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Sample records for borosilicates role du

  1. Proving the role of boron in the structure of fly-ash/borosilicate glass based geopolymers

    Czech Academy of Sciences Publication Activity Database

    Taveri, Gianmarco; Toušek, J.; Bernardo, E.; Toniolo, N.; Boccaccini, A. R.; Dlouhý, Ivo

    2017-01-01

    Roč. 200, AUG (2017), s. 105-108 ISSN 0167-577X EU Projects: European Commission(XE) 642557 - CoACH Institutional support: RVO:68081723 Keywords : Fly-ash * Borosillicate * Geopolymerization * Spectroscopy * NMR * FTIR Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass OBOR OECD: Ceramics Impact factor: 2.572, year: 2016 http://www.sciencedirect.com/science/article/pii/S0167577X1730650X

  2. Structural and crystallisation study of a rare earth alumino borosilicate glass designed for nuclear waste confinement; Etude de la structure et du comportement en cristallisation d'un verre nucleaire d'aluminoborosilicate de terre rare

    Energy Technology Data Exchange (ETDEWEB)

    Quintas, A

    2007-09-15

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

  3. Foreword - Acid decomposition of borosilicate ores

    International Nuclear Information System (INIS)

    Mirsaidov, U.M.; Kurbonov, A.S.; Mamatov, E.D.

    2015-01-01

    The elaboration and development of technology of processing of mineral raw materials have an important role for the industry of Tajikistan. The results of researches of the staff of Institute of Chemistry and Nuclear and Radiation Safety Agency of the Republic of Tajikistan were considered in present monograph. The physicochemical and technological aspects of processing of borosilicate raw materials of Ak-Arkhar Deposit of Tajikistan were considered. The necessary conditions of acid decomposition of raw materials were defined. The flowsheets for the processing of boron raw materials were proposed.

  4. The borosilicate glass for 'PAMELA'

    International Nuclear Information System (INIS)

    Schiewer, E.

    1986-01-01

    The low enriched waste concentrate (LEWC) stored at Mol, Belgium, will be solidified in the vitrification plant 'PAMELA'. An alkali-borosilicate glass was developed by the Hahn-Meitner-Institut, Berlin, which dissolves (11 +- 3)wt% waste oxides while providing sufficient flexibility for changes in the process parameters. The development of the glass labelled SM513LW11 is described. Important properties of the glass melt (viscosity, resistivity, formation of yellow phase) and of the glass (corrosion in aqueous solutions, crystallization) are reported. The corrosion data of this glass are similar to those of other HLW-glasses. Less than five wt% of crystalline material are produced upon cooling of large glass blocks. Crystallization does not affect the chemical durability. (Auth.)

  5. Introduction - Acid decomposition of borosilicate ores

    International Nuclear Information System (INIS)

    Mirsaidov, U.M.; Kurbonov, A.S.; Mamatov, E.D.

    2015-01-01

    The complex processing of mineral raw materials is an effective way for the extraction of valuable components. One of these raw materials are borosilicate ores from which the boric acid, aluminium and iron salts and building materials can be obtained. In the Institute of Chemistry of the Academy of Sciences of the Republic of Tajikistan the flowsheets of the processing of borosilicate raw materials by acid and chloric methods were elaborated. The acid methods of decomposition of borosilicate ores of Ak-Arkhar Deposit were considered in present monograph. The carried out researches on elaboration of physicochemical aspects and technological acid methods allowed to define the optimal ways of extraction of valuable products from borosilicate raw materials of Tajikistan.

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

    International Nuclear Information System (INIS)

    Paul, Manidipa; Pal, Nabanita; Bhaumik, Asim

    2012-01-01

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

  7. Irradiation test of borosilicate glass burnable poison

    International Nuclear Information System (INIS)

    Feng Mingquan; Liao Zumin; Yang Mingjin; Lu Changlong; Huang Deyang; Zeng Wangchun; Zhao Xihou

    1991-08-01

    The irradiation test and post-irradiation examinations for borosilicate glass burnable poison are introduced. Examinations include visual examination, measurement of dimensions and density, and determination of He gas releasing and 10 B burnup. The corrosion and phenomenon of irradiation densification are also discussed. Two type glass samples have been irradiated with different levels of neutron flux. It proved that the GG-17 borosilicate glass can be used as burnable poison to replace the 10 B stainless steel in the Qinshan Nuclear Power Plant, and it is safe, economical and reasonable

  8. Titanium impregnated borosilicate zeolites for epoxidation catalysis

    Czech Academy of Sciences Publication Activity Database

    Přech, Jan; Vitvarová, Dana; Lupínková, Lenka; Kubů, Martin; Čejka, Jiří

    2015-01-01

    Roč. 212, AUG 2015 (2015), s. 28-34 ISSN 1387-1811 R&D Projects: GA ČR GAP106/11/0819 Institutional support: RVO:61388955 Keywords : borosilicate * titanium impregnation * epoxidation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.349, year: 2015

  9. Topological Principles of Borosilicate Glass Chemistry

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Mauro, J. C.; Youngman, R. E.

    2011-01-01

    and laboratory glassware to high-tech applications such as liquid crystal displays. In this paper, we investigate the topological principles of borosilicate glass chemistry covering the extremes from pure borate to pure silicate end members. Based on NMR measurements, we present a two-state statistical...

  10. Borosilicate glass for gamma irradiation fields

    Science.gov (United States)

    Baydogan, N.; Tugrul, A. B.

    2012-11-01

    Four different types of silicate glass specimens were irradiated with gamma radiation using a Co-60 radioisotope. Glass specimens, with four different chemical compositions, were exposed to neutron and mixed neutron/gamma doses in the central thimble and tangential beam tube of the nuclear research reactor. Optical variations were determined in accordance with standardisation concept. Changes in the direct solar absorbance (αe) of borosilicate glass were examined using the increase in gamma absorbed dose, and results were compared with the changes in the direct solar absorbance of the three different type silicate glass specimens. Solar absorption decreased due to decrease of penetration with absorbed dose. αe of borosilicate increased considerably when compared with other glass types. Changes in optical density were evaluated as an approach to create dose estimation. Mixed/thermal neutron irradiation on glass caused to increse αe.

  11. Investigation on neptunium in a borosilicate glass

    International Nuclear Information System (INIS)

    Poirot, I.

    1988-03-01

    The oxidization state and coordination of neptunium, introduced as dopant in borosilicate glasses were studied through optical, Mossbauer spectroscopies and magnetic measurements. The neptunium oxide, introduced previously as NpO 2 is reduced during the melting process of the glass. This leads to an equilibrium in which the ratio of Np 4+ to Np 3+ valences depends on experimental conditions. Spectroscopic analysises conduct to postulate the presence of different sites for each of the oxydation states of neptunium [fr

  12. Thermodynamic properties of alkali borosilicate gasses and metaborates

    International Nuclear Information System (INIS)

    Asano, Mitsuru

    1992-01-01

    Borosilicate glasses are the proposed solidifying material for storing high level radioactive wastes in deep underground strata. Those have low melting point, and can contain relatively large amount of high level radioactive wastes. When borosilicate glasses are used for this purpose, they must be sufficiently stable and highly reliable in the vitrification process, engineered storage and the disposal in deep underground strata. The main vaporizing components from borosilicate glasses are alkali elements and boron. In this report, as for the vaporizing behavior of alkali borosilicate glasses, the research on thermodynamic standpoint carried out by the authors is explained, and the thermodynamic properties of alkali metaborates of monomer and dimer which are the main evaporation gases are reported. The evaporation and the activity of alkali borosilicate glasses, the thermodynamic properties of alkali borosilicate glasses, gaseous alkali metaborates and alkali metaborate system solid solution and so on are described. (K.I.)

  13. Topological Principles of Borosilicate Glass Chemistry - An Invited Talk

    DEFF Research Database (Denmark)

    Mauro, J.C.; Smedskjær, Morten Mattrup; Youngman, R. E.

    Borosilicate glasses display a rich complexity of chemical behavior depending on the details of their composition and thermal history. We investigate the topological principles of borosilicate glass chemistry covering the extremes from pure borate to pure silicate end members. Based on NMR...

  14. The structure of leached sodium borosilicate glass

    International Nuclear Information System (INIS)

    Bunker, B.C.; Tallant, D.R.; Headley, T.J.; Turner, G.L.; Kirkpatrick, R.J.

    1988-01-01

    Raman spectroscopy, solid state 29 Si, 11 B, 17 O, and 23 Na nuclear magnetic resonance spectroscopy, and transmission electron microscopy have been used to investigate how the structures of sodium borosilicate glasses change during leaching in water at pH 1, 9, and 12. Results show that the random network structure present prior to leaching is transformed into a network of small condensed ring structures and/or colloidal silica particles. The restructuring of leached glass can be rationalised on the basis of simple hydrolysis (depolymerisation) and condensation (repolymerisation) reactions involving Si-O-Si and Si-O-B bonds. The structural changes that occur during leaching influence the properties of the leached layer, including leaching kinetics, crazing and spalling, and slow crack growth. (author)

  15. 57Fe Moessbauer effect in borosilicate glasses

    International Nuclear Information System (INIS)

    Music, S.

    1989-01-01

    The present study was carried out to elucidate the valence state of iron and its co-ordination in borosilicate glasses, which are being investigated as possible solidification matrices for the immobilization of a simulated nuclear waste. 57 Fe Mossbauer spectroscopy was used as the experimental technique. The chemical compositions of glass samples and the experimental conditions for the preparation of these samples are given. Iron in the form of haematite (α-Fe 2 O 3 ) was used as doping material. Details of the experimental procedure have previously been described. Isomer shifts are calculated relative to α-iron. The results indicate a strong dependence of the valency of the iron and its coordination on the chemical composition of the glass and the Fe 2 O 3 content. The method of preparing the glasses also influences the state of the iron in oxide glasses. (Author)

  16. 11B nutation NMR study of powdered borosilicates

    International Nuclear Information System (INIS)

    Woo, Ae Ja; Yang, Kyung Hwa; Han, Duk Young

    1998-01-01

    In this work, we applied the 1D 11 B nutation NMR method for the analysis of the local structural environments in powdered borosilicates (SiO 2 -B 2 O 3 ). Spin dynamics during a rf irradiation for spin I=3/2 was analytically calculated with a density matrix formalism. Spectral simulation programs were written in MATLAB on a PC. Two borosilicates prepared by the sol-gel process at different stabilization temperature were used for the 1D 11 B nutation NMR experiment. The 11 B NMR parameters, quadrupole coupling constants (e 2 qQ/h) and asymmetry parameters (η), for each borosilicate were extracted from the nonlinear least-squares fitting. The effects of heat treatments on the local structures of boron sites in borosilicates were discussed

  17. Fabrication of Low Noise Borosilicate Glass Nanopores for Single Molecule Sensing.

    Directory of Open Access Journals (Sweden)

    Jayesh A Bafna

    Full Text Available We show low-cost fabrication and characterization of borosilicate glass nanopores for single molecule sensing. Nanopores with diameters of ~100 nm were fabricated in borosilicate glass capillaries using laser assisted glass puller. We further achieve controlled reduction and nanometer-size control in pore diameter by sculpting them under constant electron beam exposure. We successfully fabricate pore diameters down to 6 nm. We next show electrical characterization and low-noise behavior of these borosilicate nanopores and compare their taper geometries. We show, for the first time, a comprehensive characterization of glass nanopore conductance across six-orders of magnitude (1M-1μM of salt conditions, highlighting the role of buffer conditions. Finally, we demonstrate single molecule sensing capabilities of these devices with real-time translocation experiments of individual λ-DNA molecules. We observe distinct current blockage signatures of linear as well as folded DNA molecules as they undergo voltage-driven translocation through the glass nanopores. We find increased signal to noise for single molecule detection for higher trans-nanopore driving voltages. We propose these nanopores will expand the realm of applications for nanopore platform.

  18. Surface chemistry and durability of borosilicate glass

    International Nuclear Information System (INIS)

    Carroll, S.A.; Bourcier, W.L.; Phillips, B.L.

    1994-01-01

    Important glass-water interactions are poorly understood for borosilicate glass radioactive waste forms. Preliminary results show that glass durability is dependent on reactions occurring at the glass-solution interface. CSG glass (18.2 wt. % Na 2 O, 5.97 wt. % CaO, 11.68 wt. % Al 2 O 3 , 8.43 wt. % B 2 O 3 , and 55.73 wt. % SiO 2 ) dissolution and net surface H + and OH - adsorption are minimal at near neutral pH. In the acid and alkaline pH regions, CSG glass dissolution rates are proportional to [H + ] adsorbed 2 and [OH - ] adsorbed 0.8 , respectively. In contrast, silica gel dissolution and net H + and OH - adsorption are minimal and independent of pH in acid to neutral solutions. In the alkaline pH region, silica gel dissolution is proportional to [OH - ] adsorbed 0.9 adsorbed . Although Na adsorption is significant for CSG glass and silica gel in the alkaline pH regions, it is not clear if it enhances dissolution, or is an artifact of depolymerization of the framework bonds

  19. Method of manufacturing borosilicate glass solidification products

    International Nuclear Information System (INIS)

    Tanaka, Tsuneya.

    1986-01-01

    Purpose: To obtain glass solidification products efficiently in a dry process from medium and high level radioactive liquid wastes discharged from PWR type reactors. Method: Boric acid-containing radioactive liquid wastes generated from primary coolants of PWR type reactors are evaporated to condensate as the pre-treatment. The concentrated liquid wastes are supplied to a drum type rotary kiln. While on the other hand, usual glass frits are introduced into the kiln. The liquid wastes are dried in the rotary kiln, as well as B 2 O 3 and the glass frits in the liquid wastes are combined into glass particles. In this case, since the kiln is rotated, no glass particles are deposited on the wall of the kiln. Then, the glass particles are introduced for melting into a high frequency melting furnace made of metal. The melting temperature is set to 1100 - 1150 deg C. The molten borosilicate glass is recovered from the bottom of the melting furance, contained in a canister and cooled for several hours, and then a cover is welded to the canister. (Ikeda, J.)

  20. Effects of system size and cooling rate on the structure and properties of sodium borosilicate glasses from molecular dynamics simulations.

    Science.gov (United States)

    Deng, Lu; Du, Jincheng

    2018-01-14

    Borosilicate glasses form an important glass forming system in both glass science and technologies. The structure and property changes of borosilicate glasses as a function of thermal history in terms of cooling rate during glass formation and simulation system sizes used in classical molecular dynamics (MD) simulation were investigated with recently developed composition dependent partial charge potentials. Short and medium range structural features such as boron coordination, Si and B Q n distributions, and ring size distributions were analyzed to elucidate the effects of cooling rate and simulation system size on these structure features and selected glass properties such as glass transition temperature, vibration density of states, and mechanical properties. Neutron structure factors, neutron broadened pair distribution functions, and vibrational density of states were calculated and compared with results from experiments as well as ab initio calculations to validate the structure models. The results clearly indicate that both cooling rate and system size play an important role on the structures of these glasses, mainly by affecting the 3 B and 4 B distributions and consequently properties of the glasses. It was also found that different structure features and properties converge at different sizes or cooling rates; thus convergence tests are needed in simulations of the borosilicate glasses depending on the targeted properties. The results also shed light on the complex thermal history dependence on structure and properties in borosilicate glasses and the protocols in MD simulations of these and other glass materials.

  1. Effects of system size and cooling rate on the structure and properties of sodium borosilicate glasses from molecular dynamics simulations

    Science.gov (United States)

    Deng, Lu; Du, Jincheng

    2018-01-01

    Borosilicate glasses form an important glass forming system in both glass science and technologies. The structure and property changes of borosilicate glasses as a function of thermal history in terms of cooling rate during glass formation and simulation system sizes used in classical molecular dynamics (MD) simulation were investigated with recently developed composition dependent partial charge potentials. Short and medium range structural features such as boron coordination, Si and B Qn distributions, and ring size distributions were analyzed to elucidate the effects of cooling rate and simulation system size on these structure features and selected glass properties such as glass transition temperature, vibration density of states, and mechanical properties. Neutron structure factors, neutron broadened pair distribution functions, and vibrational density of states were calculated and compared with results from experiments as well as ab initio calculations to validate the structure models. The results clearly indicate that both cooling rate and system size play an important role on the structures of these glasses, mainly by affecting the 3B and 4B distributions and consequently properties of the glasses. It was also found that different structure features and properties converge at different sizes or cooling rates; thus convergence tests are needed in simulations of the borosilicate glasses depending on the targeted properties. The results also shed light on the complex thermal history dependence on structure and properties in borosilicate glasses and the protocols in MD simulations of these and other glass materials.

  2. The reader’s role in the fiction of Menán du Plessis

    Directory of Open Access Journals (Sweden)

    M. J. Daymond

    1992-05-01

    Full Text Available The reception theory’ of Wolfgang Iser is used to explore the effects of the differences in the narration of Du Plessis’ novels. The chief differences are the degree of consciousness with which the reader engages in meaning-making and the level at which the reader encounters the major enigma on which the larger interpretation of each novel rests. Also considered are some implications of the analogy, to which my interpretation leads, between narrative form and Du Plessis’ judgement of her world.

  3. Using of borosilicate glass waste as a cement additive

    International Nuclear Information System (INIS)

    Han, Weiwei; Sun, Tao; Li, Xinping; Sun, Mian; Lu, Yani

    2016-01-01

    Highlights: • Borosilicate glass waste used as cement additive can improves its radiation shielding. • When content is 14.8%, the linear attenuation coefficient is 0.2457 cm"−"1 after 28 d. • From 0 to 22.2%, linear attenuation coefficient firstly increase and then decrease. - Abstract: Borosilicate glass waste is investigated as a cement additive in this paper to improve the properties of cement and concrete, such as setting time, compressive strength and radiation shielding. The results demonstrate that borosilicate glass is an effective additive, which not only improves the radiation shielding properties of cement paste, but also shows the irradiation effect on the mechanical and optical properties: borosilicate glass can increase the compressive strength and at the same time it makes a minor impact on the setting time and main mineralogical compositions of hydrated cement mixtures; and when the natural river sand in the mortar is replaced by borosilicate glass sand (in amounts from 0% to 22.2%), the compressive strength and the linear attenuation coefficient firstly increase and then decrease. When the glass waste content is 14.8%, the compressive strength is 43.2 MPa after 28 d and the linear attenuation coefficient is 0.2457 cm"−"1 after 28 d, which is beneficial for the preparation of radiation shielding concrete with high performances.

  4. Using of borosilicate glass waste as a cement additive

    Energy Technology Data Exchange (ETDEWEB)

    Han, Weiwei [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan, Hubei 430070 (China); School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Sun, Tao, E-mail: sunt@whut.edu.cn [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Key Laboratory of Roadway Bridge & Structure Engineering, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Li, Xinping [Key Laboratory of Roadway Bridge & Structure Engineering, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Sun, Mian [School of Materials Science and Engineering, Wuhan University of Technology, Wuhan, Hubei 430070 (China); Lu, Yani [Urban Construction Institute, Hubei Engineering University, Xiaogan, Hubei 432000 (China)

    2016-08-15

    Highlights: • Borosilicate glass waste used as cement additive can improves its radiation shielding. • When content is 14.8%, the linear attenuation coefficient is 0.2457 cm{sup −1} after 28 d. • From 0 to 22.2%, linear attenuation coefficient firstly increase and then decrease. - Abstract: Borosilicate glass waste is investigated as a cement additive in this paper to improve the properties of cement and concrete, such as setting time, compressive strength and radiation shielding. The results demonstrate that borosilicate glass is an effective additive, which not only improves the radiation shielding properties of cement paste, but also shows the irradiation effect on the mechanical and optical properties: borosilicate glass can increase the compressive strength and at the same time it makes a minor impact on the setting time and main mineralogical compositions of hydrated cement mixtures; and when the natural river sand in the mortar is replaced by borosilicate glass sand (in amounts from 0% to 22.2%), the compressive strength and the linear attenuation coefficient firstly increase and then decrease. When the glass waste content is 14.8%, the compressive strength is 43.2 MPa after 28 d and the linear attenuation coefficient is 0.2457 cm{sup −1} after 28 d, which is beneficial for the preparation of radiation shielding concrete with high performances.

  5. Utilization of borosilicate glass for transuranic waste immobilization

    International Nuclear Information System (INIS)

    Ledford, J.A.; Williams, P.M.

    1979-01-01

    Incinerated transuranic waste and other low-level residues have been successfully vitrified by mixing with boric acid and sodium carbonate and heating to 1050 0 C in a bench-scale continuous melter. The resulting borosilicate glass demonstrates excellent mechanical durability and chemical stability

  6. IR study of Pb–Sr titanate borosilicate glasses

    Indian Academy of Sciences (India)

    Administrator

    IR study of Pb–Sr titanate borosilicate glasses. C R GAUTAM*, DEVENDRA KUMAR. † and OM PARKASH. †. Department of Physics, University of Lucknow, Lucknow 226 007, India. †. Department of Ceramic Engineering, Institute of Technology, Banaras Hindu University, Varanasi 221 005, India. MS received 3 January ...

  7. Sintering-alkaline processing of borosilicate ores of Tajikistan

    International Nuclear Information System (INIS)

    Nazarov, F.A.

    2018-01-01

    The aim of the work is to study the processes of decomposition of boron-containing ore by sintering with NaOH, finding the optimal parameters of the decomposition process, studying the kinetics of processes and developing the technological foundations for ore processing. The processes of borosilicate ore processing were studied by sintering with NaOH. Possible mechanisms of chemical reactions of the process of sintering-alkaline decomposition of boron-containing ore are established, the results of which are substantiated by physicochemical methods of analysis. A principal technological scheme for processing of borosilicate ores by a sintering-alkaline method has been developed. In the first chapter, data on alkaline and caking processes for processing boron-containing and aluminium comprising raw materials are available in the literature. Based on this, the directions of our own research are outlined. The second chapter is devoted to the study of the chemical and mineralogical compositions of borosilicate ores and their concentrates with the help of X-ray phase and chemical analysis methods, the stoichiometric calculation of the formation of aluminum, iron, and boron salts has been carried out, and a thermodynamic analysis of the processes of sintering borosilicate ores with alkali has been considered. The third chapter presents the results of a study of sintering-alkaline method of processing of initial borosilicate ore of the Ak-Arkhar Deposit and its concentrate without calcination and after calcination. The kinetics of sintering of borosilicate ores with sodium hydroxide was studied. The optimal conditions of borosilicate ore sintering before and after the preliminary calcination with alkali were determined. Optimal parameters of the sintering process have been found: sintering temperature 800-8500 deg C, duration of the process - 60 minutes, mass ratio of NaOH to raw materials 2: 1. The conditions for sintering of borosilicate concentrate with alkali have been

  8. The role of Rad 51 protein in radioresistance of spheroid model of Du 145 prostate carcinoma cell line

    International Nuclear Information System (INIS)

    Taghizadeh, M.; Khoei, S.; Nikoofar, A. R.; Ghamsari, L.; Goliaei, B.

    2009-01-01

    Rad 51 is a protein with critical role in double strand break repair. Down-regulation of this protein has a significant effect in radiosensitivity of some cell lines like prostate carcinoma. Compared to monolayer cell culture model, the spheroids are more resistant to radiation. The aim of the current study was to determine the Rad 51 protein level in Du 145 spheroids, and monolayer cells before and after exposure to gamma irradiation. Materials and Methods: In the present study, western blot was used to determine the level of Rad 51 protein in Du 145 cell line grown as monolayer and spheroid. Results: Western blot analysis showed that in the spheroid cells, Rad 51 had an elevated level before and after radiation in comparison with monolayer cells. Higher doses of radiation induced elevated expression of Rad 51 protein in both culture models.The level of at protein after exposure to gamma rays had been time-dependent. Conclusion: Rad 51 might act as a mediator of radiation resistance in tumor cells. Repression of Rad 51 activity could be a prominent strategy to overcome radiation resistance of tumors.

  9. Differential response of DU145 and PC3 prostate cancer cells to ionizing radiation: role of reactive oxygen species, GSH and Nrf2 in radiosensitivity.

    Science.gov (United States)

    Jayakumar, Sundarraj; Kunwar, Amit; Sandur, Santosh K; Pandey, Badri N; Chaubey, Ramesh C

    2014-01-01

    Radioresistance is the major impediment in radiotherapy of many cancers including prostate cancer, necessitating the need to understand the factors contributing to radioresistance in tumor cells. In the present study, the role of cellular redox and redox sensitive transcription factor, Nrf2 in the radiosensitivity of prostate cancer cell lines PC3 and DU145, has been investigated. Differential radiosensitivity of PC3 and DU145 cells was assessed using clonogenic assay, flow cytometry, and comet assay. Their redox status was measured using DCFDA and DHR probes. Expression of Nrf2 and its dependent genes was measured by EMSA and real time PCR. Knockdown studies were done using shRNA transfection. PC3 and DU145 cells differed significantly in their radiosensitivity as observed by clonogenic survival, apoptosis and neutral comet assays. Both basal and inducible levels of ROS were higher in PC3 cells than that of DU145 cells. DU145 cells showed higher level of basal GSH content and GSH/GSSG ratio than that of PC3 cells. Further, significant increase in both basal and induced levels of Nrf2 and its dependent genes was observed in DU145 cells. Knock-down experiments and pharmacological intervention studies revealed the involvement of Nrf2 in differential radio-resistance of these cells. Cellular redox status and Nrf2 levels play a causal role in radio-resistance of prostate cancer cells. The pivotal role Nrf2 has been shown in the radioresistance of tumor cells and this study will further help in exploiting this factor in radiosensitization of other tumor cell types. © 2013.

  10. Radiation structurization borosilicates in the region of small dozes

    International Nuclear Information System (INIS)

    Gadzhieva, N.N.; Melikova, S.Z.

    2007-01-01

    Full text: Borosilicates are one of perspective materials who are characterized by high thermal and radiating stability. Owing to these properties they are widely applied as constructional materials in reactor technologies. The structural condition of a bor in crystal compounds is characterized by two coordination numbers- three and and four. Change of this condition speaks also original properties borosilicate. Studying influence is actual γ-irradiations in the region of rather small dozes on ability change coordination of a B in borosilicate. In the given work results of IR-spectroscopic researches initial and radiation-structured borosilicates are presented. With this purpose were investigated borosilicates with maintenance B 2 O 3 in SiO 2 equal 0.5; 1; 1.5; 3; 5 and 10 mas.%, received by a method of sedimentation. Samples irradiated γ-quanta on an isotope source 60 Co with capacity of a doze dD γ /dt=0.80 Gy/s. The absorbed doze made D γ ∼0.5-50 kGy. IR-spectra of reflection initial and γ-irradiated tablets borosilicates measured on spectrophotometer Specord 71 IR (Carl Zeiss) at a room temperature. Optical density of the bands corresponding trigonal and tetrahedric - coordination atoms of a bor and their parity at the various mass maintenance of boric anhydride in SiO 2 before and after γ-irradiation. The absorption bands of asymmetric stretching vibration BO 3 and BO 4 groupings in structure of B 2 O 3 /SiO 2 have maxima at ν=1320 (ν as BO 3 ) and 980 cm -1 (ν as BO 4 ). Studying dose has shown dependences D 1320 /D 980 , that in the region of rather small dozes 0.5 γ 1320 /D 980 of optical densities trigonal and tetrahedric coordination a B it is established, that at the contain B 2 O 3 in SiO 2 /B 2 O 3 ∼1.5 mas.% maximal introduction B 3+ in a lattice oxide silicon is observed

  11. Optical and structural investigation on sodium borosilicate glasses doped with Cr2O3

    Science.gov (United States)

    Ebrahimi, E.; Rezvani, M.

    2018-02-01

    In this work, Sodium borosilicate glasses with chemical composition of 60% SiO2-20% B2O3-20%Na2O doped with different contents of Cr2O3 were prepared by melting-quenching method. Physical, structural and optical properties of glasses were investigated by studying density and molar volume, Fourier Transform Infrared (FT-IR) Spectra and UV-visible absorption spectroscopy. The results showed an increase in density of glasses with the increase of Cr2O3 that can be due to addition of oxide with high molar mass. The optical absorption spectra of un-doped glass reveals UV absorption due to trace iron impurities with no visible band however Cr2O3 doped glasses shows absorption in visible range that are characteristic. Increasing of Cr3 + ions in the glassy microstructure of samples provides a semiconducting character to Sodium borosilicate glass by reducing the direct and indirect optical band gaps of glass samples from 3.79 to 2.59 (ev) and 3.36 to 2.09 (ev), respectively. These changes could be attributed to the role of Cr3 + ions as the network former which asserts improvement of semiconducting behavior in presence of Cr2O3.

  12. Rutherford backscattering investigation of the corrosion of borosilicate glass

    International Nuclear Information System (INIS)

    Sales, B.C.; Boatner, L.A.; Naramoto, H.; White, C.W.

    1981-10-01

    The RBS spectra from Frit 21 borosilicate glasses doped with 5 wt % UO 2 , SrO, or Cs 2 O show that: during the initial stages of leaching (0 to 3 h) there is a substantial (300 to 500%) enhancement in the concentration of U, Sr, Ca, and Ti in the outer surface layer and that this enhancement is accompanied by a large depletion of Na, Si, and Cs; and upon further leaching under static conditions (24 h) the leached surface layer composition is indistinguishable from the unleached surface. Other borosilicate glasses such as PNL 76-68 may eventually show the same behavior if the final equilibrium pH value is greater than 9. The technique of Rutherford backscattering depth profile analysis can be a powerful tool for investigating the initial stages of glass corrosion

  13. Sulphate Incorporation in Borosilicate Glasses and Melts: a Kinetic Approach

    Energy Technology Data Exchange (ETDEWEB)

    Lenoir, M. [CEA, DEN, Laboratoire d' etude et de Developpement de Matrices de Conditionnement, Centre de Marcoule, 30207 Bagnols-sur-Ceze (France); Physique des Mineraux et Magmas, UMR 7047, CNRS- Institut de Physique du Globe de Paris, 7 place Jussieu, 75252 Paris 05 (France); Grandjean, A. [Institut de Chimie Separative de Marcoule, UMR 5257, Laboratoire des Nanomateriaux Autoreparants, Marcoule, 30207 Bagnols-sur-Ceze (France); Dussossoy, J.L. [CEA, DEN, Laboratoire d' etude et de Developpement de Matrices de Conditionnement, Centre de Marcoule, 30207 Bagnols-sur-Ceze (France); Neuville, D.R. [Physique des Mineraux et Magmas, UMR 7047, CNRS- Institut de Physique du Globe de Paris, 7 place Jussieu, 75252 Paris 05 (France)

    2008-07-01

    The kinetics of sulphate departure in a sodium borosilicate melt were studied using in situ Raman spectroscopy. This technique allows the quantification of the amount of sulphate dissolved in a borosilicate glass as a function of heating time by comparison with measurements obtained by microprobe wavelength dispersive spectrometry. To quantify the sulphate content obtained with Raman spectroscopy, the integrated intensity of the sulphate band at 990 cm{sup -1} was scaled to the sum of the integrated bands between 800 and 1200 cm{sup -1}, bands that are assigned to Qn silica units on the basis of previous literature. Calibration curves were then determined for two different samples. An evaluation of the kinetics of departure of sulphate could thus be made as a function of the viscosity of the borosilicate glass, showing that the kinetics were controlled by the diffusion of sulphate and its volatilization from the melt. This experimental method allows in situ measurements of sulphate content at high temperature which cannot be obtained by any other simple technique. (authors)

  14. Assessment of Savannah River borosilicate glass in the repository environment

    International Nuclear Information System (INIS)

    Plodinec, M.J.; Wicks, G.G.; Bibler, N.E.

    1982-04-01

    Since 1973, borosilicate glass has been studied as a matrix for the immobilization of high-level radioactive waste generated at the Savannah River Plant (SRP). In 1977, efforts began to develop and test the large-scale equipment necessary to convert the alkaline waste slurries at SRP into a durable borosilicate glass. A process has now been developed for the proposed Defense Waste Processing Facility (DWPF) which will annually produce approximately 500 canisters of SRP waste glass which will be stored on an interim basis on the Savannah River site. Current national policy calls for the permanent disposal of high-level waste in deep geologic repositories. In the repository environment, SRP waste glass will eventually be exposed to such stresses as lithostatic or hydrostatic pressures, radiation fields, and self-heating due to radioactive decay. In addition, producing and handling each canister of glass will also expose the glass to thermal and mechanical stresses. An important objective of the extensive glass characterization and testing programs of the Savannah River Laboratory (SRL) has been to determine how these stresses affect the performance of SRP waste glass. The results of these programs indicate that: these stresses will not significantly affect the performance of borosilicate glass containing SRP waste; and SRP waste glass will effectively immobilize hazardous radionuclides in the repository environment

  15. Enhancement of thermal neutron shielding of cement mortar by using borosilicate glass powder.

    Science.gov (United States)

    Jang, Bo-Kil; Lee, Jun-Cheol; Kim, Ji-Hyun; Chung, Chul-Woo

    2017-05-01

    Concrete has been used as a traditional biological shielding material. High hydrogen content in concrete also effectively attenuates high-energy fast neutrons. However, concrete does not have strong protection against thermal neutrons because of the lack of boron compound. In this research, boron was added in the form of borosilicate glass powder to increase the neutron shielding property of cement mortar. Borosilicate glass powder was chosen in order to have beneficial pozzolanic activity and to avoid deleterious expansion caused by an alkali-silica reaction. According to the experimental results, borosilicate glass powder with an average particle size of 13µm showed pozzolanic activity. The replacement of borosilicate glass powder with cement caused a slight increase in the 28-day compressive strength. However, the incorporation of borosilicate glass powder resulted in higher thermal neutron shielding capability. Thus, borosilicate glass powder can be used as a good mineral additive for various radiation shielding purposes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Radiation response of cubic mesoporous silicate and borosilicate thin films

    Science.gov (United States)

    Manzini, Ayelén; Alurralde, Martín; Luca, Vittorio

    2018-01-01

    The radiation response has been studied of cubic mesoporous silicate and borosilicate thin films having different boron contents prepared using the block copolymer template Brij 58 and the dip coating technique. The degree of pore ordering of the films was analysed using low-angle X-ray diffraction and film thickness measured by X-ray reflectivity. For films calcined at 350 °C, the incorporation of boron resulted in a reproducible oscillatory variation in the d-spacing and intensity of the primary reflection as a function of boron content. A clear peak was observed in the d-spacing at 5-10 mol% boron incorporation. For borosilicate films of a given composition an overall suppression of d-spacing was observed as a function of aging time relative to films that did not contain boron. This was ascribed to a slow condensation process. The films were irradiated in pile with neutrons and with iodine ions at energies of 180 keV and 70 MeV. Neutron irradiation of the silicate thin films for periods up to 30 days and aged for 400 days resulted in little reduction in either d-spacing or intensity of the primary low-angle X-ray reflection indicating that the films retained their mesopore ordering. In contrast borosilicate films for which the B (n, α) reaction was expected to result in enhanced displacement damage showed much larger variations in X-ray parameters. For these films short irradiation times resulted in a reduction of the d-spacing and intensity of the primary reflections considerably beyond that observed through aging. It is concluded that prolonged neutron irradiation and internal α irradiation have only a small, although measurable, impact on mesoporous borosilicate thin films increasing the degree of condensation and increasing unit cell contraction. When these borosilicate films were irradiated with iodine ions, more profound changes occurred. The pore ordering of the films was significantly degraded when low energy ions were used. In some cases the degree

  17. Low Velocity Sphere Impact of a Borosilicate Glass

    Energy Technology Data Exchange (ETDEWEB)

    Morrissey, Timothy G [ORNL; Ferber, Mattison K [ORNL; Wereszczak, Andrew A [ORNL; Fox, Ethan E [ORNL

    2012-05-01

    This report summarizes US Army TARDEC sponsored work at Oak Ridge National Laboratory (ORNL) involving low velocity (< 30 m/s or < 65 mph) ball impact testing of Borofloat borosilicate glass, and is a follow-up to a similar study completed by the authors on Starphire soda-lime silicate glass last year. The response of the borosilicate glass to impact testing at different angles was also studied. The Borofloat glass was supplied by the US Army Research Laboratory and its tin-side was impacted or indented. The intent was to better understand low velocity impact response in the Borofloat. Seven sphere materials were used whose densities bracket that of rock: borosilicate glass, soda-lime silicate glass, silicon nitride, aluminum oxide, zirconium oxide, carbon steel, and a chrome steel. A gas gun or a ball-drop test setup was used to produce controlled velocity delivery of the spheres against the glass tile targets. Minimum impact velocities to initiate fracture in the Borofloat were measured and interpreted in context to the kinetic energy of impact and the elastic property mismatch between the seven sphere-Borofloat-target combinations. The primary observations from this low velocity (< 30 m/s or < 65 mph) testing were: (1) BS glass responded similarly to soda-lime silicate glass when spherically indented but quite differently under sphere impact conditions; (2) Frictional effects contributed to fracture initiation in BS glass when it spherically indented. This effect was also observed with soda-lime silicate glass; (3) The force necessary to initiate fracture in BS glass under spherical impact decreases with increasing elastic modulus of the sphere material. This trend is opposite to what was observed with soda-lime silicate glass. Friction cannot explain this trend and the authors do not have a legitimate explanation for it yet; (4) The force necessary to initiate contact-induced fracture is higher under dynamic conditions than under quasi-static conditions. That

  18. Alteration of borosilicate glass under water saturated condition

    International Nuclear Information System (INIS)

    Tsukimura, K.; Matsuhisa, Y.; Kanai, Y.; Hirai, H.

    1991-01-01

    In the long term of the high-level nuclear waste disposal, the dissolving rates of radionuclides from the waste will be controlled by crystalline phases secondarily formed in the borosilicate glass by reaction with ground water. We have determined the crystalline phases formed from borosilicate glass in a hydrothermal experiment. Borosilicate glass powder (50 mg, Si 40 B 20 Al 4 Li 12 Na 14 K 3 Ca 2 Fe 5 O 140 ) and 200 ml of water were reacted at 300degC and 300 bars for 2 weeks with a cold-seal type hydrothermal high pressure apparatus. After the reaction the liquid phase was analyzed with atomic absorption spectroscopy and the solid phases with x-ray powder diffraction and analytical electron microscopy. The liquid phase contains 58 % of Na, 14 % of Li and 11 % of K but less than 1 % of Ca and Fe. The solid phases were found to be zeolite and smectite. The zeolite is isostructural with analcime Na 2 Al 2 (SiO 3 ) 4 · 2H 2 O or wairakite CaAl 2 (SiO 3 ) 4 · 2H 2 O and contains Ca and Si as major constituents but does not contain Al. Although no direct analytical evidence is available, logical induction of the experimental results indicates that the chemical composition of the zeolite is CaB 2 (SiO 3 ) 4 . The remaining x-ray powder diffraction peaks are same as those of smectite Na 06.7 (Al 3.33 Mg 0.67 )Si 8 O 20 (OH) 4 . However, since our starting material was free of Mg, and Na was not detected by AEM, the smectite may contain Fe instead of Mg, and Li instead of Na. (author)

  19. Gas gain stability of MSGCs on borosilicate glass

    International Nuclear Information System (INIS)

    Berg, F.D. van den; Daum, C.; Eijk, B. van; Hartjes, F.G.; Udo, F.; Zhukov, V.

    1996-01-01

    The gas gain stability in Micro Strip Gas Counters fabricated on borosilicate glass has been investigated for operation at high radiation fluxes up to 10 5 Hz/mm 2 in a X-ray set-up. We discuss effects of short and long term irradiation on the gain for different voltage settings and strip metalisations. The application of a high drift field and a back plane on positive potential provides good high rate operation up to 10 4 Hz/mm 2 . Ageing is observed to be strongly dependent on the stirp metalisation; gold and nickel perform better than aluminium and copper. (orig.)

  20. Quantitative estimation of electro-osmosis force on charged particles inside a borosilicate resistive-pulse sensor.

    Science.gov (United States)

    Ghobadi, Mostafa; Yuqian Zhang; Rana, Ankit; Esfahani, Ehsan T; Esfandiari, Leyla

    2016-08-01

    Nano and micron-scale pore sensors have been widely used for biomolecular sensing application due to its sensitive, label-free and potentially cost-effective criteria. Electrophoretic and electroosmosis are major forces which play significant roles on the sensor's performance. In this work, we have developed a mathematical model based on experimental and simulation results of negatively charged particles passing through a 2μm diameter solid-state borosilicate pore under a constant applied electric field. The mathematical model has estimated the ratio of electroosmosis force to electrophoretic force on particles to be 77.5%.

  1. Design and test of the borosilicate glass burnable poison rod for Qinshan nuclear power plant core

    International Nuclear Information System (INIS)

    Huang Jinhua; Sun Hanhong

    1988-08-01

    Material for the burnable poison of Qinshan Nuclear Power Plant core is GG-17 borosilicate glass. The chemical composition and physico-chemical properties of GG-17 is very close to Pyrex-7740 glass used by Westinghouse. It is expected from the results of the experiments that the borosilicate glass burnable poison rod can be successfully used in Qinshan Nuclear Power Plant due to good physical, mechanical, corrosion-resistant and irradiaton properties for both GG-17 glass and cold-worked stainless steel cladding. Change of material for burnable poison from boron-bearing stainless steel to borosilicate glass will bring about much more economic benefit to Qinshan Naclear Power Plant

  2. Stress corrosion in a borosilicate glass nuclear wasteform

    International Nuclear Information System (INIS)

    Ringwood, A.E.; Willis, P.

    1984-01-01

    The authors discuss a typical borosilicate glass wasteform which, when exposed to water vapour and water for limited periods, exhibits evidence of stress corrosion cracking arising from the interaction of polar OH groups with stressed glass surfaces. Glass wasteforms may experience similar stress corrosion cracking when buried in a geological repository and exposed to groundwaters over an extended period. This would increase the effective surface areas available for leaching by groundwater and could decrease the lifetime of the wasteform. Conventional leach-testing methods are insensitive to the longer-term effects of stress corrosion cracking. It is suggested that specific fracture-mechanics tests designed to evaluate susceptibility to stress corrosion cracking should be used when evaluating the wasteforms for high-level nuclear wastes. (author)

  3. Electron irradiation induced nanocrystal formation in Cu-borosilicate glass

    Energy Technology Data Exchange (ETDEWEB)

    Sabri, Mohammed Mohammed; Möbus, Günter, E-mail: g.moebus@sheffield.ac.uk [University of Sheffield, Department of Materials Science and Engineering (United Kingdom)

    2016-03-15

    Nanoscale writing of Cu nanoparticles in glasses is introduced using focused electron irradiation by transmission electron microscopy. Two types of copper borosilicate glasses, one with high and another with low Cu loading, have been tested at energies of 200–300 keV, and formation of Cu nanoparticles in a variety of shapes and sizes using different irradiation conditions is achieved. Electron energy loss spectroscopy analysis, combined with high-resolution transmission electron microscopy imaging, confirmed the irradiation-induced precipitated nanoparticles as metallic, while furnace annealing of the glass triggered dendrite-shaped particles of copper oxide. Unusual patterns of nanoparticle rings and chains under focused electron beam irradiation are also presented. Conclusively, electron beam patterning of Cu-loaded glasses is a promising alternative route to well-established femtosecond laser photoreduction of Cu ions in glass.

  4. Viscosity of melts in the sodium borosilicate system

    International Nuclear Information System (INIS)

    Tait, J.C.; Mandolesi, D.L.; Rummens, H.E.C.

    1984-01-01

    The viscosities of a series of glasses in the sodium borosilicate system (5-35Na 2 O, 5-35B 2 O 3 , 45-80SiO 2 mol%) have been determined between 950 and 1500 deg C, using a rotating bob viscometer. A simplex lattice experimental design was used to define a series of compositions suitable for numerical analysis of the data. The viscosity data were fitted using the Fulcher equation for each composition. Nonlinear regression analysis of the viscosities at constant temperatures gave expressions for the variation in viscosity as a function of composition. The results are displayed as isoviscosity contours on the Na 2 O-B 2 O 3 -SiO 2 composition diagram. The viscosity behaviour as a function of composition is discussed in terms of structural bonding in the melt. (author)

  5. Electrical conductivity and viscosity of borosilicate glasses and melts

    DEFF Research Database (Denmark)

    Ehrt, Doris; Keding, Ralf

    2009-01-01

    , 0 to 62·5 mol% B2O3, and 25 to 85 mol% SiO2. The glass samples were characterised by different methods. Refractive indices, density and thermal expansion were measured. Phase separation effects were investigated by electron microscopy. The electrical conductivity of glasses and melts were determined......Simple sodium borosilicate and silicate glasses were melted on a very large scale (35 l Pt crucible) to prepare model glasses of optical quality in order to investigate various properties depending on their structure. The composition of the glass samples varied in a wide range: 3 to 33·3 mol% Na2O...... by impedance measurements in a wide temperature range (250 to 1450°C). The activation energies were calculated by Arrhenius plots in various temperature regions: below the glass transition temperature, Tg, above the melting point, Tl, and between Tg and Tl. Viscosity measurements were carried out...

  6. Commercial Ion Exchange Resin Vitrification in Borosilicate Glass

    International Nuclear Information System (INIS)

    Cicero-Herman, C.A.; Workman, P.; Poole, K.; Erich, D.; Harden, J.

    1998-05-01

    Bench-scale studies were performed to determine the feasibility of vitrification treatment of six resins representative of those used in the commercial nuclear industry. Each resin was successfully immobilized using the same proprietary borosilicate glass formulation. Waste loadings varied from 38 to 70 g of resin/100 g of glass produced depending on the particular resin, with volume reductions of 28 percent to 68 percent. The bench-scale results were used to perform a melter demonstration with one of the resins at the Clemson Environmental Technologies Laboratory (CETL). The resin used was a weakly acidic meth acrylic cation exchange resin. The vitrification process utilized represented a approximately 64 percent volume reduction. Glass characterization, radionuclide retention, offgas analyses, and system compatibility results will be discussed in this paper

  7. Role of IGF-1/IGF-1R in regulation of invasion in DU145 prostate cancer cells

    Directory of Open Access Journals (Sweden)

    Setya Hemani

    2008-07-01

    Full Text Available Abstract Background Prostate cancer progression to androgen independence is the primary cause of mortality by this tumor type. The IGF-1/IGF-1R axis is well known to contribute to prostate cancer initiation, but its contribution to invasiveness and the downstream signalling mechanisms that are involved are unclear at present. Results We examined the invasive response of androgen independent DU145 prostate carcinoma cells to IGF-1 stimulation using Matrigel assays. We then examined the signaling mechanisms and protease activities that are associated with this response. IGF-1 significantly increased the invasive capacity of DU145 cells in vitro, and this increase was inhibited by blocking IGF-1R. We further demonstrated that specific inhibitors of the MAPK and PI3-K pathways decrease IGF-1-mediated invasion. To determine potential molecular mechanisms for this change in invasive capacity, we examined changes in expression and activity of matrix metalloproteinases. We observed that IGF-1 increases the enzymatic activity of MMP-2 and MMP-9 in DU145 cells. These changes in activity are due to differences in expression in the case of MMP-9 but not in the case of MMP-2. This observation is corroborated by the fact that correlated changes of expression in a regulator of MMP-2, TIMP-2, were also seen. Conclusion This work identifies a specific effect of IGF-1 on the invasive capacity of DU145 prostate cancer cells, and furthermore delineates mechanisms that contribute to this effect.

  8. Photon emission induced by brittle fracture of borosilicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Shiota, Tadashi, E-mail: tshiota@ceram.titech.ac.jp [Department of Metallurgy and Ceramic Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Sato, Yoshitaka [Department of Metallurgy and Ceramic Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Kishi, Tetsuo [Department of Chemistry and Materials Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Yasuda, Kouichi [Department of Metallurgy and Ceramic Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2016-05-15

    Photon emission (PE) at wavelength ranges of 430–490 nm (B-PE), 500–600 nm (G-PE) and 610–680 nm (R-PE) caused by brittle fracture was simultaneously measured in the nanosecond-to-microsecond and millisecond time domains for two types of borosilicate glasses: Pyrex-type Tempax glass and BK7 glass. The results were compared to those for silica and soda lime glasses. The time dependence of the PE of Tempax glass was similar to that of silica glass, while the PE intensity was lower. Because Tempax glass contains both silica-rich and borate-rich amorphous phases, the PE must be mainly produced by the fracture of the silica-rich phase. Moreover, the proportion of B-PE of Tempax glass was higher than that of silica glass. This suggests that the measured B-PE might also include very weak PE caused by the fracture of the borate-rich phase. The PE time dependence of BK7 glass was similar to that of soda lime glass, which was different from the case for Tempax glass. The PE intensity of BK7 glass was slightly higher than that of soda lime glass, but much lower than that of Tempax glass. The result indicates that non-bridging oxygen in the glasses affects crack propagation behavior and reduces the PE. - Highlights: • Photon emission (PE) upon brittle fracture of borosilicate glasses was measured. • Pyrex-type Tempax and BK7 glasses showed different PE characteristics. • The rupture of Si–O bonds produces much stronger PE than that of B–O bonds. • Non-bridging oxygen in glass affects crack propagation behavior and reduces the PE.

  9. sup 1 sup 1 B nutation NMR study of powdered borosilicates

    CERN Document Server

    Woo, A J; Han, D Y

    1998-01-01

    In this work, we applied the 1D sup 1 sup 1 B nutation NMR method for the analysis of the local structural environments in powdered borosilicates (SiO sub 2 -B sub 2 O sub 3). Spin dynamics during a rf irradiation for spin I=3/2 was analytically calculated with a density matrix formalism. Spectral simulation programs were written in MATLAB on a PC. Two borosilicates prepared by the sol-gel process at different stabilization temperature were used for the 1D sup 1 sup 1 B nutation NMR experiment. The sup 1 sup 1 B NMR parameters, quadrupole coupling constants (e sup 2 qQ/h) and asymmetry parameters (eta), for each borosilicate were extracted from the nonlinear least-squares fitting. The effects of heat treatments on the local structures of boron sites in borosilicates were discussed.

  10. 1.2. X-ray phase analysis of borosilicate raw material

    International Nuclear Information System (INIS)

    Mirsaidov, U.M.; Kurbonov, A.S.; Mamatov, E.D.

    2015-01-01

    Present article is devoted to X-ray phase analysis of borosilicate raw material. The thermo gram of initial borosilicate ore was considered. The X-ray pattern of initial danburite of Ak-Arhar Deposit was considered as well. The X-ray pattern of danburite of Ak-Arhar Deposit after pre-baking was studied. The X-ray pattern of initial danburite concentrate was studied as well.

  11. 3.6. The kinetics of sulfuric acid decomposition of calcined concentrate of borosilicate ore

    International Nuclear Information System (INIS)

    Mirsaidov, U.M.; Kurbonov, A.S.; Mamatov, E.D.

    2015-01-01

    Present article is devoted to kinetics of sulfuric acid decomposition of calcined concentrate of borosilicate ore. The experimental data of kinetics of extraction of boron oxide from danburite at sulfuric acid decomposition were obtained at 20-90 deg C temperature range and process duration 15-90 minutes. The flowsheet of obtaining of boric acid from borosilicate ores of Ak-Arkhar Deposit by sulfuric acid method was proposed.

  12. A novel low cost polyvinyl alcohol-Nafion-borosilicate membrane separator for microbial fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, B.R. [Department of Civil Engineering, Indian Institute of Technology, Kharagpur, 721302 (India); Noori, Md.T. [Department of Agriculture and Food Engineering, Indian Institute of Technology, Kharagpur, 721302 (India); Ghangrekar, M.M., E-mail: ghangrekar@civil.iitkgp.ernet.in [Department of Civil Engineering, Indian Institute of Technology, Kharagpur, 721302 (India)

    2016-10-01

    Composite membranes were developed from PVA-borosilicate (MP) and PVA-Nafion-borosilicate (MPN) for application in microbial fuel cells (MFCs). The membranes were characterized in terms of water uptake, PBS uptake, oxygen diffusion and proton conductivity. Proton conductivity for MPN (0.07 Scm{sup −1}) was found to be higher as compared to that of MP (0.03 Scm{sup −1}). Oxygen diffusion coefficient for MPN was 1.47 fold lower than that for MP. As a result, MFC with PVA-Nafion-borosilicate membrane exhibited maximum power density of 6.8 Wm{sup −3}, which was 151% higher than the power produced by MFC having PVA-borosilicate membrane and it was comparable with MFC using Nafion 117 (7.1 Wm{sup −3}) membrane separator. This study demonstrates that borosilicate glass membrane incorporated with PVA-Nafion matrix can be a suitable alternative to costly polymeric membrane to increase power output of MFC. Using such membranes MFC can be fabricated at around 11 fold reduced cost as compared to Nafion 117. - Highlights: • Novel membranes using PVA and borosilicate composite were fabricated. • Proton diffusion for MPN was comparable with Nafion117. • MFC-PN produced power density comparable to MFC with Nafion 117 membrane. • MPN was fabricated at almost 11 times reduced cost than Nafion 117 membranes.

  13. Determination of the free enthalpies of formation of borosilicate glasses

    International Nuclear Information System (INIS)

    Linard, Y.

    2000-01-01

    This work contributes to the study of the thermochemical properties of nuclear waste glasses. Results are used to discuss mechanisms and parameters integrated in alteration models of conditioning materials. Glass is a disordered material defined thermodynamically as a non-equilibrium state. Taking into account one order parameter to characterise its configurational state, the metastable equilibrium for the glass was considered and the main thermochemical properties were determined. Calorimetric techniques were used to measure heat capacities and formation enthalpies of borosilicate glasses (from 3 to 8 constitutive oxides). Formation Entropies were measured too, using the entropy theory of relaxation processes proposed by Adam and Gibbs (1965). The configurational entropy contribution were determined from viscosity measurements. This set of data has allowed the calculation of Gibb's free energies of dissolution of glasses in pure water. By comparison with leaching experiments, it has been demonstrated that the decreasing of the dissolution rate at high reaction progress cannot be associated to the approach of an equilibrium between the sound glass and the aqueous solution. The composition changes of the reaction area at the glass surface need to be considered too. To achieve a complete description of the thermodynamic stability, the equilibrium between hydrated de-alkalinized glass and/or the gel layer with the aqueous solution should also be evaluated. (author)

  14. Composition-Structure-Property Relations of Compressed Borosilicate Glasses

    Science.gov (United States)

    Svenson, Mouritz N.; Bechgaard, Tobias K.; Fuglsang, Søren D.; Pedersen, Rune H.; Tjell, Anders Ø.; Østergaard, Martin B.; Youngman, Randall E.; Mauro, John C.; Rzoska, Sylwester J.; Bockowski, Michal; Smedskjaer, Morten M.

    2014-08-01

    Hot isostatic compression is an interesting method for modifying the structure and properties of bulk inorganic glasses. However, the structural and topological origins of the pressure-induced changes in macroscopic properties are not yet well understood. In this study, we report on the pressure and composition dependences of density and micromechanical properties (hardness, crack resistance, and brittleness) of five soda-lime borosilicate glasses with constant modifier content, covering the extremes from Na-Ca borate to Na-Ca silicate end members. Compression experiments are performed at pressures ≤1.0 GPa at the glass transition temperature in order to allow processing of large samples with relevance for industrial applications. In line with previous reports, we find an increasing fraction of tetrahedral boron, density, and hardness but a decreasing crack resistance and brittleness upon isostatic compression. Interestingly, a strong linear correlation between plastic (irreversible) compressibility and initial trigonal boron content is demonstrated, as the trigonal boron units are the ones most disposed for structural and topological rearrangements upon network compaction. A linear correlation is also found between plastic compressibility and the relative change in hardness with pressure, which could indicate that the overall network densification is responsible for the increase in hardness. Finally, we find that the micromechanical properties exhibit significantly different composition dependences before and after pressurization. The findings have important implications for tailoring microscopic and macroscopic structures of glassy materials and thus their properties through the hot isostatic compression method.

  15. Behaviour of ruthenium dioxide particles in borosilicate glasses and melts

    Energy Technology Data Exchange (ETDEWEB)

    Pflieger, Rachel [DEN/DTCD-SCDV/CEA Valrho, Centre de Marcoule, BP17171, 30207 Bagnols-sur-Ceze (France); Institut de Chimie Separative de Marcoule, UMR5257, Centre de Marcoule, BP17171, 30207 Bagnols-sur-Ceze Cedex (France)], E-mail: rachel_pflieger@yahoo.fr; Lefebvre, Leila [DEN/DTCD-SCDV/CEA Valrho, Centre de Marcoule, BP17171, 30207 Bagnols-sur-Ceze (France); Malki, Mohammed [CNRS/CEMHTI-1D Av. de la Recherche Scientifique, 45701 Orleans cedex 2 (France); Polytech Orleans, Universite d' Orleans, 8 rue Leonard de Vinci, 45072 Orleans cedex 2 (France); Allix, Mathieu [CNRS/CEMHTI-1D Av. de la Recherche Scientifique, 45701 Orleans cedex 2 (France); Grandjean, Agnes [DEN/DTCD-SCDV/CEA Valrho, Centre de Marcoule, BP17171, 30207 Bagnols-sur-Ceze (France); Institut de Chimie Separative de Marcoule, UMR5257, Centre de Marcoule, BP17171, 30207 Bagnols-sur-Ceze Cedex (France)

    2009-06-01

    Ruthenium-glass systems are formed during the vitrification of nuclear waste. They are also widely used in micro-electronics because of their unique electrical properties. However, the interaction of this element with the glass matrix remains poorly understood. This work focuses on a RuO{sub 2} particles-nuclear alumino-borosilicate glass system in which the electrical conductivity is known to vary considerably with the RuO{sub 2} content and to become electronic above about 0.5-0.7 vol.% RuO{sub 2} [R. Pflieger, M. Malki, Y. Guari, J. Larionova, A. Grandjean, J. Am. Ceram. Soc., accepted for publication]. Some RuO{sub 2} segregation was observed in SEM/TEM investigations but no continuous chain of RuO{sub 2} particles could be seen. Electron relays between the particles are then necessary for a low-rate percolation, such as the nanoclusters suggested by Adachi et al. [K. Adachi, S. Iida, K. Hayashi, J. Mater. Res. 9 (7) (1994) 1866; K. Adachi, H. Kuno, J. Am. Ceram. Soc. 83 (10) (2000) 2441], which could consist in dissolved ruthenium. Indeed, several observations made here clearly indicate the presence of dissolved ruthenium in the glass matrix, like the modification of the glass density in presence of RuO{sub 2} particles or the diffusion-limited growth of RuO{sub 2} particles in the melt.

  16. Antagonist effects of calcium on borosilicate glass alteration

    Energy Technology Data Exchange (ETDEWEB)

    Mercado-Depierre, S. [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France); Angeli, F., E-mail: frederic.angeli@cea.fr [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France); Frizon, F. [CEA Marcoule, DTCD SECM LP2C, 30207 Bagnols sur Cèze (France); Gin, S. [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France)

    2013-10-15

    Graphical abstract: Display Omitted -- Highlights: •Kinetic study of glass alteration is investigated in calcium-enriched solutions. •New insights into silicon–calcium interactions in glass/cement systems are proposed. •Glass alteration is controlled by pH, Ca concentration and reaction progress. •Evidence of antagonist effects according to the importance of these parameters. -- Abstract: Numerous studies have been conducted on glass and cement durability in contact with water, but very little work to date has focused directly on interactions between the two materials. These interactions are mostly controlled by silicon–calcium reactivity. However, the physical and chemical processes involved remain insufficiently understood to predict the evolution of coupled glass–cement systems used in several industrial applications. Results are reported from borosilicate glass alteration in calcium-rich solutions. Our data show that four distinct behaviors can be expected according to the relative importance of three key parameters: the pH, the reaction progress (short- or long-term alteration) and the calcium concentration. Glass alteration is thus controlled by specific mechanisms depending on the solution chemistry: calcium complexation at the glass surface, precipitation of calcium silicate hydrates (C–S–H) or calcium incorporation in the altered layer. These findings highlight the impact of silicon–calcium interactions on glass durability and open the way for a better understanding of glass–cement mixing in civil engineering applications as well as in nuclear waste storage.

