dimerization and polymerization of vinylic monomers: Synthetic and mechanistic aspects

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Z.; Sen, A. (Pennsylvania State Univ., University Park (United States))

    1993-04-01

    The electrophilic palladium(II)compounds Pd(2,6-di-tert-butylpyridine)[sub 2](CH[sub 3]NO[sub 2])[sub 2](BF[sub 4])[sub 2] (1), Pd(PPh[sub 3])[sub 2](BF[sub 4])[sub 2] (2), and Pd(Ph[sub 2]PCH[sub 2]CH[sub 2]PPh[sub 2])(BF[sub 4])[sub 2] (3) were found to be highly selective catalysts for the acyclic dimerization of vinyl monomers (styrene, ethylene, and propylene) and the linear polymerization of p-divinylbenzene, the reactions proceeding through a carbocationic mechanism. One manifestation of the high selectivity was the ability to catalyze the dimerization of ethylene in the presence of propylene and styrene in the presence of [alpha]-methylstyrene even though the second member of each pair was normally significantly more reactive in reactions involving carbocationic intermediates. The linear polymerization of p-divinylbenzene involved in step-growth mechanism. The synthesis of a telechelic polymer through cross-coupling between the terminal vinyl groups of linear poly(p-divinylbenzene) and the vinyl group of a functionalized styrene derivative was also achieved. The reaction rates for the linear dimerization of styrene and the linear polymerization of p-divinylbenzene were found to be first order in the monomer concentration and fractional order in the catalyst concentration. Mathematical modeling indicated that the fractional order in the catalyst concentration was due to preequilibria involving anion dissociation from the metal center, and actually, the catalytic species in the case of 2 was found to be the dication, Pd(PPh[sub 3])[sub 2][sup 2+]. 17 refs., 6 figs., 4 tabs.

  13. Modifier constraints in alkali ultraphosphate glasses

    DEFF Research Database (Denmark)

    Rodrigues, B.P.; Mauro, J.C.; Yue, Yuanzheng

    2014-01-01

    In applying the recently introduced concept of cationic constraint strength [J. Chem. Phys. 140, 214501 (2014)] to bond constraint theory (BCT) of binary phosphate glasses in the ultraphosphate region of xR2O-(1-x)P2O5 (with x ≤ 0.5 and R = {Li, Na, Cs}), we demonstrate that a fundamental limitat...

  14. Influence of alternative cations distribution in AgxLi96-x-LSX on dehydration kinetics and its selective adsorption performance for N2 and O2

    Science.gov (United States)

    Panezai, Hamida; Sun, Jihong; Jin, Xiaoqi

    2016-12-01

    Adsorption characteristics of pure gases N2 and O2 on various silver exchanged low silica X-type (AgxLi96-x-LSX) zeolites were investigated. The equilibrium adsorption isotherms of N2 and O2 were measured at 273 and 298 K. Textual and structural properties of parent and resultant AgxLi96-x-LSX were characterized by XRD, BET surface area, and SEM techniques. Kinetics of their thermal dehydration were studied by exploiting thermogravimetric and differential data (TG-DTG) obtained at three heating rates (5, 10 and 15 K) using two model-free (Kissinger and Flynn-Wall-Ozawa) and one model fitting (Coats-Redfern) methods. Forty one mechanism functions were used to evaluate kinetic triplet (activation energy, frequency factor, and most probable mechanism/model) for different stages of dehydration. Results revealed that the impact of very small content of silver on the adsorption of N2 is pronounced and attributed to weak chemical bonds formed between N2 and Ag+ clusters due to strong adsorption of N2 at low pressure, whereas O2 adsorption is affected to a negligible extent. In addition, the N2/O2 adsorption selectivity shows unexpected low values for Ag87.08Li7.94Na0.98-LSX with higher Ag+ content (91.00 %), which might be due to low crystalline water content as well as Ag+ clusters located at SIII sites. N2 adsorption strongly depends on temperature as higher adsorption occurs at low temperature 273 K as compared to 298 K.

  15. New Horizons in Cationic Photopolymerization

    Directory of Open Access Journals (Sweden)

    Marco Sangermano

    2018-01-01

    Full Text Available In this review, we report some recent advances and new horizons in UV-induced cationic photopolymerization. In particular, after a brief introduction on the discovery and affirmation of the cationic photopolymerization process, new efforts in the synthesis of cationic photoinitiators are reported. Subsequently, an interesting and absolutely new application is reported, related to the combination of Radical-Induced Cationic Photopolymerization with Frontal Polymerization, achieving the cross-linking of epoxy composites.

  16. Comparison of Choi criteria and Response Evaluation Criteria in Solid Tumors (RECIST) for intrahepatic cholangiocarcinoma treated with glass-microspheres Yttrium-90 selective internal radiation therapy (SIRT).

    Science.gov (United States)

    Beuzit, Luc; Edeline, Julien; Brun, Vanessa; Ronot, Maxime; Guillygomarc'h, Anne; Boudjema, Karim; Gandon, Yves; Garin, Etienne; Rolland, Yan

    2016-08-01

    To compare Choi criteria with Response Evaluation Criteria in Solid Tumors (RECIST) for the prediction of overall survival (OS) in patients treated with glass-microspheres, Yttrium-90 selective internal radiation therapy (SIRT) for intrahepatic cholangiocarcinoma (ICC). Between 2010 and 2014, 45 adult patients with locally advanced ICC treated with SIRT were retrospectively analyzed. Computed tomography scans performed before and after treatment were analyzed using both RECIST 1.1 and Choi criteria. Response was correlated with survival. Patients who achieved an objective response according to Choi had a longer OS than non-responders (median OS 19.9 months [95% CI, 1.1-38.7 months] vs. 7.5 months if stable disease [uncountable CI] and 3 months if progressive disease [95% CI, 0-6.2 months], log-rank test: p=0.003) whereas there was no significant survival difference according to the RECIST response (p=0.339). Among the 39 RECIST non-responding patients, those identified as responders by Choi (n=31) had significantly better OS than Choi non-responders (median OS 19.9 months (95% CI, 5.1-34.7 months) and 5.4 months (95% CI, 0-11.6 months), p=0.005). Choi criteria appear more appropriate than RECIST to identify responders with long survival among patients who received SIRT for ICC. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. Selective laser melting of an Al86Ni6Y4.5Co2La1.5 metallic glass: Processing, microstructure evolution and mechanical properties

    International Nuclear Information System (INIS)

    Li, X.P.; Kang, C.W.; Huang, H.; Zhang, L.C.; Sercombe, T.B.

    2014-01-01

    In this study, single line scans at different laser powers were carried out using selective laser meting (SLM) equipment on a pre-fabricated porous Al 86 Ni 6 Y 4.5 Co 2 La 1.5 metallic glass (MG) preform. The densification, microstructural evolution, phase transformation and mechanical properties of the scan tracks were systematically investigated. It was found that the morphology of the scan track was influenced by the energy distribution of the laser beam and the heat transfer competition between convection and conduction in the melt pool. Due to the Gaussian distribution of laser energy and heat transfer process, different regions of the scan track experienced different thermal histories, resulting in a gradient microstructure and mechanical properties. Higher laser powers caused higher thermal stresses, which led to the formation of cracks; while low power reduced the strength of the laser track, also inducing cracking. The thermal fluctuation at high laser power produced an inhomogeneous chemical distribution which gave rise to severe crystallization of the MG, despite the high cooling rate. The crystallization occurred both within the heat affected zone (HAZ) and at the edge of melt pool. However, by choosing an appropriate laser power crack-free scan tracks could be produced with no crystallization. This work provides the necessary fundamental understanding that will lead to the fabrication of large-size, crack-free MG with high density, controllable microstructure and mechanical properties using SLM

  18. Fixation by ion exchange of toxic materials in a glass matrix

    International Nuclear Information System (INIS)

    Simmons, C.J.; Simmons, J.H.; Macedo, P.B.; Litovitz, T.A.

    1982-01-01

    A process is reported for reacting a porous silicate or borosilicate glass or silica gel with alkali metal cations, Group lb cations and/or ammonium cations bonded to the silicon through divalent oxygen linkages on the internal surfaces of the pores. Ion exchange of the cations with toxic or radioactive cations was possible resulting in a distribution of internal silicon-bonded toxic cation oxide groups within the pores of the glass or silica gel. The ion exchange reaction may be done successfully with acidic, neutral or alkaline pH solutions. The aim of the immobilization is for permanent storage of hazardous materials such as Hg 2+ , Hg + , Cd 2+ , Tl + , Pb 2+ and radioactive cations

  19. {sup 1}H and {sup 23}Na MAS NMR spectroscopy of cationic species in CO{sub 2} selective alkaline earth metal porous silicoaluminophosphates prepared via liquid and solid state ion exchange

    Energy Technology Data Exchange (ETDEWEB)

    Arevalo-Hidalgo, Ana G. [Department of Chemical Engineering, University of Puerto Rico-Mayagueez Campus, Mayagueez, PR 00681-9000 (Puerto Rico); Dugar, Sneha; Fu, Riqiang [National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310 (United States); Hernandez-Maldonado, Arturo J., E-mail: arturoj.hernandez@upr.edu [Department of Chemical Engineering, University of Puerto Rico-Mayagueez Campus, Mayagueez, PR 00681-9000 (Puerto Rico)

    2012-07-15

    The location of extraframework cations in Sr{sup 2+} and Ba{sup 2+} ion-exchanged SAPO-34 was estimated by means of {sup 1}H and {sup 23}Na MAS NMR spectroscopy and spectral deconvolution. Incorporation of the alkaline earth metal cations onto the SAPO framework was achieved via liquid state ion exchange, coupled partial detemplation/solid-state ion exchange, and combination of both techniques. MAS NMR revealed that the level of ion exchange was limited by the presence of protons and sodium cations near hexagonal prisms (site SI), which are relatively difficult to exchange with the alkaline earth metal due to steric and charge repulsion criteria. In addition, the presence of ammonium cations in the supercages facilitated the exchange of otherwise tenacious hydrogen as corroborated by unit cell compositional data as well as enhanced CO{sub 2} adsorption at low partial pressures. The extraframework ammonium species were produced from partial detemplation of the structure-directing agent employed for the SAPO-34 synthesis, tetraethylammonium. - Graphical abstract: MAS NMR was used to elucidate the position the cationic species in alkaline earth metal exchanged silicoaluminophosphates. These species played a significant role during the ion exchange process and, therefore, the materials ultimate CO{sub 2} adsorption performance. Highlights: Black-Right-Pointing-Pointer Location of extraframework Sr{sup 2+} or Ba{sup 2+} cations was estimated by means of {sup 1}H and {sup 23}Na MAS NMR. Black-Right-Pointing-Pointer Level of Sr{sup 2+} or Ba{sup 2+} ion exchange was limited by the presence of protons and sodium cations. Black-Right-Pointing-Pointer Presence of ammonium cations in the supercages facilitated the exchange. Black-Right-Pointing-Pointer Sr{sup 2+} and Ba{sup 2+} ion exchanged SAPOs are outstanding CO{sub 2} adsorbents.

  20. Spin glasses

    International Nuclear Information System (INIS)

    Fischer, K.H.; Hertz, J.A.

    1993-01-01

    Spin glasses, simply defined by the authors as a collection of spins (i.e., magnetic moments) whose low-temperature state is a frozen disordered one, represent one of the fascinating new fields of study in condensed matter physics, and this book is the first to offer a comprehensive account of the subject. Included are discussions of the most important developments in theory, experimental work, and computer modeling of spin glasses, all of which have taken place essentially within the last two decades. The first part of the book gives a general introduction to the basic concepts and a discussion of mean field theory, while the second half concentrates on experimental results, scaling theory, and computer simulation of the structure of spin glasses

  1. Raman spectra and optical properties of selected Bi2O3-PbO-B2O3-GeO2 glasses

    Czech Academy of Sciences Publication Activity Database

    Knoblochová, K.; Tichá, H.; Schwarz, J.; Tichý, Ladislav

    2009-01-01

    Roč. 31, neuvedeno (2009), s. 895-898 ISSN 0925-3467 Institutional research plan: CEZ:AV0Z40500505 Keywords : heavy metal oxide glasses Subject RIV: CA - Inorganic Chemistry Impact factor: 1.728, year: 2009

  2. Effect of material, process parameters, and simulated body fluids on mechanical properties of 13-93 bioactive glass porous constructs made by selective laser sintering.

    Science.gov (United States)

    Kolan, Krishna C R; Leu, Ming C; Hilmas, Gregory E; Velez, Mariano

    2012-09-01

    The effect of particle size distribution, binder content, processing parameters, and sintering schedule on the microstructure and mechanical properties of porous constructs was investigated. The porous constructs were produced by indirect selective laser sintering (SLS) of 13-93 bioactive glass using stearic acid as a polymeric binder. The binder content and d(50) particle size in the feedstock powders were simultaneously reduced from 22 to 12 wt% and from 20 to 11 μm, respectively, to identify the minimum binder content required for the SLS fabrication. An average particle size of ∼16 μm with a binder content of 15 wt% significantly reduced post-processing time and improved mechanical properties. Increasing the laser power and scan speed at the energy density of 1 cal/cm² maintained the feature sharpness of the parts during the fabrication of green parts and could almost double the mechanical properties of the sintered parts. Changes in the heating rates, ranging from 0.1 to 2 °C/min, during the post-processing of the fabricated "green" scaffolds showed that the heating rate significantly affects the densification and mechanical properties of the sintered scaffolds. The compressive strength of the scaffolds manufactured with the optimized parameters varied from 41 MPa, for a scaffold with a porosity of ∼50%, to 157 MPa, for a dense part. The bioactive scaffolds soaked in simulated body fluids for durations up to 6 weeks were used to evaluate the change in mechanical properties in vitro. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Metallic glasses

    NARCIS (Netherlands)

    Schaafsma, Arjen Sybren

    1981-01-01

    It is shown in section 7.1. that the influence of topological disorder on the range of magnetic interactions in ferromagnetic transition metal-metalloid (TM-M) glasses, is much less than often assumed. This is demonstrated via a study of the temperature dependence of the average iron hyperfine field

  4. Does the presence of bacteria effect basaltic glass dissolution rates? 1: Dead Pseudomonas reactants

    Science.gov (United States)

    Stockmann, Gabrielle J.; Shirokova, Liudmila S.; Pokrovsky, Oleg S.; Oelkers, Eric H.; Benezeth, Pascale

    2010-05-01

    Basaltic glass and crystalline basalt formations in Iceland have been suggested for industrial CO2 storage due to their porous and permeable properties and high reactivity. Acid CO2-saturated waters in contact with basaltic glass will lead to rapid dissolution of the glass and release of divalent cations, (Ca2+, Mg2+, Fe2+) that can react to form stable carbonates and thereby trap the CO2. However, the basalt formations in Iceland not only contains glass and mineral assemblages, but also host microbiological communities that either by their presence or by active involvement in chemical reactions could affect the amount of basaltic glass being dissolved and CO2 being trapped. Samples of natural bacteria communities from the CO2 storage grounds in Iceland were collected, separated, and purified using agar plate technique and cultured under laboratory conditions in nutrient broth-rich media. Heterotrophic aerobic Gram-negative strain of Pseudomonas reactants was selected for a series of flow-through experiments aimed at evaluation of basaltic glass dissolution rate in the presense of increasing amounts of dead bacteria and their lysis products. The experiments were carried out using mixed-flow reactors at pH 4, 6, 8 and 10 at 25 °C. Each of the four reactors contained 1 gram of basaltic glass of the size fraction 45-125 μm. This glass was dissolved in ~ 0.01 M buffer solutions (acetate, MES, bicarbonate and carbonate+bicarbonate mixture) of the desired pH. All experiments ran 2 months, keeping the flowrate and temperature stable and only changing the concentration of dead bacteria in the inlet solutions (from 0 to 430 mg/L). Experiments were performed in sterile conditions, and bacterial growth was prevented by adding NaN3 to the inlet solutions. Routine culturing of bacteria on the agar plates confirmed the sterility of experiments. Samples of outlet solutions were analyzed for major cations and trace elements by ICP-MS. Results demonstrate a slight decrease in the

  5. Raman spectroscopy of tellurate-tungstate glasses

    International Nuclear Information System (INIS)

    Gugov, I.B.; Brovchenko, I.M.; Kabanov, V.O.; Yanush, O.V.

    1989-01-01

    The Raman spectra of xTeO 2 - (1-x)WO 3 glasses, where 0.75 4 , WO 4 and WO 6 structural groups observed. This is in accordance with the absence of some chemical compounds between TeO 2 and WO 3 in the phase diagram of the system. The presence of WO 4 tetrahedra in the glasses, not observed in the different WO 3 crystalline modifications and the crystallized glasses, was defined as a feature of WO 3 g lassy state . It was suggested that the WO 4 tetrahedron does not replace equivalently the TeO 4 polyhedron in the glass structure, as it was reported previously, because of the different valency state of both cations. (author)

  6. Structure of cesium loaded iron phosphate glasses: An infrared and Raman spectroscopy study

    International Nuclear Information System (INIS)

    Joseph, Kitheri; Premila, M.; Amarendra, G.; Govindan Kutty, K.V.; Sundar, C.S.; Vasudeva Rao, P.R.

    2012-01-01

    The structure of cesium loaded iron phosphate glasses (IPG) was investigated using infrared and Raman spectroscopy. The spectra of the cesium doped samples revealed a structural modification of the parent glass owing to the incorporation of cesium. The structural changes could be correlated with the variation observed in the glass transition temperature of these glasses. Increased Cs-mediated cationic cross linking appears to be the reason for the initial rise in glass transition temperature up to 21 mol% Cs 2 O in IPG; while, breakdown of the phosphate network with increasing cesium content, brings down the glass transition temperature.

  7. Penetration Physics of Armor Glass

    Science.gov (United States)

    2009-11-30

    shaft (b). The surface of the fragment agglomerate in contact with the projectile shaft in Figure 6 was blackened and coherent, suggesting frictional...rearrangement and breaking up of glass particles, and sliding at the glass/ metal interface. RESULTS Figure 2 shows shear stress as a function of shear...several decades to relate material failure in metals and composites to the underlying microscopic processes, thereby helping to select appropriate

  8. Gas-Phase Intercluster Thiyl-Radical Induced C-H Bond Homolysis Selectively Forms Sugar C2-Radical Cations of Methyl D-Glucopyranoside: Isotopic Labeling Studies and Cleavage Reactions

    Science.gov (United States)

    Osburn, Sandra; Speciale, Gaetano; Williams, Spencer J.; O'Hair, Richard A. J.

    2017-07-01

    A suite of isotopologues of methyl D-glucopyranosides is used in conjunction with multistage mass spectrometry experiments to determine the radical site and cleavage reactions of sugar radical cations formed via a recently developed `bio-inspired' method. In the first stage of CID (MS2), collision-induced dissociation (CID) of a protonated noncovalent complex between the sugar and S-nitrosocysteamine, [H3NCH2CH2SNO + M]+, unleashes a thiyl radical via bond homolysis to give the noncovalent radical cation, [H3NCH2CH2S• + M]+. CID (MS3) of this radical cation complex results in dissociation of the noncovalent complex to generate the sugar radical cation. Replacement of all exchangeable OH and NH protons with deuterons reveals that the sugar radical cation is formed in a process involving abstraction of a hydrogen atom from a C-H bond of the sugar coupled with proton transfer to the sugar, to form [M - H• + D+]. Investigation of this process using individual C-D labeled sugars reveals that the main site of H/D abstraction is the C2 position, since only the C2-deuterium labeled sugar yields a dominant [M - D• + H+] product ion. The fragmentation reactions of the distonic sugar radical cation, [M - H•+ H+], were studied by another stage of CID (MS4). 13C-labeling studies revealed that a series of three related fragment ions each contain the C1-C3 atoms; these arise from cross-ring cleavage reactions of the sugar.

  9. Booted selective internal radiation therapy (B-SIRT) using 90Y-loaded glass microspheres induces prolonged overall survival for PVT patients

    International Nuclear Information System (INIS)

    Garin, E.; Lenoir, L.; Edeline, J.; Laffont, S.; Mesbah, H.; Poree, P.; Boucher, E.; Rolland, Y.

    2015-01-01

    Full text of publication follows. Goal: evaluation of the response rate and survival of hepatocellular carcinoma PVT patients treated with Therasphere using the boost concept. Material and methods: Therasphere was administered in 40 PVT hepatocellular carcinoma patients (main = 11, lobar = 23, segmental = 6). MAA SPECT/CT quantitative analysis was used for the calculation of the tumour dose (TD), the healthy injected liver dose (HLD) and the injected liver dose (LD). Response was evaluated at 3 months using EASL criterion. OS was evaluated using Kaplan and Meyer tests. Results: Mean 90 Y-loaded microspheres injected activity was 3.1 ± 1.5 GBq. Mean LD was 143 ± 49 Gy. Median TD was 316 Gy for responding lesions versus 133 Gy for non responding lesion (p<0.0001). With a threshold TD of 205 Gy, MAA-SPECT/CT was predictive of response with a sensibility of 100%, and an overall accuracy of 90% (0FN, 4FP). Knowing the TD and the HLD, 40% of the patients received an intensification of the treatment (increase of the injected activity with the goal to achieve a TD> 205 Gy with a LD > 150 Gy and a HLD<120 Gy) with a good response rate (81%) and without increased liver grade III toxicity (6.2% as against 12.5% in the non boosted patients, ns). 6 patients were put aside, 5 received a lobar hepatectomy. Median OS was 18.2 months [12-27]. It was 4 m [12-27] for patients with a TD < 205 Gy versus 21.5 m [12-28.5] for patients with a TD > 205 Gy. OS was 12 m [3-∞] for patients with main PVT versus 21.5 m [12-28.7] for patients segmental or lobar PVT (ns). Finally Os was 23.2 m for patients with a TD > 205 Gy and a good PVT targeting (n = 34). Conclusion: boosted selective internal radiation therapy using 90 Y-loaded glass microspheres induces prolonged overall survival for PVT patients without increasing liver toxicity. (authors)

  10. Raman studies and some physical properties of selected (PbO)x(Nb2O5)y(TeO2)1-x-y glasses

    Czech Academy of Sciences Publication Activity Database

    Ožďanová, J.; Tichá, H.; Tichý, Ladislav

    2010-01-01

    Roč. 32, č. 9 (2010), s. 950-955 ISSN 0925- 3467 Institutional research plan: CEZ:AV0Z40500505 Keywords : Raman spectroscopy * Tellurite glasses * Optical properties Subject RIV: CA - Inorganic Chemistry Impact factor: 1.679, year: 2010

  11. Glass packages in interim storage

    International Nuclear Information System (INIS)

    Jacquet-Francillon, N.

    1994-10-01

    This report summarize the current state of knowledge concerning the behavior of type C waste packages consisting of vitrified high-level solutions produced by reprocessing spent fuel. The composition and the physical and chemical properties of the feed solutions are reviewed, and the vitrification process is described. Sodium alumino-borosilicate glass compositions are generally employed - the glass used at la Hague for LWR fuel solutions, for example, contains 45 % SiO 2 . The major physical, chemical, mechanical and thermal properties of the glass are reviewed. In order to allow their thermal power to diminish, the 3630 glass packages produced (as of January 1993) in the vitrification facilities at Marcoule and La Hague are placed in interim storage for several decades. The actual interim storage period has not been defined, as it is closely related to the concept and organization selected for the final destination of the packages: a geological repository. The glass behavior under irradiation is described. Considerable basic and applied research has been conducted to assess the aqueous leaching behavior of nuclear containment glass. The effects of various repository parameters (temperature, flow rate, nature of the environmental materials) have been investigated. The experimental findings have been used to specify a model describing the kinetics of aqueous corrosion of the glass. More generally all the ''source term'' models developed in France by the CEA or by ANDRA are summarized. (author). 152 refs., 33 figs

  12. SCHOTT optical glass in space

    Science.gov (United States)

    Jedamzik, Ralf; Petzold, Uwe

    2017-09-01

    Optical systems in space environment have to withstand harsh radiation. Radiation in space usually comes from three main sources: the Van Allen radiation belts (mainly electrons and protons); solar proton events and solar energetic particles (heavier ions); and galactic cosmic rays (gamma- or x-rays). Other heavy environmental effects include short wavelength radiation (UV) and extreme temperatures (cold and hot). Radiation can damage optical glasses and effect their optical properties. The most common effect is solarization, the decrease in transmittance by radiation. This effect can be observed for UV radiation and for gamma or electron radiation. Optical glasses can be stabilized against many radiation effects. SCHOTT offers radiation resistant glasses that do not show solarization effects for gamma or electron radiation. A review of SCHOTT optical glasses in space missions shows, that not only radiation resistant glasses are used in the optical designs, but also standard optical glasses. This publication finishes with a selection of space missions using SCHOTT optical glass over the last decades.

  13. BNFL Report Glass Formers Characterization

    International Nuclear Information System (INIS)

    Schumacher, R.F.

    2000-01-01

    The objective of this task was to obtain powder property data on candidate glass former materials, sufficient to guide conceptual design and estimate the cost of glass former handling facilities as requested under Part B1 of BNFL Technical and Development Support. Twenty-nine glass forming materials were selected and obtained from vendors for the characterization of their physical properties, durability in caustic solution, and powder flow characteristics. A glass former was selected based on the characterization for each of the ten oxide classes required for Envelope A, B, and C mixtures. Three blends (A, B, and C) were prepared based on formulations provided by Vitreous State Laboratory and evaluated with the same methods employed for the glass formers. The properties obtained are presented in a series of attached Tables. It was determined that five of the ten glass formers, (kyanite, iron oxide, titania, zircon, and zinc oxide) have the potential to cause some level of solids f low problems. In addition, all of the blends may require consideration for their handling. A number of engineering considerations and recommendations were prepared based on the experimental findings, experience, and other process considerations. Recommendations for future testing are included. In conjunction with future work, it is recommended that a professional consultant be engaged to guide and assist with testing and design input

  14. BNFL Report Glass Formers Characterization

    Energy Technology Data Exchange (ETDEWEB)

    Schumacher, R.F.

    2000-07-27

    The objective of this task was to obtain powder property data on candidate glass former materials, sufficient to guide conceptual design and estimate the cost of glass former handling facilities as requested under Part B1 of BNFL Technical and Development Support. Twenty-nine glass forming materials were selected and obtained from vendors for the characterization of their physical properties, durability in caustic solution, and powder flow characteristics. A glass former was selected based on the characterization for each of the ten oxide classes required for Envelope A, B, and C mixtures. Three blends (A, B, and C) were prepared based on formulations provided by Vitreous State Laboratory and evaluated with the same methods employed for the glass formers. The properties obtained are presented in a series of attached Tables. It was determined that five of the ten glass formers, (kyanite, iron oxide, titania, zircon, and zinc oxide) have the potential to cause some level of solids f low problems. The problems might include arching or ratholing in the silo/hopper. In addition, all of the blends may require consideration for their handling.

  15. BNFL Report Glass Formers Characterization

    International Nuclear Information System (INIS)

    Schumacher, R.F.

    2000-01-01

    The objective of this task was to obtain powder property data on candidate glass former materials, sufficient to guide conceptual design and estimate the cost of glass former handling facilities as requested under Part B1 of BNFL Technical and Development Support. Twenty-nine glass forming materials were selected and obtained from vendors for the characterization of their physical properties, durability in caustic solution, and powder flow characteristics. A glass former was selected based on the characterization for each of the ten oxide classes required for Envelope A, B, and C mixtures. Three blends (A, B, and C) were prepared based on formulations provided by Vitreous State Laboratory and evaluated with the same methods employed for the glass formers. The properties obtained are presented in a series of attached Tables. It was determined that five of the ten glass formers, (kyanite, iron oxide, titania, zircon, and zinc oxide) have the potential to cause some level of solids f low problems. The problems might include arching or ratholing in the silo/hopper. In addition, all of the blends may require consideration for their handling

  16. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu

    2017-04-27

    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  17. Wear of MgO-CaO-SiO2-P2O5-F-Based Glass Ceramics Compared to Selected Dental Ceramics

    Directory of Open Access Journals (Sweden)

    Jongee Park

    2007-01-01

    Full Text Available Wear of a glass-ceramic produced through controlled crystallization of a glass in the MgO-CaO-SiO2-P2O5-F system has been evaluated and compared to various commercial dental ceramics including IPS Empress 2, Cergo Pressable Ceramic, Cerco Ceram, and Super porcelain EX-3. Wear tests were performed in accord with the ASTM G99 for wear testing with a pin-on-disk apparatus. The friction coefficient and specific wear rate of the materials investigated were determined at a load of 10 N and at ambient laboratory conditions. Microhardness of the materials was also measured to elucidate the appropriateness of these materials for dental applications.

  18. Reducible cationic lipids for gene transfer.

    Science.gov (United States)

    Wetzer, B; Byk, G; Frederic, M; Airiau, M; Blanche, F; Pitard, B; Scherman, D

    2001-01-01

    One of the main challenges of gene therapy remains the increase of gene delivery into eukaryotic cells. We tested whether intracellular DNA release, an essential step for gene transfer, could be facilitated by using reducible cationic DNA-delivery vectors. For this purpose, plasmid DNA was complexed with cationic lipids bearing a disulphide bond. This reduction-sensitive linker is expected to be reduced and cleaved in the reducing milieu of the cytoplasm, thus potentially improving DNA release and consequently transfection. The DNA--disulphide-lipid complexation was monitored by ethidium bromide exclusion, and the size of complexes was determined by dynamic light scattering. It was found that the reduction kinetics of disulphide groups in DNA--lipid complexes depended on the position of the disulphide linker within the lipid molecule. Furthermore, the internal structure of DNA--lipid particles was examined by small-angle X-ray scattering before and after lipid reduction. DNA release from lipid complexes was observed after the reduction of disulphide bonds of several lipids. Cell-transfection experiments suggested that complexes formed with selected reducible lipids resulted in up to 1000-fold higher reporter-gene activity, when compared with their analogues without disulphide bonds. In conclusion, reduction-sensitive groups introduced into cationic lipid backbones potentially allow enhanced DNA release from DNA--lipid complexes after intracellular reduction and represent a tool for improved vectorization. PMID:11389682

  19. Resonance Raman investigation of the radical cation of 1,3,5-hexatriene

    DEFF Research Database (Denmark)

    Keszhelyi, T.; Wilbrandt, R.; Cave, R.J.

    1994-01-01

    The resonance Raman spectrum of the 1,3,5-hexatriene radical cation generated by gamma-irradiation in a Freon glass is reported. The spectrum is excited at 395 nm in resonance with the second absorption band. Identical spectra are obtained from ionized (E)- and (Z)-1,3,5-hexatriene. The presence...

  20. Investigation into structure of berylliumaluminium silicate glasses and crystals by X-ray spectroscopy

    International Nuclear Information System (INIS)

    Tykachinskij, I.D.; Gorbachev, V.V.; Petrakov, V.N.; Varshal, B.G.; Bystrakov, A.S.; Dmitriev, I.D.; Zatsepin, A.F.; Blaginina, L.A.

    1983-01-01

    For the purpose of elucidating the structural state of Be 2+ and Al 3+ ions as well as the nature of Be-O bond the investigation of glasses obtained from BeO, Al 2 O 3 and SiO 2 with different component composition is undertaken by X-ray spectroscopy. In three-component beryllium alumosilicate glasses at the ratio γ=Al 2 O 3 /BeO=0.34-1.92 the main part of Al 3+ cations forms AlO 4 groups. Be 2+ cations probably occupy several non-equivalent states. At the ''crystal-glass'' transition the reorganization of near structure of beryllium alumosilicate frame with appearance in a glass in contrast to crystal analog of beryllium cations playing the role of a glass former (being a part of glass net) as well as a modifier role occurs. For compositions with γ=1 the degree of ionic character of the Be-O bond is the greatest. The increase of Be 2+ cations fraction being a part of the glass net is characteristic feature of the glasses with parameter values γ not equal to 1

  1. Crystallization In Multicomponent Glasses

    International Nuclear Information System (INIS)

    Kruger, A.A.; Hrma, P.R.

    2009-01-01

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  2. CRYSTALLIZATION IN MULTICOMPONENT GLASSES

    Energy Technology Data Exchange (ETDEWEB)

    KRUGER AA; HRMA PR

    2009-10-08

    In glass processing situations involving glass crystallization, various crystalline forms nucleate, grow, and dissolve, typically in a nonuniform temperature field of molten glass subjected to convection. Nuclear waste glasses are remarkable examples of multicomponent vitrified mixtures involving partial crystallization. In the glass melter, crystals form and dissolve during batch-to-glass conversion, melter processing, and product cooling. Crystals often agglomerate and sink, and they may settle at the melter bottom. Within the body of cooling glass, multiple phases crystallize in a non-uniform time-dependent temperature field. Self-organizing periodic distribution (the Liesegnang effect) is common. Various crystallization phenomena that occur in glass making are reviewed.

  3. Impact Strength of Glass and Glass Ceramic

    Science.gov (United States)

    Bless, S.; Tolman, J.

    2009-12-01

    Strength of glass and glass ceramic was measured with a bar impact technique. High-speed movies show regions of tensile and compressive failure. The borosilicate glass had a compressive strength of at least 2.2 GPa, and the glass ceramic at least 4 GPa. However, the BSG was much stronger in tension than GC. In ballistic tests, the BSG was the superior armor.

  4. A hybrid semiconductor-glass waveguide laser

    NARCIS (Netherlands)

    Fan, Y.; Oldenbeuving, R.M.; Klein, E.J.; Lee, C.J.; Song, H.; Khan, M.R.H.; Offerhaus, H.L.; Van der Slot, P.J.M.; Boller, K.J.

    2014-01-01

    We report on a novel type of laser in which a semiconductor optical amplifier (SOA) receives frequency-selective feedback from a glass-waveguide circuit. The laser we present here is based on InP for operation in the 1.55 µm wavelength range. The Si3N4/SiO2 glass waveguide circuit comprises two

  5. A hybrid semiconductor-glass waveguide laser

    NARCIS (Netherlands)

    Fan, Youwen; Oldenbeuving, Ruud; Klein, E.J.; Lee, Christopher James; Song, H.; Khan, M.R.H.; Offerhaus, Herman L.; van der Slot, Petrus J.M.; Boller, Klaus J.; Mackenzie, J.I.; Jelinkova, H.; Taira, T.; Ahmed, M.A.

    2014-01-01

    abstract .We report on a novel type of laser in which a semiconductor optical amplifier (SOA) receives frequency-selective feedback from a glass-waveguide circuit. The laser we present here is based on InP for operation in the 1.55 μm wavelength range. The Si3N4/SiO2 glass waveguide circuit

  6. Recycling of Glass

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Damgaard, Anders

    2011-01-01

    Glass is used for many purposes, but in the waste system glass is predominantly found in terms of beverage and food containers with a relatively short lifetime before ending up in the waste. Furthermore there is a large amount of flat glass used in building materials which also ends up in the waste...... system; this glass though has a long lifetime before ending up in the waste. Altogether these product types add up to 82% of the production of the European glass industry (IPCC, 2001). Recycling of glass in terms of cleaning and refilling of bottles as well as the use of broken glass in the production...... of new glass containers is well established in the glass industry. This chapter describes briefly howglass is produced and howwaste glass is recycled in the industry. Quality requirements and use of recycled products are discussed, as are the resource and environmental issues of glass recycling....

  7. Selectivity of the highly preorganized tetradentate ligand 2,9-di(pyrid-2-yl)-1,10-phenanthroline for metal ions in aqueous solution, including lanthanide(III) ions and the uranyl(VI) cation.

    Science.gov (United States)

    Carolan, Ashley N; Cockrell, Gregory M; Williams, Neil J; Zhang, Gang; VanDerveer, Donald G; Lee, Hee-Seung; Thummel, Randolph P; Hancock, Robert D

    2013-01-07

    Some metal ion complexing properties of DPP (2,9-Di(pyrid-2-yl)-1,10-phenanthroline) are reported with a variety of Ln(III) (Lanthanide(III)) ions and alkali earth metal ions, as well as the uranyl(VI) cation. The intense π-π* transitions in the absorption spectra of aqueous solutions of 10(-5) M DPP were monitored as a function of pH and metal ion concentration to determine formation constants of the alkali-earth metal ions and Ln(III) (Ln = lanthanide) ions. It was found that log K(1)(DPP) for the Ln(III) ions has a peak at Ln(III) = Sm(III) in a plot of log K(1) versus 1/r(+) (r(+) = ionic radius for 8-coordination). For Ln(III) ions larger than Sm(III), there is a steady rise in log K(1) from La(III) to Sm(III), while for Ln(III) ions smaller than Sm(III), log K(1) decreases slightly to the smallest Ln(III) ion, Lu(III). This pattern of variation of log K(1) with varying size of Ln(III) ion was analyzed using MM (molecular mechanics) and DFT (density functional theory) calculations. Values of strain energy (∑U) were calculated for the [Ln(DPP)(H(2)O)(5)](3+) and [Ln(qpy)(H(2)O)(5)](3+) (qpy = quaterpyrdine) complexes of all the Ln(III) ions. The ideal M-N bond lengths used for the Ln(III) ions were the average of those found in the CSD (Cambridge Structural Database) for the complexes of each of the Ln(III) ions with polypyridyl ligands. Similarly, the ideal M-O bond lengths were those for complexes of the Ln(III) ions with coordinated aqua ligands in the CSD. The MM calculations suggested that in a plot of ∑U versus ideal M-N length, a minimum in ∑U occurred at Pm(III), adjacent in the series to Sm(III). The significance of this result is that (1) MM calculations suggest that a similar metal ion size preference will occur for all polypyridyl-type ligands, including those containing triazine groups, that are being developed as solvent extractants in the separation of Am(III) and Ln(III) ions in the treatment of nuclear waste, and (2) Am(III) is very

  8. Optical properties of lead–tellurite glasses doped with samarium ...

    Indian Academy of Sciences (India)

    Administrator

    This may be due to the creation of more non-bridging oxygen at 0⋅4 mol% of. Sm2O3 and hence a glass structure change takes place. This also may be due to the presence of higher valence oxide ion, Pb. 2+. , when it is acting as a modifier, the cations present in the network can produce important structural effects.

