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Sample records for glass forming ability

  1. Glass forming ability of calcium aluminosilicate melts

    DEFF Research Database (Denmark)

    Moesgaard, Mette; Yue, Yuanzheng

    2011-01-01

    The glass forming ability (GFA) of two series of calcium aluminosilicate melts is studied by measuring their viscous behavior and crystallization tendency. The first series consists of five compositions on the joining line between the eutectic point of anorthite-wollastonite-tridymite and that of......The glass forming ability (GFA) of two series of calcium aluminosilicate melts is studied by measuring their viscous behavior and crystallization tendency. The first series consists of five compositions on the joining line between the eutectic point of anorthite......-wollastonite-tridymite and that of anorthite-wollastonite-gehlenite. The series includes the eutectic compositions as end members. The second series consists of five compositions on a line parallel to the joining line on the alumina rich side. In the present work, GFA is described in terms of glass stability, i.e., the ability of a glass...... to resist crystallization during reheating. In addition, the fragility index (m) is derived by fitting the viscosity data with the Avramov-Milchev equation. The results show that m is inversely proportional to the glass stability for the two series of melts, implying that m is an indirect measure of GFA...

  2. Glass Forming Ability in Systems with Competing Orderings

    Science.gov (United States)

    Russo, John; Romano, Flavio; Tanaka, Hajime

    2018-04-01

    Some liquids, if cooled rapidly enough to avoid crystallization, can be frozen into a nonergodic glassy state. The tendency for a material to form a glass when quenched is called "glass-forming ability," and it is of key significance both fundamentally and for materials science applications. Here, we consider liquids with competing orderings, where an increase in the glass-forming ability is signaled by a depression of the melting temperature towards its minimum at triple or eutectic points. With simulations of two model systems where glass-forming ability can be tuned by an external parameter, we are able to interpolate between crystal-forming and glass-forming behavior. We find that the enhancement of the glass-forming ability is caused by an increase in the structural difference between liquid and crystal: stronger competition in orderings towards the melting point minimum makes a liquid structure more disordered (more complex). This increase in the liquid-crystal structure difference can be described by a single adimensional parameter, i.e., the interface energy cost scaled by the thermal energy, which we call the "thermodynamic interface penalty." Our finding may provide a general physical principle for not only controlling the glass-forming ability but also the emergence of glassy behavior of various systems with competing orderings, including orderings of structural, magnetic, electronic, charge, and dipolar origin.

  3. Glass-Forming Ability of Soda Lime Borate Liquids

    DEFF Research Database (Denmark)

    Zheng, Qiuju; Mauro, J.C.; Smedskjær, Morten Mattrup

    2012-01-01

    We investigate the composition dependence of glass-forming ability (GFA) of a series of iron-containing soda lime borate liquids by substituting Na2O for B2O3. We have characterized GFA by measuring the glass stability against crystallization using a differential scanning calorimeter (DSC......). The results show that the GFA decreases when substituting Na2O for B2O3. Moreover, we find that there is no direct link between the kinetic fragility and GFA for the soda lime borate series studied herein. We have also discovered and clarified a striking thermal history dependence of the glass stability...

  4. Synthesis and devitrification of high glass-forming ability bulk metallic glasses.

    OpenAIRE

    Huang, Hong.

    2007-01-01

    In this thesis, literature on the production, microstructures and properties of bulk metallic glasses (BMG) has been reviewed with particular reference to glass forming ability (GFA) and alloys of the Fe-Zr-B and Zr-based BMG systems. The experimental procedures used in the research are presented and the results for the amorphous Fe80Zr12B8 ribbon and the Zr57Ti5Al10Cu20Ni8, Zr57Nb5Al10Cu20Ni8, Zr53Nb2Al8Cu30Ni7 BMGs are given and discussed. Wedge-shaped ingots of the Zr-based BMGs were produ...

  5. Zr-Cu-Ni-Al bulk metallic glasses with superhigh glass-forming ability

    International Nuclear Information System (INIS)

    Sun, Y.J.; Qu, D.D.; Huang, Y.J.; Liss, K.-D.; Wei, X.S.; Xing, D.W.; Shen, J.

    2009-01-01

    Zr-Cu-Ni-Al quaternary amorphous alloy compositions with varying glass-forming ability are developed by an efficient method of proportional mixing of binary eutectics. The critical diameter of the glassy sample is improved from 6 mm for Zr 53 Cu 18.7 Ni 12 Al 16.3 to 14 mm for Zr 50.7 Cu 28 Ni 9 Al 12.3 by straightforwardly adjusting the eutectic unit's coefficients. The drastic improvement in GFA is attributed to balancing the chemical affinities of the Zr, Cu, Ni and Al components in the melt prior to solidification which makes the precipitation of competing crystalline phases more difficult. As the glass-forming ability increases, the concentration of Cu in the alloys exhibits a same trend. Based on synchrotron radiation high-energy X-ray diffraction analysis and Miracle's structural model, it is envisioned that the substitution of additional Cu atoms for Zr atoms in the investigated alloys stabilizes the efficient cluster packing structure of the amorphous alloys, leading to the pronounced increase in their glass-forming ability

  6. A new parameter to evaluate the glass-forming ability of bulk metallic glasses

    International Nuclear Information System (INIS)

    Suo, Z.Y.; Qiu, K.Q.; Li, Q.F.; You, J.H.; Ren, Y.L.; Hu, Z.Q.

    2010-01-01

    Research highlights: → Develop a new criterion, i.e., Q=((T g +T x )/T l ).(ΔE/ΔH). → The reliability and benefits of the new criterion have been demonstrated in a wide range of BMG alloys. → It corresponds well with the critical diameter of BMGs investigated up to now. - Abstract: Based on the consideration of the liquid phase stability, the resistance to crystallization and the glass transition enthalpy, a new criterion Q, defined as ((T g + T x )/T l ).(ΔE/ΔH), where the T g , T x , T l , ΔE and ΔH are the glass transition temperature, the onset crystallization temperature, the liquidus temperature, the crystalline enthalpy and the fusion enthalpy, respectively, has been proposed for evaluating the glass-forming ability of bulk metallic glasses. The new criterion Q exhibits better correlation with the maximum cross section thickness (D m ) for glass formation compared with γ (=T x /(T l + T g )), T rg (=T g /T l ) and ΔT x (=T x - T g ) respectively. The available data from literatures and experiments have confirmed the effectiveness of the newly developed criterion.

  7. Copper oxide content dependence of crystallization behavior, glass forming ability, glass stability and fragility of lithium borate glasses

    International Nuclear Information System (INIS)

    Soliman, A.A.; Kashif, I.

    2010-01-01

    Differential thermal analysis (DTA) and X-ray diffraction (XRD) have been employed to investigate the copper oxide content dependence of the glass transition temperatures data, activation energy for the glass transition E t , glass stability GS, fragility index Fi, the glass-forming ability (GFA) and crystallization behavior of {(100-x) mol% Li 2 B 4 O 7 -x mol% CuO} glass samples, where x=0-40 mol% CuO. From the dependence of the glass transition temperature T g on the heating rate β, the fragility, F i , and the activation energy, E t , have been calculated. It is seen that F i and E t are attained their minimum values at 0 x -T g , SCL region and the GS. The GFA has been investigated on the basis of Hruby parameter K H , which is a strong indicator of GFA, and the relaxation time. Results of GFA are in good agreement with the fragility index, F i , calculations indicating that {90Li 2 B 4 O 7 .10CuO} is the best glass former. The stronger glass forming ability has decreasing the fragility index. XRD result indicates that no fully amorphous samples but a mixture of crystalline and amorphous phases are formed in the samples containing x>25 mol% CuO and below it composed of glassy phase. Increasing the CuO content above 25 mol% helps the crystallization process, and thus promotes a distinct SCL region. XRD suggests the presence of micro-crystallites of remaining residual amorphous matrix by increasing the CuO content.

  8. Glass forming ability and mechanical properties of Zr50Cu42Al8 bulk metallic glass

    International Nuclear Information System (INIS)

    Xia, L; Chan, K C; Wang, G; Liu, L

    2008-01-01

    In this work, we report that Zr 50 Cu 42 Al 8 bulk metallic glass (BMG) exhibits excellent glass forming ability and mechanical properties. Zr 50 Cu 42 Al 8 glassy rods with a diameter of 3 mm were prepared using conventional copper mould suction casting. The glassy rod exhibits a modulus of about 115 GPa and a fracture strength of about 2 GPa, and, as compared with other large-scale BMGs, it has excellent room-temperature plasticity of up to 20% under compression. The fracture mechanism of the rod was investigated by microstructural investigations, and it was found that the large plasticity of the as-cast rod is closely related to the in situ formation of nano-crystalline particles embedded in the amorphous matrix.

  9. Discontinuities of Plastic Deformation in Metallic Glasses with Different Glass Forming Ability

    Science.gov (United States)

    Hurakova, Maria; Csach, Kornel; Miskuf, Jozef; Jurikova, Alena; Demcak, Stefan; Ocelik, Vaclav; Hosson, Jeff Th. M. De

    The metallic ribbons Fe40Ni40B20, Cu47Ti35Zr11Ni6Si1 and Zr65Cu17.5Ni10Al7.5 with different microhardness and glass forming ability were studied at different loading rates from 0.05 to 100 mN/s. We describe in details the differences in elemental discontinuities on the loading curves for the studied alloys. It was found that the discontinuities began at a certain local deformation independently on the macroscopic mechanical properties of a ribbon. More developed discontinuities at higher deformations are created for the materials with lower microhardness and so lower strength.

  10. A thermodynamic approach towards glass-forming ability of ...

    Indian Academy of Sciences (India)

    A quantitative measure of the stability of a glass as compared to its corresponding crystalline state can be obtained by calculating ... The thermal stability of various alloy compositions is studied by ... corrosion resistance and attractive soft magnetic behaviour.1,2 .... The value of R2 determines the relationship between GFA.

  11. Glass forming ability: Miedema approach to (Zr, Ti, Hf)-(Cu, Ni) binary and ternary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Joysurya [Department of Chemical, Materials and Biomolecular Engineering, 191 Auditorium Road, University of Connecticut, Storrs 06269, CT (United States)], E-mail: jbasu@engr.uconn.edu; Murty, B.S. [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Ranganathan, S. [Department of Materials Engineering, Indian Institute of Science, Bangalore 560012 (India)

    2008-10-06

    Miedema's approach has been useful in determining the glass forming composition range for a particular alloy system. The concept of mixing enthalpy and mismatch entropy can be used in order to quantify Inoue's criteria of bulk metallic glass formation. In the present study, glass forming composition range has been determined for different binary and ternary (Zr, Ti, Hf)-(Cu, Ni) alloys based on the mixing enthalpy and mismatch entropy calculations. Though copper and nickel appear next to each other in the periodic table, the glass forming ability of the copper and nickel bearing alloys is different. Thermodynamic analysis reveals that the glass forming behaviour of Zr and Hf is similar, whereas it is different from that of Ti. The smaller atomic size of Ti and the difference in the heat of mixing of Ti, Zr, Hf with Cu and Ni leads to the observed changes in the glass forming behaviour. Enthalpy contour plots can be used to distinguish the glass forming compositions on the basis of the increasing negative enthalpy of the composition. This method reveals the high glass forming ability of binary Zr-Cu, Hf-Cu, Hf-Ni systems over a narrow composition range.

  12. Insight on the glass-forming ability of Al–Y–Ni–Ce bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Shih-Fan, E-mail: sfchen@ntut.edu.tw [Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan (China); Chen, Chih-Yuan, E-mail: chen6563@gmail.com [Department of Energy Engineering, National United University, Miaoli 36003, Taiwan (China); Lin, Chia-Hung [Institute of Materials Science and Engineering, National Taipei University of Technology, Taipei 106, Taiwan (China)

    2015-07-15

    Highlights: • Adding 1 at.% cerium to Al{sub 87}Y{sub 8}Ni{sub 5} alloy causes glass transition. • A large ΔT{sub x} indicates that (Al{sub 87}Y{sub 8}Ni{sub 5}){sub 99}Ce{sub 1} is possibly a ductile amorphous alloy. • Ce is effective in improving the thermal stability of the Al–Y–Ni amorphous alloy. • The hardness of the crystallized cerium-bearing alloy was as high as 593 Hv. - Abstract: In the present study, the role of Ce in the thermal stability and glass forming ability (GFA) of (Al{sub 87}Y{sub 8}Ni{sub 5}){sub 99}Ce{sub 1} alloy ribbons produced by a single roller melt-spinning process has been investigated in an attempt to understand the influences of multiple RE elements in an Al–TM–RE (TM: transition metal, RE: rear earth metal) alloy system. Only the (Al{sub 87}Y{sub 8}Ni{sub 5}){sub 99}Ce{sub 1} alloy ribbon showed a glass transition temperature (T{sub g}) at 483.2 K, and its ΔT{sub x} value was 41.3 K. Crystallization occurred in the temperature range of 500–750 K in three exothermic reaction stages. The peak temperature for these reactions shifted toward higher temperatures at higher heating rates. XRD and SEM analysis of annealed samples revealed that nano-sized Al particles precipitated within the amorphous matrix during the first exothermic reaction. The maximum hardness was obtained for both non-cerium and cerium addition alloys after crystallization in the 550–660 K region due to numerous nano-sized precipitates randomly and homogeneously distributed in the amorphous matrix. Moreover, from observation of the fracture surface, it is found that the fracture mode transforms from ductile to brittle when the sample is annealed at a higher crystallization temperature, at which brittle intermetallic compounds appear.

  13. New insight on glass-forming ability and designing Cu-based bulk metallic glasses: The solidification range perspective

    International Nuclear Information System (INIS)

    Wu, Jili; Pan, Ye; Li, Xingzhou; Wang, Xianfei

    2014-01-01

    Highlights: • The equation, T rg = T g /T l , was rotationally modified to T rg = κ(T m /T l ) + C/T l . • The newly generalized equation suggests a way for describing glass-forming ability. • Several new Cu-based bulk metallic glasses were discovered by solidification range. - Abstract: In this paper, a new equation was rationally generalized from the reduced glass transition temperature. This equation indicates that solidification range can be used for describing glass-forming ability, which can be calculated with the aid of computational thermodynamic approach. Based on this scenario, several new Cu-based bulk metallic glasses in the ternary Cu–Zr–Ti alloy system were discovered. The as-cast samples were characterized by X-ray diffraction and transmission electronic microscopy. The results indicate that as-cast samples have monolithic amorphous nature. Thermal analysis validates that the smaller solidification range is closely related to the higher glass-forming ability, which is contributed to the effect of solidification time on the formation of bulk metallic glasses. This work also suggests that solidus can influence glass formation

  14. Glass Forming Ability of Amorphous Drugs Investigated by Continuous Cooling and Isothermal Transformation.

    Science.gov (United States)

    Blaabjerg, Lasse I; Lindenberg, Eleanor; Löbmann, Korbinian; Grohganz, Holger; Rades, Thomas

    2016-09-06

    The aim of this study was to investigate the glass forming ability of 12 different drugs by the determination of continuous cooling and isothermal transformation diagrams in order to elucidate if an inherent differentiation between the drugs with respect to their the glass forming ability can be made. Continuous-cooling-transformation (CCT) and time-temperature-transformation (TTT) diagrams of the drugs were developed in order to predict the critical cooling rate necessary to convert the drug from the melt into an amorphous form. While TTT diagrams overestimated the actual critical cooling rate, they allowed an inherent differentiation of glass forming ability for the investigated drugs into drugs that are extremely difficult to amorphize (>750 °C/min), drugs that require modest cooling rates (>10 °C/min), and drugs that can be made amorphous even at very slow cooling rates (>2 °C/min). Thus, the glass forming ability can be predicted by the use of TTT diagrams. In contrast to TTT diagrams, CCT diagrams may not be suitable for small organic molecules due to poor separation of exothermic events, which makes it difficult to determine the zone of recrystallization. In conclusion, this study shows that glass forming ability of drugs can be predicted by TTT diagrams.

  15. Density and glass forming ability in amorphous atomic alloys: The role of the particle softness

    International Nuclear Information System (INIS)

    Douglass, Ian; Hudson, Toby; Harrowell, Peter

    2016-01-01

    A key property of glass forming alloys, the anomalously small volume difference with respect to the crystal, is shown to arise as a direct consequence of the soft repulsive potentials between metals. This feature of the inter-atomic potential is demonstrated to be responsible for a significant component of the glass forming ability of alloys due to the decrease in the enthalpy of fusion and the associated depression of the freezing point.

  16. Density and glass forming ability in amorphous atomic alloys: The role of the particle softness

    Energy Technology Data Exchange (ETDEWEB)

    Douglass, Ian; Hudson, Toby; Harrowell, Peter [School of Chemistry, University of Sydney, Sydney, NSW (Australia)

    2016-04-14

    A key property of glass forming alloys, the anomalously small volume difference with respect to the crystal, is shown to arise as a direct consequence of the soft repulsive potentials between metals. This feature of the inter-atomic potential is demonstrated to be responsible for a significant component of the glass forming ability of alloys due to the decrease in the enthalpy of fusion and the associated depression of the freezing point.

  17. Unusual glass-forming ability induced by changes in the local atomic structure in Ti-based bulk metallic glass

    International Nuclear Information System (INIS)

    Kim, Y C; Chang, H J; Kim, D H; Kim, W T; Cha, P R

    2007-01-01

    The effect of partial replacement of Cu by Be in Ti 50 Cu 32 Ni 15 Sn 3 alloy on the thermal properties, structure, and forming ability of an amorphous phase were investigated by differential scanning calorimetry (DSC), x-ray diffraction (XRD), extended x-ray absorption fine structure (EXAFS), and high-resolution transmission electron microscopy (HRTEM). Ti 50 Cu 25 Ni 15 Sn 3 Be 7 alloy shows enhanced glass-forming ability, enabling one to fabricate a fully amorphous bulk metallic glass sample 2 mm in diameter by injection casting. With the replacement, the supercooled liquid region ΔT x (= T x -T g , where T x is the crystallization temperature and T g is the glass transition temperature) decreased from 73 to 45 K and the reduced glass transition temperature T rg (= T g /T 1 , where T 1 is the liquidus temperature) increased from 0.53 to 0.57. The amorphous Ti 50 Cu 25 Ni 15 Sn 3 Be 7 phase showed a formation of short-range-ordered clusters 1-2 nm in size, which is attributed to the strong interaction between Ti and Be. The results show that ΔT x can be used as a thermal parameter reflecting the glass-forming ability of the alloy only when the phase formed during crystallization is the same as the phase competing with the glass transition during solidification

  18. Glass forming ability of amorphous drugs investigated by continuous cooling- and isothermal transformation

    DEFF Research Database (Denmark)

    Blaabjerg, Lasse Ingerslev; Lindenberg, Eleanor; Löbmann, Korbinian

    2016-01-01

    /min). Thus, the glass forming ability can be predicted by the use of TTT diagrams. In contrast to TTT diagrams, CCT diagrams may not be suitable for small organic molecules due to poor separation of exothermic events, which makes it difficult to determine the zone of recrystallization. In conclusion...

  19. Atomistic approach to predict the glass-forming ability in Zr–Cu–Al ternary metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Yu, C.Y. [Center for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, College of Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong (China); Liu, X.J. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Zheng, G.P. [Department of Mechanical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong (China); Niu, X.R. [Center for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, College of Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong (China); Liu, C.T., E-mail: chainliu@cityu.edu.hk [Center for Advanced Structural Materials, Department of Mechanical and Biomedical Engineering, College of Science and Engineering, City University of Hong Kong, Kowloon, Hong Kong (China)

    2015-04-05

    Highlights: • An atomistic approach has been developed to predict the glass forming ability (GFA) in Zr–Cu–Al ternary alloy system. • Both of the thermodynamic and structure-dependent kinetic effects to glass formation have been taken into account. • The first-principles calculation and molecular dynamics simulation have been performed. • The approach predicts the best glass former in the model Zr–Cu–Al alloy system. • The predicted GFA is consistent with various experimental results. - Abstract: Prediction of composition-dependent glass-forming ability (GFA) remains to be a key scientific challenge in the metallic-glass community, especially in multi-component alloy systems. In the present study, we apply an atomistic approach to predict the trend of GFA effectively in the Zr–Cu–Al ternary alloy system from alloy compositions alone. This approach is derived from the first-principles calculations based on the density-functional theory and molecular dynamic (MD) simulations. By considering of both the thermodynamic and atomic-structure induced kinetic effects, the predicted GFA trend from this approach shows an excellent agreement with experimental data available in this alloy system, manifesting its capability of seeking metallic glasses with superior GFA in ternary alloy systems.

  20. Effects of partitioned enthalpy of mixing on glass-forming ability

    Energy Technology Data Exchange (ETDEWEB)

    Song, Wen-Xiong; Zhao, Shi-Jin, E-mail: shijin.zhao@shu.edu.cn [Institute of Materials Science, Shanghai University, Shanghai 200072 (China)

    2015-04-14

    We explore the inherent reason at atomic level for the glass-forming ability of alloys by molecular simulation, in which the effect of partitioned enthalpy of mixing is studied. Based on Morse potential, we divide the enthalpy of mixing into three parts: the chemical part (Δ E{sub nn}), strain part (Δ E{sub strain}), and non-bond part (Δ E{sub nnn}). We find that a large negative Δ E{sub nn} value represents strong AB chemical bonding in AB alloy and is the driving force to form a local ordered structure, meanwhile the transformed local ordered structure needs to satisfy the condition (Δ E{sub nn}/2 + Δ E{sub strain}) < 0 to be stabilized. Understanding the chemical and strain parts of enthalpy of mixing is helpful to design a new metallic glass with a good glass forming ability. Moreover, two types of metallic glasses (i.e., “strain dominant” and “chemical dominant”) are classified according to the relative importance between chemical effect and strain effect, which enriches our knowledge of the forming mechanism of metallic glass. Finally, a soft sphere model is established, different from the common hard sphere model.

  1. Enhanced glass forming ability and refrigerant capacity of a Gd55Ni22Mn3Al20 bulk metallic glass

    International Nuclear Information System (INIS)

    Xia, L.; Chan, K.C.; Tang, M.B.

    2011-01-01

    Highlights: → A new Gd 55 Ni 22 Mn 3 Al 20 bulk metallic glass (BMG) was synthesized by minor Mn addition. → The BMG has enhanced glass forming ability and excellent refrigerant capacity (RC). → The RC of the BMG reaches a high value of 825 J kg -1 under a field of 3979 kA/m. → Its excellent RC is related to its large effective magnetic moment. - Abstract: In this work, a small amount of Mn was added to a Gd 55 Ni 25 Al 20 glass forming alloy, as a replacement for Ni, and a Gd 55 Ni 22 Mn 3 Al 20 bulk metallic glass (BMG) was obtained by suction casting. Its glass forming ability (GFA) was characterized by X-ray diffraction and differential scanning calorimetry, and its magnetic properties were measured using a magnetic property measurement system. It is found that the minor Mn addition can significantly improve both the GFA and the magnetocaloric effect (MCE) of the alloy. The refrigerant capacity (RC) of the BMG can reach a high value of 825 J kg -1 under a field of 3979 kA/m, which is about 29% larger than that of a Gd 55 Ni 25 Al 20 BMG. The effect of the minor Mn addition on the GFA and MCE of the BMG was investigated in the study.

  2. Effect of Nb on glass forming ability and plasticity of (Ti-Cu)-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Suo, Z.Y.; Qiu, K.Q.; Li, Q.F.; Ren, Y.L.; Hu, Z.Q.

    2010-01-01

    A Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 bulk metallic glass has been developed by Nb partial substitution for Zr in Ti 33 Cu 47 Zr 11 Ni 6 Sn 2 Si 1 alloy. The glass forming ability Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 alloy has been investigated using differential scanning calorimetry and X-ray diffractometry. Partial Nb substitutes for Zr promote the glass forming ability. Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 BMG with diameter of 3 mm can be fabricated by Cu-mold injection casting method. The glass forming ability of Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 alloy is enhanced by stabilizing the undercooled liquid against crystallization. The plastic strain up to 2.5% was obtained for Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 BMG compared to 0.15% for Ti 33 Cu 47 Zr 11 Ni 6 Sn 2 Si 1 BMG, which demonstrates that small amount of Nb addition can have a dramatic effect on plasticity enhancement in Ti-Cu-based BMG. The intersection and branching of the shear bands are observed. The plastic strain of the Ti 33 Cu 47 Zr 9 Ni 6 Sn 2 Si 1 Nb 2 BMG can be improved by the generation of nanocrystalline particles, which lead to multiple shear bands.

  3. Composition Range and Glass Forming Ability of Ternary Ca-Mg-Cu Bulk Metallic Glasses (Preprint)

    National Research Council Canada - National Science Library

    Senkov, O. N; Scott, J. M; Miracle, D. B

    2006-01-01

    .... The maximum thickness at which an alloy remains fully amorphous, glass transition temperature, crystallization temperature, temperature interval of the super-cooled region, solidus and liquidus...

  4. Effect of similar elements on improving glass-forming ability of La-Ce-based alloys

    International Nuclear Information System (INIS)

    Zhang Tao; Li Ran; Pang Shujie

    2009-01-01

    To date the effect of unlike component elements on glass-forming ability (GFA) of alloys have been studied extensively, and it is generally recognized that the main consisting elements of the alloys with high GFA usually have large difference in atomic size and atomic interaction (large negative heat of mixing) among them. In our recent work, a series of rare earth metal-based alloy compositions with superior GFA were found through the approach of coexistence of similar constituent elements. The quinary (La 0.5 Ce 0.5 ) 65 Al 10 (Co 0.6 Cu 0.4 ) 25 bulk metallic glass (BMG) in a rod form with a diameter up to 32 mm was synthesized by tilt-pour casting, for which the glass-forming ability is significantly higher than that for ternary Ln-Al-TM alloys (Ln = La or Ce; TM = Co or Cu) with critical diameters for glass-formation of several millimeters. We suggest that the strong frustration of crystallization by utilizing the coexistence of La-Ce and Co-Cu to complicate competing crystalline phases is helpful to construct BMG component with superior GFA. The results of our present work indicate that similar elements (elements with similar atomic size and chemical properties) have significant effect on GFA of alloys.

  5. Investigating the atomic level influencing factors of glass forming ability in NiAl and CuZr metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Sedighi, Sina; Kirk, Donald Walter; Singh, Chandra Veer, E-mail: chandraveer.singh@utoronto.ca; Thorpe, Steven John [Department of Materials Science and Engineering, University of Toronto, Room 140, 184 College Street, Toronto, Ontario M5S 3E4 (Canada)

    2015-09-21

    Bulk metallic glasses are a relatively new class of amorphous metal alloy which possess unique mechanical and magnetic properties. The specific concentrations and combinations of alloy elements needed to prevent crystallization during melt quenching remains poorly understood. A correlation between atomic properties that can explain some of the previously identified glass forming ability (GFA) anomalies of the NiAl and CuZr systems has been identified, with these findings likely extensible to other transition metal–transition metal and transition metal–metalloid (TM–M) alloy classes as a whole. In this work, molecular dynamics simulation methods are utilized to study thermodynamic, kinetic, and structural properties of equiatomic CuZr and NiAl metallic glasses in an attempt to further understand the underlying connections between glass forming ability, nature of atomic level bonding, short and medium range ordering, and the evolution of structure and relaxation properties in the disordered phase. The anomalous breakdown of the fragility parameter as a useful GFA indicator in TM–M alloy systems is addressed through an in-depth investigation of bulk stiffness properties and the evolution of (pseudo)Gruneisen parameters over the quench domain, with the efficacy of other common glass forming ability indicators similarly being analyzed through direct computation in respective CuZr and NiAl systems. Comparison of fractional liquid-crystal density differences in the two systems revealed 2-3 times higher values for the NiAl system, providing further support for its efficacy as a general purpose GFA indicator.

  6. Glass-Forming Ability and Early Crystallization Kinetics of Novel Cu-Zr-Al-Co Bulk Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Xiaoliang Han

    2016-09-01

    Full Text Available In recent years, CuZr-based bulk metallic glass (BMG composites ductilized by a shape memory B2 CuZr phase have attracted great attention owing to their outstanding mechanical properties. However, the B2 CuZr phase for most CuZr-based glass-forming compositions is only stable at very high temperatures, leading to the uncontrollable formation of B2 crystals during quenching. In this work, by introducing Co (i.e., 4, 5, and 6 at. % and 10 at. % Al into CuZr-based alloys, the relatively good glass-forming ability (GFA of CuZr-based alloys still can be achieved. Meanwhile, the B2 phase can be successfully stabilized to lower temperatures than the final temperatures of crystallization upon heating CuZr-based BMGs. Unlike previous reported CuZr-based BMGs, the primary crystallization products upon heating are mainly B2 CuZr crystals but not CuZr2 and Cu10Zr7 crystals. Furthermore, the primary precipitates during solidification are still dominated by B2 crystals, whose percolation threshold is detected to lie between 10 ± 2 vol. % and 31 ± 2 vol. %. The crystallization kinetics underlying the precipitation of B2 crystals was also investigated. Our results show that the present glass-forming composites are promising candidates for the fabrication of ductile CuZr-based BMG composites.

  7. Machine Learning Approach for Prediction and Understanding of Glass-Forming Ability.

    Science.gov (United States)

    Sun, Y T; Bai, H Y; Li, M Z; Wang, W H

    2017-07-20

    The prediction of the glass-forming ability (GFA) by varying the composition of alloys is a challenging problem in glass physics, as well as a problem for industry, with enormous financial ramifications. Although different empirical guides for the prediction of GFA were established over decades, a comprehensive model or approach that is able to deal with as many variables as possible simultaneously for efficiently predicting good glass formers is still highly desirable. Here, by applying the support vector classification method, we develop models for predicting the GFA of binary metallic alloys from random compositions. The effect of different input descriptors on GFA were evaluated, and the best prediction model was selected, which shows that the information related to liquidus temperatures plays a key role in the GFA of alloys. On the basis of this model, good glass formers can be predicted with high efficiency. The prediction efficiency can be further enhanced by improving larger database and refined input descriptor selection. Our findings suggest that machine learning is very powerful and efficient and has great potential for discovering new metallic glasses with good GFA.

  8. Physical stability of drugs after storage above and below the glass transition temperature: Relationship to glass-forming ability.

    Science.gov (United States)

    Alhalaweh, Amjad; Alzghoul, Ahmad; Mahlin, Denny; Bergström, Christel A S

    2015-11-10

    Amorphous materials are inherently unstable and tend to crystallize upon storage. In this study, we investigated the extent to which the physical stability and inherent crystallization tendency of drugs are related to their glass-forming ability (GFA), the glass transition temperature (Tg) and thermodynamic factors. Differential scanning calorimetry was used to produce the amorphous state of 52 drugs [18 compounds crystallized upon heating (Class II) and 34 remained in the amorphous state (Class III)] and to perform in situ storage for the amorphous material for 12h at temperatures 20°C above or below the Tg. A computational model based on the support vector machine (SVM) algorithm was developed to predict the structure-property relationships. All drugs maintained their Class when stored at 20°C below the Tg. Fourteen of the Class II compounds crystallized when stored above the Tg whereas all except one of the Class III compounds remained amorphous. These results were only related to the glass-forming ability and no relationship to e.g. thermodynamic factors was found. The experimental data were used for computational modeling and a classification model was developed that correctly predicted the physical stability above the Tg. The use of a large dataset revealed that molecular features related to aromaticity and π-π interactions reduce the inherent physical stability of amorphous drugs. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Devitrification behavior and glass-forming ability of Cu-Zr-Ag alloys

    International Nuclear Information System (INIS)

    Louzguine-Luzgin, Dmitri V.; Xie, Guoqiang; Zhang, Wei; Inoue, Akihisa

    2007-01-01

    This paper presents an influence of Ag addition on the glass-forming ability and devitrification behavior of Cu-Zr glassy alloys on heating. The crystallization kinetics and structure changes in Cu 45 Zr 45 Ag 10 and Cu 35 Zr 45 Ag 20 glassy alloys on heating were studied by X-ray diffraction, transmission electron microscopy, differential scanning and isothermal calorimetry methods. Based on the results obtained one can assume that the improvement of the glass-forming ability of the Cu-Zr alloys by the addition of Ag is connected with a particular crystallization mechanism and a higher reduced glass-transition temperature of the Cu 45 Zr 45 Ag 10 ternary alloy compared to the binary Cu 55 Zr 45 counterpart. As observed in the present work crystallization of the Cu-Zr-Ag alloys is found to cause embitterment of the samples and should be avoided as these alloys are considered to be used as structural materials. The Cu 35 Zr 45 Ag 20 alloy shows possible submicron-scale phase separation upon annealing

  10. Accuracy of a selection criterion for glass forming ability in the Ni–Nb–Zr system

    International Nuclear Information System (INIS)

    Déo, L.P.; Oliveira, M.F. de

    2014-01-01

    Highlights: • We applied a selection in the Ni–Nb–Zr system to find alloys with high GFA. • We used the thermal parameter γ m to evaluate the GFA of alloys. • The correlation between the γ m parameter and R c in the studied system is poor. • The effect of oxygen impurity reduced dramatically the GFA of alloys. • Unknown intermetallic compounds reduced the accuracy of the criterion. - Abstract: Several theories have been developed and applied in metallic systems in order to find the best stoichiometries with high glass forming ability; however there is no universal theory to predict the glass forming ability in metallic systems. Recently a selection criterion was applied in the Zr–Ni–Cu system and it was found some correlation between experimental and theoretical data. This criterion correlates critical cooling rate for glass formation with topological instability of stable crystalline structures; average work function difference and average electron density difference among the constituent elements of the alloy. In the present work, this criterion was applied in the Ni–Nb–Zr system. It was investigated the influence of factors not considered in the calculation and on the accuracy of the criterion, such as unknown intermetallic compounds and oxygen contamination. Bulk amorphous specimens were produced by injection casting. The amorphous nature was analyzed by X-ray diffraction and differential scanning calorimetry; oxygen contamination was quantified by the inert gas fusion method

  11. Influence of minor alloying additions on the glass-forming ability of Mg-Ni-La bulk metallic glasses

    International Nuclear Information System (INIS)

    Gonzalez, S.; Figueroa, I.A.; Todd, I.

    2009-01-01

    Bulk metallic glasses of Mg 60 Ni 23.6 Y x La (16.4-x) and Mg 65 Ni 20 Y x LaMM (15-x) with 0 ≤ x ≤ 1 at.% have been produced by injection casting. For the La-containing alloy a maximum amorphous diameter of 4 mm for x = 0.5 and 0.75 was obtained. The LaMM-containing alloy showed a maximum amorphous diameter of 2 mm for x = 0 and 0.25 but decreased to 1 mm with further Y additions. The glass-forming ability of the Mg 60 Ni 23.6 La 16.4 alloy decreased when La is partially substituted by small amounts of small atoms (Si or B) or by large atoms (Y and Si).

  12. Fragility of superheated melts and glass-forming ability in Pr-based alloys

    International Nuclear Information System (INIS)

    Meng, Q.G.; Zhou, J.K.; Zheng, H.X.; Li, J.G.

    2006-01-01

    The kinetic viscosity (η) of superheated melts, thermal properties (T x , T m , T L ) and X-ray diffraction analysis on the Pr-based bulk metallic glasses (BMG) are reported and discussed. A new refined concept, the superheated fragility defined as M' = E S δ x /k B , has been developed based on common solidification theory and the Arrhenius equation. The interrelationship between this kind of fragility and the glass-forming ability (GFA) is elaborated on and evaluated in Pr-based BMG and Al-based amorphous ribbon alloys. Using viscosity data of superheated melts, it is shown, theoretically and experimentally, that the fragility parameter M' may be used as a GFA indicator for metallic alloys

  13. Atomic Scale Investigation of Structural Properties and Glass Forming Ability of Ti100- x Al x Metallic Glasses

    Science.gov (United States)

    Tahiri, M.; Hasnaoui, A.; Sbiaai, K.

    2018-06-01

    In this work, we employed molecular dynamics (MD) simulations to study Ti-Al metallic glasses (MGs) using the embedded atom method (EAM) potential to model the atomic interaction with different compositions. The results showed evidence of the metallic glass formation induced by the split occurring in the second peak of the radial distribution function (RDF) curves implying both Ti and Al atoms. The common neighbor analysis (CNA) method confirmed the presence of the icosahedral clusters with a maximum amount observed for an alloy with 75 pct of Al. Analysis of coordination numbers (CNs) indicated that the total CNs are nearly unchanged in these systems. Finally, Voronoi tessellation analyses (VTA) showed a higher value of the number of icosahedral units at Ti25Al75 composition. This specific composition represents a nearby peritectic point localized at a low melting point in the Ti-Al binary phase diagram. The glass forming ability (GFA) becomes important when the fraction of Al increases by forming and connecting "icosahedral-like" clusters (12-coordinated and 13-coordinated ) and by playing a main role in the structure stability of the Ti-Al MGs.

  14. Atomic Scale Investigation of Structural Properties and Glass Forming Ability of Ti100-x Al x Metallic Glasses

    Science.gov (United States)

    Tahiri, M.; Hasnaoui, A.; Sbiaai, K.

    2018-03-01

    In this work, we employed molecular dynamics (MD) simulations to study Ti-Al metallic glasses (MGs) using the embedded atom method (EAM) potential to model the atomic interaction with different compositions. The results showed evidence of the metallic glass formation induced by the split occurring in the second peak of the radial distribution function (RDF) curves implying both Ti and Al atoms. The common neighbor analysis (CNA) method confirmed the presence of the icosahedral clusters with a maximum amount observed for an alloy with 75 pct of Al. Analysis of coordination numbers (CNs) indicated that the total CNs are nearly unchanged in these systems. Finally, Voronoi tessellation analyses (VTA) showed a higher value of the number of icosahedral units at Ti25Al75 composition. This specific composition represents a nearby peritectic point localized at a low melting point in the Ti-Al binary phase diagram. The glass forming ability (GFA) becomes important when the fraction of Al increases by forming and connecting "icosahedral-like" clusters (12-coordinated and 13-coordinated ) and by playing a main role in the structure stability of the Ti-Al MGs.

  15. Understanding the glass-forming ability of active pharmaceutical ingredients for designing supersaturating dosage forms.

    Science.gov (United States)

    Kawakami, Kohsaku; Usui, Toshinori; Hattori, Mitsunari

    2012-09-01

    Amorphous solid dispersions have great potential for enhancing oral absorption of poorly soluble drugs. Crystallization behavior during storage and after exposure to aqueous media must be examined in detail for designing stable and effective amorphous formulations, and it is significantly affected by the intrinsic properties of an amorphous drug. Many attempts have been made to correlate various thermodynamic parameters of pharmaceutical glasses with their crystallization behavior; however, variations in model drugs that could be used for such investigation has been limited because the amorphous characteristics of drugs possessing a high crystallization tendency are difficult to evaluate. In this study, high-speed differential scanning calorimetry, which could inhibit their crystallization using high cooling rates up to 2000°C/s, was employed for assessing such drugs. The thermodynamic parameters of the glasses, including glass transition temperature (T(g)) and fragility, were obtained to show that their crystallization tendency cannot be explained simply by the parameters, although there have been general thought that fragility may be correlated with crystallization tendency. Also investigated was correlation between the thermodynamic parameters and crystallization tendency upon contact with water, which influences in vivo efficacy of amorphous formulations. T(g) was correlated well with the crystallization tendency upon contact with water. Copyright © 2012 Wiley Periodicals, Inc.

  16. Glass forming ability of Al–Ni–La alloys with Si addition

    Energy Technology Data Exchange (ETDEWEB)

    Yi, J.J.; Xiong, X.Z. [State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Inoue, A. [State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); WPI-Advanced Institute for Material Research, Tohoku University, Sendai 980-8577 (Japan); Kong, L.T. [State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, J.F., E-mail: jfli@sjtu.edu.cn [State Key Laboratory of Metal Matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2015-11-25

    (Al{sub 85.5}Ni{sub 9.5}La{sub 5}){sub 100−x}Si{sub x}, (Al{sub 86}Ni{sub 9}La{sub 5}){sub 100−x}Si{sub x}, (Al{sub 86}Ni{sub 9.5}La{sub 4.5}){sub 100−x}Si{sub x}, (Al{sub 86}Ni{sub 10}La{sub 4}){sub 100−x}Si{sub x} and (Al{sub 86}Ni{sub 10.5}La{sub 3.5}){sub 100−x}Si{sub x} alloys, where x = 0.0, 0.2, 0.5, 1.0, 1.5 and 2.0, were cast under the same suction casting conditions into a wedge-shaped copper mold for investigating the effect of Si addition on the glass-forming ability (GFA). The GFA of the Al–Ni–La base alloys, except for the optimal glass former (Al{sub 85.5}Ni{sub 9.5}La{sub 5}), is enhanced when a proper content of Si is added. The largest content of Si up to which GFA can be enhanced changes in the following order of the base alloys: Al{sub 86}Ni{sub 9}La{sub 5}, Al{sub 86}Ni{sub 9.5}La{sub 4.5}, Al{sub 86}Ni{sub 10}La{sub 4} and Al{sub 86}Ni{sub 10.5}La{sub 3.5}. The enhancement of GFA due to Si addition becomes more significant as the La content decreases. This is presumably because more free Al atoms are present in the base alloy. - Highlights: • 0.2–2.0 at. % Si was added to each ternary base alloy. • Wedge-shaped samples were suction cast to obtain the glass-forming ability (GFA). • The GFA of the ternary non-optimal glass formers can be enhanced by Si addition. • The number of free-Al atoms dominates the best Si addition.

  17. Glass forming ability of Al–Ni–La alloys with Si addition

    International Nuclear Information System (INIS)

    Yi, J.J.; Xiong, X.Z.; Inoue, A.; Kong, L.T.; Li, J.F.

    2015-01-01

    (Al_8_5_._5Ni_9_._5La_5)_1_0_0_−_xSi_x, (Al_8_6Ni_9La_5)_1_0_0_−_xSi_x, (Al_8_6Ni_9_._5La_4_._5)_1_0_0_−_xSi_x, (Al_8_6Ni_1_0La_4)_1_0_0_−_xSi_x and (Al_8_6Ni_1_0_._5La_3_._5)_1_0_0_−_xSi_x alloys, where x = 0.0, 0.2, 0.5, 1.0, 1.5 and 2.0, were cast under the same suction casting conditions into a wedge-shaped copper mold for investigating the effect of Si addition on the glass-forming ability (GFA). The GFA of the Al–Ni–La base alloys, except for the optimal glass former (Al_8_5_._5Ni_9_._5La_5), is enhanced when a proper content of Si is added. The largest content of Si up to which GFA can be enhanced changes in the following order of the base alloys: Al_8_6Ni_9La_5, Al_8_6Ni_9_._5La_4_._5, Al_8_6Ni_1_0La_4 and Al_8_6Ni_1_0_._5La_3_._5. The enhancement of GFA due to Si addition becomes more significant as the La content decreases. This is presumably because more free Al atoms are present in the base alloy. - Highlights: • 0.2–2.0 at. % Si was added to each ternary base alloy. • Wedge-shaped samples were suction cast to obtain the glass-forming ability (GFA). • The GFA of the ternary non-optimal glass formers can be enhanced by Si addition. • The number of free-Al atoms dominates the best Si addition.

  18. Ductile Bulk Aluminum-Based Alloy with Good Glass-Forming Ability and High Strength

    International Nuclear Information System (INIS)

    Long-Chao, Zhuo; Shu-Jie, Pang; Hui, Wang; Tao, Zhang

    2009-01-01

    Based on a new approach for designing glassy alloy compositions, bulk Al-based alloys with good glass-forming ability (GFA) are synthesized. The cast Al 86 Si 0.5 Ni 4.06 Co 2.94 Y 6 Sc 0.5 rod with a diameter of 1 mm shows almost fully amorphous structure besides about 5% fcc-Al nucleated in the center of the rod. The bulk alloy with high Al concentration exhibits an ultrahigh yield strength of 1.18 GPa and maximum strength of 1.27 GPa as well as an obvious plastic strain of about 2.4% during compressive deformation. This light Al-based alloy with good GFA and mechanical properties is promising as a new high specific strength material with good deformability. (condensed matter: structure, mechanical and thermal properties)

  19. Effect of Si addition on glass-forming ability and mechanical properties of Cu-Zr-Al bulk metallic glass

    International Nuclear Information System (INIS)

    Malekan, M.; Shabestari, S.G.; Zhang, W.; Seyedein, S.H.; Gholamipour, R.; Makino, A.; Inoue, A.

    2010-01-01

    Research highlights: The Cu 50 Zr 43 Al 7 alloy has a surprising GFA, and the glassy rods with diameter of 10 mm have been produced in this research. It has not been reported that the Cu-based glassy rods (Cu ≥ 50 at.%) to be produced with the critical diameter greater than 10 mm. The novelty of this research is that the glass formation has been improved and the critical diameter increased to 12 mm for the alloy having x = 1 with the addition of Si. Different criteria are used to evaluate the influence of Si content on the GFA, and the possible mechanisms involved in the achievement of this GFA are also discussed. - Abstract: The effect of Si addition on the glass-forming ability (GFA) and mechanical properties of (Cu 50 Zr 43 Al 7 ) 100-x Si x (x = 0, 0.5, 1, 1.5 and 2 at.%) alloys were investigated. The GFA of Cu 50 Zr 43 Al 7 alloy is improved by addition of a small amount of Si, and the critical diameter for glass formation increases from 10 mm for the alloy with x = 0-12 mm for the alloy with x = 1 when prepared using copper mold casting. Different criteria are used to evaluate the influence of Si content on the GFA, and the possible mechanisms involved in the achievement of this GFA are also discussed. In the uniaxial compression, the bulk glassy alloys exhibit a limited plastic strain of less than 1%, but the compressive fracture strength and Young's modulus were obtained in high values of 1969-2129 MPa and 101-144 GPa, respectively. Fracture surface and shear bands of samples were studied by using scanning electron microscopy (SEM).

  20. A simple criterion to predict the glass forming ability of metallic alloys

    International Nuclear Information System (INIS)

    Falcao de Oliveira, Marcelo

    2012-01-01

    A new and simple criterion with which to quantitatively predict the glass forming ability (GFA) of metallic alloys is proposed. It was found that the critical cooling rate for glass formation (R C ) correlates well with a proper combination of two factors, the minimum topological instability (λ min ) and the Δh parameter, which depends on the average work function difference (Δφ) and the average electron density difference (Δn ws 1/3 ) among the constituent elements of the alloy. A correlation coefficient (R 2 ) of 0.76 was found between R c and the new criterion for 68 alloys in 30 different metallic systems. The new criterion and the Uhlmann's approach were used to estimate the critical amorphous thickness (Z C ) of alloys in the Cu-Zr system. The new criterion underestimated R C in the Cu-Zr system, producing predicted Z C values larger than those observed experimentally. However, when considering a scale factor, a remarkable similarity was observed between the predicted and the experimental behavior of the GFA in the binary Cu-Zr. When using the same scale factor and performing the calculation for the ternary Zr-Cu-Al, good agreement was found between the predicted and the actual best GFA region, as well as between the expected and the observed critical amorphous thickness.

  1. Y and Er minor addition effect on glass forming ability of a Ni–Nb–Zr alloy

    International Nuclear Information System (INIS)

    Deo, L.P.; Oliveira, M.F. de

    2015-01-01

    Highlights: • A theoretical selection criterion to predict the GFA was used for Ni–Nb–Zr–RE alloys. • The prediction agrees very well with thermal parameter gm used to evaluate experimentally the GFA. • RE doped alloys showed higher GFA than the base alloy. • Y and Er elements showed similar effects to improve the GFA of the base alloy. - Abstract: Since the discovering of amorphous alloys in 1960, the actual causes of why some alloys can be easily formed into glasses while others cannot, are not clearly known, thus there is no universal theory to predict the glass forming ability in metallic systems. It is well known that the minor amount addition of proper rare-earth elements can greatly enhance the glass forming ability of some glass-forming alloys. In the present study, a selection criterion was successfully used to predict the glass forming ability improvement of Ni 67.3 Nb 28.4 Zr 4.3 alloy with minor additions of Y or Er. The actual glass forming ability of the base alloy and rare-earth doped alloys were evaluated by the thermal parameter γ m and the results agree very well with the tendency predicted by the calculation. The amorphous nature of alloys was mainly analyzed by X-ray diffraction and differential scanning calorimetry. This work also presents a brief and complementary consideration about oxygen contamination quantified by the inert gas fusion method

  2. Forty years of the Hrubý glass-forming coefficient via DTA when comparing other criteria in relation to the glass stability and vitrification ability

    Czech Academy of Sciences Publication Activity Database

    Kozmidis-Petrovic, A.; Šesták, Jaroslav

    2012-01-01

    Roč. 110, č. 2 (2012), 997-1004 ISSN 1388-6150 Institutional research plan: CEZ:AV0Z10100521 Keywords : glass transition * Hrubý criterion * glass -forming ability * DTA/DSC Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.982, year: 2012

  3. Effects of Cu substitution for Fe on the glass-forming ability and soft magnetic properties for Fe-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Dou, Lintao; Liu, Haishun; Hou, Long; Xue, Lin; Yang, Weiming; Zhao, Yucheng; Chang, Chuntao

    2014-01-01

    The effects of Cu substitution for Fe on the glass-forming ability (GFA) and soft magnetic properties for Fe 72−x Cu x B 20 Si 4 Nb 4 (x=0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) bulk metallic glasses (BMGs) are investigated. It is found that the investigated BMGs exhibit large GFA as well as excellent soft magnetic properties, and proper substitution of Fe by Cu improves the saturation magnetization, coercive force, and effective permeability without obvious deterioration of the GFA. - Highlights: • Fully glassy rods of Fe 72−x Cu x B 20 Si 4 Nb 4 BMGs were produced above 1 mm in diameter. • Investigated BMGs exhibit large glass-forming ability and excellent soft magnetic properties. • Proper Cu substitution improves magnetic properties without obvious deterioration of glass-forming ability

  4. Thermodynamic and topological instability approaches for forecasting glass-forming ability in the ternary Al-Ni-Y system

    International Nuclear Information System (INIS)

    Oliveira, M.F. de; Aliaga, L.C.R.; Bolfarini, C.; Botta, W.J.; Kiminami, C.S.

    2008-01-01

    A thermodynamic approach to predict bulk glass-forming compositions in binary metallic systems was recently proposed. In this approach, the parameter γ* = ΔH amor /(ΔH inter - ΔH amor ) indicates the glass-forming ability (GFA) from the standpoint of the driving force to form different competing phases, and ΔH amor and ΔH inter are the enthalpies for glass and intermetallic formation, respectively. Good glass-forming compositions should have a large negative enthalpy for glass formation and a very small difference for intermetallic formation, thus making the glassy phase easily reachable even under low cooling rates. The γ* parameter showed a good correlation with GFA experimental data in the Ni-Nb binary system. In this work, a simple extension of the γ* parameter is applied in the ternary Al-Ni-Y system. The calculated γ* isocontours in the ternary diagram are compared with experimental results of glass formation in that system. Despite some misfitting, the best glass formers are found quite close to the highest γ* values, leading to the conclusion that this thermodynamic approach can be extended to ternary systems, serving as a useful tool for the development of new glass-forming compositions. Finally the thermodynamic approach is compared with the topological instability criteria used to predict the thermal behavior of glassy Al alloys

  5. Changes in glass formation and glass forming ability of Nd2Fe14B by the addition of TiC

    International Nuclear Information System (INIS)

    Branagan, D.J.; Iowa State Univ. of Science and Technology, Ames, IA; McCallum, R.W.; Iowa State Univ. of Science and Technology, Ames, IA

    1996-01-01

    The glass forming ability (GFA) of a stoichiometric Nd 2 Fe 14 B alloy modified with TiC additions was studied. Structural, magnetic, and thermal measurements of as-quenched melt-spun ribbons indicate increasing enhancement of GFA with increasing amounts of TiC addition. The limit of the glass formation range and the amount of glass formed at a particular cooling rate also increased with TiC addition. Enhanced GFA was concurrent with changes in the intrinsic properties of the glass. The crystallization temperature, as well as the transformation rate of crystallization, was raised by TiC addition. The intrinsic magnetic properties of the glass were changed with reductions in saturation magnetization and Curie temperature T c with increasing amounts of TiC addition. The intrinsic glass changes were related to changes in the local short range order of the glass and are consistent with a reduction in free volume and an increased packing efficiency. These changes in local structure of the glass increase the glass stability, which means that less undercooling is needed to prevent crystallization. Thus, at a particular cooling rate, a higher percentage of glass will be formed and the GFA is increased. (orig.)

  6. Effect of Ga substitution on the crystallization behaviour and glass forming ability of Zr-Al-Cu-Ni alloys

    International Nuclear Information System (INIS)

    Singh, Devinder; Yadav, T.P.; Mandal, R.K.; Tiwari, R.S.; Srivastava, O.N.

    2010-01-01

    The crystallization behaviour of melt spun Zr 69.5 Al 7.5-x Ga x Cu 12 Ni 11 (x = 0-7.5; in at.%) metallic glasses has been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The DSC traces showed changes in crystallization behaviour with substitution of Ga. Formation of single nano-quasicrystalline phase by controlled crystallization of glasses has been found only for 0 ≤ x ≤ 1.5. Further increase of Ga content gives rise to formation of the quasicrystals together with Zr 2 Cu type crystalline phase. In addition to this, the substitution of Ga influences the size and shape of nano-quasicrystals. The glass forming abilities (GFAs) of these metallic glasses were assessed by the recognition of glass forming ability indicators, i.e. reduced glass transition temperature (T rg ) and supercooled liquid region (ΔT x ). The glass transition temperature (T g ) has been observed for all the melt spun ribbons.

  7. The glass-forming ability of model metal-metalloid alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai; Liu, Yanhui; Schroers, Jan [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Shattuck, Mark D. [Department of Physics and Benjamin Levich Institute, The City College of the City University of New York, New York, New York 10031 (United States); Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); O’Hern, Corey S. [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States)

    2015-03-14

    Bulk metallic glasses (BMGs) are amorphous alloys with desirable mechanical properties and processing capabilities. To date, the design of new BMGs has largely employed empirical rules and trial-and-error experimental approaches. Ab initio computational methods are currently prohibitively slow to be practically used in searching the vast space of possible atomic combinations for bulk glass formers. Here, we perform molecular dynamics simulations of a coarse-grained, anisotropic potential, which mimics interatomic covalent bonding, to measure the critical cooling rates for metal-metalloid alloys as a function of the atomic size ratio σ{sub S}/σ{sub L} and number fraction x{sub S} of the metalloid species. We show that the regime in the space of σ{sub S}/σ{sub L} and x{sub S} where well-mixed, optimal glass formers occur for patchy and LJ particle mixtures, coincides with that for experimentally observed metal-metalloid glass formers. Thus, our simple computational model provides the capability to perform combinatorial searches to identify novel glass-forming alloys.

  8. The fundamental structural factor in determining the glass-forming ability and mechanical behavior in the Cu-Zr metallic glasses

    International Nuclear Information System (INIS)

    Sha, Z.D.; Feng, Y.P.; Li, Y.

    2011-01-01

    Research highlights: → A weak but significant hump in trend of the coordinate number and density was observed, respectively. → Our findings indicate our simulation is more accurate to describe the atomic structure of Cu-Zr MGs. The composition-structure-properties correlation was established. → And the effective structural unit for this correlation is the Cu-centered full icosahedra. - Abstract: Using the large-scale atomic/molecular massively parallel simulator, the quantitative composition-structure-properties (including glass-forming ability (GFA) and mechanical behavior) correlations in the Cu-Zr metallic glasses were established. The atomic-level origin of these correlations was tracked down. It was found that the Cu-centered full icosahedron is the microscopic factor that fundamentally influences both GFA and mechanical behavior. Our findings have implications for understanding the nature, forming ability and properties of metallic glasses, and for searching novel metallic glasses with unique functional properties.

  9. Structural Origin of the Enhanced Glass-Forming Ability Induced by Microalloying Y in the ZrCuAl Alloy

    Directory of Open Access Journals (Sweden)

    Gu-Qing Guo

    2016-03-01

    Full Text Available In this work, the structural origin of the enhanced glass-forming ability induced by microalloying Y in a ZrCuAl multicomponent system is studied by performing synchrotron radiation experiments combined with simulations. It is revealed that the addition of Y leads to the optimization of local structures, including: (1 more Zr-centered and Y-centered icosahedral-like clusters occur in the microstructure; (2 the atomic packing efficiency inside clusters and the regularity of clusters are both enhanced. These structural optimizations help to stabilize the amorphous structure in the ZrCuAlY system, and lead to a high glass-forming ability (GFA. The present work provides an understanding of GFAs in multicomponent alloys and will shed light on the development of more metallic glasses with high GFAs.

  10. Glass-forming ability and crystallization behavior of some binary and ternary Ni-based glassy alloys

    International Nuclear Information System (INIS)

    Louzguine-Luzgin, Dmitri V.; Louzguina-Luzgina, Larissa V.; Xie Guoqiang; Li Song; Zhang Wei; Inoue, Akihisa

    2008-01-01

    The purpose of the current paper is to study the influence of Ti, V, Nb, Al, Sn and Pd additions on the glass-forming ability, formation of a supercooled liquid region and a devitrification process of some Ni-Zr glassy alloys as well as to compare the results with those obtained for similar Cu-based alloys studied earlier. The Ni-based glassy alloys were investigated by using X-ray diffraction, differential scanning and isothermal calorimetries. Although the studied Ni-based alloys showed high values of the reduced glass-transition temperature of about 0.6, their glass-forming ability is quite low. This fact may be explained by low stability of the supercooled liquid against crystallization and formation of the equilibrium intermetallic compounds with a high growth rate compared to those observed in similar Cu-based alloys studied earlier. Relatively low thermal conductivity of Ni-based alloys is also found to be another factor limiting their glass-forming ability

  11. Improvement of corrosion resistance in NaOH solution and glass forming ability of as-cast Mg-based bulk metallic glasses by microalloying

    Directory of Open Access Journals (Sweden)

    Peng Hao

    2011-02-01

    Full Text Available The influences of the addition of Ag on the glass forming ability (GFA and corrosion behavior were investigated in the Mg-Ni-based alloy system by X-ray diffraction (XRD and electrochemical polarization in 0.1 mol/L NaOH solution. Results shows that the GFA of the Mg-Ni-based BMGs can be improved dramatically by the addition of an appropriate amount of Ag; and the addition element Ag can improve the corrosion resistance of Mg-Ni-based bulk metallic glass. The large difference in atomic size and large negative mixing enthalpy in alloy system can contribute to the high GFA. The addition element Ag improves the forming speed and the stability of the passive film, which is helpful to decrease the passivation current density and to improve the corrosion resistance of Mg-Ni-based bulk metallic glass.

  12. A new Ti-Zr-Hf-Cu-Ni-Si-Sn bulk amorphous alloy with high glass-forming ability

    International Nuclear Information System (INIS)

    Huang, Y.J.; Shen, J.; Sun, J.F.; Yu, X.B.

    2007-01-01

    The effect of Sn substitution for Cu on the glass-forming ability was investigated in Ti 41.5 Zr 2.5 Hf 5 Cu 42.5-x Ni 7.5 Si 1 Sn x (x = 0, 1, 3, 5, 7) alloys by using differential scanning calorimetry (DSC) and X-ray diffractometry. The alloy containing 5% Sn shows the highest glass-forming ability (GFA) among the Ti-Zr-Hf-Cu-Ni-Si-Sn system. Fully amorphous rod sample with diameters up to 6 mm could be successfully fabricated by the copper mold casting Ti 41.5 Zr 2.5 Hf 5 Cu 37.5 Ni 7.5 Si 1 Sn 5 alloy. The activation energies for glass transition and crystallization for Ti 41.5 Zr 2.5 Hf 5 Cu 37.5 Ni 7.5 Si 1 Sn 5 amorphous alloy are both larger than those values for the Sn-free alloy. The enhancement in GFA and thermal stability after the partial replacement of Cu by Sn may be contributed to the strong atomic bonding nature between Ti and Sn and the increasing of atomic packing density. The amorphous Ti 41.5 Zr 2.5 Hf 5 Cu 37.5 Ni 7.5 Si 1 Sn 5 alloy also possesses superior mechanical properties

  13. Effect of Yttrium Addition on Glass-Forming Ability and Magnetic Properties of Fe–Co–B–Si–Nb Bulk Metallic Glass

    Directory of Open Access Journals (Sweden)

    Teruo Bitoh

    2015-06-01

    Full Text Available The glass-forming ability (GFA and the magnetic properties of the [(Fe0.5Co0.50.75B0.20Si0.05]96Nb4−xYx bulk metallic glasses (BMGs have been studied. The partial replacement of Nb by Y improves the thermal stability of the glass against crystallization. The saturation mass magnetization (σs exhibits a maximum around 2 at. % Y, and the value of σs of the alloy with 2 at. % Y is 6.5% larger than that of the Y-free alloy. The coercivity shows a tendency to decrease with increasing Y content. These results indicate that the partial replacement of Nb by Y in the Fe–Co–B–Si–Nb BMGs is useful to simultaneous achievement of high GFA, high σs, and good soft magnetic properties.

  14. A unified in vitro evaluation for apatite-forming ability of bioactive glasses and their variants.

    Science.gov (United States)

    Maçon, Anthony L B; Kim, Taek B; Valliant, Esther M; Goetschius, Kathryn; Brow, Richard K; Day, Delbert E; Hoppe, Alexander; Boccaccini, Aldo R; Kim, Ill Yong; Ohtsuki, Chikara; Kokubo, Tadashi; Osaka, Akiyoshi; Vallet-Regí, Maria; Arcos, Daniel; Fraile, Leandro; Salinas, Antonio J; Teixeira, Alexandra V; Vueva, Yuliya; Almeida, Rui M; Miola, Marta; Vitale-Brovarone, Chiara; Verné, Enrica; Höland, Wolfram; Jones, Julian R

    2015-02-01

    The aim of this study was to propose and validate a new unified method for testing dissolution rates of bioactive glasses and their variants, and the formation of calcium phosphate layer formation on their surface, which is an indicator of bioactivity. At present, comparison in the literature is difficult as many groups use different testing protocols. An ISO standard covers the use of simulated body fluid on standard shape materials but it does not take into account that bioactive glasses can have very different specific surface areas, as for glass powders. Validation of the proposed modified test was through round robin testing and comparison to the ISO standard where appropriate. The proposed test uses fixed mass per solution volume ratio and agitated solution. The round robin study showed differences in hydroxyapatite nucleation on glasses of different composition and between glasses of the same composition but different particle size. The results were reproducible between research facilities. Researchers should use this method when testing new glasses, or their variants, to enable comparison between the literature in the future.

  15. Effects of Nb addition on icosahedral quasicrystalline phase formation and glass-forming ability of Zr--Ni--Cu--Al metallic glasses

    International Nuclear Information System (INIS)

    Fan, Cang; Li, Chunfei; Inoue, Akihisa; Haas, Volker

    2001-01-01

    This work shows that the crystallization process of Zr--Ni--Cu--Al metallic glass is greatly influenced by adding Nb as an alloying element. Based on the results of the differential scanning calorimetry experiments for metallic glasses Zr 69-x Nb x Ni 10 Cu 12 Al 9 (x=0--15at.%), the crystallization process takes place through two individual stages. For Zr 69 Ni 10 Cu 12 Al 9 (x=0), metastable hexagonal ω-Zr and a small fraction of tetragonal Zr 2 Cu are precipitated upon completion of the first exothermic reaction. Contrary to this alloy, the precipitation of a nanoquasicrystalline phase is detected when 5--10 at.% Nb is added. Furthermore, the crystallization temperature T x , supercooled liquid region ΔT x and reduced temperature T g /T L (T g is the glass transition temperature, T L the liquidus temperature) increase with increasing Nb content. These results indicate that adding Nb content to Zr--Ni--Cu--Al metallic glasses not only induces quasicrystalline phase formation, but also enhances glass-forming ability. Copyright 2001 American Institute of Physics

  16. A new Ti-Zr-Hf-Cu-Ni-Si-Sn bulk amorphous alloy with high glass-forming ability

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Y.J. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Shen, J. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)]. E-mail: junshen@hit.edu.cn; Sun, J.F. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Yu, X.B. [Lab of Energy Science and Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)]. E-mail: yuxuebin@hotmail.com

    2007-01-16

    The effect of Sn substitution for Cu on the glass-forming ability was investigated in Ti{sub 41.5}Zr{sub 2.5}Hf{sub 5}Cu{sub 42.5-x}Ni{sub 7.5}Si{sub 1}Sn {sub x} (x = 0, 1, 3, 5, 7) alloys by using differential scanning calorimetry (DSC) and X-ray diffractometry. The alloy containing 5% Sn shows the highest glass-forming ability (GFA) among the Ti-Zr-Hf-Cu-Ni-Si-Sn system. Fully amorphous rod sample with diameters up to 6 mm could be successfully fabricated by the copper mold casting Ti{sub 41.5}Zr{sub 2.5}Hf{sub 5}Cu{sub 37.5}Ni{sub 7.5}Si{sub 1}Sn{sub 5} alloy. The activation energies for glass transition and crystallization for Ti{sub 41.5}Zr{sub 2.5}Hf{sub 5}Cu{sub 37.5}Ni{sub 7.5}Si{sub 1}Sn{sub 5} amorphous alloy are both larger than those values for the Sn-free alloy. The enhancement in GFA and thermal stability after the partial replacement of Cu by Sn may be contributed to the strong atomic bonding nature between Ti and Sn and the increasing of atomic packing density. The amorphous Ti{sub 41.5}Zr{sub 2.5}Hf{sub 5}Cu{sub 37.5}Ni{sub 7.5}Si{sub 1}Sn{sub 5} alloy also possesses superior mechanical properties.

  17. Influence of Y, Gd and Sm on the glass forming ability and thermal crystallization of aluminum based alloy

    International Nuclear Information System (INIS)

    Aliaga, L.C.R.; Bolfarini, C.; Kiminami, C.S.; Botta Filho, W.J.; Danez, G.P.

    2010-01-01

    Al-based amorphous alloys represent an important family of metals and a great scientific activity has been devoted to determine the main features of both glass forming ability (GFA) and crystallization behavior in order to have a comprehensive framework aimed at potential technological applications. Nowadays, it is well known that the best Al-based amorphous alloys are formed in ternary systems such as Al- RE-TM, where RE is a rare earth and TM a transition metal. This paper presents results of research in Al 85 Ni 10 RE 5 alloys (RE = Y, Gd and Sm). Amorphous ribbons were processed by melt-spinning under the same conditions and subsequently characterized by x-ray diffraction (XRD) and differential scanning calorimetry (DSC). Results show appreciable micro structural differences as function of the rare earth, thus crystal is obtained for Y, nano-glassy for Gd and, fully amorphous structure for Sm. (author)

  18. Glass-forming ability and stability of ternary Ni-early transition metal (Ti/Zr/Hf) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Joysurya [Department of Metallurgy, Indian Institute of Science, Bangalore 560 012 (India); Ranganathan, S. [Department of Metallurgy, Indian Institute of Science, Bangalore 560 012 (India)]. E-mail: rangu@met.iisc.ernet.in

    2006-08-15

    Four Ni-bearing Ti, Zr and Hf ternary alloys of nominal composition Zr{sub 41.5}Ti{sub 41.5}Ni{sub 17}, Zr{sub 25}Ti{sub 25}Ni{sub 50}, Zr{sub 41.5}Hf{sub 41.5}Ni{sub 17} and Ti{sub 41.5}Hf{sub 41.5}Ni{sub 17} were rapidly solidified in order to produce ribbons. The Zr-Ti-Ni and Ti-Hf-Ni alloys become amorphous, whereas the Zr-Hf-Ni alloy shows precipitation of a cubic phase. The devitrification of all three alloys was followed and the relative tendency to form nanoquasicrystals and cF96 phases analysed. The relative glass-forming ability of the alloys can be explained by taking into account their atomic size difference. Addition of Ni often leads to quasicrystallisation or quasicrystal-related phases. This can be explained by the atomic radius and heat of mixing of the constituent elements. The phases precipitated at the initial stages of crystallisation indicate the possible presence of Frank-Kasper polyhedral structure in the amorphous alloys. Structural analysis reveals that the Laves and the anti-Laves phases have the same polyhedral structural unit, which is similar to the structural characteristics of glass.

  19. Composition dependency of the glass forming ability (GFA) in Mg-Ni-Si system by mechanical alloying

    International Nuclear Information System (INIS)

    Xie Haowen; Lin Jianguo; Li Yuncang; Hodgson, Peter D.; Wen Cuie

    2007-01-01

    The pure elemental powder mixtures with the compositions of Mg 65 Ni x Si 35-x (x = 10, 20, 25, 33 at.%) were subject to high-energy ball mill, and the structures of the mixtures at different intervals of milling were characterised by X-ray diffraction (XRD). The compositional dependency of the glass forming ability (GFA) in Mg-Ni-Si system was evaluated based on the experimental results and the theoretical calculation. The compositional dependency of GFA in Mg-Ni-Si system can be understood well by comparing the enthalpies of the crystalline and amorphous phases based on the Miedema's theory for the formation enthalpy of alloys. Increasing the Ni/Mg ratio and/or decreasing Si content can improve the amorphous formability. The calculation results might be of great help in optimising the composition with high GFA in Mg-Ni-Si system

  20. Electronic-structure origin of the glass-forming ability and magnetic properties in Fe–RE–B–Nb bulk metallic glasses

    International Nuclear Information System (INIS)

    Li, J.W.; Estévez, D.; Jiang, K.M.; Yang, W.M.; Man, Q.K.; Chang, C.T.; Wang, X.M.

    2014-01-01

    Highlights: • Relation between GFA and electronic structure of RE doped BMGs is investigated. • Tm enhances RE–B bonds and decreases the density of states near the Fermi level. • Magnetic properties of the alloys are related to the electronic structure of RE. - Abstract: (Fe 0.71 RE 0.05 B 0.24 ) 96 Nb 4 (RE = Gd, Tb, Ho, Er, Tm) bulk metallic glasses (BMGs) were found exhibiting excellent glass-forming ability (GFA) with critical diameters ranging from 3.5 to 6.5 mm, and high compressive fracture strength larger than 4300 MPa. Moreover, they displayed good soft-magnetic properties with saturation magnetic flux density of 0.71–0.87 T, coercive force of 1.23–39.76 A/m and effective permeability of 1500–12,740 at 1 kHz. X-ray photoelectron spectroscopy was performed to clarify the origin of the excellent GFA from the viewpoint of electronic structure. It was found that the Tm doped alloy displayed unique electronic structure including the deepest core-level binding energy, the most numerous RE–B bonds and the minimum density of states near the Fermi level, making this alloy the best glass former. The various trends noticed in the magnetic properties were ascribed mainly to the differences in the magnetic anisotropy and magnetic moment of RE elements

  1. Effect of Si addition on the glass-forming ability of a NiTiZrAlCu alloy

    International Nuclear Information System (INIS)

    Liang, W.Z.; Shen, J.; Sun, J.F.

