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Sample records for hollandite verre son68

  1. (Alpha, gamma) irradiation effect on the alteration of high-level radioactive wastes matrices (UO{sub 2}, hollandite, glass SON68); Effet de l'irradiation (alpha, gamma) sur l'alteration des matrices de dechets nucleaires de hautes activites (UO{sub 2}, hollandite, verre SON68)

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, T

    2007-06-15

    The aim of this work is to determine the effect of irradiation on the alteration of high level nuclear waste forms matrices. The matrices investigated are UO{sub 2} to simulate the spent fuel, the hollandite for the specific conditioning of Cs, and the inactive glass SON68 representing the nuclear glass R7T7) The alpha irradiation experiments on UO{sub 2} colloids in aqueous carbonate media have enabled to distinguish between the oxidation of UO{sub 2} matrix as initial and dissolution as subsequent step. The simultaneous presence of carbonate and H{sub 2}O{sub 2} (product resulting from water radiolysis) increased the dissolution rate of UO{sub 2} to its maximum value governed by the oxidation rate. ii) The study of hollandite alteration under gamma irradiation confirmed the good retention capacity for Cs and Ba. Gamma irradiation had brought only a little influence on releasing of Cs and Ba in solution. Electronic irradiation had conducted to the amorphization of the hollandite only for a dose 1000 times higher than the auto-induced dose of Ba over millions of years. iii) The experiences of glass irradiation under alpha beam and of helium implantation in the glass SON68 were analyzed by positon annihilation spectroscopy. No effect has been observed on the solid surface for an irradiation dose equal to 1000 years of storage. (author)

  2. (Alpha, gamma) irradiation effect on the alteration of high-level radioactive wastes matrices (UO2, hollandite, glass SON68)

    International Nuclear Information System (INIS)

    Suzuki, T.

    2007-06-01

    The aim of this work is to determine the effect of irradiation on the alteration of high level nuclear waste forms matrices. The matrices investigated are UO 2 to simulate the spent fuel, the hollandite for the specific conditioning of Cs, and the inactive glass SON68 representing the nuclear glass R7T7) The alpha irradiation experiments on UO 2 colloids in aqueous carbonate media have enabled to distinguish between the oxidation of UO 2 matrix as initial and dissolution as subsequent step. The simultaneous presence of carbonate and H 2 O 2 (product resulting from water radiolysis) increased the dissolution rate of UO 2 to its maximum value governed by the oxidation rate. ii) The study of hollandite alteration under gamma irradiation confirmed the good retention capacity for Cs and Ba. Gamma irradiation had brought only a little influence on releasing of Cs and Ba in solution. Electronic irradiation had conducted to the amorphization of the hollandite only for a dose 1000 times higher than the auto-induced dose of Ba over millions of years. iii) The experiences of glass irradiation under alpha beam and of helium implantation in the glass SON68 were analyzed by positon annihilation spectroscopy. No effect has been observed on the solid surface for an irradiation dose equal to 1000 years of storage. (author)

  3. Compared study of the local structure of alteration products of SON 68 glass and natural gels; Etude comparee de la structure locale des produits d'alteration du verre SON 68 et de gels naturels

    Energy Technology Data Exchange (ETDEWEB)

    Pellegrin, E

    2000-07-01

    This study is a contribution in the understanding of the long time behavior of alteration products of the glass SON 68, used to simulate the nuclear glass R7T7. The local structure around Zirconium and iron has been probed using X-ray absorption spectroscopy in altered surface layer of glass SON 68. Alteration products of this glass have been prepared for short (3 hours to 7 days) and long (17 months) time, using various indexes of saturation for the leaching solution with respect to the Si content of the glass (from 0 to 90 %). The evolution of the local structure around Fe has also been studied in recent and old natural ferric gels. Zr, Fe- L{sub 2,3} XANES and Zr, Fe-K EXAFS spectroscopies have shown that, in the pristine glass, these elements are connected to the polymeric network. Zr is found in an environment close to that of a zircon-silicate containing Na and Ca. Trivalent Fe is a network former. The leached layer of glass SON 68 is constituted of poorly ordered Zr-and Fe-(oxi-hydr)oxides that may have been formed by a mechanism of dissolution/precipitation; a relict phase with the same Zr local structure as that observed in the pristine glass, probably obtained thanks to in-situ solid condensation. The structural characteristics of the leached layer are observed from the first steps of alteration for Zr and Fe. Conversely to Fe, the structural status of Zr depends on the leaching kinetic as well as the contents of Ca and Si in the solid. Fe-K EXAFS results in recent natural ferri-hydrides present a clear structural similarity with that determined in glass SON 68 leached products. The study of old paleosols (between 1,800 and 200,000 years) has demonstrated the long time stability of ferric gels, although an increase of medium range order around Fe is seen. (author)

  4. Isotope tracing ({sup 29}Si and {sup 18}O) of the alteration mechanisms of the French glass 'SON68' used for the storage of nuclear waste; Tracage isotopique ({sup 29}Si and {sup 18}O) des mecanismes de l'alteration du verre de confinement des dechets nucleaires: 'SON68'

    Energy Technology Data Exchange (ETDEWEB)

    Valle, N

    2001-07-01

    This study aims to enhance our understanding of the mechanisms of aqueous corrosion of the glasses used for the storage of nuclear waste. Glass samples 'SON68', doped with a different rare earth element (La, Ce or Nd), were altered simultaneously with water enriched in {sup 29}Si and {sup 18}O, throughout a period of 20 months. The aim of such isotope tracing was (i) to follow the 'real' exchanges between glass and solution and (ii) to understand the reactions involving Si-O bonds in the leached layer during alteration. Leachates were analyzed by ICP-MS and -AES, and elemental and isotopic variations in the altered glass layer were measured by ion-probe, using a depth profiling technique. Elemental analyses enabled the distribution of the elements in the two layers of altered glass (phyllosilicates and gel) to be established, and the results reveal a selective partitioning of elements between the two layers. Isotopic analyses of altered layers and leachates allowed phyllosilicates to be distinguished from gel, and suggest two different mechanisms of formation. Whilst phyllosilicates grow on the surface of the glass by a mechanism of precipitation, gel is formed by a succession of hydrolysis / condensation reactions taking place mainly at the gel / pristine glass interface. This gel is formed by the in situ rearrangement of hydrated species, without reaching equilibrium with the solution. Moreover, an experimental technique has been developed enabling one to trace the transport of silicon from the solution into the altered glasses, under an isotopic gradient. Diffusion profiles, obtained by ion-probe, have been modeled and have allowed the determination of the apparent silicon diffusion coefficient (DSi) in gels. Therefore, our experiments have permitted the quantification of the influence of both the alteration conditions (dynamic or static tests) and the solution composition on the value of DSi. (author)

  5. SON68 glass alteration enhanced by magnetite

    Energy Technology Data Exchange (ETDEWEB)

    Godon, Nicole; Gin, Stephane; Rebiscoul, Diane; Frugier, Pierre [CEA, DEN-Marcoule, F30207, Bagnols-sur-Ceze (France)

    2013-07-01

    This paper reports experimental and modeling results of SON68 glass / magnetite interactions while in contact with synthetic groundwater from a clay environment. It is shown that magnetite enhances glass alteration, first by the sorption of Si released from the glass onto magnetite surfaces, then by a second process that could be the precipitation of an iron silicate mineral or the transformation of magnetite into a more reactive phase like hematite or goethite. This study globally suggests a detrimental effect of magnetite on the long-term durability of nuclear glass in geological disposal conditions. (authors)

  6. Evolution of the uranium local environment during alteration of SON68 glass

    International Nuclear Information System (INIS)

    Jollivet, Patrick; Auwer, Christophe Den; Simoni, Eric

    2002-01-01

    The speciation of uranium in SON68 glass specimens doped with 0.75-3.5 wt% uranium and in the gels formed by alteration of the specimens was investigated by X-ray absorption spectroscopy. In the glasses, uranium is present at oxidation state VI and coordination number 6 with the same average distances than those found in a UO 3 type environment. The U-O distances and uranium coordination numbers are identical throughout the uranium concentration range. During glass alteration the uranium remains at oxidation state VI in the gels, but was found in the uranyl form. An increase in the equatorial distances (from 2.20 and 2.32 A in the glass to respectively 2.22 and 2.39 A in the gel) and coordination numbers (to about 7 and 8, respectively) was observed

  7. Evolution of the local environment of lanthanum during simplified SON68 glass leaching

    International Nuclear Information System (INIS)

    Jollivet, P.; Delaye, J.M.; Den Auwer, C.; Simoni, E.

    2007-01-01

    The evolution of the short- and medium-range local environment of lanthanum was determined by L-III-edge X-ray absorption spectroscopy (XAS) during leaching of simplified SON68-type glasses. In glass without phosphorus, lanthanum is found in a silicate environment, and its first coordination sphere comprises eight oxygen atoms at a mean distance of 2.51 angstrom. When this glass was leached at a high renewal rate, the lanthanum local environment was significantly modified: it was present at hydroxy-carbonate and silicate sites with a mean La-O distance of 2.56 angstrom, and the second neighbors consisted of La atoms instead of Si for the glass. Conversely, in the gel formed at low renewal rates, lanthanum was found in a silicate environment similar to that of the glass. In phosphorus-doped glass, lanthanum is found in a phosphate environment, although the Si/P atomic ratio is 20:1. Lanthanum is surrounded by seven oxygen atoms at a mean distance of 2.37 angstrom. When phosphorus-doped glass is leached, regardless of the leaching solution flow rate, the short- and medium-range lanthanum local environment remains almost constant; the most significant change is a 0.05 angstrom increase in the La-O distance. (authors)

  8. Effect of Callovo-Oxfordian clay rock on the dissolution rate of the SON68 simulated nuclear waste glass

    Energy Technology Data Exchange (ETDEWEB)

    Neeway, James J., E-mail: James.Neeway@pnnl.gov [SUBATECH, Unité Mixte de Recherche 6457, École des Mines de Nantes, CNRS/IN2P3, Université de Nantes, BP 20722, 44307 Nantes cedex 3 (France); Abdelouas, Abdesselam; Ribet, Solange; El Mendili, Yassine [SUBATECH, Unité Mixte de Recherche 6457, École des Mines de Nantes, CNRS/IN2P3, Université de Nantes, BP 20722, 44307 Nantes cedex 3 (France); Schumacher, Stéphan [ANDRA, Parc de la Croix Blanche, 1/7 rue Jean Monnet, 92298 Châtenay-Malabry (France); Grambow, Bernd [SUBATECH, Unité Mixte de Recherche 6457, École des Mines de Nantes, CNRS/IN2P3, Université de Nantes, BP 20722, 44307 Nantes cedex 3 (France)

    2015-04-15

    Long-term storage of high-level nuclear waste glass in France is expected to occur in an engineered barrier system (EBS) located in a subsurface Callovo-Oxfordian (COx) clay rock formation in the Paris Basin in northeastern France. Understanding the behavior of glass dissolution in the complex system is critical to be able to reliably model the performance of the glass in this complex environment. To simulate this multi-barrier repository scenario in the laboratory, several tests have been performed to measure glass dissolution rates of the simulated high-level nuclear waste glass, SON68, in the presence of COx claystone at 90 °C. Experiments utilized a High-Performance Liquid Chromatography (HPLC) pump to pass simulated Bure site COx pore water through a reaction cell containing SON68 placed between two COx claystone cores for durations up to 200 days. Silicon concentrations at the outlet were similar in all experiments, even the blank experiment with only the COx claystone (∼4 mg/L at 25 °C and ∼15 mg/L at 90 °C). The steady-state pH of the effluent, measured at room temperature, was roughly 7.1 for the blank and 7.3–7.6 for the glass-containing experiments demonstrating the pH buffering capacity of the COx claystone. Dissolution rates for SON68 in the presence of the claystone were elevated compared to those obtained from flow-through experiments conducted with SON68 without claystone in silica-saturated solutions at the same temperature and similar pH values. Additionally, through surface examination of the monoliths, the side of the monolith in direct contact with the claystone was seen to have a corrosion thickness 2.5× greater than the side in contact with the bulk glass powder. Results from one experiment containing {sup 32}Si-doped SON68 also suggest that the movement of Si through the claystone is controlled by a chemically coupled transport with a Si retention factor, K{sub d}, of 900 mL/g.

  9. Application of the GRAAL model to leaching experiments with SON68 nuclear glass in initially pure water

    International Nuclear Information System (INIS)

    Frugier, P.; Chave, T.; Gin, S.; Lartigue, J.-E.

    2009-01-01

    Based on a review of the current state of knowledge concerning the aqueous alteration of SON68 nuclear glass we have proposed a mechanistic model, GRAAL (Glass Reactivity with Allowance for the Alteration Layer) [P. Frugier, S. Gin, Y. Minet, T. Chave, B. Bonin, N. Godon, J.E. Lartigue, P. Jollivet, A. Ayral, L. De Windt, G. Santarini, J. Nucl. Mater. 380 (2008) 8]. This article describes how the GRAAL model hypotheses are solved using a calculation code coupling chemistry and transport. The geochemical solution of this model combines three major phenomena: chemical equilibria in solution, water and ion transport by convection or diffusion, and element diffusion through the passivating reactive interphase. The model results are compared with experimental data for SON68 glass leached in initially pure water both in a closed system and in renewed media. The comparison shows the model very satisfactorily accounts for variations in the pH and the element concentrations in solution as a function of time, the glass surface area in contact with solution, and the solution renewal rate. This success is due to the fact that the diffusion of elements through the alteration gel is taken into account in the model. This mechanism cannot be disregarded under most experimental conditions - if only to predict the solution pH - and must therefore be an integral part of the geochemical model.

  10. SON68 nuclear glass dissolution kinetics: Current state of knowledge and basis of the new GRAAL model

    Energy Technology Data Exchange (ETDEWEB)

    Frugier, P. [CEA Marcoule, DTCD/SECM/LCLT, BP 17171, 30207 Bagnols-sur-Ceze cedex (France)], E-mail: pierre.frugier@cea.fr; Gin, S.; Minet, Y.; Chave, T. [CEA Marcoule, DTCD/SECM/LCLT, BP 17171, 30207 Bagnols-sur-Ceze cedex (France); Bonin, B. [CEA Saclay, DEN/DIR/DS, 91191 Gif-sur-Yvette cedex (France); Godon, N.; Lartigue, J.-E.; Jollivet, P. [CEA Marcoule, DTCD/SECM/LCLT, BP 17171, 30207 Bagnols-sur-Ceze cedex (France); Ayral, A. [IEM/CNRS-ENSCM Universite Montpellier 2, CC 047, Place Eugene Bataillon, 34095 Montpellier cedex 5 (France); De Windt, L. [ENSMP, CG, 35 rue St Honore, 77305 Fontainebleau cedex (France); Santarini, G. [CEA Saclay HC/CAB, 91191 Gif-sur-Yvette cedex (France)

    2008-10-15

    This article summarizes the present state of knowledge concerning aqueous alteration of R7T7-type nuclear containment glasses, represented mainly by the inactive reference glass designated SON68. Based on this review, we propose to describe the glass alteration kinetics up to and including the final residual rate regime by means of a new mechanistic model known as GRAAL (glassreactivitywithallowanceforthealterationlayer). Phenomenological analysis findings are reviewed for the various glass alteration regimes: interdiffusion, initial rate, rate drop, residual rate and, under very particular circumstances, resumption of alteration. These alteration regimes are associated with predominant mechanisms. Published work interpreting and modeling these mechanisms was examined in detail. There is a broad consensus on the general mechanisms of the initial rate and even the interdiffusion regime, whereas the mechanisms controlling the rate drop remain a subject of dispute not only with regard to nuclear glasses but also for the dissolution of silicate minerals. The reaction affinity responsible for the rate drop is expressed differently by different authors and depending on the underlying theories. The disagreement concerns the nature of the phase (glass or gel) or the activated complex controlling the rate drop, which in turn determines the elements that must be taken into account in the overall affinity term. Progress in recent years, especially in identifying the mechanisms responsible for the residual rate, has shed new light on these issues, allowing us to propose new theoretical foundations for modeling the different kinetic regimes of SON68 nuclear glass dissolution. The GRAAL model considers that water diffusion in the passivating reaction zone (the gel formed under saturation conditions) is a rate-limiting step in the overall glass dissolution kinetics. Moreover, this passivation zone is a soluble phase whose stability is directly dependent on the nature of the

  11. Effect of clayey groundwater on the dissolution rate of SON68 simulated nuclear waste glass at 70 °C

    Science.gov (United States)

    De Echave, T.; Tribet, M.; Jollivet, P.; Marques, C.; Gin, S.; Jégou, C.

    2018-05-01

    To predict the long-term behavior of high-level radioactive waste glass, it is necessary to study aqueous dissolution of the glass matrix under geological repository conditions. The present article focuses on SON68 (an inactive surrogate of the R7T7 glass) glass alteration in synthetic clayey groundwater at 70 °C. Experiments in deionized water as reference were also performed in the same conditions. Results are in agreement with those of previous studies showing that magnesium present in the solution is responsible for higher glass alteration. This effect is transient and pH-dependent: Once all the magnesium is consumed, the glass alteration rate diminishes. Precipitation of magnesium silicate of the smectite group seems to be the main factor for the increased glass alteration. A pH threshold of 7.5-7.8 was found, above which precipitation of these magnesium silicates at 70 °C is possible. TEM observations reveal that magnesium silicates grow at the expense of the passivating gel, which partly dissolves, forming large pores which increase mass transfer between the reacting glass surface and the bulk solution.

  12. Nuclear waste glasses of SON68 type and their weathering products, optical spectroscopy of uranium and rare earth elements

    International Nuclear Information System (INIS)

    Ollier, N.

    2002-09-01

    This study concerns the long-term behaviour of high-level waste glasses and more precisely lanthanides and uranium behaviour with weathering. The leaching was performed on glass powder at 90 deg. C in a pseudo-dynamic mode. Two weathering gels were obtained, with different renewal rate and leaching duration. In glass, we demonstrate that U(IV) and U(VI) species coexist. Time-resolved spectroscopy and XPS measurements show that hexavalent uranium is present under uranyl entities and UO 3 type environment. In weathering gels, U(VI) is still present under uranyl form as well as uranyl hydroxide. It means that U behaviour depends on renewal rate, moreover precipitation of crystallized phases like bauranolte BaU 2 O 7 .xH 2 O and uranyl silicate of uranophane type occur. Concerning lanthanides, Eu 3+ was used as a luminescent local probe. Two sites were found in glass and gels. In glass, the sites were attributed to a silicate and a borate one. In gels, the silicate site is conserved whereas the second one is supposed to correspond to an aluminate one. Photoluminescence and Moessbauer measurements show that the rare earth site symmetry increases in gel. This result confirms that order is higher in gels than in glass. The third part of the thesis concerns irradiation effect in glasses. The main result shows some behaviour differences between a 5 oxides borosilicate glass and a more complex one close to the SON68 glass. Presence of mixed alkali (Na, Li and Cs) seems to notably reduce the Na migration. (author)

  13. A 25-year laboratory experiment on French SON68 nuclear glass leached in a granitic environment - First investigations

    Energy Technology Data Exchange (ETDEWEB)

    Guittonneau, C. [CEA Marcoule DTCD/SECM/LCLT, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France); Gin, S., E-mail: stephane.gin@cea.f [CEA Marcoule DTCD/SECM/LCLT, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France); Godon, N.; Mestre, J.P. [CEA Marcoule DTCD/SECM/LCLT, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France); Dugne, O.; Allegri, P. [CEA Marcoule DTEC/SGCS/LMAC, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France)

    2011-01-01

    We have investigated a 25.75-year old leaching experiment to improve our understanding of the mechanisms controlling glass dissolution in geological disposal conditions. A SON68 glass block was leached in slowly renewed synthetic groundwater (at 90 {sup o}C, 100 bar) in contact with some pieces of granite and Ni-Cr-Mo alloy as environmental storage materials. One hundred and sixty-three samplings were carried out over the entire duration of the experiment and were used to calculate the mean thickness of the altered glass (28 ({+-}9) {mu}m) and the glass dissolution rate. After few months, the rate remained very constant at 6 x 10{sup -3} g m{sup -2} d{sup -1} which is about 20 times higher than the residual rate measured in a batch reactor at the same temperature. At the end of the experiment, mainly SEM analyses were performed on the entire glass block. Surprisingly, the glass alteration layer has neither a homogeneous thickness, nor a homogeneous morphology. The location of the sampling valve (at half height of the glass block) seems to divide the glass block into two parts. In the upper half (above the sampling valve), the general morphology of the alteration layer consists in a relatively simple and uniform gel and some secondary phases which are rare-earth phosphates. The mean measured thickness of this alteration layer is 6.7 ({+-}0.3) {mu}m. However, in the lower half of the glass block, the gel is globally larger and frequently contains rounded shapes which are rare-earth phosphates. This section is edged by secondary phases bearing Mg, Na, Zn and Ni. The mean measured thickness is 81.3 ({+-}1.1) {mu}m in the lower half. In this experiment, the flow rate which leads to the hydrodynamic transport of the soluble species must be a key factor for the local glass alteration process. We have also shown that this unexpected behavior is likely due to heterogeneities of the chemistry of the solution. This conclusion is supported by the behavior of Mg. This element

  14. The role of pH in the vapor hydration at 175 °C of the French SON68 glass

    International Nuclear Information System (INIS)

    Ait Chaou, Abdelouahed; Abdelouas, Abdesselam; El Mendili, Yassine; Martin, Christelle

    2017-01-01

    The French simulated nuclear waste SON68 glass was altered in the presence of water vapor at 175 °C and 98% of relative humidity under several atmospheres (NH_3, H_2S, CO_2 and argon). The objectives were to study the role of pH on hydration kinetics and secondary phases formation. The hydration was followed by infrared spectroscopy and the nature and extent of alteration products were determined by characterizing the reacted glass surface with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), μ-Raman spectroscopy and X-ray diffraction (XRD). The glass hydration/alteration rate clearly increased with increasing pH, that is controlled by the gas atmosphere, as the following: NH_3 > Ar > CO_2 > H_2S. This can directly be linked to the secondary phases precipitated on the glass surface. Hence, the major alteration products observed at high pH (under NH_3 and Ar) are analcime and Ca-silicates hydrates (CSH) while at low pH (under CO_2 and H_2S) only a hydrated gel layer was identified. - Highlights: • The vapor hydration study of the SON68 glass under geological conditions. • The secondary phases formation in the alteration of SON68 glass. • The pH effect on the alteration kinetics of glass.

  15. Cesium incorporation in hollandite-rich multiphasic ceramic waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Tumurugoti, P.; Clark, B.M. [Kazuo Inamori School of Engineering, The New York State College of Ceramics, Alfred University, Alfred, NY 14802 (United States); Edwards, D.J. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Amoroso, Jake [Savannah River National Laboratory, Aiken, SC 29808 (United States); Sundaram, S.K. [Kazuo Inamori School of Engineering, The New York State College of Ceramics, Alfred University, Alfred, NY 14802 (United States)

    2017-02-15

    Hollandite-rich multiphase waste form compositions processed by melt-solidification and spark plasma sintering (SPS) were characterized, compared, and validated for nuclear waste incorporation. Phase identification by x-ray diffraction (XRD) and electron back-scattered diffraction (EBSD) confirmed hollandite as the major phase present in these samples along with perovskite, pyrochlore and zirconolite. Distribution of selected elements observed by wavelength dispersive spectroscopy (WDS) maps indicated that Cs formed a secondary phase during SPS processing, which was considered undesirable. On the other hand, Cs partitioned into the hollandite phase in melt-processed samples. Further analysis of hollandite structure in melt-processed composition by selected area electron diffraction (SAED) revealed ordered arrangement of tunnel ions (Ba/Cs) and vacancies, suggesting efficient Cs incorporation into the lattice.

  16. Cesium immobilization in (Ba,Cr)-hollandites: Effects on structure

    Science.gov (United States)

    Tumurugoti, Priyatham; Sundaram, S. K.; Misture, Scott T.

    2018-02-01

    Hollandites with compositions Ba1.15-xCs2xCr2.3Ti5.7O16 (0 ≤ x ≤ 1.15) intended for the immobilization of cesium (Cs) from nuclear waste have been prepared, characterized, and analyzed for Cs retention properties. Sol-gel synthesized powders were used for structural characterization using a combination of X-ray, neutron, and electron diffraction techniques. Phase-pure hollandites adopting tetragonal (I4/m) or monoclinic symmetry (I2/m) were observed to form in the compositional range 0 ≤ x ≤ 0.4. Structural models for the compositions, x = 0, 0.15, and 0.25 were developed from Rietveld analysis of powder diffraction data. Refined anisotropic displacement parameters (βij) for the Ba and Cs ions in the hollandite tunnels indicate local disorder of Ba/Cs along the tunnel direction. In addition, weak superlattice reflections were observed in X-ray and electron diffraction patterns that were due to the compositional modulation i.e., ordering of ions and vacancies along tunnel direction. Our overall observations suggest the phase-pure hollandites studied assumed supercell structures with ordered tunnel cations, which in turn have positional disorder in individual supercells.

  17. Analytical electron microscopy study of surface layers formed on the French SON68 nuclear waste glass during vapor hydration at 200 C

    International Nuclear Information System (INIS)

    Gong, W.L.; Wang, L.M.; Ewing, R.C.; Bates, J.K.; Ebert, W.L.

    1998-01-01

    Extensive solid-state characterization (AEM/SEM/HRTEM) was completed on six SON68 (inactive R7T7) waste glasses which were altered in the presence of saturated water vapor (200 C) for 22, 91, 241, 908, 1000, 1013, and 1021 days. The samples were examined by AEM in cross-section (lattice-fringe imaging, micro-diffraction, and quantitative thin-film EDS analysis). The glass monoliths were invariably covered by a thin altered rind, and the surface layer thickness increased with increasing time of reaction, ranging from 0.5 to 30 μm in thickness. Six distinctive zones, based on phase chemistry and microstructure, were distinguished within the well-developed surface layers. Numerous crystalline phases such as analcime, gyrolite, tobermorite, apatite, and weeksite were identified on the surfaces of the reacted glasses as precipitates. The majority of the surface layer volume was composed of two basic structures that are morphologically and chemically distinct: The A-domain consisted of well-crystallized fibrous smectite aggregates; and the B-domain consisted of poorly-crystallized regions containing smectite, possibly montmorillonite, crystallites and a ZrO 2 -rich amorphous silica matrix. The retention of the rare-earth elements, Mo, and Zr mostly occurred within the B-domain; while transition metal elements, such as Zn, Cr, Ni, Mn, and Fe, were retained in the A-domain. The element partitioning among A-domains and B-domains and recrystallization of the earlier-formed B-domains into the A-domain smectites were the basic processes which have controlled the chemical and structural evolution of the surface layer. The mechanism of surface layer formation during vapor hydration are discussed based on these cross-sectional AEM results. (orig.)

  18. Secondary phase formation and the microstructural evolution of surface layers during vapor phase alteration of the French SON 68 nuclear waste glass at 200 degrees C

    International Nuclear Information System (INIS)

    Gong, W.L.; Ewing, R.C.; Wang, L.M.

    1995-01-01

    The SON 68 inactive open-quotes R7T7close quotes composition is the French reference glass for the LWR nuclear waste glass. Vapor phase alteration was used to accelerate the reaction progress of glass corrosion and to develop the characteristic suite of secondary, alteration phases. Extensive solid-state characterization (AEM/SEM/HRTEM) was completed on six inactive R7T7 waste glasses which were altered in the presence of saturated water vapor (200 degrees C) for 91, 241, 908, 1000, 1013, and 1021 days. The AEM samples were examined in cross-section (lattice-fringe imaging, micro-diffraction, and quantitative thin-film EDS analysis). The glass monoliths were invariably covered with a thin altered rind. The layer became thicker with time: 0.5 μm for 22 days; 4 μm for 91 days; 6 μm for 241 days; 10 μm for 908 days; 26 μm for 1013 days; and 2 TeO 3 and (Ca,Sr)Mo 3 O 9 (OH) 2 , were found within the inner zones of surface layers, and they must have nucleated in situ, indicating that Ag, Te, Sr, and Mo can be retained within the surface layer. The majority of the surface layer volume is composed of two morphologically and chemically different structures: one consists of well-crystallized fibrous smectite aggregates occurring along with cavities, the A-domain; and the other consists of poorly-crystallized regions containing needle-like smectite (montmorillonite) crystallites, a silica-rich amorphous matrix, and possibly ZrO 2 particles, the B-domain

  19. Isotope tracing (29Si and 18O) of the alteration mechanisms of the French glass 'SON68' used for the storage of nuclear waste

    International Nuclear Information System (INIS)

    Valle, N.

    2001-01-01

    This study aims to enhance our understanding of the mechanisms of aqueous corrosion of the glasses used for the storage of nuclear waste. Glass samples 'SON68', doped with a different rare earth element (La, Ce or Nd), were altered simultaneously with water enriched in 29 Si and 18 O, throughout a period of 20 months. The aim of such isotope tracing was (i) to follow the 'real' exchanges between glass and solution and (ii) to understand the reactions involving Si-O bonds in the leached layer during alteration. Leachates were analyzed by ICP-MS and -AES, and elemental and isotopic variations in the altered glass layer were measured by ion-probe, using a depth profiling technique. Elemental analyses enabled the distribution of the elements in the two layers of altered glass (phyllosilicates and gel) to be established, and the results reveal a selective partitioning of elements between the two layers. Isotopic analyses of altered layers and leachates allowed phyllosilicates to be distinguished from gel, and suggest two different mechanisms of formation. Whilst phyllosilicates grow on the surface of the glass by a mechanism of precipitation, gel is formed by a succession of hydrolysis / condensation reactions taking place mainly at the gel / pristine glass interface. This gel is formed by the in situ rearrangement of hydrated species, without reaching equilibrium with the solution. Moreover, an experimental technique has been developed enabling one to trace the transport of silicon from the solution into the altered glasses, under an isotopic gradient. Diffusion profiles, obtained by ion-probe, have been modeled and have allowed the determination of the apparent silicon diffusion coefficient (DSi) in gels. Therefore, our experiments have permitted the quantification of the influence of both the alteration conditions (dynamic or static tests) and the solution composition on the value of DSi. (author)

  20. Raman scattering studies of mobile ions in superionic conductor hollandites

    International Nuclear Information System (INIS)

    Shibata, Y.; Suemoto, T.; Ishigame, M.

    1986-01-01

    The Raman spectra of the superionic conductors K/sub 1.6/Mg/sub 0.8/Ti/sub 7.2/O 16 , Cs/sub 1.2/Mg/sub 0.6/Ti/sub 7.4/O 16 , and (KTl)/sub 1.6/Mg/sub 0.8/Ti/sub 7.2/O 16 are measured in the frequency range from 5 to 1000 cm -1 . In the range from 100 to 1000 cm -1 Raman spectra hardly show alkali ion dependence. On the contrary, in the frequency range from 5 to 100 cm -1 , an additional Raman band is observed. This Raman band shows alkali ion dependence. By using the Frenkel-Kontorova model for the hollandite crystal with the given configuration of the mobile ions, it is found that the dependence of vibrational frequency of mobile ions with kinds of alkali ion is well explained and that the concept of 'super unit cell' that is introduced by Beyeler is very useful to explain the Raman bands which are observed below 100 cm -1 in hollandite crystals. (author)

  1. Hollandit a kryptomelan z Poniklé u Jilemnice, Česká republika

    Czech Academy of Sciences Publication Activity Database

    Jirásek, J.; Matýsek, D.; Vaculíková, Lenka; Sivek, M.

    -, č. 23 (2015), s. 1-6 ISSN 1211-0329 R&D Projects: GA MŠk ED2.1.00/03.0082; GA MŠk(CZ) LO1406 Institutional support: RVO:68145535 Keywords : hollandite supergroup * coronadite group * mineralogy * infrared spectroscopy * Poniklá Group Subject RIV: DB - Geology ; Mineralogy http://www.nm.cz/publikace/archiv.php?id=13

  2. Synthesis and structural and thermodynamical characterization of hollandite type material intended for the specific containment of cesium; Synthese et caracterisation de ceramiques de type hollandite destinees au conditionnement specifique du cecium

    Energy Technology Data Exchange (ETDEWEB)

    Leinekugel-Le-Cocq-Errien, A.Y

    2005-09-15

    This thesis deals with the characterization of the Ba{sub 1}Cs{sub 0.28}Fe{sub 0.82}Al{sub 1.46}Ti{sub 5.72}O{sub 16} hollandite envisaged for Cs containment. Techniques used are essentially classical powder XRD or synchrotron radiation at the absorption threshold of Ba and Cs, TEM and high-temperature calorimetry. Two syntheses have been studied: an alcoxide route and a dry route. After sintering, both routes lead to an incommensurate modulated tetragonal hollandite structure (space group: I4/m(00{gamma})00) with a modulation vector distribution. Before sintering, the material obtained by the alcoxide route is composed of three phases: a tetragonal hollandite like above, a monoclinic Ba-free hollandite and a weak-coherence-length phase containing only Ba. On contrary, the dry route already leads to the tetragonal hollandite at this step of the synthesis. High temperature oxide melt solution calorimetry was used to derive standard enthalpy of formation of hollandite to deduce its free enthalpy of formation. (author)

  3. An Electrochemical Sensor Based on Nanostructured Hollandite-type Manganese Oxide for Detection of Potassium Ions

    Directory of Open Access Journals (Sweden)

    Alex S. Lima

    2009-08-01

    Full Text Available The participation of cations in redox reactions of manganese oxides provides an opportunity for development of chemical sensors for non-electroactive ions. A sensor based on a nanostructured hollandite-type manganese oxide was investigated for voltammetric detection of potassium ions. The detection is based on the measurement of anodic current generated by oxidation of Mn(III to Mn(IV at the surface of the electrode and the subsequent extraction of the potassium ions into the hollandite structure. In this work, an amperometric procedure at an operating potential of 0.80 V (versus SCE is exploited for amperometric monitoring. The current signals are linearly proportional to potassium ion concentration in the range 4.97 × 10−5 to 9.05 × 10−4 mol L−1, with a correlation coefficient of 0.9997.

  4. The Verrès Castle Access Project

    Directory of Open Access Journals (Sweden)

    Tito Berti Nulli

    2010-10-01

    Full Text Available The article describes the access project of the Verrès castle, located in Aosta Valley in Italy, underlining some urban and transport planning and design elements. This project constitute in fact an interesting example of integration between transport infrastructure planning and design with urban planning strategy for tourism development. The transport infrastructure (in this case a vertical lift for tourism use has furthermore a deep attention to the landscape and social contest and a good architectural design. The Verrès castle access project represents and interesting example of sustainable mobility and of touristic area accessibility which is strong integrated with urban renewal and territorial development. The feasibility study, financed by the Verrès municipality, is part of a the INTERREG IIIA ACOLTRA Project financed by Italy and France with the aim of creating a network of transnational tourist itineraries. Through this initiative Aosta Valley and Haute-Savoy are developing a common tourism strategy that intends to promote cultural heritage and tourism mobility through the RITT (Reseaux d’Itineraires Touristiques Transfrontalieres. In this contest of intervention the study for the accessibility of the Verrès castle is inserted, with the aim of designing a mobility infrastructure for the main attraction of the valley and at the same of strengthening the appeal of tourist attraction of the whole area. The project is located in the small city of Verrés, that lies at 390m, on the banks of the river Evançon. As many of the Valdostani municipalities is characterized by several small urban centers, which are located in a around 8kmq, in a territory where live 2.700 inhabitants. The feasibility study examines three different alternative for a lift that should connect the Verrès centre with the castle. In particular different transport technology (inclined and vertical lift and several path alternatives have been evaluated. The final

  5. Ceramic Single Phase High-Level Nuclear Waste Forms: Hollandite, Perovskite, and Pyrochlore

    Science.gov (United States)

    Vetter, M.; Wang, J.

    2017-12-01

    The lack of viable options for the safe, reliable, and long-term storage of nuclear waste is one of the primary roadblocks of nuclear energy's sustainable future. The method being researched is the incorporation and immobilization of harmful radionuclides (Cs, Sr, Actinides, and Lanthanides) into the structure of glasses and ceramics. Borosilicate glasses are the main waste form that is accepted and used by today's nuclear industry, but they aren't the most efficient in terms of waste loading, and durability is still not fully understood. Synroc-phase ceramics (i.e. hollandite, perovskite, pyrochlore, zirconolite) have many attractive qualities that glass waste forms do not: high waste loading, moderate thermal expansion and conductivity, high chemical durability, and high radiation stability. The only downside to ceramics is that they are more complex to process than glass. New compositions can be discovered by using an Artificial Neural Network (ANN) to have more options to optimize the composition, loading for performance by analyzing the non-linear relationships between ionic radii, electronegativity, channel size, and a mineral's ability to incorporate radionuclides into its structure. Cesium can be incorporated into hollandite's A-site, while pyrochlore and perovskite can incorporate actinides and lanthanides into their A-site. The ANN is used to predict new compositions based on hollandite's channel size, as well as the A-O bond distances of pyrochlore and perovskite, and determine which ions can be incorporated. These new compositions will provide more options for more experiments to potentially improve chemical and thermodynamic properties, as well as increased waste loading capabilities.

  6. Maison de verre / Zonestraal. Relato de dos edificios

    Directory of Open Access Journals (Sweden)

    Jan Molema

    2014-01-01

    Full Text Available Desde los años sesenta del siglo XX el sanatorio Zonnestraal de Hilversum y la Maison de Verre en París han sido descritos extensamente en la literatura de la arquitectura moderna. Sin embargo, no se ha hecho ningún esfuerzo por colocarlos juntos en un mismo relato. Este ensayo es un esfuerzo para enmendar ese vacío. Ambos están relacionados íntimamente por sus autores: Bernard Bijvoet, como codiseñador de los planos de la Maison, y Johannes Duiker, quien trabajó con el anterior en los preliminares de Zonnestraal, aunque lo finalizó en solitario, al mismo tiempo que se terminó el diseño de la casa. En el trabajo se cuestiona además, ofreciendo fundadas conjeturas, la creencia establecida de que se precisó una nueva estructura metálica para sustentar la inalterada vivienda situada encima de la Maison de Verre.

  7. Vitrail, verre et archéologie entre le ve et le xiie siècle

    OpenAIRE

    Sapin, Christian

    2010-01-01

    Depuis longtemps, les fouilles archéologiques ont fait apparaître des fragments de verre en très grand nombre. L’intérêt des archéologues, orienté dans un premier temps vers les verres creux, se tourne de plus en plus vers les fragments de verre plat. Ceci conduit à poser de nouvelles questions sur les diverses utilisations du verre dans l’architecture, tant civile que religieuse, en particulier pour ce qui touche à la fermeture des baies ou au décor intérieur. Cette publication fait un point...

  8. Vitrail, verre et archéologie entre le ve et le xiie siècle

    Directory of Open Access Journals (Sweden)

    Christian Sapin

    2010-10-01

    Full Text Available Depuis longtemps, les fouilles archéologiques ont fait apparaître des fragments de verre en très grand nombre. L’intérêt des archéologues, orienté dans un premier temps vers les verres creux, se tourne de plus en plus vers les fragments de verre plat. Ceci conduit à poser de nouvelles questions sur les diverses utilisations du verre dans l’architecture, tant civile que religieuse, en particulier pour ce qui touche à la fermeture des baies ou au décor intérieur. Cette publication fait un point...