  9. Magnetic Glass Ceramics by Sintering of Borosilicate Glass and Inorganic Waste

    Directory of Open Access Journals (Sweden)

    Inès M. M. M. Ponsot

    2014-07-01

    Full Text Available Ceramics and glass ceramics based on industrial waste have been widely recognized as competitive products for building applications; however, there is a great potential for such materials with novel functionalities. In this paper, we discuss the development of magnetic sintered glass ceramics based on two iron-rich slags, coming from non-ferrous metallurgy and recycled borosilicate glass. The substantial viscous flow of the glass led to dense products for rapid treatments at relatively low temperatures (900–1000 °C, whereas glass/slag interactions resulted in the formation of magnetite crystals, providing ferrimagnetism. Such behavior could be exploited for applying the obtained glass ceramics as induction heating plates, according to preliminary tests (showing the rapid heating of selected samples, even above 200 °C. The chemical durability and safety of the obtained glass ceramics were assessed by both leaching tests and cytotoxicity tests.

  10. Removal of metal cations from wastewater using recycled wool-based non-woven material

    Directory of Open Access Journals (Sweden)

    MAJA RADETIC

    2007-06-01

    Full Text Available In this study, the effect of low-temperature air plasma, biopolymer chitosan and hydrogen peroxide treatment of recycled wool-based non-woven material on metal cation uptake was investigated. Recycled wool-based material either as an untreated or modified material showed ability to bind all investigated metal cations in the following order: Pb2+>Cu2+>Zn2+>Co2+. Material performed good selectivity due to distinct sorption rates of studied metal cations.

  11. CADMIUM-RARE EARTH BORATE GLASS AS REACTOR CONTROL MATERIAL

    Science.gov (United States)

    Ploetz, G.L.; Ray, W.E.

    1958-11-01

    A reactor control rod fabricated from a cadmiumrare earth-borate glass is presented. The rare earth component of this glass is selected from among those rare earths having large neutron capture cross sections, such as samarium, gadolinium or europium. Partlcles of this glass are then dispersed in a metal matrix by standard powder metallurgy techniques.

  12. Immobilisation of radwastes in glass containers and products formed thereby

    International Nuclear Information System (INIS)

    Macedo, P.B.; Simmons, C.J.; Lagakos, N.; Simmons, J.H.; Tran, D.C.

    1980-01-01

    A method of preventing the dissemination of toxic material to the environment comprises forming an admixture of toxic material and glass packing in a hollow doped glass container of high silica content, or forming the admixture in a first container and then depositing at least a portion of the admixture in a hollow doped glass container of high silica content. The glass container is then heated to collapse its walls and to seal the container so that the toxic material is entrapped and sealed within the collapsed doped glass container. The thermal expansion coefficient of the container may be decreased prior to use by exchanging hydrogen ion in pores thereof with other cations followed by collapsing the pores. (author)

  13. On the chemical variability of Middelburg glass beads and rods

    International Nuclear Information System (INIS)

    Karklins, K.; Kottman, J.; Hancock, R.G.V.; Sempowski, M.L.; Nohe, A.W.; Moreau, J.-F.; Aufreiter, S.; Kenyon, I.

    2001-01-01

    Forty-three glass samples from a late 16th-early 17th century, glass beadmaking house in Middelburg, the Netherlands, were selected for maximum colouring variability, including plain and multi-coloured varieties. The glass chemistries were quite diverse, within each colour grouping. For each single colour of glass, anticipated colouring elements (copper for turquoise blue, cobalt for dark blue, manganese for rose, and tin for white) were used, with the exception of two beads that were opacified wih antimony rather than with tin. Multi-coloured glass glasses (chevron beads) produced chemistries that match the mixing of the different coloured glasses. In some cases, low relative amounts of some inter-mixed glasses were not detectable against the composition of the major glass component. (author). 16 refs., 3 tabs

  14. Non-parametric analysis of infrared spectra for recognition of glass and glass ceramic fragments in recycling plants.

    Science.gov (United States)

    Farcomeni, Alessio; Serranti, Silvia; Bonifazi, Giuseppe

    2008-01-01

    Glass ceramic detection in glass recycling plants represents a still unsolved problem, as glass ceramic material looks like normal glass and is usually detected only by specialized personnel. The presence of glass-like contaminants inside waste glass products, resulting from both industrial and differentiated urban waste collection, increases process production costs and reduces final product quality. In this paper an innovative approach for glass ceramic recognition, based on the non-parametric analysis of infrared spectra, is proposed and investigated. The work was specifically addressed to the spectral classification of glass and glass ceramic fragments collected in an actual recycling plant from three different production lines: flat glass, colored container-glass and white container-glass. The analyses, carried out in the near and mid-infrared (NIR-MIR) spectral field (1280-4480 nm), show that glass ceramic and glass fragments can be recognized by applying a wavelet transform, with a small classification error. Moreover, a method for selecting only a small subset of relevant wavelength ratios is suggested, allowing the conduct of a fast recognition of the two classes of materials. The results show how the proposed approach can be utilized to develop a classification engine to be integrated inside a hardware and software sorting architecture for fast "on-line" ceramic glass recognition and separation.

  15. Magnesium-phosphate-glass cements with ceramic-type properties

    Science.gov (United States)

    Sugama, T.; Kukacka, L.E.

    1982-09-23

    Rapid setting magnesium phosphate (Mg glass) cementitious materials consisting of magnesium phosphate cement paste, polyborax and water-saturated aggregate, exhibits rapid setting and high early strength characteristics. The magnesium glass cement is prepared from a cation-leachable powder and a bivalent metallic ion-accepting liquid such as an aqueous solution of diammonium phosphate and ammonium polyphosphate. The cation-leachable powder includes a mixture of two different magnesium oxide powders processed and sized differently which when mixed with the bivalent metallic ion-accepting liquid provides the magnesium glass cement consisting primarily of magnesium ortho phosphate tetrahydrate, with magnesium hydroxide and magnesium ammonium phosphate hexahydrate also present. The polyborax serves as a set-retarder. The resulting magnesium mono- and polyphosphate cements are particularly suitable for use as a cementing matrix in rapid repair systems for deteriorated concrete structures as well as construction materials and surface coatings for fireproof structures.

  16. Magnesium phosphate glass cements with ceramic-type properties

    Science.gov (United States)

    Sugama, Toshifumi; Kukacka, Lawrence E.

    1984-03-13

    Rapid setting magnesium phosphate (Mg glass) cementitious materials consisting of magnesium phosphate cement paste, polyborax and water-saturated aggregate exhibiting rapid setting and high early strength characteristics. The magnesium glass cement is prepared from a cation-leachable powder and a bivalent metallic ion-accepting liquid such as an aqueous solution of diammonium phosphate and ammonium polyphosphate. The cation-leachable powder includes a mixture of two different magnesium oxide powders processed and sized differently which when mixed with the bivalent metallic ion-accepting liquid provides the magnesium glass cement consisting primarily of magnesium ortho phosphate tetrahydrate, with magnesium hydroxide and magnesium ammonium phosphate hexahydrate also present. The polyborax serves as a set-retarder. The resulting magnesium mono- and polyphosphate cements are particularly suitable for use as a cementing matrix in rapid repair systems for deteriorated concrete structures as well as construction materials and surface coatings for fireproof structures.

  17. Thermoset composite recycling: Properties of recovered glass fiber

    DEFF Research Database (Denmark)

    Beauson, Justine; Fraisse, Anthony; Toncelli, C.

    2015-01-01

    Recycling of glass fiber thermoset polymer composite is a challenging topic and a process able to recover the glass fibers original properties in a limited cost is still under investigation. This paper focuses on the recycling technique separating the glass fiber from the matrix material. Four...... different recycling processes, mechanical, burn off, pyrolysis and glycolysis are selected are compared based on the properties of the glass fiber recovered. The intention is to use the same characterization methodology....

  18. Sorption of uranium(VI) onto hydrous ferric oxide-modified zeolite: Assessment of the effect of pH, contact time, temperature, selected cations and anions on sorbent interactions.

    Science.gov (United States)

    Nekhunguni, Pfano Mathews; Tavengwa, Nikita Tawanda; Tutu, Hlanganani

    2017-12-15

    Zeolites are commonly used as adsorbents for metal removal in most applications e.g. in wastewater. However, the ubiquity of iron in such systems may, in the long-term, distort the true interactions and mechanisms of contaminant removal as a result of modification of the zeolite surface. In this study, this potential phenomenon was assessed for the removal of uranium(VI) from aqueous solution by hydrous ferric oxide-modified zeolite (HFOMZ). This was prepared by precipitating iron hydroxide (the common precipitate of iron in aqueous systems) onto zeolite. The prepared HFOMZ was characterised by the scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). Batch adsorption experiments were performed to assess the effect of: pH, initial uranium(VI) concentration, adsorbent dosage, contact time, temperature, presence of cations (Pb 2+ , Cr 3+ , Cu 2+ , Mn 2+ and Co 2+ ) and anions ( [Formula: see text] , [Formula: see text] and [Formula: see text] ) on the adsorption of uranium(VI). Kinetic studies under these conditions indicated that the pseudo second-order kinetic model (R 2  > 0.99) best described the adsorption behaviour, implying that this could be proceeding through a chemisorption process. The experimental data was best described by the Freundlich isotherm model (R 2  > 0.93), an implication that the adsorption surface was heterogeneous. The thermodynamic parameters calculated from the experimental data suggested that the adsorption of U(VI) onto HFOMZ was spontaneous and exothermic in nature. The adsorption of U(VI) onto HFOMZ was dominated by complexation with strong ionizable hydroxyl sites on the hydrous ferric oxide surfaces and the edge sites of the zeolite. At pH values from 2 to 6, increased adsorption was observed and this decreased at higher pH values (above 6). This corresponded with the changes in speciation as determined by the PHREEQC modelling code. The presence of the cations (Pb 2+ , Cr 3+ , Cu 2+ , Mn 2+ and

  19. Boron Isotope Compositions of Selected Fresh MORB Glasses From the Northern EPR (8-10° N): Implications for MORB Magma Contamination

    Science.gov (United States)

    Le Roux, P. J.; Shirey, S. B.; Hauri, E. H.; Perfit, M. R.

    2003-12-01

    The petrogenetic role of seawater and seawater-equilibrated altered crust in the magmatic evolution of basalts formed at mid-ocean ridges is not well-constrained. Observed excess Cl in oceanic basaltic magmas led to established models of assimilation of a saline brine component, although the physical form of this component and whether any other components contaminate MORB magmas remain unresolved. Light stable isotopes such as B are valuable in further refining our understanding of these magmatic processes. The light element B has two stable isotopes (mass 11 and 10) and B isotopic ratio ranges significantly in oceanic settings: e.g. depleted upper mantle (δ 11B -10‰ ), fresh MORB magmas (δ 11B -1.2 to -6.5‰ ), altered oceanic crust (δ 11B +2 to +9‰ ), hydrothermal fluids (δ 11B +30 to +36.5‰ ), and seawater (δ 11B +38.5‰ ). We have developed an in situ laser ablation, multiple multiplier ICP-MS at DTM (see le Roux et al., in press) that has reliable uncertainties for B isotope analyses better than 1‰ (2σ ) over concentration ranges from 0.3 ppm to above 30 ppm. This technique makes nearly any size glass sample amenable to B isotope study. B isotopic compositions were obtained on 16 fresh MORB magmas from the northern East Pacific Rise (EPR) from 8 to 10° N. This region of the EPR has an extensive, existing MORB glass collection, with well-constrained general geochemistry and petrology, recovered from sites on-axis, off-axis (including young off-axis eruptions; abyssal hills), and the Siquerios fracture zone. Geophysical data from this region imaged the top of the dike section (layer 2A) and the sub-axial magma chambers (AMC). Data for these MORB glasses indicate the variable addition of H2O, Cl, F, Li and B to these magmas prior to eruption. The excess Cl can be accounted for by variable (Kent et al, 1999). Variable magma degassing places the contamination of some of these magmas at depths within the oceanic crust close to the top of the AMC

  20. Transition and post-transition metal ions in borate glasses: Borate ligand speciation, cluster formation, and their effect on glass transition and mechanical properties.

    Science.gov (United States)

    Möncke, D; Kamitsos, E I; Palles, D; Limbach, R; Winterstein-Beckmann, A; Honma, T; Yao, Z; Rouxel, T; Wondraczek, L

    2016-09-28

    A series of transition and post-transition metal ion (Mn, Cu, Zn, Pb, Bi) binary borate glasses was studied with special consideration of the cations impact on the borate structure, the cations cross-linking capacity, and more generally, structure-property correlations. Infrared (IR) and Raman spectroscopies were used for the structural characterization. These complementary techniques are sensitive to the short-range order as in the differentiation of tetrahedral and trigonal borate units or regarding the number of non-bridging oxygen ions per unit. Moreover, vibrational spectroscopy is also sensitive to the intermediate-range order and to the presence of superstructural units, such as rings and chains, or the combination of rings. In order to clarify band assignments for the various borate entities, examples are given from pure vitreous B 2 O 3 to meta-, pyro-, ortho-, and even overmodified borate glass compositions. For binary metaborate glasses, the impact of the modifier cation on the borate speciation is shown. High field strength cations such as Zn 2+ enhance the disproportionation of metaborate to polyborate and pyroborate units. Pb 2+ and Bi 3+ induce cluster formation, resulting in PbO n - and BiO n -pseudophases. Both lead and bismuth borate glasses show also a tendency to stabilize very large superstructural units in the form of diborate polyanions. Far-IR spectra reflect on the bonding states of modifier cations in glasses. The frequency of the measured cation-site vibration band was used to obtain the average force constant for the metal-oxygen bonding, F M-O . A linear correlation between glass transition temperature (T g ) and F M-O was shown for the metaborate glass series. The mechanical properties of the glasses also correlate with the force constant F M-O , though for cations of similar force constant the fraction of tetrahedral borate units (N 4 ) strongly affects the thermal and mechanical properties. For paramagnetic Cu- and Mn-borate glasses

  1. lead glass brick

    CERN Multimedia

    When you look through the glass at a picture behind, the picture appears raised up because light is slowed down in the dense glass. It is this density (4.06 gcm-3) that makes lead glass attractive to physicists. The refractive index of the glass is 1.708 at 400nm (violet light), meaning that light travels in the glass at about 58% its normal speed. At CERN, the OPAL detector uses some 12000 blocks of glass like this to measure particle energies.

  2. Drug loading to lipid-based cationic nanoparticles

    International Nuclear Information System (INIS)

    Cavalcanti, Leide P.; Konovalov, Oleg; Torriani, Iris L.; Haas, Heinrich

    2005-01-01

    Lipid-based cationic nanoparticles are a new promising option for tumor therapy, because they display enhanced binding and uptake at the neo-angiogenic endothelial cells, which a tumor needs for its nutrition and growth. By loading suitable cytotoxic compounds to the cationic carrier, the tumor endothelial and consequently also the tumor itself can be destroyed. For the development of such novel anti-tumor agents, the control of drug loading and drug release from the carrier matrix is essential. We have studied the incorporation of the hydrophobic anti-cancer agent Paclitaxel (PXL) into a variety of lipid matrices by X-Ray reflectivity measurements. Liposome suspensions from cationic and zwitterionic lipids, comprising different molar fractions of Paclitaxel, were deposited on planar glass substrates. After drying at controlled humidity, well ordered, oriented multilayer stacks were obtained, as proven by the presence of bilayer Bragg peaks to several orders in the reflectivity curves. The presence of the drug induced a decrease of the lipid bilayer spacing, and with an excess of drug, also Bragg peaks of drug crystals could be observed. From the results, insight into the solubility of Paclitaxel in the model membranes was obtained and a structural model of the organization of the drug in the membrane was derived. Results from subsequent pressure/area-isotherm and grazing incidence diffraction (GID) measurements performed with drug/lipid Langmuir monolayers were in accordance with these conjectures

  3. Cationic Antimicrobial Polymers and Their Assemblies

    Science.gov (United States)

    Carmona-Ribeiro, Ana Maria; de Melo Carrasco, Letícia Dias

    2013-01-01

    Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs). The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications. PMID:23665898

  4. Cationic Antimicrobial Polymers and Their Assemblies

    Directory of Open Access Journals (Sweden)

    Ana Maria Carmona-Ribeiro

    2013-05-01

    Full Text Available Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs. The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications.

  5. Micronutrient Fortification of Foods

    African Journals Online (AJOL)

    Micronutrient Fortification of Foods: Developing A Program. Mahshid Lotti, M.G. Venkatesh Manar, Richard J. H. M. .... Develop the fortification technology. 11. Perform studies on interactions, potency, stability, ... Fortification with vitamin A is a long-term strategy capable of maintaining adequate vitamin A status over time.

  6. Cationic electrodepositable coating composition comprising lignin

    Science.gov (United States)

    Fenn, David; Bowman, Mark P; Zawacky, Steven R; Van Buskirk, Ellor J; Kamarchik, Peter

    2013-07-30

    A cationic electrodepositable coating composition is disclosed. The present invention in directed to a cationic electrodepositable coating composition comprising a lignin-containing cationic salt resin, that comprises (A) the reaction product of: lignin, an amine, and a carbonyl compound; (B) the reaction product of lignin, epichlorohydrin, and an amine; or (C) combinations thereof.

  7. Glass and nuclear wastes

    International Nuclear Information System (INIS)

    Sombret, C.

    1982-10-01

    Glass shows interesting technical and economical properties for long term storage of solidified radioactive wastes by vitrification or embedding. Glass composition, vitrification processes, stability under irradiation, thermal stability and aqueous corrosion are studied [fr

  8. Microstructuring of glasses

    CERN Document Server

    Hülsenberg, Dagmar; Bismarck, Alexander

    2008-01-01

    As microstructured glass becomes increasingly important for microsystems technology, the main application fields include micro-fluidic systems, micro-analysis systems, sensors, micro-actuators and implants. And, because glass has quite distinct properties from silicon, PMMA and metals, applications exist where only glass devices meet the requirements. The main advantages of glass derive from its amorphous nature, the precondition for its - theoretically - direction-independent geometric structurability. Microstructuring of Glasses deals with the amorphous state, various glass compositions and their properties, the interactions between glasses and the electromagnetic waves used to modify it. Also treated in detail are methods for influencing the geometrical microstructure of glasses by mechanical, chemical, thermal, optical, and electrical treatment, and the methods and equipment required to produce actual microdevices.

  9. PLUTONIUM SOLUBILITY IN HIGH-LEVEL WASTE ALKALI BOROSILICATE GLASS

    Energy Technology Data Exchange (ETDEWEB)

    Marra, J.; Crawford, C.; Fox, K.; Bibler, N.

    2011-01-04

    The solubility of plutonium in a Sludge Batch 6 (SB6) reference glass and the effect of incorporation of Pu in the glass on specific glass properties were evaluated. A Pu loading of 1 wt % in glass was studied. Prior to actual plutonium glass testing, surrogate testing (using Hf as a surrogate for Pu) was conducted to evaluate the homogeneity of significant quantities of Hf (Pu) in the glass, determine the most appropriate methods to evaluate homogeneity for Pu glass testing, and to evaluate the impact of Hf loading in the glass on select glass properties. Surrogate testing was conducted using Hf to represent between 0 and 1 wt % Pu in glass on an equivalent molar basis. A Pu loading of 1 wt % in glass translated to {approx}18 kg Pu per Defense Waste Processing Facility (DWPF) canister, or about 10X the current allowed limit per the Waste Acceptance Product Specifications (2500 g/m{sup 3} of glass or about 1700 g/canister) and about 30X the current allowable concentration based on the fissile material concentration limit referenced in the Yucca Mountain Project License Application (897 g/m{sup 3}3 of glass or about 600 g Pu/canister). Based on historical process throughput data, this level was considered to represent a reasonable upper bound for Pu loading based on the ability to provide Pu containing feed to the DWPF. The task elements included evaluating the distribution of Pu in the glass (e.g. homogeneity), evaluating crystallization within the glass, evaluating select glass properties (with surrogates), and evaluating durability using the Product Consistency Test -- Method A (PCT-A). The behavior of Pu in the melter was evaluated using paper studies and corresponding analyses of DWPF melter pour samples.The results of the testing indicated that at 1 wt % Pu in the glass, the Pu was homogeneously distributed and did not result in any formation of plutonium-containing crystalline phases as long as the glass was prepared under 'well-mixed' conditions

  10. Plutonium Solubility In High-Level Waste Alkali Borosilicate Glass

    International Nuclear Information System (INIS)

    Marra, J.; Crawford, C.; Fox, K.; Bibler, N.

    2011-01-01

    The solubility of plutonium in a Sludge Batch 6 (SB6) reference glass and the effect of incorporation of Pu in the glass on specific glass properties were evaluated. A Pu loading of 1 wt % in glass was studied. Prior to actual plutonium glass testing, surrogate testing (using Hf as a surrogate for Pu) was conducted to evaluate the homogeneity of significant quantities of Hf (Pu) in the glass, determine the most appropriate methods to evaluate homogeneity for Pu glass testing, and to evaluate the impact of Hf loading in the glass on select glass properties. Surrogate testing was conducted using Hf to represent between 0 and 1 wt % Pu in glass on an equivalent molar basis. A Pu loading of 1 wt % in glass translated to ∼18 kg Pu per Defense Waste Processing Facility (DWPF) canister, or about 10X the current allowed limit per the Waste Acceptance Product Specifications (2500 g/m 3 of glass or about 1700 g/canister) and about 30X the current allowable concentration based on the fissile material concentration limit referenced in the Yucca Mountain Project License Application (897 g/m 3 3 of glass or about 600 g Pu/canister). Based on historical process throughput data, this level was considered to represent a reasonable upper bound for Pu loading based on the ability to provide Pu containing feed to the DWPF. The task elements included evaluating the distribution of Pu in the glass (e.g. homogeneity), evaluating crystallization within the glass, evaluating select glass properties (with surrogates), and evaluating durability using the Product Consistency Test -- Method A (PCT-A). The behavior of Pu in the melter was evaluated using paper studies and corresponding analyses of DWPF melter pour samples.The results of the testing indicated that at 1 wt % Pu in the glass, the Pu was homogeneously distributed and did not result in any formation of plutonium-containing crystalline phases as long as the glass was prepared under 'well-mixed' conditions. The incorporation of 1 wt

  11. Measurement of optical glasses

    International Nuclear Information System (INIS)

    Nicolau-Rebigan, S.

    1978-11-01

    The possibilities of measurement of the optical glasses parameters needed in building optical devices especially in lasers devices are presented. In the first chapter the general features of the main optical glasses as well as the modalities of obtaining them are given. Chapter two defines the optical glass parameters, and the third chapter describes the measuring methods of the optical glass parameters. Finally, the conclusions which point out the utilization of this paper are presented. (author)

  12. A structural bond strength model for glass durability

    International Nuclear Information System (INIS)

    Feng, Xiangdong; Metzger, T.B.

    1996-01-01

    A glass durability model, structural bond strength (SBS) model was developed to correlate glass durability with its composition. This model assumes that the strengths of the bonds between cations and oxygens and the structural roles of the individual elements in the glass arc the predominant factors controlling the composition dependence of the chemical durability of glasses. The structural roles of oxides in glass are classified as network formers, network breakers, and intermediates. The structural roles of the oxides depend upon glass composition and the redox state of oxides. Al 2 O 3 , ZrO 2 , Fe 2 O 3 , and B 2 O 3 are assigned as network formers only when there are sufficient alkalis to bind with these oxides. CaO can also improve durability by sharing non-bridging oxygen with alkalis, relieving SiO 2 from alkalis. The percolation phenomenon in glass is also taken into account. The SBS model is applied to correlate the 7-day product consistency test durability of 42 low-level waste glasses with their composition with an R 2 of 0.87, which is better than 0.81 obtained with an eight-coefficient empirical first-order mixture model on the same data set

  13. Cationic mobility in polystyrene sulfone exchangers - Application to the elution of a cation on an exchange column

    International Nuclear Information System (INIS)

    Menin, Jean-Pierre

    1969-01-01

    The aim of this work is to improve elutions and separations carried out on inorganic exchangers by selective electromigration of the ionic species to be displaced. To do this, it has been found indispensable to make a fundamental study of the mobility of cations in exchangers. As the field for this research we have chosen those organic exchangers whose structure and behaviour with respect to ion-exchange are much better known that in the case of their inorganic equivalents. We have related the idea of the equivalent conductivity to that of the cation mobility in the exchanger, and this has entailed determining the specific conductivity of the exchanger and the cation concentration in the resin. The results obtained have allowed us to draw up a hypothesis concerning the cation migration mechanism in the exchanger. The third part of our work has been the application of the preceding results to an operation on an ion-exchange column, viz. the elution by an acid solution of a single fixed ion, magnesium or strontium. This work has enabled us to show that the electromigration of a cation during its elution can markedly accelerate or retard this elution. (author) [fr

  14. Technique for Machining Glass

    Science.gov (United States)

    Rice, S. H.

    1982-01-01

    Process for machining glass with conventional carbide tools requires a small quantity of a lubricant for aluminum applied to area of glass to be machined. A carbide tool is then placed against workpiece with light pressure. Tool is raised periodically to clear work of glass dust and particles. Additional lubricant is applied as it is displaced.

  15. Predicting liquid immiscibility in multicomponent nuclear waste glasses

    International Nuclear Information System (INIS)

    Peeler, D.K.; Hrma, P.R.

    1994-01-01

    Taylor's model for predicting amorphous phase separation in complex, multicomponent systems has been applied to high-level (simulated) radioactive waste glasses at the U.S. Department of Energy's Hanford site. Taylor's model is primarily based on additions of modifying cations to a Na 2 O-B 2 O 3 -SiO 2 (NBS) submixture of the multicomponent glass. The position of the submixture relative to the immiscibility dome defines the development probability of amorphous phase separation. Although prediction of amorphous phase separation in Hanford glasses (via experimental SEM/TEM analysis) is the primary thrust of this work; reported durability data is also provides limited insight into the composition/durability relationship. Using a modified model similar to Taylor's, the results indicate that immiscibility may be predicted for multicomponent waste glasses by the addition of Li 2 O to the open-quotes alkaliclose quotes corner of the NBS submixture

  16. Predicting liquid immiscibility in multicomponent nuclear waste glasses

    International Nuclear Information System (INIS)

    Peeler, D.K.; Hrma, P.R.

    1994-04-01

    Taylor's model for predicting amorphous phase separation in complex, multicomponent systems has been applied to high-level (simulated) radioactive waste glasses at the US Department of Energy's Hanford site. Taylor's model is primarily based on additions of modifying cations to a Na 2 O-B 2 O 3 -SiO 2 (NBS) submixture of the multicomponent glass. The position of the submixture relative to the miscibility dome defines the development probability of amorphous phase separation. Although prediction of amorphous phase separation in Hanford glasses (via experimental SEM/TEM analysis) is the primary thrust of this work; reported durability data is also provides limited insight into the composition/durability relationship. Using a modified model similar to Taylor's, the results indicate that immiscibility may be predicted for multicomponent waste glasses by the addition of Li 2 O to the ''alkali'' corner of the NBS submixture

  17. NMR Studies of Permanent Compression in Oxide Glasses

    DEFF Research Database (Denmark)

    Youngman, Randall E.; Svenson, Mouritz Nolsøe; Mauro, John C.

    useful tool for examining these changes in network structure, especially for boron-containing glasses, which are particularly sensitive to permanent compression. Here we describe studies based on hot isostatic compression of several different borate and borosilicate glasses, where changes in short......Pressure-induced structural rearrangement in oxide glasses is manifested by modification of both short- and intermediate-range structures, including changes to the local coordination numbers of network forming cations and alteration of the modifier environment. NMR spectroscopy is an especially...... of the network modifying sodium atoms, will be discussed. Such changes in network structure aid in understanding the pressure-induced properties of these glasses, such as density, elastic moduli, hardness and crack resistance....

  18. Multiple Glass Ceilings

    OpenAIRE

    Russo, Giovanni; Hassink, Wolter

    2011-01-01

    Both vertical (between job levels) and horizontal (within job levels) mobility can be sources of wage growth. We find that the glass ceiling operates at both margins. The unexplained part of the wage gap grows across job levels (glass ceiling at the vertical margin) and across the deciles of the intra-job-level wage distribution (glass ceiling at the horizontal margin). This implies that women face many glass ceilings, one for each job level above the second, and that the glass ceiling is a p...

  19. Fluoride glass fiber optics

    CERN Document Server

    Aggarwal, Ishwar D

    1991-01-01

    Fluoride Glass Fiber Optics reviews the fundamental aspects of fluoride glasses. This book is divided into nine chapters. Chapter 1 discusses the wide range of fluoride glasses with an emphasis on fluorozirconate-based compositions. The structure of simple fluoride systems, such as BaF2 binary glass is elaborated in Chapter 2. The third chapter covers the intrinsic transparency of fluoride glasses from the UV to the IR, with particular emphasis on the multiphonon edge and electronic edge. The next three chapters are devoted to ultra-low loss optical fibers, reviewing methods for purifying and

  20. Selective intermixing of InGaAs/GaAs/AlGaAs quantum wells with spin-on-glass/MgF2 grating caps

    Science.gov (United States)

    Zhao, Yan-Rui; Yellowhair, Julius; Lee, Jinhyun; Zhang, Shuang; Raub, Alex K.; Wang, Ronghua; Varangis, Petros M.; El-Emawy, Abdel-Rahman; Vilela, Mauro F.; Osinski, Marek

    2001-10-01

    In order to achieve controlled degree of intermixing in selected areas (CISA), SiO2 gratings are checked first to be able to influence the degree of intermixing during high-temperature rapid thermal annealing of InGaAs/GaAs quantum wells. Subsequently, SiO2/MgF2 gratings with different periods are used to cover different parts of MWQ sample and found to be suitable for achieving CISA after only a single annealing procedure.

  1. Acoustics of glass harmonicas

    Science.gov (United States)

    Rossing, Thomas D.

    2004-05-01

    Glass musical instruments are probably as old as glassmaking. At least as early as the 17th century it was discovered that wine glasses, when rubbed with a wet finger, produced a musical tone. A collection of glasses played in this manner is called a glass harp. Another type of glass harmonica, called the armonica by its inventor Benjamin Franklin, employs glass bowls or cups turned by a horizontal axle, so the performer need only touch the rim of the bowls as they rotate to set them into vibration. We discuss the modes of vibration of both types of glass harmonica, and describe the different sounds that are emitted by rubbing, tapping, or bowing them. Rubbing with a wet finger tends to excite only the (2,0) mode and its harmonics through a ``stick-slip'' process, while tapping excites the other modes as well.

  2. Leaching of glass

    International Nuclear Information System (INIS)

    Hench, L.L.

    1977-01-01

    Understanding surface compositional profiles of glasses over a range of 0-2000 A with a variety of analytical instruments shows that five general types of glass surfaces exist. The surface character of a glass article depends upon bulk composition and environmental history during which surface dealkalization, film formation, and network dissolution can occur. Environmental-surface interactions generally result in complex compositional profiles of all the constituents in a glass. Durable glasses almost always develop a stable surface film which has a higher concentration of network formers than the bulk composition. Compositional effects that are used to improve glass durability usually improve the stability of the surface films. Durability tests or service conditions that lead to film destruction are especially severe for the most silicate glasses. 43 references

  3. The benefit of using chemical analysis in understanding archaeological glass. Case-study: Roman black glass

    Science.gov (United States)

    Cosyns, P.; Cagno, S.; Janssens, K.; Nys, K.

    LA-ICP-MS is a well acquainted technique for the quantification of a wide range of minor and trace elements present in the glass matrix. The benefit to understand the changes in technological processes or the added value in assessing the provenance and chronology of the raw glass material is however rarely discussed. By selecting a set of 197 Roman black glass artifacts dating between the 1st and 5th century AD we aimed to contribute to this issue. The obtained data on the production of glass artifacts helps better understand the constantly evolving patterns in glass consumption throughout the Roman imperial period. The key trace elements linked with the sand generally show the use of Levantine and Egyptian raw glass to produce black glass artifacts and result in well defined clusters. These indications are evidence for the use of different raw glasses in the Roman Empire and therefore featuring the work of diverse workshops over time. Specific trace elements such as copper, cobalt and lead reflect the application of recycling glass in Roman times.

  4. Cation-Coupled Bicarbonate Transporters

    OpenAIRE

    Aalkjaer, Christian; Boedtkjer, Ebbe; Choi, Inyeong; Lee, Soojung

    2014-01-01

    Cation-coupled HCO3− transport was initially identified in the mid-1970s when pioneering studies showed that acid extrusion from cells is stimulated by CO2/HCO3− and associated with Na+ and Cl− movement. The first Na+-coupled bicarbonate transporter (NCBT) was expression-cloned in the late 1990s. There are currently five mammalian NCBTs in the SLC4-family: the electrogenic Na,HCO3-cotransporters NBCe1 and NBCe2 (SLC4A4 and SLC4A5 gene products); the electroneutral Na,HCO3-cotransporter NBCn1 ...

  5. Trends in Effective Diffusion Coefficients for Ion-Exchange Strengthening of Soda-Lime-Silicate Glasses

    Directory of Open Access Journals (Sweden)

    Stefan Karlsson

    2017-04-01

    Full Text Available Monovalent cations enable efficient ion-exchange processes due to their high mobility in silicate glasses. Numerous properties can be modified in this way, e.g., mechanical, optical, electrical, or chemical performance. In particular, alkali cation exchange has received significant attention, primarily with respect to introducing compressive stress into the surface region of a glass, which increases mechanical durability. However, most of the present applications rely on specifically tailored matrix compositions in which the cation mobility is enhanced. This largely excludes the major area of soda-lime-silicates (SLS such as are commodity in almost all large-scale applications of glasses. Basic understanding of the relations between structural parameters and the effective diffusion coefficients may help to improve ion-exchanged SLS glass products, on the one hand in terms of obtainable strength and on the other in terms of cost. In the present paper, we discuss the trends in the effective diffusion coefficients when exchanging Na+ for various monovalent cations (K+, Cu+, Ag+, Rb+, and Cs+ by drawing relations to physicochemical properties. Correlations of effective diffusion coefficients were found for the bond dissociation energy and the electronic cation polarizability, indicating that localization and rupture of bonds are of importance for the ion-exchange rate.

  6. The Free Tricoordinated Silyl Cation Problem

    Directory of Open Access Journals (Sweden)

    Čičak, H.

    2010-03-01

    Full Text Available As the importance and abundance of silicon in our environment is large, it has been thought that silicon might take the place of carbon in forming a host of similar compounds and silicon-based life. However, until today there is no experimental evidence for such a hypothesis and carbon is still unique among the elements in the vast number and variety of compounds it can form. Also, the corresponding derivatives of the two elements show considerable differences in their chemical properties.The essential debate concerning organosilicon chemistry relates to the existence of the free planar tricoordinated silyl cations in condensed phase (R3Si+, in analogy to carbocations (R3C+ which have been known and characterized as free species. Although silyl cations are thermodynamically more stable than their carbon analogs, they are very reactive due to their high inherent electrophilicity and the ability of hypervalent coordination. On the other hand, stabilization by inductive and hyperconjugative effects and larger steric effects of carbocations make them less sensitive to solvation or other environmental effects than silyl cations. Hence, observation of free silyl cations in the condensed phase proved extremely difficult and the actual problem is the question of the degree of the (remaining silyl cation character.The first free silyl cation, trimesitylsilyl cation, and in analogy with it tridurylsilyl cation, were synthesized by Lambert et al. Free silyl cations based on analogy to aromatic ions (homocyclopropenylium and tropylium have also been prepared. However, in these silyl cations the cationic character is reduced by internal π -conjugation. Čičak et al. prepared some silyl-cationic intermediates (Me3Si--CH≡CR+in solid state. With the help of quantum-mechanical calculations it was concluded that these adducts have much more silyl cation than carbocation character.

  7. Final Report. Baseline LAW Glass Formulation Testing, VSL-03R3460-1, Rev. 0

    Energy Technology Data Exchange (ETDEWEB)

    Muller, Isabelle S. [The Catholic University of America, Washington, DC (United States); Pegg, Ian L. [The Catholic University of America, Washington, DC (United States); Gan, Hao [The Catholic University of America, Washington, DC (United States); Buechele, Andrew [The Catholic University of America, Washington, DC (United States); Rielley, Elizabeth [The Catholic University of America, Washington, DC (United States); Bazemore, Gina [The Catholic University of America, Washington, DC (United States); Cecil, Richard [The Catholic University of America, Washington, DC (United States); Hight, Kenneth [The Catholic University of America, Washington, DC (United States); Mooers, Cavin [The Catholic University of America, Washington, DC (United States); Lai, Shan-Tao T. [The Catholic University of America, Washington, DC (United States); Kruger, Albert A. [The Catholic University of America, Washington, DC (United States)

    2015-06-18

    The major objective of the baseline glass formulation work was to develop and select glass formulations that are compliant with contractual and processing requirements for each of the LAW waste streams. Other objectives of the work included preparation and characterization of glasses with respect to the properties of interest, optimization of sulfate loading in the glasses, evaluation of ability to achieve waste loading limits, testing to demonstrate compatibility of glass melts with melter materials of construction, development of glass formulations to support ILAW qualification activities, and identification of glass formulation issues with respect to contract specifications and processing requirements.