    2006-01-01

    The effect of Si addition on the glass-forming ability (GFA) of a NiTiZrAlCu alloy was investigated by using differential scanning calorimetry (DSC), differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The maximum diameter of glassy rods increased from 0.5 mm for the Ni 42 Ti 20 Zr 25 Al 8 Cu 5 alloy (the base alloy) to 2.5 mm for the Ni 42 Ti 20 Zr 21.5 Al 8 Cu 5 Si 3.5 alloy and to 3 mm for the Ni 42 Ti 19 Zr 22.5 Al 8 Cu 5 Si 3.5 alloy, when prepared by using the copper mould casting. The GFA of the alloys can be assessed by the reduced glass transition temperature T rg (=T g /T l ) and a newly proposed parameter, δ(=T x /T l - T g ). An addition of a proper amount of Si and a minor substitution of Ti with Zr can enhance the GFA of the base alloy by suppressing the formation of primary Ni(TiZr) and (TiZr)(CuAl) 2 phases and inducing the composition close to eutectic

  2. Dependence of glass-forming ability on starting compositions in Y2O3–Al2O3–SiO2 system

    OpenAIRE

    Yixiang Chen; Zengchao Yang; Bin He; Guanghua Liu; Jiangtao Li; Liang Wu

    2011-01-01

    The dependence of glass-forming ability on starting compositions in Y2O3–Al2O3–SiO2 (YAS) system has been investigated by melting experiment. Transparent YAS glasses have been prepared under the condition of furnace cooling instead of quenching. It is found that, in the YAS ternary phase diagram, the compositions on the Y3Al5O12–SiO2 line and with 52-68 mol% SiO2 have a higher glass-forming ability to produce pure glass. For the compositions with too much or less SiO2 or with Y/Al = 5/3, 1/1,...

  3. Glass forming ability of the Fe-Zr-Cu system studied by thermodynamic calculation and ion beam mixing

    International Nuclear Information System (INIS)

    Wang, T.L.; Liu, B.X.

    2009-01-01

    The glass forming ability/range (GFA/GFR) of the Fe-Zr-Cu system was studied by thermodynamic calculation based on Miedema's model and Alonso's method. It is found that when the atomic concentration of Zr is between 34% and 56%, no matter what the atomic concentrations of Fe and Cu are, amorphous phase could be obtained, thus the atomic mismatch playing a dominating role in influencing the GFA. While the atomic concentration of Zr is out of the above range, the GFA is highly influenced by the immiscibility between Fe and Cu. Experimentally, ion beam mixing was carried out to synthesize amorphous alloys in the Fe-Zr-Cu system. It turned out that in the samples with overall compositions of Fe 26 Zr 36 Cu 38 , Fe 52 Zr 27 Cu 21 and Fe 21 Zr 60 Cu 19 , which are located in or at the edge of the calculated GFR, amorphous phases were indeed obtained, whereas no amorphous phase was obtained if the overall compositions were located outside of the predicted region favoring for amorphous alloy formation, showing a good agreement between the experimental results and the thermodynamic calculation.

  4. Strong composition-dependence on glass-forming ability in Ni-(Ti,Zr)-Si pseudo-ternary alloys

    International Nuclear Information System (INIS)

    Yang, H.; Wang, J.Q.; Li, Y.

    2006-01-01

    The glass formation in Ni-(Ti,Zr)-Si pseudo-ternary alloys was studied. For suction casting, by carefully adjusting the alloy composition and studying the microstructure changes, the best glass-forming alloy with a 2 mm diameter is pinpointed in a narrow composition region of 57.5-58.5 at.% Ni, 36.5-38.5 at.% (Ti + Zr) and 5-5.5 at.% Si. The main competing crystalline phases, identified by XRD and SEM, were Ni 10 (Zr,Ti) 7 , Ni(Ti,Zr) and an unidentified Si-containing phase. Our results indicate a clear need for monitoring the microstructure change in the cross section of the ingots to locate the best glass-forming alloys

  5. Study on glass-forming ability and hydrogen storage properties of amorphous Mg60Ni30La10−xCox (x = 0, 4) alloys

    International Nuclear Information System (INIS)

    Lv, Peng; Wang, Zhong-min; Zhang, Huai-gang; Balogun, Muhammad-Sadeeq; Ji, Zi-jun; Deng, Jian-qiu; Zhou, Huai-ying

    2013-01-01

    Mg 60 Ni 30 La 10−x Co x (x = 0, 4) amorphous alloys were prepared by rapid solidification, using a melt-spinning technique. X-ray diffraction and differential scanning calorimetry analysis were employed to measure their microstructure, thermal stability and glass-forming ability, and hydrogen storage properties were studied by means of PCTPro2000. Based on differential scanning calorimetry results, their glass-forming ability and thermal stability were investigated by Kissinger method, Lasocka curves and atomic cluster model, respectively. The results indicate that glass-forming ability, thermal properties and hydrogen storage properties in the Mg-rich corner of Mg–Ni–La–Co system alloys were enhanced by Co substitution for La. It can be found that the smaller activation energy (ΔΕ) and frequency factor (υ 0 ), the bigger value of B (glass transition point in Lasocka curves), and higher glass-forming ability of Mg–Ni–La–Co alloys would be followed. In addition, atomic structure parameter (λ), deduced from atomic cluster model is valuable in the design of Mg–Ni–La–Co system alloys with good glass-forming ability. With an increase of Co content from 0 to 4, the hydrogen desorption capacity within 4000 s rises from 2.25 to 2.85 wt.% at 573 K. - Highlights: • Amorphous Mg 60 Ni 30 La 10−x Co x (x = 0 and 4) alloys were produced by melt spinning. • The GFA and hydrogen storage properties were enhanced by Co substitution for La. • With an increase of Co content, the hydrogen desorption capacity rises at 573 K

  6. Effect of solute atoms on glass-forming ability for Fe–Y–B alloy: An ab initio molecular dynamics study

    International Nuclear Information System (INIS)

    Han, J.J.; Wang, W.Y.; Liu, X.J.; Wang, C.P.; Hui, X.D.; Liu, Z.K.

    2014-01-01

    The glass-forming abilities of Fe 78 B 22 , Fe 70 Y 6 B 24 , Fe 72 Y 6 B 22 and Fe 72.5 Y 3.5 B 24 alloys were characterized comprehensively using ab initio molecular dynamics simulations. The calculated results were correlated with the properties and atomic structures. It was found that the Fe 72 Y 6 B 22 alloy consists of both the most stable and the least deformed body centered cubic atomic packing structures in the supercooled liquid and glassy states. It was observed that the local compositions in the Fe 72 Y 6 B 22 alloy significantly deviate from the compositions of stable crystalline phases, indicating that the Fe 72 Y 6 B 22 alloy has the best glass-forming ability among the alloys studied. However, Fe 72 Y 6 B 22 alloy has two flaws in terms of glass-forming ability, i.e. relatively large atomic diffusivity and insufficiently close atomic packing. The best performance in these two aspects is observed in the Fe 72.5 Y 3.5 B 24 alloy. Thus, the theoretical study predicts that the best glass former for the Fe–Y–B system is within the compositional range of 22–24 at.% B and 3.5–6 at.% Y

  7. Dependence of glass-forming ability on starting compositions in Y2O3–Al2O3–SiO2 system

    Directory of Open Access Journals (Sweden)

    Yixiang Chen

    2011-09-01

    Full Text Available The dependence of glass-forming ability on starting compositions in Y2O3–Al2O3–SiO2 (YAS system has been investigated by melting experiment. Transparent YAS glasses have been prepared under the condition of furnace cooling instead of quenching. It is found that, in the YAS ternary phase diagram, the compositions on the Y3Al5O12–SiO2 line and with 52-68 mol% SiO2 have a higher glass-forming ability to produce pure glass. For the compositions with too much or less SiO2 or with Y/Al = 5/3, 1/1, or 1/3, crystallization occurs with the formation of Y3Al5O12, Y2Si2O7, Al6Si2O13, or SiO2. The densities of the YAS glasses increase with decreasing SiO2 contents and increasing Y/Al ratios, and for the samples with Y/Al = 3/5 there is a good linear relationship between the density and SiO2 content.

  8. Thermal stability and glass-forming ability of amorphous Nd-Al-TM (TM=Fe, Co, Ni or Cu) alloys

    International Nuclear Information System (INIS)

    Inoue, A.; Zhang Tao

    1997-01-01

    Bulk amorphous alloys were prepared for Nd 70 Al 10 TM 20 and Nd 60 Al 10 TM 30 (TM=Fe or Co) alloys by copper mold casting. The maximum sample thickness for glass formation reaches 15 mm for the Nd-Al-Fe alloys and 5 mm for the Nd-Al-Co alloys. A significant difference in the phase transition upon heating is recognized between the Fe- and Co-containing alloys. No glass transition before crystallization is observed for the Nd-Al-Fe alloys, but the Nd-Al-Co alloys exhibit the glass transition. The ΔT x (=T x -T g ) and T g /T m are 40-55 K and 0.65-0.67, respectively, for the latter alloys. The absence of supercooled liquid for the former alloys is different from those for all bulk amorphous alloys reported up to date. The T x /T m and ΔT m (=T m -T x ) are 0.85-0.89 and 88-137 K, respectively, for the Nd-Al-Fe alloys and, hence, the large glass-forming ability is presumably due to the high T x /T m and small ΔT m values. (orig.)

  9. Effect of P addition on glass forming ability and soft magnetic properties of melt-spun FeSiBCuC alloy ribbons

    International Nuclear Information System (INIS)

    Xu, J.; Yang, Y.Z.; Li, W.; Chen, X.C.; Xie, Z.W.

    2016-01-01

    The dependency of phosphorous content on the glass forming ability, thermal stability and soft magnetic properties of Fe 83.4 Si 2 B 14−x P x Cu 0.5 C 0.1 (x=0,1,2,3,4) alloys was investigated. The experimental results showed that the substitution of B by P increased the glass forming ability in this alloy system. The Fe 83.4 Si 2 B 10 P 4 Cu 0.5 C 0.1 alloy shows a fully amorphous character. Thermal stability of melt-spun ribbons increases and temperature interval between the first and second crystallization peaks enlarges with the increase of P content. And the saturation magnetic flux density (Bs) shows a slight increase with the increase of P content. The Fe 83.4 Si 2 B 11 P 3 Cu 0.5 C 0.1 nanocrystalline alloy exhibits a high Bs about 200.6 emu/g. The Bs of fully amorphous alloy Fe 83.4 Si 2 B 10 P 4 Cu 0.5 C 0.1 drops dramatically to 172.1 emu/g, which is lower than that of other nanocrystallines. Low material cost and excellent soft magnetic properties make the FeSiBPCuC alloys promise soft magnetic materials for industrial applications. - Highlights: • Partial substituting B by P helps to improve the glass forming ability of the alloy. • The addition of P content reduces the thermal stability and improves heat treatment temperature region for these alloys. • The Fe 83.4 Si 2 B 11 P 3 Cu 0.5 C 0.1 nanocrystalline alloy exhibits a high saturation magnetic density of 200.6 emu/g.

  10. Effect of Si on the glass-forming ability, thermal stability and magnetic properties of Fe-Co-Zr-Mo-W-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, W.-M. [Institute for Metallic Materials, IFW Dresden, P.O. 270016, Dresden D-01171 (Germany); Key Lab of Liquid Structure and Heredity of Materials, Shandong University, Jinan 250061 (China); Gebert, A. [Institute for Metallic Materials, IFW Dresden, P.O. 270016, Dresden D-01171 (Germany)], E-mail: a.gebert@ifw-dresden.de; Roth, S.; Kuehn, U.; Schultz, L. [Institute for Metallic Materials, IFW Dresden, P.O. 270016, Dresden D-01171 (Germany)

    2008-07-14

    This paper presents investigations on the effect of Si on the glass-forming ability, thermal stability and magnetic properties of the Fe-Co-Zr-Mo-W-B samples (group I: Fe{sub 60}Co{sub 8}Zr{sub 10}Mo{sub 5}W{sub 2}B{sub 15-x}Si{sub x}, 1 {<=} x {<=} 4; group II: Fe{sub 60}Co{sub 8}Zr{sub 10-x}Mo{sub 5}W{sub 2}B{sub 15}Si{sub x}, 0 {<=} x {<=} 4; group III: Fe{sub 60}Co{sub 8}Zr{sub 8}Mo{sub 5}W{sub 2}B{sub 17-x}Si{sub x}, 0 {<=} x {<=} 2) prepared by melt spinning, injection casting, and centrifugal casting methods. It is found that the glass-forming ability (GFA) of the alloys in group I is more deteriorated than that in group II, and that the alloys in group III can be cast into the rods of 1-3 mm diameter without crystalline reflections in their XRD patterns. For the amorphous ribbons and rods, a non-monotonic change of the nearest neighbour distance r{sub 1} with increasing Si content c{sub Si} was detected, which is parallel to that of the glass transition and crystallization temperatures T{sub g} and T{sub x}, but opposite to that of the magnetization at room temperature M{sub RT} and the Curie temperature T{sub c}. This correlation can be interpreted by a structure model presuming that iron atoms appear simultaneously in two types of local structures in the amorphous samples.

  11. Effect of Mo-Fe substitution on glass forming ability, thermal stability, and hardness of Fe-C-B-Mo-Cr-W bulk amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Khalifa, Hesham E.; Cheney, Justin L. [University of California, San Diego Materials Science and Engineering Program, 9500 Gilman Drive, La Jolla, CA 92093-0411 (United States); Vecchio, Kenneth S. [University of California, San Diego Department of NanoEngineering, 9500 Gilman Drive, La Jolla, CA 92093-0411 (United States)], E-mail: kvecchio@ucsd.edu

    2008-08-25

    Amorphous Fe{sub 67-x}C{sub 10}B{sub 9}Mo{sub 7+x}Cr{sub 4}W{sub 3} (x = 1-7 at.%) plates with 640 {mu}m thickness were prepared by copper mold casting. The thermal properties and microstructural development during heat treatments were investigated by a combination of differential scanning calorimetry (DSC), differential thermal analysis, and X-ray diffractometry (XRD). The glass forming ability (GFA) and activation energy for crystallization have a distinct dependence on Mo content. Fe{sub 62}C{sub 10}B{sub 9}Mo{sub 12}Cr{sub 4}W{sub 3} is the best glass former in this study, demonstrating a supercooled liquid region, {delta}T{sub x} = 51 K, and an activation energy for crystallization, Q = 453 kJ/mol. The GFA of alloys in this system was governed by elastic strain optimization resulting directly from the variation in Mo content. Heat treatments were performed to demonstrate resistance to crystallization under typical processing conditions. Alloys in this system exhibited a three-phase evolution during crystallization. A second set of heat treatments was performed to identify each phase. Hardness data was collected at each of the heat treatment conditions, and a bulk metallic glasses (BMG)-derived composite containing a Mo-rich phase exhibited Vickers Hardness in excess of 2000. The fully amorphous alloys had an average hardness approaching 1500.

  12. Glass-forming ability and structure of ZnO-MoO.sub.3./sub.-P.sub.2./sub.O.sub.5./sub. glasses

    Czech Academy of Sciences Publication Activity Database

    Šubčík, J.; Koudelka, L.; Mošner, P.; Montagne, L.; Tricot, G.; Delevoye, L.; Gregora, Ivan

    2010-01-01

    Roč. 356, 44-49 (2010), 2509-2516 ISSN 0022-3093 R&D Projects: GA AV ČR KAN301370701 Institutional research plan: CEZ:AV0Z10100520 Keywords : phosphate glass es * structure * MAS NMR spectra * Raman spectra Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.483, year: 2010

  13. Glass-forming ability and structure of glasses in the ZnO-WO.sub.3./sub.-P.sub.2./sub.O.sub.5./sub. system

    Czech Academy of Sciences Publication Activity Database

    Koudelka, L.; Šubčík, J.; Mošner, P.; Gregora, Ivan; Montagne, L.; Delevoye, L.

    2012-01-01

    Roč. 53, č. 3 (2012), s. 79-85 ISSN 1753-3562 R&D Projects: GA AV ČR KAN301370701 Institutional research plan: CEZ:AV0Z10100520 Keywords : glasses * ternary systems * Raman spectra * NMR Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.764, year: 2012

  14. Beyond packing of hard spheres: The effects of core softness, non-additivity, intermediate-range repulsion, and many-body interactions on the glass-forming ability of bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Kai; Fan, Meng; Liu, Yanhui; Schroers, Jan [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Shattuck, Mark D. [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics and Benjamin Levich Institute, The City College of the City University of New York, New York, New York 10031 (United States); O’Hern, Corey S. [Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06520 (United States); Center for Research on Interface Structures and Phenomena, Yale University, New Haven, Connecticut 06520 (United States); Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States)

    2015-11-14

    When a liquid is cooled well below its melting temperature at a rate that exceeds the critical cooling rate R{sub c}, the crystalline state is bypassed and a metastable, amorphous glassy state forms instead. R{sub c} (or the corresponding critical casting thickness d{sub c}) characterizes the glass-forming ability (GFA) of each material. While silica is an excellent glass-former with small R{sub c} < 10{sup −2} K/s, pure metals and most alloys are typically poor glass-formers with large R{sub c} > 10{sup 10} K/s. Only in the past thirty years have bulk metallic glasses (BMGs) been identified with R{sub c} approaching that for silica. Recent simulations have shown that simple, hard-sphere models are able to identify the atomic size ratio and number fraction regime where BMGs exist with critical cooling rates more than 13 orders of magnitude smaller than those for pure metals. However, there are a number of other features of interatomic potentials beyond hard-core interactions. How do these other features affect the glass-forming ability of BMGs? In this manuscript, we perform molecular dynamics simulations to determine how variations in the softness and non-additivity of the repulsive core and form of the interatomic pair potential at intermediate distances affect the GFA of binary alloys. These variations in the interatomic pair potential allow us to introduce geometric frustration and change the crystal phases that compete with glass formation. We also investigate the effect of tuning the strength of the many-body interactions from zero to the full embedded atom model on the GFA for pure metals. We then employ the full embedded atom model for binary BMGs and show that hard-core interactions play the dominant role in setting the GFA of alloys, while other features of the interatomic potential only change the GFA by one to two orders of magnitude. Despite their perturbative effect, understanding the detailed form of the intermetallic potential is important for

  15. Theoretical Considerations of the Prigogine-Defay Ration with Regard to the Glass-Forming Ability of Drugs from Undercooled Melts

    Energy Technology Data Exchange (ETDEWEB)

    Wyttenbach, Nicole; Kirchmeyer, Wiebke; Alsenz, Jochem; Kuentz, Martin [UASANS

    2016-01-26

    Drug behavior in undercooled melts is highly important for pharmaceutics with regard to amorphous solid dispersions, and therefore, categories were recently introduced that differentiate glass formers (GFs) from other drugs that are nonglass formers (nGFs). The present study is based on the assumption that molecular properties relevant for the so-called Prigogine–Defay (PD) ratio would be indicative of a drug’s glass-forming ability. The PD ratio depends in theory on the entropy of fusion and molar volume. Experimental data were gathered from a broad set of pharmaceutical compounds (n = 54) using differential scanning calorimetry. The obtained entropy of fusion and molar volume were indeed found to significantly discriminate GFs from nGFs. In a next step, the entropy of fusion was predicted by different in silico methods. A first group contribution method provided rather unreliable estimates for the entropy of fusion, while an alternative in silico approach seemed more promising for drug categorization. Thus, a significant discrimination model employed molar volume, a so-called effective hydrogen bond number, and effective number of torsional bonds (or torsional units) to categorize GFs and nGFs (p ≤ 0.0000). The results led to new insights into drug vitrification and to practical rules of thumb. The latter may serve as guidance in pharmaceutical profiling and early formulation development with respect to amorphous drug formulations.

  16. Influence of substitution of La by Ce on the glass forming ability and crystallization behavior of Al–Ni–La alloys

    International Nuclear Information System (INIS)

    Zhang, Z.; Xiong, X.Z.; Zhou, W.; Li, J.F.

    2013-01-01

    Highlights: •Wedge-shaped samples were suction cast with casting conditions controlled. •Partial substitution of La by Ce decreases the GFA of Al 85.5 Ni 9.5 La 5 . •Partial substitution of La by Ce increases the GFA of other Al–Ni–La alloys. •The GFA was analyzed from the thermodynamic and topological points of view. -- Abstract: Wedge-shaped samples of Al–Ni–(La–Ce) alloys were suction cast under an identical preparation condition, and their glass forming abilities (GFAs) and crystallization behaviors were compared. It was revealed that the partial substitution of La by Ce decreases the GFA of Al 85.5 Ni 9.5 La 5 alloy but increases the GFAs of Al 87.5 Ni 7.5 La 5 , Al 86.5 Ni 8.5 La 5 , Al 86 Ni 9 La 5 and Al 86 Ni 9.5 La 4.5 alloys. Meantime the crystallization behavior significantly changes. The optimal substitution content of La for glass formation depends on the composition of the base alloy. The lower the Ni content in the base alloy, the more the La content to be substituted. The GFA change with the substitution content is determined by the atomic packing efficiencies of the La (Ce)-centered clusters

  17. Influence of substitution of La by Ce on the glass forming ability and crystallization behavior of Al–Ni–La alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.; Xiong, X.Z.; Zhou, W.; Li, J.F., E-mail: jfli@sjtu.edu.cn

    2013-11-05

    Highlights: •Wedge-shaped samples were suction cast with casting conditions controlled. •Partial substitution of La by Ce decreases the GFA of Al{sub 85.5}Ni{sub 9.5}La{sub 5}. •Partial substitution of La by Ce increases the GFA of other Al–Ni–La alloys. •The GFA was analyzed from the thermodynamic and topological points of view. -- Abstract: Wedge-shaped samples of Al–Ni–(La–Ce) alloys were suction cast under an identical preparation condition, and their glass forming abilities (GFAs) and crystallization behaviors were compared. It was revealed that the partial substitution of La by Ce decreases the GFA of Al{sub 85.5}Ni{sub 9.5}La{sub 5} alloy but increases the GFAs of Al{sub 87.5}Ni{sub 7.5}La{sub 5}, Al{sub 86.5}Ni{sub 8.5}La{sub 5}, Al{sub 86}Ni{sub 9}La{sub 5} and Al{sub 86}Ni{sub 9.5}La{sub 4.5} alloys. Meantime the crystallization behavior significantly changes. The optimal substitution content of La for glass formation depends on the composition of the base alloy. The lower the Ni content in the base alloy, the more the La content to be substituted. The GFA change with the substitution content is determined by the atomic packing efficiencies of the La (Ce)-centered clusters.

  18. Forming Glasses from Se and Te

    Directory of Open Access Journals (Sweden)

    Pierre Lucas

    2009-10-01

    Full Text Available Despite being close neighbors on the Periodic Table, selenium and tellurium present a totally different abilities to form glasses. Se is a very good glass former, and gives rise to numerous glass compositions which are popular for their transparency in the infrared range and their stability against crystallization. These glasses can be shaped into sophisticated optical devices such as optical fibers, planar guides or lenses. Nevertheless, their transparencies are limited at about 12 μm (depending on the thickness of the optical systems due to the relatively small mass of the Se element. On the other hand, tellurium is heavier and its use in substitution for Se permits to shift the IR cutoff beyond 20 μm. However, the semimetallic nature of Te limits its glass formation ability and this glass family is known to be unstable and consequently has found application as phase change material in the Digital Versatile Disk (DVD technology. In this paper, after a review of selenide glasses and their applications, it will be shown how, in a recent past, it has been possible to stabilize tellurium glasses by introducing new elements like Ga or I in their compositions.

  19. Glass forming ability of the Al-Ce-Ni system; Avaliacao da capacidade de formacao vitrea do sistema Al-Ce-Ni

    Energy Technology Data Exchange (ETDEWEB)

    Triveno Rios, C. [Engenharia Mecanica, Universidade Federal de Mato Grosso, Rondonopolis, MT (Brazil)], e-mail: triveno@ufmt.br; Surinach, S.; Baro, M.D. [Departamento de Engenharia de Materiais - Universidade Federal de Sao Carlos, SP (Brazil); Bolfarini, C.; Botta, W.J.; Kiminami, C.S. [Departamento de Fisica da Universidade Autonoma de Barcelona, Bellaterra (Spain)

    2010-07-01

    In the present work, the glass forming ability (GFA) and its compositional dependence on Al-Ni-Ce system alloys were investigated in function of several thermal parameters. Rapidly quenched Al{sub 85}Ni{sub 15}-{sub X}Ce{sub X} (X=4,5,6,7,10), Al{sub 90}Ni{sub 5}Ce{sub 5}, Al{sub 89}Ni{sub 2}.{sub 4}Ce{sub 8}.{sub 6}, Al{sub 80}Ni{sub 15.6}Ce{sub 4}.{sub 4} and Al{sub 78}Ni{sub 18.5}Ce{sub 3.5} amorphous ribbons were produced by melt-spinning and the structural transformation during heating was studied using a combination of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results showed that the GFA and the thermal stability in the Al-rich corner of Al- Ni-Ce system alloys were enhanced by increasing the solute content and specifically the Ce content (author)

  20. Characterization of glass and glass ceramic nuclear waste forms

    International Nuclear Information System (INIS)

    Lutze, W.; Borchardt, J.; De, A.K.

    1979-01-01

    Characteristics of solidified nuclear waste forms, glass and glass ceramic compositions and the properties (composition, thermal stability, crystallization, phase behavior, chemical stability, mechanical stability, and radiation effects) of glasses and glass ceramics are discussed. The preparation of glass ceramics may be an optional step for proposed vitrification plants if tailored glasses are used. Glass ceramics exhibit some improved properties with respect to glasses. The overall leach resistance is similar to that of glasses. An increased leach resistance may become effective for single radionuclides being hosted in highly insoluble crystal phases mainly when higher melting temperatures are applicable in order to get more leach resistant residual glass phases. The development of glass ceramic is going on. The technological feasibility is still to be demonstrated. The potential gain of stability when using glass ceramics qualifies the material as an alternative nuclear waste form

  1. Drastic influence of minor Fe or Co additions on the glass forming ability, martensitic transformations and mechanical properties of shape memory Zr-Cu-Al bulk metallic glass composites.

    Science.gov (United States)

    González, Sergio; Pérez, Pablo; Rossinyol, Emma; Suriñach, Santiago; Dolors Baró, Maria; Pellicer, Eva; Sort, Jordi

    2014-06-01

    The microstructure and mechanical properties of Zr 48 Cu 48 -  x Al 4 M x (M ≡ Fe or Co, x  = 0, 0.5, 1 at.%) metallic glass (MG) composites are highly dependent on the amount of Fe or Co added as microalloying elements in the parent Zr 48 Cu 48 Al 4 material. Addition of Fe and Co promotes the transformation from austenite to martensite during the course of nanoindentation or compression experiments, resulting in an enhancement of plasticity. However, the presence of Fe or Co also reduces the glass forming ability, ultimately causing a worsening of the mechanical properties. Owing to the interplay between these two effects, the compressive plasticity for alloys with x  = 0.5 (5.5% in Zr 48 Cu 47.5 Al 4 Co 0.5 and 6.2% in Zr 48 Cu 47.5 Al 4 Fe 0.5 ) is considerably larger than for Zr 48 Cu 48 Al 4 or the alloys with x  = 1. Slight variations in the Young's modulus (around 5-10%) and significant changes in the yield stress (up to 25%) are also observed depending on the composition. The different microstructural factors that have an influence on the mechanical behavior of these composites are investigated in detail: (i) co-existence of amorphous and crystalline phases in the as-cast state, (ii) nature of the crystalline phases (austenite versus martensite content), and (iii) propensity for the austenite to undergo a mechanically-driven martensitic transformation during plastic deformation. Evidence for intragranular nanotwins likely generated in the course of the austenite-martensite transformation is provided by transmission electron microscopy. Our results reveal that fine-tuning of the composition of the Zr-Cu-Al-(Fe,Co) system is crucial in order to optimize the mechanical performance of these bulk MG composites, to make them suitable materials for structural applications.

  2. Binary eutectic clusters and glass formation in ideal glass-forming liquids

    International Nuclear Information System (INIS)

    Lu, Z. P.; Shen, J.; Xing, D. W.; Sun, J. F.; Liu, C. T.

    2006-01-01

    In this letter, a physical concept of binary eutectic clusters in 'ideal' glass-forming liquids is proposed based on the characteristics of most well-known bulk metallic glasses (BMGs). The authors approach also includes the treatment of binary eutectic clusters as basic units, which leads to the development of a simple but reliable method for designing BMGs more efficiently and effectively in these unique glass-forming liquids. As an example, bulk glass formers with superior glass-forming ability in the Zr-Ni-Cu-Al and Zr-Fe-Cu-Al systems were identified with the use of the strategy

  3. A new method locating good glass-forming compositions

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Dechuan [Department of Materials Physics and Chemistry, Northeastern University, No.3-11, Wenhua Road, Shenyang, 110819 (China); Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China); Geng, Yan [Department of Materials Physics and Chemistry, Northeastern University, No.3-11, Wenhua Road, Shenyang, 110819 (China); Li, Zhengkun [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China); Liu, Dingming [Department of Materials Physics and Chemistry, Northeastern University, No.3-11, Wenhua Road, Shenyang, 110819 (China); Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China); Fu, Huameng; Zhu, Zhengwang [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China); Qi, Yang, E-mail: qiyang@imp.neu.edu.cn [Department of Materials Physics and Chemistry, Northeastern University, No.3-11, Wenhua Road, Shenyang, 110819 (China); Zhang, Haifeng, E-mail: hfzhang@imr.ac.cn [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang, 110016 (China)

    2015-10-15

    A new method was proposed to pinpoint the compositions with good glass forming ability (GFA) by combining atomic clusters and mixing entropy. The clusters were confirmed by analyzing competing crystalline phases. The method was applied to the Zr–Al–Ni–Cu–Ag alloy system. A series of glass formers with diameter up to 20 mm were quickly detected in this system. The good glass formers were located only after trying 5 compositions around the calculated composition. The method was also effective in other multi-component systems. This method might provide a new way to understand glass formation and to quickly pinpoint compositions with high GFA. - Highlights: • A new method was proposed to quickly design glass formers with high glass forming ability. • The method of designing pentabasic Zr–Al–Ni–Cu–Ag alloys was applied. • A series of new Zr-based bulk metallic glasses with critical diameter of 20 mm were discovered.

  4. A new method locating good glass-forming compositions

    International Nuclear Information System (INIS)

    Yu, Dechuan; Geng, Yan; Li, Zhengkun; Liu, Dingming; Fu, Huameng; Zhu, Zhengwang; Qi, Yang; Zhang, Haifeng

    2015-01-01

    A new method was proposed to pinpoint the compositions with good glass forming ability (GFA) by combining atomic clusters and mixing entropy. The clusters were confirmed by analyzing competing crystalline phases. The method was applied to the Zr–Al–Ni–Cu–Ag alloy system. A series of glass formers with diameter up to 20 mm were quickly detected in this system. The good glass formers were located only after trying 5 compositions around the calculated composition. The method was also effective in other multi-component systems. This method might provide a new way to understand glass formation and to quickly pinpoint compositions with high GFA. - Highlights: • A new method was proposed to quickly design glass formers with high glass forming ability. • The method of designing pentabasic Zr–Al–Ni–Cu–Ag alloys was applied. • A series of new Zr-based bulk metallic glasses with critical diameter of 20 mm were discovered

  5. Do atmospheric aerosols form glasses?

    Directory of Open Access Journals (Sweden)

    D. A. Pedernera

    2008-09-01

    Full Text Available A new process is presented by which water soluble organics might influence ice nucleation, ice growth, chemical reactions and water uptake of aerosols in the upper troposphere: the formation of glassy aerosol particles. Glasses are disordered amorphous (non-crystalline solids that form when a liquid is cooled without crystallization until the viscosity increases exponentially and molecular diffusion practically ceases. The glass transition temperatures, Tg, homogeneous ice nucleation temperatures, Thom, and ice melting temperatures, Tm, of various aqueous inorganic, organic and multi-component solutions are investigated with a differential scanning calorimeter. The investigated solutes are: various polyols, glucose, raffinose, levoglucosan, an aromatic compound, sulfuric acid, ammonium bisulfate and mixtures of dicarboxylic acids (M5, of dicarboxylic acids and ammonium sulfate (M5AS, of two polyols, of glucose and ammonium nitrate, and of raffinose and M5AS. The results indicate that aqueous solutions of the investigated inorganic solutes show Tg values that are too low to be of atmospheric importance. In contrast, aqueous organic and multi-component solutions readily form glasses at low but atmospherically relevant temperatures (≤230 K. To apply the laboratory data to the atmospheric situation, the measured phase transition temperatures were transformed from a concentration to a water activity scale by extrapolating water activities determined between 252 K and 313 K to lower temperatures. The obtained state diagrams reveal that the higher the molar mass of the aqueous organic or multi-component solutes, the higher Tg of their respective solutions at a given water activity. To a lesser extent, Tg also depends on the hydrophilicity of the organic solutes. Therefore, aerosol particles containing larger (≳150 g mol−1 and

  6. Effect of zirconium purity on the glass-forming-ability and notch toughness of Cu{sub 43}Zr{sub 43}Al{sub 7}Be{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, Laura M. [Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA (United States); Hofmann, Douglas C. [Materials Development and Manufacturing Technology Group, NASA Jet Propulsion Laboratory/California Institute of Technology, MS 18-105, 4800 Oak Grove Dr. Pasadena, CA 91109 (United States); Vecchio, Kenneth S., E-mail: kvecchio@ucsd.edu [Department of NanoEngineering, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA (United States)

    2016-09-30

    The effect of substituting standard grade zirconium lump (99.8% excluding up to 4% hafnium) for high purity zirconium crystal bar (99.5%) in a Cu{sub 43}Zr{sub 43}Al{sub 7}Be{sub 7} bulk metallic glass (BMG) is examined. The final hafnium content in the BMG specimens was found to range from 0 to 0.44 at%. Introducing low purity zirconium significantly decreased the glass-forming-ability and reduced the notch toughness of the BMG. In contrast, when adding high purity hafnium to Cu{sub 43}Zr{sub 43}Al{sub 7}Be{sub 7} made with high purity zirconium, no significant change in the glass-forming-ability or toughness was observed. This suggests that the introduction of low purity zirconium in BMGs creates a more complex response than a simple addition of hafnium. It is likely that other impurities in the material, such as oxygen, play a role in the complex crystallization kinetics and change in mechanical properties. The notch toughness was measured through four-point-bend tests, which showed a decrease in notch toughness from an average of ~53 MPa m{sup 1/2} for the high purity samples to an average of ~29 MPa m{sup 1/2} with full substitution of low purity zirconium. A similar decrease in glass-forming-ability and toughness is observed in commercially synthesized high purity Cu{sub 43}Zr{sub 43}Al{sub 7}Be{sub 7}. The large scale commercial process is expected to introduced some unintentional impurities, which decrease the properties of the BMG in the same way as the lower purity elements. Lastly, Weibull statistics are used to provide an analysis of variability in toughness for both ingots synthesized in a small laboratory arc-melter and those synthesized commercially.

  7. Glass forming ability and magnetic properties of Co(40.2−x)Fe(20.1+x)Ni6.7B22.7Si5.3Nb5 (x=0–10) bulk metallic glasses produced by suction casting

    International Nuclear Information System (INIS)

    Sarlar, Kagan; Kucuk, Ilker

    2015-01-01

    The effect of Fe concentration on the glass forming ability (GFA) and magnetic properties in Co (40.2−x) Fe (20.1+x) Ni 6.7 B 22.7 Si 5.3 Nb 5 (x=0–10) bulk metallic glasses were investigated. By suction casting method, the bulk metallic glasses with diameters up to 2 mm were produced. We try to find out which Fe concentration makes an influence on Co based system's magnetic properties and glass forming ability. The curves of thermal analysis, obtained using differential scanning calorimetry (DSC), show that the Co (40.2−x) Fe (20.1+x) Ni 6.7 B 22.7 Si 5.3 Nb 5 (x=0–10) have a supercooled liquid region (∆T x ) of about 44 K. The saturation magnetizations (J s ) for as-cast BMG alloys were in the range of 0.62 T−0.81 T. - Highlights: • The effect of Fe concentration on the glass forming ability. • The substitution of an appropriate amount of Fe can enhance the GFA. • The substitution of Fe for Co also improves soft magnetic properties of the BMGs. • The high of J s 0.62−0.81 T with a low H c of 2−289 A/m of the alloys

  8. Review of glass ceramic waste forms

    International Nuclear Information System (INIS)

    Rusin, J.M.

    1981-01-01

    Glass ceramics are being considered for the immobilization of nuclear wastes to obtain a waste form with improved properties relative to glasses. Improved impact resistance, decreased thermal expansion, and increased leach resistance are possible. In addition to improved properties, the spontaneous devitrification exhibited in some waste-containing glasses can be avoided by the controlled crystallization after melting in the glass-ceramic process. The majority of the glass-ceramic development for nuclear wastes has been conducted at the Hahn-Meitner Institute (HMI) in Germany. Two of their products, a celsian-based (BaAl 3 Si 2 O 8 ) and a fresnoite-based (Ba 2 TiSi 2 O 8 ) glass ceramic, have been studied at Pacific Northwest Laboratory (PNL). A basalt-based glass ceramic primarily containing diopsidic augite (CaMgSi 2 O 6 ) has been developed at PNL. This glass ceramic is of interest since it would be in near equilibrium with a basalt repository. Studies at the Power Reactor and Nuclear Fuel Development Corporation (PNC) in Japan have favored a glass-ceramic product based upon diopside (CaMgSi 2 O 6 ). Compositions, processing conditions, and product characterization of typical commercial and nuclear waste glass ceramics are discussed. In general, glass-ceramic waste forms can offer improved strength and decreased thermal expansion. Due to typcially large residual glass phases of up to 50%, there may be little improvement in leach resistance

  9. Study of the glass forming ability of Cu60Zr32,5Ti7,5 alloy by molecular dynamics

    International Nuclear Information System (INIS)

    Schimidt, C.S.; Lima, L.V.; Bastos, I.N.; Aliaga, L.C.R.

    2016-01-01

    This article presents the results of molecular dynamics simulation of Cu 60 Zr 32.5 Ti 7.5 alloy through the open source code LAMMPS. Amorphous samples were produced by quenching the metallic molten from 2300K to 200K at cooling rates of 50, 5 and 0.5K/ps. The pair distribution functions of both the liquid and solid were calculated and compared at different temperatures. The topology of short-range order was analyzed using the Voronoi tessellation method, which determined the presence of Cu-centered icosahedral clusters as the prevailing in the amorphous state at 300K. Moreover, the sample was submitted to uniaxial tensile tests at strain rate of 10ps -1 , in order to investigate the mechanical behavior of the metallic glass. The result of the stress-strain curve showed that applied loads lead to the plastic regime. However, the presences of shear bands, typical in the experimental testing, were not observed. Moreover, the evolution of the viscosity above the glass transition temperature and the fragility of the alloy were determined. The solidus and liquidus temperatures were determined and a good agreement with experimental data was found. (author)

  10. Glass forming ability and magnetic properties of Co{sub (40.2−x)}Fe{sub (20.1+x)}Ni{sub 6.7}B{sub 22.7}Si{sub 5.3}Nb{sub 5} (x=0–10) bulk metallic glasses produced by suction casting

    Energy Technology Data Exchange (ETDEWEB)

    Sarlar, Kagan [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey); Physics Department, Kamil Ozdag Faculty of Sciences, Karamanoglu Mehmetbey University, YunusEmre Campus, 70100 Karaman (Turkey); Kucuk, Ilker, E-mail: ikucuk@uludag.edu.tr [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey)

    2015-01-15

    The effect of Fe concentration on the glass forming ability (GFA) and magnetic properties in Co{sub (40.2−x)}Fe{sub (20.1+x)}Ni{sub 6.7}B{sub 22.7}Si{sub 5.3}Nb{sub 5} (x=0–10) bulk metallic glasses were investigated. By suction casting method, the bulk metallic glasses with diameters up to 2 mm were produced. We try to find out which Fe concentration makes an influence on Co based system's magnetic properties and glass forming ability. The curves of thermal analysis, obtained using differential scanning calorimetry (DSC), show that the Co{sub (40.2−x)}Fe{sub (20.1+x)}Ni{sub 6.7}B{sub 22.7}Si{sub 5.3}Nb{sub 5} (x=0–10) have a supercooled liquid region (∆T{sub x}) of about 44 K. The saturation magnetizations (J{sub s}) for as-cast BMG alloys were in the range of 0.62 T−0.81 T. - Highlights: • The effect of Fe concentration on the glass forming ability. • The substitution of an appropriate amount of Fe can enhance the GFA. • The substitution of Fe for Co also improves soft magnetic properties of the BMGs. • The high of J{sub s} 0.62−0.81 T with a low H{sub c} of 2−289 A/m of the alloys.

  11. Glass forming ability and mechanical properties of the NiZrTiSi amorphous alloys modified with Al, Cu and Nb additions

    International Nuclear Information System (INIS)

    Czeppe, Tomasz; Ochin, Patrick; Sypien, Anna

    2007-01-01

    The composition of the amorphous alloy Ni 59 Zr 20 Ti 16 Si 5 was modified with 2-9 at.% additions of Cu, Al and Nb. The ribbons and the bars 2.7 mm in diameter were prepared by melt spinning and injection casting from the alloys of the compositions: Ni 56 Zr 18 Ti 16 Si 5 Al 3 Cu 2 , Ni 56 Zr 18 Ti 13 Al 6 Si 5 Cu 2 , Ni 56 Zr 16 Ti 12 Nb 9 Al 3 Cu 2 Si 2 and Ni 56 Zr 16 Ti 12 Nb 6 Al 6 Cu 2 Si 2 . All ribbons were amorphous up to the resolution of the X-ray diffraction and conventional transmission electron microscopy, however rods were partially crystalline. Increase of Al content lowered and Nb content slightly increased crystallization start temperature T x and glass transition temperature T g . The influence of composition changes on the overcooled liquid range ΔT was more complicated. The increase of Nb and decrease of Ti and Zr content led to the remarkable increase of the liquidus temperature T l . As a result GFA calculated as T g /T l was lowered to the values about 0.63 for 6 and 9 at.% Nb addition. The activation energies for primary crystallization in alloy with 6 at.% Al and 6 at.% of Nb, were determined. The changes of tensile test strength and microhardness with Al and Nb additions showed hardening effect caused by Nb additions and increase in fracture strength with increasing Al content

  12. Thermodynamic and relative approach to compute glass-forming

    Indian Academy of Sciences (India)

    This study deals with the evaluation of glass-forming ability (GFA) of oxides and is a critical reading of Sun and Rawson thermodynamic approach to quantify this aptitude. Both approaches are adequate but ambiguous regarding the behaviour of some oxides (tendency to amorphization or crystallization). Indeed, ZrO2 and ...

  13. Thermodynamic and relative approach to compute glass-forming ...

    Indian Academy of Sciences (India)

    models) characteristic: the isobaric heat capacity (Cp) of oxides, and execute a mathematical treatment of oxides thermodynamic data. We note this coefficient as thermodynamical relative glass-forming ability (ThRGFA) and for- mulate a model to compute it. Computed values of 2nd, 3rd, 4th and 5th period metal oxides ...

  14. Ceramic and glass radioactive waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Readey, D.W.; Cooley, C.R. (comps.)

    1977-01-01

    This report contains 14 individual presentations and 6 group reports on the subject of glass and polycrystalline ceramic radioactive waste forms. It was the general consensus that the information available on glass as a waste form provided a good basis for planning on the use of glass as an initial waste form, that crystalline ceramic forms could also be good waste forms if much more development work were completed, and that prediction of the chemical and physical stability of the waste form far into the future would be much improved if the basic synergistic effects of low temperature, radiation and long times were better understood. Continuing development of the polycrystalline ceramic forms was recommended. It was concluded that the leach rate of radioactive species from the waste form is an important criterion for evaluating its suitability, particularly for the time period before solidified waste is permanently placed in the geologic isolation of a Federal repository. Separate abstracts were prepared for 12 of the individual papers; the remaining two were previously abstracted.

  15. Simulation of Glass Fiber Forming Processes

    DEFF Research Database (Denmark)

    Von der Ohe, Renate

    Two glass fiber forming processes have been simulated using FEM, which are the drawing of continuous glass fibers for reinforcement purposes and the spinning of discontinuous glass fibers - stone wool for insulation. The aim of this work was to set up a numerical model for each process, and to use...... this model in finding relationships between the production conditions and the resulting fiber properties. For both processes, a free surface with large deformation and radiative and convective heat transfer must be taken into account. The continuous fiber drawing has been simulated successfully......, and parametric studies have been made. Several properties that characterize the process have been calculated, and the relationship between the fictive temperature and the cooling rate of the fibers has been found. The model for the discontinuous fiber spinning was brought to the limits of the commercial code...

  16. The evaluation of the radiation shielding ability of lead glass

    International Nuclear Information System (INIS)

    Tsuda, Keisuke; Fukushi, Masahiro; Myojoyama, Atsushi; Kitamura, Hideaki; Nakaya, Giichiro; Hassan, Nabil; Inoue, Kazumasa; Kimura, Junichi; Sawaguchi, Masato; Kinase, Sakae; Saito, Kimiaki

    2008-01-01

    Positron emission tomography (PET) scanning with the tracer 2-[F-18] Fluoro-2deoxy-D-glucose (FDG) is widely used in the clinical PET. However, the photon energy used in the PET scans is considerably higher than that of the X-rays traditionally used in the diagnoses. The radiation protection in the PET institution, therefore, is the remaining problem. Meanwhile, lead glass has attracted considerable attention as a radiation-shielding material for the PET institution. The aim of the present study was to evaluate the radiation-shielding ability of the lead glass against the positron emitters. The shielding ability evaluations were done both in the actual experiments and in the Monte Carlo simulation. The lead glass, the object of evaluation in this study, proved to have sufficient protective effect. The development and the spread of a thinner and lighter lead glass with the same effective dose transmission factor should be expected in the near future. (author)

  17. Bone bonding ability of some borate bio-glasses and their corresponding glass-ceramic derivatives

    Directory of Open Access Journals (Sweden)

    Fatma H. Margha

    2012-12-01

    Full Text Available Ternary borate glasses from the system Na2O·CaO·B2O3 together with soda-lime-borate samples containing 5 wt.% of MgO, Al2O3, SiO2 or P2O5 were prepared. The obtained glasses were converted to their glass-ceramic derivatives by controlled heat treatment. X-ray diffraction was employed to investigate the separated crystalline phases in glass-ceramics after heat treatment of the glassy samples. The glasses and corresponding glass-ceramics after immersion in water or diluted phosphate solution for extended times were characterized by the grain method (adopted by several authors and recommended by ASTM and Fourier-transform infrared spectra to justify the formation of hydroxyapatite as an indication of the bone bonding ability. The influence of glass composition on bioactivity potential was discussed too.

  18. Triplex-forming ability of modified oligonucleotides

    DEFF Research Database (Denmark)

    Højland, Torben; Babu, Bolle Ravindra; Bryld, Torsten

    2007-01-01

    We present our studies on the ability of several different nucleotide analogs as triplex-forming oligonucleotides. The modifications tested include 4'-C-hydroxymethyl, LNA, 2'-amino-LNA and N2'-functionalized 2'-amino-LNA. Triplexes containing monomers of N2'-glycyl-functionalized 2'-amino-LNA ar...

  19. ESCA studies on leached glass forms

    International Nuclear Information System (INIS)

    Dawkins, B.G.

    1979-01-01

    Electron Spectroscopy for Chemical Analysis (ESCA) results for frit, obsidian, NBS standard, and Savannah River Laboratory (SRL) glass forms that have been subjected to cumulative water leachings of 36 hours show that [Na] exhibits the largest and fastest change of all the elements observed. Leaching of surface Na occurred within minutes. Surface Na depletion increased with leach time. Continuous x-ray irradiation and argon ion milling induced Na mobility, precluding semiquantitative ESCA analysis at normal operating temperatures. However, the sample stage has been equipped with a liquid nitrogen supply and alkali mobility should be eliminated in future work

  20. Forming of bulk metallic glass microcomponents

    DEFF Research Database (Denmark)

    Wert, John A.; Thomsen, Christian; Jensen, Rune Debel

    2009-01-01

    The present article considers forward extrusion, closed-die forging and backward extrusion processes for fabrication of individual microcomponents from two bulk metallic glass (BMG) compositions: Mg60Cu30Y10 and Zr44Cu40Ag8Al8. Two types of tooling were used in the present work: relatively massive...... die sets characteristic of cold forming operations for crystalline metals and lightweight die sets adapted to the special characteristics of BMGs. In addition to demonstrating that microcomponents of several geometries can be readily fabricated from BMGs, rheological properties are combined...

  1. Dynamics of glass-forming liquids

    DEFF Research Database (Denmark)

    Hansen, Henriette Wase

    on alpha relaxation dynamics, and for the two van der Waals liquids, also when we have separation of timescales, i.e. the alpha relaxation is not contributing to the picosecond dynamics. The concept of isomorphs is observed to break down in two cases for the hydrogen bonding system: in density scaling......The overall theme of this work has been to experimentally test the shoving model and isomorph theory related to the dynamics of glass-forming liquids, both of which, rather than being universal explanations, are expected to work in the simplest case. We test the connection between fast and slow...... dynamics in light of the shoving model from the temperature dependence of the mean-squared displacement from neutron scattering at nanosecond timescale and the elastic modulus from shear mechanics. We find the fast dynamics to correlate with the alpha relaxation time and fragility in agreement...

  2. Spinel dissolution via addition of glass forming chemicals. Results of preliminary experiments

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K. M. [Savannah River Site (SRS), Aiken, SC (United States); Johnson, F. C. [Savannah River Site (SRS), Aiken, SC (United States)

    2015-11-01

    Increased loading of high level waste in glass can lead to crystallization within the glass. Some crystalline species, such as spinel, have no practical impact on the chemical durability of the glass, and therefore may be acceptable from both a processing and a product performance standpoint. In order to operate a melter with a controlled amount of crystallization, options must be developed for remediating an unacceptable accumulation of crystals. This report describes preliminary experiments designed to evaluate the ability to dissolve spinel crystals in simulated waste glass melts via the addition of glass forming chemicals (GFCs).

  3. Analysis of form deviation in non-isothermal glass molding

    Science.gov (United States)

    Kreilkamp, H.; Grunwald, T.; Dambon, O.; Klocke, F.

    2018-02-01

    Especially in the market of sensors, LED lighting and medical technologies, there is a growing demand for precise yet low-cost glass optics. This demand poses a major challenge for glass manufacturers who are confronted with the challenge arising from the trend towards ever-higher levels of precision combined with immense pressure on market prices. Since current manufacturing technologies especially grinding and polishing as well as Precision Glass Molding (PGM) are not able to achieve the desired production costs, glass manufacturers are looking for alternative technologies. Non-isothermal Glass Molding (NGM) has been shown to have a big potential for low-cost mass manufacturing of complex glass optics. However, the biggest drawback of this technology at the moment is the limited accuracy of the manufactured glass optics. This research is addressing the specific challenges of non-isothermal glass molding with respect to form deviation of molded glass optics. Based on empirical models, the influencing factors on form deviation in particular form accuracy, waviness and surface roughness will be discussed. A comparison with traditional isothermal glass molding processes (PGM) will point out the specific challenges of non-isothermal process conditions. Furthermore, the underlying physical principle leading to the formation of form deviations will be analyzed in detail with the help of numerical simulation. In this way, this research contributes to a better understanding of form deviations in non-isothermal glass molding and is an important step towards new applications demanding precise yet low-cost glass optics.

  4. Predicting glass-forming compositions in the Al-La and Al-La-Ni systems

    International Nuclear Information System (INIS)

    Gargarella, P.; de Oliveira, M.F.; Kiminami, C.S.; Pauly, S.; Kuehn, U.; Bolfarini, C.; Botta, W.J.; Eckert, J.

    2011-01-01

    Research highlights: → The glass-forming ability of the Al-La and Al-La-Ni systems was studied using the λ* and the λ.Δe criteria. → Both criteria predicted with just 1% at. of error the best glass-former verified so far in the Al-La system. → Four new glass-former compositions could be predicted in the Al-La-Ni system using the λ.Δe criterion. → The best glass-former reported so far in the Al-La-Ni system was found. - Abstract: In this work, a criterion considering the topological instability (λ) and the differences in the electronegativity of the constituent elements (Δe) was applied to the Al-La and Al-Ni-La systems in order to predict the best glass-forming compositions. The results were compared with literature data and with our own experimental data for the Al-La-Ni system. The alloy described in the literature as the best glass former in the Al-La system is located near the point with local maximum for the λ.Δe criterion. A good agreement was found between the predictions of the λ.Δe criterion and literature data in the Al-La-Ni system, with the region of the best glass-forming ability (GFA) and largest supercooled liquid region (ΔT x ) coinciding with the best compositional region for amorphization indicated by the λ.Δe criterion. Four new glassy compositions were found in the Al-La-Ni system, with the best predicted composition presenting the best glass-forming ability observed so far for this system. Although the λ.Δe criterion needs further refinements for completely describe the glass-forming ability in the Al-La and Al-La-Ni systems, the results demonstrated that this criterion is a good tool to predict new glass-forming compositions.

  5. Glass Transition, Crystallization of Glass-Forming Melts, and Entropy

    Directory of Open Access Journals (Sweden)

    Jürn W. P. Schmelzer

    2018-02-01

    Full Text Available A critical analysis of possible (including some newly proposed definitions of the vitreous state and the glass transition is performed and an overview of kinetic criteria of vitrification is presented. On the basis of these results, recent controversial discussions on the possible values of the residual entropy of glasses are reviewed. Our conclusion is that the treatment of vitrification as a process of continuously breaking ergodicity with entropy loss and a residual entropy tending to zero in the limit of zero absolute temperature is in disagreement with the absolute majority of experimental and theoretical investigations of this process and the nature of the vitreous state. This conclusion is illustrated by model computations. In addition to the main conclusion derived from these computations, they are employed as a test for several suggestions concerning the behavior of thermodynamic coefficients in the glass transition range. Further, a brief review is given on possible ways of resolving the Kauzmann paradox and its implications with respect to the validity of the third law of thermodynamics. It is shown that neither in its primary formulations nor in its consequences does the Kauzmann paradox result in contradictions with any basic laws of nature. Such contradictions are excluded by either crystallization (not associated with a pseudospinodal as suggested by Kauzmann or a conventional (and not an ideal glass transition. Some further so far widely unexplored directions of research on the interplay between crystallization and glass transition are anticipated, in which entropy may play—beyond the topics widely discussed and reviewed here—a major role.

  6. Glass binder development for a glass-bonded sodalite ceramic waste form

    International Nuclear Information System (INIS)

    Riley, Brian J.; Vienna, John D.; Frank, Steven M.; Kroll, Jared O.; Peterson, Jacob A.

    2017-01-01

    This paper discusses work to develop Na_2O-B_2O_3-SiO_2 glass binders for immobilizing LiCl-KCl eutectic salt waste in a glass-bonded sodalite waste form following electrochemical reprocessing of used metallic nuclear fuel. In this paper, five new glasses with ~20 mass% Na_2O were designed to generate waste forms with high sodalite. The glasses were then used to produce ceramic waste forms with a surrogate salt waste. The waste forms made using these new glasses were formulated to generate more sodalite than those made with previous baseline glasses for this type of waste. The coefficients of thermal expansion for the glass phase in the glass-bonded sodalite waste forms made with the new binder glasses were closer to the sodalite phase in the critical temperature region near and below the glass transition temperature than previous binder glasses used. Finally, these improvements should result in lower probability of cracking in the full-scale monolithic ceramic waste form, leading to better long-term chemical durability.

  7. Glass forms for immobilization of Hanford wastes

    International Nuclear Information System (INIS)

    Schulz, W.W.; Dressen, A.L.; Hobbick, C.W.; Babad, H.

    1975-03-01

    Approximately 140 million liters of solid salt cake (mainly NaNO 3 ), produced by evaporation of aged alkaline high-level liquid wastes, will be stored in underground tanks when the present Hanford Waste Management Program is completed in the early 1980's. At this time also, large volumes of various other solid radioactive wastes (sludges, excavated Pu-contaminated soil, and doubly encapsulated 137 CsCl and 90 SrF 2 ) will be stored on the Hanford Reservation. All these solid wastes can be converted to immobile silicate and aluminosilicate glasses of low water leachability by melting them at 1100 0 to 1400 0 C with appropriate amounts of basalt (or sand) and other glass-formers such as B 2 O 3 or CaO. Reviewed in this paper are formulations and other melt conditions used successfully in batch tests to make glasses from actual and synthetic wastes; leachability and other properties of these glasses show them to be satisfactory vehicles for immobilization of the Hanford wastes. (U.S.)

  8. Are the dynamics of silicate glasses and glass-forming liquids embedded in their elastic properties?

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Mauro, John C.

    According to the elastic theory of the glass transition, the dynamics of glasses and glass-forming liquids are controlled by the evolution of shear modulus. In particular, the elastic shoving model expresses dynamics in terms of an activation energy required to shove aside the surrounding atoms......, which is determined by the shear modulus. First, we here present an in situ high-temperature Brillouin spectroscopy test of the shoving model near the glass transition of eight aluminosilicate glass-forming systems. We find that the measured viscosity data agree qualitatively with the measured...... temperature dependence of shear moduli, as predicted by the shoving model. However, the model systematically underpredicts the values of fragility. Second, we also present a thorough test of the shoving model for predicting the low temperature dynamics of an aluminosilicate glass system. This is done...

  9. 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)

  10. Leaching behavior of glass ceramic nuclear waste forms

    International Nuclear Information System (INIS)

    Lokken, R.O.

    1981-11-01

    Glass ceramic waste forms have been investigated as alternatives to borosilicate glasses for the immobilization of high-level radioactive waste at Pacific Northwest Laboratory (PNL). Three glass ceramic systems were investigated, including basalt, celsian, and fresnoite, each containing 20 wt % simulated high-level waste calcine. Static leach tests were performed on seven glass ceramic materials and one parent glass (before recrystallization). Samples were leached at 90 0 C for 3 to 28 days in deionized water and silicate water. The results, expressed in normalized elemental mass loss, (g/m 2 ), show comparable releases from celsian and fresnoite glass ceramics. Basalt glass ceramics demonstrated the lowest normalized elemental losses with a nominal release less than 2 g/m 2 when leached in polypropylene containers. The releases from basalt glass ceramics when leached in silicate water were nearly identical with those in deionized water. The overall leachability of celsian and fresnoite glass ceramics was improved when silicate water was used as the leachant

  11. Crystallization dynamics in glass-forming systems

    Energy Technology Data Exchange (ETDEWEB)

    Cullinan, Timothy Edward [Iowa State Univ., Ames, IA (United States)

    2016-02-19

    Crystallization under far-from-equilibrium conditions is investigated for two different scenarios: crystallization of the metallic glass alloy Cu50Zr50 and solidification of a transparent organic compound, o-terphenyl. For Cu50Zr50, crystallization kinetics are quanti ed through a new procedure that directly fits thermal analysis data to the commonly utilized JMAK model. The phase evolution during crystallization is quantified through in-situ measurements (HEXRD, DSC) and ex-situ microstructural analysis (TEM, HRTEM). The influence of chemical partitioning, diffusion, and crystallographic orientation on this sequence are examined. For o-terphenyl, the relationship between crystal growth velocity and interface undercooling is systematically studied via directional solidification.

  12. Influence of Y, Gd and Sm on the glass forming ability and thermal crystallization of aluminum based alloy; Efeito das terras raras Y, Gd e Sm na tendencia a formacao de amorfo e na cristalizacao termica em ligas a base de aluminio

    Energy Technology Data Exchange (ETDEWEB)

    Aliaga, L.C.R.; Bolfarini, C.; Kiminami, C.S.; Botta Filho, W.J., E-mail: aliaga@ufscar.b [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais; Danez, G.P. [Universidade Federal de Sao Carlos (PPG-CEMUFSCar), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2010-07-01

    Al-based amorphous alloys represent an important family of metals and a great scientific activity has been devoted to determine the main features of both glass forming ability (GFA) and crystallization behavior in order to have a comprehensive framework aimed at potential technological applications. Nowadays, it is well known that the best Al-based amorphous alloys are formed in ternary systems such as Al- RE-TM, where RE is a rare earth and TM a transition metal. This paper presents results of research in Al{sub 85}Ni{sub 10}RE{sub 5} alloys (RE = Y, Gd and Sm). Amorphous ribbons were processed by melt-spinning under the same conditions and subsequently characterized by x-ray diffraction (XRD) and differential scanning calorimetry (DSC). Results show appreciable micro structural differences as function of the rare earth, thus crystal is obtained for Y, nano-glassy for Gd and, fully amorphous structure for Sm. (author)

  13. Fluoride release/recharging ability and bond strength of glass ...

    African Journals Online (AJOL)

    2015-08-17

    Aug 17, 2015 ... 2017 Nigerian Journal of Clinical Practice | Published by Wolters Kluwer - ... Objectives: The aim of this in vitro study was to evaluate the microtensile bond strength (μTBS) of different glass ... Glass ionomer cements (GICs) have often been used as the ... with nano‑fluoride‑/hydroxyapatite or resin‑modified.

  14. Molecular dynamics study of the ternary Cu50Ti25Zr25 bulk glass forming alloy

    Directory of Open Access Journals (Sweden)

    Celtek M.

    2011-05-01

    Full Text Available The structure and thermodynamic properties of a ternary Cu50Ti25Zr25 metallic glass forming alloy in solid-liquid to glass phases were studied using molecular dynamics (MD method based on tight-binding (TB potentials. An atomic description of the melting, glass formation and crystallization process has been analyzed using different heating and cooling rates. The computed Glass Forming Ability (GFA parameters are in good agreement with experimental data. The structure analysis of the Cu50Ti25Zr25 based on molecular dynamics simulation will be also presented and compared with available MD results. We have also discussed the crystallization transition with two different interatomic potentials used in this work

  15. Glass-forming liquids: one or more "order" parameters"

    DEFF Research Database (Denmark)

    Bailey, Nicholas; Christensen, Tage Emil; Jakobsen, Bo

    2008-01-01

    We first summarize the classical arguments that the vast majority of glass-forming liquids require more than one ‘order' parameter for their description. Critiques against this conventional wisdom are then presented, and it is argued that the matter deserves to be reconsidered in the light...... that a description with a single "order" parameter applies to a good approximation whenever thermal equilibrium fluctuations of fundamental variables like energy and pressure are strongly correlated. Results from computer simulations showing that this is the case for a number of simple glass-forming liquids, as well...

  16. Bulk glass formation and crystallization in zirconium based bulk metallic glass forming alloys

    International Nuclear Information System (INIS)

    Savalia, R.T.; Neogy, S.; Dey, G.K.; Banerjee, S.

    2002-01-01

    The microstructures of Zr based metallic glasses produced in bulk form have been described in the as-cast condition and after crystallization. Various microscopic techniques have been used to characterize the microstructures. The microstructure in the as-cast condition was found to contain isolated crystals and crystalline aggregates embedded in the amorphous matrix. Quenched-in nuclei of crystalline phases were found to be present in fully amorphous regions. These glasses after crystallization gave rise to nanocrystalline solids. (author)

  17. High level waste forms: glass marbles and thermal spray coatings

    International Nuclear Information System (INIS)

    Treat, R.L.; Oma, K.H.; Slate, S.C.

    1982-01-01

    A process that converts high-level waste to glass marbles and then coats the marbles has been developed at Pacific Northwest Laboratory (PNL) under sponsorship of the US Department of Energy. The process consists of a joule-heated glass melter, a marble-making device based on a patent issued to Corning Glass Works, and a coating system that includes a plasma spray coater and a marble tumbler. The process was developed under the Alternative Waste Forms Program which strived to improve upon monolithic glass for immobilizing high-level wastes. Coated glass marbles were found to be more leach-resistant, and the marbles, before coating were found to be very homogeneous, highly impact resistant, and conductive to encapsulation in a metal matric for improved heat transfer and containment. Marbles are also ideally suited for quality assurance and recycling. However, the marble process is more complex, and marbles require a larger number of canisters for waste containment and have a higher surface area than do glass monoliths

  18. A slow atomic diffusion process in high-entropy glass-forming metallic melts

    Science.gov (United States)

    Chen, Changjiu; Wong, Kaikin; Krishnan, Rithin P.; Embs, Jan P.; Chathoth, Suresh M.

    2018-04-01

    Quasi-elastic neutron scattering has been used to study atomic relaxation processes in high-entropy glass-forming metallic melts with different glass-forming ability (GFA). The momentum transfer dependence of mean relaxation time shows a highly collective atomic transport process in the alloy melts with the highest and lowest GFA. However, a jump diffusion process is the long-range atomic transport process in the intermediate GFA alloy melt. Nevertheless, atomic mobility close to the melting temperature of these alloy melts is quite similar, and the temperature dependence of the diffusion coefficient exhibits a non-Arrhenius behavior. The atomic mobility in these high-entropy melts is much slower than that of the best glass-forming melts at their respective melting temperatures.

  19. Transparent form-active system with structural glass

    NARCIS (Netherlands)

    Nikolaou, M.S.N.; Veer, F.A.; Eigenraam, P.

    2015-01-01

    Free-form transparent wide-span spatial structures which have being constructed so far, are based on the concept of three sets of components, the structural components, usually steel elements to ensure both compressive and tensional capacity; the glass cladding elements for expressing transparency;

  20. Undercooling Limits and Thermophysical Properties in Glass Forming Alloys

    Science.gov (United States)

    Rhim, Won-Kyu; Ohsaka, Kenichi; Spjut, R. Erik

    1999-01-01

    The primary objective of this program is to produce deeply undercooled metallic liquids and to identify factors that limit undercooling and glass formation. The main research objectives are: (1) Investigating undercooling limits in glass-forming alloys and identifying factors that affect undercooling; (2) Measuring thermophysical properties and investigating the validity of the classical nucleation theory and other existing theories in the extreme undercooled states; and (3) To investigate the limits of electrostatic levitation technology in the ground base and to identify thermophysical parameters that might require reduced-g environment.

  1. Measuring the Thermophysical and Structural Properties of Glass-Forming and Quasicrystal-Forming Liquids

    Science.gov (United States)

    Hyers, Robert W.; Bradshaw, Richard C.; Rogers, Jan R.; Gangopadhyay, Anup K.; Kelton, Ken F.

    2006-01-01

    The thermophysical properties of glass-forming and quasicrystal-forming alloys show many interesting features in the undercooled liquid range. Some of the features in the thermophysical property curves are expected to reflect changes in the structure and coordination of the liquid. These measurements require containerless processing such as electrostatic levitation to access the undercooled liquid regime. An overview of the state of the art in measuring the thermophysical properties and structure of undercooled liquid glass-forming and quasicrystal-forming alloys will be presented, along with the status of current measurements.

  2. Poor glass-forming ability of Fe-based alloys

    DEFF Research Database (Denmark)

    Zheng, H.J.; Hu, L.N.; Zhao, X.

    2017-01-01

    processes. By using the concept of fluid cluster and supercooled liquid fragility in metallic liquids, it has been found that this dynamic transition makes the Fe-based supercooled liquids become more unstable, which leads to the poor GFA of Fe-based alloys. Further, it has been found that the degree...

  3. Low sintering temperature glass waste forms for sequestering radioactive iodine

    Science.gov (United States)

    Nenoff, Tina M.; Krumhansl, James L.; Garino, Terry J.; Ockwig, Nathan W.

    2012-09-11

    Materials and methods of making low-sintering-temperature glass waste forms that sequester radioactive iodine in a strong and durable structure. First, the iodine is captured by an adsorbant, which forms an iodine-loaded material, e.g., AgI, AgI-zeolite, AgI-mordenite, Ag-silica aerogel, ZnI.sub.2, CuI, or Bi.sub.5O.sub.7I. Next, particles of the iodine-loaded material are mixed with powdered frits of low-sintering-temperature glasses (comprising various oxides of Si, B, Bi, Pb, and Zn), and then sintered at a relatively low temperature, ranging from 425.degree. C. to 550.degree. C. The sintering converts the mixed powders into a solid block of a glassy waste form, having low iodine leaching rates. The vitrified glassy waste form can contain as much as 60 wt % AgI. A preferred glass, having a sintering temperature of 500.degree. C. (below the silver iodide sublimation temperature of 500.degree. C.) was identified that contains oxides of boron, bismuth, and zinc, while containing essentially no lead or silicon.

  4. Shear viscosity of glass-forming melts in the liquid-glass transition region

    International Nuclear Information System (INIS)

    Sanditov, D. S.

    2010-01-01

    A new approach to interpreting the hole-activation model of a viscous flow of glass-forming liquids is proposed. This model underlies the development of the concept on the exponential temperature dependence of the free energy of activation of a flow within the range of the liquid-glass transition in complete agreement with available experimental data. The 'formation of a fluctuation hole' in high-heat glass-forming melts is considered as a small-scale low-activation local deformation of a structural network, i.e., the quasi-lattice necessary for the switching of the valence bond, which is the main elementary event of viscous flow of glasses and their melts. In this sense, the hole formation is a conditioned process. A drastic increase in the activation free energy of viscous flow in the liquid-glass transition region is explained by a structural transformation that is reduced to a limiting local elastic deformation of the structural network, which, in turn, originates from the excitation (critical displacement) of a bridging atom like the oxygen atom in the Si-O-Si bridge. At elevated temperatures, as a rule, a necessary amount of excited bridging atoms (locally deformed regions of the structural network) always exists, and the activation free energy of viscous flow is almost independent of temperature. The hole-activation model is closely connected with a number of well-known models describing the viscous flow of glass-forming liquids (the Avramov-Milchev, Nemilov, Ojovan, and other models).

  5. Liquid -to-glass transition in bulk glass-forming Cu55-xZr45Agx alloys using molecular dynamic simulations

    Directory of Open Access Journals (Sweden)

    Celtek M.

    2011-05-01

    Full Text Available We report results from molecular dynamics (MD studies concerning the microscopic structure of the ternary, bulk metallic glass-forming Cu55-x Zr45Agx (x=0,10,20 alloys using tight-binding potentials. Understanding of the nature of Glass Forming Ability (GFA of studied alloys, GFA parameters, glass transition temperature (T-g, melting temperature (T-m, reduced glass transition temperature (T-g/T-m, the supercooled liquid region and other parameters were simulated and compared with experiments. The computed pair distribution functions reproduce well experimental x-ray data of Inoue and co-workers. Structure analysis of the Cu-Zr-Ag alloy based on MD simulation will be also presented

  6. Beating Homogeneous Nucleation and Tuning Atomic Ordering in Glass-Forming Metals by Nanocalorimetry.

    Science.gov (United States)

    Zhao, Bingge; Yang, Bin; Abyzov, Alexander S; Schmelzer, Jürn W P; Rodríguez-Viejo, Javier; Zhai, Qijie; Schick, Christoph; Gao, Yulai

    2017-12-13

    In this paper, the amorphous Ce 68 Al 10 Cu 20 Co 2 (atom %) alloy was in situ prepared by nanocalorimetry. The high cooling and heating rates accessible with this technique facilitate the suppression of crystallization on cooling and the identification of homogeneous nucleation. Different from the generally accepted notion that metallic glasses form just by avoiding crystallization, the role of nucleation and growth in the crystallization behavior of amorphous alloys is specified, allowing an access to the ideal metallic glass free of nuclei. Local atomic configurations are fundamentally significant to unravel the glass forming ability (GFA) and phase transitions in metallic glasses. For this reason, isothermal annealing near T g from 0.001 s to 25,000 s following quenching becomes the strategy to tune local atomic configurations and facilitate an amorphous alloy, a mixed glassy-nanocrystalline state, and a crystalline sample successively. On the basis of the evolution of crystallization enthalpy and overall latent heat on reheating, we quantify the underlying mechanism for the isothermal nucleation and crystallization of amorphous alloys. With Johnson-Mehl-Avrami method, it is demonstrated that the coexistence of homogeneous and heterogeneous nucleation contributes to the isothermal crystallization of glass. Heterogeneous rather than homogeneous nucleation dominates the isothermal crystallization of the undercooled liquid. For the mixed glassy-nanocrystalline structure, an extraordinary kinetic stability of the residual glass is validated, which is ascribed to the denser packed interface between amorphous phase and ordered nanocrystals. Tailoring the amorphous structure by nanocalorimetry permits new insights into unraveling GFA and the mechanism that correlates local atomic configurations and phase transitions in metallic glasses.