  9. Fibers and cylinders of cryptomelane-hollandite in Permian bedded salt, Palo Duro Basin, Texas

    International Nuclear Information System (INIS)

    Belkin, H.E.; Libelo, E.L.

    1987-01-01

    Fibers and thin-walled, hollow cylinders of cryptomelane-hollandite have been found in both the chevron and the clear salt from various drill cores in Permian bedded salt from the Palo Duro Basin, Texas. The authors have found fibers or cylinders from only the lower San Andres Formation units 4 and 5, the upper San Andres Formation, and the Salado-Transill salt. The fibers are inorganic, light to dark reddish brown, pleochroic, highly birefringent, filamentary single crystals, < 1 to ∼ 5 μm in diameter, with length-to-diameter ratios of at least 20:1. The fibers can be straight and/or curved, can bifurcate, can form loops, waves or spirals, and can be isolated or in parallel groups. Detailed petrographic analyses show no evidence for recrystallization or deformation of the enclosing salt after fiber formation. Although the authors observations do not provide a definitive explanation for fiber origin, they suggest that the fibers grew in situ by a solid-state diffusional process at low temperatures. The cylinders are pleochroic, highly birefringent, light to dark reddish brown, hollow, thin-walled, open-ended right cylinders, having a 1- to 2-μm wall thickness and variable lengths and diameters. There also appear to be single crystals of cryptomelane-hollandite, but these are found almost entirely in fluid inclusions in the chevron and clear salt. Their presence in the primary halite suggests that they were formed contemporaneously with the chevron structure and were accidentally trapped in the fluid inclusions. The observation of cylinders partially or completely enclosed by salt stratigraphically above large fluid inclusions suggests that natural downward fluid-inclusion migration has occurred, in response to the geothermal gradient

  10. Fabrication, characterization and radiation damage stability of hollandite based ceramics devoted to radioactive immobilisation; Synthese, caracterisation et etude du comportement sous irradiation electronique de matrices de type hollandite destinees au confinement du cesium radioactif

    Energy Technology Data Exchange (ETDEWEB)

    Aubin-Chevaldonnet, V. [CEA Valrho, Dir. de l' Energie Nucleaire (DEN/DETCD/SCDV), Dept. d' Etudes du Traitement et du Conditionnement des Dechets, Service de Conditionnement des Dechets et Vitrification, 30 - Marcoule (France)

    2004-11-01

    Research on treating specifically the long-lived and high level nuclear wastes, notably cesium, is currently carried out in France. Cesium immobilization in host matrices of high chemical durability constitutes the favoured option. Hollandite matrix is a good candidate because of its high cesium incorporation ability and its excellent chemical stability. During this study, different compositions of hollandite ceramics Ba{sub x}Cs{sub y}C{sub z}Ti{sub 8-z}O{sub 16} (C = Al{sup 3+}, Cr{sup 3+}, Ga{sup 3+}, Fe{sup 3+}, Mg{sup 2+}, Sc{sup 3+}), synthesized by oxide route, were characterized in terms of structure, microstructure and physical and chemical properties. Iron ions seems to be the most suitable of the studied C cations to get high-performance hollandites. The stability of these ceramics under external electron irradiation, simulating the {beta} particles emitted by radioactive cesium, were also estimated, at the macroscopic and atomic scale. The point defects creation and their thermal stability were followed by electron paramagnetic resonance. (author)

  11. Structure, properties, and disorder in the new distorted-Hollandite PbIr{sub 4}Se{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Trump, Benjamin A., E-mail: btrump1@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218 (United States); Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD 21218 (United States); McQueen, Tyrel M., E-mail: mcqueen@jhu.edu [Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218 (United States); Department of Physics and Astronomy, Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD 21218 (United States); Department of Material Science and Engineering, Johns Hopkins University, Baltimore, MD 21218 (United States)

    2016-10-15

    The synthesis and physical properties of the new distorted-Hollandite PbIr{sub 4}Se{sub 8} are reported. Powder X-ray diffraction and transmission electron microscopy show that the structure consists of edge- and corner-sharing IrSe{sub 6} octahedra, with one-dimensional channels occupied by Pb. The structure contains Se-Se anion-anion bonding, leading to an electron count of Pb{sup 2+}(Ir{sup 3+}){sub 4}(Se{sub 2}){sup 2-}(Se{sup 2−}){sub 6}, confirmed by bond-valence sums and diamagnetic behavior. Structural and heat capacity measurements demonstrate disorder on the Pb site, due to the combination of lone-pair effects and the large size of the one-dimensional channels. Comparisons are made to known Hollandite and pseudo-Hollandite structures, which demonstrates that the anion-anion bonding in PbIr{sub 4}Se{sub 8} distorts its structure, to accommodate the Ir{sup 3+} state. An electronic structure calculation indicates semiconductor character with a band gap of 0.76(11) eV.

  12. Alkali-Resistant Mechanism of a Hollandite DeNOx Catalyst.

    Science.gov (United States)

    Hu, Pingping; Huang, Zhiwei; Gu, Xiao; Xu, Fei; Gao, Jiayi; Wang, Yue; Chen, Yaxin; Tang, Xingfu

    2015-06-02

    A thorough understanding of the deactivation mechanism by alkalis is of great importance for rationally designing improved alkali-resistant deNOx catalysts, but a traditional ion-exchange mechanism cannot often accurately describe the nature of the deactivation, thus hampering the development of superior catalysts. Here, we establish a new exchange-coordination mechanism on the basis of the exhaustive study on the strong alkali resistance of a hollandite manganese oxide (HMO) catalyst. A combination of isothermal adsorption measurements of ammonia with X-ray absorption near-edge structure spectra and X-ray photoelectron spectra reveals that alkali metal ions first react with protons from Brønsted acid sites of HMO via the ion exchange. Synchrotron X-ray diffraction patterns and extended X-ray absorption fine structure spectra coupled with theoretical calculations demonstrate that the exchanged alkali metal ions are subsequently stabilized at size-suitable cavities in the HMO pores via a coordination model with an energy savings. This exchange-coordination mechanism not only gives a wholly convincing explanation for the intrinsic nature of the deactivation of the reported catalysts by alkalis but also provides a strategy for rationally designing improved alkali-resistant deNOx catalysts in general.

  13. Structural Defects of Silver Hollandite, Ag(x)Mn8O(y), Nanorods: Dramatic Impact on Electrochemistry.

    Science.gov (United States)

    Wu, Lijun; Xu, Feng; Zhu, Yimei; Brady, Alexander B; Huang, Jianping; Durham, Jessica L; Dooryhee, Eric; Marschilok, Amy C; Takeuchi, Esther S; Takeuchi, Kenneth J

    2015-08-25

    Hollandites (OMS-2) are an intriguing class of sorbents, catalysts, and energy storage materials with a tunnel structure permitting one-dimensional insertion and deinsertion of ions and small molecules along the c direction. A 7-fold increase in delivered capacity for Li/AgxMn8O16 electrochemical cells (160 versus 23 mAh/g) observed upon a seemingly small change in silver content (x ∼1.1 (L-Ag-OMS-2) and 1.6 (H-Ag-OMS-2)) led us to characterize the structure and defects of the silver hollandite material. Herein, Ag hollandite nanorods are studied through the combined use of local (atomic imaging, electron diffraction, electron energy-loss spectroscopy) and bulk (synchrotron based X-ray diffraction, thermogravimetric analysis) techniques. Selected area diffraction and high resolution transmission electron microscopy show a structure consistent with that refined by XRD; however, the Ag occupancy varies significantly even within neighboring channels. Both local and bulk measurements indicate a greater quantity of oxygen vacancies in L-Ag-OMS-2, resulting in lower average Mn valence relative to H-Ag-OMS-2. Electron energy loss spectroscopy shows a lower Mn oxidation state on the surface relative to the interior of the nanorods, where the average Mn valence is approximately Mn(3.7+) for H-Ag-OMS-2 and Mn(3.5+) for L-Ag-OMS-2 nanorods, respectively. The higher delivered capacity of L-Ag-OMS-2 may be related to more oxygen vacancies compared to H-Ag-OMS-2. Thus, the oxygen vacancies and MnO6 octahedra distortion are assumed to open the MnO6 octahedra walls, facilitating Li diffusion in the ab plane. These results indicate crystallite size and surface defects are significant factors affecting battery performance.

  14. Evaluation de la bioactivité d’un verre synthétisé par voie sol-gel

    OpenAIRE

    BCHELLAOUI, Nizar

    2016-01-01

    D’un point de vue structural, on peut définir un verre comme « un solide non cristallin ». Certains verres se comportent comme des matériaux totalement inertes, d’autres sont biodégradables et d’autres enfin ont présentés une adaptation osseuse très satisfaisante. Ce dernier type particulier de verre; contenant de la silice, du calcium et des phosphates est appelé bioverre ou verre bioactif : il a la propriété de se lier intimement à l’os et de mieux s’adapter aux ti...

  15. Use of glasses as industrial dosimeters; Utilisation des verres comme dosimetres industriels

    Energy Technology Data Exchange (ETDEWEB)

    Balestic, F. [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Le Clerc, P.; Bonnaud, M. [Centre de Recherches des Glaceries de Saint-Gobain (France)

    1959-07-01

    Glasses have the property of colouring under the action of ionizing radiations. We endeavoured to specify the conditions under which the intensity of coloration can be used as a measure of the quantity of radiation to which the glass has been submitted. In the case of a glass loaded with cobalt, a study of the optical density at different wavelengths enabled us to find the factors governing the formation of coloured centres and their conservation in the glass. We give a set of calibrating curves for different values of these parameters (irradiation rate, irradiation temperature; fading time and fading temperature), enabling determination of radiation doses in the range from 10 000 to 1 000 000 rep from measured optical density. (author) [French] Les verres ont la propriete de se colorer sous l'action des rayonnements ionisants. Nous avons cherche a preciser les conditions dans lesquelles l'intensite de la coloration peut servir de mesure de la quantite du rayonnement auquel le verre a ete soumis. Dans le cas d'un verre charge au cobalt, l'etude de la densite optique a differentes longueurs d'onde a mis en evidence divers facteurs dont depend la formation des centres colores et leur conservation dans le verre. En prenant comme parametres ces divers facteurs (temperature d'irradiation, intensite d'irradiation, temperature de conservation et duree de conservation) nous avons etabli des courus d'etalonnage permettant la determination de doses entre 10 000 et 1 000 000 rep d'apres la densite optique observee. (auteur)

  16. Use of glasses as industrial dosimeters; Utilisation des verres comme dosimetres industriels

    Energy Technology Data Exchange (ETDEWEB)

    Balestic, F [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires; Le Clerc, P; Bonnaud, M [Centre de Recherches des Glaceries de Saint-Gobain (France)

    1959-07-01

    Glasses have the property of colouring under the action of ionizing radiations. We endeavoured to specify the conditions under which the intensity of coloration can be used as a measure of the quantity of radiation to which the glass has been submitted. In the case of a glass loaded with cobalt, a study of the optical density at different wavelengths enabled us to find the factors governing the formation of coloured centres and their conservation in the glass. We give a set of calibrating curves for different values of these parameters (irradiation rate, irradiation temperature; fading time and fading temperature), enabling determination of radiation doses in the range from 10 000 to 1 000 000 rep from measured optical density. (author) [French] Les verres ont la propriete de se colorer sous l'action des rayonnements ionisants. Nous avons cherche a preciser les conditions dans lesquelles l'intensite de la coloration peut servir de mesure de la quantite du rayonnement auquel le verre a ete soumis. Dans le cas d'un verre charge au cobalt, l'etude de la densite optique a differentes longueurs d'onde a mis en evidence divers facteurs dont depend la formation des centres colores et leur conservation dans le verre. En prenant comme parametres ces divers facteurs (temperature d'irradiation, intensite d'irradiation, temperature de conservation et duree de conservation) nous avons etabli des courus d'etalonnage permettant la determination de doses entre 10 000 et 1 000 000 rep d'apres la densite optique observee. (auteur)

  17. Préparation et caracterisation de composites ll verre-supraconducteur gg

    Science.gov (United States)

    Roblin-Semène, L.; Pradel, A.; Ribes, M.; Belouet, C.

    1994-11-01

    Several types of " glass/superconductor " composites were prepared by a uniaxial hot pressing method. The BiSrCaCuO oxides were the materials under investigation in this work. A preliminary study of glasses obtained in this BiSrCaCuO system indicated that phase separation with nodules of 50 to 100 nm generally occurs. Glasses used as parts of composites are : 1) PbOB2O3 ones because of their low transition temperature and their large thermal stability which were favourable to texturation of superconducting grains, 2) BiSrCaCuO (2212, 2223, 4334) glasses because further recrystallisation could be carried out to improve grain connectivity and at last 3) mixture of BiSrCaCuO glass and V2O5 or PbO-B2O3 to insure a compromise between texturing and connectivity. Resistivity and current density measurements indicated that these types of composites were potential candidates for use as current limiters. Différents composites " verre/supraconducteur " ont été préparés par pressage à chaud uniaxial. Nos travaux ont porté sur les oxydes " BiSrCaCuO ". Une étude préalable des verres de ce système a permis de mettre en évidence une séparation de phase avec présence de nodules dont la taille est comprise entre 50 et 100 nm. Les verres choisis pour l'élaboration de ces composites ont été : 1 ) le verre PbO-B2O3 dont la basse température de transition vitreuse et la grande stabilité thermique étaient des éléments favorables à une bonne texturation des grains supraconducteurs, 2) les verres BiSrCaCuO purs (2212, 2223, 4334) dont la recristallisation partielle par recuit a posteriori devait assurer une meilleure connectivité entre grains, et enfin 3) des mélanges " BiSrCaCuO (V) " + V2O5 OU PbO-B2O3 qui devaient permettre d'assurer un compromis entre texturation et connectivité. Les mesures de résistivité et de densité de courant montrent que ces composites sont de bons candidats pour des applications de limiteur de courant.

  18. Etude de la propagation sous critique dans les fibres de verre par relaxation de la charge

    OpenAIRE

    R'Mili , M.; Godin , N.; Lamon , J.

    2011-01-01

    International audience; Plusieurs fibres inorganiques de type verre ou céramique (à base de carbure de silicium) sont très sensibles à la propagation sous critique de fissures, activée chimiquement ou thermiquement. Dans ce cas la rupture survient d'une façon prématurée à un niveau de contrainte relativement bas comparé à la contrainte de rupture. Cet article propose une approche statistique de la rupture en fatigue statique fondée sur l'analyse de la rupture des fibres dans une mèche sollici...

  19. Le MusVerre, Sars-Poteries, Hauts-de-France

    OpenAIRE

    Schmitt , Daniel

    2017-01-01

    Le MusVerre, inauguré en 2016, présente une collection patrimoniale et contemporaine d'art verrier. Le scénario de la visite propose un parcours en deux temps avec une séquence historique : de l’histoire des « bousillés » à la création du musée avec une galerie technique qui donne un aperçu des gestes de l’art verrier. Puis une séquence contemporaine développe un panorama des collections d’art verrier d’aujourd’hui, dans leur grande richesse et originalité.

  20. Le plafond de verre chez les enseignants chercheurs en sociologie et démographie

    OpenAIRE

    Chenu, Alain; Martin, Olivier

    2016-01-01

    La féminisation de l’enseignement supérieur français va croissante : la discipline « sociologie, démographie » illustre bien cette évolution puisqu’en 2012 44 % des enseignants-chercheurs en « sociologie, démographie » sont des femmes alors que ce taux ne s’élevait qu’à 24 % en 1984. Pourtant, cette féminisation croissante cache la persistance d’un plafond de verre. Cet article en montre l’existence et cherche à l’expliquer. À cet effet, la carrière des enseignants-chercheurs est analysée éta...

  1. Nature de la phase basse temperature des verres de spin Heisenberg en dimension 3

    OpenAIRE

    PETIT , Dorothée

    2002-01-01

    I. A Campbell (Directeur) D.R. Grempel F. Hippert (rapporteur) O. Martin P. Norblad (rapporteur) E. Vincent; La question de l'existence d'une réelle transition de phase entre l'état paramagnétique et l'état verre de spin est une question qui a été débattue pendant de nombreuses années. Il semble dorénavant admis que le gel des spins à basse température ne se fasse pas de façon progressive, et l'existence d'une véritable transition à T9. finie est communément acceptée, mais de nombreuses quest...

  2. Etude du vieillissement des verres : corrélation entre émissivité apparente (IR) et transmittance (visible)

    OpenAIRE

    Guiheneuf , Vincent; Delaleux , Fabien; Riou , Olivier; Logerais , Pierre-Olivier; Durastanti , Jean-Félix

    2015-01-01

    International audience; Le verre joue un rôle majeur comme protection supérieure, substrat et piégeage de la lumière dans la plupart des systèmes PV. Cependant, des travaux ont montré qu'au cours de sa durée de vie, un panneau solaire photovoltaïque perd entre 10 et 15% de son rendement, essentiellement à cause de pertes optiques. Nous avons testé une méthode de contrôle non destructif et non intrusif permettant de diagnostiquer l'état de vieillissement du verre sodocalcique, à l'aide d'une c...

  3. Heavy ion irradiations on synthetic hollandite-type materials: Ba{sub 1.0}Cs{sub 0.3}A{sub 2.3}Ti{sub 5.7}O{sub 16} (A=Cr, Fe, Al)

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Ming, E-mail: mtang@lanl.gov [Materials Science & Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Tumurugoti, Priyatham; Clark, Braeden; Sundaram, S.K. [Kazuo Inamori School of Engineering, The New York State College of Ceramics, Alfred University, Alfred, NY 14802 (United States); Amoroso, Jake; Marra, James [Materials Science & Technology Directorate, Savannah River National Laboratory, Aiken, SC 29808 (United States); Sun, Cheng [Materials Science & Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lu, Ping [Sandia National Laboratories, Albuquerque, NM 87185 (United States); Wang, Yongqiang [Materials Science & Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Jiang, Ying-Bing [TEM Laboratory, University of New Mexico, Albuquerque, NM 87131 (United States)

    2016-07-15

    The hollandite supergroup of minerals has received considerable attention as a nuclear waste form for immobilization of Cs. The radiation stability of synthetic hollandite-type compounds described generally as Ba{sub 1.0}Cs{sub 0.3}A{sub 2.3}Ti{sub 5.7}O{sub 16} (A=Cr, Fe, Al) were evaluated by heavy ion (Kr) irradiations on polycrystalline single phase materials and multiphase materials incorporating the hollandite phases. Ion irradiation damage effects on these samples were examined using grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). Single phase compounds possess tetragonal structure with space group I4/m. GIXRD and TEM observations revealed that 600 keV Kr irradiation-induced amorphization on single phase hollandites compounds occurred at a fluence between 2.5×10{sup 14} Kr/cm{sup 2} and 5×10{sup 14} Kr/cm{sup 2}. The critical amorphization fluence of single phase hollandite compounds obtained by in situ 1 MeV Kr ion irradiation was around 3.25×10{sup 14} Kr/cm{sup 2}. The hollandite phase exhibited similar amorphization susceptibility under Kr ion irradiation when incorporated into a multiphase system. - Graphical abstract: 600 keV Kr irradiation-induced amorphization on single phase hollandites compounds occurred at a fluence between 2.5×10{sup 14} Kr/cm{sup 2} and 5×10{sup 14} Kr/cm{sup 2}. The hollandite phase exhibited similar amorphization susceptibility under Kr ion irradiation when incorporated into a multiphase system. This is also the first time that the critical amorphization fluence of single phase hollandite compounds were determined at a fluence of around 3.25×10{sup 14} Kr/cm{sup 2} by in situ 1 MeV Kr ion irradiation. Display Omitted.

  4. Synthesis and characterisation of the hollandite solid solution Ba1.2-xCsxFe2.4-xTi5.6+xO16 for partitioning and conditioning of radiocaesium

    Science.gov (United States)

    Bailey, Daniel J.; Stennett, Martin C.; Mason, Amber R.; Hyatt, Neil C.

    2018-05-01

    The geological disposal of high level radioactive waste requires careful budgeting of the heat load produced by radiogenic decay. Removal of high-heat generating radionuclides, such as 137Cs, reduces the heat load in the repository allowing the remaining high level waste to be packed closer together therefore reducing demand for repository space and the cost of the disposal of the remaining wastes. Hollandites have been proposed as a possible host matrix for the long-term disposal of Cs separated from HLW raffinate. The incorporation of Cs into the hollandite phase is aided by substitution of cations on the B-site of the hollandite structure, including iron. A range of Cs containing iron hollandites were synthesised via an alkoxide-nitrate route and the structural environment of Fe in the resultant material characterised by Mössbauer and X-ray Absorption Near Edge Spectroscopy. The results of spectroscopic analysis found that Fe was present as octahedrally co-ordinated Fe (III) in all cases and acts as an effective charge compensator over a wide solid solution range.

  5. Mécanismes d'action des fines et des granulats de verre sur la réaction alcali-silice et la réaction pouzzolanique

    OpenAIRE

    Idir, Rachida

    2009-01-01

    Le recyclage du verre mixte contenant plusieurs couleurs pour la fabrication de nouveaux verres n'est actuellement pas économiquement viable. Ceci explique la recherche d'autres débouchés que le stockage ou l'enfouissement en décharges. L'une des applications envisageables est sa valorisation dans la fabrication des ciments et des bétons. Néanmoins, il est nécessaire de gérer les deux principaux comportements que peut avoir ce verre lorsqu'il est mis en contact avec une matrice cimentaire, à ...

  6. Conséquences de l'apport de verre pilé à la surface du champ et de son incorporation dans la couche travaillée

    OpenAIRE

    de Louvigny, Nathalie

    2001-01-01

    Pour accroître le taux de recyclage du verre d'emballage, Eco-Emballage et BSN Glasspack ont recherché des débouchés alternatifs pour les 100 à 150.000 tonnes/an de calcin ? soit environ 5% du verre d'emballage - trop pollué pour être valorisé en verrerie. Pour estimer ce que seraient les conséquences de l'incorporation de verre au sol, les effets du verre sont mesurés dans les domaines chimiques biologiques et physiques au cours d'expérimentations au terrain et au laboratoire et les résultat...

  7. Synthesis of hollandite-type LixMnO2 by Li+ ion-exchange in molten salt and lithium insertion characteristics

    International Nuclear Information System (INIS)

    Kadoma, Yoshihiro; Oshitari, Satoru; Ui, Koichi; Kumagai, Naoaki

    2007-01-01

    The Li + ion-exchange reaction of K + -type α-K 0.14 MnO 1.93 .nH 2 O containing different amounts of water molecules (n = 0-0.15) with a large (2 x 2) tunnel structure has been investigated in a LiNO 3 -LiCl molten salt at 300 deg. C. The Li + ion-exchanged products were examined by chemical analysis, X-ray diffraction, and transmission electron microscopy measurements. The K + ions and the hydrogens of the water molecules in the (2 x 2) tunnels of α-MnO 2 were exchanged by Li + ions in the molten salt, resulting in the Li + -type α-MnO 2 containing different amounts of Li + ions and lithium oxide (Li 2 O) in the (2 x 2) tunnels with maintaining the original hollandite structure. The electrochemical properties and structural variation with initial discharge and charge-discharge cycling of the Li + ion-exchanged α-MnO 2 samples have been investigated as insertion compounds in the search for new cathode materials for rechargeable lithium batteries. The Li + ion-exchanged α-MnO 2 samples provided higher capacities and higher Li + ion diffusivity than the parent K + -type materials on initial discharge and charge-discharge cyclings, probably due to the structural stabilization with the existence of Li 2 O in the (2 x 2) tunnels

  8. Le moulage pour la reconstitution des lacunes en restauration de la céramique et du verre

    Directory of Open Access Journals (Sweden)

    Hélène Blanpain

    2012-06-01

    Full Text Available La technique de reconstitution des lacunes par moulage est très vaste. Elle présente une large gamme de produits et de procédés susceptibles d’être employés dans le domaine de la restauration de la céramique et du verre. Leur choix et leur bonne mise en œuvre dépendront de plusieurs facteurs comme la nature de l’élément à mouler, sa forme et la nature du matériau de comblement choisi.The technique of gap-filling by molding is very vast. It presents a wide range of products and processes than can be used in the field of the restoration of ceramic and glass objects. Their choice depends on several factors : the material of the object, its shape, and the choice of the filling product.

  9. Les adhésifs à photopolymérisation radicalaire employés pour le collage structural du verre en conservation-restauration.

    OpenAIRE

    Gillioz, Sandra

    2016-01-01

    Nous avons étudié la compatibilité des adhésifs photopolymérisables avec le collage du verre en conservation-restauration en nous focalisant sur leur résistance mécanique. Quatre adhésifs photopolymérisables à voie radicalaire ont été sélectionnés – Conloc® 665 (EGO®), Loctite® 350 (Henkel®), NOA® 61 (Norland Optical Adhesives®) et Verifix® LV740 (Bohle®) – en employant à titre de comparaison la résine époxyde de référence pour le collage structural du verre – Hxtal® Nyl-1 (Hxtal Adhesive®). ...

  10. Effet de la nature des ions alcalins et alcalino-terreux sur la structure d'un verre riche en terre

    OpenAIRE

    Quintas , Arnaud; Lenoir , Marion; Caurant , D.; Majérus , Odile; Dussossoy , Jean-Luc; Charpentier , Thibault; Neuville , Daniel R.; Gervais , Christel

    2006-01-01

    Dans le cadre d'une étude structurale d'un verre de confinement de déchets nucléaires de type aluminoborosilicate et riche en terres rares, l'influence de la nature des ions alcalins ou alcalino-terreux est analysée. Pour cela deux séries de verres ont été élaborées dans lesquelles l'ion Na+ (respectivement l'ion Ca2+) présent dans la composition de référence, est totalement substitué par un autre ion alcalin Li+, K+, Rb+ ou Cs+ (respectivement un autre ion alcalino-terreux Mg2+, Sr2+ ou Ba2+...

  11. Variation de la composition de nanoparticules de 1-10 nm obtenues par séparation de phase dans un verre de silice

    OpenAIRE

    Blanc , W; Francois-Saint-Cyr , H; Martin , I; Lecoustumer , P; Hombourger , C; R. Neuville , D.; Larson , D.J.; Prosa , T.J.; Guillermier , C

    2014-01-01

    National audience; Les verres contenant des nanoparticules ont de nombreuses applications industrielles, notamment grâce à leurs excellentes propriétés thermo-mécaniques [1]. Ils présentent aussi un intérêt pour les propriétés optiques. En effet, l'encapsulation d'ions luminescents (ions de terre rare par exemple) dans des nanoparticules entraînent de nouvelles propriétés de luminescence qui n'existeraient pas dans le verre hôte (bande d'émission élargie, efficacité quantique augmentée, etc) ...

  12. Etude de la structure et du comportement en cristallisation d'un verre nucléaire d'aluminoborosilicate de terre rare

    OpenAIRE

    Quintas , Arnaud

    2007-01-01

    Ce travail de thèse porte sur l'étude d'un verre aluminoborosilicate de terre rare de composition molaire 61,81 SiO2 - 3,05 Al2O3 - 8,94 B2O3 - 14,41 Na2O - 6,33 CaO - 1,90 ZrO2 - 3,56 Nd2O3, destiné au confinement des déchets issus du retraitement de combustibles nucléaires usagés à haut taux de combustion. Au niveau structural, nous nous sommes intéressés principalement au rôle des ions modificateurs sur l'organisation du réseau vitreux par le biais de différents changements de composition ...

  13. Mise au point du rheometre a cisaillement annulaire pour l'etude de rheologie d'un mastic bitumineux avec verre incorpore =

    Science.gov (United States)

    El Mansouri, Souleimane

    Dans le domaine viscoelastique lineaire (VEL, domaine des petites deformations), le comportement thermomecanique du bitume et du mastic bitumineux (melange uniforme de bitume et de fillers) a ete caracterise au Laboratoire des Chaussees et Materiaux Bitumineux (LCMB) de l'Ecole de technologie superieure (ETS) avec l'appui de nos partenaires externes : la Societe des Alcools du Quebec (SAQ) et Eco Entreprises Quebec (EEQ). Les proprietes rheologiques des bitumes et des mastics ont ete mesurees grâce a un nouvel outil d'investigation appele, Rheometre a Cisaillement Annulaire (RCA), sous differentes conditions de chargement. Cet appareil permet non seulement de solliciter des eprouvettes de tailles importantes par rapport a celles utilisees lors des essais classiques, mais aussi d'effectuer des essais en conditions quasi-homogenes, ce qui permet de donner acces a la loi de comportement des materiaux. Les essais sont realises sur une large gamme de temperatures et de frequences (de -15 °C a 45°C et de 0,03Hz a 10 Hz). Cette etude a ete menee principalement pour comparer le comportement d'un bitume avec celui d'un mastic bitumineux dans le domaine des petites deformations. neanmoins, dans une seconde perspective, on s'interesse a l'influence des fillers de verre de post-consommation sur le comportement d'un mastic a faibles niveaux de deformations en comparant l'evolution des modules complexes de cisaillements (G*) d'un mastic avec fillers de verre et un mastic avec fillers conventionnels (calcaire). Enfin, le modele analogique 2S2P1D est utilise pour simuler le comportement viscoelastique lineaire des bitumes et des mastics bitumineux testes lors de la campagne experimentale.

  14. Study of the mixed ferrite Basub(x)Tisub(4-2x)Fesub(2x)Osub(8) (x=0.65) with hollandite structure by electrical, magnetic and Moessbauer effect measurements

    International Nuclear Information System (INIS)

    Abbas, Y.; Ahmed, M.A.

    1982-01-01

    Mixed ferrite Basub(x)Tisub(4-2x)Fesub(2x)Osub(8) with hollandite structure has been studies by electrical, magnetic and Moessbauer effect measurements. Electrical measurements show a semiconducting behaviour and a triclinic phase transition at about 455 K. Susceptibility data show that the compound is paramagnetic in the range 80-300 K and can be interpreted in terms of Curie-Weiss behaviour above about 200 K yielding the parameters usub(eff)5.95B.M. and Osub(p)-320 K. The susceptibility curve shows eveidence for an important ferromagnetic component due to the short range interactions preceeding the antiferromagnetic ordering and leads to the conclusion of the existance of spin canting magnetic ordering at Tsub(N)80 K. The values of the chemical shift 0.43mm/sec and quadrupole splitting 0.44mm/sec are typical of high spin Fesup(Fe 3+ ) in distorted octahedral coordination

  15. Un verre de trop

    Directory of Open Access Journals (Sweden)

    Pascal Brissette

    2009-09-01

    Full Text Available Au nombre des mythes qui accompagnent la formation de la modernité littéraire, on compte celui de la bohème, qui témoigne, comme Nathalie Heinich l’a bien montré dans L’Élite artiste, des difficultés que les producteurs symboliques éprouvent à conjuguer les critères de la singularité et du travail en communauté. La théâtralité de la « vie de bohème », son excentricité, ses tics et son chic sont au fondement de regroupements d’écrivains qui défendent paradoxalement le caractère vocationnel de ...

  16. Synthesis of hollandite-type Li yMn 1- xCo xO 2 (x = 0-0.15) by Li + ion-exchange in molten salt and the electrochemical property for rechargeable lithium battery electrodes

    Science.gov (United States)

    Kumagai, Naoaki; Oshitari, Satoru; Komaba, Shinichi; Kadoma, Yoshihiro

    The Li + ion-exchange reaction of K +-type α-K 0.14MnO 1.93·0.18H 2O and its Co-doped α-K 0.14(Mn 0.85Co 0.15)O 1.96·0.21H 2O with a large (2 × 2) tunnel structure has been investigated in a LiNO 3/LiCl molten salt at 300 °C. The Li + ion-exchanged products were examined by chemical analysis, X-ray diffraction, and scanning and transmission electron microscopic measurements. Almost all the K + ions and the hydrogens of water molecules in the (2 × 2) tunnel of α-MnO 2 and its Co-doped one were exchanged by Li + ions in the molten salt, resulting in Li +-type α-MnO 2 and its Co-doped one containing Li + ions as well as Li 2O (lithium oxide) in the (2 × 2) tunnel with maintaining the original hollandite structure. The electrochemical properties including charge-discharge cycling of the Li + ion-exchanged α-MnO 2 and its Co-doped samples have been investigated as insertion compounds in the search for new cathode materials for rechargeable lithium batteries. The Li + ion-exchanged α-MnO 2 and its Co-doped samples provided higher capacities than the K +-type parent materials on initial discharge and charge-discharge cyclings, probably due to the structural stabilization with the existence of Li 2O in the (2 × 2) tunnels.

  17. Modélisation d'un choc thermique doux d'un verre S.S.C en utilisant l'approche thermomécanique

    Science.gov (United States)

    Malou, Z.; Hamidouche, M.; Madjoubi, M. A.; Bousbaa, C.; Bouaouadja, N.

    2005-05-01

    Dans ce travail, nous avons étudié l'endommagement du verre silico-sodo-calcique (trois différentes épaisseurs : 2mm, 4mm, et 8mm) par choc thermique descendant. Nous avons utilisé l'approche thermomécanique en terme de facteur d'intensité de contrainte en se basant sur un calcul numérique. Le choc thermique descendant, est la mise en contact brutal d'un échantillon, préalablement chauffé à une température Ti, avec un milieu dont la température Tf est inférieure à Ti. Le gradient thermique engendré induit des contraintes de tension dans les couches superficielles du corps. Ces contraintes peuvent conduire à la rupture du matériau. Les hypothèses prises en compte lors de la simulation sont comme suit : Le refroidissement des échantillons en verre chauffés à différentes températures, inférieures à sa température de transition, est fait par jet d'air à 20° C pendant 6 secondes. Ce temps est suffisant pour que la température des échantillons atteigne l'ambiante. Le coefficient de transfert de chaleur est de 600 W/°C.m2. Les températures chaudes ont été variées entre 100° C et 450° C. Lors des calculs, nous avons intégré, l'évolutions en fonction de la température des propriétés thermoélastiques du verre. Dans un premier temps, nous avons déterminé les températures et les contraintes transitoires dans l'échantillon à tout instant du choc thermique. Ensuite, nous avons déterminé l'évolution du facteur d'intensité de contrainte (FIC) durant le refroidissement. Enfin, les FIC calculés sont comparés à la ténacité (K1c) du matériau. Cette dernière a été mesurée en utilisant la mécanique linéaire de la rupture. Nous avons vérifié que quand le facteur FIC atteint la valeur de la ténacité dans la zone des défauts critiques, ces derniers se propagent d'une manière brutale causant ainsi la dégradation de l'échantillon. Par cette technique, nous avons directement accès à l'écart de température critique

  18. Les adhésifs à photopolymérisation radicalaire employés pour le cpllage structural du verre en conservation-restauration: Etude de la résistance au cisaillement de 4 adhésifs optiques polymérisables aux UV

    OpenAIRE

    Gillioz, Sandra,

    2016-01-01

    Les adhésifs photopolymérisables, dont la prise s’effectue en quelques secondes sous rayonnement ultraviolet (UV), représentent une option séduisante pour le collage du verre en conservationrestauration, particulièrement lorsque les fragments ne peuvent être maintenus de manière temporaire. Dans le présent travail, nous avons étudié la compatibilité des adhésifs photopolymérisables avec le collage du verre en conservation-restauration en nous focalisant sur leur résistance mécanique. Quatre a...

  19. Évaluation des caractéristiques mécaniques du polissoir en polyuréthanne utilisé comme porte abrasifs durant le processus du polissage du verre optique

    Science.gov (United States)

    Aliouane, T.; Bouzid, D.; Belkhir, N.; Bouzid, S.; Herold, V.

    2005-05-01

    La fabrication des composants en verre optique nécessite des moyens de grande précision dans les procédés de finition vue l'importance accordée à leur qualité.
Durant le processus de polissage des verres optiques, le polissoir est un élément clé et a un impact direct sur les performances des composants optiques, non seulement il est utilisé comme support de grains abrasifs mais il doit posséder la fonction de transmission de la pression aux grains. La connaissance de ses propriétés, essentiellement mécanique, est impérative afin d'obtenir un état de surface optimal des composants optiques destinés à remplir des fonctions très précises dans des appareils optiques très performants.
Dans cette étude, nous avons constaté que les propriétés des polissoirs en polyuréthanne tel que la dureté, le module d'élasticité et la densité varient au cours du polissage. Ce changement a des effets sur l'état de surface de verre optique, causé par le changement microstructural de la surface du polissoir (distribution et dimensions des pores) et par conséquent sur la quantité des abrasifs (en oxyde de cérium) insérée dans les pores, ce qui influe sur la quantité de verre enlevée et sur l'état de surface du composant.
Sur la base des résultats obtenus, il a été prouvé que le polissoir subit des modifications très importantes ce qui influe considérablement sur son efficacité de polissage.

  20. Experiments on the incorporation of concentrated solutions of fission products in glasses and micas; Essais d'incorporation de solutions concentrees de produits de fission dans des verres et des micas

    Energy Technology Data Exchange (ETDEWEB)

    Bonniaud, R; Cohen, P; Sombret, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    1) The plants designed for extracting the plutonium of the G1, G2, G3 reactors fuel rods will produce extremely concentrated tions of fission products. 2) Let us consider a synthetic solution of the 'G2' type: (2N NO{sub 3}H - 2,25 meq/cm{sup 3} AI{sup +++} - 5.10{sup -3} {sup 134}Cs - {sup 137}Cs tracer). We made various glasses and micas by adding and mixing the necessary adjuvants and baking (900 to 1400 deg. C) in a graphite crucible. 3) The products obtained had either the shape of a cylindrical pellet or were reduced into a fine powder. They were mixed with 300 cm{sup 3} of synthetic sea water during variable periods of time in order to study leaching of the activity. 4) Experiments were first carried on caesium because of its solubility. 5) Fabrication of micas on a large scale sets many technological problems more difficult to solve (1400 deg. C) than in the case of glasses (1000 deg. C). A comparative study on both micas and glasses showed that leaching of activity was more important in the micas. (author)Fren. [French] 1) La mise en service de l'Usine d'Extraction du Plutonium destinee en particulier au traitement des barres de combustibles de G1, G2, G3 fournira des solutions residuaires concentrees de produits de fission. 2) Partant d'une solution synthetique 'G2': (2N NO{sub 3}H - 2,25meq/cm{sup 3} AI{sup +++} - 5.10{sup -3} {sup 134}Cs - {sup 137}Cs traceur) nous avens realise differents verres et micas apres adduction et melange des adjuvants necessaires suivis de cuisson (900 a 1400 deg. C) dans un creuset de graphite. 3) Les produits obtenus ont ete, soit sous forme d'eprouvette cylindrique, soit sous forme de poudre finement broyee, mis en contact et agites avec 300 cm{sup 3} d'eau de mer synthetique, durant des temps varies pour etudier la retention de l'activite. 4) Le cesium a ete choisi pour ces essais a cause de sa solubilite. 5) La fabrication de micas a grande echelle pose des problemes technologiques plus difficiles (1400 deg. C) a

  1. L’utilisation d’adhésifs optiques réticulables aux UV pour le collage d’objets d’art en verre transparent coloré, à surface d’encollage réduite

    Directory of Open Access Journals (Sweden)

    Viviane Bechoux

    2011-11-01

    Full Text Available La recherche porte sur une double problématique :1° La possibilité d’utiliser les adhésifs réticulables aux UV  pour coller le verre transparent coloré. 2° Le collage du verre  s’avère très complexe quand les éléments à assembler sont fins, fragiles et quand la surface d’encollage est réduite à quelques millimètres.Dans ce cas précis, la solidité mécanique du collage et la rapidité de polymérisation de l’adhésif sont les premiers critères à prendre en compte pour assurer un assemblage final fiable.This research focuses on two issues : 1° The possibility to use UV-crosslinkable adhesives to bond transparent coloured glass.2° The glass bonding is very complex when the parts to be joined are thin, fragile, and when the bonding surface is reduced to a few millimetres in size. In this case, the mechanical strength of the bonding and the speed of the curing process of the adhesive are the first criteria to be taken into account to ensure a reliable final bonding.