  8. Optimized Synthesis of Foam Glass from Recycled CRT Panel Glass

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

    Most of the panel glass from cathode ray tubes (CRTs) is landfilled today. Instead of landfilling, the panel glass can be turned into new environment-friendly foam glass. Low density foam glass is an effective heat insulating material and can be produced just by using recycle glass and foaming ad...... calorimetric data show that panel glass possesses good stability against crystallisation. X-ray diffraction data show that the foaming agents enhance the surface crystallisation of the panel glass. We find that the crystallisation impedes the formation of low density foam glass.......Most of the panel glass from cathode ray tubes (CRTs) is landfilled today. Instead of landfilling, the panel glass can be turned into new environment-friendly foam glass. Low density foam glass is an effective heat insulating material and can be produced just by using recycle glass and foaming...

  9. Parametric effects on glass reaction in the unsaturated test method

    Energy Technology Data Exchange (ETDEWEB)

    Woodland, A.B.; Bates, J.K.; Gerding, T.J.

    1991-12-01

    The Unsaturated Test Method has been applied to study glass reaction under conditions that may be present at the potential Yucca Mountain site, currently under evaluation for storage of reprocessed high-level nuclear waste. The results from five separate sets of parametric experiments are presented wherein test parameters ranging from water contact volume to sensitization of metal in contact with the glass were examined. The most significant effect was observed when the volume of water, as controlled by the water inject volume and interval period, was such to allow exfoliation of reacted glass to occur. The extent of reaction was also influenced to a lesser extent by the degree of sensitization of the 304L stainless steel. For each experiment, the release of cations from the glass and alteration of the glass were examined. The major alteration product is a smectite clay that forms both from precipitation from solution and from in-situ alteration of the glass itself. It is this clay that undergoes exfoliation as water drips from the glass. A comparison is made between the results of the parametric experiments with those of static leach tests. In the static tests the rates of release become progressively reduced through 39 weeks while, in contrast, they remain relatively constant in the parametric experiments for at least 300 weeks. This differing behavior may be attributable to the dripping water environment where fresh water is periodically added and where evaporation can occur.

  10. Homogeneity of Inorganic Glasses

    DEFF Research Database (Denmark)

    Jensen, Martin; Zhang, L.; Keding, Ralf

    2011-01-01

    Homogeneity of glasses is a key factor determining their physical and chemical properties and overall quality. However, quantification of the homogeneity of a variety of glasses is still a challenge for glass scientists and technologists. Here, we show a simple approach by which the homogeneity...... of different glass products can be quantified and ranked. This approach is based on determination of both the optical intensity and dimension of the striations in glasses. These two characteristic values areobtained using the image processing method established recently. The logarithmic ratio between...... the dimension and the intensity is used to quantify and rank the homogeneity of glass products. Compared with the refractive index method, the image processing method has a wider detection range and a lower statistical uncertainty....

  11. Glass formation, properties, and structure of soda-yttria-silicate glasses

    Science.gov (United States)

    Angel, Paul W.; Hann, Raiford E.

    1991-01-01

    The glass formation region of the soda yttria silicate system was determined. The glasses within this region were measured to have a density of 2.4 to 3.1 g/cu cm, a refractive index of 1.50 to 1.60, a coefficient of thermal expansion of 7 x 10(exp -6)/C, softening temperatures between 500 and 780 C, and Vickers hardness values of 3.7 to 5.8 GPa. Aqueous chemical durability measurements were made on select glass compositions while infrared transmission spectra were used to study the glass structure and its effect on glass properties. A compositional region was identified which exhibited high thermal expansion, high softening temperatures, and good chemical durability.

  12. Glass formation, properties and structure of soda-yttria-silica glasses

    Science.gov (United States)

    Angel, Paul W.; Hann, Raiford E.

    1992-01-01

    The glass formation region of the soda yttria silicate system was determined. The glasses within this region were measured to have a density of 2.4 to 3.1 g/cu cm, a refractive index of 1.50 to 1.60, a coefficient of thermal expansion of 7 x 10(exp -6)/C, softening temperatures between 500 and 780 C, and Vickers hardness values of 3.7 to 5.8 GPa. Aqueous chemical durability measurements were made on select glass compositions while infrared transmission spectra were used to study the glass structure and its effect on glass properties. A compositional region was identified which exhibited high thermal expansion, high softening temperatures, and good chemical durability.

  13. The effects of composition on glass dissolution rates: The application of four models to a data base

    Energy Technology Data Exchange (ETDEWEB)

    Geldart, R.W.; Kindle, C.H.

    1988-01-01

    Four models have been applied to a data base to relate glass dissolution in distilled water to composition. The data base is used to compare the precisions obtained from the models in fitting actual data. The usefulness of the data base in formulating a model is also demonstrated. Two related models in which the composite or pH-adjusted free energy of hydration of the glass is the correlating parameter are compared with experimental data. In a structural model, the nonbridging oxygen content of the glasses is used to correlate glass dissolution rate to composition. In a model formulated for this report, the cation valence and the oxygen content of the glass are compared with observed dissolution rates. The models were applied to the 28-day normalized silica release at 90/sup 0/C for over 285 glass compositions with surface area to volume ratios of 10 m/sup -1/ (Materials Characterization Center MCC-1 glass durability test using distilled water). These glasses included the nonradioactive analogs of WV205 and SRL-165, as well as SRL-131, PNL 76-68, and a European glass, UK209. Predicted glass dissolution rates show similar fits to the data for all four models. The predictions of the models were also plotted for two subsets of the glasses: waste glasses and Savannah River Laboratory glasses. The model predictions fit the data for these groups much better than they fit the data for the entire set of glasses. 14 refs., 12 figs., 7 tabs.

  14. Diamond turning of glass

    Energy Technology Data Exchange (ETDEWEB)

    Blackley, W.S.; Scattergood, R.O.

    1988-12-01

    A new research initiative will be undertaken to investigate the critical cutting depth concepts for single point diamond turning of brittle, amorphous materials. Inorganic glasses and a brittle, thermoset polymer (organic glass) are the principal candidate materials. Interrupted cutting tests similar to those done in earlier research are Ge and Si crystals will be made to obtain critical depth values as a function of machining parameters. The results will provide systematic data with which to assess machining performance on glasses and amorphous materials

  15. Fractography of glass

    CERN Document Server

    Tressler, Richard

    1994-01-01

    As the first major reference on glass fractography, contributors to this volume offer a comprehensive account of the fracture of glass as well as various fracture surface topography Contributors discuss optical fibers, glass containers, and flatglass fractography In addition, papers explore fracture origins; the growth of the original flaws of defects; and macroscopic fracture patterns from which fracture patterns evolve This volume is complete with photographs and schematics

  16. Glass microspheres for brachytherapy

    International Nuclear Information System (INIS)

    Prado, Miguel O.; Prastalo, Simon; Blaumann, Herman; Longhino, Juan M.; Repetto Llamazares, A.H.V.

    2007-01-01

    We developed the capacity to produce glass microspheres containing in their structure one or more radioactive isotopes useful for brachytherapy. We studied the various facts related with their production: (Rare earth) alumino silicate glass making, glass characterization, microspheres production, nuclear activation through (n,γ) nuclear reactions, mechanical characterization before and after irradiation. Corrosion tests in simulated human plasma and mechanical properties characterization were done before and after irradiation. (author) [es

  17. Glass to contain wastes

    International Nuclear Information System (INIS)

    Moncouyoux, M.; Jacquet-Francillon, M.

    1994-01-01

    Here are the tables and figures presented during the conference on the glass to confine high level radioactive wastes: definition, fabrication, storage and disposal. The composition of glasses are detailed, their properties and the vitrification proceeding. The behaviour of these glasses in front of water, irradiation and heat are shown. The characteristics of parcels are given according to the radiation protection rule, ALARA principle, the concept of multi-barriers and the geological stability

  18. Fly ash adsorbents for multi-cation wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Visa, Maria, E-mail: maria.visa@unitbv.ro [Transilvania University of Brasov, Dept. Renewable Energy Systems and Recycling, Eroilor 29, 500036 Brasov (Romania); Isac, Luminita; Duta, Anca [Transilvania University of Brasov, Dept. Renewable Energy Systems and Recycling, Eroilor 29, 500036 Brasov (Romania)

    2012-06-15

    Class 'F' fly ash (FA), collected from the Central Heat and Power (CHP) Plant Brasov (Romania), with oxides composition SiO{sub 2}/Al{sub 2}O{sub 3} over 2.4 proved good adsorbent properties, and was further used for obtaining a new substrate with good adsorption capacity for heavy metals from multi-cation wastewater treatment. Firstly, the new adsorbent was characterized by AFM, XRD, DSC, FTIR and the surface energy was evaluated by contact angle measurements. The experimental data suggested that the new type of substrate is predominant crystalline with highly polar surface. The substrate was used for removing the Pb{sup 2+}, Cd{sup 2+} and Zn{sup 2+} cations from mixed solutions. The results show high efficiency and selective adsorption the Pb{sup 2+} and Zn{sup 2+} cations. The optimized adsorption parameters were further used in thermodynamic and kinetic studies of the adsorption processes. The Langmuir and Freundlich models were used to describe the processes. The pseudo-second order kinetics could well model all the processes, indicating a surface concentration of the adsorption sites with the same order of magnitude as the cation concentrations.

  19. Adaptive resistance to cationic compounds in Pseudomonas aeruginosa.

    Science.gov (United States)

    Skiada, Anna; Markogiannakis, Antonis; Plachouras, Diamantis; Daikos, George L

    2011-03-01

    Adaptive resistance is an autoregulated phenomenon characterised by induction of resistance in the presence of drug and reversal to the sensitive phenotype in its absence. This type of resistance is well documented for polycationic antibiotics, including aminoglycosides and polymyxins, in Pseudomonas aeruginosa and other aerobic Gram-negative bacilli. It is not caused by selection of resistant mutants but rather by phenotypic alterations in order to survive the lethal drug effect. Adaptive resistance to aminoglycosides is mainly mediated by the MexXY-OprM efflux pump that is rapidly upregulated in bacteria surviving the first exposure to aminoglycosides and is downregulated when bacteria are no longer in contact with the drug. A two-component regulatory system designated ParR-ParS plays a major role in adaptive resistance induced by cationic peptides. In the presence of cationic peptides, ParR-ParS activates the lipopolysaccharide modification operon (arnBCADTEF) leading to increased resistance in polymyxins and aminoglycosides. The bactericidal kinetics related to adaptive resistance have important clinical implications and provide a rationale for administering cationic antibiotics in larger initial and longer interval bolus dosing. A better understanding of this phenomenon and the molecular mechanisms responsible will be essential not only for optimum use of cationic antibiotics but also for developing new agents with ability to counteract the detrimental effects of adaptive resistance and thus enhance the therapeutic efficacy of polycationic compounds. Copyright © 2010 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  20. Decontamination processes for waste glass canisters

    International Nuclear Information System (INIS)

    Rankin, W.N.

    1982-01-01

    A Defense Waste Processing Facility (DWPF) is currently being designed to convert Savannah River Plant liquid, high-level radioactive waste into a solid form, such as borosilicate glass. To prevent the spread of radioactivity, the outside of the canisters of waste glass must have very low levels of smearable radioactive contamination before they are removed from the DWPF. Several techniques were considered for canister decontamination: high-pressure water spray, electropolishing, chemical dissolution, and abrasive blasting. An abrasive blasting technique using a glass frit slurry has been selected for use in the DWPF. No additional equipment is needed to process waste generated from decontamination. Frit used as the abrasive will be mixed with the waste and fed to the glass melter. In contrast, chemical and electrochemical techniques require more space in the DWPF, and produce large amounts of contaminated by-products, which are difficult to immobilize by vitrification

  1. The role of a low-energy–density re-scan in fabricating crack-free Al85Ni5Y6Co2Fe2 bulk metallic glass composites via selective laser melting

    International Nuclear Information System (INIS)

    Li, X.P.; Kang, C.W.; Huang, H.; Sercombe, T.B.

    2014-01-01

    Highlights: • We proposed a re-scan strategy to prevent crack propagation in SLM. • The re-scan should be carried out at a low laser energy density. • The underlying mechanism is through reduction and relief of residual stresses. • Lowered temperature gradient and superplasticity account for reduction of stress. • For the first time, a crack-free BMGCs gear with a large size was produced. - Abstract: In this paper, we have investigated the use of a re-scanning strategy to prevent propagation of macro-cracks during the selective laser melting of an Al 85 Ni 5 Y 6 Co 2 Fe 2 bulk metallic glass composites (BMGCs). These cracks form as a result of the high residual stress caused by the rapid heating and cooling of the material by the laser beam. Unlike crystalline materials, the BMGCs possess a supercooled liquid region in which the residual stress can be relieved by plastic flow. We show that by using a high power initial scan (designed to melt the material) followed by a lower power re-scan (for stress relief) cracking can be prevented. Using this approach, crack-free Al 85 Ni 5 Y 6 Co 2 Fe 2 BMGCs components have been fabricated, including a gear with a diameter ∼25 mm and height ∼10 mm

  2. Comparative investigation on cation-cation (Al-Sn) and cation-anion (Al-F) co-doping in RF sputtered ZnO thin films: Mechanistic insight

    Science.gov (United States)

    Mallick, Arindam; Basak, Durga

    2017-07-01

    Herein, we report a comparative mechanistic study on cation-cation (Al-Sn) and cation-anion (Al-F) co-doped nanocrystalline ZnO thin films grown on glass substrate by RF sputtering technique. Through detailed analyses of crystal structure, surface morphology, microstructure, UV-VIS-NIR transmission-reflection and electrical transport property, the inherent characteristics of the co-doped films were revealed and compared. All the nanocrystalline films retain the hexagonal wurtzite structure of ZnO and show transparency above 90% in the visible and NIR region. As opposed to expectation, Al-Sn (ATZO) co-doped film show no enhanced carrier concentration consistent with the probable formation of SnO2 clusters supported by the X-ray photoelectron spectroscopy study. Most interestingly, it has been found that Al-F (AFZO) co-doped film shows three times enhanced carrier concentration as compared to Al doped and Al-Sn co-doped films attaining a value of ∼9 × 1020 cm-3 due to the respective cation and anion substitution. The carrier relaxation time increases in AFZO while it decreases significantly for ATZO film consistent with the concurrence of the impurity scattering in the latter.

  3. Local structure near actinides and nucleating elements in borosilicate glass for nuclear industry: Results of X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Petit-Maire, D.

    1988-01-01

    Possibilities and limits of X-ray absorption spectroscopy for cation site description in silicate glasses and possible applications for complex glasses, like glass for fission product containment, are examined. In borosilicate glasses two types of sites are evidenced for actinides at the valence 4: Coordinance 6 sites with a narrow radial distribution for the distance An-0; higher coordination (7, 8 or more) with a wider and asymmetrical radial distribution. Proportion of low coordinance sites increases when cation size decreases (Th > Np). U and Np VI and V are characterized as actinyles with a chain 0-An-0 practically linear, coordinance in a plane perpendicular to this complex is probably 5. X-ray absorption spectroscopy allows an accurate description of actinide sites in fission product glasses [fr

  4. Formulation and Characterization of Waste Glasses with Varying Processing Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dong-Sang; Schweiger, M. J.; Rodriguez, Carmen P.; Lepry, William C.; Lang, Jesse B.; Crum, Jarrod V.; Vienna, John D.; Johnson, Fabienne; Marra, James C.; Peeler, David K.

    2011-10-17

    This report documents the preliminary results of glass formulation and characterization accomplished within the finished scope of the EM-31 technology development tasks for WP-4 and WP-5, including WP-4.1.2: Glass Formulation for Next Generation Melter, WP-5.1.2.3: Systematic Glass Studies, and WP-5.1.2.4: Glass Formulation for Specific Wastes. This report also presents the suggested studies for eventual restart of these tasks. The initial glass formulation efforts for the cold crucible induction melter (CCIM), operating at {approx}1200 C, with selected HLW (AZ-101) and LAW (AN-105) successfully developed glasses with significant increase of waste loading compared to that is likely to be achieved based on expected reference WTP formulations. Three glasses formulated for AZ-101HLW and one glass for AN-105 LAW were selected for the initial CCIM demonstration melter tests. Melter tests were not performed within the finished scope of the WP-4.1.2 task. Glass formulations for CCIM were expanded to cover additional HLWs that have high potential to successfully demonstrate the unique advantages of the CCIM technologies based on projected composition of Hanford wastes. However, only the preliminary scoping tests were completed with selected wastes within the finished scope. Advanced glass formulations for the reference WTP melter, operating at {approx}1200 C, were initiated with selected specific wastes to determine the estimated maximum waste loading. The incomplete results from these initial formulation efforts are summarized. For systematic glass studies, a test matrix of 32 high-aluminum glasses was completed based on a new method developed in this study.

  5. Formulation and Characterization of Waste Glasses with Varying Processing Temperature

    International Nuclear Information System (INIS)

    Kim, Dong-Sang; Schweiger, M.J.; Rodriguez, Carmen P.; Lepry, William C.; Lang, Jesse B.; Crum, Jarrod V.; Vienna, John D.; Johnson, Fabienne; Marra, James C.; Peeler, David K.

    2011-01-01

    This report documents the preliminary results of glass formulation and characterization accomplished within the finished scope of the EM-31 technology development tasks for WP-4 and WP-5, including WP-4.1.2: Glass Formulation for Next Generation Melter, WP-5.1.2.3: Systematic Glass Studies, and WP-5.1.2.4: Glass Formulation for Specific Wastes. This report also presents the suggested studies for eventual restart of these tasks. The initial glass formulation efforts for the cold crucible induction melter (CCIM), operating at ∼1200 C, with selected HLW (AZ-101) and LAW (AN-105) successfully developed glasses with significant increase of waste loading compared to that is likely to be achieved based on expected reference WTP formulations. Three glasses formulated for AZ-101HLW and one glass for AN-105 LAW were selected for the initial CCIM demonstration melter tests. Melter tests were not performed within the finished scope of the WP-4.1.2 task. Glass formulations for CCIM were expanded to cover additional HLWs that have high potential to successfully demonstrate the unique advantages of the CCIM technologies based on projected composition of Hanford wastes. However, only the preliminary scoping tests were completed with selected wastes within the finished scope. Advanced glass formulations for the reference WTP melter, operating at ∼1200 C, were initiated with selected specific wastes to determine the estimated maximum waste loading. The incomplete results from these initial formulation efforts are summarized. For systematic glass studies, a test matrix of 32 high-aluminum glasses was completed based on a new method developed in this study.

  6. Structure and aqueous reactivity of silicate glasses high-resolution nuclear magnetic resonance contribution

    International Nuclear Information System (INIS)

    Angeli, F.

    2000-01-01

    This research aims at getting a better understanding of the relations which may exist between the chemical composition of the oxide silicate glasses, the structure and the aqueous reactivity. We study the cations present in most glasses, more particularly the radioactive waste glasses, and those which are more liable to bring information both about structure and reactivity. Among the experimental methods used, the nuclear magnetic resonance of multi-quantum magic-angle spinning (NMR MQ-MAS) has been carried out for the structural characterization of the pristine and altered glasses. In the first part, we discuss the possibility of deducting a type of information from a quantitative approach of the 23 Na, 27 Al and 17 O NMR MQ-MAS. In the second part, we apply this method to glasses containing between two and six oxides. The vitreous compositions studied permit to focus our attention on the influence of sodium, aluminum and calcium on their local structural environment. We point out an evolution of the distributions of bond distances and angles in relation to the glass chemical composition. We show the strong potentiality of the 17 O used to probe the pristine and altered glasses. The influence of the different cations studied on the rate of glass dissolution is debated from the alterations made on short periods. On the basis of all these data, we discuss the importance of the structural effect which may influence the kinetic phenomena of alteration. (author)

  7. Study of nuclear glasses alteration gel and synthesis of some model gels

    International Nuclear Information System (INIS)

    Ricol, S.

    1995-01-01

    This work deals with the general problem of alteration of the reference nuclear glass R7T7. Attention is paid particularly to the altered layer formed at the glass surface during alteration process. In opposition to previous works, related essentially to glass dissolution kinetics based on chemical analyses of lixiviated elements, this thesis deals with alteration problems through structural studies of the reference glass and derived gel. This approach allows the determination of mechanisms for the gel formation and a better understanding of the behaviour of glasses towards lixiviation. Both approaches appeared complementary. Based on several spectroscopic techniques, this work showed the particular role of cations such as calcium, zirconium and iron. Studies of silica-based synthetic gels showed the synergic effect of formers cation and of one highly coordinated cation. The variation of the wavenumber related to Si-O-Si asymmetric stretching vibration can be correlated to O/Si ratio for ternary systems Si/Na/Zr. On the contrary, the Si losses of the materials depend on the number of non-bridging oxygen atoms. In the perspective of long-term behaviour, the alteration gel presents better characteristics than initial glass. It is therefore a highly stable material in static conditions. In the same way, synthetic gels are materials with very low solubilities (much lower than the alteration gel) and could be used as confining matrices. (authors). refs., 71 figs., 37 tabs

  8. The glass block site radionuclide migration study

    International Nuclear Information System (INIS)

    Killey, R.W.D.; Champ, D.R.

    1990-01-01

    In 1960 25 nepheline syenite glass blocks containing 14 TBq of mixed fission products in 50 kg of glass were placed below the water table in a shallow sand aquifer at Chalk River Laboratories. Experimental studies undertaken at the site since 1960 have included detailed mapping of the plume of 90 Sr in 1963, 1966 and 1971. Mathematical modeling studies have employed the radiostrontium plume data in determining the split between ion exchange and chemisorption of 90 Sr, and in obtaining reaction rate data for chemisorption. The distribution of 137 Cs on downgradient soils was mapped in 1963 and 1979. An extended plume of low-level 137 Cs contamination observed in the 1979 study prompted an investigation of the role of particulate materials in radionuclide transport. IN 1983, large volume groundwater sampling and separation of cationic, anionic, and neutral dissolved species, as well as particulates, detected anionic and cationic dissolved europium isotopes (154 and 155), and again encountered particulate 137 Cs. A variety of investigations of cesium and strontium sorption have provided a data base on sediment mineralogy, particle surface features, and information on sorption sites and processes. The year 1990 saw the inauguration of a three-year program to update investigations of radionuclide release, transport, and sorption at the glass block site. The first stage of the program has been a detailed definition and simulation of the hydrogeologic setting. Plume mapping and aqueous speciation studies are in progress. This paper summarizes past investigations, reviews the status of the current program, and discusses components of future studies, including investigations of sediment sorption mechanisms. (Author) (17 refs., 8 figs.)

  9. Afrikaans Syllabification Patterns

    Directory of Open Access Journals (Sweden)

    Tilla Fick

    2010-01-01

    Full Text Available In contrast to English, automatic hyphenation by computer of Afrikaans words is a problem that still needs to be addressed, since errors are still often encountered in printed text. An initial step in this task is the ability to automatically syllabify words. Since new words are created continuously by joining words, it is necessary to develop an “intelligent” technique for syllabification. As a first phase of the research, we consider only the orthographic information of words, and disregard both syntactic and morphological information. This approach allows us to use machine-learning techniques such as artificial neural networks and decision trees that are known for their pattern recognition abilities. Both these techniques are trained with isolated patterns consisting of input patterns and corresponding outputs (or targets that indicate whether the input pattern should be split at a certain position, or not. In the process of compiling a list of syllabified words from which to generate training data for the  syllabification problem, irregular patterns were identified. The same letter patterns are split differently in different words and complete words that are spelled identically are split differently due to meaning. We also identified irregularities in and between  the different dictionaries that we used. We examined the influence range of letters that are involved in irregularities. For example, for their in agter-ente and vaste-rente we have to consider three letters to the left of r to be certain where the hyphen should be inserted. The influence range of the k in verstek-waarde and kleinste-kwadrate is four to the left and three to the right. In an analysis of letter patterns in Afrikaans words we found that the letter e has the highest frequency overall (16,2% of all letters in the word list. The frequency of words starting with s is the highest, while the frequency of words ending with e is the highest. It is important to

  10. Physical and chemical characterization of borosilicate glasses containing Hanford high-level wastes

    International Nuclear Information System (INIS)

    Kupfer, M.J.; Palmer, R.A.

    1980-10-01

    Scouting studies are being performed to develop and evaluate silicate glass forms for immobilization of Hanford high-level wastes. Detailed knowledge of the physical and chemical properties of these glasses is required to assess their suitability for long-term storage or disposal. Some key properties to be considered in selecting a glass waste form include leach resistance, resistance to radiation, microstructure (includes devitrification behavior or crystallinity), homogeneity, viscosity, electrical resistivity, mechanical ruggedness, thermal expansion, thermal conductivity, density, softening point, annealing point, strain point, glass transformation temperature, and refractive index. Other properties that are important during processing of the glass include volatilization of glass and waste components, and corrosivity of the glass on melter components. Experimental procedures used to characterize silicate waste glass forms and typical properties of selected glass compositions containing simulated Hanford sludge and residual liquid wastes are presented. A discussion of the significance and use of each measured property is also presented

  11. WOMEN’S EMPOYMENT ON THE BACKGROUND OF THEIR EDU-CATION AND FERTILITY RATES IN POLAND AND IN SELECTED COUNTRIES OF THE EUROPEAN UNION IN YEARS 2001-2013

    Directory of Open Access Journals (Sweden)

    Katarzyna Martens

    2016-12-01

    Full Text Available This publication considers effects of education and fertility on women’s employment in Poland and in selected countries of the European Union. Econometric models of trend and autoregression are built. It is shown that in Poland - higher education and fertility rates have little effect on the presence of women on the labor market. In the European Union both education and fertility have a significant impact on increasing job opportuni-ties. In Germany an important determinant is education and in France - fertility.

  12. Method for in situ determination cation exchange capacities of subsurface formations

    International Nuclear Information System (INIS)

    Fertl, W.H.; Welker, D.W.

    1980-01-01

    A method is disclosed for the in situ examination of each subsurface formation penetrated by a borehole to ascertain the cation exchange capacity of such formations within a geological region. Natural γ ray logging is used to develop signals functionally related to the total γ radiation and to the potassium-40, uranium and thorium energy-band radiations. A first borehole is traversed by a potential γ ray spectrometer to provide selected measurements of natural γ radiation. Core samples are taken from the logged formation and laboratory tests performed to determine the cation exchange capacity thereof. The cation exchange capacities thus are developed then correlated with selected parameters provided by the γ ray spectrometer to establish functional relationships. Cation exchange capacities of formations in subsequent boreholes within the region are then determined in situ by use of the natural γ ray spectrometer and these established relationships. (author)

  13. Comparison of different cationized proteins as biomaterials for nanoparticle-based ocular gene delivery.

    Science.gov (United States)

    Zorzi, Giovanni K; Párraga, Jenny E; Seijo, Begoña; Sanchez, Alejandro

    2015-11-01

    Cationized polymers have been proposed as transfection agents for gene therapy. The present work aims to improve the understanding of the potential use of different cationized proteins (atelocollagen, albumin and gelatin) as nanoparticle components and to investigate the possibility of modulating the physicochemical properties of the resulting nanoparticle carriers by selecting specific protein characteristics in an attempt to improve current ocular gene-delivery approaches. The toxicity profiles, as well as internalization and transfection efficiency, of the developed nanoparticles can be modulated by modifying the molecular weight of the selected protein and the amine used for cationization. The most promising systems are nanoparticles based on intermediate molecular weight gelatin cationized with the endogenous amine spermine, which exhibit an adequate toxicological profile, as well as effective association and protection of pDNA or siRNA molecules, thereby resulting in higher transfection efficiency and gene silencing than the other studied formulations. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Relaxations in spin glasses: Similarities and differences from ordinary glasses

    International Nuclear Information System (INIS)

    Ngai, K.L.; Rajagopal, A.K.; Huang, C.Y.

    1984-01-01

    Relaxation phenomena have become a major concern in the physics of spin glasses. There are certain resemblances of these relaxation properties to those of ordinary glasses. In this work, we compare the relaxation properties of spin glasses near the freezing temperature with those of glasses near the glass transition temperature. There are similarities between the two types of glasses. Moreover, the relaxation properties of many glasses and spin glasses are in conformity with two coupled ''universality'' relations predicted by a recent model of relaxations in condensed matter

  15. Evaluation of Structural Cellular Glass

    Science.gov (United States)

    Adams, M. A.; Zwissler, J. G.

    1984-01-01

    Preliminary design information presented. First report discusses state of structural-cellular-glass programs as of June 1979. Second report gives further details of program to develop improved cellular glasses and to characterize properties of glasses and commercially available materials.

  16. Getting Started with Glass

    Science.gov (United States)

    White, Heather

    2007-01-01

    The metamorphosis of glass when heated is a magical process to students, yet teachers are often reluctant to try it in class. The biggest challenge in working with glass in the classroom is to simplify procedures just enough to ensure student success while maintaining strict safety practices so no students are injured. Project concepts and safety…

  17. Electric glass capturing markets

    Energy Technology Data Exchange (ETDEWEB)

    Wikman, K.; Wikstroem, T.

    1996-11-01

    Electric glass has found its place on the construction market. In public buildings, electrically heatable windows are becoming the leading option for large glass walls. Studies on detached houses, both new and renovated, show that floor heating combined with electrically heatable windowpanes is the best choice with respect to resident`s comfort. (orig.)

  18. Dramatic Stained Glass.

    Science.gov (United States)

    Prater, Michael

    2002-01-01

    Describes an art project that is appropriate for students in fifth through twelfth grade in which they create Gothic-style stained-glass windows. Discusses how college students majoring in elementary education created stained-glass windows. Addresses how to adapt this lesson for younger students. (CMK)

  19. Structural and crystallisation study of a rare earth alumino borosilicate glass designed for nuclear waste confinement

    International Nuclear Information System (INIS)

    Quintas, A.

    2007-09-01

    This work is devoted to the study of a rare earth alumino borosilicate glass, which molar composition is 61,81 SiO 2 - 3,05 Al 2 O 3 - 8,94 B 2 O 3 - 14,41 Na 2 O - 6,33 CaO - 1,90 ZrO 2 - 3,56 Nd 2 O 3 , and envisaged for the immobilization of nuclear wastes originating from the reprocessing of high discharge burn up spent fuel. From a structural viewpoint, we investigated the role of the modifier cations on the arrangement of the glass network through different modifications of the glass composition: variation of the Na/Ca ratio and modification of the nature of the alkali and alkaline earth cations. The NMR and Raman spectroscopic techniques were useful to determine the distribution of modifier cations among the glass network and also to cast light on the competition phenomena occurring between alkali and alkaline earth cations for charge compensation of [AlO 4 ] - and [BO 4 ] - species. The neodymium local environment could be probed by optical absorption and EXAFS spectroscopies which enabled to better understand the insertion mode of Nd 3+ ions among the silicate domains of the glass network. Concerning the crystallization behavior we were interested in how the glass composition may influence the crystallization processes and especially the formation of the apatite phase of composition Ca 2 Nd 8 (SiO 4 ) 6 O 2 . In particular, this work underlined the important role of both alkaline earth and rare earth cations on the crystallization of the apatite phase. (author)

  20. Optimization of divalent cation in Saccharomyces pastorianus ...

    African Journals Online (AJOL)

    Cassava starch fermentations were conducted in batch cultures to optimize the effect of divalent cations on ethanol production with Saccharomyces pastorianus using the central composite rotatable response surface design. Divalent cations used were magnesium (Mg2+), zinc (Zn2+) and calcium (Ca2+). Maximum ethanol ...

  1. Polymorphism in glasses

    International Nuclear Information System (INIS)

    Landa, L.M.; Nikolaeva, I.N.

    1979-01-01

    To defect phase interfaces and spasmodic properties change, the inhomogeneity and the second radiation effects in quartz glass, metamict phase and intermediate states have been investigated. When irradiating with fast neutrons the transformation of quartz glass - metamict phase occurs completely. The transformation is completed at 2x10 20 part./cm 2 dose. Thermal treatment not only increases the number of inhomogeneities but also results in increasing quartz glass density. Annealing transforms the metamict phase into common quartz glass at 1400 K. The fact, that thermal treatment results in the complete transformation of metamict phase into quartz glass, and the inverse transformation occurs only partially, is quite regular, as the metamict phase has a lesser entropy and is a more ordered state. It is shown that different amorphous phases of a chemical composition have different structures and properties, that there are interfaces between them, and the transformation from one state to another in microvolumes is realized spasmodically and requires expenditure of energy

  2. Mechanical relaxation in glasses

    International Nuclear Information System (INIS)

    Hiki, Y.

    2004-01-01

    The basic properties of glasses and the characteristics of mechanical relaxation in glasses were briefly reviewed, and then our studies concerned were presented. Experimental methods adopted were viscosity, internal friction, ultrasonic attenuation, and Brillouin scattering measurements. The specimens used were several kinds of inorganic, organic, and metallic glasses. The measurements were mainly carried out from the room temperature up to the glass transition temperature, and the relaxation time was determined as a function of temperature. The 'double relaxation' composed of two Arrhenius-type relaxations was observed in many materials. In both relaxations, the 'compensation effect' showing a correlation of the pre-exponential factor and the activation energy was observed. These results were explained by considering the 'complex relaxation' due to cooperative motions of atoms or group of atoms. Values of activation energy near the glass transition determined by the various experimental methods were compared with each other

  3. Glass leaching performance

    International Nuclear Information System (INIS)

    Chick, L.A.; Turcotte, R.P.

    1983-05-01

    Current understanding of the leaching performance of high-level nuclear waste (HLW) glass is summarized. The empirical model of waste glass leaching behavior developed shows that at high water flow rates the glass leach rate is kinetically limited to a maximum value. At intermediate water flow rates, leaching is limited by the solution concentration of silica and decreases with decreasing water flow rates. Release of soluble elements is controlled by silica dissolution because silica forms the binding network of the glass. At low water flow rates, mass loss rates reach values controlled by formation rates of alteration minerals, or by diffusion of dissolution products through essentially stagnant water. The parameters reviewed with respect to their quantifiable influence on leaching behavior include temperature, pH, leachant composition, glass composition, thermal history, and radiation. Of these, temperature is most important since the rate of mass loss approximately doubles with each 10 0 C increase in dilute solutions. The pH has small effects within the 4 to 10 range. The chemical composition of the leachant is most important with regard to its influence on alteration product formation. Glass composition exhibits the largest effects at high flow rates where improved glasses leach from ten to thirty times slower than glass 76 to 68. The effects of the thermal history (devitrification) of the glass are not likely to be significant. Radiation effects are important primarily in that radiolysis can potentially drive pH values to less than 4. Radiation damage to the glass causes insignificant changes in leaching performance

  4. Characterization of Fe 3-doped silver phosphate glasses

    Indian Academy of Sciences (India)

    The relationship among the composition, structure and selected properties for five series of silver phosphate glasses containing 0, 5, 10, 15 and 20wt% Fe 2 O 3 has been investigated. The synthesized glasses have been characterized using different experimental techniques. X-ray diffraction studies revealed that the ...

  5. Characterization of Fe 3 + -doped silver phosphate glasses

    Indian Academy of Sciences (India)

    The relationship among the composition, structure and selected properties for five series of silver phosphate glasses containing 0, 5, 10, 15 and 20wt% Fe 2 O 3 has been investigated. The synthesized glasses have been characterized using different experimental techniques. X-ray diffraction studies revealed that the ...

  6. Waste glass corrosion modeling: Comparison with experimental results

    International Nuclear Information System (INIS)

    Bourcier, W.L.

    1994-01-01

    Models for borosilicate glass dissolution must account for the processes of (1) kinetically-controlled network dissolution, (2) precipitation of secondary phases, (3) ion exchange, (4) rate-limiting diffusive transport of silica through a hydrous surface reaction layer, and (5) specific glass surface interactions with dissolved cations and anions. Current long-term corrosion models for borosilicate glass employ a rate equation consistent with transition state theory embodied in a geochemical reaction-path modeling program that calculates aqueous phase speciation and mineral precipitation/dissolution. These models are currently under development. Future experimental and modeling work to better quantify the rate-controlling processes and validate these models are necessary before the models can be used in repository performance assessment calculations

  7. A new viscosity model for waste glass formulations

    International Nuclear Information System (INIS)

    Sadler, A.L.K.

    1996-01-01

    Waste glass formulation requires prediction, with reasonable accuracy, of properties over much wider ranges of composition than are typically encountered in any single industrial application. Melt viscosity is one such property whose behavior must be predicted in formulating new waste glasses. A model was developed for silicate glasses which relates the Arrhenius activation energy for flow to an open-quotes effectiveclose quotes measure of non-bridging oxygen content in the melt, NBO eff . The NBO eff parameter incorporates the differing effects of modifying cations on the depolymerization of the silicate network. The activation energy-composition relationship implied by the model is in accordance with experimental behavior. The model was validated against two different databases, with satisfactory results

  8. High electric field conduction in low-alkali boroaluminosilicate glass

    Science.gov (United States)

    Dash, Priyanka; Yuan, Mengxue; Gao, Jun; Furman, Eugene; Lanagan, Michael T.

    2018-02-01

    Electrical conduction in silica-based glasses under a low electric field is dominated by high mobility ions such as sodium, and there is a transition from ionic transport to electronic transport as the electric field exceeds 108 V/m at low temperatures. Electrical conduction under a high electric field was investigated in thin low-alkali boroaluminosilicate glass samples, showing nonlinear conduction with the current density scaling approximately with E1/2, where E is the electric field. In addition, thermally stimulated depolarization current (TSDC) characterization was carried out on room-temperature electrically poled glass samples, and an anomalous discharging current flowing in the same direction as the charging current was observed. High electric field conduction and TSDC results led to the conclusion that Poole-Frenkel based electronic transport occurs in the mobile-cation-depleted region adjacent to the anode, and accounts for the observed anomalous current.