  17. Thorium reactions in borosilicate-glass/water systems

    International Nuclear Information System (INIS)

    Rai, D.; Hess, N.J.; Felmy, A.R.; Moore, D.A.; Yui, M.

    2005-01-01

    Studies were conducted on the dissolution of Th-doped borosilicate glass, a complex assemblage of 24 different elements in various proportions, in a wide range of pH values (0.5 to 12) and carbonate (as high as 6.2 m) and bicarbonate (as high as 1.0 m) concentrations, and as a function of time to determine whether the observed thorium concentrations exhibit an equilibrium phenomenon and to ascertain whether existing thermodynamic data can be used to interpret these results. Measurable Th concentrations were observed in either the very acidic (pH 0.5 to 4) solutions or alkaline solutions containing relatively high carbonate/bicarbonate concentrations. Steady state Th concentrations were reached over time from both the oversaturation and undersaturation directions, indicating that Th concentrations are controlled by an equilibrium solubility phenomenon. The XRD, EXAFS, and thermodynamic analyses of solubility data failed to definitively identify the nature of the solubility-controlling solid in this complex system; however, the data suggests that the solubility-controlling solid most likely involves the Th-silicate phase and that the observed Th concentrations are up to many orders of magnitude lower than in equilibrium with ThO 2 (am). The solubility study also showed that existing thermodynamic data for carbonato complexes of Th can be used to reliably predict Th concentrations in relatively dilute to concentrated carbonate/bicarbonate solutions. (orig.)

  18. Antagonist effects of calcium on borosilicate glass alteration

    International Nuclear Information System (INIS)

    Mercado-Depierre, S.; Angeli, F.; Frizon, F.; Gin, S.

    2013-01-01

    Graphical abstract: Display Omitted -- Highlights: •Kinetic study of glass alteration is investigated in calcium-enriched solutions. •New insights into silicon–calcium interactions in glass/cement systems are proposed. •Glass alteration is controlled by pH, Ca concentration and reaction progress. •Evidence of antagonist effects according to the importance of these parameters. -- Abstract: Numerous studies have been conducted on glass and cement durability in contact with water, but very little work to date has focused directly on interactions between the two materials. These interactions are mostly controlled by silicon–calcium reactivity. However, the physical and chemical processes involved remain insufficiently understood to predict the evolution of coupled glass–cement systems used in several industrial applications. Results are reported from borosilicate glass alteration in calcium-rich solutions. Our data show that four distinct behaviors can be expected according to the relative importance of three key parameters: the pH, the reaction progress (short- or long-term alteration) and the calcium concentration. Glass alteration is thus controlled by specific mechanisms depending on the solution chemistry: calcium complexation at the glass surface, precipitation of calcium silicate hydrates (C–S–H) or calcium incorporation in the altered layer. These findings highlight the impact of silicon–calcium interactions on glass durability and open the way for a better understanding of glass–cement mixing in civil engineering applications as well as in nuclear waste storage

  19. Alpha self irradiation effects in nuclear borosilicate glass

    International Nuclear Information System (INIS)

    Peuget, S.; Roudil, D.; Deschanels, X.; Jegou, C.; Broudic, V.; Bart, J.M.

    2004-01-01

    The properties of actinide glasses are studied in the context of high-level waste management programs. Reprocessing high burnup fuels in particular will increase the minor actinide content in the glass package, resulting in higher cumulative alpha decay doses in the glass, and raising the question of the glass matrix behavior and especially its containment properties. The effect of alpha self-irradiation on the glass behavior is evaluated by doping the glass with a short-lived actinide ( 244 Cm) to reach in several years the alpha dose received by the future glass packages over several thousand years. 'R7T7' borosilicate glasses were doped with 3 different curium contents (0.04, 0.4 and 1.2 wt% 244 CmO 2 ). The density and mechanical properties of the curium-doped glasses were characterized up to 2. 10 18 α/g, revealing only a slight evolution of the macroscopic behavior of R7T7 glass in this range. The leaching behavior of curium-doped glass was also studied by Soxhlet tests. The results do not show any significant evolution of the initial alteration rate with the alpha dose. (authors)

  20. Dynamic fracture and fragmentation patterns of borosilicate laminate glasses

    Directory of Open Access Journals (Sweden)

    Gómez del Río, T.

    2009-10-01

    Full Text Available The dynamic behaviour of laminate borosilicate glasses (BSG with polyvinylbutiral (PVB interfaces (0,38 mm located at different distances from the impact point have been studied and compared with monolithic glass. The mechanical behaviour under impact loads have been studied using a compression split Hopkinson pressure bar (SHPB. In these experiments, the stress-strain curves of the materials at high loading rates and the capability of transmitting and reflecting the impact energy have been determined. The influence of the position of the interface on the fragmentation statistics of the SHPB recovered fragments has also been considered and analysed according to the published theoretical models.

    En este trabajo se ha estudiado los comportamientos dinámicos de un vidrio monolítico de borosilicato y varios laminados de cristal de borosilicato (BSG con intercaras de polyvinylbutiral (PVB (0,38 mm situados a diferentes distancias respecto del punto de impacto. Los resultados de las diferentes configuraciones de laminados se han comparado con el vidrio monolítico. El comportamiento mecánico bajo cargas de impacto se han estudiado realizando ensayos de compresión con una barra Hopkinson (SHPB. A partir de estos experimentos se obtienen las curvas tensión-deformación de los materiales a altas velocidades de carga y su capacidad de transmitir y reflejar la energía del impacto. La influencia de la posición de la interfaz en las estadísticas de la fragmentación de los fragmentos recuperados también se ha considerado y analizado de acuerdo a los modelos teóricos publicados.

  1. Borosilicate glass as a matrix for the immobilization of Savannah River Plant waste

    International Nuclear Information System (INIS)

    Plodinec, M.J.; Wicks, G.G.; Bibler, N.E.

    1982-01-01

    The reference waste form for immobilization of Savannah River Plant (SRP) waste is borosilicate glass. In the reference process, waste is mixed with glass-forming chemicals and melted in a Joule-heated ceramic melter at 1150 0 C. Waste glass made with actual or simulated waste on a small scale and glass made with simulated waste on a large scale confirm that the current reference process and glass-former composition are able to accommodate all SRP waste compositions and can produce a glass with: high waste loading; low leach rates; good thermal stability; high resistance to radiation effects; and good impact resistance. Borosilicate glass has been studied as a matrix for the immobilization of SRP waste since 1974. This paper reviews the results of extensive characterization and performance testing of the glass product. These results show that borosilicate glass is a very suitable matrix for the immobilization of SRP waste. 18 references, 3 figures, 10 tables

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

    International Nuclear Information System (INIS)

    Quintas, A.

    2007-09-01

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

  3. Effect of heat treatment duration on phase separation of sodium borosilicate glass, containing copper

    International Nuclear Information System (INIS)

    Shejnina, T.G.; Gutner, S.Kh.; Anan'in, N.I.

    1989-01-01

    The effect of heat treatment duration on phase separation of sodium borosilicate (SBS) glass, containing copper is studied. It is stated that phase separation close to equilibrium one is attained under 12 hours of heat treatment of SBS glass containing copper

  4. X-ray tomography of feed-to-glass transition of simulated borosilicate waste glasses

    Czech Academy of Sciences Publication Activity Database

    Harris, W.H.; Guillen, D.P.; Kloužek, Jaroslav; Pokorný, P.; Yano, T.; Lee, S.; Schweiger, M. J.; Hrma, P.

    2017-01-01

    Roč. 100, č. 9 (2017), s. 3883-3894 ISSN 0002-7820 Institutional support: RVO:67985891 Keywords : borosilicate glass * computed tomography * glass melting * morphology * nuclear waste * X-ray Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass OBOR OECD: Ceramics Impact factor: 2.841, year: 2016

  5. Evaluation of long-term leaching of borosilicate glass in pure water

    International Nuclear Information System (INIS)

    Lanza, F.; Parnisari, E.

    1979-01-01

    In order to confirm the validity of the model of the dissolving sphere, a series of tests of leaching of borosilicate glasses has been performed. The leaching rate is followed by measurements of weight loss and analysis of the surface composition. An accumulation at the surface of the less soluble cations is observed

  6. X-ray irradiation induced reduction and nanoclustering of lead in borosilicate glass

    NARCIS (Netherlands)

    Stanley, H.B.; Banerjee, D.; Breemen, van L.C.A.; Ciston, J.; Liebscher, C.H.; Martis, V.; Merino, D.H.; Longo, A.; Pattison, P.; Peters, G.W.M.; Portale, G.; Sen, Sabyasachi; Bras, W.

    2014-01-01

    We have studied the formation of nanoparticles in lead sulfide (PbS)-doped borosilicate glass subjected to a two-step nucleation and growth heat treatment using in situ small-angle X-ray scattering (SAXS). The microstructure produced was subsequently characterized using X-ray powder diffraction

  7. Chapter 1. The characteristics of borosilicate ores of Ak-Arkhar Deposit of Tajikistan

    International Nuclear Information System (INIS)

    Mirsaidov, U.M.; Kurbonov, A.S.; Mamatov, E.D.

    2015-01-01

    Present article is devoted to characteristics of borosilicate ores of Ak-Arkhar Deposit of Tajikistan. The chemical composition of danburite ore of Ak-Arkhar Deposit was defined. The chemical composition of danburite ore concentrate of Ak-Arkhar Deposit was defined as well.

  8. Modelling the evaporation of boron species. Part 1: Alkali-free borosilicate glass melts

    NARCIS (Netherlands)

    Limpt, J.A.C. van; Beerkens, R.G.C.; Cook, S.; O'Connor, R.; Simon, J.

    2011-01-01

    A laboratory test facility has been used to measure the boron evaporation rates from borosilicate glass melts. The impact of furnace atmosphere composition and glass melt composition on the temperature dependent boron evaporation rates has been investigated experimentally. In Part 1 of this paper

  9. Development of aluminosilicate and borosilicate glasses as matrices for CANDU high-level waste

    International Nuclear Information System (INIS)

    Strathdee, G.G.; McIntyre, N.S.; Taylor, P.

    1979-01-01

    This paper covers the results of analyses of two radioactive nepheline syenite glass blocks recovered from in-ground leaching experiments at the Chalk River Nuclear Laboratories. Current research on borosilicate glasses for immobilization of high-level waste is also described

  10. Characterization of borosilicate glasses containing simulated high-level radioactive wastes from PNC

    International Nuclear Information System (INIS)

    Terai, R.; Eguchi, K.; Yamanaka, H.

    1979-01-01

    The characterization of borosilicate glasses containing simulated HLW from PNC has been carried out. Phase separation of molybdates, volatilization, viscosity, electrical resistivity, thermal conductivity, elastic modulus, chemical durability, and devitrification of these glasses have been measured, and the suitability of the glasses for the vitrified solidification processes is discussed from the viewpoint of safety

  11. Quantification of the boron speciation in alkali borosilicate glasses by electron energy loss spectroscopy

    DEFF Research Database (Denmark)

    Cheng, D.S.; Yang, G.; Zhao, Y.Q.

    2015-01-01

    developed a method based on electron energy loss spectroscopy (EELS) data acquisition and analyses, which enables determination of the boron speciation in a series of ternary alkali borosilicate glasses with constant molar ratios. A script for the fast acquisition of EELS has been designed, from which...

  12. Integrated Optic Surface Plasmon Resonance Measurements in a Borosilicate Glass Substrate

    Directory of Open Access Journals (Sweden)

    Antonino Parisi

    2008-11-01

    Full Text Available The surface plasmon resonance (SPR technique is a well-known optical method that can be used to measure the refractive index of organic nano-layers adsorbed on a thin metal film. Although there are many configurations for measuring biomolecular interactions, SPR-based techniques play a central role in many current biosensing experiments, since they are the most suited for sensitive and quantitative kinetic measurements. Here we give some results from the analysis and numerical elaboration of SPR data from integrated optics experiments in a particular borosilicate glass, chosen for its composition offering the rather low refractive index of 1.4701 at 633 nm wavelength. These data regard the flow over the sensing region (metal window of different solutions with refractive indexes in the range of interest (1.3÷1.5 for the detection of contaminants in aqueous solutions. After a discussion of the principles of SPR, of the metal window design optimization by means of optical interaction numerical modeling, and of waveguide fabrication techniques, we give a description of system setup and experimental results. Optimum gold film window thickness and width in this guided-wave configuration has been for the first time derived and implemented on an integrated optic prototype device. Its characterization is given by means of the real time waveguide output intensity measurements, which correspond to the interaction between the sensing gold thin film window and the flowing analyte. The SPR curve was subsequently inferred. Finally, a modified version of the device is reported, with channel waveguides arranged in a Y-junction optical circuit, so that laser source stability requirements are lowered by a factor of 85 dB, making possible the use of low cost sources in practical applications.

  13. Phase separation of cesium from lead borosilicate glass by heat treatment under a reducing atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhanglian; Okada, Takashi, E-mail: t-okada@u-fukui.ac.jp; Nishimura, Fumihiro; Yonezawa, Susumu

    2016-11-05

    Highlights: • Cesium was phase separated from lead borosilicate glass under a reductive atmosphere. • The phase separation occurred on the glass surface that was in contact with the gas. • The leachability of cesium was enhanced by the phase separation. • The degree of such enhancement varied depending on the heat treatment conditions. - Abstract: A phase-separation technique for removing sodium from glass using a heat-treatment method under a reducing atmosphere was previously developed for sodium recovery from waste glass. In this study, this technique was applied to cesium-containing lead borosilicate glass to concentrate the cesium in phase-separated sodium-rich materials for efficient cesium extraction. The theoretical phase-separation temperature of the sodium-rich phase was simulated by thermodynamic equilibrium calculations and was predicted to occur below 700 °C for lead borosilicate glass. Experimentally, a simulated lead borosilicate glass was melted at 1000 °C and subsequently annealed below 700 °C under a CO-containing reducing atmosphere. The phase separation of cesium was found to occur with sodium enrichment on the glass surface that was in contact with the gas phase, promoting cesium extraction from the treated glass using water. The cesium extraction efficiency was affected by the surface area of the treated glass that was in contact with water, and under the examined conditions, the cesium extraction efficiency was up to 66%. Phase separation using reductive heat treatment, combined with a water leaching technique, is suggested to be effective for extracting cesium incorporated in borosilicate glass waste.

  14. World Gas Prospects: Which Role for the Middle East? Perspectives mondiales du gaz naturel : quel rôle pourrait jouer le Moyen-Orient ?

    Directory of Open Access Journals (Sweden)

    Chabrelie M. F.

    2006-12-01

    Full Text Available Since the early 1970s, the policies of energy diversification that have been implemented in the industrialized countries and in many developing countries have enabled natural gas to regularly increase its role in the world energy balance. Thus, during the past twenty years, natural gas recorded the highest growth rate among fossil fuels, and its share in the energy market has gradually risen from 18. 9% in 1975 to 23% in 1997. Today, thanks to favorable economic and environmental factors, natural gas has become the fuel of choice on many markets. Indeed, gas is blessed with a certain number of favorable assets (abundant reserves, flexibility, high-performance uses which give it a major role in all energy demand forecast scenarios. The most spectacular development will indisputably take place in the power generation sector. Endowed with a considerable gas potential, the Middle East will represent an essential source of supply for many industrialized countries and several gas export projects, either by LNG tanker or by pipelines are currently being contemplated. During the past decade, the contribution of natural gas to the energy mix also grew substantially in most Middle Eastern countries. The increase in gas demand should continue at a sustained rate, mainly driven by the power generation sector, petrochemicals and energy consumption by the hydrocarbons industry. These promising prospects for gas demand in most of the markets in the region might lead to the development of an intra-regional network. However, although opportunities exist, the region will have to meet many challenges in order to contribute more largely to the world gas balance in the years to come. de diversification énergétique mises en Suvre dans les pays industrialisés et dans de nombreux pays en voie de développement depuis le début des années 1970 ont permis au gaz naturel d'accroître régulièrement sa présence dans le bilan énergétique mondial. Ainsi, au cours des

  15. La femme du ménage The "perfect wife". The bride's role in wedding organization: setting the stage for unequal task sharing in marriage

    Directory of Open Access Journals (Sweden)

    Florence Maillochon

    2009-09-01

    Full Text Available Ce texte étudie la division sexuelle du travail dans l’organisation de la cérémonie de mariage. Les temporalités des hommes et des femmes divergent progressivement au cours des différentes étapes de la préparation du mariage (de l’élaboration du projet jusqu’au jour J en passant par l’organisation de la fête. Les femmes consacrent toujours plus de temps au collectif que les hommes. La cérémonie de mariage ne constitue donc pas seulement une étape de formation du couple mais aussi un point d’ancrage et d’incorporation du « partage inégal » du travail domestique au sein du couple. Au cours d’une série d’épreuves symboliques et techniques qu’elles traversent pour se métamorphoser en mariée et en épouse, les femmes apprennent progressivement à devenir la femme du ménage.This article studies the sexual division of labour when organizing the wedding ceremony. Men’s and women’s temporalities gradually diverge through the various steps of wedding preparation (from elaboration of the project up to the "big day" itself. Women spend more time than men on collective tasks.  The wedding ceremony is not only a key moment in founding the couple, but also a step towards instituting and embedding the “unequal sharing” of domestic work within the couple. The different symbolic and technical tests women go through to metamorphose into a spouse and bride make them learn how to become the "perfect wife".

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

    OpenAIRE

    Ponsot, In?s M. M. M.; Pontikes, Yiannis; Baldi, Giovanni; Chinnam, Rama K.; Detsch, Rainer; Boccaccini, Aldo R.; Bernardo, Enrico

    2014-01-01

    Ceramics and glass ceramics based on industrial waste have been widely recognized as competitive products for building applications; however, there is a great potential for such materials with novel functionalities. In this paper, we discuss the development of magnetic sintered glass ceramics based on two iron-rich slags, coming from non-ferrous metallurgy and recycled borosilicate glass. The substantial viscous flow of the glass led to dense products for rapid treatments at relatively low te...

  17. Chemical durability of lead borosilicate glass matrix under simulated geological conditions

    International Nuclear Information System (INIS)

    Yalmali, Vrunda S.; Deshingkar, D.S.; Wattal, P.K.

    2002-03-01

    The lead borosilicate glass has been developed for vitrification of High Level Waste (HLW) stored at Trombay. This waste is contains especially high contents of sodium, uranium sulphate and iron. The glasses containing HLW are to be ultimately disposed into deep geological repositories. Long term leach rates under simulated geological conditions need to be evaluated for glass matrix. Studies were taken up to estimate the lead borosilicate glass WTR-62 matrix for chemical durability in presence of synthetic ground water. The leachant selected was based on composition of ground water sample near proposed repository site. In the first phase of these tests, the experiments were conducted for short duration of one and half month. The leaching experiments were conducted in presence of a) distilled water b) synthetic ground water c) synthetic ground water containing granite, bentonite and ferric oxide and d) synthetic ground water containing humic acid at 100 0 C. The leachate samples were analysed by pHmetry , ion chromatography and UV -VIS spectrophotometry. The normalised leach rates for lead borosilicate WTR- 62 glass matrix based on silica, boron and sulphate analyses of leachates were of the order of 10 -3 to 10 -5 gms/cm 2 /day for 45 days test period in presence of synthetic ground water as well as in presence of other materials likely to be present along with synthetic ground water. These rates are comparable to those of sodium borsilicate glass matrices reported in literature. It is known that the leach rates of glass matrix decrease with longer test durations due to formation of leached layer on its surface. The observed leach rates of lead borosilicate WTR- 62 glass matrix for 45 day tests under simulated geological conditions were found to be sufficiently encouraging to take up long term tests for evaluating its performances under repository conditions. (author)

  18. Effect of ThO2 concentration on thermo-physical properties of barium borosilicate glass

    International Nuclear Information System (INIS)

    Mishra, R.K.; Munshi, A.K.; Kaushik, C.P.; Raj, Kanwar; Shobha, M.; Srikhande, V.K.; Kothiyal, G.P.; Tyagi, A.K.

    2006-01-01

    An advanced heavy water reactor is being developed at Bhabha Atomic Research Centre (BARC) India with an aim of utilizing thorium for power generation. The high level radioactive liquid waste (HLW) generated from reprocessing of Th-based spent fuel is expected to contain Th as one of the main constituents other than fission products, corrosion products, actinides and added chemicals. Barium borosilicate (BBS) glass is being used for vitrification of the HLW generated at the reprocessing plant at BARC, Trombay, Mumbai

  19. Determination of occluded helium and oxygen in irradiated borosilicate glass samples

    International Nuclear Information System (INIS)

    Ramanjaneyulu, P.S.; Kulkarni, A.S.; Shrivastava, K.C.; Yadav, C.S.; Saxena, M.K.; Tomar, B.S.; Ramakumar, K.L.; Shah, J.G.

    2015-01-01

    Occluded gases in irradiated borosilicate glass were determined at 573, 873 and 1273 K for understanding the radiation damage in glass matrix. Hot vacuum extraction coupled with a quadrupole mass spectrometer technique was employed for the measurements. Relative sensitivity factors of various gases in QMS system were also determined and used for gas composition calculations. At 573 K only helium was found to get released whereas at 873 and 1273 K both helium and oxygen were released with major fraction of oxygen. (author)

  20. Influence of Mo on the structure of borosilicate glass for the immobilization of high level waste

    International Nuclear Information System (INIS)

    Petrov, I.; Dimitriev, Y.; Kashchieva, E.

    2015-01-01

    It has been shown that the classic multi-borosilicate glass with concentration of MoO 3 has a low melting in the range of 1300 to 1400 ° C, but for achieving of complete homogenization and vitrification it is required temperature above 1400 ° C. Under this temperature in all tested samples areas of crystallization were observed, due to incomplete vitrification processes. It is understood that in all multicomponent borosilicate glass featuring MoO 3 , occur micro vitrification processes, and at a concentration of MoO 3 above 20% - macro segregation; It has been shown that the introduction of Nd in compound borosilicate glass featuring MoO 3 is observed crystallization of the phase Na 0.5 Nd 0.5 Mo, and it has been also found that the phase Na 0.5 Nd 0.5 Mo 4 can be synthesized either by solid phase reaction or supercooled melt. The results of surveys show that It is possible to prevent the occurrence of liquid phase separation in the studied multicomponent glass. From a structural point of view, the cause of liquid phase separation is the result of structural incompatibility of molybdenum units with structural units borosilicate network since not been established links Mo-O-B-O and Mo-Si. From a thermodynamic point of view in the lamination multi windows may be due to overlapping areas of delamination in component binary and triple systems. From the kinetic point of view of course the liquid phase by settling, and crystallization may be due to imbalances conditions the cooling process, in the course of which flow various processes of imbalances metastable settling, followed by crystallization of molybdate phases

  1. Electron irradiation effect on bubble formation and growth in a sodium borosilicate glass

    International Nuclear Information System (INIS)

    Chen, X.; Birtcher, R. C.; Donnelly, S. E.

    2000-01-01

    In this study, the authors studied simultaneous and intermittent electron irradiation effects on bubble growth in a simple sodium borosilicate glass during Xe ion implantation at 200 C. Simultaneous electron irradiation increases the average bubble size in the glass. This enhanced diffusion is also shown by the migration of Xe from bubbles into the matrix when the sample is irradiated by an electron beam after the Xe implantation

  2. Preliminary assessment of modified borosilicate glasses for chromium and ruthenium immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Farid, Osama M. [Reactors Department, Nuclear Research Center, Atomic Energy Authority of Egypt, P.O. 13759, Inshas, Cairo (Egypt); Centre of Nuclear Engineering (CNE), Department of Materials, Imperial College London, London, SW7 2BP (United Kingdom); Abdel Rahman, R.O., E-mail: alaarehab@yahoo.com [Hot Laboratory Center, Atomic Energy Authority of Egypt, P.O. 13759, Inshas, Cairo (Egypt)

    2017-01-15

    The feasibility of using modified alkali borosilicate glasses for ruthenium and chromium immobilization is preliminary assessed by investigating the immobilization system structure under normal conditions. Within this context, reference alkali borosilicate, and simulated Magnox-modified glasses were prepared and studied. The results indicate that ruthenium is immobilized in the vitreous structure as encapsulated RuO{sub 2} crystallites that act as seeds for heterogeneous nucleation of other crystalline phases. The presence of Zn, as modifier, has contributed to chromium immobilization in zincochromite spinel structure, whereas Ca is accommodated in the vitreous structure. Immobilization performance was evaluated by conducting conservative static leach test and studying the leached glass. Leached glass morphology was altered, where near surface reference glass is leached over 400 nm and simulated Magnox-modified sample is altered over 300 nm. Normalized release rates are within normal range for borosilicate material. For simulated Magnox-modified sample, Ca and alkali structural element, i.e. Na and Li, are leached via ion-exchange reaction. The ion-exchanged fraction equals 1.06 × 10{sup −8} mol/m{sup 2} s and chromium has slightly lower normalized release rate value than ruthenium. - Highlights: • The presence of modifiers and waste oxides led to localized de-vitrification. • Ruthenium is encapsulated within the vitreous glass network as RuO{sub 2} crystals. • Chromium is immobilized within the zincochromite spinel structure. • Pitting and cracks induced by leaching did not affect the immobilization performance.

  3. Development of borosilicate glass compositions for the immobilisation of the UK's separated plutonium stocks

    International Nuclear Information System (INIS)

    Harrison, M. T.; Scales, C. R.

    2008-01-01

    The UK inventory of separated civil plutonium is expected to exceed 100 tonnes by 2010. Whilst the majority of this could be used in the manufacture of MOx (Mixed Oxide) fuel in future power generation scenarios, options for the disposal of surplus plutonium are currently being investigated by Nexia Solutions Ltd on behalf of the UK's Nuclear Decommissioning Authority (NDA). One of the options being considered is immobilisation in a durable glass matrix followed by long term storage and subsequent final repository disposal. A preliminary experimental survey assessed a selection of potential glass systems on the basis of Pu-surrogate (cerium) loading, durability, and ease of processing. Following this, a number of borosilicate compositions have been taken forward into a more detailed investigation in order to fully qualify their potential for Pu-immobilisation. The selected compositions are lanthanide borosilicate (LaBS), alkali tin silicate (ATS) and high-lanthanide alkali borosilicate (modified-MW). For this second series of experiments, hafnium was selected as the Pu surrogate, and a study of the potential waste loading as a function of temperature for the three selected compositions is described in this paper. Furthermore, several variations of the LaBS composition were fabricated in order to investigate the effect of total lanthanide content on melting temperature. The benchmark of 10 wt% HfO 2 incorporation is achievable for all three glasses with temperatures of 1200, 1300 and 1400 deg. C required for ATS, modified-MW and LaBS respectively. (authors)

  4. X-ray absorption and Raman spectroscopy studies of molybdenum environments in borosilicate waste glasses

    Science.gov (United States)

    McKeown, David A.; Gan, Hao; Pegg, Ian L.

    2017-05-01

    Mo-containing high-level nuclear waste borosilicate glasses were investigated as part of an effort to improve Mo loading while avoiding yellow phase crystallization. Previous work showed that additions of vanadium decrease yellow phase formation and increases Mo solubility. X-ray absorption spectroscopy (XAS) and Raman spectroscopy were used to characterize Mo environments in HLW borosilicate glasses and to investigate possible structural relationships between Mo and V. Mo XAS spectra for the glasses indicate isolated tetrahedral Mo6+O4 with Mo-O distances near 1.75 Å. V XANES indicate tetrahedral V5+O4 as the dominant species. Raman spectra show composition dependent trends, where Mo-O symmetrical stretch mode frequencies (ν1) are sensitive to the mix of alkali and alkaline earth cations, decreasing by up to 10 cm-1 for glasses that change from Li+ to Na+ as the dominant network-modifying species. This indicates that MoO4 tetrahedra are isolated from the borosilicate network and are surrounded, at least partly, by Na+ and Li+. Secondary ν1 frequency effects, with changes up to 7 cm-1, were also observed with increasing V2O5 and MoO3 content. These secondary trends may indicate MoO4-MoO4 and MoO4-VO4 clustering, suggesting that V additions may stabilize Mo in the matrix with respect to yellow phase formation.

  5. Aqueous corrosion of borosilicate glasses. Nature and properties of alteration layers

    International Nuclear Information System (INIS)

    Trotignon, Laurent

    1990-01-01

    This research thesis addresses physical and chemical processes which occur during aqueous corrosion of silicates, and the study of the properties of their interfaces with solutions, and thus issues related to the fate of high activity nuclear wastes which are embedded in a vitreous matrix as the potential release of radionuclides towards the environment then depends on the glass parcel behaviour submitted to chemical attacks which could alter it, notably by aqueous corrosion. The objective is then to model the dissolution of nuclear glass over long periods of time, and to predict the behaviour of radionuclides. The author compared the corrosion and alteration layers of gradually more complex borosilicate glasses, from a ternary sodium borosilicate glass to a simulated nuclear glass (the French reference glass R7T7). Complexity is increased by adding oxides. After some theoretical recalls on the structure and corrosion of borosilicate glasses, the author presents the studied materials, the corrosion experiments, and analytical techniques used to study alteration layers. The mechanism of formation of altered layers is studied based on corrosion experiments performed at 90 C on the whole set of glasses. Alteration layers formed on corroded glasses are studied and compared by using various techniques: electronic microscopy, high energy ion beams, spectroscopy, infrared, photo-electron spectroscopy. Implications for underground storage of nuclear glasses are discussed

  6. High-level waste borosilicate glass a compendium of corrosion characteristics. Volume 1

    International Nuclear Information System (INIS)

    Cunnane, J.C.

    1994-03-01

    Current plans call for the United States Department of Energy (DOE) to start up facilities for vitrification of high-level radioactive waste (HLW) stored in tanks at the Savannah River Site, Aiken, South Carolina, in 1995; West Valley Demonstration Project, West Valley, New York, in 1996; and at the Hanford Site, Richland, Washington, after the year 2000. The product from these facilities will be canistered HLW borosilicate glass, which will be stored, transported, and eventually disposed of in a geologic repository. The behavior of this glass waste product, under the range of likely service conditions, is the subject of considerable scientific and public interest. Over the past few decades, a large body of scientific information on borosilicate waste glass has been generated worldwide. The intent of this document is to consolidate information pertaining to our current understanding of waste glass corrosion behavior and radionuclide release. The objective, scope, and organization of the document are discussed in Section 1.1, and an overview of borosilicate glass corrosion is provided in Section 1.2. The history of glass as a waste form and the international experience with waste glass are summarized in Sections 1.3 and 1.4, respectively

  7. Influence of Cu doping in borosilicate bioactive glass and the properties of its derived scaffolds.

    Science.gov (United States)

    Wang, Hui; Zhao, Shichang; Xiao, Wei; Xue, Jingzhe; Shen, Youqu; Zhou, Jie; Huang, Wenhai; Rahaman, Mohamed N; Zhang, Changqing; Wang, Deping

    2016-01-01

    Copper doped borosilicate glasses (BG-Cu) were studied by means of FT-IR, Raman, UV-vis and NMR spectroscopies to investigate the changes that appeared in the structure of borosilicate glass matrix by doping copper ions. Micro-fil and immunohistochemistry analysis were applied to study the angiogenesis of its derived scaffolds in vivo. Results indicated that the Cu ions significantly increased the B-O bond of BO4 groups at 980 cm(-1), while they decrease that of BO2O(-) groups at 1440-1470 cm(-1) as shown by Raman spectra. A negative shift was observed from (11)B and (29)Si NMR spectra. The (11)B NMR spectra exhibited a clear transformation from BO3 into BO4 groups, caused by the agglutination effect of the Cu ions and the charge balance of the agglomerate in the glass network, leading to a more stable glass network and lower ions release rate in the degradation process. Furthermore, the BG-Cu scaffolds significantly enhanced blood vessel formation in rat calvarial defects at 8 weeks post-implantation. Generally, it suggested that the introduction of Cu into borosilicate glass endowed glass and its derived scaffolds with good properties, and the cooperation of Cu with bioactive glass may pave a new way for tissue engineering. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Mechanical behavior of cellular borosilicate glass with pressurized Ar-filled closed pores

    International Nuclear Information System (INIS)

    Wang Bo; Matsumaru, Koji; Yang Jianfeng; Fu Zhengyi; Ishizaki, Kozo

    2012-01-01

    High strength borosilicate foams were fabricated by melting glass powder under high-pressure argon gas and subsequent heat treatment of the glass bulk at atmospheric pressure. In the first step, borosilicate glass powder was melted at 1100 °C for 1 h by capsule-free hot isostatic pressing (HIPing) under a high gas pressure of 10–70 MPa. Pressurized Ar-filled spherical pores were introduced into the glass, and argon atoms were dissolved in the glass network structure. The expansion of argon-filled pores and the release of the dissolved Ar gas resulted in the formation of pressurized Ar-filled closed pores by isothermal heat treatment at 800 °C for 10 min. A high porosity of up to 80% with a bimodal distribution of micro-size cells was obtained for the resultant cellular borosilicate glass. By increasing the total gas pressure from 10 to 70 MPa, the compressive strength and the Young’s modulus were increased considerably from 15 to 52 MPa and from 4.1 to 12.6 GPa, respectively, which can be substantially attributed to the high collapse stress from the high enclosed gas pressure. The cellular glass with a high porosity showed a large failure strain under uniaxial compression.

  9. Iron-borosilicate soft magnetic composites: The correlation between processing parameters and magnetic properties for high frequency applications

    Energy Technology Data Exchange (ETDEWEB)

    Gheiratmand, T., E-mail: t.gheiratmand@yahoo.com; Madaah Hosseini, H.R., E-mail: Madaah@sharif.edu; Seyed Reihani, S.M.

    2017-05-01

    Iron-borosilicate soft magnetic composites are suitable magnetic materials for high temperature and high frequency applications. In this research two different techniques have been applied to fabricate these composites: uniaxial pressing following by sintering and spark plasma sintering. Different processing parameters including the content of borosilicate, the amount of compaction pressure and the size of iron particles have been evaluated through the study of microstructure and magnetic properties. The microstructural observations showed that the borosilicate is distributed on the iron grain boundaries enhancing the resistivity and causing the loss of eddy currents. Increasing the compaction pressure was led to the decrease of electrical resistivity. By increasing the frequency both real and imaginary parts of permeability decreased. The use of higher content of borosilicate resulted in the lower decreasing slop of permeability. Best combination of density, permeability and electrical resistivity was obtained in the sample with 2 wt% of borosilicate. In addition, the densification of powders with fine particles was more difficult than coarse particles due to the inter particles friction and bridging effects. Furthermore, as the particles size increases the size of open porosities before sintering where the borosilicate could aggregate enhances. This could yields to the increase in the electrical resistivity. The high ratio of surface to the volume in the powders with fine particles results in the developing the demagnetizing fields and subsequently, decreasing the permeability. The highest relative density (99.99% of theoretical density) with best distribution of borosilicate was achieved in the composites produced by spark plasma sintering (SPS). The relaxation frequency, obtained from imaginary part of permeability, was found as 340 Hz in the composites made by SPS. - Highlights: • Iron-borosilicate SMC was produced for high temperature and frequency

  10. Ultrasonic and structural features of some borosilicate glasses ...

    Indian Academy of Sciences (India)

    2017-06-09

    Jun 9, 2017 ... transform infrared spectroscopy, density and ultrasonic techniques to debate the issue of the role ... in the fields of electronics [3], optical lenses with high refrac- ..... of the borate glass will be close packed through the polymer-.

  11. Fiche technique du spermogramme et du spermocytogramme ...

    African Journals Online (AJOL)

    En Afrique la stérilité du couple constitue un drame social. Selon l'OMS, environ 8 à 12 % des couples africains sont touchés par une infertilité. La responsabilité masculine dans la stérilité est comprise entre 30 à 40%. Les causes de l'infertilité masculine peuvent être l'impuissance et/ ou l'altération du sperme. L'étude de ...

  12. Deep-UV Raman spectroscopic analysis of structure and dissolution rates of silica-rich sodium borosilicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, Eric M [ORNL; WindischJr., Charles F. [Pacific Northwest National Laboratory (PNNL); Burton, Sarah D. [Pacific Northwest National Laboratory (PNNL); Bovaird, Chase C. [Pacific Northwest National Laboratory (PNNL)

    2010-01-01

    As part of ongoing studies to evaluate relationships between structure and rates of dissolution of silicate glasses in aqueous media, sodium borosilicate glasses of composition Na2O xB2O3 (3 x)SiO2, with x 1 (Na2O/B2O3 ratio 1), were analyzed using deep-UV Raman spectroscopy. Results were quantified in terms of the fraction of SiO4 tetrahedra with one non-bridging oxygen (Q3) and then correlated with Na2O and B2O3 content. The Q3 fractionwas found to increase with increasing Na2O content, in agreement with studies on related glasses, and, as long as the value of x was not too high, this contributed to higher rates of dissolution in single pass flow-through testing. In contrast, dissolution rates were less strongly determined by the Q3 fraction when the value of x was near unity, and appeared to grow larger upon further reduction of the Q3 fraction. Results were interpreted to indicate the increasingly important role of network hydrolysis in the glass dissolution mechanism as the BO4 tetrahedron replaces the Q3 unit as the charge-compensating structure for Na+ ions. Finally, the use of deep-UV Raman spectroscopy was found to be advantageous in studying finely powdered glasses in cases where visible Raman spectroscopy suffered from weak Raman scattering and fluorescence interference.

  13. Les Cahiers du CREAD

    African Journals Online (AJOL)

    Admin

    politique de bas prix exercée par la Russie et le Qatar vient confirmer ce constat ; s'ajoute à cela l'entrée éventuelle du gaz non conven- tionnel, dont son prix actuel de 3/4 $US, offre aux USA l'opportunité d'être exportateur de ..... les compagnies à produire en matière du gaz naturel, tels le prix du gaz naturel, le prix des ...

  14. Bulletin du CRDI #124

    International Development Research Centre (IDRC) Digital Library (Canada)

    Les femmes jouent un rôle important dans les exploitations minières artisanales et à petite échelle en Afrique subsaharienne. De concert ... Couverture du livre: Une vie saine pour les femmes et les enfants vulnérables · Couverture du livre: Entre el activismo y la intervención · Couverture du livre: Revitalizing Health for All.

  15. Bulletin du CRDI #125

    International Development Research Centre (IDRC) Digital Library (Canada)

    L'IOSRS remporte le prix de la diplomatie scientifique · GrowInclusive : la plateforme tant attendue est en construction · Toutes les nouvelles. Activités à venir. Semaine du développement international 2018. Le CRDI célébrera la Semaine du développement international du 4 au 10 février 2018. Suivez-nous sur Twitter et ...

  16. A Raman spectroscopy study on the effects of intermolecular hydrogen bonding on water molecules absorbed by borosilicate glass surface

    Science.gov (United States)

    Li, Fabing; Li, Zhanlong; Wang, Ying; Wang, Shenghan; Wang, Xiaojun; Sun, Chenglin; Men, Zhiwei

    2018-05-01

    The structural forms of water/deuterated water molecules located on the surface of borosilicate capillaries have been first investigated in this study on the basis of the Raman spectral data obtained at different temperatures and under atmospheric pressure for molecules in bulk and also for molecules absorbed by borosilicate glass surface. The strongest two fundamental bands locating at 3063 cm-1 (2438 cm-1) in the recorded Raman spectra are assigned here to the Osbnd H (Osbnd D) bond stretching vibrations and they are compared with the corresponding bands observed at 3124 cm-1 (2325 cm-1) in the Raman spectrum of ice Ih. Our spectroscopic observations have indicated that the structure of water and deuterated water molecules on borosilicate surface is similar to that of ice Ih (hexagonal phase of ice). These observations have also indicated that water molecules locate on the borosilicate surface so as to construct a bilayer structure and that strong and weak intermolecular hydrogen bonds are formed between water/deuterated molecules and silanol groups on borosilicate surface. In accordance with these findings, water and deuterated water molecules at the interface of capillary have a higher melting temperature.

  17. Aqueous corrosion of borosilicate glasses: experiments, modeling and Monte-Carlo simulations; Alteration par l'eau des verres borosilicates: experiences, modelisation et simulations Monte-Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Ledieu, A

    2004-10-01

    This work is concerned with the corrosion of borosilicate glasses with variable oxide contents. The originality of this study is the complementary use of experiments and numerical simulations. This study is expected to contribute to a better understanding of the corrosion of nuclear waste confinement glasses. First, the corrosion of glasses containing only silicon, boron and sodium oxides has been studied. The kinetics of leaching show that the rate of leaching and the final degree of corrosion sharply depend on the boron content through a percolation mechanism. For some glass contents and some conditions of leaching, the layer which appears at the glass surface stops the release of soluble species (boron and sodium). This altered layer (also called the gel layer) has been characterized with nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. Second, additional elements have been included in the glass composition. It appears that calcium, zirconium or aluminum oxides strongly modify the final degree of corrosion so that the percolation properties of the boron sub-network is no more a sufficient explanation to account for the behavior of these glasses. Meanwhile, we have developed a theoretical model, based on the dissolution and the reprecipitation of the silicon. Kinetic Monte Carlo simulations have been used in order to test several concepts such as the boron percolation, the local reactivity of weakly soluble elements and the restructuring of the gel layer. This model has been fully validated by comparison with the results on the three oxide glasses. Then, it has been used as a comprehensive tool to investigate the paradoxical behavior of the aluminum and zirconium glasses: although these elements slow down the corrosion kinetics, they lead to a deeper final degree of corrosion. The main contribution of this work is that the final degree of corrosion of borosilicate glasses results from the competition of two opposite mechanisms

  18. Water leaching of borosilicate glasses: experiments, modeling and Monte Carlo simulations; Alteration par l'eau des verres borosilicates: experiences, modelisation et simulations Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Ledieu, A

    2004-10-15

    This work is concerned with the corrosion of borosilicate glasses with variable oxide contents. The originality of this study is the complementary use of experiments and numerical simulations. This study is expected to contribute to a better understanding of the corrosion of nuclear waste confinement glasses. First, the corrosion of glasses containing only silicon, boron and sodium oxides has been studied. The kinetics of leaching show that the rate of leaching and the final degree of corrosion sharply depend on the boron content through a percolation mechanism. For some glass contents and some conditions of leaching, the layer which appears at the glass surface stops the release of soluble species (boron and sodium). This altered layer (also called the gel layer) has been characterized with nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. Second, additional elements have been included in the glass composition. It appears that calcium, zirconium or aluminum oxides strongly modify the final degree of corrosion so that the percolation properties of the boron sub-network is no more a sufficient explanation to account for the behavior of these glasses. Meanwhile, we have developed a theoretical model, based on the dissolution and the reprecipitation of the silicon. Kinetic Monte Carlo simulations have been used in order to test several concepts such as the boron percolation, the local reactivity of weakly soluble elements and the restructuring of the gel layer. This model has been fully validated by comparison with the results on the three oxide glasses. Then, it has been used as a comprehensive tool to investigate the paradoxical behavior of the aluminum and zirconium glasses: although these elements slow down the corrosion kinetics, they lead to a deeper final degree of corrosion. The main contribution of this work is that the final degree of corrosion of borosilicate glasses results from the competition of two opposite mechanisms

  19. Water leaching of borosilicate glasses: experiments, modeling and Monte Carlo simulations; Alteration par l'eau des verres borosilicates: experiences, modelisation et simulations Monte Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Ledieu, A

    2004-10-15

    This work is concerned with the corrosion of borosilicate glasses with variable oxide contents. The originality of this study is the complementary use of experiments and numerical simulations. This study is expected to contribute to a better understanding of the corrosion of nuclear waste confinement glasses. First, the corrosion of glasses containing only silicon, boron and sodium oxides has been studied. The kinetics of leaching show that the rate of leaching and the final degree of corrosion sharply depend on the boron content through a percolation mechanism. For some glass contents and some conditions of leaching, the layer which appears at the glass surface stops the release of soluble species (boron and sodium). This altered layer (also called the gel layer) has been characterized with nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. Second, additional elements have been included in the glass composition. It appears that calcium, zirconium or aluminum oxides strongly modify the final degree of corrosion so that the percolation properties of the boron sub-network is no more a sufficient explanation to account for the behavior of these glasses. Meanwhile, we have developed a theoretical model, based on the dissolution and the reprecipitation of the silicon. Kinetic Monte Carlo simulations have been used in order to test several concepts such as the boron percolation, the local reactivity of weakly soluble elements and the restructuring of the gel layer. This model has been fully validated by comparison with the results on the three oxide glasses. Then, it has been used as a comprehensive tool to investigate the paradoxical behavior of the aluminum and zirconium glasses: although these elements slow down the corrosion kinetics, they lead to a deeper final degree of corrosion. The main contribution of this work is that the final degree of corrosion of borosilicate glasses results from the competition of two opposite mechanisms

  20. Aqueous corrosion of borosilicate glasses: experiments, modeling and Monte-Carlo simulations; Alteration par l'eau des verres borosilicates: experiences, modelisation et simulations Monte-Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Ledieu, A

    2004-10-01

    This work is concerned with the corrosion of borosilicate glasses with variable oxide contents. The originality of this study is the complementary use of experiments and numerical simulations. This study is expected to contribute to a better understanding of the corrosion of nuclear waste confinement glasses. First, the corrosion of glasses containing only silicon, boron and sodium oxides has been studied. The kinetics of leaching show that the rate of leaching and the final degree of corrosion sharply depend on the boron content through a percolation mechanism. For some glass contents and some conditions of leaching, the layer which appears at the glass surface stops the release of soluble species (boron and sodium). This altered layer (also called the gel layer) has been characterized with nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. Second, additional elements have been included in the glass composition. It appears that calcium, zirconium or aluminum oxides strongly modify the final degree of corrosion so that the percolation properties of the boron sub-network is no more a sufficient explanation to account for the behavior of these glasses. Meanwhile, we have developed a theoretical model, based on the dissolution and the reprecipitation of the silicon. Kinetic Monte Carlo simulations have been used in order to test several concepts such as the boron percolation, the local reactivity of weakly soluble elements and the restructuring of the gel layer. This model has been fully validated by comparison with the results on the three oxide glasses. Then, it has been used as a comprehensive tool to investigate the paradoxical behavior of the aluminum and zirconium glasses: although these elements slow down the corrosion kinetics, they lead to a deeper final degree of corrosion. The main contribution of this work is that the final degree of corrosion of borosilicate glasses results from the competition of two opposite mechanisms

  1. Advances in understanding the structure of borosilicate glasses: A Raman spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Manara, D.; Grandjean, A. [CEA Marcoule, Serv Confinement Deches and Vitrificat, DTCD, DEN - 30 (France); Neuville, D.R. [Institut Physique Globe, Physique des Mineraux et Magmas, CNRS, F-75252 Paris 05 (France)

    2009-05-15

    This study is focused on the behavior of ternary SiO{sub 2}-Na{sub 2}O-B{sub 2}O{sub 3} borosilicate glasses at temperatures between 298 and 1800 K. Unpolarized Raman spectra were measured up to high temperature. SiO{sub 2}-Na{sub 2}O-B{sub 2}O{sub 3} glass samples were prepared with different values of the ratio R [Na{sub 2}O]/[B{sub 2}O{sub 3}], while the ratio K = [SiO{sub 2}]/[B{sub 2}O{sub 3}] was kept constant and equal 2.12. Spectra were measured at room temperature in samples with 0.43 {<=} R {<=} 1.68, and the effect of the modifier content was clearly observed in these glasses, only in partial agreement with previous literature results. In particular, the formation in the glass of sodium-danburite units Na{sub 2}O-B{sub 2}O{sub 3}-2SiO{sub 2} was postulated. This feature led to a new assessment of R{sup *}, the critical value of R above which every new alkali atom added to the system breaks a Fo-O-Fo (Fo=glass former) bridge causing depolymerization of the glass. A revised formula is proposed to obtain the value of R{sup *} as a function of K. Raman spectra measured at high temperature yielded important information about the temperature-dependent evolution of the borosilicate system. In particular, borate and borosilicate units including tetra-coordinated boron seem to be unstable at high temperature, where the formation of metaborate chains or rings is fostered. Above 1500 degrees C, evaporation of borate compounds is clearly observed, stemming from the small sample size. (authors)

  2. Influence of Cu doping in borosilicate bioactive glass and the properties of its derived scaffolds

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hui [School of Materials Science and Engineering, Tongji University, Shanghai 2001804 (China); Zhao, Shichang [Department of Orthopedic Surgery, Shanghai Sixth People' s Hospital, Shanghai Jiao Tong University, Shanghai 200233 (China); Xiao, Wei [Department of Materials Science and Engineering, and Center for Biomedical Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409-0340 (United States); Xue, Jingzhe [Department of Chemistry, Tongji University, Shanghai 200092 (China); Shen, Youqu [Department of Materials Science and Engineering, and Center for Biomedical Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409-0340 (United States); Zhou, Jie; Huang, Wenhai [School of Materials Science and Engineering, Tongji University, Shanghai 2001804 (China); Rahaman, Mohamed N. [Department of Materials Science and Engineering, and Center for Biomedical Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409-0340 (United States); Zhang, Changqing, E-mail: shzhangchangqing@163.com [Department of Orthopedic Surgery, Shanghai Sixth People' s Hospital, Shanghai Jiao Tong University, Shanghai 200233 (China); Wang, Deping, E-mail: wdpshk@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, Shanghai 2001804 (China)

    2016-01-01

    Copper doped borosilicate glasses (BG–Cu) were studied by means of FT-IR, Raman, UV–vis and NMR spectroscopies to investigate the changes that appeared in the structure of borosilicate glass matrix by doping copper ions. Micro-fil and immunohistochemistry analysis were applied to study the angiogenesis of its derived scaffolds in vivo. Results indicated that the Cu ions significantly increased the B–O bond of BO{sub 4} groups at 980 cm{sup −1}, while they decrease that of BO{sub 2}O{sup −} groups at 1440–1470 cm{sup −1} as shown by Raman spectra. A negative shift was observed from {sup 11}B and {sup 29}Si NMR spectra. The {sup 11}B NMR spectra exhibited a clear transformation from BO{sub 3} into BO{sub 4} groups, caused by the agglutination effect of the Cu ions and the charge balance of the agglomerate in the glass network, leading to a more stable glass network and lower ions release rate in the degradation process. Furthermore, the BG–Cu scaffolds significantly enhanced blood vessel formation in rat calvarial defects at 8 weeks post-implantation. Generally, it suggested that the introduction of Cu into borosilicate glass endowed glass and its derived scaffolds with good properties, and the cooperation of Cu with bioactive glass may pave a new way for tissue engineering. - Highlights: • Agglutination effect of Cu{sup 2+} and charge balance of agglomerate lead to more stable glass. • Lower degradability and lower ions release were found in BG-Cu scaffolds. • Excellent angiogenesis and sustain Cu{sup 2+} release were endowed by doping Cu.

  3. "Cirque du Freak."

    Science.gov (United States)

    Rivett, Miriam

    2002-01-01

    Considers the marketing strategies that underpin the success of the "Cirque du Freak" series. Describes how "Cirque du Freak" is an account of events in the life of schoolboy Darren Shan. Notes that it is another reworking of the vampire narrative, a sub-genre of horror writing that has proved highly popular with both adult and…

  4. New insight into nanoparticle precipitation by electron beams in borosilicate glasses

    Science.gov (United States)

    Sabri, M. M.; Möbus, G.

    2017-06-01

    Nanoprecipitation in different oxide glasses by means of electron irradiation in transmission electron microscopy (TEM) has been compared in this study. Upon irradiation, groups or patterns of nanoparticles with various morphologies and sizes were formed in borosilicate glasses, loaded with zinc, copper, and silver. The study successfully includes loading ranges for the target metal from doping level (1%) over medium level (20%) to majority phase (60%). It is found that particle patterning resolution is affected by parallel processes of amorphous phase separation, glass ablation, and delocalised precipitation. In addition, via an in-situ study, it is confirmed that by heating alone without irradiation, no precipitate nanoparticles form.

  5. Photoelastic examination of borosilicate glass discs used in the insulating legs for the NSF tandem

    International Nuclear Information System (INIS)

    Acton, W.J.; Cundy, D.

    1981-04-01

    The results are presented of a photoelastic stress analysis carried out to establish the effect of re-annealing borosilicate glass discs used in the insulating legs of the 30 MV tandem van de Graaff accelerator of the NSF. The results show that re-annealing of the glass discs has no measurable effect on reducing the high stress at inclusions and re-emphasise the need to exercise great care in selecting suitable discs for use in the insulating legs. (U.K.)

  6. Preliminary assessment of the controlled release of radionuclides from waste packages containing borosilicate waste glass

    International Nuclear Information System (INIS)

    Strachan, D.M.; McGrail, B.P.; Apted, M.J.; Engle, D.W.; Eslinger, P.W.

    1990-06-01

    The purpose of this report is to provide a preliminary assessment of the release-rate for an engineered barriers subsystem (EBS) containing waste packages of defense high-level waste borosilicate glass at geochemical and hydrological conditions similar to the those at Yucca Mountain. The relationship between the proposed Waste Acceptance Preliminary Specifications (WAPS) test of glass- dissolution rate and compliance with the NRC's release-rate criterion is also evaluated. Calculations are reported for three hierarchical levels: EBS analysis, waste-package analysis, and waste-glass analysis. The following conclusions identify those factors that most acutely affect the magnitude of, or uncertainty in, release-rate performance

  7. High-level waste borosilicate glass: A compendium of corrosion characteristics. Volume 3

    International Nuclear Information System (INIS)

    Cunnane, J.C.

    1994-03-01

    The objective of this document is to summarize scientific information pertinent to evaluating the extent to which high-level waste borosilicate glass corrosion and the associated radionuclide release processes are understood for the range of environmental conditions to which waste glass may be exposed in service. Alteration processes occurring within the bulk of the glass (e.g., devitrification and radiation-induced changes) are discussed insofar as they affect glass corrosion. Volume III contains a bibliography of glass corrosion studies, including studies that are not cited in Volumes I and II

  8. New insight into nanoparticle precipitation by electron beams in borosilicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Sabri, M.M.; Moebus, G. [University of Sheffield, Department of Materials Science and Engineering (United Kingdom)

    2017-06-15

    Nanoprecipitation in different oxide glasses by means of electron irradiation in transmission electron microscopy (TEM) has been compared in this study. Upon irradiation, groups or patterns of nanoparticles with various morphologies and sizes were formed in borosilicate glasses, loaded with zinc, copper, and silver. The study successfully includes loading ranges for the target metal from doping level (1%) over medium level (20%) to majority phase (60%). It is found that particle patterning resolution is affected by parallel processes of amorphous phase separation, glass ablation, and delocalised precipitation. In addition, via an in-situ study, it is confirmed that by heating alone without irradiation, no precipitate nanoparticles form. (orig.)

  9. Determination of boron in borosilicate glasses by neutron capture prompt gamma-ray activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Jr, J E; Lindstrom, R M

    1987-01-01

    Major levels of boron in borosilicate glasses were determined nondestructively by neutron activation analysis. The effects of neutron self-shielding by boron (1 to 8% by weight) are examined. Results of the analysis of a series of glasses with increasing boron composition are 1.150 +- .005% and 7.766 +- .035% for the low and high members of the series. Once analyzed, the glasses are useful as secondary standards for alpha track counting, and also ion and electron microprobe analyses of glasses. 12 refs.; 3 tables.

  10. A review of phase separation in borosilicate glasses, with reference to nuclear fuel waste immobilization

    International Nuclear Information System (INIS)

    Taylor, P.

    1990-08-01

    This report reviews information on miscibility limits in borosilicate glass-forming systems. It includes both a literature survey and an account of experimental work performed within the Canadian Nuclear Fuel Waste Management Program. Emphasis is placed on the measurement and depiction of miscibility limits in multicomponent (mainly quaternary) systems, and the effects of individual components on the occurrence of phase separation. The behaviour of the multicomponent system is related to that of simpler (binary and ternary) glass systems. The possible occurrence of phase separation, as well as its avoidance, during processing of nuclear waste glasses is discussed

  11. Influence of iron ions on the structural properties of Zn-borosilicate glasses

    International Nuclear Information System (INIS)

    Music, S.; Gotic, M.; Popovic, S.

    1989-01-01

    The objectives of this study were to determine the influence of iron ions on the appearance of crystalline phases in Zn-borosilicate glasses, and to obtain information about valence state and coordination of iron ions. The systems Na 2 O-ZnO-B 2 O 3 -SiO 2 and ZnO-B 2 O 3 -SiO 2 were doped with α-Fe 2 O 3 . X-ray diffraction, IR spectroscopy and 57 Fe Moessbauer spectroscopy were used as experimental techniques. (author) 32 refs.; 5 figs.; 5 tabs

  12. High-level waste borosilicate glass: A compendium of corrosion characteristics. Volume 3

    Energy Technology Data Exchange (ETDEWEB)

    Cunnane, J.C. [comp.; Bates, J.K.; Bradley, C.R. [Argonne National Lab., IL (United States)] [and others

    1994-03-01

    The objective of this document is to summarize scientific information pertinent to evaluating the extent to which high-level waste borosilicate glass corrosion and the associated radionuclide release processes are understood for the range of environmental conditions to which waste glass may be exposed in service. Alteration processes occurring within the bulk of the glass (e.g., devitrification and radiation-induced changes) are discussed insofar as they affect glass corrosion. Volume III contains a bibliography of glass corrosion studies, including studies that are not cited in Volumes I and II.

  13. X-ray absorption and Raman spectroscopy studies of molybdenum environments in borosilicate waste glasses

    Energy Technology Data Exchange (ETDEWEB)

    McKeown, David A., E-mail: davidm@vsl.cua.edu; Gan, Hao; Pegg, Ian L.

    2017-05-15

    Mo-containing high-level nuclear waste borosilicate glasses were investigated as part of an effort to improve Mo loading while avoiding yellow phase crystallization. Previous work showed that additions of vanadium decrease yellow phase formation and increases Mo solubility. X-ray absorption spectroscopy (XAS) and Raman spectroscopy were used to characterize Mo environments in HLW borosilicate glasses and to investigate possible structural relationships between Mo and V. Mo XAS spectra for the glasses indicate isolated tetrahedral Mo{sup 6+}O{sub 4} with Mo-O distances near 1.75 Å. V XANES indicate tetrahedral V{sup 5+}O{sub 4} as the dominant species. Raman spectra show composition dependent trends, where Mo-O symmetrical stretch mode frequencies (ν{sub 1}) are sensitive to the mix of alkali and alkaline earth cations, decreasing by up to 10 cm{sup −1} for glasses that change from Li{sup +} to Na{sup +} as the dominant network-modifying species. This indicates that MoO{sub 4} tetrahedra are isolated from the borosilicate network and are surrounded, at least partly, by Na{sup +} and Li{sup +}. Secondary ν{sub 1} frequency effects, with changes up to 7 cm{sup −1}, were also observed with increasing V{sub 2}O{sub 5} and MoO{sub 3} content. These secondary trends may indicate MoO{sub 4}-MoO{sub 4} and MoO{sub 4}-VO{sub 4} clustering, suggesting that V additions may stabilize Mo in the matrix with respect to yellow phase formation. - Highlights: •Raman and XAS data indicate isolated MoO{sub 4} tetrahedra from the borosilicate network. •Mo-O stretch frequency is sensitive to network-modifying Li and Na concentrations. •Mo-O stretch frequency shifts were also seen with increasing V{sub 2}O{sub 5} and MoO{sub 3} content. •The Raman trends may indicate MoO{sub 4}-MoO{sub 4} and MoO{sub 4}-VO{sub 4} clustering in the glass. •V may stabilize Mo in the glass matrix avoiding yellow phase formation.

  14. Conversion of radwaste-loaded zeolites into a borosilicate glass to improve their properties for final disposal (preliminary results)

    International Nuclear Information System (INIS)

    Kazemian, H.; Ghannadi Maraghe, M.; Mallah, M.H.; Firooz Zare, M.; Kooshkestani, R.; Naghavi, S.Sh.