  2. Influence des défauts de la structure du verre sur la résistance mécanique des fibres optiques

    Science.gov (United States)

    Chmel, A.; Baptizmanski, V. V.; Kharshak, A. A.

    1992-12-01

    For silica (pure and doped) optical fibers prepared from preforms irradiated by thermal neutrons and Ar^+ ions, the measurements of lifetime under transverse stress were carried out. It is found that the neutron bombardment leads to decrease of the lifetime and the strength of fiber while the ion implantation results in increasing of these parameters. The influence of particle irradiation on the glass strength is explained by the generation of structural defects which were observed by the infrared an Raman spectroscopy methods. The direction of the change of mechanical properties of fibers is determined by the type of defects and their distribution in the cross-section of fiber. Des préformes de fibres optiques de silice ont été exposées à un bombardement par des faisceaux de neutrons thermiques et d'ions Ar^+ à énergie de 40 keV afin d'engendrer des défauts de la structure respectivement dans le volume ou dans la couche superficielle des échantillons. Les fibres obtenues des préformes irradiées et non irradiées ont été mises en charge de flexion. On a déterminé leur temps de rupture sous diverses contraintes de traction sur la surface extérieure de la fibre en flexion. On a observé une diminution du temps de rupture des fibres après le bombardement neutronique et une augmentation après l'implantation ionique. L'analyse de la nature des défauts en faisant appel à la spectroscopie infrarouge et Raman a fait ressortir que l'irradiation aux ions entraînait essentiellement des liaisons chimiques dans une fine couche superficielle de l'échantillon alors que l'irradiation aux neutrons occasionnait une déformation des zones du réseau silicique dans toute la section de la préforme et de la fibre. L'amélioration de la résistance mécanique s'explique par une augmentation de la mobilité des éléments structuraux de la matrice de verre par suite d'une rupture partielle des liaisons chimiques et sa diminution par l'apparition de concentrateurs

  3. Le verre à vitre et l’archéologie de la fin de l’Antiquité au XIIe siècle. Premières approches et perspectives

    Directory of Open Access Journals (Sweden)

    Christian Sapin

    2007-08-01

    Full Text Available Le vitrail a longtemps été considéré comme représentatif du plein Moyen Âge (XIe-XIIe siècle au plus tôt. Si quelques textes historiques impliquaient l’existence de vitrail à l’époque mérovingienne, la rareté des verres plats archéologiques, datés, ne permettait pas d’écrire avec précision une histoire du vitrail.Cette histoire est depuis quelques années revisitée par les sources archéologiques, aussi ténues puissent-elles paraître. La révolution la plus importante est, dans les années 1960,...

  4. Génération d'onde stokes du second ordre et effet laser dans une fibre optique a cœur suspendu en verre de chalcogénure AsSe

    OpenAIRE

    Hey Tow , Kenny; Besnard , Pascal; Brilland , Laurent; Toupin , Périne; Troles , Johann; Méchin , David; Trégoat , Denis

    2011-01-01

    National audience; Une étude expérimentale sur les propriétés de la rétrodiffusion Brillouin stimulée dans une fibre optique à cœur suspendu en verre de chalcogénure AsSe est présentée. Avec seulement un mètre de fibre, nous générons suffisamment de gain Brillouin pour obtenir un laser à fibre monomode de type Fabry-Perot. Nous démontrons aussi la génération du second ordre Brillouin dans ces fibres avec 0,5 W de pompe.

  5. Caractérisation expérimentale et modélisation numérique des propriétés spectroscopiques d'absorbants saturables pour le déclenchement passif de laser verre erbium

    Science.gov (United States)

    Girard, S.; Shcherbitsky, V.; Fromager, M.; Aït Ameur, K.; Moncorgé, R.; Ferrand, B.; Montagne, J.

    2002-06-01

    Une comparaison entre différents absorbants saturables (LMA, MALO, ZnS et ZnSe dopés Col^+ et ZnSe dopé Cr^{2+}) utilisables comme interrupteur optique passif pour déclencher les sources lasers verre erbium à 1.53 μm est présentée. Des expériences de saturation en simple passage sont interprétées en tenant compte de la distribution spatiale et temporelle du laser de pompe. Cette technique permet d'obtenir des sections efficaces de saturation effectives fiables et indépendantes des conditions de mesure sans introduire artificiellement d'absorption dans l'état excité qui, en principe, n'existe pas dans ce type de système contrairement aux études effectuées jusqu'ici sur ces matériaux.

  6. Contribution to the study of stimulated emission in neodymium-doped glass; Contribution a l'etude de l'emission stimulee dans le verre dope au neodyme

    Energy Technology Data Exchange (ETDEWEB)

    Jego, J M [Commissariat a l' Energie Atomique, Limeil-Brevannes (France). Centre d' Etudes; Faculte des Sciences de Rennes, 35 (France)

    1969-07-01

    annees pour voir les premieres realisations. Le maser fonctionnant dans le domaine des ondes micrometriques apparait en 1954. Dans le domaine optique, le premier 'LASER' est realise par MAIMAN en 1960. L'atome actif etait le chrome au sein d'une matrice d'alumine (rubis). le monocristal fluorescent etait place entre deux reflecteurs charges de maintenir dans le mileu une inversion provoquee de population jusqu'a atteindre les conditions d'emission. L'effet laser a permis de realiser beaucoup de generateurs de raies (plusieurs centaines) couvrant la gamme optique avec les mileux tant gazeux que liquides ou solides. Parmi ceux ci, le neodyme presente une transition entre les niveaux 4 F{sub 3/2} et 4 I{sub 11/2} qui a permis la realisation de lasers de tres grande puissance. Ce travail etudie les conditions de formation d'une impulsion declenchee et de son amplification dans le verre dope au neodyme. Des mesures precises des divers rendements interessants dans ces processus nous ont permis de connaitre la valeur de l'inversion de population realisee dans le milieu et d'etudier le detail de l'emission stimulee. (auteur)

  7. Nederlands pensioenstelsel verre van af

    NARCIS (Netherlands)

    Boot, A.

    2008-01-01

    Het Nederlandse pensioenstelsel wordt verblijd met een nieuw type pensioeninstelling, de API (Algemene Pensioeninstelling). In optimale vrijheid moet deze kunnen functioneren met een toezichtregime dat aansluit op zowel dat van verzekeraars als dat van pensioenfondsen. Het pensioenstelsel is daarmee

  8. Alteration of R7T7-type nuclear glass in deep geological storage conditions; Alteration du verre de confinement de dechets type R7T7 en condition de stockage geologique

    Energy Technology Data Exchange (ETDEWEB)

    Combarieu, G de

    2007-02-15

    This PhD thesis is aimed to study the alteration of SON68 glass, French inactive glass of R7T7-type, in contact with near field materials of a deep geological storage (French concept from ANDRA) which are mainly metallic iron and Callovo-Oxfordian clay. Therefore, experiments involving a 'glass-iron-clay' system at lab-scale have been carried out. Interactions between glass, iron and clay have been characterised from submicron to millimeter scale by means of SEM, TEM, XRD and XAS and Raman spectroscopies in terms of chemistry and crystal-chemistry. In the mean time, a conceptual model of glass alteration has been developed to account for most of the experimental observations and known mechanisms of alteration. The model has been then transposed within the transport-chemistry code HYTEC, together with developed models of clay and iron corrosion, to simulate the experiments described above. This work is thus a contribution to the understanding of iron corrosion in Callovo-Oxfordian clay and subsequent glass alteration in the newly formed corrosion products, the whole process being considered as a lab-scale model of a deep geological storage of radioactive wastes. (author)

  9. Alteration of R7T7-type nuclear glass in deep geological storage conditions; Alteration du verre de confinement de dechets type R7T7 en condition de stockage geologique

    Energy Technology Data Exchange (ETDEWEB)

    Combarieu, G. de

    2007-02-15

    This PhD thesis is aimed to study the alteration of SON68 glass, French inactive glass of R7T7-type, in contact with near field materials of a deep geological storage (French concept from ANDRA) which are mainly metallic iron and Callovo-Oxfordian clay. Therefore, experiments involving a 'glass-iron-clay' system at lab-scale have been carried out. Interactions between glass, iron and clay have been characterised from submicron to millimeter scale by means of SEM, TEM, XRD and XAS and Raman spectroscopies in terms of chemistry and crystal-chemistry. In the mean time, a conceptual model of glass alteration has been developed to account for most of the experimental observations and known mechanisms of alteration. The model has been then transposed within the transport-chemistry code HYTEC, together with developed models of clay and iron corrosion, to simulate the experiments described above. This work is thus a contribution to the understanding of iron corrosion in Callovo-Oxfordian clay and subsequent glass alteration in the newly formed corrosion products, the whole process being considered as a lab-scale model of a deep geological storage of radioactive wastes. (author)

  10. Nucléation et cristallisation dans un verre de chalcogénure du syste`me As sbnd Ge sbnd Se en présence d'un agent nucléant

    Science.gov (United States)

    Hemeda, D.; Tilloca, G.

    1988-05-01

    Le phénome`ne de nucléation initiépar un agent nucléant (HfSe) dans le verre de chalcogénure As 10 Ge 30Se 60 aétéétudiépar microscopieélectronique. La nucléation se caractérise par une période de latence dont la variation suit la solution analytique proposée par Kaschiev. Plusieurs parame`tres ontétéévalués: σ, l'énergie interfaciale; A, le facteur pré-exponentiel de l'équation générale de nucléation; ΔG D, la barrie`re cinétique de nucléation. Les résultats ontétéanalysés par la méthode basée sur les données de la viscositéet l'équation générale de nucléation. Une hypothe`se sur le mécanisme de la nucléation fondée sur l'action de l'agent nucléant aétéenvisagée. Les résultats relatifs au phénome`ne de croissance indiquent que la variation du taux de croissance réduit est analoguea`celle de matériaux ayant une entropie de fusionélevée et pour lesquels le mécanisme de croissance est régi par une nucléation de surface. L'énergie d'activation de croissance calculée est différente de la valeur estimée pour le verre non nucléédans le cas de l'écoulement visqueux. Une hypothe`se aétéenvisagée pour expliquer cetécart. L'évolution avec le temps de traitement thermique de la fraction cristallisée dans les matériaux aétésuivie par la technique de diffraction X quantitative. On observe une variation de type sigmoi¨dale avec une période de latence pour les différentes températuresétudiées. La cinétique de cristallisation suit l'équation de Johnson-Mehl-Avrami. La variation du taux de réaction avec la température est décrite par une expression de type Arrhénius.

  11. The Permanent Disposal of Highly Radioactive Wastes by Incorporation into Glass; Elimination Permanente de Dechets Hautement Radioactifs par Incorporation dans le Verre; 041e 041a 041e 041d 0427 0414 ; La Evacuacion Permanente de Desechos de Elevada Radiactividad Incorporandolos en Vidrio

    Energy Technology Data Exchange (ETDEWEB)

    Watson, L. C.; Aikin, A. M.; Bancroft, A. I. [Atomic Energy of Canada Ltd. (Canada)

    1960-07-01

    Development of a process for the incorporation of the high-level wastes from chemical processing operations into glass for permanent disposal has continued at Chalk River. The process has been demonstrated by making glass containing up to 50 curies of five- to six-year old mixed fission products per kg. The operation was batch wise, on a scale of four kg per batch. These operations showed that the fission products could be incorporated into glass safely and conveniently. Consideration of the many problems involved in the permanent storage or disposal of the highly radioactive glass has resulted in the conclusion that it should be buried in the ground or stored in artificial vaults. In such conditions, the disposal may always be-subjected to further control if required. If disposal is made directly to the ground, the principal method by which fission products can be released to the environment is by leaching from the glass into water. It is therefore considered important to know the rate at which fission products will be dispersed by this mechanism. Considerable data on leaching by water have been obtained in the laboratory. It has been found that the rates of release depend on the composition of the glass. For all the compositions tested the measurements showed that the rate of leaching of fission products from the glass decreased with time. After several months in water the rate of release of several compositions was about 10{sup -4} per cent per year from a two kg hemisphere of glass. The data obtained have been used to estimate the release of fission products from glass containing the large quantities of fission products which will accumulate from operation of power reactors. (author) [French] On poursuit a Chalk River les travaux de mise au point d'un procede permettant d'incorporer dans le verre, pour elimination permanente, des dechets hautement radioactifs provenant d'operations de traitement chimique! Aux fins de demonstration du procede, on a fabrique du

  12. Proposition d'un modèle expérimental pour la caractérisation de la réponse mécanique d'un composite (tissu de verre / résine époxyde)

    Science.gov (United States)

    Naceri, A.; Vautrin, A.

    2005-05-01

    L'objet de cet article est de proposer une géométrie d'éprouvette pour la caractérisation de la réponse mécanique d'un composite constitué de 12 plis de tissus de fibres de verre noyé dans une résine époxyde. Des essais de traction uniaxiale en rampe monotone réalisés sur différentes configurations géométriques d'éprouvettes avec différentes vitesses d'essais et le calcul numérique par éléments finis de la répartition des contraintes dans la zone centrale du modèle expérimental proposé, nous ont permis de justifier le choix d'une éprouvette profilée avec un rayon de 1000 mm qui présente une section réduite au centre et pour laquelle la rupture survient dans la zone centrale sans chute notable des caractéristiques mécaniques ultimes par rapport à l'éprouvette de forme parallélépipédique.

  13. High-sensitivity gamma spectroscopy for extended sources. Application to activity measurements on the human body, on glass, and on soil; Spectrographie gamma a grande sensibilite pour sources etendues. Application a la mesure de l'activite du corps humain, du verre et du sol

    Energy Technology Data Exchange (ETDEWEB)

    Jouve, B

    1962-07-01

    verres). (auteur)

  14. High-sensitivity gamma spectroscopy for extended sources. Application to activity measurements on the human body, on glass, and on soil; Spectrographie gamma a grande sensibilite pour sources etendues. Application a la mesure de l'activite du corps humain, du verre et du sol

    Energy Technology Data Exchange (ETDEWEB)

    Jouve, B

    1962-07-01

    (dosage du potassium dans les verres). (auteur)

  15. The Measurement of Integrated Gamma-Ray Doses in the Range 50 Mrad to 5 Mrad Using Phosphate Glass and Lithium Fluoride; Mesure, au Moyen de Verre au Phosphate et de Fluorure de Lithium, de Doses Integrees de Rayons Gamma de 50 Mrad a 5 Mrad; 0418 0417 041c 0414 ; Medicion de Dosis Integradas de Rayos Gamma de 50 Mrad a 5 Mrad por Medio de Vidrio al Fosfato y de Fluoruro de Litio

    Energy Technology Data Exchange (ETDEWEB)

    Webb, G. A.M. [Central Electricity Generating Board, Berkeley Nuclear Laboratories, Berkeley, Glos. (United Kingdom)

    1965-06-15

    }-ray fluxes. A comparison is made of the two systems for general convenience and also for use in particular situations. (author) [French] L'auteur a compare la radiophotoluminescence et la coloration du verre au phosphate a la thermoluminescence du fluorure de lithium aux fins de dosimetrie pour des doses de rayons gamma de 50 mrad a 5 Mrad. Il a mesure la luminescence produite dans du verre au phosphate active a l'argent, de faible numero atomique, a l'aide d'un fluorimetre industriel (dosimetre Toshiba au verre au fluor) complete d'un spectrophotometre permettant de mesurer les variations de la densite optique pour les doses elevees. Les effets des differentes methodes de nettoyage du verre ont ete etudies. L'auteur a mesure la thermoluminescence du fluorure de lithium en utilisant un appareil de lecture de laboratoire afin d'obtenir des courbes de luminescence et en integrant ensuite la region situee sous le pic approprie. Il a mesure le spectre d'emission de la thermoluminescence au moyen de filtres optique qui ont egalement servi a reduire au minimum les effets des infrarouges emis par la plaque de chauffage. Il a etudie les effets des filtres optiques et de la mesure sous azote sur le pic de tribothermoluminescence. L'auteur a etudie et compare plusieurs parametres du rendement des deux systemes. Avec le verre, on peut mesurer une gamma d'intensites tres etendue, allant de 5 * 10{sup -2} a 5 * 10{sup 6} rad, soit une etendue de l'ordre de 10{sup 8} ; en revanche, LiF peut etre utilise pour des doses legerement plus faibles, mais il atteint le point de saturation pour les doses superieures a 10{sup 5} rad. Le LiF est presque dependant de l'energie, mais le verre presente un ecart maximum equivalent a sept fois la reponse au {sup 60}Co a 60 keV; cet ecart peut etre corrige a l 'aide d'ecrans qui ont l'inconvenient d'elever la limite inferieure d'energie. Le phenomene d'evanouissement du verre a ete etudie de maniere approfondie; celui du LiF, qui est moins prononce, n

  16. Pore-Scale Flow Simulations: Model Predictions Compared with Experiments on Bi-Dispersed Granular Assemblies Simulation d’écoulements à l’échelle porale : comparaison des prédictions du modèle et d’expériences sur mélanges de billes de verre bi-disperses

    Directory of Open Access Journals (Sweden)

    Tong A.-T.

    2012-11-01

    Full Text Available A method is presented for the simulation of pore flow in granular materials. The numerical model uses a combination of the discrete element method for the solid phase and a novel finite volume formulation for the fluid phase. The solid is modeled as an assembly of spherical particles, where contact interactions are governed by elasto-plastic relations. Incompressible Stokes flow is considered, assuming that inertial forces are small in comparison with viscous forces. Pore geometry and pore connections are defined locally through regular triangulation of spheres, from which a tetrahedral mesh arises. The definition of pore-scale hydraulic conductivities is a key aspect of this model. In this sense, the model is similar to a pore-network model. Permeability measurements on bi-dispersed glass beads are reported and compared with model predictions, validating the definition of local conductivities. Une méthode est présentée pour la simulation de l’écoulement porale dans les matériaux granulaires. Le modèle numérique est basé sur la méthode des éléments discrets pour la phase solide et sur une nouvelle méthode de type volumes finis pour la phase fluide. Le solide est modélisé comme un arrangement de particules sphériques avec des interactions de type élasto-plastique aux contacts. On considère un écoulement de Stokes incompressible en supposant que les forces inertielles sont négligeables par rapport aux forces visqueuses. La géométrie des pores et leur connectivité sont définies sur la base d’une triangulation régulière des sphères qui aboutit à un maillage tétraédrique. La définition des conductivités hydrauliques à l’échelle des pores est un point clef du modèle qui se rapproche sur ce point à des modèles de type pore-network. Des mesures de perméabilités sur des assemblages bi-disperses de billes de verre sont présentées et comparées aux prédictions du modèle ce qui valide la définition des

  17. Electron paramagnetic resonance study of radicals formed by radiolysis at 77 K of nitroalkanes and of their solutions in organic glasses. Chromatography analysis of radiolysis products of nitromethane in ethanol solution in a vitreous medium; Etude par resonance paramagnetique electronique des radicaux formes par radiolyse a 77 K des nitroalcanes et de leurs solutions dans les verres organiques analyse par chromatographie des produits de la radiolyse du nitromethane en solution dans l'ethanol en milieux vitreux

    Energy Technology Data Exchange (ETDEWEB)

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

    1968-05-01

    etude porte sur la structure et la reactivite des radicaux formes par irradiation 7 des derives nitres a 77 K, et sur le mecanisme de formation et de disparition de ces radicaux dans les differentes matrices utilisees. Les radicaux resultant de l'arrachement d'un hydrogene en {alpha} du groupe NO{sub 2}, et les radicaux resultant de reactions d'addition sur le groupe nitre caracterises par un electron non apparie sur l'azote ont ete identifies, soit dans la radiolyse des nitroalcanes purs, soit dans la radiolyse a 77 K des nitroalcanes en solution dans les verres organiques. La conformation et les mouvements des radicaux dans les matrices, le mecanisme de formation des radicaux observes resultant generalement de la capture par les nitroalcanes des especes primaires de la radiolyse ont ete etudies. Les nitroalcanes en solution dans l'ethanol se manifestent a la fois comme capteurs d'electrons et de radicaux libres. L'etude de la radiolyse des nitroalcanes en solution dans un verre polaire d'ethanol a ete completee par des analyses chimiques des produits finals de la radiolyse; elle nous a permis de deduire l'efficacite de capture des electrons pieges et des radicaux libres par les nitroalcanes dans l'ethanol. Pour cela nous avons dose, pour le systeme nitro-methane - ethanol les rendements radiochimiques de-l'hydrogene, de l'acetaldehyde et du glycol en fonction de la concentration en capteur. Un mecanisme de disparition des radicaux observes a ete propose. (auteur)

  18. Electron paramagnetic resonance study of radicals formed by radiolysis at 77 K of nitroalkanes and of their solutions in organic glasses. Chromatography analysis of radiolysis products of nitromethane in ethanol solution in a vitreous medium; Etude par resonance paramagnetique electronique des radicaux formes par radiolyse a 77 K des nitroalcanes et de leurs solutions dans les verres organiques analyse par chromatographie des produits de la radiolyse du nitromethane en solution dans l'ethanol en milieux vitreux

    Energy Technology Data Exchange (ETDEWEB)

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

    1968-05-01

    radiolyse. Notre etude porte sur la structure et la reactivite des radicaux formes par irradiation 7 des derives nitres a 77 K, et sur le mecanisme de formation et de disparition de ces radicaux dans les differentes matrices utilisees. Les radicaux resultant de l'arrachement d'un hydrogene en {alpha} du groupe NO{sub 2}, et les radicaux resultant de reactions d'addition sur le groupe nitre caracterises par un electron non apparie sur l'azote ont ete identifies, soit dans la radiolyse des nitroalcanes purs, soit dans la radiolyse a 77 K des nitroalcanes en solution dans les verres organiques. La conformation et les mouvements des radicaux dans les matrices, le mecanisme de formation des radicaux observes resultant generalement de la capture par les nitroalcanes des especes primaires de la radiolyse ont ete etudies. Les nitroalcanes en solution dans l'ethanol se manifestent a la fois comme capteurs d'electrons et de radicaux libres. L'etude de la radiolyse des nitroalcanes en solution dans un verre polaire d'ethanol a ete completee par des analyses chimiques des produits finals de la radiolyse; elle nous a permis de deduire l'efficacite de capture des electrons pieges et des radicaux libres par les nitroalcanes dans l'ethanol. Pour cela nous avons dose, pour le systeme nitro-methane - ethanol les rendements radiochimiques de-l'hydrogene, de l'acetaldehyde et du glycol en fonction de la concentration en capteur. Un mecanisme de disparition des radicaux observes a ete propose. (auteur)

  19. Glass packages in interim storage; Les verres dans les stockages

    Energy Technology Data Exchange (ETDEWEB)

    Jacquet-Francillon, N

    1994-10-01

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

  20. Denkers over eenwording van heinde en verre - Ghandi en Europa

    NARCIS (Netherlands)

    prof. dr. Ben Hoetjes

    2006-01-01

    Europa raakt in de publieke beeldvorming in Nederland duidelijk op de achtergrond. Andere zaken - het nieuwe zorgstelsel, de pensioenen, de misdaad, het internationale terrorisme, mensenrechtenschendingen, natuurrampen - hebben allang de voorpagina's overgenomen. Voor Europa-aanhangers zoals

  1. 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

  2. Fixation of Radioactive Waste in Glass. Part I. Pilot-Plant Experience at Harwell; Fixation des Dechets Radioactifs dans le Verre, Premiere Partie: L'Usine Pilote de Harwell; 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 ; Fijacion de Desechos Radiactivos en Vidrio. Parte I: Experiencia Adquirida en la Instalacion Piloto de Harwell

    Energy Technology Data Exchange (ETDEWEB)

    Elliot, M. N.; Gayler, R.; Grover, J. R.; Hardwick, W. H. [Atomic Energy Research Establishment, Harwell (United Kingdom)

    1963-02-15

    The reasons for incorporating fission-product wastes into glass for long-term storage are outlined. The flow-sheet and operating cycle of the fixation process which has been developed at Harwell are described. Two years of operation of an inactive pilot plant are surveyed to show how the present operating conditions have been evolved. Full-length runs under these conditions have confirmed the reliability and reproducibility of the process. Engineering components suitable for an active plant have been developed and tested and the layout of die 1000-c pilot plant being commissioned at Harwell is illustrated in sketch form. Factors that affect the scale-up of the process are discussed in relation to the needs of the developing United Kingdom power programme. (author) [French] Les auteurs exposent les raisons pour lesquelles on incorpore les dechets de produits de fission dans le verre en vue d'un stockage de longue duree. Ils donnent le diagramme d'operations et le cycle du procede de fixation mis au point a Harwell. Ils decrivent les deux annees de fonctionnment de l'usine pilote, sans produits radioactifs, pour montrer comment les conditions actuelles d'operations ont ete mises au point. Des cycles complets realises dans ces conditions ont confirme la securite et la reproductibilite du processus. L'appareillage approprie pour une usine de haute activite a ete mis au point et essaye; les auteurs de crivent les grandes lignes de l'usine pilote (activite de 1000 c) en construction a Harwell. Les auteurs discutent les facteurs qui peuvent affecter le developpement de ce processus a plus grande echelle, eu egard aux besoins du programme energetique du Royaume-Uni. (author) [Spanish] Los autores exponen las razones que aconsejan incorporar los desechos y productos de fision a materiales vitreos para almacenarlos por tiempo largo. Describen el diagrama de circu- lacion y el ciclo de operaciones que integran el proceso de fijacion perfeccionado en Harwell. Examinan luego

  3. Dans le labyrinthe de verre. La négociation sur l'effet de serre

    OpenAIRE

    Hourcade , Jean Charles

    2002-01-01

    National audience; En parcourant les étapes principales de la « négociation climat », on fait apparaître le jeu de miroirs qui se déroule entre Europe et États-Unis, dans un contexte historique caractérisé par les débats sur la mondialisation, la volonté de leadership de l'Union européenne sur ce thème, la montée aux États-Unis d'inquiétudes sur le maintien de leur suprématie.On montre aussi pourquoi ce jeu, après avoir masqué des possibilités réelles de compromis, a débouché en 2000 sur l'éc...

  4. Les bracelets en verre de Nages, Gard (Les Castels, fouilles 1958-1981)

    OpenAIRE

    Feugère , Michel; Py , Michel ,

    1989-01-01

    The stratigraphy from Nages, an oppidum settled during the 3rd-Ist c. BC, provides a unique opportunity to set up the chronology of the glass bracelets produced and worn during this very period in Western Europe. Giving the complete inventory of these objects discovered during the excavations, this article allows to appreciate the function of glass bracelets in the female traditional dress of this period, but also to better place the region within the preroman trade networks.; La stratigraphi...

  5. Incorporation de particules de verre post-consommation dans un enrobe bitumineux de type ESG14

    Science.gov (United States)

    Lachance Tremblay, Eric

    In 2008, around 244,000 tons of glass was produced by the Quebec population. From this number, 128,000 tons were collected by various means of collection. Glass recycling is problematic because all the glass that cannot be classified according to the type can't be used to manufacture new products. It is therefore necessary to find new sources of uses for this material. Because the use of recycled materials in road structure material is beneficial from an environmental and sometimes structural point of view, the idea of using recycled glass into asphalt mixture was recently studied at the LCMB. Nowadays, the use of recycled glass in asphalt mixture is not regulated by the MTQ. This research goal was to verify the possibility of using recycled glass particles in a ESG14 asphalt mixture while maintaining equivalent properties and performance compared to a conventional mix. Different dosages of recycled glass particles have been studied to evaluate the effect of glass on the asphalt mixture volumetric characteristics, the ability of compaction and the rutting resistance. These mixes were formulated according to the LC formulation of the MTQ. The first part allowed selecting an optimal dosage of recycled glass particles. Thereafter, the thermo mechanical performance (resistance to low temperatures (TSRST), complex modulus (E*) and resistance to fatigue cracking), physical characteristics (macro texture and surface grip) and durability (resistance to water damage) of the asphalt mixture with the optimal dosage were evaluated and compared with a reference mixture. The results show that the ESG14 mixture with recycled glass formulated with the LC method is more susceptible to rutting than the reference mixture. Therefore, a reduction of the bitumen content can increase the rutting resistance while conserving equivalent properties to a conventional mix regarding resistance to low temperatures, complex modulus, resistance to fatigue cracking as well as the physical characteristics. Therefore, the use of recycled in glass seems to modify the asphalt behavior and increase the moisture susceptibility.

  6. Effet de la poudre de verre sur le fluage du C-S-H

    Science.gov (United States)

    Danilova, Maryna

    Glass is a unique inert material that could be recycled many times without changing its physical and chemical properties. Nevertheless, for some reason, large quantities of glass are still not recycled and therefore are stored as a waste. Its alternative recycling has become, since long, a major environmental problem. Moreover, glass is a potentially useful material for the development of ecological concrete, consequently, this way valorization seems to be imminent. In this research, characterization of the creep of concrete incorporating waste glass in powder form, i.e. glass powder (GP) as a supplementary cementitious material (GP-concrete) was carried out at a macro- and nanolevels. First, results from experimental study on the under load behaviour of GP-concrete are presented. Different types of strain occurring under load or after unload were discussed: quasi-instantaneous deformation, total mechanical deformation due to the maintained uniaxial compressive load during 1 year, total creep, basic creep, elastic recovery and total recovery. Shrinkage under drying conditions and endogenous shrinkage were also studied. After 1 year creep, the effects of constant load and drying on residual strength were also examined. A comparison was made concerning the final state of the porosity. Afterwards, the thesis reveals the results of tests conducted on the cement paste, going down to its composition and properties of the hydrated phases, in particular of calcium silicate hydrates (C-S-H). All of this, in order to conclude on the harmlessness use of GP regarding to the creep. Keywords : Glass powder, Air-entrained concrete, Creep, Shrinkage, C-S-H, Nanoindentation

  7. From glass structure to its chemical durability; De la structure du verre a sa durabilite chimique

    Energy Technology Data Exchange (ETDEWEB)

    Angeli, F.

    2009-07-01

    The author gives an overview of his research activities. He more precisely reports studies related to glass structure based on nuclei observed by NMR and present in glasses of interest for nuclear activities. He discusses the influence of chemical composition on structure, and discusses information which can be extracted from network formers (Al, B) and modifiers (Na, Ca), and from oxygen present in the network linkages of oxide glasses. He discusses the different experimental and modelling approaches which enable structural and morphological information to be obtained at a mesoscopic scale. The last part deals with the investigation of the long term behaviour of confinement matrices (glassy matrix for medium-activity wastes, ceramic matrix)

  8. Modeling of glass fusion furnaces; Modelisation des fours de fusion de verre

    Energy Technology Data Exchange (ETDEWEB)

    Mechitoua, N. [Electricite de France (EDF), 78 - Chatou (France). Direction des Etudes et Recherches; Plard, C. [Electricite de France, 77 - Moret sur Loing (France). Direction des Etudes et Recherches

    1997-12-31

    The furnaces used for glass melting are industrial installations inside which complex and coupled physical and chemical phenomena occur. Thermal engineering plays a major role and numerical simulation is a precious tool for the analysis of the different coupling, of their interaction and of the influence of the different parameters. In order to optimize the functioning of glass furnaces and to improve the quality of the glass produced, Electricite de France (EdF) has developed a specialized version of the ESTET fluid mechanics code, called `Joule`. This paper describes the functioning principle of glass furnaces, the interactions between heat transfers and flows inside the melted glass, the interactions between heat transfers and the thermal regulation of the furnace, the interactions between heat transfers and glass quality and the heat transfer interactions between the melted glass, the furnace walls and the combustion area. (J.S.)

  9. Ultimate Disposal of High-Level Radioactive Wastes - Fixation in Phosphate Glass with Emphasis on the Continuous Mode of Plant Operation; Elimination Definitive de Dechets de Haute Activite - Fixation dans du Verre au Phosphate en Vue d'une Exploitation de l'Installation en Continu; ОКОНЧАТЕЛЬНОЕ УДАЛЕНИЕ ВЫСОКОАКТИВНЫХ ОТХОДОВ - ФИКСАЦИЯ В ФОСФАТНОМ СТЕКЛЕ НА НЕПРЕРЫВНО РАБОТАПЦЕЙ УСТАНОВКЕ; Evacuacion Definitiva de Desechos de Elevada Radiactividad. Fijacion en Vidrio al Fosfato Atendiendo Particularmente a la Continuidad de la Marcha de la Instalacion

    Energy Technology Data Exchange (ETDEWEB)

    Hatch, L. P.; Weth, G. C.; Tuthill, E. J. [Brookhaven National Laboratory, Upton, Long Island, NY (United States)

    1963-02-15

    In the study of ultimate disposal of high-level radioactive wastes at Brookhaven National Laboratory emphasis is being placed on the formation of phosphate glasses as a means of incorporating the fission products in stable media. Of primary interest here is the development of a process in which the entire conversion from the raw aqueous wastes to the final.glass product would be carried out in an all-liquid system. The phosphate-glass method offers a number of important advantages in this respect and, in particular, lends itself to the development of a continuous process in which the liquid medium would be readily transferable from one process step to another. The paper presents the results of bench-scale studies on the production of phosphate glasses, with the continuous mode of operation, utilizing various types of aqueous wastes. The studies have been in progress for some 20 months and were carried out to determine essential operating parameters with particular attention paid to corrosion resistance and physical integrity of the high-temperature crucible. In addition, the paper discusses flow-sheet development together with the design and results of operation of. an engineering-scale plant having a capacity of 0.5 ft{sup 3} of glass per day with a continuous feed of simulated non-radioactive wastes. (author) [French] Dans l'etude des methodes d'elimination definitive des dechets de haute activite, le Laboratoire national de Brookhaven attache une grande importance aux verres au phosphate pour la fixation des produits de fission dans un milieu stable. On s'efforce essentiellement de mettre au point un processus dans lequel la transformation, depuis le dechet liquide et l'etat brut jusqu'au produit vitreux final, s'opererait entierement en phase liquide. A cet egard, le verre au phosphate presente un grand nombre d'avantages importants; en particulier, il se prete a la mise au point d'un processus continu dans lequel le milieu liquide pourrait facilement passer d

  10. 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)

  11. 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)

  12. The Megajoule laser, a giant with glass feet; Le laser megajoule, un colosse aux pieds de verre

    Energy Technology Data Exchange (ETDEWEB)

    Muller, X

    2009-07-15

    The successful simulation of the cracks that appear in the optics of the Megajoule laser is based on a multi-scale model. The immediate proximity of the crack is described via the molecular dynamics approach while a more global approach (used to describe a continuous medium) is applied for the region near the crack. One of the difficulties was to assure an efficient and consistent transfer of data between parameters described at very different scales. This simulation appears to be 4 times as fast as the previous one based exclusively on the molecular dynamics and can be used in a more exhaustive way to study cracks. For the first time, the propagation by rushes of the crack, its propagation velocity and the presence of dislocation lines in the ahead region of the crack have been reproduced. The origin of the cracks is still unknown but the tiny defects generated by the surface polishing might be the cause. (A.C.)

  13. Redox phenomena in glass melts; Les phenomenes d'oxydoreduction dans les verres d'oxyde

    Energy Technology Data Exchange (ETDEWEB)

    Pinet, O.; Di Nardo, Ch. [CEA Valrho, (DCC/DRRV/SCD), 30 - Marcoule (France)

    2000-07-01

    One of the major concerns in the glass-making industry is the control of redox mechanisms, which condition the glass properties and particularly refinement and color. The development of vitrification processes and vitreous materials for nuclear waste containment further emphasized the advantages of optimizing the glass oxidation state. The oxidation state of polyvalent species in a glass melt essentially depends on the basicity of the glass and the oxygen fugacity in the melt at a given temperature. Theoretical studies show that redox couples in glass melts can be classified according to their characteristic oxygen fugacities. This corresponds to the oxygen fugacity for which the concentrations of reduced and oxidized forms of the couple are equal. The quantity f{sub O{sub 2}}{sub char}. depends primarily on the redox couple considered, the basicity and the temperature of the glass melt. A classification of 36 redox couples is proposed here, covering a temperature range from 1085 deg C to 1500 deg C for silicate glass compositions for which the basicity can be characterized by theoretical optical basicity values [2) between 0.55 and 0.65. This classification is based on a variety of published experimental results obtained by different techniques. Figure 1 shows the satisfactory agreement obtained from these various studies. Figure 2 shows that the increase in f{sub O{sub 2}}{sub char}. with temperature in glasses with the same level of basicity ({lambda}= 0.57 {+-} 0.02) is consistent with the theory. From the characteristic oxygen fugacity values, potentiometric measurements of the oxygen fugacity in glass with an oxygen sensor allow in situ evaluation of the redox ratio. Voltammetric investigations of glasses can be used to supplement and refine the classification. The resulting Epeak values, expressed in terms of characteristic oxygen fugacity, are fully consistent with the values for other glasses of comparable basicity measured at comparable temperature. (authors)

  14. Influence of nuclear glasses composition on their liability to deterioration; Influence de la composition des verres nucleaires sur leur alterabilite

    Energy Technology Data Exchange (ETDEWEB)

    Tovena, I

    1995-09-29

    This contributes to the study of the nuclear glasses composition influence on their liability to deterioration. The methodology of the experimental research used has lead to define between the thirty oxides which form the reference glass light water, six oxides of interest. For each of these oxides, a composition variation area has been defined. A matrix of twenty glass compositions has then been defined. The preparation of materials of these compositions has sometimes lead to materials weakly heterogeneous which have been characterized before deterioration. This study has been completed by those of three glasses in a composition variation area narrower of the light water nuclear glass : the R7T7 and two glasses at limits having respectively an initial dissolution velocity at 100 degrees Celsius theoretically maximum and minimum. Some deterioration parameters in pure water have been experimentally measured on the twenty three glasses : 1) an initial dissolution velocity at 100 degrees (Vo{sub 1}00) Celsius and another one at 90 degrees Celsius (Vo{sub 9}0) 2) a dissolution velocity in conditions near the saturation at 90 degrees Celsius 3) an apparent solubility of glass based on the ortho silicic acid activity 4) the evolution of the dissolution kinetics at 90 degrees Celsius in sub-saturated medium towards saturated medium 5) the alteration films nature developed at the glasses surface during these last alteration tests. Some thermodynamic and structural models have been studied in order to predict Vo{sub 9}0 and Vo{sub 1}00. The dissolution kinetic law developed from reference glass dissolution results has been studied with the calculation code LIXIVER. It has not been able to be used for most of the glasses compositions studied. As a consequence, the glasses dissolution control by a surface reaction which are itself controlled by the only dissolved silica is an hypothesis which is not verified for the greater part of the glasses. (O.L.). refs., figs., tabs.