  9. The mechanochemical production of phenyl cations through heterolytic bond scission.

    Science.gov (United States)

    Shiraki, Tomohiro; Diesendruck, Charles E; Moore, Jeffrey S

    2014-01-01

    High mechanical forces applied to polymeric materials typically induce unselective chain scission. For the last decade, mechanoresponsive molecules, mechanophores, have been designed to harness the mechanical energy applied to polymers and provide a productive chemical response. The selective homolysis of chemical bonds was achieved by incorporating peroxide and azo mechanophores into polymer backbones. However, selective heterolysis in polymer mechanochemistry is still mostly unachieved. We hypothesized that highly polarized bonds in ionic species are likely to undergo heterolytic bond scission. To test this, we examined a triarylsulfonium salt (TAS) as a mechanophore. Poly(methyl acrylate) possessing TAS at the center of the chain (PMA-TAS) is synthesized by a single electron transfer living radical polymerization (SET-LRP) method. Computational and experimental studies in solution reveal the mechanochemical production of phenyl cations from PMA-TAS. Interestingly, the generated phenyl cation reacts with its counter-anion (trifluoromethanesulfonate) to produce a terminal trifluoromethyl benzene structure that, to the best of our knowledge, is not observed in the photolysis of TAS. Moreover, the phenyl cation can be trapped by the addition of a nucleophile. These findings emphasize the interesting reaction pathways that become available by mechanical activation.

  10. Temperature-induced structural changes in fluorozirconate glasses and liquids

    International Nuclear Information System (INIS)

    Sen, S.; Youngman, R.E.

    2002-01-01

    The atomic structure and its temperature dependence in fluorozirconate glasses and supercooled liquids have been studied with high-resolution and high-temperature 19 F and 23 Na nuclear-magnetic-resonance (NMR) spectroscopy. The 19 F NMR spectra in these glasses show the presence of multiple F environments. Temperature dependence of the 19 F magic-angle-spinning NMR spectra indicates a progressive change in the average F coordination environment in the glass structure, besides motional narrowing due to substantial mobility of F - ions. The observed change in the average 19 F NMR chemical shift is consistent with progressive breaking of the Zr-F-Zr linkages in the glass structure with increasing temperature. The onset of such a change in F speciation is observed at temperatures well below T g . This result is evidence of changes in the average equilibrium structure in an inorganic glass-forming liquid at T g , albeit on a local scale. The 23 Na NMR spectra indicate that the cations in these glasses become significantly mobile only at temperatures T≥T g , which allows for the onset of global structural relaxation and viscous flow

  11. Rare earth impact on glass structure and alteration kinetics

    International Nuclear Information System (INIS)

    Molieres, E.

    2012-01-01

    This work is related to the question of the geological deep repository of high-level waste glass. These wastes include fission products and minor actinides, elements which can be simulated by rare earths. As new glass compositions could enable increased rare earth concentrations, it is crucial to know and understand rare earth impact on glass structure on the one hand, and on glass alteration kinetics or their incorporation into an altered layer. This work studied simplified borosilicate glasses in order to limit synergetic effects between rare earths and other elements. Various complementary techniques were used to characterize pristine and altered glasses (solid-high resolution NMR, Raman spectroscopy, fluorescence, SIMS, SAXS). Firstly, the structural role of a rare earth is discussed and is compared to a calcium cation. The local environment of rare earths is also probed. Secondly, rare earth (nature and concentration) impact on several alteration regimes was studied (initial rate, rate drop). Then, after alteration, rare earth elements being retained within the altered layer, the structural impact of rare earth elements (and their local environment) in this alteration layer was also investigated. (author) [fr

  12. Exploring backbone-cation alkyl spacers for multi-cation side chain anion exchange membranes

    Science.gov (United States)

    Zhu, Liang; Yu, Xuedi; Hickner, Michael A.

    2018-01-01

    In order to systematically study how the arrangement of cations on the side chain and length of alkyl spacers between cations impact the performance of multi-cation AEMs for alkaline fuel cells, a series of polyphenylene oxide (PPO)-based AEMs with different cationic side chains were synthesized. This work resulted in samples with two or three cations in a side chain pendant to the PPO backbone. More importantly, the length of the spacer between cations varied from 3 methylene (-CH2-) (C3) groups to 8 methylene (C8) groups. The highest conductivity, up to 99 mS/cm in liquid water at room temperature, was observed for the triple-cation side chain AEM with pentyl (C5) or hexyl (C6) spacers. The multi-cation AEMs were found to have decreased water uptake and ionic conductivity when the spacer chains between cations were lengthened from pentyl (C5) or hexyl (C6) to octyl (C8) linking groups. The triple-cation membranes with pentyl (C5) or hexyl (C6) groups between cations showed greatest stability after immersion in 1 M NaOH at 80 °C for 500 h.

  13. Intracellular trafficking mechanism of cationic phospholipids including cationic liposomes in HeLa cells.

    Science.gov (United States)

    Un, K; Sakai-Kato, K; Goda, Y

    2014-07-01

    The development of gene delivery methods is essential for the achievement of effective gene therapy. Elucidation of the intracellular transfer mechanism for cationic carriers is in progress, but there are few reports regarding the intracellular trafficking processes of the cationic phospholipids taken up into cells. In the present work, the trafficking processes of a cationic phospholipid (1,2-dioleoyl-3-trimethylammonium-propane, DOTAP) were investigated from intracellular uptake to extracellular efflux using cationic liposomes in vitro. Following intracellular transport of liposomes via endocytosis, DOTAP was localized in the endoplasmic reticulum, Golgi apparatus, and mitochondria. Moreover, the proteins involved in DOTAP intracellular trafficking and extracellular efflux were identified. In addition, helper lipids of cationic liposomes were found to partially affect this intracellulartrafficking. These findings might provide valuable information for designing cationic carriers and avoiding unexpected toxic side effects derived from cationic liposomal components.

  14. Thermal Conductivity of Foam Glass

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

    as thermal insulating material in building and chemical industry. The large volume of gas (porosity 90 – 95%) is the main reason of the low thermal conductivity of the foam glass. If gases with lower thermal conductivity compared to air are entrapped in the glass melt, the derived foam glass will contain...... only closed pores and its overall thermal conductivity will be much lower than that of the foam glass with open pores. In this work we have prepared foam glass using different types of recycled glasses and different kinds of foaming agents. This enabled the formation of foam glasses having gas cells...... with different gas compositions. The foam glasses were characterised concerning densities, open/closed porosity and crystallinity. We find out, through analytical calculations and experiments, how the thermal conductivity of foam glass depends on density, glass composition and gas composition. Certain glass...

  15. Combined cation-exchange and solid phase extraction for the selective separation and preconcentration of zinc, copper, cadmium, mercury and cobalt among others using azo-dye functionalized resin.

    Science.gov (United States)

    Chatterjee, Mousumi; Srivastava, Bhavya; Barman, Milan K; Mandal, Bhabatosh

    2016-04-01

    A facile synthesis of an ion exchange material (FSG-PAN) has been achieved by functionalizing silica gel with an azo-dye. Its composition and structure are well assessed by systematic analysis. Extractor possesses high BET surface area (617.794m(2)g(-1)), exchange capacity and break-through capacity (BTC) (Q0 Zn(II): 225; Cd(II): 918; Hg(II): 384, Cu(II): 269 and Co(II): 388μMg(-1)). The sorption process was endothermic (+ΔH), entropy-gaining (+ΔS) and spontaneous (-ΔG) in nature. Preconcentration factor has been optimized at 172(Zn(II)); 157.2(Cd(II)); 193.6(Hg(II)); 176(Cu(II)); 172.4(Co(II)). Density functional theory calculation has been performed to analyze the sorption pathway. BTC (μMg(-1)) of FSG-PAN was found to be the product of its frontier orbitals and state of sorbed metal ion species, x (at x=1, mononuclear and x>1, a polynuclear species; i.e., BTC=[amount of HOMO]×x). FSG-PAN is used for the selective separation and preconcentration of Zn(II), Cd(II), Hg(II), Cu(II),Co(II) from large volume sample (800mL) of low concentration (0.017-0.40mML(-1)) in presence of foreign ions (50-300mML(-1)) at optimum conditions (pH: 7.0±1.5, flow rate: 2.5mLmin(-1), temperature: 27°C, equilibration-time: 5min). The method was found to be effective for real samples also. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Impact Damage on a Thin Glass Plate with a Thin Polycarbonate Backing

    Science.gov (United States)

    2013-07-13

    skylight glazing and in windshields for automobile, train , and military vehicle. In order to design and improve glass laminates for protective appli- cations...explicit) finite element solution obtained by using Abaqus . The results for the bending deformation in the problem of elastic impact of a spherical rigid

  17. Alkali-free bioactive glasses for bone regeneration =

    Science.gov (United States)

    Kapoor, Saurabh

    Bioactive glasses and glass-ceramics are a class of third generation biomaterials which elicit a special response on their surface when in contact with biological fluids, leading to strong bonding to living tissues. The purpose of the present study was to develop diopside based alkali-free bioactive glasses in order to achieve good sintering behaviour, high bioactivity, and a dissolution/ degradation rates compatible with the target applications in bone regeneration and tissue engineering. Another aim was to understand the structure-property relationships in the investigated bioactive glasses. In this quest, various glass compositions within the Diopside (CaMgSi2O6) - Fluorapatite (Ca5(PO4)3F) - Tricalcium phosphate (3CaO•P2O5) system have been investigated. All the glasses were prepared by melt-quenching technique and characterized by a wide array of complementary characterization techniques. The glass-ceramics were produced by sintering of glass powders compacts followed by a suitable heat treatment to promote the nucleation and crystallization phenomena. Furthermore, selected parent glass compositions were doped with several functional ions and an attempt to understand their effects on the glass structure, sintering ability and on the in vitro bio-degradation and biomineralization behaviours of the glasses was made. The effects of the same variables on the devitrification (nucleation and crystallization) behaviour of glasses to form bioactive glass-ceramics were also investigated. Some of the glasses exhibited high bio-mineralization rates, expressed by the formation of a surface hydroxyapatite layer within 1-12 h of immersion in a simulated body fluid (SBF) solution. All the glasses showed relatively lower degradation rates in comparison to that of 45S5 Bioglass. Some of the glasses showed very good in vitro behaviour and the glasses co-doped with zinc and strontium showed an in vitro dose dependent behaviour. The as-designed bioactive glasses and glass

  18. Cation-Exchanged Zeolitic Chalcogenides for CO2 Adsorption.

    Science.gov (United States)

    Yang, Huajun; Luo, Min; Chen, Xitong; Zhao, Xiang; Lin, Jian; Hu, Dandan; Li, Dongsheng; Bu, Xianhui; Feng, Pingyun; Wu, Tao

    2017-12-18

    We report here the intrinsic advantages of a special family of porous chalcogenides for CO 2 adsorption in terms of high selectivity of CO 2 /N 2 , large uptake capacity, and robust structure due to their first-ever unique integration of the chalcogen-soft surface, high porosity, all-inorganic crystalline framework, and the tunable charge-to-volume ratio of exchangeable cations. Although tuning the CO 2 adsorption properties via the type of exchangeable cations has been well-studied in oxides and MOFs, little is known about the effects of inorganic exchangeable cations in porous chalcogenides, in part because ion exchange in chalcogenides can be very sluggish and incomplete due to their soft character. We have demonstrated that, through a methodological change to progressively tune the host-guest interactions, both facile and nearly complete ion exchange can be accomplished. Herein, a series of cation-exchanged zeolitic chalcogenides (denoted as M@RWY) were studied for the first time for CO 2 adsorption. Samples were prepared through a sequential ion-exchange strategy, and Cs + -, Rb + -, and K + -exchanged samples demonstrated excellent CO 2 adsorption performance. Particularly, K@RWY has the superior CO 2 /N 2 selectivity with the N 2 adsorption even undetected at either 298 or 273 K. It also has the large uptake of 6.3 mmol/g (141 cm 3 /g) at 273 K and 1 atm with an isosteric heat of 35-41 kJ mol -1 , the best among known porous chalcogenides. Moreover, it permits a facile regeneration and exhibits an excellent recyclability, as shown by the multicycling adsorption experiments. Notably, K@RWY also demonstrates a strong tolerance toward water.

  19. Nuclear Waste Glasses - Suitability, Surface Studies, and Stability

    International Nuclear Information System (INIS)

    Wicks, G.G.

    1999-01-01

    Every major country involved with long-term management of high-level radioactive waste (HLW) has either selected or is considering glass as the matrix of choice for immobilizing and ultimately, disposing of the potentially hazardous, high-level radioactive material. There are many reasons why glass is preferred. Among the most important considerations are the ability of glass structures to accommodate and immobilize the many different types of radionuclides present in HLW, and to produce a product that not only has excellent technical properties, but also possesses good processing features. Good processability allows the glass to be fabricated with relative ease even under difficult remote-handling conditions necessary for vitrification of highly radioactive material. The single most important property of the waste glass produced is its ability to retain hazardous species within the glass structure and this is reflected by its excellent chemical durability and corrosion resistance to a wide range of environmental conditions

  20. Glass formulation for phase 1 high-level waste vitrification

    International Nuclear Information System (INIS)

    Vienna, J.D.; Hrma, P.R.

    1996-04-01

    The purpose of this study is to provide potential glass formulations for prospective Phase 1 High-Level Waste (HLW) vitrification at Hanford. The results reported here will be used to aid in developing a Phase 1 HLW vitrification request for proposal (RFP) and facilitate the evaluation of ensuing proposals. The following factors were considered in the glass formulation effort: impact on total glass volume of requiring the vendor to process each of the tank compositions independently versus as a blend; effects of imposing typical values of B 2 O 3 content and waste loading in HLW borosilicate glasses as restrictions on the vendors (according to WAPS 1995, the typical values are 5--10 wt% B 2 O 3 and 20--40 wt% waste oxide loading); impacts of restricting the processing temperature to 1,150 C on eventual glass volume; and effects of caustic washing on any of the selected tank wastes relative to glass volume

  1. Effect of platinoids on French LWR reference glass properties

    International Nuclear Information System (INIS)

    Pacaud, F.; Fillet, C.; Jacquet-Francillon, N.

    1991-01-01

    Nine samples of the 'R7T7' glass composition selected to vitrify fission product solutions in France were prepared with added platinoid elements (ruthenium, rhodium and palladium) in soluble form and as insoluble metal particles in solution, and their major properties were measured. Regardless of the initial form when added to the glass the platinoids always formed the same heterogeneous inclusions in the final glass: RuO 2 precipitates which were often found as aggregates, and polymetallic (Pd, Rh and Te) inclusions. The particles tended to settle in the molten glass. The viscosity increased by about 20% at 1100 deg C. The mechanical properties and short-term leach rates were not significantly affected. Crystallization increased by a factor of 2 or 3 in heat-treated glass specimens but did not exceed a few volume percent. However, as the short-term leach rate did not significantly increase, the glass properties were very satisfactory

  2. Cation transport in isomeric pentanes

    International Nuclear Information System (INIS)

    Gyoergy, Istvan; Gee, Norman; Freeman, G.R.

    1985-01-01

    The cation mobility μsub(+) is measured in n-pentane, isopentane, neo-pentane, and mixtures of n- and neo-pentane over conditions from the normal liquid, through the critical fluid, to the low density gas. Most of the liquid data correlate with the reduced temperature T/Tsub(c). The T/Tsub(c) reflects free volume and viscosity changes. Comparison is made to neutral molecule diffusion. The transition from viscosity control of mobility in the liquid to density control in the dilute gas occurs over the reduced viscosity region 3 > eta/etasub(c) > 0.6, which corresponds to the reduced density region 1.9 > eta/etasub(c) > 0.5. In the saturated gas etaμsub(+) is similar in all pentanes, but iso- approximately> n- > neo-pentane. At constant density dμsub(+)/dT >= 0 for gases. The average gas nμsub(+) is similar in all pentanes, but iso- approximately> n- > neo-pentane. At constant density dμsub(+)/dT >= 0 for gases. The average momentum transfer cross sections in the n-/neo-pentane mixtures are similar to those in neo-pentane at low T but similar to those in n-pentane at high T. The present findings are combined with previous electron mobility data in addressing the effect of hydrocarbon molecular (external) shape on the electric breakdown strength of gases

  3. Cationic Bolaamphiphiles for Gene Delivery

    Science.gov (United States)

    Tan, Amelia Li Min; Lim, Alisa Xue Ling; Zhu, Yiting; Yang, Yi Yan; Khan, Majad

    2014-05-01

    Advances in medical research have shed light on the genetic cause of many human diseases. Gene therapy is a promising approach which can be used to deliver therapeutic genes to treat genetic diseases at its most fundamental level. In general, nonviral vectors are preferred due to reduced risk of immune response, but they are also commonly associated with low transfection efficiency and high cytotoxicity. In contrast to viral vectors, nonviral vectors do not have a natural mechanism to overcome extra- and intracellular barriers when delivering the therapeutic gene into cell. Hence, its design has been increasingly complex to meet challenges faced in targeting of, penetration of and expression in a specific host cell in achieving more satisfactory transfection efficiency. Flexibility in design of the vector is desirable, to enable a careful and controlled manipulation of its properties and functions. This can be met by the use of bolaamphiphile, a special class of lipid. Unlike conventional lipids, bolaamphiphiles can form asymmetric complexes with the therapeutic gene. The advantage of having an asymmetric complex lies in the different purposes served by the interior and exterior of the complex. More effective gene encapsulation within the interior of the complex can be achieved without triggering greater aggregation of serum proteins with the exterior, potentially overcoming one of the great hurdles faced by conventional single-head cationic lipids. In this review, we will look into the physiochemical considerations as well as the biological aspects of a bolaamphiphile-based gene delivery system.

  4. Bioactive glasses and glass-ceramics

    Directory of Open Access Journals (Sweden)

    de Aza, P. N.

    2007-04-01

    Full Text Available Since the late 1960´s, a great interest in the use of bioceramic materials for biomedical applications has been developed. In a previous paper, the authors reviewed crystalline bioceramic materials “sensus stricto”, it is to say, those ceramic materials, constituted for non-metallic inorganic compounds, crystallines and consolidates by thermal treatment of powders at high temperature. In the present review, the authors deal with those called bioactive glasses and glassceramics. Although all of them are also obtained by thermal treatment at high temperature, the first are amorphous and the second are obtained by devitrification of a glass, although the vitreous phase normally prevails on the crystalline phases. After an introduction to the concept of bioactive materials, a short historical review of the bioactive glasses development is made. Its preparation, reactivity in physiological media, mechanism of bonding to living tissues and mechanical strength of the bone-implant interface is also reported. Next, the concept of glass-ceramic and the way of its preparation are exposed. The composition, physicochemical properties and biological behaviour of the principal types of bioactive glasses and glass-ceramic materials: Bioglass®, Ceravital®, Cerabone®, Ilmaplant® and Bioverit® are also reviewed. Finally, a short review on the bioactive-glass coatings and bioactive-composites and most common uses of bioactive-glasses and glass-ceramics are carried out too.

    Desde finales de los años sesenta, se ha despertado un gran interés por el uso de los materiales biocerámicos para aplicaciones biomédicas. En un trabajo previo, los autores hicieron una revisión de los denominados materiales biocerámicos cristalinos en sentido estricto, es decir, de aquellos materiales, constituidos por compuestos inorgánicos no metálicos, cristalinos y consolidados mediante tratamientos térmicos a altas temperaturas. En el presente trabajo, los autores

  5. A Picture behind Glass

    Directory of Open Access Journals (Sweden)

    Poprzęcka, Maria

    2010-04-01

    Full Text Available The paper considers the singular situation of reception occasioned by a painting shielded with a reflective pane of glass. The reflections in the glass dramatically break the cohesion of the painting and bring about distracting – although sometimes intriguing – surprises. The glass is an iconoclastic intrusion, an infection of the artistic order by an invading disorder and transient immediacy, which however can be very attractive visually. The accidental obliterates the significant. "The truth of art" is confronted here with a delusive phantom. Not only two entirely different visual effects are mixed here, but also different ontological and axiological spheres.

  6. Orbital glass in HTSC

    International Nuclear Information System (INIS)

    Kusmartsev, F.V.

    1992-10-01

    The physical reasons why the orbital glass may exist in granular high-temperature superconductors and the existing experimental data appeared recently are discussed. The orbital glass is characterized by the coexistence of the orbital paramagnetic state with the superconducting state and occurs at small magnetic fields H c0 c1 . The transition in orbital glass arises at the critical field H c0 which is inversely proportional to the surface cross-area S of an average grain. In connection with theoretical predictions the possible experiments are proposed. (author). 10 refs

  7. Spin glasses (II)

    International Nuclear Information System (INIS)

    Fischer, K.H.

    1985-01-01

    Experimental results of spin glass studies are reviewed and related to existing theories. Investigations of spin glasses are concentrated on atomic structure, metallurgical treatment, and high-temperature susceptibility of alloys, on magnetic properties at low temperature and near the freezing temperature, on anisotropy behaviour measured by ESR, NMR and torque, on specific heat, Moessbauer effect, neutron scattering and muon-spin depolarization experiments, ultrasound and transport properties. Some new theories of spin glasses are discussed which have been developed since Part I appeared

  8. Synthesis, activity, and structure--activity relationship studies of novel cationic lipids for DNA transfer.

    Science.gov (United States)

    Byk, G; Dubertret, C; Escriou, V; Frederic, M; Jaslin, G; Rangara, R; Pitard, B; Crouzet, J; Wils, P; Schwartz, B; Scherman, D

    1998-01-15

    We have designed and synthesized original cationic lipids for gene delivery. A synthetic method on solid support allowed easy access to unsymmetrically monofunctionalized polyamine building blocks of variable geometries. These polyamine building blocks were introduced into cationic lipids. To optimize the transfection efficiency in the novel series, we have carried out structure-activity relationship studies by introduction of variable-length lipids, of variable-length linkers between lipid and cationic moiety, and of substituted linkers. We introduce the concept of using the linkers within cationic lipids molecules as carriers of side groups harboring various functionalities (side chain entity), as assessed by the introduction of a library composed of cationic entities, additional lipid chains, targeting groups, and finally the molecular probes rhodamine and biotin for cellular traffic studies. The transfection activity of the products was assayed in vitro on Hela carcinoma, on NIH3T3, and on CV1 fibroblasts and in vivo on the Lewis Lung carcinoma model. Products from the series displayed high transfection activities. Results indicated that the introduction of a targeting side chain moiety into the cationic lipid is permitted. A primary physicochemical characterization of the DNA/lipid complexes was demonstrated with this leading compound. Selected products from the series are currently being developed for preclinical studies, and the labeled lipopolyamines can be used to study the intracellular traffic of DNA/cationic lipid complexes.

  9. Fun with Singing Wine Glasses

    Science.gov (United States)

    Boone, Christine; Galloway, Melodie; Ruiz, Michael J.

    2018-01-01

    A fun activity is presented using singing wine glasses for introductory physics students. Students tune a white wine glass and a red wine glass to as many semitones as possible by filling the glasses with the appropriate amounts of water. A smart phone app is used to measure the frequencies of equal-temperament tones. Then plots of frequency…

  10. Glass Stronger than Steel

    Science.gov (United States)

    Yarris, Lynn

    2011-03-28

    A new type of damage-tolerant metallic glass, demonstrating a strength and toughness beyond that of steel or any other known material, has been developed and tested by a collaboration of researchers from Berkeley Lab and Caltech.

  11. Mechanically reinforced glass beams

    DEFF Research Database (Denmark)

    Nielsen, Jens Henrik; Olesen, John Forbes

    2007-01-01

    The use of glass as a load carrying material in structural elements is rarely seen even though glass is a popular material for many architects. This is owed to the unreliable and low tensile strength, which is due to surface flaws and high brittleness of the material. These properties lead...... to breakage without any warning or ductility, which can be catastrophic if no precautions are taken. One aspect of this issue is treated here by looking at the possibility of mechanically reinforcing glass beams in order to obtain ductile failure for such a structural component. A mechanically reinforced...... presented. The experiments show that it is possible to obtain a very ductile structural behavior using the right amount of reinforcement. A Finite Element Model including - in a simple manner - the effects of cracking of glass is presented. Based on a comparison between experimental and model results...

  12. Waste glass weathering

    International Nuclear Information System (INIS)

    Bates, J.K.; Buck, E.C.

    1994-01-01

    The weathering of glass is reviewed by examining processes that affect the reaction of commercial, historical, natural, and nuclear waste glass under conditions of contact with humid air and slowly dripping water, which may lead to immersion in nearly static solution. Radionuclide release data from weathered glass under conditions that may exist in an unsaturated environment are presented and compared to release under standard leaching conditions. While the comparison between the release under weathering and leaching conditions is not exact, due to variability of reaction in humid air, evidence is presented of radionuclide release under a variety of conditions. These results suggest that both the amount and form of radionuclide release can be affected by the weathering of glass

  13. Phosphate glasses, containing nitrogen

    International Nuclear Information System (INIS)

    Lisitsyna, E.A.; Khalilev, V.D.; Koryavin, A.A.; Goncharova, L.N.

    1987-01-01

    Possibilities of nitrogen-containing glass synthesis by the introduction into the charge of ammonium salts, as well as aluminium nitride, are studied. Zinc alumoyttrium phosphate glass (mol. %) Zn(PO 3 ) 2 - 4O, Al(PO 3 ) 3 - 3O, Y(PO 3 ) 3 -3O is suggested as a matrix. It is shown that the effect of amide and imide groups on the properties of the glass is less noticeable than the effect of nitride groups. Direct introduction of nitride constituent was realized using AlN, but aluminium introduction was taken into account so that the oxide was subtracted. The attempt to introduce more than 2.5 mass % of nitrogen into initial matrix by aluminium nitride has failed due to repeated restoration of glass with amorphous phosphorus isolation

  14. Molecular dynamics study of a nuclear waste glass matrix with plutonium

    International Nuclear Information System (INIS)

    Meis, C.; Delaye, J.M.; Ghaleb, D.

    1999-01-01

    Molecular dynamics simulation techniques were applied to model the incorporation of plutonium in the French nuclear waste glass matrix. Born-Mayer-Huggins analytical potentials were established to characterize short-range interactions between Pu-O and Pu-Pu pairs; the potentials were fitted to the structural properties of plutonium dioxide in the light of a recent experimental study showing that plutonium is found as Pu(IV) in the glass. The transferability of the established potentials to the glass structure is discussed, and the potential parameters are further refined by molecular dynamics simulations in an aluminoborosilicate glass to obtain mean Pu-O interatomic distances and first-neighbor coordination numbers matching the experimental values as closely as possible. Previously published Born-Mayer-Huggins potentials supplemented by Stillinger-Weber three-body terms were used for oxygen-cation and cation-cation interactions. The difficulties encountered in establishing a Pu-O potential that provides satisfactory results in both oxides and glasses are also discussed

  15. Spectrophotometric studies on cation-cation interactions between Np(V) and Th(IV) cations in nitric acid medium

    International Nuclear Information System (INIS)

    Verma, P.K.; Pathak, P.N.; Bhattacharyya, A.; Prabhu, D.R.; Mohapatra, P.K.

    2014-01-01

    The higher-valent actinide cations exhibit fascinating coordination chemistry essentially due to the flexibility in their electronic structures. This is particularly applicable for the dioxo penta- and hexavalent lighter actinides such as U, Np, Pu, and Am. Even though the oxo moiety is assumed to be chemically inert in these cations, there are several studies which show that pentavalent Np cation (NpO 2 + ) displays a tendency of bonding with charged metal ions. This class of weak bond formation has been classified as cation-cation interactions (CCI). Initial studies suggested that these types of interactions of Np(V) with polyvalent metal ions are more probable in non complexing perchloric acid solutions. Majority of these studies have been performed in perchlorate media and the stability constant values have been calculated. On the other hand, these studies in nitric acid medium are rather few. Our recent spectrophotometric study has shown that Np(V) cation undergoes disproportionation reaction and the tendency for CCI becomes less favorable at elevated temperature in nitric acid media. This study has been extended for understanding possible CCI between Np(V)O 2 + and Th 4 + ions under varying conditions such as nitric acid (1-6 M HNO 3 ). Th concentration (up to 0.86 M), and temperature (293-343K). An attempt has been made to calculate the stability constant values and compare with those reported in other media

  16. High-Intensity Plasma Glass Melter Final Technical Report

    Energy Technology Data Exchange (ETDEWEB)

    Gonterman, J. Ronald; Weinstein, Michael A.

    2006-10-27

    The purpose of this project was to demonstrate the energy efficiency and reduced emissions that can be obtained with a dual torch DC plasma transferred arc-melting system. Plasmelt Glass Technologies, LLC was formed to solicit and execute the project, which utilize a full-scale test melter system. The system is similar to the one that was originally constructed by Johns Manville, but Plasmelt has added significant improvements to the torch design and melter system that has extended the original JM short torch lives. The original JM design has been shown to achieve melt rates 5 to 10 times faster than conventional gas or electric melting, with improved energy efficiency and reduced emissions. This project began on 7/28/2003 and ended 7/27/06. A laboratory scale melter was designed, constructed, and operated to conduct multiple experimental melting trials on various glass compositions. Glass quality was assessed. Although the melter design is generic and equally applicable to all sectors within the glass industry, the development of this melter has focused primarily on fiberglass with additional exploratory melting trials of frits, specialty, and minerals-melting applications. Throughput, energy efficiency, and glass quality have been shown to be heavily dependent on the selected glass composition. During this project, Plasmelt completed the proof-of-concept work in our Boulder, CO Lab to show the technical feasibility of this transferred-arc plasma melter. Late in the project, the work was focused on developing the processes and evaluating the economic viability of plasma melting aimed at the specific glasses of interest to specific client companies. Post project work is on going with client companies to address broader non-glass materials such as refractories and industrial minerals. Exploratory melting trials have been conducted on several glasses of commercial interest including: C-glass, E-glass, S-Glass, AR-Glass, B-glass, Lighting Glass, NE-Glass, and various

  17. Catalytic oligomerization of ethylene to higher linear alpha-olefins promoted by the cationic group 4 [(eta 5-Cp-(CMe2-bridge)-Ph)MII(ethylene)2]+ (M = Ti, Zr, Hf) active catalysts: a density functional investigation of the influence of the metal on the catalytic activity and selectivity.

    Science.gov (United States)

    Tobisch, Sven; Ziegler, Tom

    2004-07-28

    A detailed theoretical analysis is presented of the catalytic abilities of heavier group 4 (M = Zr, Hf) metals for linear ethylene oligomerization with the cationic [(eta(5)-C(5)H(4)-(CMe(2)-bridge)-C(6)H(5))M(IV)(CH(3))(2)](+) complex as precatalyst, employing a gradient-corrected DFT method. The parent Ti system has been reported as a highly selective catalyst for ethylene trimerization. The mechanism involving metallacycle intermediates, originally proposed by Briggs and Jolly, has been supported by the present study to be operative for the investigated class of group 4 catalysts. Metallacycle growth through bimolecular ethylene uptake and subsequent insertion is likely to occur at uniform rates for larger cycles that are furthermore comparable for Ti, Zr, and Hf catalysts. Ethylene insertion into the two smallest five- and seven-membered cycles is found to become accelerated for Zr and Hf catalysts, which is due to geometrical factors. In contrast, electronic effects act to raise the barrier for metallacycle decomposition, affording alpha-olefins upon descending group 4. This process is furthermore predicted to be kinetically more difficult for larger metallacycles. The oligomer distribution of the Zr-mediated reaction is likely to comprise predominantly 1-hexene together with 1-octene, while 1-butene and alpha-olefins of chain lengths C(10)-C(18) should occur only in negligible portions. A similar composition of alpha-olefins having C(6)-C(18) chain lengths is indicated for the Hf catalysts, but with long-chain oligomers and polymers as the prevalent fraction. Between the group 4 catalysts of the investigated type, the Zr system appears as the most promising candidate having catalytic potential for production of 1-octene, although not selectively. The influence of temperature to modulate the oligomer product composition has been evaluated.

  18. Cationization of heparin for film applications

    Czech Academy of Sciences Publication Activity Database

    Šimkovic, I.; Mendichi, R.; Kelnar, Ivan; Filip, J.; Hricovíni, M.

    2015-01-01

    Roč. 115, 22 January (2015), s. 551-558 ISSN 0144-8617 Institutional support: RVO:61389013 Keywords : heparin * cationization * NMR Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.219, year: 2015

  19. Wastes based glasses and glass-ceramics

    Directory of Open Access Journals (Sweden)

    Barbieri, L.

    2001-12-01

    Full Text Available Actually, the inertization, recovery and valorisation of the wastes coming from municipal and industrial processes are the most important goals from the environmental and economical point of view. An alternative technology capable to overcome the problem of the dishomogeneity of the raw material chemical composition is the vitrification process that is able to increase the homogeneity and the constancy of the chemical composition of the system and to modulate the properties in order to address the reutilization of the waste. Moreover, the glasses obtained subjected to different controlled thermal treatments, can be transformed in semy-cristalline material (named glass-ceramics with improved properties with respect to the parent amorphous materials. In this review the tailoring, preparation and characterization of glasses and glass-ceramics obtained starting from municipal incinerator grate ash, coal and steel fly ashes and glass cullet are described.

    Realmente la inertización, recuperación y valorización de residuos que proceden de los procesos de incineración de residuos municipales y de residuos industriales son metas importantes desde el punto de vista ambiental y económico. Una tecnología alternativa capaz de superar el problema de la heterogeneidad de la composición química de los materiales de partida es el proceso de la vitrificación que es capaz de aumentar la homogeneidad y la constancia de la composición química del sistema y modular las propiedades a fin de la reutilización del residuo. En este artículo se presentan los resultados de vitrificación en que los vidrios fueron sometidos a tratamientos térmicos controlados diferentes, de manera que se transforman en materiales semicristalinos (también denominados vitrocerámicos con mejores propiedades respecto a los materiales amorfos originales. En esta revisión se muestra el diseño, preparación y caracterización de vidrios y vitrocerámicos partiendo de

  20. Test procedure for cation exchange chromatography

    International Nuclear Information System (INIS)

    Cooper, T.D.

    1994-01-01

    The purpose of this test plan is to demonstrate the synthesis of inorganic antimonate ion exchangers and compare their performance against the standard organic cation exchangers. Of particular interest is the degradation rate of both inorganic and organic cation exchangers. This degradation rate will be tracked by determining the ion exchange capacity and thermal stability as a function of time, radiation dose, and chemical reaction

  1. Cationic surfactants as the hydrolytic micellar catalysts

    OpenAIRE

    Janošcová, Petra

    2013-01-01

    Cationic surfactants as the hydrolytic micellar catalysts Petra Janošcová The effectiveness of hydrolytic cleavage of the pesticide fenitrothionin cationic surfactants micellar media has been tested. All used surfactants increased the rate of fenitrothionhydrolysis, which was the evidence of micellar catalysis. For some surfactants decreases has been evident at the highest rate of hydrolysis concentrations. It has been the result of a phenomenon called the effect of empty micelles. High hydro...

  2. Asymmetric Aminalization via Cation-Binding Catalysis

    DEFF Research Database (Denmark)

    Park, Sang Yeon; Liu, Yidong; Oh, Joong Suk

    2018-01-01

    Asymmetric cation-binding catalysis, in principle, can generate "chiral" anionic nucleophiles, where the counter cations are coordinated within chiral environments. Nitrogen-nucleophiles are intrinsically basic, therefore, its use as nucleophiles is often challenging and limiting the scope...... of the reaction. Particularly, a formation of configurationally labile aminal centers with alkyl substituents has been a formidable challenge due to the enamine/imine equilibrium of electrophilic substrates. Herein, we report enantioselective nucleophilic addition reactions of potassium phthalimides to Boc-protected...

  3. Cycloaliphatic epoxide resins for cationic UV - cure

    International Nuclear Information System (INIS)

    Verschueren, K.; Balwant Kaur

    1999-01-01

    This paper introduces the cyclo - aliphatic epoxide resins used for the various applications of radiation curing and their comparison with acrylate chemistry. Radiation curable coatings and inks are pre - dominantly based on acrylate chemistry but over the last few years, cationic chemistry has emerged successfully with the unique properties inherent with cyclo - aliphatic epoxide ring structures. Wide variety of cationic resins and diluents, the formulation techniques to achieve the desired properties greatly contributes to the advancement of UV - curing technology

  4. Glass microsphere lubrication

    Science.gov (United States)

    Geiger, Michelle; Goode, Henry; Ohanlon, Sean; Pieloch, Stuart; Sorrells, Cindy; Willette, Chris

    1991-01-01

    The harsh lunar environment eliminated the consideration of most lubricants used on earth. Considering that the majority of the surface of the moon consists of sand, the elements that make up this mixture were analyzed. According to previous space missions, a large portion of the moon's surface is made up of fine grained crystalline rock, about 0.02 to 0.05 mm in size. These fine grained particles can be divided into four groups: lunar rock fragments, glasses, agglutinates (rock particles, crystals, or glasses), and fragments of meteorite material (rare). Analysis of the soil obtained from the missions has given chemical compositions of its materials. It is about 53 to 63 percent oxygen, 16 to 22 percent silicon, 10 to 16 percent sulfur, 5 to 9 percent aluminum, and has lesser amounts of magnesium, carbon, and sodium. To be self-supporting, the lubricant must utilize one or more of the above elements. Considering that the element must be easy to extract and readily manipulated, silicon or glass was the most logical choice. Being a ceramic, glass has a high strength and excellent resistance to temperature. The glass would also not contaminate the environment as it comes directly from it. If sand entered a bearing lubricated with grease, the lubricant would eventually fail and the shaft would bind, causing damage to the system. In a bearing lubricated with a solid glass lubricant, sand would be ground up and have little effect on the system. The next issue was what shape to form the glass in. Solid glass spheres was the only logical choice. The strength of the glass and its endurance would be optimal in this form. To behave as an effective lubricant, the diameter of the spheres would have to be very small, on the order of hundreds of microns or less. This would allow smaller clearances between the bearing and the shaft, and less material would be needed. The production of glass microspheres was divided into two parts, production and sorting. Production includes the

  5. Potentiometric anion selective sensors

    NARCIS (Netherlands)

    Antonisse, M.M.G.; Reinhoudt, David

    1999-01-01

    In comparison with selective receptors (and sensors) for cationic species, work on the selective complexation and detection of anions is of more recent date. There are three important components for a sensor, a transducer element, a membrane material that separates the transducer element and the

  6. Cationized Carbohydrate Gas-Phase Fragmentation Chemistry

    Science.gov (United States)

    Bythell, Benjamin J.; Abutokaikah, Maha T.; Wagoner, Ashley R.; Guan, Shanshan; Rabus, Jordan M.