  7. The Incorporation of Strontium to Improve Bone-Regeneration Ability of Mesoporous Bioactive Glasses

    Directory of Open Access Journals (Sweden)

    Sonia Fiorilli

    2018-04-01

    Full Text Available Over the recent years, mesoporous bioactive glasses (MBGs gained interest as bone regeneration systems, due to their excellent bioactivity and ability to release therapeutic molecules. In order to improve the bone regeneration ability of MBGs, the incorporation of Sr2+ ions, due to its recognized pro-osteogenenic potential, represents a very promising strategy. In this study, MBGs based on the SiO2–CaO system and containing different percentages (2 and 4 mol % of strontium were prepared by two synthesis methods, in the form of microspheres and nanoparticles. Sr-containing MBGs were characterized by FE-SEM, XRD and N2 adsorption/desorption analysis. The in vitro bioactivity in SBF resulted excellent. The assessment of fibroblast cell (line L929 viability showed that Sr-containing MBGs were biocompatible both in form of micro- and nanoparticles. The osteogenic response of osteoblast-like SAOS-2 cells was investigated by analysing the expression of GAPDH, COL1a1, RANKL, SPARC, OPG and ALPL genes, as cell differentiation markers. The results indicate that the incorporation of Sr into MBG is beneficial for bone regeneration as promotes a pro-osteogenic effect, paving the way to the design of advanced devices enabled by these nanocarriers also in combination with drug release, for the treatment of bone pathologies, particularly in patients with osteoporosis.

  8. Preparation and characterization of Zr-based bulk metallic glasses in form of plate

    International Nuclear Information System (INIS)

    Pilarczyk, Wirginia

    2014-01-01

    Highlights: • Zr-based BMGs in form of plate was successful produced by die pressure casting method. • Many techniques have been used to characterize the structure of Zr 55 Cu 30 Ni 5 Al 10 alloy. • The calculated GFA parameters show that the alloy exhibits satisfactory GFA. • The studies reveal that tested as-cast Zr-based alloy is in amorphous state. - Abstract: Zr-based bulk metallic glasses present an interesting combination of physical, chemical and mechanical properties. During the last decade, intensive progress has been made and a number of applications have been suggested for these materials. In order to successfully apply these materials, it is necessary to accurately characterize their structure, thermal stability and other properties accurately. The aim of the presented work is the manufacturing, examination of the structure of selected Zr-based bulk metallic alloys and confirmation of an amorphous structure using X-ray analysis, microscopic observation and thermal analysis. In this work, the Zr-based bulk metallic glasses in form of plate was successful produced by die pressure casting method. Designed scientific station for casting zirconium based amorphous alloys in the form of plates and rods with selected dimensions is in our university a comprehensive method for achieving amorphous materials which enables us to maintain repeatability of as-cast samples with the amorphous structure and the assumed dimensions range. The diffraction pattern and exothermic reaction as well as the fracture surface morphology reveal that studied as-cast Zr-based alloy is in amorphous state. The calculated GFA parameters show that the alloy exhibits satisfactory glass-forming ability in form of studied plate. These obtained values can suggest that studied alloys are suitable materials for further planned practical application at welding process. The success of Zr-based bulk metallic glasses production in form of plate with obtained sizes is important for future

  9. Fragility correlates thermodynamic and kinetic properties of glass forming liquids

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, C.Narayana [Maharani’s Science College for Women, Bangalore 560001 (India); Viswanatha, R.; Chethana, B.K. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India); Gowda, V.C.Veeranna [Government First Grade College, Jayanagara, Bangalore 560070 (India); Rao, K.J., E-mail: kalyajrao@yahoo.co.in [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India)

    2015-03-15

    Graphical abstract: The suggested new fragility parameter correlates viscosity and configurational entropy. - Highlights: • A new fragility function, F=ΔT/ΔC{sub p}×C{sub p}{sup l}/T{sub g} has been proposed. • A three parameter viscosity function using the new F reproduces Angell fragility plot. • A new ΔC{sub p} function is derived which directly relates Adam–Gibbs function with the fragility based viscosity function. - Abstract: In our earlier communication we proposed a simple fragility determining function, ([NBO]/V{sub m}{sup 3}T{sub g}), which we have now used to analyze several glass systems using available thermal data. A comparison with similar fragility determining function, ΔC{sub p}/C{sub p}{sup l}, introduced by Chryssikos et al. in their investigation of lithium borate glasses has also been performed and found to be more convenient quantity for discussing fragilities. We now propose a new function which uses both ΔC{sub p} and ΔT and which gives a numerical fragility parameter, F whose value lies between 0 and 1 for glass forming liquids. F can be calculated through the use of measured thermal parameters ΔC{sub p}, C{sub p}{sup l}, T{sub g} and T{sub m}. Use of the new fragility values in reduced viscosity equation reproduces the whole range of viscosity curves of the Angell plot. The reduced viscosity equation can be directly compared with the Adam–Gibbs viscosity equation and a heat capacity function can be formulated which reproduces satisfactorily the ΔC{sub p} versus ln(T{sub r}) curves and hence the configurational entropy.

  10. Consolidated waste forms: glass marbles and ceramic pellets

    International Nuclear Information System (INIS)

    Treat, R.L.; Rusin, J.M.

    1982-05-01

    Glass marbles and ceramic pellets have been developed at Pacific Northwest Laboratory as part of the multibarrier concept for immobilizing high-level radioactive waste. These consolidated waste forms served as substrates for the application of various inert coatings and as ideal-sized particles for encapsulation in protective matrices. Marble and pellet formulations were based on existing defense wastes at Savannah River Plant and proposed commercial wastes. To produce marbles, glass is poured from a melter in a continuous stream into a marble-making device. Marbles were produced at PNL on a vibratory marble machine at rates as high as 60 kg/h. Other marble-making concepts were also investigated. The marble process, including a lead-encapsulation step, was judged as one of the more feasible processes for immobilizing high-level wastes. To produce ceramic pellets, a series of processing steps are required, which include: spray calcining - to dry liquid wastes to a powder; disc pelletizing - to convert waste powders to spherical pellets; sintering - to densify pellets and cause desired crystal formation. These processing steps are quite complex, and thereby render the ceramic pellet process as one of the least feasible processes for immobilizing high-level wastes

  11. Immobilization of radwastes in glass containers and products formed thereby

    International Nuclear Information System (INIS)

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

    1982-01-01

    A mixture of glass packing and radioactive or other toxic material is placed in a solid glass container, and the container is heated to drive off volatile components and collapse and seal the container

  12. Glass as a waste form for the immobilization of plutonium

    International Nuclear Information System (INIS)

    Bates, J.K.; Ellison, A.J.G.; Emery, J.W.; Hoh, J.C.

    1995-01-01

    Several alternatives for disposal of surplus plutonium are being considered. One method is incorporating Pu into glass and in this paper we discuss the development and corrosion behavior of an alkali-tin-silicate glass and update results in testing Pu doped Defense Waste Processing Facility (DWPF) reference glasses. The alkali-tin-silicate glass was engineered to accommodate a high Pu loading and to be durable under conditions likely to accelerate glass reaction. The glass dissolves about 7 wt% Pu together with the neutron absorber Gd, and under test conditions expected to accelerate the glass reaction with water, is resistant to corrosion. The Pu and the Gd are released from the glass at nearly the same rate in static corrosion tests in water, and are not segregated into surface alteration phases when the glass is reacted in water vapor. Similar results for the behavior of Pu and Gd are found for the DWPF reference glasses, although the long-term rate of reaction for the reference glasses is more rapid than for the alkali-tin-silicate glass

  13. Structural disorder in metallic glass-forming liquids.

    Science.gov (United States)

    Pan, Shao-Peng; Feng, Shi-Dong; Wang, Li-Min; Qiao, Jun-Wei; Niu, Xiao-Feng; Dong, Bang-Shao; Wang, Wei-Min; Qin, Jing-Yu

    2016-06-09

    We investigated structural disorder by a new structural parameter, quasi-nearest atom (QNA), in atomistic configurations of eight metallic glass-forming systems generated through molecular dynamics simulations at various temperatures. Structural analysis reveals that the scaled distribution of the number of QNA appears to be an universal property of metallic liquids and the spatial distribution of the number of QNA displays to be clearly heterogeneous. Furthermore, the new parameter can be directly correlated with potential energy and structural relaxation at the atomic level. Some straightforward relationships between QNA and other properties (per-atom potential energy and α-relaxation time) are introduced to reflect structure-property relationship in metallic liquids. We believe that the new structural parameter can well reflect structure disorder in metallic liquids and play an important role in understanding various properties in metallic liquids.

  14. Compressive deformation of in situ formed bulk metallic glass composites

    Energy Technology Data Exchange (ETDEWEB)

    Clausen, B. [Lujan Neutron Science Center, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lee, S.Y. [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States); Ustuendag, E. [Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011 (United States)]. E-mail: ustundag@iastate.edu; Kim, C.P. [Liquidmetal Technologies, Lake Forest, CA 92630 (United States); Brown, D.W. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Bourke, M.A.M. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2006-02-15

    A bulk metallic glass matrix composite with dendc second phase precipitates was investigated using neutron diffraction and self-consistent modeling (SCM) to ascertain its deformation mechanisms. The compressive behavior of both the composite and the second phase (in its monolithic form) were investigated. The diffraction data were compared to the predictions of a new SCM resulting in good agreement. For the first time, this model considered both amorphous and crystalline phases and allowed the calculation of single crystal elastic constants from polycrystalline diffraction data. It was shown that the ductile second phase yielded first upon loading, and this was followed by multiple shear band formation in the matrix, a process which enhanced the ductility of the composite.

  15. Compressive deformation of in situ formed bulk metallic glass composites

    International Nuclear Information System (INIS)

    Clausen, B.; Lee, S.Y.; Ustuendag, E.; Kim, C.P.; Brown, D.W.; Bourke, M.A.M.

    2006-01-01

    A bulk metallic glass matrix composite with dendritic second phase precipitates was investigated using neutron diffraction and self-consistent modeling (SCM) to ascertain its deformation mechanisms. The compressive behavior of both the composite and the second phase (in its monolithic form) were investigated. The diffraction data were compared to the predictions of a new SCM resulting in good agreement. For the first time, this model considered both amorphous and crystalline phases and allowed the calculation of single crystal elastic constants from polycrystalline diffraction data. It was shown that the ductile second phase yielded first upon loading, and this was followed by multiple shear band formation in the matrix, a process which enhanced the ductility of the composite

  16. Evaluation of the ability of Acinetobacter baumannii to form biofilms on six different biomedical relevant surfaces.

    Science.gov (United States)

    Greene, C; Wu, J; Rickard, A H; Xi, C

    2016-10-01

    The human opportunistic pathogen, Acinetobacter baumannii, has the propensity to form biofilms and frequently cause medical device-related infections in hospitals. However, the physio-chemical properties of medical surfaces, in addition to bacterial surface properties, will affect colonization and biofilm development. The objective of this study was to compare the ability of A. baumannii to form biofilms on six different materials common to the hospital environment: glass, porcelain, stainless steel, rubber, polycarbonate plastic and polypropylene plastic. Biofilms were developed on material coupons in a CDC biofilm reactor. Biofilms were visualized and quantified using fluorescent staining and imaged using confocal laser scanning microscopy (CLSM) and by direct viable cell counts. Image analysis of CLSM stacks indicated that the mean biomass values for biofilms grown on glass, rubber, porcelain, polypropylene, stainless steel and polycarbonate were 0·04, 0·26, 0·62, 1·00, 2·08 and 2·70 μm(3) /μm(2) respectively. Polycarbonate developed statistically more biofilm mass than glass, rubber, porcelain and polypropylene. Viable cell counts data were in agreement with the CLSM-derived data. In conclusion, polycarbonate was the most accommodating surface for A. baumannii ATCC 17978 to form biofilms while glass was least favourable. Alternatives to polycarbonate for use in medical and dental devices may need to be considered. In the hospital environment, Acinetobacter baumannii is one of the most persistent and difficult to control opportunistic pathogens. The persistence of A. baumannii is due, in part, to its ability to colonize surfaces and form biofilms. This study demonstrates that A. baumannii can form biofilms on a variety of different surfaces and develops substantial biofilms on polycarbonate - a thermoplastic material that is often used in the construction of medical devices. The findings highlight the need to further study the in

  17. Production of sodalite waste forms by addition of glass

    International Nuclear Information System (INIS)

    Pereira, C.

    1995-01-01

    Spent nuclear fuel can be treated in a molten salt electrorefiner for conversion into metal and mineral waste forms for geologic disposal. Sodalite is one of the mineral waste forms under study. Fission products in the molten salt are ion-exchanged into zeolite A, which is converted to sodalite and consolidated. Sodalite can be formed directly from mixtures of salt and zeolite A at temperatures above 975 K; however, nepheline is usually produced as a secondary phase. Addition of small amounts of glass frit to the mixture reduced nepheline formation significantly. Loss of fission products was not observed for reaction below 1000 K. Hot-pressing of the sodalite powders yielded dense pellets (∼2.3 g/cm 3 ) without any loss of fission product species. Normalized release rates were below 1 g/m 2 ·day for pre-washed samples in 28-day leach tests based on standard MCC-1 tests but increased with the presence of free salt on the sodalite

  18. Basaltic glasses from Iceland and the deep sea: Natural analogues to borosilicate nuclear waste-form glass

    International Nuclear Information System (INIS)

    Jercinovic, M.J.; Ewing, R.C.

    1987-12-01

    The report provides a detailed analysis of the alteration process and products for natural basaltic glasses. Information of specific applicability to the JSS project include: * The identification of typical alteration products which should be expected during the long-term corrosion process of low-silica glasses. The leached layers contain a relatively high proportion of crystalline phases, mostly in the form of smectite-type clays. Channels through the layer provide immediate access of solutions to the fresh glass/alteration layer interface. Thus, glasses are not 'protected' from further corrosion by the surface layer. * Corrosion proceeds with two rates - an initial rate in silica-undersaturated environments and a long-term rate in silica-saturated environments. This demonstrates that there is no unexpected change in corrosion rate over long periods of time. The long-term corrosion rate is consistent with that of borosilicate glasses. * Precipitation of silica-containing phases can result in increased alteration of the glass as manifested by greater alteration layer thicknesses. This emphasizes the importance of being able to predict which phases form during the reaction sequence. * For natural basaltic glasses the flow rate of water and surface area of exposed glass are critical parameters in minimizing glass alteration over long periods of time. The long-term stability of basalt glasses is enhanced when silica concentrations in solution are increased. In summary, there is considerable agreement between corrosion phenomena observed for borosilicate glasses in the laboratory and those observed for natural basalt glasses of great age. (With 121 refs.) (authors)

  19. Comparison of the corrosion behaviors of the glass-bonded sodalite ceramic waste form and reference HLW glasses

    International Nuclear Information System (INIS)

    Ebert, W. L.; Lewis, M. A.

    1999-01-01

    A glass-bonded sodalite ceramic waste form is being developed for the long-term immobilization of salt wastes that are generated during spent nuclear fuel conditioning activities. A durable waste form is prepared by hot isostatic pressing (HIP) a mixture of salt-loaded zeolite powders and glass frit. A mechanistic description of the corrosion processes is being developed to support qualification of the CWF for disposal. The initial set of characterization tests included two standard tests that have been used extensively to study the corrosion behavior of high level waste (HLW) glasses: the Material Characterization Center-1 (MCC-1) Test and the Product Consistency Test (PCT). Direct comparison of the results of tests with the reference CWF and HLW glasses indicate that the corrosion behaviors of the CWF and HLW glasses are very similar

  20. Calculation of glass forming ranges in Al-Ni-RE (Ce, La, Y) ternary alloys and their sub-binaries based on Miedema's model

    International Nuclear Information System (INIS)

    Sun, S.P.; Yi, D.Q.; Liu, H.Q.; Zang, B.; Jiang, Y.

    2010-01-01

    Research highlights: → A method based on semi-empirical Miedema's and Toop's model for predicting glass forming range of ternary alloy system has been systematically described. → The method is superior to conventional models by considering the effect of the thermodynamic asymmetric component when dealing with a ternary alloy system. → The glass forming ranges of Al-Ni-RE (Al-Ni-Ce, Al-Ni-Y and Al-Ni-La) systems and their sub-binaries have been successfully calculated. → The present calculations using the method are in well agreement with experiments. → This model is especially useful for predicting the glass forming range of ternary alloy system because the calculations do not require experimental data. - Abstract: A method based on the semi-empirical Miedema's and Toop's model for calculating the glass forming range of a ternary alloy system was systematically described. The method is superior to conventional models by considering the effect of the thermodynamic asymmetric component when dealing with a ternary alloy system. Using this method, the glass forming ranges of Al-Ni-RE (Ce, La, Y) systems and their sub-binaries were successfully predicted. The mixing enthalpy and mismatch entropy were calculated, and their effects on the glass forming abilities of Al-Ni-RE (Ce, La, Y) systems were also discussed. The glass forming abilities of Al-Ni-Ce, Al-Ni-La and Al-Ni-Y are found to be close. The calculated glass forming ranges agree with experiments well. Meanwhile, the enthalpy change from amorphous phase to solid solution in the glass forming ranges was calculated, and the results suggest that those alloys close to the Ni-RE sub-binary system have higher glass forming abilities.

  1. Waste vitrification: prediction of acceptable compositions in a lime-soda-silica glass-forming system

    International Nuclear Information System (INIS)

    Gilliam, T.M.; Jantzen, C.M.

    1996-10-01

    A model is presented based upon calculated bridging oxygens which allows the prediction of the region of acceptable glass compositions for a lime-soda-silica glass-forming system containing mixed waste. The model can be used to guide glass formulation studies (e.g., treatability studies) or assess the applicability of vitrification to candidate waste streams

  2. Simulation of an Aspheric Glass Lens Forming Behavior in Progressive GMP Process

    International Nuclear Information System (INIS)

    Chang, Sung Ho; Lee, Young Min; Kang, Jeong Jin; Hong, Seok Kwan; Shin, Gwang Ho; Heo, Young Moo; Jung, Tae Sung

    2007-01-01

    Recently, GMP(Glass Molding Press) process is mainly used to produce aspheric glass lenses. Because glass lens is heated at high temperature above Tg (Transformation Temperature) for forming the glass, the quality of aspheric glass lens is deteriorated by residual stresses which are generated in a aspheric glass lens after forming. In this study, as a fundamental study to develop the mold for progressive GMP process, we conducted a aspheric glass lens forming simulation. Prior to a aspheric glass lens forming simulation, compression and thermal conductivity tests were carried out to obtain mechanical and thermal properties of K-PBK40 which is newly developed material for precision molding, and flow characteristics of K-PBK40 were obtained at high temperature. Then, using the flow characteristics obtained, compression simulation was carried out and compared with the experimental result for the purpose of verifying the obtained flow characteristics. Finally, a glass lens press simulation in progressive GMP process was carried out and we could forecast the shape of deformed glass lenses and residual stresses contribution in the structure of deformed glass lenses after forming

  3. Metastability and thermophysical properties of metallic bulk glass forming alloys

    International Nuclear Information System (INIS)

    Wunderlich, R.K.; Fecht, H.J.

    1998-01-01

    The absence of crystallization over a wide time/temperature window can be used to produce bulk metallic glass by relatively slow cooling of the melt. For a number of alloys, including several multicomponent Zr-based alloys, the relevant thermodynamic and thermomechanical properties of the metastable glassy and undercooled liquid states have been measured below and above the glass transition temperature. These measurements include specific heat, viscosity, volume, and elastic properties as a function of temperature. As a result, it becomes obvious that the maximum undercooling for these alloys is given by an isentropic condition before an enthalpic or isochoric instability is reached. Alternatively, these glasses can also be produced by mechanical alloying, thus replacing the thermal disorder by static disorder and resulting in the same thermodynamic glass state. During heating through the undercooled liquid, a nanoscale phase separation occurs for most glasses as a precursor of crystallization

  4. On the star-forming ability of Molecular Clouds

    Science.gov (United States)

    Anathpindika, S.; Burkert, A.; Kuiper, R.

    2018-02-01

    The star-forming ability of a molecular cloud depends on the fraction of gas it can cycle into the dense-phase. Consequently, one of the crucial questions in reconciling star formation in clouds is to understand the factors that control this process. While it is widely accepted that the variation in ambient conditions can alter significantly the ability of a cloud to spawn stars, the observed variation in the star-formation rate in nearby clouds that experience similar ambient conditions, presents an interesting question. In this work, we attempted to reconcile this variation within the paradigm of colliding flows. To this end we develop self-gravitating, hydrodynamic realizations of identical flows, but allowed to collide off-centre. Typical observational diagnostics such as the gas-velocity dispersion, the fraction of dense-gas, the column density distribution (N-PDF), the distribution of gas mass as a function of K-band extinction and the strength of compressional/solenoidal modes in the post-collision cloud were deduced for different choices of the impact parameter of collision. We find that a strongly sheared cloud is terribly inefficient in cycling gas into the dense phase and that such a cloud can possibly reconcile the sluggish nature of star formation reported for some clouds. Within the paradigm of cloud formation via colliding flows this is possible in case of flows colliding with a relatively large impact parameter. We conclude that compressional modes - though probably essential - are insufficient to ensure a relatively higher star-formation efficiency in a cloud.

  5. Transparent phosphosilicate glasses containing crystals formed during cooling of melts

    DEFF Research Database (Denmark)

    Liu, S. J.; Zhang, Yanfei; He, W.

    2011-01-01

    The effect of P2O5-SiO2 substitution on spontaneous crystallization of SiO2-Al2O3-P2O5- Na2O-MgO melts during cooling was studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and rotation viscometry. Results show that addition of P2O5 leads...... to amorphous phase separation (APS), i.e., phosphate- and silicate-rich phases. It is due to the tendency of Mg2+ to form [MgO4] linking with [SiO4]. Molar substitution of P2O5 for SiO2 enhances the network polymerization of silicate-rich phase in the melts, and thereby the spontaneous crystallization of cubic...... Na2MgSiO4 is also enhanced during cooling of the melts. In addition, the sizes of the local crystalline and separated glassy domains are smaller than the wavelength of the visible light, and this leads to the transparency of the obtained glasses containing crystals....

  6. Glass forming in La2O3-TiO2-ZrO2 ternary system by containerless processing

    Science.gov (United States)

    Kaneko, Masashi; Kentei Yu, Yu; Kumar, Vijaya; Masuno, Atsunobu; Inoue, Hiroyuki; Odawara, Osamu; Yoda, Shinichi

    The containerless processing is an appropriate method to create new glasses, because it sup-presses nucleation at the boundary between liquid and crucible during solidification and it enables molten samples to be solidified without crystallization. Recently, we have succeeded in forming BaTi2 O5 glass in the bulk state by using an aerodynamic levitation furnace. BaTi2 O5 glass includes no traditional glass network former and it possesses high electric permittivity [1, 2]. From the point of view of optical application, BaTi2 O5 glass has high refractive indices over 2.1. BaTi2 O5 glass, however, vitrify only in a small sphere, and it crystallize when its diameter exceed 1.5 mm. In order to synthesize new titanate oxide glasses which possess higher refractive indices and larger diameter than BaTi2 O5 , La and Zr can be used as substitutive components. When Ba is replaced with La, refractive indices are expected to increase because of the heavier element. The addition of a third element is thought to be effective for enhance-ment of glass formation ability and Zr can be a candidate because Ti and Zr are homologous. In this research, we have succeeded in forming new bulk glass in La2 O3 -TiO2 -ZrO2 ternary system by means of the aerodynamic levitation furnace. We investigated the glass forming region, thermal properties and optical properties of La2 O3 -TiO2 -ZrO2 glass. Glass transition temperature, crystallization temperature, density, refractive indices and transmittance spectra were varied depending on the chemical composition. Reference [1] J. Yu et al, "Fabrication of BaTi2O5 Glass-Ceramics with Unusual Dielectric Properties during Crystallization", Chem-istry of Materials, 18 (2006) 2169-2173. [2] J. Yu et al., "Comprehensive Structural Study of Glassy and Metastable Crystalline BaTi2O5", Chemistry of Materials, 21 (2009) 259-263.

  7. Bioactive glass coupling with natural polyphenols: Surface modification, bioactivity and anti-oxidant ability

    Energy Technology Data Exchange (ETDEWEB)

    Cazzola, Martina [Politecnico di Torino, Department of Applied Science and Technology, Institute of Materials Physics and Engineering, C.so Duca degli Abruzzi 24, Torino 10129 (Italy); Corazzari, Ingrid [Università degli Studi di Torino, Department of Chemistry, Via Pietro Giuria 7, Torino 10125 (Italy); Centro Interdipartimentale “G. Scansetti” per lo studio degli amianti e di altri particolati nocivi, Via Pietro Giuria 9, 10125 Torino (Italy); Prenesti, Enrico [Università degli Studi di Torino, Department of Chemistry, Via Pietro Giuria 7, Torino 10125 (Italy); Bertone, Elisa [Politecnico di Torino, Department of Applied Science and Technology, Institute of Materials Physics and Engineering, C.so Duca degli Abruzzi 24, Torino 10129 (Italy); Vernè, Enrica, E-mail: enrica.verne@polito.it [Politecnico di Torino, Department of Applied Science and Technology, Institute of Materials Physics and Engineering, C.so Duca degli Abruzzi 24, Torino 10129 (Italy); Ferraris, Sara [Politecnico di Torino, Department of Applied Science and Technology, Institute of Materials Physics and Engineering, C.so Duca degli Abruzzi 24, Torino 10129 (Italy)

    2016-03-30

    Graphical abstract: - Highlights: • Surface functionalization of bioactive glass with biomolecules has been optimized. • Biomolecules are present and active on the glass surface after functionalization. • Biomolecules affect deposition kinetics and morphology of hydroxyapatite. • Free radical scavenging activity is seen for the first time on bioactive glasses. - Abstract: Polyphenols are actually achieving an increasing interest due to their potential health benefits, such as antioxidant, anticancer, antibacterial and bone stimulation abilities. However their poor bioavailability and stability hamper an effective clinical application as therapeutic principles. The opportunity to couple these biomolecules with synthetic biomaterials, in order to obtain local delivery at the site of interest, improve their bioavailability and stability and combine their properties with the ones of the substrate, is a challenging opportunity for the biomedical research. A silica based bioactive glass, CEL2, has been successfully coupled with gallic acid and natural polyphenols extracted from red grape skins and green tea leaves. The effectiveness of grafting has been verified by means of XPS analyses and the Folin&Ciocalteu tests. In vitro bioactivity has been investigated by soaking in simulated body fluid (SBF). Surface modification after functionalization and early stage reactivity in SBF have been studied by means of zeta potential electrokinetic measurements in KCl and SBF. Finally the antioxidant properties of bare and modified bioactive glasses has been investigated by means of the evaluation of free radical scavenging activity by Electron Paramagnetic Resonance (EPR)/spin trapping technique after UV photolysis of H{sub 2}O{sub 2} highlighting scavenging activity of the bioactive glass.

  8. Evaluation of lead-iron-phosphate glass as a high-level waste form

    International Nuclear Information System (INIS)

    Chick, L.A.; Bunnell, L.R.; Strachan, D.M.; Kissinger, H.E.; Hodges, F.N.

    1986-01-01

    The lead-iron-phosphate (Pb-Fe-P) nuclear waste glass developed at Oak Ridge National Laboratory (ORNL) was evaluated for its potential as an improvement over the current reference waste form, borosilicate (B-Si) glass. Vitreous Pb-Fe-P glass appears to have substantially better chemical durability than B-Si glass. However, severe crystallization leading to deteriorated chemical durability would result if this glass were poured into large canisters, as is presently done with B-Si glass. Cesium leach rates from this crystallized material are orders of magnitude greater than those from B-Si glass. Therefore, to realize the performance advantages of the Pb-Fe-P material in a nuclear waste form, it would be necessary to process it so that it is cooled rapidly, thus retaining its vitreous structure

  9. Evaluation of lead-iron-phosphate glass as a high-level waste form

    International Nuclear Information System (INIS)

    Chick, L.A.; Bunnell, L.R.; Strachan, D.M.; Kissinger, H.E.; Hodges, F.N.

    1986-01-01

    The lead-iron-phosphate nuclear waste glass developed at Oak Ridge National Laboratory (ORNL) was evaluated for its potential as an improvement over the current reference waste form, borosilicate glass. Vitreous lead-iron-phosphate glass appears to have substantially better chemical durability than borosilicate glass. However, severe crystallization leading to deteriorated chemical durability would result if this glass were poured into large canisters as is presently done with borosilicate glass. Cesium leach rates from this crystallized material are orders of magnitude greater than those from borosilicate glass. Therefore, in order to realize the performance advantages of the lead-iron-phosphate material in a nuclear waste form, it would be necessary to process it so that it is rapidly cooled, thus retaining its vitreous structure. 22 refs., 4 figs., 4 tabs

  10. Preparation and characterization of Zr-based bulk metallic glasses in form of plate

    Energy Technology Data Exchange (ETDEWEB)

    Pilarczyk, Wirginia, E-mail: wirginia.pilarczyk@polsl.pl

    2014-12-05

    Highlights: • Zr-based BMGs in form of plate was successful produced by die pressure casting method. • Many techniques have been used to characterize the structure of Zr{sub 55}Cu{sub 30}Ni{sub 5}Al{sub 10} alloy. • The calculated GFA parameters show that the alloy exhibits satisfactory GFA. • The studies reveal that tested as-cast Zr-based alloy is in amorphous state. - Abstract: Zr-based bulk metallic glasses present an interesting combination of physical, chemical and mechanical properties. During the last decade, intensive progress has been made and a number of applications have been suggested for these materials. In order to successfully apply these materials, it is necessary to accurately characterize their structure, thermal stability and other properties accurately. The aim of the presented work is the manufacturing, examination of the structure of selected Zr-based bulk metallic alloys and confirmation of an amorphous structure using X-ray analysis, microscopic observation and thermal analysis. In this work, the Zr-based bulk metallic glasses in form of plate was successful produced by die pressure casting method. Designed scientific station for casting zirconium based amorphous alloys in the form of plates and rods with selected dimensions is in our university a comprehensive method for achieving amorphous materials which enables us to maintain repeatability of as-cast samples with the amorphous structure and the assumed dimensions range. The diffraction pattern and exothermic reaction as well as the fracture surface morphology reveal that studied as-cast Zr-based alloy is in amorphous state. The calculated GFA parameters show that the alloy exhibits satisfactory glass-forming ability in form of studied plate. These obtained values can suggest that studied alloys are suitable materials for further planned practical application at welding process. The success of Zr-based bulk metallic glasses production in form of plate with obtained sizes is

  11. Glass Ceramic Waste Forms for Combined CS+LN+TM Fission Products Waste Streams

    International Nuclear Information System (INIS)

    Crum, Jarrod V.; Turo, Laura A.; Riley, Brian J.; Tang, Ming; Kossoy, Anna; Sickafus, Kurt E.

    2010-01-01

    In this study, glass ceramics were explored as an alternative waste form for glass, the current baseline, to be used for immobilizing alkaline/alkaline earth + lanthanide (CS+LN) or CS+LN+transition metal (TM) fission-product waste streams generated by a uranium extraction (UREX+) aqueous separations type process. Results from past work on a glass waste form for the combined CS+LN waste streams showed that as waste loading increased, large fractions of crystalline phases precipitated upon slow cooling.(1) The crystalline phases had no noticeable impact on the waste form performance by the 7-day product consistency test (PCT). These results point towards the development of a glass ceramic waste form for treating CS+LN or CS+LN+TM combined waste streams. Three main benefits for exploring glass ceramics are: (1) Glass ceramics offer increased solubility of troublesome components in crystalline phases as compared to glass, leading to increased waste loading; (2) The crystalline network formed in the glass ceramic results in higher heat tolerance than glass; and (3) These glass ceramics are designed to be processed by the same melter technology as the current baseline glass waste form. It will only require adding controlled canister cooling for crystallization into a glass ceramic waste form. Highly annealed waste form (essentially crack free) with up to 50X lower surface area than a typical High-Level Waste (HLW) glass canister. Lower surface area translates directly into increased durability. This was the first full year of exploring glass ceramics for the Option 1 and 2 combined waste stream options. This work has shown that dramatic increases in waste loading are achievable by designing a glass ceramic waste form as an alternative to glass. Table S1 shows the upper limits for heat, waste loading (based on solubility), and the decay time needed before treatment can occur for glass and glass ceramic waste forms. The improvements are significant for both combined waste

  12. Glass Ceramic Waste Forms for Combined CS+LN+TM Fission Products Waste Streams

    Energy Technology Data Exchange (ETDEWEB)

    Crum, Jarrod V.; Turo, Laura A.; Riley, Brian J.; Tang, Ming; Kossoy, Anna; Sickafus, Kurt E.

    2010-09-23

    In this study, glass ceramics were explored as an alternative waste form for glass, the current baseline, to be used for immobilizing alkaline/alkaline earth + lanthanide (CS+LN) or CS+LN+transition metal (TM) fission-product waste streams generated by a uranium extraction (UREX+) aqueous separations type process. Results from past work on a glass waste form for the combined CS+LN waste streams showed that as waste loading increased, large fractions of crystalline phases precipitated upon slow cooling.[1] The crystalline phases had no noticeable impact on the waste form performance by the 7-day product consistency test (PCT). These results point towards the development of a glass ceramic waste form for treating CS+LN or CS+LN+TM combined waste streams. Three main benefits for exploring glass ceramics are: (1) Glass ceramics offer increased solubility of troublesome components in crystalline phases as compared to glass, leading to increased waste loading; (2) The crystalline network formed in the glass ceramic results in higher heat tolerance than glass; and (3) These glass ceramics are designed to be processed by the same melter technology as the current baseline glass waste form. It will only require adding controlled canister cooling for crystallization into a glass ceramic waste form. Highly annealed waste form (essentially crack free) with up to 50X lower surface area than a typical High-Level Waste (HLW) glass canister. Lower surface area translates directly into increased durability. This was the first full year of exploring glass ceramics for the Option 1 and 2 combined waste stream options. This work has shown that dramatic increases in waste loading are achievable by designing a glass ceramic waste form as an alternative to glass. Table S1 shows the upper limits for heat, waste loading (based on solubility), and the decay time needed before treatment can occur for glass and glass ceramic waste forms. The improvements are significant for both combined waste

  13. An Assessment of Binary Metallic Glasses: Correlations Between Structure, Glass Forming Ability and Stability (Preprint)

    Science.gov (United States)

    2011-07-01

    volume (via indentation, relaxation or positron annihilation ) are expected to significantly clarify structural descriptions. Further insights may be... applicability of the concept of smaller spheres filling the interstices of larger spheres diminishes with decreasing difference in size, the efficient...alloys observed by Mossbauer spectroscopy and calorimetry’, Rapidly Quenched Metals, Proc. 4th International Conference on Rapidly Quenched Metals

  14. Radiation effects in glass and glass-ceramic waste forms for the immobilization of CANDU UO2 fuel reprocessing waste

    International Nuclear Information System (INIS)

    Tait, J.C.

    1993-05-01

    AECL has investigated three waste forms for the immobilization of high-level liquid wastes that would arise if used CANDU fuels were reprocessed at some time in the future to remove fissile materials for the fabrication of new power reactor fuel. These waste forms are borosilicate glasses, aluminosilicate glasses and titanosilicate glass-ceramics. This report discusses the potential effects of alpha, beta and gamma radiation on the releases of radionuclides from these waste forms as a result of aqueous corrosion by groundwaters that would be present in an underground waste disposal vault. The report discusses solid-state damage caused by radiation-induced atomic displacements in the waste forms as well as irradiation of groundwater solutions (radiolysis), and their potential effects on waste-form corrosion and radionuclide release. The current literature on radiation effects on borosilicate glasses and in ceramics is briefly reviewed, as are potential radiation effects on specialized waste forms for the immobilization of 129 I, 85 Kr and 14 C. (author). 104 refs., 9 tabs., 5 figs

  15. Anomalies in the Thermophysical Properties of Undercooled Glass-Forming Alloys

    Science.gov (United States)

    Hyers, Robert W.; Rogers, Jan R.; Kelton, Kenneth F.; Gangopadhyay, Anup

    2008-01-01

    The surface tension, viscosity, and density of several bulk metallic glass-forming alloys have been measured using noncontact techniques in the electrostatic levitation facility (ESL) at NASA Marshall Space Flight Center. All three properties show unexpected behavior in the undercooled regime. Similar deviations were previously observed in titanium-based quasicrystal-forming alloys,but the deviations in the properties of the glass-forming alloys are much more pronounced. New results for anomalous thermophysical properties in undercooled glass-forming alloys will be presented and discussed.

  16. Bioactive glass coupling with natural polyphenols: Surface modification, bioactivity and anti-oxidant ability

    Science.gov (United States)

    Cazzola, Martina; Corazzari, Ingrid; Prenesti, Enrico; Bertone, Elisa; Vernè, Enrica; Ferraris, Sara

    2016-03-01

    Polyphenols are actually achieving an increasing interest due to their potential health benefits, such as antioxidant, anticancer, antibacterial and bone stimulation abilities. However their poor bioavailability and stability hamper an effective clinical application as therapeutic principles. The opportunity to couple these biomolecules with synthetic biomaterials, in order to obtain local delivery at the site of interest, improve their bioavailability and stability and combine their properties with the ones of the substrate, is a challenging opportunity for the biomedical research. A silica based bioactive glass, CEL2, has been successfully coupled with gallic acid and natural polyphenols extracted from red grape skins and green tea leaves. The effectiveness of grafting has been verified by means of XPS analyses and the Folin&Ciocalteu tests. In vitro bioactivity has been investigated by soaking in simulated body fluid (SBF). Surface modification after functionalization and early stage reactivity in SBF have been studied by means of zeta potential electrokinetic measurements in KCl and SBF. Finally the antioxidant properties of bare and modified bioactive glasses has been investigated by means of the evaluation of free radical scavenging activity by Electron Paramagnetic Resonance (EPR)/spin trapping technique after UV photolysis of H2O2 highlighting scavenging activity of the bioactive glass.

  17. Distinct atomic structures of the Ni-Nb metallic glasses formed by ion beam mixing

    International Nuclear Information System (INIS)

    Tai, K. P.; Wang, L. T.; Liu, B. X.

    2007-01-01

    Four Ni-Nb metallic glasses are obtained by ion beam mixing and their compositions are measured to be Ni 77 Nb 23 , Ni 55 Nb 45 , Ni 31 Nb 69 , and Ni 15 Nb 85 , respectively, suggesting that a composition range of 23-85 at. % of Nb is favored for metallic glass formation in the Ni-Nb system. Interestingly, diffraction analyses show that the structure of the Nb-based Ni 31 Nb 69 metallic glass is distinctly different from the structure of the Nb-based Ni 15 Nb 85 metallic glass, as the respective amorphous halos are located at 2θ≅38 and 39 deg. To explore an atomic scale description of the Ni-Nb metallic glasses, an n-body Ni-Nb potential is first constructed with an aid of the ab initio calculations and then applied to perform the molecular dynamics simulation. Simulation results determine not only the intrinsic glass forming range of the Ni-Nb system to be within 20-85 at. % of Nb, but also the exact atomic positions in the Ni-Nb metallic glasses. Through a statistical analysis of the determined atomic positions, a new dominant local packing unit is found in the Ni 15 Nb 85 metallic glass, i.e., an icositetrahedron with a coordination number to be around 14, while in Ni 31 Nb 69 metallic glasses, the dominant local packing unit is an icosahedron with a coordination number to be around 12, which has been reported for the other metallic glasses. In fact, with increasing the irradiation dose, the Ni 31 Nb 69 metallic glasses are formed through an intermediate state of face-centered-cubic-solid solution, whereas the Ni 15 Nb 85 metallic glass is through an intermediate state of body-centered-cubic-solid solution, suggesting that the structures of the constituent metals play an important role in governing the structural characteristics of the resultant metallic glasses

  18. Effect of glass composition on waste form durability: A critical review

    International Nuclear Information System (INIS)

    Ellison, A.J.G.; Mazer, J.J.; Ebert, W.L.

    1994-11-01

    This report reviews literature concerning the relationship between the composition and durability of silicate glasses, particularly glasses proposed for immobilization of radioactive waste. Standard procedures used to perform durability tests are reviewed. It is shown that tests in which a low-surface area sample is brought into contact with a very large volume of solution provide the most accurate measure of the intrinsic durability of a glass composition, whereas high-surface area/low-solution volume tests are a better measure of the response of a glass to changes in solution chemistry induced by a buildup of glass corrosion products. The structural chemistry of silicate and borosilicate glasses is reviewed to identify those components with the strongest cation-anion bonds. A number of examples are discussed in which two or more cations engage in mutual bonding interactions that result in minima or maxima in the rheologic and thermodynamic properties of the glasses at or near particular optimal compositions. It is shown that in simple glass-forming systems such interactions generally enhance the durability of glasses. Moreover, it is shown that experimental results obtained for simple systems can be used to account for durability rankings of much more complex waste glass compositions. Models that purport to predict the rate of corrosion of glasses in short-term durability tests are evaluated using a database of short-term durability test results for a large set of glass compositions. The predictions of these models correlate with the measured durabilities of the glasses when considered in large groupings, but no model evaluated in this review provides accurate estimates of durability for individual glass compositions. Use of these models in long-term durability models is discussed. 230 refs

  19. Supercooled dynamics of glass-forming liquids and polymers under hydrostatic pressure

    Energy Technology Data Exchange (ETDEWEB)

    Roland, C M [Naval Research Laboratory, Chemistry Division, Code 6120, Washington, DC 20375-5342 (United States); Hensel-Bielowka, S [Institute of Physics, Silesian University, ul. Uniwersytecka 4, 40-007 Katowice (Poland); Paluch, M [Institute of Physics, Silesian University, ul. Uniwersytecka 4, 40-007 Katowice (Poland); Casalini, R [Naval Research Laboratory, Chemistry Division, Code 6120, Washington, DC 20375-5342 (United States); Chemistry Department, George Mason University, Fairfax, VA 22030 (United States)

    2005-06-01

    An intriguing problem in condensed matter physics is understanding the glass transition, in particular the dynamics in the equilibrium liquid close to vitrification. Recent advances have been made by using hydrostatic pressure as an experimental variable. These results are reviewed, with an emphasis in the insight provided into the mechanisms underlying the relaxation properties of glass-forming liquids and polymers.

  20. Machinable glass-ceramics forming as a restorative dental material.

    Science.gov (United States)

    Chaysuwan, Duangrudee; Sirinukunwattana, Krongkarn; Kanchanatawewat, Kanchana; Heness, Greg; Yamashita, Kimihiro

    2011-01-01

    MgO, SiO(2), Al(2)O(3), MgF(2), CaF(2), CaCO(3), SrCO(3), and P(2)O(5) were used to prepare glass-ceramics for restorative dental materials. Thermal properties, phases, microstructures and hardness were characterized by DTA, XRD, SEM and Vickers microhardness. Three-point bending strength and fracture toughness were applied by UTM according to ISO 6872: 1997(E). XRD showed that the glass crystallized at 892°C (second crystallization temperature+20°C) for 3 hrs consisted mainly of calcium-mica and fluorapatite crystalline phases. Average hardness (3.70 GPa) closely matched human enamel (3.20 GPa). The higher fracture toughness (2.04 MPa√m) combined with the hardness to give a lower brittleness index (1.81 µm(-1/2)) which indicates that they have exceptional machinability. Bending strength results (176.61 MPa) were analyzed by Weibull analysis to determine modulus value (m=17.80). Machinability of the calcium mica-fluorapatite glass-ceramic was demonstrated by fabricating with CAD/CAM.

  1. AN ALTERNATIVE HOST MATRIX BASED ON IRON PHOSPHATE GLASSES FOR THE VITRIFICATION OF SPECIALIZED WASTE FORMS

    International Nuclear Information System (INIS)

    Day, Delbert D.

    2000-01-01

    As mentioned above, the overall goal of this research project was to collect the scientific information essential to develop iron phosphate glass based nuclear wasteforms. The specific objectives of the project were: (1) Investigate the structure of binary iron phosphate glasses and it's dependence on the composition and melting atmosphere: Understand atomic arrangements and nature of the bonding. Establish structure-property relationships. Determine the compositions and melting conditions which optimize the critical properties of the base glass. (2) Understand the structure of iron phosphate wasteforms and it's dependence on the composition and melting atmosphere: Investigate how the waste elements are bonded and coordinated within the glass structure. Establish structure-property relationships for the waste glasses. Determine the compositions and melting atmosphere for which the critical properties of the waste forms would be optimum. (3) Determine the role(s) played by the valence states of iron ions and it's dependence on the composition and melting atmosphere: Understand the different roles of iron(II) and iron(III) ions in determining the critical properties of the base glass and the waste forms. Investigate how the iron valence and its significance depend on the composition and melting atmosphere. (4) Investigate glass forming and crystallization processes of the iron phosphate glasses and their waste forms: Understand the dependence of the glass forming and crystallization characteristics on overall glass composition and valence states of iron ions. Identify the products of devitrification and investigate the critical properties of these crystalline compounds which may adversely affect the chemical and physical properties of the waste forms

  2. Talc-silicon glass-ceramic waste forms for immobilization of high- level calcined waste

    International Nuclear Information System (INIS)

    Vinjamuri, K.

    1993-06-01

    Talc-silicon glass-ceramic waste forms are being evaluated as candidates for immobilization of the high level calcined waste stored onsite at the Idaho Chemical Processing Plant. These glass-ceramic waste forms were prepared by hot isostatically pressing a mixture of simulated nonradioactive high level calcined waste, talc, silicon and aluminum metal additives. The waste forms were characterized for density, chemical durability, and glass and crystalline phase compositions. The results indicate improved density and chemical durability as the silicon content is increased

  3. Evaluation of lead-iron-phosphate glass as a high-level waste form

    International Nuclear Information System (INIS)

    Chick, L.A.; Bunnell, L.R.; Strachan, D.M.; Kissinger, H.E.; Hodges, F.N.

    1986-09-01

    The lead-iron-phosphate (Pb-Fe-P) glass developed at Oak Ridge National Laboratory was evaluated for its potential as an improvement over the current reference nuclear waste form, borosilicate (B-Si) glass. The evaluation was conducted as part of the Second Generation HLW Technology Subtask of the Nuclear Waste Treatment Program at Pacific Northwest Laboratory. The purpose of this work was to investigate possible alternatives to B-Si glass as second-generation waste forms. While vitreous Pb-Fe-P glass appears to have substantially better chemical durability than B-Si glass, severe crystallization or devitrification leading to deteriorated chemical durability would result if this glass were poured into large canisters as is the procedure with B-Si glass. Cesium leach rates from this crystallized material are orders of magnitude greater than those from B-Si glass. Therefore, to realize the potential performance advantages of the Pb-Fe-P material in a nuclear waste form, the processing method would have to cool the material rapidly to retain its vitreous structure

  4. Infrared and Raman investigation of rare-earth phosphate glasses for potential use as radioactive waste forms

    International Nuclear Information System (INIS)

    Morgan, S.H.

    1989-01-01

    This project was designed to investigate the properties of the rare-earth phosphate glass systems CeO 2 -P 2 O 5 and Pr 2 O 3 -P 2 O 5 for potential use as radioactive waste glasses. The glass-forming region and optimum processing parameters of these glass systems were investigated. The structure of the host glasses and glassed loaded with simulated waste elements was investigated using Raman and infrared spectroscopy. Because of the radical differences in the spectra of the molybdenum-loaded glasses, the structure of the MoO 3 -P 2 O 5 glass system was also investigated. 29 refs., 8 figs., 2 tabs

  5. Early stage crystallization kinetics in metallic glass-forming alloys

    International Nuclear Information System (INIS)

    Louzguine-Luzgin, Dmitri V.

    2014-01-01

    Highlights: • Heterogeneous nucleation may precede the homogeneous one in an alloy. • High kinetic constants and the nucleation rate at the initial stage. • Metallic glasses have heterogeneous nucleation sites which saturate later. -- Abstract: The crystallization kinetics and structural changes of a few metallic glassy alloys were monitored using X-ray diffraction, transmission electron microscopy, differential scanning and isothermal calorimetry methods. Microstructural observations were used to estimate the nucleation and growth rates. A clear comparison of the differences in the crystallization kinetics in the metallic glassy samples is observed at the early and later crystallization stages

  6. Correlation between relaxations and plastic deformation, and elastic model of flow in metallic glasses and glass-forming liquids

    International Nuclear Information System (INIS)

    Wang Weihua

    2011-01-01

    We study the similarity and correlations between relaxations and plastic deformation in metallic glasses (MGs) and MG-forming liquids. It is shown that the microscope plastic events, the initiation and formation of shear bands, and the mechanical yield in MGs where the atomic sites are topologically unstable induced by applied stress, can be treated as the glass to supercooled liquid state transition induced by external shear stress. On the other hand, the glass transition, the primary and secondary relaxations, plastic deformation and yield can be attributed to the free volume increase induced flow, and the flow can be modeled as the activated hopping between the inherent states in the potential energy landscape. We then propose an extended elastic model to describe the flow based on the energy landscape theory. That is, the flow activation energy density is linear proportional to the instantaneous elastic moduli, and the activation energy density ρ E is determined to be a simple expression of ρ E =(10/11)G+(1/11)K. The model indicates that both shear and bulk moduli are critical parameters accounting for both the homogeneous and inhomogeneous flows in MGs and MG-forming liquids. The elastic model is experimentally certified. We show that the elastic perspectives offers a simple scenario for the flow in MGs and MG-forming liquids and are suggestive for understanding the glass transition, plastic deformation, and nature and characteristics of MGs

  7. Solution exchange corrosion testing with the glass-zeolite ceramic waste form in demineralized water at 900C

    International Nuclear Information System (INIS)

    Simpson, L. J.

    1998-01-01

    A ceramic waste form of glass-bonded zeolite is being developed for the long-term disposition of fission products and transuranic elements in wastes from the U.S. Department of Energy's spent nuclear fuel conditioning activities. Solution exchange corrosion tests were performed on the ceramic waste form and its potential base constituents of glass, zeolite 5A, and sodalite as part of an effort to qualify the ceramic waste form for acceptance into the Civilian Radioactive Waste Management System. Solution exchange tests were performed at 90 C by replacing 80 to 90% of the leachate with fresh demineralized water after set time intervals. The results from these tests provide information about corrosion mechanisms and the ability of the ceramic waste form and its constituent materials to retain waste components. The results from solution exchange tests indicate that radionuclides will be preferentially retained in the zeolites without the glass matrix and in the ceramic waste form, with respect to cations like Li, K, and Na. Release results have been compared for simulated waste from candidate ceramic waste forms with zeolite 5A and its constituent materials to determine the corrosion behavior of each component

  8. The production of advanced glass ceramic HLW forms using cold crucible induction melter

    International Nuclear Information System (INIS)

    Rutledge, V.J.; Maio, V.

    2013-01-01

    Cold Crucible Induction Melters (CCIM) will favorably change how High-Level radioactive Waste (from nuclear fuel recovery) is treated in a near future. Unlike the existing Joule-Heated Melters (JHM) currently in operation for the glass-based immobilization of High-Level Waste (HLW), CCIM offers unique material features that will increase melt temperatures, increase throughput, increase mixing, increase loading in the waste form, lower melter foot prints, eliminate melter corrosion and lower costs. These features not only enhance the technology for producing HLW forms, but also provide advantageous attributes to the waste form by allowing more durable alternatives to glass. It is concluded that glass ceramic waste forms that are tailored to immobilize fission products of HLW can be can be made from the HLW processed with the CCIM. The advantageous higher temperatures reached with the CCIM and unachievable with JHM allows the lanthanides, alkali, alkaline earths, and molybdenum to dissolve into a molten glass. Upon controlled cooling they go into targeted crystalline phases to form a glass ceramic waste form with higher waste loadings than achievable with borosilicate glass waste forms. Natural cooling proves to be too fast for the formation of all targeted crystalline phases

  9. Cesium Hydroxide Fusion Dissolution of Analytical Reference Glass-1 in Both Powder and Shard Form

    International Nuclear Information System (INIS)

    Coleman, C.J.; Spencer, W.A.

    1998-04-01

    CsOH has been shown to be an effective and convenient dissolution reagent for Analytical Reference Glass-1 (ARG-1). This glass standard was prepared from nonradioactive DWPF Start-up Glass. Therefore, its composition is similar to DWPF product glass and many of the glass matrices prepared at SRTC.The principal advantage of the CsOH fusion dissolution is that the reagent does not add the alkali metals Li, Na, and K usually needed by SRS customers. Commercially available CsOH is quite pure so that alkali metals can be measured accurately, often without blank corrections. CsOH fusions provide a single dissolution method for applicable glass to replace multiple dissolution schemes used by most laboratories. For example, SRTC glass samples are most commonly dissolved with a Na 2 O 2 -NaOH fusion (ref.1) and a microwave- assisted acid dissolution with HNO 3 -HF-H 3 BO 3 -HCl (ref.2). Othe laboratories use fusion methods based on KOH, LiBO 2 , and Na 2 CO 3 CsOH fusion approach reduces by half not only the work in the dissolution laboratory, but also in the spectroscopy laboratories that must analyze each solution.Experiments also revealed that glass shards or pellets are rapidly attacked if the flux temperature is raised considerably above the glass softening point. The softening point of ARG-1 glass is near 650 degrees C. Fusions performed at 750 degrees C provided complete dissolutions and accurate elemental analyses of shards. Successful dissolution of glass shards was demonstrated with CsOH, Na 2 O 2 , NaOH, KOH, and RbOH. Ability to dissolve glass shards is of considerable practical importance. Crushing glass to a fine powder is a slow and tedious task, especially for radioactive glasses dissolved in shielded cells. CsOH fusion of glass powder or shards is a convenient, cost-effective dissolution scheme applicable in SRTC, the DWPF, and the commercial glass industry

  10. Development of iodine waste forms using low-temperature sintering glass

    International Nuclear Information System (INIS)

    Krumhansl, James Lee; Nenoff, Tina Maria; Garino, Terry J.; Rademacher, David

    2010-01-01

    This presentation will describe our recent work on the use of low temperature-sintering glass powders mixed with either AgI or AgI-zeolite to produce a stable waste form. Radioactive iodine ( 129 I, half-life of 1.6 x 10 7 years) is generated in the nuclear fuel cycle and is of particular concern due to its extremely long half-life and its effects on human health. As part of the DOE/NE Advanced Fuel Cycle Initiative (AFCI), the separation of 129 I from spent fuel during fuel reprocessing is being studied. In the spent fuel reprocessing scheme under consideration, the iodine is released in gaseous form and collected using Ag-loaded zeolites, to form AgI. Although AgI has extremely low solubility in water, it has a relatively high vapor pressure at moderate temperatures (>550 C), thus limiting the thermal processing. Because of this, immobilization using borosilicate glass is not feasible. Therefore, a bismuth oxide-based glasses are being studied due to the low solubility of bismuth oxide in aqueous solution at pH > 7. These waste forms were processed at 500 C, where AgI volatility is low but the glass powder is able to first densify by viscous sintering and then crystallize. Since the glass is not melted, a more chemically stable glass can be used. The AgI-glass mixture was found to have high iodine leach resistance in these initial studies.

  11. Diffusion in confinement as a microscopic relaxation mechanism in glass-forming liquids

    International Nuclear Information System (INIS)

    Mamontov, Eugene

    2012-01-01

    Using quasielastic neutron scattering, we compare dynamics in single-element liquids, glass-forming selenium and non glass-forming gallium. There is a single jump-diffusion process in gallium, whereas in selenium there is also a faster, spatially localized process. The fast and slow processes describe β- and α-relaxation, respectively. We then analyze an archetypical glass-former, glycerol, to show that the two-component fit, with β- and α-relaxations explicitly separated, yields the correct value for the translational diffusion coefficient and provides information on the spatial localization of the β-relaxation that is not experimentally accessible otherwise.

  12. Effect of high pressure on the relaxation dynamics of glass-forming liquids

    Energy Technology Data Exchange (ETDEWEB)

    Paluch, M; Grzybowska, K; Grzybowski, A [Institute of Physics, Silesian University, ulica Uniwersytecka 4, 40-007 Katowice (Poland)

    2007-05-23

    A glass is usually formed by cooling a liquid at a rate sufficient to avoid crystallization. In the vicinity of the glass transition the structural relaxation time increases with lowering temperature in a non-Arrhenius fashion and the structural relaxation function reveals a non-Debye behaviour. However, liquid can be also vitrified by keeping it at a constant temperature and increasing the pressure. This pressure-induced transition to the glassy state is also accompanied by dramatic changes in the relaxation dynamics. Herein we discuss the behaviour of the structural relaxation times of glass-forming liquids and polymer melts under high pressure.

  13. Effect of high pressure on the relaxation dynamics of glass-forming liquids

    International Nuclear Information System (INIS)

    Paluch, M; Grzybowska, K; Grzybowski, A

    2007-01-01

    A glass is usually formed by cooling a liquid at a rate sufficient to avoid crystallization. In the vicinity of the glass transition the structural relaxation time increases with lowering temperature in a non-Arrhenius fashion and the structural relaxation function reveals a non-Debye behaviour. However, liquid can be also vitrified by keeping it at a constant temperature and increasing the pressure. This pressure-induced transition to the glassy state is also accompanied by dramatic changes in the relaxation dynamics. Herein we discuss the behaviour of the structural relaxation times of glass-forming liquids and polymer melts under high pressure

  14. Corrosion behaviors of a glass-bonded sodalite ceramic waste form and its constituents

    International Nuclear Information System (INIS)

    Lewis, M. A.; Ebert, W. L.; Morss, L.

    1999-01-01

    A ceramic waste form (CWF) of glass bonded sodalite is being developed as a waste form for the long-term immobilization of fission products and transuranic elements from the U.S. Department of Energy's activities on spent nuclear fuel conditioning. A durable waste form was prepared by hot isostatic pressing (HIP) a mixture of salt-loaded zeolite powders and glass frit. During HIP the zeolite is converted to sodalite, and the resultant CWF is been completed for durations of up to 182 days. Four dissolution modes were identified: dissolution of free salt, dissolution of the aluminosilicate matrix of sodalite and the accompanying dissolution of occluded salt, dissolution of the boroaluminosilicate matrix of the glass, and ion exchange. Synergies inherent to the CWF were identified by comparing the results of the tests with pure glass and sodalite with those of the composite CWF

  15. Thermal forming of glass microsheets for x-ray telescope mirror segments

    DEFF Research Database (Denmark)

    Jimenez-Garate, M.A.; Hailey, C.J.; Craig, W.W.

    2003-01-01

    envisioned for future x-ray observatories. The glass microsheets are shaped into mirror segments at high temperature by use of a guiding mandrel, without polishing. We determine the physical properties and mechanisms that elucidate the formation process and that are crucial to improve surface quality. We......We describe a technology to mass-produce ultrathin mirror substrates for x-ray telescopes of near Wolter-I geometry. Thermal glass forming is a low-cost method to produce high-throughput, spaceborne x-ray mirrors for the 0.1-200-keV energy band. These substrates can provide the collecting area...... develop a viscodynamic model for the glass strain as the forming proceeds to find the conditions for repeatability. Thermal forming preserves the x-ray reflectance and scattering properties of the raw glass. The imaging resolution is driven by a large wavelength figure. We discuss the sources of figure...

  16. Osteoconductive properties of two different bioactive glass forms (powder and fiber) combined with collagen

    Science.gov (United States)

    Magri, Angela Maria Paiva; Fernandes, Kelly Rossetti; Ueno, Fabio Roberto; Kido, Hueliton Wilian; da Silva, Antonio Carlos; Braga, Francisco José Correa; Granito, Renata Neves; Gabbai-Armelin, Paulo Roberto; Rennó, Ana Claudia Muniz

    2017-11-01

    Bioactive Glasses (BG) is a group of synthetic silica-based materials with the unique ability to bond to living bone and can be used in bone repair. Although the osteogenic potential of BG, this material may have not present sufficient osteoconductive and osteoinductive properties to allow bone regeneration, especially in compromised situations. In order to overcome this limitation, it was proposed the combination the BG in two forms (powder and fiber) combined with collagen type I (COL-1). The aim of this study was to evaluate the BG/COL-based materials in terms of morphological characteristics, physicochemical features and mineralization. Additionally, the second objective was to investigate and compare the osteoconductive properties of two different bioactive glass forms (powder and fiber) enriched or not with collagen using a tibial bone defect model in rats. For this, four different formulations (BG powder - BGp, BG powder enriched with collagen - BGp/Col, BG fibers - BGf and BGp fibers enriched with collagen - BGf/Col) were developed. The physicochemical and morphological modifications were analyzed by SEM, FTIR, calcium assay and pH measurement. For in vivo evaluations, histopathology, morphometrical and immunohistochemistry were performed in a tibial defect in rats. The FTIR analysis indicated that BGp and BGf maintained the characteristic peaks for this class of material. Furthermore, the calcium assay showed an increased Ca uptake in the BG fibers. The pH measurements revealed that BGp (with or without collagen) presented higher pH values compared to BGf. In addition, the histological analysis demonstrated no inflammation for all groups at the site of the injury, besides a faster material degradation and higher bone ingrowth for groups with collagen. The immunohistochemistry analysis demonstrated Runx-2 and Rank-L expression for all the groups. Those findings support that BGp with collagen can be a promising alternative for treating fracture of difficult

  17. Revealing the Link between Structural Relaxation and Dynamic Heterogeneity in Glass-Forming Liquids.

    Science.gov (United States)

    Wang, Lijin; Xu, Ning; Wang, W H; Guan, Pengfei

    2018-03-23

    Despite the use of glasses for thousands of years, the nature of the glass transition is still mysterious. On approaching the glass transition, the growth of dynamic heterogeneity has long been thought to play a key role in explaining the abrupt slowdown of structural relaxation. However, it still remains elusive whether there is an underlying link between structural relaxation and dynamic heterogeneity. Here, we unravel the link by introducing a characteristic time scale hiding behind an identical dynamic heterogeneity for various model glass-forming liquids. We find that the time scale corresponds to the kinetic fragility of liquids. Moreover, it leads to scaling collapse of both the structural relaxation time and dynamic heterogeneity for all liquids studied, together with a characteristic temperature associated with the same dynamic heterogeneity. Our findings imply that studying the glass transition from the viewpoint of dynamic heterogeneity is more informative than expected.

  18. Revealing the Link between Structural Relaxation and Dynamic Heterogeneity in Glass-Forming Liquids

    Science.gov (United States)

    Wang, Lijin; Xu, Ning; Wang, W. H.; Guan, Pengfei

    2018-03-01

    Despite the use of glasses for thousands of years, the nature of the glass transition is still mysterious. On approaching the glass transition, the growth of dynamic heterogeneity has long been thought to play a key role in explaining the abrupt slowdown of structural relaxation. However, it still remains elusive whether there is an underlying link between structural relaxation and dynamic heterogeneity. Here, we unravel the link by introducing a characteristic time scale hiding behind an identical dynamic heterogeneity for various model glass-forming liquids. We find that the time scale corresponds to the kinetic fragility of liquids. Moreover, it leads to scaling collapse of both the structural relaxation time and dynamic heterogeneity for all liquids studied, together with a characteristic temperature associated with the same dynamic heterogeneity. Our findings imply that studying the glass transition from the viewpoint of dynamic heterogeneity is more informative than expected.

  19. Dynamical heterogeneity in a glass-forming ideal gas.

    Science.gov (United States)

    Charbonneau, Patrick; Das, Chinmay; Frenkel, Daan

    2008-07-01

    We conduct a numerical study of the dynamical behavior of a system of three-dimensional "crosses," particles that consist of three mutually perpendicular line segments of length sigma rigidly joined at their midpoints. In an earlier study [W. van Ketel, Phys. Rev. Lett. 94, 135703 (2005)] we showed that this model has the structural properties of an ideal gas, yet the dynamical properties of a strong glass former. In the present paper we report an extensive study of the dynamical heterogeneities that appear in this system in the regime where glassy behavior sets in. On the one hand, we find that the propensity of a particle to diffuse is determined by the structure of its local environment. The local density around mobile particles is significantly less than the average density, but there is little clustering of mobile particles, and the clusters observed tend to be small. On the other hand, dynamical susceptibility results indicate that a large dynamical length scale develops even at moderate densities. This suggests that propensity and other mobility measures are an incomplete measure of the dynamical length scales in this system.

  20. Transport properties of glass-forming liquids suggest that dynamic crossover temperature is as important as the glass transition temperature.

    Science.gov (United States)

    Mallamace, Francesco; Branca, Caterina; Corsaro, Carmelo; Leone, Nancy; Spooren, Jeroen; Chen, Sow-Hsin; Stanley, H Eugene

    2010-12-28

    It is becoming common practice to partition glass-forming liquids into two classes based on the dependence of the shear viscosity η on temperature T. In an Arrhenius plot, ln η vs 1/T, a strong liquid shows linear behavior whereas a fragile liquid exhibits an upward curvature [super-Arrhenius (SA) behavior], a situation customarily described by using the Vogel-Fulcher-Tammann law. Here we analyze existing data of the transport coefficients of 84 glass-forming liquids. We show the data are consistent, on decreasing temperature, with the onset of a well-defined dynamical crossover η(×), where η(×) has the same value, η(×) ≈ 10(3) Poise, for all 84 liquids. The crossover temperature, T(×), located well above the calorimetric glass transition temperature T(g), marks significant variations in the system thermodynamics, evidenced by the change of the SA-like T dependence above T(×) to Arrhenius behavior below T(×). We also show that below T(×) the familiar Stokes-Einstein relation D/T ∼ η(-1) breaks down and is replaced by a fractional form D/T ∼ η(-ζ), with ζ ≈ 0.85.

  1. Linking Equilibrium and Nonequilibrium Dynamics in Glass-Forming Systems

    DEFF Research Database (Denmark)

    Mauro, John C.; Guo, Xiaoju; Smedskjær, Morten Mattrup

    , we show that the nonequilibrium glassy dynamics are intimately connected with the equilibrium liquid dynamics. This is accomplished by deriving a new functional form for the thermal history dependence of nonequilibrium viscosity, which is validated against experimental measurements of industrial...

  2. Effect of different glass and zeolite A compositions on the leach resistance of ceramic waste forms

    International Nuclear Information System (INIS)

    Lewis, M.A.; Hash, M.; Glandorf, D.

    1996-01-01

    A ceramic waste form is being developed for waste generated during electrometallurgical treatment of spent nuclear fuel. The waste is generated when fission products are removed from the electrolyte, LiCl-KCl eutectic. The waste form is a composite fabricated by hot isostatic pressing a mixture of glass frit and zeolite occluded with fission products and salt. Normalized release rate is less than 1 g/m 2 d for all elements in MCC-1 leach test run for 28 days in deionized water at 90 C. This leach resistance is comparable to that of early Savannah River glasses. We are investigating how leach resistance is affected by changes in cationic form of zeolite and in glass composition. Composites were made with 3 forms of zeolite A and 6 glasses. We used 3-day ASTM C1220-92 (formerly MCC-1) leach tests to screen samples for development purposes only. The leach test results show that the glass composites of zeolites 5A and 4A retain fission products equally well. Loss of Cs is small (0.1-0.5 wt%), while the loss of divalent and trivalent fission products is one or more orders of magnitude smaller. Composites of 5A retain chloride ion better in these short-term screens than 4A and 3A. The more leach resistant composites were made with durable glasses rich in silica and poor in alkaline earth oxides. XRD show that a salt phase was absent in the leach resistant composites of 5A and the better glasses but was present in the other composites with poorer leach performance. Thus, absence of salt phase corresponds to improved leach resistance. Interactions between zeolite and glass depend on composition of both

  3. Determination of the Structure of Vitrified Hydroceramic/CBC Waste Form Glasses Manufactured from DOE Reprocessing Waste

    International Nuclear Information System (INIS)

    Scheetz, B.E.; White, W. B.; Chesleigh, M.; Portanova, A.; Olanrewaju, J.

    2005-01-01

    The selection of a glass-making option for the solidification of nuclear waste has dominated DOE waste form programs since the early 1980's. Both West Valley and Savannah River are routinely manufacturing glass logs from the high level waste inventory in tank sludges. However, for some wastes, direct conversion to glass is clearly not the optimum strategy for immobilization. INEEL, for example, has approximately 4400 m 3 of calcined high level waste with an activity that produces approximately 45 watts/m 3 , a rather low concentration of radioactive constituents. For these wastes, there is value in seeking alternatives to glass. An alternative approach has been developed and the efficacy of the process demonstrated that offers a significant savings in both human health and safety exposures and also a lower cost relative to the vitrification option. The alternative approach utilizes the intrinsic chemical reactivity of the highly alkaline waste with the addition of aluminosilicate admixtures in the appropriate proportions to form zeolites. The process is one in which a chemically bonded ceramic is produced. The driving force for reaction is derived from the chemical system itself at very modest temperatures and yet forms predominantly crystalline phases. Because the chemically bonded ceramic requires an aqueous medium to serve as a vehicle for the chemical reaction, the proposed zeolite-containing waste form can more adequately be described as a hydroceramic. The hydrated crystalline materials are then subject to hot isostatic pressing (HIP) which partially melts the material to form a glass ceramic. The scientific advantages of the hydroceramic/CBC approach are: (1) Low temperature processing; (2) High waste loading and thus only modest volumetric bulking from the addition of admixtures; (3) Ability to immobilize sodium; (4) Ability to handle low levels of nitrate (2-3% NO 3 - ); (5) The flexibility of a vitrifiable waste; and (6) A process that is based on an

  4. Characterization and durability testing of a glass-bonded ceramic waste form

    International Nuclear Information System (INIS)

    Johnson, S. G.

    1998-01-01

    Argonne National Laboratory is developing a glass bonded ceramic waste form for encapsulating the fission products and transuranics from the conditioning of metallic reactor fuel. This waste form is currently being scaled to the multi-kilogram size for encapsulation of actual high level waste. This paper will present characterization and durability testing of the ceramic waste form. An emphasis on results from application of glass durability tests such as the Product Consistency Test and characterization methods such as X-ray diffraction and scanning electron microscopy. The information presented is based on a suite of tests utilized for assessing product quality during scale-up and parametric testing

  5. Structural origin of fractional Stokes-Einstein relation in glass-forming liquids.

    Science.gov (United States)

    Pan, Shaopeng; Wu, Z W; Wang, W H; Li, M Z; Xu, Limei

    2017-01-06

    In many glass-forming liquids, fractional Stokes-Einstein relation (SER) is observed above the glass transition temperature. However, the origin of such phenomenon remains elusive. Using molecular dynamics simulations, we investigate the break- down of SER and the onset of fractional SER in a model of metallic glass-forming liquid. We find that SER breaks down when the size of the largest cluster consisting of trapped atoms starts to increase sharply at which the largest cluster spans half of the simulations box along one direction, and the fractional SER starts to follows when the largest cluster percolates the entire system and forms 3-dimentional network structures. Further analysis based on the percolation theory also confirms that percolation occurs at the onset of the fractional SER. Our results directly link the breakdown of the SER with structure inhomogeneity and onset of the fraction SER with percolation of largest clusters, thus provide a possible picture for the break- down of SER and onset of fractional SER in glass-forming liquids, which is is important for the understanding of the dynamic properties in glass-forming liquids.