    2002-01-01

    Research was undertaken to fix radioisotopes from simulated nuclear waste streams into durable and stable borosilicate glass matrices based on the conversion of different type of zeolites. It was found that the selectivity of Iranian clinoptilolite and the relevant synthetic zeolite toward cesium and strontium were quite good whereas the leach resistance of the loaded zeolite was relatively poor. To improve the leach resistance of the used zeolites, conversion of the spent exchangers into borosilicate glass was investigated. Results obtained in the non active bench scale tests phase were promising. It is concluded that spent zeolites loaded with radioactive materials can be converted into a durable, high leach resistant borosilicate glass, a proper matrix for final disposal of nuclear waste. (author)

  15. The role of technical progress in the process of recalculating oil reserves; Le role du progres technique dans le processus de renouvellement des reserves petrolieres

    Energy Technology Data Exchange (ETDEWEB)

    Boulard, J.N. [Total/Fina/Institut Francais du Petrole (IFP), 92 - Rueil-Malmaison (France)

    1999-08-01

    Contrary to the concept of resources (which is essentially a geological one), the notion of reserves designates the quantities that are technically and economically recoverable. Beyond the production-related effect, the reserves therefore evolve over time in accordance with numerous technical and economic parameters. Among these parameters, it can be seen that technical progress plays a considerable role throughout the process of converting resources into reserves, including progress in the identification, accessibility and processing of the resources, and improvements in economic viability. After having tackled the problem of measuring the 'technical progress effects' and citing examples, we demonstrate that the evolution in oil reserves is subject to three types of impact. These are a quantitative impact by significantly improving the recovery rates or making it possible to identify hitherto undetectable oil fields, a qualitative impact by widening the resource base thanks to the adoption of new categories of oil (in particular the so-called 'unconventional' oils) and by carrying out the gradual substitution between these resources of differing qualities. There is also a dynamic impact, through the acceleration of resource availability. Through these three approaches, technical progress makes makes it possible to ensure continuity in oil supply and contributes significantly to the recalculation of reserves. It therefore acts as a compensating factor, counterbalancing the progressive depletion of resources. (author)

  16. On fluidization of borosilicate glasses in intense radiation fields - 16055

    International Nuclear Information System (INIS)

    Ojovan, Michael; Moebus, Guenter; Tsai, Jim; Cook, Stuart; Yang, Guang

    2009-01-01

    The viscosity is rate-limiting for many processes in glassy materials such as homogenisation and crystallisation. Changes in the viscous flow behaviour in conditions of long-term irradiation are of particular interest for glassy materials used in nuclear installations as well as for nuclear waste immobilising glasses. We analyse the viscous flow behaviour of oxide amorphous materials in conditions of electron-irradiation using the congruent bond lattice model of oxide materials accounting for the flow-mediating role of broken bonds termed configurons. An explicit equation of viscosity was obtained which is in agreement with experimental data for non-irradiated glasses and shows for irradiated glasses, first, a significant decrease of viscosity, and, second, a stepwise reduction of the activation energy of flow. An equation for glass-transition temperature was derived which shows that irradiated glasses have lower glass transition temperatures. Intensive electron irradiation of glasses causes their fluidization due to non-thermal bond breaking and can occur below the glass transition temperature. Due to surface tension forces fluidization of glasses at enough high electron flux densities can result in modification of nano-size volumes and particles such as those experimentally observed under TEM electron beams. (authors)

  17. Le plurilinguisme du perroquet

    Directory of Open Access Journals (Sweden)

    Manuel Mühlbacher

    2012-05-01

    Full Text Available La figure du perroquet occupe une position ambiguë face à la question de la traduction. Il est capable d’imiter des paroles en toutes les langues, mais il n’est capable d’en comprendre aucune — il ne peut que répéter des sons, c’est-à-dire des signifiants. Le traducteur semble faire le contraire quand il passe d’une langue à une autre en tâchant de transmettre une signification semblable par d’autres signes. L’article vise à discuter le rôle du traducteur et sa relation, éventuellement équivoque, au perroquet, en analysant la traduction allemande de Trois Contes par André Stoll et Cora van Kleffens. Un décalage au niveau sémantique peut éclairer l’interprétation du texte, par exemple en explicitant des allusions sous-jacentes, tandis que le transfert de la syntaxe française en allemand pose souvent des problèmes considérables. Comment le traducteur peut-il reproduire des structures syntaxiques qui n’existent pas en allemand, mais qui ne cessent de revenir dans le texte français ? Que faire si le texte se met à jouer au perroquet et finit par se singer lui-même ? André Stoll et Cora van Kleffens ont su trouver des stratégies pour affronter ces difficultés.The figure of the parrot holds an ambiguous position towards the question of translation. It is able to imitate all languages, but it will never understand any of them – its only skill is to mimic sounds, i.e. mere signifiers. On the contrary, the translator seems to be the antithesis of the parrot when he moves from one language to another. He endeavours to convey a similar meaning, but by different signs. The article aims at discussing the role of the translator and his or her eventually equivocal relation to the parrot by means of analysing the German translation of Trois Contes by André Stoll and Cora van Kleffens. Whereas a semantic divergence can result in a different tendency on the level of interpretation, as in the case of an underlying

  18. Ecologie du phytoplancton du lac Kivu

    Directory of Open Access Journals (Sweden)

    Sarmento, H.

    2008-01-01

    Full Text Available Speciation within the African Coffee Pathogen. Cet article analyse s'il est avantageux d'utiliser le compost au lieu de l'engrais minéral pour produire la laitue dans la zone urbaine et péri-urbaine de Yaoundé. Les résultats de terrain montrent l'obtention de rendements et profits plus élevés lorsqu'on utilise le compost. Les résultats de la fonction de production Cobb-Douglas prouvent que l'utilisation du compost est statistiquement significative pour expliquer la variation de rendement de la laitue et que le compost est l'intrant le plus productif. D'autres résultats montrent que le compost fournit la matière organique utile au sol et que les besoins d'irrigation en eau de la culture sont réduits grâce à l'utilisation du compost. Par conséquent, malgré le fait que l'application du compost demande une main-d'oeuvre beaucoup plus élevée, son utilisation est généralement bénéfique pour les agriculteurs vivant aux alentours de Yaoundé. Les programmes de vulgarisation de cet intrant pour encourager son adoption devraient donc figurer parmi les points prioritaires dans la politique agricole du gouvernement camerounais.

  19. 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

  20. Chemical durability of borosilicate glasses containing simulated high-level nuclear wastes, 1

    International Nuclear Information System (INIS)

    Hara, Shigeo; Terai, Ryohei; Yamanaka, Hiroshi

    1983-01-01

    The Soxhlet-type leaching test apparatus has been developed to evaluate the chemical durability of some borosilicate glasses containing simulated High-Level nuclear Wastes, HLW. After the leaching over the temperature range of 50 0 -95 0 C, the weight loss of specimens with time was determined on both the samples of blocks and grains, and various components dissolved into water were analyzed by atomic absorption and colorimetry technique. It was found that Soxhlet-type test method was more useful than JIS test method, because the specimens in Soxhlet type apparatus were forced always to react with pure water and the mechanism of leaching could be evaluate accurately. The chemical durability of commercial glasses decreases generally with increasing of alkali contents in glasses. In the case of these borosilicate glasses containing HLW, however, the leachability was apparently independent on the alkali contents because of the complexity of these glass compositions. The variation of leaching rate with temperature suggests that dissolution mechanism changes with temperature. (author)

  1. Fabrication of Silicon Nitride Dental Core Ceramics with Borosilicate Veneering material

    Science.gov (United States)

    Wananuruksawong, R.; Jinawath, S.; Padipatvuthikul, P.; Wasanapiarnpong, T.

    2011-10-01

    Silicon nitride (Si3N4) ceramic is a great candidate for clinical applications due to its high fracture toughness, strength, hardness and bio-inertness. This study has focused on the Si3N4 ceramic as a dental core material. The white Si3N4 was prepared by pressureless sintering at relative low sintering temperature of 1650 °C in nitrogen atmosphere. The coefficient of thermal expansion (CTE) of Si3N4 ceramic is lower than that of Zirconia and Alumina ceramic which are popular in this field. The borosilicate glass veneering was employed due to its compatibility in thermal expansion. The sintered Si3N4 specimens represented the synthetic dental core were paintbrush coated by a veneer paste composed of borosilicate glass powder (tube furnace between 1000-1200°C. The veneered specimens fired at 1100°C for 15 mins show good bonding, smooth and glossy without defect and crazing. The veneer has thermal expansion coefficient as 3.98×10-6 °C-1, rather white and semi opaque, due to zirconia addition, the Vickers hardness as 4.0 GPa which is closely to the human teeth.

  2. Dielectric behaviour of (Ba,Sr)TiO3 perovskite borosilicate glass ceramics

    International Nuclear Information System (INIS)

    Yadav, Avadhesh Kumar; Gautam, C.R.

    2013-01-01

    Various perovskite (Ba,Sr)TiO 3 borosilicate glasses were prepared by rapid melt-quench technique in the glass system ((Ba 1-x Sr x ).TiO 3 )-(2SiO 2 .B 2 O 3 )-(K 2 O)-(La 2 O 3 ). On the basis of differential thermal analysis results, glasses were converted into glass ceramic samples by regulated heat treatment schedules. The dielectric behaviour of crystallized barium strontium titanate borosilicate glass ceramic samples shows diffuse phase transition. The study depicts the dielectric behaviour of glass ceramic sample BST5K1L0.2S814. The double relaxation was observed in glass ceramic samples corresponding 80/20% Ba/Sr due to change in crystal structure from orthorhombic to tetragonal and tetragonal to cubic with variation of temperature. The highest value of dielectric constant was found to be 48289 for the glass ceramic sample BST5K1L0.2S814. The high value of dielectric constant attributed to space charge polarization between the glassy phase and perovskite phase. Due to very high value of dielectric constant, such glass ceramics are used for high energy storage devices. La 2 O 3 acts as nucleating agent for crystallization of glass to glass ceramics and enhances the dielectric constant and retarded dielectric loss. Such glass ceramics can be used in high energy storage devices such as barrier layer capacitors, multilayer capacitors etc. (author)

  3. Rhenium solubility in borosilicate nuclear waste glass: implications for the processing and immobilization of technetium-99.

    Science.gov (United States)

    McCloy, John S; Riley, Brian J; Goel, Ashutosh; Liezers, Martin; Schweiger, Michael J; Rodriguez, Carmen P; Hrma, Pavel; Kim, Dong-Sang; Lukens, Wayne W; Kruger, Albert A

    2012-11-20

    The immobilization of technetium-99 ((99)Tc) in a suitable host matrix has proven to be a challenging task for researchers in the nuclear waste community around the world. In this context, the present work reports on the solubility and retention of rhenium, a nonradioactive surrogate for (99)Tc, in a sodium borosilicate glass. Glasses containing target Re concentrations from 0 to 10,000 ppm [by mass, added as KReO(4) (Re(7+))] were synthesized in vacuum-sealed quartz ampules to minimize the loss of Re from volatilization during melting at 1000 °C. The rhenium was found as Re(7+) in all of the glasses as observed by X-ray absorption near-edge structure. The solubility of Re in borosilicate glasses was determined to be ~3000 ppm (by mass) using inductively coupled plasma optical emission spectroscopy. At higher rhenium concentrations, additional rhenium was retained in the glasses as crystalline inclusions of alkali perrhenates detected with X-ray diffraction. Since (99)Tc concentrations in a glass waste form are predicted to be wastes, assuming Tc as Tc(7+) and similarities between Re(7+) and Tc(7+) behavior in this glass system.

  4. Fabrication of Silicon Nitride Dental Core Ceramics with Borosilicate Veneering material

    International Nuclear Information System (INIS)

    Wananuruksawong, R; Jinawath, S; Wasanapiarnpong, T; Padipatvuthikul, P

    2011-01-01

    Silicon nitride (Si 3 N 4 ) ceramic is a great candidate for clinical applications due to its high fracture toughness, strength, hardness and bio-inertness. This study has focused on the Si 3 N 4 ceramic as a dental core material. The white Si 3 N 4 was prepared by pressureless sintering at relative low sintering temperature of 1650 deg. C in nitrogen atmosphere. The coefficient of thermal expansion (CTE) of Si 3 N 4 ceramic is lower than that of Zirconia and Alumina ceramic which are popular in this field. The borosilicate glass veneering was employed due to its compatibility in thermal expansion. The sintered Si 3 N 4 specimens represented the synthetic dental core were paintbrush coated by a veneer paste composed of borosilicate glass powder ( 2 O 3 - partial stabilized zirconia) and 30 wt% of polyvinyl alcohol (5 wt% solution). After coating the veneer on the Si 3 N 4 specimens, the firing was performed in electric tube furnace between 1000-1200 deg. C. The veneered specimens fired at 1100 deg. C for 15 mins show good bonding, smooth and glossy without defect and crazing. The veneer has thermal expansion coefficient as 3.98x10 -6 deg. C -1 , rather white and semi opaque, due to zirconia addition, the Vickers hardness as 4.0 GPa which is closely to the human teeth.

  5. Er3+-Al2O3 nanoparticles doping of borosilicate glass

    International Nuclear Information System (INIS)

    Massera, Jonathan; Petit, Laeticia; Hupa, Leena; Hupa, Mikko; Koponen, Joona; Glorieux, Benoit

    2015-01-01

    Novel borosilicate glasses were developed by adding in the glass batch Er 3+ -Al 2 O 3 nanoparticles synthetized by using a soft chemical method. A similar nanoparticle doping with modified chemical vapour deposition (MCVD) process was developed to increase the efficiency of the amplifying silica fibre in comparison to using MCVD and solution doping. It was shown that with the melt quench technique, a Er 3+ -Al 2 O 3 nanoparticle doping neither leads to an increase in the Er 3+ luminescence properties nor allows one to control the rare-earth chemical environment in a borosilicate glass. The site of Er 3+ in the Er 3+ -Al 2 O 3 nanoparticle containing glass seems to be similar as in glasses with the same composition prepared using standard raw materials. We suspect the Er 3+ ions to diffuse from the nanoparticles into the glass matrix. There was no clear evidence of the presence of Al 2 O 3 nanoparticles in the glasses after melting. (author)

  6. 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 considerable amount of literature published on chemical dissolution behavior and apatite-forming ability of potentially bioactive glasses, the majority of this literature has been produced on silicate glass chemistries using different experimental and measurement protocols. It follows that inter-comparison of different datasets reveals inconsistencies between experimental groups. There are also some major experimental challenges or choices that need to be carefully navigated to unearth the mechanisms governing the chemical degradation behavior and kinetics of boron-containing bioactive glasses, and to accurately determine the composition-structure-property relationships. In order to address these challenges, a simplified

  7. Du Pont de Nemours

    NARCIS (Netherlands)

    Ros JPM; LAE

    1994-01-01

    Dit rapport over Du Pont de Nemours (produktie van o.a. chemische stoffen) is gepubliceerd binnen het Samenwerkingsproject Procesbeschrijvingen Industrie Nederland (SPIN). In het kader van dit project is informatie verzameld over industriele bedrijven of industriele processen ter ondersteuning

  8. A kinetic approach of sulphur behaviour in borosilicate glasses and melts: implications for sulphate incorporation in nuclear waste glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lenoir, Marion [Service de Confinement des Dechets et Vitrification - Laboratoire d' Etudes de Base sur les Verres, CEA Valrho, Centre de Marcoule, 30207 Bagnols sur Ceze (France); Physique des Mineraux et des Magmas, UMR 7047 - CNRS, Institut de Physique du Globe de Paris, 7 place Jussieu, 75252 Paris Cedex 05 (France); Grandjean, Agnes [Service de Confinement des Dechets et Vitrification - Laboratoire d' Etudes de Base sur les Verres, CEA Valrho, Centre de Marcoule, 30207 Bagnols sur Ceze (France); Neuville, Daniel R. [Physique des Mineraux et des Magmas, UMR 7047 - CNRS, Institut de Physique du Globe de Paris, 7 place Jussieu, 75252 Paris Cedex 05 (France)

    2008-07-01

    The kinetics of sulphate decomposition in a borosilicate melt were studied using in situ Raman spectroscopy. This technique permits the quantification of the amount of sulphate dissolved in a borosilicate glass as a function of heating time by comparison with measurements obtained by microprobe WDS (Wavelength Dispersive Spectrometry). In order to quantify the content of sulphate obtained by Raman spectroscopy, the integrated intensity of the sulphate band at 985 cm{sup -1} was scaled to the sum of the integrated bands between 800 and 1200 cm{sup -1}, bands that are assigned to Q{sup n} silica units on the basis of previous literature. Viscosities of some borosilicate glasses are also presented here in order to study the kinetics of sulphate decomposition as a function of the viscosity of the melt. This underlines the importance of variations in viscosity depending on the composition of the melt and thus shows that viscosity is an important parameter governing the kinetics of decomposition of sulphate in borosilicate glasses. (authors)

  9. Deep-UV Raman spectroscopic analysis of structure and dissolution rates of silica-rich sodium borosilicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, Charles F.; Pierce, Eric M.; Burton, Sarah D.; Bovaird, Chase C.

    2011-03-24

    As part of ongoing studies to evaluate the relationships between structural variations in silicate glasses and rates of glass dissolution in aqueous media, molecular structures present in sodium borosilicate glasses of composition Na2O.xB2O3.(3-x)SiO2, with x 1 (Na2O/B2O3 ratio 1), were analyzed using deep-UV Raman spectroscopy. The results were quantified in terms of the fraction of SiO4 tetrahedra with one non-bridging oxygen (Q3) and then correlated with Na2O and B2O3 content. Increasing Na2O was found to raise the fraction of Q3 units in the glasses systematically, in agreement with studies on related glasses, and, as long as the value of x was not too high, contribute to higher rates of dissolution in single pass flow-through testing. The finding was obtained across more than one series of silica-rich glasses prepared for independent dissolution studies. In contrast, dissolution rates were less strongly determined by the Q3 fraction when the value of x was near unity and appeared to grow larger upon further reduction of the Q3 fraction. The results were interpreted to indicate the increasingly important role of network hydrolysis in the glass dissolution mechanism as the BO4 tetrahedron replaces the Q3 unit as the charge-compensating structure for Na+ ions. Finally, the use of deep-UV Raman spectroscopy was found to be advantageous in studying finely powdered glasses in cases where visible Raman spectroscopy suffered from weak Raman scattering and fluorescence interference.

  10. Les Cahiers du CREAD

    African Journals Online (AJOL)

    Admin

    6 juil. 2007 ... La problématique du développement du secteur de l'artisanat en. Algérie a été très peu abordée par les chercheurs, qu'ils soient universitaires ou .... La loi a institué une taxe d'apprentissage dont le taux a été fixé à. 1% de la ...

  11. Les outils du CERN

    CERN Multimedia

    1999-01-01

    C'est le plus grand centre mondial de recherche en physique des particules. Les outils du Laboratoire, accélérateurs et détecteurs de particules, figurent parmi les instruments scientifiques les plus complexes au monde. Des prix Nobels ont d'ailleurs été attribués aux physiciens du CERN pour leurs développements.

  12. Bulletin du CRDI #127

    International Development Research Centre (IDRC) Digital Library (Canada)

    La mise à l'échelle de la recherche et de l'innovation en vue de créer un impact social constitue une priorité pour la communauté du développement. Toutefois ... Nous avons renouvelé notre soutien à la recherche auprès du gouvernement de l'Inde ... Des femmes étudient à l'École supérieure d'infotronique d'Haïti.

  13. 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

  14. Operating Range for High Temperature Borosilicate Waste Glasses: (Simulated Hanford Enveloped)

    International Nuclear Information System (INIS)

    Mohammad, J.; Ramsey, W. G.; Toghiani, R. K.

    2003-01-01

    The following results are a part of an independent thesis study conducted at Diagnostic Instrumentation and Analysis Laboratory-Mississippi State University. A series of small-scale borosilicate glass melts from high-level waste simulant were produced with waste loadings ranging from 20% to 55% (by mass). Crushed glass was allowed to react in an aqueous environment under static conditions for 7 days. The data obtained from the chemical analysis of the leachate solutions were used to test the durability of the resulting glasses. Studies were performed to determine the qualitative effects of increasing the B2O3 content on the overall waste glass leaching behavior. Structural changes in a glass arising due to B2O3 were detected indirectly by its chemical durability, which is a strong function of composition and structure. Modeling was performed to predict glass durability quantitatively in an aqueous environment as a direct function of oxide composition

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

    Directory of Open Access Journals (Sweden)

    Inès M. M. M. Ponsot

    2014-07-01

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

  16. Effect of MoO3 addition on phase separation in borosilicate glasses

    International Nuclear Information System (INIS)

    Wakabayashi, Hajimu; Yamanaka, Hiroshi; Terai, Ryohei; Fukumoto, Shinji.

    1987-01-01

    The effect of MoO 3 addition on the phase separation of sodium borosilicate glasses has been studied by electron microscopic observation and electrical conductivity measurement. With increasing MoO 3 addition, the immiscibility temperatures rose, the growth rate of phase separation increased, and the immiscibility region in the Na 2 O-B 2 O 3 -SiO 2 system extended. When MoO 3 more than 5 mol% was added to the glasses, two stages of phase separation appeared ; one is metastable immiscibility, which takes place below the liquidus temperature, and the other is stable immiscibility, occurring above the liquidus temperature. The present experiment confirmed that the conductivity measurement of molten glasses is usefull to detect phase separation in the glasses, giving some suggestions for preventing the separation of molybdates in nuclear waste glasses and also for controlling the micro-pore sizes of porous glasses. (author)

  17. Heat accumulation during high repetition rate ultrafast laser interaction: Waveguide writing in borosilicate glass

    International Nuclear Information System (INIS)

    Zhang, Haibin; Eaton, Shane M; Li, Jianzhao; Herman, Peter R

    2007-01-01

    During high repetition rate (>200 kHz) ultrafast laser waveguide writing, visible heat modified zones surrounding the formed waveguide occur as a result of heat accumulation. The radii of the heat-modified zones increase with the laser net fluence, and were found to correlate with the formation of low-loss and cylindrically symmetric optical waveguides. A numerical thermal model based on the finite difference method is applied here to account for cumulative heating and diffusion effects. The model successfully shows that heat propagation and accumulation accurately predict the radius of the 'heat modified' zones observed in borosilicate glass waveguides formed across a wide range of laser exposure conditions. Such modelling promises better control of thermal effects for optimizing the fabrication and performance of three-dimensional optical devices in transparent materials

  18. Energy transfer and cross-relaxation in Tb3+-doped borosilicate glasses

    International Nuclear Information System (INIS)

    Kim, Jung Hwan; Sol, Jung Sik

    1990-01-01

    Energy transfer in Tb 3+ -doped borosilicate glasses has been studied by the analysis of fluorescence intensities and lifetimes of 5 D 3 and 5 D 4 states as a function of Tb 3+ concentration. It is shown that as the Tb 3+ concentration is increased the cross-relaxation produces high population of the 5 D 4 state at the expense of 5 D 3 . It is also found that this interaction is predominantly dipole-dipole transition with critical distance of 13 A. The critical distance for energy transfer 5 D 4 5 D 3 which is responsible for the quenching of 5 D 4 emission at high concentration of Tb 3+ ions is 4.5 A. (Author)

  19. Determination of iron redox ratio in borosilicate glasses and melts from Raman spectra

    Energy Technology Data Exchange (ETDEWEB)

    Cochain, B. [SCDV-Laboratoire d' Etudes de Base sur les Verres, CEA Valrho, Centre de Marcoule, 30207 Bagnols-sur-ceze (France); Physique des Mineraux et des Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris Cedex05 (France); Neuville, D.R.; Richet, P. [Physique des Mineraux et des Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris Cedex05 (France); Henderson, G.S. [Dept of Geology, University of Toronto, 22 Russell Street, Toronto (Canada); Pinet, O. [SCDV-Laboratoire d' Etudes de Base sur les Verres, CEA Valrho, Centre de Marcoule, 30207 Bagnols-sur-ceze (France)

    2008-07-01

    A method is presented to determine the redox ratio of iron in borosilicate glasses and melts relevant to nuclear waste storage from an analysis of Raman spectra recorded at room or high temperature. The basis of this method is the strong variation of the spectral feature observed between 800 and 1200 cm{sup -1}, in which it is possible to assign a band to vibrational modes involving ferric iron in tetrahedral coordination whose intensity increases with iron content and iron oxidation. After baseline correction and normalization, fits to the Raman spectra made with Gaussian bands enable us to determine the proportion of ferric iron provided the redox ratio is known independently for at least two redox states for a given glass composition. This method is particularly useful for in situ determinations of the kinetics and mechanisms of redox reactions. (authors)

  20. Electrical characterization of strontium titanate borosilicate glass ceramics system with bismuth oxide addition using impedance spectroscopy

    International Nuclear Information System (INIS)

    Thakur, O.P.; Kumar, Devendra; Parkash, Om; Pandey, Lakshman

    2003-01-01

    The ac electrical data, measured in the frequency range 0.1 kHz-1 MHz, were used to study the electrical response of strontium titanate borosilicate glass ceramic system with bismuth oxide addition. Complex plane plots from these electrical data for various glass ceramic samples reveal contributions from simultaneously operating polarization mechanisms to overall dielectric behavior. The complex modulus (M * ) representation of electrical data for various glass ceramic samples were found to be more informative. Equivalent circuit models, which represent the electrical behavior of glass ceramic samples, were determined using complex non-linear least square (CNLS) fitting. An attempt has been made to understand the dielectric behavior of various glass ceramics in terms of contributions arising from different polarization processes occurring at glassy matrix, crystalline phases, glass to crystal interface region and blocking electrodes. Glass ceramics containing SrTiO 3 and TiO 2 (rutile) phases show thermally stable dielectric behavior

  1. Determination of iron redox ratio in borosilicate glasses and melts from Raman spectra

    International Nuclear Information System (INIS)

    Cochain, B.; Neuville, D.R.; Richet, P.; Henderson, G.S.; Pinet, O.

    2008-01-01

    A method is presented to determine the redox ratio of iron in borosilicate glasses and melts relevant to nuclear waste storage from an analysis of Raman spectra recorded at room or high temperature. The basis of this method is the strong variation of the spectral feature observed between 800 and 1200 cm -1 , in which it is possible to assign a band to vibrational modes involving ferric iron in tetrahedral coordination whose intensity increases with iron content and iron oxidation. After baseline correction and normalization, fits to the Raman spectra made with Gaussian bands enable us to determine the proportion of ferric iron provided the redox ratio is known independently for at least two redox states for a given glass composition. This method is particularly useful for in situ determinations of the kinetics and mechanisms of redox reactions. (authors)

  2. Development of Composite Materials Under Ecological Aspects as Recycling Concept For Borosilicate Glass Containing Iron Slags

    International Nuclear Information System (INIS)

    Khalil, T.K.; Bossert, J.; Aly, H.F.; Bossert, J.

    1999-01-01

    Composite concept in materials science can be conveniently applied in the waste treatment technology to construct specific t ailor made c omposite materials, in which at least one of the phases is built by the waste material. In this work the applicability of this concept for the fixation and recycling of slags wastes is done, whereby different mixtures of blast furnace slags are mixed with two different borosilicate glasses, which serve as matrix material. Thermal behaviour of the produced compacts were studied. Both melting and powder technology are applied for the fabrication of dense products. The microstructure of sintered samples is investigated by electron microscopy. The mechanical properties such as hardness and fracture toughness are determined by a Vickers technique. An improvement of the fracture toughness of more than 50% over the value for the original glass VG 98 is achieved by slag addition

  3. Influence of Some Nuclear Waste on The Durability and Mechanical Properties of Borosilicate glass

    International Nuclear Information System (INIS)

    El-Alaily, N.A.

    2003-01-01

    Various glass systems have been shown to be suitable for producing waste glass forms that are thermally and mechanically stable and exhibit good chemical durability. In this study borosilicate glass containing sodium oxide and aluminum oxide was prepared as a host for high level nuclear waste. The glass durability when the samples were immersed either in distilled water or ground water at 70 degree was studied. The density, porosity and mechanical properties were also investigated. The effects of exposing the samples immersed in groundwater to gamma rays in the glass durability and all other mentioned properties were also studied. The results showed that immersing the glass in ground water causing a decrease in the glass durability. The exposure of the glass immersed in ground water to the gamma rays increases the durability of the glass. The mechanical properties of the prepared glass were good. Although these properties decrease for the corroded glass but they were still good

  4. Corrosion of inconel in high-temperature borosilicate glass melts containing simulant nuclear waste

    Science.gov (United States)

    Mao, Xianhe; Yuan, Xiaoning; Brigden, Clive T.; Tao, Jun; Hyatt, Neil C.; Miekina, Michal

    2017-10-01

    The corrosion behaviors of Inconel 601 in the borosilicate glass (MW glass) containing 25 wt.% of simulant Magnox waste, and in ZnO, Mn2O3 and Fe2O3 modified Mg/Ca borosilicate glasses (MZMF and CZMF glasses) containing 15 wt.% of simulant POCO waste, were evaluated by dimensional changes, the formation of internal defects and changes in alloy composition near corrosion surfaces. In all three kinds of glass melts, Cr at the inconel surface forms a protective Cr2O3 scale between the metal surface and the glass, and alumina precipitates penetrate from the metal surface or formed in-situ. The corrosion depths of inconel 601 in MW waste glass melt are greater than those in the other two glass melts. In MW glass, the Cr2O3 layer between inconel and glass is fragmented because of the reaction between MgO and Cr2O3, which forms the crystal phase MgCr2O4. In MZMF and CZMF waste glasses the layers are continuous and a thin (Zn, Fe, Ni, B)-containing layer forms on the surface of the chromium oxide layer and prevents Cr2O3 from reacting with MgO or other constituents. MgCr2O4 was observed in the XRD analysis of the bulk MW waste glass after the corrosion test, and ZrSiO4 in the MZMF waste glass, and ZrSiO4 and CaMoO4 in the CZMF waste glass.

  5. Comparison of radiation and quenching rate effects on the structure of a sodium borosilicate glass

    International Nuclear Information System (INIS)

    Peuget, Sylvain; Maugeri, Emilio-Andrea; Mendoza, Clement; Fares, Toby; Bouty, Olivier; Jegou, Christophe; Charpentier, Thibault; Moskura, Melanie

    2013-01-01

    The effects of quenching rate and irradiation on the structure of a sodium borosilicate glass were compared using 29 Si, 11 B, and 23 Na nuclear magnetic resonance and Raman spectroscopy. Quenching rate ranging from 0.1 to 3 * 10 4 K min -1 was studied. Various irradiation conditions were performed, i.e. gold-ion irradiation in a multi-energy mode (from 1 to 6.75 MeV), and Kr and Xe ion irradiations with energy of 74 and 92 MeV, respectively. In pile irradiation with thermal neutron flux was performed as well, to study the effect of alpha radiation from the nuclear reaction 10 B(n,α) 7 Li. Both irradiation and high quenching rate induce similar local order modification of the glass structure, mainly a decrease of the mean boron coordination and an increase of Q 3 units. Nevertheless, the variations observed under irradiation are more pronounced than the ones induced by the quenching rate. Moreover, some important modifications of the glass medium range order, i.e. the emergence of the D2 band associated to three members silica rings and a modification of the Si-O-Si angle distribution were only noticed after irradiation. These results suggest that the irradiated structure is certainly not exactly the one obtained by a rapidly quenched equilibrated melt, but rather a more disordered structure that was weakly relaxed during the very rapid quenching phase following the energy deposition step. Raman spectroscopy showed a similar irradiated structure whereas the glass evolutions were controlled by the electronic energy loss in the ion track formation regime for Kr-ion irradiation or by the nuclear energy loss for Au and OSIRIS irradiation. The similar irradiated structure despite different irradiation routes, suggests that the final structural state of this sodium borosilicate glass is mainly controlled by the glass reconstruction after the energy deposition step. (authors)

  6. Wetspun poly-L-(lactic acid)-borosilicate bioactive glass scaffolds for guided bone regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, João S., E-mail: joao.fernandes@dep.uminho.pt [3B' s Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark-Parque de Ciência e Tecnologia, Zona Industrial da Gandra, 4805-017 Barco GMR (Portugal); ICVS/3B' s - PT Government Associate Laboratory, Braga/Guimarães (Portugal); Reis, Rui L. [3B' s Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark-Parque de Ciência e Tecnologia, Zona Industrial da Gandra, 4805-017 Barco GMR (Portugal); ICVS/3B' s - PT Government Associate Laboratory, Braga/Guimarães (Portugal); Pires, Ricardo A., E-mail: rpires@dep.uminho.pt [3B' s Research Group - Biomaterials, Biodegradables and Biomimetics, University of Minho, Headquarters of the European Institute of Excellence on Tissue Engineering and Regenerative Medicine, AvePark-Parque de Ciência e Tecnologia, Zona Industrial da Gandra, 4805-017 Barco GMR (Portugal); ICVS/3B' s - PT Government Associate Laboratory, Braga/Guimarães (Portugal)

    2017-02-01

    We developed a porous poly-L-lactic acid (PLLA) scaffold compounded with borosilicate bioactive glasses (BBGs) endowing it with bioactive properties. Porous PLLA-BBG fibre mesh scaffolds were successfully prepared by the combination of wet spinning and fibre bonding techniques. Micro-computed tomography (μCT) confirmed that the PLLA-BBG scaffolds containing ≈ 25% of BBGs (w/w) exhibited randomly interconnected porous (58 to 62% of interconnectivity and 53 to 67% of porosity) with mean pore diameters higher that 100 μm. Bioactivity and degradation studies were performed by immersing the scaffolds in simulated body fluid (SBF) and ultrapure water, respectively. The PLLA-BBG scaffolds presented a faster degradation rate with a constant release of inorganic species, which are capable to produce calcium phosphate structures at the surface of the material after 7 days of immersion in SBF (Ca/P ratio of ~ 1.7). Cellular in vitro studies with human osteosarcoma cell line (Saos-2) and human adipose-derived stem cells (hASCs) showed that PLLA-BBGs are not cytotoxic to cells, while demonstrating their capacity to promote cell adhesion and proliferation. Overall, we showed that the proposed scaffolds present a tailored kinetics on the release of inorganic species and controlled biological response under conditions that mimic the bone physiological environment. - Highlights: • We prepared borosilicate glasses and their PLLA composites in the form of fibres. • These glasses imparted bioactivity and controlled degradability to the fibres. • The prepared fibres did not elicit cytotoxicity. • hASCs attached and proliferated in the surface and inner sections of the scaffolds. • The composites present appropriate properties to be used in bone tissue engineering.

  7. Aqueous corrosion of borosilicate glasses: experiments, modeling and Monte-Carlo simulations

    International Nuclear Information System (INIS)

    Ledieu, A.

    2004-10-01

    This work is concerned with the corrosion of borosilicate glasses with variable oxide contents. The originality of this study is the complementary use of experiments and numerical simulations. This study is expected to contribute to a better understanding of the corrosion of nuclear waste confinement glasses. First, the corrosion of glasses containing only silicon, boron and sodium oxides has been studied. The kinetics of leaching show that the rate of leaching and the final degree of corrosion sharply depend on the boron content through a percolation mechanism. For some glass contents and some conditions of leaching, the layer which appears at the glass surface stops the release of soluble species (boron and sodium). This altered layer (also called the gel layer) has been characterized with nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. Second, additional elements have been included in the glass composition. It appears that calcium, zirconium or aluminum oxides strongly modify the final degree of corrosion so that the percolation properties of the boron sub-network is no more a sufficient explanation to account for the behavior of these glasses. Meanwhile, we have developed a theoretical model, based on the dissolution and the reprecipitation of the silicon. Kinetic Monte Carlo simulations have been used in order to test several concepts such as the boron percolation, the local reactivity of weakly soluble elements and the restructuring of the gel layer. This model has been fully validated by comparison with the results on the three oxide glasses. Then, it has been used as a comprehensive tool to investigate the paradoxical behavior of the aluminum and zirconium glasses: although these elements slow down the corrosion kinetics, they lead to a deeper final degree of corrosion. The main contribution of this work is that the final degree of corrosion of borosilicate glasses results from the competition of two opposite mechanisms

  8. The Dissolution Behavior of Borosilicate Glasses in Far-From Equilibrium Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Neeway, James J.; Rieke, Peter C.; Parruzot, Benjamin PG; Ryan, Joseph V.; Asmussen, Robert M.

    2018-02-10

    In far-from-equilibrium conditions, the dissolution of borosilicate glasses used to immobilize nuclear waste is known to be a function of both temperature and pH. The aim of this paper is to study effects of these variables on three model waste glasses (SON68, ISG, AFCI). To do this, experiments were conducted at temperatures of 23, 40, 70, and 90 °C and pH(RT) values of 9, 10, 11, and 12 with the single-pass flow-through (SPFT) test method. The results from these tests were then used to parameterize a kinetic rate model based on transition state theory. Both the absolute dissolution rates and the rate model parameters are compared with previous results. Discrepancies in the absolute dissolution rates as compared to those obtained using other test methods are discussed. Rate model parameters for the three glasses studied here are nearly equivalent within error and in relative agreement with previous studies. The results were analyzed with a linear multivariate regression (LMR) and a nonlinear multivariate regression performed with the use of the Glass Corrosion Modeling Tool (GCMT), which is capable of providing a robust uncertainty analysis. This robust analysis highlights the high degree of correlation of various parameters in the kinetic rate model. As more data are obtained on borosilicate glasses with varying compositions, the effect of glass composition on the rate parameter values could possibly be obtained. This would allow for the possibility of predicting the forward dissolution rate of glass based solely on composition

  9. Water leaching of borosilicate glasses: experiments, modeling and Monte Carlo simulations

    International Nuclear Information System (INIS)

    Ledieu, A.

    2004-10-01

    This work is concerned with the corrosion of borosilicate glasses with variable oxide contents. The originality of this study is the complementary use of experiments and numerical simulations. This study is expected to contribute to a better understanding of the corrosion of nuclear waste confinement glasses. First, the corrosion of glasses containing only silicon, boron and sodium oxides has been studied. The kinetics of leaching show that the rate of leaching and the final degree of corrosion sharply depend on the boron content through a percolation mechanism. For some glass contents and some conditions of leaching, the layer which appears at the glass surface stops the release of soluble species (boron and sodium). This altered layer (also called the gel layer) has been characterized with nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. Second, additional elements have been included in the glass composition. It appears that calcium, zirconium or aluminum oxides strongly modify the final degree of corrosion so that the percolation properties of the boron sub-network is no more a sufficient explanation to account for the behavior of these glasses. Meanwhile, we have developed a theoretical model, based on the dissolution and the reprecipitation of the silicon. Kinetic Monte Carlo simulations have been used in order to test several concepts such as the boron percolation, the local reactivity of weakly soluble elements and the restructuring of the gel layer. This model has been fully validated by comparison with the results on the three oxide glasses. Then, it has been used as a comprehensive tool to investigate the paradoxical behavior of the aluminum and zirconium glasses: although these elements slow down the corrosion kinetics, they lead to a deeper final degree of corrosion. The main contribution of this work is that the final degree of corrosion of borosilicate glasses results from the competition of two opposite mechanisms

  10. Fabrication of Silicon Nitride Dental Core Ceramics with Borosilicate Veneering material

    Energy Technology Data Exchange (ETDEWEB)

    Wananuruksawong, R; Jinawath, S; Wasanapiarnpong, T [Research Unit of Advanced Ceramic, Department of Materials Science, Faculty of Science, Chulalongkorn University, Bangkok (Thailand); Padipatvuthikul, P, E-mail: raayaa_chula@hotmail.com [Faculty of Dentistry, Srinakharinwirot University, Bangkok (Thailand)

    2011-10-29

    Silicon nitride (Si{sub 3}N{sub 4}) ceramic is a great candidate for clinical applications due to its high fracture toughness, strength, hardness and bio-inertness. This study has focused on the Si{sub 3}N{sub 4} ceramic as a dental core material. The white Si{sub 3}N{sub 4} was prepared by pressureless sintering at relative low sintering temperature of 1650 deg. C in nitrogen atmosphere. The coefficient of thermal expansion (CTE) of Si{sub 3}N{sub 4} ceramic is lower than that of Zirconia and Alumina ceramic which are popular in this field. The borosilicate glass veneering was employed due to its compatibility in thermal expansion. The sintered Si{sub 3}N{sub 4} specimens represented the synthetic dental core were paintbrush coated by a veneer paste composed of borosilicate glass powder (<150 micrometer, Pyrex) with 5 wt% of zirconia powder (3 wt% Y{sub 2}O{sub 3} - partial stabilized zirconia) and 30 wt% of polyvinyl alcohol (5 wt% solution). After coating the veneer on the Si{sub 3}N{sub 4} specimens, the firing was performed in electric tube furnace between 1000-1200 deg. C. The veneered specimens fired at 1100 deg. C for 15 mins show good bonding, smooth and glossy without defect and crazing. The veneer has thermal expansion coefficient as 3.98x10{sup -6} deg. C{sup -1}, rather white and semi opaque, due to zirconia addition, the Vickers hardness as 4.0 GPa which is closely to the human teeth.

  11. Wetspun poly-L-(lactic acid)-borosilicate bioactive glass scaffolds for guided bone regeneration

    International Nuclear Information System (INIS)

    Fernandes, João S.; Reis, Rui L.; Pires, Ricardo A.

    2017-01-01

    We developed a porous poly-L-lactic acid (PLLA) scaffold compounded with borosilicate bioactive glasses (BBGs) endowing it with bioactive properties. Porous PLLA-BBG fibre mesh scaffolds were successfully prepared by the combination of wet spinning and fibre bonding techniques. Micro-computed tomography (μCT) confirmed that the PLLA-BBG scaffolds containing ≈ 25% of BBGs (w/w) exhibited randomly interconnected porous (58 to 62% of interconnectivity and 53 to 67% of porosity) with mean pore diameters higher that 100 μm. Bioactivity and degradation studies were performed by immersing the scaffolds in simulated body fluid (SBF) and ultrapure water, respectively. The PLLA-BBG scaffolds presented a faster degradation rate with a constant release of inorganic species, which are capable to produce calcium phosphate structures at the surface of the material after 7 days of immersion in SBF (Ca/P ratio of ~ 1.7). Cellular in vitro studies with human osteosarcoma cell line (Saos-2) and human adipose-derived stem cells (hASCs) showed that PLLA-BBGs are not cytotoxic to cells, while demonstrating their capacity to promote cell adhesion and proliferation. Overall, we showed that the proposed scaffolds present a tailored kinetics on the release of inorganic species and controlled biological response under conditions that mimic the bone physiological environment. - Highlights: • We prepared borosilicate glasses and their PLLA composites in the form of fibres. • These glasses imparted bioactivity and controlled degradability to the fibres. • The prepared fibres did not elicit cytotoxicity. • hASCs attached and proliferated in the surface and inner sections of the scaffolds. • The composites present appropriate properties to be used in bone tissue engineering.

  12. Intrinsic dosimetry. Properties and mechanisms of thermoluminescence in commercial borosilicate glass

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Richard A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2012-10-01

    Intrinsic dosimetry is the method of measuring total absorbed dose received by the walls of a container holding radioactive material. By considering the total absorbed dose received by a container in tandem with the physical characteristics of the radioactive material housed within that container, this method has the potential to provide enhanced pathway information regarding the history of the container and its radioactive contents. The latest in a series of experiments designed to validate and demonstrate this newly developed tool are reported. Thermoluminescence (TL) dosimetry was used to measure dose effects on raw stock borosilicate container glass up to 70 days after gamma ray, x-ray, beta particle or ultraviolet irradiations at doses from 0.15 to 20 Gy. The TL glow curve when irradiated with 60Co was separated into five peaks: two relatively unstable peaks centered near 120 and 165°C, and three relatively stable peaks centered near 225, 285, and 360°C. Depending on the borosilicate glass source, the minimum measurable dose using this technique is 0.15-0.5 Gy, which is roughly equivalent to a 24 hr irradiation at 1 cm from a 50-165 ng source of 60Co. Differences in TL glow curve shape and intensity were observed for the glasses from different geographical origins. These differences can be explained by changes in the intensities of the five peaks. Electron paramagnetic resonance (EPR) and multivariate statistical methods were used to relate the TL intensity and peaks to electron/hole traps and compositional variations.

  13. Effet du Pediococcus acidilactici sur le bilan lipidique sanguin du ...

    African Journals Online (AJOL)

    Les résultats relatifs aux performances zootechniques ont montré que l'addition du probiotique a amélioré significativement le gain de poids pendant la phase de croissance se traduisant par un indice de consommation meilleur. Les dosages du cholestérol total, des triglycérides, du HDL et du LDL ont été déterminés à la ...

  14. Effect of the Callovian-Oxfordian clayey fraction on borosilicate glass alteration

    International Nuclear Information System (INIS)

    Debure, M.; Frugier, P.; GIN, S.; De Windt, L.; Michau, N.

    2012-01-01

    Document available in extended abstract form only. In France, high-level nuclear waste (HLW) is confined in a glass matrix packaged into stainless steel canister and carbon steel overpack. The HLW should be buried in a geological clay formation like, potentially, the Callovian-Oxfordian (COx) clay-stone located in the north-eastern Parisian basin. The COx clay-stone contains minerals that can feed the near-field with soluble Mg. Such minerals are carbonates (ankerite, dolomite) as well as clay minerals (chlorite, illite, interstratified illite/smectite). Previous laboratory experiments have proved that aqueous solutions of Mg salts could significantly increase the alteration rate of nuclear glass (Jollivet et al., 2012). This motivated to go a step further by studying the alteration of nuclear glass put in contact with Mg minerals. A first set of experiments have revealed that the rate of glass dissolution was increased with hydro-magnesite (4MgCO 3 .Mg(OH) 2 .4H 2 O, a chemically simple model mineral) and dolomite. In both cases, Mg coming from carbonate dissolution reacts with Si, provided by the glass, in order to form Mg silicates (Debure et al., 2012). In that case, Si consumption sustains glass alteration. Mg silicate precipitation also consumes protons; therefore the interdiffusion of alkali within the glass alteration layer eventually becomes a driving force that sustains Mg silicate precipitation. The second set of experiments, presented here, aimed at better characterizing the role of the COx clayey fraction. The separation of the clayey phases of the COx clay-stone has been made in collaboration with the LEM lab (Nancy, France) by a sequence of sieving, acidic dissolution of carbonates, NaCl washing and sedimentation (Rivard, 2011). According to XRD and infrared analyses, the clayey fraction was mainly composed of kaolinite, illite, interstratified illite/smectite and chlorite (plus a little residual amount of quartz). This first step aimed to remove

  15. Les mots du jazz

    OpenAIRE

    Roueff, Olivier

    2007-01-01

    L’ouvrage d’André Schaeffner constitue la première analyse savante du jazz (1926). Il a marqué une étape importante dans le processus de réinvention du jazz en France en contribuant notamment, par sa réception et les polémiques qu’il a suscitées, à transformer l’identification du jazz d’une musique « américaine » à une musique « noire-américaine » (c’est-à-dire aux « racines » africaines). Les analyses proposées dans cet ouvrage, alors qu’elles désignaient des musiques que la critique de jazz...

  16. fibrosarcome du larynx

    African Journals Online (AJOL)

    pie du lit tumoral est employée comme complément thé- rapeutique [9] alors que la chimiothérapie est générale- ment indiquée dans les formes métastatiques. Le pronos- tic dépend essentiellement du degré de différentiation his- tologique. En fait, le fibrosarcome bien différencié est caractérisé par la fréquence de récidive ...

  17. du Chott Marouane

    African Journals Online (AJOL)

    plancton de 90 µm de vide de maille. Ils ont été conservés dans du formol à 5%. L'identification de l'espèce est basée sur des critères morphologiques [20]: la forme des furcas, les lobes frontaux des antennes des mâles, de l'organe copulateur (pénis) et du sac ovigère. Le comptage des soies furcales a été réalisé. L'étude ...

  18. W.E.B. Du Bois and Caste Education: Racial Capitalist Schooling from Reconstruction to Jim Crow

    Science.gov (United States)

    Pierce, Clayton

    2017-01-01

    This essay provides the first account and examination of caste education in the work of W.E.B. Du Bois. In so doing, I argue that caste education plays a central role in realizing the political and social goals of racial capitalist society for Du Bois. Using Du Bois's caste analytic, I take up and articulate three biopolitical governing strategies…

  19. Preparation and characterization of an improved borosilicate glass for the solidification of high level radioactive fission product solutions (HLW). Pt. 2

    International Nuclear Information System (INIS)

    Kahl, L.; Ruiz-Lopez, M.C.; Saidl, J.; Dippel, T.

    1982-04-01

    In the 'Institut fuer Nuklare Entsorgungstechnik' the borosilicate glass VG 98/12 has been developed for the solidification of the high level radioactive waste (HLW). This borosilicate glass can be used in a direct heated ceramic melter and forms together with the HLW the borosilicate glass product GP 98/12. This borosilicate glass product has been examined in detail both in liquid and solid state. The elements contained in the HLW can be incorporated without problems. Only in a few exceptions the concentration must be kept below certain limits to exclude the formation of a second phase ('yellow phase') by separation. No spontaneous crystallization and no crystallization over a long time could be observed as long as the temperature of the borosilicate glass product is kept below its transformation area. Simulating accidental conditions in the final storage, samples had been leached at temperatures up to 200 0 C and pressures up to 130 bar with saturated rock salt brine and saturated quinary salt brine. The leaching process seems to be stopped by the formed 'leached layer' on the surface of the borosilicate glass product after a limited leaching time. Detailed investigations have been started to explain this phenomenon. (orig.) [de

  20. Studies on the accelerated chemical durability test and its impact on structural changes in borosilicate glass matrix

    International Nuclear Information System (INIS)

    Thorat, Vidya S.; Kadam, P.S.; Mishra, R.K.; Kumar, Amar; Kaushik, C.P.; Sudarsan, V.; Tyagi, A.K.

    2015-01-01

    Sodium borosilicate glass used for the immobilisation of high level nuclear waste with tentative compositions (SiO 2 ) 0.477 (B 2 O 3 ) 0.239 (Na 2 O) 0.170 (TiO 2 ) 0.02 )3 (CaO) 0.068 (Al 2 O 3 ) 0.023 was evaluated for its long term stability in the repository conditions where it may be exposed to high temperature and pressure. 29 Si MAS NMR studies have confirmed that, upon leaching, sodium borosilicate glass undergoes congruent crystallization leading to the formation of an aluminosilicate phase, Na 6 Al 6 Si 10 O 32 . Further the residual glass structure in the composite sample is identical with that of the un-leached glass. Boron structural units are unaffected in the glass compositions upon leaching

  1. High-level waste glass compendium; what it tells us concerning the durability of borosilicate waste glass

    International Nuclear Information System (INIS)

    Cunnane, J.C.; Allison, J.

    1993-01-01

    Facilities for vitrification of high-level nuclear waste in the United States are scheduled for startup in the next few years. It is, therefore, appropriate to examine the current scientific basis for understanding the corrosion of high-level waste borosilicate glass for the range of service conditions to which the glass products from these facilities may be exposed. To this end, a document has been prepared which compiles worldwide information on borosilicate waste glass corrosion. Based on the content of this document, the acceptability of canistered waste glass for geological disposal is addressed. Waste glass corrosion in a geologic repository may be due to groundwater and/or water vapor contact. The important processes that determine the glass corrosion kinetics under these conditions are discussed based on experimental evidence from laboratory testing. Testing data together with understanding of the long-term corrosion kinetics are used to estimate radionuclide release rates. These rates are discussed in terms of regulatory performance standards

  2. les cahiers du cread

    African Journals Online (AJOL)

    Our Journal “les cahiers du cread” is a quarterly economic review publishing original findings of empirical research and theoretical debates on fields pertaining to our mission coverage (Macro Economics, Industrial Economics and Firms, Human Development & Social Economics, Agriculture & Environment). Other websites ...

  3. 4.2. The kinetics of nitric acid decomposition of calcined borosilicate raw material of Ak-Arkhar Deposit

    International Nuclear Information System (INIS)

    Mirsaidov, U.M.; Kurbonov, A.S.; Mamatov, E.D.

    2015-01-01

    Present article is devoted to kinetics of nitric acid decomposition of calcined borosilicate raw material of Ak-Arkhar Deposit. The dependence of nitric acid decomposition of calcined boric raw material for extraction of boron oxide on temperature (20-100 deg C) and process duration (15-60 minutes) was defined. It was defined that at temperature increasing the extraction rate of boron oxide increases from 20.8 to 78.6%.

  4. Entrapment of 137Cs vapour generated during vitrification and casting of cesium borosilicate glass by inorganic materials

    International Nuclear Information System (INIS)

    Ram, Ramu; Gandhi, Shyamala; Dash, A.; Varma, R.N.

    2003-01-01

    Efficiency of different inorganic materials like zirconium antimonate (ZrA), ammonium molybdophosphate (AMP), synthetic zeolites, activated charcoal, glass wool etc, towards the entrapment of 137 Cs vapour escaping during vitrification and casting of cesium borosilicate glass required for the preparation of 137 Cs sources for medical and industrial applications have been determined. The recovery of entrapped cesium using dilute acids for subsequent recycling has also been explored. (author)

  5. Barium borosilicate glass - a potential matrix for immobilization of sulfate bearing high-level radioactive liquid waste

    International Nuclear Information System (INIS)

    Kaushik, C.P.; Mishra, R.K.; Sengupta, P.; Kumar, Amar; Das, D.; Kale, G.B.; Raj, Kanwar

    2006-01-01

    Borosilicate glass formulations adopted worldwide for immobilization of high-level radioactive liquid waste (HLW) is not suitable for sulphate bearing HLW, because of its low solubility in such glass. A suitable glass matrix based on barium borosilicate has been developed for immobilization of sulphate bearing HLW. Various compositions based on different glass formulations were made to examine compatibility with waste oxide with around 10 wt% sulfate content. The vitrified waste product obtained from barium borosilicate glass matrix was extensively evaluated for its characteristic properties like homogeneity, chemical durability, glass transition temperature, thermal conductivity, impact strength, etc. using appropriate techniques. Process parameters like melt viscosity and pour temperature were also determined. It is found that SB-44 glass composition (SiO 2 : 30.5 wt%, B 2 O 3 : 20.0 wt%, Na 2 O: 9.5 wt% and BaO: 19.0 wt%) can be safely loaded with 21 wt% waste oxide without any phase separation. The other product qualities of SB-44 waste glass are also found to be on a par with internationally adopted waste glass matrices. This formulation has been successfully implemented in plant scale

  6. The dissolution behavior of borosilicate glasses in far-from equilibrium conditions

    Science.gov (United States)

    Neeway, James J.; Rieke, Peter C.; Parruzot, Benjamin P.; Ryan, Joseph V.; Asmussen, R. Matthew

    2018-04-01

    An area of agreement in the waste glass corrosion community is that, at far-from-equilibrium conditions, the dissolution of borosilicate glasses used to immobilize nuclear waste is known to be a function of both temperature and pH. The aim of this work is to study the effects of temperature and pH on the dissolution rate of three model nuclear waste glasses (SON68, ISG, AFCI). The dissolution rate data are then used to parameterize a kinetic rate model based on Transition State Theory that has been developed to model glass corrosion behavior in dilute conditions. To do this, experiments were conducted at temperatures of 23, 40, 70, and 90 °C and pH (22 °C) values of 9, 10, 11, and 12 with the single-pass flow-through (SPFT) test method. Both the absolute dissolution rates and the rate model parameters are compared with previous results. Rate model parameters for the three glasses studied here are nearly equivalent within error and in relative agreement with previous studies though quantifiable differences exist. The glass dissolution rates were analyzed with a linear multivariate regression (LMR) and a nonlinear multivariate regression performed with the use of the Glass Corrosion Modeling Tool (GCMT), with which a robust uncertainty analysis is performed. This robust analysis highlights the high degree of correlation of various parameters in the kinetic rate model. As more data are obtained on borosilicate glasses with varying compositions, a mathematical description of the effect of glass composition on the rate parameter values should be possible. This would allow for the possibility of calculating the forward dissolution rate of glass based solely on composition. In addition, the method of determination of parameter uncertainty and correlation provides a framework for other rate models that describe the dissolution rates of other amorphous and crystalline materials in a wide range of chemical conditions. The higher level of uncertainty analysis would provide

  7. Structure and chemical durability of barium borosilicate glass–ceramics containing zirconolite and titanite crystalline phases

    International Nuclear Information System (INIS)

    Li, Huidong; Wu, Lang; Xu, Dong; Wang, Xin; Teng, Yuancheng; Li, Yuxiang

    2015-01-01

    In order to increase the solubility of actinides in the glass matrix, the effects of CaO, TiO 2 , and ZrSiO 4 addition (abbreviated as CTZ, in the mole ratio of 2:2:1) on crystalline phases, microstructure, and chemical durability of barium borosilicate glass–ceramics were investigated. The results show that the samples possess both zirconolite-2M and titanite phase when the CTZ content is greater than or equal to 45 wt.%. For the glass–ceramics with 45 wt.% CTZ (CTZ-45), only zirconolite-2M phase is observed after annealing at 680–740 °C for 2 h. The CTZ-45 possess zirconolite-2M and titanite phases after annealing at 700 °C first, and then annealing at 900–1050 °C for 2 h. Furthermore, the zirconolite-2M and titanite grains show a strip and brick shape, respectively. The CTZ-45 annealing at 950 °C shows the lower normalized leaching rates of B, Na and Nd when compared to that of CTZ-0 and CTZ-55. - Highlights: • CaO, TiO 2 , ZrSiO 4 (CTZ) as nucleating agents were added to barium borosilicate glass. • The samples with 45–55 wt% CTZ possess CaZrTi 2 O 7 -2M and CaTiSiO 5 crystalline phases. • CTZ-45 (45wt% CTZ) possesses only CaZrTi 2 O 7 -2M phase after annealing at 680–740 °C. • CTZ-45 possesses CaZrTi 2 O 7 -2M and CaTiSiO 5 phases after annealing at 900–1050 °C. • CTZ-45 annealing at 950 °C shows the lower leaching rates of B, Na and Nd than CTZ-0 and CTZ-55.

  8. Study of phase separation and crystallization phenomena in soda-lime borosilicate glass enriched in MoO3

    International Nuclear Information System (INIS)

    Magnin, M.

    2009-09-01

    Molybdenum oxide immobilization (MoO 3 , as fission product) is one of the major challenges in the nuclear glass formulation issues for high level waste solutions conditioning since many years, these solutions arising from spent nuclear fuel reprocessing. Phase separation and crystallisation processes may arise in molten glass when the MoO 3 content is higher than its solubility limit that may depend on glass composition. Molybdenum combined with other elements such as alkali and alkaline-earth may form crystalline molybdates, known as 'yellow phases' in nuclear glasses which may decrease the glass durability. In order to confine high level wastes (HLW) such as the fission product solutions arising from the reprocessing of high burn-up UOX-type nuclear spent fuels, a new glass composition (HLW glass) is being optimized. This work is devoted to the study of the origin and the mechanism of phase separation and crystallization phenomena induced by molybdenum oxide incorporation in the HLW glass. From microstructural and structural point of view, the molybdenum oxide behavior was studied in glass compositions belonging to the SiO 2 -B 2 O 3 - Na 2 O-CaO simplified system which constituted basis for the HLW glass formulation. The structural role of molybdenum oxide in borosilicate network explaining the phase separation and crystallization tendency was studied through the coupling of structural ( 95 Mo, 29 Si, 11 B, 23 Na MAS NMR, XRD) and microstructural (SEM, HRTEM) analysis techniques. The determination of phase separation (critical temperature) and crystallization (liquidus temperature) appearance temperatures by in situ viscosimetry and Raman spectroscopy experiments allowed us to propose a transformation scenario during melt cooling. These processes and the nature of the crystalline phases formed (CaMoO 4 , Na 2 MoO 4 ) that depend on the evolution of MoO 3 , CaO and B 2 O 3 contents were correlated with changes of sodium and calcium cations proportions in the

  9. Comparaison du filtre adaptatif RIF et du filtre a base de reseau de ...

    African Journals Online (AJOL)

    Comparaison du filtre adaptatif RIF et du filtre a base de reseau de neurones pour le filtrage du courant de reference pour la commande du filtre actif parallele. C Benachaiba, A Bassou, B Mazari ...