    2017-04-01

    We investigate the fragmentation chemistry of cationized carbohydrates using a combination of tandem mass spectrometry, regioselective labeling, and computational methods. Our model system is D-lactose. Barriers to the fundamental glyosidic bond cleavage reactions, neutral loss pathways, and structurally informative cross-ring cleavages are investigated. The most energetically favorable conformations of cationized D-lactose were found to be similar. In agreement with the literature, larger group I cations result in structures with increased cation coordination number which require greater collision energy to dissociate. In contrast with earlier proposals, the B n -Y m fragmentation pathways of both protonated and sodium-cationized analytes proceed via protonation of the glycosidic oxygen with concerted glycosidic bond cleavage. Additionally, for the sodiated congeners our calculations support sodiated 1,6-anhydrogalactose B n ion structures, unlike the preceding literature. This affects the subsequent propensity of formation and prediction of B n /Y m branching ratio. The nature of the anomeric center (α/β) affects the relative energies of these processes, but not the overall ranking. Low-energy cross-ring cleavages are observed for the metal-cationized analytes with a retro-aldol mechanism producing the 0,2 A 2 ion from the sodiated forms . Theory and experiment support the importance of consecutive fragmentation processes, particularly for the protonated congeners at higher collision energies.

  7. Luminescent sulfides of monovalent and trivalent cations

    International Nuclear Information System (INIS)

    1975-01-01

    The invention discloses a family of luminescent materials or phosphors having a rhombohedral crystal structure and consisting essentially of a mixed host sulfide of at least one monovalent host cation and at least one trivalent host cation, and containing, for each mole of phosphor, 0.0005 to 0.05 mole of at least one activating cation. The monovalent host cations may be Na, K or Rb and Cs. The trivalent host cations may be Gd, La, Lu, Sc and Y. The activating cations may be one or more of trivalent As, Bi, Ce, Dy, Er, Pr, Sb, Sm, Tb and Tm; divalent Lu, Mn, Pb and Sn; and monovalent Ag, Cu and Tl. The novel phosphors may be used in devices to convert electron-beam, ultraviolet or x-ray energy to light in the visible spectrum. Such energy conversion can be employed for example in fluoroscopic screens, and in viewing screens of cathode-ray tubes and other electron tubes

  8. DWPF GLASS BEADS AND GLASS FRIT TRANSPORT DEMONSTRATION

    Energy Technology Data Exchange (ETDEWEB)

    Adamson, D; Bradley Pickenheim, B

    2008-11-24

    DWPF is considering replacing irregularly shaped glass frit with spherical glass beads in the Slurry Mix Evaporator (SME) process to decrease the yield stress of the melter feed (a non-Newtonian Bingham Plastic). Pilot-scale testing was conducted on spherical glass beads and glass frit to determine how well the glass beads would transfer when compared to the glass frit. Process Engineering Development designed and constructed the test apparatus to aid in the understanding and impacts that spherical glass beads may have on the existing DWPF Frit Transfer System. Testing was conducted to determine if the lines would plug with the glass beads and the glass frit slurry and what is required to unplug the lines. The flow loop consisted of vertical and horizontal runs of clear PVC piping, similar in geometry to the existing system. Two different batches of glass slurry were tested: a batch of 50 wt% spherical glass beads and a batch of 50 wt% glass frit in process water. No chemicals such as formic acid was used in slurry, only water and glass formers. The glass beads used for this testing were commercially available borosilicate glass of mesh size -100+200. The glass frit was Frit 418 obtained from DWPF and is nominally -45+200 mesh. The spherical glass beads did not have a negative impact on the frit transfer system. The transferring of the spherical glass beads was much easier than the glass frit. It was difficult to create a plug with glass bead slurry in the pilot transfer system. When a small plug occurred from setting overnight with the spherical glass beads, the plug was easy to displace using only the pump. In the case of creating a man made plug in a vertical line, by filling the line with spherical glass beads and allowing the slurry to settle for days, the plug was easy to remove by using flush water. The glass frit proved to be much more difficult to transfer when compared to the spherical glass beads. The glass frit impacted the transfer system to the point

  9. DWPF GLASS BEADS AND GLASS FRIT TRANSPORT DEMONSTRATION

    International Nuclear Information System (INIS)

    Adamson, D.; Pickenheim, Bradley

    2008-01-01

    DWPF is considering replacing irregularly shaped glass frit with spherical glass beads in the Slurry Mix Evaporator (SME) process to decrease the yield stress of the melter feed (a non-Newtonian Bingham Plastic). Pilot-scale testing was conducted on spherical glass beads and glass frit to determine how well the glass beads would transfer when compared to the glass frit. Process Engineering Development designed and constructed the test apparatus to aid in the understanding and impacts that spherical glass beads may have on the existing DWPF Frit Transfer System. Testing was conducted to determine if the lines would plug with the glass beads and the glass frit slurry and what is required to unplug the lines. The flow loop consisted of vertical and horizontal runs of clear PVC piping, similar in geometry to the existing system. Two different batches of glass slurry were tested: a batch of 50 wt% spherical glass beads and a batch of 50 wt% glass frit in process water. No chemicals such as formic acid was used in slurry, only water and glass formers. The glass beads used for this testing were commercially available borosilicate glass of mesh size -100+200. The glass frit was Frit 418 obtained from DWPF and is nominally -45+200 mesh. The spherical glass beads did not have a negative impact on the frit transfer system. The transferring of the spherical glass beads was much easier than the glass frit. It was difficult to create a plug with glass bead slurry in the pilot transfer system. When a small plug occurred from setting overnight with the spherical glass beads, the plug was easy to displace using only the pump. In the case of creating a man made plug in a vertical line, by filling the line with spherical glass beads and allowing the slurry to settle for days, the plug was easy to remove by using flush water. The glass frit proved to be much more difficult to transfer when compared to the spherical glass beads. The glass frit impacted the transfer system to the point

  10. Thermal conductivity of glass copper-composite

    International Nuclear Information System (INIS)

    Kinoshita, Makoto; Terai, Ryohei; Haidai, Haruki

    1980-01-01

    Glass-metal composites are to be one of the answers for promoting thermal conduction in the glassy solids containing high-level radioactive wastes. In order to investigate the effect of metal addition on thermal conductivity of glasses, glass-copper composites were selected, and the conductivities of the composites were measured and discussed in regards to copper content and microstructure. Fully densified composites were successfully prepared by pressure sintering of the powder mixtures of glass and copper at temperatures above the yield points of the constituent glasses if the copper content was not so much. The conductivity was measured by means of a comparative method, in which the thermal gradient of the specimen was compared with that of quartz glass as standard under thermally steady state. Measurements were carried out at around 50 0 C. The thermal conductivity increased with increasing content of copper depending on the kind of copper powder used. The conductivities of the composites of the same copper content differed considerably each another. Fine copper powder was effective on increasing conductivity, and the conductivity became about threefold of that of glass by mixing the fine copper powder about 10 vol%. For the composites containing the fine copper powder less than 5 vol%, the conductivity obeyed so-called logarithmic rule, one of the mixture rules of conductivity, whereas for composites containing more than 5 vol%, the conductivity remarkably increased apart from the rule. This fact suggests that copper becomes continuous in the composite when the copper content increased beyond 5 vol%. For the composites containing coarse copper powder, the conductivity was increased not significantly, and obeyed an equation derived from the model in which conductive material dispersed in less conductive one. (author)

  11. Network topology for the formation of solvated electrons in binary CaO-Al2O3 composition glasses.

    Science.gov (United States)

    Akola, Jaakko; Kohara, Shinji; Ohara, Koji; Fujiwara, Akihiko; Watanabe, Yasuhiro; Masuno, Atsunobu; Usuki, Takeshi; Kubo, Takashi; Nakahira, Atsushi; Nitta, Kiyofumi; Uruga, Tomoya; Weber, J K Richard; Benmore, Chris J

    2013-06-18

    Glass formation in the CaO-Al2O3 system represents an important phenomenon because it does not contain typical network-forming cations. We have produced structural models of CaO-Al2O3 glasses using combined density functional theory-reverse Monte Carlo simulations and obtained structures that reproduce experiments (X-ray and neutron diffraction, extended X-ray absorption fine structure) and result in cohesive energies close to the crystalline ground states. The O-Ca and O-Al coordination numbers are similar in the eutectic 64 mol % CaO (64CaO) glass [comparable to 12CaO·7Al2O3 (C12A7)], and the glass structure comprises a topologically disordered cage network with large-sized rings. This topologically disordered network is the signature of the high glass-forming ability of 64CaO glass and high viscosity in the melt. Analysis of the electronic structure reveals that the atomic charges for Al are comparable to those for Ca, and the bond strength of Al-O is stronger than that of Ca-O, indicating that oxygen is more weakly bound by cations in CaO-rich glass. The analysis shows that the lowest unoccupied molecular orbitals occurs in cavity sites, suggesting that the C12A7 electride glass [Kim SW, Shimoyama T, Hosono H (2011) Science 333(6038):71-74] synthesized from a strongly reduced high-temperature melt can host solvated electrons and bipolarons. Calculations of 64CaO glass structures with few subtracted oxygen atoms (additional electrons) confirm this observation. The comparable atomic charges and coordination of the cations promote more efficient elemental mixing, and this is the origin of the extended cage structure and hosted solvated (trapped) electrons in the C12A7 glass.

  12. Gd3+ and calcium sensitive, sodium leak currents are features of weak membrane-glass seals in patch clamp recordings.

    Directory of Open Access Journals (Sweden)

    Adrienne N Boone

    Full Text Available The properties of leaky patch currents in whole cell recording of HEK-293T cells were examined as a means to separate these control currents from expressed sodium and calcium leak channel currents from snail NALCN leak channels possessing both sodium (EKEE and calcium (EEEE selectivity filters. Leak currents were generated by the weakening of gigaohm patch seals by artificial membrane rupture using the ZAP function on the patch clamp amplifier. Surprisingly, we found that leak currents generated from the weakened membrane/glass seal can be surprisingly stable and exhibit behavior that is consistent with a sodium leak current derived from an expressible channel. Leaky patch currents differing by 10 fold in size were similarly reduced in size when external sodium ions were replaced with the large monovalent ion NMDG+. Leaky patch currents increased when external Ca2+ (1.2 mM was lowered to 0.1 mM and were inhibited (>40% to >90% with 10 µM Gd3+, 100 µM La3+, 1 mM Co2+ or 1 mM Cd2+. Leaky patch currents were relatively insensitive (<30% to 1 mM Ni2+ and exhibited a variable amount of block with 1 mM verapamil and were insensitive to 100 µM mibefradil or 100 µM nifedipine. We hypothesize that the rapid changes in leak current size in response to changing external cations or drugs relates to their influences on the membrane seal adherence and the electro-osmotic flow of mobile cations channeling in crevices of a particular pore size in the interface between the negatively charged patch electrode and the lipid membrane. Observed sodium leak conductance currents in weak patch seals are reproducible between the electrode glass interface with cell membranes, artificial lipid or Sylgard rubber.

  13. Silicate glasses corrosion. Texture analysis of the corrosion layer

    International Nuclear Information System (INIS)

    Portal, Sabine

    2001-01-01

    We have studied the kinetic and the texture evolution of the corroded layer that forms on glass surfaces exposed to acidic solutions. The corroded layer is depleted in alkali cations and is produced by an ion exchange mechanism. It is porous and shows a lower refractive index than the one of the bulk glass. Spectroscopic ellipsometry allows determining the thickness of the layer and its refractive index. Several other techniques have been developed for characterizing the corrosion behaviour of glass surfaces: porosity is thus investigated by adsorption-desorption of nitrogen; the thickness and the composition of the layer are studied by secondary ion mass spectroscopy (S.I.M.S.); sodium concentration in the solution has been analyzed by atomic absorption. This study shows the importance of leaching conditions and glass preparation. The type of drying employed is susceptible to modify the texture and the structure of the layer. The layers produced in the early stages of the leaching process are not easily detectable. The different results lead however to the same conclusion: after a strong increase of porosity, a densification of the layer is observed with increasing time. The evolution of the layer texture could therefore modify the kinetic of the glass corrosion. (author) [fr

  14. Formation and decay of the methylviologen radical cation in the solid phase

    Science.gov (United States)

    Wolszczak, M.; Stradowski, Cz.

    Absorption and emission spectra of the methylviologen (MV 2+)/ tris (2,2'-bipyridine) ruthenium(II)[Ru(bpy) 2+3 system in a variety of solid systems—ethylene glycol-water glass, polymer foil, cellulose, and wool—have been studied at 4.2, 77, and 298 K. It was found that MV 2+ always quenches the luminescence of ∗ Ru(bpy)2+3. However, the MV +. radical cation, which is generated at 298 K as a result of a quenching process, is not generated at 77 and 4.2 K. Lowering of the temperature probably prevents the diffusion of electron donor to the oxidized form of photosensitizer and enables instantaneous back reaction. The formation of the MV +. radical cation under the influence of light λ > 300 nm at low and ambient temperatures has been studied. The crucial role of water in the oxidation of MV +. was confirmed in a pulse radiolysis experiment.

  15. Reduction-induced inward diffusion and crystal growth on the surfaces of iron-bearing silicate glasses

    DEFF Research Database (Denmark)

    Liu, S.J.; Tao, H.Z.; Zhang, Y.F.

    2015-01-01

    We investigate the sodium inward diffusion (i.e., sodium diffusion from surface toward interior) in iron containing alkaline earth silicate glasses under reducing conditions around Tg and the induced surface crystallization. The surface crystallization is caused by formation of a silicate-gel layer...... first and then the growth of silica crystals on the glass surface. The type of alkaline earth cations has a strong impact on both the glass transition and the surface crystallization. In the Mg-containing glass, a quartz layer forms on the glass surface. This could be attributed to the fact that Mg2......+ ions have stronger bonds to oxygen and lower coordination number (4~5) than Ca2+, Sr2+ and Ba2+ ions. In contrast, a cristobalite layer forms in Ca-, Sr- and Ba-containing glasses....

  16. Optical glass: standards - present state and outlook

    Science.gov (United States)

    Hartmann, Peter

    2015-10-01

    In 1996, the international organization for standardization ISO started the standards series ISO 10110 specifying indications in drawings of optical elements. Three parts cover material properties: part 2 (stress birefringence), 3 (bubbles and inclusions), and 4 (inhomogeneity and striae). Customers used to just send optical element drawings to glass manufacturers often leading to uncertainty, overspecification, and delivery problems. The raw glass standard ISO 12123 of 2010 allows direct addressing of raw glass specifications. Harmonizing ISO 10110 with ISO 12123 and progress in inspection methods require updating of the material specifying parts. A new part 18 containing all properties is under preparation and is meant to replace parts 2-4. ISO 12123 will be amended by introducing definitions for relative partial dispersions and reference normal lines and grade denominations for tolerance ranges. The working draft ISO/WD 10110 part 18 extends indication possibilities to allow relating to ISO 12123 while ensuring backward compatibility. Default optical glass quality and direct specification of raw glass simplify tolerancing considerably. Annexes support selection of appropriate quality classes referring to optical element size categories. Test and inspection standards on chemical resistances, hardness, stress birefringence, and optical homogeneity will be maintained. Standards for water resistance, refractive index, and striae inspection are being prepared.

  17. Alkaline glass as induced fission fragment detectors

    International Nuclear Information System (INIS)

    Amorim, A.M.M.

    1986-01-01

    The slide glass, registered trade marks INLAB, INVICT and PERFECTA were compared. For the three kinds of glasses the following studies were done: chemical composition; general dissolution rate for hydrofluoric acid solutions of concentrations between 1 and 10M, at 30 0 C and ultrasound shaking; relative efficiency for recording fission fragment tracks from 252 Cf. The INLAB glass was selected due to the better quality of its surface after chemical etching. The HF concentration 2.5M was determined for chemical etching of INLAB glass, and the optimum etching time was chosen between 8 and 10 minutes. The thermal attenuation of latent tracks in the environmental temperature was observed for intervals uo to 31 days between the detector exposure to the fission fragment source and etching of tracks. Several methods were used for determining the detector parameters, such as: critical angle, angle of the cone and efficiency of etching. The effects of gamma irradiation from 60 Co and reactor neutrons in material properties as track detector were studied. Attenuation of latent tracks and saturation of color centers were observed for doses over 100M Rad. Since this kind of material contains uranium as impurity, uniformely distributed, slide glass were calibrated to be applied as a monitor of thermal neutron flux in nuclear reactor. (Author) [pt

  18. Interaction of ethidium and tetraphenylphosphonium cations with Salmonella enterica cells

    Directory of Open Access Journals (Sweden)

    Valeryia Mikalayeva

    2017-01-01

    Conclusions: Results of our experiments indicate that ionic strength of the incubation medium influence the selectivity, the medium temperature and the assay conditions impact the kinetics of efflux. The lower accumulated amount and the weaker fluorescence of Et+ registered in slightly acidic medium indicate that ΔΨ plays a role in the accumulation of this indicator cation. The bound amount of Et+ to the de-energized or permeabilized cells considerably varies depending on the conditions and methods of de-energization or permeabilization of cells. Tris/EDTA permeabilization of the cells does not inhibit the efflux.

  19. Electrical properties of phosphate glasses

    International Nuclear Information System (INIS)

    Mogus-Milankovic, A; Santic, A; Reis, S T; Day, D E

    2009-01-01

    Investigation of the electrical properties of phosphate glasses where transition metal oxide such as iron oxide is the network former and network modifier is presented. Phosphate glasses containing iron are electronically conducting glasses where the polaronic conduction is due to the electron hopping from low to high iron valence state. The identification of structural defects caused by ion/polaron migration, the analysis of dipolar states and electrical conductivity in iron phosphate glasses containing various alkali and mixed alkali ions was performed on the basis of the impedance spectroscopy (IS). The changes in electrical conductivity from as-quenched phosphate glass to fully crystallized glass (glass-ceramics) by IS are analyzed. A change in the characteristic features of IS follows the changes in glass and crystallized glass network. Using IS, the contribution of glass matrix, crystallized grains and grain boundary to the total electrical conductivity for iron phosphate glasses was analyzed. It was shown that decrease in conductivity is caused by discontinuities in the conduction pathways as a result of the disruption of crystalline network where two or more crystalline phases are formed. Also, phosphate-based glasses offer a unique range of biomaterials, as they form direct chemical bonding with hard/soft tissue. The surface charges of bioactive glasses are recognized to be the most important factors in determining biological responses. The improved bioactivity of the bioactive glasses as a result of the effects of the surface charges generated by electrical polarization is discussed.

  20. Cation Exchange in the Presence of Oil in Porous Media

    NARCIS (Netherlands)

    Farajzadeh, R.; Guo, H.; van Winden, J.L.; Bruining, J.

    2017-01-01

    Cation exchange is an interfacial process during which cations on a clay surface are replaced by other cations. This study investigates the effect of oil type and composition on cation exchange on rock surfaces, relevant for a variety of oil-recovery processes. We perform experiments in which brine

  1. Glass matrix armor

    Science.gov (United States)

    Calkins, Noel C.

    1991-01-01

    An armor system which utilizes glass. A plurality of constraint cells are mounted on a surface of a substrate, which is metal armor plate or a similar tough material, such that the cells almost completely cover the surface of the substrate. Each constraint cell has a projectile-receiving wall parallel to the substrate surface and has sides which are perpendicular to and surround the perimeter of the receiving wall. The cells are mounted such that, in one embodiment, the substrate surface serves as a sixth side or closure for each cell. Each cell has inside of it a plate, termed the front plate, which is parallel to and in contact with substantially all of the inside surface of the receiving wall. The balance of each cell is completely filled with a projectile-abrading material consisting of glass and a ceramic material and, in certain embodiments, a polymeric material. The glass may be in monolithic form or particles of ceramic may be dispersed in a glass matrix. The ceramic material may be in monolithic form or may be in the form of particles dispersed in glass or dispersed in said polymer.

  2. Sol-Gel Glasses

    Science.gov (United States)

    Mukherjee, S. P.

    1985-01-01

    Multicomponent homogeneous, ultrapure noncrystalline gels/gel derived glasses are promising batch materials for the containerless glass melting experiments in microgravity. Hence, ultrapure, homogeneous gel precursors could be used to: (1) investigate the effect of the container induced nucleation on the glass forming ability of marginally glass forming compositions; and (2) investigate the influence of gravity on the phase separation and coarsening behavior of gel derived glasses in the liquid-liquid immiscibility zone of the nonsilicate systems having a high density phase. The structure and crystallization behavior of gels in the SiO2-GeO2 as a function of gel chemistry and thermal treatment were investigated. As are the chemical principles involved in the distribution of a second network former in silica gel matrix being investigated. The procedures for synthesizing noncrystalline gels/gel-monoliths in the SiO2-GeO2, GeO2-PbO systems were developed. Preliminary investigations on the levitation and thermal treatment of germania silicate gel-monoliths in the Pressure Facility Acoustic Levitator were done.

  3. Theory of glass

    International Nuclear Information System (INIS)

    Rivier, N.

    1985-01-01

    The physical properties of glass are direct consequences of its non-crystalline structure. The structure is described from a topological point of view, since topology is the only geometry surviving non-crystallinity, i.e. absence of metric and trivial space group. This fact has two main consequences: the overall homogeneity of glass is a gauge symmetry, and the only extended, structurally stable constituents are odd lines (or 2π-disclinations in the elastic continuum limit). A gauge theory of glass, based on odd lines as sources of frozen-in strain, can explain those properties of glasses which are both specific to, and universal in amorphous solids: low-temperature excitations, and relaxation at high temperatures. The methods of statistical mechanics can be applied to give a minimal description of amorphous structures in statistical equilibrium. Criteria for statistical equilibrium of the structure and detailed balance are given, together with structural equations of state, which turn out to be well-known empirically among botanists and metallurgists. This review is based on lectures given in 1984 in Niteroi. It contains five parts: I - Structure, from a topological viewpoint; II - gauge invariance; III - Tunneling modes; IV - Supercooled liquid and the glass transitions; V - Statistical crystallography. (Author) [pt

  4. CO 2 adsorption in mono-, di- and trivalent cation-exchanged metal-organic frameworks: A molecular simulation study

    KAUST Repository

    Chen, Yifei

    2012-02-28

    A molecular simulation study is reported for CO 2 adsorption in rho zeolite-like metal-organic framework (rho-ZMOF) exchanged with a series of cations (Na +, K +, Rb +, Cs +, Mg 2+, Ca 2+, and Al 3+). The isosteric heat and Henry\\'s constant at infinite dilution increase monotonically with increasing charge-to-diameter ratio of cation (Cs + < Rb + < K + < Na + < Ca 2+ < Mg 2+ < Al 3+). At low pressures, cations act as preferential adsorption sites for CO 2 and the capacity follows the charge-to-diameter ratio. However, the free volume of framework becomes predominant with increasing pressure and Mg-rho-ZMOF appears to possess the highest saturation capacity. The equilibrium locations of cations are observed to shift slightly upon CO 2 adsorption. Furthermore, the adsorption selectivity of CO 2/H 2 mixture increases as Cs + < Rb + < K + < Na + < Ca 2+ < Mg 2+ ≈ Al 3+. At ambient conditions, the selectivity is in the range of 800-3000 and significantly higher than in other nanoporous materials. In the presence of 0.1% H 2O, the selectivity decreases drastically because of the competitive adsorption between H 2O and CO 2, and shows a similar value in all of the cation-exchanged rho-ZMOFs. This simulation study provides microscopic insight into the important role of cations in governing gas adsorption and separation, and suggests that the performance of ionic rho-ZMOF can be tailored by cations. © 2012 American Chemical Society.

  5. On the relations between ISE and structure in some RE(Mg)SiAlO(N) glasses

    DEFF Research Database (Denmark)

    Keding, Ralf; Dauce, Rachel; Sangleboeuf, J. C.

    2008-01-01

     Six oxide and oxynitride glasses were synthesized in the Y–Mg–Si–Al–O–N, Nd–Mg–Si–Al–O–N and La–Mg–Si–Al–O–N systems. As already known, nitrogen introduction increases the T g, packing factor and mechanical properties of the glasses. Cationic substitution also has an influence on the glasses’ be...... behaves as a former in the network. seems to be a key parameter governing hardness and sensitivity to ISE and can be linked to normal/abnormal behavior of glasses regarding indentation....... Six oxide and oxynitride glasses were synthesized in the Y–Mg–Si–Al–O–N, Nd–Mg–Si–Al–O–N and La–Mg–Si–Al–O–N systems. As already known, nitrogen introduction increases the T g, packing factor and mechanical properties of the glasses. Cationic substitution also has an influence on the glasses......’ behavior, particularly in terms of sensitivity to indentation load/size effect (ISE). The structure of the yttrium-containing glasses was investigated by mean of 27Al and 29Si MAS-NMR. Al is found to occur for 2/3 as a network former and for 1/3 as a modifier. The oxide glass mainly contains Q2 and Q3...

  6. Sinter recrystalization and properties evaluation of glass-ceramic from waste glass bottle and magnesite for extended application

    Directory of Open Access Journals (Sweden)

    As'mau Ibrahim Gebi

    2016-12-01

    Full Text Available In a bid to address environmental challenges associated with the management of waste Coca cola glass bottle, this study set out to develop glass ceramic materials using waste coca cola glass bottles and magnesite from Sakatsimta in Adamawa state. A reagent grade chrome (coloring agent were used to modify the composition of the coca cola glass bottle;  X-ray fluorescence(XRF, X-ray diffraction (XRD and Thermo gravimetric analysis (TGA were used to characterize raw materials, four batches GC-1= Coca cola glass frit +1%Cr2O3, GC-2=97% Coca cola glass frit+ 2% magnesite+1%Cr2O3, GC-3=95% Coca cola glass frit+ 4%magnesite+1%Cr2O3, GC-4=93%Coca cola glass frit+ 6%magnesite+ 1%Cr2O3 were formulated and prepared. Thermal Gradient Analysis (TGA results were used as a guide in selection of three temperatures (7000C, 7500C and 8000C used for the study, three particle sizes -106+75, -75+53, -53µm and 2 hr sintering time were also used, the sinter crystallization route of glass ceramic production was adopted. The samples were characterized by X-ray diffraction (XRD and Scanning Electron Microscope (SEM, the density, porosity, hardness and flexural strength of the resulting glass ceramics were also measured. The resulting glass ceramic materials composed mainly of wollastonite, diopside and anorthite phases depending on composition as indicated by XRD and SEM, the density of the samples increased with increasing sintering temperature and decreasing particle size. The porosity is minimal and it decreases with increasing sintering temperature and decreasing particle size. The obtained glass ceramic materials possess appreciable hardness and flexural strength with GC-3 and GC-4 having the best combination of both properties.

  7. Evidence for the Formation of Pyrimidine Cations from the Sequential Reactions of Hydrogen Cyanide with the Acetylene Radical Cation.

    Science.gov (United States)

    Hamid, Ahmed M; Bera, Partha P; Lee, Timothy J; Aziz, Saadullah G; Alyoubi, Abdulrahman O; El-Shall, M Samy

    2014-10-02

    Herein, we report the first direct evidence for the formation of pyrimidine ion isomers by sequential reactions of HCN with the acetylene radical cation in the gas phase at ambient temperature using the mass-selected variable temperature and pressure ion mobility technique. The formation and structures of the pyrimidine ion isomers are theoretically predicted via coupled cluster and density functional theory calculations. This ion-molecule synthesis may indicate that pyrimidine is produced in the gas phase in space environments before being incorporated into condensed-phase ices and transformed into nucleic acid bases such as uracil.

  8. Properties and structural features of iron doped BABAL glasses

    Directory of Open Access Journals (Sweden)

    Reis Signo Tadeu dos

    2003-01-01

    Full Text Available The chemical durability, density and structure of the BABAL glasses with batch compositions (100-x(0.30BaO·0.50B2O3·0.20Al2O3·xFe 2O3 (1 < x < 10 mol%, were investigated using Mössbauer spectroscopy, electron paramagnetic resonance (EPR, X-ray diffraction, Raman and differential thermal analysis (DTA. The chemical durability for the glass of composition 27BaO·45B2O3·18Al 2O3·10Fe2O3 (mol% at 90 °C in distilled water was 700 times lower than that of iron phosphate glass 40Fe2O3·60P2O 5 (mol%. The Mössbauer spectra indicate the presence of iron (II and iron (III in tetrahedral or octahedral coordination. The results obtained from the g ef = 4.3 EPR line are typical of the occurrence of iron (III occupying substitutional sites and the line g ef = 2.0 is related to the association of two or more Fe ions found in the interstices (or holes occupied by the glass modifier cations of the glass network. The paths of X-ray diffraction are typical for glasses based in borate glasses. The Raman spectra showed that the boroxol ring disappears with the increase of iron content, concomitant with the appearance of BO4 and tetraborate structural units. At these conditions, an increase of dissolution rate and clustering of iron ions is observed.

  9. Composite membranes prepared from cation exchange membranes and polyaniline and their transport properties in electrodialysis

    Energy Technology Data Exchange (ETDEWEB)

    Sata, Tshikatsu; Ishii, Yuuko; Kawamura, Kohei; Matsusaki, Koji [Yamaguchi Univ., Ube City, Yamaguchi (Japan). Dept. of Applied Chemistry and Chemical Engineering

    1999-02-01

    A cation exchange membrane was modified with polyaniline by polymerizing aniline with ammonium peroxodisulfate on the membrane surfaces, producing a membrane with polyaniline layers on both surfaces or a membrane with a single polyaniline layer on the surface. The modified membranes, composite membranes, showed sodium ion permselectivity in electrodialysis compared with divalent cations at an optimum polymerization time. The electronic conductivity of dry membranes showed a maximum (ca. 5 {times} 10{sup {minus}3} S/cm) at the same polymerization time as the time to attain a maximum value of the sodium ion permselectivity. Because emeraldine-based polyaniline is conductive and has a cationic charge, the sodium ion permselectivity is based on the difference in the electrostatic repulsion forces of the cationic charge on the membrane surface of a desalting side to divalent cations and sodium ions. In fact, the selective permeation of sodium ions appeared only when the layer faced the desalting side of the membrane, and was affected by dissociation of polyaniline. Further oxidized polyaniline, pernigraniline-based polyaniline, did not affect the permselectivity between cations, and the diffusion coefficient of neutral molecules, urea, increased with increasing polymerization time. Sodium ion permselectivity was maintained with repeated electrodialysis.

  10. Infrared spectroscopy of the methanol cation and its methylene-oxonium isomer

    Science.gov (United States)

    Mosley, J. D.; Young, J. W.; Huang, M.; McCoy, A. B.; Duncan, M. A.

    2015-03-01

    The carbenium ion with nominal formula [C,H4,O]+ is produced from methanol or ethylene glycol in a pulsed-discharge supersonic expansion source. The ion is mass selected, and its infrared spectrum is measured from 2000 to 4000 cm-1 using laser photodissociation spectroscopy and the method of rare gas atom tagging. Computational chemistry predicts two isomers, the methanol and methylene-oxonium cations. Predicted vibrational spectra based on scaled harmonic and reduced dimensional treatments are compared to the experimental spectra. The methanol cation is the only isomer produced when methanol is used as a precursor. When ethylene glycol is used as the precursor, methylene-oxonium is produced in addition to the methanol cation. Theoretical results at the CCSD(T)/cc-pVTZ level show that methylene-oxonium is lower in energy than methanol cation by 6.4 kcal/mol, and is in fact the global minimum isomer on the [C,H4,O]+ potential surface. Methanol cation is trapped behind an isomerization barrier in our source, providing a convenient method to produce and characterize this transient species. Analysis of the spectrum of the methanol cation provides evidence for strong CH stretch vibration/torsion coupling in this molecular ion.

  11. Using physical properties of molten glass to estimate glass composition

    International Nuclear Information System (INIS)

    Choi, Kwan Sik; Yang, Kyoung Hwa; Park, Jong Kil

    1997-01-01

    A vitrification process is under development in KEPRI for the treatment of low-and medium-level radioactive waste. Although the project is for developing and building Vitrification Pilot Plant in Korea, one of KEPRI's concerns is the quality control of the vitrified glass. This paper discusses a methodology for the estimation of glass composition by on-line measurement of molten glass properties, which could be applied to the plant for real-time quality control of the glass product. By remotely measuring viscosity and density of the molten glass, the glass characteristics such as composition can be estimated and eventually controlled. For this purpose, using the database of glass composition vs. physical properties in isothermal three-component system of SiO 2 -Na 2 O-B 2 O 3 , a software TERNARY has been developed which determines the glass composition by using two known physical properties (e.g. density and viscosity)

  12. Porous vycor glass tube joined to borosilicate glass

    Science.gov (United States)

    Abe, Shinichi; Kikuchi, Takemitsu; Onodera, Shinji

    1992-09-01

    Porous glass can absorb various size of molecules with large surface area even in high temperature. However, it is difficult to use porous glass tubes at high-temperature, for example as a separation membrane for hydrogen condensation, because adhesives at joining sites could be damaged. In this study, welding of a porous glass tube and a glass tube was attempted to develop a gas separation membrane used at 500 C. Since forms present in porous glass may cause crack at high temperature, it is necessary to remove such forms by heat processing. Such porous glass is called to be porous vycor glass, which contains quartz 6 percents, and can be joined with a quartz tube. As a result, a gas separator with porous glass membrane which is joined by this process could endure high temperature up to 600 C and could maintain high vacuum.

  13. Comparative investigation on cation-cation (Al-Sn) and cation-anion (Al-F) co-doping in RF sputtered ZnO thin films: Mechanistic insight

    Energy Technology Data Exchange (ETDEWEB)

    Mallick, Arindam; Basak, Durga, E-mail: sspdb@iacs.res.in

    2017-07-15

    Highlights: • Comparative study on Al, Al-Sn and Al-F doped ZnO films has been carried out. • High transparent Al-F co-doped film shows three times enhanced carrier density. • Al-F co-doped film shows larger carrier relaxation time. • Al-Sn co-doped films shows carrier transport dominated by impurity scattering. • Al-F co-doped ZnO film can be applied as transparent electrode. - Abstract: Herein, we report a comparative mechanistic study on cation-cation (Al-Sn) and cation-anion (Al-F) co-doped nanocrystalline ZnO thin films grown on glass substrate by RF sputtering technique. Through detailed analyses of crystal structure, surface morphology, microstructure, UV-VIS-NIR transmission-reflection and electrical transport property, the inherent characteristics of the co-doped films were revealed and compared. All the nanocrystalline films retain the hexagonal wurtzite structure of ZnO and show transparency above 90% in the visible and NIR region. As opposed to expectation, Al-Sn (ATZO) co-doped film show no enhanced carrier concentration consistent with the probable formation of SnO{sub 2} clusters supported by the X-ray photoelectron spectroscopy study. Most interestingly, it has been found that Al-F (AFZO) co-doped film shows three times enhanced carrier concentration as compared to Al doped and Al-Sn co-doped films attaining a value of ∼9 × 10{sup 20} cm{sup −3} due to the respective cation and anion substitution. The carrier relaxation time increases in AFZO while it decreases significantly for ATZO film consistent with the concurrence of the impurity scattering in the latter.