  6. Polyphase ceramic and glass-ceramic forms for immobilizing ICPP high-level nuclear waste

    International Nuclear Information System (INIS)

    Harker, A.B.; Flintoff, J.F.

    1984-01-01

    Polyphase ceramic and glass-ceramic forms have been consolidated from simulated Idaho Chemical Processing Plant wastes by hot isostatic pressing calcined waste and chemical additives by 1000 0 C or less. The ceramic forms can contain over 70 wt% waste with densities ranging from 3.5 to 3.85 g/cm 3 , depending upon the formulation. Major phases are CaF 2 , CaZrTi 207 , CaTiO 3 , monoclinic ZrO 2 , and amorphous intergranular material. The relative fraction of the phases is a function of the chemical additives (TiO 2 , CaO, and SiO 2 ) and consolidation temperature. Zirconolite, the major actinide host, makes the ceramic forms extremely leach resistant for the actinide simulant U 238 . The amorphous phase controls the leach performance for Sr and Cs which is improved by the addition of SiO 2 . Glass-ceramic forms were also consolidated by HIP at waste loadings of 30 to 70 wt% with densities of 2.73 to 3.1 g/cm 3 using Exxon 127 borosilicate glass frit. The glass-ceramic forms contain crystalline CaF 2 , Al 203 , and ZrSi 04 (zircon) in a glass matrix. Natural mineral zircon is a stable host for 4+ valent actinides. 17 references, 3 figures, 5 tables

  7. Effect of irradiation on the evolution of alteration layer formed during nuclear glass leaching

    International Nuclear Information System (INIS)

    Mougnaud, Sarah

    2016-01-01

    High-level radioactive waste (HLW) remaining after spent nuclear fuel reprocessing is immobilized within a glass matrix, eventually destined for geological disposal. Water intrusion into the repository is expected after several thousand years. The alteration of a non-radioactive surrogate for nuclear glass has been extensively studied and it has been determined that successive leaching mechanisms lead to the formation of a 'passivating' alteration layer and to the establishment of a residual rate regime in the long term. However, glass packages are submitted to the radioactivity of confined radioelements. This work focuses on the influence of irradiation on the alteration layer formed during the residual rate regime, in a structural and mechanistic point of view. Three focal areas have been selected. Non-radioactive simple glasses have been leached and externally irradiated in order to determine modifications induced by electronic effects (irradiations with electrons and alpha particles). The same type of glass samples have been previously irradiated with heavy ions and their leaching behavior have been studied in order to assess the impact of ballistic dose cumulated by the glass before water intrusion. Leaching behavior of a complex radioactive glass, doped with an alpha-emitter, has been studied to consider a more realistic situation. (author) [fr

  8. Career Adapt-Abilities Scale--Netherlands Form: Psychometric Properties and Relationships to Ability, Personality, and Regulatory Focus

    Science.gov (United States)

    van Vianen, Annelies E. M.; Klehe, Ute-Christine; Koen, Jessie; Dries, Nicky

    2012-01-01

    The Career Adapt-Abilities Scale (CAAS)--Netherlands Form consists of four scales, each with six items, which measure concern, control, curiosity, and confidence as psychosocial resources for managing occupational transitions, developmental tasks, and work traumas. Internal consistency estimates for the subscale and total scores ranged from…

  9. Reversible and Irreversible Behavior of Glass-forming Materials from the Standpoint of Hierarchical Dynamical Facilitation

    Science.gov (United States)

    Keys, Aaron

    2013-03-01

    Using molecular simulation and coarse-grained lattice models, we study the dynamics of glass-forming liquids above and below the glass transition temperature. In the supercooled regime, we study the structure, statistics, and dynamics of excitations responsible for structural relaxation for several atomistic models of glass-formers. Excitations (or soft spots) are detected in terms of persistent particle displacements. At supercooled conditions, we find that excitations are associated with correlated particle motions that are sparse and localized, and the statistics and dynamics of these excitations are facilitated and hierarchical. Excitations at one point in space facilitate the birth and death of excitations at neighboring locations, and space-time excitation structures are microcosms of heterogeneous dynamics at larger scales. Excitation-energy scales grow logarithmically with the characteristic size of the excitation, giving structural-relaxation times that can be predicted quantitatively from dynamics at short time scales. We demonstrate that these same physical principles govern the dynamics of glass-forming systems driven out-of-equilibrium by time-dependent protocols. For a system cooled and re-heated through the glass transition, non-equilibrium response functions, such as heat capacities, are notably asymmetric in time, and the response to melting a glass depends markedly on the cooling protocol by which the glass was formed. We introduce a quantitative description of this behavior based on the East model, with parameters determined from reversible transport data, that agrees well with irreversible differential scanning calorimetry. We find that the observed hysteresis and asymmetric response is a signature of an underlying dynamical transition between equilibrium melts with no trivial spatial correlations and non-equilibrium glasses with correlation lengths that are both large and dependent upon the rate at which the glass is prepared. The correlation

  10. Study of the confined solutions properties: case of gel formed during nuclear glass alteration

    International Nuclear Information System (INIS)

    Matar-Briman, I.

    2012-01-01

    In this study, we have investigated the thermodynamic properties, the structure and the dynamics of confined solutions in model gels and in a gel coming from glass alteration. The first step was to determine the structure and the dynamics of pure confined water in porous materials by using nuclear magnetic resonance and neutron scattering. Meso-porous silica was elaborated and grafted by sol-gel route to decrease the pore sizes from 2.7 to 2 nm and to modify pore surfaces to have Si-OH, Zr-OH and Al-OH. The second step involved determining the dynamics of water in leachate confined in the model gels and in the gel of altered glass by using neutron scattering. In the model gels and at a 10 -12 -10 -9 second timescale, two kinds of waters were highlighted: first, an interfacial water linked to the pore surfaces and second, a free water in the pore core. Their ratio depends on the pore size and pore surface composition. Whatever the pore surface, when the pore size decreases the free water ratio in the pore center also decreases. For pores smaller than 2.3 nm and pore surfaces with Zr-OH or Al-OH surfaces, water is strongly linked to the surface and few water molecules are mobile. This is due to the ability of alumina and zirconia to immobilize water molecules through chemical coordination bonds stronger than the physical bonds established between silica and water. The result also highlight that pore surface composition could be the predominant parameter affecting the fixed proton content. Moreover, the mobility of water confined in a leachate is not modified. The study of the water dynamics in a gel formed during alteration of glass constituted of SiO 2 , Al 2 O 3 and CaO, and having a porosity between 2 and 7 nm showed the same behavior as water confined in pores presenting an Al-OH surface. (author) [fr

  11. Comprehension and modelling of chromia-forming alloys corrosion mechanisms in nuclear glasses

    International Nuclear Information System (INIS)

    Schmucker, Eric

    2016-01-01

    Nuclear wastes management consists in the confinement of the radioactive wastes in a glass matrix. This is made by inductive melting in a hot crucible at an operating temperature around 1150 C. These crucibles are constituted of nickel based superalloys with high chromium content. They are submitted to a harsh corrosion by the molten glass, eventually leading to their replacement. The protection of the crucible against corrosion is best provided by the establishment of a protective chromium oxide layer at the surface of the alloy. A binary chromia-forming alloy (Ni-30Cr) is studied in this work. Three different binary and ternary glass compositions are chosen in order to understand the influence of the glass basicity and glass viscosity on the corrosion kinetics. Besides, the de-correlation of the formation and dissolution kinetics of the oxide layer allows the modelling of the overall oxide growth in the molten glass. For that purpose, the oxide formation kinetics in molten glass media is assimilated to the oxidation kinetics of the alloy in gaseous media with oxygen partial pressure that are representative of the redox properties of the glasses. Studies of the oxidation kinetics and of the diffusion mechanisms have shown that the oxidation kinetics is independent on the oxygen pressure in the range of 10"-"1"3 up to 10"-"3 atm O_2 at 1150 C. The present work has shown that the dissolution kinetics of the oxide layer is governed by the diffusion of Cr(III) in the glass melt. This dissolution kinetics has been evaluated from the diffusion coefficient and the solubility limit of Cr(III) in the glass. Finally, the overall growth kinetics of the Cr_2O_3 layer in the glass has been successfully modelled for each glass, thanks to the knowledge of (i) the solubility limit of Cr(III), (ii) its diffusion coefficient in the glasses and (iii) the oxidation kinetics of the alloy. The presented model also allows quantifying the influence of each of these parameters on the

  12. Economic comparison of crystalline ceramic and glass waste forms for HLW disposal

    International Nuclear Information System (INIS)

    McKee, R.W.; Daling, P.M.; Wiles, L.E.

    1983-05-01

    A titanate-based, crystalline ceramic produced by hot isostatic pressing has been proposed as a potentially more stable and improved waste form for high-level nuclear waste disposal compared to the currently favored borosilicate glass waste form. This paper describes the results of a study to evaluate the relative costs for disposal of high-level waste from a 70,000 metric ton equivalent (MTE) system. The entire waste management system, including waste processing and encapsulation, transportation, and final repository disposal, was included in this analysis. The repository concept is based on the current basalt waste isolation project (BWIP) reference design. A range of design basis alternatives is considered to determine if this would influence the relative economics of the two waste forms. A thermal analysis procedure was utilized to define optimum canister sizes to assure that each waste form was compared under favorable conditions. Repository costs are found to favor the borosilicate glass waste form while transportation costs greatly favor the crystalline ceramic waste form. The determining component in the cost comparison is the waste processing cost, which strongly favors the borosilicate glass process because of its relative simplicity. A net cost advantage on the order of 12% to 15% on a waste management system basis is indicated for the glass waste form

  13. Glass-Ceramic Waste Forms for Uranium and Plutonium Residues Wastes - 13164

    International Nuclear Information System (INIS)

    Stewart, Martin W.A.; Moricca, Sam A.; Zhang, Yingjie; Day, R. Arthur; Begg, Bruce D.; Scales, Charlie R.; Maddrell, Ewan R.; Hobbs, Jeff

    2013-01-01

    A program of work has been undertaken to treat plutonium-residues wastes at Sellafield. These have arisen from past fuel development work and are highly variable in both physical and chemical composition. The principal radiological elements present are U and Pu, with small amounts of Th. The waste packages contain Pu in amounts that are too low to be economically recycled as fuel and too high to be disposed of as lower level Pu contaminated material. NNL and ANSTO have developed full-ceramic and glass-ceramic waste forms in which hot-isostatic pressing is used as the consolidation step to safely immobilize the waste into a form suitable for long-term disposition. We discuss development work on the glass-ceramic developed for impure waste streams, in particular the effect of variations in the waste feed chemistry glass-ceramic. The waste chemistry was categorized into actinides, impurity cations, glass formers and anions. Variations of the relative amounts of these on the properties and chemistry of the waste form were investigated and the waste form was found to be largely unaffected by these changes. This work mainly discusses the initial trials with Th and U. Later trials with larger variations and work with Pu-doped samples further confirmed the flexibility of the glass-ceramic. (authors)

  14. Radiation effects in glass waste forms for high-level waste and plutonium disposal

    International Nuclear Information System (INIS)

    Weber, W.J.; Ewing, R.C.

    1997-01-01

    A key challenge in the permanent disposal of high-level waste (HLW), plutonium residues/scraps, and excess weapons plutonium in glass waste forms is the development of predictive models of long-term performance that are based on a sound scientific understanding of relevant phenomena. Radiation effects from β-decay and α-decay can impact the performance of glasses for HLW and Pu disposition through the interactions of the α-particles, β-particles, recoil nuclei, and γ-rays with the atoms in the glass. Recently, a scientific panel convened under the auspices of the DOE Council on Materials Science to assess the current state of understanding, identify important scientific issues, and recommend directions for research in the area of radiation effects in glasses for HLW and Pu disposition. The overall finding of the panel was that there is a critical lack of systematic understanding on radiation effects in glasses at the atomic, microscopic, and macroscopic levels. The current state of understanding on radiation effects in glass waste forms and critical scientific issues are presented

  15. Biofilm-Forming Abilities of Listeria monocytogenes Serotypes Isolated from Different Sources

    Science.gov (United States)

    Doijad, Swapnil P.; Barbuddhe, Sukhadeo B.; Garg, Sandeep; Poharkar, Krupali V.; Kalorey, Dewanand R.; Kurkure, Nitin V.; Rawool, Deepak B.; Chakraborty, Trinad

    2015-01-01

    A total of 98 previously characterized and serotyped L. monocytogenes strains, comprising 32 of 1/2a; 20 of 1/2b and 46 of 4b serotype, from clinical and food sources were studied for their capability to form a biofilm. The microtiter plate assay revealed 62 (63.26%) strains as weak, 27 (27.55%) strains as moderate, and 9 (9.18%) strains as strong biofilm formers. Among the strong biofilm formers, 6 strains were of serotype 1/2a and 3 strains were of serotype 1/2b. None of the strain from 4b serotype exhibited strong biofilm formation. No firm correlation (p = 0.015) was noticed between any serotype and respective biofilm formation ability. Electron microscopic studies showed that strong biofilm forming isolates could synthesize a biofilm within 24 h on surfaces important in food industries such as stainless steel, ceramic tiles, high-density polyethylene plastics, polyvinyl chloride pipes, and glass. Cell enumeration of strong, moderate, and weak biofilm was performed to determine if the number of cells correlated with the biofilm-forming capabilities of the isolates. Strong, moderate, and weak biofilm showed 570±127× 103 cells/cm2, 33±26× 103 cells/cm2, 5±3× 103 cells/cm2, respectively, indicating that the number of cells was directly proportional to the strength of the biofilm. The hydrophobicity index (HI) analysis revealed higher hydrophobicity with an increased biofilm formation. Fatty acid methyl esterase analysis revealed the amount of certain fatty acids such as iso-C15:0, anteiso-C15:0, and anteiso-C17:0 fatty acids correlated with the biofilm-forming capability of L. monocytogenes. This study showed that different strains of L. monocytogenes form biofilm of different intensities which did not completely correlate with their serotype; however, it correlated with the number of cells, hydrophobicity, and amount of certain fatty acids. PMID:26360831

  16. Biofilm-Forming Abilities of Listeria monocytogenes Serotypes Isolated from Different Sources.

    Directory of Open Access Journals (Sweden)

    Swapnil P Doijad

    Full Text Available A total of 98 previously characterized and serotyped L. monocytogenes strains, comprising 32 of 1/2a; 20 of 1/2b and 46 of 4b serotype, from clinical and food sources were studied for their capability to form a biofilm. The microtiter plate assay revealed 62 (63.26% strains as weak, 27 (27.55% strains as moderate, and 9 (9.18% strains as strong biofilm formers. Among the strong biofilm formers, 6 strains were of serotype 1/2a and 3 strains were of serotype 1/2b. None of the strain from 4b serotype exhibited strong biofilm formation. No firm correlation (p = 0.015 was noticed between any serotype and respective biofilm formation ability. Electron microscopic studies showed that strong biofilm forming isolates could synthesize a biofilm within 24 h on surfaces important in food industries such as stainless steel, ceramic tiles, high-density polyethylene plastics, polyvinyl chloride pipes, and glass. Cell enumeration of strong, moderate, and weak biofilm was performed to determine if the number of cells correlated with the biofilm-forming capabilities of the isolates. Strong, moderate, and weak biofilm showed 570±127× 103 cells/cm2, 33±26× 103 cells/cm2, 5±3× 103 cells/cm2, respectively, indicating that the number of cells was directly proportional to the strength of the biofilm. The hydrophobicity index (HI analysis revealed higher hydrophobicity with an increased biofilm formation. Fatty acid methyl esterase analysis revealed the amount of certain fatty acids such as iso-C15:0, anteiso-C15:0, and anteiso-C17:0 fatty acids correlated with the biofilm-forming capability of L. monocytogenes. This study showed that different strains of L. monocytogenes form biofilm of different intensities which did not completely correlate with their serotype; however, it correlated with the number of cells, hydrophobicity, and amount of certain fatty acids.

  17. Infrared spectroscopy study of structural changes in glass-forming salol.

    Science.gov (United States)

    Baran, J; Davydova, N A

    2010-03-01

    We report the investigation of glass-forming salol upon different courses of the temperature changes from liquid to glass state and back using FT-IR spectroscopy measurements in the wide spectral and temperature ranges. The formation of the ordered clusters in supercooled liquid salol has been observed at 250 K. When the temperature is decreased further to 11 K these ordered clusters become an element of the glass structure. With increasing temperature to 270 K through the glass transition noticeable evolutions of the IR spectrum occurs up till the ordered clusters are developed into crystal. So produced crystal melts in the temperature range 300-310 K, that corresponds to the melting temperature of the metastable phase (Tmelt=302 K) . Thus, the crystalline structure of the ordered clusters corresponds to the structure of metastable phase and is monoclinic.

  18. Studies of glass waste form performance at Japan Atomic Energy Research Institute

    International Nuclear Information System (INIS)

    Banba, Tsunetaka; Kamizono, Hiroshi; Nakayama, Shinichi; Tashiro, Shingo

    1989-08-01

    The recent studies of glass waste form performance at Japan Atomic Energy Research Institute can be classified into the following three categories; (1) Study on the volatilization of radionuclides from the waste glass, which is necessary to estimate the safety in relation to operation of a storage facility. (2) Study on the radiation (alpha-radiation) effects which have relation to the long-term stability of the waste glass. (3) Study on the leaching behavior of actinides under the repository conditions, which is necessary to predict the long-term release rate of radionuclides from the waste glass. In the present report, the recent results corresponding to the above categories are described. (author)

  19. The Production of Advanced Glass Ceramic HLW Forms using Cold Crucible Induction Melter

    Energy Technology Data Exchange (ETDEWEB)

    Veronica J Rutledge; Vince Maio

    2013-10-01

    Cold Crucible Induction Melters (CCIMs) will favorably change how High-Level radioactive Waste (from nuclear fuel recovery) is treated in the 21st century. Unlike the existing Joule-Heated Melters (JHMs) currently in operation for the glass-based immobilization of High-Level Waste (HLW), CCIMs offer unique material features that will increase melt temperatures, increase throughput, increase mixing, increase loading in the waste form, lower melter foot prints, eliminate melter corrosion and lower costs. These features not only enhance the technology for producing HLW forms, but also provide advantageous attributes to the waste form by allowing more durable alternatives to glass. This paper discusses advantageous features of the CCIM, with emphasis on features that overcome the historical issues with the JHMs presently utilized, as well as the benefits of glass ceramic waste forms over borosilicate glass waste forms. These advantages are then validated based on recent INL testing to demonstrate a first-of-a-kind formulation of a non-radioactive ceramic-based waste form utilizing a CCIM.

  20. Measurements of the Poisson ratio and fragility of glass-forming liquids

    DEFF Research Database (Denmark)

    Christensen, Tage Emil; Olsen, Niels Boye

    Recently much attention has been given to models and phenomenology of glass-forming liquids that correlates fast and slow degrees of freedom . In particular the Poisson ratio has been correlated with fragility. We present data on shear - and bulk modulus obtained by the techniques...... of the piezoelectric transducers PBG and PSG on a number of glass-forming liquids. Hereby the Poisson ratio can be found. Furthermore the PSG also gives the temperature dependence of shear viscosity and thereby the fragility. The validity of the conjectured relation is discussed...

  1. Extracting energy and structure properties of glass-forming liquids from structural relaxation time.

    Science.gov (United States)

    Wang, Lianwen

    2012-04-18

    A comprehensive examination of the kinetic liquid model (Wang et al 2010 J. Phys.: Condens. Matter 22 455104) is carried out by fitting the structural relaxation time of 26 different glass-forming liquids in a wide temperature range, including most of the well-studied materials. Careful analysis of the compiled reported data reveals that experimental inaccuracies should not be overlooked in any 'benchmark test' of relating theories or models (e.g. in Lunkenheimer et al 2010 Phys. Rev. E 81 051504). The procedure, accuracy, ability, and efficiency of the kinetic liquid model are discussed in detail and in comparison with other available fitting methods. In general, the kinetic liquid model could be verified by 17 of the 26 compiled data sets and can serve as a meaningful approximative method for analyzing these liquids. Nonetheless, further experimental examinations in a wide temperature range are needed and are called for. Through fitting, the microscopic details of these liquids are extracted, namely, the enthalpy, entropy, and cooperativity in structural relaxation, which may facilitate further quantitative analysis to both the liquidus and glassy states of these materials.

  2. Glass composite waste forms for iodine confined in bismuth-embedded SBA-15

    Science.gov (United States)

    Yang, Jae Hwan; Park, Hwan Seo; Ahn, Do-Hee; Yim, Man-Sung

    2016-11-01

    The aim of this study was to stabilize bismuth-embedded SBA-15 that captured iodine gas by fabrication of monolithic waste forms. The iodine containing waste was mixed with Bi2O3 (a stabilizing additive) and low-temperature sintering glass followed by pelletizing and the sintering process to produce glass composite materials. Iodine volatility during the sintering process was significantly affected by the ratio of Bi2O3 and the glass composition. It was confirmed that BiI3, the main iodine phase within bismuth-embedded SBA-15, was effectively transformed to the mixed phases of Bi5O7I and BiOI. The initial leaching rates of iodine from the glass composite waste forms ranged 10-3-10-2 g/m2 day, showing the stability of the iodine phases encapsulated by the glassy networks. It was also observed that common groundwater anions (e.g., chloride, carbonate, sulfite, and fluoride) elevated the iodine leaching rate by anion exchange reactions. The present results suggest that the glass composite waste form of bismuth-embedded SBA-15 could be a candidate material for stable storage of 129I.

  3. Bulk metallic glasses: A new class of engineering materials

    Indian Academy of Sciences (India)

    M. Senthilkumar (Newgen Imaging) 1461 1996 Oct 15 13:05:22

    been discovered. Glass-forming ability depends on various factors like enthalpy ... The determination of a glass transition temperature in ... Rao (1980) has postulated that an alloy with the smallest possible molar volume is most prone to glass ...

  4. Crystallization study of Te–Bi–Se glasses

    Indian Academy of Sciences (India)

    Unknown

    Thermal stability; chalcogenide glasses; glass forming ability; glass transition temperature. 1. Introduction ... as well as their wide technological applications including threshold and ... are other important aspects such as ON-state current,.

  5. Anomalous Crystallization as a Signature of the Fragile-to-Strong Transition in Metallic Glass-Forming Liquids

    DEFF Research Database (Denmark)

    Yang, X.N.; Zhou, C.; Sun, Q.J.

    2014-01-01

    We study the fragile-to-strong (F−S) transition of metallic glass-forming liquids (MGFLs) by measuring the thermal response during annealing and dynamic heating of La55Al25Ni5Cu15 glass ribbons fabricated at different cooling rates. We find that the glasses fabricated in the intermediate regime o...

  6. Solvent dynamics in a glass-forming liquid from 300 K to 3 K : What photon echoes can teach us

    NARCIS (Netherlands)

    Lazonder, Kees; Pshenichnikov, Maxim S.

    2007-01-01

    The temperature dependence of the optical non-linear response of dye molecules dissolved in a glass-forming liquid over a temperature range that includes the glass transition is investigated. Cooling down to temperatures below the glass transition dramatically slows the diffusive motion of the

  7. Acid Neutralizing Ability and Shear Bond Strength Using Orthodontic Adhesives Containing Three Different Types of Bioactive Glass

    Directory of Open Access Journals (Sweden)

    Song-Yi Yang

    2016-02-01

    Full Text Available The objective of the study was to compare the acid neutralizing ability and shear bond strength (SBS of three different types of orthodontic adhesives containing bioactive glasses (BAGs. 45S5, 45S5F and S53P4 BAGs were prepared using the melting technique and ground to fine particles. Orthodontic adhesives containing three types of BAGs were prepared as follows: 52.5% 45S5 BAG + 17.5% glass (45S5_A; 61.25% 45S5 BAG + 8.75% glass (45S5_B; 52.5% 45S5F BAG + 17.5% glass (45S5F_A; 61.25% 45S5F BAG + 8.75% glass (45S5F_B; 52.5% S53P4 BAG + 17.5% glass (S53P4_A; 61.25% S53P4 BAG + 8.75% glass (S53P4_B; and 70.0% glass (BAG_0. To evaluate the acid neutralizing properties, specimens were immersed in lactic acid solution, and pH changes were measured. SBS was measured with a universal testing machine. For all of the BAG-containing adhesives, the one with 61.25% of BAG showed a significantly greater increase of pH than the one with 52.5% of BAG (p < 0.05. Groups with 61.25% of BAG showed lower SBS than samples with 52.5% of BAG. 45S5F_A showed no significant difference of SBS compared to BAG_0 (p > 0.05. The adhesive containing 61.25% of 45S5F BAG exhibited clinically acceptable SBS and acid neutralizing properties. Therefore, this composition is a suitable candidate to prevent white spot lesions during orthodontic treatment.

  8. Secondary phases formed during nuclear waste glass-water interactions: Thermodynamic and derived properties

    International Nuclear Information System (INIS)

    McKenzie, W.F.

    1992-08-01

    The thermodynamic properties of secondary phases observed to form during nuclear waste glass-water interactions are of particular interest as it is with the application of these properties together with the thermodynamic properties of other solid phases, fluid phases, and aqueous species that one may predict the environmental consequences of introducing radionuclides contained in the glass into groundwater at a high-level nuclear waste repository. The validation of these predicted consequences can be obtained from laboratory experiments and field observations at natural analogue sites. The purpose of this report is to update and expand the previous compilation (McKenzie, 1991) of thermodynamic data retrieved from the literature and/or estimated for secondary phases observed to form (and candidate phases from observed chemical compositions) during nuclear waste glass-water interactions. In addition, this report includes provisionally recommended thermodynamic data of secondary phases

  9. Linking structure to fragility in bulk metallic glass-forming liquids

    International Nuclear Information System (INIS)

    Wei, Shuai; Stolpe, Moritz; Gross, Oliver; Gallino, Isabella; Hembree, William; Busch, Ralf; Evenson, Zach; Bednarcik, Jozef; Kruzic, Jamie J.

    2015-01-01

    Using in-situ synchrotron X-ray scattering, we show that the structural evolution of various bulk metallic glass-forming liquids can be quantitatively connected to their viscosity behavior in the supercooled liquid near T g . The structural signature of fragility is identified as the temperature dependence of local dilatation on distinct key atomic length scales. A more fragile behavior results from a more pronounced thermally induced dilatation of the structure on a length scale of about 3 to 4 atomic diameters, coupled with shallower temperature dependence of structural changes in the nearest neighbor environment. These findings shed light on the structural origin of viscous slowdown during undercooling of bulk metallic glass-forming liquids and demonstrate the promise of predicting the properties of bulk metallic glasses from the atomic scale structure

  10. Linking structure to fragility in bulk metallic glass-forming liquids

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Shuai, E-mail: shuai.wei@asu.edu, E-mail: m.stolpe@mx.uni-saarland.de [Department of Materials Science and Engineering, Saarland University, Campus C63, 66123 Saarbrücken (Germany); Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287 (United States); Stolpe, Moritz, E-mail: shuai.wei@asu.edu, E-mail: m.stolpe@mx.uni-saarland.de; Gross, Oliver; Gallino, Isabella; Hembree, William; Busch, Ralf [Department of Materials Science and Engineering, Saarland University, Campus C63, 66123 Saarbrücken (Germany); Evenson, Zach [Department of Materials Science and Engineering, Saarland University, Campus C63, 66123 Saarbrücken (Germany); Institut für Materialphysik im Weltraum, Deutsches Zentrum für Luft- und Raumfahrt (DLR), 51170 Köln (Germany); Bednarcik, Jozef [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22603 Hamburg (Germany); Kruzic, Jamie J. [Material Science, School of Mechanical, Industrial, and Manufacturing Engineering, Oregon State University, Corvallis, Oregon 97331 (United States)

    2015-05-04

    Using in-situ synchrotron X-ray scattering, we show that the structural evolution of various bulk metallic glass-forming liquids can be quantitatively connected to their viscosity behavior in the supercooled liquid near T{sub g}. The structural signature of fragility is identified as the temperature dependence of local dilatation on distinct key atomic length scales. A more fragile behavior results from a more pronounced thermally induced dilatation of the structure on a length scale of about 3 to 4 atomic diameters, coupled with shallower temperature dependence of structural changes in the nearest neighbor environment. These findings shed light on the structural origin of viscous slowdown during undercooling of bulk metallic glass-forming liquids and demonstrate the promise of predicting the properties of bulk metallic glasses from the atomic scale structure.

  11. Cold crucible induction melter studies for making glass ceramic waste forms: A feasibility assessment

    International Nuclear Information System (INIS)

    Crum, Jarrod; Maio, Vince; McCloy, John; Scott, Clark; Riley, Brian; Benefiel, Brad; Vienna, John; Archibald, Kip; Rodriguez, Carmen; Rutledge, Veronica; Zhu, Zihua; Ryan, Joe; Olszta, Matthew

    2014-01-01

    Glass ceramics are being developed to immobilize fission products, separated from used nuclear fuel by aqueous reprocessing, into a stable waste form suitable for disposal in a geological repository. This work documents the glass ceramic formulation at bench scale and for a scaled melter test performed in a pilot-scale (∼1/4 scale) cold crucible induction melter (CCIM). Melt viscosity, electrical conductivity, and crystallization behavior upon cooling were measured on a small set of compositions to select a formulation for melter testing. Property measurements also identified a temperature range for melter operation and cooling profiles necessary to crystallize the targeted phases in the waste form. Bench scale and melter run results successfully demonstrate the processability of the glass ceramic using the CCIM melter technology

  12. Mineralogy and thermodynamic properties of magnesium phyllosilicates formed during the alteration of a simplified nuclear glass

    Energy Technology Data Exchange (ETDEWEB)

    Debure, Mathieu, E-mail: m.debure@brgm.fr [CEA, DEN, DTCD, SECM, F-30207 Bagnols-sur-Ceze (France); MINES-ParisTech, PSL Research University, Centre de Géosciences, 77305 Fontainebleau (France); De Windt, Laurent [MINES-ParisTech, PSL Research University, Centre de Géosciences, 77305 Fontainebleau (France); Frugier, Pierre; Gin, Stéphane [CEA, DEN, DTCD, SECM, F-30207 Bagnols-sur-Ceze (France); Vieillard, Philippe [IC2MP-CNRS-UMR 7285, 5 Ave. Albert Turpain TSA 51106, 86073 Poitiers Cedex 09 (France)

    2016-07-15

    The precipitation of crystallized magnesium phyllosilicates generally sustains the alteration rate of nuclear waste containment glass. However, glass alteration slows down to a residual rate as soon as Mg disappears from the solution. The identification of the phyllosilicates formed is therefore crucial for modeling the long-term behavior of nuclear glass. This study deals with batch alteration of the simplified nuclear glass ISG in presence of magnesium, and the characterization of the secondary phases. Morphological, chemical and structural analyses (MET, EDX, XRD) were performed to determine the nature and structure of the precipitated phases identified as trioctahedral smectites. Analyses conducted on the secondary phases proved the presence of Al, Na and Ca in the Mg-phyllosilicate phases. Such elements had been suspected but never quantitatively measured. The experimental results were then used to determine the thermodynamic solubility constants for each precipitated secondary phase at various temperatures. The calculated values were consistent with those available for sodium and magnesium saponites in the existing thermodynamic databases. - Highlights: • The international simple glass dissolution rate increases in presence of magnesium. • Mg added in solution combines with Si from glass to yield trioctahedral smectites. • Their calculated logK are close to smectite thermodynamic constants reported in databases. • It confirms assumptions on Mg-silicates phases made in previous geochemical modeling.

  13. Development and testing of a glass waste form for the immobilization of plutonium

    International Nuclear Information System (INIS)

    Chamberlain, D.B.; Hanchar, J.M.; Emery, J.W.; Hoh, J.C.; Wolf, S.F.; Finch, R.J.; Bates, J.K.; Ellison, A.J.G.; Dingwell, D.B.

    1996-01-01

    The United States has declared about 50 metric tons of weapons-grade Pu surplus to national security needs. The President has directed that this Pu be placed in a form that provides a high degree of proliferation resistance in which the surplus Pu is both unattractive and inaccessible for use by others [I]. Three alternatives are being evaluated for the disposal 2048 of this material: (1) use of the Pu as a fuel source for commercial reactors; (2) immobilization, where Pu is fixed in a glass or ceramic matrix that also contains or is surrounded by highly radioactive material; and (3) deep bore hole, where Pu is emplaced at depths of several kilometers. The immobilization alternative is being directed by the staff at Lawrence Livermore National Laboratory (LLNL). The staff at ANL are assisting by developing a glass for the immobilization of Pu and in the corrosion testing of glass and ceramic material prepared both at ANL and at other DOE laboratories. As part of this program, we have developed an ATS glass into which 5-7 wt percent Pu has been dissolved. The ATS glass was engineered to accommodate high Pu loading and to be durable under conditions likely to accelerate glass reactions in the geological environment during long-term storage

  14. Fluctuations in an Inorganic Glass Forming System Capable of Liquid-Liquid Phase Separation

    Science.gov (United States)

    Bogdanov, V.; Maksimov, L.; Anan'ev, A.; Nemilov, S.; Rusan, V.

    2012-08-01

    Rayleigh and Mandel'shtam-Brillouin scattering (RMBS) spectroscopy and high temperature ultrasonic study (HTUS) are applied to PbO-Al2O3-B2O3 glass forming system characterized by over liquidus miscibility gap. Temperature dependences of ultrasonic velocity of glass melts were measured in 600-1200°C range. "Frozen-in" density fluctuations in two phase glasses were estimated from HTUS data by Macedo-Shroeder formulation. Landau-Placzek ratios were found from RMBS spectra of single phase glasses at room temperature. Results of RMBS and HTUS were compared with well-known SAXS data. It was found that contribution of "frozen-in" density fluctuations into light scattering by two-phase glasses is much smaller than the scattering on particles of the second glassy phase causing opalescence of the glasses. Abnormal "water-like" growth of ultrasonic velocity with melt temperature can be explained by coexistence of two types of packaging of structural elements.

  15. Relating structural parameters to leachability in a glass-bonded ceramic waste form

    International Nuclear Information System (INIS)

    Frank, S. M.; Johnson, S. G.; Moschetti, T. L.

    1998-01-01

    Lattice parameters for a crystalline material can be obtained by several methods, notably by analyzing x-ray powder diffraction patterns. By utilizing a computer program to fit a pattern, one can follow the evolution or subtle changes in a structure of a crystalline species in different environments. This work involves such a study for an essential component of the ceramic waste form that is under development at Argonne National Laboratory. Zeolite 4A and zeolite 5A are used to produce two different types of waste forms: a glass-bonded sodalite and a glass-bonded zeolite, respectively. Changes in structure during production of the waste forms are discussed. Specific salt-loadings in the sodalite waste form are related to relative peak intensities of certain reflections in the XRD patterns. Structural parameters for the final waste forms will also be given and related to leachability under standard conditions

  16. Fast and slow crystal growth kinetics in glass-forming melts

    Energy Technology Data Exchange (ETDEWEB)

    Orava, J.; Greer, A. L., E-mail: alg13@cam.ac.uk [WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan and Department of Materials Science and Metallurgy, 27 Charles Babbage Road, University of Cambridge, Cambridge CB3 0FS (United Kingdom)

    2014-06-07

    Published values of crystal growth rates are compared for supercooled glass-forming liquids undergoing congruent freezing at a planar crystal-liquid interface. For the purposes of comparison pure metals are considered to be glass-forming systems, using data from molecular-dynamics simulations. For each system, the growth rate has a maximum value U{sub max} at a temperature T{sub max} that lies between the glass-transition temperature T{sub g} and the melting temperature T{sub m}. A classification is suggested, based on the lability (specifically, the propensity for fast crystallization), of the liquid. High-lability systems show “fast” growth characterized by a high U{sub max}, a low T{sub max} / T{sub m}, and a very broad peak in U vs. T / T{sub m}. In contrast, systems showing “slow” growth have a low U{sub max}, a high T{sub max} / T{sub m}, and a sharp peak in U vs. T / T{sub m}. Despite the difference of more than 11 orders of magnitude in U{sub max} seen in pure metals and in silica, the range of glass-forming systems surveyed fit into a common pattern in which the lability increases with lower reduced glass-transition temperature (T{sub g} / T{sub m}) and higher fragility of the liquid. A single parameter, a linear combination of T{sub g} / T{sub m} and fragility, can show a good correlation with U{sub max}. For all the systems, growth at U{sub max} is coupled to the atomic/molecular mobility in the liquid. It is found that, across the diversity of glass-forming systems, T{sub max} / T{sub g} = 1.48 ± 0.15.

  17. An alternative host matrix based on iron phosphate glasses for the vitrification of specialized nuclear waste forms. Annual progress report, September 15, 1996 - September 14, 1997

    International Nuclear Information System (INIS)

    Day, D.E.; Marasinghe, K.; Ray, C.S.

    1997-01-01

    'Objectives of this project are to: (1) investigate the glass composition and processing conditions that yield optimum properties for iron phosphate glasses for vitrifying radioactive waste, (2) determine the atomic structure of iron phosphate glasses and the structure-property relationships, (3) determine how the physical and structural properties of iron phosphate glasses are affected by the addition of simulated high level nuclear waste components, and (4) investigate the process and products of devitrification of iron phosphate waste forms. The glass forming ability of about 125 iron phosphate melts has been investigated in different oxidizing to reducing atmospheres using various iron oxide raw materials such as Fe 2 O 3 , FeO, Fe 3 O 4 , and FeC 2 O 4 2H 2 O. The chemical durability, redox equilibria between Fe(II) and Fe(III), crystallization behavior and structural features for these glasses and their crystalline forms have been investigated using a variety of techniques including Mossbauer spectroscopy, X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), Extended x-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) analysis, differential thermal and thermogravimetric analysis (DTA/TGA), and X-ray and neutron diffraction.'

  18. Glass composite waste forms for iodine confined in bismuth-embedded SBA-15

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jae Hwan [Nuclear Fuel Cycle Process Development Division, Korea Atomic Energy Research Institute, 989-111 Daeduk-daero, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of); Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701 (Korea, Republic of); Park, Hwan Seo; Ahn, Do-Hee [Nuclear Fuel Cycle Process Development Division, Korea Atomic Energy Research Institute, 989-111 Daeduk-daero, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of); Yim, Man-Sung, E-mail: msyim@kaist.ac.kr [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, 305-701 (Korea, Republic of)

    2016-11-15

    The aim of this study was to stabilize bismuth-embedded SBA-15 that captured iodine gas by fabrication of monolithic waste forms. The iodine containing waste was mixed with Bi{sub 2}O{sub 3} (a stabilizing additive) and low-temperature sintering glass followed by pelletizing and the sintering process to produce glass composite materials. Iodine volatility during the sintering process was significantly affected by the ratio of Bi{sub 2}O{sub 3} and the glass composition. It was confirmed that BiI{sub 3}, the main iodine phase within bismuth-embedded SBA-15, was effectively transformed to the mixed phases of Bi{sub 5}O{sub 7}I and BiOI. The initial leaching rates of iodine from the glass composite waste forms ranged 10{sup −3}–10{sup −2} g/m{sup 2} day, showing the stability of the iodine phases encapsulated by the glassy networks. It was also observed that common groundwater anions (e.g., chloride, carbonate, sulfite, and fluoride) elevated the iodine leaching rate by anion exchange reactions. The present results suggest that the glass composite waste form of bismuth-embedded SBA-15 could be a candidate material for stable storage of {sup 129}I. - Highlights: • Glass composite waste forms were developed to stabilize iodine confined in Bi-embedded SBA-15. • BiI{sub 3} within Bi-embedded SBA-15 was transformed to BiOI and Bi{sub 5}O{sub 7}I during sintering process. • Iodine volatility was significantly affected by glass composition and Bi{sub 2}O{sub 3} additive. • Iodine leaching rates were 10{sup −3}–10{sup −2} g/m{sup 2} day due to the stable iodine phases encapsulated by glassy networks. • Glass composite waste form of Bi-embedded SBA-15 is expected to be a candidate material for stable storage of {sup 129}I.

  19. Phenomenological description of internal friction spectra in glass-forming and glassy systems

    International Nuclear Information System (INIS)

    Lomovskij, V.A.

    1999-01-01

    Dissipative events in different by chemical nature glass-forming systems, including B 2 O 3 , are studied. It is established from the spectra of internal friction of these systems that the maxima of the energy dissipation of the external power impact are positioned both in the area of viscous flow metastable structural liquid state and in the area of solid elastic state

  20. Exploring the Origin of Fragile-to-Strong Transition in Some Glass-Forming Liquids

    DEFF Research Database (Denmark)

    Yue, Yuanzheng; Hu, L. N.

    2014-01-01

    , topological and thermodynamic changes causing this transition. The theory for describing the transition has not been fully established. In this paper, we summarize our current understanding of the fragile-to-strong transition in some glass-forming liquids basedon our two published papers and recent...

  1. Plan for glass waste form testing for NNWSI [Nevada Nuclear Waste Storage Investigations

    International Nuclear Information System (INIS)

    Aines, R.D.

    1987-09-01

    The purpose of glass waste form testing is to determine the rate of release of radionuclides from breached glass waste containers. This information will be used to qualify glass waste forms with respect to the release requirements. It will be the basis of the source term from glass waste for repository performance assessment modeling. This information will also serve as part of the source term in the calculation of cumulative releases after 100,000 years in the site evaluation process. It will also serve as part of the source term input for calculation of cumulative releases to the accessible environment for 10,000 years after disposal, to determine compliance with EPA regulations. This investigation will provide data to resolve information needs. Information about the waste forms which is provided by the producer will be accumulated and evaluated; the waste form will be tested, properties determined, and mechanisms of degradation determined; and models providing long-term evaluation of release rates designed and tested. 23 refs

  2. Local dynamics and deformation of glass-forming polymers : modelling and atomistic simulations

    NARCIS (Netherlands)

    Vorselaars, B.

    2008-01-01

    The research described in the present thesis is about glassy phenomena and mechanical properties in vitrifiable polymer materials. Glasses are solid materials, but, in contrast to crystals, the structure is disordered. Polymers are macromolecular chains formed by covalently linking a very large

  3. Local elastic expansion model for viscous-flow activation energies of glass-forming molecular liquids

    DEFF Research Database (Denmark)

    Dyre, Jeppe; Olsen, Niels Boye; Christensen, Tage Emil

    1996-01-01

    A model for the viscosity of glass-forming molecular liquids is proposed in which a "flow event" requires a local volume increase. The activation energy for a flow event is identified with the work done in shoving aside the surrounding liquid; this work is proportional to the high-frequency shear...

  4. Study of the glass forming ability of Cu{sub 60}Zr{sub 32,5}Ti{sub 7,5} alloy by molecular dynamics; Formacao de fase amorfa na liga Cu{sub 60}Zr{sub 32,5}Ti{sub 7,5} por dinamica molecular

    Energy Technology Data Exchange (ETDEWEB)

    Schimidt, C.S.; Lima, L.V.; Bastos, I.N.; Aliaga, L.C.R., E-mail: camilaschimidt17@gmail.com [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Departamento de Materiais

    2016-07-01

    This article presents the results of molecular dynamics simulation of Cu{sub 60}Zr{sub 32.5}Ti{sub 7.5} alloy through the open source code LAMMPS. Amorphous samples were produced by quenching the metallic molten from 2300K to 200K at cooling rates of 50, 5 and 0.5K/ps. The pair distribution functions of both the liquid and solid were calculated and compared at different temperatures. The topology of short-range order was analyzed using the Voronoi tessellation method, which determined the presence of Cu-centered icosahedral clusters as the prevailing in the amorphous state at 300K. Moreover, the sample was submitted to uniaxial tensile tests at strain rate of 10ps{sup -1}, in order to investigate the mechanical behavior of the metallic glass. The result of the stress-strain curve showed that applied loads lead to the plastic regime. However, the presences of shear bands, typical in the experimental testing, were not observed. Moreover, the evolution of the viscosity above the glass transition temperature and the fragility of the alloy were determined. The solidus and liquidus temperatures were determined and a good agreement with experimental data was found. (author)

  5. Correlation between short-range order, optical properties and UV-absorption ability in tellurate glasses; Poster M7

    Energy Technology Data Exchange (ETDEWEB)

    Burger, H; Tews, W; Vogel, W; Kozhukharov, V [Jena Univ. (Germany)

    1989-01-01

    Tellurate glasses, with as second components Al[sub 2]O[sub 3], PbO, PbF[sub 2], PbCl[sub 2], PbBr[sub 2], PbSO[sub 4], ZnO, B[sub 2]O[sub 3], P[sub 2]O[sub 5], Li[sub 2]O, Na[sub 2]O, K[sub 2]O, MgO and BaO as well as some glasses from ternary TeO[sub 2]-P[sub 2]O[sub 5]-RO systems (R is Pb, Ba and Zn ions), have been investigated. Transmittance spectra in UV and VIS region of some selected glasses have been measured. A correlation between optical properties and UV absorption edge of the transmittance have been done. Using p[sup 31]-NMR spectroscopy the structural changes on short-range level order are studied. A strong influence on the refraction and dispersion values as well as UV-absorption ability of the glasses is established. For p[sup 31] -NMR spectroscopy investigations of crystalline phosphotellurites and related phosphotellurite glasses the TeO[sub 2]-P[sub 2]O[sub 5B]aO ternary system have been chosen. (author).

  6. Disposal costs for SRP high-level wastes in borosilicate glass and crystalline ceramic waste forms

    International Nuclear Information System (INIS)

    Rozsa, R.B.; Campbell, J.H.

    1982-01-01

    Purpose of this document is to compare and contrast the overall burial costs of the glass and ceramic waste forms, including processing, storage, transportation, packaging, and emplacement in a repository. Amount of waste will require approximately 10,300 standard (24 in. i.d. x 9-5/6 ft length) canisters of waste glass, each containing about 3260 lb of waste at 28% waste loading. The ceramic waste form requires about one-third the above number of standard canisters. Approximately $2.5 billion is required to process and dispose of this waste, and the total cost is independent of waste form (glass or ceramic). The major cost items (about 80% of the total cost) for all cases are capital and operating expenses. The capital and 20-year operating costs for the processing facility are the same order of magnitude, and their sum ranges from about one-half of the total for the reference glass case to two-thirds of the total for the ceramic cases

  7. Applying a new criterion to predict glass forming alloys in the Zr–Ni–Cu ternary system

    Energy Technology Data Exchange (ETDEWEB)

    Déo, L.P., E-mail: leonardopratavieira@gmail.com [Universidade de São Paulo, EESC, SMM - Av. Trabalhador São Carlense, 400 – São Carlos, SP 13566-590 (Brazil); Mendes, M.A.B., E-mail: marcio.andreato@gmail.com [Universidade Federal de São Carlos, DEMa - Rod. Washington Luiz, Km 235 – São Carlos, SP 13565-905 (Brazil); Costa, A.M.S., E-mail: alexmatos1980@gmail.com [Universidade de São Paulo, DEMAR, EEL – Polo Urbo-Industrial Gleba AI-6, s/n – Lorena, SP 12600-970 (Brazil); Campos Neto, N.D., E-mail: nelsonddcn@gmail.com [Universidade de São Paulo, EESC, SMM - Av. Trabalhador São Carlense, 400 – São Carlos, SP 13566-590 (Brazil); Oliveira, M.F. de, E-mail: falcao@sc.usp.br [Universidade de São Paulo, EESC, SMM - Av. Trabalhador São Carlense, 400 – São Carlos, SP 13566-590 (Brazil)

    2013-03-15

    Highlights: ► Calculation to predict and select the glass forming ability (GFA) of metallic alloys in Zr–Ni–Cu system. ► Good correlation between theoretical and experimental GFA samples. ► Combination of X-ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques mainly to characterize the samples. ► Oxygen impurity dramatically reduced the GFA. ► The selection criterion used opens the possibility to obtain new amorphous alloys, reducing the experimental procedures of trial and error. -- Abstract: A new criterion has been recently proposed to predict and select the glass forming ability (GFA) of metallic alloys. It was found that the critical cooling rate for glass formation (R{sub c}) correlates well with a proper combination of two factors, the minimum topological instability (λ{sub min}) and the thermodynamic parameter (Δh). The (λ{sub min}) criterion is based on the concept of topological instability of stable crystalline structures and (Δh) depends on the average work function difference (Δϕ) and the average electron density difference Δn{sub ws}{sup 1/3} among the constituent elements of the alloy. In the present work, the selection criterion was applied in the Zr–Ni–Cu system and its predictability was analyzed experimentally. Ribbon-shaped and splat-shaped samples were produced by melt-spinning and splat-cooling techniques respectively. The crystallization content and behavior were analyzed by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. The results showed a good correlation between the theoretical GFA values and the amorphous phase percentages found in different alloy compositions.

  8. Liquidus Temperature of SrO-Al2O3-SiO2 Glass-Forming Compositions

    DEFF Research Database (Denmark)

    Abel, Brett M.; Morgan, James M.; Mauro, John C.

    2013-01-01

    . In the composition range of interest for industrial glasses, Tliq tends to decrease with increasing strontium-to-alumina ratio. We find that cristobalite, mullite, and slawsonite are the dominant devitrification phases for the compositions with high SiO2, SiO2+Al2O3, and SrO contents, respectively. By comparison...... with the phase diagrams for CaO-Al2O3-SiO2 and MgO-Al2O3-SiO2 systems, we have found that for the highest [RO]/[Al2O3] ratios, Tliq exhibits a minimum value for R = Ca. Based on the phase diagram established here, the composition of glass materials, for example, for liquid crystal display substrates, belonging...... to the SrO-Al2O3-SiO2 family may be designed with a more exact control of the glass-forming ability by avoiding the regions of high liquidus temperature....

  9. A Glass-Ceramic Waste Forms for the Immobilization of Rare Earth Oxides from the Pyroprocessing Waste salt

    International Nuclear Information System (INIS)

    Ahn, Byung-Gil; Park, Hwan-Seo; Kim, Hwan-Young; Kim, In-Tae

    2008-01-01

    The fission product of rare earth (RE) oxide wastes are generates during the pyroprocess . Borosilicate glass or some ceramic materials such as monazite, apatite or sodium zirconium phosphate (NZP) have been a prospective host matrix through lots of experimental results. Silicate glasses have long been the preferred waste form for the immobilization of HLW. In immobilization of the RE oxides, the developed process on an industrial scale involves their incorporation into a glass matrix, by melting under 1200 ∼ 1300 .deg. C. Instead of the melting process, glass powder sintering is lower temperature (∼ 900 .deg. C) required for the process which implies less demanding conditions for the equipment and a less evaporation of volatile radionuclides. This study reports the behaviors, direct vitrification of RE oxides with glass frit, glass powder sintering of REceramic with glass frit, formation of RE-apatite (or REmonazite) ceramic according to reaction temperature, and the leach resistance of the solidified waste forms

  10. Study on the leach mechanism of 90-19/U glass form in underground water of disposal site

    International Nuclear Information System (INIS)

    Sheng Jiawei; Luo Shanggeng; Tang Baolong

    1996-01-01

    The leach behavior of 90-19/U glass form in underground water (UW) of disposal site and in the deionized water (DIW) is studied. The total mass losses of glass form and the normalized element mass losses of B, Li and Si in UW are presented and compared to DIW. It is found that the ions in UW affect the leach behavior of 90-19/U glass. At the beginning of the reaction the reaction rate of the glass is smaller in UW than in DIW due to the low glass dissolution affinity in UW which is defined as (1-c/K). The rate determining step of leach reaction of 90-19/U glass in UW during the entire reaction period is the ion-exchange reaction. The apparent activation energy of glass reaction in UW is 51.6 kJ/mol

  11. Development and testing of matrices for the encapsulation of glass and ceramic nuclear waste forms

    International Nuclear Information System (INIS)

    Wald, J.W.; Brite, D.W.; Gurwell, W.E.; Buckwalter, C.Q.; Bunnell, L.R.; Gray, W.J.; Blair, H.T.; Rusin, J.M.

    1982-02-01

    This report details the results of research on the matrix encapsulation of high level wastes at PML over the past few years. The demonstrations and tests described were designed to illustrate how the waste materials are effected when encapsulated in an inert matrix. Candidate materials evaluated for potential use as matrices for encapslation of pelletized ceramics or glass marbles were categorized into four groups: metals, glasses, ceramics, and graphite. Two processing techniques, casting and hot pressing, were investigated as the most promising methods of formation or densification of the matrices. The major results reported deal with the development aspects. However, chemical durability tests (leach tests) of the matrix materials themselves and matrix-waste form composites are also reported. Matrix waste forms can provide a low porosity, waste-free barrier resulting in increased leach protection, higher impact strength and improved thermal conductivity compared to unencapsulated glass or ceramic waste materials. Glass marbles encapsulated in a lead matrix offer the most significant improvement in waste form stability of all combinations evaluated. This form represents a readily demonstrable process that provides high thermal conductivity, mechanical shock resistance, radiation shielding and increased chemical durability through both a chemical passivation mechanism and as a physical barrier. Other durable matrix waste forms evaluated, applicable primarily to ceramic pellets, involved hot-pressed titanium or TiO 2 materials. In the processing of these forms, near 100% dense matrices were obtained. The matrix materials had excellent compatibility with the waste materials and superior potential chemical durability. Cracking of the hot-pressed ceramic matrix forms, in general, prevented the realization of their optimum properties

  12. The correlation between fragility, density, and atomic interaction in glass-forming liquids

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lijin; Guan, Pengfei, E-mail: pguan@csrc.ac.cn [Beijing Computational Science Research Center, Beijing 100193 (China); Wang, W. H. [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2016-07-21

    The fragility that controls the temperature-dependent viscous properties of liquids as the glass transition is approached, in various glass-forming liquids with different softness of the repulsive part of atomic interactions at different densities, is investigated by molecular dynamic simulations. We show that the landscape of fragility in purely repulsive systems can be separated into three regions denoted as R{sub I,} R{sub II}, and R{sub III}, respectively, with qualitatively disparate dynamic behaviors: R{sub I} which can be described by “softness makes strong glasses,” R{sub II} where fragility is independent of softness and can only be tuned by density, and R{sub III} with constant fragility, suggesting that density plays an unexpected role for understanding the repulsive softness dependence of fragility. What is more important is that we unify the long-standing inconsistence with respect to the repulsive softness dependence of fragility by observing that a glass former can be tuned more fragile if nonperturbative attraction is added into it. Moreover, we find that the vastly dissimilar influences of attractive interaction on fragility could be estimated from the structural properties of related zero-temperature glasses.

  13. The correlation between fragility, density, and atomic interaction in glass-forming liquids

    International Nuclear Information System (INIS)

    Wang, Lijin; Guan, Pengfei; Wang, W. H.

    2016-01-01

    The fragility that controls the temperature-dependent viscous properties of liquids as the glass transition is approached, in various glass-forming liquids with different softness of the repulsive part of atomic interactions at different densities, is investigated by molecular dynamic simulations. We show that the landscape of fragility in purely repulsive systems can be separated into three regions denoted as R I, R II , and R III , respectively, with qualitatively disparate dynamic behaviors: R I which can be described by “softness makes strong glasses,” R II where fragility is independent of softness and can only be tuned by density, and R III with constant fragility, suggesting that density plays an unexpected role for understanding the repulsive softness dependence of fragility. What is more important is that we unify the long-standing inconsistence with respect to the repulsive softness dependence of fragility by observing that a glass former can be tuned more fragile if nonperturbative attraction is added into it. Moreover, we find that the vastly dissimilar influences of attractive interaction on fragility could be estimated from the structural properties of related zero-temperature glasses.

  14. The correlation between fragility, density, and atomic interaction in glass-forming liquids.

    Science.gov (United States)

    Wang, Lijin; Guan, Pengfei; Wang, W H

    2016-07-21

    The fragility that controls the temperature-dependent viscous properties of liquids as the glass transition is approached, in various glass-forming liquids with different softness of the repulsive part of atomic interactions at different densities, is investigated by molecular dynamic simulations. We show that the landscape of fragility in purely repulsive systems can be separated into three regions denoted as RI, RII, and RIII, respectively, with qualitatively disparate dynamic behaviors: RI which can be described by "softness makes strong glasses," RII where fragility is independent of softness and can only be tuned by density, and RIII with constant fragility, suggesting that density plays an unexpected role for understanding the repulsive softness dependence of fragility. What is more important is that we unify the long-standing inconsistence with respect to the repulsive softness dependence of fragility by observing that a glass former can be tuned more fragile if nonperturbative attraction is added into it. Moreover, we find that the vastly dissimilar influences of attractive interaction on fragility could be estimated from the structural properties of related zero-temperature glasses.

  15. Length scales in glass-forming liquids and related systems: a review

    International Nuclear Information System (INIS)

    Karmakar, Smarajit; Dasgupta, Chandan; Sastry, Srikanth

    2016-01-01

    The central problem in the study of glass-forming liquids and other glassy systems is the understanding of the complex structural relaxation and rapid growth of relaxation times seen on approaching the glass transition. A central conceptual question is whether one can identify one or more growing length scale(s) associated with this behavior. Given the diversity of molecular glass-formers and a vast body of experimental, computational and theoretical work addressing glassy behavior, a number of ideas and observations pertaining to growing length scales have been presented over the past few decades, but there is as yet no consensus view on this question. In this review, we will summarize the salient results and the state of our understanding of length scales associated with dynamical slow down. After a review of slow dynamics and the glass transition, pertinent theories of the glass transition will be summarized and a survey of ideas relating to length scales in glassy systems will be presented. A number of studies have focused on the emergence of preferred packing arrangements and discussed their role in glassy dynamics. More recently, a central object of attention has been the study of spatially correlated, heterogeneous dynamics and the associated length scale, studied in computer simulations and theoretical analysis such as inhomogeneous mode coupling theory. A number of static length scales have been proposed and studied recently, such as the mosaic length scale discussed in the random first-order transition theory and the related point-to-set correlation length. We will discuss these, elaborating on key results, along with a critical appraisal of the state of the art. Finally we will discuss length scales in driven soft matter, granular fluids and amorphous solids, and give a brief description of length scales in aging systems. Possible relations of these length scales with those in glass-forming liquids will be discussed. (review article)

  16. Electron microprobe analysis (WDS EPMA) of Zhamanshin glass reveals the impactor and a common role of accretion in the origin of splash-form impact glass

    International Nuclear Information System (INIS)

    Vetvicka, I; Frank, J; Drtina, J

    2010-01-01

    Impact glass samples collected during expeditions to the Zhamashin and Lonar craters were subjected to a morphology survey and compared to Wabar, Henbury and Darwin impact glasses to reveal that the accretion of fibres and spherules is not exclusive for irghizites but occurs in other splash form glasses over the world. WDS EPMA and LA-ICP-MS assays of Zhamanshin and Lonar glasses enabled the definition of akmurynites as Zhamanshin glass of specific morphology, chemistry and absence of extraterrestrial contamination. However, extraterrestrial contamination in irghizites was verified and further WDS EPMA analyses led to the conclusion that the Zhamanshin crater had been formed by the impact of a primitive achondrite of Lodran chemistry.

  17. 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....

  18. Durability, mechanical, and thermal properties of experimental glass-ceramic forms for immobilizing ICPP high level waste

    International Nuclear Information System (INIS)

    Vinjamuri, K.

    1990-01-01

    The high-level liquid waste generated at the Idaho Chemical Processing Plant (ICPP) is routinely solidified into granular calcined high-level waste (HLW) and stored onsite. Research is being conducted at the ICPP on methods of immobilizing the HLW, including developing a durable glass-ceramic form which has the potential to significantly reduce the final waste volume by up to 60% compared to a glass form. Simulated, pilot plant, non-radioactive, calcines similar to the composition of the calcined HLW and glass forming additives are used to produce experimental glass-ceramic forms. The objective of the research reported in this paper is to study the impact of ground calcine particle size on durability and mechanical and thermal properties of experimental glass-ceramic forms

  19. The role of the dynamic crossover temperature and the arrest in glass-forming fluids.

    Science.gov (United States)

    Mallamace, F; Corsaro, C; Stanley, H E; Chen, S-H

    2011-09-01

    We discuss the role of the dynamic glass-forming fragile-to-strong crossover (FSC) in supercooled liquids. In the FSC, significant dynamic changes such as the decoupling (the violation of the Stokes-Einstein relation) of homologous transport parameters, e.g., the density relaxation time τ and the viscosity η, occur at a characteristic temperature T(c). We study the FSC using a scaling law approach. In particular, we use both forms of the mode-coupling theory (MCT): the original (ideal) and the extended form, which explicitly describes energy hopping processes. We demonstrate that T(c) plays the most important physical role in understanding dynamic arrest processes.

  20. Performance of borosilicate glass, Synroc and spent fuel as nuclear waste forms

    International Nuclear Information System (INIS)

    Lutze, W.; Grambow, B.; Ewing, R.C.

    1990-01-01

    Presently, there are three prominent waste forms under consideration for the disposal of high-level waste: Borosilicate glass and Synroc for high-level radioactive waste from fuel reprocessing and spent fuel as the waste form for non-reprocessed fuel. Using the present experimental data base, one may compare the performance of these three waste forms under repository relevant conditions. In low water flow regimes and at temperatures less than 100 degree C, the fractional release rates of all three waste forms are low, on the order of 10-7/d or less and may decrease with time. Under these conditions the three waste forms behave similarly. At elevated temperatures or in high flow regimes, the durability of borosilicate glass will be much less than that of Synroc, and thus, for certain disposal schemes (e.g., deep burial) Synroc is preferable. All predictions of the long-term behavior are based on the extrapolation of short term experimental data, we point out that appropriate and useful natural analogues are available for each of these waste forms and should be used in the performance assessment of each waste form's long-term behavior. 14 refs

  1. Hydrotalcite formed by alteration of R7T7 nuclear waste glass and basaltic glass in salt brine at 190 degrees C

    International Nuclear Information System (INIS)

    Abdelouas, A.; Crovisier, J.L.; Lutze, W.; Mueller, R.; Bernotat, W.

    1994-01-01

    The R7T7 and synthetic basaltic glasses were submitted to corrosion in a saline MgCl 2 dominated solution at 190 degrees C. For both glasses, the early alteration product is a hydrotalcite-like compound in which HPO 4 2- , SO 4 2- and Cl - substitutes to CO 3 2- . The measured d 003 spacing is 7.68 angstrom for the hydrotalcite formed from R7T7 glass and 7.62 angstrom for the hydrotalcite formed from basaltic glass which reflect the high aluminium content. Chemical microanalyses show that the hydrotalcite is subsequently covered by a silica-rich gel which evolves into saponite after few months

  2. Forming of protective nanostructure coatings on metals and glasses and their properties investigation

    International Nuclear Information System (INIS)

    Deshkovskaya, A.; Lynkov, L.; Nagibarov, A.; Glybin, V.; Richter, E.; Pham, M.

    2013-01-01

    Transparent heat-resistant coatings of 10-30 nm thickness described by (ZrO 2 ) x •(Y 2 O 3 ) y composition are formed on the surface of metals and glasses by thermolysis technique. Produced coatings possess high adhesive strength, high corrosive and abrasive resistance. Nanocrystalline formations are revealed on samples surface, with quantity of these formations depending on basic solution concentration, formed layers number and thermal treatment mode. Ion-beam modification of obtained coatings under mixing mode enables said properties enhancing owing to zirconium oxiboride formation at substrate-coating interface as a result of ion-beam synthesis. (authors)

  3. Fracture toughness measurements on a glass bonded sodalite high-level waste form

    International Nuclear Information System (INIS)

    DiSanto, T.; Goff, K. M.; Johnson, S. G.; O'Holleran, T. P.

    1999-01-01

    The electrometallurgical treatment of metallic spent nuclear fuel produces two high-level waste streams; cladding hulls and chloride salt. Argonne National Laboratory is developing a glass bonded sodalite waste form to immobilize the salt waste stream. The waste form consists of 75 Vol.% crystalline sodalite (containing the salt) with 25 Vol.% of an ''intergranular'' glassy phase. Microindentation fracture toughness measurements were performed on representative samples of this material using a Vickers indenter. Palmqvist cracking was confirmed by post-indentation polishing of a test sample. Young's modulus was measured by an acoustic technique. Fracture toughness, microhardness, and Young's modulus values are reported, along with results from scanning electron microscopy studies

  4. Mini Seminar on Form Filling Ability of Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm

    2005-01-01

    The Nordic mini-seminar “Form Filling Ability of Self-Compacting Concrete” took place on 3-4 November 2003 at the Danish Technological Institute in Taastrup, Denmark. The mini-seminar gathered 12 participants from Finland, Sweden, Norway and Denmark. The objective was to present and discuss recent...... developments of Self-Compacting Concrete in the Nordic countries. In general, the seminar included results and observations on the effect of fresh concrete behaviour, casting technique, and organisation on site on the filling ability, passing ability, and surface quality. The seminar had participants from...

  5. The analysis of glass ceiling phenomenon in the promotion of women’s abilities in organizations

    Directory of Open Access Journals (Sweden)

    Mahboubeh Soleymanpour Omran

    2015-09-01

    Full Text Available Women constitute almost half of the workforce of a society and there has been considerable increase in women employment rate in recent years. However, their promotion to management positions has not been very tangible. Gender inequalities in the workplace especially in the domain of management have resulted in the lack of efficient use of potential capacities of women. Even though the previous research demonstrates that women are not less ambitious than men, wrong beliefs which attribute management to men make a kind of invisible barrier, known as glass ceiling, which prevents women’s promotion to top organizational positions. The purpose of this study was to investigate the reasons for the lack of promotion of women to top management levels in the society. It was conducted with a descriptive analytic method through the review of the related literature and emphasis on the concept of glass ceiling to present practical solutions to solve the problem.

  6. Quantitative model of super-Arrhenian behavior in glass forming materials

    Science.gov (United States)

    Caruthers, J. M.; Medvedev, G. A.

    2018-05-01

    The key feature of glass forming liquids is the super-Arrhenian temperature dependence of the mobility, where the mobility can increase by ten orders of magnitude or more as the temperature is decreased if crystallization does not intervene. A fundamental description of the super-Arrhenian behavior has been developed; specifically, the logarithm of the relaxation time is a linear function of 1 /U¯x , where U¯x is the independently determined excess molar internal energy and B is a material constant. This one-parameter mobility model quantitatively describes data for 21 glass forming materials, which are all the materials where there are sufficient experimental data for analysis. The effect of pressure on the loga mobility is also described using the same U¯x(T ,p ) function determined from the difference between the liquid and crystalline internal energies. It is also shown that B is well correlated with the heat of fusion. The prediction of the B /U¯x model is compared to the Adam and Gibbs 1 /T S¯x model, where the B /U¯x model is significantly better in unifying the full complement of mobility data. The implications of the B /U¯x model for the development of a fundamental description of glass are discussed.

  7. Glass-bonded iodosodalite waste form for immobilization of 129I

    Science.gov (United States)

    Chong, Saehwa; Peterson, Jacob A.; Riley, Brian J.; Tabada, Diana; Wall, Donald; Corkhill, Claire L.; McCloy, John S.

    2018-06-01

    Immobilization of radioiodine is an important requirement for current and future nuclear fuel cycles. Iodosodalite [Na8(AlSiO4)6I2] was synthesized hydrothermally from metakaolin, NaI, and NaOH. Dried unwashed sodalite powders were used to synthesize glass-bonded iodosodalite waste forms (glass composite materials) by heating pressed pellets at 650, 750, or 850 °C with two types of sodium borosilicate glass binders. These heat-treated specimens were characterized with X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, thermal analysis, porosity and density measurements, neutron activation analysis, and inductively-coupled plasma mass spectrometry. For the best waste form produced (pellets mixed with 10 mass% of glass binder and heat-treated at 750 °C), the maximum possible elemental iodine loading was 19.8 mass%, but only ∼8-9 mass% waste loading of iodine was retained in the waste form after thermal processing. Other pellets with higher iodine retention either contained higher porosity or were incompletely sintered. ASTM C1308 and C1285 (product consistency test, PCT) experiments were performed to understand chemical durability under diffusive and static conditions. The C1308 test resulted in significantly higher normalized loss compared to the C1285 test, most likely because of the strong effect of neutral pH solution renewal and prevention of ion saturation in solution. Both experiments indicated that release rates of Na and Si were higher than for Al and I, probably due to a poorly durable Na-Si-O phase from the glass bonding matrix or from initial sodalite synthesis; however the C1308 test result indicated that congruent dissolution of iodosodalite occurred. The average release rates of iodine obtained from C1308 were 0.17 and 1.29 g m-2 d-1 for 80 or 8 m-1, respectively, and the C1285 analysis gave a value of 2 × 10-5 g m-2 d-1, which is comparable to or better than the durability of

  8. Probing heterogeneous dynamics from spatial density correlation in glass-forming liquids.

    Science.gov (United States)

    Li, Yan-Wei; Zhu, You-Liang; Sun, Zhao-Yan

    2016-12-01

    We numerically investigate the connection between spatial density correlation and dynamical heterogeneity in glass-forming liquids. We demonstrate that the cluster size defined by the spatial aggregation of densely packed particles (DPPs) can better capture the difference between the dynamics of the Lennard-Jones glass model and the Weeks-Chandler-Andersen truncation model than the commonly used pair correlation functions. More interestingly, we compare the mobility of DPPs and loosely packed particles, and we find that high local density correlates well with slow dynamics in systems with relatively hard repulsive interactions but links to mobile ones in the system with soft repulsive interactions at one relaxation time scale. Our results show clear evidence that the above model dependence behavior stems from the hopping motion of DPPs at the end of the caging stage due to the compressive nature of soft repulsive spheres, which activates the dynamics of DPPs in the α relaxation stage.

  9. Oriented color centres being formed in anisotropic action of optical radiation on sodium-silicate glass

    International Nuclear Information System (INIS)

    Barinova, N.A.; Glebov, L.B.; Dokuchaev, V.G.; Savel'ev, V.L.

    1992-01-01

    A study was made of anisotropy of absorption of hole colour centres appearing in sodium-silicate glass due to anisotropic action of UV radiation. In case of such action in the field of long-wave edge of their fundamental absorption oriented hole colour centres occurs with maximum of absorption bands to 2.0, 2.8, 4.1 eV. Principal direction of hole colour centres orientation in this case coincides with orientation of ionized glass matrix centres. Orientation of such kind is connected with selective ionization of disorderedly oriented centres forming edge of fundamental absorption. Value of guided dichroism of colour centres absorption is determined by hole migration

  10. Communication: High pressure specific heat spectroscopy reveals simple relaxation behavior of glass forming molecular liquid

    DEFF Research Database (Denmark)

    Roed, Lisa Anita; Niss, Kristine; Jakobsen, Bo

    2015-01-01

    The frequency dependent specific heat has been measured under pressure for the molecular glass forming liquid 5-polyphenyl-4-ether in the viscous regime close to the glass transition. The temperature and pressure dependences of the characteristic time scale associated with the specific heat...... is compared to the equivalent time scale from dielectric spectroscopy performed under identical conditions. It is shown that the ratio between the two time scales is independent of both temperature and pressure. This observation is non-trivial and demonstrates the existence of specially simple molecular...... liquids in which different physical relaxation processes are both as function of temperature and pressure/density governed by the same underlying “inner clock.” Furthermore, the results are discussed in terms of the recent conjecture that van der Waals liquids, like the measuredliquid, comply...