  15. In situ study of glasses decomposition layer; Etude in situ de la couche d`alteration de verres

    Energy Technology Data Exchange (ETDEWEB)

    Zarembowitch-Deruelle, O

    1997-10-21

    The aim of this work is to understand the involved mechanisms during the decomposition of glasses by water and the consequences on the morphology of the decomposition layer, in particular in the case of a nuclear glass: the R{sub 7} T{sub 7}. The chemical composition of this glass being very complicated, it is difficult to know the influence of the different elements on the decomposition kinetics and on the resulting morphology because several atoms have a same behaviour. Glasses with simplified composition (only 5 elements) have then been synthesized. The morphological and structural characteristics of these glasses have been given. They have then been decomposed by water. The leaching curves do not reflect the decomposition kinetics but the solubility of the different elements at every moment. The three steps of the leaching are: 1) de-alkalinization 2) lattice rearrangement 3) heavy elements solubilization. Two decomposition layer types have also been revealed according to the glass heavy elements rate. (O.M.) 59 refs.

  16. Europe and oil: beware of the glass ceiling; L'europe et le petrole: attention au plafond de verre

    Energy Technology Data Exchange (ETDEWEB)

    Durand, B. [ASPO France et de SLC France (France)

    2011-01-15

    Because current oil exporting countries consume an increasing share of their production and will shortly be producing less and less, available amounts of oil for the international market will decrease faster than world production, in spite of the emergence of new exporting countries such as Brazil or Kazakhstan. Owing to expanding consumption of major emerging countries, the share le for developed countries will drop rapidly, by approximately one third in the coming fifteen years. Europe, whose oil reserves will soon be exhausted, will almost entirely depend on outside sources. If it does not adjust through massive and swift consumption reduction, its material growth will be durably jeopardized due to substantial oil price increases. The adjustment requires strong and urgent measures to reduce the consumption of oil-based fuel in transportation, as well as of fuel oil by the residential and tertiary sectors. A selection of measures is set out. (author)

  17. Thermodynamical modeling of nuclear glasses: coexistence of amorphous phases; Modelisation thermodynamique des verres nucleaires: coexistence entre phases amorphes

    Energy Technology Data Exchange (ETDEWEB)

    Adjanor, G

    2007-11-15

    Investigating the stability of borosilicate glasses used in the nuclear industry with respect to phase separation requires to estimate the Gibbs free energies of the various phases appearing in the material. In simulation, using current computational resources, a direct state-sampling of a glassy system with respect to its ensemble statistics is not ergodic and the estimated ensemble averages are not reliable. Our approach consists in generating, at a given cooling rate, a series of quenches, or paths connecting states of the liquid to states of the glass, and then in taking into account the probability to generate the paths leading to the different glassy states in ensembles averages. In this way, we introduce a path ensemble formalism and calculate a Landau free energy associated to a glassy meta-basin. This method was validated by accurately mapping the free energy landscape of a 38-atom glassy cluster. We then applied this approach to the calculation of the Gibbs free energies of binary amorphous Lennard-Jones alloys, and checked the correlation between the observed tendencies to order or to phase separate and the computed Gibbs free energies. We finally computed the driving force to phase separation in a simplified three-oxide nuclear glass modeled by a Born-Mayer-Huggins potential that includes a three-body term, and we compared the estimated quantities to the available experimental data. (author)

  18. Influence of microorganisms on the alteration of glasses; Influence des microorganismes sur l'alteration des verres

    Energy Technology Data Exchange (ETDEWEB)

    Besnainou, B; Libert, M F [CEA Cadarache, 13 - Saint Paul lez Durance (France). Dept. d' Entreposage et de Stockage des Dechets

    1997-07-01

    Under specific conditions, microorganisms may enhance the alteration process of basaltic glass. However bacterial activity in the near field of a glass container would be possible only in environmental conditions provide nutrients and energetic substrates for bacterial growth. Depending of these conditions, microorganisms can: - modify the pH or the medium, - consume or produce soluble organic acids. To qualify the long term behaviour of glass, in presence of microorganisms, a qualitative and quantitative estimation of microbial activity potentialities and their consequences is needed. This must be achieved in studying the availability of the chemical species in the environment. (authors)

  19. Effet des terres rares sur la structure et l'altération des verres borosilicatés

    OpenAIRE

    Molières , Estelle

    2012-01-01

    This work is related to the question of the geological deep repository of high-level waste glass. These wastes include fission products and minor actinides, elements which can be simulated by rare earths. As new glass compositions could enable increased rare earth concentrations, it is crucial to know and understand rare earth impact on glass structure on the one hand, and on glass alteration kinetics or their incorporation into an altered layer. This work studied simplified borosilicate glas...

  20. Preparation and characterization of a PbO protective glass; Elaboration et caracterisation d un verre protecteur a base de PbO

    Energy Technology Data Exchange (ETDEWEB)

    Ayadi, Azzedine; Stiti, Nacera; Benaissa, Abdelazeze [Laboratoire des materiaux mineraux et composites, Faculte des sciences de l ingenieur - Universite de Boumerdes - 35000 Boumerdes - (Algeria); Palou, Martin [Departement ceramique et verre, Faculte de chimie, Universite de Bratislava - (Slovakia)

    2006-07-01

    The study of the binary system of lead silicate glass PbO-SiO{sub 2}, and particularly the glasses having more than 80% of PbO and no alkaline oxides allows to answer to some preoccupations and requirements towards these glasses, in particular their transparencies and their attenuation power, on account of the high values of the refractive index and the density of these glasses. Radiation protection is a field which concerns all the countries of the world including Algeria; this country is then concerned by the import of this product used in hospitals for instance. On account of the importance of this glass and of its wide application domain, it is interesting to study it in order to be able to manufacture it in Algeria and to improve its properties. The aim of this work is then to prepare different lead silicate glasses allowing a maximal absorption of the ionizing radiations. (O.M.)

  1. Modelling of nuclear glasses by classical and ab initio molecular dynamics; Modelisation de verres intervenant dans le conditionnement des dechets radioactifs par dynamiques moleculaires classique et ab initio

    Energy Technology Data Exchange (ETDEWEB)

    Ganster, P

    2004-10-15

    A calcium aluminosilicate glass of molar composition 67 % SiO{sub 2} - 12 % Al{sub 2}O{sub 3} - 21 % CaO was modelled by classical and ab initio molecular dynamics. The size effect study in classical MD shows that the systems of 100 atoms are more ordered than the larger ones. These effects are mainly due to the 3-body terms in the empirical potentials. Nevertheless, these effects are small and the structures generated are in agreement with experimental data. In such kind of glass, we denote an aluminium avoidance and an excess of non bridging oxygens which can be compensated by tri coordinated oxygens. When the dynamics of systems of 100 and 200 atoms is followed by ab initio MD, some local arrangements occurs (bond length, angular distributions). Thus, more realistic vibrational properties are obtained in ab initio MD. The modelling of thin films shows that aluminium atoms extend to the most external part of the surface and they are all tri-coordinated. Calcium atoms are set in the sub layer part of the surface and they produce a depolymerization of the network. In classical MD, tri-coordinated aluminium atoms produce an important electric field above the surface. With non bridging oxygens, they constitute attractive sites for single water molecules. (author)

  2. Le verre celtique de Nemcice nad Hanou. In: Kruta, V. ed.: Les Celtes en Bohême, en Moravie et dans le nord de la Gaule

    Czech Academy of Sciences Publication Activity Database

    Venclová, Natalie

    -, č. 313 (2006), s. 50-55 ISSN 1141-7137 R&D Projects: GA ČR(CZ) GA404/04/0118 Institutional research plan: CEZ:AV0Z80020508 Keywords : glass * glass working * ornament * La Tene period * Celts * Moravia Subject RIV: AC - Archeology, Anthropology, Ethnology

  3. Contribution des pratiques RSE à l'éclatement du plafond de verre et à l'engagement des femmes cadres : le cas de deux entreprises au Maroc

    OpenAIRE

    Bennani Meziane , Ghita

    2016-01-01

    Since women have been integrated to the labor market, they encounter barriers which slow down their professional evolution and limit their access to top management. The« glass ceiling » is the expression used to refer to these invisible barriers. This doctoral work proposes a contribution to the study of these barriers by placing it within a theoretical framework which integrates its antecedents and its consequences. More specifically, this thesis focuses on the impact of gender oriented Corp...

  4. Synthesis on the durability of composite fiberglass/epoxy resin structures; Synthese sur la durabilite des structures composites en fibres de verre/resine epoxide

    Energy Technology Data Exchange (ETDEWEB)

    Thevenin, P. [Electricite de France (EDF), Direction des Etudes et Recherches, 92 - Clamart (France)

    1997-12-31

    The purpose of this paper is to collect together in a systematic way information and results relating to the durability of composite fiberglass/ epoxy resin structures. First it is a matter of assessing the average level of understanding the long term behaviour of these structures which change under the combined effects of varied mechanical loading and stresses of a physico-chemical type linked to the environment. Looking at phenomena encountered and facts from current analyses, it will then be advisable to specify a methodology which can be applied to industrial piping used in PWR cooling systems for transporting raw water under pressure. In fact assessment of their service life is at present based on long and costly testing (ASTM D 2992 B standard), the appearance of which is inherited from metal piping testing.. Therefore it appears essential to study substitution test procedures, more composite specific and at the same time which can be conducted in reasonable time. For this purpose, by coherently accelerating and combining them in order not to underestimate their effects, ageing tests shall reproduce mechanisms representative of operating conditions. (author). 113 refs.

  5. heT BoeK PrediKer: een verrAssende en uiTdAgende sTem in de ...

    African Journals Online (AJOL)

    Precies in deze context moeten qohelet's bespiege lingen over de 'ijdelheid' van de dingen begrepen worden. 10 cf. delitzsch (1875:197): “Wenn das buch Koheleth altsalomonisch ware, so gäbe es keine geschichte der hebräischen sprache”. 11 voor een omstandiger bespreking van en uitgebreide bibliografie omtrent de ...

  6. Comportement de l’uranium et de ses simulants dans les verres d’aluminosilicates en contact avec des métaux fondus

    OpenAIRE

    Chevreux , Pierrick

    2016-01-01

    This study concerns an innovative process used for conditioning nuclear waste that contain metallic parts contaminated with actinides. High actinides concentrations are expected to be incorporated in the glass melt in contact with the molten metals. Among these metals, aluminum and/or stainless steel impose a strongly reducing environment to the glass melt involving redox reactions. These reactions modify actinides oxidation states and therefore change their solubilities in the glass and coul...

  7. Thermal stability of the French nuclear waste glass - long term behavior modeling; Etude de la stabilite thermique du verre nucleaire. Modelisation de son evolution a long terme

    Energy Technology Data Exchange (ETDEWEB)

    Orlhac, X

    2000-07-01

    The thermal stability of the French nuclear waste glass was investigated experimentally and by modeling to predict its long-term evolution at low temperature. The crystallization mechanisms were analyzed by studying devitrification in the supercooled liquid. Three main crystalline phases were characterized (CaMoO{sub 4}, CeCO{sub 2}, ZnCr{sub 2}O{sub 4}). Their crystallisation was TO 4.24 wt%, due to the low concentration of the constituent elements. The nucleation and growth curves showed that platinoid elements catalysed nucleation but did not affect growth, which was governed by volume diffusion. The criteria of classic nucleation theory were applied to determine the thermodynamic and diffusional activation energies. Viscosity measurements illustrate the analogy between the activation energy of viscous flow and diffusion, indicating control of crystallization by viscous flow phenomena. The combined action of nucleation and growth was assessed by TTT plots, revealing a crystallization equilibrium line that enables the crystallized fractions to be predicted over the long term. The authors show that hetero-genetics catalyze the transformation without modifying the maximum crystallized fraction. A kinetic model was developed to describe devitrification in the glass based on the nucleation and growth curves alone. The authors show that the low-temperature growth exhibits scale behavior (between time and temperature) similar to thermo-rheological simplicity. The analogy between the resulting activation energy and that of the viscosity was used to model growth on the basis of viscosity. After validation with a simplified (BaO{sub 2}SiO{sub 2}) glass, the model was applied to the containment glass. The result indicated that the glass remained completely vitreous after a cooling scenario with the one measured at the glass core. Under isothermal conditions, several million years would be required to reach the maximum theoretical crystallization fraction. (author)

  8. Etude structurale et propriétés des verres peralumineux de conditionnement des produits de fission et actinides mineurs"

    OpenAIRE

    Gasnier , Estelle

    2013-01-01

    In this work, peraluminous glasses (lack of alkaline and alkaline earth ions regarding aluminum) are under study to assess the potentiality of these matrices to confine fission products and minor actinides (FPA) at higher rate than current R7T7 glass (18,5 wt % FPA). The first part of this work aims at studying the physical and chemical properties of complex peraluminous glasses containing increasing FPA rate (18.5 to 32 wt %) to compare them with the specifications. The very low crystallizat...

  9. 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 : the rapid extraction of the soluble species and the reconstruction of the passivating altered layer. (author)

  10. 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 : the rapid extraction of the soluble species and the reconstruction of the passivating altered layer. (author)

  11. Study of nuclear glasses alteration gel and synthesis of some model gels; Etude du gel d`alteration des verres nucleaires et synthese de gels modeles

    Energy Technology Data Exchange (ETDEWEB)

    Ricol, S

    1995-10-05

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

  12. Étude archéométrique du verre du Ve au XIIe siècle en Bourgogne et Franche-Comté

    OpenAIRE

    Pactat, Inès

    2013-01-01

    National audience; Depuis une quinzaine d'années, les recherches archéologiques sur le haut Moyen Âge se sont multipliées en Bourgogne et en Franche-Comté. Nos connaissances sur cette période ne se limitent plus seulement aux données fournies par les contextes funéraires. Plus d'une trentaine de sites d'habitat sont désormais répertoriés dans les deux régions. Le maillage des établissements religieux s'est également densifié avec la mise au jour de plusieurs églises paléochrétiennes et la mis...

  13. Platinoids and molybdenum in nuclear waste containment glasses: a structural study; Les platinoides et le molybdene dans des verres d'interet nucleaires: etude structurale

    Energy Technology Data Exchange (ETDEWEB)

    Le Grand, M. [CEA/VALRHO - site de Marcoule, Dept. de Recherche en Retraitement et en Vitrification (DRRV), 30 - Marcoule (France)]|[Paris-7 Univ., 75 (France)

    2000-07-01

    This work deals with the structure of borosilicate nuclear glasses and with some relationships between structure and macroscopic properties. Two types of elements which may disturb the industrial process - platinoids (Ru and Pd) and molybdenum - are central to this work. Platinoids induce weak modifications on the structure of the glass, causing a depolymerization of the glassy network, an increase of the {sup [3]}B/{sup [4]}B ratio and a modification of the medium range order around Si between 3.3 and 4.5 angstrom. The modifications of viscosity and density induced by platinoids in the glass are not due to the structural effect of the platinoids. The increase of viscosity is attributed to needle shaped RuO{sub 2}. It can be moderated by imposing reducing conditions during the elaboration of the glass. The slight difference between experimental and calculated densities is due to the increase of the volume percentage of bubbles in the glass with increasing platinoid content. Mo is either present in the glass as molybdic groupings, or mobilized in chemically complex molybdic crystalline phases. The chemical composition and mineralogy of these phases has been obtained using electronic microprobe data and XRD with Rietveld analysis. The distribution of the different elements between the crystalline phases and the glass is strongly influenced by the structural role of the various cations in the glass. The Mo present in the glass appears as MoO{sub 4} tetrahedra, independent of the borosilicate network. The formation of the crystalline phases can be explained by the existence of a precursor in which the MoO{sub 4} tetrahedra are concentrated in rich alkali and earth-alkali bearing areas of the glass. (author)

  14. Solubility of actinides and surrogates in nuclear glasses; Solubilite des actinides et de leurs simulants dans les verres nucleaires. Limites d'incorporation et comprehension des mecanismes

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Ch

    2003-07-01

    The nuclear wastes are currently incorporated in borosilicate glass matrices. The resulting glass must be perfectly homogeneous. The work discussed here is a study of actinide (thorium and plutonium) solubility in borosilicate glass, undertaken to assess the extent of actinide solubility in the glass and to understand the mechanisms controlling actinide solubilization. Glass specimens containing; actinide surrogates were used to prepare and optimize the fabrication of radioactive glass samples. These preliminary studies revealed that actinide Surrogates solubility in the glass was enhanced by controlling the processing temperature, the dissolution kinetic of the surrogate precursors, the glass composition and the oxidizing versus reducing conditions. The actinide solubility was investigated in the borosilicate glass. The evolution of thorium solubility in borosilicate glass was determined for temperatures ranging from 1200 deg C to 1400 deg C.Borosilicate glass specimens containing plutonium were fabricated. The experimental result showed that the plutonium solubility limit ranged from 1 to 2.5 wt% PuO{sub 2} at 1200 deg C. A structural approach based on the determination of the local structure around actinides and their surrogates by EXAFS spectroscopy was used to determine their structural role in the glass and the nature of their bonding with the vitreous network. This approach revealed a correlation between the length of these bonds and the solubility of the actinides and their surrogates. (author)

  15. Platinoids and molybdenum in nuclear waste containment glasses: a structural study; Les platinoides et le molybdene dans des verres d'interet nucleaires: etude structurale

    Energy Technology Data Exchange (ETDEWEB)

    Le Grand, M [CEA/VALRHO - site de Marcoule, Dept. de Recherche en Retraitement et en Vitrification (DRRV), 30 - Marcoule (France); [Paris-7 Univ., 75 (France)

    2000-07-01

    This work deals with the structure of borosilicate nuclear glasses and with some relationships between structure and macroscopic properties. Two types of elements which may disturb the industrial process - platinoids (Ru and Pd) and molybdenum - are central to this work. Platinoids induce weak modifications on the structure of the glass, causing a depolymerization of the glassy network, an increase of the {sup [3]}B/{sup [4]}B ratio and a modification of the medium range order around Si between 3.3 and 4.5 angstrom. The modifications of viscosity and density induced by platinoids in the glass are not due to the structural effect of the platinoids. The increase of viscosity is attributed to needle shaped RuO{sub 2}. It can be moderated by imposing reducing conditions during the elaboration of the glass. The slight difference between experimental and calculated densities is due to the increase of the volume percentage of bubbles in the glass with increasing platinoid content. Mo is either present in the glass as molybdic groupings, or mobilized in chemically complex molybdic crystalline phases. The chemical composition and mineralogy of these phases has been obtained using electronic microprobe data and XRD with Rietveld analysis. The distribution of the different elements between the crystalline phases and the glass is strongly influenced by the structural role of the various cations in the glass. The Mo present in the glass appears as MoO{sub 4} tetrahedra, independent of the borosilicate network. The formation of the crystalline phases can be explained by the existence of a precursor in which the MoO{sub 4} tetrahedra are concentrated in rich alkali and earth-alkali bearing areas of the glass. (author)

  16. Thermo-chemistry of nuclear waste glasses: a new approach; Thermochimie des verres de stockage de dechets nucleaires: une nouvelle approche

    Energy Technology Data Exchange (ETDEWEB)

    Linard, Y.; Neuville, D.R.; Richet, P. [Institut de Physique du Globe, Lab. de Physique des Geomateriaux, URA CNRS 734, 75 - Paris (France)

    1997-07-01

    Understanding of the stability and weathering of glasses used for storing fission products is hampered by a general lack of basic thermochemical information. Models have been setup to predict Gibbs free energies of dissolution of glasses, but ascertaining their accuracy is made difficult by the very lack of reliable experimental data with which model results should be compared. As enthalpies of formation can in principle be determined from usual solution calorimetry experiments, the lack of Gibbs-free energy data for glasses mainly stems from the fact that, as disordered substances, glasses do not obey the third principle and have indeed large configurational entropies. These entropies can be determined from thermochemical measurements only when there exist a congruently melting crystalline compound with the same composition. Using available data, we have calculated the Gibbs-free energies of formation of a series of silicate glasses for which such a calorimetric determination is possible. With these results, we assess the predictions of Paul's model (1977) for calculating Gibbs-free energies of dissolution. As the complex compositions of the borosilicate glasses used for nuclear waste storage prevent determining configurational entropies by calorimetric methods, we point out how these can be determined instead from viscosity measurements. We finally discuss the implications of this approach for modeling of water-glass interactions. (authors)

  17. Synthesis on the durability of composite fiberglass/epoxy resin structures; Synthese sur la durabilite des structures composites en fibres de verre/resine epoxide

    Energy Technology Data Exchange (ETDEWEB)

    Thevenin, P [Electricite de France (EDF), Direction des Etudes et Recherches, 92 - Clamart (France)

    1998-12-31

    The purpose of this paper is to collect together in a systematic way information and results relating to the durability of composite fiberglass/ epoxy resin structures. First it is a matter of assessing the average level of understanding the long term behaviour of these structures which change under the combined effects of varied mechanical loading and stresses of a physico-chemical type linked to the environment. Looking at phenomena encountered and facts from current analyses, it will then be advisable to specify a methodology which can be applied to industrial piping used in PWR cooling systems for transporting raw water under pressure. In fact assessment of their service life is at present based on long and costly testing (ASTM D 2992 B standard), the appearance of which is inherited from metal piping testing.. Therefore it appears essential to study substitution test procedures, more composite specific and at the same time which can be conducted in reasonable time. For this purpose, by coherently accelerating and combining them in order not to underestimate their effects, ageing tests shall reproduce mechanisms representative of operating conditions. (author). 113 refs.

  18. Souffleurs de verre, mémoires intimes « au travail »  Glassblowers, private memories « at work »

    Directory of Open Access Journals (Sweden)

    Marie-Ange Lasmènes

    2011-12-01

    Full Text Available Le recueil de mémoires réalisé à l’occasion d’une enquête ethnographique auprès de verriers montre l’intérêt d’observer le changement au sein d’une entreprise porteuse de projets à la fois artistiques, sociaux et politiques. Après avoir montré l’intérêt pour l’ethnologue d’étudier la mémoire dans une perspective diachronique et le jeu de temporalité qui s’en dégage, il s’agira d’exposer en quoi la patrimonialisation des métiers relatifs à l’artisanat d’art ouvre vers une nouvelle catégorie patrimoniale à la croisée entre des politiques nationales et le développement d’un sentiment identitaire local autour de ce secteur d’activité exprimé par des discours officiels comme par un ensemble de mémoires individuelles. Enfin, sans rechercher à retracer une vérité historique du passé, il s’agira de présenter certains éléments de mémoires intimes autour du travail en entreprise rendus tacites par le changement de contexte entrepreneurial et la réappropriation d’une mémoire « officielle ».Glassblowers’ collect of memories realized during an ethnographic investigation shows the interest to observe how a firm holding artistic, social and politic projects can change. After have shown the interest for the ethnologist to study memory in a diachronical way dealing with its temporality, it will be exposed how patrimonialisation of handcrafts offers a new category of heritage localized between national politics and the expansion of a local feeling of identity linked to this corporation expressed by official talks and individual memories. Finally, far from a search of a historical truth of past, some elements of private memories at work, in a glass firm, hidden by the change of an entrepreneurial context and the assimilation of an official memory, will be presented.

  19. Modeling of an electric arc transferred on a melted glass bath; Modelisation d`un arc electrique transfere sur un bain de verre

    Energy Technology Data Exchange (ETDEWEB)

    Mehlman, G.; Langlois, A. [SGN, 78 - Saint Quentin en Yvelines (France)

    1997-12-31

    The aim of this study is to propose a methodology allowing the simulation of melting processes involving electromagnetic phenomena. This methodology is based on the use of scientific calculation tools currently used elsewhere. The case considered in this study has been defined in collaboration with Electricite de France (EdF) and concerns more particularly an electric arc vitrification process for wastes. Basic data have been determined in order to obtain results representative of the tests performed by EdF with pilot installations. (J.S.)

  20. Comparative evaluation of glasses reprocessing and reversible conditioning of calcinates; Evaluation comparative de la reprise des verres et du conditionnement reversible des calcinats

    Energy Technology Data Exchange (ETDEWEB)

    Boen, R

    2000-01-15

    Fission products and minor actinides separated during the spent fuel reprocessing treatment are industrially vitrified on-line and thus confined inside a glass matrix with admittedly durability properties. In the framework of the feasibility of a reversible conditioning, this document examines first the possible alternative ways of conditioning and storage of calcinates before vitrification, which may simplify the reversibility aspect. Such a conditioning must be compatible with the storage process, with a possible extraction of actinides and long-lived fission products, and with the vitrification process if no extraction is performed. Calcinates are pulverulent and comprise an important soluble fraction, a proportion of nitrates of about 30%, and release a high thermal power (17 kW/m{sup 3}) combined to a low thermal conductivity (0.1 to 0.15 W.m{sup -1} k{sup -1}). Among the different foreseeable solutions (denitration, mixing with another material, with or without compacting, dissolution inside another material..), the dissolution inside a borate seems to be the most acceptable with respect to the safety, feasibility and vitrification aspects. The thermal aspect of the storage remains complex as a specific container is necessary. In a second part, this report analyzes the possibility to re-extract back the long-lived radionuclides from vitrified wastes. The different possible ways to destroy the glass structure and to transfer the fission products and minor actinides in an aqueous solution compatible with an hydrometallurgical separation process are explored. Two processes are foreseeable: a low temperature dissolution process which requires a preliminary crushing and the handling of huge amounts of acids, and a both high and low temperature process which comprises the following steps: melting, fractionation by water tempering, addition of Na{sub 2}O or sodium tetraborate to make it sensible to hot leaching, separation of fission products and minor actinides, recycling of reagents, and vitrification of secondary wastes. This last process is the most feasible as it is accessible to existing technologies but its industrialization would require important developments. (J.S.)

  1. 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 : the rapid extraction of the soluble species and the reconstruction of the passivating altered layer. (author)

  2. 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 : the rapid extraction of the soluble species and the reconstruction of the passivating altered layer. (author)

  3. Spectroscopies et modélisation de verres de silice dopés d'ions de terre rare - influence du co-dopage

    OpenAIRE

    Alombert-Goget , Guillaume

    2007-01-01

    This study concerns the role of a co-doping agent on the environment of the rare earth ions in silica glass and its consequences on the spectroscopy of the luminescent element. Two different co-doping agents were studied: aluminium and hafnium ions. The samples of doped and co-doped glasses were obtained by sol-gel process and were studied by different experimental methods: luminescence spectroscopy, FLN spectroscopy, Raman spectroscopy, and EXAFS spectroscopy. In parallel some numerical simu...

  4. Effect of the kind of alkaline and rare earth ions on the structure of a glass rich in earth; Effet de la nature des ions alcalins et alcalino-terreux sur la structure d un verre riche en terre

    Energy Technology Data Exchange (ETDEWEB)

    Quintas, Arnaud; Caurant, Daniel; Majerus, Odile [Laboratoire de Chimie Appliquee de l Etat Solide, UMR 7574, ENSCP, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05, (France); Lenoir, Marion; Dussossoy, Jean-Luc [Commissariat a l Energie Atomique, Centre d Etudes de la Vallee du Rhone, DIEC/SCDV/LEBM, 30207 Bagnols-sur-Ceze, (France); Charpentier, Thibault [Service de Chimie Moleculaire, DSM/DRECAM/CEA Saclay, 91191 Gif-sur-Yvette Cedex, (France); Neuville, Daniel R. [Laboratoire de Physique des Mineraux et des Magmas, UMR 7047-CNRS-IPGP, Universite Pierre et Marie Curie, 4 place Jussieu, 75252 Paris Cedex 05, (France); Gervais, C. [Laboratoire de Chimie de la matiere condensee, UMR7574, Universite Pierre et Marie Curie, 4 place Jussieu, F-75252 Paris Cedex 05, (France)

    2006-07-01

    In the framework of a structural study of a nuclear wastes containment glass of type alumino borosilicate and rich in rare earths, the influence of the kind of alkaline or rare earth ions is analyzed. For that, two glasses series have been prepared in which the Na{sup +} ion (respectively Ca{sup 2+} ions) present in the standard composition is totally substituted by another alkaline ion Li{sup +}, K{sup +}, Rb{sup +} or Cs{sup +} (respectively another rare earth ion Mg{sup 2+}, Sr{sup 2+} or Ba{sup 2+}). These glasses, analyzed by optical absorption, Raman and {sup 27}Al or {sup 11}B NMR spectroscopies have revealed the strong impact of the kind of the modifying ion as well as the structure of the vitreous lattice (variation of the ratio BO{sub 3}/BO{sub 4} and local variations of the polymerization degree) than the local surroundings of the rare earth (decrease of the covalency degree of the bond Nd-O with the increase of the field force of the modifying ion). (O.M.)

  5. Sulphate solubility and sulphate diffusion in oxide glasses: implications for the containment of sulphate-bearing nuclear wastes; Solubilite et cinetiques de diffusion des sulfates dans differents verres d'oxydes: application au conditionnement des dechets nucleaires sulfates

    Energy Technology Data Exchange (ETDEWEB)

    Lenoir, M.

    2009-09-15

    The thesis deals with sulphate solubility and sulphate diffusion in oxide glasses, in order to control sulphate incorporation and sulphate volatilization in nuclear waste glasses. It was conducted on simplified compositions, in the SiO{sub 2}-B{sub 2}O{sub 3}-R{sub 2}O (R = Li, Na, K, Cs), SiO{sub 2}-B{sub 2}O{sub 3}-BaO and V{sub 2}O{sub 5}-B{sub 2}O{sub 3}-BaO systems. These compositions allowed us to study the influence of the nature of network-modifying ions (Li{sup +}, Na{sup +}, K{sup +}, Cs{sup +} or Ba{sup 2+}) and also of former elements (Si, B, V), on structure and properties of glasses. Sulphate volatility is studied in sodium borosilicate melts using an innovative technique of sulphate quantitation with Raman spectroscopy. This technique is useful to obtain kinetic curves of sulphate volatilization. The establishment of a model to fit these curves leads to the determination of diffusion coefficients of sulphate. These diffusion coefficients can thus be compared to diffusion coefficients of other species, determined by other techniques and presented in the literature. They are also linked to diffusion coefficients in relation with the viscosity of the melts. Concerning sulphate solubility in glasses, it depends on glass composition and on the nature of sulphate incorporated. Sulphate incorporation in alkali borosilicate glasses leads to the formation of a sulphate layer floating on top of the melt. Sulphate incorporation in barium borosilicate and boro-vanadate glasses leads to the crystallization of sulphate species inside the vitreous matrix. Moreover, sulphate solubility is higher in these glasses than in alkali borosilicates. Finally, exchanges between cations present in glasses and cations present in the sulphate phase are also studied. (author)

  6. 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)

  7. Ion beam assisted synthesis of nano-crystals in glasses (silver and lead chalcogenides); Synthese assistee par faisceau d'ions d'agregats dans les verres (argent et chalcogenures de plomb)

    Energy Technology Data Exchange (ETDEWEB)

    Espiau de Lamaestre, R

    2005-04-15

    This work deals with the interest in ion beams for controlling nano-crystals synthesis in glasses. We show two different ways to reach this aim, insisting on importance of redox phenomena induced by the penetration and implantation of ions in glasses. We first show that we can use the great energy density deposited by the ions to tailor reducing conditions, favorable to metallic nano-crystal precipitation. In particular, we show that microscopic mechanism of radiation induced silver precipitation in glasses are analogous to the ones of classical photography. Ion beams can also be used to overcome supersaturation of elements in a given matrix. In this work, we synthesized lead chalcogenide nano-crystals (PbS, PbSe, PbTe) whose optical properties are interesting for telecommunication applications. We demonstrate the influence of complex chalcogenide chemistry in oxide glasses, and its relationship with the observed loss of growth control when nano-crystals are synthesized by sequential implantation of Pb and S in pure silica. As a consequence of this understanding, we demonstrate a novel and controlled synthesis of PbS nano-crystals, consisting in implanting sulfur into a Pb-containing glass, before annealing. Choice of glass composition provides a better control of precipitation physico-chemistry, whereas the use of implantation allows high nano-crystal volume fractions to be reached. Our study of IR emission properties of these nano-crystals shows a very high excitation cross section, and evidence for a 'dark exciton' emitting level. (author)

  8. Effect of the impact directions, of the fibers and of the aging on the glass fibers composite resistance; Effet des directions de l'impact, des fibres et du vieillissement sur la resistance du composite en fibres de verre

    Energy Technology Data Exchange (ETDEWEB)

    Vina, J.; Arguelles, A. [Oviedo Univ. (Spain); Zenasni, R.; Ouinas, D. [Universite de Mostaganem (Algeria)

    2006-07-01

    Usually, composites of epoxy matrix reinforced with glass fiber are used in the fabrication of wind turbine blades. This material has an anisotropic structure and its mechanical properties are not the same in all the directions. The impact strength was evaluated from the mechanical tests carried out in two perpendicular directions. The effect of aging was analyzed immersing the specimens into water to 70 C, during different periods of time. From the results of the tests, the dynamic fracture toughness (Kid) and the resilience (KCV) were obtained. An important difference was obtained between the specimens taken out in the blade direction and in the perpendicular direction. The aging specimens, in the two directions, have showed continuous decrements in the dynamic toughness and resilience, from the first period of immersion of 15 days until 180 days. (authors)

  9. Volatility mechanisms of borosilicate glasses and molten glasses of nuclear interest structural effects; Mecanismes de volatilite des verres et des fontes borosilicates d'interet nucleaire influence de la structure

    Energy Technology Data Exchange (ETDEWEB)

    Delorme, L

    1998-04-23

    This work is devoted to the study of the mechanisms which control the volatility of the reference glass used for the confinement of radioactive waste. It was conducted on simplified compositions, in the SiO{sub 2}-B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-{alpha}Na{sub 2}O-(1-alpha)Li{sub 2}O-CaO system.The structural approach carried out by NMR, from room temperature up to 1500 deg.C, shows a strong increase in the mobility of alkalis above Tg. A rapid exchange between B{sup III} and B{sup IV} sites near 700 deg.C, and the change of coordination number B{sup IV-} B{sup III} near 1100 deg.C, also seem to take place. The analysis of the vapor phase, carried out by High Temperature Mass Spectrometry coupled to Knudsen cells, reveals the presence between 780 deg.C and 830 deg.C of NaBO{sub 2}(g), LiBO{sub 2}(g) and Na{sub 2}(BO{sub 2})2(g). The calculation of the partial pressure of each species shows that the total pressure of simplified glasses is dominated by the contribution of sodium. To study the volatility of glasses at higher temperature, equipment using the Transpiration method was used. The analysis of the deposits indicate the presence at 1060 deg.C of the species quoted previously. The vaporization rate and the vapor density were determined for each composition studied in a saturated state. Thus, we show that the volatility of the reference glass can be simulated by that of a simplified glass. For {alpha}=1, the kinetic of vaporization between 1060 deg.C and 1200 deg.C reveals an evaporation from the surface associated with a mechanism of diffusion in the molten glass. This is similar to the volatility of the reference glass at 1060 deg.C. To finally explain these mechanisms on a microscopic basis, we develop a model of molecular interactions. Between 780 deg.C and 830 deg.C, these mechanisms are controlled by a strong attraction between Na{sub 2}O and Li{sub 2}O, which maintains the total vapor pressure on a quasi-constant lever up to {alpha}=0.27. (author)

  10. Modelling the fatigue behaviour of a stratified glass-epoxy composite: theoretical and experimental aspects; Modelisation du comportement en fatigue d`un composite stratifie verre-epoxyde: aspects theoriques et experimentaux

    Energy Technology Data Exchange (ETDEWEB)

    Verdiere, N.; Suri, C. [Laboratoire de mecanique appliquee, 25 - Besancon (France)

    1996-01-01

    Composite materials are used in the manufacture of water transport pipework for use in PWR`s. Estimation of their life expectancy relies on long and costly tests (ASTM D2992B standard). It would be extremely advantageous to have another method relying only on short laboratory tests which could be based on a mechanical behaviour and damage model. For several years, the Laboratoire de Mecanique Appliquee de Besancon has been developing a mechanical behaviour model for composite material tubes for different types of multiaxial stresses. However, this model does not take into account the fatigue behaviour. We therefore needed to find out how this type of stress could be incorporated into the model. To this end, research was undertaken in the form of a thesis (by E. Joseph) both to perfect the multiaxial fatigue stress testing machines and to take into account this type of behaviour in the mechanical model. This study covered glass fibre/epoxy resin composite material tubes and allowed their behaviour to be modelled. An important part of the work concerned the instrumentation and adaptation of test machines which hitherto did not exist so that the research could be carried out. For each of the stress axes (traction, internal pressure without vacuum effect ({Sigma}{sup zz}=0) and internal pressure with vacuum effect ({Sigma}{sup zz}=1/2{Sigma}{sup {theta}{theta}})), instantaneous behaviour was studied. Three stress levels and frequency values were used to define the fatigue behaviour. (authors). 23 refs., 41 figs., 5 tabs.

  11. Study of the performances of acoustic emission testing for glass fibre reinforced plastic pipes containing defects; Etude des performances du controle par emission acoustique de tubes en materiaux composites resine-fibre de verre contenant des defauts

    Energy Technology Data Exchange (ETDEWEB)

    Villard, D.; Vidal, M.C.

    1995-08-01

    Glass fibre reinforced plastic pipes are more and more often used, in nuclear power plants, for building or replacement of water pipings classified `nuclear safety`. Tests have been performed to evaluate the performances of acoustic emission testing for in service inspection of these components. The tests were focused on glass fibre reinforced polyester and vinyl-ester pipes, in as received conditions or containing impacts, and intentionally introduced defects. They have been carried out by CETIM, following the ASTM Standard E 1118 (code CARP), to a maximum pressure lever of 25 Bar The results show that the CARP procedure can be used for detection of defects and evaluation of their noxiousness towards internal pressure: most of the tubes containing low energy impacts could not be distinguished from tubes without defect; on the other hand the important noxiousness of lacks of impregnation of roving layer appeared clearly. Complementary tests have been performed on some tubes at a more important pressure lever, for which the damage of the tubes in enough to deteriorate there elastic properties. The results showed that CARP procedure give valuable informations on damage level. It would be interesting to evaluate acoustic emission on tubes containing realistic in-service degradations. (author). 11 refs., 15 figs., 6 tabs., 2 appends.

  12. Experimental investigation of the effects of aqueous species on the dissolution kinetics of R7T7 glass; Etude experimentale de l`influence d`especes aqueuses sur la cinetique de dissolution du verre nucleaire R7T7

    Energy Technology Data Exchange (ETDEWEB)

    Gin, S

    1994-10-01

    This contribution to the study of aqueous corrosion of the French ``R7T7`` reference nuclear containment glass includes a bibliographic survey of prior investigations, highlighting the problems encountered in interpreting the interactions in systems containing clay materials in contact with the glass. An experimental methodology is proposed to investigate the effects of inorganic aqueous species separately from those of a few organic acids on the dissolution mechanisms and kinetics of R7T7 glass at 90 deg. C. The experimental results discussed support the idea that several glass network forming elements may have a kinetically limiting role. The most likely hypothesis to account for the absence of saturation conditions with respect to the glass in certain clay media involves the formation of complexes with kinetically limiting metallic elements such as aluminum released by glass corrosion. This work contributes to a better understanding of the basic mechanisms of nuclear glass dissolution in a geological repository environment. It facilitates the interpretation of glass alteration studies in realistic or actual solutions and may contribute to specifying near field chemical barriers in the form of additives (amorphous silica, aluminum hydroxides or phosphates) around the glass disposal package to enhance the stability of the glass matrix. (author). 148 refs., 40 figs., 32 tabs., 1 append.