  14. Exchangeable cations-mediated photodegradation of polycyclic aromatic hydrocarbons (PAHs) on smectite surface under visible light

    International Nuclear Information System (INIS)

    Jia, Hanzhong; Li, Li; Chen, Hongxia; Zhao, Yue; Li, Xiyou; Wang, Chuanyi

    2015-01-01

    Graphical abstract: Roles of exchangeable cations in PAHs photodegradation on clay surafces under visible light. - Highlights: • Photolysis rate are strongly dependent on the type of cations on clay surface. • The strength of “cation–π” interactions governs the photodegradation rate of PAHs. • Several exchangeable cations could cause a shift in the absorption spectrum of PAHs. • Exchangeable cations influence the type and amount of reactive intermediates. - Abstract: Clay minerals saturated with different exchangeable cations are expected to play various roles in photodegradation of polycyclic aromatic hydrocarbons (PAHs) via direct and/or indirect pathways on clay surfaces. In the present study, anthracene and phenanthrene were selected as molecule probes to investigate the roles of exchangeable cations on their photodegradation under visible light irradiation. For five types of cation-modified smectite clays, the photodegradation rate of anthracene and phenanthrene follows the order: Fe 3+ > Al 3+ > Cu 2+ >> Ca 2+ > K + > Na + , which is consistent with the binding energy of cation–π interactions between PAHs and exchangeable cations. The result suggests that PAHs photolysis rate depends on cation–π interactions on clay surfaces. Meanwhile, the deposition of anthracene at the Na + -smectite and K + -smectite surface favors solar light absorption, resulting in enhanced direct photodecomposition of PAHs. On the other hand, smectite clays saturated with Fe 3+ , Al 3+ , and Cu 2+ are highly photoreactive and can act as potential catalysts giving rise to oxidative radicals such as O 2 − · , which initiate the transformation of PAHs. The present work provides valuable insights into understanding the transformation and fate of PAHs in the natural soil environment and sheds light on the development of technologies for contaminated land remediation

  15. Exchangeable cations-mediated photodegradation of polycyclic aromatic hydrocarbons (PAHs) on smectite surface under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Hanzhong, E-mail: jiahz@ms.xjb.ac.cn [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Li, Li [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Chen, Hongxia; Zhao, Yue [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); School of Geology and Mining Engineering, Xinjiang University, Urumqi 830046 (China); Li, Xiyou [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China); Wang, Chuanyi, E-mail: cywang@ms.xjb.ac.cn [Laboratory of Environmental Sciences and Technology, Xinjiang Technical Institute of Physics & Chemistry, Key Laboratory of Functional Materials and Devices for Special Environments, Chinese Academy of Sciences, Urumqi 830011 (China)

    2015-04-28

    Graphical abstract: Roles of exchangeable cations in PAHs photodegradation on clay surafces under visible light. - Highlights: • Photolysis rate are strongly dependent on the type of cations on clay surface. • The strength of “cation–π” interactions governs the photodegradation rate of PAHs. • Several exchangeable cations could cause a shift in the absorption spectrum of PAHs. • Exchangeable cations influence the type and amount of reactive intermediates. - Abstract: Clay minerals saturated with different exchangeable cations are expected to play various roles in photodegradation of polycyclic aromatic hydrocarbons (PAHs) via direct and/or indirect pathways on clay surfaces. In the present study, anthracene and phenanthrene were selected as molecule probes to investigate the roles of exchangeable cations on their photodegradation under visible light irradiation. For five types of cation-modified smectite clays, the photodegradation rate of anthracene and phenanthrene follows the order: Fe{sup 3+} > Al{sup 3+} > Cu{sup 2+} >> Ca{sup 2+} > K{sup +} > Na{sup +}, which is consistent with the binding energy of cation–π interactions between PAHs and exchangeable cations. The result suggests that PAHs photolysis rate depends on cation–π interactions on clay surfaces. Meanwhile, the deposition of anthracene at the Na{sup +}-smectite and K{sup +}-smectite surface favors solar light absorption, resulting in enhanced direct photodecomposition of PAHs. On the other hand, smectite clays saturated with Fe{sup 3+}, Al{sup 3+}, and Cu{sup 2+} are highly photoreactive and can act as potential catalysts giving rise to oxidative radicals such as O{sub 2}{sup −}· , which initiate the transformation of PAHs. The present work provides valuable insights into understanding the transformation and fate of PAHs in the natural soil environment and sheds light on the development of technologies for contaminated land remediation.

  16. Comparison of glass surfaces as a countertop material to existing surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Turo, Laura A.; Winschell, Abigail E.

    2011-09-01

    Gleen Glass, a small production glass company that creates countertops, was selected for the Technology Assistance Program through Pacific Northwest National Laboratory. Gleen Glass was seeking material property analysis comparing glass as a countertop material to current surfaces (i.e. marble, granite and engineered stone). With samples provided from Gleen Glass, testing was done on granite, marble, and 3 different glass surfaces ('Journey,' 'Pebble,' and 'Gleen'). Results showed the glass surfaces have a lower density, lower water absorption, and are stronger in compressive and flexural tests as compared to granite and marble. Thermal shock tests showed the glass failed when objects with a high thermal mass are placed directly on them, whereas marble and granite did not fracture under these conditions.

  17. Aging in a Structural Glass

    OpenAIRE

    Kob, Walter; Barrat, Jean-Louis

    1998-01-01

    We discuss the relaxation dynamics of a simple structural glass which has been quenched below its glass transition temperature. We demonstrate that time correlation functions show strong aging effects and investigate in what way the fluctuation dissipation theorem is violated.

  18. Study of fluorine ion structural role in Al(PO3)3-MF glass by the 19F nuclear magnetic resonance method

    International Nuclear Information System (INIS)

    Gurova, N.N.; Vopilov, V.A.; Buznik, V.M.; Urusovskaya, L.N.

    1989-01-01

    Results of investigation into Al(PO 3 ) 3 -xMF glasses (M=Li, Na, K) by the 19 F NMR method are presented. Investigation supported the structural identity of glasses, containing NaF and KF. One structural position, related to fluorine atoms, coordinating lithium and aluminium ions, is observed in glasses, containing lithium fluoride. The highest mobility of fluorine atoms was revealed in glasses with lithium fluoride. Mobility of fluorine atoms is lower in glasses, containing potassium and sodium fluoride modifications. Dynamic heterogeneity in these glasses is conditioned both by distribution of frequencies of atom motion in the glass and by structural nonequivalence of positions. Fluorine atoms, coordinating cations of alkaline metals, appear to be more mobile

  19. What Glass Ceiling?

    Science.gov (United States)

    Lynch, Michael; Post, Katherine

    1996-01-01

    A recent study drawing on data from the Census Bureau and the Bureau of Labor Statistics suggests that the wage gap between men and women has virtually disappeared, and that the so-called "glass ceiling" results more from age and qualifications than from explicit discrimination. (SLD)

  20. Glass ceilings of professionalisation.

    Science.gov (United States)

    Stott, Dawn L

    2016-04-01

    The term glass ceiling is a political term often used to describe an unbreakable barrier that isnot visible with the human eye, but it keeps minorities from rising up i.e. it is a barrier to minoritygroups, in the past (and sometimes still) for women, that stops them from achieving theirtrue potential.

  1. in glass transition region

    Indian Academy of Sciences (India)

    Unknown

    compositions of arsenic. An effort has also been made to develop an empirical model for the composition dependence of ∆H. A good agreement has been observed between the experimental values and the results of model calculation. Keywords. Glass transition temperature; activation energy; heat absorbed; composition ...

  2. Glass as matter

    DEFF Research Database (Denmark)

    Beim, Anne

    2000-01-01

    Refraiming the Moderns - Substitute Windows and Glass. In general terms, the seminar has contributed to the growing interest in the problems concerning the restoration of Modern Movement architecture. More particularly, it has of course drawn our attention to modern windows, which are increasingl...... recognized as precious and important feature, both for technical resons and for their expression af aesthetic values....

  3. "Stained Glass" Landscape Windows

    Science.gov (United States)

    Vannata, Janine

    2008-01-01

    Both adults and children alike marvel at the grand vivid stained-glass windows created by American artist Louis Comfort Tiffany. Today he is commonly recognized as one of America's most influential designers and artists throughout the last nineteenth and early twentieth century. In the lesson described in this article, students created their own…

  4. in glass transition region

    Indian Academy of Sciences (India)

    Unknown

    wave-guides e.g. in welding and surgery (Nishi et al. 1992). Especially amorphous chalcogenide alloys exhibit the property of reversible transformation. This property makes these systems very useful in optical memory. Glasses are amorphous (Elliot 1990) in nature, i.e. they form a disordered and metastable structure.

  5. Glass as matter

    DEFF Research Database (Denmark)

    Beim, Anne

    2000-01-01

    Refraiming the Moderns - Substitute Windows and Glass. In general terms, the seminar has contributed to the growing interest in the problems concerning the restoration of Modern Movement architecture. More particularly, it has of course drawn our attention to modern windows, which are increasingl...

  6. Stained Glass and Flu

    Centers for Disease Control (CDC) Podcasts

    2017-02-01

    Dr. Robert Webster, an Emeritus member of the Department of Infectious Diseases at St. Jude Children's Research Hospital, discusses his cover art story on stained glass and influenza.  Created: 2/1/2017 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 2/1/2017.

  7. Immobilization of hazardous and radioactive waste into glass structures

    International Nuclear Information System (INIS)

    Wicks, G.G.

    1997-01-01

    As a result of more than three decades of international research, glass has emerged as the material of choice for immobilization of a wide range of potentially hazardous radioactive and non-radioactive materials. The ability of glass structures to incorporate and then immobilize many different elements into durable, high integrity, waste glass products is a direct function of the unique random network structure of the glassy state. Every major country involved with long-term management of high-level radioactive waste (HLW) has either selected or is considering glass as the matrix of choice for immobilizing and ultimately, disposing of the potentially hazardous, high-level radioactive material. There are many reasons why glass is preferred. Among the most important considerations are the ability of glass structures to accommodate and immobilize the many different types of radionuclides present in HLW, and to produce a product that not only has excellent technical properties, but also possesses good processing features. Good processability allows the glass to be fabricated with relative ease even under difficult remote-handling conditions necessary for vitrification of highly radioactive material. The single most important property of the waste glass produced is its ability to retain hazardous species within the glass structure and this is reflected by its excellent chemical durability and corrosion resistance to a wide range of environmental conditions. In addition to immobilization of HLW glass matrices are also being considered for isolation of many other types of hazardous materials, both radioactive as well as nonradioactive. This includes vitrification of various actinides resulting from clean-up operations and the legacy of the cold war, as well as possible immobilization of weapons grade plutonium resulting from disarmament activities. Other types of wastes being considered for immobilization into glasses include transuranic wastes, mixed wastes, contaminated

  8. Mechanism of bacterial inactivation by cationic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Pavlova, I.B.; Samoylenko, I.I.

    1985-03-01

    The mechanism of bacteriocidal action of the cationic surfactant dimethylbenzylammonium chloride was studied on exposure of Staphylococcus aureus, Streptococcus faecium, Bacillus subtilis and Escherichia coli to different concentrations of the agent and determinations of survival plots. The data showed that the surfactant was bacteriocidal for all the bacteria tested at a concentration of 0.0001%, but more efficient in the case of the gram positives. Electron microscopy showed considerable damage and dissarrangement of the cytoplasmic membrane, indicating that the killing mechanism involved this organelle. It appears that cationic surfactants may constitute effective disinfectant preparations. 9 references, 2 figures.

  9. The relationship between structural and optical properties of Se-Ge-As glasses

    Science.gov (United States)

    Ghayebloo, M.; Rezvani, M.; Tavoosi, M.

    2018-05-01

    In this study, the structural and optical characterization of bulk Se-Ge-As glasses has been investigated. In this regards, six different Se60Ge40-xAsx (0 ≤ x ≤ 25) glasses were prepared by conventional melt quenching technique in quartz ampoule. The produced samples were characterized using X-ray diffraction (XRD), Raman spectroscopy, differential thermal analysis (DTA), ultraviolet-visible (UV-Vis) and Fourier transform infrared (FTIR) spectroscopy. The fundamental absorption edge for all the glasses was analyzed in terms of the theory proposed by Davis and Mott. According to achieved results, fully amorphous phase can easily form in different Se-Ge-As systems. The thermal and optical characteristic of Se60Ge40-xAsx glasses shows anomalous behavior at 5 mol% of As for the glass transition temperature, transmittance, absorption edge, optical energy gap and Urbach energy. The highest glass transition temperature, transmittance, optical energy gap and Urbach energy properties were achieved in Se60Ge35As5 glass as a result of the highest connectivity of cations and anions in glass network.

  10. Bioactive and inert dental glass-ceramics.

    Science.gov (United States)

    Montazerian, Maziar; Zanotto, Edgar Dutra

    2017-02-01

    The global market for dental materials is predicted to exceed 10 billion dollars by 2020. The main drivers for this growth are easing the workflow of dentists and increasing the comfort of patients. Therefore, remarkable research projects have been conducted and are currently underway to develop improved or new dental materials with enhanced properties or that can be processed using advanced technologies, such as CAD/CAM or 3D printing. Among these materials, zirconia, glass or polymer-infiltrated ceramics, and glass-ceramics (GCs) are of great importance. Dental glass-ceramics are highly attractive because they are easy to process and have outstanding esthetics, translucency, low thermal conductivity, high strength, chemical durability, biocompatibility, wear resistance, and hardness similar to that of natural teeth, and, in certain cases, these materials are bioactive. In this review article, we divide dental GCs into the following two groups: restorative and bioactive. Most restorative dental glass-ceramics (RDGCs) are inert and biocompatible and are used in the restoration and reconstruction of teeth. Bioactive dental glass-ceramics (BDGCs) display bone-bonding ability and stimulate positive biological reactions at the material/tissue interface. BDGCs are suggested for dentin hypersensitivity treatment, implant coating, bone regeneration and periodontal therapy. Throughout this paper, we elaborate on the history, processing, properties and applications of RDGCs and BDGCs. We also report on selected papers that address promising types of dental glass-ceramics. Finally, we include trends and guidance on relevant open issues and research possibilities. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 619-639, 2017. © 2016 Wiley Periodicals, Inc.

  11. Glasses and nuclear waste vitrification

    International Nuclear Information System (INIS)

    Ojovan, Michael I.

    2012-01-01

    Glass is an amorphous solid material which behaves like an isotropic crystal. Atomic structure of glass lacks long-range order but possesses short and most probably medium range order. Compared to crystalline materials of the same composition glasses are metastable materials however crystallisation processes are kinetically impeded within times which typically exceed the age of universe. The physical and chemical durability of glasses combined with their high tolerance to compositional changes makes glasses irreplaceable when hazardous waste needs immobilisation for safe long-term storage, transportation and consequent disposal. Immobilisation of radioactive waste in glassy materials using vitrification has been used successfully for several decades. Nuclear waste vitrification is attractive because of its flexibility, the large number of elements which can be incorporated in the glass, its high corrosion durability and the reduced volume of the resulting wasteform. Vitrification involves melting of waste materials with glass-forming additives so that the final vitreous product incorporates the waste contaminants in its macro- and micro-structure. Hazardous waste constituents are immobilised either by direct incorporation into the glass structure or by encapsulation when the final glassy material can be in form of a glass composite material. Both borosilicate and phosphate glasses are currently used to immobilise nuclear wastes. In addition to relatively homogeneous glasses novel glass composite materials are used to immobilise problematic waste streams. (author)

  12. Yesterday's Trash Makes Tomorrow's "Glass"

    Science.gov (United States)

    Wayne, Dale

    2010-01-01

    In this article, the author describes a glass art project inspired by Dale Chihuly. This project uses two-liter plastic soda bottles which are cut apart and trimmed. Applying heat using a hair dryer, the plastic curls and takes an uneven blown-glass quality. The "glass" is then painted using acrylic paint. (Contains 2 resources and 1 online…

  13. Analysis of glass fibre sizing

    DEFF Research Database (Denmark)

    Petersen, Helga Nørgaard; Kusano, Yukihiro; Brøndsted, Povl

    2014-01-01

    . Soxhlet extraction was used to extract components of the sizing from the glass fibres. The glass fibres, their extracts and coated glass plates were analysed by Thermo-Gravimetric Analysis combined with a mass spectrometer (TGA-MS), and Attenuated Total Reflectance Fourier Transform Infrared (ATR...

  14. Final Report - Glass Formulation Development and DM10 Melter Testing with ORP LAW Glasses, VSL-09R1510-2, Rev. 0, dated 6/12/09

    Energy Technology Data Exchange (ETDEWEB)

    Kruger, Albert A.; Pegg, I. L.; Matlack, K. S.; Joseph, I.; Muller, I. S.; Gong, W.

    2013-11-13

    The principal objective of the work described in this Final Report is to extend the glass formulation methodology developed in the earlier work by development of acceptable glass compositions for four LAW compositions specified by ORP that cover the range of sulfate to sodium and potassium to sodium ratios expected in Hanford LAW. The glass formulations were designed to exclude titanium and iron as glass former additives, while tin and vanadium as glass former additives were evaluated for beneficial effects in increasing waste loading in the glasses. This was accomplished through a combination of crucible-scale tests and tests on the DM10 melter system. This melter is the most efficient melter platform for screening glass compositions over a wide range of sulfate concentrations and therefore was selected for the present tests. The current tests provide information on melter processing characteristics and off-gas data, including sulfur incorporation and partitioning.

  15. Composition effects on synthetic glass alteration mechanisms: Part 1. Experiments

    International Nuclear Information System (INIS)

    Rajmohan, Natarajan; Frugier, P.; Gin, St.

    2010-01-01

    Alteration of nuclear waste glasses and silicate minerals is governed by complex processes regulated by several coupled mechanisms. Among these processes is reactive mass transfer through the amorphous gel layer (known as the passivating reactive interphase (PRI) in case of a rate-limiting effect) located between the pristine glass and the bulk solution. In order to assess the influence of the glass composition and the pH on the properties of the PRI, and thus on the nuclear glass durability, an experimental leaching study was performed on borosilicate glass samples with or without Ca, Al, and Zr. Experiments were conducted to understand the influence of the pH and glass composition on the solvated cation diffusion coefficient within the PRI and to generate data for calibration of a PRI solubility model (not presented here). All the experiments were carried out at high S/V ratios so that silicon rapidly reached apparent saturated conditions and the PRI could form: in such conditions glass alteration is controlled only by diffusion of water and dissolved species through the PRI and by precipitation of crystallized secondary phases. The constituents in the PRI and the crystallized secondary phases depend to a large extent on the glass composition and pH. Alkali metal (Na) or preferentially alkaline earth (Ca) elements are retained in the PRI for charge compensation of Al and Zr. The apparent diffusion coefficient calculated from the release of boron, a good tracer, varies with the pH from less than 4 * 10 -22 to 9 * 10 -18 m 2 s -1 in the studied glasses. These very low diffusion coefficients decrease as the pH increases. Concerning the PRI composition we show that Si, Al, Ca and Zr have strong interactions and thus major consequences on the glass durability. Our findings indicate that the SiO 2 aq activity is relatively constant and independent of the pH below pH 9, followed by a drop at pH 10. In addition, the activity of SiO 2 aq is affected by the glass

  16. Assessment, development, and testing of glass for blast environments.

    Energy Technology Data Exchange (ETDEWEB)

    Glass, Sarah Jill

    2003-06-01

    Glass can have lethal effects including fatalities and injuries when it breaks and then flies through the air under blast loading (''the glass problem''). One goal of this program was to assess the glass problem and solutions being pursued to mitigate it. One solution to the problem is the development of new glass technology that allows the strength and fragmentation to be controlled or selected depending on the blast performance specifications. For example the glass could be weak and fail, or it could be strong and survive, but it must perform reliably. Also, once it fails it should produce fragments of a controlled size. Under certain circumstances it may be beneficial to have very small fragments, in others it may be beneficial to have large fragments that stay together. The second goal of this program was to evaluate the performance (strength, reliability, and fragmentation) of Engineered Stress Profile (ESP) glass under different loading conditions. These included pseudo-static strength and pressure tests and free-field blast tests. The ultimate goal was to provide engineers and architects with a glass whose behavior under blast loading is less lethal. A near-term benefit is a new approach for improving the reliability of glass and modifying its fracture behavior.

  17. Integrated Disposal Facility FY 2012 Glass Testing Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, Eric M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kerisit, Sebastien N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Krogstad, Eirik J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Burton, Sarah D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bjornstad, Bruce N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Freedman, Vicky L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Cantrell, Kirk J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Snyder, Michelle MV [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Crum, Jarrod V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Westsik, Joseph H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-03-29

    PNNL is conducting work to provide the technical basis for estimating radionuclide release from the engineered portion of the disposal facility for Hanford immobilized low-activity waste (ILAW). Before the ILAW can be disposed, DOE must conduct a performance assessment (PA) for the Integrated Disposal Facility (IDF) that describes the long-term impacts of the disposal facility on public health and environmental resources. As part of the ILAW glass testing program, PNNL is implementing a strategy, consisting of experimentation and modeling, to provide the technical basis for estimating radionuclide release from the glass waste form in support of future IDF PAs. Key activities in FY12 include upgrading the STOMP/eSTOMP codes to do near-field modeling, geochemical modeling of PCT tests to determine the reaction network to be used in the STOMP codes, conducting PUF tests on selected glasses to simulate and accelerate glass weathering, developing a Monte Carlo simulation tool to predict the characteristics of the weathered glass reaction layer as a function of glass composition, and characterizing glasses and soil samples exhumed from an 8-year lysimeter test. The purpose of this report is to summarize the progress made in fiscal year (FY) 2012 and the first quarter of FY 2013 toward implementing the strategy with the goal of developing an understanding of the long-term corrosion behavior of LAW glasses.

  18. Glass/Ceramic Composites for Sealing Solid Oxide Fuel Cells

    Science.gov (United States)

    Bansal, Narottam P.; Choi, Sung R.

    2007-01-01

    A family of glass/ceramic composite materials has been investigated for use as sealants in planar solid oxide fuel cells. These materials are modified versions of a barium calcium aluminosilicate glass developed previously for the same purpose. The composition of the glass in mole percentages is 35BaO + 15CaO + 5Al2O3 + 10B2O3 + 35SiO2. The glass seal was found to be susceptible to cracking during thermal cycling of the fuel cells. The goal in formulating the glass/ ceramic composite materials was to (1) retain the physical and chemical advantages that led to the prior selection of the barium calcium aluminosilicate glass as the sealant while (2) increasing strength and fracture toughness so as to reduce the tendency toward cracking. Each of the composite formulations consists of the glass plus either of two ceramic reinforcements in a proportion between 0 and 30 mole percent. One of the ceramic reinforcements consists of alumina platelets; the other one consists of particles of yttria-stabilized zirconia wherein the yttria content is 3 mole percent (3YSZ). In preparation for experiments, panels of the glass/ceramic composites were hot-pressed and machined into test bars.

  19. Model Simulations of a Field Experiment on Cation Exchange-affected Multicomponent Solute Transport in a Sandy Aquifer

    DEFF Research Database (Denmark)

    Bjerg, Poul Løgstrup; Ammentorp, Hans Christian; Christensen, Thomas Højlund

    1993-01-01

    A large-scale and long-term field experiment on cation exchange in a sandy aquifer has been modelled by a three-dimensional geochemical transport model. The geochemical model includes cation-exchange processes using a Gaines-Thomas expression, the closed carbonate system and the effects of ionic...... by batch experiments and by the composition of the cations on the exchange complex. Potassium showed a non-ideal exchange behaviour with K&z.sbnd;Ca selectivity coefficients indicating dependency on equivalent fraction and K+ concentration in the aqueous phase. The model simulations over a distance of 35 m...

  20. U-based metallic glasses with superior glass forming ability

    Science.gov (United States)

    Xu, Hongyang; Ke, Haibo; Huang, Huogen; Zhang, Pengguo; Pu, Zhen; Zhang, Pei; Liu, Tianwei

    2018-02-01

    By using Al as the third and B as the fourth but minor alloying elements for the U66.7Co33.3 basic metallic glass, a series of U-Co-Al(-B) alloys were designed. The quaternary U-Co-Al-B alloys exhibit significantly improved glass-forming ability (GFA) than previously reported U-based metallic glasses. Low fragility (∼24) is found for these new U-based metallic glasses. The improvement in GFA would result from denser atomic packing in the undercooled liquids due to the presence of small B atoms. Some U-Co-Al(-B) glasses showed corrosion resistance comparable to that of U64Co34Al2 glass, known for premium anti-corrosive performance among the unveiled U-based glasses.

  1. The current status of glass leaching studies in France

    International Nuclear Information System (INIS)

    Laude, F.

    1983-11-01

    Glass has been selected in France as the material used to confine the activity of fission product solutions, and a continuous vitrification process has been developed at the Marcoule Vitrification Facility (AVM), the first industrial plant. Borosilicate glass was chosen in various compositions for its properties: it is a homogeneous, non-porous material that incorporates appreciable quantities of most of the fission product oxides, and is only alterable at the surface interface layer. Glass thus constitutes the primary radioactivity containment barrier, and it is essential to determine its long-term behavior. Water constitutes the principal hazard during temporary or definitive storage of the glass blocks. Two types of inherent material properties are studied from the standpoint of glass stability under leaching conditions: - chemical durability; - radioactive containability with regard to the various radionuclides, fission products and especially the actinides. Durability tests are carried out in SOXHLET devices and the alteration rates are measured by the weight loss. The containability is measured by the leach rate, i.e. by the rate of activity loss into the water. Leaching tests are conducted for several major objectives: - selection of glass compositions (leach rates); - leaching mechanism studies (hydrolyzed layer characteristics, effects of temperature, pressure, pH, etc.); - long-term behavior studies (glass specimens doped with alpha-emitters); - simulation of geological repository environments [fr

  2. Preliminary Testing For Anionic, Cationic and Non-ionic

    Directory of Open Access Journals (Sweden)

    Bokic, Lj.

    2007-11-01

    Full Text Available Detergents present a major environmental problem due to large quantities of surfactants released from laundries. For this reason, it is important to apply an appropriate analytical method for their determination. In this work, we propose two simple, fast and inexpensive analytical methods for anionic, cationic and non-ionic surfactant determination: thin layer chromatography (TLC separation for qualitative screening and quantitative potentiometric determination with ion-selective electrodes. These methods have been chosen because of their many advantages: rapidity, ease of operation, low cost of analysis and a wide variety of TLC application possibilities. The advantage of potentiometric titration is its very high degree of automation and very low detection limits obtained with different ion-selective electrodes applied for different surfactants.

  3. Enhanced LAW Glass Correlation - Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    Muller, Isabelle S. [The Catholic Univ. of America, Washington, DC (United States). Vitreous State Lab.; Matlack, Keith S. [The Catholic Univ. of America, Washington, DC (United States). Vitreous State Lab.; Pegg, Ian L. [The Catholic Univ. of America, Washington, DC (United States). Vitreous State Lab.; Joseph, Innocent [Atkins Energy Federal EPC, Inc., Columbia, MD (United States)

    2016-12-01

    About 50 million gallons of high-level mixed waste is currently stored in underground tanks at the United States Department of Energy’s (DOE’s) Hanford site in the State of Washington. The Hanford Tank Waste Treatment and Immobilization Plant (WTP) will provide DOE’s Office of River Protection (ORP) with a means of treating this waste by vitrification for subsequent disposal. The tank waste will be separated into low- and high-activity waste fractions, which will then be vitrified respectively into Immobilized Low Activity Waste (ILAW) and Immobilized High Level Waste (IHLW) products. The ILAW product will be disposed in an engineered facility on the Hanford site while the IHLW product is designed for acceptance into a national deep geological disposal facility for high-level nuclear waste. The ILAW and IHLW products must meet a variety of requirements with respect to protection of the environment before they can be accepted for disposal. Acceptable glass formulations for vitrification of Hanford low activity waste (LAW) must meet a variety of product quality, processability, and waste loading requirements. To this end, The Vitreous State Laboratory (VSL) at The Catholic University of America (CUA) developed and tested a number of glass formulations during Part A, Part B1 and Part B2 of the WTP development program. The testing resulted in the selection of target glass compositions for the processing of eight of the Phase I LAW tanks. The selected glass compositions were tested at the crucible scale to confirm their compliance with ILAW performance requirements. Duramelter 100 (DM100) and LAW Pilot Melter tests were then conducted to demonstrate the viability of these glass compositions for LAW vitrification at high processing rates.

  4. Composition-structure-property relation of oxide glasses

    DEFF Research Database (Denmark)

    Hermansen, Christian

    also increases such properties. Yet, these rules are not strictly followed even for the simplest binary oxide glasses, such as alkali silicates, borates and phosphates. In this thesis it is argued that the missing link between composition and properties is the glass structure. Structural models...... are proposed based on topological selection rules and experimentally verified. The relation between structure and properties is evaluated using topological constraint theory, which in its essence is a theory that quantifies the two intuitions of the glass scientist. The end result is a quantitative model...

  5. Contribution of germanium dioxide to the thermal expansion characteristics of some borosilicate glasses and their corresponding glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Darwish, H.; Salama, S.N.; Salman, S.M. [National Research Centre, Cairo (Egypt). Glass Research Dept.

    2002-07-01

    The thermal expansion characteristics of some lithium aluminium germanium borosilicate glasses and their crystalline solids have been investigated. The base glass composition was modified by partial replacement of germanium dioxide instead of silica. In some cases, however, TiO{sub 2} was also added to some selected glasses as a nucleation catalyst. Slight increase in the thermal expansion coefficient ({alpha}) values of the glasses and corresponding slight decrease in both transition (Tg) and softening (Ts) temperatures are detected by GeO{sub 2}/SiO{sub 2} replacements, however, the reverse results were recorded by TiO{sub 2} addition. The obtained data were correlated to the local structure changes induced by GeO{sub 2} or TiO{sub 2} and their contributions to the thermal expansion property of the glasses. On the crystallization, the expansivity of the glasses was markedly changed. It was greatly affected by crystallization of GeO{sub 2}-containing phases and aluminosilicate solid solutions together with the TiO{sub 2}-containing phases formed. The results obtained were explained in relation to the nature, composition and concentration of all phases formed in the glass-ceramics including a residual glass matrix. (orig.)

  6. Foam Glass for Construction Materials

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund

    2016-01-01

    in a solid foam glass. The foam glass industry employs a range of different melt precursors and foaming agents. Recycle glass is key melt precursors. Many parameters influence the foaming process and optimising the foaming conditions is very time consuming. The most challenging and attractive goal is to make...... the foaming process for foam glass with closed pores. In addition, it is shown that melt foaming should preferably be performed in a viscosity limited regime. Finally, it is suggested that the foaming agent contributes significantly to the solid conductivity of foam glass....

  7. Binding properties of oxacalix[4]arenes derivatives toward metal cations

    International Nuclear Information System (INIS)

    Mellah, B.

    2006-11-01

    The objective of this work was to establish the binding properties of oxacalix[4]arene derivatives with different numbers of the oxa bridges, functional groups (ketones, pyridine, ester, amide and methoxy) and conformations. Their interactions with alkali and alkaline-earth, heavy and transition metal cations have been evaluated according to different approaches: (i) extraction of corresponding picrates from an aqueous phase into dichloromethane; (ii) determination of the thermodynamic parameters of complexation in methanol and/or acetonitrile by UV-spectrophotometry and micro-calorimetry; (iii) determination of the stoichiometry of the complexes by ESI-MS; (iv) 1 H-NMR titrations allowing to localize the metal ions in the ligand cavity. In a first part dealing on homo-oxacalix[4]arenes, selectivities for Na + , K + , Ca 2+ , Pb 2+ and Mn 2+ of ketones derivatives was shown. The presence of oxa bridge in these derivatives increases their efficiency while decreasing their selectivity with respect to related calixarenes. The pyridine derivative prefers transition and heavy metal cations, in agreement with the presence of the soft nitrogen atoms. In the second part, di-oxacalix[4]arene ester and secondary amide derivatives were shown to be less effective than tertiary amide counterparts but to present high selectivities for Li + , Ba 2+ , Zn 2+ and Hg 2+ . A third part devoted to the octa-homo-tetra-oxacalix[4]arene tetra-methoxy shows that the 1:1 metal complexes formed are generally more stable than those of calixarenes, suggesting the participation of the oxygen atoms of the bridge in the complexation. Selectivity for Cs + , Ba 2+ , Cu 2+ and Hg 2+ were noted. (author)

  8. Effect of cations on the hydrated proton.

    Science.gov (United States)

    Ottosson, Niklas; Hunger, Johannes; Bakker, Huib J

    2014-09-17

    We report on a strong nonadditive effect of protons and other cations on the structural dynamics of liquid water, which is revealed using dielectric relaxation spectroscopy in the frequency range of 1-50 GHz. For pure acid solutions, protons are known to have a strong structuring effect on water, leading to a pronounced decrease of the dielectric response. We observe that this structuring is reduced when protons are cosolvated with salts. This reduction is exclusively observed for combinations of protons with other ions; for all studied solutions of cosolvated salts, the effect on the structural dynamics of water is observed to be purely additive, even up to high concentrations. We derive an empirical model that quantitatively describes the nonadditive effect of cosolvated protons and cations. We argue that the effect can be explained from the special character of the proton in water and that Coulomb fields exerted by other cations, in particular doubly charged cations like Mg(2+)aq and Ca(2+)aq, induce a localization of the H(+)aq hydration structures.

  9. NMR studies of cation transport across membranes

    Energy Technology Data Exchange (ETDEWEB)

    Shochet, N.R.

    1985-01-01

    /sup 23/Na NMR Studies of cation transport across membranes were conducted both on model and biological membranes. Two ionophores, the carrier monensin and the channel-former gramicidin, were chosen to induce cation transport in large unilamellar phosphatidylcholine vesicles. The distinction between the NMR signals arising from the two sides of the membrane was achieved by the addition of an anionic paramagnetic shift reagent to the outer solution. The kinetics of the cation transport across the membrane was observed simultaneously monitoring the changes in the /sup 23/Na NMR signals of both compartments. Two mathematical models were developed for the estimation of the transport parameters of the monensin- and gramicidin-induced cation transport. The models were able to fit the experimental data very well. A new method for the estimation of the volume trapped inside the vesicles was developed. The method uses the relative areas of the intra- and extravesicular NMR signals arising from a suspension of vesicles bathed in the same medium they contain, as a measure for the relative volumes of these compartments. Sodium transport across biological membranes was studied by /sup 23/ NMR, using suspensions of cultured nerve cells. The sodium influx through voltage-gated channels was studied using the channel modifier batrachotoxin in combination with scorpion toxin.

  10. Resonance raman studies of phenylcyclopropane radical cations

    NARCIS (Netherlands)

    Godbout, J.T.; Zuilhof, H.; Heim, G.; Gould, I.R.; Goodman, J.L.; Dinnocenzo, J.P.; Myers Kelley, A.

    2000-01-01

    Resonance Raman spectra of the radical cations of phenylcyclopropane and trans-1-phenyl-2-methylcyclopropane are reported. A near-UV pump pulse excites a photosensitizer which oxidizes the species of interest, and a visible probe pulse delayed by 35 ns obtains the spectrum of the radical ion. The

  11. Water Adsorption on Free Cobalt Cluster Cations

    NARCIS (Netherlands)

    Kiawi, Denis M.; Bakker, Joost M.; Oomens, Jos; Buma, Wybren Jan; Jamshidi, Zahra; Visscher, Lucas; Waters, L. B. F. M.

    2015-01-01

    Cationic cobalt clusters complexed with water Con+–H2O (n = 6–20) are produced through laser ablation and investigated via infrared multiple photon dissociation (IR-MPD) spectroscopy in the 200–1700 cm–1 spectral range. All spectra exhibit a resonance close to the 1595 cm–1 frequency of the free

  12. Water adsorption on free cobalt cluster cations

    NARCIS (Netherlands)

    Kiawi, D.M.; Bakker, J.M.; Oomens, J.; Buma, W.J.; Jamshidi, Z.; Visscher, L.; Waters, L.B.F.M.

    2015-01-01

    Cationic cobalt clusters complexed with water Con+-​H2O (n = 6-​20) are produced through laser ablation and investigated via IR multiple photon dissocn. (IR-​MPD) spectroscopy in the 200-​1700 cm-​1 spectral range. All spectra exhibit a resonance close to the 1595 cm-​1 frequency of the free water

  13. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.

    2003-01-01

    Polypyrrole (PPy) polymer films permanently doped with large, immobile anion dodecyl benzene sulfonate (DBS) have been characterized by cyclic voltammetry in order to clarify the roles of cations and anions in the aqueous electrolyte as mobile ions in the film. Aqueous solutions of 0.05-0.1 M...

  14. Cationic flotation of some lithium ores

    International Nuclear Information System (INIS)

    Valadao, G.E.S.; Peres, A.E.C.; Silva, H.C. da

    1984-01-01

    The cationic flotation of some lithium ores (spodumene, amblygonite, petalite, lepidolite) is studied by the measure of zeta potential and micro-flotation tests in Hallimond tube. The effect of some modifier agents (corn starch, meta sodium silicate) on the lithium flotation is studied. (M.A.C.) [pt

  15. Infrared and Raman spectroscopic studies on alkali borate glasses: evidence of mixed alkali effect.

    Science.gov (United States)

    Padmaja, G; Kistaiah, P

    2009-03-19

    A lithium-potassium-borate glass system containing manganese and iron cations has been thoroughly investigated in order to obtain information about the mixed alkali effect and the structural role of both the manganese and iron in such glass hosts. Mixed alkali borate glasses of the (30 - x)Li(2)O - xK(2)O - 10CdO/ZnO - 59B(2)O(3) (x = 0, 10, 15, 20, and 30) doped with 1MnO(2)/1Fe(2)O(3) system were prepared by a melt quench technique. The amorphous phase of the prepared glass samples was confirmed from their X-ray diffraction. The spectroscopic properties of glass samples were studied using infrared (IR) and Raman spectroscopic techniques. The density of all the prepared glasses was measured using Archimedes principle. Molar volumes were estimated from the density data. IR spectra of these glasses revealed a dramatic variation of three- and four-coordinated boron structures as a function of mixed alkali concentration. The vibrations due to Li-O, K-O, and MnO(4)/FeO(4) arrangements are consistent in all the compositions and show a nonlinear variation in the intensity with alkali content. Raman spectra of different alkali combinations with CdO and ZnO present drastic changes in the intensity of various Raman bands. The observation of disappearance and reappearance of IR and Raman bands as a function of various alkali concentrations is an important result pertaining to the mixed alkali effect in borate glasses. Acting as complementary spectroscopic techniques, both types of measurements, IR and Raman, revealed that the network structure of the studied glasses is mainly based on BO(3) and BO(4) units placed in different structural groups, the BO(3) units being dominant. The measured IR and Raman spectra of different glasses are used to clarify the optical properties of the present glasses correlating them with their structure and composition.

  16. Low thermal expansion glass ceramics

    CERN Document Server

    1995-01-01

    This book is one of a series reporting on international research and development activities conducted by the Schott group of companies With the series, Schott aims to provide an overview of its activities for scientists, engineers, and managers from all branches of industry worldwide where glasses and glass ceramics are of interest Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated This volume describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics The composition, structure, and stability of polycrystalline materials having a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization Thus glass ceramics with thermal c...

  17. The borosilicate glass for 'PAMELA'

    International Nuclear Information System (INIS)

    Schiewer, E.