  10. There Is Still Room for Improvement: Presentation of a Neutral Borosilicate Glass with Improved Chemical Stability for Parenteral Packaging.

    Science.gov (United States)

    Boltres, Bettine; Tratzky, Stephan; Kass, Christof; Eichholz, Rainer; Naß, Peter

    2016-01-01

    For pharmaceutical parenteral packaging the glass compositions have always been either Type I borosilicate or Type III soda-lime glass. As both the compositions and certain chemical and physical properties are mandated by international standards, there has not been room for any changes. However, by applying only minor adjustments, a borosilicate glass was developed that showed improved chemical stability. The chemical composition is still in the range of currently used borosilicate glasses, which makes it a Type I glass according to all current pharmacopeia. A study was performed on glass vials comparing the new glass with the standard FIOLAX(®) and two other publicly available glasses. In an extraction study with water at 121 °C the new glass showed the highest chemical stability with the lowest amount of extractables. In an accelerated ageing study, which was done with water, phosphate, and carbonate buffer at 40 °C for 12 months, the new glass also proved to have the lowest amount of leachables. In this article the new glass and the results from the studies are presented, showing the reader how much of an effect can be attained with only minor adjustments if the scientific fundamentals are clear. The pharmaceutical market has been quite constant and risk-oriented due to the high impact on the safety of the patient. As any change necessitates a complicated change process, this has, in consequence, lead the industry to resist changing the parenteral primary packaging material for decades. The main glasses have either been Type I borosilicate or Type III soda-lime glass. On the other hand, a combination of improved inspection systems and the development of more sensitive biologically based drugs has elevated the standards for parental packaging materials. For example, the measurement of extractables and leachables from the packaging material steadily came into focus. In this article, a new glass is presented that still belongs to the group of Type I borosilicate

  11. Effects of solution chemistry and atmosphere on leaching of alkali borosilicate glass

    International Nuclear Information System (INIS)

    Hermansson, H.P.; Christensen, H.; Clark, D.E.; Werme, L.

    1983-01-01

    The leaching behavior of two alkali-borosilicate glasses containing 9 wt % simulated fission products and 1.6 wt % uranium oxide has been studied. Samples were exposed to one of eight types of leachants including doubly distilled water, simulated ground silicate water, a brine solution, and solutions containing various concentrations of iron, aluminum or sodium maintained at either 25 0 C, 40 0 C or 90 0 C for up to 182 days. The most aggressive leachants were the solutions containing sodium (excluding brine) and simulated ground silicate water. These solutions increased the extent of leaching by a factor of 2 to 3 over that for distilled water for one of the glasses. A partially protective surface film rich in magnesium, potassium, and chlorine was formed on the glasses exposed to the brine solution. In order to evaluate the effects of atmosphere on leaching, samples were also immersed in doubly distilled water over which the relative concentrations of oxygen, nitrogen and carbon dioxide were varied. Increasing the carbon dioxide concentration from 0 to 50% resulted in a factor of 3 increase in the leaching rate

  12. Leach behavior of high-level borosilicate glasses under deep geological environment

    International Nuclear Information System (INIS)

    Kim, Seung Soo; Chun, Kwan Sik; Park, Hyun Soo

    1998-02-01

    This report presents an overview of the activities in high-level radioactive waste glass which is considered as the most practicable form of waste, and also is intended to be used in the disposal of national high-level radioactive waste in future. Leach theory of waste glass and the leach effects of ground water, metal barrier, buffer materials and rocks on the waste glass were reviewed. The leach of waste glass was affected by various factors such as composition, pH and Eh of ground water, temperature, pressure, radiation and humic acid. The crystallization, crack, weathering and the formation of altered phases of waste glass which is expected to occur in real disposal site were reviewed. The results of leaching in laboratory and in-situ were compared. The behaviors of radioactive elements leached from waste glass and the use of basalt glass for the long-term natural analogue of waste glass were also written in this report. The appraisal of durability of borosilicate waste glass as a waste media was performed from the known results of leach test and international in-situ tests were introduced. (author). 134 refs., 15 tabs., 24 figs

  13. Physical and optical properties of lithium borosilicate glasses doped with Dy3+ ions

    Science.gov (United States)

    Ramteke, D. D.; Gedam, R. S.; Swart, H. C.

    2018-04-01

    The borosilicate glasses with Dy3+ ions were prepared by the melt quench technique with varying concentration of Dy2O3. The glasses were characterized by the density calculation, absorbance and photoluminescence (PL) spectroscopy measurements. Density and molar volume of the glasses increases with increase in Dy3+ ions in the glass matrix. This behavior is correlated with the higher molecular weight and larger ionic radius of Dy3+ ion compared to the other constituents of glass matrix. Emission of Dy3+ doped glasses showed three bands at 482, 573 and at 665 nm which correspond to 6H15/2 (blue), 6H13/2 (yellow) and 6H11/2 (red) transitions. The emission spectra of glasses with different concentration of Dy3+ ions shows that, glasses with 0.5 mol% of Dy2O3 shows highest emission and decreases with further doping. CIE 1931 chromaticity diagram showed that the emission of these glasses was in the white region. Photographs of these glasses under 349 nm Light emitting diode excitation also confirmed the white light emission from these glasses.

  14. 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

  15. Study of Structural Properties of Mesoporous Carbon From Fructose with Zinc Borosilicate Activator

    Directory of Open Access Journals (Sweden)

    Tutik Setianingsih

    2014-04-01

    Full Text Available Structural properties, including pore structure, functional group of carbon surface, and crystal structure of carbon built by zinc borosilicate (ZBS and ZnCl2 (Z have been investigated in this work. Physically, ZBS and ZnCl2 may act as template of carbon, whereas the Zn(II cation act as chemical activator of carbonization. All precursors of ZBS (silicagel, boric acid, and ZnCl2 may act as catalysts of caramelization. The caramelization was conducted hydrothermally at 85oC and thermally 130oC. The carbonization was conducted at 450oC. The resulted carbons were washed by using HF 48% solution, 1M HCl solution, and aquadest respectively. The solid products were characterized by using nitrogen gas adsorption, infrared spectrophotometry, X-ray diffraction, and Transmition Electron Microscopy. Result of research showed that ZBS built larger mesopore volume, larger pore domination of pore size, more hydrophobic carbon, and more amorf than ZnCl2.

  16. Influence of processing conditions on the glass-crystal transition into borosilicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Deschanels, X.; Cachia, J.N.; Lopez, C.; Peuget, S. [CEA Marcoule, BP 17171, 30207 Bagnols sur Ceze (France)

    2008-07-01

    The precipitation of a crystalline phase in glass is observed when one element exceeds its loading limit (i.e.: solubility limit). In this work we have studied the solubility of different actinides and surrogates (lanthanides and hafnium) in borosilicate glass used for the immobilization of the high-level nuclear waste (HLW glasses). The results obtained show an increase of the solubility limits of these elements with the processing temperature and the redox potential of the melt. The elements at the oxidation state (III) exhibit a higher solubility than the element at oxidation state (IV). In this framework, cerium is an interesting element because its oxidation state tunes from (IV) to (III) as a function of the processing conditions. It is shown that the solubility of cerium can be multiplied by a factor of 20 at 1100 C. degrees. In order to have a better understanding of the mechanisms that underline the evolution of the solubility, XAFS and NMR investigation has been undertaken. Trivalent elements present the characteristics of network-modified cations while tetravalent elements look like network-former cations.

  17. Deformation mechanisms during nanoindentation of sodium borosilicate glasses of nuclear interest

    Energy Technology Data Exchange (ETDEWEB)

    Kilymis, D. A.; Delaye, J.-M., E-mail: jean-marc.delaye@cea.fr [CEA Marcoule, DEN/DTCD, Service d’Etude et Comportement des Matériaux de Conditionnement, BP17171 30207 Bagnols-sur-Cèze Cedex (France)

    2014-07-07

    In this paper we analyze results of Molecular Dynamics simulations of Vickers nanoindentation, performed for sodium borosilicate glasses of interest in the nuclear industry. Three glasses have been studied in their pristine form, as well as a disordered one that is analogous to the real irradiated glass. We focused in the behavior of the glass during the nanoindentation in order to reveal the mechanisms of deformation and how they are affected by microstructural characteristics. Results have shown a strong dependence on the SiO{sub 2} content of the glass, which promotes densification due to the open structure of SiO{sub 4} tetrahedra and also due to the strength of Si-O bonds. Densification for the glasses is primarily expressed by the relative decrease of the Si-O-Si and Si-O-B angles, indicating rotation of the structural units and decrease of free volume. The increase of alkali content on the other hand results to higher plasticity of the matrix and increased shear flow. The most important effect on the deformation mechanism of the disordered glasses is that of the highly depolymerized network that will also induce shear flow and, in combination with the increased free volume, will result in the decreased hardness of these glasses, as has been previously observed.

  18. Deformation mechanisms during nanoindentation of sodium borosilicate glasses of nuclear interest.

    Science.gov (United States)

    Kilymis, D A; Delaye, J-M

    2014-07-07

    In this paper we analyze results of Molecular Dynamics simulations of Vickers nanoindentation, performed for sodium borosilicate glasses of interest in the nuclear industry. Three glasses have been studied in their pristine form, as well as a disordered one that is analogous to the real irradiated glass. We focused in the behavior of the glass during the nanoindentation in order to reveal the mechanisms of deformation and how they are affected by microstructural characteristics. Results have shown a strong dependence on the SiO2 content of the glass, which promotes densification due to the open structure of SiO4 tetrahedra and also due to the strength of Si-O bonds. Densification for the glasses is primarily expressed by the relative decrease of the Si-O-Si and Si-O-B angles, indicating rotation of the structural units and decrease of free volume. The increase of alkali content on the other hand results to higher plasticity of the matrix and increased shear flow. The most important effect on the deformation mechanism of the disordered glasses is that of the highly depolymerized network that will also induce shear flow and, in combination with the increased free volume, will result in the decreased hardness of these glasses, as has been previously observed.

  19. Luminescence properties of Dy3+ doped lithium zinc borosilicate glasses for photonic applications

    Directory of Open Access Journals (Sweden)

    N. Jaidass

    2018-03-01

    Full Text Available Different concentrations of Dy3+ ions doped lithium zinc borosilicate glasses of chemical composition (30-x B2O3 - 25 SiO2 -10 Al2O3 -30 LiF - 5 ZnO - x Dy2O3 (x = 0, 0.1, 0.5, 1.0 and 2.0 mol% were prepared by the melt quenching technique. The prepared glasses were investigated through X-ray diffraction, optical absorption, photoluminescence and decay measurements. Intensities of absorption bands expressed in terms of oscillator strengths (f were used to determine the Judd-Ofelt (J-O intensity parameters Ωλ (λ = 2, 4 and 6. The evaluated J-O parameters were used to determine the radiative parameters such as transition probabilities (AR, total transition probability rate (AT, radiative lifetime (τR and branching ratios (βR for the excited 4F9/2 level of Dy3+ ions. The chromaticity coordinates determined from the emission spectra were found to be located in the white light region of CIE chromaticity diagram. Keywords: Condensed matter physics, Engineering, Materials science

  20. Tc and Re Behavior in Borosilicate Waste Glass Vapor Hydration Tests

    International Nuclear Information System (INIS)

    McKeown, David A.; Buechele, Andrew C.; Pegg, Ian L.; Lukens, Wayne W.; Shuh, David K.

    2007-01-01

    Technetium (Tc), found in some nuclear wastes, is of particular concern with regard to long-term storage, because of its long-lived radioactivity and high mobility in the environment. Tc and rhenium (Re), commonly used as a non-radioactive surrogate for Tc, were studied to assess their behavior in borosilicate glass under hydrothermal conditions in the Vapor Hydration Test (VHT). X-ray absorption spectroscopy (XAS) and scanning electron microscopy (SEM) measurements were made on the original Tc- and Re-containing glasses and their corresponding VHT samples, and show different behavior for Tc and Re under VHT conditions. XAS indicates that, despite starting with different Tc(IV) and Tc(VII) distributions in each glass, the VHT samples have 100% Tc(IV)O 6 environments. SEM shows complete alteration of the original glass, Tc enrichment near the sample surface, and Tc depletion in the center. Perrhenate (Re(VII)O 4 - ) is dominant in both Re-containing samples before and after the VHT, where Re is depleted near the VHT sample surface and more concentrated toward the center. (authors)

  1. Processing and optical characterization of lead calcium titanate borosilicate glass doped with germanium

    Science.gov (United States)

    Gautam, C. R.; Das, Sangeeta; Gautam, S. S.; Madheshiya, Abhishek; Singh, Anod Kumar

    2018-04-01

    In this study, various compositions of lead calcium titanate borosilicate glass doped with a fixed amount of germanium were synthesized using the rapid melt quench technique. The amorphous nature of the synthesized glass was confirmed by X-ray diffraction and scanning electron microscopy analyses. The structural and optical properties were deduced using Raman, Fourier transform infrared (FTIR), and ultraviolet-visible (UV-Vis) spectroscopy. FTIR spectroscopy confirmed the presence of borate groups in triangular and tetrahedral coordination. Infrared and Raman analyses detected the vibrational bonds of Gesbnd Osbnd Ge, Bsbnd Osbnd Ge, Sisbnd Osbnd Ge, Sisbnd Osbnd Si, and Pbsbnd Osbnd Ge. The energy band gaps were evaluated for the prepared glass samples based on Tauc plots of the UV-Vis spectra. The calculated values of the optical band gap decreased from 2.91 to 2.85 eV as the PbO content increased from x = 0.0 to x = 0.7. Furthermore, the Urbach energy was studied based on the UV-Vis results to confirm the disordered structure of the glass. The calculated densities of the glass samples (1.5835 g/cm3 to 3.9184 g/cm3) increased as the concentration of PbO increased, whereas they decreased with the molar volume.

  2. High-level waste borosilicate glass: A compendium of corrosion characteristics. Volume 2

    International Nuclear Information System (INIS)

    Cunnane, J.C.

    1994-03-01

    The objective of this document is to summarize scientific information pertinent to evaluating the extent to which high-level waste borosilicate glass corrosion and the associated radionuclide release processes are understood for the range of environmental conditions to which waste glass may be exposed in service. Alteration processes occurring within the bulk of the glass (e.g., devitrification and radiation-induced changes) are discussed insofar as they affect glass corrosion.This document is organized into three volumes. Volumes I and II represent a tiered set of information intended for somewhat different audiences. Volume I is intended to provide an overview of waste glass corrosion, and Volume 11 is intended to provide additional experimental details on experimental factors that influence waste glass corrosion. Volume III contains a bibliography of glass corrosion studies, including studies that are not cited in Volumes I and II. Volume I is intended for managers, decision makers, and modelers, the combined set of Volumes I, II, and III is intended for scientists and engineers working in the field of high-level waste

  3. High-level waste borosilicate glass: A compendium of corrosion characteristics. Volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Cunnane, J.C. [comp.; Bates, J.K.; Bradley, C.R. [Argonne National Lab., IL (United States)] [and others

    1994-03-01

    The objective of this document is to summarize scientific information pertinent to evaluating the extent to which high-level waste borosilicate glass corrosion and the associated radionuclide release processes are understood for the range of environmental conditions to which waste glass may be exposed in service. Alteration processes occurring within the bulk of the glass (e.g., devitrification and radiation-induced changes) are discussed insofar as they affect glass corrosion.This document is organized into three volumes. Volumes I and II represent a tiered set of information intended for somewhat different audiences. Volume I is intended to provide an overview of waste glass corrosion, and Volume 11 is intended to provide additional experimental details on experimental factors that influence waste glass corrosion. Volume III contains a bibliography of glass corrosion studies, including studies that are not cited in Volumes I and II. Volume I is intended for managers, decision makers, and modelers, the combined set of Volumes I, II, and III is intended for scientists and engineers working in the field of high-level waste.

  4. Immobilization of simulated high-level radioactive waste in borosilicate glass: Pilot scale demonstrations

    International Nuclear Information System (INIS)

    Ritter, J.A.; Hutson, N.D.; Zamecnik, J.R.; Carter, J.T.

    1991-01-01

    The Integrated DWPF Melter System (IDMS), operated by the Savannah River Laboratory, is a pilot scale facility used in support of the start-up and operation of the Department of Energy's Defense Waste Processing Facility. The IDMS has successfully demonstrated, on an engineering scale (one-fifth), that simulated high level radioactive waste (HLW) sludge can be chemically treated with formic acid to adjust both its chemical and physical properties, and then blended with simulated precipitate hydrolysis aqueous (PHA) product and borosilicate glass frit to produce a melter feed which can be processed into a durable glass product. The simulated sludge, PHA and frit were blended, based on a product composition program, to optimize the loading of the waste glass as well as to minimize those components which can cause melter processing and/or glass durability problems. During all the IDMS demonstrations completed thus far, the melter feed and the resulting glass that has been produced met all the required specifications, which is very encouraging to future DWPF operations. The IDMS operations also demonstrated that the volatile components of the melter feed (e.g., mercury, nitrogen and carbon, and, to a lesser extent, chlorine, fluorine and sulfur) did not adversely affect the melter performance or the glass product

  5. Effect of various lead species on the leaching behavior of borosilicate waste glass

    International Nuclear Information System (INIS)

    Lehman, R.L.; Kuchinski, F.A.

    1984-01-01

    A borosilicate nuclear waste glass was static leached in pure water, silicate water, and brine solution. Three different forms of lead were included in specified corrosion cells to assess the extent to which various lead species alter the leaching behavior of the glass. Weight loss data indicated that Pb/sub m/ amd PbO greatly reduce the weight loss of glass when leached in pure water, and similar effects were noted in silicate and brine. Si concentrations, which were substantial in the glass-alone leachate, were reduced to below detection limits in all pure water cells containing a lead form. Lead concentration levels in the leachate were controlled by lead form solubility and appeared to be a significant factor in influencing apparent leaching behavior. Surface analysis revealed surface crystals, which probably formed when soluble lead in the leachate reacted with dissolved or activated silica at the glass surface. The net effect was to reduce the lease of some glass constituents to the leachate, although it was not clear whether the actual corrosion of the glass surface was reduced. Significantly different corrosion inhibiting effects were noted among lead metal and two forms of lead oxide. 9 refs., 7 figs., 3 tabs

  6. Volatilization from borosilicate glass melts of simulated Savannah River Plant waste

    International Nuclear Information System (INIS)

    Wilds, G.W.

    1979-01-01

    Laboratory scale studies determined the rates at which the semivolatile components sodium, boron, lithium, cesium, and ruthenium volatilized from borosilicate glass melts that contained simulated Savannah River Plant waste sludge. Sodium and boric oxides volatilize as the thermally stable compound sodium metaborate, and accounted for approx. 90% of the semivolatiles that evolved. The amounts of semivolatiles that evolved increased linearly with the logarithm of the sodium content of the glass-forming mixture. Cesium volatility was slightly suppressed when titanium dioxide was added to the melt, but was unaffected when cesium was added to the melt as a cesium-loaded zeolite rather than as a cesium carbonate solution. Volatility of ruthenium was not suppressed when the glass melt was blanketed with a nonoxidizing atmosphere. Trace quantities of mercury were removed from vapor streams by adsorption onto a silver-exchanged zeolite. A bed containing silver in the ionic state removed more than 99.9% of the mercury and had a high chemisorption capacity. Beds of lead-, copper-, and copper sulfide-exchanged zeolite-X and also an unexchanged zeolite-X were tested. None of these latter beds had high removal efficiency and high chemisorption capacity

  7. Volatilization from borosilicate glass melts of simulated Savannah River Plant waste

    International Nuclear Information System (INIS)

    Wilds, G.W.

    1978-01-01

    Laboratory scale studies determined the rates at which the semivolatile components sodium, boron, lithium, cesium, and ruthenium volatilized from borosilicate glass melts that contained simulated Savannah River Plant waste sludge. Sodium and boric oxides volatilize as the thermally stable compound sodium metaborate, and accounted for approx. 90% of the semivolatiles that evolved. The amounts of semivolatiles that evolved increased linearly with the logarithm of the sodium content of the glass-forming mixture. Cesium volatility was slightly suppressed when titanium dioxide was added to the melt, but was unaffected when cesium was added to the melt as a cesium-loaded zeolite rather than as a cesium carbonate solution. Volatility of ruthenium was not suppressed when the glass melt was blanketed with a nonoxidizing atmosphere. Trace quantities of mercury were removed from vapor streams by adsorption onto a silver-exchanged zeolite. A bed containing silver in the ionic state removed more than 99.9% of the mercury and had a high chemisorption capacity. Beds of lead-, copper-, and copper sulfide-exchanged zeolite-X and also an unexchanged zeolite-X were tested. None of these latter beds had high removal efficiency and high chemisorption capacity

  8. 3 and 4 oxidation state element solubilities in borosilicate glasses. Implement to actinides in nuclear glasses

    International Nuclear Information System (INIS)

    Cachia, J.N.

    2005-12-01

    In order to ensure optimal radionuclides containment, the knowledge of the actinide loading limits in nuclear waste glasses and also the comprehension of the solubilization mechanisms of these elements are essential. A first part of this manuscript deals with the study of the differences in solubility of the tri and tetravalent elements (actinides and surrogates) particularly in function of the melting temperature. The results obtained indicate that trivalent elements (La, Gd, Nd, Am, Cm) exhibit a higher solubility than tetravalent elements (Hf, Th, Pu). Consequently, it was planned to reduce plutonium at the oxidation state (III), the later being essentially tetravalent in borosilicate glasses. An innovating reduction process of multi-valent elements (cerium, plutonium) using silicon nitride has been developed in a second part of this work. Reduced plutonium-bearing glasses synthesized by Si 3 N 4 addition made it possible to double the plutonium solubility from 2 to 4 wt% at 1200 deg C. A structural approach to investigate the differences between tri and tetravalent elements was finally undertaken. These investigations were carried out by X-rays Absorption Spectroscopy (EXAFS) and NMR. Trivalent rare earth and actinide elements seem to behave as network modifiers while tetravalent elements rather present true intermediaries' behaviour. (author)

  9. 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.

  10. Le ministre du Commerce international du Canada rencontre des ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    17 juil. 2017 ... La promotion de l'entrepreneuriat, la façon dont le commerce peut profiter aux femmes et à leur famille, et la création d'emplois pour les plus vulnérables étaient au coeur de la discussion en table ronde du ministre du Commerce international du Canada, l'honorable François-Philippe Champagne, et des ...

  11. Portage vaginal du streptocoque du groupe B chez la femme ...

    African Journals Online (AJOL)

    Introduction: le streptocoque du groupe B est le principal agent impliqué dans les infections materno-fœtales, les septicémies et les méningites du nouveau-né à terme. L'objectif est de déterminer le taux de portage maternel du streptocoque du groupe B (SGB) à terme. Méthodes: un prélèvement vaginal a été réalisé de ...

  12. Aux origines du monde

    CERN Multimedia

    2004-01-01

    "C'est l'histoire d'une aventure humaine, scientifique, international qui a vu le jour il y a cinquante ans, aux confins de la Suisse et du département de l'Ain. Le plus grand laboratoire de physique des particules du monde, le Cern, a été fondé en 1954. Les festivités organisées à l occasion de cet anniversaire connaîtront leur point d'orgue le 16 octobre prochain, avec portes-ouvertes, accueil de personallités et inauguration d'un monumnet spécifique, le Globe de l'innovation" (2 pages)

  13. CHOEUR DU CERN

    CERN Multimedia

    CHOEUR DU CERN

    2010-01-01

    Les répétitions du chœur du CERN reprendront le mercredi 15 septembre à 20.00 heures à l’amphithéâtre principal – bâtiment 500. Au programme la préparation de notre concert de Noël avec la Missa Brevis, KV115, de Léopold Mozart et de la musique de Noël d’Europe. Les personnes qui aiment chanter, notamment des sopranes et des ténors, sont les bienvenues. Pour tout contact s’adresser à : Baudouin Bleus - (tél.CERN 767 82 44) -(baudouin.bleus@cern.ch) ou Martin Gatehouse ( martin.gatehouse@wanadoo.fr) ou Jean-Paul Diss (jean-pauldiss@wanadoo.fr).  

  14. Hepatiques du Surinam

    NARCIS (Netherlands)

    Jovet-Ast, S.

    1957-01-01

    Il n’existe pas, actuellement, de catalogue des Hépatiques du Surinam. Les Hépatiques de ce pays restent très peu connues. Cependant, certaines ont attiré l’attention des Bryologues et ont été citées dans quelques ouvrages anciens ou récents. Je ne ferai pas ici une révision complète de ces

  15. (l.) Medik du Maroc

    African Journals Online (AJOL)

    PR BOKO

    Résumé. Dipcadi serotinum (L.) Medik, est une plante de la famille des Hyacinthaceae, elle est largement utilisée comme réchauffant et aussi pour combattre la jaunisse. Cette plante trouve une large utilisation par la population de la région côtière du Maroc. À notre connaissance l'huile essentielle de cette espèce n'a ...

  16. La mesure du danger

    CERN Document Server

    Manceron, Vanessa; Revet, Sandrine

    2014-01-01

    La mesure du danger permet d’explorer des dangers de nature aussi diverse que la délinquance, la pollution, l’écueil maritime, la maladie ou l’attaque sorcellaire, l’extinction d’espèces animales ou végétales, voire de la Planète tout entière. Au croisement de la sociologie, de l’anthropologie et de l’histoire, les différents articles analysent les pratiques concrètes de mesure pour tenter de comprendre ce qui se produit au cours de l’opération d’évaluation du danger sans préjuger de la nature de celui-ci. L’anthropologie a contribué à la réflexion sur l’infortune en s’intéressant aux temporalités de l’après : maladies, catastrophes, pandémies, etc. et en cherchant à rendre compte de l’expérience des victimes, de leur vie ordinaire bouleversée, de la recomposition du quotidien. Elle s’intéresse aussi aux autres types de mesures, les savoirs incorporés, qui reposent sur l’odorat, la vue ou le toucher et ceux qui ressortent d’une épistémologie « non ...

  17. Investigation of U3O8 immobilization in the GP-91 borosilicate glass by induction melter with a cold crucible (CCIM)

    International Nuclear Information System (INIS)

    Matyunin, Y.I.; Demin, A.V.; Smelova, T.V.; Yudintsev, S.V.; Lapina, M.I.

    1997-01-01

    One of the most promising and intensively developed methods for the solidification of high-level wastes is their vitrification with the use of a cold crucible induction melter (CCIM), which offers a number of advantages over ceramic melter. This work is concerned with comparison studies on the behavior of uranium in vitreous borosilicate materials synthesized by the traditional technique (melting in muffle furnaces) and CCIM method. The incorporation of uranium oxide U 3 O 8 into the GP-91 borosilicate glass with the use of CCIM technology is investigated. The limiting solubility of uranium in the GP-91 borosilicate glass is evaluated. The phase composition of precipitated dispersed particles based on uranium is determined. Some physicochemical properties of synthesized materials are explored. Investigations into the behavior of uranium in borosilicate glass prepared in the CCIM show a feasibility to synthesize the X-ray amorphous homogeneous borosilicate glasses incorporating as much as 25 - 28 wt% uranium, which is 4 - 5 times larger than that in glasses obtained by the traditional method. (author)

  18. Laser-assisted fabrication of gold nanoparticle-composed structures embedded in borosilicate glass

    Directory of Open Access Journals (Sweden)

    Nikolay Nedyalkov

    2017-11-01

    Full Text Available We present results on laser-assisted formation of two- and three-dimensional structures comprised of gold nanoparticles in glass. The sample material was gold-ion-doped borosilicate glass prepared by conventional melt quenching. The nanoparticle growth technique consisted of two steps – laser-induced defect formation and annealing. The first step was realized by irradiating the glass by nanosecond and femtosecond laser pulses over a wide range of fluences and number of applied pulses. The irradiation by nanosecond laser pulses (emitted by a Nd:YAG laser system induced defect formation, expressed by brown coloration of the glass sample, only at a wavelength of 266 nm. At 355, 532 and 1064 nm, no coloration of the sample was observed. The femtosecond laser irradiation at 800 nm also induced defects, again observed as brown coloration. The absorbance spectra indicated that this coloration was related to the formation of oxygen deficiency defects. After annealing, the color of the irradiated areas changed to pink, with a corresponding well-defined peak in the absorbance spectrum. We relate this effect to the formation of gold nanoparticles with optical properties defined by plasmon excitation. Their presence was confirmed by high-resolution TEM analysis. No nanoparticle formation was observed in the samples irradiated by nanosecond pulses at 355, 532 and 1064 nm. The optical properties of the irradiated areas were found to depend on the laser processing parameters; these properties were studied based on Mie theory, which was also used to correlate the experimental optical spectra and the characteristics of the nanoparticles formed. We also discuss the influence of the processing conditions on the characteristics of the particles formed and the mechanism of their formation and demonstrate the fabrication of structures composed of nanoparticles inside the glass sample. This technique can be used for the preparation of 3D nanoparticle systems

  19. Leaching of the simulated borosilicate waste glasses and spent nuclear fuel under a repository condition

    International Nuclear Information System (INIS)

    Kim, Seung Soo; Chun, Kwan Sik; Kang, Chul Hyung; Suh, Hang Suk

    2002-12-01

    Leaching behaviors of simulated waste glass and spent fuel, contacted on bentonite blocks, in synthetic granitic groundwater were investigated in this study. The leach rate of boron from borosilicate waste glass between the compacted bentonite blocks reached about 0.03 gm-2day-1 at 1500 days, like as that of molybdenum. However, the concentration of uranium in leachate pass through bentonite blocks was less than their detection limits of 2 μg/L and whose yellow amorphous compound was found on the surface of glass contacted with the bentonite blocks. The leaching mechanism of waste glasses differed with their composition. The release rate of cesium from PWR spent fuel in the simulated granitic water without bentonite was leas than $1.0x10 -5 fraction/day after 300 days. The retardation factor of cesium by a 10 -mm thickness of bentonite block was more than 100 for 4-years leaching time. The cumulative release fraction of uranium for 954 days was 0.016% (1.7x10 -7 fraction/day) in granitic water without bentonite. The gap inventory of cesium for spent fuel G23-J11 was 0.15∼0.2%. However, the release of cesium from C15-I08 was 0.9% until 60 days and has being continued after that. Gap inventories of strontium and iodine in G23-J11 were 0.033% and below 0.2%, respectively. The sum of fraction of cesium in gap and grain boundary of G23-J11 was suggested below 3% and less

  20. An enhanced resolution of the structural environment of zirconium in borosilicate glasses

    International Nuclear Information System (INIS)

    Jollivet, P.; Angeli, F.; Bergeron, B.; Gin, S.; Calas, G.; Galoisy, L.; Ruffoni, M.P.; Trcera, N.

    2013-01-01

    The short- and medium-range local environment of zirconium was determined by Zr L 2,3 -edge and K-edge XANES and by Zr K-edge EXAFS in borosilicate glasses with 1 to 8 mol% ZrO 2 . Regardless of the ZrO 2 content of the glass, Zr is six-coordinated in octahedra with Zr-O distances of 2.09 Angstroms. In the glasses containing 8 mol% ZrO 2 , the octahedra are more distorted than at lower ZrO 2 content. Enhanced resolution in the real space is achieved by recording Zr K-edge EXAFS spectra over a broad energy range, enabling to get access k-values up to 20 Angstroems -1 with a high signal to noise ratio. This allows discriminate between the various second neighbor contributions. A correct fit is based on four Si and two B. This local structure around Zr derived from that of zircono-silicates such as elpidite, in which two Si are replaced by two B. The Zr-Si distances increase from 3.63 ± 0.02 to 3.67 ± 0.01 Angstroms, as Zr-B distances remain constant within uncertainties, as ZrO 2 content increases. Two Na are situated at 3.64 ± 0.03 Angstroms from Zr, ensuring charge compensation of the ZrO 6 sites. Increasing the CaO content from 4 to 8 mol% does not lead to any structural change around Zr. (authors)

  1. The influence of ZnO incorporation on the aqueous leaching characteristics of a borosilicate glass

    Science.gov (United States)

    Vance, E. R.; Gregg, D. J.; Karatchevtseva, I.; Griffiths, G. J.; Olufson, K.; Rees, Gregory J.; Hanna, John V.

    2017-10-01

    With increasing ZnO content, short term aqueous durability enhancement of all elements in borosilicate glasses containing 1.0 and 3.85 wt% ZnO was evident in 7-day PCT-B tests. In 14-day MCC-1 type leach tests conducted at 90 °C, surface alteration was very clear in the undoped glass via the formation of strongly altered amorphous material which tended to spall off the surface. No sign of crystallinity was detected by grazing incidence X-ray diffraction or electron microscopy of the surface layers and the surface material was very rich in silica. For the ZnO-bearing glasses, significant growth of particles following PCT leaching for 7 days was observed, due to a build-up of surface ZnO-containing Si-rich material and possible agglomeration. This alteration layer was also observed in MCC-1 type experiments in which cross-section SEM-EDS data were obtained. Raman, infrared and 11B and 29Si MAS NMR spectroscopy showed only slight changes in boron speciation on the addition of up to 9.1 wt% ZnO. Bulk positron annihilation lifetime spectra (PALS) of glasses containing 0-3.85 wt% ZnO could be analysed with three distinct lifetimes and also showed only slight differences. These results indicate that the basic glass structure was essentially not influenced by the ZnO content and that the passivation of the alteration layer is promoted by ZnO content.

  2. Synthesis, electrical and magnetic properties of sodium borosilicate glasses containing Co-ferrites nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Othman, H.A. [Department of Physics, Faculty of Science, Menoufia University, Shibin El-Kom 32511, Menoufia (Egypt); Eltabey, M.M. [Department of Basic Engineering Science, Faculty of Engineering, Menoufia University, Shibin El-Kom, Menoufia (Egypt); Department of Physics, Faculty of Science, Jazan University (Saudi Arabia); Ibrahim, Samia E.; El-Deen, L.M. Sharaf; Elkholy, M.M. [Department of Physics, Faculty of Science, Menoufia University, Shibin El-Kom 32511, Menoufia (Egypt)

    2017-02-01

    Co-ferrites nanoparticles that have been prepared by the co-precipitation method were added to sodium borosilicate (Na{sub 2}O–B{sub 2}O{sub 3}–SiO{sub 2}) glass matrix by the solid solution method and they were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and magnetization measurements. (XRD) revealed the formation of the Co-ferrite magnetic crystalline phase embedded in an amorphous matrix in all the samples. The investigated samples by (TEM) showed the formation of the cobalt ferrite nanoparticles with a spherical shape and highly monodispersed with an average size about 13 nm. IR data revealed that the BO{sub 3} and BO{sub 4} are the main structural units of these samples network. IR spectra of the investigated samples showed the characteristic vibration bands of Co-ferrite. Composition and frequency dependent dielectric properties of the prepared samples were measured at room temperature in the frequency range 100–100 kHz. The conductivity was found to increase with increasing cobalt ferrite content. The variations of conductivity and dielectric properties with frequency and composition were discussed. Magnetic hysteresis loops were traced at room temperature using VSM and values of saturation magnetization M{sub S} and coercive field H{sub C} were determined. The obtained results revealed that a ferrimagnetic behavior were observed and as Co-ferrite concentration increases the values of M{sub S} and H{sub C} increase from 2.84 to 8.79 (emu/g) and from 88.4 to 736.3 Oe, respectively.

  3. Borosilicate glass as a matrix for immobilization of SRP high-level waste

    International Nuclear Information System (INIS)

    Wicks, G.G.

    1980-01-01

    Approximately 22 million gallons of high-level radioactive defense waste are currently being stored in large underground tanks located on the Savannah River Plant (SRP) site in Aiken, South Carolina. One option now being considered for long-term management of this waste involves removing the waste from the tanks, chemically processing the waste, and immobilizing the potentially harmful radionuclides in the waste into a borosilicate glass matrix. The technology for producing waste glass forms is well developed and has been demonstrated on various scales using simulated as well as radioactive SRP waste. Recently, full-scale prototypical equipment has been made operational at SRP. This includes both a joule-heated ceramic melter and an in-can melter. These melters are a part of an integrated vitrification system which is under evaluation and includes a spray calciner, direct liquid feed apparatus, and various elements of an off-gas system. Two of the most important properties of the waste glass are mechanical integrity and leachability. Programs are in progress at SRL aimed at minimizing thermally induced cracking by carefully controlling cooling cycles and using ceramic liners or coatings. The leachability of SRP waste glass has been studied under many different conditions and consistently found to be low. For example, the leachability of actual SRP waste glass was found to be 10 -6 to 10 -5 g/(cm 2 )(day) initially and decreasing to 10 -9 to 10 -8 g/(cm 2 )(day) after 100 days. Waste glass is also being studied under anticipated storage conditions. In brine at 90 0 C, the leachability is about 5 x 10 -8 g/(cm 2 )(day) after 60 days. The effects of other geological media including granite, basalt, shale, and tuff are also being studied as part of the multibarrier isolation system

  4. Archives: les cahiers du cread

    African Journals Online (AJOL)

    Items 1 - 24 of 24 ... Archives: les cahiers du cread. Journal Home > Archives: les cahiers du cread. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. 1 - 24 of 24 Items. 2016 ...

  5. Le commerce du Nord

    OpenAIRE

    Pourchasse, Pierrick; Bouëdec, Gérard Le

    2015-01-01

    Au XVIIIe siècle, la France s'approvisionne abondamment dans les pays du Nord : bois, chanvre et goudron de la Baltique, tonnellerie de Poméranie, pêche de rogue de Norvège, graines de lin de Courlande, barres de fer suédois… Sa balance commerciale est pourtant positive grâce aux sels, aux vins et surtout des nouvelles marchandises coloniales. Or, la plupart des transactions passent par l’incontournable intermédiaire hollandais. Les explications sur l’absence des Français dans le Nord sont re...

  6. La voie du Centre

    OpenAIRE

    2017-01-01

    Après avoir quelque peu louvoyé dans un discours apparemment anarchique où les souvenirs semblent se bousculer sans autre fil conducteur que la référence obsédante au mal satanique, brusquement le narrateur annonce un événement primordial : Foi um fato que se deu, um dia, se abriu. O primeiro. Depois o senhor verá por quê, me devolvendo minha razão (79). Cette introduction situe la rencontre du Menino comme fondatrice d’un destin dont il reviendrait au narrataire de dégager les enchaînements....

  7. Bulletin du CRDI #126

    International Development Research Centre (IDRC) Digital Library (Canada)

    26 févr. 2018 ... Dans ce numéro, découvrez comment la recherche financée par le CRDI permet d'améliorer la santé des mères et des enfants dans les pays du Sud et comment les innovations techniques et sociales de l'initiative SEARCH permettent de surmonter les défis liés à la cybersanté. N'oubliez pas non plus de ...

  8. Activation and transfer of sulfate in biological systems (1960); Activation biologique du sulfate et son transfert (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Chapeville, F [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    It examines in this review the successive stages of active sulfate formation and its role in biological synthesis of sulfuric esters. The possible role of active sulfate as intermediary in sulfate reduction is also discussed. (author) [French] On examine dans cette etude les stades successifs de la mise en evidence du sulfate actif, son role dans la formation des esters sulfuriques de natures diverses, ainsi que sa participation eventuelle comme intermediaire au cours de la reduction du sulfate. On decrit aussi un procede de preparation du systeme biologique, generateur du sulfate actif et une methode de synthese chimique. (auteur)

  9. Choeur du CERN : Concert

    CERN Multimedia

    CERN Choir

    2017-01-01

    Une œuvre à découvrir! La grande Missa pro defunctis de François-Joseph Gossec (1734-1829) est le chef-d’œuvre tôt venu (à vingt-cinq ans) d’un compositeur qui vivra encore 70 ans après sa création. Elle a connu la gloire, puis s’est fait un peu oublier. Pas du tout le monde cependant : des musicologues ont montré ce que le Requiem de Mozart lui devait ; et il suffit de l’avoir entendue pour comprendre pourquoi Berlioz (qui avait vingt-six ans à la mort de Gossec) en a été impressionné : les nombreux cuivres et bois répartis dans des endroits plus ou moins cachés de la salle de concert pour exprimer les frayeurs du Jugement dernier annoncent son Requiem – et celui de Verdi. Mais « plus encore que par...

  10. Les risques du travail

    CERN Document Server

    Thébaud-Mony, Annie

    2015-01-01

    Depuis les années 1990, les conditions de travail se sont peu à peu imposées dans le débat social. Néanmoins, la situation reste critique. Les risques traditionnels n'ont pas disparu : les manutentions lourdes, l'exposition professionnelle aux cancérogènes, au bruit ou aux vibrations demeurent répandues... De plus, certaines " améliorations " n'ont fait que déplacer et dissimuler les problèmes, telle l'externalisation des risques grâce à la sous-traitance. Dans le même temps, les transformations du travail et des modalités de gestion de la main-d'œuvre ont fragilisé les collectifs et accru l'isolement des salariés, conduisant à une montée visible de la souffrance psychique. Face à ces évolutions, il est plus que jamais nécessaire que tous les acteurs concernés, en particulier les salariés eux-mêmes et leurs représentants, s'approprient les connaissances indispensables pour améliorer la protection de la santé sur les lieux du travail. Tel est le but de ce livre, qui renouvelle int�...

  11. Diffusion of cesium in sodium-borosilicate glasses for nuclear waste immobilisation. Diffusie van cesium in natrium borosilicaat glazen voor het immobiliseren van radioaktief afval

    Energy Technology Data Exchange (ETDEWEB)

    Janssen, F.J.J.G.; Sengers, E.G.F. (Keuring van Electrotechnische Materialen NV, Arnhem (Netherlands)); Waal, H. de (TPD-TNO-Glass technology, Eindhoven (Netherlands))

    1989-09-26

    Diffusion of cesium in borosilicate glass for high-level radioactive waste is discussed. For this purpose model glasses with non-radioactive elements are being made, in accordance with the specifications of the reprocessing plants, from which concentration couples are composed. A concentration couple consists of two cylinders of borosilicate glass which contain different amounts of cesium. After heat treatment the couples are studied by means of the scanning electron microscopy and X-ray microanalysis. The model study will provide a basis for predictions of the containment achieved over a longer period of time. (author). 11 refs.; 2 figs.; 2 tabs.

  12. Gamma ray shielding study of barium-bismuth-borosilicate glasses as transparent shielding materials using MCNP-4C code, XCOM program, and available experimental data

    Energy Technology Data Exchange (ETDEWEB)

    Bagheri, Reza; Yousefinia, Hassan [Nuclear Fuel Cycle Research School (NFCRS), Nuclear Science and Technology Research Institute (NSTRI), Atomic Energy Organization of Iran, Tehran (Iran, Islamic Republic of); Moghaddam, Alireza Khorrami [Radiology Department, Paramedical Faculty, Mazandaran University of Medical Sciences, Sari (Iran, Islamic Republic of)

    2017-02-15

    In this work, linear and mass attenuation coefficients, effective atomic number and electron density, mean free paths, and half value layer and 10th value layer values of barium-bismuth-borosilicate glasses were obtained for 662 keV, 1,173 keV, and 1,332 keV gamma ray energies using MCNP-4C code and XCOM program. Then obtained data were compared with available experimental data. The MCNP-4C code and XCOM program results were in good agreement with the experimental data. Barium-bismuth-borosilicate glasses have good gamma ray shielding properties from the shielding point of view.

  13. Gamma Ray Shielding Study of Barium–Bismuth–Borosilicate Glasses as Transparent Shielding Materials using MCNP-4C Code, XCOM Program, and Available Experimental Data

    Directory of Open Access Journals (Sweden)

    Reza Bagheri

    2017-02-01

    Full Text Available In this work, linear and mass attenuation coefficients, effective atomic number and electron density, mean free paths, and half value layer and 10th value layer values of barium–bismuth–borosilicate glasses were obtained for 662 keV, 1,173 keV, and 1,332 keV gamma ray energies using MCNP-4C code and XCOM program. Then obtained data were compared with available experimental data. The MCNP-4C code and XCOM program results were in good agreement with the experimental data. Barium–bismuth–borosilicate glasses have good gamma ray shielding properties from the shielding point of view.

  14. The role of brachytherapy in the definitive management of prostate cancer; Place de la curietherapie dans le traitement du cancer prostatique localise

    Energy Technology Data Exchange (ETDEWEB)

    Crook, J. [British Columbia Cancer Agency, Center for the Southern Interior, 399, Royal Avenue, Kelowna, British Columbia, V1Y 5L33 (Canada)

    2011-06-15

    Over the past two decades, brachytherapy has played an ever expanding role in the definitive radiotherapy of prostate cancer. Brachytherapy surpasses external beam radiotherapy in its ability to deliver intense intra-prostatic dose escalation. Although initially low dose rate permanent seed brachytherapy was favored for favorable risk prostate cancers, and high dose rate temporary brachytherapy for intermediate and advanced disease, both types of brachytherapy now have a place across all the risk groups of localized prostate cancer. This article will review indications and patient selection, planning and technical aspects, toxicity and efficacy for both low and high dose rate prostate brachytherapy. (author)

  15. Contribution to the study of the role of diffusion in the growth of crystals from solution; Contribution a l'etude du role de la diffusion dans la croissance des cristaux a partir de solution

    Energy Technology Data Exchange (ETDEWEB)

    Quivy, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-12-01

    In the case of the two-dimensional growth of crystals from solution, the concentration distribution could be explained on the basis of Fick diffusion equation. The limiting conditions are defined in a satisfactory way, and the curves of equal concentration in the solution surrounding the crystal are calculated using a resistance network device. These curves are similar to the observed interference fringes. The limiting conditions are different according as to whether the type of crystal growth is regular or dendritic. In this work the growth rate of the crystal faces in solution has been measured for various substances. These direct measurements were carried out using a micrometric eye-piece and chrono-photographs. The interferential method using polarized light has been used for determining the concentration distribution in the neighbourhood of the crystal; it was thereby possible, knowing the diffusion coefficient, to calculate the growth rate and to observe the existence of a disagreement, of the order of two, with the direct measurements. This discrepancy can even attain a value of ten in the case of very soluble substances; these latter have been studied by R. ITTI. (author) [French] Dans le cas de la croissance a deux dimensions de cristaux a partir de solution, la distribution des concentrations pouvait etre expliquee a partir de l'equation de diffusion de FICK. En fixant les conditions aux limites de facon convenable, on calcule, au moyen d'un dispositif a reseaux resistifs, les courbes d'egale concentration de la solution entourant le cristal. On constate que ces courbes sont semblables aux franges d'interferences observees. Les conditions aux limites sont differentes suivant que le type de croissance du cristal est regulier ou dendritique. Dans ce travail, on a egalement mesure les vitesses de croissance des faces cristallines a partir de solutions, en employant differentes substances. Ces mesures directes ont ete effectuees au moyen d'un oculaire

  16. X-ray absorption studies of chlorine valence and local environments in borosilicate waste glasses

    International Nuclear Information System (INIS)

    McKeown, David A.; Gan, Hao; Pegg, Ian L.; Stolte, W.C.; Demchenko, I.N.

    2011-01-01

    Chlorine (Cl) is a constituent of certain types of nuclear wastes and its presence can affect the physical and chemical properties of silicate melts and glasses developed for the immobilization of such wastes. Cl K-edge X-ray absorption spectra (XAS) were collected and analyzed to characterize the unknown Cl environments in borosilicate waste glass formulations, ranging in Cl-content from 0.23 to 0.94 wt.%. Both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) data for the glasses show trends dependent on calcium (Ca) content. Near-edge data for the Ca-rich glasses are most similar to the Cl XANES of CaCl 2 , where Cl - is coordinated to three Ca atoms, while the XANES for the Ca-poor glasses are more similar to the mineral davyne, where Cl is most commonly coordinated to two Ca in one site, as well as Cl and oxygen nearest-neighbors in other sites. With increasing Ca content in the glass, Cl XANES for the glasses approach that for CaCl 2 , indicating more Ca nearest-neighbors around Cl. Reliable structural information obtained from the EXAFS data for the glasses is limited, however, to Cl-Cl, Cl-O, and Cl-Na distances; Cl-Ca contributions could not be fit to the glass data, due to the narrow k-space range available for analysis. Structural models that best fit the glass EXAFS data include Cl-Cl, Cl-O, and Cl-Na correlations, where Cl-O and Cl-Na distances decrease by approximately 0.16 A as glass Ca content increases. XAS for the glasses indicates Cl - is found in multiple sites where most Cl-sites have Ca neighbors, with oxygen, and possibly, Na second-nearest neighbors. EXAFS analyses suggest that Cl-Cl environments may also exist in the glasses in minor amounts. These results are generally consistent with earlier findings for silicate glasses, where Cl - was associated with Ca 2+ and Na + in network modifier sites.

  17. Optical properties of 3d transition metal ion-doped sodium borosilicate glass

    International Nuclear Information System (INIS)

    Wen, Hongli; Tanner, Peter A.

    2015-01-01

    Graphical abstract: Photographs of undoped (SiO 2 ) 50 (Na 2 O) 25 (B 2 O 3 ) 25 (SiNaB) glass and transition metal ion-doped (TM) 0.5 (SiO 2 ) 49.5 (Na 2 O) 25 (B 2 O 3 ) 25 glass samples. - Highlights: • 3d transition metal ion (from Ti to Zn) doped SiO 2 -Na 2 O-B 2 O 3 glasses. • Optical properties of doped glasses investigated. • V(IV,V); Cr(III, VI); Mn(II,III); Fe(II,III); Co(II); Ni(II); Cu(II) by XANES, DRS. • Strong visible absorption but only vanadium ion gives strong emission in glass. - Abstract: SiO 2 -Na 2 O-B 2 O 3 glasses doped with 3d-transition metal species from Ti to Zn were prepared by the melting-quenching technique and their optical properties were investigated. The X-ray absorption near edge spectra of V, Cr, and Mn-doped glasses indicate that the oxidation states of V(IV, V), Cr(III, VI) and Mn(II, III) exist in the studied glasses. The oxidation states revealed from the diffuse reflectance spectra of the glasses are V(IV, V), Cr(III, VI), Mn(III), Fe(II, III), Co(II), Ni(II), and Cu(II). Most of the 3d transition element ions exhibit strong absorption in the visible spectral region in the glass. Under ultraviolet excitation, the undoped sodium borosilicate glass produces weak and broad emission, while doping of vanadium introduces strong and broad emission due to the V(V) charge transfer transition. Only weak emission is observed from Ti(IV), Mn(II), Fe(III) and Cu(II), partly resulting from the strong electron–phonon coupling of the 3d-electrons and the relatively high phonon energy of the studied glass host, with the former leading to dominant nonradiative relaxation based on multiphonon processes for most of the 3d excited states

  18. GLASS FABRICATION AND PRODUCT CONSISTENCY TESTING OF LANTHANIDE BOROSILICATE FRIT X COMPOSITION FOR PLUTONIUM DISPOSITION

    Energy Technology Data Exchange (ETDEWEB)

    Marra, J

    2006-11-15

    The Department of Energy Office of Environmental Management (DOE/EM) plans to conduct the Plutonium Disposition Project at the Savannah River Site (SRS) to disposition excess weapons-usable plutonium. A plutonium glass waste form is the preferred option for immobilization of the plutonium for subsequent disposition in a geologic repository. A reference glass composition (Lanthanide Borosilicate (LaBS) Frit B) was developed during the Plutonium Immobilization Program (PIP) to immobilize plutonium in the late 1990's. A limited amount of performance testing was performed on this baseline composition before efforts to further pursue Pu disposition via a glass waste form ceased. Recent FY05 studies have further investigated the LaBS Frit B formulation as well as development of a newer LaBS formulation denoted as LaBS Frit X. The objectives of this present task were to fabricate plutonium loaded LaBS Frit X glass and perform corrosion testing to provide near-term data that will increase confidence that LaBS glass product is suitable for disposal in the Yucca Mountain Repository. Specifically, testing was conducted in an effort to provide data to Yucca Mountain Project (YMP) personnel for use in performance assessment calculations. Plutonium containing LaBS glass with the Frit X composition with a 9.5 wt% PuO{sub 2} loading was prepared for testing. Glass was prepared to support Product Consistency Testing (PCT) at Savannah River National Laboratory (SRNL). The glass was thoroughly characterized using x-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) prior to performance testing. A series of PCTs were conducted at SRNL using quenched Pu Frit X glass with varying exposed surface areas. Effects of isothermal and can-in-canister heat treatments on the Pu Frit X glass were also investigated. Another series of PCTs were performed on these different heat-treated Pu Frit X glasses. Leachates from all these PCTs

  19. Optical absorption and gamma-radiation-shielding parameter studies of Tm3+-doped multicomponent borosilicate glasses

    Science.gov (United States)

    Lakshminarayana, G.; Sayyed, M. I.; Baki, S. O.; Lira, A.; Dong, M. G.; Kaky, Kawa M.; Kityk, I. V.; Mahdi, M. A.

    2018-05-01

    Different concentrations (0.1‒2.0 mol%) of Tm3+-doped multicomponent borosilicate glasses with 10 mol% Li2O (alkali) or MgO (alkaline) have been synthesized and their optical absorption and radiation shielding features were studied. For both Li2O and MgO series 0.5 mol% Tm3+-doped glass samples, the evaluated Ωλ ( λ = 2, 4, and 6) Judd-Ofelt (JO) intensity parameters from experimental oscillator strengths were used in estimating the radiative transition probabilities ( A R), branching ratios ( β R), and radiative lifetimes ( τ R) for several emission transitions. Using the XCOM software, the mass attenuation coefficients ( µ/ ρ) for all the fabricated glasses were evaluated within the 0.015‒10 MeV energy range. Also, the ( µ/ ρ) values were calculated at 0.356, 0.662, 1.173, and 1.33 MeV photon energies by MCNP5 simulation code and the results were compared with those obtained by XCOM. The ( µ/ ρ) values for Li2O, as well as MgO series glasses, increase with the addition of Tm2O3 and these values for MgO series glasses are slightly higher with respect to Li2O series glasses. From the ( µ/ ρ) values, effective atomic number ( Z eff), half-value layer (HVL), and mean free path (MFP) were calculated and the HVL and MFP results revealed that high-energy photons have more penetration into a glass sample compared to low-energy photons. Further, geometric progression (GP) fitting method was utilized to calculate the exposure buildup factor (EBF) within the 0.015‒15 MeV energy range. The 2.0 mol% Tm2O3-doped glasses show a better ability to attenuate gamma-rays in comparison to other glass samples, so the addition of Tm2O3 content leads to improvement of the shielding efficiency of the prepared glasses.

  20. Investigation of local environment around rare earths (La and Eu) by fluorescence line narrowing during borosilicate glass alteration

    International Nuclear Information System (INIS)

    Molières, Estelle; Panczer, Gérard; Guyot, Yannick; Jollivet, Patrick; Majérus, Odile; Aschehoug, Patrick; Barboux, Philippe; Gin, Stéphane; Angeli, Frédéric

    2014-01-01

    The local environment of europium in soda-lime borosilicate glasses with a range of La 2 O 3 content was probed by continuous luminescence and Fluorescence Line Narrowing (FLN) to investigate the local environment of rare earth elements in pristine and leached glass. After aqueous leaching at 90 °C at pH 7 and 9.5, rare earths were fully retained and homogeneously distributed in the amorphous alteration layer (commonly called gel). Two separate silicate environments were observed in pristine and leached glasses regardless of the lanthanum content and the leaching conditions. A borate environment surrounding europium was not observed in pristine and leached glasses. During glass alteration, OH groups were located around the europium environment, which became more organized (higher symmetry) in the first coordination shell. -- Highlights: • No borate environment surrounding europium was detected in pristine borosilicate glasses. • Up to 12 mol% of REE2O3 in glass, local environment of europium does not significantly change. • Europium environment becomes more ordered and symmetric in gels than in pristine glasses. • Two distinct silicate sites were observed, as well in pristine glass as in gels (leached glasses). • In altered glasses, OH groups were located around europium

  1. Investigation of local environment around rare earths (La and Eu) by fluorescence line narrowing during borosilicate glass alteration

    Energy Technology Data Exchange (ETDEWEB)

    Molières, Estelle [CEA – DEN-DTCD-LCV-SECM Laboratoire d' études du Comportement à Long Terme, 30207 Bagnols-sur-Cèze (France); Panczer, Gérard; Guyot, Yannick [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne cedex (France); Jollivet, Patrick [CEA – DEN-DTCD-LCV-SECM Laboratoire d' études du Comportement à Long Terme, 30207 Bagnols-sur-Cèze (France); Majérus, Odile; Aschehoug, Patrick; Barboux, Philippe [Laboratoire de Chimie de la Matière Condensée de Paris, UMR-CNRS 7574, École Nationale Supérieure de Chimie de Paris (ENSCP Chimie-ParisTech), 11 rue Pierre et Marie Curie, 75231 Paris (France); Gin, Stéphane [CEA – DEN-DTCD-LCV-SECM Laboratoire d' études du Comportement à Long Terme, 30207 Bagnols-sur-Cèze (France); Angeli, Frédéric, E-mail: frederic.angeli@cea.fr [CEA – DEN-DTCD-LCV-SECM Laboratoire d' études du Comportement à Long Terme, 30207 Bagnols-sur-Cèze (France)

    2014-01-15

    The local environment of europium in soda-lime borosilicate glasses with a range of La{sub 2}O{sub 3} content was probed by continuous luminescence and Fluorescence Line Narrowing (FLN) to investigate the local environment of rare earth elements in pristine and leached glass. After aqueous leaching at 90 °C at pH 7 and 9.5, rare earths were fully retained and homogeneously distributed in the amorphous alteration layer (commonly called gel). Two separate silicate environments were observed in pristine and leached glasses regardless of the lanthanum content and the leaching conditions. A borate environment surrounding europium was not observed in pristine and leached glasses. During glass alteration, OH groups were located around the europium environment, which became more organized (higher symmetry) in the first coordination shell. -- Highlights: • No borate environment surrounding europium was detected in pristine borosilicate glasses. • Up to 12 mol% of REE2O3 in glass, local environment of europium does not significantly change. • Europium environment becomes more ordered and symmetric in gels than in pristine glasses. • Two distinct silicate sites were observed, as well in pristine glass as in gels (leached glasses). • In altered glasses, OH groups were located around europium.

  2. Effects of alpha radiation on hardness and toughness of the borosilicate glass applied to radioactive wastes immobilization

    International Nuclear Information System (INIS)

    Prado, Miguel Oscar; Bernasconi, Norma B. Messi de; Bevilacqua, Arturo Miguel; Arribere, Maria Angelica; Heredia, Arturo D.; Sanfilippo, Miguel

    1999-01-01

    Borosilicate german glass SG7 samples, obtained by frit sintering, were irradiated with different fluences of thermal neutrons in the nucleus of a nuclear reactor. The nuclear reaction 10 B(n,α) 7 Li, where the 10 B isotope is one of the natural glass components, was used to generate alpha particles throughout the glass volume. The maximum alpha disintegration per unit volume achieved was equivalent to that accumulated in a borosilicate glass with nuclear wastes after 3.8 million years. Through Vickers indentations values for microhardness, stress for 50% fracture probability (Weibull statistics) and estimation of the toughness were obtained as a function of alpha radiation dose. Two counterbalanced effects were found: that due to the disorder created by the alpha particles in the glass and that due to the annealing during irradiation (temperature below 240 deg C). Considering the alpha radiation effect, glasses tend decrease Vickers hardness, and to increase thr 50% fracture probability stress with the dose increase. (author)

  3. Preparation and characterization of an improved borosilicate glass matrix for the incorporation of high level radioactive waste (HAW). Pt. 1

    International Nuclear Information System (INIS)

    Guber, W.; Hussain, M.; Kahl, L.; Ondracek, G.; Saidl, J.; Dippel, T.