  13. Contribution to the study of the effects of {alpha}-irradiation in nuclear glasses; Contribution a l'etude des effets de l'irradiation {alpha} sur les verres nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, A

    2001-07-01

    The main topic of this work is to characterise the effects of {alpha}-disintegration in nuclear waste glasses. Experimental and numerical approaches have been considered. The structure of the French nuclear waste glass (R7T7) has been simulated using four- and six-oxides simplified glasses which contain the main elements of the R7T7 glass: SiO{sub 2}, B{sub 2}O{sub 3}, Na{sub 2}O, ZrO{sub 2}, Al{sub 2}O{sub 3} and CaO. Four- and six-oxides glasses have been irradiated with 1 MeV-He{sup +} (ionisation) and 2.1 MeV-Kr{sup 3+} (ionisation and atomic collisions) ions in order to reproduce the effects of the {alpha}-particle and of the recoil nucleus emitted during {alpha}-disintegration of actinides, and also to differentiate electronic and ballistic effects. Irradiated glasses have been characterised using several techniques, which have been adapted to the peculiarities of our samples (isolated material, small irradiated depth). The results point out the salient role of sodium in the observed modifications: depth concentration profiles obtained with RBS show an accumulation of sodium at the irradiated surface. We found a apparent acceleration of sodium release in leaching experiments which confirm that point. Modifications observed in Raman spectra of irradiated glasses show an increase of the polymerisation (increase of Q{sub 3}/Q{sub 2} ratio) due to sodium migration. In simplified glasses we have found that the modifications of mechanical properties by external irradiations reproduce the modifications observed in actinide doped nuclear glass (decrease of hardness and increase of fracture toughness). At the same time, we performed Molecular Dynamics simulations of a six-oxides glass. We have shown that the surface modifies the glass structure down to a depth of 10 Angstrom: modification of depth concentration profiles, decrease of the atomic coordination number (A1, B and Si). During cascades, we found that atomic displacements are easier near the surface. This behaviour is also observed when the glass is submitted to an external electric field. In the energy range used, the efficiency of the glassy structure rebuilding seems to be unaffected by the surface. (author)

  14. Smoke filtration in the glass industry. Thomson Videoglass` global approach with closed loop recycling; Fitration des fumees dans l`industrie du verre. L`approche globale avec recyclage en boucle fermee de thomson videoglass

    Energy Technology Data Exchange (ETDEWEB)

    Mocek, L. [Thomson Videoglass, 77 - Bagneaux-sur-Loing (France)

    1996-12-31

    Thomson Videoglass, an ISO 9002 certified manufacturer of glass components for Tv sets in France, has introduced a global closed-loop recycling dust filtration system for glass kilns; electrostatic filters and bag filters (for the lead-containing flat glass kiln) have been selected and collected dusts are recycled in the cone glass kiln. Energy savings, operating conditions, investment and operating costs are discussed together with filter corrosion, clogging-up and service life issues and dust extraction performances

  15. 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)

  16. Numerical modelling of coupled phenomena within molten glass heated by induction and mechanically stirred; Modelisation numerique de phenomenes couples dans des bains de verre brasses mecaniquement et elabores en creuset froid inductif

    Energy Technology Data Exchange (ETDEWEB)

    Jacoutot, L

    2006-11-15

    This study reports on a new vitrification process developed by the French Atomic Energy Commission (CEA, Marcoule). This process is used for the treatment of high activity nuclear waste. It is characterized by the cooling of all the metal walls and by currents directly induced inside the molten glass. In addition, a mechanical stirring device is used to homogenize the molten glass. The goal of this study is to develop numerical tools to understand phenomena which take place within the bath and which involve thermal, hydrodynamic and electromagnetic aspects. The numerical studies are validated using experimental results obtained from pilot vitrification facilities. (author)

  17. The use of natural and archaeological analogues for understanding the long-term behavior of nuclear glasses; L'utilisation des analogues naturels et archeologiques pour la comprehension de l'evolution a long terme des verres nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Libourel, G.; Verney-Carron, A.; Morlok, A. [CNRS UPR2300, centre de recherches petrographiques et geochimiques (CRPG), Nancy-universite, 15, rue Notre-Dame-des-Pauvres, BP 20, 54501 Vandoeuvre-les-Nancy (France); Libourel, G. [INPL, Ecole nationale superieure de geologie (ENSG), Nancy-universite, rue du Doyen-Marcel-Roubault, BP 20, 54501 Vandoeuvre-les-Nancy (France); Gin, St. [CEA Marcoule, DEN/SECM/LCLT, 30 (France); Sterpenich, J. [G2R, CNRS-UMR 7566, Nancy-universite, BP 70239, 54506 Vandoeuvre-les-Nancy cedex (France); Michelin, A.; Neff, D.; Dillmann, Ph. [Laboratoire archeomateriaux et prevision de l' alteration LAPA/SIS2 M, CEA and CNRS, Bat 637, CEA Saclay, 91191 Gif/Yvette cedex (France); Michelin, A.; Dillmann, Ph. [LMC IRAMAT UMR5060 CNRS (France)

    2011-02-15

    The knowledge of the long-term behavior of nuclear waste in anticipation of ultimate disposal in a deep geological formation is of prime importance in a waste management strategy. If phenomenological models have been developed to predict the long-term behavior of these materials, validating these models remains a challenge, when considering the time scale of radioactive decay of radionuclides of environmental concern, typically 10{sup 4}-10{sup 5} yrs. Here we show how natural or archaeological analogues provide critical constraints not only on the phenomenology of glass alteration and the mechanisms involved, but also on the ability of experimental short-term data to predict long-term alteration in complex environments. (authors)

  18. Importance of space-time fluctuations and non-linearities for the transport inside insulating glasses; Importance des fluctuations spatio-temporelles et des non linearites pour le transport dans les verres isolants

    Energy Technology Data Exchange (ETDEWEB)

    Ladieu, F

    2003-07-01

    This work deals with transport in insulating glasses. In such solids, the discrete translational symmetry is lost, which means that the plane wave analysis is not a priori the right 'starting point'. As a result, the transport is more difficult to handle, and a huge amount of works have been devoted to many aspects of transport in disordered systems, especially since the seventies. Here we focus on three specific questions: (i) the heat transport in glasses submitted to micro-beams and the associated irreversible vaporization; (ii) the electronic d.c. transport, below 1 Kelvin, in Mott-Anderson insulators, i.e. in 'electron glasses' where both disorder and electron-electron interactions are relevant; (iii) the low frequency dielectric constant in 'structural glasses' (i.e. 'ordinary glasses') which, below 1 Kelvin, is both universal (i.e. independent on the chemical composition) and very different of that of crystals. For each topic, we present both original experiments and the new theoretical concepts that we have elaborated so as to understand the main experimental features. Eventually, it appears that, in any case, transport in insulating glasses is strongly dominated by quite a small part of the 'glass-applied field' ensemble and that the nonlinear response is a relevant tool to get informations on this 'sub-part' which dominates the transport in the whole system. (author)

  19. Volatility mechanisms of borosilicate glasses and molten glasses of nuclear interest structural effects; Mecanismes de volatilite des verres et des fontes borosilicates d'interet nucleaire influence de la structure

    Energy Technology Data Exchange (ETDEWEB)

    Delorme, L

    1998-04-23

    This work is devoted to the study of the mechanisms which control the volatility of the reference glass used for the confinement of radioactive waste. It was conducted on simplified compositions, in the SiO{sub 2}-B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-{alpha}Na{sub 2}O-(1-alpha)Li{sub 2}O-CaO system.The structural approach carried out by NMR, from room temperature up to 1500 deg.C, shows a strong increase in the mobility of alkalis above Tg. A rapid exchange between B{sup III} and B{sup IV} sites near 700 deg.C, and the change of coordination number B{sup IV-} B{sup III} near 1100 deg.C, also seem to take place. The analysis of the vapor phase, carried out by High Temperature Mass Spectrometry coupled to Knudsen cells, reveals the presence between 780 deg.C and 830 deg.C of NaBO{sub 2}(g), LiBO{sub 2}(g) and Na{sub 2}(BO{sub 2})2(g). The calculation of the partial pressure of each species shows that the total pressure of simplified glasses is dominated by the contribution of sodium. To study the volatility of glasses at higher temperature, equipment using the Transpiration method was used. The analysis of the deposits indicate the presence at 1060 deg.C of the species quoted previously. The vaporization rate and the vapor density were determined for each composition studied in a saturated state. Thus, we show that the volatility of the reference glass can be simulated by that of a simplified glass. For {alpha}=1, the kinetic of vaporization between 1060 deg.C and 1200 deg.C reveals an evaporation from the surface associated with a mechanism of diffusion in the molten glass. This is similar to the volatility of the reference glass at 1060 deg.C. To finally explain these mechanisms on a microscopic basis, we develop a model of molecular interactions. Between 780 deg.C and 830 deg.C, these mechanisms are controlled by a strong attraction between Na{sub 2}O and Li{sub 2}O, which maintains the total vapor pressure on a quasi-constant lever up to {alpha}=0.27. (author)

  20. Self-defects and self diffusion in a silica glass: a first-principles study; Etude ab-initio des auto-defauts et des mecanismes d'auto-diffusion dans un verre de silice

    Energy Technology Data Exchange (ETDEWEB)

    Martin, L.; Colomer, S

    2004-11-15

    SiO{sub 2} and silica based compounds are key materials in a variety of scientific and technological fields as, for instance, in microelectronics or nuclear technology. In all these fields, one of the still open questions is their long term aging in a radioactive environment. Due to the complexity of the effects of radiations upon matter, the understanding of the long term aging needs the knowledge of diffusion mechanisms at the atomic scale. In that context, numerical modelling appears as a way to access this scale. We present a first principles study on self-defects and self-diffusion in a silica model. As expected, at variance with SiO{sub 2} crystalline phases, the defects formation energies are distributed, due to the non-equivalence of defects sites. We prove that the formation energy dispersion is correlated to the local stress. Concerning the equilibrium concentrations and oxygen diffusion mechanism, we discuss how the shape of the distribution, as well as impurity levels within the gap, play a main role in the dominance of defect types. Finally we present the main oxygen diffusion mechanism in homogeneous and heterogeneous defect formation regime. (author)

  1. Structure and properties of rare earth-rich glassed for nuclear waste immobilisation; Etude des caracteristiques structurales et des proprietes de verres riches en terres rares destines au confinement des produits de fission et elements a vie longue

    Energy Technology Data Exchange (ETDEWEB)

    Bardez, I

    2004-11-15

    A new nuclear glass composition, able to immobilize highly radioactive liquid wastes from high burn-up UO{sub 2} fuel, was established and its structure studied. The composition of the selected rare earth-rich glass is (molar %): 61.79 SiO{sub 2} - 8.94 B{sub 2}O{sub 3} - 3.05 Al{sub 2}O{sub 3} - 14.41 Na{sub 2}O - 6.32 CaO - 1.89 ZrO{sub 2} - 3.60 RE{sub 2}O{sub 3} (with RE = La, Ce, Pr and Nd). The aim of this study was to determine the local environment of the rare earth in this glass and also to glean information about the effect of glass composition on the rare earth neighbouring (influence of Si, B, Al, Na and Ca contents). To this end, several series of glasses, prepared from the baseline glass, were studied by different characterisation methods such as EXAFS spectroscopy at the neodymium LIII-edge, optical absorption spectroscopy, Raman spectroscopy and {sup 29}Si, {sup 27}Al and {sup 11}B MAS-NMR. By coupling all the results obtained, several hypotheses about the nature of the rare earth neighbouring in the glass were proposed. (author)

  2. Doping influence by some transition elements on the irradiation effects in nuclear waste glasses; Influence du dopage par certains elements de transition sur les effets d'irradiation dans des verres d'interet nucleaire

    Energy Technology Data Exchange (ETDEWEB)

    Florent, Olivier

    2006-06-15

    High-level waste glasses are submitted to auto-irradiation. Modelling it using external irradiations on simple glasses revealed defects production and non negligible structural changes. This thesis aims at determining the impact of a more complex composition on these effects, especially the influence of adding polyvalent transition metals. Silicate, soda-lime and alumino-borosilicate glasses are doped with different iron, chromium and manganese concentrations then {beta} irradiated at different doses up to 10{sup 9} Gy. Non doped glasses show an increase of their density and polymerisation coupled with a molecular oxygen and point defects production. Adding 0.16 mol% Fe decreases the amount of defects by 85 % and all irradiation effects. A Fe{sup 3+} reduction is also observed by EPR, optical absorption and indirectly by Raman spectroscopy. A higher than 0.32 mol% Fe concentration causes complete blockage of the evolution of polymerisation, density and defect production. The same results are obtained on chromium or manganese doped glasses. An original in situ optical absorption device shows the quick decrease of Fe{sup 3+} amount to a 25 % lower level during irradiation. Stopping irradiation causes a lower decrease of 65 %, suggesting a dynamic (h{sup 0}/e-) consuming equilibrium. He{sup +} and Kr{sup 3+} ions and {gamma} irradiated glasses tend to confirm these phenomena for all kind of irradiation with electronic excitations. (author)

  3. Verres et vitrocéramiques fluorés dopés terre rare et/ou métal de transition pour la conversion de l'énergie solaire

    OpenAIRE

    Maalej , Olfa

    2015-01-01

    The efficiency of solar cells can be improved by fully exploiting the UV-blue portion of the solar spectrum, through a frequency converting mechanism of type downconversion. This process using energy transfer between rare earth ions (RE) or 3d transition metal (pairs RE3+/Yb3+ with TR = Pr, Tm,… and Cr3+/Yb3+) requires a matrix with low phonon energy to reduce non radiative relaxation.So far, the studied materials are mainly in the form of polycristalline powder, which limits their use due to...

  4. Etude des caractéristiques structurales et des propriétés de verres riches en terres rares destinés au confinement des produits de fission et éléments à vie longue

    OpenAIRE

    Bardez , Isabelle

    2004-01-01

    Une nouvelle matrice vitreuse riche en terres rares, capable d'incorporer les déchets issus du retraitement de combustibles nucléaires UOX à hauts taux de combustion (60 GWj/t, à comparer à 33 GWj/t pour le combustible de référence actuel) a été mise au point et étudiée au niveau structural. Sa composition molaire simplifiée est la suivante : 61 ,79 SiO2 - 8,94 B2O3 - 3,05 Al2O3 - 14,41 Na2O - 6,32 CaO - 1,89 ZrO2 - 3,60 TR2O3 (avec TR = La, Ce, Pr et Nd) En particulier, l'environnement local...

  5. Contribution and limits of geochemical calculation codes to evaluate the long term behavior of nuclear waste glasses; Apports et limites des modeles geochimiques pour l'evaluation du comportement a long terme des verres de confinement des dechets radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Fritz, B; Crovisier, J L [Universite Louis Pasteur, Centre de Geochimie de la Surface, CNRS ULP, Ecole et Observatoire des Sciences de la Terre, 67 - Strasbourg (France)

    1997-07-01

    Geochemical models have been intensively developed by researchers since more than twenty five years in order to be able to better understand and/or predict the long term stability/instability of water-rock systems. These geochemical codes were ail built first on a thermodynamic approach deriving from the application of Mass Action Law. The resulting first generation of models allowed to detect or predict the possible mass transfers (thermodynamic models) between aqueous and mineral phases including irreversible dissolutions of primary minerals and/or precipitation near equilibrium of secondary mineral phases. The recent development of models based on combined thermodynamics and kinetics opens the field of Lime dependent reactions prediction. This is crucial if one thinks to combine geochemical and hydrological studies in the so-called coupled models for transport and reaction calculations. All these models are progressively applied to the prediction of long term behavior of mineral phases, and more specifically glasses. In order to succeed in chat specific extension of the models, but also the data bases, there is a great need for additional new data from experimental approaches and from natural analogues. The modelling approach appears than also very useful in order to interpret the results of experimental data and to relate them to long term data extracted from natural analogues. Specific functions for modelling solid solution phases mat' also be used for describing the products of glasses alterations. (authors)

  6. Structure and aqueous reactivity of silicate glasses high-resolution nuclear magnetic resonance contribution; Structure et reactivite aqueuse des verres silicates apport de la resonance magnetique nucleaire haute-resolution

    Energy Technology Data Exchange (ETDEWEB)

    Angeli, F

    2000-10-25

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

  7. 2367-IJBCS-Article-Koffi Mathias Yao

    African Journals Online (AJOL)

    hp

    comportement serait lié au prix de vente des différents alcools. C'est pourquoi, la publicité ... troubles physiques et mentaux, parmi lesquels ... consommation de 5 verres chez l'homme ou ... consomme trois à quatre verres, au plus une fois par ...

  8. Chapitre IV. Aspects neuro-fonctionnels des systèmes mis en jeu dans les habiletés manuelles chez l’adulte

    OpenAIRE

    Fagard, Jacqueline

    2016-01-01

    À la base des habiletés les plus complexes se trouvent des mouvements simples, coordonnés entre eux. Tous les mouvements, même les plus simples comme le geste de tendre le bras pour prendre un verre, demandent la contraction simultanée de nombreux muscles. Certains muscles font partie de la motricité proximale - ceux qui sont responsables du geste d’avancer le bras vers le verre -, d’autres de la motricité distale - lors de la prise du verre avec les doigts -, d’autres encore font partie de l...

  9. Mobilization and Defense Management Technical Reports Series. The Use of Reactivation Networks to Improve Mobilization Preparedness of the Ammunition Industry

    Science.gov (United States)

    1983-05-01

    t~he other hand, VERr -3 has had less publicity and is not as well known as MRP. It is still developing, and in the current application is directly...effort, ARiCOM contracted with Day & Zimmermann, Inc., Kansas Division, Stetter Associates, Le Clair, Iowa to develop a standard networking system...wide variety of reictivation situations which lend themselves "to VERr -3 networking that can be added to the basic networks. The primary networks

  10. Micromechanisms of Crack Growth in Ceramics and Glasses in Corrosive Environments.

    Science.gov (United States)

    1980-05-01

    Resistance Mecanique du Verre et les Moyens de l’Amelioree, Union Scientifique Continentale du Verre , Charleroix, Belgium, (1962). 8. B. A. Proctor, I...exhibit similar types of delayed failure curves. Failure occurs most rapidly at high loads. Below a critical value of the load known as the stress...fracture for the three types of materials differ greatly. Polymers and metals have plastic zones at their crack tips, so that stress corrosion

  11. Der Sinn des Wahns : Der Mad Scientist und die unmögliche Wissenschaft

    OpenAIRE

    Keller, Felix

    2004-01-01

    Der Text untersucht die Herkunft des verrückten Wissenschaftlers, des Mad Scientist, so wie er in den populären Kultur zelebriert wird. Es wird die Auffassung vertreten, dass der Ursprung der Figur im romantischen Mythos des Genies liegt. Doch wie und weshalb ist es dann zu dieser seltsamen Mutation zum verrückten Wissenschaftler gekommen? Und was berichtet diese Figur über die Wahrnehmung von Wissenschaft?

  12. Structure study and properties of rare earth-rich glassed for the conditioning of nuclear waste; Etude des caracteristiques structurales et des proprietes de verres riches en terres rares destines au confinement des produits de fission et elements a vie longue

    Energy Technology Data Exchange (ETDEWEB)

    Bardez, I

    2004-11-15

    A new nuclear glass composition, able to immobilize highly radioactive liquid wastes from high burn-up UO{sub 2} fuel, was established and its structure studied. The composition of the selected rare earth-rich glass is (molar %): 61.79 SiO{sub 2} - 8.94 B{sub 2}O{sub 3} - 3.05 Al{sub 2}O{sub 3} - 14.41 Na{sub 2}O - 6.32 CaO - 1.89 ZrO{sub 2} - 3.60 RE{sub 2}O{sub 3} (with RE = La, Ce, Pr and Nd) The aim of this study was to determine the local environment of the rare earth in this glass and also to glean information about the effect of glass composition on the rare earth neighbouring (influence of Si, B, Al, Na and Ca contents). To this end, several series of glasses, prepared from the baseline glass, were studied by different characterisation methods such as EXAFS spectroscopy at the neodymium L{sub III}-edge, optical absorption spectroscopy, Raman spectroscopy and {sup 29}Si, {sup 27}Al and {sup 11}B MAS-NMR. By coupling all the results obtained, several hypotheses about the nature of the rare earth neighbouring in the glass were proposed. (author)

  13. Electrical conductivity of oxides from molten state to glassy. Effect on the incorporation of RuO{sub 2} particles; Conductivite electrique des verres et fontes d'oxides. Effets de l'incorporation de particules RuO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Simonnet, C

    2004-07-01

    This study concerns the electrical conductivity of oxides from molten state to glassy state and, in particular, the effect of the incorporation of RuO{sub 2} particles in the context of vitrification of radioactive waste. The material of interest in the nuclear field is basically a viscous or vitreous borosilicate containing a dispersion of RuO{sub 2} microcrystals. A very simple model of this heterogeneous material has been studied in particular (SiO{sub 2}, B{sub 2}O{sub 3}, Na{sub 2}O, RuO{sub 2}). An original method of impedance measurement in the liquid at high temperature yields reliable electrical conductivity values over a temperature range covering the liquid and vitreous phases of the borosilicates studied. In the borosilicate matrix, alkaline transport is mainly responsible for the ionic conduction. The temperature dependence of the conductivity may thus be represented by an equation combining a VFT law and an Arrhenius law to represent the electrical conductivity above and below T{sub g}. Beyond a critical volume fraction V{sub c} {approx} 0.01 of RuO{sub 2}, an electronic contribution is added to the ionic contribution of the matrix and the electrical conductivity increases significantly with the RuO{sub 2} content. This effect is described in terms of electrical percolation of the particle network. An electronic mechanism by tunnel transfer between particles is demonstrated. A mathematical model is developed to describe this mechanism in the solid composite. Beyond T{sub g}, conduction by the tunnel effect persists and the partial solubilization of RuO{sub 2} appears to be mainly responsible for the significant increase in electronic conductivity with the temperature. (author)

  14. The understanding of the R7T7 glass blocks long term behavior: chemical and transport coupling in fractured media; Comprehension de l'alteration a long terme des colis de verre R7T7: etude du couplage chimie transport dans un milieu fissure

    Energy Technology Data Exchange (ETDEWEB)

    Chomat, L

    2008-04-15

    The long term behavior of nuclear waste glass blocks depends highly on chemical reactions which occur at the surface in contact with water. Studies carried out on inactive fractured glass blocks show that fracture networks play a significant part in reactive surface area. Nevertheless, the complexity of results interpretation, due to a weak knowledge of fracture networks and local lixiviation conditions, does not allow us to comprehend the physical and chemical mechanisms involved. Model cracks are a key step to study chemical and transport coupling in fractured media. Crack lixiviation in aggressive conditions (pH{>=}11) show that the crack's position (horizontal or vertical) determines the dominant transport mechanism (respectively diffusion or convection induced by gravity). This gravity driven flow seems to be negligible in lower pH conditions. The convective velocity is estimated by a 1D model of reactive transport. Two other parameters are studied: the influence of thermal gradient and the influence of interconnected cracks on alteration. A strong retroactive effect of convection, due to thermal gradient, on the alteration kinetic is observed inside the crack. These works lead to a complete alteration experiment of a 163 crack network subject to a thermal gradient. The use of the geochemical software, HYTEC, within the framework of this study shows the potential of the software which is however limited by the kinetics law used. (author)

  15. Alteration of 'R7T7' type nuclear glasses: statistical approach, experimental validation, local evolution model; Alteration des verres nucleaires de type 'R7T7': demarche statistique, validation experimentale, modele local d'evolution

    Energy Technology Data Exchange (ETDEWEB)

    Thierry, F

    2003-02-01

    The aim of this work is to propose an evolution of nuclear (R7T7-type) glass alteration modeling. The first part of this thesis is about development and validation of the 'r(t)' model. This model which predicts the decrease of alteration rates in confined conditions is based upon a coupling between a first-order dissolution law and a diffusion barrier effect of the alteration gel layer. The values and the uncertainties regarding the main adjustable parameters of the model ({alpha}, Dg and C*) have been determined from a systematic study of the available experimental data. A program called INVERSION has been written for this purpose. This work lead to characterize the validity domain of the 'r(t)' model and to parametrize it. Validation experiments have been undertaken, confirming the validity of the parametrization over 200 days. A new model is proposed in the second part of this thesis. It is based on an inhibition of glass dissolution reaction by silicon coupled with a local description of silicon retention in the alteration gel layer. This model predicts the evolutions of boron and silicon concentrations in solution as well as the concentrations and retention profiles in the gel layer. These predictions have been compared to measurements of retention profiles by the secondary ion mass spectrometry (SIMS) method. The model has been validated on fractions of gel layer which reactivity present low or moderate disparities. (author)

  16. Contribution to the study of the mechanism of crack in amorphous silica: study by the molecular dynamics of crack in amorphous silica; Contribution a l'etude des mecanismes de rupture dans les amorphes: etude par dynamique moleculaire de la rupture de verre de silice

    Energy Technology Data Exchange (ETDEWEB)

    Van Brutzel, L

    2000-07-01

    The aim of this thesis was to understand the mechanism which occurs during the crack at the atomic scale in amorphous silica. The difficulties of the experimental observations at this length scale lead us to use numerical studies by molecular dynamics to access to the dynamical and the thermodynamical informations. We have carried out large simulations with 500000 atoms and studied the structure of the amorphous silica before to studying their behaviours under an imposed strain. The structure of this simulated amorphous silica settled in three length scales. In small length scale between 0 and 5 angstrom glass is composed of tetrahedra, this is close to the crystalline structure. In intermediate length scale between 3 and 10 angstrom tetrahedra are connected together and build rings of different sizes composed in majority between 5 and 7 tetrahedra. In bigger length scale between 15 and 60 angstrom, areas with high density of rings are surrounded by areas with low density of rings. These structural considerations play an important role in initiation and propagation of a crack. Indeed. in this length scale. crack propagates by growth and coalescence of some small cavities which appear in area with low density of rings behind the crack tip. The cavities dissipate the stress with carries away a delay to propagation of the crack. This phenomenons seems ductile and leads to non linear elastic behaviour near the crack tip. We have also shown that the addition of alkali in the amorphous silica changes the structure by creation of nano-porosities and leads to enhance the ductility during the crack propagation. (author)

  17. Long-term alteration of R7T7 glass packages: development of a multi-scale approach to estimate the cracking; Alteration a long terme des colis de verres de type R7T7: developpement d'une approche multi-echelle pour evaluer l'impact de la fracturation

    Energy Technology Data Exchange (ETDEWEB)

    Chomat, L. [Paris-6 Univ. Pierre et Marie Curie, 75 (France)]|[CEA Valrho, Lab. d' Etudes du Comportement Long Terme des Materiaux de Conditionnement (LCLT), 30 - Marcoule (France)

    2006-07-01

    The aim of this work is to model the alteration and transport mechanisms implied in a cracks system and to deduce the evolution of the quantity of leached glass. This quantity will be then compared with those measured in leaching tests carried out on a package of industrial size. To estimate this quantity, several steps are required: 1)study of the local alteration inside a crack (according to the alteration parameters: flow, crack opening, pH..) or in a simple set of cracks (connexion); 2)description of a crack system at the package scale by tomography and SEM of bulk samples: opening, accessibility; 3)determination of the alteration parameters in the ALISE device (leaching device of industrial size in which is altered a package for 2001): temperatures gradients, convection, diffusion, pH..; 4)modelling: passage from the local alteration (crack) to the global alteration (package); 5)design and carrying out of a specific experiment to validate the model: control of the system of known cracks (opening, connectivity..) and of the alterations conditions (thermal gradient..); 6)confrontation of the model with the results obtained on ALISE and the specific experiment indicated in 5). The main experimental results are described. (O.M.)

  18. Partitioning of the rare earths and actinides between R7T7 nuclear glass alteration products and solution according to disposal conditions; Partage des terres rares et des actinides entre solution et produits d`alteration du verre nucleaire type R7T7 en fonction des conditions de stockage

    Energy Technology Data Exchange (ETDEWEB)

    Menard, O

    1995-10-25

    The alteration of nuclear glass by water is liable to release radionuclides into the environment. Determining the release kinetics of these elements and their aqueous chemical forms are therefore essential steps in establishing the safety of a geological repository site. Leach tests were conducted with a nonradioactive specimen of the French ``R7T7`` light water containment glass spiked with U and Th, and with two R7T7 specimens spiked with {sup 237}Np and {sup 239}Pu, respectively. The alteration solution compositions were representative of deep groundwater and contained carbonate, sulfate, phosphate, fluorine and chlorine ions. The release of U, Th, Np and Pu, as well as of the rare earths La, Ce and Nd were monitored by ICP mass spectrometry and by {alpha} spectrometry. Scanning and transmission electron microscopic examination of the nonradioactive altered glass surfaces was also performed to assess the partitioning balance for the rare earths, U and Th between the glass alteration products and solution. The mobility of these elements depends on two competing mechanisms. The rare earths and thorium are incorporated in the alteration products (gel); the retention process is assumed to involve chemisorption or coprecipitation, enhanced in the gel layer by the presence of phosphate ions in particular. Conversely, the aqueous species in the alteration solutions (mainly anions) form complexes with the actinides and rare earths; this phenomenon is particularly evident with U and Np. The presence of carbonate ions favors this mobility. Plutonium differs from U and Np in that it is adsorbed mainly on colloids formed by glass dissolution, the principal factors governing its chemical evolution in solution. (author). refs., 122 figs., 185 tabs.

  19. Micro-ion beam analysis of physico-chemical reactions in vitro induced by nano-structured sol-gel derived bioactive glasses; Caracterisation par micro-faisceau d'ions des reactions physico-chimiques induites in vitro par des verres bioactifs nanostructures elabores par la methode sol-gel

    Energy Technology Data Exchange (ETDEWEB)

    Lao, J

    2007-07-15

    The study of bioactive glasses is a multi-field area of research aiming at a major goal: the development of new generation biomaterials that would be able to bond with host tissues through the formation of a strong interfacial bond, together with helping the body heal itself through the stimulation of specific cellular responses. Thus clinical applications of bioactive glasses mainly concern dental surgery and orthopedics, for filling osseous defects. For this purpose, we have elaborated bioactive glasses in the binary SiO{sub 2}-CaO system, ternary SiO{sub 2}-CaO-P{sub 2}O{sub 5} system, and for the first time, to our knowledge, strontium-doped SiO{sub 2}-CaO-SrO and SiO{sub 2}-CaO-P{sub 2}O{sub 5}-SrO glasses. The materials were elaborated using the sol-gel process, which allowed the synthesis of nano-porous materials with great purity and homogeneity. The bio-activity of the glasses was clearly demonstrated in vitro: in contact with biological fluids, the whole lot of mate-rials were able to induce the formation of a Ca-P-Mg layer a few microns thick at their surface. Our work is characterized by the use of PIXE-RBS nuclear microprobes to study the bioactive glass/biological fluids interface. Thanks to these methods we obtained chemical maps that made possible the analysis of major and trace elements concentrations at the interface. Moreover, quantitative information regarding the local reactivity of glasses were acquired. These data are important to evaluate the kinetics and amplitude of the physico-chemical reactions involved in the bio-activity process. Thus, we highlighted that the binary glass is the highest reactive regarding the dissolution of the glassy matrix as well as the first appearance of the Ca-P rich layer. However the Ca/P atomic ratio calculated at the glass/biological fluids interface decreases slowly, indicating that the Ca-P-Mg layer encounters difficulties to be changed into a more stable apatitic phase. For the P-containing glasses, the de-alkalinization of the matrix and the formation of the calcium phosphate layer are delayed. However, calculation of the interfacial Ca/P ratios along with supersaturation studies of the biological medium demonstrate that the Ca-P-Mg layer is quickly changed into an apatitic phase. Concerning the Sr-doped glasses, we highlighted that the dissolution of the material decreased and that the Ca-P-Mg layer was formed on a reduced depth. Nevertheless, according to the rapid decrease of the Ca/P ratio, there is evidence that the layer is more quickly changed into apatite, We also demonstrated that traces of Sr are both present at the glass/biological fluids interface and diffused in the biological medium. Knowing the positive effects of Sr on the cellular activity and on the bone modelling process, it might result in an improved bio-activity for the Sr-doped glasses in contact with a living system. (author)

  20. Wastes vitrification by plasma torch: study of a glass formulation compatible with a wide range of B wastes; Vitrification des dechets par torche a plasma: recherche d'une formulation de verre compatible avec un large eventail de dechets B

    Energy Technology Data Exchange (ETDEWEB)

    Poitou, S.; Richaud, D.; Fiquet, O.; Gramondi, P.; Massit, H. [CEA Cadarache, Dept. d' Entreposage et de Stockage des Dechets, 13 - Saint-Paul-lez-Durance (France)

    2001-07-01

    Within the context of radioactive waste management, CEA has equipped itself with a 'PLASMARC' device. The central element of this device is a plasma torch treatment furnace. It has been implemented and validated for the vitrification of low level radioactive wastes. Meanwhile, the plasma torch presents potentially interests for immobilizing under an inert form in vitreous matrices, B wastes which are generally divided and of complex chemical composition. The application of this process to this type of wastes has been studied here. The obtained results show that with the plasma torch it is possible to make glasses with a high amount of silicon and aluminium oxide and which are adapted to the treatment / packaging of the B wastes. (O.M.)

  1. The understanding of the R7T7 glass blocks long term behavior: chemical and transport coupling in fractured media; Comprehension de l'alteration a long terme des colis de verre R7T7: etude du couplage chimie transport dans un milieu fissure

    Energy Technology Data Exchange (ETDEWEB)

    Chomat, L

    2008-04-15

    The long term behavior of nuclear waste glass blocks depends highly on chemical reactions which occur at the surface in contact with water. Studies carried out on inactive fractured glass blocks show that fracture networks play a significant part in reactive surface area. Nevertheless, the complexity of results interpretation, due to a weak knowledge of fracture networks and local lixiviation conditions, does not allow us to comprehend the physical and chemical mechanisms involved. Model cracks are a key step to study chemical and transport coupling in fractured media. Crack lixiviation in aggressive conditions (pH{>=}11) show that the crack's position (horizontal or vertical) determines the dominant transport mechanism (respectively diffusion or convection induced by gravity). This gravity driven flow seems to be negligible in lower pH conditions. The convective velocity is estimated by a 1D model of reactive transport. Two other parameters are studied: the influence of thermal gradient and the influence of interconnected cracks on alteration. A strong retroactive effect of convection, due to thermal gradient, on the alteration kinetic is observed inside the crack. These works lead to a complete alteration experiment of a 163 crack network subject to a thermal gradient. The use of the geochemical software, HYTEC, within the framework of this study shows the potential of the software which is however limited by the kinetics law used. (author)

  2. 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)

  3. R7T7 glass alteration mechanism in an aqueous closed system: understanding and modelling the long term alteration kinetic; Etude des mecanismes d'alteration par l'eau du verre R7T7 en milieu confine: comprehension et modelisation de la cinetique residuelle

    Energy Technology Data Exchange (ETDEWEB)

    Chave, T

    2007-10-15

    The long term alteration rate of the French R7T7 nuclear glass has been investigated since many years because it will define the overall resistance of the radionuclide containment matrix. Recent studies have shown that the final rate remains constant or is slightly decreasing with time. It never reaches zero. Though this residual rate is very low, only 5 nm per year at 50 C, it would be the dominant alteration phenomenon in a geological repository. Two mechanisms are suggested for explaining such behaviour: diffusion in solution of elements from glass through an amorphous altered layer and precipitation of neo-formed phases. The diffusion processes are in agreement with a solid state diffusion mechanism and can lead to secondary phase precipitation due to solution concentration increases. Observed phases are mainly phyllosilicates and zeolites, in specific conditions. Phyllosilicates are expected to maintain the residual kinetic rate whereas alteration resumption could be observed in presence of zeolites at very high pH or temperature (10.5 at 90 C or temperature above 150 C). Both diffusion and neo-formed phase precipitation have been investigated in order to better understand their impact on the residual alteration rate and have then been modelled by a calculation code, coupling chemistry and transport, in order to be able to better anticipate the long term behaviour of the glass R7T7 in an aqueous closed system. (author)

  4. Chemical durability and resistance to irradiation of LnYSiAlO (Ln=La or Ce) glasses, potential immobilization matrix of minor actinides; Durabilite chimique et comportement a l'irradiation des verres quaternaires LnYSiAlO (Ln = La ou Ce), matrice potentielle d'immobilisation d'actinides mineurs trivalents

    Energy Technology Data Exchange (ETDEWEB)

    Gavarini, St

    2002-11-01

    Rare earth aluminosilicate glasses are known for their interesting mechanical and optical properties. Recent studies have shown that their chemical durability was very good too, such they have the potential to be used in the nuclear industry for the specific immobilization of trivalent actinides. Initial dissolution rates of LaYSiAlO and CeYSiAlO were determined using a Soxhlet device (dynamic leaching). The differences linked to the nature of the rare earth element were studied by synthesizing analogous glasses that only differed in their rare earth element composition (%at.): Y-5%, La-5 %, Si-15%, Al-10% O-65%. The influence of pH on the dissolution mechanisms and kinetics was also studied by static leaching tests performed in dilute solutions of NaOH or HNO{sub 3}. Electronic defects and collision cascades, induced by a-disintegration of radioelements confined in storage matrix, can cause important modifications in the glass structure and, thus, influence its chemical durability. To simulate these effects, glass samples were irradiated with {beta} particles and heavy ions accelerated to 2,5 MeV and 200 keV, respectively. Monoliths were then leached in static bi-distilled water (pH{>=}{>=} 5.5) for one month in an autoclave heated to 90 degrees C. Initially, the structural changes caused by irradiation were determined using Raman, NMR and EPR spectroscopies. Ion {mu}-beams, SEM-EDS and XPS analysis were also performed to evaluate the potential modifications of the superficial composition. Finally, the leaching behavior was studied, for both irradiated and unirradiated samples, through solution and solid elementary characterization. (author)

  5. Guides d’onde en verres et vitrocéramiques fluorés dopés terre rare élaborés par PVD pour l’émission dans le visible et la conversion de fréquence

    OpenAIRE

    Dieudonné , Belto

    2012-01-01

    The project joins in the development of miniaturized laser sources RGB for display and videoprojection, frequency conversion in solar cells.Fluoride glasses ZLAG ( ZrF4-LaF3-AlF3-GaF3) co-doped with rare earths were studied. This glass has a low phonon energy, a strong solubility of the rare earth ions and can be fabricated as thin films by PVD. It is also the precursor of transparent glass-ceramics. Similar emissions in both co-doped bulk and waveguides have been observed ; blue, orange, red...

  6. Status of the synroc project

    International Nuclear Information System (INIS)

    Reeve, K.D.; Ramm, E.J.; Woolfrey, J.L.; Ryan, R.K.; Buykx, W.J.; Cassidy, D.J.; Webb, C.E.