  11. Microscopic Theory of Coupled Slow Activated Dynamics in Glass-Forming Binary Mixtures.

    Science.gov (United States)

    Zhang, Rui; Schweizer, Kenneth S

    2018-04-05

    The Elastically Collective Nonlinear Langevin Equation theory for one-component viscous liquids and suspensions is generalized to treat coupled slow activated relaxation and diffusion in glass-forming binary sphere mixtures of any composition, size ratio, and interparticle interactions. A trajectory-level dynamical coupling parameter concept is introduced to construct two coupled dynamic free energy functions for the smaller penetrant and larger matrix particle. A two-step dynamical picture is proposed where the first-step process involves matrix-facilitated penetrant hopping quantified in a self-consistent manner based on a temporal coincidence condition. After penetrants dynamically equilibrate, the effectively one-component matrix particle dynamics is controlled by a new dynamic free energy (second-step process). Depending on the time scales associated with the first- and second-step processes, as well as the extent of matrix-correlated facilitation, distinct physical scenarios are predicted. The theory is implemented for purely hard-core interactions, and addresses the glass transition based on variable kinetic criteria, penetrant-matrix coupled activated relaxation, self-diffusion of both species, dynamic fragility, and shear elasticity. Testable predictions are made. Motivated by the analytic ultralocal limit idea derived for pure hard sphere fluids, we identify structure-thermodynamics-dynamics relationships. As a case study for molecule-polymer thermal mixtures, the chemically matched fully miscible polystyrene-toluene system is quantitatively studied based on a predictive mapping scheme. The resulting no-adjustable-parameter results for toluene diffusivity and the mixture glass transition temperature are in good agreement with experiment. The theory provides a foundation to treat diverse dynamical problems in glass-forming mixtures, including suspensions of colloids and nanoparticles, polymer-molecule liquids, and polymer nanocomposites.

  12. Comparison of SRP high-level waste disposal costs for borosilicate glass and crystalline ceramic waste forms

    International Nuclear Information System (INIS)

    McDonell, W.R.

    1982-04-01

    An evaluation of costs for the immobilization and repository disposal of SRP high-level wastes indicates that the borosilicate glass waste form is less costly than the crystalline ceramic waste form. The wastes were assumed immobilized as glass with 28% waste loading in 10,300 reference 24-in.-diameter canisters or as crystalline ceramic with 65% waste loading in either 3400 24-in.-diameter canisters or 5900 18-in.-diameter canisters. After an interim period of onsite storage, the canisters would be transported to the federal repository for burial. Total costs in undiscounted 1981 dollars of the waste disposal operations, excluding salt processing for which costs are not yet well defined, were about $2500 million for the borosilicate glass form in reference 24-in.-diameter canisters, compared to about $2900 million for the crystalline ceramic form in 24-in.-diameter canisters and about $3100 million for the crystalline ceramic form in 18-in.-diameter canisters. No large differences in salt processing costs for the borosilicate glass and crystalline ceramic forms are expected. Discounting to present values, because of a projected 2-year delay in startup of the DWPF for the crystalline ceramic form, preserved the overall cost advantage of the borosilicate glass form. The waste immobilization operations for the glass form were much less costly than for the crystalline ceramic form. The waste disposal operations, in contrast, were less costly for the crystalline ceramic form, due to fewer canisters requiring disposal; however, this advantage was not sufficient to offset the higher development and processing costs of the crystalline ceramic form. Changes in proposed Nuclear Regulatory Commission regulations to permit lower cost repository packages for defense high-level wastes would decrease the waste disposal costs of the more numerous borosilicate glass forms relative to the crystalline ceramic forms

  13. Evaluation of final waste forms and recommendations for baseline alternatives to group and glass

    Energy Technology Data Exchange (ETDEWEB)

    Bleier, A.

    1997-09-01

    An assessment of final waste forms was made as part of the Federal Facilities Compliance Agreement/Development, Demonstration, Testing, and Evaluation (FFCA/DDT&E) Program because supplemental waste-form technologies are needed for the hazardous, radioactive, and mixed wastes of concern to the Department of Energy and the problematic wastes on the Oak Ridge Reservation. The principal objective was to identify a primary waste-form candidate as an alternative to grout (cement) and glass. The effort principally comprised a literature search, the goal of which was to establish a knowledge base regarding four areas: (1) the waste-form technologies based on grout and glass, (2) candidate alternatives, (3) the wastes that need to be immobilized, and (4) the technical and regulatory constraints on the waste-from technologies. This report serves, in part, to meet this goal. Six families of materials emerged as relevant; inorganic, organic, vitrified, devitrified, ceramic, and metallic matrices. Multiple members of each family were assessed, emphasizing the materials-oriented factors and accounting for the fact that the two most prevalent types of wastes for the FFCA/DDT&E Program are aqueous liquids and inorganic sludges and solids. Presently, no individual matrix is sufficiently developed to permit its immediate implementation as a baseline alternative. Three thermoplastic materials, sulfur-polymer cement (inorganic), bitumen (organic), and polyethylene (organic), are the most technologically developed candidates. Each warrants further study, emphasizing the engineering and economic factors, but each also has limitations that regulate it to a status of short-term alternative. The crystallinity and flexible processing of sulfur provide sulfur-polymer cement with the highest potential for short-term success via encapsulation. Long-term immobilization demands chemical stabilization, which the thermoplastic matrices do not offer. Among the properties of the remaining

  14. Evaluation of final waste forms and recommendations for baseline alternatives to grout and glass

    International Nuclear Information System (INIS)

    Bleier, A.

    1997-09-01

    An assessment of final waste forms was made as part of the Federal Facilities Compliance Agreement/Development, Demonstration, Testing, and Evaluation (FFCA/DDT ampersand E) Program because supplemental waste-form technologies are needed for the hazardous, radioactive, and mixed wastes of concern to the Department of Energy and the problematic wastes on the Oak Ridge Reservation. The principal objective was to identify a primary waste-form candidate as an alternative to grout (cement) and glass. The effort principally comprised a literature search, the goal of which was to establish a knowledge base regarding four areas: (1) the waste-form technologies based on grout and glass, (2) candidate alternatives, (3) the wastes that need to be immobilized, and (4) the technical and regulatory constraints on the waste-from technologies. This report serves, in part, to meet this goal. Six families of materials emerged as relevant; inorganic, organic, vitrified, devitrified, ceramic, and metallic matrices. Multiple members of each family were assessed, emphasizing the materials-oriented factors and accounting for the fact that the two most prevalent types of wastes for the FFCA/DDT ampersand E Program are aqueous liquids and inorganic sludges and solids. Presently, no individual matrix is sufficiently developed to permit its immediate implementation as a baseline alternative. Three thermoplastic materials, sulfur-polymer cement (inorganic), bitumen (organic), and polyethylene (organic), are the most technologically developed candidates. Each warrants further study, emphasizing the engineering and economic factors, but each also has limitations that regulate it to a status of short-term alternative. The crystallinity and flexible processing of sulfur provide sulfur-polymer cement with the highest potential for short-term success via encapsulation. Long-term immobilization demands chemical stabilization, which the thermoplastic matrices do not offer. Among the properties of the

  15. Resource function of conceptual and metacognitive abilities in adolescents with different forms of dysontogenesis.

    Directory of Open Access Journals (Sweden)

    Kholodnaya, M.

    2015-07-01

    Full Text Available This study investigated the level of conceptual and metacognitive abilities and their interaction in adolescents with different forms of dysontogenesis. The total sample (N= 173 included four groups of young adolescents (11-12 years old: with normal development, with infantile cerebral palsy (CP, with attention deficit hyperactivity disorder (ADHD, and with delayed intellectual development (DID. We measured the adolescents’ performance on tests of conceptual abilities (the use of categories at different grades of generalization, the discovery of abstract meaning and implicit connections between concepts and metacognitive abilities (attention selectivity, as measured by Mtinsterberg’s test and the understanding of hidden pictures, and attention organization, as measured by indices of cognitive styles. The results showed, first, that in comparison with normal adolescents, the adolescents with CP and ADHD had a deficit of metacognitive abilities, but they did not differ in rates of conceptual abilities. As for adolescents with DID, even though they had lower rates of conceptual abilities and attention selectivity, they did not differ from the “norm” group on some indices of attention organization. Second, a tendency for the disintegration of conceptual and metacognitive abilities (as measured by correlation and factor analysis was most clearly seen in the adolescents with ADHD and DID. The adolescents with CP and ADHD had conceptual (categorial and generative abilities as a mental resource, and the adolescents with DID had metacognitive abilities as a mental resource. The resource function of conceptual and metacognitive abilities was determined not only by their level but also by the extent of their interaction (integration.

  16. Career Adapt-Abilities Scale-Belgium Form: psychometric characteristics and construct validity

    NARCIS (Netherlands)

    Dries, N.; van Esbroeck, R.; van Vianen, A.E.M.; de Cooman, R.; Pepermans, R.

    2012-01-01

    The Dutch version of the Career Adapt-Abilities Scale-Belgium Form (CAAS-Belgium) consists of four scales, each with six items, which measure concern, control, curiosity, and confidence as psychosocial resources for managing occupational transitions, developmental tasks, and work traumas. A pilot

  17. Field Dependence/Independence in College Nonmusic Majors and Their Ability to Discern Form in Music.

    Science.gov (United States)

    Ellis, Mark C.; McCoy, Clair W.

    1990-01-01

    Measures the effects of cognitive-style field dependence/field independence on students' ability to discern form in music. Applies tests to 119 nonmusic majors enrolled in an introductory music course. Finds field-independent subjects scored significantly higher than field-dependent subjects. Identifies variables affecting learning for both…

  18. Gene knockdown of CENPA reduces sphere forming ability and stemness of glioblastoma initiating cells

    Directory of Open Access Journals (Sweden)

    Jinan Behnan

    2016-09-01

    Knockdown of CENPA reduced sphere forming ability, proliferation and cell viability of GICs. We also detected significant reduction in the expression of stemness marker SOX2 and the proliferation marker Ki67. These results indicate that CENPA might represent a promising therapeutic target for GBM treatment.

  19. Icosahedral binary clusters of glass-forming Lennard-Jones binary alloy

    International Nuclear Information System (INIS)

    Iwamatsu, Masao

    2007-01-01

    It is widely believed that the local icosahedral structure is related to the formation of bulk metallic glasses (BMGs). Specifically the existence of 13-atom icosahedral cluster in undercooled liquid is imagined to play a key role to initiate the glass formation as the seed of amorphous structure or to block the nucleation of regular crystal as the impurity. The existence of 13-atom icosahedral clusters in one-component liquids was predicted more than half a century ago by Frank from his total energy calculation for isolated clusters. In BMG alloys, however, the situation is less clear. In this report, we present the lowest-energy structures of 13-atom Lennard-Jones binary cluster calculated from the modified space-fixed genetic algorithm. We study, in particular, the artificial Lennard-Jones potential designed by Kob and Andersen [W. Kob, H.C. Andersen, Phys. Rev. E 51 (1995) 4626] that is known to form BMG. Curiously, the lowest-energy structures of 13-atom cluster are non-icosahedral for almost all compositions. Our result suggests that the existence of the icosahedral cluster is not a necessary condition but only a sufficient condition for glass formation

  20. Effects of waste content of glass waste forms on Savannah River high-level waste disposal costs

    International Nuclear Information System (INIS)

    McDonell, W.R.; Jantzen, C.M.

    1985-01-01

    Effects of the waste content of glass waste forms of Savannah River high-level waste disposal costs are evaluated by their impact on the number of waste canisters produced. Changes in waste content affect onsite Defense Waste Processing Facility (DWPF) costs as well as offsite shipping and repository emplacement charges. A nominal 1% increase over the 28 wt % waste loading of DWPF glass would reduce disposal costs by about $50 million for Savannah River wastes generated to the year 2000. Waste form modifications under current study include adjustments of glass frit content to compensate for added salt decontamination residues and increased sludge loadings in the DWPF glass. Projected cost reductions demonstrate significant incentives for continued optimization of the glass waste loadings. 13 refs., 3 figs., 3 tabs

  1. [Apatite-forming ability of pure titanium implant after micro-arc oxidation treatment].

    Science.gov (United States)

    Tian, Zhihui; Zhang, Yu; Wang, Lichao; Nan, Kaihui

    2013-10-01

    To investigate the apatite forming ability of pure titanium implant after micro-arc oxidation treatment in simulated body fluid (SBF) and obtain implants with calcium phosphate (Ca-P) layers. The implants were immersed in (SBF) after micro-arc oxidation treatment for different time lengths, and their apatite forming ability and the morphology and constituents of the Ca-P layers formed on the sample surface were analyzed using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive electron probe. After immersion in SBF, large quantities of Ca-P layers were induced on the surface of the samples. The Ca-P layers were composed of octacalcium phosphate and carbonated hydroxyapatite, and the crystals showed a plate-like morphology with an oriented growth. The implants with micro-arc oxidation treatment show good apatite forming ability on the surface with rich calcium and phosphorus elements. The formed layers are composed of bone-like apatite including octacalcium phosphate and carbonated hydroxyapatite.

  2. Radiation effects in glass and glass-ceramic waste forms for the immobilization of CANDU UO{sub 2} fuel reprocessing waste

    Energy Technology Data Exchange (ETDEWEB)

    Tait, J C

    1993-05-01

    AECL has investigated three waste forms for the immobilization of high-level liquid wastes that would arise if used CANDU fuels were reprocessed at some time in the future to remove fissile materials for the fabrication of new power reactor fuel. These waste forms are borosilicate glasses, aluminosilicate glasses and titanosilicate glass-ceramics. This report discusses the potential effects of alpha, beta and gamma radiation on the releases of radionuclides from these waste forms as a result of aqueous corrosion by groundwaters that would be present in an underground waste disposal vault. The report discusses solid-state damage caused by radiation-induced atomic displacements in the waste forms as well as irradiation of groundwater solutions (radiolysis), and their potential effects on waste-form corrosion and radionuclide release. The current literature on radiation effects on borosilicate glasses and in ceramics is briefly reviewed, as are potential radiation effects on specialized waste forms for the immobilization of {sup 129}I, {sup 85}Kr and {sup 14}C. (author). 104 refs., 9 tabs., 5 figs.

  3. Cerium, uranium, and plutonium behavior in glass-bonded sodalite, a ceramic nuclear waste form

    International Nuclear Information System (INIS)

    Lewis, M. A.; Lexa, D.; Morss, L. R.; Richmann, M. K.

    1999-01-01

    Glass-bonded sodalite is being developed as a ceramic waste form (CWF) to immobilize radioactive fission products, actinides, and salt residues from electrometallurgical treatment of spent nuclear reactor fuel. The CWF consists of about 75 mass % sodalite, 25 mass % glass, and small amounts of other phases. This paper presents some results and interpretation of physical measurements to characterize the CWF structure, and dissolution tests to measure the release of matrix components and radionuclides from the waste form. Tests have been carried out with specimens of the CWF that contain rare earths at concentrations similar to those expected in the waste form. Parallel tests have been carried out on specimens that have uranium or plutonium as well as the rare earths at concentrations similar to those expected in the waste forms; in these specimens UCl 3 forms UO 2 and PuCl 3 forms PuO 2 . The normalized releases of rare earths in dissolution tests were found to be much lower than those of matrix elements (B, Si, Al, Na). When there is no uranium in the CWF, the release of cerium is two to ten times lower than the release of the other rare earths. The low release of cerium may be due to its tetravalent state in uranium-free CWF. However, when there is uranium in the CWF, the release of cerium is similar to that of the other rare earths. This trivalent behavior of cerium is attributed to charge transfer or covalent interactions among cerium, uranium, and oxygen in (U,Ce)O 2

  4. Weather ability studies of phenolic resin coated woods and glass fiber reinforced laminates

    International Nuclear Information System (INIS)

    Munir, A.; Hussain, R.; Rizvi, M.H.; Ahmed, F.

    1997-01-01

    Phenolic resins have made a major breakthrough in the field of high technology in 80's. These are now active participants of h igh tech' areas ranging from electronics, computers, communication, outer space, aerospace, advanced materials, bio materials and technology. A phenol - formaldehyde (1:1.5) resin having resin content of 70% synthesized in the laboratory has been applied for wood coating and reinforcing glass fiber. The weatherability and solvent resistance of these items have been studied and results discussed keeping in view the envisaged application for structural materials and chemical equipment. The toxic materials released during contact with solvents for chemical applications and during degradation general have been monitored. The results are discussed with reference to environmental pollution due to these resins and their composites under different conditions. (authors)

  5. Analysis of the Glass-Forming Ability of Fe-Er Alloys, Based on Thermodynamic Modeling

    Science.gov (United States)

    Arutyunyan, N. A.; Zaitsev, A. I.; Dunaev, S. F.; Kalmykov, K. B.; El'nyakov, D. D.; Shaposhnikov, N. G.

    2018-05-01

    The Fe-Er phase diagram and thermodynamic properties of all its phases are assessed by means of self-consistent analysis. To refine the data on phase equilibria in the Fe-Er system, an investigation is performed in the 10-40 at % range of Er concentrations. The temperature-concentration dependences of the thermodynamic properties of a melt are presented using the model of ideal associated solutions. Thermodynamic parameters of each phase are obtained, and the calculated results are in agreement with available experimental data. The correlation between the thermodynamic properties of liquid Fe-Er alloys and their tendency toward amorphization are studied. It is shown that compositions of amorphous alloys prepared by melt quenching coincide with the ranges of concentration with the predominance of Fe3Er and FeEr2 associative groups that have large negative entropies of formation.

  6. A thermodynamic approach to the quantitative evaluation of the metallic melts glass-forming ability

    International Nuclear Information System (INIS)

    Zajtsev, A.I.

    2004-01-01

    The outlook for development of quantitative criteria of the tendency of metallic melt to render amorphous is shown with taking into account specific features of chemical interaction between components. With the use of statistical physics methods and thermodynamics as well as concepts of association the techniques are devised for quantitative separation of contributions to liquid alloy thermodynamic functions conditioned by various types of chemical interaction between components. The results Knudsen mass-spectroscopic comprehensive thermodynamic study of a wide range of systems with various tendency to vitrification are summarized. It is shown that excessive (configurational) entropy and specific heat of the liquid are key features predetermining thermodynamic and kinetic stimuli of amorphization. Their values are completely determined by a covalent constituent of chemical interaction on entropic term of association reaction. The possibility of construction of quantitative amorphization criteria on the basis of this feature and the outlook for the use of the approach proposed to predict physicochemical and mechanical properties of solid amorphous materials are illustrated [ru

  7. Crossover to potential energy landscape dominated dynamics in a model glass-forming liquid

    DEFF Research Database (Denmark)

    Schrøder, Thomas; Sastry, S.; Dyre, Jeppe

    2000-01-01

    An equilibrated model glass-forming liquid is studied by mapping successive configurations produced by molecular dynamics simulation onto a time series of inherent structures (local minima in the potential energy). Using this "inherent dynamics" approach we find direct numerical evidence for the ......An equilibrated model glass-forming liquid is studied by mapping successive configurations produced by molecular dynamics simulation onto a time series of inherent structures (local minima in the potential energy). Using this "inherent dynamics" approach we find direct numerical evidence...... for the long held view that below a crossover temperature, Tx, the liquid's dynamics can be separated into (i) vibrations around inherent structures and (ii) transitions between inherent structures [M. Goldstein, J. Chem. Phys. 51, 3728 (1969)], i.e., the dynamics become "dominated" by the potential energy...... landscape. In agreement with previous proposals, we find that Tx is within the vicinity of the mode-coupling critical temperature Tc. We further find that near Tx, transitions between inherent structures occur via cooperative, stringlike rearrangements of groups of particles moving distances substantially...

  8. Collective dynamics of glass-forming polymers at intermediate length scales

    International Nuclear Information System (INIS)

    Colmenero, J.; Alvarez, F.; Arbe, A.

    2015-01-01

    Deep understanding of the complex dynamics taking place in glass-forming systems could potentially be gained by exploiting the information provided by the collective response monitored by coherent neutron scattering. We have revisited the question of the characterization of the collective response of polyisobutylene at intermediate length scales observed by neutron spin echo (NSE) experiments. The model, generalized for sub-linear diffusion - as it is the case of glass-forming polymers - has been successfully applied by using the information on the total self-motions available from MD-simulations properly validated by direct comparison with experimental results. From the fits of the coherent NSE data, the collective time at Q → 0 has been extracted that agrees very well with compiled results from different experimental techniques directly accessing such relaxation time. We show that a unique temperature dependence governs both, the Q → 0 and Q → ∞ asymptotic characteristic times. The generalized model also gives account for the modulation of the apparent activation energy of the collective times with the static structure factor. It mainly results from changes of the short-range order at inter-molecular length scales

  9. In-situ ductile metal/bulk metallic glass matrix composites formed by chemical partitioning

    Science.gov (United States)

    Kim, Choong Paul; Hays, Charles C.; Johnson, William L.

    2004-03-23

    A composite metal object comprises ductile crystalline metal particles in an amorphous metal matrix. An alloy is heated above its liquidus temperature. Upon cooling from the high temperature melt, the alloy chemically partitions, forming dendrites in the melt. Upon cooling the remaining liquid below the glass transition temperature it freezes to the amorphous state, producing a two-phase microstructure containing crystalline particles in an amorphous metal matrix. The ductile metal particles have a size in the range of from 0.1 to 15 micrometers and spacing in the range of from 0.1 to 20 micrometers. Preferably, the particle size is in the range of from 0.5 to 8 micrometers and spacing is in the range of from 1 to 10 micrometers. The volume proportion of particles is in the range of from 5 to 50% and preferably 15 to 35%. Differential cooling can produce oriented dendrites of ductile metal phase in an amorphous matrix. Examples are given in the Zr--Ti--Cu--Ni--Be alloy bulk glass forming system with added niobium.

  10. Using 20-million-year-old amber to test the super-Arrhenius behaviour of glass-forming systems

    Science.gov (United States)

    Zhao, Jing; Simon, Sindee L.; McKenna, Gregory B.

    2013-04-01

    Fossil amber offers the opportunity to investigate the dynamics of glass-forming materials far below the nominal glass transition temperature. This is important in the context of classical theory, as well as some new theories that challenge the idea of an ‘ideal’ glass transition. Here we report results from calorimetric and stress relaxation experiments using a 20-million-year-old Dominican amber. By performing the stress relaxation experiments in a step-wise fashion, we measured the relaxation time at each temperature and, above the fictive temperature of this 20-million-year-old glass, this is an upper bound to the equilibrium relaxation time. The results deviate dramatically from the expectation of classical theory and are consistent with some modern ideas, in which the diverging timescale signature of complex fluids disappears below the glass transition temperature.

  11. The differentiated approach in forming swimming abilities and skills of students

    Directory of Open Access Journals (Sweden)

    Nikolskiy A.U.

    2010-09-01

    Full Text Available It is considered the directions of organization and methods of conducting of lessons with students. In experiment took part students of the 17-20 years old. The criteria of forming of typological educational groups are presented on the initial stage of teaching swimming of students. The degree of connection of the hereditarily conditioned swimming coordinating inclination is certain with the indexes of formed swimming abilities and skills of students. It is well-proven that a process of capture motive habits is under unreserved influence of conservative heredity of individual.

  12. Biofilm forming ability of bacteria isolated from necrotic roots canals of teeth

    Science.gov (United States)

    Alwan, Merriam Ghadhanfar; Usup, Gires; Heng, Lee Yook; Ahmad, Asmat

    2018-04-01

    The growth of microbes in biofilms are associated with repeated and chronic human infections and are extremely resistant to antimicrobial agents. The purpose of this study was to determine the diversity of bacteria from necrotic roots canals of teeth and to detect their biofilm formation ability. A total of 42 bacterial isolates were isolated and identified as belonging to 11 genera. These are Enterococcus sp. (21.4%) followed by Streptococcus sp. (16.8%), Bacillus sp. (11.9%), Peptostreptococcus sp. (9.5%), Staphylococcus sp. (9.5%), Bacteroides sp. (7.1%), Clostridium sp. (7.1%), Actinomyces sp. (7.1%), Fusobacterium sp. (4.76%), Provotella sp. (2.4%) and Chromobacterium sp. (2.4%). Three screening methods for biofilm forming ability were used. Congo Red Agar method (CRA), Tube method (TM) and Microtitre Plate (MTP). From the results, MTP method is a more reliable and quantitative method for the screening and detection of microorganism's ability to form biofilm. This method can be recommended and suggested as a general screening method for the detection of biofilm forming bacteria isolated from roots canals of teeth.

  13. Structural relaxation and thermal conductivity of high-pressure formed, high-density di-n-butyl phthalate glass and pressure induced departures from equilibrium state.

    Science.gov (United States)

    Johari, G P; Andersson, Ove

    2017-06-21

    We report a study of structural relaxation of high-density glasses of di-n-butyl phthalate (DBP) by measuring thermal conductivity, κ, under conditions of pressure and temperature (p,T) designed to modify both the vibrational and configurational states of a glass. Various high-density glassy states of DBP were formed by (i) cooling the liquid under a fixed high p and partially depressurizing the glass, (ii) isothermal annealing of the depressurized glass, and (iii) pressurizing the glass formed by cooling the liquid under low p. At a given low p, κ of the glass formed by cooling under high p is higher than that of the glass formed by cooling under low p, and the difference increases as glass formation p is increased. κ of the glass formed under 1 GPa is ∼20% higher at ambient p than κ of the glass formed at ambient p. On heating at low p, κ decreases until the glass to liquid transition range is reached. This is the opposite of the increase in κ observed when a glass formed under a certain p is heated under the same p. At a given high p, κ of the low-density glass formed by cooling at low p is lower than that of the high-density glass formed by cooling at that high p. On heating at high p, κ increases until the glass to liquid transition range is reached. The effects observed are due to a thermally assisted approach toward equilibrium at p different from the glass formation p. In all cases, the density, enthalpy, and entropy would change until the glasses become metastable liquids at a fixed p, thus qualitatively relating κ to variation in these properties.

  14. Thermodynamics of the Gd/sub 63.2/Co/sub 36.8/ glass-forming eutectic

    International Nuclear Information System (INIS)

    Baricco, M.; Antonione, C.; Battezzati, L.

    1987-01-01

    In the last years a tendency has consolidated to investigate the properties of the liquid phase in relation to amorphization. The thermodynamic properties of glass-forming liquids show some remarkable similarities and provide a unifying picture for the understanding of glass formation. In particular the specific heat difference between liquid and crystal phases, C/sub P/, seem always positive thus enabling the liquid entropy to approach that of the solid on under-cooling towards the glass transition temperature, T/sub g/. The enthalpy of mixing in glass-forming alloys is strongly negative and depends on temperature giving rise to an excess specific heat. As the liquid and crystalline pure elements have similar specific heat and the Newmann-Kopp law is usually obeyed by solid alloys, the excess specific heat can be assimilated to G. This last quantity, therefore, determines the trend of the thermodynamic properties in the undercooling regime and ultimately the glass-forming tendency of the liquid systems. Specific heat data are available for some liquid alloys but only a few of them refer to glass-forming systems. Typical examples are Au/sub 77/Ge/sub 13.6/Si/sub 9.4/ among metal-metalloid and Mg/sub 85.5/Cu/sub 14.5/ among metal-metal systems. The authors present here a complete determination of the thermodynamic properties of the Gd/sub 63.2/Co/sub 36.8/ eutectic as an example for anthanide transition metal glass-formers. This alloy is low melting so that its liquid state is accessible by differential scanning calorimetry. It forms glasses readily by means of liquid quenching

  15. Candidate Low-Temperature Glass Waste Forms for Technetium-99 Recovered from Hanford Effluent Management Facility Evaporator Concentrate

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Mei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tang, Ming [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rim, Jung Ho [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chamberlin, Rebecca M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-07-24

    Alternative treatment and disposition options may exist for technetium-99 (99Tc) in secondary liquid waste from the Hanford Direct-Feed Low-Activity Waste (DFLAW) process. One approach includes development of an alternate glass waste form that is suitable for on-site disposition of technetium, including salts and other species recovered by ion exchange or precipitation from the EMF evaporator concentrate. By recovering the Tc content from the stream, and not recycling the treated concentrate, the DFLAW process can potentially be operated in a more efficient manner that lowers the cost to the Department of Energy. This report provides a survey of candidate glass formulations and glass-making processes that can potentially incorporate technetium at temperatures <700 °C to avoid volatilization. Three candidate technetium feed streams are considered: (1) dilute sodium pertechnetate loaded on a non-elutable ion exchange resin; (2) dilute sodium-bearing aqueous eluent from ion exchange recovery of pertechnetate, or (3) technetium(IV) oxide precipitate containing Sn and Cr solids in an aqueous slurry. From the technical literature, promising candidate glasses are identified based on their processing temperatures and chemical durability data. The suitability and technical risk of three low-temperature glass processing routes (vitrification, encapsulation by sintering into a glass composite material, and sol-gel chemical condensation) for the three waste streams was assessed, based on available low-temperature glass data. For a subset of candidate glasses, their long-term thermodynamic behavior with exposure to water and oxygen was modeled using Geochemist’s Workbench, with and without addition of reducing stannous ion. For further evaluation and development, encapsulation of precipitated TcO2/Sn/Cr in a glass composite material based on lead-free sealing glasses is recommended as a high priority. Vitrification of pertechnetate in aqueous anion exchange eluent solution

  16. Glass-bonded iodosodalite waste form for immobilization of 129 I

    Energy Technology Data Exchange (ETDEWEB)

    Chong, Saehwa; Peterson, Jacob A.; Riley, Brian J.; Tabada, Diana; Wall, Donald; Corkhill, Claire L.; McCloy, John S.

    2018-06-01

    Immobilization of radioiodine (e.g., 129I, 131I) is an important need for current and future nuclear fuel cycles. For the current work, iodosodalite [Na8(AlSiO4)6I2] was synthesized hydrothermally from metakaolin, NaI, and NaOH. Following hydrothermal treatment, dried unwashed powders were used to make glass-bonded iodosodalite waste forms by heating pressed pellets at 650, 750, or 850 °C with two different types of sodium borosilicate glass binders, i.e., NBS-4 and SA-800. These heat-treated specimens were characterized with X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, thermal analysis, porosity and density measurements, neutron activation analysis, and inductively-coupled plasma mass spectrometry. The pellets mixed with 10 mass% of NBS-4 or SA-800 and heat-treated at 750 °C contained relatively high percentage iodine retention (~44-47 % of the maximum iodine loading) with relatively low porosities, while other pellets with higher percentages iodine retention either contained higher porosity or were not completely sintered. ASTM C1308 chemical durability tests of monolithic specimens showed a large initial release of Na, Al, Si, and I on the first day, possibly from water-soluble salt crystals or non-durable amorphous phases. Release rates of Na and Si were higher than for Al and I, probably due to a poorly durable Na-Si-O phase from the glass bonding matrix. The cumulative normalized release of iodine was 12.5 g m-2 for the first 10 1-d exchanges, suggestive of coherent dissolution. The average release rate from 10-24 days during the 7-d exchange intervals was 0.2336 g m-2 d-1.

  17. Bioactivity, mechanical properties and drug delivery ability of bioactive glass-ceramic scaffolds coated with a natural-derived polymer.

    Science.gov (United States)

    Araújo, M; Viveiros, R; Philippart, A; Miola, M; Doumett, S; Baldi, G; Perez, J; Boccaccini, A R; Aguiar-Ricardo, A; Verné, E

    2017-08-01

    In this work, hybrid melanin-coated bioactive glass-ceramic multifunctional scaffolds were developed and characterized in terms of mechanical strength, in vitro bioactivity in simulated body fluid (SBF) and ability to load ibuprofen. The coated scaffolds exhibited an accelerated bioactivity in comparison with the uncoated ones, being able of developing hydroxyapatite-like crystals after 7days soaking in simulated body fluid (SBF). Besides its positive influence on the scaffolds bioactivity, the melanin coating was able to enhance their mechanical properties, increasing the initial compressive strength by a factor of >2.5. Furthermore, ibuprofen was successfully loaded on this coating, allowing a controlled drug release of the anti-inflammatory agent. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Combined PIXE and SEM study of the behaviour of trace elements in gel formed around implant coated with bioactive glass

    Science.gov (United States)

    Oudadesse, H.; Irigaray, J. L.; Barbotteau, Y.; Brun, V.; Moretto, Ph.

    2002-05-01

    Bioactive glasses are used as coating biomaterials to facilitate anchorage of metallic prostheses implanted into the body. The aim of this work is to study the behavior of gel formed in contact with alloys and BVA and BVH bioactive glasses implanted. Cylinders of metallic implants composed by Ti, Al and V, are coated with bioactive glass. Three sheep were implanted for different time length: 3, 6 and 12 months in the femoral epiphysis. Results obtained with particle induced X-ray emission and scanning electron microscopy show that BVA coating induces a better contact between the metallic implant and bone. On the other hand, BVH coating prevents corrosion from the metallic implant.

  19. PREFACE: Dynamic crossover phenomena in water and other glass-forming liquids Dynamic crossover phenomena in water and other glass-forming liquids

    Science.gov (United States)

    Chen, Sow-Hsin; Baglioni, Piero

    2012-02-01

    This special section has been inspired by the workshop on Dynamic Crossover Phenomena in Water and Other Glass-Forming Liquids, held during November 11-13, 2010 at Pensione Bencistà, Fiesole, Italy, a well-preserved 14th century Italian villa tucked high in the hills overlooking Florence. The meeting, an assembly of world renowned scientists, was organized as a special occasion to celebrate the 75th birthday of Professor Sow-Hsin Chen of MIT, a pioneer in several aspects of complex fluids and soft matter physics. The workshop covered a large variety of experimental and theoretical research topics of current interest related to dynamic crossover phenomena in water and, more generally, in other glass-forming liquids. The 30 invited speakers/lecturers and approximately 60 participants were a select group of prominent physicists and chemists from the USA, Europe, Asia and Mexico, who are actively working in the field. Some highlights of this special issue include the following works. Professor Yamaguchi's group and their collaborators present a neutron spin echo study of the coherent intermediate scattering function of heavy water confined in cylindrical pores of MCM-41-C10 silica material in the temperature range 190-298 K. They clearly show that a fragile-to-strong (FTS) dynamic crossover occurs at about 225 K. They attribute the FTS dynamic crossover to the formation of a tetrahedral-like structure, which is preserved in the bulk-like water confined to the central part of the cylindrical pores. Mamontov and Kolesnikov et al study the collective excitations in an aqueous solution of lithium chloride over a temperature range of 205-270 K using neutron and x-ray Rayleigh-Brillouin (coherent) scattering. They detect both the low-frequency and the high-frequency sounds known to exist in pure bulk water above the melting temperature. They also perform neutron (incoherent) and x-ray (coherent) elastic intensity scan measurements. Clear evidence of the crossover in the

  20. SEALING ABILITY OF MINERAL TRIOXIDE AGGREGATE, CALCIUM PHOSPHATE CEMENT, AND GLASS IONOMER CEMENT IN THE REPAIR OF FURCATION PERFORATIONS

    Directory of Open Access Journals (Sweden)

    Prabath Singh

    2013-01-01

    Full Text Available Objectives: The purpose of this study was to evaluate the in vitro sealing ability of three repair materials. Mineral trioxide aggregate (MTA; Group A, calcium phosphate cement (CPC; Group B, and light cured glass ionomer cement (GIC; Group C when used to repair the perforation created in the pulpal floor of fifty extracted human permanent molars. Materials and methods: Preparation of access openings and furcation perforations were done, and the teeth divided into five experimental groups (A, B, C including two controls (D, E with ten samples in each group randomly. Following the repair procedure, the pulp chambers and access openings were filled with composite resin and immersed in 2% methylene blue solution for 48 hours. The teeth were sectioned longitudinally and the linear dye penetration measured under a stereo­microscope. Results: The comparison of the linear length of micro-leakage (mm among the experimental groups revealed no significant difference (p = 0.332. On calculating the percentage of depth of leakage to the total length of the perforation, it was observed that the mean leakage was 35.5% in Group A, 53.6% in Group B and the highest, 87.5% in Group C. The mean of leakage percentage was statistically significant by Kruskal-Wallis test (p = 0.003. The results indicated that the dye penetration used as furcation perforation repair material was least with mineral trioxide aggregate. Comparing the depth of penetration of dye, 50% of the Group A samples showed less than 25% of depth penetration. While 40% of Group B cases had more than 50% dye penetration. In our study, all Group C teeth had ≥ 50% dye penetration. Conclusions: The present study indicated that GIC had the greatest dye penetration followed by CPC and MTA. Mineral trioxide aggregate and calcium phosphate cement had comparatively better sealing ability than glass ionomer cement.

  1. 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

  2. Casting of organic glass by radiation-induced polymerization of glass-forming monomers at low temperature. II. Optical strain of remaining stress type

    International Nuclear Information System (INIS)

    Okubo, H.; Yoshii, F.; Kaetsu, I.; Honda, S.

    1978-01-01

    Previously it was found that casting could be carried out efficiently without strain formation by radiation-induced polymerization of glass-forming monomers. Two types of strain were observed in casting: thermal stream type, which was studied previously, and remained stress type. In this report, the effect of various factors on the formation of remaining stress-type strain in radiation-induced casting polymerization was studied. It was found that the molecular weight of prepolymer did not affect strain formation, while prepolymer concentration and viscosity of the system had a serious influence on strain formation. It could be deduced that this type of strain formed as a result of remaining inner stress due to poor relaxation of the shrinking stress. It was realized that less volume shrinkage of glass-forming monomers accompanying casting polymerization reduced the strain formation of this type in radiation-induced casting polymerization at low temperatures

  3. Simple Theory for the Dynamics of Mean-Field-Like Models of Glass-Forming Fluids

    Science.gov (United States)

    Szamel, Grzegorz

    2017-10-01

    We propose a simple theory for the dynamics of model glass-forming fluids, which should be solvable using a mean-field-like approach. The theory is based on transparent physical assumptions, which can be tested in computer simulations. The theory predicts an ergodicity-breaking transition that is identical to the so-called dynamic transition predicted within the replica approach. Thus, it can provide the missing dynamic component of the random first order transition framework. In the large-dimensional limit the theory reproduces the result of a recent exact calculation of Maimbourg et al. [Phys. Rev. Lett. 116, 015902 (2016), 10.1103/PhysRevLett.116.015902]. Our approach provides an alternative, physically motivated derivation of this result.

  4. The Monte Carlo dynamics of a binary Lennard-Jones glass-forming mixture

    International Nuclear Information System (INIS)

    Berthier, L; Kob, W

    2007-01-01

    We use a standard Monte Carlo algorithm to study the slow dynamics of a binary Lennard-Jones glass-forming mixture at low temperature. We find that the Monte Carlo approach is by far the most efficient way to simulate a stochastic dynamics since the relaxation is about 10 times faster than in Brownian dynamics and about 30 times faster than in stochastic dynamics. Moreover, the average dynamical behaviour of the system is in quantitative agreement with that obtained using Newtonian dynamics, apart from at very short times where thermal vibrations are suppressed. We show, however, that dynamic fluctuations quantified by four-point dynamic susceptibilities do retain a dependence on the microscopic dynamics, as recently predicted theoretically

  5. Crystal phases of a glass-forming Lennard-Jones mixture

    International Nuclear Information System (INIS)

    Fernandez, Julian R.; Harrowell, Peter

    2003-01-01

    We compare the potential energy at zero temperature of a range of crystal structures for a glass-forming binary mixture of Lennard-Jones particles. The lowest-energy ordered state consists of coexisting phases of a single component face centered cubic structure and an equimolar cesium chloride structure. An infinite number of layered crystal structures are identified with energies close to this ground state. We demonstrate that the finite size increase of the energy of the coexisting crystal with incoherent interfaces is sufficient to destabilize this ordered phase in simulations of typical size. Two specific local coordination structures are identified as of possible structural significance in the amorphous state. We observe rapid crystal growth in the equimolar mixture

  6. Immobilization of enzymes by radiation-induced polymerization of glass-forming monomers

    International Nuclear Information System (INIS)

    Yoshida, M.; Kumakura, M.; Kaetsu, I.

    1979-01-01

    The effect of cooling rate of a monomeric system on the porosity and activity of an immobilized enzyme prepared by radiation-induced polymerization of 2-hydroxyethyl methacrylate at low temperatures has been studied. Slow cooling gave the same effect on porosity of the polymer as decreasing the monomer concentration. A glass-forming solvent such as diethylene glycol was added to water to study the effect of the supercooling tendency of the solvent. Addition of diethylene glycol decreased porosity and also enzymic activity. Water was replaced by the miscible solvent p-dioxane and the immiscible solvent n-decane in order to clarify the effect of solvent. p-Dioxane had a similar effect to water on the relation between the monomer concentration, porosity and activity. On the other hand, polymer prepared from the system containing n-decane showed different immobilization properties owing to the presence of independent pores in the matrix. (author)

  7. Characteristics of borosilicate waste glass form for high-level radioactive waste

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Soo; Chun, Kwan Sik; Choi, Jong Won; Kang, Chul Hyung

    2001-03-01

    Basic data, required for the design and the performance assessment of a repository of HLW, suchas the chemical composition and the characteristics of the borosilicate waste glass have been identified according to the burn-ups of spent PWR fuels. The diemnsion of waste canister is 430mm in diameter and 1135mm in length, and the canister should hold less than 2kwatts of heat from their decay of radionuclides contained in the HLW. Based on the reprocessing of 5 years-cooled spent fuel, one canister could hold about 11.5wt.% and 10.8wt.% of oxidized HLW corresponding to their burn-ups of 45,000MWD/MTU and 55,000MWD/MTU, respectively. These waste forms have been recommanded as the reference waste forms of HLW. The characteristics of these wastes as a function of decay time been evaluated. However, after a specific waste form and a specific site for the disposal would be selected, the characteristics of the waste should be reevaluated under the consideration of solidification period, loaded waste, storage condition and duration, site circumstances for the repository system and its performance assessment.

  8. Estimates of radionuclide release from glass waste forms in a tuff repository and the effects on regulatory compliance

    International Nuclear Information System (INIS)

    Aines, R.D.

    1986-04-01

    This paper discusses preliminary estimates of the release of radionuclides from waste packages containing glass-based waste forms under the expected conditions at Yucca Mountain. These estimates can be used to evaluate the contribution of waste package performance toward meeting repository regulatory restrictions on radionuclide release. Glass waste will be held in double stainless steel canisters. After failure of the container sometime after the 300 to 1000 year containment period, the open headspace in these cans will provide the only area where standing water can accumulate and react with the glass. A maximum release rate of 0.177 g/m 2 x year or 1.3 grams per year was obtained. Normalized loss of 1.3 grams per year corresponds to 0.08 parts in 100,000 per year of the 1660 kg reference weight of DWPF glass

  9. Long-term musical training may improve different forms of visual attention ability.

    Science.gov (United States)

    Rodrigues, Ana Carolina; Loureiro, Maurício Alves; Caramelli, Paulo

    2013-08-01

    Many studies have suggested that structural and functional cerebral neuroplastic processes result from long-term musical training, which in turn may produce cognitive differences between musicians and non-musicians. We aimed to investigate whether intensive, long-term musical practice is associated with improvements in three different forms of visual attention ability: selective, divided and sustained attention. Musicians from symphony orchestras (n=38) and non-musicians (n=38), who were comparable in age, gender and education, were submitted to three neuropsychological tests, measuring reaction time and accuracy. Musicians showed better performance relative to non-musicians on four variables of the three visual attention tests, and such an advantage could not solely be explained by better sensorimotor integration. Moreover, in the group of musicians, significant correlations were observed between the age at the commencement of musical studies and reaction time in all visual attention tests. The results suggest that musicians present augmented ability in different forms of visual attention, thus illustrating the possible cognitive benefits of long-term musical training. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Effect of component substitution on the atomic dynamics in glass-forming binary metallic melts

    Science.gov (United States)

    Nowak, B.; Holland-Moritz, D.; Yang, F.; Voigtmann, Th.; Evenson, Z.; Hansen, T. C.; Meyer, A.

    2017-08-01

    We investigate the substitution of early transition metals (Zr, Hf, and Nb) in Ni-based binary glass-forming metallic melts and the impact on structural and dynamical properties by using a combination of neutron scattering, electrostatic levitation (ESL), and isotopic substitution. The self-diffusion coefficients measured by quasielastic neutron scattering (QENS) identify a sluggish diffusion as well as an increased activation energy by almost a factor of 2 for Hf35Ni65 compared to Zr36Ni64 . This finding can be explained by the locally higher packing density of Hf atoms in Hf35Ni65 compared to Zr atoms in Zr36Ni64 , which has been derived from interatomic distances by analyzing the measured partial structure factors. Furthermore, QENS measurements of liquid Hf35Ni65 prepared with 60Ni , which has a vanishing incoherent scattering cross section, have demonstrated that self-diffusion of Hf is slowed down compared to the concentration weighted self-diffusion of Hf and Ni. This implies a dynamical decoupling between larger Hf and smaller Ni atoms, which can be related to a saturation effect of unequal atomic nearest-neighbor pairs, that was observed recently for Ni-rich compositions in Zr-Ni metallic melts. In order to establish a structure-dynamics relation, measured partial structure factors have been used as an input for mode-coupling theory (MCT) of the glass transition to calculate self-diffusion coefficients for the different atomic components. Remarkably, MCT can reproduce the increased activation energy for Hf35Ni65 as well as the dynamical decoupling between Hf and Ni atoms.

  11. Preparation and characterization of Fe-based bulk metallic glasses in plate form

    International Nuclear Information System (INIS)

    Lavorato, G.C.; Fiore, G.; Castellero, A.; Baricco, M.; Moya, J.A.

    2012-01-01

    Amorphous alloys with composition (at%) Fe 48 Cr 15 Mo 14 C 15 B 6 Gd 2 (alloy A) and Fe 48 Cr 15 Mo 14 C 15 B 6 Y 2 (alloy B) were prepared either using pure elements (A and B1) and a commercial AISI430 steel as a base material (B2). When prepared from pure elements both alloys (A and B1) could be cast in plate form with a fixed thickness of 2 mm and variable lengths between 10 and 20 mm by means of copper-mold injection in air atmosphere. In the case of alloy B2, prepared using commercial grade raw materials, rods of 2 mm diameter were obtained. X-ray diffraction and scanning electron microscopy observations confirmed that an amorphous structure was obtained in all the as-cast samples. A minor fraction of crystalline phases (oxides and carbides) was detected on the as-cast surface. Differential scanning calorimetry measurements showed a glass transition temperature at 856 K for alloy A and 841 K for alloy B1, and an onset crystallization temperature of 887 K for alloy A and 885 K for alloy B1. In the case of alloy B2 a slightly different crystallization sequence was observed. Values of hardness (∼13 GPa) and the Young modulus (∼180 GPa) were measured by nanoindentation for both the alloys. The effects of adverse casting conditions (such as air atmosphere, non-conventional injection copper mold casting and partial replacement of pure elements with commercial grade raw materials) on the glass formation and properties of the alloy are discussed.

  12. Preparation and characterization of Fe-based bulk metallic glasses in plate form

    Energy Technology Data Exchange (ETDEWEB)

    Lavorato, G.C. [INTECIN (FIUBA-CONICET), Paseo Colon 850, Capital Federal (Argentina); Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Fiore, G.; Castellero, A.; Baricco, M. [Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Moya, J.A., E-mail: jmoya.fi.uba@gmail.com [IESIING, Facultad de Ingenieria e Informatica, UCASAL, Salta (Argentina); CONICET (Argentina)

    2012-08-15

    Amorphous alloys with composition (at%) Fe{sub 48}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Gd{sub 2} (alloy A) and Fe{sub 48}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Y{sub 2} (alloy B) were prepared either using pure elements (A and B1) and a commercial AISI430 steel as a base material (B2). When prepared from pure elements both alloys (A and B1) could be cast in plate form with a fixed thickness of 2 mm and variable lengths between 10 and 20 mm by means of copper-mold injection in air atmosphere. In the case of alloy B2, prepared using commercial grade raw materials, rods of 2 mm diameter were obtained. X-ray diffraction and scanning electron microscopy observations confirmed that an amorphous structure was obtained in all the as-cast samples. A minor fraction of crystalline phases (oxides and carbides) was detected on the as-cast surface. Differential scanning calorimetry measurements showed a glass transition temperature at 856 K for alloy A and 841 K for alloy B1, and an onset crystallization temperature of 887 K for alloy A and 885 K for alloy B1. In the case of alloy B2 a slightly different crystallization sequence was observed. Values of hardness ({approx}13 GPa) and the Young modulus ({approx}180 GPa) were measured by nanoindentation for both the alloys. The effects of adverse casting conditions (such as air atmosphere, non-conventional injection copper mold casting and partial replacement of pure elements with commercial grade raw materials) on the glass formation and properties of the alloy are discussed.

  13. Structural predictor for nonlinear sheared dynamics in simple glass-forming liquids.

    Science.gov (United States)

    Ingebrigtsen, Trond S; Tanaka, Hajime

    2018-01-02

    Glass-forming liquids subjected to sufficiently strong shear universally exhibit striking nonlinear behavior; for example, a power-law decrease of the viscosity with increasing shear rate. This phenomenon has attracted considerable attention over the years from both fundamental and applicational viewpoints. However, the out-of-equilibrium and nonlinear nature of sheared fluids have made theoretical understanding of this phenomenon very challenging and thus slower to progress. We find here that the structural relaxation time as a function of the two-body excess entropy, calculated for the extensional axis of the shear flow, collapses onto the corresponding equilibrium curve for a wide range of pair potentials ranging from harsh repulsive to soft and finite. This two-body excess entropy collapse provides a powerful approach to predicting the dynamics of nonequilibrium liquids from their equilibrium counterparts. Furthermore, the two-body excess entropy scaling suggests that sheared dynamics is controlled purely by the liquid structure captured in the form of the two-body excess entropy along the extensional direction, shedding light on the perplexing mechanism behind shear thinning.

  14. Structural predictor for nonlinear sheared dynamics in simple glass-forming liquids

    Science.gov (United States)

    Ingebrigtsen, Trond S.; Tanaka, Hajime

    2018-01-01

    Glass-forming liquids subjected to sufficiently strong shear universally exhibit striking nonlinear behavior; for example, a power-law decrease of the viscosity with increasing shear rate. This phenomenon has attracted considerable attention over the years from both fundamental and applicational viewpoints. However, the out-of-equilibrium and nonlinear nature of sheared fluids have made theoretical understanding of this phenomenon very challenging and thus slower to progress. We find here that the structural relaxation time as a function of the two-body excess entropy, calculated for the extensional axis of the shear flow, collapses onto the corresponding equilibrium curve for a wide range of pair potentials ranging from harsh repulsive to soft and finite. This two-body excess entropy collapse provides a powerful approach to predicting the dynamics of nonequilibrium liquids from their equilibrium counterparts. Furthermore, the two-body excess entropy scaling suggests that sheared dynamics is controlled purely by the liquid structure captured in the form of the two-body excess entropy along the extensional direction, shedding light on the perplexing mechanism behind shear thinning.

  15. A comparative study of ibuprofen and ketoprofen glass-forming liquids by molecular dynamics simulations

    Science.gov (United States)

    Ottou Abe, M. T.; Correia, N. T.; Ndjaka, J. M. B.; Affouard, F.

    2015-10-01

    In this paper, structural and dynamical properties of ibuprofen and ketoprofen glass-forming liquids have been investigated by means of molecular dynamics simulations. Molecular mobility of both materials is analyzed with respect to the different inter-molecular linear/cyclic hydrogen bonding associations. For ibuprofen, the dominant organization is found to be composed of small hydrogen bonding aggregates corresponding to cyclic dimers through the carboxyl group. For ketoprofen, the propensity of cyclic dimers is significantly reduced by the formation of hydrogen bonds with the ketone oxygen of the molecule altering the hydrogen bond (HB) associating structures that can be formed and thus molecular dynamics. The issue of the presence/absence of the peculiar low frequency Debye-type process in dielectric relaxation spectroscopy (DRS) data in these materials is addressed. Results obtained from simulations confirm that the Debye process originates from the internal cis-trans conversion of the —COOH carboxyl group. It is shown that the specific intermolecular HB structures associated to a given profen control the main dynamical features of this conversion, in particular its separation from the α-process, which make it detectable or not from DRS. For ibuprofen, the possible role of the —CCCO torsion motion, more "local" than the —COOH motion since it is less influenced by the intermolecular HBs, is suggested in the microscopic origin of the quite intense secondary γ-relaxation process detected from DRS.

  16. Magnetic nanoparticles formed in glasses co-doped with iron and larger radius elements

    OpenAIRE

    Edelman , Irina; Ivanova , Oxana; Ivantsov , Ruslan; Velikanov , D.; Zabluda , V.; Zubavichus , Y.; Veligzhanin , A.; Zaikovskiy , V.; Stepanov , S.; Artemenko , Alla; Curély , Jacques; Kliava , Janis

    2012-01-01

    International audience; A new type of nanoparticle-containing glasses based on borate glasses co-doped with low contents of iron and larger radius elements, Dy, Tb, Gd, Ho, Er, Y, and Bi, is studied. Heat treatment of these glasses results in formation of magnetic nanoparticles, radically changing their physical properties. Transmission electron microscopy and synchrotron radiation-based techniques: x-ray diffraction, extended x-ray absorption fine structure, x-ray absorption near-edge struct...

  17. The effect of assessment form to the ability of student to answer the problem correctly

    Directory of Open Access Journals (Sweden)

    Arifian Dimas

    2017-02-01

    Full Text Available Assessment is an important part of education. For educators, are collecting information about students learning and information about the learning process. For students, the assessment is the process of informing them about the progress of learning. Effective assessment process is responsive to the strengths, needs and clearly articulated student learning objectives. This research was aimed to know the effect of assessment form towards students ability in answering the problem correctly on kinematics and dynamics of motion. The method used in this research is descriptive qualitative. The data collecting method are assessment test and interview. Assessment test instrument are written test and animation form test. The question we use was taken "Force Concept Inventory" on kinematics and dynamics concepts. The sample are 36 student of 6th terms student of Physics Undergraduate Departement in Sebelas Maret University. The result shows that for kinematics concept, more students answer correctly for test presented in animation form but for dynamics concept conventional test is better.

  18. Mean-coordination number dependence of the fragility in Ge-Se-In glass-forming liquids

    International Nuclear Information System (INIS)

    Saffarini, G.; Saiter, A.; Garda, M.R.; Saiter, J.M.

    2007-01-01

    Differential scanning calorimetry measurements have been performed on elemental Se as well as on Ge x Se 94- x In 6 (x=4, 8, and 11 at%) and on Ge y Se 88- y In 12 (y=5, 7, and 9 at%) chalcogenide glasses. From the cooling rate dependence of the fictive temperature, the apparent activation energies, Δh*, and the fragility indices, m, as defined in the strong-fragile glass-forming liquid concept, are determined. It is found that, in Ge-Se-In system, there is an evolution from strong (m=67) to fragile (m=116) glass-forming liquids. The dependence of 'm' on the mean-coordination number, Z, is also obtained. This dependence is rationalized by assuming that, in this glassy alloy system, there is a tendency for the formation of In 2 Se 3 clusters

  19. Crystal growth nucleation and Fermi energy equalization of intrinsic spherical nuclei in glass-forming melts

    Directory of Open Access Journals (Sweden)

    Robert F Tournier

    2009-01-01

    Full Text Available The energy saving resulting from the equalization of Fermi energies of a crystal and its melt is added to the Gibbs free-energy change ΔG2ls associated with a crystal formation in glass-forming melts. This negative contribution being a fraction ε ls(T of the fusion heat is created by the electrostatic potential energy −U0 resulting from the electron transfer from the crystal to the melt and is maximum at the melting temperature Tm in agreement with a thermodynamics constraint. The homogeneous nucleation critical temperature T2, the nucleation critical barrier ΔG2ls*/kBT and the critical radius R*2ls are determined as functions of εls(T. In bulk metallic glass forming melts, εls(T and T2 only depend on the free-volume disappearance temperature T0l, and εls(Tm is larger than 1 (T0l>Tm/3; in conventional undercooled melts εls(Tm is smaller than 1 (T0l>Tm/3. Unmelted intrinsic crystals act as growth nuclei reducing ΔG2ls*/kBT and the nucleation time. The temperature-time transformation diagrams of Mg65Y10 Cu25, Zr41.2Ti13.8 Cu12.5Ni10Be22.5, Pd43Cu27 Ni10P20, Fe83B17 and Ni melts are predicted using classic nucleation models including time lags in transient nucleation, by varying the intrinsic nucleus contribution to the reduction of ΔG2ls*/kBT. The energy-saving coefficient ε nm(T of an unmelted crystal of radius Rnm is reduced when Rnm LtR*2ls; εnm is quantified and corresponds to the first energy level of one s-electron moving in vacuum in the same spherical attractive potential −U0 despite the fact that the charge screening is built by many-body effects.

  20. Infrared and x-ray photoelectron spectroscopic studies on sodium borosilicate glass interacted with thermally oxidized aluminides formed on alloy 690

    International Nuclear Information System (INIS)

    Yusufali, C.; Dutta, R.S.; Dey, G.K.; Kshirsagar, R.J.; Jagannath; Mishra, R.K.

    2012-01-01

    Thermally oxidized aluminides formed on Ni-Cr-Fe based superalloy 690 substrates were subjected to interaction with sodium borosilicate melt (used as matrices for immobilization of high-level radioactive liquid waste) at 1248 K for 192 hours. After the interaction, Fourier-transform infrared (FT-IR) spectroscopy analysis of glass samples indicated the incorporation of Al in the glass network. X-ray photoelectron spectroscopy (XPS) of glass specimens revealed modified glass structure. (author)

  1. Durum Wheat (Triticum Durum Desf. Lines Show Different Abilities to Form Masked Mycotoxins under Greenhouse Conditions

    Directory of Open Access Journals (Sweden)

    Martina Cirlini

    2013-12-01

    Full Text Available Deoxynivalenol (DON is the most prevalent trichothecene in Europe and its occurrence is associated with infections of Fusarium graminearum and F. culmorum, causal agents of Fusarium head blight (FHB on wheat. Resistance to FHB is a complex character and high variability occurs in the relationship between DON content and FHB incidence. DON conjugation to glucose (DON-3-glucoside, D3G is the primary plant mechanism for resistance towards DON accumulation. Although this mechanism has been already described in bread wheat and barley, no data are reported so far about durum wheat, a key cereal in the pasta production chain. To address this issue, the ability of durum wheat to detoxify and convert deoxynivalenol into D3G was studied under greenhouse controlled conditions. Four durum wheat varieties (Svevo, Claudio, Kofa and Neodur were assessed for DON-D3G conversion; Sumai 3, a bread wheat variety carrying a major QTL for FHB resistance (QFhs.ndsu-3B, was used as a positive control. Data reported hereby clearly demonstrate the ability of durum wheat to convert deoxynivalenol into its conjugated form, D3G.

  2. Designing new biocompatible glass-forming Ti75-x Zr10 Nbx Si15 (x = 0, 15) alloys: corrosion, passivity, and apatite formation.

    Science.gov (United States)

    Abdi, Somayeh; Oswald, Steffen; Gostin, Petre Flaviu; Helth, Arne; Sort, Jordi; Baró, Maria Dolors; Calin, Mariana; Schultz, Ludwig; Eckert, Jürgen; Gebert, Annett

    2016-01-01

    Glass-forming Ti-based alloys are considered as potential new materials for implant applications. Ti75 Zr10 Si15 and Ti60 Zr10 Nb15 Si15 alloys (free of cytotoxic elements) can be produced as melt-spun ribbons with glassy matrix and embedded single β-type nanocrystals. The corrosion and passivation behavior of these alloys in their homogenized melt-spun states have been investigated in Ringer solution at 37°C in comparison to their cast multiphase crystalline counterparts and to cp-Ti and β-type Ti-40Nb. All tested materials showed very low corrosion rates as expressed in corrosion current densities icorr  alloys passive states in a wide potential range. This corresponds to low passive current densities ipass  = 2 ± 1 µA/cm(2) based on the growth of oxide films with thickness d alloys is beneficial for stable surface passivity. The addition of Nb does not only improve the glass-forming ability and the mechanical properties but also supports a high pitting resistance even at extreme anodic polarization up to 4V versus SCE were oxide thickness values of d ∼35 nm are reached. With regard to the corrosion properties, the Nb-containing nearly single-phase glassy alloy can compete with the β-type Ti-40Nb alloy. SBF tests confirmed the ability for formation of hydroxyapatite on the melt-spun alloy surfaces. All these properties recommend the new glass-forming alloys for application as wear- and corrosion-resistant coating materials for implants. © 2015 Wiley Periodicals, Inc.

  3. Kissinger method applied to the crystallization of glass-forming liquids: Regimes revealed by ultra-fast-heating calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Orava, J., E-mail: jo316@cam.ac.uk [Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Greer, A.L., E-mail: alg13@cam.ac.uk [Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); WPI-Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2015-03-10

    Highlights: • Study of ultra-fast DSC applied to the crystallization of glass-forming liquids. • Numerical modeling of DSC traces at heating rates exceeding 10 orders of magnitude. • Identification of three regimes in Kissinger plots. • Elucidation of the effect of liquid fragility on the Kissinger method. • Modeling to study the regime in which crystal growth is thermodynamically limited. - Abstract: Numerical simulation of DSC traces is used to study the validity and limitations of the Kissinger method for determining the temperature dependence of the crystal-growth rate on continuous heating of glasses from the glass transition to the melting temperature. A particular interest is to use the wide range of heating rates accessible with ultra-fast DSC to study systems such as the chalcogenide Ge{sub 2}Sb{sub 2}Te{sub 5} for which fast crystallization is of practical interest in phase-change memory. Kissinger plots are found to show three regimes: (i) at low heating rates the plot is straight, (ii) at medium heating rates the plot is curved as expected from the liquid fragility, and (iii) at the highest heating rates the crystallization rate is thermodynamically limited, and the plot has curvature of the opposite sign. The relative importance of these regimes is identified for different glass-forming systems, considered in terms of the liquid fragility and the reduced glass-transition temperature. The extraction of quantitative information on fundamental crystallization kinetics from Kissinger plots is discussed.

  4. Kissinger method applied to the crystallization of glass-forming liquids: Regimes revealed by ultra-fast-heating calorimetry

    International Nuclear Information System (INIS)

    Orava, J.; Greer, A.L.

    2015-01-01

    Highlights: • Study of ultra-fast DSC applied to the crystallization of glass-forming liquids. • Numerical modeling of DSC traces at heating rates exceeding 10 orders of magnitude. • Identification of three regimes in Kissinger plots. • Elucidation of the effect of liquid fragility on the Kissinger method. • Modeling to study the regime in which crystal growth is thermodynamically limited. - Abstract: Numerical simulation of DSC traces is used to study the validity and limitations of the Kissinger method for determining the temperature dependence of the crystal-growth rate on continuous heating of glasses from the glass transition to the melting temperature. A particular interest is to use the wide range of heating rates accessible with ultra-fast DSC to study systems such as the chalcogenide Ge 2 Sb 2 Te 5 for which fast crystallization is of practical interest in phase-change memory. Kissinger plots are found to show three regimes: (i) at low heating rates the plot is straight, (ii) at medium heating rates the plot is curved as expected from the liquid fragility, and (iii) at the highest heating rates the crystallization rate is thermodynamically limited, and the plot has curvature of the opposite sign. The relative importance of these regimes is identified for different glass-forming systems, considered in terms of the liquid fragility and the reduced glass-transition temperature. The extraction of quantitative information on fundamental crystallization kinetics from Kissinger plots is discussed

  5. Applications of High Energy Ion Beam Techniques in Environmental Science: Investigation Associated with Glass and Ceramic Waste Forms

    Energy Technology Data Exchange (ETDEWEB)

    Thevuthasan, Suntharampillai; Shutthanandan, V; Zhang, Yanwen

    2006-02-01

    High energy ion beam capabilities including Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) have been very effectively used in environmental science to investigate the ion exchange mechanisms in glass waste forms and the effects of irradiation in glass and ceramic waste forms in the past. In this study, RBS and NRA along with SIMNRA simulations were used to monitor the Na depletion and D and 18O uptake in alumina silicate glasses, respectively, after the glass coupons were exposed to aqueous solution. These results show that the formation of a reaction layer and an establishment of a region where diffusion limited ion exchange occur in these glasses during exposure to silica-saturated solutions. Different regions including reaction and diffusion regions were identified on the basis of the depth distributions of these elements. In the case of ceramics, damage accumulation was studied as a function of ion dose at different irradiation temperatures. A sigmoidal dependence of relative disorder on the ion dose was observed. The defect dechanneling factors were calculated for two irradiated regions in SrTiO? using the critical angles determined from the angular yield curves. The dependence of defect dechanneling parameter on the incident energy was investigated and it was observed that the generated defects are mostly interstitial atoms and amorphous clusters. Thermal recovery experiments were performed to study the damage recovery processes up to a maximum temperature of 870 K.

  6. Effect of low dose electron beam irradiation on the alteration layer formed during nuclear glass leaching

    Energy Technology Data Exchange (ETDEWEB)

    Mougnaud, S., E-mail: sarah.mougnaud@gmail.com [CEA Marcoule, DEN, DTCD, SECM, BP 17171, 30207 Bagnols-sur-Cèze cedex (France); Tribet, M. [CEA Marcoule, DEN, DTCD, SECM, BP 17171, 30207 Bagnols-sur-Cèze cedex (France); Renault, J.-P. [NIMBE, CNRS, CEA, Université Paris Saclay, CEA Saclay, 91191 Gif-sur-Yvette cedex (France); Jollivet, P. [CEA Marcoule, DEN, DTCD, SECM, BP 17171, 30207 Bagnols-sur-Cèze cedex (France); Panczer, G. [Institut Lumière Matière, UMR 5306, Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex (France); Charpentier, T. [NIMBE, CNRS, CEA, Université Paris Saclay, CEA Saclay, 91191 Gif-sur-Yvette cedex (France); Jégou, C. [CEA Marcoule, DEN, DTCD, SECM, BP 17171, 30207 Bagnols-sur-Cèze cedex (France)

    2016-12-15

    This investigation concerns borosilicate glass leaching mechanisms and the evolution of alteration layer under electron beam irradiation. A simple glass doped with rare earth elements was selected in order to access mechanistic and structural information and better evaluate the effects of irradiation. It was fully leached in initially pure water at 90 °C and at high glass surface area to solution volume ratio (S/V = 20 000 m{sup −1}) in static conditions. Under these conditions, the system quickly reaches the residual alteration rate regime. A small particle size fraction (2–5 μm) was sampled in order to obtain a fairly homogeneous altered material enabling the use of bulk characterization methods. External irradiations with 10 MeV electrons up to a dose of 10 MGy were performed either before or after leaching, to investigate respectively the effect of initial glass irradiation on its alteration behavior and the irradiation stability of the alteration layer. Glass dissolution rate was analyzed by regular leachate samplings and the alteration layer structure was characterized by Raman, luminescence (continuous or time-resolved), and {sup 29}Si MAS NMR and EPR spectroscopy. It was shown that the small initial glass evolutions under irradiation did not induce any modification of the leaching kinetic nor of the structure of the alteration layer. The alteration process seemed to “smooth over” the created defects. Otherwise, the alteration layer and initial glass appeared to have different behaviors under irradiation. No Eu{sup 3+} reduction was detected in the alteration layer after irradiation and the defect creation efficiency was much lower than for initial glass. This can possibly be explained by the protective role of pore water contained in the altered material (∼20%). Moreover, a slight depolymerization of the silicon network of the altered glass under irradiation with electrons was evidenced, whereas in the initial glass it typically

  7. Growing correlation length on cooling below the onset of caging in a simulated glass-forming liquid

    DEFF Research Database (Denmark)

    Lačević, N.; Starr, F. W.; Schrøder, Thomas

    2002-01-01

    We present a calculation of a fourth-order, time-dependent density correlation function that measures higher-order spatiotemporal correlations of the density of a liquid. From molecular dynamics simulations of a glass-forming Lennard-Jones liquid, we find that the characteristic length scale...... of the dynamics of the liquid in the alpha-relaxation regime....

  8. Electronic structure of metallic glasses

    International Nuclear Information System (INIS)

    Oelhafen, P.; Lapka, R.; Gubler, U.; Krieg, J.; DasGupta, A.; Guentherodt, H.J.; Mizoguchi, T.; Hague, C.; Kuebler, J.; Nagel, S.R.

    1981-01-01

    This paper is organized in six sections and deals with (1) the glassy transition metal alloys, their d-band structure, the d-band shifts on alloying and their relation to the alloy heat of formation (ΔH) and the glass forming ability, (2) the glass to crystal phase transition viewed by valence band spectroscopy, (3) band structure calculations, (4) metallic glasses prepared by laser glazing, (5) glassy normal metal alloys, and (6) glassy hydrides

  9. AC Calorimetry and Thermophysical Properties of Bulk Glass-Forming Metallic Liquids

    Science.gov (United States)

    Johnson, William L.

    2000-01-01

    Thermo-physical properties of two bulk metallic glass forming alloys, Ti34Zr11Cu47Ni8 (VIT 101) and Zr57Nb5Ni12.6Al10CU15.4 (VIT 106), were investigated in the stable and undercooled melt. Our investigation focused on measurements of the specific heat in the stable and undercooled liquid using the method of AC modulation calorimetry. The VIT 106 exhibited a maximum undercooling of 140 K in free radiative cooling. Specific heat measurements could be performed in stable melt down to an undercooling of 80 K. Analysis of the specific heat data indicate an anomaly near the equilibrium liquidus temperature. This anomaly is also observed in y the temperature dependencies of the external relaxation time, the specific volume, and the surface tension; it is tentatively attributed to a phase separation in the liquid state. The VIT 101 specimen exhibited a small undercooling of about 50 K. Specific heat measurements were performed in the stable and undercooled melt. These various results will be combined with ground based work such as the measurement of T-T-T curves in the electrostatic levitator and low temperature viscosity and specific heat measurements for modeling the nucleation kinetics of these alloys.

  10. High density liquid structure enhancement in glass forming aqueous solution of LiCl

    Science.gov (United States)

    Camisasca, G.; De Marzio, M.; Rovere, M.; Gallo, P.

    2018-06-01

    We investigate using molecular dynamics simulations the dynamical and structural properties of LiCl:6H2O aqueous solution upon supercooling. This ionic solution is a glass forming liquid of relevant interest in connection with the study of the anomalies of supercooled water. The LiCl:6H2O solution is easily supercooled and the liquid state can be maintained over a large decreasing temperature range. We performed simulations from ambient to 200 K in order to investigate how the presence of the salt modifies the behavior of supercooled water. The study of the relaxation time of the self-density correlation function shows that the system follows the prediction of the mode coupling theory and behaves like a fragile liquid in all the range explored. The analysis of the changes in the water structure induced by the salt shows that while the salt preserves the water hydrogen bonds in the system, it strongly affects the tetrahedral hydrogen bond network. Following the interpretation of the anomalies of water in terms of a two-state model, the modifications of the oxygen radial distribution function and the angular distribution function of the hydrogen bonds in water indicate that LiCl has the role of enhancing the high density liquid component of water with respect to the low density component. This is in agreement with recent experiments on aqueous ionic solutions.