    1986-01-01

    The low enriched waste concentrate (LEWC) stored at Mol, Belgium, will be solidified in the vitrification plant 'PAMELA'. An alkali-borosilicate glass was developed by the Hahn-Meitner-Institut, Berlin, which dissolves (11 +- 3)wt% waste oxides while providing sufficient flexibility for changes in the process parameters. The development of the glass labelled SM513LW11 is described. Important properties of the glass melt (viscosity, resistivity, formation of yellow phase) and of the glass (corrosion in aqueous solutions, crystallization) are reported. The corrosion data of this glass are similar to those of other HLW-glasses. Less than five wt% of crystalline material are produced upon cooling of large glass blocks. Crystallization does not affect the chemical durability. (Auth.)

  18. Iron Phosphate Glass-ceramics

    Directory of Open Access Journals (Sweden)

    Andrea Moguš-Milanković

    2015-12-01

    Full Text Available The crystallization of 40Fe2O3-60P2O5, 10ZnO-30Fe2O3-60P2O5 and (43.3−xPbO–(13.7+xFe2O3–43P2O5, (0 x < 30, glasses and glass-ceramic have been investigated. The structural evolution of glasses during heat treatment at various temperatures and the tendency for crystallization for series of glasses with modified composition are characterized by a dendrite-like phase separation in the early stage of crystallization. Such a behavior leads to the formation of randomly dispersed agglomerates which contain the anhedrally shaped crystallites embedded in glass matrix. Therefore, regardless of the type of crystallization, controlled or spontaneous, the formation of crystalline phases in these phosphate glasses and glass-ceramics is attributed to the disordered interfaces between crystalline grains and glassy matrix.

  19. Uranium mobility during interaction of rhyolitic glass with alkaline solutions: dissolution of glass

    Science.gov (United States)

    Zielinski, Robert A.

    1977-01-01

    This report concerns investigations designed to identify the important physical and chemical parameters influencing the rate of release of uranium from glass shards of rhyolitic air-fall ash. Oxidizing, silica undersaturated, alkaline solutions are eluted through a column of rhyolitic glass shards at a carefully controlled temperature, pressure, and flow rate. The solutions are monitored for the concentration of uranium and selected additional elements (Si, K, Li, F), and the glass is recovered and examined for physical and/or chemical evidence of attack. The flushing mode is designed to mimic leaching of glass shards by intermittent, near-surface waters with which the glass is not in equilibrium. Reported rates are applicable only to the experimental conditions (120?C, 7,000 psi), but it is assumed that the reaction mechanisms and the relative importance of rate-influencing parameters remain unchanged, at reduced temperature and pressure. Results of the above experiment indicate that silica and uranium are released from glass shards at comparable rates, while lithium and potassium are released faster and fluorine slower than either Si or U. Rates of release of silica and uranium correlate positively with the surface area of the shards. Rhyolitic shards release uranium at faster rates than rhyodacitic shards of comparable surface area. Changes in the shards resulting from experimental treatment and observed in the original glass separates from an Oligocene ash (compared to a Pleistocene ash) include; surface pitting, increased surface area, devitrification rinds (effect of temperature, pressure, solution composition, and flow rate on the relative mobility of U, Si, Li, F, and K.

  20. Fluoride-containing bioactive glasses: Glass design, structure, bioactivity, cellular interactions, and recent developments

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Furqan A., E-mail: furqan.ali.shah@biomaterials.gu.se

    2016-01-01

    Bioactive glasses (BGs) are known to bond to both hard and soft tissues. Upon exposure to an aqueous environment, BG undergoes ion exchange, hydrolysis, selective dissolution and precipitation of an apatite layer on their surface, which elicits an interfacial biological response resulting in bioactive fixation, inhibiting further dissolution of the glass, and preventing complete resorption of the material. Fluorine is considered one of the most effective in-vivo bone anabolic factors. In low concentrations, fluoride ions (F{sup −}) increase bone mass and mineral density, improve the resistance of the apatite structure to acid attack, and have well documented antibacterial properties. F{sup −} ions may be incorporated into the glass in the form of calcium fluoride (CaF{sub 2}) either by part-substitution of network modifier oxides, or by maintaining the ratios of the other constituents relatively constant. Fluoride-containing bioactive glasses (FBGs) enhance and control osteoblast proliferation, differentiation and mineralisation. And with their ability to release fluoride locally, FBGs make interesting candidates for various clinical applications, dentinal tubule occlusion in the treatment of dentin hypersensitivity. This paper reviews the chemistry of FBGs and the influence of F{sup −} incorporation on the thermal properties, bioactivity, and cytotoxicity; and novel glass compositions for improved mechanical properties, processing, and bioactive potential. - Highlights: • Fluoride ions form charged CaF{sup +} species rather than Si–F bonds. • Fluoride incorporation lowers glass transition and crystallisation temperatures. • Oxynitride and oxyfluoronitride glasses with superior mechanical properties • Mixed-alkali and alkali-free compositions with better processing characteristics.

  1. Surface silver-doping of biocompatible glass to induce antibacterial properties. Part I: Massive glass.

    Science.gov (United States)

    Verné, E; Miola, M; Vitale Brovarone, C; Cannas, M; Gatti, S; Fucale, G; Maina, G; Massé, A; Di Nunzio, S

    2009-03-01

    A glass belonging to the system SiO(2)-Al(2)O(3)-CaO-Na(2)O has been subjected to a patented ion-exchange treatment to induce surface antibacterial activity by doping with silver ions. Doped samples have been characterized by means of X-Ray diffraction (XRD), scanning electron microscopy (SEM) observation, energy dispersion spectrometry (EDS) analysis, in vitro bioactivity test, Ag(+) leaching test by graphite furnace atomic absorption spectroscopy (GFAAS) analyses, cytotoxicity tests by fibroblasts adhesion and proliferation, adsorption of IgA and IgG on to the material to evaluate its inflammatory property and antibacterial tests (cultures with Staphylococcus aureus and Escherichia coli). In vitro tests results demonstrated that the modified glass maintains the same biocompatibility of the untreated one and, moreover, it acquires an antimicrobial action against tested bacteria. This method can be selected to realize glass or glass-ceramic bone substitutes as well as coatings on bio-inert devices, providing safety against bacterial colonization thus reducing the risks of infections nearby the implant site. The present work is the carrying on of a previous research activity, concerning the application of an ion-exchange treatment on glasses belonging to the ternary system SiO(2)-CaO-Na(2)O. On the basis of previous results the glass composition was refined and the ion-exchange process was adapted to it, in order to tune the final material properties. The addition of Al(2)O(3) to the original glass system and the optimization of the ion-exchange conditions allowed a better control of the treatment, leading to an antibacterial material, without affecting both bioactivity and biocompatibility.

  2. Synthesis and Structural Studies of Er3+ Containing Lead Cadmium Fluoroborate Glasses and Glass-Ceramics

    Directory of Open Access Journals (Sweden)

    Silva Maurício A.P.

    2002-01-01

    Full Text Available The vitreous domain was established in the PbF2-CdF2-B2O 3 system from melting and quenching experiments. Er3+ containing glasses were prepared and glass ceramics were obtained by selected heat-treatments. Lead fluoride was identified (beta-PbF2 as the crystalline phase. Structural studies were performed in some glassy and partially crystallized samples by means of X-ray Diffraction (XRD and Extended X-ray Absorption Fine Structure (EXAFS measurements. The role of Cd2+ and Pb2+ atoms on the glass network formation and also on the crystallization behavior was put forward by these techniques. After crystallization Er3+ atoms segregated in the crystal phase.

  3. Development and modification of glass membranes for aggressive gas separations

    Energy Technology Data Exchange (ETDEWEB)

    Lindbraaten, Arne

    2004-07-01

    Chlorine as a chemical is widespread in industry and found in a great variety of processes ranging from water purification to plastic production. In this thesis, a magnesium production factory was chosen as an example because it involved both chlorine - air separation and hydrogen -hydrogen chloride separation. Previously, various types of membrane materials have been tested out for their applicability in the chosen process. The materials previously tested either lacked sufficient membrane performance or sufficient membrane stability. As an attempt to improve both the membrane performance and stability, glass membranes are used in this thesis. Glass membranes are prepared from a borosilicate glass, via a phase separation followed by an acid leaching route. By choosing the appropriate phase separation temperature and acid to glass ratio, the membrane can be produced with an average pore diameter of 2 nm (or 4 nm). However, the 2 nm average pore size is still too large to separate gases with separation selectivities beyond the selectivities predicted from Knudsen diffusion theory. If the pores are narrowed, the selectivity may be raised while the flux hopefully is maintained. The narrowing of the pores was done by a silane coupling to the surface OH-groups on the glass. The silane coupling agent is of the dimethyl-acyl-chlorosilane type, where the length of the acyl chain varies from 1 carbon up to 18 carbons. Glass fibres are also tested in this work, which are produced without phase separation and their average pore size is smaller than the surface-modified glasses. To be able to compare the performance of the various membranes, performance measurements are performed and these measurements are evaluated by the separation power (product of the selectivity and the permeability of the fastest permeating compound). Because of the harsh chlorine or hydrogen chloride environment, to which the membranes are exposed in this work, the membrane stability is at least as

  4. Glasses for Mali

    CERN Multimedia

    PH Department

    2008-01-01

    We are collecting old pairs of glasses to take out to Mali, where they can be re-used by people there. The price for a pair of glasses can often exceed 3 months salary, so they are prohibitively expensive for many people. If you have any old spectacles you can donate, please put them in the special box in the ATLAS secretariat, Bldg.40-4-D01 before the Christmas closure on 19 December so we can take them with us when we leave for Africa at the end of the month. (more details in ATLAS e-news edition of 29 September 2008: http://atlas-service-enews.web.cern.ch/atlas-service-enews/news/news_mali.php) many thanks! Katharine Leney co-driver of the ATLAS car on the Charity Run to Mali

  5. Breaking the glass ceiling.

    Science.gov (United States)

    Lazarus, A

    1997-03-01

    The glass ceiling is a form of organizational bias and discrimination that prevents qualified professionals from achieving positions of top governance and leadership. This article examines glass ceiling barriers that keep physicians from the upper reaches of management. While these factors apply mainly to women and minority physicians in academia, and are attributable to sexual harassment and discrimination, physicians as a class are frequently denied executive management positions. Such denial results from inadequate preparation for a career in health care administration. Important issues in the professional development of physician executives include mentoring, training and education, administrative experience, and cultural and personality factors. All of those must be considered when making the transition from medicine to management.

  6. Gas phase hydration of halogenated benzene cations. Is it hydrogen or halogen bonding?

    Science.gov (United States)

    Mason, Kyle A; Pearcy, Adam C; Attah, Isaac K; Platt, Sean P; Aziz, Saadullah G; El-Shall, M Samy

    2017-07-19

    Halogen bonding (XB) non-covalent interactions can be observed in compounds containing chlorine, bromine, or iodine which can form directed close contacts of the type R1-XY-R2, where the halogen X acts as a Lewis acid and Y can be any electron donor moiety including electron lone pairs on hetero atoms such as O and N, or π electrons in olefin double bonds and aromatic conjugated systems. In this work, we present the first evidence for the formation of ionic halogen bonds (IXBs) in the hydration of bromobenzene and iodobenzene radical cations in the gas phase. We present a combined thermochemical investigation using the mass-selected ion mobility (MSIM) technique and density functional theory (DFT) calculations of the stepwise hydration of the fluoro, chloro, bromo, and iodobenzene radical cations. The binding energy associated with the formation of an IXB in the hydration of the iodobenzene cation (11.2 kcal mol -1 ) is about 20% higher than the typical unconventional ionic hydrogen bond (IHB) of the CH δ+ OH 2 interaction. The formation of an IXB in the hydration of the iodobenzene cation involves a significant entropy loss (29 cal mol -1 K -1 ) resulting from the formation of a more ordered structure and a highly directional interaction between the oxygen lone pair of electrons of water and the electropositive region around the iodine atom of the iodobenzene cation. In comparison, the hydration of the fluorobenzene and chlorobenzene cations where IHBs are formed, -ΔS° = 18-21 cal mol -1 K -1 consistent with the formation of less ordered structures and loose interactions. The electrostatic potentials on the lowest energy structures of the hydrated halogenated benzene radical cations show clearly that the formation of an IXB is driven by a positively charged σ-hole on the external side of the halogen atom X along the C-X bond axis. The size of the σ-hole increases significantly in bromobenzene and iodobenzene radical cations which results in strong

  7. Amorphous gauge glass theory

    International Nuclear Information System (INIS)

    Nielsen, H.B.; Bennett, D.L.

    1987-08-01

    Assuming that a lattice gauge theory describes a fundamental attribute of Nature, it should be pointed out that such a theory in the form of a gauge glass is a weaker assumption than a regular lattice model in as much as it is not constrained by the imposition of translational invariance; translational invariance is, however, recovered approximately in the long wavelength or continuum limit. (orig./WL)

  8. Nuclear traces in glass

    International Nuclear Information System (INIS)

    Segovia A, M. de N.

    1978-01-01

    The charged particles produce, in dielectric materials, physical and chemical effects which make evident the damaged zone along the trajectory of the particle. This damaged zone is known as the latent trace. The latent traces can be enlarged by an etching of the detector material. This treatment attacks preferently the zones of the material where the charged particles have penetrated, producing concavities which can be observed through a low magnification optical microscope. These concavities are known as developed traces. In this work we describe the glass characteristics as a detector of the fission fragments traces. In the first chapter we present a summary of the existing basic theories to explain the formation of traces in solids. In the second chapter we describe the etching method used for the traces development. In the following chapters we determine some chatacteristics of the traces formed on the glass, such as: the development optimum time; the diameter variation of the traces and their density according to the temperature variation of the detector; the glass response to a radiation more penetrating than that of the fission fragments; the distribution of the developed traces and the existing relation between this ditribution and the fission fragments of 252 Cf energies. The method which has been used is simple and cheap and can be utilized in laboratories whose resources are limited. The commercial glass which has been employed allows the registration of the fission fragments and subsequently the realization of experiments which involve the counting of the traces as well as the identification of particles. (author)

  9. Binding properties of oxacalix[4]arenes derivatives toward metal cations; Interactions entre cations metalliques et derives des oxacalix[4]arenes

    Energy Technology Data Exchange (ETDEWEB)

    Mellah, B

    2006-11-15

    The objective of this work was to establish the binding properties of oxacalix[4]arene derivatives with different numbers of the oxa bridges, functional groups (ketones, pyridine, ester, amide and methoxy) and conformations. Their interactions with alkali and alkaline-earth, heavy and transition metal cations have been evaluated according to different approaches: (i) extraction of corresponding picrates from an aqueous phase into dichloromethane; (ii) determination of the thermodynamic parameters of complexation in methanol and/or acetonitrile by UV-spectrophotometry and micro-calorimetry; (iii) determination of the stoichiometry of the complexes by ESI-MS; (iv) {sup 1}H-NMR titrations allowing to localize the metal ions in the ligand cavity. In a first part dealing on homo-oxacalix[4]arenes, selectivities for Na{sup +}, K{sup +}, Ca{sup 2+}, Pb{sup 2+} and Mn{sup 2+} of ketones derivatives was shown. The presence of oxa bridge in these derivatives increases their efficiency while decreasing their selectivity with respect to related calixarenes. The pyridine derivative prefers transition and heavy metal cations, in agreement with the presence of the soft nitrogen atoms. In the second part, di-oxacalix[4]arene ester and secondary amide derivatives were shown to be less effective than tertiary amide counterparts but to present high selectivities for Li{sup +}, Ba{sup 2+}, Zn{sup 2+} and Hg{sup 2+}. A third part devoted to the octa-homo-tetra-oxacalix[4]arene tetra-methoxy shows that the 1:1 metal complexes formed are generally more stable than those of calixarenes, suggesting the participation of the oxygen atoms of the bridge in the complexation. Selectivity for Cs{sup +}, Ba{sup 2+}, Cu{sup 2+} and Hg{sup 2+} were noted. (author)

  10. Polyamorphism in metalic glass.

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, H. W.; Liu, H. Z.; Cheng, Y. Q.; Wen, J.; Lee, P.L.; Luo, W.K.; Shastri, S.D.; Ma, E.; X-Ray Science Division; Johns Hopkins Univ.; Chinese Academy of Sciences

    2007-03-01

    A metal, or an alloy, can often exist in more than one crystal structure. The face-centered-cubic and body-centered-cubic forms of iron (or steel) are a familiar example of such polymorphism. When metallic materials are made in the amorphous form, is a parallel 'polyamorphism' possible? So far, polyamorphic phase transitions in the glassy state have been observed only in glasses involving directional and open (such as tetrahedral) coordination environments. Here, we report an in situ X-ray diffraction observation of a pressure-induced transition between two distinct amorphous polymorphs in a Ce{sub 55}Al{sub 45} metallic glass. The large density difference observed between the two polyamorphs is attributed to their different electronic and atomic structures, in particular the bond shortening revealed by ab initio modeling of the effects of f-electron delocalization. This discovery offers a new perspective of the amorphous state of metals, and has implications for understanding the structure, evolution and properties of metallic glasses and related liquids. Our work also opens a new avenue towards technologically useful amorphous alloys that are compositionally identical but with different thermodynamic, functional and rheological properties due to different bonding and structural characteristics.

  11. Athermal photofluidization of glasses

    Science.gov (United States)

    Fang, G. J.; Maclennan, J. E.; Yi, Y.; Glaser, M. A.; Farrow, M.; Korblova, E.; Walba, D. M.; Furtak, T. E.; Clark, N. A.

    2013-02-01

    Azobenzene and its derivatives are among the most important organic photonic materials, with their photo-induced trans-cis isomerization leading to applications ranging from holographic data storage and photoalignment to photoactuation and nanorobotics. A key element and enduring mystery in the photophysics of azobenzenes, central to all such applications, is athermal photofluidization: illumination that produces only a sub-Kelvin increase in average temperature can reduce, by many orders of magnitude, the viscosity of an organic glassy host at temperatures more than 100 K below its thermal glass transition. Here we analyse the relaxation dynamics of a dense monolayer glass of azobenzene-based molecules to obtain a measurement of the transient local effective temperature at which a photo-isomerizing molecule attacks its orientationally confining barriers. This high temperature (Tloc~800 K) leads directly to photofluidization, as each absorbed photon generates an event in which a local glass transition temperature is exceeded, enabling collective confining barriers to be attacked with near 100% quantum efficiency.

  12. Effect of alkali ion on relaxation properties of binary alkali-borate glasses

    International Nuclear Information System (INIS)

    Lomovskoj, V.A.; Bartenev, G.M.

    1992-01-01

    Method of relaxation spectrometry were used to analyze the data on internal friction spectra of lithium, sodium, potassium and rubidium alkali-borate glasses in wide range of temperatures and frequencies. The nature of two relaxation processes was clarified: β m -process, related with mobility of alkaline metal cations, and α-process (vitrification), conditioned by system transformation from viscous-flow to vitreous state. It is shown that atomic-molecular mechanism of vitrification process changes when passing from vitreous B 2 O 3 to alkali-borate glasses

  13. Electron beam induced cationic polymerization of epoxy resins. Dependence of Tg on conversion

    International Nuclear Information System (INIS)

    Degrand, H.; Cazaux, F.; Coqueret, X.

    2002-01-01

    Complete text of publication follows. The high-energy radiation curing of monomer blends polymerizing by a free radical or by a cationic mechanism receives increasing attention in the perspective of high performance composite materials. In the present work, we have focused our attention on epoxy formulations as models of the matrices polymerizing by a cationic mechanism that could be used in fiber-reinforced composites for aerospace applications. We have examined the progress of the electron beam (EB) induced polymerization of diglycidylether of bisphenol A (DGEBA) in the presence of a diaryliodonium salt (DAIS) by FTIR spectroscopy and by dynamic mechanical thermal analysis (DMA). The obtained results allow to draw the gradual increase of the temperature for the network thermomechanical transition (T a , associated with the glass transition temperature T g ) over a broad range of conversion (p) and reveal a peculiar behavior at high conversion. In this domain (p > 0.90), the material's T g is shown to decrease when conversion approaches unity. Moreover, the post-irradiation thermal treatment of the materials, that generally yields effective 'dark curing', appears to induce a decrease of T g , with an amplitude correlated with the amount of DAIS in the formulation. Owing to the particular nature of the propagating centers in cationic polymerisation, the thermal relaxation of ionic clusters trapped in the glassy matrix can be reasonably invoked as a possible cause for this behavior

  14. Preface JFDE Special Issue Glass

    Directory of Open Access Journals (Sweden)

    Ulrich Knaack

    2015-05-01

    Full Text Available Facade Design and Engineering is a multidisciplinary field that touches many other scientific disciplines. Glass is one of the key materials for building envelopes, and a strong scientific community has developed over the last decade. Designers love glass for its transparency. It is strong but brittle and very demanding in terms of engineering. We continuously see new innovative developments in terms of its climatic performance, structural possibilities, construction design and new applications. Reason enough to dedicate this special issue to the topic. The issue would not have been possible without the contribution of our special editors Jan Belis and Christian Louter, who contributed through their outstanding editorial work and network. Most of the papers in this issue were carefully selected from of a number of invited submissions and conference papers of the COST Action TU0905 Mid-Term Conference, April 17+18 2013, Porec, (CRC Press/Balkema, Leiden and subsequently subjected to the regular blind review process of the journal. Glass as a building material demonstrates the nature of the architectural discipline, where science and building practice are closely linked. Buildings are the live testing bed for scientific research and, at the same time, building practice formulates new research questions. We found that many articles sent to us deal with this relation. Therefore we decided to introduce the new category ’Applied Practice’ for certain journal paper contributions, which from now on can be found at the end of each issue. Although they do not need to be purely scientific, ’Applied Practice’ papers will always discuss new developments, will have a clear structure and are subjected to the strict JFDE review process. Façade Design and Engineering is a peer reviewed, open access journal, funded by The Netherlands Organisation for Scientific Research NWO (www.nwo.nl. We see ’open access’ as the future publishing model. But it

  15. Helium behaviour in nuclear glasses

    International Nuclear Information System (INIS)

    Fares, T.

    2011-01-01

    The present thesis focuses on the study of helium behavior in R7T7 nuclear waste glass. Helium is generated by the minor actinides alpha decays incorporated in the glass matrix. Therefore, four types of materials were used in this work. These are non radioactive R7T7 glasses saturated with helium under pressure, glasses implanted with 3 He + ions, glasses doped with curium and glasses irradiated in nuclear reactor. The study of helium solubility in saturated R7T7 glass has shown that helium atoms are inserted in the glass free volume. The results yielded a solubility of about 10 16 at. cm -3 atm. -1 . The incorporation limit of helium in this type of glass has been determined; its value amounted to about 2*10 21 at. cm -3 , corresponding to 2.5 at.%. Diffusion studies have shown that the helium migration is controlled by the single population dissolved in the glass free volume. An ideal diffusion model was used to simulate the helium release data which allowed to determine diffusion coefficients obeying to the following Arrhenius law: D = D 0 exp(-E a /kBT), where D 0 = 2.2*10 -2 and 5.4*10 -3 cm 2 s -1 and E a = 0.61 eV for the helium saturated and the curium doped glass respectively. These results reflect a thermally activated diffusion mechanism which seems to be not influenced by the glass radiation damage and helium concentrations studied in the present work (up to 8*10 19 at. g -1 , corresponding to 0.1 at.%). Characterizations of the macroscopic, structural and microstructural properties of glasses irradiated in nuclear reactor did not reveal any impact associated with the presence of helium at high concentrations. The observed modifications i.e. a swelling of 0.7 %, a decrease in hardness by 38 %, an increase between 8 and 34 % of the fracture toughness and a stabilization of the glass structure under irradiation, were attributed to the glass nuclear damage induced by the irradiation in reactor. Characterizations by SEM and TEM of R7T7 glasses implanted

  16. Physical capture and release of drug molecules, water and cations by a smectite clay

    DEFF Research Database (Denmark)

    Carvalho dos Santos, Éverton

    adsorption ability, charged nano-layered structure. It is in this context that this thesis was developed. Here further understanding on the physico-chemical properties that influence capture and release of Ciprofloxacin (CIPRO, C17H18FN3O3), an antibiotic agent, water molecules, and cations by Li......Clay minerals have been widely applied through human history. For instance research in archaeological sites shows their use to build tools or applied as medicine from prehistoric times. This wide range of applications results from the unique clay minerals properties, such as porosity, water...... conditions, i.e. 60 minutes of data collection. A similar behavior was observed during the XRD studies of capture and release of CIPRO. These results were interpreted based on the selectivity rule among cations. Secondly regarding the dependence of the water absorption behavior on the interlayer cation, from...

  17. Cationic amphipathic peptides accumulate sialylated proteins and lipids in the plasma membrane of eukaryotic host cells

    OpenAIRE

    Weghuber, Julian; Aichinger, Michael C.; Brameshuber, Mario; Wieser, Stefan; Ruprecht, Verena; Plochberger, Birgit; Madl, Josef; Horner, Andreas; Reipert, Siegfried; Lohner, Karl; Henics, Tamas; Schuetz, Gerhard J

    2011-01-01

    Cationic antimicrobial peptides (CAMPs) selectively target bacterial membranes by electrostatic interactions with negatively charged lipids. It turned out that for inhibition of microbial growth a high CAMP membrane concentration is required, which can be realized by the incorporation of hydrophobic groups within the peptide. Increasing hydrophobicity, however, reduces the CAMP selectivity for bacterial over eukaryotic host membranes, thereby causing the risk of detrimental side-effects. In t...

  18. In vivo cation exchange in quantum dots for tumor-specific imaging.

    Science.gov (United States)

    Liu, Xiangyou; Braun, Gary B; Qin, Mingde; Ruoslahti, Erkki; Sugahara, Kazuki N

    2017-08-24

    In vivo tumor imaging with nanoprobes suffers from poor tumor specificity. Here, we introduce a nanosystem, which allows selective background quenching to gain exceptionally tumor-specific signals. The system uses near-infrared quantum dots and a membrane-impermeable etchant, which serves as a cation donor. The etchant rapidly quenches the quantum dots through cation exchange (ionic etching), and facilitates renal clearance of metal ions released from the quantum dots. The quantum dots are intravenously delivered into orthotopic breast and pancreas tumors in mice by using the tumor-penetrating iRGD peptide. Subsequent etching quenches excess quantum dots, leaving a highly tumor-specific signal provided by the intact quantum dots remaining in the extravascular tumor cells and fibroblasts. No toxicity is noted. The system also facilitates the detection of peritoneal tumors with high specificity upon intraperitoneal tumor targeting and selective etching of excess untargeted quantum dots. In vivo cation exchange may be a promising strategy to enhance specificity of tumor imaging.The imaging of tumors in vivo using nanoprobes has been challenging due to the lack of sufficient tumor specificity. Here, the authors develop a tumor-specific quantum dot system that permits in vivo cation exchange to achieve selective background quenching and high tumor-specific imaging.

  19. Methylene blue adsorption in clay mineral dealt with organic cation

    International Nuclear Information System (INIS)

    Silva, T.L.; Lemos, V.P.

    2011-01-01

    The interaction among organic cations, as the methylene blue (AM) and benzyltrimethylammonium (BTMA), and clay minerals of the group of the smectite they result in the formation of applied materials in the adsorption of organic pollutant presents in waters, soils and you cultivate. In this work they were prepared the adsorbents (organic-clays) smectite - AM and smectite-BTMA. The precursory sample of smectite was collected in Rio Branco-Acre. We were also used an smectite sample collected in Sena Madureira (SM)-Acre already characterized in previous work and a sample of standard smectite Swy-2-Na-Montmorillonite (SWy-2) of Wymong - USA. The organic agents selected for this study they were: Blue of Methylene, denominated AM and Benzyltrimethylammonium, denominated BTMA. They were appraised the capacities adsorptive of the treated samples with BTMA being used AM as adsorbate. The results of these evaluations detected that ran total adsorption of AM (concentrations varying from 1 to 10 ppm) for the treated samples with BTMA. The organic cation, BTMA, interacting with the surfaces of the natural clay was more efficient in the adsorption of AM than the clay without the previous treatment with this salt. (author)

  20. Transferability of glass lens molding

    Science.gov (United States)

    Katsuki, Masahide

    2006-02-01

    Sphere lenses have been used for long time. But it is well known that sphere lenses theoretically have spherical aberration, coma and so on. And, aspheric lenses attract attention recently. Plastic lenses are molded easily with injection machines, and are relatively low cost. They are suitable for mass production. On the other hand, glass lenses have several excellent features such as high refractive index, heat resistance and so on. Many aspheric glass lenses came to be used for the latest digital camera and mobile phone camera module. It is very difficult to produce aspheric glass lenses by conventional process of curve generating and polishing. For the solution of this problem, Glass Molding Machine was developed and is spreading through the market. High precision mold is necessary to mold glass lenses with Glass Molding Machine. The mold core is ground or turned by high precision NC aspheric generator. To obtain higher transferability of the mold core, the function of the molding machine and the conditions of molding are very important. But because of high molding temperature, there are factors of thermal expansion and contraction of the mold and glass material. And it is hard to avoid the factors. In this session, I introduce following items. [1] Technology of glass molding and the machine is introduced. [2] The transferability of glass molding is analyzed with some data of glass lenses molded. [3] Compensation of molding shape error is discussed with examples.

  1. Analytical Plan for Roman Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Strachan, Denis M.; Buck, Edgar C.; Mueller, Karl T.; Schwantes, Jon M.; Olszta, Matthew J.; Thevuthasan, Suntharampillai; Heeren, Ronald M.

    2011-01-01

    Roman glasses that have been in the sea or underground for about 1800 years can serve as the independent “experiment” that is needed for validation of codes and models that are used in performance assessment. Two sets of Roman-era glasses have been obtained for this purpose. One set comes from the sunken vessel the Iulia Felix; the second from recently excavated glasses from a Roman villa in Aquileia, Italy. The specimens contain glass artifacts and attached sediment or soil. In the case of the Iulia Felix glasses quite a lot of analytical work has been completed at the University of Padova, but from an archaeological perspective. The glasses from Aquileia have not been so carefully analyzed, but they are similar to other Roman glasses. Both glass and sediment or soil need to be analyzed and are the subject of this analytical plan. The glasses need to be analyzed with the goal of validating the model used to describe glass dissolution. The sediment and soil need to be analyzed to determine the profile of elements released from the glass. This latter need represents a significant analytical challenge because of the trace quantities that need to be analyzed. Both pieces of information will yield important information useful in the validation of the glass dissolution model and the chemical transport code(s) used to determine the migration of elements once released from the glass. In this plan, we outline the analytical techniques that should be useful in obtaining the needed information and suggest a useful starting point for this analytical effort.

  2. Preparation of crosslinked chitosan magnetic membrane for cations sorption from aqueous solution.

    Science.gov (United States)

    Khan, Adnan; Begum, Samina; Ali, Nauman; Khan, Sabir; Hussain, Sajjad; Sotomayor, Maria Del Pilar Taboada

    2017-05-01

    A chitosan magnetic membrane was prepared in order to confer magnetic properties to the membrane, which could be used for the removal of cations from aqueous solution. The crosslinked magnetic membrane was compared with pristine chitosan membrane in term of stability, morphology and cation adsorption capacity. The fabricated magnetic materials are thermally stable as shown by thermogravimetric curves. The membrane containing nickel magnetic particles (CHNiF-G) shows high thermal stability compared to the other membranes. The Fourier transform infrared spectroscopy showed successful preparation of chitosan magnetic membrane. Scanning electron microscopy micrographs showed the rough surface of the membrane with increased porosity. The prepared chitosan membranes were applied to cations of copper, nickel and lead in dilute aqueous solution. The chitosan membrane showed the following adsorption order for metallic cations: Cu 2+ > Ni 2+ > Pb 2+ , while CHNiF-G showed higher capacity, 3.51 mmol g -1 for copper, reflecting the improvement in adsorption capacity, since the amount of copper on pristine chitosan gave 1.40 mmol g -1 . The time required for adsorption to reach to the equilibrium was 6 h for the selected cations using different chitosan membranes. The kinetic study showed that adsorption followed pseudo-second order kinetics. The most commonly used isotherm models, Freundlich, Langmuir and Temkin, were applied to experimental data using linear regression technique. However, The Temkin model fits better to experimental data.

  3. [Determination of cations in wines and beverages based on capillary ion chromatography].

    Science.gov (United States)

    Zhang, Tingting; Ye, Mingli; Hu, Zhongyang; Pan, Guangwen; Liang, Lina; Wu, Shuchao

    2012-04-01

    A new method for the determination of five cations (sodium, ammonium, potassium, magnesium and calcium) in wines and beverages was developed and validated based on capillary ion chromatography. With a capillary ion exchange column (IonPac CS12A, 250 mm x 0.4 mm, 8 microm) and 18 mmol/L methanesulfonic acid (MSA) elution, the five cations can be well separated in 15 min. After suppression with a capillary suppressor (CCES 300), the background was much decreased, and the sensitivities of the cations were greatly improved. For the milky tea, acetonitrile was added into the sample solution to deposit the proteins. With the pretreatment of an OnGuard RP cartridge to remove hydrophobic substances in the sample, the developed method can be applied to the determination of the cations in wines and beverages. The calibration curves of peak area versus concentration gave correlation coefficients more than 0.9997 for these cations. Average recoveries were between 95.2% - 103.3%. The method is suitable for the determination of alkali metals and alkaline-earth metals in wines and beverages. The capillary ion chromatography provides analysis with less solvent consumption and better column efficiency, also possesses the advantages of high sensitivity, good selectivity and environmental friendly.

  4. Reaction enthalpy from the binding of multivalent cations to anionic polyelectrolytes in dilute solutions

    Science.gov (United States)

    Hansch, Markus; Kaub, Hans Peter; Deck, Sascha; Carl, Nico; Huber, Klaus

    2018-03-01

    Dilute solutions of sodium poly(styrene sulfonate) (NaPSS) in the presence of Al3+, Ca2+, and Ba2+ were analysed by means of isothermal titration calorimetry (ITC) in order to investigate the heat effect of bond formation between those cations and the anionic SO3- residues of NaPSS. The selection of the cations was guided by the solution behavior of the corresponding PSS salts from a preceding study [M. Hansch et al., J. Chem. Phys. 148(1), 014901 (2018)], where bonds between Ba2+ and anionic PSS showed an increasing solubility with decreasing temperature and Al3+ exhibited the inverse trend. Unlike to Al3+ and Ba2+, Ca2+ is expected to behave as a purely electrostatically interacting bivalent cation and was thus included in the present study. Results from ITC satisfactorily succeeded to explain the temperature-dependent solution behavior of the salts with Al3+ and Ba2+ and confirmed the non-specific behavior of Ca2+. Additional ITC experiments with salts of Ca2+ and Ba2+ and sodium poly(acrylate) complemented the results on PSS by data from a chemically different polyanion. Availability of these joint sets of polyanion-cation combinations not only offers the chance to identify common features and subtle differences in the solution behavior of polyelectrolytes in the presence of multi-valent cations but also points to a new class of responsive materials.

  5. Foam Glass Production from Waste Glass by Compression

    Science.gov (United States)

    Khamidulina, D. D.; Nekrasova, S. A.; Voronin, K. M.

    2017-11-01

    The authors have identified the impact of the glass mixture briquetting process parameters (milling method, dispersibility, particle size distribution, particle form and compression parameters) on the performance characteristics and the physical and chemical properties of foam glass. It was demonstrated that briquette density increasing contributes to achieving a lower average density of foam glass. It was proven that briquettes produced from multifractional powders are characterized by a higher density than those produced from powders with a limited range of particle size distribution.

  6. UV curing silicon-containing epoxy resin and its glass cloth reinforced composites

    International Nuclear Information System (INIS)

    Yang Guang; Tang Zhuo; Huang Pengcheng

    2007-01-01

    A UV-curable cationic silicon-containing epoxy resin formulation was developed. The gel conversion of the cured resin after 10-min UV irradiation reached 80% in the presence of 5% diaryliodonium salt photoinitiator and 5.5% polyol chain transfer agent by cationic ring-opening polymerization. The glass cloth-reinforced composites were fabricated with the silicon-containing epoxy resin using the wet lay-up technique and UV irradiation. The mechanical properties of the composites were evaluated. Compared with glass cloth reinforced bisphenol A epoxy resin matrix composites, the silicon-containing epoxy resin matrix composites possessed higher tensile strength and interlayer shear strength which was 158.5MPa and 9.9MPa respectively while other mechanical properties such as flexural property and tensile modulus were similar. (authors)

  7. Water resistance and ion diffusion in glass materials simulating vitrified radioactive waste

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, I.A.; Gulin, A.N. [St. Petersburg Institute of Technology (Russian Federation); Stefanovskii, S.V. [RADON Research and Production Association, Moscow (Russian Federation)

    1993-09-01

    Water resistance and diffusion properties of glass materials are studied with reference to pseudobinary systems: simulated ash residue oxides ARO-Na{sub 2}O{center_dot}2B{sub 2}O{sub 3} and ARO-Na{sub 2}O{center_dot}2SiO{sub 2}. The rate of sodium cation leaching is shown to decrease from increasing ARO content, reaching 10{sup -12}, 10{sup -14} kg m{sup -2} s{sup -1}, which satisfies relevant environmental requirements. The diffusion coefficients of sodium cations in ash-containing aluminosilicate glasses, measured by the method of integrated residual activity using the radionuclide {sup 22}Na, are equal to 10{sup -12} - 10{sup -13} kg m{sup -2} s{sup -1} and are 4 to 5 orders of magnitude greater than the diffusion coefficients of the radionuclides {sup 90}Sr and {sup 137}Cs.