    1980-10-01

    SYNROC-B has been proposed as a vehicle for the immobilisation of solidified radioactive waste. It consists of an assemblage of three synthetic mineral phases: perovskite, barium hollandite and zirconolite. Fabrication studies, leach testing and irradiation testing of SYNROC are reported

  7. Phase equilibria, leaching characteristics and ceramic processing of SYNROC D formulations for US defense wastes

    International Nuclear Information System (INIS)

    Newkirk, H.; Ryerson, F.; Coles, D.; Hoenig, C.; Rozsa, R.; Rossington, C.; Bazan, F.; Tewhey, J.

    1980-01-01

    The assemblage of coexisting phases in SYNROC D is perovskite, zirconolite, nepheline and spinel. Cesium from the supernate is to be immobilized in hollandite. In the current processing scheme, presynthesized granules of hollandite are added to calcined SYNROC D powders prior to hot procesing or sintering. The disposition of inert and radwaste components of Savannah River Plant (SRP) wastes in SYNROC D formulations has been determined by means of optical microscopy, XRD, XRF, SEM, STEM, electron microprobe analysis and autoradiography. A summary of results is presented. Leaching studies of SYNROC D have been done by means of static, high temperature experiments and continuous-flow experiments. The data reported are from high-temperature experiments (distilled water, powdered sample, 150 0 C, one day). The elements reported are the only ones observed in the leachate. Analysis was done by means of XRF. The flowsheet which depicts the current experimental methods that are being employed at LLNL to produce SYNROC D samples containing presynthesized Cs-bearing hollandite is presented. The starting material for SYNROC D (high Fe, high Al and composite compositions) is simulated sludge obtained in 55 gallon quantities from Southwestern Chemical Corporation. Hot pressing temperatures for SYNROC D are 1000 to 1150 0 C. Hot pressing temperatures for hollandite are 1200 to 1400 0 C

  8. Study on the formation of heterogeneous structures in leached layers during the corrosion process of glass

    OpenAIRE

    Willemien Anaf

    2010-01-01

    Le verre, corrodé dans des conditions naturelles, montre souvent des hétérogénéités dans la couche lixiviée, comme une structure lamellaire ou des inclusions de MnO2 ou Ca3(PO4)2. La formation de ces hétérogénéités n’est pas encore bien comprise. Des structures de ce type ont été produites artificiellement en laboratoire en immergeant des échantillons de verre dans des solutions riches en métaux. Les résultats expérimentaux ont été comparés avec des théories décrivant la corrosion du verre.Gl...

  9. Stress Corrosion of Ceramic Materials.

    Science.gov (United States)

    1983-10-01

    Scientifique Continentale du Verre , Charleroi, Belgium, 1962. Dunning, J.M., Effects of Aqueous Chemical Environments on Crack Propagation in Quartz, this volume...Symposium on Mechanical Strength of Glass and Ways of Improving It. Florence, Italy, September 25-29, 1961. Union Scientifique Continentale du Verre ...F-0e38 UNCLSIFIEDF/G 112 N moflfllh....h... I fflfflfflffl..fNDf EIEEEEEEE % le 1111.0 L4 5 .8 _ = g 13 2 . LL IMI 11111= _"A 2.2 MICROCOPY

  10. Current Flow Through Two Dimensional Arrays of Metal Nanoparticles as a Novel Sensor Platform

    Science.gov (United States)

    2009-05-01

    de qualité élevée, du verre et des substrats de polyéthylène, formaient de tels films. L’implantation de 2-CEES était...Suffield TM 2009-068; R & D pour la défense Canada – Suffield; août 2009. Les indicateurs d’exposition de type macarons sont une composante essentielle... de l’environnement du soldat. On a récemment expérimenté pour mieux résoudre ce problème en déposant des nanoparticules de métal sur du verre

  11. STUDY OF FLUORIDE GLASSES DEVITRIFICATION-BASED ...

    African Journals Online (AJOL)

    4 mars 2013 ... D'après la définition du verre donnée par A. S. T. M : le verre est un produit de fusion des composés chimiques ... t : temps (s). K : facteur global qui tient compte des vitesses de nucléation et de croissance n : coefficient d'Avrami qui dépend du mécanisme de cristallisation. Le paramètre K dépend de la ...

  12. Octahedral molecular sieve sorbents and catalysts

    Science.gov (United States)

    Li, Liyu [Richland, WA; King, David L [Richland, WA

    2010-04-20

    Octahedral molecular sieve sorbents and catalysts are disclosed, including silver hollandite and cryptomelane. These materials can be used, for example, to catalyze the oxidation of CO.sub.x (e.g., CO), NO.sub.x (e.g., NO), hydrocarbons (e.g., C.sub.3H.sub.6) and/or sulfur-containing compounds. The disclosed materials also may be used to catalyze other reactions, such as the reduction of NO.sub.2. In some cases, the disclosed materials are capable of sorbing certain products from the reactions they catalyze. Silver hollandite, in particular, can be used to remove a substantial portion of certain sulfur-containing compounds from a gas or liquid by catalysis and/or sorption. The gas or liquid can be, for example, natural gas or a liquid hydrocarbon.

  13. Photoelastic Studies of Internal Stress Distributions of Unidirectional Composites.

    Science.gov (United States)

    1980-12-01

    34 verre a, If t nece, e.ry and Identify by block number) ..... ’Io-dimensional phutoelastli, models were used to determine internal taading-. and...Secretary of Defense for Research and Engineering, le Pe, ,tagon,, Uashington, D.C. 10301 ]2 Commandr, T)efens. lecn, ical Information Center, Cameron

  14. AS_597_A4 OK

    African Journals Online (AJOL)

    AKA BOKO

    Dans l'industrie du verre d'emballage, la partie la plus importante des pertes ... des paramètres contrôlables dans le processus d'optimisation du procédé de .... le nombre de colonnes minimum n=nombre facteurs+nombre d'interactions.

  15. Connaissances et usages traditionnels des plantes médicinales du ...

    African Journals Online (AJOL)

    SARAH

    ... didierdibong@yahoo.fr. Original submitted in on 13th February 2017. Published online at www.m.elewa.org on 31st May 2017 ..... hypertension artérielle. -Macération. 1 verre matin et soir pendant ..... A guide for health-care professional.

  16. 986-IJBCS-Article-Dr Niebie Roger

    African Journals Online (AJOL)

    DR GATSING

    activité antioxydante des extraits de basilic. En effet, après 23 jours de .... d'un appareil du type Clevenger pendant 3 heures. Lors de la distillation, l'huile ... conservée dans des flacons en verre ambré hermétiquement fermés et conservés au.

  17. Schouderarthrodese

    NARCIS (Netherlands)

    Fontijne, Willem

    1965-01-01

    SAMENVATTING Het na-onderzoek van een aantal patienten bij wie een schouderarthrodese was gedaan leerde dat de beweging van de arm in abductie verre ten achter bleef bij die in anteflexie, waarbij de stand der arthrodese een ankylose in grotere abductie dan in anteflexie werd nagestreefd en

  18. Investigations on the effects of triazole group fungicides on some important antagonistic fungi and non-pathogen Fusarium oxysporum (Schlecht) in vitro.

    OpenAIRE

    Demirci, A.; Katırcıoğlu, Z.; Demirci, F.

    2008-01-01

    The effects of eight triazole fungicides (cyproconazole, diniconazole, flusilazole hexaconazole, myclobutanil, penconazole, tebuconazole and triticinazole) on some important antagonistic fungi [Trichoderma harzianum (Rifai), T. viride (Pers. ex Gray), T. pseudokoningii (Rifai), T. hamatum (Bonard), Gliociadium viride (Matrouchot), Aspergillus niger (Tieghem), Penicillium verrııcosum (Dierckx)] and non-pathogen Fusarium oxysporum (Schlecht) were investigated on PDA in vitro. EC5 0 values ...

  19. Investigations on the effects of triazole group fungicides on some important antagonistic fungi and non-pathogen Fusarium oxysporum (Schlecht) in vitro.

    OpenAIRE

    Demirci, A.; Katırcıoğlu, Z.; Demirci, F.

    2008-01-01

    The effects of eight triazole fungicides (cyproconazole, diniconazole, flusilazole hexaconazole, myclobutanil, penconazole, tebuconazole and triticinazole) on some important antagonistic fungi [Trichoderma harzianum (Rifai), T. viride (Pers. ex Gray), T. pseudokoningii (Rifai), T. hamatum (Bonard), Gliociadium viride (Matrouchot), Aspergillus niger (Tieghem), Penicillium verrııcosum (Dierckx)] and non-pathogen Fusarium oxysporum (Schlecht) were investigated on PDA in vitro. EC5 0 values ...

  20. Synthèse: Revue des Sciences et de la Technologie - Vol 24 (2015)

    African Journals Online (AJOL)

    Synthèse: Revue des Sciences et de la Technologie - Vol 24 (2015) ... hygrothermique en eau douce sur un composite unidirectionnel verre-époxy · EMAIL ... Problèmes de type obstacle : algorithmes de résolution · EMAIL FREE FULL TEXT ...

  1. Le début d'une nouvelle vie pour de vieux ordinateurs | CRDI ...

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

    25 janv. 2011 ... En cette ère de l'électronique, l'évolution rapide de la technologie a créé un ... un terrain inutilisable où s'amoncellent verre brisé, métal et plastique. .... trois fois plus rapidement que celui de tout autre type de déchet urbain.

  2. Leishmaniose : maladie sans frontières | CRDI - Centre de ...

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

    La leishmaniose viscérale, la forme la plus sévère de la maladie, .... une petite bière », sourit-il en levant son verre avant d'embrasser son accordéon. ... 20 espèces de parasites du type leishmania; 90 espèces de phlébotomes vecteurs.

  3. MODELING OF THE THERMAL BEHAVIOR OF METALS DURING ...

    African Journals Online (AJOL)

    30 juin 2012 ... Laboratoire LENREZA, Département de Physique, Faculté des ... Le milieu actif dans les lasers solides est un verre ou un cristal. ... modélisation numérique est un outil de prédiction du comportement des matériaux pour.

  4. Dispersion capacitive de l'interface H2SO4/Pt Capacitive dispersion ...

    African Journals Online (AJOL)

    Administrateur

    Département de Physique, Faculté des Sciences Exactes. Université des .... d'un comportement idéal de la capacité. Au vu .... Figure 2 : Photographie de la cellule Pt/0,5 MH2SO4 (fabriquée par Verre-Lab Constantine) plongée dans un bain.

  5. Comportement à la corrosion intrinsèque de couches minces à base ...

    African Journals Online (AJOL)

    Comportement à la corrosion intrinsèque de couches minces à base d'aluminium (Al-M: M=Mo, Mg, ... Département de Physique, Université Badji Mokhtar, BP 12, Annaba 23000, Algérie. .... dépôts réalisés sur substrat en verre servent pour la ...

  6. Etude expérimentale et analyse probabiliste du comportement à la ...

    African Journals Online (AJOL)

    DK

    en traction de composites verre-perlon-acrylique à usage orthopédique. Experimental ... du comportement à la rupture de ces stratifiés ainsi que l'aspect probabiliste de cette dernière sont décrits .... signification physique qui donne au volume.

  7. 50 Modélisation des propriétés diélectriques des nanocomposites ...

    African Journals Online (AJOL)

    AKA BOKO

    3 Laboratoire de Physique des Solides et des Couches Minces, Faculté des Sciences,. Sémlalia ... renfort (fibres de verre, carbone ou Kevlar,..) ont alors été utilisés ... diélectrique. Par ailleurs, pour modéliser le comportement diélectrique à la.

  8. Case series

    African Journals Online (AJOL)

    ebutamanya

    23 oct. 2015 ... secondaires à des agressions physiques sur une durée de trois ans. Les critères d'inclusion ... morceaux de verre. Dans notre série .... contre les comportements agressifs; les médias devront éliminer la diffusion de portraits ...

  9. Caractérisation d'un béton autoplaçant avec addition de laitier ...

    African Journals Online (AJOL)

    DK

    comportement à l'état frais (étalement, taux de remplissage et stabilité au tamis) et le comportement à l'état durci. (essai de .... Compositions chimiques et caractéristiques physiques des additions. Oxydes. (%) ...... nulé et de la poudre de verre.

  10. ETUDE DE LA DISTRIBUTION DES CATIONS ECHANGEABLES

    African Journals Online (AJOL)

    SEI Joseph

    été mené dans une serre en verre au département de Biologie (Université de ... taux de Na+ et K+, et fait l'analyse des paramètres physique et chimique du sol .... comportement de cette espèce : Atriplex. halimus vis-à-vis de cinq doses de ...

  11. SIMULATION OF THERMO-ELASTICS PROPERTIES OF THERMAL ...

    African Journals Online (AJOL)

    30 juin 2011 ... Energies Renouvelables, Faculté des sciences, Département de physique, université de ... proche de celle des verres (de 1 à 2 W.m-1. ..... amélioration et le comportement du revêtement sans traitement thermique sera quasi.

  12. Distributie in een turbulente wereld : over de voornaamste ontwikkelingen van invloed op (distributie)logistiek en hoe bedrijven hierop inspelen

    NARCIS (Netherlands)

    Laarhoven, van P.J.M.

    1999-01-01

    De logistiek manager wordt heden ten dage met talloze trends en ontwikkelingen geconfronteerd, en het is verre van duidelijk, laat staan eenvoudig, bij de planning en aansturing van logistieke activiteiten met deze trends rekening te houden of er op in te spelen. In dit artikel wordt een aantal van

  13. Pentateugtradisies in die boek Hosea

    African Journals Online (AJOL)

    om te bepaal of die verwysing na 'n gebeure te doen het met die verre verlede of met die .... Hosea 2:1-2 JHWH se trou aan sy beloftes. ... dat huile na Egipte sal terugkeer. Die presiese bedoeiing van die woorde 'huile sal terugkeer na Egipte' is omstre- de. Kommentatore soos Rudolph meen dat dit verstaan moet word as ...

  14. Infectious souvenirs: the toll of travel?

    NARCIS (Netherlands)

    Baaten, G.G.G.

    2011-01-01

    Reizen naar ontwikkelingslanden brengt gezondheidsrisico’s met zich mee. Het meeste last hebben reizigers die al een ziekte onder de leden hebben. Om gezondheidsrisico’s van verre reizen te beperken en ziektes zo goed mogelijk te behandelen, is gefundeerde informatie onontbeerlijk. Helaas blijken

  15. Cesium release from ceramic waste form materials in simulated canister corrosion product containing solutions

    Energy Technology Data Exchange (ETDEWEB)

    Vittorio, Luca; Drabarek, Elizabeth; Chronis, Harriet; Griffith, Christopher S

    2004-07-01

    It has previously been demonstrated that immobilization of Cs{sup +} and/or Sr{sup 2+} sorbed on hexagonal tungsten oxide bronze (HTB) adsorbent materials can be achieved by heating the materials in air at temperatures in the range 500 - 1300 deg C. Highly crystalline powdered HTB materials formed by heating at 800 deg C show leach characteristics comparable to Cs-containing hot-pressed hollandites in the pH range from 0 to 12. As a very harsh leaching test, and also to model in a basic manner, leaching in the presence of canister corrosion products in oxidising environments, leaching of the bronzoid phases has been undertaken in Fe(NO{sub 3}){sub 3} solutions of increasing concentration. This is done in comparison with Cs -hollandite materials in order to compare the leaching characteristics of these two materials under such conditions. Both the Cs-loaded bronze and hollandite materials leach severely in Fe(NO{sub 3}){sub 3} losing virtually all of the immobilized Cs in a period of four days at 150 deg C. Total release of Cs and conversion of hollandite to titanium and iron titanium oxides begins to be observed at relatively low concentrations and is virtually complete after four days reaction in 0.5 mol/L Fe(NO{sub 3}){sub 3}. In the case of the bronze, all of the Cs is also extracted but the HTB structure is preserved. The reaction presumably involves an ion-exchange mechanism and iron oxide with a spinel structure is also observed at high Fe concentrations. (authors)

  16. Cesium release from ceramic waste form materials in simulated canister corrosion product containing solutions

    International Nuclear Information System (INIS)

    Vittorio, Luca; Drabarek, Elizabeth; Chronis, Harriet; Griffith, Christopher S.

    2004-01-01

    It has previously been demonstrated that immobilization of Cs + and/or Sr 2+ sorbed on hexagonal tungsten oxide bronze (HTB) adsorbent materials can be achieved by heating the materials in air at temperatures in the range 500 - 1300 deg C. Highly crystalline powdered HTB materials formed by heating at 800 deg C show leach characteristics comparable to Cs-containing hot-pressed hollandites in the pH range from 0 to 12. As a very harsh leaching test, and also to model in a basic manner, leaching in the presence of canister corrosion products in oxidising environments, leaching of the bronzoid phases has been undertaken in Fe(NO 3 ) 3 solutions of increasing concentration. This is done in comparison with Cs -hollandite materials in order to compare the leaching characteristics of these two materials under such conditions. Both the Cs-loaded bronze and hollandite materials leach severely in Fe(NO 3 ) 3 losing virtually all of the immobilized Cs in a period of four days at 150 deg C. Total release of Cs and conversion of hollandite to titanium and iron titanium oxides begins to be observed at relatively low concentrations and is virtually complete after four days reaction in 0.5 mol/L Fe(NO 3 ) 3 . In the case of the bronze, all of the Cs is also extracted but the HTB structure is preserved. The reaction presumably involves an ion-exchange mechanism and iron oxide with a spinel structure is also observed at high Fe concentrations. (authors)

  17. Modeling of Materials for Energy Storage: A Challenge for Density Functional Theory

    Science.gov (United States)

    Kaltak, Merzuk; Fernandez-Serra, Marivi; Hybertsen, Mark S.

    Hollandite α-MnO2 is a promising material for rechargeable batteries and is studied extensively in the community because of its interesting tunnel structure and the corresponding large capacity for lithium as well as sodium ions. However, the presence of partially reduced Mn ions due to doping with Ag or during lithiation makes hollandite a challenging system for density functional theory and the conventionally employed PBE+U method. A naive attempt to model the ternary system LixAgyMnO2 with density functionals, similar to those employed for the case y = 0 , fails and predicts a strong monoclinic distortion of the experimentally observed tetragonal unit cell for Ag2Mn8O16. Structure and binding energies are compared with experimental data and show the importance of van der Waals interactions as well as the necessity for an accurate description of the cooperative Jan-Teller effects for silver hollandite AgyMnO2. Based on these observations a ternary phase diagram is calculated allowing to predict the physical and chemical properties of LixAgyMnO2, such as stable stoichiometries, open circuit voltages, the formation of Ag metal and the structural change during lithiation. Department of Energy (DOE) under award #DE-SC0012673.

  18. Investigation of Chemical Durability Mechanisms and Structure of Fluoride Glasses.

    Science.gov (United States)

    1988-03-01

    Compositions of fluorozirconate glasses (mol%) mnemonic ZrF 4 BaF 2 LaF 3 A1F 3 LiF source ZBLA 57 36 3 4 -- RADC* ZBLA-F 51.16 38.62 5.66 4.56 -- Le Verre ...Fluore4 ZBLAL 51.8 20.0 5.3 3.3 19.6 NRL * Rome Air Development Center, Hanscom AFB, MA (Dr. El Bayoumi) # Le Verre Fluore’ Co., LeMans, France " Naval...Maine, LeMans, France, (with partial support from the French Foreign Office), studied corrosion of UF4 -based fluorides. - Michel Le Toullec - 10/86

  19. Un cas particulier de la relation partie-tout: les compléments adnominaux en à avec et sans article défini anaphorique

    Directory of Open Access Journals (Sweden)

    Vassil Mostrov

    2013-12-01

    Full Text Available This paper deals with the syntax and the interpretation of French noun phrases of the type N à N where a part-whole relationship is involved. We focus on the differences arising from the presence (un verre au pied doré/cassé or absence of a determiner (un verre à pied [doré] before the N denoting the part. We argue that both the adnominal complements à N (Mod and à LE N Mod function as adjectival constituents that qualify the noun denoting the whole, but the actualization of the part noun can be linguistically effective only in cases where the definite determiner, A-bound according to Guéron’s (1985, 2005 hypothesis, is present. The discussion considers the consequences of our analysis.

  20. Fabrication de soupe de poisson en bocal

    OpenAIRE

    Nicolle, Jean-pierre

    1983-01-01

    Le récipient en verre destiné à la conserve, qui connaît un intérêt croissant auprès des fabricants comme des utilisateurs, doit répondre aux deux points principaux de la définition de la conserve, c'est-à-dire être étanche aux gaz, liquides et micro-organismes et permettre un traitement d'appertisation qui rende le contenu propre il la consommation. Le but de cette note technique n'est pas de traiter théoriquement l'ensemble des problèmes liés aux différents pots en verre et types de capsula...

  1. Influence d'un ecran thermique sur le bilan energetique et le microclimat nocturnes d'une serre

    OpenAIRE

    Baille, M.; Laury, J.C.; Baille, Alain

    1984-01-01

    Dans cet article, on présente les résultats expérimentaux concernant les effets d’un écran thermique sur les déperditions énergétiques et le microclimat nocturnes de deux serres identiques, mais de matériaux de couverture différents : verre horticole ordinaire (V.O.) et verre à faible émissivité (V.F.E.). lorsque l’écran est déployé, on constate une diminution significative des pertes thermiques globales dans les deux serres. L’écran agit surtout au niveau des pertes par convection et par...

  2. Modélisation multi-échelles en viscoplasticité endommageable de composites thermoplastiques renforcés par des fibres discontinues

    OpenAIRE

    ACHOUR, Nadia; CHATZIGEORGIOU, George; BONNAY, Kevin; MERAGHNI, Fodil

    2017-01-01

    Un nouveau modèle multi-échelles en régime viscoplastique endommageable est développé pour un composite à matrice polypropylène renforcé par des fibres de verre courtes. Basé sur l’approche en champs moyens de Mori Tanaka, il intègre une matrice viscoplastique modélisée par un modèle phénoménologique nommé par ses auteurs DSGZ et des fibres de verres modélisées par un comportement élastique linéaire. Le modèle multi-échelles permet d’intégrer la microstructure du composite préalablement carac...

  3. Bragg Gratings, Photosensitivity, and Poling in Glass Fibers and Waveguides: Applications and Fundamentals. Technical Digest Series, Volume 17

    Science.gov (United States)

    1998-05-26

    Figure 2 shows LE spectra in preform B which is composed uniquely by cladding material. The excitation of luminescence has been achieved by...Ge02 concentration, i.e. larger than 20 mol%. Figure 3 shows LE spectra for various luminescence wavelengths collected from preform C. In that...doped fluoride glasses, F. Smektala, R. Sramek, J. Lucas, Laboratoire des Verres et Ceramiques, Universite de Rennes I, 35000 Rennes, France; W. Xie, P

  4. Weapons Effects in Cities. Volume 1

    Science.gov (United States)

    1974-12-01

    been poor to nonexistent. Platoon le ^ideTi are frequently out of sight and earr-hot of squads. Wire gets cut quii-kly by pro’octilr...radios verr Jepoittd to have worked well, perhaps because command posts and transmitting antennas were easy to emplace on top of the flat...Thus it appears to Le mathematically as well as practically invalid to use the nudel results a:* probabilities of kill or incnpncitatioii

  5. Sessile macro-epibiotic community of solitary ascidians, ecosystem engineers in soft substrates of Potter Cove, Antarctica

    OpenAIRE

    Rimondino, Clara; Torre, Luciana; Sahade, Ricardo Jose; Tatian, Marcos

    2016-01-01

    The muddy bottoms of inner Potter Cove, King George Island (Isla 25 de Mayo), South Shetlands, Antarctica, show a high density and richness of macrobenthic species, particularly ascidians. In other areas, ascidians have been reported to play the role of ecosystem engineers, as they support a significant number of epibionts, increasing benthic diversity. In this study, a total of 21 sessile macro-epibiotic taxa present on the ascidian species Corella antarctica Sluiter, 1905, Cnemidocarpa verr...

  6. 1840-IJBCS-Article-Sarr Bathie

    African Journals Online (AJOL)

    hp

    des minitubercules. Le calibre des minitubercules présente une variabilité de réponse selon la variété de pomme de terre et le type d'insecticide. Ce travail a permis ... Glomus mosseae avec l'application des insecticides au sol chez les variétés Aïda et Atlas de la pomme de terre. .... tubes de verres (22x150 mm) contenant.

  7. Connaissances et perceptions locales de la dynamique des ...

    African Journals Online (AJOL)

    chlorhydrique) et pH eau, par la méthode électrométrique au pH mètre à électrode de verre (AFNOR, 1999) . Une analyse diachronique des surfaces gravillonnaires a été réalisée à partir de la classification supervisée des images de type Landsat sur trois dates différentes : images Landsat ETM+ pour les périodes 1987 et.

  8. Activité antifongique de quelques plantes de la flore ivoirienne

    African Journals Online (AJOL)

    Administrateur

    Les extraits dichlorométhane, méthanolique et aqueux, réalisés à partir des poudres de feuilles ou de rameaux feuillés de chaque espèce, ont permis .... Les souches de référence proviennent des collections enregistrées à l'American Type Culture ... dans un verre de montre, sous hotte, l'extrait dichlorométhane. La poudre ...

  9. Leren van ver weg

    NARCIS (Netherlands)

    Switzer, Andrew

    2016-01-01

    Van de week kreeg ik in mijn klushuis in de Bijlmer bezoek over de vloer: een onderzoekster uit het verre São Paulo die samen met collega’s aan een project over zel ouw werkt. Wie aan zel ouw in Brazilië denkt, komt al snel uit op de favela’s en het valt te betwijfelen of er vraag is naar dit soort

  10. APPLICATION OF JUDD-OFELT THEORY UPON ...

    African Journals Online (AJOL)

    30 juin 2012 ... A. Babai et al. J Fundam Appl Sci. 2012, 4(1), 64-72. 66 fois, puis est moyennée afin d'obtenir des résultats fiables. Pour ce verre, la densité moyenne ..... J. Alloys Compd. 1998, 15, 275-277. [3] Philipps J. F., Töpfer T., Ebendorff-Heidepriem H., Ehrt D., Sauerbrey R. Spectroscopic and lasing properties of ...

  11. Analysis of the Reliable STING Early Warning System.

    Science.gov (United States)

    1982-03-01

    verr much appreciated. II .. . . . . . . . . . iV, , . . .l . . al I ll I III I I I III - 7 --7 ,,- ..11! I. INTRODUCTION A. BACKGROUND The U.S. Army is...information to a variety of elements ranging from the division staff to de ~loyed maneuver units, this study will focus on the air defense information...aircraft type . TABLE I Example Track Report ELEMENTS OF INFORMATION EXAMPLE IDENTIFICATION .................... HOSTILE TRACK DESIGNATOR

  12. 4TH Mediterranean Workshop and Tropical Meeting "Novel Optical Materials and Applications" NOMA 99.

    Science.gov (United States)

    1999-07-19

    Qu~mard", F. Smektalaa, V. Condereb, A. Barth616myb. aLaboratoire des Verres et Cramniques, Universit6 de Rennes 1, Avenue du G6n~raI Leclerc, 35042...and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES...insights toward a qualitative understanding of PDE’s. POLYMER CELL-WALL TYPE LIQUID CRYSTAL OPTICAL SHUTTERS AND THEIR APPLICATIONS TADAHIRO ASADA

  13. Developing Inhibitors of Ovarian Cancer Progression by Targeted Disruption of the Gamma-Synuclein Activated Migratory and Survival Signaling Pathways

    Science.gov (United States)

    2007-04-01

    Golub TR. A molecular signature of metastasis in primary solid tumors. Nat Gene 2003;33:49–54. 2. van’t Verr LJ, Dai H, van de Vijver MJ, et al. Gene...Philadelphia, Pennsylvania 19111 REPORT DATE: April 2007 TYPE OF REPORT: Final PREPARED FOR: U.S. Army Medical Research and... TYPE Final 3. DATES COVERED (From - To) 1 Apr 2003 – 31 Mar 2007 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Developing Inhibitors of Ovarian

  14. 13 Imorou WEB 02.pmd

    African Journals Online (AJOL)

    Owner

    deuxième partie de cette étude, celle-ci organise une relation d'identité entre trois ..... j'ai laissé parler l'enfant que j'étais en gommant les tics que l'âge adulte .... sa marginalité est sociale: Verre Cassé appartient au monde des bas fonds, ...

  15. Mesure du Deplacement de Frequence au Maximum de la Raie P20 un Laser CO2 a Ondes Guidees (Measurement of the Frequency Shift at the Peak of the P20 Line of a CO2 Waveguide Laser),

    Science.gov (United States)

    1986-06-01

    poinpC pendant environ 10 min, sauf celul en verre qul est scell - Apr~s avoir introduit le m~lange gazeux, on s~iectionne la temp~rature precise a...f~rence (n* 4 A la ref. 1) *Composition: 5.8% de N. 10.8% de CO2 83.4% de He Ce m~lange, qui est identique A celul utilis4 dans le laser A

  16. The nature of particulate organic matter settled on solid substrata

    Digital Repository Service at National Institute of Oceanography (India)

    Sharma, M.O.; Wagh, A.B.

    on these substrata. Oceollo!ogica Acta. 1990, 13,4,471-474. -~----~-------- I.• ABSTRACT --,- RESUME Composition de la matiere organique particulaire adsorbee sur un substrat solide La matiere organique particulaire adsorb&: sur des panneaux d'aluminium et de verre... immerges dans un estuaire a ete analysce: bacteries, chlorophylle a, poids sec, matiere organique, carbone organique, azote, proteines, glueides et lipides. Aucune difference n'a etc dccelee dans lacomposition de la matiere organique et dans les...

  17. Polymer and Surface Science in Europe, Israel, and Egypt: Some Observations,

    Science.gov (United States)

    1981-11-25

    scientist funding a university colleague to work jointly on some specific topic of mutual interest. The concept of a contract manager monitoring a...de Documentation du Verre Textile et des Plastiques Renforc’s, Paris, on 28 March 1979 (ESN 33-9:368 (19791 I had a qlimpse of the level of industrial...The University of Alexandria Research Center (UNARC) was started with considerable financial help from UNESCO. The concept and formation of UNARC

  18. 2259-IJBCS-Article-Bazouma Koulibaly

    African Journals Online (AJOL)

    hp

    4Unité de Formation des Sciences de la Vie et de la Terre (UFR/SVT), Laboratoire de Biologie et Ecologie. Végétale .... électrode en verre, selon un rapport ..... Impact des graminées sur une ressource rare : l'azote. In La Jachère en Afrique. Tropicale, Floret Ch, Pontanier R (eds). John Libbey Eurotext, Paris, 189-193.

  19. Study on the formation of heterogeneous structures in leached layers during the corrosion process of glass

    Directory of Open Access Journals (Sweden)

    Willemien Anaf

    2010-11-01

    Full Text Available Le verre, corrodé dans des conditions naturelles, montre souvent des hétérogénéités dans la couche lixiviée, comme une structure lamellaire ou des inclusions de MnO2 ou Ca3(PO42. La formation de ces hétérogénéités n’est pas encore bien comprise. Des structures de ce type ont été produites artificiellement en laboratoire en immergeant des échantillons de verre dans des solutions riches en métaux. Les résultats expérimentaux ont été comparés avec des théories décrivant la corrosion du verre.Glass that corrodes under natural conditions often shows heterogeneities in the leached layer, such as a lamellar structure or inclusions of MnO2 or Ca3(PO42. The formation of these heterogeneities is still not well understood. By means of experiments under laboratory conditions, our aim was to artificially generate specific structures. Therefore, glass samples were immersed in metal-rich solutions. The experimental results were compared with theories describing glass corrosion from a molecular point of view.

  20. Report on the scientific feasibility of new matrices for the conditioning of long lived radionuclides; Rapport sur la faisabilite scientifique des matrices nouvelles de conditionnement des radionucleides a vie longue

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    New specific matrices for the conditioning of long lived radionuclides (I, Cs, Tc, minor actinides) have been developed. This report presents the conditions of their synthesis by sintering or melting and the quantifying of their crystallographic, physical and thermal properties. A 7% mass insertion of iodine can be reached with a phosphorus-vanadium-lead iodo-apatite. A 5% mass insertion of cesium is reached with the hollandite-type crystal structure (barium aluminate-titanate). An insertion level of at least 10% mass of rare earth oxides (simulating the presence of actinides) is reached for britholite, zirconolite, thorium phosphate, monazite, and zirconolite glass/ceramic materials. The chemical durability has been also determined. Enhanced aqueous corrosion resistance, 100 times better than for the glasses used today, are obtained for iodo-apatite (I), hollandite (Cs), britholite (actinides 3+/4+), thorium phosphate (actinides 4+) and monazite (3+/4+). The first elements of stability with respect to irradiation are reported for the minor actinide conditioning matrices. External post-irradiation examinations by heavy ion bombardment coupled to atomistic modeling have been performed. The characterization of self-irradiated natural analogues of britholite, zirconolite and monazite with more than 10{sup 20} {alpha}/g disintegrations confirms the very long time stability of these mineral structures (>10{sup 8} years). On the basis of the obtained results, it appears that the iodo-apatite, britholite, zirconolite, and thorium phosphate conditioning matrices have reached the stage of scientifical feasibility. The monazite matrice is on the way to reach the feasibility too. Other specific matrices for technetium (metal alloys) and cesium (hollandite) are also under development, but their long-term properties remain to be determined. (J.S.)

  1. Comparison of structure, morphology, and leach characteristics of multi-phase ceramics produced via melt processing and hot isostatic pressing

    Science.gov (United States)

    Dandeneau, Christopher S.; Hong, Tao; Brinkman, Kyle S.; Vance, Eric R.; Amoroso, Jake W.

    2018-04-01

    Melt processing of multi-phase ceramic waste forms offers potential advantages over traditional solid-state synthesis methods given both the prevalence of melters currently in use and the ability to reduce the possibility of airborne radionuclide contamination. In this work, multi-phase ceramics with a targeted hollandite composition of Ba1.0Cs0.3Cr1.0Al0.3Fe1.0Ti5.7O16 were fabricated by melt processing at 1675 °C and hot isostatic pressing (HIP) at 1250 and 1300 °C. X-ray diffraction analysis (XRD) confirmed hollandite as the major phase in all specimens. Zirconolite/pyrochlore peaks and weaker perovskite reflections were observed after melt processing, while HIP samples displayed prominent perovskite peaks and low-intensity zirconolite reflections. Melt processing produced specimens with large (>50 μm) well-defined hollandite grains, while HIP yielded samples with a more fine-grained morphology. Elemental analysis showed "islands" rich in Cs and Ti across the surface of the 1300 °C HIP sample, suggesting partial melting and partitioning of Cs into multiple phases. Photoemission data revealed multiple Cs 3d spin-orbit pairs for the HIP samples, with the lower binding energy doublets likely corresponding to Cs located in more leachable phases. Among all specimens examined, the melt-processed sample exhibited the lowest fractional release rates for Rb and Cs. However, the retention of Sr and Mo was greater in the HIP specimens.

  2. Report on the scientific feasibility of new matrices for the conditioning of long lived radionuclides

    International Nuclear Information System (INIS)

    2001-01-01

    New specific matrices for the conditioning of long lived radionuclides (I, Cs, Tc, minor actinides) have been developed. This report presents the conditions of their synthesis by sintering or melting and the quantifying of their crystallographic, physical and thermal properties. A 7% mass insertion of iodine can be reached with a phosphorus-vanadium-lead iodo-apatite. A 5% mass insertion of cesium is reached with the hollandite-type crystal structure (barium aluminate-titanate). An insertion level of at least 10% mass of rare earth oxides (simulating the presence of actinides) is reached for britholite, zirconolite, thorium phosphate, monazite, and zirconolite glass/ceramic materials. The chemical durability has been also determined. Enhanced aqueous corrosion resistance, 100 times better than for the glasses used today, are obtained for iodo-apatite (I), hollandite (Cs), britholite (actinides 3+/4+), thorium phosphate (actinides 4+) and monazite (3+/4+). The first elements of stability with respect to irradiation are reported for the minor actinide conditioning matrices. External post-irradiation examinations by heavy ion bombardment coupled to atomistic modeling have been performed. The characterization of self-irradiated natural analogues of britholite, zirconolite and monazite with more than 10 20 α/g disintegrations confirms the very long time stability of these mineral structures (>10 8 years). On the basis of the obtained results, it appears that the iodo-apatite, britholite, zirconolite, and thorium phosphate conditioning matrices have reached the stage of scientifical feasibility. The monazite matrice is on the way to reach the feasibility too. Other specific matrices for technetium (metal alloys) and cesium (hollandite) are also under development, but their long-term properties remain to be determined. (J.S.)

  3. Topography and Mechanical Property Mapping of International Simple Glass Surfaces with Atomic Force Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, Eric M [ORNL

    2014-01-01

    Quantitative Nanomechanical Peak Force (PF-QNM) TappingModeTM atomic force microscopy measurements are presented for the first time on polished glass surfaces. The PF-QNM technique allows for topography and mechanical property information to be measured simultaneously at each pixel. Results for the international simple glass which represents a simplified version of SON68 glass suggests an average Young s modulus of 78.8 15.1 GPa is within the experimental error of the modulus measured for SON68 glass (83.6 2 GPa) with conventional approaches. Application of the PF-QNM technique will be extended to in situ glass corrosion experiments with the goal of gaining atomic-scale insights into altered layer development by exploiting the mechanical property differences that exist between silica gel (e.g., altered layer) and pristine glass surface.

  4. Stephane Gin's application file for the HDR (accreditation to supervise research) diploma

    International Nuclear Information System (INIS)

    Gin, St.

    2000-01-01

    This document contains a curriculum vitae of the candidate who is a researcher in the Marcoule CEA, and then a presentation of his personal and professional approach to scientific research and the main topic he has been studying, i.e. the long term behaviour of nuclear glasses. He indicates the numerous works performed in collaboration with other researchers, his supervision activities. He provides a list of his scientific publications, and three articles: Use of orthophosphate complexing agents to investigate mechanisms limiting the alteration kinetics of French SON 68 nuclear glass; Alteration kinetics of a simplified nuclear glass in an aqueous medium: effects of solution chemistry and of protective gel properties on diminishing the alteration rate; French SON 68 nuclear glass alteration mechanisms on contact with clay media

  5. Anomalous metallic state with strong charge fluctuations in BaxTi8O16 +δ revealed by hard x-ray photoemission spectroscopy

    Science.gov (United States)

    Dash, S.; Kajita, T.; Okawa, M.; Saitoh, T.; Ikenaga, E.; Saini, N. L.; Katsufuji, T.; Mizokawa, T.

    2018-04-01

    We have studied a charge-orbital driven metal-insulator transition (MIT) in hollandite-type BaxTi8O16 +δ by means of hard x-ray photoemission spectroscopy (HAXPES). The Ti 2 p HAXPES indicates strong Ti3 +/Ti4 + charge fluctuation in the metallic phase above the MIT temperature. The metallic phase is characterized by a power-law spectral function near the Fermi level which would be a signature of bad metal with non-Drude polaronic behavior. The power-law spectral shape is associated with the large Seebeck coefficient of the metallic phase in BaxTi8O16 +δ .

  6. Naturally occurring crystalline phases: analogues for radioactive waste forms

    International Nuclear Information System (INIS)

    Haaker, R.F.; Ewing, R.C.