  11. Connection between fragility, mean-squared displacement and shear modulus in two van der Waals bonded glass-forming liquids

    DEFF Research Database (Denmark)

    Hansen, Henriette Wase; Frick, Bernhard; Hecksher, Tina

    2017-01-01

    The temperature dependence of the high-frequency shear modulus measured in the kHz range is compared with the mean-squared displacement measured in the nanosecond range for the two van der Waals bonded glass-forming liquids cumene and 5-polyphenyl ether. This provides an experimental test for the...... for the assumption connecting two versions of the shoving model for the non-Arrhenius temperature dependence of the relaxation time in glass formers. The two versions of the model are also tested directly and both are shown to work well for these liquids....

  12. Radiation-induced polymerization of glass-forming systems. VII. Polymerization in supercooled state under high pressure

    International Nuclear Information System (INIS)

    Kaetsu, I.; Yoshii, F.; Watanabe, Y.

    1978-01-01

    Radiation-induced polymerization of glass-forming monomers such as 2-hydroxyethyl methacrylate and glycidyl methacrylate under high pressure was studied. The glass transition temperature of these monomers was heightened by increased pressure. The temperature dependence of polymerizability showed a characteristic relation, similar to those in supercooled-phase polymerization under normal pressure, that had a maximum at T/sub ν/ which shifted to higher levels of temperature as well as to T/sub g/ under high pressure. Polymerizability in the supercooled state also increased under increased pressure

  13. Study of the environment and optical properties of Ti3+ ions formed under ionizing irradiations in oxide glasses

    International Nuclear Information System (INIS)

    Lombard, Pierre

    2009-10-01

    We studied by Electron Paramagnetic Resonance (EPR), by EPR simulation, by Raman spectroscopy and by photoluminescence the Ti 3+ ions formed under β-irradiation from 3, 37 * 10 5 to 1, 68 * 10 9 Gy in SiO 2 - Na 2 O - TiO 2 and SiO 2 - Al 2 0 3 - B 2 O 3 - Na 2 O - TiO 2 glasses. We demonstrate the existence of three different Ti 3+ sites in silicate glasses and three other Ti 3+ sites in alumino-borosilicate glasses. One of theses sites is common to both kind of glasses. Moreover, we associate theses sites to three different titanium environment: (VI)Ti 3+ (octahedral), (V)Ti 3+ square pyramid and may be (V)Ti 3+ trigonal bi - pyramid. The existence of theses sites is determined by the total integrated dose and by the [Na]/[Ti] ratio. We propose a definition of this ratio in the special case of SiO 2 - Al 2 O 3 - B 2 O 3 - Na 2 O - TiO 2 glasses. Last, under 266 nm excitation, we observe at room temperature an emission band at 500 nm attributed to Ti 4+ ions. Under a 532 nm excitation, we observe an emission band at 590 nm with a short lifetime (hundred of ns) attributed either to Ti 3+ ions or to an irradiation defect formed near a Ti 4+ ion. Our study demonstrate that is possible to control by the chemical composition and the integrated dose the Ti 3+ environment and the emission properties of this ion in an oxide glass. (author)

  14. Thermoplastic forming of bulk metallic glasses for precision robotics components, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Demand for novel manufacturing methods for space systems brings unique properties of bulk metallic glasses (BMG) into the spotlight. In addition to superior...

  15. Characterization of surface layers formed under natural environmental conditions on medieval glass from Siponto (Southern Italy)

    International Nuclear Information System (INIS)

    Genga, Alessandra; Siciliano, Maria; Fama, Lia; Filippo, Emanuela; Siciliano, Tiziana; Mangone, Annarosa; Traini, Angela; Laganara, Caterina

    2008-01-01

    In this paper a low-vacuum scanning electron microscope (SEM) coupled with an energy-dispersive X-ray spectrometer (EDX) was used to investigate the alteration processes that occur on silica-soda-lime glass exposed to soil materials and dated from XI to second half of XIII sec. The chemical data were collected for altered glass gel and fresh glass. In order to study the influence of chemical composition on weathering process, 16 glasses have been selected on the basis of the chemical characterization and on the basis of the different corrosion processes present on the fragments. Six selected samples had been produced with the use of natron as fluxer and 10 samples with the use of plant ash as fluxer. The analysed pieces come from Siponto excavations (Foggia, Italy) and they include feet and rims of chalices, fragments of lamps and of globular bottles

  16. Contribution of electron microscopy to the study of alteration layers formed on the surface of glasses

    International Nuclear Information System (INIS)

    Crovisier, J.L.; Eberhart, J.P.

    1985-01-01

    In order to understand the whole process of glass corrosion in aqueous solutions, the analysis of the reagent must be completed by a study of the actual alteration layers on the glass surface. Transmission electron microscopy on ultramicrotomic thin sections turns out to be a most suitable tool to achieve this. It enables to supplement the conventional methods of surface investigation, such as A.E.S., ESCA, IRRS, SIMS. Two examples are given. The first deals with a (SiO 2 -CaO-Na 2 O-P 2 O 5 )- glass leached in a buffer solution of tris-hydromethyl-aminomethane at 40 0 C. The major feature is ion exchange within a residual porous glass, followed by the precipitation of hydroxyapatite. In the second example, a basaltic glass is altered in sea-water at 50 0 C. The glass constituents are dissolved simultaneously and the alteration layer is a precipitate of crystalline and amorphous phases which have reached their saturation level [fr

  17. Investigation of biofilm forming ability in Staphylococci causing bovine mastitis using phenotypic and genotypic assays.

    Science.gov (United States)

    Darwish, Samah F; Asfour, Hanaa A E

    2013-01-01

    A total of 40 S. aureus and 68 coagulase negative Staphylococcus (CNS) isolates from bovine subclinical mastitis were investigated for their ability to form biofilm as one of the most important virulence factors.Using Congo Red Agar (CRA) method, 32.5%, 35%, and 32.5% of S. aureus strains were strong, intermediate, and negative biofilm producers, while in CNS the percentages were 29.5%, 42.6%, and 27.9%, respectively. By microtiter plate (MTP) method, 52.5%, 27.5%, and 20% of S. aureus isolates were strong, moderate, and weak biofilm producers, while in CNS the percentages were 44%, 30.9%, and 19.2%, respectively. Indian ink staining was used to detect the EPS layer of biofilm producers. All isolates were screened for presence of biofilm related genes, eno, icaA, icaD, and bap. In S. aureus isolates, the positive rates of eno, icaA, icaD, and bap genes were 75%, 15%, 62.5%, and 2.5% while in CNS were 92.6%, 5.9%, 47.1%, and 4.4%, respectively. The eno gene had the highest rate while the bap gene had the lowest rate. Presence of icaA and icaD genes was not always correlated with biofilm production. This study demonstrated high prevalence of Staphylococcus biofilm producers among bovine mastitis in Egypt. Therefore, attention must be paid toward implementation of new ways for effective treatment of such infections.

  18. Post-UV colony-forming ability of normal fibroblast strains and of the xeroderma pigmentosum group G strain

    International Nuclear Information System (INIS)

    Barrett, S.F.; Tarone, R.E.; Moshell, A.N.; Ganges, M.B.; Robbins, J.H.

    1981-01-01

    In xeroderma pigmentosum, an inherited disorder of defective DNA repair, post-uv colony-forming ability of fibroblasts from patients in complementation groups A through F correlates with the patients' neurological status. The first xeroderma pigmentosum patient assigned to the recently discovered group G had the neurological abnormalities of XP. Researchers have determined the post-uv colony-forming ability of cultured fibroblasts from this patient and from 5 more control donors. Log-phase fibroblasts were irradiated with 254 nm uv light from a germicidal lamp, trypsinized, and replated at known densities. After 2 to 4 weeks' incubation the cells were fixed, stained and scored for colony formation. The strains' post-uv colony-forming ability curves were obtained by plotting the log of the percent remaining post-uv colony-forming ability as a function of the uv dose. The post-uv colony-forming ability of 2 of the 5 new normal strains was in the previously defined control donor zone, but that of the other 3 extended down to the level of the most resistant xeroderma pigmentosum strain. The post-uv colony-forming ability curve of the group G fibroblasts was not significantly different from the curves of the group D fibroblast strains from patients with clinical histories similar to that of the group G patient

  19. Electrochromic Glasses.

    Science.gov (United States)

    1980-07-31

    this glass and that dipole-dipole correlations contribute to the "ferroelectric-like" character of this amorphous system. The TeO2 -W03 glasses can only...shows the dielectric constant and Fig. I(b) glass from pure TeO2 ot pure WO. In addition, glass the tan 8 of the WO glass as a function of temperature... glasses containing WO, in various glass forming nitworks of LifO-B1O0, Na:O-BzO,, and TeO2 were prepared from reagent grade oxides at 800 C - 9SO C in

  20. Improving the Ability of Mathematic Representation Capabilities and Students Skills in Importing Square Forms to Square Using Variation Solutions

    Science.gov (United States)

    Nirawati, R.

    2018-04-01

    This research was conducted to see whether the variation of the solution is acceptable and easy to understand by students with different level of ability so that it can be seen the difference of students ability in facilitating the quadratic form in the upper, middle and lower groups. This research used experimental method with factorial design. Based on the result of final test analysis, there were differences of students ability in upper group, medium group, and lower group in putting squared form based on the use certain variation of solution.

  1. Staphylococcus aureus Clinical Isolates: Antibiotic Susceptibility, Molecular Characteristics, and Ability to Form Biofilm

    Directory of Open Access Journals (Sweden)

    N. Indrawattana

    2013-01-01

    Full Text Available Periodic monitoring of Staphylococcus aureus characteristics in a locality is imperative as their drug-resistant variants cause treatment problem. In this study, antibiograms, prevalence of toxin genes (sea-see, seg-ser, seu, tsst-1, eta, etb, and etd, PFGE types, accessory gene regulator (agr groups, and ability to form biofilm of 92 S. aureus Thailand clinical isolates were investigated. They were classified into 10 drug groups: groups 1–7 (56 isolates were methicillin resistant (MRSA and 8–10 (36 isolates were methicillin sensitive (MSSA. One isolate did not have any toxin gene, 4 isolates carried one toxin gene (seq, and 87 isolates had two or more toxin genes. No isolate had see, etb, or tsst-1; six isolates had eta or etd. Combined seg-sei-sem-sen-seo of the highly prevalent egc locus was 26.1%. The seb, sec, sel, seu, and eta associated significantly with MSSA; sek was more in MRSA. The sek-seq association was 52.17% while combined sed-sej was not found. Twenty-three PFGE types were revealed, no association of toxin genes with PFGE types. All four agr groups were present; agr group 1 was predominant (58.70% but agr group 2 strains carried more toxin genes and were more frequent toxin producers. Biofilm formation was found in 72.83% of the isolates but there was no association with antibiograms. This study provides insight information on molecular and phenotypic markers of Thailand S. aureus clinical isolates which should be useful for future active surveillance that aimed to control a spread of existing antimicrobial resistant bacteria and early recognition of a newly emerged variant.

  2. Interspecific in vitro assay for the chimera-forming ability of human pluripotent stem cells.

    Science.gov (United States)

    Masaki, Hideki; Kato-Itoh, Megumi; Umino, Ayumi; Sato, Hideyuki; Hamanaka, Sanae; Kobayashi, Toshihiro; Yamaguchi, Tomoyuki; Nishimura, Ken; Ohtaka, Manami; Nakanishi, Mahito; Nakauchi, Hiromitsu

    2015-09-15

    Functional assay limitations are an emerging issue in characterizing human pluripotent stem cells (PSCs). With rodent PSCs, chimera formation using pre-implantation embryos is the gold-standard assay of pluripotency (competence of progeny to differentiate into all three germ layers). In human PSCs (hPSCs), however, this can only be monitored via teratoma formation or in vitro differentiation, as ethical concerns preclude generation of human-human or human-animal chimeras. To circumvent this issue, we developed a functional assay utilizing interspecific blastocyst injection and in vitro culture (interspecies in vitro chimera assay) that enables the development and observation of embryos up to headfold stage. The assay uses mouse pre-implantation embryos and rat, monkey and human PSCs to create interspecies chimeras cultured in vitro to the early egg-cylinder stage. Intra- and interspecific chimera assays with rodent PSC lines were performed to confirm the consistency of results in vitro and in vivo. The behavior of chimeras developed in vitro appeared to recapitulate that of chimeras developed in vivo; that is, PSC-derived cells survived and were integrated into the epiblast of egg-cylinder-stage embryos. This indicates that the interspecific in vitro chimera assay is useful in evaluating the chimera-forming ability of rodent PSCs. However, when human induced PSCs (both conventional and naïve-like types) were injected into mouse embryos and cultured, some human cells survived but were segregated; unlike epiblast-stage rodent PSCs, they never integrated into the epiblast of egg-cylinder-stage embryos. These data suggest that the mouse-human interspecies in vitro chimera assay does not accurately reflect the early developmental potential/process of hPSCs. The use of evolutionarily more closely related species as host embryos might be necessary to evaluate the developmental potency of hPSCs. © 2015. Published by The Company of Biologists Ltd.

  3. Investigation of Biofilm Forming Ability in Staphylococci Causing Bovine Mastitis Using Phenotypic and Genotypic Assays

    Directory of Open Access Journals (Sweden)

    Samah F. Darwish

    2013-01-01

    Full Text Available A total of 40 S. aureus and 68 coagulase negative Staphylococcus (CNS isolates from bovine subclinical mastitis were investigated for their ability to form biofilm as one of the most important virulence factors.Using Congo Red Agar (CRA method, 32.5%, 35%, and 32.5% of S. aureus strains were strong, intermediate, and negative biofilm producers, while in CNS the percentages were 29.5%, 42.6%, and 27.9%, respectively. By microtiter plate (MTP method, 52.5%, 27.5%, and 20% of S. aureus isolates were strong, moderate, and weak biofilm producers, while in CNS the percentages were 44%, 30.9%, and 19.2%, respectively. Indian ink staining was used to detect the EPS layer of biofilm producers. All isolates were screened for presence of biofilm related genes, eno, icaA, icaD, and bap. In S. aureus isolates, the positive rates of eno, icaA, icaD, and bap genes were 75%, 15%, 62.5%, and 2.5% while in CNS were 92.6%, 5.9%, 47.1%, and 4.4%, respectively. The eno gene had the highest rate while the bap gene had the lowest rate. Presence of icaA and icaD genes was not always correlated with biofilm production. This study demonstrated high prevalence of Staphylococcus biofilm producers among bovine mastitis in Egypt. Therefore, attention must be paid toward implementation of new ways for effective treatment of such infections.

  4. Glass forming tendencies of chalcogenides of the system (As2Se3)sub(1-x):(T12Se)sub(x)

    International Nuclear Information System (INIS)

    Majid, C.A.

    1982-07-01

    In this paper glass forming capabilities of chalcogenide glasses based on As 2 Se 3 with T1 2 Se concentrations are discussed. The studies were made using the differential thermal analysis (DTA) technique. These studies show that the glass forming tendency of As 2 Se 3 decreases as the concentrations of T1 2 Se molecules are increased. Also these studies show that with addition of T1 2 Se, the glass transition temperature Tsub(g) of As 2 Se 3 decreases, suggesting a tendency for weaker bonding and hence less stability of T1-rich compositions. (author)

  5. Structural evolution during fragile-to-strong transition in CuZr(Al) glass-forming liquids

    DEFF Research Database (Denmark)

    Zhou, C.; Hu, L.N.; Sun, Q.J.

    2015-01-01

    In the present work, we show experimental evidence for the dynamic fragile-to-strong (F-S) transition in a series of CuZr(Al) glass-forming liquids (GFLs). A detailed analysis of the dynamics of 98 glass-forming liquids indicates that the F-S transition occurs around Tf-s ≈ 1.36 Tg. Using...... the hyperquenching-annealing-x-ray scattering approach, we have observed a three-stage evolution pattern of medium-range ordering (MRO) structures during the F-S transition, indicating a dramatic change of the MRO clusters around Tf-s upon cooling. The F-S transition in CuZr(Al) GFLs is attributed to the competition...... among the MRO clusters composed of different locally ordering configurations. A phenomenological scenario has been proposed to explain the structural evolution from the fragile to the strong phase in the CuZr(Al) GFLs....

  6. Validation of an Adapted French Form of the Career Adapt-Abilities Scale in Four Francophone Countries

    Science.gov (United States)

    Johnston, Claire S.; Broonen, Jean-Paul; Stauffer, Sarah D.; Hamtiaux, Armanda; Pouyaud, Jacques; Zecca, Gregory; Houssemand, Claude; Rossier, Jerome

    2013-01-01

    This study presents the validation of a French version of the Career Adapt-Abilities Scale in four Francophone countries. The aim was to re-analyze the item selection and then compare this newly developed French-language form with the international form 2.0. Exploratory factor analysis was used as a tool for item selection, and confirmatory factor…

  7. Microstructural Control via Copious Nucleation Manipulated by In Situ Formed Nucleants: Large-Sized and Ductile Metallic Glass Composites.

    Science.gov (United States)

    Song, Wenli; Wu, Yuan; Wang, Hui; Liu, Xiongjun; Chen, Houwen; Guo, Zhenxi; Lu, Zhaoping

    2016-10-01

    A novel strategy to control the precipitation behavior of the austenitic phase, and to obtain large-sized, transformation-induced, plasticity-reinforced bulk metallic glass matrix composites, with good tensile properties, is proposed. By inducing heterogeneous nucleation of the transformable reinforcement via potent nucleants formed in situ, the characteristics of the austenitic phase are well manipulated. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Coercivity of the Nd–Fe–B hot-deformed magnets diffusion-processed with low melting temperature glass forming alloys

    Energy Technology Data Exchange (ETDEWEB)

    Seelam, U.M.R. [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Liu, Lihua [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan); Akiya, T.; Sepehri-Amin, H.; Ohkubo, T. [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Sakuma, N.; Yano, M.; Kato, A. [Advanced Material Engineering Division, Toyota Motor Corporation, Susono 410-1193 (Japan); Hono, K., E-mail: kazuhiro.hono@nims.go.jp [Elements Strategy Initiative Center for Magnetic Materials (ESICMM), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571 (Japan)

    2016-08-15

    Nd- and Pr-based alloys with bulk glass forming ability and low melting temperatures, Nd{sub 60}Al{sub 10}Ni{sub 10}Cu{sub 20} and Pr{sub 60}Al{sub 10}Ni{sub 10}Cu{sub 20}, were used for grain boundary diffusion process to enhance the coercivity of hot-deformed magnets. The coercivity increment was proportional to the weight gain after the diffusion process. For the sample with 64% weight gain, the coercivity increased up to 2.8 T, which is the highest value for bulk Nd–Fe–B magnets that do not contain heavy rare-earth elements, Dy or Tb. Approximately half of the intergranular regions were amorphous and the remaining regions were crystalline. Magnetic isolation of the Nd{sub 2}Fe{sub 14}B grains by the Nd-rich amorphous/crystalline intergranular phases is attributed to the large coercivity enhancement. The coercivity does not change after the crystallization of the intergranular phase, indicating that the coercivity is not influenced by the strain at the interface with the crystalline intergranular phase. - Highlights: • Bulk-glass forming alloys were infiltrated into hot-deformed Nd–Fe–B magnets. • Very high coercivity of 2.8 T was attained without heavy rare-earth elements. • Approximately half of the inter-granular regions were amorphous. • Crystallization of amorphous intergranular phase does not change coercivity.

  9. Preparation of glass-forming materials from granulated blast furnace slag

    Science.gov (United States)

    Alonso, M.; Sáinz, E.; Lopez, F. A.

    1996-10-01

    Glass precursor materials, to be used for the vitrification of hazardous wastes, have been prepared from blast furnace slag powder through a sol-gel route. The slag is initially reacted with a mixture of alcohol (ethanol or methanol) and mineral acid (HNO3 or H2SO4) to give a sol principally consisting of Si, Ca, Al, and Mg alkoxides. Gelation is carried out with variable amounts of either ammonia or water. The gelation rate can be made as fast as desired by adding excess hydrolizing agent or else by distilling the excess alcohol out of the alkoxide solution. The resulting gel is first dried at low temperature and ground. The powder thus obtained is then heat treated at several temperatures. The intermediate and final materials are characterized by thermal analysis, infrared (IR) spectroscopy, X-ray diffraction, scanning electron microscopy (SEM), and chemical analysis. From the results, the operating conditions yielding a variety of glass precursors differing in their composition are established. The method, in comparison with direct vitrification of slag, presents a number of advantages: (1) the glass precursor obtained devitrifies at higher temperatures; (2) it enables the adjustment, to a certain extent, of the chemical composition of the glass precursor; and (3) it permits recovering marketable materials at different stages of the process.

  10. Potential energy landscape signatures of slow dynamics in glass forming liquids

    DEFF Research Database (Denmark)

    Sastry, S.; Debenedetti, P. G.; Stillinger, F. H.

    1999-01-01

    We study the properties of local potential energy minima (‘inherent structures’) sampled by liquids at low temperatures as an approach to elucidating the mechanisms of the observed dynamical slowing down observed as the glass transition temperature is approached. This onset of slow dynamics...

  11. Volume and enthalpy recovery of glass-forming polymers and the predictions controlled by internal energy

    Czech Academy of Sciences Publication Activity Database

    Říha, Pavel; Slobodian, P.; Kubát, J.

    2009-01-01

    Roč. 54, č. 1 (2009), s. 59-71 ISSN 0001-7043 R&D Projects: GA AV ČR IAA200600803 Institutional research plan: CEZ:AV0Z20600510 Keywords : a-PMMA * Glass transition * Aging * Cooperative relaxation model Subject RIV: BK - Fluid Dynamics

  12. Enhanced 99 Tc retention in glass waste form using Tc(IV)-incorporated Fe minerals

    Energy Technology Data Exchange (ETDEWEB)

    Um, Wooyong; Luksic, Steven A.; Wang, Guohui; Saslow, Sarah; Kim, Dong-Sang; Schweiger, Michael J.; Soderquist, Chuck Z.; Bowden, Mark E.; Lukens, Wayne W.; Kruger, Albert A.

    2017-11-01

    Technetium (99Tc) immobilization by doping into iron oxide mineral phases may alleviate the problems with Tc volatility during vitrification of nuclear waste. Reduced Tc, Tc(IV), substitutes for Fe(III) in the crystal structure by a process of Tc reduction from Tc(VII) to Tc(IV) followed by co-precipitation of Fe oxide minerals. Two Tc-incorporated Fe minerals (Tc-goethite and Tc-magnetite/maghemite) were prepared and tested for Tc retention in glass melt samples at temperatures between 600 – 1,000 oC. After being cooled, the solid glass specimens prepared at different temperatures were analyzed for Tc oxidation state using Tc K-edge XANES. In most samples, Tc was partially oxidized from Tc(IV) to Tc(VII) as the melt temperature increased. However, Tc retention in glass melt samples prepared using Tc-incorporated Fe minerals were moderately higher than in glass prepared using KTcO4 because of limited and delayed Tc volatilization.

  13. Enhanced apatite-forming ability and antibacterial activity of porous anodic alumina embedded with CaO-SiO2-Ag2O bioactive materials.

    Science.gov (United States)

    Ni, Siyu; Li, Xiaohong; Yang, Pengan; Ni, Shirong; Hong, Feng; Webster, Thomas J

    2016-01-01

    In this study, to provide porous anodic alumina (PAA) with bioactivity and anti-bacterial properties, sol-gel derived bioactive CaO-SiO2-Ag2O materials were loaded onto and into PAA nano-pores (termed CaO-SiO2-Ag2O/PAA) by a sol-dipping method and subsequent calcination of the gel-glasses. The in vitro apatite-forming ability of the CaO-SiO2-Ag2O/PAA specimens was evaluated by soaking them in simulated body fluid (SBF). The surface microstructure and chemical property before and after soaking in SBF were characterized. Release of ions into the SBF was also measured. In addition, the antibacterial properties of the samples were tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The results showed that CaO-SiO2-Ag2O bioactive materials were successfully decorated onto and into PAA nano-pores. In vitro SBF experiments revealed that the CaO-SiO2-Ag2O/PAA specimens dramatically enhanced the apatite-forming ability of PAA in SBF and Ca, Si and Ag ions were released from the samples in a sustained and slow manner. Importantly, E. coli and S. aureus were both killed on the CaO-SiO2-Ag2O/PAA (by 100%) samples compared to PAA controls after 3 days of culture. In summary, this study demonstrated that the CaO-SiO2-Ag2O/PAA samples possess good apatite-forming ability and high antibacterial activity causing it to be a promising bioactive coating candidate for implant materials for orthopedic applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Thermomechanical and calorimetric behaviours of supported glass-forming films: A study based on thermodynamics with internal variables

    International Nuclear Information System (INIS)

    Lion, Alexander; Engelhard, Marco; Johlitz, Michael

    2012-01-01

    In order to understand the temperature-dependent response behaviour of thin thermoviscoelastic films which are deposited on relative stiff but thermally deformable substrates it is important to consider the lateral geometric constraints. They are generated by differences in the thermal expansion properties between the substrate and the film and provoke internal stresses. Since glass-forming materials exhibit distinct temperature history-dependent thermal expansion and calorimetric properties, primarily in the vicinity of the glass transition, the situation is rather complicated. In this article, a recently developed three-dimensional model of thermodynamics with internal variables is applied and adapted to simulate this type of behaviour. Explicit relations are obtained for the specific heat of the film, the normal strain and the lateral stresses. Numerical simulations demonstrate that the magnitude of the internal stress at temperatures below the glass transition depends strongly on the cooling rate. It is also shown that the specific heat of the supported film is principally different from the isobaric specific heat of the bulk material: the glassy limit of the specific heat of the film is reduced but the glass transition temperature is almost uninfluenced. The simulated behaviour is in accordance with experimental observations from literature. - Highlights: ► For the specific heat, stress and strain of the film, explicit equations were derived. ► The constraints of the substrate reduce the glassy limit of specific heat of the film. ► Glass transition temperatures of free bulk material and supported film are equal. ► Simulations are in good agreement with experimental observations from literature.

  15. Thermomechanical and calorimetric behaviours of supported glass-forming films: A study based on thermodynamics with internal variables

    Energy Technology Data Exchange (ETDEWEB)

    Lion, Alexander, E-mail: alexander.lion@unibw.de; Engelhard, Marco; Johlitz, Michael

    2012-11-01

    In order to understand the temperature-dependent response behaviour of thin thermoviscoelastic films which are deposited on relative stiff but thermally deformable substrates it is important to consider the lateral geometric constraints. They are generated by differences in the thermal expansion properties between the substrate and the film and provoke internal stresses. Since glass-forming materials exhibit distinct temperature history-dependent thermal expansion and calorimetric properties, primarily in the vicinity of the glass transition, the situation is rather complicated. In this article, a recently developed three-dimensional model of thermodynamics with internal variables is applied and adapted to simulate this type of behaviour. Explicit relations are obtained for the specific heat of the film, the normal strain and the lateral stresses. Numerical simulations demonstrate that the magnitude of the internal stress at temperatures below the glass transition depends strongly on the cooling rate. It is also shown that the specific heat of the supported film is principally different from the isobaric specific heat of the bulk material: the glassy limit of the specific heat of the film is reduced but the glass transition temperature is almost uninfluenced. The simulated behaviour is in accordance with experimental observations from literature. - Highlights: Black-Right-Pointing-Pointer For the specific heat, stress and strain of the film, explicit equations were derived. Black-Right-Pointing-Pointer The constraints of the substrate reduce the glassy limit of specific heat of the film. Black-Right-Pointing-Pointer Glass transition temperatures of free bulk material and supported film are equal. Black-Right-Pointing-Pointer Simulations are in good agreement with experimental observations from literature.

  16. Experimental evidence for excess entropy discontinuities in glass-forming solutions.

    Science.gov (United States)

    Lienhard, Daniel M; Zobrist, Bernhard; Zuend, Andreas; Krieger, Ulrich K; Peter, Thomas

    2012-02-21

    Glass transition temperatures T(g) are investigated in aqueous binary and multi-component solutions consisting of citric acid, calcium nitrate (Ca(NO(3))(2)), malonic acid, raffinose, and ammonium bisulfate (NH(4)HSO(4)) using a differential scanning calorimeter. Based on measured glass transition temperatures of binary aqueous mixtures and fitted binary coefficients, the T(g) of multi-component systems can be predicted using mixing rules. However, the experimentally observed T(g) in multi-component solutions show considerable deviations from two theoretical approaches considered. The deviations from these predictions are explained in terms of the molar excess mixing entropy difference between the supercooled liquid and glassy state at T(g). The multi-component mixtures involve contributions to these excess mixing entropies that the mixing rules do not take into account. © 2012 American Institute of Physics

  17. Entropic vs. elastic models of fragility of glass-forming liquids: Two sides of the same coin?

    Science.gov (United States)

    Sen, Sabyasachi

    2012-10-01

    The two most influential atomistic models that have been proposed in the literature to explain the temperature dependent activation energy of viscous flow of a glass-forming liquid, i.e., its fragility, are the configurational entropy model of Adam and Gibbs [J. Chem. Phys. 43, 139 (1965), 10.1063/1.1696442] and the elastic "shoving" model of Dyre et al. [J. Non-Cryst. Solids 352, 4635 (2006), 10.1016/j.jnoncrysol.2006.02.173]. Here we demonstrate a qualitative equivalence between these two models starting from the well-established general relationships between the interatomic potentials, elastic constants, structural rearrangement, and entropy in amorphous materials. The unification of these two models provides important predictions that are consistent with experimental observations and shed new light into the problem of glass transition.

  18. Optical and morphological characterizations of pyronin dye-poly (vinyl alcohol) thin films formed on glass substrates

    International Nuclear Information System (INIS)

    Meral, Kadem; Arik, Mustafa; Onganer, Yavuz

    2016-01-01

    Thin films of pyronin dye mixed with poly(vinyl alcohol) (PVA) on glass substrate were prepared by using spin-coating technique. The optical and morphological properties of the thin films were studied by UV-Vis., steady-state fluorescence spectroscopies and atomic force microscopy (AFM). The thin films on glass substrate were fabricated at various [PVA]/[dye] (P/D) ratios. Hence, the monomeric and H-aggregates thin films of pyronin dye mixed with PVA were formed as a function of the dye and PVA concentration. It was determined that while the monomeric thin films showed strong fluorescence, the formation of H-aggregates in the thin film caused to decreasing the fluorescence intensity. AFM studies demonstrated that the morphology of the thin film was drastically varied with changing the optical property of the thin film such as monomeric and H-aggregates thin films.

  19. Optical and morphological characterizations of pyronin dye-poly (vinyl alcohol) thin films formed on glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Meral, Kadem, E-mail: kademm@atauni.edu.tr; Arik, Mustafa, E-mail: marik@tatauni.edu.tr; Onganer, Yavuz, E-mail: yonganer@atauni.edu.tr [Department of Chemistry, Faculty of Sciences, Atatürk University, 25240 Erzurum (Turkey)

    2016-04-18

    Thin films of pyronin dye mixed with poly(vinyl alcohol) (PVA) on glass substrate were prepared by using spin-coating technique. The optical and morphological properties of the thin films were studied by UV-Vis., steady-state fluorescence spectroscopies and atomic force microscopy (AFM). The thin films on glass substrate were fabricated at various [PVA]/[dye] (P/D) ratios. Hence, the monomeric and H-aggregates thin films of pyronin dye mixed with PVA were formed as a function of the dye and PVA concentration. It was determined that while the monomeric thin films showed strong fluorescence, the formation of H-aggregates in the thin film caused to decreasing the fluorescence intensity. AFM studies demonstrated that the morphology of the thin film was drastically varied with changing the optical property of the thin film such as monomeric and H-aggregates thin films.

  20. Conventional methods fail to measure cp(omega) of glass-forming liquids

    DEFF Research Database (Denmark)

    Christensen, Tage Emil; Olsen, Niels Boye; Dyre, Jeppe

    2007-01-01

    thermal-wave method does not measure the isobaric frequency-dependent specific heat cp(omega). This method rather measures a "longitudinal" frequency-dependent specific heat, a quantity defined and detailed here that is in between cp(omega) and cV(omega). This result means that no reliable wide......-frequency measurements of cp(omega) on liquids approaching the calorimetric glass transition exist. We briefly discuss consequences for experiment....

  1. Magnetic nanoparticles formed in glasses co-doped with iron and larger radius elements

    Energy Technology Data Exchange (ETDEWEB)

    Edelman, I.; Ivanova, O.; Ivantsov, R.; Velikanov, D.; Zabluda, V. [L.V. Kirensky Institute of Physics SB RAS, 660036 Krasnoyarsk (Russian Federation); Zubavichus, Y.; Veligzhanin, A. [NRC ' Kurchatov Institute,' 123182 Moscow (Russian Federation); Zaikovskiy, V. [Boreskov Institute of Catalysis, Siberian Branch of RAS, 630090 Novosibirsk (Russian Federation); Stepanov, S. [S.I. Vavilov State Optical Institute, St. Petersburg (Russian Federation); Artemenko, A. [ICMCB, UPR CNRS 9048, 33608 Pessac cedex (France); Curely, J.; Kliava, J. [LOMA, UMR 5798 Universite Bordeaux 1-CNRS, 33405 Talence cedex (France)

    2012-10-15

    A new type of nanoparticle-containing glasses based on borate glasses co-doped with low contents of iron and larger radius elements, Dy, Tb, Gd, Ho, Er, Y, and Bi, is studied. Heat treatment of these glasses results in formation of magnetic nanoparticles, radically changing their physical properties. Transmission electron microscopy and synchrotron radiation-based techniques: x-ray diffraction, extended x-ray absorption fine structure, x-ray absorption near-edge structure, and small-angle x-ray scattering, show a broad distribution of nanoparticle sizes with characteristics depending on the treatment regime; a crystalline structure of these nanoparticles is detected in heat treated samples. Magnetic circular dichroism (MCD) studies of samples subjected to heat treatment as well as of maghemite, magnetite, and iron garnet allow to unambiguously assign the nanoparticle structure to maghemite, independently of co-dopant nature and of heat treatment regime used. Different features observed in the MCD spectra are related to different electron transitions in Fe{sup 3+} ions gathered in the nanoparticles. The static magnetization in heat treated samples has non-linear dependence on the magnetizing field with hysteresis. Zero-field cooled magnetization curves show that at higher temperatures the nanoparticles occur in superparamagnetic state with blocking temperatures above 100 K. Below ca. 20 K, a considerable contribution to both zero field-cooled and field-cooled magnetizations occurs from diluted paramagnetic ions. Variable-temperature electron magnetic resonance (EMR) studies unambiguously show that in as-prepared glasses paramagnetic ions are in diluted state and confirm the formation of magnetic nanoparticles already at earlier stages of heat treatment. Computer simulations of the EMR spectra corroborate the broad distribution of nanoparticle sizes found by 'direct' techniques as well as superparamagnetic nanoparticle behaviour demonstrated in the

  2. Magnetic nanoparticles formed in glasses co-doped with iron and larger radius elements

    International Nuclear Information System (INIS)

    Edelman, I.; Ivanova, O.; Ivantsov, R.; Velikanov, D.; Zabluda, V.; Zubavichus, Y.; Veligzhanin, A.; Zaikovskiy, V.; Stepanov, S.; Artemenko, A.; Curély, J.; Kliava, J.

    2012-01-01

    A new type of nanoparticle-containing glasses based on borate glasses co-doped with low contents of iron and larger radius elements, Dy, Tb, Gd, Ho, Er, Y, and Bi, is studied. Heat treatment of these glasses results in formation of magnetic nanoparticles, radically changing their physical properties. Transmission electron microscopy and synchrotron radiation-based techniques: x-ray diffraction, extended x-ray absorption fine structure, x-ray absorption near-edge structure, and small-angle x-ray scattering, show a broad distribution of nanoparticle sizes with characteristics depending on the treatment regime; a crystalline structure of these nanoparticles is detected in heat treated samples. Magnetic circular dichroism (MCD) studies of samples subjected to heat treatment as well as of maghemite, magnetite, and iron garnet allow to unambiguously assign the nanoparticle structure to maghemite, independently of co-dopant nature and of heat treatment regime used. Different features observed in the MCD spectra are related to different electron transitions in Fe 3+ ions gathered in the nanoparticles. The static magnetization in heat treated samples has non-linear dependence on the magnetizing field with hysteresis. Zero-field cooled magnetization curves show that at higher temperatures the nanoparticles occur in superparamagnetic state with blocking temperatures above 100 K. Below ca. 20 K, a considerable contribution to both zero field-cooled and field-cooled magnetizations occurs from diluted paramagnetic ions. Variable-temperature electron magnetic resonance (EMR) studies unambiguously show that in as-prepared glasses paramagnetic ions are in diluted state and confirm the formation of magnetic nanoparticles already at earlier stages of heat treatment. Computer simulations of the EMR spectra corroborate the broad distribution of nanoparticle sizes found by “direct” techniques as well as superparamagnetic nanoparticle behaviour demonstrated in the magnetization

  3. Magnetic nanoparticles formed in glasses co-doped with iron and larger radius elements

    Science.gov (United States)

    Edelman, I.; Ivanova, O.; Ivantsov, R.; Velikanov, D.; Zabluda, V.; Zubavichus, Y.; Veligzhanin, A.; Zaikovskiy, V.; Stepanov, S.; Artemenko, A.; Curély, J.; Kliava, J.

    2012-10-01

    A new type of nanoparticle-containing glasses based on borate glasses co-doped with low contents of iron and larger radius elements, Dy, Tb, Gd, Ho, Er, Y, and Bi, is studied. Heat treatment of these glasses results in formation of magnetic nanoparticles, radically changing their physical properties. Transmission electron microscopy and synchrotron radiation-based techniques: x-ray diffraction, extended x-ray absorption fine structure, x-ray absorption near-edge structure, and small-angle x-ray scattering, show a broad distribution of nanoparticle sizes with characteristics depending on the treatment regime; a crystalline structure of these nanoparticles is detected in heat treated samples. Magnetic circular dichroism (MCD) studies of samples subjected to heat treatment as well as of maghemite, magnetite, and iron garnet allow to unambiguously assign the nanoparticle structure to maghemite, independently of co-dopant nature and of heat treatment regime used. Different features observed in the MCD spectra are related to different electron transitions in Fe3+ ions gathered in the nanoparticles. The static magnetization in heat treated samples has non-linear dependence on the magnetizing field with hysteresis. Zero-field cooled magnetization curves show that at higher temperatures the nanoparticles occur in superparamagnetic state with blocking temperatures above 100 K. Below ca. 20 K, a considerable contribution to both zero field-cooled and field-cooled magnetizations occurs from diluted paramagnetic ions. Variable-temperature electron magnetic resonance (EMR) studies unambiguously show that in as-prepared glasses paramagnetic ions are in diluted state and confirm the formation of magnetic nanoparticles already at earlier stages of heat treatment. Computer simulations of the EMR spectra corroborate the broad distribution of nanoparticle sizes found by "direct" techniques as well as superparamagnetic nanoparticle behaviour demonstrated in the magnetization studies.

  4. Changing the Tendency of Glass-Forming Liquid To Crystallize by Moving Along Different Isolines in the T-p Phase Diagram

    DEFF Research Database (Denmark)

    Adrjanowicz, Karolina; Koperwas, Kajetan; Tarnacka, Magdalena

    2016-01-01

    Controlling crystallization and glass-forming tendencies of molecular liquids is of great scientific and practical importance. In the present work, we show that a lot can be learned regarding this process by introducing temperature and pressure as thermodynamic control variables. For the glass...

  5. Aging of the Johari-Goldstein relaxation in the glass-forming liquids sorbitol and xylitol

    Science.gov (United States)

    Yardimci, Hasan; Leheny, Robert L.

    2006-06-01

    Employing frequency-dependent dielectric susceptibility we characterize the aging in two supercooled liquids, sorbitol and xylitol, below their calorimetric glass transition temperatures. In addition to the alpha relaxation that tracks the structural dynamics, the susceptibility of both liquids possesses a secondary Johari-Goldstein relaxation at higher frequencies. Following a quench through the glass transition, the susceptibility slowly approaches the equilibrium behavior. For both liquids, the magnitude of the Johari-Goldstein relaxation displays a dependence on the time since the quench, or aging time, that is quantitatively very similar to the age dependence of the alpha peak frequency. The Johari-Goldstein relaxation time remains constant during aging for sorbitol while it decreases slightly with age for xylitol. Hence, one cannot sensibly assign a fictive temperature to the Johari-Goldstein relaxation. This behavior contrasts with that of liquids lacking distinct Johari-Goldstein peaks for which the excess wing of the alpha peak tracks the main part of the peak during aging, enabling the assignment of a single fictive temperature to the entire spectrum. The aging behavior of the Johari-Goldstein relaxation time further calls into question the possibility that the relaxation time possesses stronger temperature dependence in equilibrium than is observed in the out-of-equilibrium state below the glass transition.

  6. Local dynamics of glass-forming polystyrene thin films from atomistic simulation

    Science.gov (United States)

    Zhou, Yuxing; Milner, Scott

    Despite a wide technological application ranging from protective coatings to organic solar cells, there still no consensus on the mechanism for the glass transition in polymer thin films a manifestation of the infamous glass problem under confinement. Many experimental and computational studies have observed a large deviation of nanoscale dynamical properties in thin films from the corresponding properties in bulk. In this work, we perform extensive united-atom simulations on atactic polystyrene free-standing thin films near the glass transition temperature and focus on the effect of free surface on the local dynamics. We study the segmental dynamics as a function of distance from the surface for different temperatures, from which relaxation time and thereby local Tg is obtained for each layer. We find the dynamics near free surface is not only enhanced but becomes less strongly temperature dependent as Tg is approached compared to the bulk. We find an increasing length scale associated with mobility propagation from the free surface as temperature decreases, but no correlation between local structure and enhanced relaxation rates near the surface, consistent with studies on bead-spring chains.

  7. Physiological integration affects growth form and competitive ability in clonal plants

    Czech Academy of Sciences Publication Activity Database

    Herben, Tomáš

    2004-01-01

    Roč. 18, - (2004), s. 493-520 ISSN 0269-7653 R&D Projects: GA ČR(CZ) GA206/02/0953 Institutional research plan: CEZ:AV0Z6005908 Keywords : competitive ability * Physiological integration * clonal plants Subject RIV: EF - Botanics Impact factor: 3.215, year: 2004

  8. Density-driven structural transformations in network forming glasses: a high-pressure neutron diffraction study of GeO2 glass up to 17.5 GPa

    International Nuclear Information System (INIS)

    Salmon, Philip S; Drewitt, James W E; Whittaker, Dean A J; Zeidler, Anita; Wezka, Kamil; Bull, Craig L; Tucker, Matthew G; Wilding, Martin C; Guthrie, Malcolm; Marrocchelli, Dario

    2012-01-01

    The structure of GeO 2 glass was investigated at pressures up to 17.5(5) GPa using in situ time-of-flight neutron diffraction with a Paris-Edinburgh press employing sintered diamond anvils. A new methodology and data correction procedure were developed, enabling a reliable measurement of structure factors that are largely free from diamond Bragg peaks. Calibration curves, which are important for neutron diffraction work on disordered materials, were constructed for pressure as a function of applied load for both single and double toroid anvil geometries. The diffraction data are compared to new molecular-dynamics simulations made using transferrable interaction potentials that include dipole-polarization effects. The results, when taken together with those from other experimental methods, are consistent with four densification mechanisms. The first, at pressures up to ≃ 5 GPa, is associated with a reorganization of GeO 4 units. The second, extending over the range from ≃ 5 to 10 GPa, corresponds to a regime where GeO 4 units are replaced predominantly by GeO 5 units. In the third, as the pressure increases beyond ∼10 GPa, appreciable concentrations of GeO 6 units begin to form and there is a decrease in the rate of change of the intermediate-range order as measured by the pressure dependence of the position of the first sharp diffraction peak. In the fourth, at about 30 GPa, the transformation to a predominantly octahedral glass is achieved and further densification proceeds via compression of the Ge-O bonds. The observed changes in the measured diffraction patterns for GeO 2 occur at similar dimensionless number densities to those found for SiO 2 , indicating similar densification mechanisms for both glasses. This implies a regime from about 15 to 24 GPa where SiO 4 units are replaced predominantly by SiO 5 units, and a regime beyond ∼24 GPa where appreciable concentrations of SiO 6 units begin to form.

  9. Formation of Ti--Zr--Cu--Ni bulk metallic glasses

    International Nuclear Information System (INIS)

    Lin, X.H.; Johnson, W.L.

    1995-01-01

    Formation of bulk metallic glass in quaternary Ti--Zr--Cu--Ni alloys by relatively slow cooling from the melt is reported. Thick strips of metallic glass were obtained by the method of metal mold casting. The glass forming ability of the quaternary alloys exceeds that of binary or ternary alloys containing the same elements due to the complexity of the system. The best glass forming alloys such as Ti 34 Zr 11 Cu 47 Ni 8 can be cast to at least 4-mm-thick amorphous strips. The critical cooling rate for glass formation is of the order of 250 K/s or less, at least two orders of magnitude lower than that of the best ternary alloys. The glass transition, crystallization, and melting behavior of the alloys were studied by differential scanning calorimetry. The amorphous alloys exhibit a significant undercooled liquid region between the glass transition and first crystallization event. The glass forming ability of these alloys, as determined by the critical cooling rate, exceeds what is expected based on the reduced glass transition temperature. It is also found that the glass forming ability for alloys of similar reduced glass transition temperature can differ by two orders of magnitude as defined by critical cooling rates. The origins of the difference in glass forming ability of the alloys are discussed. It is found that when large composition redistribution accompanies crystallization, glass formation is enhanced. The excellent glass forming ability of alloys such as Ti 34 Zr 11 Cu 47 Ni 8 is a result of simultaneously minimizing the nucleation rate of the competing crystalline phases. The ternary/quaternary Laves phase (MgZn 2 type) shows the greatest ease of nucleation and plays a key role in determining the optimum compositions for glass formation. copyright 1995 American Institute of Physics

  10. Developmental Abilities to Form Chunks in Immediate Memory and its Non-Relationship to Span Development

    Directory of Open Access Journals (Sweden)

    Fabien eMathy

    2016-02-01

    Full Text Available Both adults and children --by the time they are two to three years old-- have a general ability to recode information to increase memory efficiency. This paper aims to evaluate the ability of untrained children aged six to ten years old to deploy such a recoding process in immediate memory. A large sample of 374 children were given a task of immediate serial report based on SIMON, a classic memory game made of four colored buttons (red, green, yellow, blue requiring players to reproduce a sequence of colors within which repetitions eventually occur. It was hypothesized that a primitive ability across all ages (since theoretically already available in toddlers to detect redundancies allows the span to increase whenever information can be recoded on the fly. The chunkable condition prompted the formation of chunks based on the perceived structure of color repetition within to-be-recalled sequences of colors. Our result shows a similar linear improvement of memory span with age for both chunkable and non-chunkable conditions. The amount of information retained in immediate memory systematically increased for the groupable sequences across all age groups, independently of the average age-group span that was measured on sequences that contained fewer repetitions. This result shows that chunking gives young children an equal benefit as older children. We discuss the role of recoding in the expansion of capacity in immediate memory and the potential role of data compression in the formation of chunks in long-term memory.

  11. Developmental Abilities to Form Chunks in Immediate Memory and Its Non-Relationship to Span Development.

    Science.gov (United States)

    Mathy, Fabien; Fartoukh, Michael; Gauvrit, Nicolas; Guida, Alessandro

    2016-01-01

    Both adults and children -by the time they are 2-3 years old- have a general ability to recode information to increase memory efficiency. This paper aims to evaluate the ability of untrained children aged 6-10 years old to deploy such a recoding process in immediate memory. A large sample of 374 children were given a task of immediate serial report based on SIMON®, a classic memory game made of four colored buttons (red, green, yellow, blue) requiring players to reproduce a sequence of colors within which repetitions eventually occur. It was hypothesized that a primitive ability across all ages (since theoretically already available in toddlers) to detect redundancies allows the span to increase whenever information can be recoded on the fly. The chunkable condition prompted the formation of chunks based on the perceived structure of color repetition within to-be-recalled sequences of colors. Our result shows a similar linear improvement of memory span with age for both chunkable and non-chunkable conditions. The amount of information retained in immediate memory systematically increased for the groupable sequences across all age groups, independently of the average age-group span that was measured on sequences that contained fewer repetitions. This result shows that chunking gives young children an equal benefit as older children. We discuss the role of recoding in the expansion of capacity in immediate memory and the potential role of data compression in the formation of chunks in long-term memory.

  12. Ability of nitrones of various structures to control the radical polymerization of styrene mediated by in situ formed nitroxides.

    NARCIS (Netherlands)

    Sciannamea, V.; Guerrero-Sanchez, C.A.; Schubert, U.S.; Catala, J.-M.; Jerome, R.; Detrembleur, C.

    2005-01-01

    The ability of several nitrones to control the radical polymerization of styrene at 110 °C has been investigated by high-throughput experimentation. The nitrone/free radical initiator pair dictates the structure of the nitroxide and the alkoxyamine formed in situ, which determines the position of

  13. Iron phosphate glass containing simulated fast reactor waste: Characterization and comparison with pristine iron phosphate glass

    International Nuclear Information System (INIS)

    Joseph, Kitheri; Asuvathraman, R.; Venkata Krishnan, R.; Ravindran, T.R.; Govindaraj, R.; Govindan Kutty, K.V.; Vasudeva Rao, P.R.

    2014-01-01

    Detailed characterization was carried out on an iron phosphate glass waste form containing 20 wt.% of a simulated nuclear waste. High temperature viscosity measurement was carried out by the rotating spindle method. The Fe 3+ /Fe ratio and structure of this waste loaded iron phosphate glass was investigated using Mössbauer and Raman spectroscopy respectively. Specific heat measurement was carried out in the temperature range of 300–700 K using differential scanning calorimeter. Isoconversional kinetic analysis was employed to understand the crystallization behavior of the waste loaded iron phosphate glass. The glass forming ability and glass stability of the waste loaded glass were also evaluated. All the measured properties of the waste loaded glass were compared with the characteristics of pristine iron phosphate glass

  14. Apatite and sodalite based glass-bonded waste forms for immobilization of 129I and mixed halide radioactive wastes

    Energy Technology Data Exchange (ETDEWEB)

    Goel, Ashutosh [Rutgers Univ., New Brunswick, NJ (United States); McCloy, John S. [Washington State Univ., Pullman, WA (United States); Riley, Brian J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Matyas, Josef [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-12-30

    The goal of the project was to utilize the knowledge accumulated by the team, in working with minerals for chloride wastes and biological apatites, toward the development of advanced waste forms for immobilizing 129I and mixed-halide wastes. Based on our knowledge, experience, and thorough literature review, we had selected two minerals with different crystal structures and potential for high chemical durability, sodalite and CaP/PbV-apatite, to form the basis of this project. The focus of the proposed effort was towards: (i) low temperature synthesis of proposed minerals (iodine containing sodalite and apatite) leading to the development of monolithic waste forms, (ii) development of a fundamental understanding of the atomic-scale to meso-scale mechanisms of radionuclide incorporation in them, and (iii) understanding of the mechanism of their chemical corrosion, alteration mechanism, and rates. The proposed work was divided into four broad sections. deliverables. 1. Synthesis of materials 2. Materials structural and thermal characterization 3. Design of glass compositions and synthesis glass-bonded minerals, and 4. Chemical durability testing of materials.

  15. Dynamical, structural and chemical heterogeneities in a binary metallic glass-forming liquid

    Science.gov (United States)

    Puosi, F.; Jakse, N.; Pasturel, A.

    2018-04-01

    As it approaches the glass transition, particle motion in liquids becomes highly heterogeneous and regions with virtually no mobility coexist with liquid-like domains. This complex dynamic is believed to be responsible for different phenomena including non-exponential relaxation and the breakdown of the Stokes-Einstein relation. Understanding the relationships between dynamical heterogeneities and local structure in metallic liquids and glasses is a major scientific challenge. Here we use classical molecular dynamics simulations to study the atomic dynamics and microscopic structure of Cu50Zr50 alloy in the supercooling regime. Dynamical heterogeneities are identified via an isoconfigurational analysis. We demonstrate the transition from isolated to clustering low mobility with decreasing temperature. These slow clusters, whose sizes grow upon cooling, are also associated with concentration fluctuations, characterized by a Zr-enriched phase, with a composition CuZr2 . In addition, a structural analysis of slow clusters based on Voronoi tessellation evidences an increase with respect of the bulk system of the fraction of Cu atoms having a local icosahedral order. These results are in agreement with the consolidated scenario of the relevant role played by icosahedral order in the dynamic slowing-down in supercooled metal alloys.

  16. Mineralogical textural and compositional data on the alteration of basaltic glass from Kilauea, Hawaii to 300 degrees C: Insights to the corrosion of a borosilicate glass waste-form

    International Nuclear Information System (INIS)

    Smith, D.K.

    1990-01-01

    Mineralogical, textural and compositional data accompanying greenschist facies metamorphism (to 300 degrees C) of basalts of the East Rift Zone (ERZ), Kilauea, Hawaii may be evaluated relative to published and experimental results for the surface corrosion of borosilicate glass. The ERZ alteration sequence is dominated by intermittent palagonite, interlayered smectite-chlorite, chlorite, and actinolite-epidote-anhydrite. Alteration is best developed in fractures and vesicles where surface reaction layers root on the glass matrix forming rinds in excess of 100 microns thick. Fractures control fluid circulation and the alteration sequence. Proximal to the glass surface, palagonite, Fe-Ti oxides and clays replace fresh glass as the surface reaction layer migrates inwards; away from the surface, amphibole, anhydrite, quartz and calcite crystallize from hydrothermal fluids in contact with the glass. The texture and composition of basaltic glass surfaces are similar to those of a SRL-165 glass leached statically for sixty days at 150 degrees C. While the ERZ reservoir is a complex open system, conservative comparisons between the alteration of ERZ and synthetic borosilicate glass are warranted. 31 refs., 2 figs

  17. Improvement of the Shock Absorption Ability of a Face Guard by Incorporating a Glass-Fiber-Reinforced Thermoplastic and Buffering Space

    OpenAIRE

    Wada, Takahiro; Churei, Hiroshi; Takayanagi, Haruka; Iwasaki, Naohiko; Ueno, Toshiaki; Takahashi, Hidekazu; Uo, Motohiro

    2018-01-01

    This study aimed to evaluate the shock absorption ability of trial face guards (FGs) incorporating a glass-fiber-reinforced thermoplastic (GF) and buffering space. The mechanical properties of 3.2 mm and 1.6 mm thick commercial medical splint materials (Aquaplast, AP) and experimental GF prepared from 1.6 mm thick AP and fiberglass cloth were determined by a three-point bending test. Shock absorption tests were conducted on APs with two different thicknesses and two types of experimental mate...

  18. Plasticity of Ability to Form Cross-Modal Representations in Infant Japanese Macaques

    Science.gov (United States)

    Adachi, Ikuma; Kuwahata, Hiroko; Fujita, Kazuo; Tomonaga, Masaki; Matsuzawa, Tetsuro

    2009-01-01

    In a previous study, Adachi, Kuwahata, Fujita, Tomonaga & Matsuzawa demonstrated that infant Japanese macaques (Macaca fuscata) form cross-modal representations of conspecifics but not of humans. However, because the subjects in the experiment were raised in a large social group and had considerably less exposure to humans than to…

  19. Dynamic stabilities of icosahedral-like clusters and their ability to form quasicrystals

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Xiaogang; Hamid, Ilyar; Duan, Haiming, E-mail: dhm@xju.edu.cn [College of Physics Science and Technology. Xinjiang University, Urumqi 830046 (China)

    2016-06-15

    The dynamic stabilities of the icosahedral-like clusters containing up to 2200 atoms are investigated for 15 metal elements. The clusters originate from five different initial structures (icosahedron, truncated decahedron, octahedron, closed-shell fragment of an HCP structure, and non-closed-shell fragment of an HCP structure). The obtained order of the dynamic stabilities of the icosahedral-like clusters can be assigned to three groups, from stronger to weaker, according to the size ranges involved: (Zr, Al, Ti) > (Cu, Fe, Co, Ni, Mg, Ag) > (Pb, Au, Pd, Pt, Rh, Ir), which correspond to the predicted formation ability of the quasicrystals. The differences of the sequences can be explained by analyzing the parameters of the Gupta-type many-body inter-atomic potentials.

  20. In vitro mechanical stimulation facilitates stress dissipation and sealing ability at the conventional glass ionomer cement-dentin interface.

    Science.gov (United States)

    Toledano, Manuel; Osorio, Raquel; Osorio, Estrella; Cabello, Inmaculada; Toledano-Osorio, Manuel; Aguilera, Fátima S

    2018-06-01

    The aim of this study was to evaluate the induced changes in the chemical and mechanical performance at the glass-ionomer cement-dentin interface after mechanical load application. A conventional glass-ionomer cement (GIC) (Ketac Bond), and a resin-modified glass-ionomer cement (RMGIC) (Vitrebond Plus) were used. Bonded interfaces were stored in simulated body fluid, and then tested or submitted to the mechanical loading challenge. Different loading waveforms were applied: No cycling, 24 h cycled in sine or loaded in sustained hold waveforms. The cement-dentin interface was evaluated using a nano-dynamic mechanical analysis, estimating the complex modulus and tan δ. Atomic Force Microscopy (AFM) imaging, Raman analysis and dye assisted confocal microscopy evaluation (CLSM) were also performed. The complex modulus was lower and tan delta was higher at interfaces promoted with the GIC if compared to the RMGIC unloaded. The conventional GIC attained evident reduction of nanoleakage. Mechanical loading favored remineralization and promoted higher complex modulus and lower tan delta values at interfaces with RMGIC, where porosity, micropermeability and nanoleakage were more abundant. Mechanical stimuli diminished the resistance to deformation and increased the stored energy at the GIC-dentin interface. The conventional GIC induced less porosity and nanoleakage than RMGIC. The RMGIC increased nanoleakage at the porous interface, and dye sorption appeared within the cement. Both cements created amorphous and crystalline apatites at the interface depending on the type of mechanical loading. Remineralization, lower stress concentration and resistance to deformation after mechanical loading improved the sealing of the GIC-dentin interface. In vitro oral function will favor high levels of accumulated energy and permits micropermeability at the RMGIC-dentin interface which will become remineralized. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Universal divergenceless scaling between structural relaxation and caged dynamics in glass-forming systems.

    Science.gov (United States)

    Ottochian, A; De Michele, C; Leporini, D

    2009-12-14

    On approaching the glass transition, the microscopic kinetic unit spends increasing time rattling in the cage of the first neighbors, whereas its average escape time, the structural relaxation time tau(alpha), increases from a few picoseconds up to thousands of seconds. A thorough study of the correlation between tau(alpha) and the rattling amplitude, expressed by the Debye-Waller factor, was carried out. Molecular-dynamics simulations of both a model polymer system and a binary mixture were performed by varying the temperature, the density rho, the potential and the polymer length to consider the structural relaxation as well as both the rotational and the translation diffusion. The present simulations, together with MD studies on other glassformers, evidence the scaling between the structural relaxation and the caged dynamics. An analytic model of the master curve is developed in terms of two characteristic length scales a(2) (1/2) and sigma(a(2) ) (1/2), pertaining to the distance to be covered by the kinetic unit to reach a transition state. The model does not imply tau(alpha) divergences. The comparison with the experiments supports the numerical evidence over a range of relaxation times as wide as about eighteen orders of magnitude. A comparison with other scaling and correlation procedures is presented. In particular, the density scaling of the length scales a(2) (1/2), sigma(a(2) ) (1/2) proportional to rho(-1/3) is shown to be not supported by the present simulations. The study suggests that the equilibrium and the moderately supercooled states of the glassformers possess key information on the huge slowing-down of their relaxation close to the glass transition. The latter, according to the present simulations, exhibits features consistent with the Lindemann melting criterion and the free-volume model.

  2. Glass formation ability, structure and magnetocaloric effect of a heavy rare-earth bulk metallic glassy Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Jo, C.-L. [Shanghai University, School of Materials Science and Engineering, Yanchang Road 149, Zhabei District, 200072 Shanghai (China)], E-mail: jochollong@163.com; Xia Lei; Ding Ding; Dong Yuanda; Gracien, Ekoko [Shanghai University, School of Materials Science and Engineering, Yanchang Road 149, Zhabei District, 200072 Shanghai (China)

    2008-06-30

    The glass formation ability, the structure and the magnetocaloric effect of the bulk metallic glassy Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy were investigated. Bulk metallic glassy (BMGs) alloys were prepared by a copper-mold casting method. The glass forming ability and their structure were studied by using X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The XRD analysis revealed that the as-cast cylinder of Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy showed fully amorphous structure in 2 mm diameter. The DSC revealed that the bulk cylinder of the Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} alloy showed a distinct glass transition temperature and a relatively wide supercooled liquid region before crystallization. SQUID investigated the magnetic properties and the entropy changes. The Curie temperature of Gd{sub 55}Co{sub 20}Fe{sub 5}Al{sub 20} BMGs alloy was about 130 K, but the maximum magnetic entropy changes(-{delta}S{sub M}) showed at about 125 K, a little lower than the Curie temperature 130 K. The reason could probably be due to the presence of a little amount of nanocrystalline particles between amorphous phases. The BMG alloy has the characteristic of second-order transition (SOT) on Arrott plots. The results showed that the amorphous sample had a relatively improved magnetocaloric effect, indicating that the amorphous alloy could be considered as a candidate for magnetic refrigeration applications in the temperature interval range of 100-200 K.

  3. Glassy slag: A complementary waste form to homogeneous glass for the implementation of MAWS in treating DOE low level/mixed wastes

    International Nuclear Information System (INIS)

    Feng, X.; Ordaz, G.; Krumrine, P.

    1994-01-01

    Glassy slag waste forms are being developed to complement glass waste forms in implementing the Minimum Additive Waste Stabilization (MAWS) Program for supporting DOE's environmental restoration efforts. These glassy slags are composed of various metal oxide crystalline phases embedded in an alumino-silicate glass phase. The slags are appropriate final waste forms for waste streams that contain large amounts of scrap metals and elements with low solubilities in glass, and that have low-flux contents. Homogeneous glass waste forms are appropriate for wastes with sufficient fluxes and low metal contents. Therefore, utilization of both glass and glassy slag waste forms will make vitrification technology applicable to the treatment of a much larger range of radioactive and mixed wastes. The MAWS approach was a plied to glassy slags by blending multiple waste streams to produce the final waste form, minimizing overall waste form volume and reducing costs. The crystalline oxide phases formed in the glassy slags can be specially formulated so that they are very durable and contain hazardous and radioactive elements in their lattice structures. The Structural Bond Strength (SBS) Model was used to predict the chemical durability of the product from the slag composition so that optimized slag compositions could be obtain with a limited number of crucible melts and testing

  4. Clinical isolates of Acinetobacter baumannii from a Portuguese hospital: PFGE characterization, antibiotic susceptibility and biofilm-forming ability.

    Science.gov (United States)

    Duarte, Andreia; Ferreira, Susana; Almeida, Sofia; Domingues, Fernanda C

    2016-04-01

    Acinetobacter baumannii is an emerging pathogen associated with nosocomial infections that in addition has shown an increasing resistance to antibiotics. In this work the genetic diversity of A. baumannii isolates from a Portuguese hospital, their antibiotic resistance profiles and ability to form biofilms was studied. Seventy-nine clinical A. baumannii isolates were characterized by pulsed-field gel electrophoresis (PFGE) with 9 different PFGE profiles being obtained. Concerning the antimicrobial susceptibility, all A. baumannii isolates were resistant to 12 of the 17 tested antibiotics and classified as multidrug-resistant (MDR). In addition, 74.7% of the isolates showed biofilm formation ability, however no statistical significance with antibiotic resistance was observed. In contrast, urine samples isolates were more likely to form biofilms than strains isolated from other sources. Our findings highlight the high number of MDR A. baumannii isolates and the importance of the formation of biofilms as a potential virulence factor. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. [Influence of La2O3 and Li2O on glass powder for infiltrating ZTA all-ceramic dental material formed by gel-casting].

    Science.gov (United States)

    Jin, Qiong; Wang, Xiao-fei; Yang, Zheng-yu; Tong, Yi-ping; Zhu, Li; Ma, Jian-feng

    2012-10-01

    The influence of La2O3 and Li2O on glass powder was studied in this paper, which is to infiltrate ZTA all-ceramic dental material formed by gel-casting. The performance of different component was analyzed to optimize glass formula. Six groups of glass powder were designed and prepared by conventional melt-quenching method. ZTA ceramic blocks were covered with glass paste, which were formed by gel-casting and sintered in 1200 degrees centigrade, then infiltrated in 1150 degrees centigrade for twice to make glass/ZTA ceramic composites. By detecting differential thermal analysis and melting range of infiltration glass power, as well as flexural strength, linear shrinkage, SEM and EDS of glass/ZTA ceramic composites, the optimized glass group was determined out. Statistical analysis was performed using SPSS 13.0 software package by means of paired t test or one way ANOVA. The bending strength of group Li1 was (291.2±27.9) MPa, significantly higher than group Li2 and group La2(Pglass of group Li1 can lubricate ZTA ceramics well, their structure was compact and had a few small pores. Intergranular fracture existed on cross surface as well as transgranular fracture. The results showed that Li1(30%La2O3-15%Al2O3-15%SiO2-15%B2O3-5%Li2O) glass infiltrated ZTA ceramic composite had the best capability. Glass/ZTA composite material can be prepared by gel-casting and infiltrating way, and this process is simple and economically suitable for general dental laboratory.

  6. Biological Behavior of Osteoblast Cell and Apatite Forming Ability of the Surface Modified Ti Alloys.

    Science.gov (United States)

    Zhao, Jingming; Hwang, K H; Choi, W S; Shin, S J; Lee, J K

    2016-02-01

    Titanium as one kind of biomaterials comes in direct contact with the body, making evaluation of biocompatibility an important aspect to biomaterials development. Surface chemistry of titanium plays an important role in osseointegration. Different surface modification alters the surface chemistry and result in different biological response. In this study, three kinds of mixed acid solutions were used to treat Ti specimens to induce Ca-P formation. Following a strong mixed acid activation process, Ca-P coating successfully formed on the Ti surfaces in simulated body fluid. Strong mixed acid increased the roughness of the metal surface, because the porous and rough surface allows better adhesion between Ca-P coatings and substrates. After modification of titanium surface by mixed acidic solution and subsequently H2O2/HCL treatment evaluation of biocompatibility was conducted from hydroxyapatite formation by biomimetic process and cell viability on modified titanium surface. Nano-scale modification of titanium surfaces can alter cellular and tissue responses, which may benefit osseointegration and dental implant therapy. Results from this study indicated that surface treatment methods affect the surface morphology, type of TiO2 layer formed and subsequent apatite deposition and biological responses. The thermo scientific alamarblue cell viability assay reagent is used to quantitatively measure the viability of mammalian cell lines, bacteria and fungi by incorporating a rapid, sensitive and reliable fluorometric/colorimetric growth indicator, without any toxic and side effect to cell line. In addition, mixed acid treatment uses a lower temperature and shorter time period than widely used alkali treatment.

  7. Investigation of the antibiotic resistance and biofilm-forming ability of Staphylococcus aureus from subclinical bovine mastitis cases.

    Science.gov (United States)

    Aslantaş, Özkan; Demir, Cemil

    2016-11-01

    A total of 112 Staphylococcus aureus isolates obtained from subclinical bovine mastitis cases were examined for antibiotic susceptibility and biofilm-forming ability as well as genes responsible for antibiotic resistance, biofilm-forming ability, and adhesin. Antimicrobial susceptibility of the isolates were determined by disk diffusion method. Biofilm forming ability of the isolates were investigated by Congo red agar method, standard tube method, and microplate method. The genes responsible for antibiotic resistance, biofilm-forming ability, and adhesion were examined by PCR. Five isolates (4.5%) were identified as methicillin-resistant Staph. aureus by antibiotic susceptibility testing and confirmed by mecA detection. The resistance rates to penicillin, ampicillin, tetracycline, erythromycin, trimethoprim-sulfamethoxazole, enrofloxacin, and amoxicillin-clavulanic acid were 45.5, 39.3, 33, 26.8, 5.4, 0.9, and 0.9%, respectively. All isolates were susceptible against vancomycin and gentamicin. The blaZ (100%), tetK (67.6%), and ermA (70%) genes were the most common antibiotic-resistance genes. Using Congo red agar, microplate, and standard tube methods, 70.5, 67, and 62.5% of the isolates were found to be biofilm producers, respectively. The percentage rate of icaA, icaD, and bap genes in Staph. aureus isolates were 86.6, 86.6, and 13.4%, respectively. The adhesion molecules fnbA, can, and clfA were detected in 87 (77.7%), 98 (87.5%), and 75 (70%) isolates, respectively. The results indicated that Staph. aureus from sublinical bovine mastitis cases were mainly resistant to β-lactams and, to a lesser extent, to tetracycline and erythromycin. Also, biofilm- and adhesion-related genes, which are increasingly accepted as an important virulence factor in the pathogenesis of Staph. aureus infections, were detected at a high rate. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  8. Structural study of conventional and bulk metallic glasses during annealing

    International Nuclear Information System (INIS)

    Pineda, E.; Hidalgo, I.; Bruna, P.; Pradell, T.; Labrador, A.; Crespo, D.

    2009-01-01

    Metallic glasses with conventional glass-forming ability (Al-Fe-Nd, Fe-Zr-B, Fe-B-Nb compositions) and bulk metallic glasses (Ca-Mg-Cu compositions) were studied by synchrotron X-ray diffraction during annealing throughout glass transition and crystallization temperatures. The analysis of the first diffraction peak position during the annealing process allowed us to follow the free volume change during relaxation and glass transition. The structure factor and the radial distribution function of the glasses were obtained from the X-ray measurements. The structural changes occurred during annealing are analyzed and discussed.

  9. About forming of personality physical culture of students in the process of physical education (in aspect of presence of abilities

    Directory of Open Access Journals (Sweden)

    S.I. Belykh

    2013-01-01

    Full Text Available It is shown that practice of teaching of discipline «Physical education» does not provide forming of volume of abilities, sufficient for the origin of athletic activity. Prevail ability to pick up a place, sporting form, inventory depending on the type of physical exercises and ability on the observance of rules of the personal hygiene. In the questionnaire questioning 650 students (324 youths and 326 girls of the first and fourth courses took part. All of students visited employments on physical education at school and institute of higher. It is marked that the important task of amateurish athletic education is forming for the students of the personal experience of independent athletic, health and рекреационных employments. It is underlined that sense of amateurish athletic education of students consists in achievement by a man unity of mental and activity processes. Such processes are needed for an estimation and understanding of the state of the health, programming and residence of healthy way of life.

  10. FLO11 gene length and transcriptional level affect biofilm-forming ability of wild flor strains of Saccharomyces cerevisiae.

    Science.gov (United States)

    Zara, Giacomo; Zara, Severino; Pinna, Claudia; Marceddu, Salvatore; Budroni, Marilena

    2009-12-01

    In Saccharomyces cerevisiae, FLO11 encodes an adhesin that is associated with different phenotypes, such as adherence to solid surfaces, hydrophobicity, mat and air-liquid biofilm formation. In the present study, we analysed FLO11 allelic polymorphisms and FLO11-associated phenotypes of 20 flor strains. We identified 13 alleles of different lengths, varying from 3.0 to 6.1 kb, thus demonstrating that FLO11 is highly polymorphic. Two alleles of 3.1 and 5.0 kb were cloned into strain BY4742 to compare the FLO11-associated phenotypes in the same genetic background. We show that there is a significant correlation between biofilm-forming ability and FLO11 length both in different and in the same genetic backgrounds. Moreover, we propose a multiple regression model that allows prediction of air-liquid biofilm-forming ability on the basis of transcription levels and lengths of FLO11 alleles in a population of S. cerevisiae flor strains. Considering that transcriptional differences are only partially explained by the differences in the promoter sequences, our results are consistent with the hypothesis that FLO11 transcription levels are strongly influenced by genetic background and affect biofilm-forming ability.