  8. An Overview of the Structure-Property Relationships in Silicon-Based Oxynitride Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Becher, Paul F [ORNL; Hampshire, Stuart [University of Limerick; Pomeroy, Michael [University of Limerick; Hoffmann, M. J. [Universituet Karlsruhe, Germany; Lance, Michael J [ORNL; Satet, Raphaella L. [Universituet Karlsruhe, Germany

    2011-01-01

    The silicon oxynitride glasses take advantage of nitrogen-bonding to attain high elastic modulus, increased softening temperatures and viscosities, greater slow crack growth resistance and modest gains in fracture resistance. Of the oxynitride glasses, the Si-Y-Al based oxynitride glasses have been most extensively studied and a degree of success has been achieved in understanding how changes in glass composition affect structural parameters and their relationship to properties. More recent studies have focused on the Si-RE-Me oxynitride glasses where Me is primarily Al or Mg and RE includes most of the lanthanide series elements. These glasses possess a range of elastic, thermal, mechanical and optical properties, which can be correlated with the strength of the RE bond in terms of the cationic field strength. However, such correlation require knowledge of not only the RE valence state but also its coordination with the anions. Herein, the current state of the art understanding of the properties and structural parameters of oxynitride glasses and their interrelationships are reviewed.

  9. Ion conductivities of ZrF4-BaF2-CsF glasses

    International Nuclear Information System (INIS)

    Kawamoto, Yoji; Nohara, Ichiro

    1987-01-01

    The glass-forming region in the ZrF 4 -BaF 2 -CsF glass system has been determined and the ac conductivity and the transport number of fluoride ions have been measured. The conductivities of compounds β-Cs 2 ZrF 6 , α-SrZrF 6 , α-BaZrF 6 , β-BaZrF 6 and α-PbZrF 6 have also been measured. These results and a previous study of ZrF 4 -BaF 2 -MF n (M: the groups I-IV metals) glasses revealed the following: (1) the ZrF 4 -BaF 2 -CsF glasses are exclusively fluoride-ion conductors; (2) the ionic conductivities of ZrF 4 -based glasses are predominantly determined by the activation energies for conduction; (3) the activation energy for conduction decreases with an increase in the average polarizability of glass-constituting cations; (4) a decrease in average Zr-F bond length and a lowering of the average F coordination number of Zr are presumed to increase the activation energy for conduction. Principles of developing ZrF 4 -based glasses with higher conductivities have also been proposed. (Auth.)

  10. Influence of Glass Property Restrictions on Hanford HLW Glass Volume

    International Nuclear Information System (INIS)

    Kim, Dong-Sang; Vienna, John D.

    2001-01-01

    A systematic evaluation of Hanford High-Level Waste (HLW) loading in alkali-alumino-borosilicate glasses was performed. The waste feed compositions used were obtained from current tank waste composition estimates, Hanford's baseline retrieval sequence, and pretreatment processes. The waste feeds were sorted into groups of like composition by cluster analysis. Glass composition optimization was performed on each cluster to meet property and composition constraints while maximizing waste loading. Glass properties were estimated using property models developed for Hanford HLW glasses. The impacts of many constraints on the volume of HLW glass to be produced at Hanford were evaluated. The liquidus temperature, melting temperature, chromium concentration, formation of multiple phases on cooling, and product consistency test response requirements for the glass were varied one- or many-at-a-time and the resultant glass volume was calculated. This study shows clearly that the allowance of crystalline phases in the glass melter can significantly decrease the volume of HLW glass to be produced at Hanford.

  11. Mechanical failure and glass transition in metallic glasses

    International Nuclear Information System (INIS)

    Egami, T.

    2011-01-01

    Research highlights: → We review the recent results of molecular dynamics simulations on metallic glasses. → They show the equivalence of mechanical failure and glass transition. → We discuss the microscopic mechanism behind this equivalence. → We show that the density of defects in metallic glasses is as high as a quarter. → Our concepts about the defect state in glasses need to be changed. - Abstract: The current majority view on the phenomenon of mechanical failure in metallic glasses appears to be that it is caused by the activity of some structural defects, such as free-volumes or shear transformation zones, and the concentration of such defects is small, only of the order of 1%. However, the recent results compel us to revise this view. Through molecular dynamics simulation it has been shown that mechanical failure is the stress-induced glass transition. According to our theory the concentration of the liquid-like sites (defects) is well over 20% at the glass transition. We suggest that the defect concentration in metallic glasses is actually very high, and percolation of such defects causes atomic avalanche and mechanical failure. In this article we discuss the glass transition, mechanical failure and viscosity from such a point of view.

  12. Impact of alpha-recoil damage on dissolution of thoriated glass

    International Nuclear Information System (INIS)

    Eyal, Y.; Ewing, R.C.

    1993-01-01

    Reaction of a seventeen-year old borosilicate glass containing 4 wt% ThO 2 with a bicarbonate-carbonate solution was investigated for times from a few minutes up to approximately one year. For the untreated glass, the initial 228-Th leach rate was enhanced relative to the initial 232-Th leach rate by 15--45%. This incongruent dissolution occurs due to the selective removal of radiogenic 228-Th nuclides from 228-Ra-recoil tracks, damaged regions in the aperiodic glass. Heating the glass at 650 C in air prior to leaching eliminates the 228-Th/232-Th fractionation. Similar enhanced dissolution of alpha-decay products may occur in nuclear waste glasses/groundwater systems; thus, actinide-containing glasses should be examined for alpha-recoil damage effects in order to insure satisfactory prediction of the long-term release of actinides from the nuclear waste glass

  13. A study of water in glass by an autoradiographic method that utilizes tritiated water

    International Nuclear Information System (INIS)

    Knickerbocker, S.H.; Brown, S.D.; Joshi, S.B.

    1983-01-01

    This chapter determines water concentration and spatial distribution in glass by an autoradiographic method that makes use of tritiated water as the tagged species. Describes the method and presents some typical results. Lists advantages and disadvantages associated with the method and examines other methods that might be used for the study of water in glass. Discusses dry glass preparation, the addition of tritiated water to glass, glass preparation, film selection, and film analysis. Shows tritium autoradiography to be a valuable technique for measuring the content and spatial distribution of water in inorganic glasses. Finds that the technique yields unique information, particularly in regard to spatial distribution, when compared with techniques of IR spectroscopy, SIMS, SIPS, NRRA, ESR and NMR. Points out that large areas (e.g., several square inches) of sample can be mapped in a single exposure. Notes that the spatial resolution of water in the glass network can be 10 -7 m, so very accurate diffusion profiles are obtainable

  14. Glass packages in interim storage; Les verres dans les stockages

    Energy Technology Data Exchange (ETDEWEB)

    Jacquet-Francillon, N.

    1994-10-01

    This report summarize the current state of knowledge concerning the behavior of type C waste packages consisting of vitrified high-level solutions produced by reprocessing spent fuel. The composition and the physical and chemical properties of the feed solutions are reviewed, and the vitrification process is described. Sodium alumino-borosilicate glass compositions are generally employed - the glass used at la Hague for LWR fuel solutions, for example, contains 45 % SiO{sub 2}. The major physical, chemical, mechanical and thermal properties of the glass are reviewed. In order to allow their thermal power to diminish, the 3630 glass packages produced (as of January 1993) in the vitrification facilities at Marcoule and La Hague are placed in interim storage for several decades. The actual interim storage period has not been defined, as it is closely related to the concept and organization selected for the final destination of the packages: a geological repository. The glass behavior under irradiation is described. Considerable basic and applied research has been conducted to assess the aqueous leaching behavior of nuclear containment glass. The effects of various repository parameters (temperature, flow rate, nature of the environmental materials) have been investigated. The experimental findings have been used to specify a model describing the kinetics of aqueous corrosion of the glass. More generally all the ``source term`` models developed in France by the CEA or by ANDRA are summarized. (author). 152 refs., 33 figs.

  15. Stained glasses under the nuclear microprobe: A window into history

    Energy Technology Data Exchange (ETDEWEB)

    Vilarigues, M. [Dep. de Conservacao e Restauro and R and D Unit Vidro e da Ceramica Para as Artes, FCT-UNL, Quinta da Torre, 2829-516 Caparica (Portugal)], E-mail: mgv@fct.unl.pt; Fernandes, P. [Dep. de Conservacao e Restauro and R and D Unit Vidro e da Ceramica Para as Artes, FCT-UNL, Quinta da Torre, 2829-516 Caparica (Portugal); Alves, L.C.; Silva, R.C. da [Dep. Fisica, LFI, ITN, E.N.10, 2686-953 Sacavem (Portugal)

    2009-06-15

    Stained glass fragments from the 15th, 16th and 20th centuries, belonging to Mosteiro de Santa Maria da Vitoria, Batalha (Portugal), were characterised non-destructively in a nuclear microprobe. The work aimed at finding the composition of the glasses and glass paintings and relating these with the corresponding production periods. The elemental compositions of the glass fragments were obtained by means of scanning micro-beam Particle Induced X-ray Emission ({mu}-PIXE) spectrometry in selected cross-sections. These were complemented by micro X-Ray fluorescence spectrometry. Characterisation of colour was performed by optical absorption spectroscopy in the UV-vis range, while the corrosion products were identified by optical microscopy and {mu}-FTIR (Fourier Transform Infra Red) spectroscopy in combination with the data generated by {mu}-PIXE. Nuclear microprobe analysis allowed unveiling the compositions and structures, in particular of glass paintings and corrosion products. While it is not surprising that Fe, Cu and Pb were the main elements identified in the grisaille paintings of all studied periods, as well as Ag and Cu found in the glasses decorated with yellow silver painting, their distribution gave important clues on the materials and techniques used to manufacture these stained glasses. Furthermore, it allowed establishing a definite relation between the compositions found and the periods of production, with the added bonus of correctly reassigning the manufacturing period of some samples.

  16. The adjuvant mechanism of cationic dimethyldioctadecylammonium liposomes

    DEFF Research Database (Denmark)

    Korsholm, Karen Smith; Agger, Else Marie; Foged, Camilla

    2007-01-01

    Cationic liposomes are being used increasingly as efficient adjuvants for subunit vaccines but their precise mechanism of action is still unknown. Here, we investigated the adjuvant mechanism of cationic liposomes based on the synthetic amphiphile dimethyldioctadecylammonium (DDA). The liposomes...... concentrations. This efficient adsorption onto the liposomes led to an enhanced uptake of OVA by BM-DCs as assessed by flow cytometry and confocal fluorescence laser-scanning microscopy. This was an active process, which was arrested at 4 degrees and by an inhibitor of actin-dependent endocytosis, cytochalasin D....... In vivo studies confirmed the observed effect because adsorption of OVA onto DDA liposomes enhanced the uptake of the antigen by peritoneal exudate cells after intraperitoneal injection. The liposomes targeted antigen preferentially to antigen-presenting cells because we only observed a minimal uptake...

  17. Preparation of cation-exchange stir bar sorptive extraction based on monolithic material and its application to the analysis of soluble cations in milk by ion chromatography.

    Science.gov (United States)

    Huang, Xiaojia; Lin, Jianbin; Yuan, Dongxing

    2011-10-21

    In this study, a new cation-exchange coating for stir bar sorptive extraction (SBSE) based on poly (acrylic acid-ethylene dimethacrylate) monolithic material was synthesized. The effect of polymerization conditions such as the ratio of functional monomer to cross-linker and the content of porogenic solvent on the extraction efficiencies were investigated in detail. The monolithic material was characterized by elemental analysis, scanning electron microscopy and infrared spectroscopy. In order to evaluate the usability of the new coating for the extraction of inorganic cations, the analysis of soluble K(+), Mg(2+) and Ca(2+) in milk by ion chromatography with conductivity detection was selected as a paradigm. Several extractive parameters, including pH value in sample matrix, desorption solvent, extraction and desorption time were optimized. Under the optimum conditions, low detection limits (S/N = 3) and quantification limits (S/N = 10) of the proposed method for the target cations were achieved within the range of 0.12-0.28 and 0.4-0.92 μg L(-1), respectively. The method also showed good linearity, simplicity, practicality and low cost for the extraction of inorganic cations. Finally, the proposed method was successfully used to analyse three different trademarks of commercial milk samples with satisfactory recoveries in the range of 71.1% to 102.8%.

  18. Moessbauer effect and infrared study of some borate glass containing Mn and Fe oxides

    International Nuclear Information System (INIS)

    Gabr, M.

    2005-01-01

    Lithium borate glasses containing transition metals appeared now of very high technological and scientific interest. Therefore some lithium borate glasses containing mixed transition metal ions (manganese and iron) were investigated. The glass batches were melted at 1250 degree C for three hours and annealed at 350 degree C -over night- to obtain strain free glasses. Moessbauer Effect spectroscopy and Infrared analysis were employed to investigate the structural changes due to the change of their batches composition. Differential thermal analysis, magnetic susceptibility, density and molar volume measurements were also performed to study the effect of changing both manganese and iron oxides at the expense of boron oxide on these properties. Infrared analysis indicated the presence of different structural groups such as BO 3 , BO 4 , FeO 4 and MnO 6 as well as different vibrations indicated the presence of various bonds in the glass network. The values of the characteristic temperatures (T g , T c and T m ) showed gradual increase except those of the last sample where they showed a decrease. The mid sample showed the lowest stability value. It was found that the molar volume showed its highest value at R=0.33 [where R is the ratio of glass network modifier to the glass network former]. After that it showed gradual linear decrease. The magnetic susceptibility measurements showed approximately stable value between R=0.29 and 0.33, then it increased up to R=0.38, and after that, it decreased up to R= 0.43. The obtained magnetic susceptibility values indicated that all these glasses are paramagnetic. The obtained Moessbauer spectra and the calculated parameters confirmed that iron ions participated in the glass network as network former cations. It confirmed also that all glasses reflect paramagnetic character. The observed structural change were explained and correlated with the change of the measured physical properties

  19. Platinoids and molybdenum in nuclear waste containment glasses: a structural study

    International Nuclear Information System (INIS)

    Le Grand, M.

    2000-01-01

    This work deals with the structure of borosilicate nuclear glasses and with some relationships between structure and macroscopic properties. Two types of elements which may disturb the industrial process - platinoids (Ru and Pd) and molybdenum - are central to this work. Platinoids induce weak modifications on the structure of the glass, causing a depolymerization of the glassy network, an increase of the [3] B/ [4] B ratio and a modification of the medium range order around Si between 3.3 and 4.5 angstrom. The modifications of viscosity and density induced by platinoids in the glass are not due to the structural effect of the platinoids. The increase of viscosity is attributed to needle shaped RuO 2 . It can be moderated by imposing reducing conditions during the elaboration of the glass. The slight difference between experimental and calculated densities is due to the increase of the volume percentage of bubbles in the glass with increasing platinoid content. Mo is either present in the glass as molybdic groupings, or mobilized in chemically complex molybdic crystalline phases. The chemical composition and mineralogy of these phases has been obtained using electronic microprobe data and XRD with Rietveld analysis. The distribution of the different elements between the crystalline phases and the glass is strongly influenced by the structural role of the various cations in the glass. The Mo present in the glass appears as MoO 4 tetrahedra, independent of the borosilicate network. The formation of the crystalline phases can be explained by the existence of a precursor in which the MoO 4 tetrahedra are concentrated in rich alkali and earth-alkali bearing areas of the glass. (author)

  20. Analysis of glass fibre sizing

    DEFF Research Database (Denmark)

    Petersen, Helga Nørgaard; Kusano, Yukihiro; Brøndsted, Povl

    2014-01-01

    surfaces are called sizing. The sizing influences the properties of the interface between fibres and a matrix, and subsequently affects mechanical properties of composites. In this work the sizing of commercially available glass fibres was analysed so as to study the composition and chemical structures......Glass fibre reinforced polymer composites are widely used for industrial and engineering applications which include construction, aerospace, automotive and wind energy industry. During the manufacturing glass fibres, they are surface-treated with an aqueous solution. This process and the treated....... Soxhlet extraction was used to extract components of the sizing from the glass fibres. The glass fibres, their extracts and coated glass plates were analysed by Thermo-Gravimetric Analysis combined with a mass spectrometer (TGA-MS), and Attenuated Total Reflectance Fourier Transform Infrared (ATR...

  1. Relaxation Pathways in Metallic Glasses

    Science.gov (United States)

    Gallino, Isabella; Busch, Ralf

    2017-11-01

    At temperatures below the glass transition temperature, physical properties of metallic glasses, such as density, viscosity, electrical resistivity or enthalpy, slowly evolve with time. This is the process of physical aging that occurs among all types of glasses and leads to structural changes at the microscopic level. Even though the relaxation pathways are ruled by thermodynamics as the glass attempts to re-attain thermodynamic equilibrium, they are steered by sluggish kinetics at the microscopic level. Understanding the structural and dynamic pathways of the relaxing glassy state is still one of the grand challenges in materials physics. We review some of the recent experimental advances made in understanding the nature of the relaxation phenomenon in metallic glasses and its implications to the macroscopic and microscopic properties changes of the relaxing glass.

  2. Crystallization of bismuth borate glasses

    International Nuclear Information System (INIS)

    Bajaj, Anu; Khanna, Atul

    2009-01-01

    Bismuth borate glasses with Bi 2 O 3 concentration of 20-66 mol% were prepared by melt quenching and devitrified by heat treatment above their glass transition temperatures. All glasses show a strong tendency towards crystallization on annealing that increases with Bi 2 O 3 concentration. The crystalline phases formed on devitrification were characterized by FTIR absorption spectroscopy and DSC measurements. Our studies reveal that phases produced in glasses are strongly determined by initial glass composition and the two most stable crystalline phases are: Bi 3 B 5 O 12 and Bi 4 B 2 O 9 . The metastable BiBO 3 phase can also be formed by devitrification of glass with 50 mol% of Bi 2 O 3 . This phase is, however, unstable and decomposes into Bi 3 B 5 O 12 and Bi 4 B 2 O 9 on prolonged heat treatment.

  3. Regulation of Cation Balance in Saccharomyces cerevisiae

    Science.gov (United States)

    Cyert, Martha S.; Philpott, Caroline C.

    2013-01-01

    All living organisms require nutrient minerals for growth and have developed mechanisms to acquire, utilize, and store nutrient minerals effectively. In the aqueous cellular environment, these elements exist as charged ions that, together with protons and hydroxide ions, facilitate biochemical reactions and establish the electrochemical gradients across membranes that drive cellular processes such as transport and ATP synthesis. Metal ions serve as essential enzyme cofactors and perform both structural and signaling roles within cells. However, because these ions can also be toxic, cells have developed sophisticated homeostatic mechanisms to regulate their levels and avoid toxicity. Studies in Saccharomyces cerevisiae have characterized many of the gene products and processes responsible for acquiring, utilizing, storing, and regulating levels of these ions. Findings in this model organism have often allowed the corresponding machinery in humans to be identified and have provided insights into diseases that result from defects in ion homeostasis. This review summarizes our current understanding of how cation balance is achieved and modulated in baker’s yeast. Control of intracellular pH is discussed, as well as uptake, storage, and efflux mechanisms for the alkali metal cations, Na+ and K+, the divalent cations, Ca2+ and Mg2+, and the trace metal ions, Fe2+, Zn2+, Cu2+, and Mn2+. Signal transduction pathways that are regulated by pH and Ca2+ are reviewed, as well as the mechanisms that allow cells to maintain appropriate intracellular cation concentrations when challenged by extreme conditions, i.e., either limited availability or toxic levels in the environment. PMID:23463800

  4. Mechanism of metal cationization in organic SIMS

    International Nuclear Information System (INIS)

    Wojciechowski, I.; Delcorte, A.; Gonze, X.; Bertrand, P.

    2003-01-01

    A scenario of metal cationization in which the organic molecule combines with a neutral excited metal atom is proposed. Ionization of the nascent complex occurs via ejection of an electron during the association process. Electron structure calculations for the model systems C 6 H 6 +Me (Me=Ag, Cu, Au) using the density functional theory give a strong argument in favor of the proposed mechanism

  5. Proton dynamics investigation for dimethyl ammonium cation

    International Nuclear Information System (INIS)

    Pislewski, N.; Tritt-Goc, J.; Jakubas, R.

    1995-01-01

    Proton dynamics in dimethyl ammonium cation has been investigated by means of NMR and spin echo methods in polycrystalline salts [NH 2 (CH 3 ) 2 ] + Bi 2 J 9 - and [NH 2 (CH 3 ) 2 ] + SbJ 9 - . Spin-lattice relaxation time as well as second moment of NMR line have been measured for influence study of crystal structure changes on proton dynamics

  6. Structural color from colloidal glasses

    Science.gov (United States)

    Magkiriadou, Sofia

    When a material has inhomogeneities at a lengthscale comparable to the wavelength of light, interference can give rise to structural colors: colors that originate from the interaction of the material's microstructure with light and do not require absorbing dyes. In this thesis we study a class of these materials, called photonic glasses, where the inhomogeneities form a dense and random arrangement. Photonic glasses have angle-independent structural colors that look like those of conventional dyes. However, when this work started, there was only a handful of colors accessible with photonic glasses, mostly hues of blue. We use various types of colloidal particles to make photonic glasses, and we study, both theoretically and experimentally, how the optical properties of these glasses relate to their structure and constituent particles. Based on our observations from glasses of conventional particles, we construct a theoretical model that explains the scarcity of yellow, orange, and red photonic glasses. Guided by this model, we develop novel colloidal systems that allow a higher degree of control over structural color. We assemble glasses of soft, core-shell particles with scattering cores and transparent shells, where the resonant wavelength can be tuned independently of the reflectivity. We then encapsulate glasses of these core-shell particles into emulsion droplets of tunable size; in this system, we observe, for the first time, angle-independent structural colors that cover the entire visible spectrum. To enhance color saturation, we begin experimenting with inverse glasses, where the refractive index of the particles is lower than the refractive index of the medium, with promising results. Finally, based on our theoretical model for scattering from colloidal glasses, we begin an exploration of the color gamut that could be achieved with this technique, and we find that photonic glasses are a promising approach to a new type of long-lasting, non-toxic, and

  7. PLZT capacitor on glass substrate

    Science.gov (United States)

    Fairchild, M. Ray; Taylor, Ralph S.; Berlin, Carl W.; Wong, Celine W. K.; Ma, Beihai; Balachandran, Uthamalingam

    2016-01-05

    A lead-lanthanum-zirconium-titanate (PLZT) capacitor on a substrate formed of glass. The first metallization layer is deposited on a top side of the substrate to form a first electrode. The dielectric layer of PLZT is deposited over the first metallization layer. The second metallization layer deposited over the dielectric layer to form a second electrode. The glass substrate is advantageous as glass is compatible with an annealing process used to form the capacitor.

  8. Who will buy smart glasses?

    DEFF Research Database (Denmark)

    Rauschnabel, Philipp; Brem, Alexander; Ivens, Bjørn S.

    2015-01-01

    of research that investigates the role of personality in predicting media usage by analyzing smart glasses, particularly Google Glass. First, we integrate AR devices into the current evolution of media and technologies. Then, we draw on the Big Five Model of human personality and present the results from two...... studies that investigate the direct and moderating effects of human personality on the awareness and innovation adoption of smart glasses. Our results show that open and emotionally stable consumers tend to be more aware of Google Glass. Consumers who perceive the potential for high functional benefits...

  9. Halide laser glasses

    Energy Technology Data Exchange (ETDEWEB)

    Weber, M.J.

    1982-01-14

    Energy storage and energy extraction are of prime importance for efficient laser action and are affected by the line strengths and linewidths of optical transitions, excited-state lifetimes, nonradiative decay processes, spectroscopic inhomogeneities, nonlinear refractive index, and damage threshold. These properties are all host dependent. To illustrate this, the spectroscopic properties of Nd/sup 3 +/ have been measured in numerous oxide, oxyhalide, and halide glasses. A table summarizes the reported ranges of stimulated emission cross sections, peak wavelengths, linewidths, and radiative lifetimes associated with the /sup 4/F/sub 3/2/ ..-->.. /sup 4/I/sub 11/2/ lasing transition.

  10. Concentration of ions Co(II), Ni(II) at the Tokem-250 carboxylic cation exchange for catalysts development

    Science.gov (United States)

    Zharkova, Valentina; Bobkova, Ludmila; Brichkov, Anton; Kozik, Vladimir

    2017-11-01

    Sorption and catalytic properties of the cation exchanger are investigated. It was found that the Tokem-250 has a wide operating range of pH. The value of the effective ionization constant of the functional groups of the cation exchanger (pKa) is 6.59. The Tokem-250 cation exchanger exhibits selectivity to Ni2+ ions to Co2+ (D˜103). This is probably due to the stability of ion-exchange complexes detected by the method of diffuse reflectance electron spectroscopy (ESDD). According to these data, for Co2+ ions, in contrast to Ni2+, tetragonal distortion of octahedral coordination is characteristic, which has a positive effect on the stability of complexes with Co2+. To obtain spherical catalysts on the basis of Tokem-250, cobalt-containing samples of cation exchanger were used. The developed spherical materials have catalytic activity in the reactions of deep and partial oxidation of n-heptane.

  11. [Antioxidant activity of cationic whey protein isolate].

    Science.gov (United States)

    titova, M E; Komolov, S A; Tikhomirova, N A

    2012-01-01

    The process of lipid peroxidation (LPO) in biological membranes of cells is carried out by free radical mechanism, a feature of which is the interaction of radicals with other molecules. In this work we investigated the antioxidant activity of cationic whey protein isolate, obtained by the cation-exchange chromatography on KM-cellulose from raw cow's milk, in vitro and in vivo. In biological liquids, which are milk, blood serum, fetal fluids, contains a complex of biologically active substances with a unique multifunctional properties, and which are carrying out a protective, antimicrobial, regenerating, antioxidant, immunomodulatory, regulatory and others functions. Contents of the isolate were determined electrophoretically and by its biological activity. Cationic whey protein isolate included lactoperoxidase, lactoferrin, pancreatic RNase, lysozyme and angeogenin. The given isolate significantly has an antioxidant effect in model experimental systems in vitro and therefore may be considered as a factor that can adjust the intensity of lipid oxidation. In model solutions products of lipid oxidation were obtained by oxidation of phosphatidylcholine by hydrogen peroxide in the presence of a source of iron. The composition of the reaction mixture: 0,4 mM H2O2; 50 mcM of hemin; 2 mg/ml L-alpha-phosphatidylcholine from soybean (Sigma, German). Lipid peroxidation products were formed during the incubation of the reaction mixture for two hours at 37 degrees C. In our studies rats in the adaptation period immediately after isolation from the nest obtained from food given orally native cationic whey protein isolate at the concentration three times higher than in fresh cow's milk. On the manifestation of the antioxidant activity of cationic whey protein isolate in vivo evidence decrease of lipid peroxidation products concentration in the blood of rats from the experimental group receipt whey protein isolate in dos 0,6 mg/g for more than 20% (pisolate has an antioxidant

  12. Determination of LFER descriptors of 30 cations of ionic liquids--progress in understanding their molecular interaction potentials.

    Science.gov (United States)

    Cho, Chul-Woong; Jungnickel, Christian; Stolte, Stefan; Preiss, Ulrich; Arning, Jürgen; Ranke, Johannes; Krossing, Ingo; Thöming, Jorg

    2012-02-01

    In order to understand molecular interaction potentials of 30 cations of ionic liquids (ILs), the well-known linear free energy relationship concept (LFER) was applied. The LFER descriptors for the excess molar refractivity and the molar volume were calculated in silico and for hydrogen-bonding acidity and basicity, and the polarizability/dipolarity of IL cations were experimentally determined through high performance liquid chromatography (HPLC) measurements. For the study, three different columns (RP-select B, Cyan, and Diol) and buffered mobile phases, based on two organic solvents acetonitrile (ACN) and methanol (MeOH), were selectively combined to the HPLC separation systems RP-select B-ACN, RP-select B-MeOH, Cyan-MeOH, Diol-ACN, and Diol-MeOH. By measuring the retention factors of 45 neutral calibration compounds and calculating LFER descriptors of three cations in the HPLC systems, the system parameters, including an ionic z coefficient, were determined. Conversely, the LFER descriptors of 30 ionic liquid cations were determined, based on the parameters of five systems and their retention factors in the HPLC systems. The results showed that the type of head group, alkyl chain length and further substituents of the cation have a significant influence on the dipolarity/polarizability and the hydrogen-bonding acidity, and functionalized groups (hydroxyl, ether, and dimethylamino) lead to hydrogen-bonding basicity of the cation. The characterization of cationic LFER descriptors opens up the chance for a more quantitative understanding of molecular interaction potentials and physicochemical properties of ILs. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Comparative analysis of cation/proton antiporter superfamily in plants

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Chuyu [ORNL; Yang, Xiaohan [ORNL; Xia, Xinli [Beijing Forestry University, China; Yin, Weilun [Beijing Forestry University, China

    2013-01-01

    The cation/proton antiporter superfamily is associated with the transport of monovalent cations across membranes. This superfamily was annotated in the Arabidopsis genome and some members were functionally characterized. In the present study, a systematic analysis of the cation/proton antiporter genes in diverse plant specieswas reported.We identified 240 cation/proton antiporters in alga, moss, and angiosperm. A phylogenetic tree was constructed showing these 240members are separated into three families, i.e., Na+/H+ exchangers, K+ efflux antiporters, and cation/H+ exchangers. Our analysis revealed that tandem and/or segmental duplications contribute to the expansion of cation/H+ exchangers in the examined angiospermspecies. Sliding windowanalysis of the nonsynonymous/synonymous substitution ratios showed some differences in the evolutionary fate of cation/proton antiporter paralogs. Furthermore, we identified over-represented motifs among these 240 proteins and foundmostmotifs are family specific, demonstrating diverse evolution of the cation/proton antiporters among three families. In addition, we investigated the co-expressed genes of the cation/proton antiporters in Arabidopsis thaliana. The results showed some biological processes are enriched in the co-expressed genes, suggesting the cation/proton antiporters may be involved in these biological processes. Taken together, this study furthers our knowledge on cation/proton antiporters in plants.

  14. Relative abundances of primary ion radicals in γ-irradiated DNA: Cytosine vs thymine anions and guanine vs adenine cations

    International Nuclear Information System (INIS)

    Sevilla, M.D.; Becker, D.; Yan, Mengyao; Summerfield, S.R.

    1991-01-01

    An ESR study of the relative distribution of ion radicals formed in DNA equilibrated with D 2 O and γ-irradiated at 77 K is presented. The ESR spectra of irradiated DNA and polynucleotides (poly[dG]·poly[dC] and poly[dAdT]·poly[dAdT]) were obtained and employed in a computer-assisted analysis for the individual ion-radical distribution. Analysis of spectra as a function of power allowed the separation of the spectra of the pyrimidine anions (T sm-bullet- , C sm-bullet- ) from the spectra of the purine cations (G sm-bullet+ , A sm-bullet+ ). The spectra of the mononucleotide ion radicals, dCMP sm-bullet- , dTMP sm-bullet- , dGMP sm-bullet+ , and dAMP sm-bullet+ , were produced in 8 M LiCl glasses. In addition, the spectra of the ion radicals of all of the mononucleotide ion radicals except dAMP + were simulated by using hyperfine and g tensors from the literature. Basis spectra derived from (1) power saturation experiments, (2) polynucleotide and mononucleotide spectra, (3) spectra of mononucleotides alone, and (4) anisotropic simulations were used to fit the spectra of DNA by use of a linear least-squares analysis. Each of the four separate analyses confirms that the cytosine anion dominates the spectra of DNA at 100 K. Three analyses included the cationic composition, and they strongly favor the guanine cation over the adenine cation. An average of the authors results gives the DNA ion radicals' relative to abundances as ca. 77% C sm-bullet- , 23% T sm-bullet- for the anions and >90% G sm-bullet+ for the cations about equal amounts of anions and cations are present. No difference in results is found for DNA irradiated in frozen D 2 O solutions or simply exchanged at 100% D 2 O humidity

  15. New Erbium Doped Antimony Glasses for Laser and Glass ...

    African Journals Online (AJOL)

    Because of the special spectroscopic properties of the rare earth ions, rare earth doped glasses are widely used in bulk and fiber lasers or amplifiers. The modelling of lasers and searching for new laser transitions require a precise knowledge of the spectroscopic properties of rare earth ions in different host glasses.

  16. Structural Glass Beams with Embedded Glass Fibre Reinforcement

    NARCIS (Netherlands)

    Louter, P.C.; Leung, Calvin; Kolstein, M.H.; Vambersky, J.N.J.A.; Bos, Freek; Louter, Pieter Christiaan; Veer, Fred

    2010-01-01

    This paper investigates the possibilities of pultruded glass fibre rods as embedded reinforcement in SentryGlas (SG) laminated glass beams. To do so, a series of pullout tests, to investigate the bond strength of the rods to the laminate, and a series of beam tests, to investigate the post-breakage

  17. Restorative Glass : Reversible, discreet restoration using structural glass components

    NARCIS (Netherlands)

    Oikonomopoulou, F.; Bristogianni, T.; Barou, L.; van Hees, R.P.J.; Nijsse, R.; Veer, F.A.; Henk, Schellen; van Schijndel, Jos

    2016-01-01

    The application of structural glass as the principal material in restoration and conservation practices is a distinguishable, yet discreet approach. The transparency of glass allows the simultaneous perception of the monument at both its original and present condition, preserving its historical and

  18. Spherical resonators coated by glass and glass-ceramic films

    Science.gov (United States)

    Ristic, Davor; Chiappini, Andrea; Chiasera, Alessandro; Armellini, Cristina; Carpentiero, Alessandro; Mazzola, Maurizio; Moser, Enrico; Varas, Stefano; Berneschi, Simone; Nunzi Conti, Gualtiero; Pelli, Stefano; Soria, Silvia; Speranza, Giorgio; Lunelli, Lorenzo; Pederzolli, Cecilia; Prudenzano, Francesco; Feron, Patrice; Ivanda, Mile; Cibiel, Gilles; Righini, Giancarlo C.; Ferrari, Maurizio

    2012-02-01

    Coating of spherical microresonators is a very promising technique for optimizing their optical properties. Optical coatings are constituted by glasses, polymer, and glass ceramics, passive or activated by luminescent species, Glass ceramic activated by rare earth ions are nanocomposite systems that exhibit specific morphologic, structural and spectroscopic properties allowing to develop interesting new physical concepts, for instance the mechanism related to the transparency, as well as novel photonic devices based on the enhancement of the luminescence. At the state of art the fabrication techniques based on bottom-up and top-down approaches appear to be viable although a specific effort is required to achieve the necessary reliability and reproducibility of the preparation protocols. In particular, the dependence of the final product on the specific parent glass and on the employed synthesis still remain an important task of the research in material science. Looking to application, the enhanced spectroscopic properties typical of glass ceramic in respect to those of the amorphous structures constitute an important point for the development of integrated optics devices, including coating of spherical microresonators. Here we present a review regarding spherical microresonators coated by glass and glass-ceramic film activated by Er3+ ions. Er3+ ions appear to be embedded in a crystalline or amorphous environment and the lifetime dynamic is influenced by the geometry and by the morphology of the system. Photoluminescence results and morphologic properties are discussed for both amorphous and glass ceramic films.

  19. Study of nuclear glasses alteration gel and synthesis of some model gels; Etude du gel d`alteration des verres nucleaires et synthese de gels modeles

    Energy Technology Data Exchange (ETDEWEB)

    Ricol, S.

    1995-10-05

    This work deals with the general problem of alteration of the reference nuclear glass R7T7. Attention is paid particularly to the altered layer formed at the glass surface during alteration process. In opposition to previous works, related essentially to glass dissolution kinetics based on chemical analyses of lixiviated elements, this thesis deals with alteration problems through structural studies of the reference glass and derived gel. This approach allows the determination of mechanisms for the gel formation and a better understanding of the behaviour of glasses towards lixiviation. Both approaches appeared complementary. Based on several spectroscopic techniques, this work showed the particular role of cations such as calcium, zirconium and iron. Studies of silica-based synthetic gels showed the synergic effect of formers cation and of one highly coordinated cation. The variation of the wavenumber related to Si-O-Si asymmetric stretching vibration can be correlated to O/Si ratio for ternary systems Si/Na/Zr. On the contrary, the Si losses of the materials depend on the number of non-bridging oxygen atoms. In the perspective of long-term behaviour, the alteration gel presents better characteristics than initial glass. It is therefore a highly stable material in static conditions. In the same way, synthetic gels are materials with very low solubilities (much lower than the alteration gel) and could be used as confining matrices. (authors). refs., 71 figs., 37 tabs.

  20. Glass ceramic fibres

    International Nuclear Information System (INIS)

    Blaschek, O.; Paulitsch, P.

    1983-01-01

    As the correlation between mineralogical phase and chemical composition influences the type of application at different high temperatures, we studied the mineralogical phases of nine crystal glass fibres of the temperature ranges 1 150 degrees Celsius (Type 1), 1 400 degrees Celsius (Type 2) and 1 500 degrees Celsius (Type 3) at various high temperatures. The methods used in the study were microscopy, X-ray diffraction, transmission electron microscopy and differential thermal analysis. The investigations showed that mullite forms in glassy fibres of the system Al 2 O 3 . SiO 2 from 850 degrees Celsius to 990 degrees Celsius as 2/1 mullite; 3/2 mullite appeared above 990 degrees Celsius besides the crystallization of cristobalite. Fibres with 95 per cent Al 2 O 3 include the phases delta-Al 2 O 3 and alpha- Al 2 O 3 and mullite. Delta- Al 2 O 3 is stable up to 1 100 degrees Celsius. Alpha-Al 2 O 3 and mullite are only stable phases at 1 400 degrees Celsius. These different crystal phases influence the quality of the technical fibre according to the stability field of glass and crystals. This study has determined that it is possible to identify different fibres from different productions by their mineralogical compositions and to relate them to the high temperature application