    1981-01-01

    Naturally occurring mineral analogues to crystalline phases that are constituents of crystalline radioactive waste forms provide a basis for comparison by which the long-term stability of these phases may be estimated. The crystal structures and the crystal chemistry of the following natural analogues are presented: baddeleyite, hematite, nepheline; pollucite, scheelite;sodalite, spinel, apatite, monazite, uraninite, hollandite-priderite, perovskite, and zirconolite. For each phase in geochemistry, occurrence, alteration and radiation effects are described. A selected bibliography for each phase is included

  7. Tunnel-Structured KxTiO2 Nanorods by in Situ Carbothermal Reduction as a Long Cycle and High Rate Anode for Sodium-Ion Batteries.

    Science.gov (United States)

    Zhang, Qing; Wei, Yaqing; Yang, Haotian; Su, Dong; Ma, Ying; Li, Huiqiao; Zhai, Tianyou

    2017-03-01

    The low electronic conductivity and the sluggish sodium-ion diffusion in the compact crystal structure of Ti-based anodes seriously restrict their development in sodium-ion batteries. In this study, a new hollandite K x TiO 2 with large (2 × 2) tunnels is synthesized by a facile carbothermal reduction method, and its sodium storage performance is investigated. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses illustrate the formation mechanism of the hollandite K x TiO 2 upon the carbothermal reduction process. Compared to the traditional layered or small (1 × 1) tunnel-type Ti-based materials, the hollandite K x TiO 2 with large (2 × 2) tunnels may accommodate more sodium ions and facilitate the Na + diffusion in the structure; thus, it is expected to get a large capacity and realize high rate capability. The synthesized K x TiO 2 with large (2 × 2) tunnels shows a stable reversible capacity of 131 mAh g -1 (nearly 3 times of (1 × 1) tunnel-structured Na 2 Ti 6 O 13 ) and superior cycling stability with no obvious capacity decay even after 1000 cycles, which is significantly better than the traditional layered Na 2 Ti 3 O 7 (only 40% of capacity retention in 20 cycles). Moreover, the carbothermal process can naturally introduce oxygen vacancy and low-valent titanium as well as the surface carbon coating layer to the structure, which would greatly enhance the electronic conductivity of K x TiO 2 and thus endow this material high rate capability. With a good rate capability and long cyclability, this hollandite K x TiO 2 can serve as a new promising anode material for room-temperature long-life sodium-ion batteries for large-scale energy storage systems, and the carbothermal reduction method is believed to be an effective and facile way to develop novel Ti-based anodes with simultaneous carbon coating and Ti(III) self-doping.

  8. Sintering, microstructural and dilatometric studies of combustion synthesized Synroc phases

    International Nuclear Information System (INIS)

    Muthuraman, M.; Patil, K.C.; Senbagaraman, S.; Umarji, A.M.

    1996-01-01

    Sintering, microstructure, and linear thermal expansion properties of Synroc-B and constituent phases, viz. perovskite CaTiO 3 , zirconolite ZrTi 2 O 7 , hollandite (ideal formula BaAl2Ti 6 O 16 ) have been investigated. Synroc-B powder when pelletized and sintered at 1250 C for 2 h achieved >95% theoretical density. Sintered Synroc-B has a linear thermal expansion coefficient α of 8.72 x 10 -6 K -1 and Vicker's microhardness 9.88 GPa. The linear thermal expansion curves did not show any hysteresis indicating the absence of microcracking in the sintered bodies

  9. Naturally occurring crystalline phases: analogues for radioactive waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Haaker, R.F.; Ewing, R.C.

    1981-01-01

    Naturally occurring mineral analogues to crystalline phases that are constituents of crystalline radioactive waste forms provide a basis for comparison by which the long-term stability of these phases may be estimated. The crystal structures and the crystal chemistry of the following natural analogues are presented: baddeleyite, hematite, nepheline; pollucite, scheelite;sodalite, spinel, apatite, monazite, uraninite, hollandite-priderite, perovskite, and zirconolite. For each phase in geochemistry, occurrence, alteration and radiation effects are described. A selected bibliography for each phase is included.

  10. Immobilization of high level nuclear reactor wastes in SYNROC: a current appraisal

    International Nuclear Information System (INIS)

    Oversby, V.M.; Ringwood, A.E.

    1981-01-01

    Results are presented for leach testing at 95 0 C and 200 0 C of SYNROC containing 9% and 20% simulated high level radioactive waste, synthetic hollandite and pervoskite samples, and natural zirconolite and pervoskite samples. Single phase synthetic minerals show much higher leach rates than natural mineral samples and polyphase SYNROC samples. Natural zirconolite samples with low radiation damage have leach rates at 200 0 C based on U which are identical to those measured on SYNROC samples. Natural zirconolites with very large accumulated α dose and radiation damage have leach rates at 200 0 C which are only 5 times higher than those of low dose samples

  11. Calculated Phase Relations in the System KFMASH Between 6 and 16 GPa

    Science.gov (United States)

    Massonne, H.; Brandelik, A.

    2005-12-01

    To better understand the modal compositions of deeply buried metagranitoids and metapelites, phase relations in the model system K2O-FeO-MgO-Al2O3-SiO2-H2O (KFMASH) with SiO2 in excess were calculated applying thermodynamic principles. We used the software package PTGIBBS, published data, and thermodynamic data (e.g. for phase egg (AlSiO3OH), K-hollandite (KAlSi3O8)) newly derived on the basis of former high-pressure (HP) experiments. Non-ideal mixing was considered for the solid solution series of garnet (components: pyrope, majorite, almandine) and potassic white mica (components: muscovite, MgAl-celadonite, FeAl-celadonite). For phases such as HP-clinoenstatite ((Mg,Fe)SiO3), Si-spinel ((Fe,Mg)2SiO4), and beta phase ((Mg,Fe)2SiO4) only binary solid solutions, assuming ideal mixing, were taken into account. On the basis of the above data, we constructed petrogenetic grids mainly for the P-T range 6 to 16 GPa and 600 to 1600 ° C. Typical features of these grids are, for instance, the disappearance of K-cymrite (KAlSi3O8 H2O) with rising pressure close to 10 GPa and the occurrence of phase egg above 12 GPa. In KMASH potassic white mica reacts with OH-topaz at about 11 GPa (1000-1200 ° C) to form pyrope + K-hollandite. The content of majorite component in pyrope is less than 1 mol% which is systematically so for all garnets coexisting with an Al-silicate at least up to 16 GPa. Potassic white mica, which is virtually pure MgAl-celadonite, finally breaks down at pressures close to 12 GPa. Decomposition assemblages are K-hollandite + HP-clinoenstatite + H2O (T free) garnet + Al-silicate. The latter phase is either OH-topaz (Al2SiO4(OH)2) or phase egg or kyanite also depending on the availability of H2O. Metagranitoids should be composed of shishovite + K-hollandite + majorite-bearing garnet + (enstatite-rich) clinopyroxene. Si-spinel is an important additional phase in this assemblage. This phase shows increasing amounts by approaching to 16 GPa.

  12. Nano-Continuum Modeling of a Nuclear Glass Specimen Altered for 25 Years

    Energy Technology Data Exchange (ETDEWEB)

    Steefel, Carl

    2014-01-06

    The purpose of this contribution is to report on preliminary nano-continuum scale modeling of nuclear waste glass corrosion. The focus of the modeling is an experiment involving a French glass SON68 specimen leached for 25 years in a granitic environment. In this report, we focus on capturing the nano-scale concentration profiles. We use a high resolution continuum model with a constant grid spacing of 1 nanometer to investigate the glass corrosion mechanisms.

  13. Phase formation during corrosion experiments with two simulated borosilicate nuclear waste glasses

    International Nuclear Information System (INIS)

    Haaker, R.F.

    1985-10-01

    Corrosion products resulting from the reaction of simulated high-level radioactive waste glasses with various solutions have been identified. At 200degC, in saturated NaCl, a degree of reaction of 10 g C31-3 glass or 2.6 g SON 68 glass per liter of solution was obtained. Analcime, vermiculite (a phyllosilicate) and a 2:1 zinc silicate are the major silica containing alteration products for the C31-3 glass. Analcime was the only silicate alteration product which could be identified for SON 68 glass. C31-3 glass appeared to be less reactive with a quinary brine containing Mg ++ than with NaCl. With the quinary brine, montmorillonite (a phyllosilicate) was the predominant silica containing alteration product. Hydrotalcite (a Mg-Al hydroxysulfate) and montmorillonite were the major Al-containing phases. A phyllosilicate, probably montmorillonite, was observed to form during the reaction of SON 68 glass with quinary brine. With either glass, modified NaCl brines which contained small amounts of MgCl 2 seem to have the effect of decreasing the amount of analcime and increasing the amount of phyllosilicate which is formed. In the case of C31-3 glass, there is approximately enough Mg, Al and Zn to precipitate most of the leached Si; measured Si concentrations remain well below that expected for amorphous silica. SON 68 glass has less Zn, Al and Mg than C31-3 glass and much higher Si concentrations of the leachates. (orig./RB)

  14. The present state of research on the vitrification of concentrated solutions of fission products (1962); Etat des etudes sur la vitrification des solutions concentrees de produits de fission (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Bonniaud, R; Sombret, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    The present report gives the actual point of studies on vitrification of concentrated solutions of fission products. An active cell, giving glasses in crucibles, permitted to study various glass compositions. The leaching rate from the glass raises 1 to 2 10{sup -7} g of glass/cm{sup 2}/day. Activity loss by volatility during vitrification remains weak and often below 0.1 per cent of total activity. Off gas cleaning is made easier by presence of filter which is compound of granules including iron oxide. After saturation the content of this filter can be melt. Moreover different processes are in experimentation for a more important production. Daily 72 liters of solution containing tracer activity are treated in a continuous calcination and vitrification plant. The loss in {sup 106}Ru is still important and a modification of installation has been necessary. A pot vitrification plant is in study. In order to reduce cost of processing the possibility to pour glass after melting is actuality in study. A production set of very active glass is also in project. (authors) [French] Le present rapport fait le point des etudes menees sur la vitrification des solutions concentrees de produits de fission. Une installation active, produisant des verres en creusets, a permis d'etudier plusieurs compositions de verres. Le taux de perte d'activite par lixiviation a l'eau atteint 1 a 2 10{sup -7} gramme de verre/cm{sup 2}/jour. Les pertes d'activite par volatilite au cours de la cuisson restent faibles et souvent inferieures a 0,1 pour cent de l'activite totale. L'epuration des gaz de cuisson est facilitee par la presence d'un filtre a granules riches en oxyde de fer, dont le contenu peut etre fondu apres saturation. Differentes techniques sont, en outre, en experimentation pour une production plus importante: Une installation de calcination et vitrification continue traite 72 litres par jour de solution contenant une activite traceur. La perte en Ru{sup 106} est encore importante

  15. Characterization of Ceramic Material Produced From a Cold Crucible Induction Melter Test

    Energy Technology Data Exchange (ETDEWEB)

    Amoroso, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Marra, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-04-30

    This report summarizes the results from characterization of samples from a melt processed surrogate ceramic waste form. Completed in October of 2014, the first scaled proof of principle cold crucible induction melter (CCIM) test was conducted to process a Fe-hollandite-rich titanate ceramic for treatment of high level nuclear waste. X-ray diffraction, electron microscopy, inductively coupled plasma-atomic emission spectroscopy (and inductively coupled plasma-mass spectroscopy for Cs), and product consistency tests were used to characterize the CCIM material produced. Core samples at various radial locations from the center of the CCIM were taken. These samples were also sectioned and analyzed vertically. Together, the various samples were intended to provide an indication of the homogeneity throughout the CCIM with respect to phase assemblage, chemical composition, and chemical durability. Characterization analyses confirmed that a crystalline ceramic with desirable phase assemblage was produced from a melt using a CCIM. Hollandite and zirconolite were identified in addition to possible highly-substituted pyrochlore and perovskite. Minor phases rich in Fe, Al, or Cs were also identified. Remarkably only minor differences were observed vertically or radially in the CCIM material with respect to chemical composition, phase assemblage, and durability. This recent CCIM test and the resulting characterization in conjunction with demonstrated compositional improvements support continuation of CCIM testing with an improved feed composition and improved melter system.

  16. Driving Curie temperature towards room temperature in the half-metallic ferromagnet K2Cr8O16 by soft redox chemistry.

    Science.gov (United States)

    Pirrotta, I; Fernández-Sanjulián, J; Moran, E; Alario-Franco, M A; Gonzalo, E; Kuhn, A; García-Alvarado, F

    2012-02-14

    The half-metallic ferromagnet K(2)Cr(8)O(16) with the hollandite structure has been chemically modified using soft chemistry methods to increase the average oxidation state of chromium. The synthesis of the parent material has been performed under high pressure/high temperature conditions. Following this, different redox reactions have been carried out on K(2)Cr(8)O(16). Oxidation to obtain potassium-de-inserted derivatives, K(2-x)Cr(8)O(16) (0 ≤x≤ 1), has been investigated with electrochemical methods, while the synthesis of sizeable amounts was achieved chemically by using nitrosonium tetrafluoroborate as a highly oxidizing agent. The maximum amount of extracted K ions corresponds to x = 0.8. Upon oxidation the hollandite structure is maintained and the products keep high crystallinity. The de-insertion of potassium changes the Cr(3+)/Cr(4+) ratio, and therefore the magnetic properties. Interestingly, the Curie temperature increases from ca. 175 K to 250 K, getting therefore closer to room temperature.

  17. Thermodynamic stability and kinetic dissolution of perovskite in natural waters

    International Nuclear Information System (INIS)

    Nesbitt, H.W.; Bancroft, G.M.; Fyfe, W.S.; Karkhanis, S.; Melling, P.; Nishijima, A.

    1981-01-01

    Ringwood and coworkers have recently proposed using titanates and zirconates as hosts for nuclear waste in the Synroc B process. Three minerals are used as hosts: perovskite (CaTiO 3 ), Ba-hollandite (BaAl 2 Ti 6 O 16 ), and zirconolite (CaZrTi 2 O 7 ). The Synroc philosophy relies heavily on geological and geochemical observations in selecting stable host minerals. Although it has been recognized that the Synroc minerals are not thermodynamically compatible with siliceous rocks, the minerals are considered to be thermodynamically stable in the presence of water, and it has been reported that these minerals are kinetically stable under high-temperature (up to 900 0 C) hydrothermal conditions. Detailed thermodynamic calculations and leach tests have been performed which demonstrate: first, that perovskite is thermodynamically unstable in all known natural waters; and second, that pervoskite leaches at a significant rate even at 100 0 C. Hydrothermal leach tests have been made on natural and synthetic perovskite and perovskite analogues between 100 0 C and 300 0 C. Weight losses and solution concentrations were monitored. The results reported previously in the literature also show that perovskite is kinetically unstable in the presence of common silicates. Our results show that perovskite may be no more stable than siliceous glasses, such as rhyolite, which have been studied previously. Geologic evidence from common alkaline rocks also indicates that hollandite and zirconolite probably will not survive in common rock matrices

  18. Crystal chemistry of six-coordinated silicon: A key to understanding the earth's deep interior

    International Nuclear Information System (INIS)

    Finger, L.W.; Hazen, R.M.

    1991-01-01

    A survey of high-pressure silicates reveals 12 distinct high-density structural topologies with octahedral Si. Seven of these structure types - stishovite, perovskite, ilmenite, hollandite, calcium ferrite, pyrochlore and K 2 NiF 4 type - contain only six-corrdinated silicon. Other high-pressure silicates, including those with the garnet, pyroxene, wadeite, anhydrous phase B and phase B structures, contain both tetrahedral and octahedral Si. Five systematic trends among these dozen structures suggest the existence of other, as yet unobserved, possible mantle Si phases. The criteria are: (1) Structures like rutile, hollandite and calcium ferrite formed from edge-sharing chains of silicon octahedra; (2) germanates synthesized at room pressure with octahedral Ge; (3) isomorphs of room-pressure oxides with 3+ or 4+ transition-metal cations; (4) high-pressure magnesium silicates related to room-pressure aluminates by the substitution 2Al→Mg+Si; and (5) the homologous structures in system Mg-Si-O-H that includes phase B and anhydrous phase B. Each of these criteria can be used to predict other potential octahedral Si phases. Of special interest are predicted structure types that fulfill more than one criterion: Diaspore-type (MgSi)O 2 (OH) 2 , aerugite-type Mg 10 Si 3 O 16 , sphene-type CaSi 2 O 5 , benitoite-type BaSi 4 O 9 , gibbsite-type MgSi(OH) 6 and pseudobrookite-type Fe 2 SiO 5 . (orig.)

  19. DEVELOPMENT OF CRYSTALLINE CERAMICS FOR IMMOBILIZATION OF ADVANCED FUEL CYCLE REPROCESSING WASTES

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K.; Brinkman, K.

    2011-09-22

    The Savannah River National Laboratory (SRNL) is developing crystalline ceramic waste forms to incorporate CS/LN/TM high Mo waste streams consisting of perovskite, hollandite, pyrochlore, zirconolite, and powellite phase assemblages. Simple raw materials, including Al{sub 2}O{sub 3}, CaO, and TiO{sub 2} were combined with simulated waste components to produce multiphase crystalline ceramics. Fiscal Year 2011 (FY11) activities included (i) expanding the compositional range by varying waste loading and fabrication of compositions rich in TiO{sub 2}, (ii) exploring the processing parameters of ceramics produced by the melt and crystallize process, (iii) synthesis and characterization of select individual phases of powellite and hollandite that are the target hosts for radionuclides of Mo, Cs, and Rb, and (iv) evaluating the durability and radiation stability of single and multi-phase ceramic waste forms. Two fabrication methods, including melting and crystallizing, and pressing and sintering, were used with the intent of studying phase evolution under various sintering conditions. An analysis of the XRD and SEM/EDS results indicates that the targeted crystalline phases of the FY11 compositions consisting of pyrochlore, perovskite, hollandite, zirconolite, and powellite were formed by both press and sinter and melt and crystallize processing methods. An evaluation of crystalline phase formation versus melt processing conditions revealed that hollandite, perovskite, zirconolite, and residual TiO{sub 2} phases formed regardless of cooling rate, demonstrating the robust nature of this process for crystalline phase development. The multiphase ceramic composition CSLNTM-06 demonstrated good resistance to proton beam irradiation. Electron irradiation studies on the single phase CaMoO{sub 4} (a component of the multiphase waste form) suggested that this material exhibits stability to 1000 years at anticipated self-irradiation doses (2 x 10{sup 10}-2 x 10{sup 11} Gy), but that

  20. Deep Recycling of Sedimentary Lithologies in Subduction Zones: Geochemical and Physical Constraints from Phase Equilibria and Synchrotron-Based Multi-Anvil Experiments at 15-25 GPa

    Science.gov (United States)

    Rapp, R. P.; Nishiyama, N.; Irifune, T.; Inoue, T.; Yamasaki, D.

    2003-12-01

    Ocean island basalts (OIBs) provide geochemical evidence for the presence of crustally-derived sedimentary material in the deep mantle plume source region for EM-type OIBs, and global seismic tomography provides us with dramatic images of subducted slabs, presumably carrying a sediment component, penetrating through the transition zone and into the lower mantle, in some cases to the core-mantle boundary. In an effort to better constrain the geochemical effects of deeply recycled sedimentary material in subduction zones, and their role in the petrogenesis of EM-type OIBs, we have undertaken a series of phase equlibria experiments in the multi-anvil apparatus at 10-25 GPa, using natural sediment lithologies as starting materials. The goal of these experiments is to identify the dominant phases in deeply subducted sediments, constrain their P-T stability limits, and to assess their role in crustal recycling and element redistribution in the deep mantle during subduction. The phase equilibria experiments were performed in a 2000-ton Kawai-type apparatus, using tungsten carbide cubes with 3 mm TEL and Cr-doped MgO and zirconia pressure media. A cylindrical lanthanum chromite heater was used, along with short (gold capsules to minimize thermal gradients and to retain the small amounts of water (< 1 wt%) present in the starting material, and long run-durations (12-48 hours) in order to facilitate future analyses of the dominant phases for key trace elements using the ion microprobe. Our preliminary results at 10-25 GPa indicate that K-hollandite (KalSi3O3) and stishovite are the primary high-pressure phases in the sediment composition, with subordinate garnet and an as-yet-unidentified (possibly hydrous) Al-silicate phase present as well. These results suggest that K-hollandite is the primary repository for incompatible elements (e.g., La, Ce, Sr, Ba, Rb, etc., and the heat-producing elements K, U and Th) in sedimentary material recycled into the deep mantle via

  1. El vidrio en la construcción. Situación actual y orientación de la l+D

    Directory of Open Access Journals (Sweden)

    Coto, José Antonio

    1991-03-01

    Full Text Available Not available.

    El vidrio, bajo sus diferentes formas y composiciones, constituye uno de los materiales más utilizados en la construcción. Desempeña múltiples funciones: Estética, Confort, Seguridad,... Aunque se trata de un material muy antiguo, gracias al esfuerzo de l+D, está teniendo una importante evolución durante estos últimos años. Se desarrollan nuevas propiedades y funciones mediante modificaciones en su composición, tratamientos de su superficie o asociación con otros productos. Se recoge, en esta comunicación, un extenso número de nuevos productos y sus procedimientos de obtención, destacando su aplicación y funcionalidad en la construcción. Se da cierta extensión a los diferentes tratamientos de superficie (principalmente, capas delgadas sobre vidrio plano, por su especial implantación en la construcción actual. Igualmente, se describen los productos compuestos y sus utilizaciones más funcionales. Los vidrios con propiedades variables a voluntad son objeto de múltiples desarrollos actuales y, sin duda, serán de gran aplicación en la construcción en un futuro próximo. Se termina esta comunicación con una referencia, necesariamente breve, a los vidrios estructurales y las diferentes fibras de vidrio (tanto de aislamiento térmico y acústico, como de refuerzo, también de gran interés y difusión en la construcción. [fr] Le verre dans la construction. Situation actuelle et orientation de la R+D. Le verre, sous des formes et compositions différentes, représente un matériau très utilisé dans le bâtiment. Ses fonctions sont multiples: Esthétique, Confort, Sécurité, ... Bien qu'il s'agit d'un matériau très ancien, grâce a l'effort de R+D, son évolution pendant les dernières années a été très importante. On a développé de nouvelles propriétés et fonctions en modifiant la composition, les traitements de surface ou l'association avec d'autres produits. Dans cette

  2. LA LINGUA FILMATA: "L'UOMO CHE VERRÀ" DI GIORGIO DIRITTI

    Directory of Open Access Journals (Sweden)

    Marta Idini

    2016-02-01

    Full Text Available La lingua filmata appare oggi uno dei campi linguistici in cui il dialetto torna ad essere scelta registica e veicolo di nuove istanze comunicative, in stretta relazione con un nuovo modo di intendere e praticare il cinema. Il presente articolo introduce il lettore alla consuetudine cinematografica del dialetto, analizzandone la presenza e le funzioni che gli sono state attribuite nei decenni trascorsi e presenti, e guarda a L’Uomo che verrà quale espressione attuale di una nuova risorgenza dialettale all’interno delle pellicole nostrane. Attraverso un’analisi attenta dei fenomeni vernacolari in esso presenti, l’indagine si sofferma sulle motivazioni e l’efficacia comunicativa cui perviene l’uso del dialetto e si interroga su quale grado di realismo o mimesi linguistica Diritti abbia raggiunto. Language of film: "L’uomo che verrà" by Giorgio DirittiLanguage in films is one of the fields where dialect becomes a choice and a vehicle for new communicative demands, closely related the new way of understanding and practicing the cinema. This article introduces the reader to the use of dialect in films, analyzing the presence and functions that have been attributed to it in the past and present decades, and looks at L’Uomo che verrà as an expression of the new resurgence of dialect in Italian films. Through careful analysis of the vernacular, the paper focuses on the motivations and the communicative effectiveness of the use of dialect and questions the degree of realism or linguistic mimesis that Diritti was able to reach.

  3. Çocukluk Çağında Anogenıtal Verru ve Cinsel İstismar

    Directory of Open Access Journals (Sweden)

    Dua Sumeyra Demirkıran

    2014-04-01

    Full Text Available Çocuklarda anogenital bölgede cinsel yolla bulaşan hastalıkların varlığı cinsel istismarın delilidir. Human papilloma virüs (HPV yetişkinlerin %80 ini etkileyen, en sık görülen cinsel yolla geçen hastalık kabul edilmektedir. Bu virüsün oluşturduğu verrülerin çocuklarda görülmesi cinsel istismar kanısı oluşturmaktadır. Çalışmamızda anogonital verrü (AGV ile ilgili literatür derlemesi yaparak AGV'li çocuk olgularına adli tıp yönünden yaklaşım önerilerini sunmayı amaçladık. Yapılan çalışmalara göre HPV'nin cinsel istismar dışında farklı bulaş yollarının olduğu bilimsel olarak saptanmıştır. Bu nedenle AGV'li çocuklara yaklaşımda cinsel istismar ön yargısının kırılması gerektiği kanaati oluşmuştur. Çocukların ve ailelerin "cinsel istismar" psikolojisinden uzak tutulmalıdır. Bu olgulara multidisipliner yaklaşılarak bulaş yolu hakkında kanaat oluştuktan sonra adli olgu açısından değerlendirilmelidir. Anahtar kelimeler: anogenital verrü, bulaş yolları, cinsel istismar

  4. Data for Design of Entrance Vanes from Two-Dimensional Tests of Airfoils in Cascade

    Science.gov (United States)

    1945-10-01

    le between the initial air and the chord line of the blower blade deslph angle of attack...34t le ’Je a;: .r.nr .1 rjrnel o ptrr ti.e so nt: v, :" 1 ^ ** •jrther r -. 1 ay r-’sd a ft bet d the -ch- it lidity. If «itb For...j-.ir "haper (.•".f. •.’•) verr . -«-lasted ar KüR lines for -.ilsc’os L"r< j"vtr a •ar-..-’-- ;.-f t’^n’ur* tr.;’ls fi-op;

  5. Integrated Information Support System (IISS). Volume 5. Common Data Model Subsystem. Part 6. NDDL Processor Product Specification. Section 3.10.9 through 4.2.

    Science.gov (United States)

    1985-11-01

    132 M1 .2 * 125 ŕ.4 1.6 MICROCOPY RESOLUTION TEST CHART NATKIOAt BUREAU OF STANDARDS 1963-A - -W -o - 4w " " " lE FILE CUBe -. a II j AFVAL-TR-66...a 12- ----- le ------- 37+ - -----21+ - -----90+ 3-1176 I*LL A -A S * - S PS 620141100 1 November 1985 61 ICPYDES I I I I I I... VERRELI I +---+--- 4---+---- ----- f---, IVERENTI IUERRORI IVERRCI +----- 14+ --... 3+ +--+--+ I I I ft--ft---+ I ERRPRO I 3-1196 !V PS 620141100 1

  6. Computer-Based Methods for Thermodynamic Analysis of Materials Processing.

    Science.gov (United States)

    1983-11-30

    systems and the Cd- le -I1’ ternary systems at pressures up to 74 atmospheres. Comparison of the calcislaled results with experimental data on tie-line...of BF, J=Stable form of LE , C-Stable form of PF * NFNFLS -(t/2)NaF(Liquid)-(1/2)NaF(S, sodium chloride) ZFZFLH-12845-IO.669T KFKFt.S-14 121-12.468T...page 302. 9. A. Lecoq and M. Poulain, Verres Refract. 34 333 (1980). .9 -151- .,. ... ,.-.. -. ,.* . -.-. ..- ,,- . ’-.. ...- ’’.. - --. . --. ’--. . .--A.:,,.’ " " :’ ’.." .<

  7. ELABORATION ET ETUDE DES MATERIAUX CHALCOPYRITES AIBIIIC2 IV : LE DISELINURE DE CUIVRE ET D’INDIUM

    Directory of Open Access Journals (Sweden)

    S MEHDAOUI

    2007-06-01

    par évaporation sur des substrats en verre présentent des coefficients d’absorption ( élevées de l’ordre de 5.104 cm-1. Le tracé de la fonction (h2 des couches minces recuites sous vide à différentes températures en fonction de l’énergie des photons incident a mis en relief la nature directe de la transition fondamentale est a permis également de calculer le gap Eg = 1.04 eV.

  8. A Mixed-Integer Linear Programming Problem which is Efficiently Solvable.

    Science.gov (United States)

    1987-10-01

    ger prongramn rg versions or the problem is not ac’hievable in genieral for sparse inistancves of’ P rolem(r Mi. Th le remrai nder or thris paper is...rClazes c:oIh edge (i,I*) by comlpli urg +- rnirr(z 3, ,x + a,j). A sirnI) le analysis (11 vto Nei [131 indicates why whe Iellinan-Ford algorithm works...ari cl(cck to iceat reguilar rnct’vtuls. For c’xamiic, oi1cc Wwitiil pcroccc’ssicg svlstcici1 rccjcilrcc thicit I iisc wires ice repeated verr 200W

  9. Les traces matérielles de la Carte du Ciel. Le cas des observatoires d'Alger et de Bordeaux.

    Science.gov (United States)

    Le Guet Tully, F.; Davoigneau, J.; Lamy, J.; de La Noë, J.; Rousseau, J.-M.; Sadsaoud, H.

    2008-06-01

    Le chapitre évoque les traces matérielles de la Carte du ciel subsistant dans les observatoires d'Alger et de Bordeaux. Les auteurs examinent d'abord l'opération d'inventaire du patrimoine astronomique entreprise à partir du milieu des années 1990. Ils examinent ensuite les éléments concrets constituant aujourd'hui le patrimoine de la Carte du Ciel : lunettes, abris, accessoires, laboratoires, réseaux, plaques de verre, registres, machines à mesurer les clichés, et cartes.

  10. Tracer sa route, en toute intransparence numérique ?

    Directory of Open Access Journals (Sweden)

    Philippe Vidal

    2015-12-01

    Full Text Available « Comme l’intransparence des vitres ferait tache dans une habitation et l’attristerait en obstruant le passage du regard, on a dû chercher au moyen de voir au travers sans être vu, et l’on a inventé le verre mousseline. » L’expression « tracer sa route » est souvent utilisée dans un sens familier. Elle signifie, ordinairement, partir à l’aventure, sans se soucier des éventuelles contraintes et conséquences d’un tel choix, qu’elles soient sociales, matérielles ou familiales. A l’image des trav...

  11. L'ordre du chaos

    CERN Document Server

    1989-01-01

    Le mouvement brownien ; la mémoire des atomes ; le chaos ; déterminisme et prédictabilité ; déterminisme et chaos ; les phénomènes de physique et les échelles de longueur ; un ordre caché dans la matière désordonnée ; les verres de spin et l'étude des milieux désordonnés ; la convection ; la croissance fractale ; la physique de la matière hétérogène ; la matière ultradivisée.

  12. PH measurement under pressure and at high temperatures; Mesure du pH sous pression et a temperature elevee

    Energy Technology Data Exchange (ETDEWEB)

    Fournie, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Le Peintre, M; Mahieu, C [Centre National de la Recherche Scientifique (CNRS), 91 - Gif-sur-Yvette (France)

    1961-07-01

    In the first part the development and operation of a glass electrode under pressure at room temperature is described. The pressure equilibrium between the inside and outside of the glass membrane several centimetres thick is obtained instantaneously by means of a siphon. The use of a silicone oil as electrical insulator makes possible the working of the glass electrode with the siphon at high pressures (100 kg/cm{sup 2}). In the second part, we determined the pH of various buffer solutions up to 250 deg. C using a cell of our design having two hydrogen electrodes. The values thus obtained for the buffer solutions make it possible to verify and calibrate the pH electrodes independently of the oxido-reduction potential of the medium. In the third part we give the results obtained up to 200 deg. C with the glass electrodes developed in conjunction with the Societe St Gobain. (author) [French] Dans une premiere partie, nous exposons la mise au point et le fonctionnement d'une electrode en verre sous pression a la temperature ordinaire. L'equilibrage instantane de la pression a l'interieur et a l'exterieur de la membrane en verre de quelques diziemes de millimetres d'epaisseur s'effectue par l'intermediaire d'un siphon. L'emploi d'une huile de silicone comme isolant electrique a permis le fonctionnement de l'electrode en verre a siphon sous haute pression (1000 kg/cm{sup 2}). Dans une deuxieme partie, nous avons determine jusqu'a 250 deg. C les valeurs du pH des diverses solutions tampons avec une cellule de notre conception a deux electrodes d'hydrogene. Les valeurs des solutions tampons ainsi obtenues permettent de verifier et d'etalonner les electrodes a pH independantes du potentiel d'oxydo-reduction du milieu. Dans une troisieme partie, nous relatons les resultats obtenus jusqu'a 200 deg. C avec les electrodes en verre mis au point en collaboration avec la Societe Saint-Gobain. (auteur)

  13. Procédé de l'étude de la rupture des fibres à partir d'un essai en ...

    African Journals Online (AJOL)

    Le travail consiste à solliciter en traction des mèches de fibres de verre, en utilisant l'émission acoustique pour suivre en temps réel l'endommagement du matériau. En effet, les ... Deux types d'essais doivent être réalisés, ceci afin de pouvoir comparer les méthodes et les résultats avec ceux déjà obtenus. La procédure ...

  14. 2193-IJBCS-Article - Diouf Ceress

    African Journals Online (AJOL)

    admin

    Pour trouver des alternatifs aux insecticides de synthèse, les extraits de plantes sont de plus en plus utilisés par les paysans pour protéger les stocks .... présents dans chaque extrait, plusieurs types de réactifs et témoins ont été utilisés. ... sont lancés dans des bocaux en verre de 500. mL de volume environ. A l'intérieur de.

  15. Meteoritics, Number 19

    Science.gov (United States)

    1964-06-01

    266, 1958. 131. Houziaux, L., Spectres d’absorption infra-rouge de quelques verres naturels entr 2 et 24 microns (Infrared Absorption Spectra of...Taking Pb20L’ 1), Given as a Function of Time. reteorites was made in a work by M. M. Shats (Ref. 10). M. M. Shats de - termined the uranium and lead...billion years. Table 6. Age, l09 Type of Data of Published Meteorite Years Meteorite Source, Investi- gator Kashin 3.00 Chondrite 1951 (Ref. 14), E.K

  16. U.S. Navy Marine Climatic Atlas of the World. Volume IX. World-Wide Means and Standard Deviations

    Science.gov (United States)

    1981-10-01

    TITLE (..d SobtII,) S. TYPE OF REPORT & PERIOD COVERED U. S. Navy Marine Climatic Atlas of the World Volume IX World-wide Means and Standard Reference...Ives the best estimate of the population standard deviations. The means, , are com~nuted from: EX IIN I 90 80 70 60" 50’ 40, 30 20 10 0 1070 T- VErr ...or 10%, whichever is greater Since the mean ice limit approximates the minus two de l temperature isopleth, this analyzed lower limit was Wave Heights

  17. An Investigation of the Lateral-Control Characteristics of Spoilers on a High-Aspect-Ratio Wing of NACA 65-210 Section in the Langley 8-Foot High-Speed Tunnel

    Science.gov (United States)

    1947-06-24

    sgoilers retain a lwge de @’ee of control s;t high s ~ e b . (referenceu .8 and 9) and produce lesa wing t w i s t thm cmventiond. dIei*om of equ...were included in the tests. {fig. 3) - Tbe Span Of 8poiGP 8" a.6 that of the The d l e r o n wae of the plain type with no aerodynamic nose...corrections =re verr e m l l aad mounted to a m x i m of about 1 percent a t a bhch nuiber of 0 -91 as determined from calculations using the

  18. A Strategic Approach to the Maritime-Continental Strategy Debate

    Science.gov (United States)

    1987-02-01

    TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE A Strategic Approach to the Maritime-Continental Strategy Debate 5a. CONTRACT NUMBER 5b...cesses, and ’the study ,’-,f strategi,- the,:,ry alqd histc, ry. Itl additi,:,n to his civilian gc, verr ~r,~ent expc.ri .... ence, his rrlilitary...is esset~- tial. The ,-,perati,-,nal purp,-,se ,_-,f that ,-ar~ipaig~; should n,-,t be the quix,-rti,- de ,- l ar at ,z, ry ob.je,ztive of de

  19. Chemical Durability Improvement and Static Fatigue of Glasses.

    Science.gov (United States)

    1982-05-01

    Ss’n- 5cr.. Glassm. Union Scientifie. Contmentale de Verre , Belgium. 1962. 63 741 25 (1967). ’E. Orowan. "Fatigueueof Glas, Under Stress." Natre...PAGE 33703 CSILETmuE FORM . REPORT NUMER A2. DOV ACCRSION NOM S RECIPIENT’S CATALOG NUMER 4. TITLE (and sub.e.a S. TYPE OF REPORT 6 PERIOD COVERED...and J. S. Olcott, "Strengthening by Ion Exchange," J. this type of ion exchange is unlikely since Am. Ceram. Soc., 47 151 215-19 (1964). the alkali

  20. Mid-Infrared Fiber Lasers (Les fibres laser infrarouge moyen)

    Science.gov (United States)

    2010-09-01

    Marcel Poulain, Université de Rennes / Le Verre Fluoré, France Fluoride Fiber Sources: Problems and Prospects Prof. Marcel Poulain from Rennes...currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 3. DATES...Les fibres laser infrarouge moyen (RTO-MP-SET-171) Synthèse Les sources laser en infrarouge moyen sont nécessaires aux systèmes actifs de

  1. Improved Maneuver Criteria Evaluation Program

    Science.gov (United States)

    1979-11-01

    If the rotor rpm breakpoint (OMGBL2) is le :-s than the mininum rotor rpm (OMEGMN), then the rpm bleed :ate (OMGBDI) will be the only bleed rate used...VCP =60 PSU 1 EEF = 1 OMGBD1=2 OMGBD3=0 OMGRC2=0 VERR = 2 MPRINT= 1 OMEGMN=300 OMGBL.2=4 OMGBL4=0 OMGRD2=0 MUF = 1 BINERT:2860 TRPMMN= 0 OMGBD2=0 OMGBD4...height is within 2 feet of the measured height. These comparisons show that the MCEP maneuvers are accurate for simulating these types of maneuvers

  2. A Review of Navy Stock Fund Accounting Practices for Procurements from Commercial Sources.

    Science.gov (United States)

    1987-06-01

    ssues as a hole, t here appears 4o be One s ’ le ci s" 4 A i m nI t Y - - I eveI -) lote’ . I t Aproars S ~t V.jf0A tfh’ ierefore becomes tPh. -) verr I FQ...such industrial type activities, and for such commercial type activities as provide common services within or among the departments and agencies of...will be discussed in detail later on in the next chapter. 28 The "accounting system" of the NSF must perform different types of accounting based upon

  3. Carcinoma verrucoso plantar. A propósito de un caso poco frecuente

    OpenAIRE

    López López, Daniel; Rodríguez Sanz, David; Morales Ponce, Ángel; Soriano Medrano, Alfredo

    2013-01-01

    Antecedentes: Los carcinomas verrucosos en pocas ocasiones se mencionan en la literatura su localización en la planta de los pies, siendo una variante bien diferenciada del carcinoma de células escamosas visto en mucosa y piel, incluyendo los pies. Objetivo: Describir las características clínicas, histopatológicas y de laboratorio y los resultados de un caso clínico inusual de un carcinoma verrucoso en la planta del pie. Métodos: Presentamos un extraño caso de un carcinoma verr...