  11. The effects of mycoplasma contamination upon the ability to form bioengineered 3D kidney cysts.

    Directory of Open Access Journals (Sweden)

    Teresa M DesRochers

    Full Text Available Mycoplasma contamination of cell cultures is a pervasive, often undiagnosed and ignored problem in many laboratories that can result in reduced cell proliferation and changes in gene expression. Unless contamination is specifically suspected, it is often undetected in two dimensional (2D cultures and the resulting effects of mycoplasma contamination are rarely appreciated and can lead to incorrect conclusions. Three dimensional (3D tissue cultures are increasingly utilized to explore tissue development and phenotype. However, 3D cultures are more complex than 2D cell cultures and require a more controlled cellular environment in order to generate structures necessary to mimic in vivo responses and are often maintained for longer time periods. Changes to the microenvironment are assumed to have a more extreme effect upon the success of 3D tissue cultures than 2D cell cultures, but the effects of mycoplasma have not been studied. To test this hypothesis, we grew 2D cell cultures and 3D tissues from pig kidney epithelial cells (LLC-PK1 that were contaminated with mycoplasma and the same stock of cells after mycoplasma removal. We did not observe an effect of mycoplasma contamination on proliferation in 2D monolayer cell culture. However, cyst formation in 3D tissues was altered, with effects upon the number, size and structure of cysts formed. These data serve to reinforce the necessity of testing cell stocks for mycoplasma contamination.

  12. Role of string-like collective atomic motion on diffusion and structural relaxation in glass forming Cu-Zr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hao [International Center for New-Structured Materials (ICNSM), Zhejiang University and Laboratory of New-Structured Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada); Zhong, Cheng; Wang, Xiaodong; Cao, Qingping; Jiang, Jian-Zhong, E-mail: jiangjz@zju.edu.cn, E-mail: jack.douglas@nist.gov [International Center for New-Structured Materials (ICNSM), Zhejiang University and Laboratory of New-Structured Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Douglas, Jack F., E-mail: jiangjz@zju.edu.cn, E-mail: jack.douglas@nist.gov [Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Zhang, Dongxian [State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027 (China)

    2015-04-28

    We investigate Cu-Zr liquid alloys using molecular dynamics simulation and well-accepted embedded atom method potentials over a wide range of chemical composition and temperature as model metallic glass-forming (GF) liquids. As with other types of GF materials, the dynamics of these complex liquids are characterized by “dynamic heterogeneity” in the form of transient polymeric clusters of highly mobile atoms that are composed in turn of atomic clusters exhibiting string-like cooperative motion. In accordance with the string model of relaxation, an extension of the Adam-Gibbs (AG) model, changes in the activation free energy ΔG{sub a} with temperature of both the Cu and Zr diffusion coefficients D, and the alpha structural relaxation time τ{sub α} can be described to a good approximation by changes in the average string length, L. In particular, we confirm that the strings are a concrete realization of the abstract “cooperatively rearranging regions” of AG. We also find coexisting clusters of relatively “immobile” atoms that exhibit predominantly icosahedral local packing rather than the low symmetry packing of “mobile” atoms. These two distinct types of dynamic heterogeneity are then associated with different fluid structural states. Glass-forming liquids are thus analogous to polycrystalline materials where the icosahedrally packed regions correspond to crystal grains, and the strings reside in the relatively disordered grain boundary-like regions exterior to these locally well-ordered regions. A dynamic equilibrium between localized (“immobile”) and wandering (“mobile”) particles exists in the liquid so that the dynamic heterogeneity can be considered to be type of self-assembly process. We also characterize changes in the local atomic free volume in the course of string-like atomic motion to better understand the initiation and propagation of these fluid excitations.

  13. Non-monotonic variations of the nucleation free energy in a glass-forming ultra-soft particles fluid.

    Science.gov (United States)

    Desgranges, Caroline; Delhommelle, Jerome

    2018-06-18

    Using molecular dynamics simulation, we study the impact of the degree of supercooling on the crystal nucleation of ultra-soft particles, modeled with the Gaussian core potential. Focusing on systems with a high number density, our simulations reveal dramatically different behaviors as the degree of supercooling is varied. In the moderate supercooling regime, crystal nucleation proceeds as expected from classical nucleation theory, with a decrease in the free energy of nucleation, as well as in the size of the critical nucleus, as supercooling is increased. On the other hand, in the large supercooling regime, we observe an unusual reversal of behavior with an increase in the free energy of nucleation and in the critical size, as supercooling is increased. This unexpected result is analyzed in terms of the interplay between the glass transition and the crystal nucleation process. Specifically, medium range order crystal-like domains, with structural features different from that of the crystal nucleus, are found to form throughout the system when the supercooling is very large. These, in turn, play a pivotal role in the increase in the free energy of nucleation, as well as in the critical size, as the temperature gets closer to the glass transition.

  14. Predicting Nanoscale Dynamics of a Glass-Forming Liquid from Its Macroscopic Bulk Behavior and Vice Versa.

    Science.gov (United States)

    Adrjanowicz, Karolina; Kaminski, Kamil; Tarnacka, Magdalena; Szklarz, Grzegorz; Paluch, Marian

    2017-02-02

    The properties of a molecular liquid confined at the nanometer length scale can be very distinct from the bulk. For that reason, the macro- and the nanoscopic behaviors of glass-forming liquids are regarded as two nonconnected realms, governed by their own rules. Here, we show that the glassy dynamics in molecular liquids confined to nanometer pores might obey the density scaling relation, ρ γ /T, just like in bulk fluids. Even more surprisingly, the same value of the scaling exponent γ superposes the α-relaxation time measured at different state points in nanoscale confinement and upon increased pressure. We report this remarkable finding for van der Waals liquids tetramethyl-tetraphenyl-trisiloxane (DC704) and polyphenyl ether (5PPE), considered as simple, single-parameter liquids. Demonstrating that the density scaling idea can be fulfilled in both environments opens an exciting possibility to predict the dynamic features of the nanoconfined system close to its glass-transition temperature from the high-pressure studies of the bulk liquid. Likewise, we can describe the viscous liquid dynamics at any given combination of temperature and pressure based on analysis of its behavior in nanopores.

  15. Roles of Co element in Fe-based bulk metallic glasses utilizing industrial FeB alloy as raw material

    Directory of Open Access Journals (Sweden)

    Shouyuan Wang

    2017-08-01

    Full Text Available A series of Fe-based bulk metallic glasses were fabricated by a conventional copper mold casting method using a kind of Fe-B industrial raw alloy. It is found that Fe-B-Y-Nb bulk metallic glass with 3 at% of Co addition possesses the best glass forming ability, thermal stability, hardness, magnetic property and anti-corrosion property. The hardness test result indicates a synchronically trend with glass-forming ability parameters. The excellent glass-forming ability and a combination of good mechanical and functional properties suggest that the alloys in this work might be good candidates for commercial use.

  16. Synthesis, structure and complex forming ability of phosphorylated derivatives of heterocyclic compounds

    International Nuclear Information System (INIS)

    Babaev, B.N.

    2004-01-01

    Full text: The derivatives of acids of phosphorus, due to variety of properties, are a subject of numerous researches. Now it is known, that the derivatives of acids of phosphorus apart from insect, neurotoxic, antienzym and other kinds of physiological activity have also complex forming properties. As extra gents of noble metals particularly are analyzed by the derivatives of dithio phosphor of acids although organ phosphorus compounds with one nuclear of sulfur make extraction properties. Therefore, with the purpose of detection of effective extra gents of ions of argentum the phosphorylated derivatives of heterogeneous ring compounds were synthesized: Ph(RO)P(O)Cl + HOCH(CH 3 )CH 2 -R ' -> Ph(RO)P(O)OCH(CH 3 )CH 2 -R ' + HCl. R C 2 H 5 - C 6 H 13 , R ' = a piperidine, morpholine, anabasine Structure of the obtained connections is confirmed by the results IR -, Pm- and mass- spectrometry. In an IR-spectrum O-hexyl-O - [piperidynoisopropyl] phenylphosphonate has lines of absorption bands of the following functional groups (ν, cm -1 ): (P-O-C 5 H 11 ) 990-1000, (P = 0) 1260, (P-C 6 H 5 )1450, (C-N in cycle) 1550. In an IR-spectrum O-pentyl-[anabasinoisopropyl] phenylphosphonate has lines of absorption bands of the following functional groups (ν, cm -1 ): (P-O-C 5 H 11 ) 990-1000, (P = 0) 1250, (P-C 6 H 5 )1450, (C-N in cycle) 1550. In a spectrum PMR about O-pentyl-[morpholyniisopropyl] phenylphosphonate in the field of a weak field (7, 18-7, 29 p.m.) the multiplet about tones of phenyl group is watched. Me tin proton resonate at 4,66 m.d.as multiplet The signals O-CH 2 of protons of morpholinic cycle appear at 3,58 m.d.. 4H) by the way of triplet. The protons N-CH 2 (6H) three methylene groups will derivate a composite multiple at 2, 10-2, 70 m.d.. The signal of metil group's protons (3H) is watched at 1,15m.d.as doublet. Final metal group resonates at 0, 87 p.m. Six of C-CH 2 of groups give a complex signal in the field of 1, 2-1, 8 m.d. The obtained connections

  17. 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

  18. Eutectic crystallization behavior of new Zr48Cu36Al8Ag8 alloy with high glass-forming ability

    International Nuclear Information System (INIS)

    Zhang, Q S; Zhang, W; Xie, G Q; Inoue, A

    2009-01-01

    A water quenching method is used to produce as-cast Zr 48 Cu 36 Al 8 Ag 8 rods with diameters from 20 mm to 25 mm. The microstructures of the as-cast samples were investigated by X-ray diffraction, optical microscopy and scanning electron microscopy. Furthermore, the crystallization behavior of the Zr 48 Cu 36 Al 8 Ag 8 glassy alloy was examined by XRD and transmission electron microscopy. Based on the results obtained one can assume that the simultaneous precipitation of the Zr 2 Cu+AlCu 2 Zr eutectic phases is the possible reason for the high stabilization of the quaternary Zr 48 Cu 36 Al 8 Ag 8 supercooled liquid.

  19. Thermal behaviors of liquid La-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, D. W.; Wang, X. D., E-mail: wangxd@zju.edu.cn, E-mail: jiangjz@zju.edu.cn; Lou, H. B.; Cao, Q. P.; Jiang, J. Z., E-mail: wangxd@zju.edu.cn, E-mail: jiangjz@zju.edu.cn [International Center for New-Structured Materials (ICNSM), Laboratory of New-Structured Materials, State Key Laboratory of Silicon Materials, and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Wang, L. W. [Institute of Materials Science and Engineering, Lanzhou University, Lanzhou 730000 (China); Zhang, D. X. [State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027 (China)

    2014-12-14

    Thermal behaviors of liquid La-based bulk metallic glasses have been measured by using the dilatometer with a self-sealed sample cell. It is demonstrated that the strong glass forming liquid not only has the small thermal expansion coefficient but also shows the slow variation rate. Moreover, the strong glass former has relatively dense atomic packing and also small density change in the liquid state. The results suggest that the high glass forming ability of La-based metallic glasses would be closely related to the slow atomic rearrangements in liquid melts.

  20. In Vitro Comparison of Zinc Phosphate and Glass Ionomers Ability to Inhibit Decalcification under and Adjacent to Orthodontic Bands.

    Science.gov (United States)

    1985-08-01

    confer the ability to leach fluoride ions into the surrounding tooth enamel . Kidd 3 7 using an artifical caries tec- hnique with a diffusion controlled...5 - Enamel Changes Scoring System- 1. NONE: No color change evident 2. MILD: Slight change in enamel color 3.MODERATE: Definate whitening of enamel ...to adhere to stainless steel and to tooth enamel with a chemical bond 51 . Zinc phosphate, on the other hand, does not chemically adhere to enamel or

  1. Fragility characterization of disaccharide/water glass-forming systems by QENS

    Energy Technology Data Exchange (ETDEWEB)

    Branca, C.; Magazu, S.; Maisano, G

    2003-08-01

    Up to now, the molecular mechanisms underlying the bioprotectant properties of trehalose are not fully understood. From the beginning of our research the attention has been mainly focused on the role played by the disaccharide/water interactions in unravelling the mechanisms which make trehalose, among disaccharides, the most effective bioprotector. In the present work, results of neutron scattering measurements performed on trehalose/H{sub 2}O and sucrose/H{sub 2}O mixtures are reported. A correlation between the temperature behaviour of the mean-square displacement evaluated by QENS and fragility is proposed. What emerges from this study is the stronger character of the trehalose/water mixture in comparison with the sucrose/water. This implies a greater ability of trehalose, in respect to sucrose, to encapsulate biomolecules into more rigid structures and hence a greater cryptobiotic effectiveness.

  2. The ability to form full-length intron RNA circles is a general property of nuclear group I introns

    DEFF Research Database (Denmark)

    Nielsen, Henrik; Fiskaa, Tonje; Birgisdottir, Asa Birna

    2003-01-01

    at the expense of the host. The circularization pathway has distinct structural requirements that differ from those of splicing and appears to be specifically suppressed in vivo. The ability to form full-length circles is found in all types of nuclear group I introns, including those from the Tetrahymena...... ribosomal DNA. The biological function of the full-length circles is not known, but the fact that the circles contain the entire genetic information of the intron suggests a role in intron mobility....

  3. Binucleate cell formation correlates to loss of colony-forming ability in X-irradiated cultured mammalian cells

    International Nuclear Information System (INIS)

    Sasaki, H.; Yoshinaga, H.; Kura, S.

    1986-01-01

    The relationship between binucleate cell formation and the loss of colony-forming ability was examined in several cultured mammalian cell lines irradiated with X rays. The maximum fraction of binucleate cells after X irradiation increased dose-dependently within the range in which reproductive cell death might predominate over interphase cell death. When the logarithm of percentage survival was plotted against the percentage binucleate cells, a similar correlation was found for all cell lines tested, with the exception of mouse leukemia L5178Y cells, the most radiosensitive cells used. These observations suggest that the fraction of binucleate cells in the cell population can serve as a measure of cellular radiation damage

  4. Characterization of a glass-bonded ceramic waste form loaded with U and Pu

    International Nuclear Information System (INIS)

    Sinkler, W.; O'Holleran, T. P.; Frank, S. M.; Richmann, M. K.; Johnson, S. G.

    1999-01-01

    This paper presents microscopic characterization of four samples of a ceramic waste form (CWF) developed for disposal of actinide-containing electrorefiner salts. The four samples were prepared to investigate the influence of water content and the Pu:U ratio on CWF microstructure and performance. While the overall phase content is not strongly influenced by either variable, the presence of water in the initial zeolite has a detectable effect on CWF microstructure. It is found to influence the distribution of the major actinide host phase, a (U,Pu)O 2 mixed oxide

  5. Comparative risk assessments for the production and interim storage of glass and ceramic waste forms: defense waste processing facility

    International Nuclear Information System (INIS)

    Huang, J.C.; Wright, W.V.

    1982-04-01

    The Defense Waste Processing Facility (DWPF) for immobilizing nuclear high level waste (HLW) is scheduled to be built at the Savannah River Plant (SRP). High level waste is produced when SRP reactor components are subjected to chemical separation operations. Two candidates for immobilizing this HLW are borosilicate glass and crystalline ceramic, either being contained in weld-sealed stainless steel canisters. A number of technical analyses are being conducted to support a selection between these two waste forms. The present document compares the risks associated with the manufacture and interim storage of these two forms in the DWPF. Process information used in the risk analysis was taken primarily from a DWPF processibility analysis. The DWPF environmental analysis provided much of the necessary environmental information. To perform the comparative risk assessments, consequences of the postulated accidents are calculated in terms of: (1) the maximum dose to an off-site individual; and (2) the dose to off-site population within 80 kilometers of the DWPF, both taken in terms of the 50-year inhalation dose commitment. The consequences are then multiplied by the estimated accident probabilities to obtain the risks. The analyses indicate that the maximum exposure risk to an individual resulting from the accidents postulated for both the production and interim storage of either waste form represents only an insignificant fraction of the natural background radiation of about 90 mrem per year per person in the local area. They also show that there is no disaster potential to the off-site population. Therefore, the risks from abnormal events in the production and the interim storage of the DWPF waste forms should not be considered as a dominant factor in the selection of the final waste form

  6. Simulated glass-forming polymer melts: dynamic scattering functions, chain length effects, and mode-coupling theory analysis.

    Science.gov (United States)

    Frey, S; Weysser, F; Meyer, H; Farago, J; Fuchs, M; Baschnagel, J

    2015-02-01

    We present molecular-dynamics simulations for a fully flexible model of polymer melts with different chain length N ranging from short oligomers (N = 4) to values near the entanglement length (N = 64). For these systems we explore the structural relaxation of the supercooled melt near the critical temperature T c of mode-coupling theory (MCT). Coherent and incoherent scattering functions are analyzed in terms of the idealized MCT. For temperatures T > T c we provide evidence for the space-time factorization property of the β relaxation and for the time-temperature superposition principle (TTSP) of the α relaxation, and we also discuss deviations from these predictions for T ≈ T c. For T larger than the smallest temperature where the TTSP holds we perform a quantitative analysis of the dynamics with the asymptotic MCT predictions for the late β regime. Within MCT a key quantity, in addition to T c, is the exponent parameter λ. For the fully flexible polymer models studied we find that λ is independent of N and has a value (λ = 0.735 ) typical of simple glass-forming liquids. On the other hand, the critical temperature increases with chain length toward an asymptotic value T c (∞) . This increase can be described by T c (∞) - T c(N) ∼ 1/N and may be interpreted in terms of the N dependence of the monomer density ρ, if we assume that the MCT glass transition is ruled by a soft-sphere-like constant coupling parameter Γ c = ρ c T c (-1/4), where ρ c is the monomer density at T c. In addition, we also estimate T c from a Hansen-Verlet-like criterion and MCT calculations based on structural input from the simulation. For our polymer model both the Hansen-Verlet criterion and the MCT calculations suggest T c to decrease with increasing chain length, in contrast to the direct analysis of the simulation data.

  7. 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.

  8. 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.

  9. Study of the mixed alkali effect in lithium and sodium metaphosphate glass-forming liquids by photon correlation spectroscopy

    International Nuclear Information System (INIS)

    Changstrom, J R; Sidebottom, D L

    2008-01-01

    We report results of an extensive study of the structural relaxation occurring in mixed alkali metaphosphate liquids obtained by photon correlation spectroscopy. Values for the glass transition temperature, the fragility index, and the heterogeneity parameter (also known as the Kohlrausch exponent) are extracted from the measurements and are all shown to exhibit a mixed alkali effect wherein nonlinear variations with mixing occur. The depression in the glass transition temperature is shown to be the direct result of mechanical relaxations, present in the solid, which prematurely loosen the glass structure. A minimum in the fragility index is believed to be an artifact of the resulting depression of the glass transition temperature

  10. Hydrothermal alteration of the glass R7T7. Glass dissolution kinetics at 150 and 2500, role of neo-formed phases

    International Nuclear Information System (INIS)

    Caurel, J.

    1990-01-01

    The glass R7T7 is chosen in France for vitrification of solution from reprocessing. Safety requires the knowledge of R7T7 long term behavior in deep geologic formations. Temperature dependence of leaching between 50 and 300 0 C is studied by static tests for 7 days. An activation energy of 30kJ/Mole is calculated between 50; 75 or 100 0 C and 250 0 C. Results suggest similar corrosion mechanisms between 90-100 and 250 0 C by a complete change between 250 and 275 0 C. Glass corrosion kinetics at 150 0 C and 250 0 C between 1 day and 1 year evidence the precipitation of aluminosilicates and formation of thick amorphous gels progressively enriched with silica. Glass dissolution at 150 0 C and 250 0 C is simulated with the geochemical DISSOL code. Results suggest that dissolution kinetics are controlled by activity of H 4 SiO 4 in solution only. Silica contained into the gel controls corrosion kinetics different from 0. Even if the nature of dissolution mechanisms does not seem modified between 150 and 250 0 C, sample cracking at 250 0 C induces an increase of dissolved glass that does not allow a direct comparison of corrosion kinetics between 150 and 250 0 C [fr

  11. Effect of glass-forming biopreservatives on head group rotational dynamics in freeze-dried phospholipid bilayers: A 31P NMR study

    Science.gov (United States)

    Jain, P.; Sen, S.; Risbud, S. H.

    2009-07-01

    P31 NMR spectroscopy has been used to elucidate the role of glass-forming sugars in the preservation of dipalmitoylphosphatidylcholine (DPPC) lipid bilayers. P31 wideline NMR spectra of freeze-dried pure DPPC, DPPC/trehalose, DPPC/glucose, and DPPC/hydroxyethyl starch (HES) mixtures collected in the temperature range of 25-80 °C have been simulated to obtain quantitative information about rotational dynamics and orientation of the lipid head groups in these media. In the case of pure DPPC, DPPC/glucose, and DPPC/HES, the gel-to-liquid crystalline phase transition of DPPC bilayer is characterized by a sudden increase in the rate of rotational diffusion of the PO4 head groups near 40 °C. The corresponding rotational jump frequency increases from a few kilohertz in the gel phase to at least several megahertz in the liquid crystalline phase. On the other hand, in the case of DPPC/trehalose mixture the temperature of this onset of rapid head group dynamics is increased by ˜10 °C. Trehalose reduces the lipid head group motions most effectively in the temperature range of T ≤50 °C relevant for biopreservation. Additionally, and possibly more importantly, trehalose is found to strongly restrict any change in the orientation of the diffusion axis of the PO4 head groups during the phase transformation. This unique ability of trehalose to maintain the dynamical and orientational rigidity of lipid head groups is likely to be responsible for its superior ability in biopreservation.

  12. 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.

  13. Characterization of the alteration products formed at the surface of LaYSiAlO and CeYSiAlO glasses using ERDA and RBS techniques

    International Nuclear Information System (INIS)

    Gavarini, S.; Trocellier, P.; Matzen, G.

    2004-01-01

    Leaching tests have been performed on LnYSiAlO glasses (Ln = La or Ce) that are considered as potential matrices for the specific immobilization of minor actinides. Elastic recoil detection analysis (ERDA) performed on leached samples indicated a superficial hydration of LaYSiAlO glass of about 100-150 nm. This hydrated layer is (Al, Y)-enriched according to SEM-EDS analysis, suggesting the formation of hydroxide (or hydroxycarbonates) compounds including these two elements. This process leads to a very efficient passivation of the material due to the low solubility of Al and Y hydroxides (and hydroxycarbonates) species in near neutral media, even when the solution is rapidly replenished is dynamic leaching experiments. Rutherford Backscattering Spectrometry elemental mapping revealed very localized and significantly Y-enriched deposits at the surface of the sample after leaching. This could be the sign of heterogeneities already present on the pristine glass. These may be correlated with the weak solubility of yttrium (and rare earth) elements in silicate matrices (Y + Ln initial content in the glass ∼11 at.%). In the case of CeYSiAlO glass, a thin layer was formed on the solid after leaching. The simulation of the corresponding RBS spectra showed a surface (Y, Ce)-enrichment and (Al, Si)-depletion in both cases. This could be explained by the oxidation of trivalent cerium initially present in the glass structure during leaching. This might be explained by the low solubility of Ce(IV)-compounds (CeO 2 and/or Ce(OH) 4 ) in solution leading to an enrichment of this element at the glass/solution interface, to form a mixture of amorphous CeO 2 and Y(OH) 3 , as confirmed by XPS and XRD experiments

  14. Thermomechanical Properties of Sb2O3-TeO2-V2O5 Glassy Systems: Thermal Stability, Glass Forming Tendency and Vickers Hardness

    Science.gov (United States)

    Souri, Dariush; Torkashvand, Ziba

    2017-04-01

    Three-component 40TeO2-(60- x)V2O5- xSb2O3 glasses with 0 ≤ x ≤ 10 (in mol.%) were obtained by the rapid melt-quenching method. These glasses were studied with respect to some mechanical properties with the goal of obtaining information about their structure. The Vickers hardness test was employed to obtain Vickers micro-hardness ( H V) at two different loads, which was within the range of 13.187-17.557 GPa for a typical 0.1 HV (0.9807 N) load. In addition, theoretical micro-hardness ( H) was investigated and compared with experimental H V, showing the elevating trend with increase of Sb2O3 content, as for H V. Furthermore, differential scanning calorimetry (DSC) was employed within the range of 150-500°C at heating rates of φ = 3 K/min, 6 K/min, 9 K/min, 10 K/min, and 13 K/min. In this work, thermal stability ( T s = T cr - T x) and glass forming tendency ( K gl) were measured and reported for these glasses to determine the relationship between the chemical composition and the thermal stability, in order to interpret the structure of glass. Generally, from the ascertained outputs [analysis of mechanical data, titration study, the values of reduced fraction of vanadium ions ( C V) and oxygen molar volume ( V_{{O}}^{*} )], it was found that the micro-hardness had an increasing trend with increasing the Sb2O3 content. Among the studied glasses, the sample with x = 8 had a higher average micro-hardness value, the highest average thermal stability and glass forming tendency with respect to the other samples, which makes it a useful material (owning very good resistance against thermal attacks) for device manufacturing.

  15. Physical, thermal and structural properties of Calcium Borotellurite glass system

    Energy Technology Data Exchange (ETDEWEB)

    Paz, E.C. [CCSST – UFMA, Imperatriz, MA (Brazil); IFMA, Açailândia, MA (Brazil); Dias, J.D.M. [CCSST – UFMA, Imperatriz, MA (Brazil); Melo, G.H.A. [CCSST – UFMA, Imperatriz, MA (Brazil); IFMA, Imperatriz, MA (Brazil); Lodi, T.A. [CCSST – UFMA, Imperatriz, MA (Brazil); Carvalho, J.O. [CCSST – UFMA, Imperatriz, MA (Brazil); IFTO, Araguaína, TO (Brazil); Façanha Filho, P.F.; Barboza, M.J.; Pedrochi, F. [CCSST – UFMA, Imperatriz, MA (Brazil); Steimacher, A., E-mail: steimacher@hotmail.com [CCSST – UFMA, Imperatriz, MA (Brazil)

    2016-08-01

    In this work the glass forming ability in Calcium Borotellurite (CBTx) glass system was studied. Six glass samples were prepared by melt-quenching technique and the obtained samples are transparent, lightly yellowish, with no visible crystallites. The structural studies were carried out by using XRD, FTIR, Raman Spectra, density measurements, and the thermal analysis by using DTA and specific heat. The results are discussed in terms of tellurium oxide content and their changes in structural and thermal properties of glass samples. The addition of TeO{sub 2} increased the density and thermal stability values and decreased glass transition temperature (Tg). Raman and FTIR spectroscopies indicated that the network structure of CBTx glasses is formed by BO{sub 3}, BO{sub 4}, TeO{sub 3}, TeO{sub 3+1} and TeO{sub 4} units. CBTx system showed good glass formation ability and good thermal stability, which make CBTx glasses suitable for manufacturing process and a candidate for rare-earth doping for several optical applications. - Highlights: • Glass forming ability on Calcium Borotellurite system was studied. • The glass structure was investigated by XRD, Raman and FTIR. • The glass network structure of the CBTx glasses is formed by BO{sub 3}, BO{sub 4}, TeO{sub 3}, TeO{sub 3+1} and TeO{sub 4} units. • The density and thermal stability of the CBTx glass decreases with TeO{sub 2} while the Cp and the Tg decreases. • The obtained CBTx glasses are suitable for manufacturing process and rare-earth doping for several optical applications.

  16. Effect of histatin-5 and lysozyme on the ability of Streptococcus mutans to form biofilms in in vitro conditions.

    Science.gov (United States)

    Krzyściak, Wirginia; Jurczak, Anna; Piątkowski, Jakub; Kościelniak, Dorota; Gregorczyk-Maga, Iwona; Kołodziej, Iwona; Papież, Monika A; Olczak-Kowalczyk, Dorota

    2015-09-20

    The mechanisms of adhesion to solid surfaces enable S. mutans to colonize oral cavities and form biofilms, which play an important role in caries development. Additional properties enabling the survival of S. mutans in the oral cavity include its ability to survive in acidic environments and specific interactions with other microorganisms inhabiting this ecosystem. The aim of this study was to determine the antibacterial activity of saliva histatin-5 (peptide) and lysozyme (protein) against S. mutans and L. rhamnosus, as representatives of physiological flora. The study involved strains of physiological (L. rhamnosus) and cariogenic (S. mutans) flora isolated from one patient with diagnosed early caries of the deciduous teeth. It was proved that the presence of probiotic L. rhamnosus bacteria in the environment had a negative impact on the ability of S. mutans to produce biofilm. Moreover, the antibacterial activity of histatin-5 was confirmed, and it inhibited S. mutans growth at concentrations of 27.2 μg/ml and 54.4 μg/ml, both individually and in a mixture with lysozyme (in a total concentration of 54.4 μg/ml). The data obtained constitute a promising result due to their potential future application in the prevention and early diagnosis of caries.

  17. Effect of histatin-5 and lysozyme on the ability of Streptococcus mutans to form biofilms in in vitro conditions

    Directory of Open Access Journals (Sweden)

    Wirginia Krzyściak

    2015-09-01

    Full Text Available The mechanisms of adhesion to solid surfaces enable S. mutans to colonize oral cavities and form biofilms, which play an important role in caries development. Additional properties enabling the survival of S. mutans in the oral cavity include its ability to survive in acidic environments and specific interactions with other microorganisms inhabiting this ecosystem.The aim of this study was to determine the antibacterial activity of saliva histatin-5 (peptide and lysozyme (protein against S. mutans and L. rhamnosus, as representatives of physiological flora.The study involved strains of physiological (L. rhamnosus and cariogenic (S. mutans flora isolated from one patient with diagnosed early caries of the deciduous teeth.It was proved that the presence of probiotic L. rhamnosus bacteria in the environment had a negative impact on the ability of S. mutans to produce biofilm. Moreover, the antibacterial activity of histatin-5 was confirmed, and it inhibited S. mutans growth at concentrations of 27.2 μg/ml and 54.4 μg/ml, both individually and in a mixture with lysozyme (in a total concentration of 54.4 μg/ml.The data obtained constitute a promising result due to their potential future application in the prevention and early diagnosis of caries.

  18. Improvement of the Shock Absorption Ability of a Face Guard by Incorporating a Glass-Fiber-Reinforced Thermoplastic and Buffering Space

    Directory of Open Access Journals (Sweden)

    Takahiro Wada

    2018-01-01

    Full Text Available This study aimed to evaluate the shock absorption ability of trial face guards (FGs incorporating a glass-fiber-reinforced thermoplastic (GF and buffering space. The mechanical properties of 3.2 mm and 1.6 mm thick commercial medical splint materials (Aquaplast, AP and experimental GF prepared from 1.6 mm thick AP and fiberglass cloth were determined by a three-point bending test. Shock absorption tests were conducted on APs with two different thicknesses and two types of experimental materials, both with a bottom material of 1.6 mm thick AP and a buffering space of 30 mm in diameter (APS and with either (i 1.6 mm thick AP (AP-APS or (ii  1.6 mm thick GF (GF-APS covering the APS. The GF exhibited significantly higher flexural strength (64.4 MPa and flexural modulus (7.53 GPa than the commercial specimens. The maximum load of GF-APS was 75% that of 3.2 mm AP, which is widely used clinically. The maximum stress of the GF-APS only could not be determined as its maximum stress is below the limits of the analysis materials used (<0.5 MPa. Incorporating a GF and buffering space would enhance the shock absorption ability; thus, the shock absorption ability increased while the total thickness and weight decreased.

  19. NMR characterization of simulated Hanford low-activity waste glasses and its use in understanding waste form chemical durability

    International Nuclear Information System (INIS)

    Darab, J.G.; Linehan, J.C.; McGrail, B.P.

    1999-01-01

    Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR) spectroscopy has been used to characterize the structural and chemical environments of B, Al, and Si in model Hanford low-activity waste glasses. The average 29 Si NMR peak position was found to systematically change with changing glass composition and structure. From an understanding of the structural roles of Al and B obtained from MAS-NMR experiments, the authors first developed a model that reliably predicts the distribution of structural units and the average 29 Si chemical shift value, δ, based purely on glass composition. A product consistency test (PCT) was used to determine the normalized elemental release (NL) from the prepared glasses. Comparison of the NMR and PCT data obtained from sodium boro-aluminosilicate glasses indicates that a rudimentary exponential relationship exists between the 29 Si chemical shift value, and the boron NL value

  20. Effect of Polymer Form and its Consolidation on Mechanical Properties and Quality of Glass/PBT Composites

    DEFF Research Database (Denmark)

    Raghavalu Thirumalai, Durai Prabhakaran; Pillai, Saju; Charca, Samuel

    2014-01-01

    different material systems included in this study; Glass/CBT (CBT160 powder based resin), Glass/PBT (prepreg tapes), and Glass/PBT (commingled yarns). The different types of thermoplastic polymer resin systems used for the manufacturing of the composite UD laminate dictate the differences in final......The aim of this study was to understand the role of the processing in determining the mechanical properties of glass fibre reinforced polybutylene terephthalate composites (Glass/PBT). Unidirectional (UD) composite laminates were manufactured by the vacuum consolidation technique using three...... mechanical properties which were evaluated by through compression, flexural and short beam transverse bending tests. Microscopy was used to evaluate the quality of the processed laminates, and fractography was used to characterize the observed failure modes. The study provides an improved understanding...

  1. Effect of Polymer Form and its Consolidation on Mechanical Properties and Quality of Glass/PBT Composites

    Science.gov (United States)

    Durai Prabhakaran, R. T.; Pillai, Saju; Charca, Samuel; Oshkovr, Simin Ataollahi; Knudsen, Hans; Andersen, Tom Løgstrup; Bech, Jakob Ilsted; Thomsen, Ole Thybo; Lilholt, Hans

    2014-04-01

    The aim of this study was to understand the role of the processing in determining the mechanical properties of glass fibre reinforced polybutylene terephthalate composites (Glass/PBT). Unidirectional (UD) composite laminates were manufactured by the vacuum consolidation technique using three different material systems included in this study; Glass/CBT (CBT160 powder based resin), Glass/PBT (prepreg tapes), and Glass/PBT (commingled yarns). The different types of thermoplastic polymer resin systems used for the manufacturing of the composite UD laminate dictate the differences in final mechanical properties which were evaluated by through compression, flexural and short beam transverse bending tests. Microscopy was used to evaluate the quality of the processed laminates, and fractography was used to characterize the observed failure modes. The study provides an improved understanding of the relationships between processing methods, resin characteristics, and mechanical performance of thermoplastic resin composite materials.

  2. Temperature dependence of charge-transfer fluorescence from extended and U-shaped donor-bridge-acceptor systems in glass-forming solvents.

    NARCIS (Netherlands)

    Goes, M.; de Groot, M.; Koeberg, M.; Verhoeven, J.W.; Lokan, N.R.; Shephard, M.J.; Paddon-Row, M.N.

    2001-01-01

    Abstract: The behavior is reported of three fluorescent D-bridge-A systems that display a fascinating temperature dependence in glass forming solvents over the temperature range between 77 and 293 K. In two of these systems, a rigid, saturated alkane bridge maintains an extended conformation, and as

  3. Preparation and properties of calcium-silicate filled resins for dental restoration. Part I: chemical-physical characterization and apatite-forming ability.

    Science.gov (United States)

    Profeta, Andrea Corrado

    2014-11-01

    The aim of this study was to measure dimensional changes due to hygroscopic expansion and the bioactivity of two experimental methacrylate-based dental adhesives either incorporating Bioglass 45S5 (3-E&RA/BG) or MTA (3-E&RA/WMTA). 3-E&RA/BG, 3-E&RA/WMTA and a control filler-free resin blend (3-E&RA) were formulated from commercially available monomers. Water sorption (WS) and solubility (SL) behaviour were evaluated by weighing material disks at noted intervals; the relationship between degree of hydration and the glass transition temperature (Tg) was investigated by using differential scanning calorimetry (DSC). In vitro apatite-forming ability as a function of soaking time in phosphate-containing solutions was also determined. Kruskal-Wallis analysis of variance (ANOVA) was used to evaluate differences between groups for maximum WS, SL, net water uptake and the percentage change in Tg values. Post-ANOVA pair-wise comparisons were conducted using Mann-Whitney-U tests. 3-E&RA/BG and 3-E&RA/WMTA exhibited values of maximum WS and net water uptake that were significantly higher when compared to 3-E&RA. However, no statistically significant differences were observed in terms of SL between all the adhesives. The addition of the Bioglass 45S5 and MTA to the 3-E&RA showed no reduction of the Tg after 60 days of storage in deionized water. ATR Fourier Transform Infrared Spectroscopy (ATR-FTIR) of the filled resin disks soaked in DPBS for 60 days showed the presence of carbonate ions in different chemical phases. Dentine bonding agents comprising calcium-silicates are not inert materials in a simulated oral environment and apatite formation may occur in the intra-oral conditions. A bioactive dental material which forms apatite on the surface would have several benefits including closure of gaps forming at the resin-dentine interface and potentially better bond strength over time (less degradation of bond).

  4. Dynamics of the α-relaxation in glass-forming polymers. Study by neutron scattering and relaxation techniques

    Science.gov (United States)

    Colmenero, J.

    1993-12-01

    The dynamics of the α-relaxation in three different polymeric systems, poly(vinyl methyl ether) (PVME), poly(vinyl chloride) (PVC) and poly(bisphenol A, 2-hydroxypropylether) (PH) has been studied by means of relaxation techniques and quasielastic neutron scattering (backscattering spectrometers IN10 and IN13 at the ILL-Grenoble). By using these techniques we have covered a wide time scale ranging from mesoscopic to macroscopic times (10 -10 -10 1 s). For analyzing the experimental data we have developed a phenomenological procedure in the frequency domain based on the Havriliak-Negami relaxation function, which in fact implies a Kohlrausch-Williams-Watts relaxation function in the time domain. The results obtained indicate that the dynamics of the α-relaxation in a wide time scale shows a clear non-Debye behaviour. The shape of the relaxation functions is found to be similar for the different techniques used and independent of temperature and momentum transfer ( Q). Moreover, the characteristic relaxation times deduced from the fitting of the experimental data can also be described using only one Vogel-Fulcher functional form. Besides we found that the Q-dependence of the relaxation times obtained by QENS is given by a power law, τ( Q) ∞ Q- n ( n>2), n being dependent on the system, and that the Q-behaviour and the non-Debye behaviour are directly correlated. In the case of PVC, time of flight (TOF) neutron scattering experiments confirm these results in a shorter time scale (2×10 -11 -2× 10 -12 s). Moreover, TOF results also suggest the possibility of interpreting the “fast process” usually detected in glass-forming systems as a Debye-like short regime of the α-relaxation.

  5. Experimental study of the hydrothermal alteration of a chemical analogue of the French nuclear glass in a thermal gradient: characterization of newly formed phases and of matter transfers

    International Nuclear Information System (INIS)

    Poinssot, Christophe

    1994-01-01

    As the most dangerous radioactive wastes are to be stored in deep geological layers after having been packaged in barrels made of borosilicate glasses, this research report addresses the study of the alteration of such glasses through the study of a chemical analogue. In order to experimentally model phenomena involved within a storage, the studied glass has been submitted to different thermal gradients between 320 and 150 C and during 3 to 5 months. These gradients comply with those met about the parcels, and allows the spatial evolution of the waste parcel at a given moment, as well as the evolution in time (progressive cooling of wastes) to be simultaneously simulated. The different phases formed within the gradient have been studied and characterized by scanning electronic microscopy, semi-quantitative microanalysis, and X-ray micro-diffraction [fr

  6. Targeted changes of the cell wall proteome influence Candida albicans ability to form single- and multi-strain biofilms.

    Directory of Open Access Journals (Sweden)

    Vitor Cabral

    2014-12-01

    Full Text Available Biofilm formation is an important virulence trait of the pathogenic yeast Candida albicans. We have combined gene overexpression, strain barcoding and microarray profiling to screen a library of 531 C. albicans conditional overexpression strains (∼10% of the genome for genes affecting biofilm development in mixed-population experiments. The overexpression of 16 genes increased strain occupancy within a multi-strain biofilm, whereas overexpression of 4 genes decreased it. The set of 16 genes was significantly enriched for those encoding predicted glycosylphosphatidylinositol (GPI-modified proteins, namely Ihd1/Pga36, Phr2, Pga15, Pga19, Pga22, Pga32, Pga37, Pga42 and Pga59; eight of which have been classified as pathogen-specific. Validation experiments using either individually- or competitively-grown overexpression strains revealed that the contribution of these genes to biofilm formation was variable and stage-specific. Deeper functional analysis of PGA59 and PGA22 at a single-cell resolution using atomic force microscopy showed that overexpression of either gene increased C. albicans ability to adhere to an abiotic substrate. However, unlike PGA59, PGA22 overexpression led to cell cluster formation that resulted in increased sensitivity to shear forces and decreased ability to form a single-strain biofilm. Within the multi-strain environment provided by the PGA22-non overexpressing cells, PGA22-overexpressing cells were protected from shear forces and fitter for biofilm development. Ultrastructural analysis, genome-wide transcript profiling and phenotypic analyses in a heterologous context suggested that PGA22 affects cell adherence through alteration of cell wall structure and/or function. Taken together, our findings reveal that several novel predicted GPI-modified proteins contribute to the cooperative behaviour between biofilm cells and are important participants during C. albicans biofilm formation. Moreover, they illustrate the power

  7. Career Adapt-Abilities Scale--Italian Form: Psychometric Properties and Relationships to Breadth of Interests, Quality of Life, and Perceived Barriers

    Science.gov (United States)

    Soresi, Salvatore; Nota, Laura; Ferrari, Lea

    2012-01-01

    The Career Adapt-Abilities Scale (CAAS)-Italian Form consists of four 6-item scales, which measure concern, control, curiosity, and confidence as psychosocial resources for managing occupational transitions, developmental tasks, and work traumas. The 24-item CAAS-Italian Form is identical to the International Form 2.0. The factor structure was…

  8. Pock forming ability of fowl pox virus isolated from layer chicken and its adaptation in chicken embryo fibroblast cell culture.

    Science.gov (United States)

    Gilhare, Varsha Rani; Hirpurkar, S D; Kumar, Ashish; Naik, Surendra Kumar; Sahu, Tarini

    2015-03-01

    The objective of the present study was to examine pock forming ability of field strain and vaccine strain of fowl pox virus (FPV) in chorioallantoic membrane (CAM) of embryonated chicken eggs and its adaptation in chicken embryo fibroblast (CEF) cell culture. Dry scabs were collected from 25 affected birds in glycerin-saline and preserved at 4°C until processed. Virus was isolated in 10-day-old embryonated chicken eggs by dropped CAM method. The identity of the virus is confirmed by clinical findings of affected birds, pock morphology and histopathology of infected CAM. In addition one field isolate and vaccine strain of FPV was adapted to CEF cell culture. CEF cell culture was prepared from 9-day-old embryonated chicken eggs. Clinical symptoms observed in affected birds include pox lesion on comb, wattle, eyelids and legs, no internal lesions were observed. All field isolates produced similar findings in CAM. Pocks produced by field isolates ranged from 3 mm to 5 mm at the third passage while initial passages edematous thickening and necrosis of CAM was observed. Pocks formed by lyophilized strain were ranges from 0.5 mm to 2.5 mm in diameter scattered all over the membrane at the first passage. Intra-cytoplasmic inclusion bodies are found on histopathology of CAM. At third passage level, the CEF inoculated with FPV showed characteristic cytopathic effect (CPE) included aggregation of cells, syncytia and plaque formation. FPV field isolates and vaccine strain produced distinct pock lesions on CAMs. Infected CAM showed intracytoplasmic inclusion bodies. The CEF inoculated with FPV field isolate as well as a vaccine strain showed characteristic CPE at third passage level.

  9. Two Strains of Lymnaea stagnalis and the Progeny from Their Mating Display Differential Memory-Forming Ability on Associative Learning Tasks.

    Science.gov (United States)

    Sunada, Hiroshi; Totani, Yuki; Nakamura, Ryota; Sakakibara, Manabu; Lukowiak, Ken; Ito, Etsuro

    2017-01-01

    The pond snail Lymnaea stagnalis learns and forms long-term memory (LTM) following both operant conditioning of aerial respiratory behavior and classical conditioning of taste aversive behavior. In the present study, we examined whether there are interstrain differences in the ability to form LTM following these two types of conditioning. A strain of Lymnaea (TC1) collected in Alberta, Canada exhibits superior memory-forming ability following aerial respiratory operant conditioning compared to a laboratory-reared strain of Lymnaea from Netherlands known as the Dutch strain. We asked whether the offspring of the Canadian TC1 and Dutch snails (i.e., filial 1 (F 1 ) cross snails) would have the superior memory ability and found, rather, that their memory ability was average like the Dutch snails. That is, the Canadian TC1 snails have superior ability for LTM formation following aerial respiratory operant conditioning, but the Dutch and the generated F 1 cross have average ability for memory forming. We next examined the Canadian TC1, Dutch and F 1 cross snails for their ability to learn and form memory following conditioned taste aversion (CTA). All three populations showed similar associative CTA responses. However, both LTM formation and the ratio of good-to-poor performers in the memory retention test were much better in the Dutch snails than the Canadian TC1 and F 1 cross snails. The memory abilities of the Canadian TC1 and F 1 cross snails were average. Our present findings, therefore, suggest that snails of different strains have different memory abilities, and the F 1 cross snails do not inherit the memory ability from the smart strain. To our knowledge, there have been a limited number of studies examining differences in memory ability among invertebrate strains, with the exception of studies using mutant flies.

  10. Two Strains of Lymnaea stagnalis and the Progeny from Their Mating Display Differential Memory-Forming Ability on Associative Learning Tasks

    Directory of Open Access Journals (Sweden)

    Hiroshi Sunada

    2017-09-01

    Full Text Available The pond snail Lymnaea stagnalis learns and forms long-term memory (LTM following both operant conditioning of aerial respiratory behavior and classical conditioning of taste aversive behavior. In the present study, we examined whether there are interstrain differences in the ability to form LTM following these two types of conditioning. A strain of Lymnaea (TC1 collected in Alberta, Canada exhibits superior memory-forming ability following aerial respiratory operant conditioning compared to a laboratory-reared strain of Lymnaea from Netherlands known as the Dutch strain. We asked whether the offspring of the Canadian TC1 and Dutch snails (i.e., filial 1 (F1 cross snails would have the superior memory ability and found, rather, that their memory ability was average like the Dutch snails. That is, the Canadian TC1 snails have superior ability for LTM formation following aerial respiratory operant conditioning, but the Dutch and the generated F1 cross have average ability for memory forming. We next examined the Canadian TC1, Dutch and F1 cross snails for their ability to learn and form memory following conditioned taste aversion (CTA. All three populations showed similar associative CTA responses. However, both LTM formation and the ratio of good-to-poor performers in the memory retention test were much better in the Dutch snails than the Canadian TC1 and F1 cross snails. The memory abilities of the Canadian TC1 and F1 cross snails were average. Our present findings, therefore, suggest that snails of different strains have different memory abilities, and the F1 cross snails do not inherit the memory ability from the smart strain. To our knowledge, there have been a limited number of studies examining differences in memory ability among invertebrate strains, with the exception of studies using mutant flies.

  11. Water-limiting conditions alter the structure and biofilm-forming ability of bacterial multispecies communities in the alfalfa rhizosphere.

    Directory of Open Access Journals (Sweden)

    Pablo Bogino

    Full Text Available Biofilms are microbial communities that adhere to biotic or abiotic surfaces and are enclosed in a protective matrix of extracellular compounds. An important advantage of the biofilm lifestyle for soil bacteria (rhizobacteria is protection against water deprivation (desiccation or osmotic effect. The rhizosphere is a crucial microhabitat for ecological, interactive, and agricultural production processes. The composition and functions of bacterial biofilms in soil microniches are poorly understood. We studied multibacterial communities established as biofilm-like structures in the rhizosphere of Medicago sativa (alfalfa exposed to 3 experimental conditions of water limitation. The whole biofilm-forming ability (WBFA for rhizospheric communities exposed to desiccation was higher than that of communities exposed to saline or nonstressful conditions. A culture-dependent ribotyping analysis indicated that communities exposed to desiccation or saline conditions were more diverse than those under the nonstressful condition. 16S rRNA gene sequencing of selected strains showed that the rhizospheric communities consisted primarily of members of the Actinobacteria and α- and γ-Proteobacteria, regardless of the water-limiting condition. Our findings contribute to improved understanding of the effects of environmental stress factors on plant-bacteria interaction processes and have potential application to agricultural management practices.

  12. Biofilm forming ability of Sphingomonas paucimobilis isolated from community drinking water systems on plumbing materials used in water distribution.

    Science.gov (United States)

    Gulati, Parul; Ghosh, Moushumi

    2017-10-01

    Sphingomonas paucimobilis, an oligotroph, is well recognized for its potential for biofilm formation. The present study explored the biofilm forming ability of a strain isolated from municipal drinking water on plumbing materials. The intensity of biofilm formation of this strain on different plumbing materials was examined by using 1 × 1 cm 2 pieces of six different pipe materials, i.e. polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), aluminium (Al), copper (Cu) and rubber (R) and observing by staining with the chemical chromophore, Calcofluor. To understand whether biofilm formation occurs under flow through conditions, a laboratory-scale simulated distribution system, comprised of the above materials was fabricated. Biofilm samples were collected from the designed system at different biofilm ages (10, 40 and 90 hours old) and enumerated. The results indicated that the biofilm formation occurred on all plumbing materials with Cu and R as exceptions. The intensity of biofilm formation was found to be maximum on PVC followed by PP and PE. We also demonstrated the chemical chromophore (Calcofluor) successfully for rapid and easy visual detection of biofilms, validated by scanning electron microscope (SEM) analysis of the plumbing materials. Chlorination has little effect in preventing biofilm development.

  13. Recent advances on glass-forming systems driven far from equilibrium. Special issue marking the completion of the Research Unit FOR 1394 `Nonlinear response to probe vitrification'

    Science.gov (United States)

    Fuchs, Matthias

    2017-08-01

    The nature of the glass transition is one of the frontier questions in Statistical Physics and Materials Science. Highly cooperative structural processes develop in glass-forming melts exhibiting relaxational dynamics which is spread out over many decades in time. While considerable progress has been made in recent decades towards understanding dynamical slowing-down in quiescent systems, the interplay of glassy dynamics with external fields reveals a wealth of novel phenomena yet to be explored. This special issue focuses on recent results obtained by the Research Unit FOR 1394 `Nonlinear response to probe vitrification' which was funded by the German Science Foundation (DFG). In the projects of the research unit, strong external fields were used in order to gain insights into the complex structural and transport phenomena at the glass transition under far-from-equilibrium conditions. This aimed inter alia to test theories of the glass transition developed for quiescent systems by pushing them beyond their original regime. Combining experimental, simulational, and theoretical efforts, the eight projects within the FOR 1394 measured and determined aspects of the nonlinear response of supercooled metallic, polymeric, and silica melts, of colloidal dispersions, and of ionic liquids. Applied fields included electric and mechanic fields, and forced active probing (`micro-rheology'), where a single probe is forced through the glass-forming host. Nonlinear stress-strain and force-velocity relations as well as nonlinear dielectric susceptibilities and conductivities were observed. While the physical manipulation of melts and glasses is interesting in its own right, especially technologically, the investigations performed by the FOR 1394 suggest to use the response to strong homogeneous and inhomogeneous fields as technique to explore on the microscopic level the cooperative mechanisms in dense melts of strongly interacting constituents. Questions considered concern the

  14. Conceptual waste package interim product specifications and data requirements for disposal of borosilicate glass defense high-level waste forms in salt geologic repositories

    International Nuclear Information System (INIS)

    1983-06-01

    The conceptual waste package interim product specifications and data requirements presented are applicable specifically to the normal borosilicate glass product of the Defense Waste Processing Facility (DWPF). They provide preliminary numerical values for the defense high-level waste form parameters and properties identified in the waste form performance specification for geologic isolation in salt repositories. Subject areas treated include containment and isolation, operational period safety, criticality control, waste form/production canister identification, and waste package performance testing requirements. This document was generated for use in the development of conceptual waste package designs in salt. It will be revised as additional data, analyses, and regulatory requirements become available

  15. Self-motion and the α-relaxation in glass-forming polymers. Molecular dynamic simulation and quasielastic neutron scattering results in polyisoprene

    International Nuclear Information System (INIS)

    Colmenero, Juan; Arbe, Arantxa; Alvarez, Fernando; Monkenbusch, Michael; Richter, Dieter; Farago, Bela; Frick, Bernhard

    2003-01-01

    The momentum transfer dependence of the self-motion of main chain hydrogens in the α-relaxation regime of a glass forming polymer, polyisoprene, has been thoroughly investigated by a combined effort involving fully atomistic molecular dynamic simulations and quasielastic neutron scattering measurements. In this way, we have established the existence of a crossover from a Gaussian regime of sublinear diffusion to a strongly non-Gaussian regime at short distances. We show that an anomalous jump diffusion model with a distribution of jump lengths gives rise to such a crossover. This model leads to a time-dependent non-Gaussian parameter exhibiting all features revealed so far from various simulations of different glass forming systems

  16. Speech and language abilities of children with the familial form of 22q11.2 deletion syndrome

    Directory of Open Access Journals (Sweden)

    Rakonjac Marijana

    2016-01-01

    Full Text Available The 22q11.2 Deletion Syndrome (22q11.2DS, which encompasses Shprintzen syndrome, DiGeorge and velocardiofacial syndrome, is the most common microdeletion syndrome in humans with an estimated incidence of approximately 1/4000 per live births. After Down syndrome, it is the second most common genetic syndrome associated with congenital heart malformations. The mode of inheritance of the 22q11.2DS is autosomal dominant. In approximately 72 - 94% of the cases the deletion has occurred de novo, while in 6 to 28% of patients deletion was inherited from a parent. As a part of a multidisciplinary study we examined the speech and language abilities of members of two families with inherited form of 22q11.2DS. The presence of 22q11.2 microdeletion was revealed by fluorescence in situ hybridization (FISH and/or multiplex ligation-dependent probe amplification (MLPA. In one family we detected 1.5 Mb 22q11.2 microdeletion, while in the other family we found 3Mb microdeletion. Patients from both families showed delays in cognitive, socio-emotional, speech and language development. Furthermore, we found considerable variability in the phenotypic characteristics of 22q11.2DS and the degree of speech-language pathology not only between different families with 22q11.2 deletion, but also among members of the same family. In addition, we detected no correlation between the phenotype and the size of 22q11.2 microdeletion.

  17. Effect of Alkali-Acid-Heat Chemical Surface Treatment on Electron Beam Melted Porous Titanium and Its Apatite Forming Ability

    Directory of Open Access Journals (Sweden)

    Suzan Bsat

    2015-04-01

    Full Text Available Advanced additive manufacturing techniques such as electron beam melting (EBM, can produce highly porous structures that resemble the mechanical properties and structure of native bone. However, for orthopaedic applications, such as joint prostheses or bone substitution, the surface must also be bio-functionalized to promote bone growth. In the current work, EBM porous Ti6Al4V alloy was exposed to an alkali acid heat (AlAcH treatment to bio-functionalize the surface of the porous structure. Various molar concentrations (3, 5, 10M and immersion times (6, 24 h of the alkali treatment were used to determine optimal parameters. The apatite forming ability of the samples was evaluated using simulated body fluid (SBF immersion testing. The micro-topography and surface chemistry of AlAcH treated samples were evaluated before and after SBF testing using scanning electron microscopy and energy dispersive X-ray spectroscopy. The AlAcH treatment successfully modified the topographical and chemical characteristics of EBM porous titanium surface creating nano-topographical features ranging from 200–300 nm in size with a titania layer ideal for apatite formation. After 1 and 3 week immersion in SBF, there was no Ca or P present on the surface of as manufactured porous titanium while both elements were present on all AlAcH treated samples except those exposed to 3M, 6 h alkali treatment. An increase in molar concentration and/or immersion time of alkali treatment resulted in an increase in the number of nano-topographical features per unit area as well as the amount of titania on the surface.

  18. Selected mucolytic, anti-inflammatory and cardiovascular drugs change the ability of neutrophils to form extracellular traps (NETs).

    Science.gov (United States)

    Zawrotniak, Marcin; Kozik, Andrzej; Rapala-Kozik, Maria

    2015-01-01

    Neutrophils form the first line of host defense against infections that combat pathogens using two major mechanisms, the phagocytosis or the release of neutrophil extracellular traps (NETs). The netosis (NET formation) exerts additional, unfavorable effects on the fitness of host cells and is also involved at the sites of lung infection, increasing the mucus viscosity and in the circulatory system where it can influence the intravascular clot formation. Although molecular mechanisms underlying the netosis are still incompletely understood, a role of NADPH oxidase that activates the production of reactive oxygen species (ROS) during the initiation of NETs has been well documented. Since several commonly used drugs can affects the netosis, our current study was aimed to determine the effects of selected mucolytic, anti-inflammatory and cardiovascular drugs on NET formation, with a special emphasis on ROS production and NADPH oxidase activity. The treatment of neutrophils with N-acetylcysteine, ketoprofen and ethamsylate reduced the production of ROS by these cells in a dose-dependent manner. NET formation was also modulated by selected drugs. N-acetylcysteine inhibited the netosis but in the presence of H2O2 this neutrophil ability was restored, indicating that N-acetylcysteine may influence the NET formation by modulating ROS productivity. The administration of ethamsylate led to a significant reduction in NET formation and this effect was not restored by H2O2 or S. aureus, suggesting the unexpected additional side effects of this drug. Ketoprofen seemed to promote ROS-independent NET release, simultaneously inhibiting ROS production. The results, obtained in this study strongly suggest that the therapeutic strategies applied in many neutrophil-mediated diseases should take into account the NET-associated effects.

  19. Effect of Alkali-Acid-Heat Chemical Surface Treatment on Electron Beam Melted Porous Titanium and Its Apatite Forming Ability.

    Science.gov (United States)

    Bsat, Suzan; Yavari, Saber Amin; Munsch, Maximilian; Valstar, Edward R; Zadpoor, Amir A

    2015-04-08

    Advanced additive manufacturing techniques such as electron beam melting (EBM), can produce highly porous structures that resemble the mechanical properties and structure of native bone. However, for orthopaedic applications, such as joint prostheses or bone substitution, the surface must also be bio-functionalized to promote bone growth. In the current work, EBM porous Ti6Al4V alloy was exposed to an alkali acid heat (AlAcH) treatment to bio-functionalize the surface of the porous structure. Various molar concentrations (3, 5, 10M) and immersion times (6, 24 h) of the alkali treatment were used to determine optimal parameters. The apatite forming ability of the samples was evaluated using simulated body fluid (SBF) immersion testing. The micro-topography and surface chemistry of AlAcH treated samples were evaluated before and after SBF testing using scanning electron microscopy and energy dispersive X-ray spectroscopy. The AlAcH treatment successfully modified the topographical and chemical characteristics of EBM porous titanium surface creating nano-topographical features ranging from 200-300 nm in size with a titania layer ideal for apatite formation. After 1 and 3 week immersion in SBF, there was no Ca or P present on the surface of as manufactured porous titanium while both elements were present on all AlAcH treated samples except those exposed to 3M, 6 h alkali treatment. An increase in molar concentration and/or immersion time of alkali treatment resulted in an increase in the number of nano-topographical features per unit area as well as the amount of titania on the surface.

  20. Unusual features of long-range density fluctuations in glass-forming organic liquids: A Rayleigh and Rayleigh-Brillouin light scattering study

    International Nuclear Information System (INIS)

    Patkowski, A.; Fischer, E. W.; Steffen, W.; Glaser, H.; Baumann, M.; Ruths, T.; Meier, G.

    2001-01-01

    A new feature of glass-forming liquids, i.e., long-range density fluctuations of the order of 100 nm, has been extensively characterized by means of static light scattering, photon correlation spectroscopy and Rayleigh-Brillouin spectroscopy in orthoterphenyl (OTP) and 1,1-di(4 # prime#-methoxy-5 # prime#methyl-phenyl)-cyclohexane (BMMPC). These long-range density fluctuations result in the following unusual features observed in a light scattering experiment, which are not described by the existing theories: (i) strong q-dependent isotropic excess Rayleigh intensity, (ii) additional slow component in the polarized photon correlation function, and (iii) high Landau-Placzek ratio. These unusual features are equilibrium properties of the glass-forming liquids and depend only on temperature, provided that the sample has been equilibrated long enough. The temperature-dependent equilibration times were measured for BMMPC and are about 11 orders of magnitude longer than the α process. It was found that the glass-forming liquid OTP may occur in two states: with and without long-range density fluctuations ('clusters'). We have characterized the two states by static and dynamic light scattering in the temperature range from T g to T g +200 K. The relaxation times of the α process as well as the parameters of the Brillouin line are identical in both OTP with and without clusters. The α process (density fluctuations) in OTP was characterized by measuring either the polarized (VV) or depolarized (VH) correlation function, which are practically identical and q-independent. This feature, which is commonly observed in glass-forming liquids, is not fully explained by the existing theories

  1. Early phyllosilicates formed by alteration of R7T7 glass in water at 250 deg C

    International Nuclear Information System (INIS)

    Vernaz, E.; Dussossoy, J.L.; Caurel, J.; Crovisier, J.L.

    1991-01-01

    T7T7 glass samples have been altered during periods of one and seven days at 250 deg C in distilled water. Ultramicrotomic thin sections were performed in the outermost part of the glass for a study under analytical transmission electron microscope. After one day the alteration layer is about 5 μm thick. It is made up of sheeted silicated particles, tentatively identified as septechlorite (7 A intervals) mixed with an intercrystalline amorphous matrix of different composition. After seven days the alteration layer is about 11 μm thick. It is made up of sheeted silicated particles of smectite type (10 A intervals). No 7 A particles were found in the seven days sample. This study illustrates the capacity of poorly crystalline phyllosilicates to adapt to the chemical changes in solution. 15 refs., 4 tabs., 2 plates

  2. The Influence of Na and Ti on the In Vitro Degradation and Bioactivity in 58S Sol-Gel Bioactive Glass

    Directory of Open Access Journals (Sweden)

    Shirong Ni

    2012-01-01

    Full Text Available The aim of this study was to investigate the effect of Na and Ti on the in vitro degradation and bioactivity in the 58S bioactive glass. The degradation was evaluated through the activation energy of Si ion release from bioactive glasses and the weight loss of bioactive glasses in Tris-HCl buffer solution. The in vitro bioactivity of the bioactive glasses was investigated by analysis of apatite-formation ability in the simulated body fluid (SBF. The results showed that Na in the 58S glass accelerated the dissolution rate of the glass, whereas Ti in the 58S glass slowed down the rate of glass solubility. Bioactivity tests showed that Na in glass increased the apatite-forming ability in SBF. In contrast, Ti in glass retards the apatite formation at the initial stage of SBF soaking but does not affect the growth of apatite after long periods of soaking.

  3. Study of the glass formation of high temperature superconductors

    Science.gov (United States)

    Ethridge, Edwin C.; Kaukler, William F.; Rolin, Terry

    1992-01-01

    A number of compositions of ceramic oxide high T(sub c) superconductors were elevated for their glass formation ability by means of rapid thermal analysis during quenching, optical, and electron microscopy of the quenched samples, and with subsequent DSC measurements. Correlations between experimental measurements and the methodical composition changes identified the formulations of superconductors that can easily form glass. The superconducting material was first formed as a glass; then, with subsequent devitrification, it was formed into a bulk crystalline superconductor by a series of processing methods.

  4. Enhanced99Tc retention in glass waste form using Tc(IV)-incorporated Fe minerals

    OpenAIRE

    Um, W; Luksic, SA; Wang, G; Saslow, S; Kim, DS; Schweiger, MJ; Soderquist, CZ; Bowden, ME; Lukens, WW; Kruger, AA

    2017-01-01

    © 2017 Elsevier B.V. Technetium ( 99 Tc) immobilization by doping into iron oxide mineral phases may alleviate the problems with Tc volatility during vitrification of nuclear waste. Because reduced Tc, Tc(IV), substitutes for Fe(III) in the crystal structure by a process of Tc reduction from Tc(VII) to Tc(IV) followed by co-precipitation of Fe oxide minerals, two Tc-incorporated Fe minerals (Tc-goethite and Tc-magnetite/maghemite) were prepared and tested for Tc retention in glass melt sample...

  5. Interaction on boundary of current-conducting and glass-forming phases in cermet films under annealing

    International Nuclear Information System (INIS)

    Shulishova, O.I.; Zyrin, A.V.; Ismalgaliev, R.K.; Izmajlov, Sh.Z.; Kovylyaev, V.V.; Shevchuk, N.V.; Shcherbak, I.A.

    1990-01-01

    The electron-probe microanalysis permits investigating the interaction on the boundary of current-conducting and glass-binding phases in cermet films without noble metals on the base of ruthenium oxide. The performed studies along with experiments on model microsections subject to annealing in different media have shown the differences in the process of formation of structure and properties of cermet resistive elements as well as a significance of the oxidation process of current-conducting phase in formation of high working characteristics of cermet resistors on the base of hexaborides of the rare-earth elements

  6. Self-powdering and nonlinear optical domain structures in ferroelastic β'-Gd2(MoO4)3 crystals formed in glass

    International Nuclear Information System (INIS)

    Tsukada, Y.; Honma, T.; Komatsu, T.

    2009-01-01

    Ferroelastic β'-Gd 2 (MoO 4 ) 3 , (GMO), crystals are formed through the crystallization of 21.25Gd 2 O 3 -63.75MoO 3 -15B 2 O 3 glass (mol%), and two scientific curious phenomena are observed. (1) GMO crystals formed in the crystallization break into small pieces with a triangular prism or pyramid shape having a length of 50-500 μm spontaneously during the crystallizations in the inside of an electric furnace, not during the cooling in air after the crystallization. This phenomenon is called 'self-powdering phenomenon during crystallization' in this paper. (2) Each self-powdered GMO crystal grain shows a periodic domain structure with different refractive indices, and a spatially periodic second harmonic generation (SHG) depending on the domain structure is observed. It is proposed from polarized micro-Raman scattering spectra and the azimuthal dependence of second harmonic intensities that GMO crystals are oriented in each crystal grain and the orientation of (MoO 4 ) 2- tetrahedra in GMO crystals changes periodically due to spontaneous strains in ferroelastic GMO crystals. - Graphical abstract: This figure shows the polarized optical photograph at room temperature for a particle (piece) obtained by a heat treatment of the glass at 590 deg. C for 2 h in an electric furnace in air. This particle was obtained through the self-powdering behavior in the crystallization of glass. The periodic domain structure is observed. Ferroelastic β'-Gd 2 (MoO 4 ) 3 crystals are formed in the particle, and second harmonic generations are detected, depending on the domain structure.

  7. Effect of Ba in the glass characteristics of cesium loaded iron phosphate glasses

    International Nuclear Information System (INIS)

    Joseph, Kitheri; Asuvathraman, R.; Vasudeva Rao, P.R.

    2015-01-01

    Radioactive 137 Cs extracted from high level nuclear waste, when immobilized in a suitable matrix can be used as a γsource in medical industry. Iron phosphate glass (IPG) is one of a suitable matrix for the immobilization of 137 Cs prior to the immobilization of 137 Cs in IPG, it is essential to optimize the immobilization conditions using natural (inactive) cesium. Glass characteristics of inactive Cs loaded iron phosphate glasses were already explored in our earlier studies. However, the change in glass characteristics of 137 Cs loaded iron phosphate glass to 137 Ba loaded iron phosphate glass need to be studied before the immobilization of 137 Cs in iron phosphate glass as 137 Cs transforms to 137 Ba due to nuclear transmutation ( 137 Cs(β,γ) 137 Ba). This paper reports the studies on such a behaviour by incorporating inactive Ba in cesium loaded iron phosphate glasses. Cs and Ba loaded iron phosphate glasses were prepared by melt quench technique in air using appropriate amounts of Fe 2 O 3 , NH 4 H 2 PO 4 , Ba(OH) 2.8 H 2 O and Cs 2 CO 3 . The chemicals were added such that the glass formed possesses the batch composition of (a) 21.4 wt. % Fe 2 O 3 -45 wt. % Cs 2 O-5 wt % BaO-P 2 O 5 (henceforth referred as IP50Cs45Ba5); (b) 21.4 wt. % Fe 2 O 3 -25 wt. % Cs 2 O-25 wt % BaO-P 2 O5 (henceforth referred as IP50Cs25Ba25). The thermal expansion measurements were also carried out using a home-built quartz push-rod dilatometer. The data related to change in thermal expansion behaviour, glass forming ability, glass stability and structural changes in phosphate network due to the partial replacement of Cs with Ba will also be discussed. (author)

  8. Effect of aluminum and silicon reactants and process parameters on glass-ceramic waste form characteristics for immobilization of high-level fluorinel-sodium calcined waste

    International Nuclear Information System (INIS)

    Vinjamuri, K.

    1993-06-01

    In this report, the effects of aluminum and silicon reactants, process soak time and the initial calcine particle size on glass-ceramic waste form characteristics for immobilization of the high-level fluorinel-sodium calcined waste stored at the Idaho Chemical Processing Plant (ICPP) are investigated. The waste form characteristics include density, total and normalized elemental leach rates, and microstructure. Glass-ceramic waste forms were prepared by hot isostatically pressing (HIPing) a pre-compacted mixture of pilot plant fluorinel-sodium calcine, Al, and Si metal powders at 1050 degrees C, 20,000 psi for 4 hours. One of the formulations with 2 wt % Al was HIPed for 4, 8, 16 and 24 hours at the same temperature and pressure. The calcine particle size range include as calcined particle size smaller than 600 μm (finer than -30 mesh, or 215 μm Mass Median Diameter, MMD) and 180 μm (finer than 80 mesh, or 49 μm MMD)

  9. Conceptual waste package interim product specifications and data requirements for disposal of glass commercial high-level waste forms in salt geologic repositories

    International Nuclear Information System (INIS)

    1983-10-01

    The conceptual waste package interim product specifications and data requirements presented are applicable to the reference glass composition described in PNL-3838 and carbon steel canister described in ONWI-438. They provide preliminary numerical values for the commercial high-level waste form parameters and properties identified in the waste form performance specification for geologic isolation in salt repositories. Subject areas treated include containment and isolation, operational period safety, criticality control, waste form/production canister identification, and waste package performance testing requirements. This document was generated for use in the development of conceptual waste package designs in salt. It will be revised as additional data, analyses and regulatory requirements become available. 13 references, 1 figure

  10. Training Lymnaea in the presence of a predator scent results in a long-lasting ability to form enhanced long-term memory.