    1979-08-01

    On the basis of laboratory and technical experience with the preparation and the characterization of borosilicate glasses as solidification matrix for high level radioactive waste solution (HAW), a borosilicate glass composition with optimum properties has been developed. Keeping in view the technical and final storage requirements, a number of glass compositions with varying proportions of influential components as Al, Mg, Na were prepared and thoroughly investigated for certain parameters as specific gravity, thermal conductivity, impact resistance, thermal expansion, viscosity, characteristic temperature points, specific heat, evaporation losses from the melt, electrical conductivity, leach resistance, tendency toward recrystallization and second phase formation. All the compositions (some with different amounts of Gd 2 O 3 , an expected neutron poision) contained 15 wt. % simulated HAW oxides. Samples for investigation were fabricated very close to the actual process conditions of vitrification. Two glass products GP12 and GP26 (3.7% Gd 2 O 3 ) have been selected out of 25 glasses as the optimised products for further thorough investigations. Leach resistance, viscosity at 1420 K, tendency towards recrystallization and second phase formation were the most important deciding factors. (orig.) [de

  4. Jouer du piano

    Directory of Open Access Journals (Sweden)

    Fériel Kaddour

    2011-04-01

    Full Text Available La réflexion s’appuie dans un premier temps sur une opposition entre deux attitudes de pianistes  à l’égard du travail à l’instrument : Gould, qui revendique une séparation d’avec le clavier pour ne privilégier que la lecture; Arrau, dont la technique au contraire vise à « faire corps » avec son piano. L’étude de ces deux démarches d’interprètes conduit à une conclusion croisée : l’abstraction gouldienne n’est rien d’autre qu’un déplacement du jeu vers d’autres instruments (ceux qui servent à la prise de son et au montage de ses enregistrements ; le « faire-corps » hérité de la culture pianistique romantique est plus dialectique que fusionnel, et en cela implique une capacité de mise à distance. A partir de cette double conclusion, on tâche enfin de repenser la place du jeu à l’instrument dans la mise en œuvre d’une interprétation, en interrogeant le dialogue qui s’instaure entre la partition telle qu’elle s’écrit et le geste tel qu’il se joue.Our study leans on an opposition between two pianists' attitudes about their work with the instrument. Gould claims a necessary separation from the keyboard in order to prioritize reading. Arrau, on the contrary, relies on a technique which consists in “being one” with his piano. The analysis of these two interprets’ behaviours leads to a crossed conclusion: the gouldian abstraction is nothing else than a displacement of the playing towards another kind of instruments, the ones he uses in sound recording and cut up; Arrau’s “being one” is more dialectic than at first sight, and it therefore implies a real distancing from the piano. This constatation leads to rethink the place of the piano playing in the setting of an interpretation, and to highlight the real dialogue which develops itself between the score as it has been written and the gesture as it is played.

  5. La grammaticalisation du monde.

    Directory of Open Access Journals (Sweden)

    Etienne Pingaud

    2010-01-01

    Full Text Available Ouvrage atypique par le fond comme par la forme, Le devoir et la grâce rend compte du minutieux travail d’élaboration théorique auquel s’attelle Cyril Lemieux depuis plusieurs années. Et le résultat final se veut pour le moins ambitieux : l’auteur propose un système total supposé dépasser d’un même élan le relativisme, le mentalisme, l’universalisme ethnocentrique, l’historicisme, le naturalisme et l’herméneutisme, tout en réconciliant les sciences sociales avec le ...

  6. Le sacre du printemps

    Directory of Open Access Journals (Sweden)

    Denise Pumain

    2002-03-01

    Full Text Available Cybergeo aura six ans en avril : dans la réalité du virtuel, dans l'univers récent et fluctuant de la publication en ligne, cela fait de nous, tout à la fois, des pionniers et des vétérans. De façon plus surprenante, il se trouve que nous sommes aussi uniques : parmi toutes les revues électroniques de sciences sociales, aucune ne combine comme Cybergeo ancienneté, publication exclusivement électronique, liberté d'accès au texte intégral, édition et gestion par des chercheurs, et comité de lec...

  7. Le Brahmane du Komintern

    Directory of Open Access Journals (Sweden)

    Elizabeth Burgos

    2008-01-01

    Full Text Available Le Brahmane du Komintern, largometraje documental del realizador francés Vladimir León, constituye un ejercicio ejemplar de investigación histórica y  de lograda factura de realización. Y, pese a no haber contado con la ayuda de ninguno organismo público, se trata de un ambicioso proyecto que cubre una amplia extensión geográfica que abarca: Estados Unidos, México, Moscú, Berlín, y la India. Gira en torno a una figura que tuvo en su tiempo su hora de gloria. Un bengalí, hijo de braman, la c...

  8. Corrosion testing of a plutonium-loaded lanthanide borosilicate glass made with Frit B.

    Energy Technology Data Exchange (ETDEWEB)

    Ebert, W. L.; Chemical Engineering

    2006-09-30

    Laboratory tests were conducted with a lanthanide borosilicate (LaBS) glass made with Frit B and added PuO2 (the glass is referred to herein as Pu LaBS-B glass) to measure the dependence of the glass dissolution rate on pH and temperature. These results are compared with the dependencies used in the Defense HLW Glass Degradation Model that was developed to account for HLW glasses in total system performance assessment (TSPA) calculations for the Yucca Mountain repository to determine if that model can also be used to represent the release of radionuclides from disposed Pu LaBS glass by using either the same parameter values that are used for HLW glasses or parameter values specific for Pu LaBS glass. Tests were conducted by immersing monolithic specimens of Pu LaBS-B glass in six solutions that imposed pH values between about pH 3.5 and pH 11, and then measuring the amounts of glass components released into solution. Tests were conducted at 40, 70, and 90 C for 1, 2, 3, 4, and 5 days at low glass-surface-area-to-solution volume ratios. As intended, these test conditions maintained sufficiently dilute solutions that the impacts of solution feedback effects on the dissolution rates were negligible in most tests. The glass dissolution rates were determined from the concentrations of Si and B measured in the test solutions. The dissolution rates determined from the releases of Si and B were consistent with the 'V' shaped pH dependence that is commonly seen for borosilicate glasses and is included in the Defense HLW Glass Degradation Model. The rate equation in that model (using the coefficients determined for HLW glasses) provides values that are higher than the Pu LaBS-B glass dissolution rates that were measured over the range of pH and temperature values that were studied (i.e., an upper bound). Separate coefficients for the rate expression in acidic and alkaline solutions were also determined from the test results to model Pu LaBS-B glass dissolution

  9. (Sorghum bicolor (L.) Moench) du Nord du Burkina Faso

    African Journals Online (AJOL)

    SARAH

    29 déc. 2014 ... sorghos à grains sucrés ont un cycle court et arrivent donc à maturité avant les autres sorghos et le mil d'où leur exploitation comme aliment de soudure par les paysans. L'organisation de la diversité morphologique des accessions de sorghos à grains sucrés du Nord du. Burkina autour principalement des ...

  10. OPERATION DU FOISONNEMENT

    Directory of Open Access Journals (Sweden)

    Gholamreza Djelveh

    2010-04-01

    Full Text Available Mousses alimentaires sont un sous-ensemble des aliments connus sous le nom de produits fouettés ou des produits aérés. Ils sont des produits formulés avec des qualités telles que la légèreté et la souplesse et sont principalement consommés à l'apéritif ou au dessert. Les produits en mousse obtenue par dispersion d'un gaz dans une matrice alimentaire (la phase continue ont connu un développement croissant au cours des années 80 et 90. Le processus d'aération liés à leurs activités de production est appelée l'expansion ou à fouetter. Le document présente les principaux-paramètres du procédé du point permanent de la formulation, la mise en œuvre processus dans les installations pilotes et à l'échelle industrielle, la caractérisation des produits finis, la base énergétique de l'échelle de processus en place, et le lien entre la formulation, émulsion préparation de l'expansion. Cette vue d'ensemble de l'opération d'expansion continue, nous a permis de mettre en évidence le fait qu'il ya des opérations de l'unité encore mal décrite par le génie des procédés et pour lesquels les méthodes et outils pour l'extrapolation et la prédiction sont encore à leurs balbutiements.

  11. Alimentation du nouveau-ne et du nourrisson dans la region ...

    African Journals Online (AJOL)

    Alimentation du nouveau-ne et du nourrisson dans la region centrale du togo : pratiques familiales et communautaires avant la mise en oeuvre de la strategie « prise en charge integree des maladies de l'enfant »

  12. W. E. B. Du Bois: Reform, Will, and the Veil

    Science.gov (United States)

    England, Lynn; Warner, W. Keith

    2013-01-01

    While W. E. B. Du Bois is widely recognized for his contributions to the sociology of race, his contributions to the foundations of sociology are largely ignored. His sociology is based on African American reformism, a version of pragmatism, and a contingent historicism. The basic view of sociology is one that emphasizes the role of chance and…

  13. Titulaires de la bourse du CRDI aux chercheurs candidats au ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Université d'Ottawa, doctorat en développement international. ... The role of traditional actors in taxation in Sierra Leone: Unorthodox public-private ... Abonnez-vous à notre bulletin pour recevoir les nouvelles du CRDI chaque mois. Abonnez- ...

  14. The origin of cholesterol in chyle demonstrated by nuclear indicator methods; Origines du cholesterol du chyle mises en evidence par la methode des indicateurs nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Vyas, M

    1962-07-01

    In order to obtain information about the mechanism of the intestinal absorption of cholesterol, rats having a lymphatic abdominal fistula are used. The animals receive either 4-{sup 14}C- cholesterol subcutaneously or orally, or the 1-{sup 14}C acetate. The study of the specific radio-activities of the cholesterol in chyle, in serum, in the lining, and in the intestinal contents makes it possible to define the roles played by the transfer cholesterol from the serum, by the cholesterol synthesised intestinally, and by the absorption cholesterol, in the formations of the lymph and of the chylomicrons. A new theory is proposed for the mechanism of cholesterol absorption. (author) [French] Pour obtenir des renseignements concernant le mecanisme de l'absorption intestinale du cholesterol, on utilise des rats porteurs d'une fistule lymphatique abdominale. Les animaux recoivent soit du cholesterol 4-{sup 14}C par voie sous-cutanee ou par voie orale, soit de l'acetate 1-{sup 14}C. L'etude des radioactivites specifiques du cholesterol du chyle, du serum, de la paroi et du contenu intestinal permet de preciser les roles joues par le cholesterol de transfert d'origine serique, par le cholesterol de synthese intestinale et par le cholesterol d'absorption, dans la formation de la lymphe et des chylomicrons. Une theorie nouvelle concernant le mecanisme de l'absorption du cholesterol est proposee. (auteur)

  15. Structure, thermal stability and resistance under external irradiation of rare earths and molybdenum-rich alumino-borosilicate glasses

    International Nuclear Information System (INIS)

    Chouard, N.

    2011-01-01

    In France, the highly radioactive nuclear liquid wastes arising from spent nuclear fuel reprocessing (fission products + minor actinides (FPA)) are currently immobilized in an alumino-borosilicate glass called 'R7T7'. In the future, the opportunity of using new alumino-borosilicate glass compositions (HTC glasses) is considered in order to increase the waste loading in glasses and thus significantly decrease the number of glass canisters. However, the increase of the concentration of FPA could lead to the crystallization of rare-earth-rich phases (Ca 2 RE 8 (SiO 4 ) 6 O 2 ) or molybdenum-rich phases (CaMoO 4 , Na 2 MoO 4 ) during melt cooling, which can modify the confinement properties of the glass (chemical durability, self-irradiation resistance..), particularly if they can incorporate radionuclides α or β in their structure. This thesis can be divided into two parts: The first part deals with studying the relationship that can occur between the composition, the structure and the crystallization tendency of simplified seven oxides glasses, belonging to the SiO 2 -B 2 O 3 -Al 2 O 3 -Na 2 O-CaO-MoO 3 -Nd 2 O 3 system and derived from the composition of the HTC glass at 22,5 wt. % in FPA. The impact of the presence of platinoid elements (RuO 2 in our case) on the crystallization of the different phases is also studied. The second part deals with the effect of actinides α decays and more particularly of nuclear interactions essentially coming from recoil nuclei (simulated here by heavy ions external irradiations) on the behaviour under irradiation of an alumino-borosilicate glass containing apatite Ca 2 Nd 8 (SiO 4 ) 6 O 2 crystals, that can incorporate actinides in their structure. Two samples containing apatite crystals with different size are studied, in order to understand the impact of microstructure on the irradiation resistance of this kind of material. (author) [fr

  16. Evaluation de l'oral: les hauts et les bas de l'entrevue et du jeu de role (Oral Evaluation: The Highs and Lows of the Interview and Role-Play).

    Science.gov (United States)

    Berrier, Astrid

    1989-01-01

    The advantages and disadvantages of the use of the oral interview and role-playing to assess communicative competence are outlined. The interview is criticized and deemed an inappropriate form of testing, and it is proposed that role-playing allows better assessment of sociolinguistic competence. Group interaction is suggested as providing another…

  17. Etat Du Magnesium Dans Quelques Sols Sales Du Sud Et Du ...

    African Journals Online (AJOL)

    étude a été réalisée sur 86 échantillons de sols provenant du Centre et du Sud de l´Irak. L\\'expérimentation a consisté, d´une part, à calculer les différents sels dominants dans les sols salés par la méthode de combinaison hypothétique et, ...

  18. Caractérisation des sables et morphologie du fond du lac du ...

    African Journals Online (AJOL)

    Une analyse sédimentologique et minéralogique réalisée sur un cycle hydrologique entre octobre 2004 et août 2005 a permis d\\'évaluer les charges solides en suspension et de caractériser les sédiments du lac du barrage de Taabo. La concentration moyenne en matières en suspension (12 mg.L-1) et la turbidité ...

  19. Caractérisation des sables et morphologie du fond du lac du ...

    African Journals Online (AJOL)

    Administrateur

    Une analyse sédimentologique et minéralogique réalisée sur un cycle hydrologique entre octobre 2004 et août 2005 a permis d'évaluer les charges solides en suspension et de caractériser les sédiments du lac du barrage de Taabo. La concentration moyenne en matières en suspension (12 mg.L-1) et la turbidité ...

  20. Standardization of a PIGE methodology for simultaneous quantification of low Z elements in barium borosilicate glass samples

    International Nuclear Information System (INIS)

    Chhillar, S.; Acharya, R.; Dasari, K.B.; Pujari, P.K.; Mishra, R.K.; Kaushik, C.P.

    2013-01-01

    In order to standardize particle induced gamma-ray emission (PIGE) methodology for simultaneous quantification of light elements, analytical sensitivities of Li, F, B, Na, Al and Si were evaluated using 4 MeV proton beam ( ∼ 10 nA current) using 3 MV Pelletron at IOP, Bhubaneswar. The PIGE method was validated by determining all six elements in a synthetic sample in graphite matrix and applied to two barium borosilicate glass (BaBSG) samples. The prompt γ-rays emitted from inelastic scattering or nuclear reactions of corresponding isotopes were measured using a 60% HPGe coupled to MCA and the current normalized count rates were used for concentration calculation. (author)

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

    International Nuclear Information System (INIS)

    Petit-Maire, D.

    1988-01-01

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

  2. Color-converted remote phosphor prototype of a multiwavelength excitable borosilicate glass for white light-emitting diodes

    International Nuclear Information System (INIS)

    Tian Hua; Qiu Kun; Song Jun; Wang Da-Jian; Liu Ji-Wen

    2012-01-01

    We report a unique red light-emitting Eu-doped borosilicate glass to convert color for warm white light-emitting diodes. This glass can be excited from 394 nm-peaked near ultraviolet light, 466 nm-peaked blue light, to 534 nm-peaked green light to emit the desired red light with an excellent transmission in the wavelength range of 400–700 nm which makes this glass suitable for color conversion without a great cost of luminous power loss. In particular, when assembling this glass for commercial white light-emitting diodes, the tested results show that the color rendering index is improved to 84 with a loss of luminous power by 12 percent at average, making this variety of glass promising for inorganic “remote-phosphor” color conversion

  3. A kinetic model for borosilicate glass dissolution based on the dissolution affinity of a surface alteration layer

    International Nuclear Information System (INIS)

    Bourcier, W.L.; Peiffer, D.W.; Knauss, K.G.; McKeegan, K.D.; Smith, D.K.

    1989-11-01

    A kinetic model for the dissolution of borosilicate glass is used to predict the dissolution rate of a nuclear waste glass. In the model, the glass dissolution rate is controlled by the rate of dissolution of an alkali-depleted amorphous surface (gel) layer. Our model predicts that all components concentrated in the surface layer, affect glass dissolution rates. The good agreement between predicted and observed elemental dissolution rates suggests that the dissolution rate of the gel layer limits the overall rate of glass dissolution. The model predicts that the long-term rate of glass dissolution will depend mainly on ion concentrations in solution, and therefore on the secondary phases which precipitate and control ion concentrations. 10 refs., 5 figs., 1 tab

  4. Investigating the effect of V{sub 2}O{sub 5} addition on sodium barium borosilicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Halder, Rumu, E-mail: rumuhalder24feb@gmail.com; Sengupta, Pranesh; Dey, G. K. [Materials Science Division, Bhabha Atomic Research Centre, Mumbai-700 085 (India); Sudarsan, V. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai-700 085 (India); Kaushik, C. P. [Waste Management Division, Bhabha Atomic Research Centre, Mumbai-700 085 (India)

    2016-05-23

    V{sub 2}O{sub 5} doped sodium barium borosilicate glasses were characterized by photoluminescence spectroscopy and electron probe microanalyzer (EPMA). The glass remains homogeneous for lower concentration of V{sub 2}O{sub 5} but a phase separation is observed when V{sub 2}O{sub 5} doping is increased beyond 5 mol%. Detailed microanalysis reveals that the phase separated glass consists of a phase containing V, Ba and Si and a separate Si rich phase within the glass matrix. The luminescence study demonstrated that at low concentration the vanadium mainly interacts with the structural units of B/Si while at higher concentrations, V-O-V/ V-O{sup −} Na{sup +}/Ba{sup 2+} linkages are formed.

  5. Phase evolution and dielectric properties of MgTi2O5 ceramic sintered with lithium borosilicate glass

    International Nuclear Information System (INIS)

    Shin, Hyunho; Shin, Hee-Kyun; Jung, Hyun Suk; Cho, Seo-Yong; Hong, Kug Sun

    2005-01-01

    Phase evolution, densification, and dielectric properties of MgTi 2 O 5 dielectric ceramic, sintered with lithium borosilicate (LBS) glass, were studied. Reaction between LBS glass and MgTi 2 O 5 was significant in forming secondary phases such as TiO 2 and (Mg,Ti) 2 (BO 3 )O. The glass addition was not necessarily deleterious to the dielectric properties due to the formation of TiO 2 : permittivity increased and temperature coefficient of resonance frequency could be tuned to zero with the addition of LBS glass, although the inevitable glass-induced decrease of quality factor was not retarded by the formation of TiO 2 . The sintered specimen with 10 wt% LBS fired at 950 deg. C for 2 h showed permittivity of 19.3, quality factor of 6800 GHz, and τ f of -16 ppm/ deg. C

  6. Effect of composition and temperature on viscosity and electrical conductivity of borosilicate glasses for Hanford nuclear waste immobilization

    International Nuclear Information System (INIS)

    Hrma, P.; Piepel, G.F.; Smith, D.E.; Redgate, P.E.; Schweiger, M.J.

    1993-04-01

    Viscosity and electrical conductivity of 79 simulated borosilicate glasses in the expected range of compositions to be produced in the Hanford Waste Vitrification Plant were measured within the temperature span from 950 to 1250 degree C. The nine major oxide components were SiO 2 , B 2 O 3 , Li 2 O, Na 2 O, CaO, MgO, Fe 2 O 3 , Al 2 O 3 , and ZrO 2 . The test compositions were generated statistically. The data were fitted by Fulcher and Arrhenius equations with temperature coefficients being multilinear functions of the mass fractions of the oxide components. Mixture models were also developed for the natural logarithm of viscosity and that of electrical conductivity at 1150 degree C. Least squares regression was used to obtain component coefficients for all the models

  7. Le bal du loup

    CERN Multimedia

    Happy Children's Home

    2013-01-01

    The Bord'eau amateur theatre group will graciously perform a play of their creation Le bal du loup Saturday 19 October 2013 at 20:00 Sunday 20 October at 17:00 in the Théâtre des Grottes Rue Louis Favre 43, 1201 Genève Children from age 12 upwards. Summary: The new-elected mayoress of a small village would like to clean up the town by prohibiting alcohol and getting rid of its prostitutes. Then along comes « Massimo Lupo » the pimp... The performances will be given to support the Happy Children's Home charity, which runs a foster-home in Pokhara for Nepali children:  http://www.happychildrenshome.org/ Admission : minimum charge of 10 CHF per person requested, to cover the cost of technical assistance and theatre rental. Any profit will be used solely for the foster-home. At the end of each performance members of the HCH charity will be happy to answer any questions you may have. The theatre has 86 seats, thank you for reserv...

  8. Preparation and nonlinear optical properties of indium nanocrystals in sodium borosilicate glass by the sol–gel route

    International Nuclear Information System (INIS)

    Zhong, Jiasong; Xiang, Weidong; Zhao, Haijun; Chen, Zhaoping; Liang, Xiaojuan; Zhao, Wenguang; Chen, Guoxin

    2012-01-01

    Graphical abstract: The sodium borosilicate glass doped with indium nanocrystals have been successfully prepared by sol–gel methods. And the indium nanocrystals in tetragonal crystal system have formed uniformly in the glass, and the average diameter of indium nanocrystals is about 30 nm. The third-order optical nonlinear refractive index γ, absorption coefficient β, and susceptibility χ (3) of the glass are determined to be −4.77 × 10 −16 m 2 /W, 2.67 × 10 −9 m/W, and 2.81 × 10 −10 esu, respectively. Highlights: ► Indium nanocrystals embedded in glass matrix have been prepared by sol–gel route. ► The crystal structure and composition are investigated by XRD and XPS. ► Size and distribution of indium nanocrystals is determined by TEM. ► The third-order optical nonlinearity is investigated by using Z-scan technique. -- Abstract: The sodium borosilicate glass doped with indium nanocrystals have been successfully prepared by sol–gel route. The thermal stability behavior of the stiff gel is investigated by thermogravimetric (TG) and differential thermal (DTA) analysis. The crystal structure of the glass is characterized by X-ray powder diffraction (XRD). Particle composition is determined by X-ray photoelectron spectroscopy (XPS). Size and distribution of the nanocrystals are characterized by transmission electron microscopy (TEM) as well as high-resolution transmission electron microscopy (HRTEM). Results show that the indium nanocrystals in tetragonal crystal structure have formed in glass, and the average diameter is about 30 nm. Further, the glass is measured by Z-scan technique to investigate the nonlinear optical (NLO) properties. The third-order NLO coefficient χ (3) of the glass is determined to be 2.81 × 10 −10 esu. The glass with large third-order NLO coefficient is promising materials for applications in optical devices.

  9. 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)

  10. Utilization of Cs137 to generate a radiation barrier for weapons grade plutonium immobilized in borosilicate glass canisters. Revision 1

    International Nuclear Information System (INIS)

    Jardine, L.J.; Armantrout, G.A.; Collins, L.F.

    1995-01-01

    One of the ways recommended by a recent National Academy of Sciences study to dispose of excess weapons-grade plutonium is to encapsulate the plutonium in a glass in combination with high-level radioactive wastes (HLW) to generate an intense radiation dose rate field. The objective is to render the plutonium as difficult to access as the plutonium contained in existing US commercial spent light-water reactor (LWR) fuel until it can be disposed of in a permanent geological repository. A radiation dose rate from a sealed canister of 1,000 rem/h (10 Sv/h) at 1 meter for at least 30 years after fabrication was assumed in this paper to be a radiation dose comparable to spent LWR fuel. This can be achieved by encapsulating the plutonium in a borosilicate glass with an adequate amount of a single fission product in the HLWS, namely radioactive Cs 137 . One hundred thousand curies of Cs 137 will generate a dose rate of 1,000 rem/h (10 Sv/h) at 1 meter for at least 30 years when imbedded into canisters of the size proposed for the Savannah River Site's vitrified high-level wastes. The United States has a current inventory of 54 MCi of CS 137 that has been separated from defense HLWs and is in sealed capsules. This single curie inventory is sufficient to spike 50 metric tons of excess weapons-grade plutonium if plutonium can be loaded at 5.5 wt% in glass, or 540 canisters. Additional CS 137 inventories exist in the United States' HLWs from past reprocessing operations, should additional curies be required. Using only one fission product, CS 137 , rather than the multiple chemical elements and compounds in HLWs to generate a high radiation dose rate from a glass canister greatly simplifies the processing engineering retirement for encapsulating plutonium in a borosilicate glass

  11. Raman and X-ray absorption spectroscopic studies of hydrothermally altered alkali-borosilicate nuclear waste glass

    Energy Technology Data Exchange (ETDEWEB)

    McKeown, David A., E-mail: davidm@vsl.cua.ed [Vitreous State Laboratory, Catholic University of America, 620 Michigan Ave., N.E., Washington, DC 20064 (United States); Buechele, Andrew C.; Viragh, Carol; Pegg, Ian L. [Vitreous State Laboratory, Catholic University of America, 620 Michigan Ave., N.E., Washington, DC 20064 (United States)

    2010-04-01

    Raman spectroscopy and X-ray absorption spectroscopy (XAS) are used to characterize structural changes that took place in hydrothermally altered (Na,K)-alumina-borosilicate glasses with different Na/K ratios, formulated as part of a durability study to investigate the behavior of glasses for nuclear waste storage. The hydrothermal experiments, or vapor hydration tests (VHT), were performed on each glass for 3 and 20 days at 200 deg. C to accelerate and approximate long-term alteration processes that may occur in a nuclear waste repository. Results found for both glasses and their VHT altered counterparts show little, if any, structural influence from the different starting Na/K ratios. X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, and Raman spectroscopy indicate that the altered samples are mostly amorphous with small amounts of analcime-like and leucite-like crystals within 200 mum of the sample surface and contain up to 9.7 wt.% water or OH. The Raman data are nearly identical for the amorphous portions of all altered VHT samples investigated, and indicate that two glass structural changes took place during alteration: one, partial depolymerization of the alumina-borosilicate network, and two, introduction of water or OH. Al and Si XAS data indicate tetrahedral AlO{sub 4} and SiO{sub 4} environments in the original glasses as well as in the altered samples. Small energy shifts of the Si K-edge also show that the altered VHT samples have less polymerized networks than the original glass. Na XAS data indicate expanded Na environments in the VHT samples with longer Na-O distances and more nearest-neighbor oxygen atoms, compared with the original glasses, which may be due to hydrous species introduced into the expanding Na-sites.

  12. Reinforcement of poly-l-lactic acid electrospun membranes with strontium borosilicate bioactive glasses for bone tissue engineering.

    Science.gov (United States)

    Fernandes, João S; Gentile, Piergiorgio; Martins, Margarida; Neves, Nuno M; Miller, Cheryl; Crawford, Aileen; Pires, Ricardo A; Hatton, Paul; Reis, Rui L

    2016-10-15

    Herein, for the first time, we combined poly-l-lactic acid (PLLA) with a strontium borosilicate bioactive glass (BBG-Sr) using electrospinning to fabricate a composite bioactive PLLA membrane loaded with 10% (w/w) of BBG-Sr glass particles (PLLA-BBG-Sr). The composites were characterised by scanning electron microscopy (SEM) and microcomputer tomography (μ-CT), and the results showed that we successfully fabricated smooth and uniform fibres (1-3μm in width) with a homogeneous distribution of BBG-Sr microparticles (bone marrow-derived mesenchymal stem cells (BM-MSCs) demonstrated that PLLA-BBG-Sr membranes promoted the osteogenic differentiation of the cells as demonstrated by increased alkaline phosphatase activity and up-regulated osteogenic gene expression (Alpl, Sp7 and Bglap) in relation to PLLA alone. These results strongly suggest that the composite PLLA membranes reinforced with the BBG-Sr glass particles have potential as an effective biomaterial capable of promoting bone regeneration. PLLA membranes were reinforced with 10% (w/w) of strontium-bioactive borosilicate glass microparticles, and their capacity to induce the osteogenic differentiation of bone marrow mesenchymal stem cells (BM-MSCs) was evaluated. These membranes presented an increased: degradability, water uptake, Young modulus and tensile strength. We also demonstrated that these membranes are non-cytotoxic and promote the attachment of BM-MSCs. The addition of the glass microparticles into the PLLA membranes promoted the increase of ALP activity (under osteogenic conditions), as well as the BM-MSCs osteogenic differentiation as shown by the upregulation of Alpl, Sp7 and Bglap gene expression. Overall, we demonstrated that the reinforcement of PLLA with glass microparticles results in a biomaterial with the appropriate properties for the regeneration of bone tissue. Copyright © 2016 Acta Materialia Inc. All rights reserved.

  13. Alpha radiation and in-pile annealing effects on the fracture properties of a sintered alumino borosilicate glass

    International Nuclear Information System (INIS)

    Bevilacqua, Arturo M.; Prado, Miguel O.; Messi de Bernasconi, Norma B.; Heredia, Arturo D.; Sanfilippo, Miguel

    1999-01-01

    The alpha radiation and the in-pile during irradiation effects on the hardness, the crack nucleation and the fracture toughness of the German alumino borosilicate glass SG7 were investigated by using the Vickers indentation. Cold pressed and sintered samples were irradiated with thermal neutrons, in the Argentine nuclear reactors RA-3 and RA-6, to produce alpha particles in the whole volume of the glass by means of the (n, alpha)-reaction with B-10. The Vickers hardness, the crack nucleation, as 50 percent fracture probability load, plotted as the Weibull's fracture probability distribution function and the fracture toughness, as critical stress intensity factor K Ic , were correlated to the four cumulative disintegration values. It was ascertained that: a) the Vickers hardness decreases from 5.6 GPa for the non-irradiated sample up to 4.7 GPa for the sample irradiated 70 h at the lower neutron flux (4.0 x 10 - sup 18 - alpha disintegration per cm - sup 3 -), b) the 50 % fracture probability load increases from 1.4 N for the non-irradiated sample up to 4.7 g for the sample irradiated 22 h at the higher flux (6.8 x 10 - sup 18 - alpha disintegration per cm - sup 3 -), and c) the stress intensity factor increases from 0.80 MPa.m - sup 1/2 - for the non irradiated sample up to 0.86 MPa.m - sup 1/2 - for the sample mentioned in b). The in-pile annealing was analyzed by comparing the crack nucleation after irradiation with data obtained by heavy ion irradiation followed by thermal annealing. Results for the SG7 glass were compared to those for soda-lime and borosilicate glasses. (author)

  14. Upconversion studies of Er3+/Yb3+ doped SrO.TiO2 borosilicate glass ceramic system

    International Nuclear Information System (INIS)

    Maheshwari, Aditya; Om Prakash; Kumar, Devendra; Rai, S.B.

    2011-01-01

    Upconversion behaviour has been studied in various matrices and fine powders of SrTiO 3 by previous workers. In present work, Er 3+ /Yb 3+ were doped in appropriate ratio in SrO.TiO 2 borosilicate glass ceramic system to study the upconversion phenomenon. Dielectric properties of this class of glass ceramic system have been extensively investigated by Thakur et al. It has been observed that both upconversion efficiency and dielectric constant increases with transformation of glass into glass ceramic. Therefore, present investigation is based upon the study of optical as well as the electrical properties of same glass ceramic system. In order to prepare different crystalline matrices, two different Er 3+ /Yb 3+ :SrO.TiO 2 borosilicate glasses with same amount of Er 2 O 3 and Yb 2 O 3 were prepared by melt quench method. Glasses were transparent with light-wine colour. Glass ceramics were prepared from the glasses by heat treatment based on DTA (Differential thermal analysis) results. Glass ceramics were fully opaque with brownish-cream colour. Powder X-ray diffraction (XRD) patterns confirmed that two different crystalline matrices, Sr 3 Ti 2 O 7 , Ti 10 O 19 and SrTiO 3 , TiO 2 were present in two glass ceramic samples respectively. Luminescence properties of glass and glass ceramic samples with 976nm laser irradiation showed that the intensities of the green and red emission increased multiple times in glass ceramic than that of the glass. Possible mechanisms responsible for upconversion eg. Energy Transfer (ET) and Excited State Absorption (ESA), were studied through laser pumping power log dependence

  15. Effets de la microdose sur la production du niébé, du mil et du ...

    African Journals Online (AJOL)

    Effets de la microdose sur la production du niébé, du mil et du sorgho en fonction la toposéquence. Fatimata Saba, Sibiri Jean Baptiste Taonda, Idriss Serme, Alimata A. Bandaogo, Augustin P. Sourwema, Adama Kabre ...

  16. Dynamique des populations du foreur des tiges du cacaoyer ...

    African Journals Online (AJOL)

    SARAH

    30 nov. 2014 ... déprédateur dans la région du Haut-Sassandra, la deuxième plus grande région de production de cacao en. Côte d'ivoire. Méthodologie et résultats : L'étude a été réalisée de 2009 à 2013 dans les plantations villageoises de la région du Haut-Sassandra en Côte d'Ivoire. Les variations des taux d'attaques ...

  17. Dynamique des populations du foreur des tiges du cacaoyer ...

    African Journals Online (AJOL)

    Objectif : Le foreur de tiges du cacaoyer, Eulophonotus myrmeleon Felder cause aujourd'hui d'énormes dégâts dans les cacaoyères ivoiriennes. La présente étude vise à déterminer les périodes de fortes attaques de ce déprédateur dans la région du Haut-Sassandra, la deuxième plus grande région de production de ...

  18. Gestion durable du paysage

    Directory of Open Access Journals (Sweden)

    Jean-David Gerber

    2009-03-01

    Full Text Available Le paysage est de plus en plus perçu comme une ressource. À ce titre, il est nécessaire de trouver des instruments juridiques, politiques ou économiques susceptibles de gérer cette « ressource-paysage » sur le long terme. Le gouvernement suisse a introduit récemment l’instrument des parcs naturels régionaux, organisés selon le modèle français, dans sa législation de protection de la nature et du paysage. Une mise en regard des nouveaux parcs avec des structures de gestion beaucoup plus anciennes, les bourgeoisies et les corporations, permet de mettre en évidence les forces et les faiblesses de chacun de ces instruments dans leur contribution à résoudre les rivalités d’usage entre acteurs utilisant ou influençant la ressource paysage. Cette comparaison permet de formuler des recommandations pratiques concernant la gestion de cette ressource.The landscape is increasingly perceived as a resource. For this reason, it is necessary to find legal, political and economic instruments that will succeed in managing this “resource landscape” in the long term. The Swiss government recently introduced the instrument of regional nature parks into the legislation governing nature and landscape preservation; the proposed parks are organized on the basis of the French model. The examination of the new parks from the perspective of much older management structures, i.e. the civic municipalities (bourgeoisies and corporations, makes it possible to demonstrate the strengths and weaknesses of each of these instruments in their contribution to the resolution of use rivalries between actors who use or influence the resource landscape. This comparison also enables the formulation of practical recommendations regarding the management of this resource.

  19. Le Developmental Entrepreneurship Program du Massachusetts ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Faire en sorte que les étudiants venant des pays en développement pour étudier au MIT retournent ensuite dans leurs pays respectifs afin d'y concrétiser leurs idées est un souci majeur du MIT, des bailleurs de fonds et du milieu du développement. Ce projet palliera à ce souci en soutenant la formation des fellows du ...

  20. Acquisition of rheological and calorimetric properties of borosilicate glass to determine the free energy of formation

    International Nuclear Information System (INIS)

    Linard, Y.; Advocat, Th.

    2000-01-01

    No fundamental thermodynamic data, such as the entropy Δ f S T) and enthalpy Δ f H T) of formation are currently available for nuclear borosilicate glasses. They are necessary to assess the glass thermodynamic stability in water, one of the most important potential long-term glass alteration vectors. Three glass composition ranges were investigated: - 8 compositions ranging from a ternary B 2 O 3 -SiO 2 --Na 2 O (BSN) glass to the simulated SON 68 industrial glass for containment of high active nuclear wastes after reprocessing spent uranium oxide fuel from light water reactors. The basic BSN glass was gradually modified with the additives: Al 2 O 3 , CaO, ZrO 2 , Ce 2 O 3 , Li 2 O and Fe 2 O 3 , and non-radioactive surrogate fission product oxides. - A second using another BSN ternary glass to which Al 2 O 3 , MgO and a group of non-radioactive surrogate fission product oxides, representative of natural uranium GCR fuel, were added. - A third range consisting of various BSN ternary glass compositions. All the glass specimens were fabricated by melting the oxides, carbonates anal nitrates at 1273 to 1473 K in a platinum crucible. Experimental methods based on calorimetry and viscosimetry techniques were used to determine the heat capacity Cp of each glass composition, a necessary parameter in addition to the known heat capacities of the basic glass component oxides, for calculating Δ f S T) and Δ f S T). The heat capacity Cp was measured between 273 K and 1480 K through a combination of three experimental devices: a low-temperature adiabatic calorimeter, a differential scanning calorimeter, and an ice calorimeter. The glass configuration entropy S conf (T g ) necessary to obtain the glass entropy of formation (Eqn.(3)) was determined from tile glass rheological properties. A low-temperature viscosimeter was used to measure the strain ε of a glass specimen subjected to a given uniaxial stress σ to determine the viscosity η. A Couette viscosimeter was used to

  1. VARIABILITY STUDY TO DETERMINE THE SOLUBILITY OF IMPURITIES IN PLUTONIUM-BEARING, LANTHANIDE BOROSILICATE GLASS

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K; Elizabeth Hoffman, E; Charles Crawford, C; Tommy Edwards, T; David Best, D; James Marra, J

    2007-09-26

    This study focuses on the development of a compositional envelope that describes the retention of various impurities in lanthanide borosilicate (LaBS) glass for vitrification and immobilization of excess, defense-related plutonium. A limited amount of impurity data for the various plutonium sources is available and projections were made through analysis of the available information. These projections were used to define types and concentrations of impurities in the LaBS glass compositions to be fabricated and tested. Sixty surrogate glass compositions were developed through a statistically designed approach to cover the anticipated ranges of concentrations for several impurity species expected in the plutonium feeds. An additional four glass compositions containing actual plutonium oxide were selected based on their targeted concentrations of metals and anions. The glasses were fabricated and characterized in the laboratory and shielded cells facility to determine the degree of retention of the impurity components, the impact of the impurities on the durability of each glass, and the degree of crystallization that occurred, both upon quenching and slow cooling. Overall, the LaBS glass system appears to be very tolerant of most of the impurity types and concentrations projected in the plutonium waste stream. For the surrogate glasses, the measured CuO, Ga{sub 2}O{sub 3}, Na{sub 2}O, NiO, and Ta{sub 2}O{sub 5} concentrations fell very close to their target values across the ranges of concentrations targeted in this study for each of these components. The measured CaO and PbO concentrations were consistently higher than the targeted values. The measured Cr{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} concentrations were very close to the targets except for the one highest targeted value for each of these components. A solubility limit may have been approached in this glass system for K{sub 2}O and MgO. The measured Cl{sup -}, F{sup -}, SeO{sub 2} and SO{sub 4}{sup 2

  2. Les dispositifs du Net art

    OpenAIRE

    Fourmentraux, Jean-Paul

    2010-01-01

    La pratique du Net art radicalise la question du potentiel communicationnel d’un média —Internet— qui constitue tout à la fois le support technique, l’outil créatif et le dispositif social de l’œuvre. Les technologies de l’information et de la communication (TIC) placent en effet l’œuvre d’art au cœur d’une négociation socialement distribuée entre l’artiste et le public. L’article est focalisé sur cette construction collective du Net art et sur ses mises en scènes. Il montre le travail artist...

  3. L'administration du travail et la production du droit du travail (1906-1960). : Note de synthèse du rapport de recherche

    OpenAIRE

    Le Crom , Jean-Pierre

    2007-01-01

    Synthèse d'un rapport de recherche dont l'objectif est d'appréhender le rôle de l'administration centrale du travail dans la production du droit du travail. Deux dimensions sont explorées : le profil des rédacteurs et l'organisation des structures.

  4. La percezione del ruolo materno in madri detenute/La perception du rôle maternel chez les mères détenues/The Perception Incarcerated Mothers' Maternal role

    Directory of Open Access Journals (Sweden)

    Agostini Francesca

    2011-12-01

    Full Text Available Nel panorama nazionale ed internazionale non si discute ancora abbastanza della maternità vissuta in carcere, tuttavialargamente diffusa e quindi tema che merita opportuni approfondimenti al fine di promuovere la ricerca di strategie chegarantiscano il diritto della donna detenuta ad essere madre e il diritto dei figli a non essere privati di questo legame.Questo studio esplorativo, svolto presso la Casa Circondariale “Dozza” di Bologna, nella sezione femminile, ha avutocome obiettivo quello di indagare le caratteristiche della percezione del ruolo materno in donne detenute che non vivonocon il proprio figlio. Attraverso le interviste e l’uso di strumenti standardizzati, si è approfondito il tipo di maternitàesperita dalle donne e le difficoltà personali che la lontananza e l’ambiente frappongono alla possibilità di svolgereadeguatamente il proprio ruolo genitoriale. Pur essendo piccolo il campione, le indagini qualitative hanno consentito dievidenziare un quadro di consistente sofferenza, con utilizzo di meccanismi difensivi quali processi di idealizzazionedell’esperienza di maternità e di razionalizzazione.RésuméDans le panorama national et international, on ne discute pas encore assez de la maternité vécue en prison. Toutefois,celle-ci est largement répandue. Partant, il s’agit d’un thème qui mérite d’être approfondi afin de promouvoir larecherche de stratégies qui garantissent le droit de la femme détenue à être mère et le droit des enfants à ne pas êtreprivés de ce lien.Cette étude - réalisée dans le quartier pour femmes de la maison d’arrêt "Dozza" de Bologne - a eu comme objectifd’analyser les caractéristiques de la perception du rôle maternel chez les femmes détenues qui ne vivent pas avec leurspropres enfants. À travers les entretiens et l'usage d'instruments standardisés, nous avons approfondi le type dematernité vécue par ces femmes et les difficultés personnelles que l

  5. Réflexion sur l’origine du processus de segmentation du marche du travail

    Directory of Open Access Journals (Sweden)

    Attia Nicole

    2006-01-01

    Full Text Available (francuski Ce travail propose une réflexion sur l'origine du processus de segmentation du marché du travail par rapport à l'entreprise. Se situe-t-elle au sein même de l'entreprise ou en amont, c'est à dire entre les entreprises? Cela revient à se demander si on peut avoir une approche microéconomique ou macroéconomique de la segmentation et, à s'interroger sur le rôle réel tenu par les firmes dans le processus. Déterminant pour la théorie, ce rôle est à repenser selon la réponse apportée à notre question.

  6. RHENIUM SOLUBILITY IN BOROSILICATE NUCLEAR WASTE GLASS IMPLICATIONS FOR THE PROCESSING AND IMMOBILIZATION OF TECHNETIUM-99 (AND SUPPORTING INFORMATION WITH GRAPHICAL ABSTRACT)

    Energy Technology Data Exchange (ETDEWEB)

    AA KRUGER; A GOEL; CP RODRIGUEZ; JS MCCLOY; MJ SCHWEIGER; WW LUKENS; JR, BJ RILEY; D KIM; M LIEZERS; P HRMA

    2012-08-13

    The immobilization of 99Tc in a suitable host matrix has proved a challenging task for researchers in the nuclear waste community around the world. At the Hanford site in Washington State in the U.S., the total amount of 99Tc in low-activity waste (LAW) is {approx} 1,300 kg and the current strategy is to immobilize the 99Tc in borosilicate glass with vitrification. In this context, the present article reports on the solubility and retention of rhenium, a nonradioactive surrogate for 99Tc, in a LAW sodium borosilicate glass. Due to the radioactive nature of technetium, rhenium was chosen as a simulant because of previously established similarities in ionic radii and other chemical aspects. The glasses containing target Re concentrations varying from 0 to10,000 ppm by mass were synthesized in vacuum-sealed quartz ampoules to minimize the loss of Re by volatilization during melting at 1000 DC. The rhenium was found to be present predominantly as Re7 + in all the glasses as observed by X-ray absorption near-edge structure (XANES). The solubility of Re in borosilicate glasses was determined to be {approx}3,000 ppm (by mass) using inductively coupled plasma-optical emission spectroscopy (ICP-OES). At higher rhenium concentrations, some additional material was retained in the glasses in the form of alkali perrhenate crystalline inclusions detected by X-ray diffraction (XRD) and laser ablation-ICP mass spectrometry (LA-ICP-MS). Assuming justifiably substantial similarities between Re7 + and Tc 7+ behavior in this glass system, these results implied that the processing and immobilization of 99Tc from radioactive wastes should not be limited by the solubility of 99Tc in borosilicate LAW glasses.

  7. Linear thermal expansion coefficient (at temperatures from 130 to 800 K) of borosilicate glasses applicable for coupling with silicon in microelectronics

    OpenAIRE

    Sinev, Leonid S.; Petrov, Ivan D.

    2017-01-01

    Processing results of measurements of linear thermal expansion coefficients and linear thermal expansion of two brands of borosilicate glasses --- LK5 and Borofloat 33 --- are presented. The linear thermal expansion of glass samples have been determined in the temperature range 130 to 800 K (minus 143 to 526 $\\deg$C) using thermomechanical analyzer TMA7100. Relative imprecision of indirectly measured linear thermal expansion coefficients and linear thermal expansion of both glass brands is le...

  8. 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)

  9. Un Nouveau Monde du Savoir

    International Development Research Centre (IDRC) Digital Library (Canada)

    Si les effets de la mondialisation sur l'économie, la politique ou encore les ..... Il souligne l'importance cruciale d'un plan stratégique d'internationalisation, ...... Lors du recrutement de nouveaux professeurs ( lorsque cette situation est ...

  10. rive gauche du fleuve Rimac

    International Development Research Centre (IDRC) Digital Library (Canada)

    tégée du fleuve et les terrains vagues d'une zone industrielle. .... Ces deux diagnostics sont d'importants outils qui contri- bueront à une meilleure planification ... conditions et instruments nécessaires pour améliorer la situation financière des ...

  11. Voorwoord Forward | du Plessis | Lexikos

    African Journals Online (AJOL)

    J.CM.D. du Plessis. Abstract. No Abstract. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More about AJOL · AJOL's Partners · Terms and Conditions ...

  12. Charte du Conseil des Gouverneurs

    International Development Research Centre (IDRC) Digital Library (Canada)

    Office 2004 Test Drive User

    7. favoriser des communications ouvertes et franches entre le personnel, la direction ..... de dresser le procès-verbal des réunions du Conseil et de ses comités et de veiller à ce ... et des résultats qu'il obtient, et non de sa gestion quotidienne.

  13. Bases biologiques du comportement social

    CERN Document Server

    Laborit, H

    1994-01-01

    Pour bien comprendre le comportement humain dans un environnement social,il est necessaire de comprendre comment fonctionne le systÂ?me nerveux central. L'une des principales fonctions du cerveau est de crÂ?er des relations entre leshumains.. .................

  14. Determination of the free enthalpies of formation of borosilicate glasses; Determination des enthalpies libres de formation des verres borosilicates. Application a l'etude de l'alteration des verres de confinement de dechets radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Linard, Y

    2000-07-01

    This work contributes to the study of the thermochemical properties of nuclear waste glasses. Results are used to discuss mechanisms and parameters integrated in alteration models of conditioning materials. Glass is a disordered material defined thermodynamically as a non-equilibrium state. Taking into account one order parameter to characterise its configurational state, the metastable equilibrium for the glass was considered and the main thermochemical properties were determined. Calorimetric techniques were used to measure heat capacities and formation enthalpies of borosilicate glasses (from 3 to 8 constitutive oxides). Formation Entropies were measured too, using the entropy theory of relaxation processes proposed by Adam and Gibbs (1965). The configurational entropy contribution were determined from viscosity measurements. This set of data has allowed the calculation of Gibb's free energies of dissolution of glasses in pure water. By comparison with leaching experiments, it has been demonstrated that the decreasing of the dissolution rate at high reaction progress cannot be associated to the approach of an equilibrium between the sound glass and the aqueous solution. The composition changes of the reaction area at the glass surface need to be considered too. To achieve a complete description of the thermodynamic stability, the equilibrium between hydrated de-alkalinized glass and/or the gel layer with the aqueous solution should also be evaluated. (author)

  15. 3 and 4 oxidation state element solubilities in borosilicate glasses. Implement to actinides in nuclear glasses; Solubilite des elements aux degres d'oxydation (3) et (4) dans les verres de borosilicate. Application aux actinides dans les verres nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Cachia, J.N

    2005-12-15

    In order to ensure optimal radionuclides containment, the knowledge of the actinide loading limits in nuclear waste glasses and also the comprehension of the solubilization mechanisms of these elements are essential. A first part of this manuscript deals with the study of the differences in solubility of the tri and tetravalent elements (actinides and surrogates) particularly in function of the melting temperature. The results obtained indicate that trivalent elements (La, Gd, Nd, Am, Cm) exhibit a higher solubility than tetravalent elements (Hf, Th, Pu). Consequently, it was planned to reduce plutonium at the oxidation state (III), the later being essentially tetravalent in borosilicate glasses. An innovating reduction process of multi-valent elements (cerium, plutonium) using silicon nitride has been developed in a second part of this work. Reduced plutonium-bearing glasses synthesized by Si{sub 3}N{sub 4} addition made it possible to double the plutonium solubility from 2 to 4 wt% at 1200 deg C. A structural approach to investigate the differences between tri and tetravalent elements was finally undertaken. These investigations were carried out by X-rays Absorption Spectroscopy (EXAFS) and NMR. Trivalent rare earth and actinide elements seem to behave as network modifiers while tetravalent elements rather present true intermediaries' behaviour. (author)

  16. Study of the role of film flows in three-phase displacement mechanisms in porous media; Etude du role des ecoulements par film dans les mecanismes de deplacement triphasique en milieux poreux

    Energy Technology Data Exchange (ETDEWEB)

    Bataillon, D

    1996-12-11

    The determination of the role of liquid films in three phase flows in porous media is very important for enhanced oil recovery by gas injection in a petroleum reservoir. The existence of liquid films (water, oil), their thickness and their stability, control the distribution of fluids and the displacement of these fluids in the reservoir. The target of this research is to obtain, from experimental observations, the microscopic rules of flow by films taking into account the elementary mechanisms controlling the displacement of fluids. For this, a method of liquid film flow thickness measurement is developed in a quartz Hele-Shaw cell. It is based on infrared spectrometry, used for the first time to our knowledge for such an application, which gives the possibility to follow the drainage kinetics of oil and water in the presence of gas. When the thick oil film is initially stable on water in the presence of gas, it slowly drains until it reaches a constant thickness of about 20 nm. This film may breaks down into micro droplets of less than few micrometers in diameter. When this thick oil film is not initially stable, it immediately breaks down into droplets of 10 to 20 {mu}m in diameter prevents any oil flow. For spreading conditions, the initial oil thickness of about 200 nm is calculated form the Ca capillary number. The flow kinetics of this film is then determined when macroscopic forces are predominant. Finally, for the estimation of the stabilisation thickness, disjoining pressure isotherms, based on long-scale intermolecular forces (VdW), are calculated for pure n-alkanes. In order to study the macroscopic flow parameters, gravity drainage experiments are carried out in a 2D glass network (micro-model). Measurements of oil production (weight) and residual saturations (image analysis) show clearly the influence of the initial stability of oil, coating water in the presence of gas, on the flow mechanisms. (author) 73 refs.

  17. Contribution to the study of the role of sulfate-reducing bacteria in bio-corrosion phenomenon; Contribution a l'etude du role des bacteries sulfato-reductrices dans les phenomenes de biocorrosion

    Energy Technology Data Exchange (ETDEWEB)

    Chatelus, C

    1987-11-15

    By their metabolic activities of hydrogen consumption and of sulfides production, the sulfate-reducing bacteria are the main bacteria responsible of the metallic corrosion phenomena in the absence of oxygen. A physiological and enzymatic study of some Desulfovibrio has contributed to the understanding of the role of these bacteria in the anaerobic bio-corrosion phenomena. Desulfovibrio (D.) vulgaris in organic medium, after having oxidized the lactate, consumes the hydrogen formed by the electrochemical reaction of iron dissolution. The Desulfovibrio can be responsible either of a corrosion by a direct contact with the metal in using the H{sub 2} layer formed at its surface, (bacteria are then adsorbed at the surface because of an iron sulfide crystalline lattice), or of a distant corrosion in consuming the dissolved or gaseous hydrogen. As their hydrogenases can be stable in time independently of the cellular structure (D. vulparis) and active at high temperatures (to 70 C - 75 C) (D. baculatus), these bacteria can act in conditions incompatible with the viability of cells but compatible with the enzymatic expression. A study in terms of temperature has shown that inside the mesophilic group of the Desulfovibrio, the behaviour towards this parameter is specific to each bacteria, that accounts for the permanent presence of the representatives of this population in sites where the temperature variations are important. A change of some degrees Celsius can induce modifications in the yields of bacteria growth and by a consequence in variations in the corrosion intensity. Moreover, sulfate D. multispirans can reduce with specific velocities of different growth, the nitrate, the nitrite and the fumarate. Some sulfato-reducing could then adapt themselves to the variations of concentrations in electron acceptors and metabolize the oxidized substances used as biocides too. The choice of an electron acceptor rather than another do not depend uniquely of the specificity of

  18. Contribution to the study of the role of sulfate-reducing bacteria in bio-corrosion phenomenon; Contribution a l'etude du role des bacteries sulfato-reductrices dans les phenomenes de biocorrosion

    Energy Technology Data Exchange (ETDEWEB)

    Chatelus, C

    1987-11-15

    By their metabolic activities of hydrogen consumption and of sulfides production, the sulfate-reducing bacteria are the main bacteria responsible of the metallic corrosion phenomena in the absence of oxygen. A physiological and enzymatic study of some Desulfovibrio has contributed to the understanding of the role of these bacteria in the anaerobic bio-corrosion phenomena. Desulfovibrio (D.) vulgaris in organic medium, after having oxidized the lactate, consumes the hydrogen formed by the electrochemical reaction of iron dissolution. The Desulfovibrio can be responsible either of a corrosion by a direct contact with the metal in using the H{sub 2} layer formed at its surface, (bacteria are then adsorbed at the surface because of an iron sulfide crystalline lattice), or of a distant corrosion in consuming the dissolved or gaseous hydrogen. As their hydrogenases can be stable in time independently of the cellular structure (D. vulparis) and active at high temperatures (to 70 C - 75 C) (D. baculatus), these bacteria can act in conditions incompatible with the viability of cells but compatible with the enzymatic expression. A study in terms of temperature has shown that inside the mesophilic group of the Desulfovibrio, the behaviour towards this parameter is specific to each bacteria, that accounts for the permanent presence of the representatives of this population in sites where the temperature variations are important. A change of some degrees Celsius can induce modifications in the yields of bacteria growth and by a consequence in variations in the corrosion intensity. Moreover, sulfate D. multispirans can reduce with specific velocities of different growth, the nitrate, the nitrite and the fumarate. Some sulfato-reducing could then adapt themselves to the variations of concentrations in electron acceptors and metabolize the oxidized substances used as biocides too. The choice of an electron acceptor rather than another do not depend uniquely of the specificity of

  19. Paul Celan in Translation: "Du sei wie du"

    Directory of Open Access Journals (Sweden)

    John Felstiner

    1983-09-01

    Full Text Available Translating the lyric poetry of Paul Celan, especially his later poems, carries not only the endemic challenge and difficulty of any verse translation, but the added incentive of doing justice to a writer whose whole recourse after the Holocaust—whose sanctuary, if he was to have any at all—he sought in language itself, specifically in the Muttersprache , the mother tongue that was as well the tongue of those who murdered his mother and father. This essay exposes a process of translating "Du sei wie du" (1970, which perhaps more than any other poem by Celan, at once solicits and defies translation, moving as it does from modern to medieval German, and closing with Hebrew words from Isaiah— a messianic imperative that shows Celan verging as ever on his Jewish identity.

  20. Le parcours migratoire de jeunes ruraux du bled du kif

    Directory of Open Access Journals (Sweden)

    Khalid Mouna

    2015-06-01

    Full Text Available Cet article analyse le parcours migratoire des jeunes ruraux originaires des zones de production du cannabis, jeunes qui cherchent à briser les chaînes de soumission et d’humiliation vécues au quotidien. Pour les jeunes concernés par notre étude, la migration constitue un moyen de s’intégrer dans des réseaux transnationaux et ainsi d’entamer une carrière de beznass (commerçant du cannabis. Ce parcours « initiatique » permet à ces jeunes de revenir au bled avec de nouvelles idées, des moyens accrus, et de jouer un rôle actif dans l’économie locale – qui reste pour eux focalisée sur la production de cannabis, cette dernière restant néanmoins officiellement interdite.

  1. Bassins versants du Loup, de la Cagne et du Malvan

    OpenAIRE

    Lepère, Cédric; Lautier, Laurence; Pellegrino, Emmanuel

    2013-01-01

    Identifiant de l'opération archéologique : 8453 Date de l'opération : 2007 (PC) ; 2007 (PI) Inventeur(s) : Lepère Cédric (AUT) ; Lautier Laurence (AUT) ; Pellegrino Emmanuel (AUT) Une campagne de prospection inventaire a été effectuée pendant trois mois, dans les bassins-versants de la Cagne, du Loup et du Malvan qui regroupent les communes de Cagnes-sur-Mer, Villeneuve-Loubet, La Colle-sur-Loup, Saint-Paul-de-Vence, Vence, Saint-Jeannet, Bezaudun, Tourrettes-sur-Loup, Roquefort-les-Pins, Le ...

  2. Marche du foncier urbain et promotion du logement au Benin ...

    African Journals Online (AJOL)

    Le marché du foncier urbain au Bénin est un secteur qui met en jeu l'intervention de plusieurs acteurs publics et privés mais également de l'informel. La notion de « foncier urbain » utilisée dans cet article englobe les acceptions et les utilisations faites en architecture, en urbanisme, en aménagement et en gestion urbaine.

  3. Gestion du parc agroforestier du terroir de Vipalogo (Burkina Faso ...

    African Journals Online (AJOL)

    Au Burkina Faso, l'arbre rural fait partie des systèmes de production. Le choix des espèces, leur densité, les modes de gestion ainsi que les besoins à satisfaire, obéissent à des critères propres aux producteurs. C'est pour comprendre ces logiques paysannes de la gestion du parc agroforestier que la présente étude a été ...

  4. Malformations du tube neural en chirurgie pediatrique du chu de ...

    African Journals Online (AJOL)

    encéphalocèle et 6 cas de sipina bifida. La cure chirurgicale a été le principal mode de prise en charge des patients. Seuls 91,38% des cas ont été opérés. Pour toutes les malformations du tube neural, nous avons enregistré 7 décès dont 2 décès ...

  5. Recovery of palladium, cesium, and selenium from heavy metal alkali borosilicate glass by combination of heat treatment and leaching processes

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zhanglian; Okada, Takashi, E-mail: t-okada@u-fukui.ac.jp; Nishimura, Fumihiro; Yonezawa, Susumu

    2017-06-05

    Highlights: • A separation technique of both noble and less noble metal from glass is studied. • Via reductive heat treatment, 80% of palladium is extracted in liquid bismuth. • Sodium–potassium-rich materials with cesium and selenium are phase separated. • From the materials, over 80% of cesium and selenium are extracted in water. - Abstract: Reductive heat-treatment and leaching process were applied to a simulated lead or bismuth soda-potash-borosilicate glass with palladium, cesium, and selenium to separate these elements. In the reductive heat treatment, palladium is extracted in liquid heavy metal phase generated by the reduction of the heavy metal oxides, whereas cesium and selenium are concentrated in phase separated Na–K-rich materials on the glass surface. From the materials, cesium and selenium can be extracted in water, and the selenium extraction was higher in the treatment of the bismuth containing glass. The chemical forms of palladium in the glass affected the extraction efficiencies of cesium and selenium. Among the examined conditions, in the bismuth glass treatment, the cesium and selenium extraction efficiencies in water were over 80%, and that of palladium in liquid bismuth was over 80%.

  6. Effects of magnesium minerals representative of the Callovian-Oxfordian clay-stone on borosilicate glass alteration

    International Nuclear Information System (INIS)

    Debure, M.

    2012-01-01

    Borosilicate glasses dissolution has been studied in presence of magnesium minerals. Those minerals (dolomite, illite, smectite...) belong to the Callovo-Oxfordian (COx) clay-stone layer, studied in France as a potential site for nuclear waste disposal. Such minerals contain magnesium, an element able to sustain glass alteration when it is available in solution. In the confined media of the wastes disposal, the solids reactivity controls the solution composition and can be the driving force of nuclear glass alteration. Experiments show that magnesium carbonates (hydro-magnesite and dolomite) increase in the glass alteration: the precipitation of magnesium silicates consumes silicon which slows down the formation of the glass passivating layer. The lower the magnesium mineral solubility, the lower the glass alteration. The purified clay phases (illite, smectite...) from the COx layer increase the glass alteration. Half the magnesium was replaced by sodium during the purification process. In such conditions, the effect of clay phases on glass alteration is in part due to the acidic pH-buffering effect of the clay fraction. The GRAAL model implemented in the geochemical transport code HYTEC has confirmed and quantified the mechanisms put in evidence in the experiments. Cells diffusion experiments where the two solids were separated by an inert diffusion barrier allow to valid reactive transport modelling. Such experiments are more representative of the glass package which will be separated from the COx by corrosion products. They show that glass alteration rate is reduced when solids are not close. (author) [fr

  7. The Effect of Caramelization and Carbonization Temperatures toward Structural Properties of Mesoporous Carbon from Fructose with Zinc Borosilicate Activator

    Directory of Open Access Journals (Sweden)

    Tutik Setianingsih

    2014-10-01

    Full Text Available Mesoporous carbon was prepared from fructose using zinc borosilicate (ZBS activator. The synthesis involves caramelization and carbonization processes. The effect of both process temperature toward porosity and functional group of carbon surface are investigated in this research. The caramelization was conducted hydrothermally at 85 and 100 °C, followed by thermally 130 °C. The carbonization was conducted at various temperatures (450–750 °C. The carbon-ZBS composite were washed by using HF 48% solution, 1M HCl solution, and aquadest respectively to remove ZBS from the carbon. The carbon products were characterized with nitrogen gas adsorption-desorption method, FTIR spectrophotometry, X-ray diffraction, and Transmission Electron Microscopy. The highest mesopore characteristics is achieved at 100 °C (caramelization and 450 °C (carbonization, including Vmeso about 2.21 cm3/g (pore cage and 2.32 cm3/g (pore window with pore uniformity centered at 300 Å (pore cage and 200 Å (pore window, containing the surface functional groups of C=O and OH, degree of graphitization about 57% and aromaticity fraction about 0.68.

  8. A dynamic fatigue study of soda-lime silicate and borosilicate glasses using small scale indentation flaws

    International Nuclear Information System (INIS)

    Dabbs, T.P.; Lawn, B.R.; Kelly, P.L.

    1982-01-01

    The dynamic fatigue characteristics of two glasses, soda-lime silicate and borosilicate, in water have been studied using a controlled indentation flaw technique. It is argued that the indentation approach offers several advantages over more conventional fatigue testing procedures: (i) the reproducibility of data is relatively high, eliminating statistics as a basis of analysis: (ii) the flaw ultimately responsible for failure is well defined and may be conveniently characterised before and after (and during, if necessary) the strength test; (iii) via adjustment of the indentation load, the size of the flaw can be suitably predetermined. Particular attention is devoted to the third point because of the facility it provides for systematic investigation of the range of flaw sizes over which macroscopic crack behaviour remains applicable. The first part of the paper summarises the essential fracture mechanics theory of the extension of an indentation flaw to failure. In the next part of the paper the results of dynamic fatigue tests on glass rods in distilled water are described. Data are obtained for Vickers indentation loads in the range 0.05 to 100 N, corresponding to contact dimensions of 2 to 100 μm. Finally, the implications of the results in relation to the response of 'natural' flaws are discussed. (author)

  9. Enhanced mechanical properties of single walled carbon nanotube-borosilicate glass composite due to cushioning effect and localized plastic flow

    Directory of Open Access Journals (Sweden)

    Sujan Ghosh

    2011-12-01

    Full Text Available A borosilicate glass composite has been fabricated incorporating Single Wall Carbon Nanotubes (SWCNT in the glass matrix by melt-quench technique. Hardness and the fracture toughness of the composite, were found to increase moderately with respect to the base glass. Interestingly one can observe accumulation of SWCNT bundles around the crack zone though no such accumulation was observed in the crack free indentation zone. The enhanced hardness of the composite was discussed by correlating the cushioning as well as toughening behavior of the agglomerated SWCNT bundles. On the other hand enhanced plastic flow was proposed to be the prime reason for the accumulation of SWCNT bundles around the crack, which increases the toughness of the composite by reducing the crack length. Moreover to ascertain the enhanced plasticity of the composite than that of the glass we calculated the recovery resistance of glass and the composite where recovery resistance of composite was found to be higher than that of the glass.

  10. Chemical durability of alkali-borosilicate glasses studied by analytical SEM, IBA, isotopic-tracing and SIMS

    Science.gov (United States)

    Trocellier, P.; Djanarthany, S.; Chêne, J.; Haddi, A.; Brass, A. M.; Poissonnet, S.; Farges, F.

    2005-10-01

    Simple and complex alkali-borosilicate glasses were submitted to aqueous corrosion at room temperature, 60 and 90 °C in solutions with pH ranging between 0 and 12. Analytical scanning electron microscopy (SEM), ion beam analysis (IBA) techniques, isotopic tracing and secondary ion mass-depth profiling (SIMS) have been used to investigate the variations of the surface composition of glass. In acidic medium, the glass surface is generally covered by a thick hydrated silica layer, mobile elements like Li, Na and B and transition elements (Fe, Zr, Mo, etc.) are strongly depleted. Near pH 7, relative enrichments of aluminium, iron and rare earths are shown together with strong Li, Na and B depletions. In basic medium, the glass surface exhibits relative enrichments of the major part of transition metals (from Cr to U) whereas mobile elements seem to be kept close to their nominal concentration level at the glass surface and Si is severely impoverished. Hydrogen incorporated at the glass surface after leaching is much more immobile in neutral and basic media than in acid medium.

  11. Irradiations effects on the structure of boro-silicated glasses: long term behaviour of nuclear waste glassy matrices

    International Nuclear Information System (INIS)

    Bonfils, J. de

    2007-09-01

    This work deals with the long term behaviour of R7T7-type nuclear waste glasses and more particularly of non-active boro-silicated glasses made up of 3 or 5 oxides. Radioactivity of active glasses is simulated by multi energies ions implantations which reproduce the same defects. The damages due to the alpha particles are simulated by helium ions implantations and those corresponding to the recoil nucleus are obtained with gold ions ones. Minor actinides, stemming from the used fuel, is simulated by trivalent rare-earths (Eu 3+ and Nd 3+ ). In a first part, we have shown by macroscopic experiments (Vickers hardness - swelling) and optical spectroscopies (Raman - ATR-IR) that the structure of the glassy matrices is modified under implantations until a dose of 2,3.10 13 at.cm -2 , which corresponds to a R7T7 storage time estimated at 300 years. Beyond this dose, no additional modifications have been observed. The second part concerns the local environment of the rare-earth ions in glasses. Two different environments were found and identified as follows: one is a silicate rich one and the other is attributed to a borate rich one. (author)

  12. In Vitro Degradation of Borosilicate Bioactive Glass and Poly(l-lactide-co-ε-caprolactone Composite Scaffolds

    Directory of Open Access Journals (Sweden)

    Jenna Tainio

    2017-11-01

    Full Text Available Composite scaffolds were obtained by mixing various amounts (10, 30 and 50 weight % [wt %] of borosilicate bioactive glass and poly(l-lactide-co-ε-caprolactone (PLCL copolymer. The composites were foamed using supercritical CO2. An increase in the glass content led to a decrease in the pore size and density. In vitro dissolution/reaction test was performed in simulated body fluid. As a function of immersion time, the solution pH increased due to the glass dissolution. This was further supported by the increasing amount of Ca in the immersing solution with increasing immersion time and glass content. Furthermore, the change in scaffold mass was significantly greater with increasing the glass content in the scaffold. However, only the scaffolds containing 30 and 50 wt % of glasses exhibited significant hydroxyapatite (HA formation at 72 h of immersion. The compression strength of the samples was also measured. The Young’s modulus was similar for the 10 and 30 wt % glass-containing scaffolds whereas it increased to 90 MPa for the 50 wt % glass containing scaffold. Upon immersion up to 72 h, the Young’s modulus increased and then remained constant for longer immersion times. The scaffold prepared could have great potential for bone and cartilage regeneration.

  13. White-Beam X-ray Diffraction and Radiography Studies on High-Boron Containing Borosilicate Glass at High Pressures

    Science.gov (United States)

    Ham, Kathryn; Vohra, Yogesh; Kono, Yoshio; Wereszczak, Andrew; Patel, Parimal

    Multi-angle energy-dispersive x-ray diffraction studies and white-beam x-ray radiography were conducted with a cylindrically shaped (1 mm diameter and 0.7 mm high) high-boron content borosilicate glass sample (17.6% B2O3) to a pressure of 13.7 GPa using a Paris-Edinburgh (PE) press at Beamline 16-BM-B, HPCAT of the Advanced Photon Source. The measured structure factor S(q) to large q = 19 Å-1, is used to determine information about the internuclear bond distances between various species of atoms within the glass sample. Sample pressure was determined with gold as a pressure standard. The sample height as measured by radiography showed an overall uniaxial compression of 22.5 % at 13.7 GPa with 10.6% permanent compaction after decompression to ambient conditions. The reduced pair distribution function G(r) was extracted and Si-O, O-O, and Si-Si bond distances were measured as a function of pressure. Raman spectroscopy of pressure recovered sample as compared to starting material showed blue-shift and changes in intensity and widths of Raman bands associated with silicate and B3O6 boroxol rings. US Army Research Office under Grant No. W911NF-15-1-0614.

  14. Effects of cobalt-60 gamma radiation on the strength-related internal structure of the borosilicate glass

    International Nuclear Information System (INIS)

    Cafe, Arven I.; Liamzon, Angelie J.

    2011-03-01

    Borosilicate glass in the form of glass slides (1.Omm in thickness and cut into 12.5mm x 55.Omm surface area) was examined to determine the reusability or recyclability and strength of glass apparatuses or compartments after exposing to gamma irradiation from Co-60 source. After knowing the initial parameters using EDXRF under six secondary targets, glass specimens prepared was subjected to gamma radiation for doses 3kGy, 6kGy, 15kGy, 25kGy, and 100kGy. Results of characterization under FTIR provides information about the occurred extension of B-O-Si and B-O-B linkages for lower doses (3-25kGy), while destruction of Si-O bonds for higher dose (100kGy). It shows direct relationship on the observed color change from clear ransparent to deep brown corresponding to the change in optical densities as irradiation dose increases. Ability to fade the induced deep brown color was also observed for a certain time interval which satisfies that this type of glass exhibits self healing property. Although, average energy of about 1.25MeV causes rearrangement of atoms within the glass, according to the XRD result, it remained to be an amorphous solid even in higher dose applied which satisfies that remanufacturing and recycling is possible. (author)

  15. Effects of Sb2O3 on the Mechanical Properties of the Borosilicate Foam Glasses Sintered at Low Temperature

    Directory of Open Access Journals (Sweden)

    Chenxi Zhai

    2014-01-01

    Full Text Available The physical properties and microstructure of a new kind of borosilicate foam glasses with different Sb2O3 doping content are comprehensively investigated. The experimental results show that appropriate addition of Sb2O3 has positive impact on the bulk porosity and compressive strength of the foam glass. It is more suitable in this work to introduce 0.9 wt.% Sb2O3 into the Na2O-K2O-B2O3-Al2O3-SiO2 basic foam glass component and sinter at 775°C. And the obtained foam glasses present much more uniform microstructure, large pore size, and smooth cell walls, which bring them with better performance including a lower bulk density, low water absorption, and an appreciable compressive strength. The microstructure analysis indicates that, with the increase of the content of Sb2O3 additives, the cell size tends to increase at first and then decreases. Larger amounts of Sb2O3 do not change the crystalline phase of foam glass but increase its vitrification. It is meaningful to prepare the foam glass at a relatively low temperature for reducing the heat energy consumption.

  16. Chemical durability of alkali-borosilicate glasses studied by analytical SEM, IBA, isotopic-tracing and SIMS

    International Nuclear Information System (INIS)

    Trocellier, P.; Djanarthany, S.; Chene, J.; Haddi, A.; Brass, A.M.; Poissonnet, S.; Farges, F.

    2005-01-01

    Simple and complex alkali-borosilicate glasses were submitted to aqueous corrosion at room temperature, 60 and 90 deg. C in solutions with pH ranging between 0 and 12. Analytical scanning electron microscopy (SEM), ion beam analysis (IBA) techniques, isotopic tracing and secondary ion mass-depth profiling (SIMS) have been used to investigate the variations of the surface composition of glass. In acidic medium, the glass surface is generally covered by a thick hydrated silica layer, mobile elements like Li, Na and B and transition elements (Fe, Zr, Mo, etc.) are strongly depleted. Near pH 7, relative enrichments of aluminium, iron and rare earths are shown together with strong Li, Na and B depletions. In basic medium, the glass surface exhibits relative enrichments of the major part of transition metals (from Cr to U) whereas mobile elements seem to be kept close to their nominal concentration level at the glass surface and Si is severely impoverished. Hydrogen incorporated at the glass surface after leaching is much more immobile in neutral and basic media than in acid medium

  17. Impact of soda-lime borosilicate glass composition on water penetration and water structure at the first time of alteration

    International Nuclear Information System (INIS)

    Rebiscoul, D.; Bruguier, F.; Gin, S.; Magnin, V.

    2012-01-01

    In this study, the impact of soda-lime borosilicate glass composition and particularly the effect of charge compensators such Ca and Na and, of network formers such Si and Zr, on water penetration and water structure at the first time of alteration were investigated. Two non-destructive techniques were combined: the Fourier transform infrared spectroscopy in attenuated total reflection geometry to precise the predominant alteration mechanisms and assess the water structure in altered zone and the grazing incidence X-ray reflectometry to determine the thickness of the altered glass zone allowing to calculate the water diffusion coefficients through the glasses. The results of glass alteration at pH = 3 and 30 degrees C have shown that hydrolysis was the predominant mechanism after few seconds for glass having a high amount of non-binding oxygen. For the other glasses, which for the diffusion was the limiting reaction, the calculated water diffusion coefficients were comprised between 10 -21 and 10 -19 m 2 .s -1 and vary as a function of glass composition. An activation energy of 76.9 kJ.mol -1 was calculated and appears to be higher than inert gas diffusion through the glass highlighting that water molecules strongly interact with the glass matrix. (authors)

  18. Conversion of plutonium-containing materials into borosilicate glass using the glass material oxidation and dissolution system

    International Nuclear Information System (INIS)

    Forsberg, C.W.; Beahm, E.C.; Parker, G.W.

    1996-01-01

    The end of the cold war has resulted in excess plutonium-containing materials (PCMs) in multiple chemical forms. Major problems are associated with the long-term management of these materials: safeguards and nonproliferation issues; health, environment, and safety concerns; waste management requirements; and high storage costs. These issues can be addressed by conversion of the PCMs to glass: however, conventional glass processes require oxide-like feed materials. Conversion of PCMs to oxide-like materials followed by vitrification is a complex and expensive process. A new vitrification process has been invented, the Glass Material Oxidation and Dissolution System (GMODS) to allow direct conversion of PCMs to glass. GMODS directly converts metals, ceramics, and amorphous solids to glass; oxidizes organics with the residue converted to glass; and converts chlorides to borosilicate glass and a secondary sodium chloride stream. Laboratory work has demonstrated the conversion of cerium (a plutonium surrogate), uranium (a plutonium surrogate), Zircaloy, stainless steel, multiple oxides, and other materials to glass. Equipment options have been identified for processing rates between 1 and 100,000 t/y. Significant work, including a pilot plant, is required to develop GMODS for applications at an industrial scale

  19. L’Harmonie du monde

    Directory of Open Access Journals (Sweden)

    Martine Clouzot

    2003-11-01

    Full Text Available La Bourgogne est particulièrement bien présente et représentée dans l’exposition sur la musique et ses représentations au Moyen Âge organisée par Isabelle Marchesin (université de Poitiers, Christine Laloue (conservatrice du Patrimoine au Musée et Martine Clouzot (université de Bourgogne, au Musée de la Musique à Paris du 26 mars au 27 juin 2004. En Côte-d’Or, à Dijon, la Bibliothèque municipale a donné son accord officiel pour le prêt de la Bible d’Etienne Harding, les Moralia in Job et u...

  20. Les vicissitudes du fret ferroviaire

    OpenAIRE

    DABLANC, L

    2010-01-01

    Dans beaucoup de pays européens, et plus encore en Amérique du Nord et en Asie, le transport de marchandises par le train a augmenté depuis dix ans. Cette activité réduit la part des marchandises acheminées par la route et contribue ainsi au développement durable : un camion émet 8 à 30 fois plus de dioxyde de carbone que le train, pour une distance et une quantité transportée équivalentes. Pourtant, la France a raté ce renouveau. Filiale du groupe public SNCF, la Société Fret SNCF, qui assur...

  1. L'energie du moustique

    CERN Document Server

    Augereau, J F

    2002-01-01

    ENSEMBLE DE QUATRE ARTICLES - LARGE HADRON COLLIDER: Le dernier accelerateur de particules du CERN, le LEP, produisait des faisceaux d'electrons de 100 GeV chacun. Le LHC, qui accelere des faisceaux de protons, leur communiquera une energie de 7 TeV chacun. Une energie a la fois colossale et derisoire. Un TeV represente a peu pres l'energie cinetique d'un moustique (1/2 page).

  2. Revision des Symphurus du Siboga

    NARCIS (Netherlands)

    Chabanaud, Paul

    1955-01-01

    Ce m’est un devoir particulièrement agréable que de saisir l’occasion de ce petit mémoire pour remercier M. L. F. DE BEAUFORT, M. H. ENGEL, Directeur du Zoologisch Museum, ainsi que M. J. J. HOEDEMAN de l’accueil qu’à diverses reprises, j’ai reçu de leur part, au Zoölogisch Museum, et aussi des

  3. Actes des 5èmes Journées Scientifiques du GDR3544 Sciences du Bois. Journées Annuelles du GDR 3544 Sciences du Bois

    OpenAIRE

    CHAPLAIN, Myriam; CARE, Sabine; GRIL, Joseph

    2016-01-01

    Le Groupement de Recherche en Sciences du bois (GDR3544 Sciences du Bois) a été créé en 2012 par le CNRS et renouvelé en 2016 pour 5 ans. La mission de ce groupement est : (1) de structurer la recherche sur le bois en France pour lui donner une visibilité nationale, (2) de contribuer au développement de la formation en sciences du bois et (3) de servir de relai aux réseaux internationaux de sciences du bois. Les 5èmes journées annuelles du GDR Bois ont été organisées à Bordeaux, au domaine du...

  4. Original Paper Performances comparées du HDL-cholestérol et du ...

    African Journals Online (AJOL)

    CT/HDL-C) et du HDL-Cholestérol est le meilleur prédicteur du SMet chez les adultes béninois. .... (Canada) et du. Ministère de la Santé du Bénin. Le consentement éclairé écrit a été obtenu de chaque participant avant leur recrutement dans.

  5. 35 Typologie des eaux de surface du bassin du Sebou par multi ...

    African Journals Online (AJOL)

    PR BOKO

    2Service de protection de la qualité de l'eau, Agence du Bassin Hydraulique du ... pour montrer l'évolution de la qualité biologique des eaux de surface du ..... Biological Indicators of Freshwater Pollution and Environmental Management,.

  6. Régionalisation du recrutement du personnel de santé au Burkina ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Régionalisation du recrutement du personnel de santé au Burkina Faso ... le ministère a adopté une politique de recrutement régionalisé de certaines catégories du ... de comprendre le contexte dans lequel une telle stratégie a été formulée, ...

  7. La disparition du temps en gravitation quantique

    OpenAIRE

    Saint-Ours, Alexis de

    2012-01-01

    Le but de ce travail est d’examiner l’incidence philosophique de la gravitation quantique sur le concept de temps. Je cherche à montrer qu’elle conduit à une disparition du temps comme dimension et ouvre la voie à une compréhension du temps comme variation et même à l’idée de variation pure. En l’absence de temps mécanique, il est cependant possible de définir un temps d’origine thermodynamique. Je montre en quoi cette dissociation du temps mécanique et du temps thermodynamique, fait écho à l...

  8. Au fil du temps (1976 ou la loi du seuil

    Directory of Open Access Journals (Sweden)

    Isabelle Singer

    2010-04-01

    Full Text Available Ayant choisi de vivre dans un camion, les héros d’Au fil du temps (film de Wim Wenders de 1976 font du seuil une expérience particulière. Celle de la rupture avec toute idée de foyer et celle du refus d’appartenance à la terre natale, cette terre allemande traversée par une frontière le long de laquelle ils vont voyager, et qui les renvoie à chaque instant aux traumatismes de l’Histoire. Sur le pare-brise du camion, l’extérieur (campagnes indifférenciées, villes à l’abandon… et l’intérieur se superposent. Au fil du temps questionne le paysage : il s’agit d’en décoller un à un les mythes qui le recouvrent. L’image alors n’est plus surface mais volume à traverser, à lacérer et découvrir ce qui est tissé dans le paysage. La démarche de Wenders est alors proche de celle d’un de ses contemporains : Anselm Kiefer. Le paysage allemand provoque le rejet parce qu’il y a là toujours plus que le visible : des strates et des strates de culpabilité que le mythe - et c’est sa fonction - a recouvert. Et qu’il s’agira ici, de soulever. Le choix du nomadisme, c’est celui d’un état de l’humanité antérieur à l’idée de patrie. Et c’est aussi celui de la solitude, comme prix à payer à ce refus d’appartenance et à cette mise à jour des mythes. L’appartenance à la terre allemande et à son Histoire est profondément problématique parce que les pères sont fondamentalement coupables. On se reconnaîtra alors des pères de substitution : des pères de cinéma (Nicholas Ray ou Fritz Lang. Et l’on substituera l’Histoire du cinéma à l’Histoire. Bruno est réparateur ambulant de projecteurs et Au fil du temps dressera, au gré de ses pérégrinations, un état des lieux du cinéma allemand des années soixante-dix : déliquescent, colonisé par les images hollywoodiennes. Il faut que cela change : état du cinéma ; état des protagonistes solitaires en quête d’une identit

  9. Some aspects of sulphite metabolism in plants; Quelques aspects du metabolisme du sulfite chez les vegetaux

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Milan, Hernan

    1958-05-15

    As sulphite appears to be an intermediate substance in the degradation of sulphur-containing amino acids, and has an important metabolic role, notably for plants, this research thesis aims at comparing transformations which may occur for a same chemical compound (the sulphite) in various organisms belonging to different species or kingdoms. More particularly, the author studied the formation of sulphite in vegetal tissues, and the oxidisation of sulphite into sulfate within these tissues. In vitro experiments have been performed with oat, while in vivo experiments have been performed on tobacco plants [French] Le sulfite apparait comme une substance intermediaire de la degradation des acides amines soufres. Son role dans la biosynthese de certains d'entre eux, problematique chez les mammiferes, est certain chez les oiseaux, qui, a cet egard, se comportent comme des autotrophes partiels, puisqu'ils reduisent le sulfate en sulfite. On s'apercoit ainsi qu'un degre d'evolution moindre confere au sulfite une importance metabolique plus grande. On peut s'attendre a trouver chez les vegetaux un role encore accru pour le sulfite. Le present travail entre dans ce cadre d'etudes comparees des transformations que peut subir un meme type de compose chimique: le sulfite, dans divers organismes appartenant a des especes ou a des regnes differents. Les donnees acquises exposees ici auront trait aux deux points suivants: I - La formation du sulfite dans les tissus vegetaux, II - L'oxydation dans ces tissus, du sulfite en sulfate. L'avoine nous a servi comme materiel de depart pour les experiences faites in vitro. Cette plante presente en effet l'avantage de se bien cultiver en toutes saisons, de se broyer facilement, et d'etre depourvue au maximum de mucilages, de resines, substances genantes pour l'analyse ulterieure. Les essais faits in vivo, ont mis en oeuvre des plants de tabac, qui permettent une nutrition par le petiole ou par la tige particulierement aisee.

  10. 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

  11. Color centers of a borosilicate glass induced by 10 MeV proton, 1.85 MeV electron and 60Co-γ ray

    Science.gov (United States)

    Du, Jishi; Wu, Jiehua; Zhao, Lili; Song, Lixin

    2013-05-01

    Optical absorption spectra, electron paramagnetic resonance (EPR) spectra, Raman spectra of a borosilicate glass after irradiation by 10 MeV proton, 1.85 MeV electron and 60Co-γ ray were studied. The process of irradiation inducing color centers in the glass was discussed. The band gap of the glass before and after 60Co-γ ray irradiation was studied using Mott and Davis's theory, and it was found that calculated change of the band gap introduced a paradox, because Mott and Davis's theory on the band gap cannot be adopted in the study on the irradiated glass.

  12. Effects of /sup 60/Co gamma radiation damage and heat treatment on the electro-mechanical properties of some related lithium alumino-borosilicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Abou Sekkina, M.M.; Gohar, I.A.; Megahed, A.A. (Al-Azhar Univ., Tanta (Egypt). Faculty of Science; Cairo Univ., El Mansura (Egypt). Faculty of Science)

    1985-01-01

    Various samples of pure lithium alumino-borosilicate glasses have been prepared and annealed. Data have been taken on the temperature dependence of DC electrical conductivity and the activation energy for conduction was evaluated in each case. Vickers hardness data have also been obtained as a function of tempering temperature and time for all glass compositions. Co-ordinated explanations of the DC conductivity and Vickers hardness induced by ionizing radiation are put forward and the activation energy for the process of carrier liberation are evaluated for the first time.

  13. Le vide univers du tout et du rien

    CERN Document Server

    Diner, Simon

    1997-01-01

    Pourquoi l'Univers plutôt que le vide ? Le temps et l'espace existent-ils en l'absence de l'Univers ? Que reste-t-il quand tout est enlevé ? Pourquoi quelque chose plutôt que rien ? Depuis des siècles, ces interrogations mobilisent philosophes et physiciens. Mais aujourd'hui, le vide n'est pas le rien. Il serait même l'acteur central de l'histoire de la matière et de l'Univers, le partenaire privilégié de la physique. Vide et matière ne sont plus deux manifestations séparées de la nature, mais deux aspects d'une même réalité. Le vide est l'état de base dont la matière émerge, sans couper son cordon ombilical Le vide comme Univers du rien cède la place au vide comme Univers du tout. Que le vide puisse être conçu par les physiciens comme réservoir potentiel d'univers, voici qui ne devrait laisser personne indifférent. Ce livre ouvre un débat et nous convie à une réflexion surprenante.

  14. Image du savoir, image du pouvoir dans le Lapidaire

    Directory of Open Access Journals (Sweden)

    Marta LACOMBA

    2007-01-01

    Full Text Available À travers le prologue et les enluminures de présentation, le Lapidaire d’Alphonse X oriente l’interprétation de l’œuvre. Ces paratextes mettent en avant le rôle capital du savoir, représenté par la métaphore du trésor caché, qui a ici une valeur topique. Ils mettent également en exergue le rôle que s’attribue le roi dans la transmission de ce savoir, et placent cette nouvelle attribution royale au cœur de son projet politique.A través del prólogo y las miniaturas de presentación, el Lapidario de Alfonso X orienta la interpretación de la obra. Estos paratextos subrayan el papel capital del saber, representado por la metáfora del tesoro escondido, que tiene aquí un valor tópico. Ponen asimismo de manifiesto el papel que se atribuye el monarca en la transmisión de ese saber y colocan esta nueva atribución real en el centro de su proyecto político.

  15. Main: 1DU5 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1DU5 トウモロコシ Corn Zea mays L. Zeamatin Precursor. Name=Zlp; Zea Mays Molecule: Zeamatin; Chai...eta Sandwich SWS:ZEAM_MAIZE,P33679|EMBL; U06831; AAA92882.1; -.|PIR; T02075; T02075.|PDB; 1DU5; X-ray; A/B=22-227.|Mai

  16. les cahiers du cread: About this journal

    African Journals Online (AJOL)

    les cahiers du cread: About this journal. Journal Home > les cahiers du cread: About this journal. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register · Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives. People. » Contact. Policies.

  17. Les figures multiples du maire.

    Directory of Open Access Journals (Sweden)

    Olivier Lebraud

    2004-06-01

    Full Text Available Alors même que l’ensemble du personnel gouvernemental et parlementaire est sujet à une relative désaffection de la part des citoyens, les maires français jouissent, on le sait, d’une popularité qui fait d’eux les figures centrales de la scène politique. Au-delà de la décentralisation, qui a souvent renforcé leur image de décideurs, ils ont su tirer parti de la dimension identitaire qui caractérise l’échelon communal pour devenir les acteurs indispensables de la vie locale. ...

  18. Vers une anthropologie du Confucianisme

    OpenAIRE

    Rieu , Alain-Marc

    2010-01-01

    Research in Anthropology developed in France by Jean-Pierre Vernant, Marcel Détienne and Philippe Descola opens the possibility to reframe the debate and research on the function of Confucianism in Chinese culture, history and society. This paper shows how Confucianism can be studied as a "mythology"; La fonction du Confucianisme dans l'histoire de la société et de la culture chinoise, les débats et les reconstructions dont il est l'objet et l'enjeu, ouvre la possibilité de l'étudier d'un poi...

  19. Session du Conseil du CERN : le ministre britannique, Robert Jackson, souligne l'intérêt de on pays pour l'avenir du CERN : décisions du Conseil pour la mise en oeuvre des recommandations du Comité d'évaluation du CERN: départ anticipé pour 200 membres au moins du personnel - mise à jour de la méthode de calcule pour les contributions des Etats Membres au budget

    CERN Multimedia

    CERN Press Office. Geneva

    1988-01-01

    Session du Conseil du CERN : le ministre britannique, Robert Jackson, souligne l'intérêt de on pays pour l'avenir du CERN : décisions du Conseil pour la mise en oeuvre des recommandations du Comité d'évaluation du CERN: départ anticipé pour 200 membres au moins du personnel - mise à jour de la méthode de calcule pour les contributions des Etats Membres au budget

  20. Physique du deuil. Note sur la dernière vie de Roland Barthes

    Directory of Open Access Journals (Sweden)

    Maïté Snauwaert

    2013-03-01

    Full Text Available Les remarques sur la tenue de la maison et du corps dans le quotidien domestique, conçue comme une éthique de la fidélité à la mère récemment disparue, apparaissent dans l’écrit privé du Journal de deuil de Roland Barthes comme un écho des observations faites dans le cours sur La préparation du roman. Participant d’une physique du vivre et de l’habiter qui met l’accent sur l’entretien quotidien du lieu, le silence et la difficulté de tout voyage, les « notations » du journal rendent compte de la condensation dans le corps de l’épreuve du deuil, et de la prise de conscience d’un dernier âge de la vie.In the personal writings of Journal de deuil, Roland Barthes’ remarks regarding the maintenance of the home and body are conceived of as an ethic of faithfulness to his recently deceased mother. They are considered in this article as an echo to the observations he makes during his lectures in the course La préparation du roman. Both emphasize the physicality of everyday life and the role played by one’s relationship to the home. By stressing the necessity of silence and the difficulties of leaving “the apartment”, the brief “notations” in the diary translate the physical concentration of the mourning experience, as well as the emergent understanding of a final stage of life.

  1. Le rôle du récit de vie dans le discours politique de Lula The role of Lula’s Life Story in his Political Speeches

    Directory of Open Access Journals (Sweden)

    Ida Lucia Machado

    2011-10-01

    Full Text Available Cet article propose une réflexion sur le rôle du récit de vie dans les discours politiques, et plus précisément dans les discours d’investiture à la présidence du Brésil de Luis Ignacio Lula da Silva. Il analyse quelques fragments qui mêlent expressément des souvenirs de sa vie passée aux discours politiques d’actualité, mais aussi qui font allusion à sa vie de façon indirecte. Dans le premier discours, Lula se présente comme un personnage de l’histoire, un « il » qui veut travailler pour la collectivité ; néanmoins, les allusions à sa trajectoire de vie le légitiment comme celui qui peut promouvoir le changement requis par le peuple. Dans le second discours, Lula utilise depuis le début un « je » ancré dans sa propre histoire : sa « petite » histoire personnelle semble ainsi s’incorporer à la « grande » histoire d’une nation. En ce sens, le récit de vie comprend une dimension argumentative qui permet de construire un ethos présidentiel par le jeu qu’il instaure entre l’individuel et le collectif, créant ainsi un effet de pathos qui appelle à l’identification. On s’interroge dans ce cadre sur la question du populisme dans son rapport aux stratégies de captation propres au discours politique.This paper analyzes fragments of President Luiz Inácio Lula da Silva’s inaugural speeches. Lula da Silva served as the President of Brazil for two consecutive terms in office. In his first inaugural speech, Lula da Silva refers to himself as a historical character, and uses the pronoun “he” (or “not-I”, a “he” at the service of the community. However, his path in life, mentioned in a single paragraph, legitimizes him as someone who is able to bring forward the changes demanded by the people. From the beginning of his second inaugural speech, Lula da Silva uses the pronoun “I”, which points to his own story: therefore, his “small, personal story” seems to be embedded into the

  2. Impact of crystallization on the structure and chemical durability of borosilicate glass

    International Nuclear Information System (INIS)

    Nicoleau, Elodie

    2016-01-01

    This work describes a new approach to help understand the chemical durability of partially crystallized nuclear waste conditioning matrices. Among the studies carried out on nuclear waste deep geological disposal, long term behavior studies have so far been conducted on homogeneous glassy matrices. However, as the crystalline phases may generate modifications in the chemical composition and properties of such matrices, the description and a better understanding of their effects on the chemical durability of waste packages are of primary importance. A protocol to study the durability of heterogeneous model matrices of nuclear interest containing different types of crystalline phases was developed. It is based on a detailed description of the morphology, microstructure and structure of the glassy matrix and crystalline phases, and on the study of various alteration regimes. Three crystal phases that may form when higher concentrations of waste are immobilized in Uranium Oxide type conditioning glasses were studied: alkali and alkaline earth molybdates, rare earth silicates and ruthenium oxide. The results highlight the roles of the composition and the structure of the surrounding glassy matrix as the parameters piloting the alteration kinetics of the partially crystallized glassy matrices. This behavior is identical whatever the nature of the crystalline phases, as long as these phases do not lead to a composition gradient and do not percolate within the glassy matrix. Given these results, a methodology to study partially crystallized matrices with no composition gradient is then suggested. Its key development lies firstly in the evaluation of the behavior of partially crystallized matrices through the experimental study of the residual glassy matrix in various alteration regimes. This methodology may be adapted to the case of new glass formulations with more complex compositions (e.g. highly waste-loaded glass), which may contain crystals formed during cooling

  3. Bases en technique du vide

    CERN Document Server

    Rommel, Guy

    2017-01-01

    Cette seconde édition, 20 ans après la première, devrait continuer à aider les techniciens pour la réalisation de leur système de vide. La technologie du vide est utilisée, à présent, dans de nombreux domaines très différents les uns des autres et avec des matériels très fiables. Or, elle est souvent bien peu étudiée, de plus, c'est une discipline où le savoir-faire prend tout son sens. Malheureusement la transmission par des ingénieurs et techniciens expérimentés ne se fait plus ou trop rapidement. La technologie du vide fait appel à la physique, à la chimie, à la mécanique, à la métallurgie, au dessin industriel, à l'électronique, à la thermique, etc. Cette discipline demande donc de maîtriser des techniques de domaines très divers, et ce n'est pas chose facile. Chaque installation est en soi un cas particulier avec ses besoins, sa façon de traiter les matériaux et celle d'utiliser les matériels. Les systèmes de vide sont parfois copiés d'un laboratoire à un autre et le...

  4. Contributions of vitreous natural analogs to the investigation of long-term nuclear glass behavior; Apports des analogues naturels vitreux a la validation des codes de prediction du comportement a long terme des verres nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Techer, I

    1999-07-01

    This study assesses the extend of the analogy between the alteration behavior in water and in a moist clay environment of aluminosilicate volcanic glass and alumino-borosilicate nuclear containment glass. Basaltic glass alteration in water initially occurs by hydrolysis processes with an activation energy on the order of 73 kJ.mol{sup -1}. As the reaction progresses, the alteration rate drops by over four orders of magnitude from the initial rate r{sub 0}, The alteration kinetics are not governed by the alteration solution chemistry alone, the glass alteration film appears to have a major role as a diffusion barrier limiting the transfer of reaction species and products. All these aspects highlight the behavioral analogy between basaltic glass and nuclear borosilicate glass in aqueous media. Conversely, the alteration reaction of obsidian-type volcanic glass involves other mechanisms than those governing the dissolution of borosilicate glass. Basaltic glass alteration is also examined in the presence of a clay environmental material, in a study of the natural basaltic glass and argillaceous pelites system of the Salagou basin in southern France, in an approach combining mineralogical, chemical and isotopic data to assess the interactions between a basaltic glass and the argillaceous pelites. Laboratory leach test results with basaltic glass and measured data for the Salagou glass in its natural environment are modeled using a code implementing a kinetic law coupling diffusive transfer of dissolved silica with a reaction affinity law. (author)

  5. Les dimensions émotionnelles du terrorisme

    Directory of Open Access Journals (Sweden)

    Benjamin Ducol

    2013-10-01

    Full Text Available Par une volonté louable de rompre avec des approches psychologisantes du phénomène terroriste dominantes au cours des années 1960-70, les recherches contemporaines en matière de terrorisme(s et de violence(s politique(s ont très largement mis l’emphase sur la figure du « terroriste » comme acteur rationnel et stratégique. Face aux limites des approches rationalistes de l’engagement radical qui envisagent de manière réductionniste les individus au travers d’un calcul rationnel univoque en terme de coûts et d’incitatifs à l’action, il nous apparaît important de réintégrer dans les réflexions théoriques sur les phénomènes terroristes, les émotions afin d’en interroger le rôle dans la production d’une trajectoire violente. Le présent article entend proposer à cet égard un bilan critique des travaux universitaires actuels autour de l’engagement terroriste et une réflexion théorique mettant en lumière les contours d’un futur agenda de recherche accordant une place plus importante aux ressorts émotionnels de la violence politique clandestine. Contemporary research on terrorism(s and political violence(s have largely put the emphasis on the figure of the "terrorist" as rational and strategic player, in a break with psychoanalytical approaches to terrorism that were dominant from the 1960-1970’s. Given the limitations of rationalist approaches to radical commitment, and considering how reductionist is the understanding of individual participation to terrorism related activities through a rational calculation framework in terms of costs and incentives to action, it is important to reintegrate in the theoretical reflections on terrorist phenomena how emotions can play a role in leading potential terrorists down a violent path. This paper presents a critical assessment of current academic work surrounding the issue of violent radicalization and involvement in terrorism, and engages in a theoretical debate

  6. Separation process of zirconium and hafnium; Procede de separation du zirconium et du hafnium

    Energy Technology Data Exchange (ETDEWEB)

    Hure, J; Saint-James, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1955-07-01

    About the separation different processes of zirconium-hafnium, the extraction by solvent in cross-current is the most easily the process usable on an industrial scale. It uses tributyl phosphate as solvent, diluted with white spirit to facilitate the decanting. Some exploratory tests showed that nitric environment seemed the most favorable for extraction; but a lot of other factors intervene in the separation process. We studied the influence of the acidity successively, the NO{sub 3}{sup -} ions concentration, the role of the cation coming with NO{sub 3}{sup -}, as well as the influence of the concentration of zirconium in the solution on the separation coefficient {beta} = {alpha}{sub Zr} / {alpha}{sub Hf}. (M.B.) [French] Des differents procedes de separation zirconium-hafnium, l'extraction par solvant en contre-courant est le procede le plus facilement utilisable a l'echelle industrielle. On utilise comme solvant le phosphate de tributyle, dilue avec du white spirit pour faciliter les decantations. Des essais preliminaires ont montre que le milieu nitrique semblait le plus favorable a l'extraction; mais beaucoup d'autres facteurs interviennent dans le processus de separation. Nous avons etudie successivement l'influence de l'acidite, celle de la concentration en ions NO{sub 3}{sup -}, le role du cation accompagnant NO{sub 3}{sup -}, ainsi que l'influence de la concentration en zirconium de la solution sur le coefficient de separation {beta} = {alpha}{sub Zr} / {alpha}{sub Hf}. (MB)

  7. Synthesis of phenobarbital {sup 14}C - 5 (1964); Synthese du phenobarbital {sup 14}C - 5 (1964)

    Energy Technology Data Exchange (ETDEWEB)

    Benakis, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    Phenobarbital (Luminal), well known as a hypnotic agent, plays also an important role in the medical treatment of epilepsy. With the object of studying the metabolism of this medicament in the living system, the synthesis of phenobarbital marked in position 2 of the pyrimidinic ring has been effected. It has been necessary, in order to carry out to research into the metabolism of this product, to have a phenobarbital marked in position 5 of the pyrimidinic ring. This synthesis, making it possible to introduce C-14 into position 5 of the pyrimidinic ring, consists of seven stages starting from C-14 carboxyl benzoic acid having a specific activity of 25 mc/mM. The melting point of the final product is 172 - 173 deg. C and its specific activity is 11.15 mc/mM. The overall radioactive yield of the pure product, with respect to the original benzoic acid (10 mM) is of the order of 3 per cent. The purity of the product has been controlled by paper chromatography; it is of the order of 99 per cent. (author) [French] Le phenobarbital (Luminal) bien connu comme agent hypnotique, joue egalement un role important dans la medication anti-epileptique. Pour l'etude du metabolisme de ce medicament dans l'organisme vivant, nous avons synthetise le phenobarbital marque en position 2 du cycle pyrimidinique. Afin de poursuivre la recherche du metabolisme de ce produit, il a ete necessaire de disposer du phenobarbital marque en position 5 du cycle. pyrimidinique. Cette synthese, permettant l'introduction du {sup 14}C en position 5 du cycle pyrimidinique, comporte sept etapes, au depart de l'acide benzoique carboxyle {sup 14}C, d'une activite specifique de 25 mc/mM. Point de fusion du produit final: 172 - 173 deg. C Activite specifique: 11,15 mC/mM. Rendement total radioactif du produit pur, par rapport a l'acide benzoique de depart sur 10 mM, de l'ordre de 3 pour cent. La purete du produit a ete controlee par chromatographie sur papier; elle est de l'ordre de 99 pour cent. (auteur)

  8. Culture du bambou : diversification des moyens de subsistance des ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Culture du bambou : diversification des moyens de subsistance des petits producteurs de tabac du sud de la province de Nyanza, au Kenya - phase II. Au cours de la première phase du projet (projet no 103765), les chercheurs ont effectué une analyse de marché pour le bambou et les produits du bambou, comparé les ...

  9. Calcium-borosilicate glass-ceramics wasteforms to immobilize rare-earth oxide wastes from pyro-processing

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Miae [Department of Materials Science and Engineering and Division of Advanced Nuclear Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, 790-784 (Korea, Republic of); Heo, Jong, E-mail: jheo@postech.ac.kr [Department of Materials Science and Engineering and Division of Advanced Nuclear Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, 790-784 (Korea, Republic of); Department of Materials Engineering, Adama Science and Technology University (ASTU), PO Box 1888, Adama (Ethiopia)

    2015-12-15

    Glass-ceramics containing calcium neodymium(cerium) oxide silicate [Ca{sub 2}Nd{sub 8-x}Ce{sub x}(SiO{sub 4}){sub 6}O{sub 2}] crystals were fabricated for the immobilization of radioactive wastes that contain large portions of rare-earth ions. Controlled crystallization of alkali borosilicate glasses by heating at T ≥ 750 °C for 3 h formed hexagonal Ca–silicate crystals. Maximum lanthanide oxide waste loading was >26.8 wt.%. Ce and Nd ions were highly partitioned inside Ca–silicate crystals compared to the glass matrix; the rare-earth wastes are efficiently immobilized inside the crystalline phases. The concentrations of Ce and Nd ions released in a material characterization center-type 1 test were below the detection limit (0.1 ppb) of inductively coupled plasma mass spectroscopy. Normalized release values performed by a product consistency test were 2.64·10{sup −6} g m{sup −2} for Ce ion and 2.19·10{sup −6} g m{sup −2} for Nd ion. Results suggest that glass-ceramics containing calcium neodymium(cerium) silicate crystals are good candidate wasteforms for immobilization of lanthanide wastes generated by pyro-processing. - Highlights: • Glass-ceramic wasteforms containing Ca{sub 2}Nd{sub 8-x}Ce{sub x}(SiO{sub 4}){sub 6}O{sub 2} crystals were synthesized to immobilize lanthanide wastes. • Maximum lanthanide oxide waste loading was >26.8 wt.%. • Ce and Nd ions were highly partitioned inside Ca–Nd–silicate crystals compared to glass matrix. • Amounts of Ce and Nd ions released in the material characterization center-type 1 were below the detection limit (0.1 ppb). • Normalized release values performed by a PCT were 2.64• 10{sup −6} g m{sup −2} for Ce ions and 2.19• 10{sup −6} g m{sup −2} for Nd ions.

  10. The effects of sulfate content on crystalline phase, microstructure, and chemical durability of zirconolite−barium borosilicate glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Lang, E-mail: lang.wu@163.com [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Wang, Xin; Li, Huidong; Teng, Yuancheng [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Peng, Long [Sichuan Province Key Laboratory of Information Materials and Devices Application, Chengdu University of Information Technology, Chengdu 610225 (China)

    2016-09-15

    The effects of sulfate content on structure and chemical durability of barium borosilicate glass-ceramics were studied. The results show that the glass-ceramics with 0–1.10 mol% SO{sub 3} possess mainly CaZrTi{sub 2}O{sub 7}-2M phase along with a small amount of CaZrTi{sub 2}O{sub 7}-3T and ZrO{sub 2} phases. The hexagonal CaZrTi{sub 2}O{sub 7}-3T crystals crystallize on the surface of glass-ceramics. For the samples with 1.24–1.55 mol% SO{sub 3}, the main crystalline phases are CaTiSiO{sub 5} and CaZrTi{sub 2}O{sub 7}-2M in the bulk, while a separate sulfate layer containing Na{sub 2}SO{sub 4} and BaSO{sub 4} is observed on the surface. X-ray fluorescence analysis indicates that about 2/3 of the SO{sub 3} originally added has been lost by volatility. The normalized mass loss (NL{sub i}) for Na, B, Ca elements remains almost unchanged (∼10{sup −2} g/m{sup 2}) after 7 days for the samples with 0–1.10 mol% SO{sub 3}. The NL{sub i} for both Na and B increases gradually after 7 days when the SO{sub 3} content is 1.24 mol%. - Highlights: • Strip-shaped CaZrTi{sub 2}O{sub 7}-2M and plate-like CaTiSiO{sub 5} crystals crystallize in the bulk. • CaZrTi{sub 2}O{sub 7}-3T crystals crystallize on the surface for samples with 0–1.10 mol% SO{sub 3}. • A separate sulfate layer crystallizes on the surface when SO{sub 3} exceeds solubility.

  11. A container closure system that allows for greater recovery of radiolabeled peptide compared to the standard borosilicate glass system

    International Nuclear Information System (INIS)

    Leece, Alicia K.; Heidari, Pedram; Yokell, Daniel L.; Mahmood, Umar

    2013-01-01

    Objectives: Often peptides used in synthesis of radiopharmaceutical PET tracers are lipophilic and adhere to the walls of container closure systems (CCS) such that costly peptide and product are not fully recoverable after synthesis occurs. This investigation compares a standard United States Pharmacopeia (USP) Type I borosilicate glass CCS to a cyclic polyolefin copolymer Crystal Zenith ® (CZ) CCS, for 68 Ga-chloride and 68 Ga-DOTATOC ([ 68 Ga] Ga-DOTA-D-Phe1-Tyr3-octreotide) retention in the reaction vial after labeling. Methods: 68 Gallium labeling of DOTATOC was conducted by adding 68 Ga-chloride, 2 M HEPES (4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid) or 0.75 M sodium acetate, and 1–30 µg of DOTATOC into the CZ or glass CCS. The reaction mixture was heated for 15 min and cooled to room temperature. The crude reaction mixture was then withdrawn via syringe, for final processing. The CCS was then assayed using a dose calibrator to determine the amount of retained 68 Ga-DOTATOC. Statistical significance was assessed using an unpaired Student's t-test. Results: In all experiments (n=72) with various amounts of peptide and different buffering systems, the CZ CCS retained less activity than the glass CCS. Using 2 M HEPES and 15 µg or 30 µg of DOTATOC, the CZ CCS retained approximately 10% less of the labeled DOTATOC compared to the glass CCS (p 68 Ga-chloride. Conclusion: For applications involving the labeling of peptides such as 68 Ga-DOTATOC, the CZ CCS compared to the glass CCS, results in an improved recovery of product. - Highlights: • We examined the adhesion of 68 Ga-DOTATOC to glass and CZ CCS. • The adhesion of the 68 Ga-DOTATOC was 10% less in CZ CCS compared to glass CCS. • Overall recovery of 68 Ga-DOTATOC reaction solution is higher in CZ CCS than glass CCS. • Adhesion to the CCS is due to 68 Ga-DOTATOC, not 68 Ga-chloride

  12. The structure of phosphate and borosilicate glasses and their structural evolution at high temperatures as studied with solid state NMR spectroscopy: Phase separation, crystallisation and dynamic species exchange

    International Nuclear Information System (INIS)

    Wegner, S.; Van Wullen, L.; Tricot, G.; Tricot, G.

    2010-01-01

    In this contribution we present an in-depth study of the network structure of different phosphate based and borosilicate glasses and its evolution at high temperatures. Employing a range of advanced solid state NMR methodologies, complemented by the results of XPS, the structural motifs on short and intermediate length scales are identified. For the phosphate based glasses, at temperatures above the glass transition temperature Tg, structural relaxation processes and the devitrification of the glasses were monitored in situ employing MAS NMR spectroscopy and X-ray diffraction. Dynamic species exchange involving rapid P-O-P and P-O-Al bond breaking and reforming was observed employing in situ 27 Al and 31 P MAS NMR spectroscopy and could be linked to viscous flow. For the borosilicate glasses, an atomic scale investigation of the phase separation processes was possible in a combined effort of ex situ NMR studies on glass samples with different thermal histories and in situ NMR studies using high temperature MAS NMR spectroscopy including 11 B MAS, 29 Si MAS and in situ 29 Si{ 11 B} REAPDOR NMR spectroscopy. (authors)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-01-02

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

  14. COMMUNICATION DU CREDIT AGRICOLE - French version only

    CERN Multimedia

    2003-01-01

    La Direction du Crédit Agricole informe son aimable clientèle du CERN des jours et heures d'ouverture de l'agence du site de Prévessin à compter du mardi 14 janvier 2003 : 1. Horaires pour les opérations bancaires courantes 7 jours sur 7 et 24h/24 avec l'espace libre service bancaire. 2. Horaires conseil du mardi au vendredi - Mardi, de 9h. à 12h. et de 14h.15 à 16h.30. - Mercredi, jeudi et vendredi, de 9h. à 12h. et de 13h.30 à 16h.30. Deux collaboratrices au lieu d'une seront désormais présentes toute la journée du mardi au vendredi pour vous accueillir, vous informer et vous conseiller en crédits et placements (réception conseil sur rendez-vous). Autre nouveauté : les mêmes conseillers seront aussi à votre disposition le samedi, sur notre agence de Gex, de 8h.15 à 13h.05, notamment pour les études de financements habitat. La Direction et toute l'équipe de l'agence du Crédit Agricole vous souhaitent une excellent année 2003.

  15. Nouvelles du Centre Aéré de l’Association du Personnel du CERN

    CERN Multimedia

    Jardin d'enfants

    2015-01-01

    Cet été 2015, durant quatre semaines d’été, le Centre Aéré a accueilli plus de 40 enfants âgés de 4 à 6 ans. Devant le succès rencontré, et à la demande des parents, il a été décidé d’en doubler la capacité maximale. A l'été 2016, du 4 au 29 juillet, la structure pourra accueillir les enfants de 4 ans révolus et de moins de 7 ans (nés après le 31/07/2009 mais avant  01/07/2012). Les inscriptions se feront à la semaine durant le mois d'Avril 2016. Les programmes sont en cours d'élaboration cependant nous pouvons déjà vous communiquer le thème conducteur du centre qui sera : à la découverte d'un continent différent chaque ...

  16. Coordonnateur du bureau d'assistance | CRDI - Centre de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Résumé des fonctions. En tant que membre de l'équipe du Bureau d'assistance au sein de la Section du service à la clientèle (SSC), le coordonnateur du Bureau d'assistance offre au personnel du Centre et aux autres utilisateurs reconnus des installations TI du Centre un soutien de première ligne en matière d'utilisation ...

  17. La population du Moyen-Orient et de l'Afrique du Nord contribue ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    29 avr. 2016 ... Le degré d'apport au contenu varie grandement d'une population à l'autre. Si les habitants du Moyen-Orient et de l'Afrique du Nord (région MENA) utilisent Wikipédia, ils y contribuent cependant moins que les populations d'autres régions du monde. Le contenu au sujet de la région MENA est, le plus ...

  18. L'action du CRDI — le développement du secteur privé

    International Development Research Centre (IDRC) Digital Library (Canada)

    Cathy Egan

    Le CRDI est du nombre. Il reconnaît depuis longtemps la valeur de l'industrie, des échanges et du commerce comme moteurs de la croissance économique. Grâce au soutien concret qu'il a accordé au développement du secteur privé, le CRDI a appris que deux types d'aide peuvent porter fruit : améliorer le con- texte dans ...

  19. Sulphite metabolism; Metabolisme du sulfite

    Energy Technology Data Exchange (ETDEWEB)

    Fromageot, P; Chapeville, F [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    Although the formation of sulphite by micro-organisms was observed as early as 1914 by Neuberg, it was only in 1932 that Nightingale showed it to be present inside cells, in the case of tomato leaf stalks, its formation being due to the reaction: SO{sub 3}H{sup -} + (S{sub 2}O{sub 3}){sub 2}{sup --} {yields} S{sub 2}O{sub 3}{sup --} + O{sub 3}S{sub 2}O{sub 3}{sup --}. The presence of the thiosulphate formed was shown by the high refractive index of its barium salt. Today we have a certain amount of data concerning the formation and use of sulphite in the living cell, even through the knowledge is still incomplete. In this article we will describe and discuss the facts which are known, with particular reference to the oxidation of sulphite. (author) [French] Si la formation de sulfite par des micro-organismes a ete observee des 1914 par Neuberg, sa presence a l'interieur des cellules a ete demontree pour la premiere fois par Nightingale en 1932, dans des tiges et des feuilles de tomates, par la reaction: SO{sub 3}H{sup -} + (S{sub 2}O{sub 3}){sub 2}{sup --} {yields} S{sub 2}O{sub 3}{sup --} + O{sub 3}S{sub 2}O{sub 3}{sup --}. Le thiosulfate forme etait mis en evidence par l'indice de refraction eleve de son sel de baryum. Aujourd'hui on possede un certain nombre de donnees, cependant encore tres incompletes, sur la formation du sulfite et son utilisation par la cellule vivante. Dans cet expose nous decrirons et discuterons quelques-unes de ces acquisitions, tout particulierement celles relatives a l'oxydation du sulfite. (auteur)

  20. Monnaie du commun et revenu social garanti

    OpenAIRE

    Baronian, Laurent; Vercellone, Carlo

    2015-01-01

    Le but de cet article est de poser les bases d’une approche de la monnaie du commun à partir d’une interrogation évincée par la théorie économique des biens communs. Notre analyse de la relation entre monnaie et théorie du commun s’articulera en trois parties. Dans la première, il s’agit d’établir une conception dynamique du commun au singulier dans laquelle la question de la monnaie et des mutations de la division du travail occupe une place centrale. Cette démarche fondée sur la triade trav...

  1. Paysans du Brésil

    Directory of Open Access Journals (Sweden)

    Dominique Temple

    2007-01-01

    Full Text Available Eric Sabourin, « Paysans du Brésil : Entre échange marchand et réciprocité » Paris, Editions Quae, 241p, 30 euros, (préface de Maxime Haubert, 2007Dans la présentation du livre, Maxime Haubert dit :«Cet ouvrage propose une analyse socio-anthropologique et agronomique des sociétés rurales et paysannes du Brésil et des transformations qu'elles ont connues ces dernières décennies, en particulier face aux interventions de l'Etat et à l'expansion du marché capitaliste (.... «Le livre pose d'abor...

  2. Daphne du Maurier' unustatud jutud / Udo Uibo

    Index Scriptorium Estoniae

    Uibo, Udo, 1956-

    2011-01-01

    Ajalehe "The Independent" teatel kavatseb kirjastus "Virago" maikuus avaldada Daphne Du Maurier lühiproosa kogumiku "Nukk" (The Doll), mille on koostanud tema loomingu suur austaja Ann Willmore ja mis sisaldab 13 unustatud ja seni avaldamata novelli

  3. Aux frontières du politique et du religieux

    Directory of Open Access Journals (Sweden)

    Frédéric Sylvanise

    2006-05-01

    Full Text Available The Autobiography of Miss Jane Pittman met en scène de manière spectaculaire deux figures de leadership noir-américain au XIXe siècle (Ned et au XXe siècle (Jimmy. Ned, fils adoptif de Jane Pittman, se rebaptise Professor Douglass en hommage au leader abolitionniste Frederick Douglass. S’il est fondamentalement laïc (il est instituteur, le texte lui confère néanmoins une dimension religieuse, notamment dans le chapitre intitulé « The Sermon at the River » , qui renvoie à la fois à Moïse (le fleuve et à Jésus (le sermon sur la montagne. Abattu par un tueur à gages, Ned est un martyr dont l’histoire était déjà écrite. Le personnage de Jimmy, attendu par toute une communauté comme le messie (alors que lui aussi est un laïc et un homme qui perd la foi, s’inscrit dans la même histoire. Lettré, éloquent et impliqué dans le mouvement pour les droits civils, il est assassiné comme son prédécesseur. Dans les deux cas, le texte lie donc le politique et le biblique comme s’il ne faisait qu’un : être un leader politique, c’est être un preacher et un messie qui guide le peuple. Il est possible de lire l’évocation de ces deux hommes à la lumière d’une certaine actualité. Ned et Jimmy connaissent en effet un sort proche de celui de Malcolm X et de Martin Luther King, récemment assassinés au moment de l’écriture de The Autobiography of Miss Jane Pittman. C’est l’histoire de la répression du leadership noir, au travers du portrait de deux de ses avatars, qui peut donc se lire en creux ici.

  4. Complications du traitement traditionnel des fractures : aspects ...

    African Journals Online (AJOL)

    Tous les patients reçus avec des complications du traitement traditionnel des fractures ont été inclus dans ce travail. Le diagnostic des lésions était clinique et radiologique. Nous avions reçu 51 patients porteurs de complications suite à des traitements de médecine traditionnelle, soit 13,7% du total des patients hospitalisés ...