    Science.gov (United States)

    Forest, Jeremy; Sunada, Hiroshi; Dodd, Shawn; Lukowiak, Ken

    2016-06-01

    Lymnaea exposed to crayfish effluent (CE) gain an enhanced ability to form long-term memory (LTM). We test the hypothesis that a single CE exposure and operant conditioning training leads to long lasting changes in the capability of snails to form LTM when tested in pond water four weeks later. We trained both juvenile and adult snails with a single 0.5 h training session in CE and show that LTM was present 24 h later. Snails trained in a similar manner in just pond water show no LTM. We then asked if such training in CE conferred enhanced memory forming capabilities on these snails four weeks later. That is, would LTM be formed in these snails four weeks later following a single 0.5 h training session in pond water? We found that both adult and juvenile snails previously trained in CE one month previously had enhanced LTM formation abilities. The injection of a DNA methylation blocker, 5-AZA, prior to training in adult snails blocked enhanced LTM formation four weeks later. Finally, this enhanced LTM forming ability was not passed on to the next generation of snails.

  11. Effect of different glasses in glass bonded zeolite

    International Nuclear Information System (INIS)

    Lewis, M.A.; Ackerman, J.P.; Verma, S.

    1995-01-01

    A mineral waste form has been developed for chloride waste salt generated during the pyrochemical treatment of spent nuclear fuel. The waste form consists of salt-occluded zeolite powders bound within a glass matrix. The zeolite contains the salt and immobilizes the fission products. The zeolite powders are hot pressed to form a mechanically stable, durable glass bonded zeolite. Further development of glass bonded zeolite as a waste form requires an understanding of the interaction between the glass and the zeolite. Properties of the glass that enhance binding and durability of the glass bonded zeolite need to be identified. Three types of glass, boroaluminosilicate, soda-lime silicate, and high silica glasses, have a range of properties and are now being investigated. Each glass was hot pressed by itself and with an equal amount of zeolite. MCC-1 leach tests were run on both. Soda-lime silicate and high silica glasses did not give a durable glass bonded zeolite. Boroaluminosilicate glasses rich in alkaline earths did bind the zeolite and gave a durable glass bonded zeolite. Scanning electron micrographs suggest that the boroaluminosilicate glasses wetted the zeolite powders better than the other glasses. Development of the glass bonded zeolite as a waste form for chloride waste salt is continuing

  12. From beta-relaxation to alpha-decay: Atomistic picture from molecular dynamics simulations for glass-forming Ni0.5Zr0.5 melt

    Energy Technology Data Exchange (ETDEWEB)

    Teichler, Helmar [Inst. Materialphysik, Univ Goettingen (Germany)

    2013-07-01

    In glass-forming melts the decay of structural fluctuation shows the well known transition from beta-relaxation (von-Schweidler law with exponent b) to alpha-decay (KWW law with exponent beta). Here we present results from molecular dynamics simulations for a metallic glass forming Ni0.5Zr0.5 model aimed at giving an understanding of this transition on the atomistic scale. At the considered temperature below mode coupling Tc, the dynamics of the system can be interpreted by residence of the particles in their neighbour cages and escape from the cages as rare processes. Our analysis yields that the fraction of residing particles is characterized by a hierarchical law in time, with von-Schweidler b explicitly related to the exponent of this law. In the alpha-decay regime the stretching exponent reflects, in addition, floating of the cages due to strain effects of escaped particles. Accordingly, the change from beta-relaxation to alpha-decay indicates the transition from low to large fraction of escaped particles.

  13. Genetic control of the radiosensitivity of lymphoid cells for antibody-forming ability in CXS series of recombinant inbred mouse strains

    International Nuclear Information System (INIS)

    Okumoto, M.; Mori, N.; Nishikawa, R.; Imai, S.; Hilgers, J.; Takamori, Y.; Yagasaki, O.

    1992-01-01

    Incidence of radiation-induced lymphomas differs remarkably among various mouse strains. BALB/cHeA (C) mice are highly susceptible to radiation induction of lymphomas, while STS/A (S) mice are resistant. Thus, the induction of the disease is controlled by some genetic factors. To examine an involvement of radiosensitivity of lymphoid cells in lymphomagenesis, we have compared genetic control of the radiosensitivity for antibody-forming ability with that of lymphoma development in BALB/cHeA, STS/A, (CXS)F 1 hybrids and CXS series of recombinant inbred strains. Decrease of number of splenic plaque-forming cell (PFC) in Jerne's method by 3 Gy of X-irradiation for BALB/cHeA mice was larger than that for STS/A mice by more than one order of magnitude. (CXS)F 1 hybrid mice showed small number of decrease of PFC similar to STS/A mice suggesting that phenotype of radioresistance was dominant over sensitivity. The best concordance between genetic markers and radiosensitivities of antibody-forming ability in recombinant inbred strains was observed in a region containing Igh locus on chromosome 12. The results show that one locus controlling the radioresistance of lymphoid cells for antibody-forming ability might exist in the region containing Igh locus, and that this region clearly differ from a region with Ifa locus on chromosome 4 which regulate the susceptibility to radiation-induced lymphomagenesis. (author)

  14. Baseline LAW Glass Formulation Testing

    International Nuclear Information System (INIS)

    Kruger, Albert A.; Mooers, Cavin; Bazemore, Gina; Pegg, Ian L.; Hight, Kenneth; Lai, Shan Tao; Buechele, Andrew; Rielley, Elizabeth; Gan, Hao; Muller, Isabelle S.; Cecil, Richard

    2013-01-01

    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

  15. Readiness of senior higher school students for self-determination in ecology field as an ability to form subjective attitude

    Directory of Open Access Journals (Sweden)

    Titov Evgeny V.

    2016-01-01

    Full Text Available The current state of environment demands from senior pupils to occupy a correct position in problem ecological situations. An effective means of forming senior pupils’ own position is activity in a field of ecology. Through a variety of activities in the field of ecology (learning, playing, research, environmental protection, and others. senior pupils are involved in situations requiring self-determination. Self-determined senior pupils overcome a conflict, a contradiction between an individual’’s position and a social role caused by a situation arising in activity.

  16. Mechanism of stimulation of antibody-forming ability of bone marrow cells of mice immunized with staphylococci

    International Nuclear Information System (INIS)

    Lyashchenko, K.P.; Golovanova, T.A.; Bobrovnik, S.A.

    1987-01-01

    The purpose of this paper is to study the formation of the ability of the bone marrow cells of mice immunized with staphylococci to create antibodies to this antigen. The research includes a study of the effect of the irradiation in vitro of the bone marrow cells on their stimulating activity and the role played by the thymus and spleen in the formation of this activity. Experiments were carried out on CBA and BALB/c mice as well as on mice with congenital absence of the thymus. The bone marrow cell donors were immunized intravenously with staphylococcal corpuscular antigen. Receptor mice were irradiated with cobalt 60 gamma radiation and injected intravenously with bone marrow cell extract from the immunized donors and were immunized with the antigen. Spleen cells were labelled with chromium 51 and injected intravenously into intact syngeneic recipients together with as well as without the antigen. Three days later the level of radioactivity in the spleen and femora of the animals was determined by scintillation counting. Total radioactivity of the bone marrow was calculated. Irradiation of the bone marrow cells of immunized animals was shown to abolish their stimulating effect on the humoral immune response of intact syngeneic recipients to the staphylococcal corpuscular antigen. Consequently, the immunostimulating effect of bone marrow cells is realized through the proliferating and radiosensitive lymphoid cells rather than through the macrophages

  17. Raman Spectroscopy and Statistical Analysis of the Silicate Species and Group Connectivity in Cesium Silicate Glass Forming System

    Directory of Open Access Journals (Sweden)

    Armenak Osipov

    2015-01-01

    Full Text Available The Raman spectra of x%Cs2O-(100 − x%SiO2 (x=17, 22, 27, 33, and 37 mol% glasses and melts were measured in the temperature range of 293 to 1553 K. The concentrations of the Qn species were calculated as a function of the composition and temperature based on the deconvolution analysis of the spectra. It was found that a dynamic equilibrium among structural units in the melts with x>17 mol% can be described by disproportionation reaction Q3⇔Q4+Q2. The enthalpy of this reaction was found to be equal to 32 ± 6, 43 ± 8, 56 ± 10, and 52 ± 9 for x=22, 27, 33, and 37 mol%, respectively. The nonideal entropy of mixing (ΔSmix depends on the melt temperature and increases almost linearly with increasing temperature. The Qn, Q2–Q2, and Qn,ijkl distributions with x ranging from 0 to 55 mol% were modeled using experimental data for the concentrations of the Qn units.

  18. Effects of Cr-N-ZrO 2 seed layer formed on glass substrates for longitudinal recording media

    Science.gov (United States)

    Suzuki, Hiroyuki; Djayaprawira, David D.; Takahashi, Yoshio; Ishikawa, Akira; Ono, Toshinori; Yahisa, Yotsuo

    1999-03-01

    Effects of Cr-N-ZrO 2 seed layer deposited on glass substrates before the deposition of C/Co-Cr-Pt/Cr-Ti layers for longitudinal recording media have been investigated. The product of v and Is, the activation volume and the saturation magnetization per unit volume, media noise Nd and S0/ Nd, which is the half value of peak-to-peak output voltage of an isolated pulse over Nd at 11.8 kFC/mm, are evaluated. We find that vIs is decreased by adding N and ZrO 2 to Cr seed layer. Nd is reduced as vIs decreases by adding nitrogen to the Cr seed layer. This is mainly due to the decreased grain sizes of both Cr-Ti underlayer and Co-Cr-Pt magnetic layer. The Nd is further reduced by the addition of ZrO 2 to the Cr-N seed layer. Highest S0/ Nd is achieved for the media with Cr-N-ZrO 2 seed layer. On the other hand, the media with Cr-ZrO 2 seed layer deposited without nitrogen show the higher Nd. Therefore the decrease of the grain size by addition of nitrogen into Ar is essential to reduce Nd, and the ZrO 2 addition to the Cr-N seed layer seems to enhance the effect of grain size reduction by nitrogen addition.

  19. Analytical electron microscopy study of surface layers formed on the French SON68 nuclear waste glass during vapor hydration at 200 C

    International Nuclear Information System (INIS)

    Gong, W.L.; Wang, L.M.; Ewing, R.C.; Bates, J.K.; Ebert, W.L.

    1998-01-01

    Extensive solid-state characterization (AEM/SEM/HRTEM) was completed on six SON68 (inactive R7T7) waste glasses which were altered in the presence of saturated water vapor (200 C) for 22, 91, 241, 908, 1000, 1013, and 1021 days. The samples were examined by AEM in cross-section (lattice-fringe imaging, micro-diffraction, and quantitative thin-film EDS analysis). The glass monoliths were invariably covered by a thin altered rind, and the surface layer thickness increased with increasing time of reaction, ranging from 0.5 to 30 μm in thickness. Six distinctive zones, based on phase chemistry and microstructure, were distinguished within the well-developed surface layers. Numerous crystalline phases such as analcime, gyrolite, tobermorite, apatite, and weeksite were identified on the surfaces of the reacted glasses as precipitates. The majority of the surface layer volume was composed of two basic structures that are morphologically and chemically distinct: The A-domain consisted of well-crystallized fibrous smectite aggregates; and the B-domain consisted of poorly-crystallized regions containing smectite, possibly montmorillonite, crystallites and a ZrO 2 -rich amorphous silica matrix. The retention of the rare-earth elements, Mo, and Zr mostly occurred within the B-domain; while transition metal elements, such as Zn, Cr, Ni, Mn, and Fe, were retained in the A-domain. The element partitioning among A-domains and B-domains and recrystallization of the earlier-formed B-domains into the A-domain smectites were the basic processes which have controlled the chemical and structural evolution of the surface layer. The mechanism of surface layer formation during vapor hydration are discussed based on these cross-sectional AEM results. (orig.)

  20. Determination of Fragility in Organic Small Molecular Glass Forming Liquids: Comparison of Calorimetric and Spectroscopic Data and Commentary on Pharmaceutical Importance.

    Science.gov (United States)

    Chakravarty, Paroma; Pandya, Keyur; Nagapudi, Karthik

    2018-03-05

    The fragility index ( m) and conversely the strength parameter ( D) are widely used to categorize glass forming liquids and are used to characterize temperature dependency of viscosity and relaxation time as the supercooled liquid approaches glass transition. The currently used calorimetric methods in pharmaceutical literature lead to wide variability in measured values of m. In this work, a modulated differential scanning calorimetry (DSC) method is introduced that can directly determine m with minimal variability. Although calorimetric fragility is easy to measure due to availability and ease of use of DSC, there is no correlation between calorimetric and dielectric fragility (calculated spectroscopically from relaxation times). In addition, there is also no correlation between calorimetric fragility and the so-called "thermodynamic fragility" that can be calculated using only thermodynamic parameters. No relationship can be found between the crystallization propensity in the supercooled liquid state and D. However, the crystallization propensity shows a reasonable correlation with the Kohlrausch distribution parameter β k , which defines the breadth of the relaxation time distribution.

  1. On the reversibility window in binary As-Se glasses

    Energy Technology Data Exchange (ETDEWEB)

    Golovchak, R. [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202 Stryjska str., Lviv UA-79031 (Ukraine); Institute of Physics of Jan Dlugosz University, 13/15 al. Armii Krajowej, Czestochowa PL-42201 (Poland); Faculty of Physics of Opole University of Technology, 75 Ozimska str., Opole PL-45370 (Poland); Shpotyuk, O. [Lviv Scientific Research Institute of Materials of SRC ' Carat' , 202 Stryjska str., Lviv UA-79031 (Ukraine); Institute of Physics of Jan Dlugosz University, 13/15 al. Armii Krajowej, Czestochowa PL-42201 (Poland)], E-mail: shpotyuk@novas.lviv.ua; Kozdras, A. [Faculty of Physics of Opole University of Technology, 75 Ozimska str., Opole PL-45370 (Poland)

    2007-10-29

    Physical ageing effects caused by prolonged natural storage are recorded for binary As{sub x}Se{sub 1-x} glasses with 0.2{<=}x<0.4. Their origin is associated with pure 'shrinkage' of under-constrained glass networks. It is shown that only stoichiometric As{sub 2}Se{sub 3} composition, which network is formed by a so-called self-organized phase, possesses the ideal non-ageing ability.

  2. Structure, biodegradation behavior and cytotoxicity of alkali-containing alkaline-earth phosphosilicate glasses.

    Science.gov (United States)

    Kansal, Ishu; Reddy, AlluAmarnath; Muñoz, Francisco; Choi, Seong-Jun; Kim, Hae-Won; Tulyaganov, Dilshat U; Ferreira, José M F

    2014-11-01

    We report on the effect of sodium on the structure, chemical degradation and bioactivity of glasses in the CaO-MgO-SiO2-P2O5-CaF2 system. The (29)Si and (31)P magic angle spinning-nuclear magnetic resonance spectroscopy of melt-quenched glasses with varying Na2O/MgO ratios exhibit a silicate glass network with the dominance of Q(2)(Si) units and phosphorus mainly forming orthophosphate species. Sodium incorporation in the glasses did not induce a significant structural change in the silicate network, while it did influence the phosphate environment due to its lower ionic field strength in comparison with that of magnesium. The apatite forming ability of glasses has been investigated by immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1h and 7 days while their chemical degradation has been studied in Tris-HCl in accordance with ISO-10993-14. Increasing Na(+)/Mg(2+) ratio caused a decrease in the chemical durability of glasses and in the apatite forming ability especially during initial steps of interaction between glass and SBF solution. The cellular responses were observed in vitro on bulk glass samples using mouse-derived pre-osteoblastic MC3T3-E1 cell line. The preliminary study suggested that the increasing alkali-concentration in glasses led to cytotoxicity in the cell culture medium. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Equilibration and deformation of glass-forming polymers : molecular simulation via connectivity-altering Monte Carlo and scale-jumping methods

    NARCIS (Netherlands)

    Mulder, T.

    2008-01-01

    A deep understanding of the structure and dynamics of glasses poses a great challenge in soft condensed matter physics. On approaching the glass transition the molecular relaxation times in simple glass-formers are observed to grow to such an extent that these systems do not reach thermal

  4. Glass-ceramic nuclear waste forms obtained by crystallization of SiO 2-Al 2O 3-CaO-ZrO 2-TiO 2 glasses containing lanthanides (Ce, Nd, Eu, Gd, Yb) and actinides (Th): Study of the crystallization from the surface

    Science.gov (United States)

    Loiseau, P.; Caurant, D.

    2010-07-01

    Glass-ceramic materials containing zirconolite (nominally CaZrTi 2O 7) crystals in their bulk can be envisaged as potential waste forms for minor actinides (Np, Am, Cm) and Pu immobilization. In this study such matrices are synthesized by crystallization of SiO 2-Al 2O 3-CaO-ZrO 2-TiO 2 glasses containing lanthanides (Ce, Nd, Eu, Gd, Yb) and actinides (Th) as surrogates. A thin partially crystallized layer containing titanite and anorthite (nominally CaTiSiO 5 and CaAl 2Si 2O 8, respectively) growing from glass surface is also observed. The effect of the nature and concentration of surrogates on the structure, the microstructure and the composition of the crystals formed in the surface layer is presented in this paper. Titanite is the only crystalline phase able to significantly incorporate trivalent lanthanides whereas ThO 2 precipitates in the layer. The crystal growth thermal treatment duration (2-300 h) at high temperature (1050-1200 °C) is shown to strongly affect glass-ceramics microstructure. For the system studied in this paper, it appears that zirconolite is not thermodynamically stable in comparison with titanite growing form glass surface. Nevertheless, for kinetic reasons, such transformation (i.e. zirconolite disappearance to the benefit of titanite) is not expected to occur during interim storage and disposal of the glass-ceramic waste forms because their temperature will never exceed a few hundred degrees.

  5. The Relationship between Intrinsic Couplings of the Visual Word Form Area with Spoken Language Network and Reading Ability in Children and Adults

    Directory of Open Access Journals (Sweden)

    Yu Li

    2017-06-01

    Full Text Available Reading plays a key role in education and communication in modern society. Learning to read establishes the connections between the visual word form area (VWFA and language areas responsible for speech processing. Using resting-state functional connectivity (RSFC and Granger Causality Analysis (GCA methods, the current developmental study aimed to identify the difference in the relationship between the connections of VWFA-language areas and reading performance in both adults and children. The results showed that: (1 the spontaneous connectivity between VWFA and the spoken language areas, i.e., the left inferior frontal gyrus/supramarginal gyrus (LIFG/LSMG, was stronger in adults compared with children; (2 the spontaneous functional patterns of connectivity between VWFA and language network were negatively correlated with reading ability in adults but not in children; (3 the causal influence from LIFG to VWFA was negatively correlated with reading ability only in adults but not in children; (4 the RSFCs between left posterior middle frontal gyrus (LpMFG and VWFA/LIFG were positively correlated with reading ability in both adults and children; and (5 the causal influence from LIFG to LSMG was positively correlated with reading ability in both groups. These findings provide insights into the relationship between VWFA and the language network for reading, and the role of the unique features of Chinese in the neural circuits of reading.

  6. Optical properties of alkaline earth borate glasses

    African Journals Online (AJOL)

    user

    ... devices; radiation shields, surgical lasers and their glass ceramic counter ... Alkaline earth oxides improve glass forming capability while heavy metal ... reports on optical properties of MO-B2O3 glasses containing alkaline earth oxides.

  7. Properties of gallium lanthanum sulphide glass

    OpenAIRE

    Bastock, P.; Craig, C.; Khan, K.; Weatherby, E.; Yao, J.; Hewak, D.W.

    2015-01-01

    A series of gallium lanthanum sulphide (GLS) glasses has been studied in order to ascertain properties across the entire glass forming region. This is the first comprehensive study of GLS glass over a wide compositional range.

  8. Development and psychometric characteristics of the SCI-QOL Ability to Participate and Satisfaction with Social Roles and Activities item banks and short forms.

    Science.gov (United States)

    Heinemann, Allen W; Kisala, Pamela A; Hahn, Elizabeth A; Tulsky, David S

    2015-05-01

    To develop a spinal cord injury (SCI)-focused version of PROMIS and Neuro-QOL social domain item banks; evaluate the psychometric properties of items developed for adults with SCI; and report information to facilitate clinical and research use. We used a mixed-methods design to develop and evaluate Ability to Participate in Social Roles and Activities and Satisfaction with Social Roles and Activities items. Focus groups helped define the constructs; cognitive interviews helped revise items; and confirmatory factor analysis and item response theory methods helped calibrate item banks and evaluate differential item functioning related to demographic and injury characteristics. Five SCI Model System sites and one Veterans Administration medical center. The calibration sample consisted of 641 individuals; a reliability sample consisted of 245 individuals residing in the community. A subset of 27 Ability to Participate and 35 Satisfaction items demonstrated good measurement properties and negligible differential item functioning related to demographic and injury characteristics. The SCI-specific measures correlate strongly with the PROMIS and Neuro-QOL versions. Ten item short forms correlate >0.96 with the full banks. Variable-length CATs with a minimum of 4 items, variable-length CATs with a minimum of 8 items, fixed-length CATs of 10 items, and the 10-item short forms demonstrate construct coverage and measurement error that is comparable to the full item bank. The Ability to Participate and Satisfaction with Social Roles and Activities CATs and short forms demonstrate excellent psychometric properties and are suitable for clinical and research applications.

  9. Structural and morphological studies lead borate glasses by melt quenching technique

    International Nuclear Information System (INIS)

    Jetruth Mary Alphonsa, K.; Sumathi, T.

    2013-01-01

    The studies of oxide glasses have gained attention due to their structural features. This type of glass has some remarkable features such as low melting temperature, impressive wide glass formation region, high resistance against devitrification and high refractive index. 60B 2 O 3 -(30-x) PbO-xK 2 O/Li 2 O glasses were prepared using the melt quenching technique because of its rapid glass forming ability. The amorphous nature of the prepared glass samples were confirmed by XRD (X-Ray diffraction technique) and SEM (Scanning Electron Microscopy). The quantitative analysis has been carried out in order to obtain more information about the structure of these glasses using FT-IR (Fourier transform infrared spectroscopy). (author)

  10. 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

  11. Characterization of HLW glass samples Task 3 Characterization of radioactive waste forms a series of final reports (1985-89) No 20

    International Nuclear Information System (INIS)

    Malow, G.; Behrend, U.; Schubert, P.

    1991-01-01

    Due to a delay in the melting of the highly radioactive SON68 glass, a short-term post-investigation of the highly radioactive glass from the Pamela plant in Mol (Belgium) has been carried out, the aim being a check-up of the active LEWC glass SM 513 LW11. The results were compared with those obtained for non-radioactive glass samples. The final report of the present CEC programme shortly describes the planned investigations of the glass R7T7 for the whole period of the research contract and the results of the short-term post-investigation of the Pamela glass. 11 refs.; 9 figs.; 4 tabs

  12. Photoreactivation of ultraviolet light-induced damage in cultured fish cells as revealed by increased colony forming ability and decreased content of pyrimidine dimers

    International Nuclear Information System (INIS)

    Shima, A.; Ikenaga, M.; Egami, N.

    1981-01-01

    Cultured cells derived from a goldfish were irradiated with 254 nm ultraviolet light. Cell survival and splitting of pyrimidine dimers after photoreactivation treatment with white fluorescent lamps were examined by colony forming ability and by a direct dimer assay, respectively. When UV-irradiated (5 J/m 2 ) cells were illuminated by photoreactivating light, cell survival was enhanced up to a factor of 9(40 min) followed by a decline after prolonged exposures. Exposure of UV-irradiated (15 J/m 2 ) cells to radiation from white fluorescent lamps reduced the amounts of thymine-containing dimers in a photoreactivating fluence dependent manner, up to about 60% reduction at 120 min exposure. Keeping UV-irradiated cells in the dark for up to 120 min did not affect either cell survival or the amount of pyrimidine dimers in DNA, indicating that there were not detectable levels of a dark-repair system in the cells under our conditions. Correlation between photoreactivation of colony forming ability and photoreactivation of the pyrimidine dimers was demonstrated, at least at relatively low fluences of photoreactivating light. (author)

  13. Photoreactivation of ultraviolet light-induced damage in cultured fish cells as revealed by increased colony forming ability and decreased content of pyrimidine dimers

    Energy Technology Data Exchange (ETDEWEB)

    Shima, A. (Shiga University of Medical Science, Otsu (Japan)); Ikenaga, M. (Osaka Univ. (Japan). Faculty of Medicine); Nikaido, O.; Takebe, H. (Kyoto Univ. (Japan)); Egami, N. (Tokyo Univ. (Japan). Faculty of Science)

    1981-03-01

    Cultured cells derived from a goldfish were irradiated with 254 nm ultraviolet light. Cell survival and splitting of pyrimidine dimers after photoreactivation treatment with white fluorescent lamps were examined by colony forming ability and by a direct dimer assay, respectively. When UV-irradiated (5 J/m/sup 2/) cells were illuminated by photoreactivating light, cell survival was enhanced up to a factor of 9(40 min) followed by a decline after prolonged exposures. Exposure of UV-irradiated (15 J/m/sup 2/) cells to radiation from white fluorescent lamps reduced the amounts of thymine-containing dimers in a photoreactivating fluence dependent manner, up to about 60% reduction at 120 min exposure. Keeping UV-irradiated cells in the dark for up to 120 min did not affect either cell survival or the amount of pyrimidine dimers in DNA, indicating that there were not detectable levels of a dark-repair system in the cells under our conditions. Correlation between photoreactivation of colony forming ability and photoreactivation of the pyrimidine dimers was demonstrated, at least at relatively low fluences of photoreactivating light.

  14. Micrometer and nanometer scale photopatterning of proteins on glass surfaces by photo-degradation of films formed from oligo(ethylene glycol) terminated silanes.

    Science.gov (United States)

    Tizazu, Getachew; el Zubir, Osama; Patole, Samson; McLaren, Anna; Vasilev, Cvetelin; Mothersole, David J; Adawi, Ali; Hunter, C Neil; Lidzey, David G; Lopez, Gabriel P; Leggett, Graham J

    2012-12-01

    Exposure of films formed by the adsorption of oligo(ethylene glycol) (OEG) functionalized trichlorosilanes on glass to UV light from a frequency-doubled argon ion laser (244 nm) causes photodegradation of the OEG chain. Although the rate of degradation is substantially slower than for monolayers of OEG terminated thiolates on gold, it is nevertheless possible to form micrometer-scale patterns by elective adsorption of streptavidin to exposed regions. A low density of aldehyde functional groups is produced, and this enables derivatization with nitrilotriacetic acid via an amine linker. Complexation with nickel enables the site-specific immobilization of histidine-tagged yellow and green fluorescent proteins. Nanometer-scale patterns may be fabricated using a Lloyd's mirror interferometer, with a sample and mirror set at right angles to each other. At low exposures, partial degradation of the OEG chains does not remove the protein-resistance of the surface, even though friction force microscopy reveals the formation of patterns. At an exposure of ca. 18 J cm(-2), the modified regions became adhesive to proteins in a narrow region ca. 30 nm (λ/8) wide. As the exposure is increased further the lines quickly broaden to ca. 90 nm. Adjustment of the angle between the sample and mirror enables the fabrication of lines of His-tagged green fluorescent protein at a period of 340 nm that could be resolved using a confocal microscope.

  15. In Vitro Screening of the Apatite-Forming Ability, Biointeractivity and Physical Properties of a Tricalcium Silicate Material for Endodontics and Restorative Dentistry

    Directory of Open Access Journals (Sweden)

    Maria Giovanna Gandolfi

    2013-12-01

    Full Text Available Aim: Calcium silicate-based materials are hydraulic self-setting materials with physico-chemical properties suitable for endodontic surgery and good biological/clinical outcomes. The study aim was to evaluate the bio-properties (biointeractivity and apatite-forming ability and selected physical properties (porosity, water sorption, solubility, and setting time of Biodentine, a tricalcium silicate material for endodontics and restorative dentistry, compared to that of ProRoot MTA (Mineral Trioxide Aggregate as gold standard material. Methods: Biodentine and ProRoot MTA pastes were prepared and analyzed for calcium release and alkalinizing activity (3 h–28 days, setting time, water sorption, porosity, solubility, surface microstructure and composition, and apatite-forming ability in simulated body fluid. Results: Biodentine showed higher calcium release, alkalinizing activity, and solubility but higher open and apparent porosity, water sorption, and a markedly shorter setting time. Calcium phosphate (CaP deposits were noted on material surfaces after short ageing times. A CaP coating composed of spherulites was detected after 28 days. The thickness, continuity, and Ca/P ratio of the coating differed markedly between the materials. Biodentine showed a coating composed by denser but smaller spherulites, while ProRoot MTA showed large but less dense aggregates of spherulitic deposits. Conclusions: Biodentine showed a pronounced ability to release calcium and extended alkalinizing activity interlinked with its noticeable porosity, water sorption, and solubility: open porosities provide a broad wet biointeractive surface for the release of the calcium and hydroxyl ions involved in the formation of a CaP mineral. Biodentine is a biointeractive tricalcium silicate material with interesting chemical-physical properties and represents a fast-setting alternative to the conventional calcium silicate MTA-like cements.

  16. Evaluation of the biofilm forming ability and its associated genes in Staphylococcus species isolates from bovine mastitis in Argentinean dairy farms.

    Science.gov (United States)

    Felipe, Verónica; Morgante, Carolina A; Somale, Paola S; Varroni, Florencia; Zingaretti, María L; Bachetti, Romina A; Correa, Silvia G; Porporatto, Carina

    2017-03-01

    Staphylococcus aureus and coagulase-negative staphylococci (CNS) are important causes of intramammary infection in dairy cattle, and their ability to produce biofilm is considered an important virulence property in the pathogenesis of mastitis. However, the published date on mechanisms and factors involved in infection persistence in the mammary gland remains unclear. The aim of this study was to investigate whether the main Staphylococcus species involved in bovine intramammary infections possess specific characteristics that promote colonization of the udder. We evaluated the biofilm-forming ability and distribution of adhesion- and biofilm-associated genes of Staphylococcus spp. isolated from bovine mastitis infected animals in Argentinean dairy farms. For this purpose, the phenotypic biofilm formation ability of 209 Staphylococcus spp. from bovine mastitis was investigated. All isolates produced biofilm in vitro, being 35,0% and 45,0% of the 127 S. aureus or 51,0% and 29,0% of the 82 CNS strong and moderate biofilm producers respectively. All S. aureus samples were PCR-positive for icaA, icaD, clfA, clfB and fnbpA genes, 76.3% were positive for fnbpB gene and 11.0% were positive for bap gene. In CNS isolates, the positive rates for icaA and icaD were 73.2%, while for clfA, clfB, fnbpA fnbpB and bap genes the percentage were lower. The results demonstrate that in Staphylococcus spp. biofilm formation, the polysaccharide and the adhesion- and biofilm-associated genes are of overall importance on bovine mastitis in Argentina. Therefore, future works should focus on these pathogenic specific factors for the development of more effective therapies of control, being essential to consider the ability of isolates to produce biofilm. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Yeast Ivy1p Is a Putative I-BAR-domain Protein with pH-sensitive Filament Forming Ability in vitro.

    Science.gov (United States)

    Itoh, Yuzuru; Kida, Kazuki; Hanawa-Suetsugu, Kyoko; Suetsugu, Shiro

    2016-01-01

    Bin-Amphiphysin-Rvs161/167 (BAR) domains mold lipid bilayer membranes into tubules, by forming a spiral polymer on the membrane. Most BAR domains are thought to be involved in forming membrane invaginations through their concave membrane binding surfaces, whereas some members have convex membrane binding surfaces, and thereby mold membranes into protrusions. The BAR domains with a convex surface form a subtype called the inverse BAR (I-BAR) domain or IRSp53-MIM-homology domain (IMD). Although the mammalian I-BAR domains have been studied, those from other organisms remain elusive. Here, we found putative I-BAR domains in Fungi and animal-like unicellular organisms. The fungal protein containing the putative I-BAR-domain is known as Ivy1p in yeast, and is reportedly localized in the vacuole. The phylogenetic analysis of the I-BAR domains revealed that the fungal I-BAR-domain containing proteins comprise a distinct group from those containing IRSp53 or MIM. Importantly, Ivy1p formed a polymer with a diameter of approximately 20 nm in vitro, without a lipid membrane. The filaments were formed at neutral pH, but disassembled when pH was reverted to basic. Moreover, Ivy1p and the I-BAR domain expressed in mammalian HeLa cells was localized at a vacuole-like structure as filaments as revealed by super-resolved microscopy. These data indicate the pH-sensitive polymer forming ability and the functional conservation of Ivy1p in eukaryotic cells.

  18. Antibiotic resistance, ability to form biofilm and susceptibility to copper alloys of selected staphylococcal strains isolated from touch surfaces in Polish hospital wards

    Directory of Open Access Journals (Sweden)

    Anna Różańska

    2017-08-01

    Full Text Available Abstract Background Despite the employment of sanitary regimes, contact transmission of the aetiological agents of hospital infections is still exceedingly common. The issue of microbe transmission becomes particularly important when facing multidrug-resistant microorganisms such as methicillin-resistant staphylococci. In the case of deficiencies in cleaning and disinfection procedures, hospital equipment made of copper alloys can play an important role, complementing traditional hospital hygiene procedures. The objective of this study was to characterize staphylococcal strains isolated from touch surfaces in Polish hospital wards in terms of their drug resistance, ability to form biofilm and susceptibility to antimicrobial activity of copper alloys. Methods The materials for the study were 95 staphylococcal strains isolated from touch surfaces in 13 different hospital wards from Małopolska province (the south of Poland. Phenotypic and genotypic antibiotic resistance were checked for erythromycin, clindamycin, gentamycin, ciprofloxacin, trimethoprim/sulfamethoxazole and mupirocin. Biofilm formation ability for the tested strains was checked with the use of culture on Congo red agar. Susceptibility to copper, tin bronze, brass and new silver was tested using a modification of the Japanese standard. Results Over 67% of the analysed staphylococcal strains were methicillin-resistant (MR. Four strains were resistant to all of the tested antibiotics, and 14 were resistant to all except mupirocin. Strains classified as MR had significantly increased resistance to the remaining antibiotic groups. About one-third of the analysed strains revealed biofilm-forming ability. Among the majority of species, biofilm-forming and non-biofilm-forming strains were distributed evenly; in the case of S. haemolyticus only, negative strains accounted for 92.8%. Susceptibility to copper alloys was different between strains and rather lower than in the case of the SA

  19. Glass formability of high T(sub c) Bi-Sr-Ca-Cu-O superconductors

    Science.gov (United States)

    Kaukler, William F.

    1992-01-01

    A number of compositions of ceramic oxide high T(sub c) superconductors were evaluated for their glass formation ability by means of rapid thermal analysis during quenching, optical and electron microscopy of the quenched samples, and with subsequent DSC measurements. Correlations between experimental measurements and the methodical composition changes identified the formulations of superconductors that can easily form glass. The superconducting material was first formed as a glass, then with subsequent devitrification it was formed into bulk crystalline superconductor by a series of processing methods.

  20. 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.

  1. Crystallization in lead tungsten fluorophosphate glasses

    International Nuclear Information System (INIS)

    Nardi, R.P.R.D.; Braz, C.E.; Cassanjes, F.C.; Poirier, G.

    2014-01-01

    The glass forming ability was investigated in the ternary system NaPO 3 -WO 3 -PbF 2 with a constant NaPO 3 /WO 3 ratio of 3/2 and increasing amounts of PbF 2 . It has been found that glass samples can be obtained from PbF 2 contents from 0 mole% to 60 mole%. The most lead fluoride concentrated samples (50% and 60%) were chosen for a crystallization study in order to investigate the possibility of obtaining glass-ceramics containing crystalline lead fluoride. DSC measurements allowed to determine the characteristic temperatures such as Tg, Tx, Tp and Tf. These glass samples were heat-treated near the crystallization peaks observed by thermal analysis. X-ray diffraction results of these heat-treated glasses pointed out that the dominant phase which precipitates from the glass sample containing 50% of PbF 2 is the lead fluorophosphates phase Pb 5 F(PO 4 ) 3 whereas the sample containing 60% of PbF 2 exhibits a preferential crystallization of cubic lead fluoride β-PbF 2 . (author)

  2. Crystallization in lead tungsten fluorophosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Nardi, R.P.R.D.; Braz, C.E.; Cassanjes, F.C.; Poirier, G., E-mail: gael.poirier@unifal-mg.edu.br [Universidade Federal de Alfenas (UNIFAL), Pocos de Caldas, MG (Brazil). Instituto de Ciencia e Tecnologia

    2014-07-01

    The glass forming ability was investigated in the ternary system NaPO{sub 3}-WO{sub 3}-PbF{sub 2} with a constant NaPO{sub 3}/WO{sub 3} ratio of 3/2 and increasing amounts of PbF{sub 2}. It has been found that glass samples can be obtained from PbF{sub 2} contents from 0 mole% to 60 mole%. The most lead fluoride concentrated samples (50% and 60%) were chosen for a crystallization study in order to investigate the possibility of obtaining glass-ceramics containing crystalline lead fluoride. DSC measurements allowed to determine the characteristic temperatures such as Tg, Tx, Tp and Tf. These glass samples were heat-treated near the crystallization peaks observed by thermal analysis. X-ray diffraction results of these heat-treated glasses pointed out that the dominant phase which precipitates from the glass sample containing 50% of PbF{sub 2} is the lead fluorophosphates phase Pb{sub 5}F(PO{sub 4}){sub 3} whereas the sample containing 60% of PbF{sub 2} exhibits a preferential crystallization of cubic lead fluoride β-PbF{sub 2}. (author)

  3. Loss of the ability to generate large burst-forming unit-like megakaryocytic colonies from thawed cord blood in semisolid cultures after short term suspension culture.

    Science.gov (United States)

    Eskola, M; Bäckman, S; Möttönen, S; Kekomäki, R

    2015-04-01

    Total colony-forming cells from thawed cord blood units (CBUs) include megakaryocytic colony-forming units (CFU-Mks), which survive the freezing process. The aim of this study was to evaluate whether different megakaryocytic progenitors from unseparated CBUs survive the freezing process and a short-term liquid culture. Thawed samples of CBUs were cultured in liquid medium. During the cultures, serial samples were drawn to assess the growth of different megakaryocytic progenitors in a semisolid collagen medium with identical cytokines as in the liquid medium. Megakaryocytic cells were detected using immunohistochemistry and flow cytometry. In suspension culture, the megakaryocytic progenitors almost completely lost the ability to generate large (burst-forming unit-like, BFU-like) megakaryocytic colonies in semisolid cultures (large colonies, median count per chamber d0: 7.25 vs. d7: 1.5; P culture in suspension resulted in the decline of small colonies as well (d7: 16.0 vs. d14: 5.75; P = 0.0088). Total CFU-Mk count declined from 23.3 (range 12.5-34.0) at d0 to 7.25 (range 1.0-13.5) at d14 (P culture after a short suspension culture. Small CFU-Mks were observed throughout the cultures. It may be that the BFU-Mk colonies matured and acquired CFU-Mk behaviour. © 2014 International Society of Blood Transfusion.

  4. Mechanical spectra of glass-forming liquids. II. Gigahertz-frequency longitudinal and shear acoustic dynamics in glycerol and DC704 studied by time-domain Brillouin scattering

    DEFF Research Database (Denmark)

    Klieber, Christoph; Hecksher, Tina; Pezeril, Thomas

    2013-01-01

    This paper presents and discusses the temperature and frequency dependence of the longitudinal and shear viscoelastic response at MHz and GHz frequencies of the intermediate glass former glycerol and the fragile glass former tetramethyl-tetraphenyl-trisiloxane (DC704). Measurements were performed...

  5. On the reversibility window in binary As-Se glasses

    International Nuclear Information System (INIS)

    Golovchak, R.; Shpotyuk, O.; Kozdras, A.

    2007-01-01

    Physical ageing effects caused by prolonged natural storage are recorded for binary As x Se 1-x glasses with 0.2≤x 2 Se 3 composition, which network is formed by a so-called self-organized phase, possesses the ideal non-ageing ability

  6. Involvement of AmpG in mediating a dynamic relationship between serine beta-lactamase induction and biofilm-forming ability of Escherichia coli.

    Science.gov (United States)

    Mallik, Dhriti; Pal, Shilpa; Ghosh, Anindya S

    2018-04-01

    AmpG permease is implicated both in beta-lactamase induction and peptidoglycan recycling in enterobacterial isolates. Here, physiological studies using molecular genetics show that deletion of AmpG permease dramatically increases beta-lactam susceptibility even in the presence of AmpC, TEM-1 and OXA beta-lactamases. Also, there is an appreciable decrease in the biofilm-forming ability of strains lacking this protein. Expression of this permease in excess probably compromises the integrity of the bacterial cells, leading to cell lysis. Based on these results, we propose that AmpG permease may be used as a potential antibiotic target and its suppression could efficiently inhibit both beta-lactamase induction and biofilm formation.

  7. Research of level of formed knowledge, abilities and skills on basket-ball for the students of faculty of physical education.

    Directory of Open Access Journals (Sweden)

    Kovalenko J.A.

    2011-06-01

    Full Text Available The results of a zero control of students of faculty of physical education are presented. The estimation of theoretical knowledge's is conducted, abilities and skills on basket-ball for the students of a 1 course of directions of preparation «Physical education», «Health of man» and «Sport». It is set that the level of their formed at most students of different directions of preparation is insufficient. It is certain that by reason of such position, foremost, there is insufficient preparation and playing practice of students during teaching at general school. A diary is developed on basket-ball for student general schools.

  8. Effect of poly-A:U, dextran sulfate and yeast RNA on the bone marrow colony-forming ability in irradiated mice

    International Nuclear Information System (INIS)

    Chernyavskij, V.I.; Lysenko, A.I.; Kulakova, G.S.

    1977-01-01

    It has been shown, that poly-A:U, dextran sulfate and yeast RNA increased a number of endogenic colonies (COE) in the mouse spleen sublethally irradiated, as a result of, apparently, their mitogenic effect on proliferous COE. The preparations did not affect the number of exogenic colonies when introducting them together with transfer of syngenic cells of bone marrow, taken from the intact donors. Dextran sulfate increased 2.7 times the number of the endogenic colonies in the spleens of nonuniformly irradiated mice mainly due to the COE migration from protected bone marrow areas. The complex of poly-A:U and yest RNA in such experiment type were ineffective. One of the most important factors in the mechanism of the dextran sulfate adjuvant activity possibly is its ability to increase migration potencies of the stem blood-forming cells

  9. Effect of barbiturates on radiosensitivity of cells: a comparative study of electrophoretic mobility, colony forming ability and thymidine uptake on human amnion cells

    International Nuclear Information System (INIS)

    Lalwani, N.D.; Chaubal, K.A.

    1980-01-01

    Suspensions of human amnion cells were 60 Co γ-irradiated in the presence of phenobarbital or thiobarbital (50 μg/ml). The barbiturates protected the cells against the dose-dependent reduction in electrophoretic mobility (EPM) observed 4 hours after irradiation of untreated cells, although there was an initial decrease in the EPM of treated cells followed by recovery. Treated irradiated cells exhibited greater colony-forming ability than the untreated cells. Pentobarbital and phenobarbital had similar effects, but thiobarbital was not so effective. 3 H-TdR uptake increased within 4 hours of irradiation for the treated cells. The reproductive capacity of the cells was retained at doses as high as 500 rad. The results are discussed with reference to the effects of anaesthetics on cell membranes. (U.K.)

  10. Silicate glasses. Chapter 1

    International Nuclear Information System (INIS)

    Lutze, W.

    1988-01-01

    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 glass. A historical overview of waste form development programs in nine countries is followed by a summary of the design criteria for borosilicate glass compositions glass compositions. In the sections on glass properties the waste form is characterized in terms of potential alterations under the influence of heat, thermal gradients, radiation, aqueous solutions and combinations thereof. The topics are phase transformations, mechanical properties, radiation effects and chemical durability. The results from studies of volcanic glasses, as natural analogues for borosilicate nuclear waste glasses in order to verify predictions obtained from short-term tests in the laboratory, have been compiled in a special section on natural analogues. A special section on advanced vitrification techniques summarizes the various actual and potential processing schemes and describes the facilities. The literature has been considered until 1985. (author). 430 refs.; 68 figs.; 29 tabs

  11. 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.

  12. Transition from Arrhenius to non-Arrhenius temperature dependence of structural relaxation time in glass-forming liquids: continuous versus discontinuous scenario.

    Science.gov (United States)

    Popova, V A; Surovtsev, N V

    2014-09-01

    The temperature dependences of α relaxation time τ(α)(T) of three glass-forming liquids (salol, o-terphenyl, and α-picoline) were investigated by a depolarized light scattering technique. A detailed description of τ(α)(T) near T(A), the temperature of the transition from the Arrhenius law at high temperatures to a non-Arrhenius behavior of τ(α)(T) at lower temperatures, was done. It was found that this transition is quite sharp. If the transition is described as switching from the Arrhenius law to the Vogel-Fulcher-Tammann law, it occurs within the temperature range of about 15 K or less. Most of the known expressions for τ(α)(T) cannot describe this sharp transition. Our analysis revealed that this transition can be described either as a discontinuous transition in the spirit of the frustration-limited domain theory [D. Kivelson, G. Tarjus, X. Zhao, and S. A. Kivelson, Phys. Rev. E 53, 751 (1996)], implying a phase transition, or by a phenomenological expression recently suggested [B. Schmidtke, N. Petzold, R. Kahlau, M. Hofmann, and E. A. Rössler, Phys. Rev. E 86, 041507 (2012)], where the activation energy includes the term depending exponentially on temperature.

  13. Teaching Form as Form

    DEFF Research Database (Denmark)

    Keiding, Tina Bering

    2012-01-01

    understanding of form per se, or, to use an expression from this text, of form as form. This challenge can be reduced to one question: how can design teaching support students in achieving not only the ability to recognize and describe different form-related concepts in existing design (i.e. analytical...

  14. 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.

  15. Direct conversion of plutonium-containing materials to borosilicate glass for storage or disposal

    International Nuclear Information System (INIS)

    Forsberg, C.W.; Beahm, E.C.

    1995-01-01

    A new process, the Glass Material Oxidation and Dissolution System (GMODS), has been invented for the direct conversion of plutonium metal, scrap, and residue into borosilicate glass. The glass should be acceptable for either the long-term storage or disposition of plutonium. Conversion of plutonium from complex chemical mixtures and variable geometries into homogeneous glass (1) simplifies safeguards and security; (2) creates a stable chemical form that meets health, safety, and environmental concerns; (3) provides an easy storage form; (4) may lower storage costs; and (5) allows for future disposition options. In the GMODS process, mixtures of metals, ceramics, organics, and amorphous solids containing plutonium are fed directly into a glass melter where they are directly converted to glass. Conventional glass melters can accept materials only in oxide form; thus, it is its ability to accept materials in multiple chemical forms that makes GMODS a unique glass making process. Initial proof-of-principle experiments have converted cerium (plutonium surrogate), uranium, stainless steel, aluminum, and other materials to glass. Significant technical uncertainties remain because of the early nature of process development

  16. Molecular Insight into Human Lysozyme and Its Ability to Form Amyloid Fibrils in High Concentrations of Sodium Dodecyl Sulfate: A View from Molecular Dynamics Simulations.

    Directory of Open Access Journals (Sweden)

    Majid Jafari

    Full Text Available Changes in the tertiary structure of proteins and the resultant fibrillary aggregation could result in fatal heredity diseases, such as lysozyme systemic amyloidosis. Human lysozyme is a globular protein with antimicrobial properties with tendencies to fibrillate and hence is known as a fibril-forming protein. Therefore, its behavior under different ambient conditions is of great importance. In this study, we conducted two 500000 ps molecular dynamics (MD simulations of human lysozyme in sodium dodecyl sulfate (SDS at two ambient temperatures. To achieve comparative results, we also performed two 500000 ps human lysozyme MD simulations in pure water as controls. The aim of this study was to provide further molecular insight into all interactions in the lysozyme-SDS complexes and to provide a perspective on the ability of human lysozyme to form amyloid fibrils in the presence of SDS surfactant molecules. SDS, which is an anionic detergent, contains a hydrophobic tail with 12 carbon atoms and a negatively charged head group. The SDS surfactant is known to be a stabilizer for helical structures above the critical micelle concentration (CMC [1]. During the 500000 ps MD simulations, the helical structures were maintained by the SDS surfactant above its CMC at 300 K, while at 370 K, human lysozyme lost most of its helices and gained β-sheets. Therefore, we suggest that future studies investigate the β-amyloid formation of human lysozyme at SDS concentrations above the CMC and at high temperatures.

  17. Evaluation of the ability of commercial wine yeasts to form biofilms (mats) and adhere to plastic: implications for the microbiota of the winery environment.

    Science.gov (United States)

    Tek, Ee Lin; Sundstrom, Joanna F; Gardner, Jennifer M; Oliver, Stephen G; Jiranek, Vladimir

    2018-02-01

    Commercially available active dried wine yeasts are regularly used by winemakers worldwide to achieve reliable fermentations and obtain quality wine. This practice has led to increased evidence of traces of commercial wine yeast in the vineyard, winery and uninoculated musts. The mechanism(s) that enables commercial wine yeast to persist in the winery environment and the influence to native microbial communities on this persistence is poorly understood. This study has investigated the ability of commercial wine yeasts to form biofilms and adhere to plastic. The results indicate that the biofilms formed by commercial yeasts consist of cells with a combination of different lifestyles (replicative and non-replicative) and growth modes including invasive growth, bud elongation, sporulation and a mat sectoring-like phenotype. Invasive growth was greatly enhanced on grape pulp regardless of strain, while adhesion on plastic varied between strains. The findings suggest a possible mechanism that allows commercial yeast to colonise and survive in the winery environment, which may have implications for the indigenous microbiota profile as well as the population profile in uninoculated fermentations if their dissemination is not controlled. © FEMS 2018. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Effect of X-Rays on Growth Rate of Rose Shoot Cultures and the Ability of Isolated Protoplasts to Form Cell Colonies

    International Nuclear Information System (INIS)

    Moustafa, R. A. K.

    2004-01-01

    The popularity of rose as a garden plant, allied with its use in the production of cut flowers and also as a source of aromatic rose oils, make it one of the most important ornamental crops. Roses, however, have suffered from a narrow genetic base to which only few species have contributed significantly. In vitro culture of plants might facilitate the improvement of rose via the exploitation of somaclonal variation to generate new genetic variability and selection within the variation for desirable traits. The application of mutagens for in vitro cultures, in addition to the induced mutations, may lead to increase the somaclonal variation, thus providing additional variation for selection. On the other hand, plant protoplasts offer exciting possibilities to establish in vitro selection programs based on single cells. Induced variation in isolated protoplasts using mutagen agents may be one mean to select useful mutants. Thus the present experiments were conducted to determine the effect of X-rays on shoot cultures and the isolated protoplasts of rose (Rosa sp.). The materials consisted of the three rose varieties Rosa wichuriana, Paricer charm and Heckenzauber.The applied doses were 0, 10, 20, 30, 40, 50 and 60 Gy. Obtained results indicated that the genotypes differed in their sensitivity to X-rays. Rosa wichuriana seemed to be the most sensitive variety to radiation, where a dose of 20 Gy caused approximately 50% reduction in growth rate of shoot cultures, while the same dose decreased the growth rate of Paricer charm only by 25% and did not affect the growth of Heckenzauber. Results also revealed that the ability of irradiated protoplasts to form cell colonies increased when a dose of 10 Gy was performed. Doses higher than that level caused gradual decreasing in the forming of cell colonies, but however, the protoplasts could form colonies even when a dose of 60 Gy was applied. (Author)

  19. Pretreatment with platelet derived growth factor-BB modulates the ability of costochondral resting zone chondrocytes incorporated into PLA/PGA scaffolds to form new cartilage in vivo.

    Science.gov (United States)

    Lohmann, C H; Schwartz, Z; Niederauer, G G; Carnes, D L; Dean, D D; Boyan, B D

    2000-01-01

    Optimal repair of chondral defects is likely to require both a suitable population of chondrogenic cells and a biodegradable matrix to provide a space-filling structural support during the early stages of cartilage formation. This study examined the ability of chondrocytes to support cartilage formation when incorporated into biodegradable scaffolds constructed from copolymers (PLG) of polylactic acid (PLA) and polyglycolic acid (PGA) and implanted in the calf muscle of nude mice. Scaffolds were fabricated to be more hydrophilic (PLG-H) or were reinforced with 10% PGA fibers (PLG-FR), increasing the stiffness of the implant by 20-fold. Confluent primary cultures of rat costochondral resting zone chondrocytes (RC) were loaded into PLG-H foams and implanted intramuscularly. To determine if growth factor pretreatment could modulate the ability of the cells to form new cartilage, RC cells were pretreated with recombinant human platelet derived growth factor-BB IPDGF-BB) for 4 or 24 h prior to implantation. To assess whether scaffold material properties could affect the ability of chondrogenic cells to form cartilage, RC cells were also loaded into PLG-FR scaffolds. To determine if the scaffolds or treatment with PDGF-BB affected the rate of chondrogenesis, tissue at the implant site was harvested at four and eight weeks post-operatively, fixed, decalcified and embedded in paraffin. Sections were obtained along the transverse plane of the lower leg, stained with haematoxylin and eosin, and then assessed by morphometric analysis for area of cartilage, area of residual implant, and area of fibrous connective tissue formation (fibrosis). Whether or not the cartilage contained hypertrophic cells was also assessed. The amount of residual implant did not change with time in any of the implanted tissues. The area occupied by PLG-FR implants was greater than that occupied by PLG-H implants at both time points. All implants were surrounded by fibrous connective tissue, whether

  20. Characterization of the Italian glasses and their interaction with clay Task 3 Characterization of radioactive waste forms a series of final reports (1985-89) No 23

    International Nuclear Information System (INIS)

    Cantale, C.; Castelli, S.; Donato, A.; Traverso, D.M.

    1991-01-01

    The objective of this research work was the selection of a borosilicate glass composition suitable for the solidification of the HLW stream coming from the treatment of all the high-level wastes stored in Italy (MTR, Candu and Elk River) and the characterization of this glass with reference to the geological disposal. This research work was part of an Italian research project named 'Ulisse project', whose goal was the development and the demonstration of an integrated treatment of all the HLW stored in Italy, after their mixing (resulting waste: MCE waste). The main concept is to carry out a pre-treatment of the wastes, in order to concentrate the HLW fraction and to simplify the vitrification process, separating the most part of the inert salts. The research work concerning the separation process and pilot plant demonstration of the pre-treatment process were carried out in the framework of the CEC R and D programme (Contract No Fl1W-0011-lS). The laboratory studies concerning the vitrification of the resulting HLW streams and the vitrification demonstration in the Italian full-scale, inactive IVET plant complete the 'Ulisse project'. Some glass compositions were prepared and preliminarily characterized. The glass named BAZ was finally selected. A complete characterization of this glass was carried out in order to evaluate its mechanical, physical and physico-chemical properties. The chemical durability was evaluated by the MCC-1 static leach test at 90 0 C, using three different leachants and two surface-area to leachant-volume ratios. The same characterization programme was applied to the BAZ glass produced in the IVET plant during the plant vitrification demonstration programme. A comparison between the two glasses and a critical evaluation of their performances with respect to other nuclear waste glasses' durability was performed. 25 refs.; 46 figs.; 20 tabs

  1. Persistent and transient Listeria monocytogenes strains from retail deli environments vary in their ability to adhere and form biofilms and rarely have inlA premature stop codons.

    Science.gov (United States)

    Wang, Jingjin; Ray, Andrea J; Hammons, Susan R; Oliver, Haley F

    2015-02-01

    Based on recent risk assessments, up to 83% of listeriosis cases from deli meat in the United States are predicted to be from ready-to-eat deli meats contaminated during processing at retail grocery stores. Listeria monocytogenes is known to use sanitizer tolerance and biofilm formation to survive, but interplay of these mechanisms along with virulence potential and persistence mechanisms specific to deli environments had yet to be elucidated. In this study, 442 isolates from food and nonfood contact surfaces in 30 retail delis over 9 months were tested for inlA premature stop codons (PMSCs); inlA encodes InlA, which is necessary to cause listeriosis. A total of 96 isolates, composed of 23 persistent and 73 transient strains, were tested for adhesion and biofilm-forming ability and sanitizer tolerance. Only 10/442 isolates had inlA PMSCs (pdelis with other persistent strains. Most (7/10) PMSC-containing isolates were collected from food contact surfaces (pdelis (p<0.05). Persistent strains had enhanced adhesion on day 1 of a 5-day adhesion-biofilm formation assay. However, there was no significant difference in sanitizer tolerance between persistent and transient strains. Results suggest that foods contaminated with persistent L. monocytogenes strains from the retail environment are (1) likely to have wild-type virulence potential and (2) may persist due to increased adhesion and biofilm formation capacity rather than sanitizer tolerance, thus posing a significant public health risk.

  2. Enhanced radiosensitivity of cultured fibroblasts from ataxia telangiectasia heterozygotes manifested by defective colony-forming ability and reduced DNA repair replication after hypoxic γ-irradiation

    International Nuclear Information System (INIS)

    Paterson, M.C.; Anderson, A.K.; Smith, B.P.; Smith, P.J.

    1979-01-01

    We have measured the sensitivity to γ-ray inactivation of diploid skin fibroblasts cultured from 10 persons in four families with ataxia telangiectasia (AT). Persons heterozygous for AT, including parents of afflicted patients, are not as yet detectable by any specific clinical or laboratory marker but are believed to constitute a substantial portion of the middle-aged cancer population. In one AT family, fibroblast strains from both parents exhibited a colony-forming ability after hypoxic irradiation which was intermediate between that displayed by five control strains from normal children and that from the affected child. In the remaining three families, cultures from only one parent were available; one parental strain displayed an intermediate survival capacity as above, whereas the other two responded normally. The homozygous recessive strains from the five afflicted children in the four families were all equally hypersensitive to hypoxic γ-ray inactivation. The three presumed AT heterozygous strains that displayed intermediate rayiosensitivity also carried out γ-rad-induced DNA repair replication to an extent intermediate between those in normals and AT homozygotes. These findings suggest that a numerically significant, cancer-prone subpopulation of humans carrying one normal and one abnormal AT gene may also be moderately sensitive to lethal effects of hypoxic γ-rays due to a defect in the enzymatic repair of DNA

  3. The effects of crystallization and residual glass on the chemical durability of iron phosphate waste forms containing 40 wt% of a high MoO3 Collins-CLT waste

    Science.gov (United States)

    Hsu, Jen-Hsien; Bai, Jincheng; Kim, Cheol-Woon; Brow, Richard K.; Szabo, Joe; Zervos, Adam

    2018-03-01

    The effects of cooling rate on the chemical durability of iron phosphate waste forms containing up to 40 wt% of a high MoO3 Collins-CLT waste simulant were determined at 90 °C using the product consistency test (PCT). The waste form, designated 40wt%-5, meets appropriate Department of Energy (DOE) standards when rapidly quenched from the melt (as-cast) and after slow cooling following the CCC (canister centerline cooling)-protocol, although the quenched glass is more durable. The analysis of samples from the vapor hydration test (VHT) and the aqueous corrosion test (differential recession test) reveals that rare earth orthophosphate (monazite) and Zr-pyrophosphate crystals that form on cooling are more durable than the residual glass in the 40wt%-5 waste form. The residual glass in the CCC-treated samples has a greater average phosphate chain length and a lower Fe/P ratio, and those contribute to its faster corrosion kinetics.

  4. Examining porous bio-active glass as a potential osteo-odonto-keratoprosthetic skirt material.

    Science.gov (United States)

    Huhtinen, Reeta; Sandeman, Susan; Rose, Susanna; Fok, Elsie; Howell, Carol; Fröberg, Linda; Moritz, Niko; Hupa, Leena; Lloyd, Andrew

    2013-05-01

    Bio-active glass has been developed for use as a bone substitute with strong osteo-inductive capacity and the ability to form strong bonds with soft and hard tissue. The ability of this material to enhance tissue in-growth suggests its potential use as a substitute for the dental laminate of an osteo-odonto-keratoprosthesis. A preliminary in vitro investigation of porous bio-active glass as an OOKP skirt material was carried out. Porous glass structures were manufactured from bio-active glasses 1-98 and 28-04 containing varying oxide formulation (1-98, 28-04) and particle size range (250-315 μm for 1-98 and 28-04a, 315-500 μm for 28-04b). Dissolution of the porous glass structure and its effect on pH was measured. Structural 2D and 3D analysis of porous structures were performed. Cell culture experiments were carried out to study keratocyte adhesion and the inflammatory response induced by the porous glass materials. The dissolution results suggested that the porous structure made out of 1-98 dissolves faster than the structures made from glass 28-04. pH experiments showed that the dissolution of the porous glass increased the pH of the surrounding solution. The cell culture results showed that keratocytes adhered onto the surface of each of the porous glass structures, but cell adhesion and spreading was greatest for the 98a bio-glass. Cytokine production by all porous glass samples was similar to that of the negative control indicating that the glasses do not induce a cytokine driven inflammatory response. Cell culture results support the potential use of synthetic porous bio-glass as an OOKP skirt material in terms of limited inflammatory potential and capacity to induce and support tissue ingrowth.

  5. Foam Glass for Construction Materials

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund

    2016-01-01

    Foaming is commonly achieved by adding foaming agents such as metal oxides or metal carbonates to glass powder. At elevated temperature, the glass melt becomes viscous and the foaming agents decompose or react to form gas, causing a foamy glass melt. Subsequent cooling to room temperature, result...... 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...... low density foam glass for thermal insulation applications. In this thesis, it is argued that the use of metal carbonates as foaming agents is not suitable for low density foam glass. A reaction mechanism is proposed to justify this result. Furthermore, an in situ method is developed to optimise...

  6. Glass consistency and glass performance

    International Nuclear Information System (INIS)

    Plodinec, M.J.; Ramsey, W.G.

    1994-01-01

    Glass produced by the Defense Waste Processing Facility (DWPF) will have to consistently be more durable than a benchmark glass (evaluated using a short-term leach test), with high confidence. The DWPF has developed a Glass Product Control Program to comply with this specification. However, it is not clear what relevance product consistency has on long-term glass performance. In this report, the authors show that DWPF glass, produced in compliance with this specification, can be expected to effectively limit the release of soluble radionuclides to natural environments. However, the release of insoluble radionuclides to the environment will be limited by their solubility, and not glass durability

  7. Structure, biodegradation behavior and cytotoxicity of alkali-containing alkaline-earth phosphosilicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kansal, Ishu; Reddy, AlluAmarnath [Department of Materials and Ceramics Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal); Muñoz, Francisco [Ceramics and Glass Institute (CSIC), Kelsen 5, 28049 Madrid (Spain); Choi, Seong-Jun [Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 330714 (Korea, Republic of); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330714 (Korea, Republic of); Kim, Hae-Won [Department of Nanobiomedical Science and BK21 PLUS NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 330714 (Korea, Republic of); Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 330714 (Korea, Republic of); Department of Biomaterials Science, College of Dentistry, Dankook University, Cheonan 330714 (Korea, Republic of); Tulyaganov, Dilshat U. [Turin Polytechnic University in Tashkent, 100095 Tashkent (Uzbekistan); Ferreira, José M.F., E-mail: jmf@ua.pt [Department of Materials and Ceramics Engineering, University of Aveiro, CICECO, 3810-193 Aveiro (Portugal)

    2014-11-01

    We report on the effect of sodium on the structure, chemical degradation and bioactivity of glasses in the CaO–MgO–SiO{sub 2}–P{sub 2}O{sub 5}–CaF{sub 2} system. The {sup 29}Si and {sup 31}P magic angle spinning-nuclear magnetic resonance spectroscopy of melt-quenched glasses with varying Na{sub 2}O/MgO ratios exhibit a silicate glass network with the dominance of Q{sup 2}(Si) units and phosphorus mainly forming orthophosphate species. Sodium incorporation in the glasses did not induce a significant structural change in the silicate network, while it did influence the phosphate environment due to its lower ionic field strength in comparison with that of magnesium. The apatite forming ability of glasses has been investigated by immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1 h and 7 days while their chemical degradation has been studied in Tris–HCl in accordance with ISO-10993-14. Increasing Na{sup +}/Mg{sup 2+} ratio caused a decrease in the chemical durability of glasses and in the apatite forming ability especially during initial steps of interaction between glass and SBF solution. The cellular responses were observed in vitro on bulk glass samples using mouse-derived pre-osteoblastic MC3T3-E1 cell line. The preliminary study suggested that the increasing alkali-concentration in glasses led to cytotoxicity in the cell culture medium. - Highlights: • Na{sup +} did not induce significant structural changes in chemical Si environment. • Sodium is more prone to affect the chemical environment around P. • Increasing Na{sup +}/Mg{sup 2+} ratios hinder bio-mineralization and chemical durability. • Alkali-containing glasses confer cyto-toxicity to the cell culture medium.

  8. Structure, biodegradation behavior and cytotoxicity of alkali-containing alkaline-earth phosphosilicate glasses

    International Nuclear Information System (INIS)

    Kansal, Ishu; Reddy, AlluAmarnath; Muñoz, Francisco; Choi, Seong-Jun; Kim, Hae-Won; Tulyaganov, Dilshat U.; Ferreira, José M.F.

    2014-01-01

    We report on the effect of sodium on the structure, chemical degradation and bioactivity of glasses in the CaO–MgO–SiO 2 –P 2 O 5 –CaF 2 system. The 29 Si and 31 P magic angle spinning-nuclear magnetic resonance spectroscopy of melt-quenched glasses with varying Na 2 O/MgO ratios exhibit a silicate glass network with the dominance of Q 2 (Si) units and phosphorus mainly forming orthophosphate species. Sodium incorporation in the glasses did not induce a significant structural change in the silicate network, while it did influence the phosphate environment due to its lower ionic field strength in comparison with that of magnesium. The apatite forming ability of glasses has been investigated by immersion of glass powders in simulated body fluid (SBF) for time durations varying between 1 h and 7 days while their chemical degradation has been studied in Tris–HCl in accordance with ISO-10993-14. Increasing Na + /Mg 2+ ratio caused a decrease in the chemical durability of glasses and in the apatite forming ability especially during initial steps of interaction between glass and SBF solution. The cellular responses were observed in vitro on bulk glass samples using mouse-derived pre-osteoblastic MC3T3-E1 cell line. The preliminary study suggested that the increasing alkali-concentration in glasses led to cytotoxicity in the cell culture medium. - Highlights: • Na + did not induce significant structural changes in chemical Si environment. • Sodium is more prone to affect the chemical environment around P. • Increasing Na + /Mg 2+ ratios hinder bio-mineralization and chemical durability. • Alkali-containing glasses confer cyto-toxicity to the cell culture medium

  9. 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)

  10. GENERAL AND SPECIFIC COMBINING ABILITY OF INITIAL PARENTAL FORMS IN TOMATO FOR COMPLEX OF ECONOMICALLY VALUABLE TRAITS TO DEVELOP HYBRIDS F1 OF CHERRY AND COCKTAIL TYPES

    Directory of Open Access Journals (Sweden)

    R. K. Rechets

    2017-01-01

    Full Text Available Results of estimation of general and specific combining ability of male and female parental tomato forms were given for complex of traits. The estimation was carried out according to incomplete diallel crosses 15x15. Such varities   as   ‘Trapeza’,  Rosovaya  kapelka’,  ‘Seniorita’, ‘Ocharovanie’,  ‘Tigris’   ‘Vishnya  Zheltaya’  (Gavrish, ‘Denezhnoye Derevo’ (national breeding, and  lines: ‘46/06’,  ‘49/09’,  ‘295/09’,  ‘336/11’,  ‘354/11’,  ‘357/11’, ‘388/09’ (nor, ‘498’ (selection of TARI were used as intial breeding accessions, differing in bush type (determinate and indeterminate, duration of vegetative phase (ultraearly,  early, medium early, middle-ripening, fruit  shape (rounded, oval, fruit color (red, pink, black, orange, tiger and with the gene nor, fruit weight (10 g. and more, brush structure (dense, friable. As a results, ‘Trapeza’, ‘Vishnya Zheltaya’, ‘Ocharovaniye’, ‘Seniorita’, and lines: ‘295/10’, ‘49/09’,  ‘498’,  ‘357/11’,  ‘354/11’,  ‘388/09’  (nor were selected and recommended to be used in breeding program for development of heterotic hybrids with high fruit setting and generative bush type. The promising hybrids F1 with high constants of specific combining ability for a complex of economically valuable traits have been observed. Because of different lines and accessions were used in crossings, these hybrids varied in internode length of cluster type, classical or shorten; rounded or oval fruit shape; fruit  color, red (F1   combinations ‘354/11’ х ‘Seniorita’, ‘Trapeza’ х  ‘L.49/09’,  L.  ‘49/09’  х  L.354/11, pink (F1 combination ‘Rosovaya Kapelka’ х ‘L.354/11’, yellow (F1 combination ‘Ocharovaniye’ х  ‘Vishiya Zheltaya’, deep brown (F1 combination  ‘L.357/11’ х ‘L.354/11’.

  11. Development of the rectal dosage form with silver-coated glass beads for local-action applications in lower sections of the gastrointestinal tract.

    Science.gov (United States)

    Siczek, Krzysztof; Fichna, Jakub; Zatorski, Hubert; Karolewicz, Bożena; Klimek, Leszek; Owczarek, Artur

    2018-03-01

    Recent findings indicating the anti-inflammatory action of silver preparations through modulation of the gut microbiota and apoptosis of inflammatory cells predestine silver use in inflammatory bowel disease (IBD). The aim of our study was to validate the possibility of effective silver release from silver-coated glass beads for anti-inflammatory local application in the lower sections of the gastrointestinal (GI) tract. Silver-coated glass beads were prepared using magnetron method. Release of silver from the silver-coated glass bead surface was carried out in BIO-DIS reciprocating cylinder apparatus. Erosion of silver coating and indirect estimation of the silver release dynamics was assessed using scanning electron microscope. Rectal suppositories containing silver-coated glass beads were prepared using five different methods (M1-M5) and X-ray scanned for their composition. The XR microanalysis and the chemical composition analysis evidenced for a rapid (within 30 min) release of nearly 50% of silver from the coating of the glass beads, which remained stable up to 24 h of incubation. The most homogeneous distribution of beads in the entire volume of the suppository was obtained for formulation M5, where the molten base was poured into mold placed in an ice bath, and the beads were added after 10 s. Our study is the first to present the concept of enclosing silver-coated glass beads in the lipophilic suppository base to attenuate inflammation in the lower GI tract and promises efficient treatment with reduced side effects.

  12. 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 ...

  13. Understanding the structural drivers governing glass-water interactions in borosilicate based model bioactive glasses.

    Science.gov (United States)

    Stone-Weiss, Nicholas; Pierce, Eric M; Youngman, Randall E; Gulbiten, Ozgur; Smith, Nicholas J; Du, Jincheng; Goel, Ashutosh

    2018-01-01

    The past decade has witnessed a significant upsurge in the development of borate and borosilicate based resorbable bioactive glasses owing to their faster degradation rate in comparison to their silicate counterparts. However, due to our lack of understanding about the fundamental science governing the aqueous corrosion of these glasses, most of the borate/borosilicate based bioactive glasses reported in the literature have been designed by "trial-and-error" approach. With an ever-increasing demand for their application in treating a broad spectrum of non-skeletal health problems, it is becoming increasingly difficult to design advanced glass formulations using the same conventional approach. Therefore, a paradigm shift from the "trial-and-error" approach to "materials-by-design" approach is required to develop new-generations of bioactive glasses with controlled release of functional ions tailored for specific patients and disease states, whereby material functions and properties can be predicted from first principles. Realizing this goal, however, requires a thorough understanding of the complex sequence of reactions that control the dissolution kinetics of bioactive glasses and the structural drivers that govern them. While there is a consider