  5. Le désordre du monde

    African Journals Online (AJOL)

    sulaiman.adebowale

    Le début du XXIe siècle se caractérise par l'accumulation et la consécution ..... Unis a présidé à la naissance aux forceps de cet outil d'équilibre du monde en ... De toute évidence, l'ONU reste l'instrument qui a marqué le siècle dernier,.

  6. W. E. B. Du Bois: A Dynamic Communicator and Cultural Iconoclast.

    Science.gov (United States)

    Reppert, James E.

    This paper presents a biographical sketch of the prolific African-American writer and sociologist W.E.B. Du Bois, designed as an instructional unit in an introduction to mass communication course which can help make students aware of the roles played by ethnic minorities in shaping American and world media. The paper provides numerous details of…

  7. College of DuPage District 502 Educational Needs Assessment (Total Sample Summary).

    Science.gov (United States)

    Rice, Gary

    In spring 1987, the Gallup Organization conducted a telephone survey for the College of DuPage (COD) in Illinois to determine community perceptions of the college's role in the community; community awareness of COD and its competitors; perceptions of current college services; importance of factors in selecting an educational program; interest in…

  8. Pru du 2S albumin or Pru du vicilin?

    Science.gov (United States)

    Garino, Cristiano; De Paolis, Angelo; Coïsson, Jean Daniel; Arlorio, Marco

    2015-06-01

    A short partial sequence of 28 amino acids is all the information we have so far about the putative allergen 2S albumin from almond. The aim of this work was to analyze this information using mainly bioinformatics tools, in order to verify its rightness. Based on the results reported in the paper describing this allergen from almond, we analyzed the original data of amino acids sequencing through available software. The degree of homology of the almond 12kDa protein with any other known 2S albumin appears to be much lower than the one reported in the paper that firstly described it. In a publicly available cDNA library we discovered an expressed sequence tag which translation generates a protein that perfectly matches both of the sequencing outputs described in the same paper. A further analysis indicated that the latter protein seems to belong to the vicilin superfamily rather than to the prolamin one. The fact that also vicilins are seed storage proteins known to be highly allergenic would explain the IgE reactivity originally observed. Based on our observations we suggest that the IgE reactive 12kDa protein from almond currently known as Pru du 2S albumin is in reality the cleaved N-terminal region of a 7S vicilin like protein. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Les effets du changement climatique dans le bassin du Congo : la ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    22 avr. 2016 ... Dans le bassin du fleuve Congo, plus de 80 % des habitants vivent exclusivement de l'agriculture, de la pêche, de l'élevage et de la cueillette, qui sont des activités largement tributaires du climat.

  10. Engagez-vous, devenez délégué(e) du personnel du CERN

    CERN Multimedia

    Staff Association

    2017-01-01

    Dans notre ECHO N° 275, nous avons annoncé les élections à venir au Conseil du personnel du CERN. Dans le présent ECHO, nous vous informons du lancement du processus des élections qui débute par le dépôt des candidatures. Tous les titulaires, boursiers et associés, qui sont aussi membres de l’Association du personnel, peuvent s’engager et déposer leur candidature entre le 11 septembre à 08 h 00 et le 13 octobre 2017 à 17 h 00. N’hésitez plus, remplissez le formulaire de candidature, présentez-vous aux élections au Conseil du personnel afin de pouvoir représenter et défendre vos collègues du personnel du CERN. ÊTRE DÉLÉGUÉ(E), C’EST QUOI ? Poser la question à plusieurs d...

  11. Color centers of a borosilicate glass induced by 10 MeV proton, 1.85 MeV electron and 60Co-γ ray

    International Nuclear Information System (INIS)

    Du, Jishi; Wu, Jiehua; Zhao, Lili; Song, Lixin

    2013-01-01

    Optical absorption spectra, electron paramagnetic resonance (EPR) spectra, Raman spectra of a borosilicate glass after irradiation by 10 MeV proton, 1.85 MeV electron and 60 Co-γ ray were studied. The process of irradiation inducing color centers in the glass was discussed. The band gap of the glass before and after 60 Co-γ ray irradiation was studied using Mott and Davis's theory, and it was found that calculated change of the band gap introduced a paradox, because Mott and Davis's theory on the band gap cannot be adopted in the study on the irradiated glass. - Highlights: ► All the three types of irradiation induce the same types of color centers. ► Calculated change of the band gap introduced a paradox. ► Mott and Davis's theory on band gap cannot be adopted in the irradiated glass

  12. Kinetic Rate Law Parameter Measurements on a Borosilicate Waste Glass: Effect of Temperature, pH, and Solution Composition on Alkali Ion Exchange

    International Nuclear Information System (INIS)

    Pierce, Eric M.; McGrail, B PETER.; Icenhower, J P.; Rodriguez, Elsa A.; Steele, Jackie L.; Baum, Steven R.

    2004-01-01

    The reaction kinetics of glass is controlled by matrix dissolution and ion exchange (IEX). Dissolution of an alkali-rich simulated borosilicate waste glass was investigated using single-pass flow-through (SPFT) experiments. Experiments were conducted as a function of temperature, pH, and solution composition by varying the SiO 2 (aq) activity in the influent solution. Results showed that under dilute conditions matrix dissolution increased with increasing pH and temperature, and decreased with increasing SiO 2 (aq) activity. IEX rates decreased with increasing pH and temperature, and increased with increasing SiO 2 (aq) activity. Over the solution composition range interrogated in this study the dominant dissolution mechanism changed from matrix dissolution to IEX. These results suggest that ''secondary'' reactions may become dominant under certain environmental conditions and emphasize the need to incorporate these reactions into dissolution rate models

  13. Elaboration and experimental study of the Borosilicate glass GP 98/12 for the vitrification of the radioactive wastes of KfKarlsruhe Centre (R.F.A.)

    International Nuclear Information System (INIS)

    Ghezal, A.

    1987-09-01

    The transformation into a vitrified block of highly radioactive liquid wastes is actually the best solution for the storage in long run. In West Germany, the research institute in the field of nuclear energy (KfK) has been oriented in this way by developing industrial processes of vitrification and by following studies on the behaviour of the final products. For the fission products, the chosen glasses present good stability characteristics and are used as a first barrier during confinement. Our work, which is part of the research program on radioactive waste vitrification, consists of preparing borosilicate glass GP 98/12 and studying physical and chemical characteristics. We have also contributed to the development and the realization of glass blocks sampling system prepared at pilot scale

  14. Aux marges du monde arabe

    Directory of Open Access Journals (Sweden)

    Hélène Thiollet

    2004-09-01

    Full Text Available L’étude des migrations contemporaines des Érythréens vers le Yémen au tournant des années quatre-vingt-dix permet d’observer les transformations des dynamiques régionales à l’œuvre dans le monde arabe. Les migrations sont un phénomène sensible aux différents aspects (politiques, économiques, culturels, géographiques de l’intégration régionale. Celle si est envisagée dans cet article à travers une approche doublement marginale : -la marginalité géographique de l’Érythrée arabo-africaine et du Yémen, économi­quement isolé dans la péninsule Arabique, -l’étude des migrations formelles et informelles, élément souvent marginal dans l’étude des institutions et des échanges qui constituent un système régional intégré. Cette étude est fondée sur une série d’entretiens menés au Yémen entre février et avril 2002 auprès des administrations yéménites et de la population érythréenne.

  15. Cirque du Monde as a health intervention

    Science.gov (United States)

    Fournier, Cynthia; Drouin, Mélodie-Anne; Marcoux, Jérémie; Garel, Patricia; Bochud, Emmanuel; Théberge, Julie; Aubertin, Patrice; Favreau, Gil; Fleet, Richard

    2014-01-01

    Abstract Objective To present Cirque du Soleil’s social circus program, Cirque du Monde, to explore its potential as a primary health care tool for family physicians. Data sources A review of the literature in PubMed, the Cochrane Library, PsycINFO, LaPresse, Eureka, Google Scholar, and Érudit using the key words circus, social circus, Cirque du Monde, and Cirque du Soleil; a Montreal-based initiative, Espace Transition, modeled on Cirque du Monde; and personal communication with Cirque du Soleil’s Social Circus Training Advisor. Study selection The first 50 articles or websites identified for each key word in each of the databases were examined on the basis of their titles and abstracts in the case of articles, and on the basis of their titles and page content in the case of websites. Articles and websites that explored an aspect of social circuses or that described an intervention that involved circuses were then retained for analysis. Because all literature on social circuses was searched, no criterion for year of publication was used. Synthesis No articles on the social circus as a health intervention were found. One study on the use of the circus as an intervention in schools was identified. It demonstrated an increase in self-esteem in the children who took part. One study on the use of the circus in a First Nations community was found; it contained nonspecific, qualitative findings. The other articles identified were merely descriptions of social circuses. One website was identified on the use of the social circus to help youth who had been treated in a hospital setting for major psychiatric disorders to re-enter the community. The team in the pediatric psychiatry department at Centre Hospitalier Universitaire Sainte-Justine, the children’s hospital in Montreal, Que, was contacted; they were leading this project, called Espace Transition. The unpublished preliminary findings of its pilot project demonstrate substantial improvements in overall patient

  16. Établissements recevant du public

    CERN Document Server

    2014-01-01

    Synthèse pour les installations électriques, des règles de sécurité contre les risques d’incendie et de panique dans les établissements recevant du public (ERP), selon l’arrêté du 25 juin 1980 modifié. L'ouvrage traite à la fois des dispositions communes aux établissements du 1er groupe (1ère à 4ème catégorie), du 2ème groupe (5ème catégorie) et des règles particulières applicables aux différents types d'établissements (structures d'accueil pour personnes âgées ou handicapées, hôtels, magasins de vente, restaurants et débit de boisson, établissements de soins, administration, châpiteaux, etc...) Sont ainsi notamment traités, dans le cadre des dispositions communes aux établissements du 1er groupe, pour les installations électriques normales : les installations des appareils, tableaux et canalisations, les locaux électriques et installation de machines, l'éclairage normal des locaux accessibles au public, le chauffage et la ventilation, l'installation d'eau chaude sanita...

  17. Thermal decomposition of biphenyl (1963); Decomposition thermique du biphenyle (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Clerc, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-06-15

    The rates of formation of the decomposition products of biphenyl; hydrogen, methane, ethane, ethylene, as well as triphenyl have been measured in the vapour and liquid phases at 460 deg. C. The study of the decomposition products of biphenyl at different temperatures between 400 and 460 deg. C has provided values of the activation energies of the reactions yielding the main products of pyrolysis in the vapour phase. Product and Activation energy: Hydrogen 73 {+-} 2 kCal/Mole; Benzene 76 {+-} 2 kCal/Mole; Meta-triphenyl 53 {+-} 2 kCal/Mole; Biphenyl decomposition 64 {+-} 2 kCal/Mole; The rate of disappearance of biphenyl is only very approximately first order. These results show the major role played at the start of the decomposition by organic impurities which are not detectable by conventional physico-chemical analysis methods and the presence of which accelerates noticeably the decomposition rate. It was possible to eliminate these impurities by zone-melting carried out until the initial gradient of the formation curves for the products became constant. The composition of the high-molecular weight products (over 250) was deduced from the mean molecular weight and the dosage of the aromatic C - H bonds by infrared spectrophotometry. As a result the existence in tars of hydrogenated tetra, penta and hexaphenyl has been demonstrated. (author) [French] Les vitesses de formation des produits de decomposition du biphenyle: hydrogene, methane, ethane, ethylene, ainsi que des triphenyles, ont ete mesurees en phase vapeur et en phase liquide a 460 deg. C. L'etude des produits de decomposition du biphenyle a differentes temperatures comprises entre 400 et 460 deg. C, a fourni les valeurs des energies d'activation des reactions conduisant aux principaux produits de la pyrolyse en phase vapeur. Produit et Energie d'activation: Hydrogene 73 {+-} 2 kcal/Mole; Benzene 76 {+-} 2 kcal/Mole; Metatriphenyle, 53 {+-} 2 kcal/Mole; Decomposition du biphenyle 64 {+-} 2 kcal/Mole; La

  18. Sådan kan du bruge optioner og futures

    DEFF Research Database (Denmark)

    Kohl, Niklas

    2017-01-01

    Masterclass. Har du brug for at forsikre værdierne i din portefølje i en periode, hvor du forventer stor uro på finansmarkederne, kan du gøre det med optioner eller futures. Her kan du læse om de forskellige typer – og om de muligheder de giver dig.......Masterclass. Har du brug for at forsikre værdierne i din portefølje i en periode, hvor du forventer stor uro på finansmarkederne, kan du gøre det med optioner eller futures. Her kan du læse om de forskellige typer – og om de muligheder de giver dig....

  19. Science et technologie du collage

    CERN Document Server

    Cognard, Jacques

    2003-01-01

    L'Homme a su coller avant de savoir écrire et compter. Le collage est en effet l'une des premières techniques d'assemblage d'une structure que l'homme ait utilisée, technique qui n'est devenue science qu'au début du 20e siècle avec la fabrication des premières colles synthétiques. Cette science de l'adhésion a considérablement progressé ces dix dernières années et ce livre présente l'état actuel des connaissances en décrivant les progrès considérables réalisés dans la compréhension des phénomènes fondamentaux qui font qu'un collage tient bien et durablement. Après l'exposé des bases scientifiques nécessaires et des modèles théoriques récents, l'auteur introduit la distinction entre collages faibles et collages forts puis expose les difficultés rencontrées dans les cas pratiques, difficultés souvent dues à la complexité de la chimie des surfaces et des réactions surface-polymère. L'ouvrage se termine par la présentation de quelques applications récentes, en particulier dans...

  20. La moralité implicite du marché

    Directory of Open Access Journals (Sweden)

    Pierre-Yves Néron

    2010-05-01

    Full Text Available In this article, I put forward an approach to business ethics that focuses on the notion of “implicit morality of the market”. I therefore try to identify the main components of this implicit morality of the market and expose the advantages of taking such a stance to think about the obligations of firms. In order to do so, I try to shed some light, drawing on recent works by Joseph Heath, on the potential normative role of the concept of market failures as articulated in economic theory. I finish by examining three problems that this approach is facing.RÉSUMÉDans cet article, je mets en avant une approche de l’éthique du commerce centrée sur la notion de « moralité implicite du marché ». J’essaie d’identifier les grands traits de cette moralité impli- cite du marché en plus d’exposer les avantages d’adopter une telle approche pour penser les obli- gations des firmes. Pour ce faire, je tente, en m’inspirant de travaux récents de Joseph Heath, de mettre en lumière le rôle proprement normatif que peut jouer le concept de défaillances des mar- chés tel que développé dans la théorie économique. Je termine en examinant trois problèmes auxquels fait face l’approche proposée ici.

  1. Accroissement du recours aux politiques fiscales dans la lutte ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Incidence de la hausse des taxes sur le tabac et du prix des produits du tabac en Ukraine, en Russie et au Bélarus. La recherche destinée aux responsables des politiques de l'Ukraine, de la Russie et du Bélarus mettra en évidence la façon dont les mesures de taxation des produits du tabac peuvent contribuer.

  2. Couzeix – Les Terres du Puy Dieu

    OpenAIRE

    Maniquet, Christophe

    2013-01-01

    Identifiant de l'opération archéologique : 122281 Date de l'opération : 2005 (EX) Dans le cadre du projet de construction d'un lotissement constitué de trois pavillons au lieu-dit « Les Terres du Puy Dieu », un diagnostic archéologique a été prescrit par le service régional de l'Archéologie. En effet, plusieurs sites archéologiques avaient été inventoriés à proximité immédiate de la zone d'intervention. On notera, en particulier, la découverte en 1982, près du Puy Dieu, au cours de travaux de...

  3. Profils des porteurs du VIH/SIDA au début du traitement ...

    African Journals Online (AJOL)

    But : Décrire les profils des porteurs de VIH/sida au début du traitement antirétroviral. Matériels et méthode: Les dossiers des porteurs du VIH/sida de la région maritime ont été analysés de mai 2008 à avril 2009 par le comité thérapeutique. Résultats: Parmi les 641 dossiers analysés, 67,40% venaient du district de Yoto.

  4. Distribution spatiale du singe à ventre rouge, Cercopithecus ...

    African Journals Online (AJOL)

    danger et endémique du Dahomey Gap est très peu documenté au Togo. Pour connaître sa ..... chaque secteur prospecté ainsi que celui du complexe en entier. ..... 2008-009 portant loi-cadre sur l'environnement au Togo. JO du 06 juin. 2008.

  5. Directeur, Gestion du risque et audit interne | CRDI - Centre de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Résumé des fonctions En qualité de dirigeant principal de l'audit (DPA), ... président du Centre et au président du Comité des finances et de l'audit une assurance et des ... Il fournit des services de gestion du risque organisationnel et d'autres ...

  6. Webzzle : paradoxal confort du confinement.

    Directory of Open Access Journals (Sweden)

    Marc Dumont

    2007-06-01

    Full Text Available La plupart des agences de « news » technologiques viennent de se faire l’écho du développement de Webzzle , un nouveau moteur de recherche dit « collaboratif ». Ce cas est tout à fait intéressant parce qu’il permet de pointer rapidement quelques grands enjeux du Web 2 que risquent souvent de dissimuler la jungle sémantique et l’enthousiasme qui l’entourent. Pour quelles raisons ? Rappelons d’abord les deux principales perspectives ouvertes par cette nouvelle ...

  7. Krypton purification (1961); Purification du krypton (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Larher, Y [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Institut Fourier, 38 - Grenoble (France)

    1961-07-01

    The amount of xenon in otherwise very pure krypton can be reduced from 1.5 to 0.0025 per cent approximately by passage through an activated carbon column at dry-ice temperature. The circulation of the krypton is effected by condensing at -196 deg. C and then evaporating. (author) [French] Le taux de xenon dans du krypton par ailleurs tres pur est ramene de 1,5 pour cent a 0,0025 pour cent environ au cours d'un passage a travers une colonne de charbon actif a la temperature de la carboglace. La circulation du krypton se fait par condensation a -196 deg. C, puis evaporation. (auteur)

  8. Effets de la microdose sur la production du niébé, du mil et du ...

    African Journals Online (AJOL)

    respectivement pour le sorgho, le mil et le niébé comparativement au témoin. La microdose a été .... Les prix utilisés sont celui du marché local au moment des semis pour les engrais soit 17500 FCFA pour NPK et ..... Projet « Transfert de la.

  9. L’ombre du Condor

    Directory of Open Access Journals (Sweden)

    Franck Gaudichaud

    2003-09-01

    Full Text Available Si l’on observe aujourd’hui, avec un regard d’historien, le Cône Sud à la fin des années soixante soixante-dix et que par, la suite, on tourne une page de quelques années, pour fixer la même partie du monde, le constat est sans appel : le sous-continent latino-américain est passé, en général, d’une phase de forte mobilisation et politisation sociale, montée en puissance de partis et organisations révolutionnaires, surgissements de gouvernements populistes de gauche ou progressistes – appelant à une rupture avec l’impérialisme –, à un reflux généralisé du mouvement ouvrier, une ère de violence politique étatisée, la destruction massive de tous les espaces d’expression et de participation démocratiques, l’écrasement physique et idéologique sans relâche des militants et mouvements révolutionnaires, la mise en place de modèles économiques capitalistes dirigistes puis/ou néolibéraux. Que s’est-il passé ? Quel fil conducteur a été rompu et par quels moyens l’Amérique Latine a été conduite à ce reflux des luttes sociales ? Pour répondre à cette question, nous nous contenterons dans cet article de focaliser notre objectif sur un aspect spécifique et essentiel de ce retournement de tendance que vit alors l���Amérique Latine : celui de la mise en place d’un terrorisme d’Etat contre-révolutionnaire transnational, appuyé par l’impérialisme américain, nommé « l’Opération Condor ». Dans cet article, il s’agit de montrer le fonctionnement d’un terrorisme hégémonique dont l’impact sur les sociétés latino-américaines est considérable en termes de destruction du mouvement social, des activités culturelles et de l’ensemble de la vie sociale et politique qui restent marquées, encore aujourd’hui à des degrés divers, par la violence, la peur et l’atomisation structurelle.Si miramos hoy en día, desde una perspectiva histórica, el Cono Sur hacia finales de

  10. Étude de la qualité des eaux usées des deux retenues du bassin du ...

    African Journals Online (AJOL)

    SARAH

    31 mai 2017 ... Gourou au carrefour de l'Indénié à Abidjan en 2012. 11138. Journal of Applied .... retenues sont nées du projet de gestion intégrée du bassin du Gourou (CI-FAD, ..... Contrôle de la qualité microbiologique des eaux usées ...

  11. 26 Calcul multi-caractéristique du coût du non-qualité via la fonction ...

    African Journals Online (AJOL)

    PR BOKO

    Le coût du non - qualité (CNQ) est un indicateur permettant l'estimation de la marge ..... multicritères de Taguchi en fonction de l'évolution du poids et capacité du ... A Scheduling Example; International Journal of Information and Management.

  12. Le Flaubert de Charles Du Bos

    Directory of Open Access Journals (Sweden)

    Jacques Neefs

    2009-01-01

    Full Text Available Charles Du Bos a porté une attention constante à l’œuvre de Flaubert (à l’exclusion de Bouvard et Pécuchet qui semble ne pas exister pour lui, à Madame Bovary et à L’Éducation sentimentale en particulier. La mise en relation de son étude : « Sur le milieu intérieur chez Flaubert », écrite en 1921, avec des textes du Journal de 1923 et de 1937, les rapprochements avec Gogol, Thomas Hardy, Tolstoï, Baudelaire, Henry James qui traversent les écrits de Du Bos, permettent de suivre ce que celui-ci décrit comme « l’expérience spirituelle » d’une matérialité comprise dans la conquête de la triple exigence du Beau, du Vivant et du Vrai. Du Bos décèle la force de l’œuvre de Flaubert dans la « disproportion » du style, et dans la puissance d’absorption qui fait la densité de cette prose, et qui désigne un extraordinaire travail de conversion. L’obscure expérience spirituelle ainsi poursuivie est celle d’un absolu de l’art, expérience paradoxale d’un « mystique qui ne croit à rien » (comme se désignait Flaubert lui-même, que le critique lie à une interrogation sur sa propre conversion.Charles Du Bos devoted an unflagging attention to Flaubert’s work (except for Bouvard et Pécuchet, which, apparently, according to him did not exist, to Madame Bovary and in particular L’Éducation sentimentale. The connection between his essay “Sur le milieu intérieur chez Flaubert”, written in 1921, and extracts from his Journal, from 1923 to 1937, the comparisons with Gogol, Thomas Hardy, Tolstoy, Baudelaire, and Henry James that run through the writings of Du Bos, allow us to follow what he terms “the spiritual experience” of a materiality encompassed in the conquest of the triple demand of the Beautiful, the Living, the Truth. Du Bos detects the power of Flaubert’s work in the “disproportion” of his style, and the power of absorption that forms the density of his prose, showing an

  13. 25 years of the Conseil du Léman

    CERN Multimedia

    2012-01-01

    On 30 June, the Conseil du Léman will celebrate its 25th anniversary. The Conseil, which comprises representatives of the French departments of Ain and Haute-Savoie and the Swiss cantons of Geneva, Vaud and Valais, was set up to promote cross-border cooperation in the Lake Geneva region.   To celebrate its quarter centenary, the Conseil will be holding a day of discussions and activities, including a round-table discussion in CERN’s Globe of Science and Innovation. You are cordially invited to participate in the round-table discussion, which will be led by prominent representatives of each of the Conseil’s five constituent authorities: Round-Table Discussion The Challenges of Cross-border Cooperation: A look back at the role of the Conseil du Léman over the past 25 years. Saturday, 30 June 9.30 am - 12.30 pm Globe of Science and Innovation During the afternoon, activities for the general public will be organised in the park of the Château de ...

  14. Analyses de la dégradation du lac Kinkony pour la conservation du ...

    African Journals Online (AJOL)

    Le lac Kinkony fait partie des habitats clefs pour la biodiversité du Complexe des ... provide favoured habitat for numerous endemic and endangered avian, fish ... on fauna is essential for developing regional conservation and natural resource ...

  15. Consolidation du leadership en recherche en écosanté en Asie du ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    1 juin 2016 ... Financée par le CRDI, l'Initiative de renforcement du leadership en recherche en écosanté en Asie du Sud‑Est appuie l'exécution, dans la région, de travaux de recherche qui visent à permettre de mieux comprendre les effets de la transformation de l'agriculture sur les écosystèmes et sur la santé humaine ...

  16. Accroissement de la compétitivité du Kenya dans l'économie du ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    La promulgation par le Kenya du Science, Technology and Innovation Bill, 2012 confirme l'intérêt et la volonté du gouvernement de mettre en oeuvre désormais un programme de développement fondé sur la science. La loi offre aussi au CRDI l'occasion d'appuyer le programme de recherche et de politiques de la nouvelle ...

  17. Effets du travail du sol sur le comportement chimique et biologique ...

    African Journals Online (AJOL)

    SARAH

    31 juil. 2017 ... RESUME. Objectif : L'objectif de cette étude est de comparer les effets de six techniques culturales de mise en place du blé tendre sur certaines propriétés chimiques et biologiques du sol et les conséquences sur le rendement grain et ses composantes dans la région «non chernozem» en 7ème années ...

  18. OGM : vers une définition commune du contenu du problème ?

    Directory of Open Access Journals (Sweden)

    Icart Jean-Claude

    2001-07-01

    Full Text Available Les divergences croissantes depuis des années entre experts, responsables économiques, et acteurs sociaux et « citoyens » au sujet des OGM, ont pu être analysées à juste titre, comme exprimant la difficulté de dégager une « définition commune du contenu du problème »1.

  19. Évaluation du nouveau programme d'études du College of Health ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Ces changements étaient jugés nécessaires pour préparer les professionnels de la santé aux nouvelles exigences de la prestation de services de santé décentralisés, pour juguler les nouvelles pandémies comme celles du VIH/sida et du virus Ébola, ainsi que pour répondre aux besoins des malades dans les zones ...

  20. Une force venant du futur chercherait à saboter l'expérience du LHC...

    CERN Multimedia

    Scappaticci, Bruno

    2009-01-01

    "A quelques jours de la reprise de l'expérience du LHC, on ne parle plus de la menace d'un trou noir, mais deux physicines souteinnent aujourd'hui une tout autres hypothèse: la nature, depuis le futur, va continuer de contrarier les travaux du Cern, afin d'éviter à l'Homme de mettre le doigt là où il ne faut pas..." (1.5 pages)

  1. Cartes infographiques du Symposium Afrique de l'Ouest et du Centre

    International Development Research Centre (IDRC) Digital Library (Canada)

    fdieudonne

    VILLES SÛRES ET INCLUSIVES | AFRIQUE DE L'OUEST ET DU CENTRE. Spécificités de violence, d'exclusion, et de lutte contre la criminalité. République démocratique du Congo: Taux de natalité par femme, en moyenne 10 enfants, très élevé. Exclusion sociale exacerbée : des jeunes enfants accusés de sorcellerie.

  2. Une mesure différente du bien-être : l'indice du bonheur national ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    À la lumière de ces données, le Centre for Bhutan Studies publiera, en 2011, un indice du BNB quantitatif. Cette subvention permettra à l'OPHI d'assister le Centre dans la synthèse et l'analyse des résultats de l'enquête de 2010. L'objectif : assurer la validité et la reconnaissance internationale de l'indice du BNB de sorte ...

  3. Maison du Peuple; Jean Prouvè

    DEFF Research Database (Denmark)

    Beim, Anne

    2017-01-01

    The chapter presents a deep analysis of Maison du Peuple, de Clichy in Paris by the French architect and manufacturer Jean Prouvè. The historical context of the original ideas behind the building and how and by which means it was constructed are being examined from a tectonic perspective....

  4. les cahiers du cread - Vol 101 (2012)

    African Journals Online (AJOL)

    Les importations subventionnees de genisses a haut potentiel laitier : Un echec du a l'absence de politique laitiere globale · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. Hamida Kheffache, Slimane Bedrani ...

  5. The case of Cirque du Soleil Dralion

    African Journals Online (AJOL)

    Cirque entered this landscape not by competing with the traditional circus, but by redefining it altogether (Leslie ... Amidst the decline in traditional travelling circuses in South Africa, the popularity of sold-out Cirque du Soleil ... about their motives in order to devise effective marketing strategies. Swanson, Davis and Zhao ...

  6. Picholine marocaine clones X Picholine du Languedoc

    African Journals Online (AJOL)

    SERVER

    2007-12-17

    Dec 17, 2007 ... marocaine" cultivar and the "Picholine du Languedoc" cultivar, the descendants and their parents were analysed using 35 ... marocaine" is the most dominant cultivar; more than 98% ... this proportion, a χ2 test was calculated to test the null hypothesis. ... a lethal or semi-lethal locus (Bradshaw and Stettler,.

  7. récolte du melon

    African Journals Online (AJOL)

    SARAH

    30 sept. 2015 ... In vivo, 600 ppm of calcium silicate, calcium hydroxide and calcium oxide inhibited ... En 2013, la production du melon au Maroc a été .... Ca(OH)2, l'oxyde de calcium CaO, le sulfate de calcium ...... rot disease complex.

  8. PREDICTION DE LA CROISSANCE DU BANANIER PLANTAIN ...

    African Journals Online (AJOL)

    Hornik K., Stinchcombe M., White H., Auer P. 1994. Degree of approximation results of feedforward networks approximating unknown mapping et their derivatives. Neur. Net. Comp., 6 : 1262 - 1275. Jannoyer M. 1995. Déterminisme du nombre d'or- ganes reproducteurs d'une inflorescence de bananier (Musa acuminata, ...

  9. A Study on the Role of Reaction Modeling in Multi-phase CFD-based Simulations of Chemical Looping Combustion; Impact du modele de reaction sur les simulations CFD de la combustion en boucle chimique

    Energy Technology Data Exchange (ETDEWEB)

    Kruggel-Emden, H.; Stepanek, F. [Department of Chemical Engineering, South Kensington Campus, Imperial College London, SW7 2AZ, London (United Kingdom); Kruggel-Emden, H.; Munjiza, A. [Department of Engineering, Queen Mary, University of London, Mile End Road, E1 4NS, London (United Kingdom)

    2011-03-15

    Chemical Looping Combustion is an energy efficient combustion technology for the inherent separation of carbon dioxide for both gaseous and solid fuels. For scale up and further development of this process multi-phase CFD-based simulations have a strong potential which rely on kinetic models for the solid/gaseous reactions. Reaction models are usually simple in structure in order to keep the computational cost low. They are commonly derived from thermogravimetric experiments. With only few CFD-based simulations performed on chemical looping combustion, there is a lack in understanding of the role and of the sensitivity of the applied chemical reaction model on the outcome of a simulation. The aim of this investigation is therefore the study of three different carrier materials CaSO{sub 4}, Mn{sub 3}O{sub 4} and NiO with the gaseous fuels H{sub 2} and CH{sub 4} in a batch type reaction vessel. Four reaction models namely the linear shrinking core, the spherical shrinking core, the Avrami-Erofeev and a recently proposed multi parameter model are applied and compared on a case by case basis. (authors)

  10. Etude de la transition ferroelectrique-ferroelastique du KD2PO4 forme du front de phase en fonction du gradient thermique

    OpenAIRE

    Kvítek, Zdeněk

    2010-01-01

    Etude de la transition ferroelectrique-ferroelastique du KD2PO4 forme du front de phase en fonction du gradient thermique The thesis explores complex process of first order transition of KD2PO4 crystal from tetragonal phase to ferroelectric - ferroelastic orthorhombic phase and back at temperature 209 K. The experimental set up of nitrogeneous cryostat allowes temperature and temperature gradient variations during simultaneous three axes optical sample observations, dielectric measurements. T...

  11. Néotoponymie contestée à Potchefstroom / Tlokwe (Province du Nord-Ouest, Afrique du Sud

    Directory of Open Access Journals (Sweden)

    Myriam Houssay-Holzschuch

    2010-09-01

    Full Text Available Illustration 1 - Extrait du site de la municipalité de Potchefstroom / TlokweSource : http://www.potch.co.za/newsarchive/streetnames.htmlIllustration 2- Potchefstroom (Afrique du SudAuteur : Béatrice Obry-Guyot, début décembre 2007.Illustration 3 - Extrait du plan Google Map de PotchefstroomSource : Google Map.La question toponymique en Afrique du Sud sur la longue durée porte sur deux thèmes essentiels porteurs de controverses : le plurilinguisme et le marquage symbolique et mémoriel du te...

  12. Crystalline phase, microstructure, and aqueous stability of zirconolite-barium borosilicate glass-ceramics for immobilization of simulated sulfate bearing high-level liquid waste

    Science.gov (United States)

    Wu, Lang; Xiao, Jizong; Wang, Xin; Teng, Yuancheng; Li, Yuxiang; Liao, Qilong

    2018-01-01

    The crystalline phase, microstructure, and aqueous stability of zirconolite-barium borosilicate glass-ceramics with different content (0-30 wt %) of simulated sulfate bearing high-level liquid waste (HLLW) were evaluated. The sulfate phase segregation in vitrification process was also investigated. The results show that the glass-ceramics with 0-20 wt% of HLLW possess mainly zirconolite phase along with a small amount baddeleyite phase. The amount of perovskite crystals increases while the amount of zirconolite crystals decreases when the HLLW content increases from 20 to 30 wt%. For the samples with 20-30 wt% HLLW, yellow phase was observed during the vitrification process and it disappeared after melting at 1150 °C for 2 h. The viscosity of the sample with 16 wt% HLLW (HLLW-16) is about 27 dPa·s at 1150 °C. The addition of a certain amount (≤20 wt %) of HLLW has no significant change on the aqueous stability of glass-ceramic waste forms. After 28 days, the 90 °C PCT-type normalized leaching rates of Na, B, Si, and La of the sample HLLW-16 are 7.23 × 10-3, 1.57 × 10-3, 8.06 × 10-4, and 1.23 × 10-4 g·m-2·d-1, respectively.

  13. Lanthanide-activated Na5Gd9F32 nanocrystals precipitated from a borosilicate glass: Phase-separation-controlled crystallization and optical property

    International Nuclear Information System (INIS)

    Chen, Daqin; Wan, Zhongyi; Zhou, Yang; Chen, Yan; Yu, Hua; Lu, Hongwei; Ji, Zhenguo; Huang, Ping

    2015-01-01

    Highlights: • Na 5 Gd 9 F 32 nanocrystals embedded glass ceramics were fabricated for the first time. • Such glass ceramics were achieved by phase-separation-controlled crystallization. • Elemental mapping evidenced the segregation of activators into the Na 5 Gd 9 F 32 lattice. • Luminescent color could be tuned by controlling glass crystallization temperature. - Abstract: Lanthanide-activated cubic Na 5 Gd 9 F 32 nanocrystals were precipitated from a borosilicate glass with a specifically designed composition. The precursor glass is already phase-separated after melt-quenching, which is beneficial to the realization of the controllable glass crystallization for affording desirable size, morphology and activator partition. Elemental mapping in the scanning transmission electron microscopy evidenced that the segregation of lanthanide ions into the Na 5 Gd 9 F 32 lattice was in situ formed without the requirement of long-range ionic diffusion. Impressively, such fabricated glass ceramic co-doped with Yb 3+ /Er 3+ ions exhibited intense upconversion luminescence, which was about 500 times higher than that of the precursor glass, and its luminescent color could be easily tuned from red to green by controlling glass crystallization temperature. It is anticipated that such phase-separation synthesis strategy with precise control over nanostructure of glass ceramics offer a great opportunity to design other highly transparent nanocomposites with a wide range of tunable optical properties

  14. A Comparison of Modifications Induced by Li3+ and Ag14+ Ion Beam in Spectroscopic Properties of Bismuth Alumino-Borosilicate Glass Thin Films

    Directory of Open Access Journals (Sweden)

    Ravneet Kaur

    2013-01-01

    Full Text Available Ion irradiation effects on the glass network and structural units have been studied by irradiating borosilicate glass thin film samples with 50 MeV Li3+ and 180 MeV Ag14+ swift heavy ions (SHI at different fluence rates ranging from 1012 ions/cm2 to 1014 ions/cm2. Glass of the composition (65-x Bi2O3-10Al2O3-(65-y B2O3-25SiO2 (x = 45, 40; y = 20, 25 has been prepared by melt quench technique. To study the effects of ionizing radiation, the glass thin films have been prepared from these glasses and characterized using XRD, FTIR, and UV-Vis spectroscopic techniques. IR spectra are used to study the structural arrangements in the glass before and after irradiation. The values of optical band gap, Urbach energy, and refractive index have been calculated from the UV-Vis measurements. The variation in optical parameters with increasing Bi2O3 content has been analyzed and discussed in terms of changes occurring in the glass network. A comparative study of the influence of Li3+ ion beam on structural and optical properties of the either glass system with Ag14+ ion is done. The results have been explained in the light of the interaction that SHI undergo on entering the material.

  15. Properties of sodium borosilicate glasses/Al2O3 sintered composites containing fluorides. Gan Fukkabutsu hokei san natoriumu garasu to alumina fukugo shoketsutai no bussei

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Bonggi; Yasui, I [The Univ. of Tokyo, Tokyo (Japan). Inst. of Industrial Science

    1993-06-01

    Glass/alumina sintered composites were synthesized from sodium borosilicate glass powder containing fluorides like AlF3 and NaF3, and Al2O3, and change in material properties was examined. Glass compositions of B2O3 and Na2O greatly affected the crystal phase and material properties. Nephelin crystal phase was extracted by the reaction of Na2O, NaF2, SiO2 and Al2O3 when B/Na<1. Coefficient of thermal expansion increased with the increase of Na/Si ratio. The residual amount of fluorides of sintered materials in nitrogen atmosphere was higher than that of air, and differed with the type of fluoride. The F[sup -] of NaF is bonded with Si of glass network and forms quiet stable glass structure, whereas, F[sup -] of AlF3 reacts with Si[sup 4+] forming SiF4 which is vaporized. Sintering temperature and dielectric constant of sintered materials containing fluoride was lower than the sintered materials without fluorides addition, however, at a sintering temperature range of 100 to 150[degree]C, it was inferred that this was because of the increase in voids due to SiF4 formed in the reaction. 16 refs., 17 figs., 3 tabs.

  16. Sud du Sahara | Page 10 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Nakacho was one of just a handful of women at this artisanal mining site who had managed to break away from the roles generally ascribed to her gender to become a ... Trouver un juste équilibre entre s'occuper des enfants et générer des revenus est un problème auquel sont confrontées les mères autour du monde.

  17. Présentation du volume

    Directory of Open Access Journals (Sweden)

    Ana Zwitter Vitez

    2012-12-01

    Full Text Available Dans de nombreuses disciplines scientifiques, le discours parlé représente depuis quelques décennies un objet de recherche proéminent. Ce fait s’explique probablement par deux caractéristiques principales du discours parlé: la structure complexe de sa matérialité et les fonctions variées de différentes pratiques langagières. C’est pourquoi le présent numéro réunit les articles basés sur les approches actuelles du discours parlé et sur les pratiques langagières spécifiques. Le volume est introduit par deux articles interdisciplinaires: Peter Garrard et Ahmed Samrah présentent le domaine de la pathologie du langage en donnant une revue fouillée sur les approches actuelles de l’analyse linguistique lors de la détection de la maladie d’Alzheimer, tandis que Harry Hollien donne un aperçu structuré sur le domaine de la phonétique judiciaire destiné à dévoiler l’identité des locuteurs et de détecter la déception dans le discours parlé. Les analyses explorant l’acquisition du langage commencent par l’article de Katharina Zipser qui examine la progression de structures grammaticales en les mettant en comparaison avec la compétence des apprenants et continuent par l’étude de Meta Lah proposant une évaluation des documents audiovisuels proposés aux apprenants de langue étrangère. Vesna Požgaj Hadži, Damir Horga et Tatjana Balažic Bulc remettent en question la corrélation entre la compétence linguistique et la fluence linguistique auprès de locuteurs non-maternels et l'analyse de Gemma Santiago Alonso aborde l'acquisition de l'article défini dans le langage enfantin. Les articles suivants se réunissent autour du domaine de l'interprétation: Jana Zidar Forte présente une approche actuelle dans l'entrainement d'interprètes, Lea Burjan analyse les phénomènes issus de la pratique de l'interprétation juridique et Simona  Šumrada traite de la reformulation dans le discours de la traduction et de

  18. DU-AGG pilot plant design study

    International Nuclear Information System (INIS)

    Lessing, P.A.; Gillman, H.

    1996-07-01

    The Idaho National Engineering Laboratory (INEL) is developing new methods to produce high-density aggregate (artificial rock) primarily consisting of depleted uranium oxide. The objective is to develop a low-cost method whereby uranium oxide powder (UO[sub 2], U[sub 3]O[sub ]8, or UO[sub 3]) can be processed to produce high-density aggregate pieces (DU-AGG) having physical properties suitable for disposal in low-level radioactive disposal facilities or for use as a component of high-density concrete used as shielding for radioactive materials. A commercial company, G-M Systems, conducted a design study for a manufacturing pilot plant to process DU-AGG. The results of that study are included and summarized in this report. Also explained are design considerations, equipment capacities, the equipment list, system operation, layout of equipment in the plant, cost estimates, and the proposed plan and schedule

  19. L’écologie du coupable.

    Directory of Open Access Journals (Sweden)

    André Ourednik

    2006-04-01

    Full Text Available « Denn dass der Mensch erlöst werde von der Rache  : das ist mir die Brücke zur höchsten Hoffnung und ein Regenbogen nach langen Unwettern. » 1 Nous l’aurions presque oublié, en fouillant parmi les fondations du rapport moral au monde de nos sociétés, nous trouverons encore bien en place deux piliers érigés au cours du processus de la chrétienté : celui de l’ empathie et celui de la culpabilité . Le premier semble offrir le seul appui plausible à notre vivre ...

  20. DuPont Chemical Vapor Technical Report

    International Nuclear Information System (INIS)

    MOORE, T.L.

    2003-01-01

    DuPont Safety Resources was tasked with reviewing the current chemical vapor control practices and providing preventive recommendations on best commercial techniques to control worker exposures. The increased focus of the tank closure project to meet the 2024 Tri-Party Agreement (TPA) milestones has surfaced concerns among some CH2MHill employees and other interested parties. CH2MHill is committed to providing a safe working environment for employees and desires to safely manage the tank farm operations using appropriate control measures. To address worker concerns, CH2MHill has chartered a ''Chemical Vapors Project'' to integrate the activities of multiple CH2MHill project teams, and solicit the expertise of external resources, including an independent Industrial Hygiene expert panel, a communications consultant, and DuPont Safety Resources. Over a three-month time period, DuPont worked with CH2MHill ESH and Q, Industrial Hygiene, Engineering, and the independent expert panel to perform the assessment. The process included overview presentations, formal interviews, informal discussions, documentation review, and literature review. DuPont Safety Resources concluded that it is highly unlikely that workers in the tank farms are exposed to chemicals above established standards. Additionally, the conventional and radiological chemistry is understood, the inherent chemical hazards are known, and the risk associated with chemical vapor exposure is properly managed. The assessment highlighted management's commitment to addressing chemical vapor hazards and controlling the associated risks. Additionally, we found the Industrial Hygiene staff to be technically competent and well motivated. The tank characterization data resides in a comprehensive database containing the tank chemical compositions and relevant airborne concentrations

  1. Autour du paradigme d’écotourisme

    Directory of Open Access Journals (Sweden)

    Anne-Laure Transler

    2008-02-01

    Full Text Available L’écotourisme ouvre un cadre conceptuel original qui permet d’envisager des démarches renouvelées de développement à partir des revenus issus de consommations touristiques mieux réfléchies et organisées, susceptibles de soutenir des initiatives de développement local s’inscrivant dans un projet global de développement durable. Variante douce du tourisme, loin du tourisme de masse, le champ de l’écotourisme s’étend aux confins du tourisme de nature, du tourisme culturel et des pratiques scientifiques et sportives de plein air. Une définition de l’écotourisme peut être proposée à partir des six points suivants : 1/ nature et culture, 2/ le bien-être des sociétés hôtes, 3/ des touristes responsables, 4/ la participation des sociétés hôtes, 5/ la durabilité, 6/ l’art de la rencontre.Ecotourism provides an original conceptual framework that enables approaches to development that are better able to provide a more equitable distribution of income, as well as better organized and thought through initiatives which are more likely to promote a holistic sustainable local development. With somewhat less negative impact than normal tourism, considerably less that mass tourism, ecotourism can encompass nature tourism, cultural tourism, scientific exploration, and even outdoor sports... A definition of ecotourism should take into account the following six points: 1/ nature and culture, 2/ the welfare of the host community, tourists acting responsibly, 3/ participation by the local community, 5 / sustainability , 6/ promotion of cultural exchanges

  2. Le cas du Brésil

    International Development Research Centre (IDRC) Digital Library (Canada)

    pwust

    important volet des activités de coopération du Brésil dans les pays en développement, ...... attention à l'Amérique latine ou aux Caraïbes, malgré la priorité accordée à .... prudente et sélective face aux opérations triangulaires, afin d'éviter la ...

  3. Fès, la cybercapitale du Maroc

    International Development Research Centre (IDRC) Digital Library (Canada)

    Fès, la cybercapitale du Maroc. La ville de Fès est devenue un modèle primé en matière de mise en œuvre efficace des technologies de l'information et de la communication (TIC) dans les services publics d'un pays africain. ès, au Maroc. Dans une pièce renfermée datant des années 1950, des centaines de documents.

  4. Inventaire des champignons ectomycorhiziens du Maroc

    African Journals Online (AJOL)

    SARAH

    31 juil. 2014 ... RÉSUMÉ. Objectif : Le travail présenté ici a pour objectif de dresser, à partir de la bibliographie, l'inventaire des espèces ectomycorhiziennes du Maroc. Méthodologie et résultats : Les données sur les champignons, recueillies à partir de différents travaux publiés nous ont permis de réaliser un premier ...

  5. Les sens du musée

    Directory of Open Access Journals (Sweden)

    Laurent Grison

    1999-09-01

    Full Text Available Cet article, fondé sur l'exemple de la National Gallery de Londres, porte sur l'intégration dans le cadre urbain, l'aménagement et les dynamiques spatiales du lieu muséal. Sur le même thème, nous relatons un exercice réalisé avec des lycéens.

  6. Technostress et autres revers du travail nomade

    NARCIS (Netherlands)

    Popma, J.

    2013-01-01

    L'Internet et l'utilisation des ordinateurs portables, des téléphones mobiles et des tablettes ont accru l'importance du « travail nomade». Ce type de travail, sans contrainte de lieu ni de temps, peut entraîner, d’après ce working paper, une plus grande autonomie et une plus grande flexibilité pour

  7. KYSTE DERMOÏDE DU PLANCHER BUCCAL

    African Journals Online (AJOL)

    18 juin 2007 ... molle, indolore bien limitée, sessile ou pédiculée, lisse avec un aspect jaune caractéristique[10]. La palpation bidigitale, l'échographie associée à une ponc- tion cytologique, le scanner et au mieux l'IRM sont essen- tiels pour l'orientation étiologique devant toute lésion du plancher buccal [8]. En effet, l'IRM ...

  8. Administration des subventions du CRDI aux institutions :

    International Development Research Centre (IDRC) Digital Library (Canada)

    IDRC CRDI

    Comment puis-je réviser le budget de mon projet ? Le CRDI couvre-t-il les dépenses engagées en sus du montant de la subvention ? De quelle façon le CRDI transmet-il les fonds ? Mon institution doit-elle déposer les fonds reçus pour le projet dans un compte bancaire distinct ? Combien de temps faut-il au CRDI pour ...

  9. PersPectives du Programme acca

    International Development Research Centre (IDRC) Digital Library (Canada)

    à acca@crdi.ca. À propos du programme ACCA. Lancé en 2006, le programme Adaptation aux changements ... Nous pourrions y ajouter, par soucis d'équilibre, les « connus inconnus », c'est- à-dire les connaissances que nous ne ...... marocain m'a déjà dit ceci : « Je comprends vos préoccupations, mais mes questions ...

  10. Les Gammaridae (Crustaces, Amphipodes) du Massif Central

    NARCIS (Netherlands)

    Goedmakers, Annemarie

    1974-01-01

    Une prospection systématique des eaux courantes du Massif Central a permis de reconnaître le nombre d’espèces des Gammaridés présentes dans cette région. On a trouvé les espèces suivantes: Gammarus pulex (Linnaeus, 1758), G. fossarum Koch, 1835, et G. ibericus Margalef, 1951. G. ibericus, espèce

  11. L’écriture du temps dans Robinson Crusoe

    OpenAIRE

    Bulckaen, Denise

    2018-01-01

    “Le récit est une séquence deux fois temporelle... il y a le temps de la chose-racontée et le temps du récit (temps du signifié et temps du signifiant)”. Cette citation se trouve au début du chapitre que Genette consacre à “Ordre” dans Figures III. Elle s'applique à de nombreux romans, mais elle est particulièrement intéressante quand on considère le roman de forme autobiographique. Le décalage entre “le temps du signifié” et “le temps du signifiant” est plus ou moins grand selon les romans. ...

  12. Enfants du soleil histoire de nos origines

    CERN Document Server

    Brahic, André

    1999-01-01

    D'où venons-nous ? Comment le Soleil et la Terre sont-ils apparus ? Nous avons enfin atteint le moment où la science peut apporter des réponses de plus en plus précises, de plus en plus étonnantes. La Nature a décidément plus d'imagination que les hommes ! Depuis l'exploration spatiale, nous en avons plus appris sur notre système solaire et son origine en une génération qu'en quarante siècles. Là où l'on attendait l'uniformité, on a trouvé la plus grande diversité. André Brahic, qui a découvert les anneaux de Neptune, nous présente les multiples facettes du système solaire et nous raconte quatre milliards et demi d'années de son histoire. Les planètes sont les soeurs du Soleil. Nous sommes les enfants du temps et des étoiles. Sommes-nous seuls dans l'Univers ? Les astronomes commencent à apercevoir d'autres planètes autour de quelques soleils proches, Ils espèrent bientôt trouver d'autres Terres...

  13. Ksenia Pimenova, Les sources de savoirs. Le renouveau du bouddhisme et du chamanisme chez les Touvas de la Sibérie du Sud

    OpenAIRE

    Pimenova, Ksenia

    2013-01-01

    Cette thèse présente une étude comparative du « renouveau » post-soviétique du chamanisme et du bouddhisme tibétain (école Guélougpa) chez les Touvas, un des peuples autochtones de la Sibérie du Sud (Russie). Ce phénomène a lieu après des décennies de politique antireligieuse (dès la fin des années 1920 jusqu’aux années 1980) ayant abouti à la destruction de la communauté bouddhique et à la marginalisation du chamanisme. Nous analysons le chamanisme et le bouddhisme post-soviétiques comme deu...

  14. Ved du, hvad der er i dine varer, når du handler?

    DEFF Research Database (Denmark)

    Phillip, Anja; Smith, Viktor

    2016-01-01

    I supermarkedet på vej hjem køber du ind til madpakken. Ved kølemontren med pålæg ser du en pakke Gårdlykke Hønsesalat. ... Måske vælger du den uden at tænke nærmere over hvorfor, eller fordi emballagen og navnet får hønsesalaten til at fremstå lokal, hjemmelavet eller økologisk. ... Alt dette ba...... bakkes op af resultaterne fra årelang forskning på CBS, hvor universitetets forskergruppe Fair-Speak har undersøgt emballagernes måde at påvirke forbrugerne til at købe produktet....

  15. 98 Etude Comparative du Systeme Phonematique et Tonal des ...

    African Journals Online (AJOL)

    98. Etude Comparative du Systeme Phonematique et Tonal des. Deux Parlers: Le Yoruba du Nigeria et L'itsa Parle en. Republique du Benin. Ajani Akinwumi Lateef et Ayuba G. Ajibabi http://dx.doi./org/10.4314/ujah.v18i3.5. Résume. En ce début de l'époque ou la mondialisation et la coexistence des peuples dans le ...

  16. Carcinome du tube collecteur de Bellini: une nouvelle observation ...

    African Journals Online (AJOL)

    Le carcinome du tube collecteur de Bellini est un type très rare des carcinomes à cellules rénales (CCR), sa fréquence est inférieure à 1%. Il dérive de la partie distale du néphron, plus précisément du tube collecteur. Ses aspects morphologiques sont extrêmement variables, rendant son diagnostic difficile. Nous rapportons ...

  17. Bourse du CRDI aux chercheurs candidats au doctorat 2018 | CRDI ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Carrières · Communiquez avec nous · Plan du site. Abonnez-vous à notre bulletin pour recevoir les nouvelles du CRDI chaque mois. Abonnez-vous · Droits d'auteur · Éthique de la recherche · Politique de libre accès · Politique de confidentialité · Transparence · Utilisation du site Web. Suivez-nous; Facebook · Twitter ...

  18. Incorporation du coprah et des cuticules de cacao et d'arachide ...

    African Journals Online (AJOL)

    Incorporation du coprah et des cuticules de cacao et d'arachide dans l'aliment du ( tilapia du nil( ( Oreohromis niloticus , linné, 1758) eleve en etang : Effet sur la croissance et la composition biochimique.

  19. Matere z motnjami v duševnem razvoju

    OpenAIRE

    Kolarič, Sandra

    2015-01-01

    S pregledom tuje literature in že opravljenih raziskav v tujini smo v teoretičnem delu magistrske naloge zajeli značilnosti mater z motnjami v duševnem razvoju, dejavnike, ki vplivajo na uspešnost opravljanja materinske vloge, ter pravice oseb z motnjami v duševnem razvoju do starševstva, v povezavi z zakonodajo na slovenskem. Navedli smo vzroke za omejevanje reprodukcije pri ženskah z motnjami v duševnem razvoju in problematiko odvzema skrbništva materam z motnjami v duševnem razvoju nad otr...

  20. Autonomie du groupe restreint et performance

    Directory of Open Access Journals (Sweden)

    Elke Nissen

    2005-09-01

    Full Text Available Un groupe est autonome lorsqu'il prend lui-même en charge sa gestion (Abric, 1996 et lorsque celle-ci fonctionne bien. L'autonomie du groupe restreint est une caractéristique revendiquée dans le cadre actuel de l'expansion de dispositifs collaboratifs à distance entre apprenants. La question qui se pose alors est de savoir si un groupe restreint autonome est plus performant qu'un groupe moins autonome. L'autonomie d'un groupe d'apprentissage en ligne est-elle en relation avec la qualité de la réalisation de la tâche ? Est-elle en relation avec les progrès réalisés par les membres du groupe ? Dans le cadre de notre étude expérimentale, menée dans deux dispositifs pédagogiques différents (l'environnement d'apprentissage Babbelnet et une formation sur la plate-forme Acolad, des étudiants ont réalisé en groupes restreints, avec l'accompagnement d'un tuteur, une tâche de type actionnel – en l'occurrence une rédaction en langue étrangère (allemand ou anglais. Pour ce faire, ils disposaient d'aides méthodologiques et linguistiques dans l'environnement pédagogique en ligne. Ils ont interagi par le biais d'Internet au moyen de différents outils de communication. Une analyse de l'interaction qui a eu lieu dans chaque groupe, l'évaluation des rédactions réalisées conjointement, deux tests réalisés respectivement avant et après la phase de travail en groupe ainsi qu'un formulaire auto-administré nous permettent de mettre en lien l'autonomie des groupes, d'une part, et leur performance, voire leur apprentissage, d'autre part. Au vu de cette étude, il apparaît que l'autonomie du groupe n'a pas d'influence directe sur l'apprentissage des groupes restreints. En revanche, un rapport est visible entre l'appréciation du fonctionnement du groupe par ses membres et l'évolution de la performance des groupes.

  1. EQUILIBRE GLYCEMIQUE ET COMPLICATIONS MACROANGIOPATHIQUES DU DIABETE

    Directory of Open Access Journals (Sweden)

    Lyse BORDIER

    2017-05-01

    Full Text Available La question de l’efficacité d’un équilibre glycémique optimal dans la prévention des complications macroangiopathiques du diabète a fait l’objet d’une récente polémique. Si les faits sont clairs pour la microangiopathie notamment au cours du diabète de type 1, ils paraissent moins certains pour les complications cardiovasculaires du diabète de type 2. Cette constatation vient de l’intrication des autres facteurs de risque cardiovasculaires qui sont très fréquents chez ces patients. Cependant, les études de suivi sur une longue durée s’inscrivent en faveur de l’intérêt d’un bon équilibre glycémique sur les complications macroangiopathiques. Les résultats négatifs sur la mortalité de l’étude ACCORD et les inquiétudes concernant la rosiglitazone ont conduit à la mise en place d’études sur la sécurité d’utilisation des nouvelles molécules. Tous ces travaux ont abouti à la démonstration de l’absence de risque des iDPP-4 et de l’effet très positif de certaines molécules de la classe des analogues du GLP-1 et des iSGLT2.Il reste à espérer que la récente mise au point de l’Académie de Médecine soulignant que les complications du diabète de type 2 exigent une prévention multifactorielle qui passe obligatoirement par un contrôle optimisé de l'équilibre glycémique mette fin à une polémique inutile et dangereuse pour nos malades.

  2. Visite du Conseil des gouverneurs du CRDI en Afrique de l'Est ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    17 oct. 2017 ... La délégation dans la communauté La délégation à l'école féminine. La délégation avec les membres du Women's Group. Durant la visite, Jean Lebel et Molapo Qhobela, directeur général de la Fondation nationale de la recherche de l'Afrique du Sud, ont annoncé les projets retenus au Kenya et en ...

  3. Hausse du niveau des océans et perte de terres dans le delta du Nil ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    9 juin 2016 ... Au moyen de systèmes d'information géographique (SIG), des chercheurs subventionnés par le CRDI ont déterminé les zones littorales du delta du Nil qui pourraient être touchées par la hausse du niveau des océans. Il pourrait en résulter d'importantes pertes de terres d'ici 2100. Selon les plus récentes ...

  4. Le Silurien du Synclinorium de Moncorvo (NE du Portugal): Biostratigraphie et Importance Paléogéographique

    Czech Academy of Sciences Publication Activity Database

    Sarmiento, G. N.; Picarra, J. M.; Rebelo, J. A.; Robardet, M.; Gutiérrez-Marco, J. C.; Štorch, Petr; Rábano, I.

    1999-01-01

    Roč. 32, č. 5 (1999), s. 749-767 ISSN 0016-6995 R&D Projects: GA AV ČR Projects 351 et 421 du Programme International de Corrélation Géologique et au Projet Iberian Variscides du programme Europrobe, Projet 061-B0 du Programme de Coopération Scientifique et Technique Franco-Portugais Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.736, year: 1999

  5. Gestion intégrée du mildiou du mil en station au centre régional de ...

    African Journals Online (AJOL)

    user

    Le mil (Pennicetum glaucum) L.R.Br constitue 75% de la production céréalière du Niger. Cependant, son rendement est très faible dû à plusieurs types de contraintes. La maladie du mildiou du mil causé par un champignon Sclerospora graminicola (Sacc) Schroët, occupe une place importante. L'objectif de cette étude.

  6. Effect of lactose on intestinal absorption of calcium; Effet du lactose sur l'absorption intestinale du calcium

    Energy Technology Data Exchange (ETDEWEB)

    Labat, Marie-Louise

    1972-06-15

    Calcium absorption was immediately increased when lactose was administered in large amounts in the intestine of standard rats fed on a vitamin D diet. The same effect could be reproduced with lactulose, a glucid un-hydrolyzed by lactase and unabsorbed. The occurrence of a saturation process for high doses of calcium agrees with a biochemical process through a carrier; this process was not inhibited by actinomycin D, which does not agree with a 'de novo' synthesis of a calcium binding protein; yet activation of the preexisting protein cannot be excluded. The intestinal effect of lactose resulted in an inhibition of bone catabolism in the adult normocalcemic rat indicating a possible interference of thyrocalcitonin. Finally in the young rat, hypocalcemic by lack of vitamin D, on account of the lactose effect, calcium can be considered as a 'third messenger' in the chain of intracellular events between the interaction of the parathyroid hormone with the bone receptor and the expression of its activity. (author) [French] Le lactose introduit en quantite importante dans l'intestin augmente immediatement l'absorption du calcium chez le rat normal recevant par ailleurs de la vitamine D. Cet effet peut etre reproduit par le lactulose, glucide non hydrolyse par la lactase et non absorbe. L'apparition d'un phenomene de saturation pour les doses elevees de calcium s'accorde avec un mecanisme biochimique mettant en jeu un transporteur. Ce mecanisme n'est pas inhibe par l'actinomycine D, ce qui ne s'accorde pas avec une synthese 'de novo' de proteine transporteuse liant le calcium; on ne peut toutefois exclure une activation de cette proteine preexistante. L'effet intestinal du lactose a pour consequence l'inhibition du catabolisme osseux chez le rat adulte normocalcemique; ceci pose le probleme d'une intervention eventuelle de la thyrocalcitonine. Enfin, l'effet lactose nous permet d'attribuer au calcium le role de 'troisieme messager' dans la chaine d

  7. Sorrow Songs and Mbira Music: Du Bois, Mapfumo, and the Power of Music

    Directory of Open Access Journals (Sweden)

    Shelia Bassoppo-Moyo

    2012-10-01

    Full Text Available This article examines how music functions as social commentary on a group’s lived experience and as a tool to inform identity. Music is a data source that articulates historical and cultural contexts and can thus be utilized as social commentary to socially construct the identity of people of African ancestry and descent. The "sorrow songs" are the music genre created by slaves in the American South and were considered by W. E. B. Du Bois as the most important historical narrative for African Americans. In comparison, the more contemporary "mbira music" or Chimeranga (rebellion songs of Thomas Mapfumo, led the liberation struggle against colonialism in Zimbabwe. His music played a journalistic role in communicating with the masses. Several theoretical perspectives were employed in this study which included Du Bois’ inductive, empirical framework for the study of "the Negro problems"; Georg Simmel’s perspective on the role of music in society; Berger and Luckmann’s social construction of reality; and O'Shaughnessy and Stadler's social construction of the media. This paper uses content analysis to analyze the musical lyrics of both genres. These musical forms shed light on Du Bois' understanding of the veil and double consciousness within the African American experience and Zimbabwe's struggle for liberation respectively. Points of intersection between the two genres provide insight into how music creates knowledge and constructs social reality.

  8. Progrès de la connaissance du Congo, du Rwanda et du Burundi de 1993 à 2008

    Directory of Open Access Journals (Sweden)

    Henri Nicolaï

    2013-03-01

    Full Text Available Cette chronique, la vingt et unième d’une série qui a commencé avec l’année 1949, couvre la période 1993-2008 et a pour objectif de faire le point sur les progrès réalisés sur la connaissance du Congo (République démocratique du Congo, du Rwanda et du Burundi, dans le domaine de la géographie mais aussi dans les domaines des sciences naturelles et des sciences humaines qui peuvent fournir des données utiles ou indispensables aux géographes. Chaque référence bibliographique, livre ou article, est accompagnée d’un bref commentaire qui en retient les éléments principaux et surtout les faits ou les idées qui intéressent particulièrement les géographes. L’article comporte onze chapitres dont les plus importants concernent le milieu naturel, la géographie de la santé, la démographie, l’histoire (y compris l’histoire récente, la vie sociale et économique des campagnes traditionnelles et modernes, le secteur informel, les aspects de la vie urbaine. Les événements dramatiques qui se sont produits dans ces territoires africains au cours des quinze dernières années ont rendu la recherche sur le terrain particulièrement difficile tant pour les chercheurs nationaux que pour les chercheurs étrangers, ce qui se traduit notamment par une part de plus en plus importante des recherches menées en milieu urbain.This paper, the 21st issue of an edition of books and paper reviews on the knowledge of three countries of former Belgian Africa (DR Congo, Rwanda, and Burundi, covers the period 1993-2008. A short text for each reference points out the facts or ideas that are useful for geographers. The paper is composed of eleven sections. The most important are coping with the natural environment, health geography, population geography, history (including recent events, social and economic life in traditional and modern rural areas, informal economy, and urban geography. During the last sixteen years, conditions for field

  9. Un Genevois coopte a la tete du Front islamique du salut

    CERN Multimedia

    Merckling, N

    2002-01-01

    "Le Front islamique du salut (FIS), a nomme a la tete de ce parti fondamentaliste un resident genevois, Mourad Dhani, chois parmi trois candidats. Ce physicien algerien est arrive a Geneve il y a 14 ans pour travailler au CERN (1 page).

  10. La ministre Bibeau annonce la nomination du président du CRDI et ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    il y a 5 jours ... ... et chargé de cours associé à l'Université Griffith de South East Queensland, en Australie. Ancien professeur adjoint auxiliaire à la School of International and Public Affairs de l'Université Columbia, à New York; et ancien chercheur du Centre international pour la recherche en agroforesterie, à Nairobi.

  11. 73 Utilisation du SIG pour une réorganisation urbaine du centre-ville ...

    African Journals Online (AJOL)

    TOHOZIN

    restructuration des routes, du chemin de fer, des bâtis et des cours d'eaux. ... aussi la réalisation d'une mappe foncière qui est un instrument capital en matière ..... confirmer que le SIG, en tant qu'outil de décision et de planification a ...

  12. Résultats du traitement chirurgical des traumatismes du rachis à l ...

    African Journals Online (AJOL)

    incomplète était prédictive de bon pronostic P< 0,001. Les traumatismes du rachis cervical sont des urgences neurologiques qui mettent en jeu le pronostic vital et fonctionnel des patients. Mots clés : Traumatisme, rachis, traitement. The purpose of this series was to describe the results of surgical treatment of spinal injury.

  13. ETUDE DU COMPORTEMENT MECANIQUE DU BETON CELLULAIRE AUTOCLAVE PRODUIT EN ALGERIE

    Directory of Open Access Journals (Sweden)

    R BELOUETTAR

    2002-12-01

    Full Text Available Ce travail présente une étude expérimentale du comportement mécanique du béton cellulaire autoclavé. L’étude est portée essentiellement sur une série d’essais mécaniques en compression quasistatique à différentes vitesses de déformation variables entre 10-4 s-1 et 10 s-1 et à deux états différents (état sec et état saturé d’eau. En général, l’augmentation de la vitesse de déformation donne une augmentation de la contrainte critique du béton cellulaire autoclavé. Le béton cellulaire autoclavé présente une sensibilité à la vitesse de déformation positive. La valeur du module d’élasticité est proche de la valeur standard (1.5 GPa pour un béton cellulaire autoclavé de masse volumique égale à 500-550 kg/m3.

  14. La reconstruction du sourcil par greffon composite du cuir chevelu: une astuce pour faciliter la technique

    Science.gov (United States)

    El Omari, Mounia; El Mazouz, Samir; Gharib, Noureddine; EL Abbassi, Abdallah

    2015-01-01

    Les sourcils jouent un rôle important dans l’équilibre esthétique du visage. Leur reconstruction ou ophriopoïése, après séquelle de brûlure fait partie intégrante du programme de réhabilitation de la face brûlée. Plusieurs techniques ont été décrites. Nous insistons ici sur l'intérêt d'une technique simple, à la portée de tous les chirurgiens, et dont la méthode et les résultats peuvent être améliorés par un dessin bien planifié des zones donneuse et receveuse: la greffe composite prélevée au niveau du cuir chevelu dessinée à l'aide d'un calque du sourcil controlatéral. PMID:26401195

  15. Lignes directrices du CRDI pour la préparation du rapport technique

    International Development Research Centre (IDRC) Digital Library (Canada)

    fdieudonne

    l'accord de subvention et doivent faire partie de tout rapport hébergé dans la ... questions de nature délicate ou confidentielle doivent être traitées par un échange .... les innovations relevant des sciences, de la recherche ou du savoir;.

  16. L'aventure du grand collisionneur LHC du big bang au boson de Higgs

    CERN Document Server

    Denegri, Daniel; Hoecker, Andreas; Roos, Lydia; Rubbia, Carlo

    2014-01-01

    Qu'est-ce que la physique des particules élémentaires, le LHC, et le boson de Higgs ? Ce livre présente de manière simple le monde des quarks, des leptons et de leurs interactions, gouvernées par des symétries fondamentales de la nature, ainsi que le lien entre ce monde de l'infiniment petit et celui de l'infiniment grand. Cette conjonction entre la physique des particules élémentaires et l'évolution de la matière dans les premiers instants de l Univers qui ont suivi le Big-Bang est un des plus beaux acquis de la science de ces cinquante dernières années. Après une description du cadre théorique, le modèle standard, et de son élaboration durant la deuxième moitié du XXe siècle, l'accent est mis sur ses grands succès expérimentaux, mais aussi sur ses faiblesses ou insuffisances telles que nous les percevons aujourd'hui. La passionnante histoire du grand collisionneur de hadrons du CERN, le LHC, le plus grand projet purement scientifique jamais réalisé, est présentée à la fois sous ses...

  17. Une brève histoire du temps du Big Bang aux trous noirs

    CERN Document Server

    Hawking, Stephen

    2017-01-01

    Stephen Hawking est universellement reconnu comme l'un des plus grands cosmologistes de notre époque et l'un des plus brillants physiciens depuis Einstein. Successeur de Newton, il occupe à l'université de Cambridge la chaire de Mathématiques, et s'est rendu célèbre pour ses travaux sur les origines de l'Univers. Une brève histoire du temps est le premier livre qu'il ait décidé d'écrire pour le non-spécialiste. Il y expose, dans un langage simple et accessible, les plus récents développements de l'astrophysique concernant la nature du temps et du monde. Retraçant les grandes théories du cosmos, de Galilée et Newton à Einstein et Poincaré, racontant les ultimes découvertes de l'espace, expliquant la nature des trous noirs, il propose ensuite de relever le plus grand défi de la science moderne : la recherche d'une théorie unitaire combinant et unifiant la relativité générale et la mécanique quantique. On sait que Stephen Hawking lutte depuis plus de trente ans contre une maladie neurolo...

  18. Harmful effects of DU in the offspring of the military personnel employed in DU contaminated regions

    International Nuclear Information System (INIS)

    Atlagic, N.; Lisov, Lj.; Barjaktarovic, V.; Djurovic, B.; Spasic, Jokic V.

    2008-01-01

    Full text: In 1999, during the NATO attacks on Kosovo, from AT-10 aircraft has been shot over 50000 30-mm projectiles which contained approximately 15 tones of DU. Besides DU, projectiles contained products of DU radioactive decay as well as americium, neptunium, plutonium and technetium. Due to DU contamination military personnel employed near hit targets could be contaminated and irradiated. Besides the harmful effects in exposed military personnel, harmful effects were noticed in their offsprings, too. DU can cause genetic and teratogenic harmful effects in the embryos/fetus. It is concentrated in semen of contaminated males and also can contaminate the embryo/fetus through placenta. DU, as a toxic and radioactive element, can cause variety of harmful effects, but the most important are the effects on DNA which are the cause of many diseases. The aim of this paper is to examine is there any change in the incidence in heritable effects, congenital malformations, malignant diseases, endocrine and immune disorders. For that reason we compared the incidence of these diseases in the offspring's of military personnel born from 1995-1999 (1204) with the children born from 2000-2004 (1131) / and 2005-2008. Our results showed higher incidence of congenital malformations and chromosomal abnormalities (12.55 % vs 4.57 %), with highest incidence of foot deformity-52.04 % and hip deformity. These abnormalities were followed with immunological disorders and dysfunction of the urine bladder. Endocrine diseases were increased too(2.16 % :1.63 %). In this period higher incidence of malignant diseases was not noticed, but in the second period (from 5-9 year) after 1999, higher incidence of malignant hematological diseases was noticed, as well as Down Sy. During the conflicts future parents as well as embryo/fetus are exposed to many harmfulness and it is very hard to separate the influence of each. Considering the fact that the effects of DU, could be delayed and synergistic with

  19. Suivi après le traitement du cancer du sein

    Science.gov (United States)

    Sisler, Jeffrey; Chaput, Geneviève; Sussman, Jonathan; Ozokwelu, Emmanuel

    2016-01-01

    Résumé Objectif Offrir aux médecins de famille un résumé des recommandations fondées sur les données probantes pour guider les soins aux survivantes traitées pour le cancer du sein. Qualité des données Une recherche documentaire a été effectuée dans MEDLINE entre 2000 et 2016 à l’aide des mots-clés anglais suivants : breast cancer, survivorship, follow-up care, aftercare, guidelines et survivorship care plans, en se concentrant sur la revue des lignes directrices publiées récemment par les organismes nationaux de cancérologie. Les données étaient de niveaux I à III. Message principal Les soins aux survivantes comportent 4 facettes : surveillance et dépistage, prise en charge des effets à long terme, promotion de la santé et coordination des soins. La surveillance des récidives ne se traduit que par une mammographie annuelle, et le dépistage d’autres cancers doit suivre les lignes directrices basées sur la population. La prise en charge des effets à long terme du cancer et de son traitement aborde des problèmes courants tels la douleur, la fatigue, le lymphœdème, la détresse et les effets indésirables des médicaments, de même que les préoccupations à long terme comme la santé du cœur et des os. La promotion de la santé met en relief les bienfaits de l’activité chez les survivantes du cancer, avec l’accent mis sur l’activité physique. Les soins aux survivantes sont de meilleure qualité lorsque divers services et professionnels de la santé participent aux soins, et le médecin de famille joue un rôle important dans la coordination des soins. Conclusion Les médecins de famille sont de plus en plus souvent les principaux fournisseurs de soins de suivi après le traitement du cancer du sein. Le cancer du sein doit être considéré comme une affection médicale chronique, même chez les femmes en rémission, et les patientes profitent de la même approche que celle utilisée pour les autres affections chroniques en

  20. Le devenir actif du corps affectif

    Directory of Open Access Journals (Sweden)

    Pascal Séverac

    2005-09-01

    Full Text Available Le but de cet article est de saisir ce que signifie, pour le corps, être actif. À partir de la proposition 49 de la partie IV de l’Éthique, on propose de distinguer deux manières d’appréhender le corps – soit comme corps organique, soit comme corps affectif -, et l’on montre que la question éthique du devenir actif s’adresse à la dimension affective du corps. Il faut penser le devenir actif du corps affectif comme augmentation de son aptitude non seulement à affecter, mais aussi à être affecté. En effet, être affecté pour le corps n’est pas identique à pâtir : au contraire, plus est grande l’ouverture sensible d’un corps aux autres corps, plus est grande son activité éthique.The aim of this paper is to understand how the body can be active. With the proposition 49 of the fourth part of Ethics, two ways of conceiving of the body are distinguished : like an organic body or like an affective body. The ethics question of becoming active is about the affective body. This becoming active must be understood as increasing of the ability to affect, as well as to be affected. To be affected is different from to be passive. On the contrary, the more the body is able to be affected, the more he becomes active.

  1. vARIATIONS MENSUELLES DURANT TROIS ANNÉES DU ...

    African Journals Online (AJOL)

    , Université .... ont reçu une alimentation à base de pâturage de. Panicum maximum avec ... Variations mensuelles durant trois années du nombre de spermatozoïdes par éjaculat et des paramètres de spermocytogramme du sperme de bélier ...

  2. Les physiciens du CERN se font batisseurs de cavernes

    CERN Multimedia

    Augereau, J F

    2002-01-01

    Pour percer les secrets bien gardes de la nature, en particulier les origines de la masse, les chercheurs vont installer dans une de ces grottes un enorme detecteur de particules. Atlas, c'est son nom, sera place sur le trace du plus grand accelerateur du monde pour recueillir des indices (1 page).

  3. pluviosite en region soudano-sahelienne au nord du cameroun

    African Journals Online (AJOL)

    AISA

    Dans le but de montrer qu'en zone soudano-sahélienne du Nord du ... principaux facteurs responsables de la variation des rendements en culture pluviale, une étude basée sur ... Mots clés : Risque climatique, pluviométrie, variation, rendement agricole, Nord Cameroun. ... d'analyse plus global et fonctionnel, à savoir,.

  4. Petites entreprises en Afrique: Clés du Changement

    International Development Research Centre (IDRC) Digital Library (Canada)

    Petites et moyennes entreprises — Politique gouvernementale — Afrique — ...... d'adhérer aux stratégies et aux politiques visant à assurer le développement ...... Qui plus est, les banques ont du mal à recruter du personnel de direction et de ...

  5. Connaissances, attitudes, pratiques et appréciations du personnel ...

    African Journals Online (AJOL)

    Connaissances, attitudes, pratiques et appréciations du personnel médical du CHU-Tokoin sur le rôle de la pharmacie hospitalière dans sa mission d'appui au fonctionnement des unités de soins et de diagnostic.

  6. Appel à propositions pour le concours de 2018 du Programme ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    23 nov. 2017 ... Zipline uses drone technology to save lives. Sarah Farhat / Banque mondiale. Le CRDI, l'Israel Science Foundation, la Fondation Azrieli et les Instituts de recherche en santé du Canada annoncent l'appel de propositions pour la quatrième ronde du Programme conjoint canado-israélien de recherche en ...

  7. Renforcement de la lutte antitabac en Afrique du Sud | IDRC ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    affichage de mises en garde sur les produits du tabac (l'équipe doit encore proposer des messages, les soumettre à un groupe test et les évaluer) et de délimiter des zones sans fumée pour les spectateurs de la Coupe du monde de football de 2010.

  8. Fondements du projet urbain ; enjeux et processus

    OpenAIRE

    Tabouret , René

    1989-01-01

    Ce rapport retrace l’émergence et la formalisation progressive du concept de projet urbain dans le cadre de l’Ecole d’Architecture de Strasbourg sur une décennie (1978-1988), à l’épreuve de projets contrastés (villes de Mulhouse, St Denis, Strasbourg) et de la participation au Seminario Internazionale de Arquitectura Contemporanea (sessions de Barcelone, Naples et Belfort). La projet urbain y est identifié comme ‘intervention dans le processus complexe de (trans)formation de la ville’ ; ceci ...

  9. EPIDEMIOLOGIE DE LA PANACHURE JAUNE DU RIZ ...

    African Journals Online (AJOL)

    AISA

    Dans le but de connaître la situation épidémiologique de la panachure jaune du riz en côte d'Ivoire, une enquête phytosanitaire a été effectuée au cours des campagnes agricoles en 2004 et 2005. Elle a porté sur. 128 rizières irriguées et pluviales de 28 localités représentatives dans la moitié sud de la Côte d'Ivoire. Sur.

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

    Science.gov (United States)

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

    2015-01-01

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

  11. Festival du rire de Genève

    CERN Document Server

    Staff Association

    2015-01-01

    Connaissez-vous le Festival du rire de Genève ? La deuxième édition aura lieu du 25 au 28 mars 2015 au Casino-Théâtre à Carouge. Côté programmation, Marc Donnet-Monay ouvre les festivités avant trois autres soirées de folie et d’humour que nous vous laissons le soin de découvrir dans le programme : http://www.rire-geneve.ch/#programme. Réduction de 30% sur l’achat de places pour les membres du personnel du CERN. Pour cela, il suffit de se rendre sur la billetterie en ligne de notre site : www.rire-geneve.ch et d’utiliser le code promotionnel. Contacter le secrétariat de l’Association du personnel (Staff.Association@cern.ch) pour connaitre ce code promotionnel.

  12. La longue marche du mouvement sportif camerounais : l'émergence du Comité Olympique Camerounais (1946–1964

    Directory of Open Access Journals (Sweden)

    Charitas Pascal

    2016-01-01

    Dans ces conditions et selon le statut particulier de ce territoire du « pré-carré » africain de la France, il s'agit de comprendre les étapes de l'institutionnalisation du sport camerounais au sein des atermoiements de la colonisation française puis les processus à l'œuvre dans l'émergence puis la création du Comité Olympique Camerounais (COC, symbole de l'émancipation du sport camerounais et marqueur de son intégration sur la scène sportive internationale, plus particulièrement olympique. Autrement dit, de 1946 et la mise sous tutelle par l'ONU du Cameroun français pour sa partie orientale à 1964 et la première participation du CNO du Cameroun aux Jeux olympiques de Tokyo, l'objectif est de saisir ici le passage d'un sport colonial à un sport postcolonial mettant en exergue le rôle de l'influence française et le rôle des cadres camerounais du secteur sportif.

  13. Performances comparées du HDL-cholestérol et du ratio cholestérol ...

    African Journals Online (AJOL)

    Pour le dépistage du SMet, l'AUC du CT/HDL-C est de 0,69 (IC 95% 0,61-0,77) chez les ... high blood pressure (BP), high fasting glucose, low HDL-C and high triglycerides. Areas under the "Receiver operator characteristic" curves (AUC)

  14. "Cet obscur objet du Désir"

    Directory of Open Access Journals (Sweden)

    Reto Melchior

    1996-09-01

    Full Text Available Luis Bunuel’s last film is based on Pierre Louÿs’ La Femme et le Pantin. This now forgotten bestseller, published in 1898, is drawn from Goya s painting El Pelele, in which four women are playing with a male puppet. In Pierre Louÿs’ novel this scene is inverted so that one woman with two faces plays with four men. In Cet Obscur Objet du Désir this “femme fatale” is interpreted by two actresses. The concentric structure of the film puts focus on a scene of being excluded from knowing. The technique of continually interrupting the flash-back sequences frustrates the audience because of its exclusion from the “real” course of events and gives rise to doubts whether the male protagonist tells the truth about his love-affair or whether he satisfies the curiosity of the audience by telling them Pierre Louÿs’ novel as his own story. This ambiguous art of narration mirrors Bunuel’s claim that the main topic of Cet Obscur Objet du Désir is frustration.

  15. La dimension publicitaire du storytelling politique

    Directory of Open Access Journals (Sweden)

    Andreea Monica State

    2016-11-01

    Full Text Available Le thème général de cet article fait référence à la dimension publicitaire de la narration politique. J'ai choisi ce sujet parce que les histoires font partie de la vie humaine depuis longtemps, utilisées pour transmettre la tradition et enseigner des modèles de comportement social. Récemment, des histoires ont été utilisées de plus en plus souvent à des fins diverses telles que la publicité, la gestion ou la politique. Cet article vise à réaliser une recherche qualitative qui combine l'analyse du contenu et l'analyse du discours. En dehors de la base théorique qui vise à clarifier les concepts de base de la recherche, j’étudie la narration politique utilisée par l'ancien Président Traian Basescu et l'ancien Premier Ministre Victor Ponta dans les biographies en ligne, puis une analyse de leurs discours lors de la Fête Nationale de la Roumanie et l'Union des Principautés Roumaines.

  16. Irradiations effects on the structure of boro-silicated glasses: long term behaviour of nuclear waste glassy matrices; Effets d'irradiations sur la structure de verres borosilicates - comportement a long terme des matrices vitreuses de stockage des dechets nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Bonfils, J. de

    2007-09-15

    This work deals with the long term behaviour of R7T7-type nuclear waste glasses and more particularly of non-active boro-silicated glasses made up of 3 or 5 oxides. Radioactivity of active glasses is simulated by multi energies ions implantations which reproduce the same defects. The damages due to the alpha particles are simulated by helium ions implantations and those corresponding to the recoil nucleus are obtained with gold ions ones. Minor actinides, stemming from the used fuel, is simulated by trivalent rare-earths (Eu{sup 3+} and Nd{sup 3+}). In a first part, we have shown by macroscopic experiments (Vickers hardness - swelling) and optical spectroscopies (Raman - ATR-IR) that the structure of the glassy matrices is modified under implantations until a dose of 2,3.10{sup 13} at.cm{sup -2}, which corresponds to a R7T7 storage time estimated at 300 years. Beyond this dose, no additional modifications have been observed. The second part concerns the local environment of the rare-earth ions in glasses. Two different environments were found and identified as follows: one is a silicate rich one and the other is attributed to a borate rich one. (author)

  17. Fixation of Radioactive Waste in Glass. Part II. The Experimental Evaluation of Phosphate and Borosilicate Glasses; Fixation des Dechets Radioactifs dans le Verre, Deuxieme Partie: Evaluation Experimentale des Verres au Phosphate et au Borosilicate; 0424 0418 041a 0421 0410 0426 0418 042f 0420 0410 0414 0418 041e 0410 041a 0422 0418 0412 041d 042b 0425 041e 0422 0425 041e 0414 041e 0412 0412 0421 0422 0415 041a 041b 0415 . 0427 0410 0421 0422 042c Ii. 042d 041a 0421 041f 0415 0420 0418 041c 0415 041d 0422 0410 041b 042c 041d 0410 042f 041e 0426 0415 041d 041a 0410 041a 0410 0427 0415 0421 0422 0412 0424 041e 0421 0424 0410 0422 041d 042b 0425 0418 0411 041e 0420 041e 0421 0418 041b 0418 041a 0410 0422 041d 042b 0425 0421 0422 0415 041a 041e 041b ; Fijacion de Desechos Radiactivos en Vidrio, Parte II: Evaluacion Experimental de los Vidrios al Fosfato y al Borosilicato

    Energy Technology Data Exchange (ETDEWEB)

    Elliot, M. N.; Grover, J. R.; Hardwick, W. H. [Atomic Energy Research Establishment, Harwell (United Kingdom)

    1963-02-15

    A glass suitable for long-term storage of fission-product wastes must be chosen firstly with regard to the method of storage, and secondly with regard to reliability of manufacture in a highly radioactive plant. The factors that are relevant to storage include leach resistance, thermal and radiation stability and die percentage of waste that can be incorporated, while the physical and chemical nature of glass-forming additives together with the melting point and viscosity of the glass relate to the manufacturing process. The relative importance of these factors is discussed. Experimental studies of the borosilicate glasses that have been chosen for pilot-plant work are described, including the effect of radiation doses of up to 10{sup 12}rad on their physical and chemical properties. Glasses of other kinds have also been examined and their potential value as storage media is compared with the borosilicate glasses. (author) [French] Un verre convenant au.stockage de longue duree des dechets de produits de fission doitetre choisi: premierement, en fonction de la methode de stockage et deuxiemement, eu egard a la securite des operations de traitement dans une usine de haute activite. En ce qui concerne le stockage, les facteurs importants sont la resistance a la corrosion, la stabilite thermique, la stabilite vis a-vis des rayonnements et le pourcentage de dechets pouvant etre incorpores. Au point de vue de la securite des manutentions, il faut tenir compte de la nature physique et chimique des elements intervenant dans la composition du verre, du point de fusion et de la viscosite du verre. Les auteurs examinent l'importance relative de ces facteurs. Ils decrivent les etudes experimentales faites sur les verres au borosilicate choisis pour l'usine pilote, de meme que l'influence des rayonnements sur leurs proprietes chimiques et physiques pour des doses allant jusqu'a 10{sup 12} rad. Ils ont etudie d'autres especes de verre et examine la possibilite de les employer

  18. Géochimie organique du bassin de Paris Organic Geochemistry of the Paris Basin

    Directory of Open Access Journals (Sweden)

    Espitalie J.

    2006-11-01

    Full Text Available On présente ici les principaux résultats de l'étude géochimique réalisée, dans le bassin de Paris, à partir des déblais et des carottes provenant de 100 sondages pétroliers ou miniers, et des huiles prélevées dans les réservoirs du Mésozoïque (Trias, Bathonien supérieur, Néocomien. Les différentes méthodes géochimiques utilisées sont la pyrolyse, particulièrement bien adaptée à l'étude des nombreux échantillons de déblais recueillis, la chromatographie en phase gazeuse pour l'analyse détaillée des huiles et des extraits de roche, la spectrométrie de masse pour l'étude des biomarqueurs. Les époques principales de formation de l'huile et du gaz ont été déterminées par simulation sur ordinateur d'un modèle mathématique de genèse des hydrocarbures. Les méthodes de pyrolyse ont permis de dresser des logs géochimiques des forages étudiés et de déterminer, par le calcul, les paramètres de pyrolyse initiaux des roches-mères, avant leur enfouissement. On a pu ainsi établir, dans le périmètre étudié, des cartes de carbone organique initial, de potentiels pétroliers totaux et de quantités d'HC migrés. L'ensemble de ces résultats montre que les roches-mères de la grande majorité des huiles du Mésozoïque sont situées dans le Lias, s'échelonnant depuis le Toarcien jusqu'à l'Hettangien et que les meilleures zones de potentiel pétrolier du Bassin sont localisées à l'emplacement des régions de forte subsidence à l'époque du Lias. L'étude détaillée des hydrocarbures et celle des biomarqueurs ne permettent pas de distinguer les différentes huiles entre elles, quelle que soit leur profondeur, ni de leur attribuer une origine précise à partir des différents niveaux du Lias. Les cartes de migration mettent en évidence des déplacements latéraux des hydrocarbures dans certaines roches-mères (cas du Toarcien inférieur. Elles montrent aussi un déficit important en hydrocarbures à la base du

  19. Generation of Anomalous Internal Pressures in Source Rocks and Its Role in Driving Petroleum Migration La genèse de pressions internes anormales dans les roches mères et son rôle de poussée dans la migration du pétrole

    Directory of Open Access Journals (Sweden)

    Barker C.

    2006-11-01

    Full Text Available High pressures generated within shales probably have an important role in driving the expulsion of oil and gas. The rising temperature that accompanies increasing depth of burial and drives the generation process causes thermal expansion of the water and in an isolated pore aquathermal pressuringcan lead to high overpressures. In addition, the generation process itself seems to proceed with a volume increase that can cause very high overpressures. These mechanisms have been discussed previously only for liquid-filled systems. The presence of gas leads to very different behaviour and pores in source rocks become subnormally pressured on burial unless there is sufficient generation from the organic matter to offset this. In the absence of continuing generation (e. g. for biogenic methane gas steadily dissolves and pressures fall considerably below hydrostatic. Conversely, on uplift gas-bearing systems tend to overpressure and the pressure can rise to the rock load for the depth when fracturing must occur. Thermal cracking of the bitumens that remain in a source rock as it is buried goes with a volume increase, and in an isolated pore system pressures rise to high values. Only about one percent of oil-like butimen needs to be cracked to gas for the pressure to reach the rock load with fracturing as an inevitable consequence. Les pressions élevées générées dans les argiles jouent probablement un rôle important dans l'expulsion de l'huile et du gaz. L'augmentation de température, qui accompagne l'enfouissement et contrôle les processus de genèse, est la cause d'une dilatation thermique de l'eau et, dans un pore isolé, l'aquathermal pressuring peut amener des surpressions élevées. De plus, le processus de genèse lui-même semble être accompagné d'une augmentation de volume pouvant être également la cause de surpressions élevées. Ces mécanismes ont déjà fait l'objet d'études, mais seulement pour des systèmes imbibés de liquides

  20. β-Irradiation Effects on the Formation and Stability of CaMoO4 in a Soda Lime Borosilicate Glass Ceramic for Nuclear Waste Storage.

    Science.gov (United States)

    Patel, Karishma B; Boizot, Bruno; Facq, Sébastien P; Lampronti, Giulio I; Peuget, Sylvain; Schuller, Sophie; Farnan, Ian

    2017-02-06

    Molybdenum solubility is a limiting factor to actinide loading in nuclear waste glasses, as it initiates the formation of water-soluble crystalline phases such as alkali molybdates. To increase waste loading efficiency, alternative glass ceramic structures are sought that prove resistant to internal radiation resulting from radioisotope decay. In this study, selective formation of water-durable CaMoO 4 in a soda lime borosilicate is achieved by introducing up to 10 mol % MoO 3 in a 1:1 ratio to CaO using a sintering process. The resulting homogeneously dispersed spherical CaMoO 4 nanocrystallites were analyzed using electron microscopy, X-ray diffraction (XRD), Raman and electron paramagnetic resonance (EPR) spectroscopies prior to and post irradiation, which replicated internal β-irradiation damage on an accelerated scale. Following 0.77 to 1.34 GGy of 2.5 MeV electron radiation CaMoO 4 does not exhibit amorphization or significant transformation. Nor does irradiation induce glass-in-glass phase separation in the surrounding amorphous matrix, or the precipitation of other molybdates, thus proving that excess molybdenum can be successfully incorporated into a structure that it is resistant to β-irradiation proportional to 1000 years of storage without water-soluble byproducts. The CaMoO 4 crystallites do however exhibit a nonlinear Scherrer crystallite size pattern with dose, as determined by a Rietveld refinement of XRD patterns and an alteration in crystal quality as deduced by anisotropic peak changes in both XRD and Raman spectroscopy. Radiation-induced modifications in the CaMoO 4 tetragonal unit cell occurred primarily along the c-axis indicating relaxation of stacked calcium polyhedra. Concurrently, a strong reduction of Mo 6+ to Mo 5+ during irradiation is observed by EPR, which is believed to enhance Ca mobility. These combined results are used to hypothesize a crystallite size alteration model based on a combination of relaxation and diffusion

  1. 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

  2. DU weaponry: a view on facts and deceptions

    International Nuclear Information System (INIS)

    Joksimovich, V.

    2002-01-01

    The paper summarizes the results of literature research conducted by the author on the use of depleted uranium (DU) weaponry. The research was initiated during the NATO bombing of Yugoslavia in 1999 with an objective of searching for facts in the presence of massive deceptions staged by the huge propaganda machinery of DU weaponry use proponents. The U.S. made use of DU penetrators in the Persian Gulf war as well as in the Balkan wars both in Bosnia and Kosovo. Brief science and history backgrounds are provided including overviews of DU uses and abuses in these three wars. The U.S./NATO public pronouncements have been centered around the theme that there has been no proven link between DU and cancers. In the author's view, these types of carefully word engineered statements are motivated by possible compensation and cleanup claims rather than supported by hard data and sound science. Since underlying causes of so called Gulf and Balkan syndromes have not been found despite a decade elapsed since conclusion of the Persian Gulf War, the DU must continue to be a front-line suspect. From the standpoint of public health and safety, it is prudent and responsible to call for a moratorium. DU use in the Kosovo war, which was not sanctioned by the UN Security Council, was reckless in the extreme. (author)

  3. Depleted uranium (DU) mobility in the natural environment

    International Nuclear Information System (INIS)

    Ragnarsdottir, K.V.

    2002-01-01

    In 1999 the Balkan's conflict lead NATO war planes to leave 10x10 3 kg of depleted uranium (DU) in the environment of Kosovo and neighbouring states (UNEP, 2001). DU behaves in the same manner in the environment as natural uranium and it can be traced with isotopic analysis due to the fact that DU has the isotopic composition of 0.2% 235 U and 99.8% 2 38 U as opposed to natural uranium which has 0.7% 2 35 U and 99.3% 2 38 U. DU is a waste product of the nuclear industry which enrich nuclear fuel by 2 35 U. Large stock piles of DU therefore exist in countries that produce nuclear energy and/or nuclear weapons. The DU is given to the weapons industry for free (or cheap) and has been a popular choice for armour penetrating arsenal due to the high density of uranium (19 g cm -3 ) and therefore its high penetrating power. Indeed the arsenal used in Kosovo consisted of DU penetrators that were shot from A-10 aeroplanes. They weigh roughly 300 g and have the shape of a fat 9 cm long pencil. (author)

  4. Roman contre roman dans l’organisation du manuscrit du Vatican, Regina Latina 1725

    Directory of Open Access Journals (Sweden)

    Francis Gingras

    2012-08-01

    Full Text Available Alors que les développements structuralistes et post-structuralistes ont favorisé la “textualisation” de la littérature médiévale, l’auteur suggère que la recontextualisation de la réception du roman médiéval passe par un retour aux manuscrits. Appliquée au manuscrit du Vatican, Regina Latina 1725, cette hypothèse de recherche révèle une technique de contrepoint que permet la juxtaposition de différents romans et dont, en dernier recours, le lecteur est toujours un peu juge.

  5. Strategie de repeuplement du mollusque gasteropode Concholepas concholepas (B) au sud du Chili

    OpenAIRE

    Varelasantibanez, C

    1992-01-01

    Une stratégie de repeuplement du "loco" Concholepas concholepas (B) est développée dans le sud du Chili à partir de résultats obtenus au laboratoire sur la reproduction et la croissance de ce mollusque. Les reproducteurs sont conservés au laboratoire pendant toute l'année et l'émission de capsules ovigères peut être provoquée au cours de toute cette période. Les capsules sont ensuite transférées dans le milieu naturel où a lieu l'éclosion. Par ailleurs, des juvéniles recrutés dans le milie...

  6. effet du potassium et du deficit hydrique modere sur la transpiration ...

    African Journals Online (AJOL)

    AISA

    2Université de Cocody-Abidjan, Laboratoire de Physiologie et Pathologie Végétales, UFR Biosciences, 22 B.P. 582. Abidjan 22, Côte d'Ivoire. 3CIRAD-CP, TA 80/01, 34398 Montpellier cedex 5. RESUME. L'importance relative des ions K+ et Cl- dans la tolérance du palmier à la sécheresse n'est pas complètement.

  7. TABLE DES MATIÈRES 1.À propos du CRDI et du domaine de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Marie-Isabelle Beyer

    15 déc. 2014 ... Modalités de l'accord de subvention type du CRDI. 11 ... En partenariat avec le Department for International Development .... Les effets que la structure de la croissance a sur l'autonomisation économique des ..... Le CRDI a conclu un accord général de coopération scientifique et technique avec certains.

  8. l'algerie, du transfert de technologie a l'economie du savoir

    African Journals Online (AJOL)

    Abdelkader DJEFLAT

    sphère académique et l'entreprise, ni négocié correctement par la sphère de la ... La stratégie d'import-substitution poursuivie et les politiques mises en ...... formation adéquate a été à l'origine du bas niveau de recrutement des diplômés et de ...

  9. Accroissement de la compétitivité du Kenya dans l'économie du ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Pour répondre à la demande d'une participation plus active au développement, les universités doivent entretenir des relations plus étroites avec l'industrie et un vaste éventail d'acteurs sociaux. Vision 2030, le plan directeur du Kenya en matière de développement, fait des universités des acteurs de premier plan dans le ...

  10. CALCUL DU SPECTRE DE REFLEXION DU MULTICOUCHE Ni/C DANS LE DOMAINE DES RAYONS X

    Directory of Open Access Journals (Sweden)

    A MEDDOUR

    2000-12-01

    Full Text Available Le pouvoir réflecteur d’un dioptre quelconque dans le domaine des rayons X est trop faible, mais il est toujours possible de choisir des systèmes pouvant présenter un pic de réflexion d’intensité importante autour d’une incidence caractéristique du matériau. Ce dernier est un multicouche, composé de deux couches déposées en sandwich.                 Nous avons élaboré un programme qui permet de calculer la réflexion d’un tel matériau en suivant la méthode d’Abelès dans laquelle une couche mince est représentée par une matrice carrée contenant toutes les informations nécessaires pour le calcul de la réflexion. Ce programme tient compte aussi des rugosités aux interfaces du multicouche, vue leur importante influence sur l’intensité du pic apparaissant sur le spectre de réflexion.                 L’application du programme au multicouche Ni/C a montré  l’existence d’un pic centré autour de 31.32°. Son intensité est sensible au nombre de périodes dans le multicouche, aux épaisseurs des couches minces de Ni et de C et à la taille des rugosités des interfaces Ni/C et C/Ni.

  11. Lettre ouverte au Président du Conseil du CERN

    CERN Document Server

    Association du personnel

    2010-01-01

    Genève, le 1er février 2010 Monsieur le Président, Les membres de la Caisse de pensions, actifs et pensionnés, sont à la fois très inquiets et indignés par la manière avec laquelle le Conseil traite la question, devenue alarmante, de l’équilibre de la Caisse. Dès 2004 en effet, l’étude actuarielle avait alerté le Conseil au sujet du déficit technique du régime et de l’insuffisance du financement de son plan de prestations. Le Conseil s’est alors contenté de mettre en place un mécanisme de sous indexation des pensions – arbitraire et discriminatoire dans la mesure où il ne fait appel qu’à la solidarité des pensionnés – et de décider une augmentation minime des contributions à la Caisse, une mesurette ...

  12. Proudhon, science ou métaphysique du travail

    OpenAIRE

    Lecerf , Eric

    2008-01-01

    La philosophie de Proudhon, même si elle trouve son concept essentiel dans la justice, est intégralement une philosophie du travail, non pas que le travail en constitue l'objet unique, mais car c'est en lui que les tensions du réel sont concrètement identifiables. C'est dans sa critique que l'agir humain se donne comme émancipation et/ou aliénation, autrement dit que la dialectique acquiert toute sa justification. La philosophie du travail de Proudhon donnera lieu à deux lectures opposées : c...

  13. Brain stem hypoplasia associated with Cri-du-Chat syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Jin Ho; Lee, Ha Young; Lim, Myung Kwan; Kim, Mi Young; Kang, Young Hye; Lee, Kyung Hee; Cho, Soon Gu [Dept. of Radiology, Inha University Hospital, Inha University School of Medicine, Incheon (Korea, Republic of)

    2013-12-15

    Cri-du-Chat syndrome, also called the 5p-syndrome, is a rare genetic abnormality, and only few cases have been reported on its brain MRI findings. We describe the magnetic resonance imaging findings of a 1-year-old girl with Cri-du-Chat syndrome who showed brain stem hypoplasia, particularly in the pons, with normal cerebellum and diffuse hypoplasia of the cerebral hemispheres. We suggest that Cri-du-Chat syndrome chould be suspected in children with brain stem hypoplasia, particularly for those with high-pitched cries.

  14. Business plan pour une application Smartphone : du concept au lancement

    OpenAIRE

    Vriamont, Gilles

    2015-01-01

    Création d'une application mobile pour Smartphone. Description théorique concernant la rédaction d'un business plan dans une première partie suivi d'une description théorique des caractéristiques des applications mobiles. Dans une seconde partie, analyse de l'industrie des Smartphones et des applications mobiles suivi de la partie pratique et du développement du produit, partant de la description du produit jusqu'à l'analyse des coûts. Master [120] en Ingénieur de gestion, Université catho...

  15. Activity report 2015 Commission Perspectives du Reseau

    International Nuclear Information System (INIS)

    Ricour, Olivia

    2016-01-01

    This document contains the activity report for 2015 of the Commission Perspectives du Reseau which has been set up by RTE to be the main body for organising a dialogue with all the actors of the energy sector and civil society about challenges and stakes of the electric power system on the medium and on the long term. It describes how this body aims at sharing knowledge and expertise of all stakeholders (publications, European platform for data transparency), at being a place for debating and enriching the understanding of tomorrow's important stakes for the power system (discussion of the issue of greenhouse gas emissions with an analysis of the impact of the CO 2 price signal on emissions by the European electricity system and results of the e-Highway 2050 European project). The road-map of the Commission works for 2016 is provided, as well as a list of members

  16. Chronologie politique du Yémen. 2002

    Directory of Open Access Journals (Sweden)

    Stéphane Levaux

    2002-04-01

    Full Text Available photo © François Burgat Politique Intérieure Janvier-février 06 janvier : Dix chefs tribaux des provinces de Ma'rib, de Shabwa et du Jawf, provinces dont l'importance politique va croissant en raison des tensions sécuritaires, affirment leur soutien au Président `Alî `Abd Allâh /Sâli/h dans sa campagne antiterroriste. 14 janvier : L'ambassade américaine reçoit des menaces et ferme son service consulaire. 15 janvier : Amnistie et retour d'exil de Sâlim /Sâli/h Mu/hammad, ancien dirig...

  17. La crise du vivre-ensemble

    DEFF Research Database (Denmark)

    Schultz, Nils Voisin

    2014-01-01

    Cet article examine les caractères idéologique et affectif de deux essais écrits respectivement par Alain Finkielkraut et Richard Millet sur la crise actuelle du vivre-ensemble en France. Les deux penseurs critiquent la société multiculturelle, mais alors que pour Finkielkraut cette société est une...... chance pour la France à condition que le dialogue interculturel soit renforcé et que l’idée d’une culture française y garde sa place, elle reste pour Millet une impossibilité. L’enjeu de l’analyse est de dévoiler la capacité des discours à générer par l’affectivité une peur capable d’intensifier l’argumentation...

  18. Elevage intensif du loup Dicentrarchus labrax

    OpenAIRE

    Coves, Denis; Gasset, Eric

    1993-01-01

    Cet article fait le point sue les coûts de production directs relatifs à différentes méthodes d'élevage intensif du loup (Dicentrarchus labrax). Il s'appuie sur des résultats zootechniques obtenus dans l'unité de démonstration à grande échelle de notre laboratoire. Par rapport à un système de production en circuit ouvert, le recyclage de l'eau permet de diviser par 2.2 les charges directes de production. Si les proies vivantes sont précédemment remplacées par une microparticule efficace, ces ...

  19. evaluation du nouveau ne par cesarienne

    OpenAIRE

    MERAD, Atif Djelloul; BOUARFA, Wahiba

    2014-01-01

    L’étude rétrospective des dossiers montre un recueil des données anamnestiques peu satisfaisant. L’anamnèse reste l’élément essentiel qui permet de faire le point sur l’enfant nouveau-né adressé pour soins appropriés, elle doit retracer l’histoire de la grossesse jusqu’à l’accouchement. L’étude du profil de nos patientes montre que La césarienne concerne particulièrement les primipares qui représentent plus de la moitié de nos femmes. Le risque de césarienne augmente statistiquement lorsqu...

  20. Entretiens sur la multitude du monde

    CERN Document Server

    Damour, Thibault

    2014-01-01

    L'un est un écrivain et un scénariste célèbre. L'autre est un physicien et un chercheur mondialement connu. Une même interrogation les porte. Comment penser le monde après un siècle de bouleversements scientifiques ? Jean- Claude Carrière et Thibault Damour nous entraînent ici dans un dialogue lumineux, qui met l'esprit au défi de lui- même et où la clarté rivalise avec le gai savoir. La matière éternelle, l'espace et le temps absolus, l 'unique réalité : en ce début de troisième millénaire, toutes ces grandes notions du passé n'ont plus qu'une valeur d'illu- sions. Il n'y a plus d'histoire prédéterminée, inexorable, li- vrée à des forces mécaniques. L'univers se révèle léger, instable, multiple dans la superposition d'une infinité d'his- toires possibles dont nous ne percevons qu'un mince fais- ceau. C'est à la découverte de cette multitude du monde, laissant loin derrière les récits de science-fiction, que nous invitent Jean-Claude Carrière et Thibault Damour. Un voyage p...

  1. Recent and future developments at the Regie du gaz naturel

    International Nuclear Information System (INIS)

    Giroux, J.

    1995-01-01

    The history of the Quebec Regie du gaz naturel, dating back to 1932, and its role in distributing natural gas in Quebec was described. Among more recent developments construction of a natural gas distribution system on the south shore of Quebec City was discussed. Unlinked mini-systems were built in St-Romuald and Levis. Gas was delivered by truck until an underwater crossing was completed. The federal-provincial infrastructures program was also summarized. The most important ruling by the Regie was the D-94-19 decision on GMi's supply policy and the concept of u mbrella buy-sell . Although this policy was originally approved by the Regie, after consideration of all factors, it was decided that this system was not in line with the deregulation trend and that buyers and sellers could do without GMi's intrusion in their contractual agreements. Issues to be addressed by the Regie in the coming months included transportation service, unbundling, cost allocation and rate of return adjustments mechanism in regards to the recent National Energy Board (NEB) decision on the subject, and separation of (LDC) distribution activities from LDC sales

  2. Impact socio professionnel de la libération chirurgicale du syndrome du canal carpien

    Science.gov (United States)

    Kraiem, Aouatef Mahfoudh; Hnia, Hajer; Bouzgarrou, Lamia; Henchi, Mohamed Adnène; Khalfallah, Taoufik

    2016-01-01

    L’objectif de notre travail était d’étudier les conséquences socioprofessionnelles d’une libération chirurgicale du SCC. Il s’agit d’une étude transversale portant sur les sujets opérés pour un SCC d’origine professionnelle ; recensés dans le Service de Médecine de Travail et de Pathologies Professionnelles au CHU Tahar Sfar de Mahdia en Tunisie sur une période de 8 ans allant du 1 Janvier 2006 au mois Décembre 2013. Le recueil des données s’est basé sur une fiche d’enquête, portant sur la description des caractéristiques socioprofessionnelles, médicales, et sur le devenir professionnel des participants. Pour étudier les contraintes psychosociales au travail, nous avons adopté le questionnaire de Karasek. La durée d’arrêt de travail après libération chirurgicale du SCC était significativement liée à l’existence d’autres troubles musculo-squelettiques autre que le SCC, la déclaration du SCC en maladie professionnelle et à l’ancienneté professionnelle des salariés. Quant au devenir professionnel des salariés opérés, 50,7% ont gardé le même poste, 15,3% ont bénéficié d’un aménagement de poste et 33,8% ont bénéficié d’un changement de poste dans la même entreprise. Le devenir professionnel de ces salariés était corrélé à leurs qualifications professionnelles et au type de l’atteinte sensitive et/ou motrice du nerf médian à l’EMG. Un certain nombre de facteurs non lésionnels déterminaient la durée de l’arrêt de travail, alors que le devenir professionnel des opérés pour SCC dépendait essentiellement de leurs qualifications professionnelles et des données de l’électromyogramme. Il est certain que des travaux beaucoup plus larges permettraient d’affiner encore ces résultats. PMID:27800089

  3. Politique de gestion de l'habitat du poisson du Ministère des pêches et des océans

    National Research Council Canada - National Science Library

    1986-01-01

    Le present document enonce la politique, les objectifs et les strategies du Ministere des Peches et des Oceans pour la gestion de l'habitat du poisson dont dependent les peches canadiennes en eaux douces et marines...

  4. Archéologie d’un parasite du cheval

    OpenAIRE

    Dufour, Benjamin; Bailly, Matthieu Le

    2017-01-01

    Oxyuris equi, l’oxyure du cheval, est un vers parasite spécifique des équidés régulièrement mis en évidence lors des études paléoparasitologiques. Nous proposons ici une synthèse originale entre les mentions de ce parasite connues dans la bibliographie et les textes anciens, avec des données inédites issues de nos recherches en paléoparasitologie. Cette compilation des données montre que la plus ancienne observation de l’oxyure du cheval date du milieu du Ier millénaire avant notre ère en Asi...

  5. Echographie devant une metrorragie du premier trimestre de ...

    African Journals Online (AJOL)

    Echographie devant une metrorragie du premier trimestre de grossesse sur uterus bicorne a issue favorable. Vaginal bleeding in a pregnant woman with a bicornuate uterus, ultrasound finding and favourable outcome.

  6. Ottawa exprime son soutien lors des projections du documentaire ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    22 mars 2017 ... Les récentes projections à Ottawa du film primé Little Gandhi: The lost truth of the Syrian uprising ont été chaleureusement accueillies tant par les parlementaires que par le public.

  7. Duši alla sauna / Margit Aedla

    Index Scriptorium Estoniae

    Aedla, Margit, 1970-

    2007-01-01

    Duraviti multifunktsionaalne värviline duširuum. Electroluxi Design Lab'07 konkursi finalisti Joao Diego Schimansky Fog Shower (ududuš). Väiksematesse kodudesse sobiv Muoto mobiilne aurusaunatool Muoto-Steam Deluxe

  8. Sibelius: Luonnotar. Chevauchee nocturne et lever du soleil / Pierre Gervasoni

    Index Scriptorium Estoniae

    Gervasoni, Pierre

    1996-01-01

    Uuest heliplaadist "Sibelius: Luonnotar. Chevauchee nocturne et lever du soleil. 4 Legendes. Orchestre Philharmonique Royal de Stockholm, Paavo Järvi. Virgin Classics 545 213-2 (CD:167F). 1996. TT: 1h 13'22"

  9. Stravinsky, Igor: Le Sacre du Printemps / Pierre-E. Barbier

    Index Scriptorium Estoniae

    Barbier, Pierre-E.

    1996-01-01

    Uuest heliplaadist "Stravinsky, Igor: Le Sacre du Printemps. Requiem Canticles. Canticum sacrum. Variations sur un choral de Bach. Orchestre de la Suisse Romande, Neeme Järvi" Chandos CHAN 9 408, distribution Media 7 (SD:160F)

  10. Emilie du Châtelet between Leibniz and Newton

    CERN Document Server

    Hagengruber, Ruth

    2012-01-01

    This book describes Emilie du Chatelet known as "Emilia Newtonmania", and her innovative and outstanding position within the controversy between Newton and Leibniz, one of the fundamental scientific discourses of her time.

  11. Sodium purification in Rapsodie; La purification du sodium a Rapsodie

    Energy Technology Data Exchange (ETDEWEB)

    Giraud, B [Commissariat a l' Energie Atomique, Dir. des Piles Atomiques, Cadarache (France). Centre d' Etudes Nucleaires

    1968-07-01

    This report is one of a series of publications presenting the main results of tests carried out during the start-up of the first french fast neutron reactor: Rapsodie. The article presents the sodium purification techniques used in the reactor cooling circuits both from the constructional point of view and with respect to results obtained during the first years working. (author) [French] Ce rapport fait partie d'une serie de publications presentant l'essentiel des resultats des essais effectues a l'occasion du demarrage du premier reacteur francais a neutrons rapides: RAPSODIE. Cet article expose les techniques de la purification du sodium utilise dans les circuits de refroidissement du reacteur tant au point de vue de leur realisation technologique, que des resultats obtenus pendant la premiere annee de fonctionnement. (auteur)

  12. Magic turtle dans le canton du Jura: concept marketing

    OpenAIRE

    Hauser, Magali; Perruchoud-Massy, Marie-Françoise

    2012-01-01

    Depuis juin 2009, Saint-Ursanne/Clos du Doubs est une région pilote du Projet Enjoy Switzerland/ASM ayant pour but d’intervenir sur le développement et la sensibilisation du tourisme dans la région. En parallèle, la Maison du Tourisme, entreprise proposant principalement des offres touristiques dans la région, a ouvert ses portes l’année dernière. Ces deux entités ont travaillé ensemble afin de développer une nouvelle offre touristique intitulée « Magic turtle ». Le Magic turtle, pensé par de...

  13. La microflore des sols du vignoble de Touraine

    Directory of Open Access Journals (Sweden)

    Claude Cuinier

    1975-12-01

    Full Text Available L'étude microbiologique des sols du vignoble porte sur trois années. Les déterminations quantitatives des bactéries, champignons, actinomycètes et des groupes fonctionnels des cycles de l'azote, du carbone et du soufre sont effectuées au cours de trois périodes du cycle végétatif de la vigne. Des variations saisonnières et annuelles sont observées. La microflore des sols viticoles est comparée à celle d'autres sols. Elle est au moins aussi riche et se distingue par son caractère plus aérobie. De grands écarts dans la composition microbiologique sont apparus entre des sols viticoles différant par leurs caractéristiques physiques et chimiques.

  14. Protéger les collectivités côtières du nord du Maroc | CRDI - Centre ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    3 févr. 2011 ... Élévation du niveau de la mer, ondes de tempête, inondations littorales : les ... Un plan d'action en matière de gestion intégrée du littoral et une nouvelle ... du territoire sans recourir à un guide de la dynamique du milieu côtier. ... local, et encore moins de contrôle sur les terres dont elles sont tributaires.

  15. Communication du Service juridique et du Département HR à l'attention des membres du personnel domiciliés en France

    CERN Multimedia

    HR Department

    2007-01-01

    Déclaration de revenus 2006 Les membres du personnel trouveront ci-après les informations nécessaires sur la manière de remplir la déclaration de revenus 2006, qui doit être retournée au plus tard le 31 mai 2007. Qui doit remplir la déclaration? Comment l'obtenir? Tous les membres du personnel1) domiciliés en France2), qu'ils soient ou non de nationalité française, doivent remplir la déclaration de revenus 2006 sur la base des présentes instructions et la renvoyer signée, au plus tard le 31 mai 2007, au centre des impôts de leur domicile. Les membres du personnel devraient recevoir la déclaration de revenus 2006 fin avril - début mai. Ceux qui ne la recevraient pas directement devront la retirer au centre des impôts, à la trésorerie ou à la mairie de leur domicile ou bien encore la télécharger sur le site internet du Ministère des Finances (www.finances.gouv.fr). Comment remplir la déclaration Les membres du personnel doivent remplir la DECLARATION PAPIER uniquement. Dé...

  16. Histoire tertiaire de l'Arche de Brahmaputra ; son rôle dans la prospection des hydrocarbures du Haut Assam (Inde (résumé Tertiary History of Brahmaputra Arch. Its Role in Hydrocarbon Prospects of Upper Assam, India (Abstract

    Directory of Open Access Journals (Sweden)

    Murty K. N.

    2006-10-01

    Full Text Available On analyse l'histoire tertiaire de la plate-forme du Haut Assam (Inde et on discute les facteurs géologiques responsables du caractère pétrolier de cette importante province ainsi que ses relations avec la ceinture mobile de Naga au Sud-Est et avec l'avant-fosse himalayenne au Nord-Ouest. A cette intention, on a préparé des cartes paléologiques pour différentes formations dans la vallée supérieure de l'Assam, basées sur de nombreux puits et levers géophysiques. A partir de ces cartes, on a construit une série de coupes paléogéologiques pour illustrer l'évolution structurale de la plate-forme du haut Assam. Cette étude montre que la structure régionale de la haute vallée de l'Assam est en subsurface une arche large - l'Arche de Brahrnaputra - parallèle à, et juste au sud de la rivière Brahmaputra, formée par un double basculernent opposé : un ancien talus vers le Sud-Est durant le Paléogène et l'autre tourné vers le Nord-Ouest pendant le Mio-Pliocène. On peut identifier deux phases de migration des hydrocarbures. L'étude permet l'affirmation d'objectifs futurs en Haut Assam. Cette arche a une histoire géologique voisine de celle de l'arche de Bend du centre-nord du Texas et de l'arche de Hunton-Seminole-Ozark en Oklahoma où de riches gisements ont été trouvés dans presque tous les terrains impliqués dans le bombement. The Tertiary history of Upper Assam shelf, India is analysed. The geological factors responsible for making this an important petroleum province and ifs relationship with the Nago mobile belt in the south-east and the Himalayan fore deep in the north-vvest ore discussed. Sub-crop maps of différent geological formations in Upper Assam Valley based on a number of drilled wells and various geophysical surveys ore prepared for this purpose. From these maps, a series of palaeogeological sections are constructed to illustrate the structural evolution of the Upper Assam shelf. The study reveals thot the

  17. Du Mal-être au votre extrême

    OpenAIRE

    Gethin,, Amory; Jenmana,, Thanasak

    2017-01-01

    Note d'analyse de l'Observatoire du Bien-être du CEPREMAP; The rise of populism and the failure of traditional parties during the 2017 French presidential election calls to question the relevance of traditional determinants of voting. Given the difficult economic context associated with François Hollande’s term, to what extent has the increasing pessimism in France contributed towards anti-establishment voting?Available surveys reveal two remarkable phenomena. The extremes, particularly the e...

  18. Le developpement olympique du kayak Africain : Anglophonie vs ...

    African Journals Online (AJOL)

    Si le kayak de slalom s'est développé récemment en Afrique (premier Championnat continental organisé en 2009), il a été médiatisé à la faveur de sa reconnaissance olympique. Mais quels sont les enjeux culturels du développement olympique du kayak en Afrique francophone ? Comment cette activité a-t-elle pu ...

  19. Donner aux travailleurs du sexe les moyens de consigner les ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Dans la plupart des sociétés, le travail du sexe est fortement stigmatisé, et ceux qui le pratiquent sont en butte aux reproches, à la désapprobation et à la discrimination. Par conséquent, la violence faite aux travailleurs du sexe se voit peu, et dans certains contextes, elle est même tolérée. On dispose donc de très peu de ...

  20. Reproduction du programme MamaToto en Tanzanie rurale ((ISMEA)

    International Development Research Centre (IDRC) Digital Library (Canada)

    Le nouvel engagement du gouvernement de la Tanzanie visant à améliorer le bien-être des mères et des enfants a besoin de données probantes appuyant la création de ... L'équipe du projet mobilisera les responsables de district, renforcera les services des établissements et précisera le rôle des travailleurs en santé ...