  4. Protective pneumothorax in CT monitored mediastinal puncture

    International Nuclear Information System (INIS)

    Wein, B.B.; Dickgreber, N.J.; Guenther, R.W.

    1997-01-01

    Purpose: To achieve an extrapulmonary pathway for biopsy of mediastinal masses. Methods: In 6 patients a protective, temporary pneumothorax was established before performing large-bore needle biopsies of mediastinal masses using a Verres-needle. Results: Transpleural, extrapulmonary access was easy to achieve. One patient developed a tension pneumothorax after biopsy which was drained by percutaneous small chest tube. Another patient showed mediastinal tumour bleeding through the biopsy needle. As a prophylactic measure the bleeding was stopped by injection of tissue glue through the biopsy needle. Conclusion: The use of protective pneumothorax allows cutting needle biopsies of mediastinal masses where aspiration cytology yields no secure specific diagnosis. (orig.) [de

  5. Produktiwiteit en verantwoordelikheid, enkele sielkundige aspekte

    Directory of Open Access Journals (Sweden)

    A. P. Venter

    1978-11-01

    Maslow se motiveringsteorie wat uit die kliniese sielkunde ontspruit het, is ook deur bedryfsielkundiges van nader beskou, veral in hoe verre dit met produktiwiteit verband het. Enkele sielkundige aspekte word bespreek ten einde op die nut van hierdie teorie in die bedryfsituasie te wys. Die vermoede bestaan dat die teorie deur bedryfsielkundiges nie altyd korrek vertolk word soos Maslow dit self uiteensit nie; veral word die verantwoordelikheidsaspek in die selfuitlewingsbehoeftes misken en nie verreken nie; 'n Logiese konklusie is dat selfuitlewing, soos deur Maslow beskryf, wel verband met produktiwiteit het.

  6. Déchets solides encombrants les plages d'Annaba | Chaouch ...

    African Journals Online (AJOL)

    Nos résultats montrent que les verres et les métaux viennent en 1ère position avec respectivement 32,84% et 32,53 % puis on a les plastiques avec 14,17%, les bois et dérivés 13,88 %, les diverses structures en papier avec 3,32% et enfin les textiles avec 3,26%. La plage Ain-Achir est la plus polluée avec 10,59 Kg/m2 de ...

  7. Comportement à la corrosion intrinsèque de couches minces à base ...

    African Journals Online (AJOL)

    Mo, le Mg et les Terres rares Y et Gd. Le réacteur de pulvérisation ... dépôts réalisés sur substrat en verre servent pour la caractérisation de leur .... en Terres rares. Ceci pourrait s'expliquer par la différence de rayon atomique entre ces deux terres rares et celui de l'Al pur. (rY = 0,177 nm, rGd = 0,178 nm et. rAl = 0,143 nm).

  8. Studies on the long-term characteristics of HLW glass under ultimate storage conditions

    International Nuclear Information System (INIS)

    Roggendorf, H.; Conradt, R.; Ostertag, R.

    1987-01-01

    This interim report deals with first results of corrosion investigations of HLW simulation glass (COGEMA glass SON 68) in quinary salt solutions of different concentrations; the aim of these investigations was to find out about the corrosion mechanism at the surface of the glass and the quantitative registration of the corrosion products. It became obvious that the surface layers developed can be easily removed and that a determination of weight losses becomes possible thereby. The corrosion rates for a test period of 30 days were determined. (RB) [de

  9. Deactivation of SCR catalysts by potassium: A study of potential alkali barrier materials

    DEFF Research Database (Denmark)

    Olsen, Brian Kjærgaard; Kügler, Frauke; Castellino, Francesco

    2017-01-01

    The use of coatings in order to protect vanadia based SCR catalysts against potassium poisoning has been studied by lab- and pilot-scale experiments. Three-layer pellets, consisting of a layer ofa potential coating material situated between layers of fresh and potassium poisoned SCR catalyst, were...... the coating process. Potassium had to some extent penetrated the MgO coat, and SEM analysis revealed it to be rather thick and fragile. Despite these observations, the coating did protect the SCR catalyst against potassium poisoning to some degree, leaving promise of further optimization....... used to test the ability of the barrier layer to block the diffusion of potassium across the pellet. Of MgO, sepiolite and Hollandite manganese oxide, MgO was the most effective potassium barrier, and no potassium was detected in the MgO layer upon exposure to SCR conditions for 7 days. Two monoliths...

  10. Continuous-flow leaching studies of crushed and cored SYNROC

    International Nuclear Information System (INIS)

    Coles, D.G.; Bazan, F.

    1980-01-01

    Both crushed (150 to 300 μm) and cored 1.8 mm diameter) samples of SYNROC have been leached with the single-pass continuous-flow leaching equipment. Crushed samples of Cs-hollandite were also leached in a similar experiment. Temperatures used were 25 0 C and 75 0 C and leachates were 0.03 N NaHCO 3 and distilled water. Leaching rates from SYNROC C were ranked Cs > Sr greater than or equal to Ca > Ba > Zr. A comparison of leaching rates is made between crushed SYNROC, cored SYNROC, and PNL 76-68 glass beads. Problems encountered when comparing the leaching rates of different waste forms are discussed

  11. MnO2/MCMB electrocatalyst for all solid-state alkaline zinc-air cells

    International Nuclear Information System (INIS)

    Zhang, G.Q.; Zhang, X.G.

    2004-01-01

    Nanostructured MnO 2 /mesocarbon microbeads (MCMB) composite has been prepared successfully for use in zinc-air cell as electrocatalyst for oxygen reaction. The scanning electron microscope (SEM) images showed that the MnO 2 nanorods were formed and covered on the surface of MCMB in bird's nest morphology. X-ray diffraction (XRD) pattern indicated that the MnO 2 has the hollandite structure with a composition approximating KMn 8 O 16 . By the cathodic polarization curve tests, the nanostructured material demonstrated excellent electrocatalytic activity as a kind of oxygen electrode electrocatalyst compared with electrolytic MnO 2 . An all solid-state zinc-air cell has been fabricated with this material as electrocatalyst for oxygen electrode and potassium salt of cross-linked poly(acrylic acid) as an alkaline polymer gel electrolyte. The cell has good discharge characteristics at room temperature

  12. Cold crucible induction melter test for crystalline ceramic waste form fabrication: A feasibility assessment

    Energy Technology Data Exchange (ETDEWEB)

    Amoroso, Jake W., E-mail: jake.amoroso@srnl.doe.gov [Savannah River National Laboratory, Aiken, SC 29808 (United States); Marra, James; Dandeneau, Christopher S. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Brinkman, Kyle; Xu, Yun [Clemson University, Clemson, SC 29634 (United States); Tang, Ming [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Maio, Vince [Idaho National Laboratory, Idaho Falls, ID 83415 (United States); Webb, Samuel M. [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94086 (United States); Chiu, Wilson K.S. [University of Connecticut, Storrs, Connecticut 06269-3139 (United States)

    2017-04-01

    The first scaled proof-of-principle cold crucible induction melter (CCIM) test to process a multiphase ceramic waste form from a simulated combined (Cs/Sr, lanthanide and transition metal fission products) commercial used nuclear fuel waste stream was recently conducted in the United States. X-ray diffraction, 2-D X-ray absorption near edge structure (XANES), electron microscopy, inductively coupled plasma-atomic emission spectroscopy (and inductively coupled plasma-mass spectroscopy for Cs), and product consistency tests were used to characterize the fabricated CCIM material. Characterization analyses confirmed that a crystalline ceramic with a desirable phase assemblage was produced from a melt using a CCIM. Primary hollandite, pyrochlore/zirconolite, and perovskite phases were identified in addition to minor phases rich in Fe, Al, or Cs. The material produced in the CCIM was chemically homogeneous and displayed a uniform phase assemblage with acceptable aqueous chemical durability.

  13. Alternative High-Performance Ceramic Waste Forms

    Energy Technology Data Exchange (ETDEWEB)

    Sundaram, S. K. [Alfred Univ., NY (United States)

    2017-02-01

    This final report (M5NU-12-NY-AU # 0202-0410) summarizes the results of the project titled “Alternative High-Performance Ceramic Waste Forms,” funded in FY12 by the Nuclear Energy University Program (NEUP Project # 12-3809) being led by Alfred University in collaboration with Savannah River National Laboratory (SRNL). The overall focus of the project is to advance fundamental understanding of crystalline ceramic waste forms and to demonstrate their viability as alternative waste forms to borosilicate glasses. We processed single- and multiphase hollandite waste forms based on simulated waste streams compositions provided by SRNL based on the advanced fuel cycle initiative (AFCI) aqueous separation process developed in the Fuel Cycle Research and Development (FCR&D). For multiphase simulated waste forms, oxide and carbonate precursors were mixed together via ball milling with deionized water using zirconia media in a polyethylene jar for 2 h. The slurry was dried overnight and then separated from the media. The blended powders were then subjected to melting or spark plasma sintering (SPS) processes. Microstructural evolution and phase assemblages of these samples were studied using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion analysis of x-rays (EDAX), wavelength dispersive spectrometry (WDS), transmission electron spectroscopy (TEM), selective area x-ray diffraction (SAXD), and electron backscatter diffraction (EBSD). These results showed that the processing methods have significant effect on the microstructure and thus the performance of these waste forms. The Ce substitution into zirconolite and pyrochlore materials was investigated using a combination of experimental (in situ XRD and x-ray absorption near edge structure (XANES)) and modeling techniques to study these single phases independently. In zirconolite materials, a transition from the 2M to the 4M polymorph was observed with increasing Ce content. The resulting

  14. Solution chemistry techniques in SYNROC preparation

    International Nuclear Information System (INIS)

    Dosch, R.G.; Lynch, A.W.

    1981-07-01

    Investigations of titanate-based ceramic forms for radioactive waste immobilization are underway at Sandia National Laboratories (SNLA) and at Lawrence Livermore National Laboratory (LLNL). Although the waste forms differ as to overall product composition, the waste-containing phases in both ceramic products have similar crystalline structure types. These include metallic phases along with oxides with structure types of the mineral analogues perovskite, zirconolite, and hollandite. Significant differences also exist in the area of processing. More conventional ceramic processing methods are used at LLNL to produce SYNROC while solution chemistry techniques involving metal alkoxide chemistry and ion exchange have been developed at SNLA to prepare calcium titanate-based waste ceramics. The SNLA techniques were recently modified and applied to producing SYNROC (compositions C and D) as part of an interlaboratory information exchange between SNLA and LLNL. This report describes the methods used in preparing SYNROC including the solution interaction, and hot-pressing methods used to obtain fully dense SYNROC monoliths

  15. Subduction recycling of continental sediments and the origin of geochemically enriched reservoirs in the deep mantle

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, R.P.; Irifune, T.; Shimizu, N.; Nishiyama, N.; Norman, M.D.; Inoue, T. (Ehime U); (WHOI); (UC); (ANU)

    2008-10-08

    the product of melting of deeply recycled (subducted) Archean-age metasediments in the mantle transition zone [Murphy, D.T., Collerson, K.D., Kamber, B.S., 2002. Lamproites from Gaussberg, Antartica: possible transition zone melts of Archaean subducted sediments. J. Petrol. 43, 981-1001]. Here we report the results of phase equilibria experiments on two different natural sedimentary compositions (a high-grade metapelite with < 1 wt.% H{sub 2}O, and a marine 'mud' with 8 wt.% H{sub O}) at 16-23 GPa. In both materials, the high-pressure mineral assemblages contain {approx} 15-30 wt.% K-hollandite (KAlSi{sub 3}O{sub 8}), in addition to stishovite, garnet, an Al-silicate phase (kyanite or phase egg), and a Fe-Ti spinel (corundum). Ion microprobe analyses of K-hollandite for a range of trace elements reveal that this phase controls a significant proportion of the whole-rock budget of incompatible, large-ion lithophile elements (LILEs, e.g., Rb, Ba, Sr, K, Pb, La, Ce and Th). Comparisons between the abundances and ratios of these elements in K-hollandite with those in EM-I type ocean-island basalts from Pitcairn Island and related seamounts, and with the Gaussberg lamproites, indicate the presence of deeply recycled, continent-derived sediments in these lavas sources. Our results suggest that the incompatible trace-element signature of EM-I OIB reservoirs in general and of the Gaussberg lamproites in particular can be attributed to recycling of K-hollandite-bearing continental sediments to transition zone depths.

  16. Research On Stabilization Of Radioactive Waste By Method Of SYNROCK Ceramic

    International Nuclear Information System (INIS)

    Nguyen Hoang Lan; Nguyen Ba Tien; Vuong Huu Anh; Nguyen An Thai

    2014-01-01

    Separate phases from SYNROC polyphases ceramic were investigated to fabricate completely SYNROC and the distribution of stable isotopes (Sr) in SYNROC matrix was surveyed simultaneously with leaching test. The experimental conditions: 13.5 x 11mm pressed pellet SYNROC with pressure of 2.5 - 3 tons/cm 2 , sintering temperature t tk = 1250 o C, thermal lifting velocity v t = 20 o C/min with 2 hours prolongation in 1250 o C, Sr loading amount was 7% mole, the results showed that pellets contain 3 phases perovskite CaTiO 3 , zirconolite CaZrTi 2 O 7 , hollandite BaAl 2 Ti 6 O 16 with average density of 4.1 g/cm 3 , leaching rate R (g/m 2 .d) of 10 -6 , 10 -5 for Ti, Sr respectively. (author)

  17. Radiophase development in hot-pressed alkoxide-derived titanate ceramics for nuclear waste stabilization

    International Nuclear Information System (INIS)

    Dickson, F.J.; Mitamura, H.; White, T.J.

    1989-01-01

    This paper reports phase development as a function of hot-pressing temperature studied in alkoxide-derived titanate-based ceramics doped with a 10 wt% loading of a sodium-rich (NAR) and a sodium-poor (NAP) simulated high-level waste. Pyrochlore was found to be the most abundant phase in both calcine powders. A pseudobrookite phase existed metastably at hot-pressing temperatures between 890 degrees and 920 degrees C. After hot-pressing at 1100 degrees C, the final phase assemblage for the NAP material consisted of zirconolite, hollandite-type, perovskite, alloy, and reduced rutile (Magneli phases). In addition, NAR samples contained hibonite, freudenbergite, and loveringite. Phase development was driven to completion over a very narrow temperature range (≤50 degrees C), beginning at 870 degrees and 850 degrees C for NAP and NAR, respectively, although full densification was not achieved below 1100 degrees C. Both waste forms exhibited comparable microstructure and aqueous durability

  18. Il gradiente implicito nella verifica a fatica di giunzioni saldate sollecitate a fatica

    Directory of Open Access Journals (Sweden)

    R. Tovo

    2009-07-01

    Full Text Available L’incremento delle potenzialità di strumenti per la progettazione assistita (come modellatori solidi e strumenti per FEA in grado di gestire modelli molto complessi permette di ipotizzare lo sviluppo di strumenti numerici specifici per la previsione della resistenza a fatica delle giunzioni saldate. Tali strumenti potrebbero essere in grado di valutare l’influenza di geometria e carichi senza la necessità di elaborazioni successive, e spesso, del progettista (come nelle tensioni di Hot Spot. Il presente lavoro propone una metodologia di calcolo adatta alla previsione della vita a fatica di giunzioni saldate complesse. Un indice di resistenza è ottenuto innanzitutto risolvendo il problema tensionale completamente in modo numerico (agli elementi finiti. La previsione della resistenza a fatica, è calcolata facendo uso di un modello analitico basato sul gradiente implicito che assume come tensione efficace la tensione equivalente non locale derivante dalla tensione principale. Dapprima verrà tarato il metodo su prove sperimentali eseguite su giunzioni saldate a croce, successivamente il metodo verrà utilizzato per la verifica a fatica di giunzioni saldate più complesse a sviluppo tridimensionale.

  19. Le Corbusier, Pierre Chareau and two masterpieces of modern architecture

    Directory of Open Access Journals (Sweden)

    Sílvia Amaral Palazzi Zakia

    2015-06-01

    Full Text Available Le Corbusier and Pierre Chareau are famously responsible for two projects considered iconic of modern architecture: Villa Savoye and Maison de Verre. Both are coeval and commissioned by clients with the same socioeconomic profile – the French haute bourgeoisie –, and with similar needs. Villa Savoye is a single family home, while Maison de Verre houses both residential and medical clinic functions in the same building structure. However, this difference does not interfere in our intended analysis. By comparing the client-architect relationships in both projects – Le Corbusier/Savoye and Chareau/Dalsace – we raise  questions regarding the professional behavior that modern architects have arrogated to themselves: to revolutionize customs and practices. The projects are modern and diverse responses to similar requests. In both cases, the role of women is indicative of their influence in that particular historical context as opinion setters. The house is the locus of the female dominium, and as such expresses women’s tastes and habits.

  20. SYNROC process. A geochemical approach to nuclear waste immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Ringwood, A E; Kesson, S E; Ware, N G; Hibberson, W O; Major, A [Australian National Univ., Canberra. Research School of Earth Sciences

    1979-08-01

    The SYNROC process is proposed to immobilize high-level wastes as dilute solid solutions in the constituent minerals of a synthetic rock formed from a mixture of oxides. New modification of the SYNROC was developed. Experiments showed that the entire spectra of high-level waste elements can be incorporated in the crystal lattices of Ba-hollandite, perovskite and zirconolite. This titanate assemblage has been proved to be exceptionally resistant to hydrothermal leaching, and in this respect, amongst others, it is demonstrably superior to alternative ceramic waste forms and to borosilicate glasses. The relative stability of various waste forms was compared in hydrothermal leaching experiments using both pure water and 10 w/o NaCl solution. Borosilicate glasses were almost completely decomposed and disintegrated after only 24 hours at 350 deg C and 1000 bars, and the extensive loss of hazardous high-level waste elements occurred. The phase pollucite in ceramic waste forms began to decompose at 400 deg C. The hollandite-perovskite-zirconolite SYNROC assemblage was proved to be exceptionally resistant to leaching, surviving invariably the extreme conditions up to 900 deg C and 5000 bars. Geochemical studies of the naturally-occurring minerals containing radwaste elements are relevant to the problem of radiation damage to SYNROC phases. These imply that the 2-particle flux in SYNROC is unlikely to be enough to impair the ability to immobilize radwaste for the required period. The production of SYNROC is explained in detail. The SYNROC phases have the structures analogous to the natural minerals which have survived a variety of geological conditions for millions of years while retaining certain high-level waste elements in their crystal lattices.

  1. Thermal durability of modified Synroc material as reactor fuel matrix

    International Nuclear Information System (INIS)

    Kikuchi, Akira; Kanazawa, Hiroyuki; Togashi, Yoshihiro; Matumoto, Seiichiro; Nishino, Yasuharu; Ohwada, Isao; Nakata, Masahito; Amano, Hidetoshi; Mitamura, Hisayoshi

    1994-08-01

    A Synroc, a polyphase titanate ceramics composed of three mineral phases (perovskite, hollandite and zirconolite), has an excellent performance of immobilization of high level nuclear waste. A working group in the Department of Hot Laboratories paid special attention to this merit and started a development study on a LWR fuel named 'Waste Disposal Possible (WDP) Fuel', which has the two functions of a reactor fuel and a waste form. The present paper mainly describes thermal durability of a modified Synroc material, which is essentially important for applying the material to a fuel matrix. The two kinds of Synroc specimens, designated 'SM' as modified and 'SB' as a reference, were prepared by hot-pressing and annealed at 1200degC to 1500degC for 30 min in air. Unexpected and peculiar spherical voids were observed in the specimen SM at 1400degC and 1500degC, which caused the specimen swelling. The formation of the voids depends significantly on the existence of spherical precipitates seen in the as-fabricated specimen including latent micropores with high pressure. On the other hand, the heat treatment at 1500degC formed additional new phases, designated 'Phase A' for the specimen SB and 'Phase X' for SM. Phase A is a decomposition product of hollandite and Phase X a reaction product of Phase A and perovskite in the spherical voids. Furthermore, additional information and thermal properties examined are presented in Appendix 1 and Appendix 2, respectively. It was recognized that the modified Synroc specimen SM had excellent thermal properties. (author)

  2. Manganese-oxide minerals in fractures of the Crater Flat Tuff in drill core USW G-4, Yucca Mountain, Nevada

    International Nuclear Information System (INIS)

    Carlos, B.A.; Bish, D.L.; Chipera, S.J.

    1990-07-01

    The Crater Flat Tuff is almost entirely below the water table in drill hole USW G-4 at Yucca Mountain, Nevada. Manganese-oxide minerals from the Crater Flat Tuff in USW G-4 were studied using optical, scanning electron microscopic, electron microprobe, and x-ray powder diffraction methods to determine their distribution, mineralogy, and chemistry. Manganese-oxide minerals coat fractures in all three members of the Crater Flat Tuff (Prow Pass, Bullfrog, and Tram), but they are most abundant in fractures in the densely welded devitrified intervals of these members. The coatings are mostly of the cryptomelane/hollandite mineral group, but the chemistry of these coatings varies considerably. Some of the chemical variations, particularly the presence of calcium, sodium, and strontium, can be explained by admixture with todorokite, seen in some x-ray powder diffraction patterns. Other chemical variations, particularly between Ba and Pb, demonstrate that considerable substitution of Pb for Ba occurs in hollandite. Manganese-oxide coatings are common in the 10-m interval that produced 75% of the water pumped from USW G-4 in a flow survey in 1983. Their presence in water-producing zones suggests that manganese oxides may exert a significant chemical effect on groundwater beneath Yucca Mountain. In particular, the ability of the manganese oxides found at Yucca Mountain to be easily reduced suggests that they may affect the redox conditions of the groundwater and may oxidize dissolved or suspended species. Although the Mn oxides at Yucca Mountain have low exchange capacities, these minerals may retard the migration of some radionuclides, particularly the actinides, through scavenging and coprecipitation. 23 refs., 21 figs., 2 tabs

  3. Materiaux composites supraconducteurs

    Science.gov (United States)

    Kerjouan, Philippe; Boterel, Florence; Lostec, Jean; Bertot, Jean-Paul; Haussonne, Jean-Marie

    1991-11-01

    The new superconductor materials with a high critical current own a large importance as well in the electronic components or in the electrotechnical devices fields. The deposit of such materials with the thick films technology is to be more and more developped in the years to come. Therefore, we tried to realize such thick films screen printed on alumina, and composed mainly of the YBa2CU3O{7-δ} material. We first realized a composite material glass/YBa2CU3O{7-δ}, by analogy with the classical screen-printed inks where the glass ensures the bonding with the substrate. We thus realized different materials by using some different classes of glass. These materials owned a superconducting transition close to the one of the pure YBa2CU3O{7-δ} material. We made a slurry with the most significant composite materials and binders, and screen-printed them on an alumina substrate preliminary or not coated with a diffusion barrier layer. After firing, we studied the thick films adhesion, the alumina/glass/composite material interfaces, and their superconducting properties. Les nouveaux matériaux supraconducteurs à haute température critique ont potentiellement un rôle important à jouer dans le domaine de l'électronique et de l'électrotechnique. En particulier, le dépôt d'oxydes supraconducteurs sur divers types de substrats est une technologie amenée à se développer. Nous avons donc entrepris une étude dont l'objet est la réalisation de conducteurs sérigraphiés sur alumine et composés essentiellement du matériau YBa2CU3O{7-δ}. Nous avons tout d'abord cherché à réaliser un composite verre/YBa2CU3O{7-δ}, par analogie au principe de réalisation de couches conductrices sérigraphiées, le verre permettant d'obtenir une liaison physico-chimique avec le substrat. Une étude préliminaire a permis de réaliser divers matériaux composites massifs, utilisant différentes familles de verres. Ces matériaux massifs, se présentant sous la forme de barreaux de

  4. Water penetration mechanisms in nuclear glasses by X-ray and neutron reflectometry

    International Nuclear Information System (INIS)

    Rebiscoul, D.; Rieutord, F.; Ne, F.; Frugier, P.; Gin, S.; Cubitt, R.

    2007-01-01

    To determine the water diffusion at the early stage of the alteration, X-ray and neutron reflectometry have been performed on altered simplified glasses and the SON68 glass (an inactive R7T7-type French nuclear glass). For the first experiment, the simplified and SON68 glasses were altered at pH 3 and pH 6 and characterized by X-ray reflectometry as a function of the alteration duration. The evolutions of the electron density profile obtained from the reflectivity curves simulations have allowed the determination of the layers compositions. At the beginning of the alteration and for pH 3, the altered surface layer is constituted of a dealkalized zone. Upon alteration progress, the water diffuses inside the layer and hydrolyzes the Si-O-B bonds. For the second experiment, glasses were altered in D 2 O (pD 3) and analyzed in D 2 O saturated cell. After a D 2 O/H 2 O substitution, the samples were characterized one more time in H 2 O saturated cell. The evolution of the scattering length density shows that in the first stage of the alteration, the layer is constituted of two parts: a dealkalized glass and a dealkalized and boron depleted glass where water has diffused. According to the glass composition and after few hours of alteration, this dealkalized glass part can disappear. (authors)

  5. Scintillation Counters for Neutron Scattering Experiments; Compteurs a scintillations pour les experiences de diffusion neutronique; Stsintillyatsionnye schetchiki dlya ehksperimentov s rasseyaniem nejtronov; Contadores de centelleo para experimentos de dispersion neutronica.

    Energy Technology Data Exchange (ETDEWEB)

    Harris, D; Duffil, C [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada); Wraight, L A [Aere, Harwell, Didcot, Berks (United Kingdom)

    1963-01-15

    Scintillation counters discussed in this paper are of two types : (i) UP or B{sub 2}O{sub 3} fixed with zinc sulphide in varving composition, (ii) Li containing glasses of varying composition. The ideal composition of each rype for neutron scattering experiments and their relative sensitivity tae neutrons and {gamma}-rays are considered. The ZnS type can be used with a {gamma}-ray pulse shape discriminator and practical experience of its use in a multi-counter time-of-flight experiment is described. The Li glass has higher {gamma}-background but also higher neutron efficiency. Performance figures of a scintillator containing 25% by wt. Li{sub 2}O and 1 mm thick will be given. (author) [French] Les compteurs a scintillations etudies sont de deux types : i) LiF ou B{sub 2}O{sub 3} fixe par du sulfure de zinc en composition variable, ii) verres contenant du lithium en composition variable. Les auteurs examinent la composition ideale de chaque type de compteur pour les experiences de diffusion de neutrons, ainsi que leur sinsibilite rrelative aux neutrons et aux rayons gamma. On peut utiliser le compteur a ZnS avec un discriminates de forme pour rayons gamma; les auteurs decrivent l'experience qu'ils ont de son emploi dans une experience de temps de vol a plusieurs compteurs. Le compteur verre-Li a un mouvement propre plus eleve pour les rayons gamma mais une meilleure efficacite vis-a-vis des neutrons. Les auteurs donnent quelques chiffres concernant le fonctionnement d'un scintillateur contenant 25% en poids de Li{sub 2}O et ayant une epaisseur de un millimetre. (author) [Spanish] Los contadores de centelleo examinados en esta memoria son de dos tipos : a) de LiF o B{sub 2}O{sub 3} mezclado con sulfuro de cinc en proporciones variables; b) de vidrios litiados de diversas composiciones. Los autores estudian la composicion ideal de cada tipo para experimentos de dispersion neutronica, asi como su sensibilidad relativa a los neutrones y a los rayos gamma. El tio de Zn

  6. Ein unbekanntes Meisterwerk altdeutscher Glaskunst: Hans Wertingers gläserne Hostienschale von 1498

    Directory of Open Access Journals (Sweden)

    Koreny, Fritz

    2010-08-01

    Full Text Available This hitherto unknown glass paten with églomisé painting, dated 1498 and measuring 36 cm in diameter, depicts the meeting of Abraham and Melchisedek. The painting can be attributed to Hans Wertinger, an artist from Landshut, who is well known for his paintings and stained glass. The recently discovered paten is executed in a refined églomisé technique with painting, scratching-out and with underlayers of gold and silver leaf, making it one of the earliest and finest examples of this technique, not only for Bavarian early Renaissance art but worldwide. The paten thus sheds fresh light on Wertinger as it shows him as an highly trained artist who worked also with bravura in the art of verre églomisé.

  7. Pluridisciplinaire

    Directory of Open Access Journals (Sweden)

    Eliana Magnani

    2007-08-01

    Full Text Available L’actualité de la recherche présentée dans ce onzième volume du Bulletin du CEM montre le renforcement pluridisciplinaire dans la plupart des programmes de recherche menés par les médiévistes de l’ARTeHIS (UMR 5594 – archéologues, historiens, historiens de l’art et musicologues – regroupés autour du Centre d’études médiévales d’Auxerre. L’analyse et l’étude des matériaux, du verre aux terres cuites architecturales, en passant par les pierres, les enduits et le stuc, sont depuis plusieurs ann...

  8. Advanced Aircrew Display Symposium Proceedings (5th) Held at the Naval Air Test Center, Patuxent, Maryland on 15-16 September 1981

    Science.gov (United States)

    1981-01-01

    neaiy* ~ rly a l wayn Wi. lit. 111TN ul . designl leadl~ll, alid th11c illiOet.Vý~iii;tIy l~ess warrurital- le assumiption tha t the pilot is aidaptive...iThe !I.Vl iHornet txpandL; tue( concept oil the AV-8B ’rid fur the firzt tim hant Urinchieved q re( verr .-al ill the trendl toward: toroe tnd more...ti-i a1 t e Iut i. t t Il I t le thea uprighlt. paul ition inl (J.05 ’ocl-. Thiti in h:o;rLa~vaelt~ (barnad upon the eonýtraivitiu wand in I he .Lt a

  9. The Air Is on Fire

    Directory of Open Access Journals (Sweden)

    Thérèse Guilbert

    2008-05-01

    Full Text Available C’est un grand néon rose fluorescent accroché à la façade de verre de la Fondation Cartier qui affiche le nom de David Lynch et annonce l’exposition The Air Is on Fire (du 3 mars au 27 mai 2007. La forme froide des lettres intriquées évoque l’architecture industrielle qui fascine tant l’artiste et, sans surprise, le modèle du néon sera à chercher dans la collection de ses dessins soigneux. Car on connaissait David Lynch le cinéaste, mais voilà le plasticien : peintures et aquarelles, sculptu...

  10. Proceedings of Workshop on Atmospheric Density and Aerodynamic Drag Models for Air Force Operations Held at Air Force Geophysics Laboratory on 20-22 October 1987. Volume 2

    Science.gov (United States)

    1990-02-13

    cr, K Glk- M Le C - 0 of a-0 60.U) 0 Go Ui :lq 5~I - 2 Im’ 04 En wv I C1 -i CL lk I S~a v~w/so 000 5~. - - CD coD CD CD 0N N IN >Z C4 ’C4 -- J C...wcigh- of 25 lie- verr : CIo-’ to that of air in the irixitng rg mion (25.9G. 5 - 33 14 0 -- - - - I-- I I I ’I ’ I ’T . "I I I I MSIS 1983- - 70 - 130...F :i z~ I ~ i LLI HE ) I--r ua 1 : a I: U. VI C cr~ Le IL i II, ~ 1 0 2 < 5 -46 Lu - D. 0 I 0.J w:- a:: ɚ w Hl uj 02 0. T (3 ccG, CL (0 CI J LL (n

  11. Pressure and Temperature Studies of Glass Properties Related to Vibrational Spectra.

    Science.gov (United States)

    1974-12-01

    Press, New York, 61 (1972). (61 G.K. White, Cryogenics 4, 2, (1964). (71 A. Dietzel and H.A. Sheybany, Verres et Refractaires 2, 63 (1948); Ceramic...Go 0 0 0 0 C64 44 CL a 1-4 k %% 4. OD 4 v. .0 0 0 04 6 r4 vI 1. 4 .- 4v- - 0) 60 en %D %. . I 4 0 n Nt 40 4 0ý Wa Lo 4A Le Nn LO %a 4o 4 0. ൴ ;1I c...M.I1. MANGHNANI TA• LE I. comn•i~sltIIm of Na2O-810O glasnse. TABLE U. Sodium silicate glasses. Observed infrared absorp-tions at ambient pressure (cMa

  12. Gallé, une vie au tournant du siècle.

    Directory of Open Access Journals (Sweden)

    Isabelle Debilly

    2004-05-01

    Full Text Available La collection Découvertes de Gallimard propose un nouveau volume dédié à Émile Gallé, le magicien du verre . Il s’agit là déjà, du 446 e numéro de cette collection destinée à l’origine aux adolescents. Ce principe a été en grande partie abandonné, même si l’on trouve encore les volumes de cette collection dans les rayons « jeunesse » de certaines librairies. Le grand public a depuis longtemps plébiscité ces ouvrages qui présentent une riche iconographie, ...

  13. Synthetic Aperture Processing of Wideband Scattering Measurements Made in the DRDC Atlantic Acoustic Calibration Tank

    Science.gov (United States)

    2008-09-01

    as represented by the Minister of National Defence, 2008 © Sa Majesté la Reine (en droit du Canada), telle que représentée par le ministre de la...des mines ventouses d’entraînement réelles, sur un disque de un mètre de diamètre qui était suspendu dans le bassin d’étalonnage acoustique de RDDC...Atlantique à l’aide d’une perche rotative. Deux disques ont été examinés : un en aluminium et l’autre en fibre de verre . Ces disques ont été tournés

  14. Your World in Pictures

    Directory of Open Access Journals (Sweden)

    Frédéric Perrier

    2009-06-01

    Full Text Available En association avec le groupe Time Inc., propriétaire de Life Magazine, dont la version papier a disparu des kiosques en 2007 du fait de son coût d’impression devenu trop lourd, le géant américain Google a mis en ligne une partie de la collection du magazine. Photographies, gravures, plaques de verre et diapositives (dont la grande majorité n’a jamais été publiée sont archivées sur un site qui leur sont dédiées: Google Images. Elles sont disponibles gratuitement pour un usage personnel ou po...

  15. A Study of the Attitudes of Married Minuteman Crewmembers and Their Wives Concerning Female Minuteman Crewmembers

    Science.gov (United States)

    1978-12-01

    344 H P4 1- c 04 -n P3 W4.t ~ ~ 03 o ~ *~ A C14 -4 %C)C14 -r C14 Le C14 C14 cn* -? - It u-n r- 0%1 C? ~I C-4 0 .- 4 ~N 0i~ CD 0% -r) 00 CN Y C14𔃻 0r0...mixed, she would have to be verr liberal. My deputy got sick and I played nurse for 4 days. However, others (i.e., executive secretary) are in...different fromt Controlling Office) 15. SECURITY CLASS. (of tis report) Unclassified Iea. DECL ASSI F1CATION/ODOWN GRAOI NO SC14EDU LE 1S. DISTRIBUTION

  16. Le massacre de la mariée

    Directory of Open Access Journals (Sweden)

    Bastiaan van der Velden

    2016-06-01

    Full Text Available Le Massacre des innocents a été pour Marcel Duchamp l’une de ses sources en composant Le Grand Verre. Ce ‘massacre’ est dans ce cas plus précisément une attraction foraine. D’autre part l’infanticide à Bethlehem constitue un sujet maintes fois représenté par différents peintres. Pour Alfred Jarry, auteur littéraire et de théâtre qui a plus particulièrement inspiré Duchamp, le tableau Le Massacre des innocents de Breughel l’Ancien était une pièce clé qui lui permettait de démontrer pourquoi il rejetait l’art historisant en peinture et dans le théâtre.

  17. Liberté, Égalité, Ébriété

    Directory of Open Access Journals (Sweden)

    Geneviève Lafrance

    2009-09-01

    Full Text Available « Allons, enfants de la Courtille, le jour de boire est arrivé. » Fusil à l’épaule, chanson aux lèvres et verre à la main, les patriotes qui célébraient, fin 1792, l’avènement de la République entendaient jouir d’un privilège que la mise à sac de l’Ancien Régime avait laissé intact : celui qu’ont les vainqueurs de trinquer à leurs succès. En cet automne où l’on s’apprêtait à voter la mort du roi, un parodiste anonyme profita des circonstances pour offrir au lectorat parisien une version burle...

  18. 'Paranoia and its historical development (systematized delusion)', by Eugenio Tanzi (1884).

    Science.gov (United States)

    Castagnini, Augusto

    2016-06-01

    This was the first paper by the Italian alienist Eugenio Tanzi (1856-1934). It surveyed existing works and provided an analysis of clinical categories such as monomania, sensory madness, moral insanity, Wahnsinn, Verrücktheit and systematized delusions, which had been used in France, Germany, Britain and Italy since the early nineteenth century to deal with paranoia. As pointed out by Tanzi, discrepancies and discontinuities in diagnostic concepts affected both psychiatric nosology and practice. Paranoia (from the Greek παρά and νοια) made for greater clarity in psychiatric terminology, and denoted a broad category, including both acute and chronic delusional states which were considered to be distinct from mania and melancholia, and usually not to lead to mental deterioration. © The Author(s) 2016.

  19. Geneva University: Experiments in Physics: Hands-on Creative Processes

    CERN Multimedia

    Université de Genève

    2011-01-01

    Geneva University Physics Department 24, quai Ernest-Ansermet CH-1211 Geneva 4 Tel: (022) 379 62 73 Fax: (022) 379 69 92   Lundi 3 octobre 2011, 17h00 Ecole de Physique, Auditoire Stueckelberg «Experiments in Physics : Hands-on Creative Processes» Prof. Manfred Euler Leibniz-Institute for Mathematics and Science Education (IPN) University of Kiel, Deutschland Experiments play a variety of different roles in knowledge generation. The lecture will focus on the function of experiments as engines of intuition that foster insights into complex processes. The experimental presentations consider self-organization phenomena in various domains that range from the nanomechanics of biomolecules to perception and cognition. The inherent universality contributes to elucidating the enigmatic phenomenon of creativity. Une verrée en compagnie du conférencier sera offerte après le colloque.       &...

  20. Les images en géographie sous l’angledes humanités numériques

    Directory of Open Access Journals (Sweden)

    Gaëlle Hallair

    2009-04-01

    Full Text Available L’article présente une méthodologie pour conserver, stocker, inventorier, archiver, numériser, indexer, valoriser et diffuser des archives géographiques sous l’angle des Digital humanities. L’article applique cette méthodologie aux images en géographie avant de présenter un projet de plate-forme documentaire concernant les plaques de verres du fonds Emmanuel de Martonne hébergées actuellement par l’UMR CNRS 8586 PRODIG.This article points out the methodology of Digital humanities to preserve, to stock, to make an inventory, to digitize, to index, to enhance the value und to spread geographical archives. It applies this methodology to geographical visual documents and presents a database project about photographic plates of the Emmanuel de Martonne’s collection localised in the research center PRODIG (UMR CNRS 8586.

  1. CERN SOLAR CLUB

    CERN Multimedia

    Solar Club

    2011-01-01

    Le club tiendra son Assemblée générale le mercredi 13 avril 2011 à la suite de la conférence organisée par l'Association du personnel Sur la route du soleil levant Une première en vélo électrique solaire qui a lieu à 18 h 30 * * * * * * L’AG aura donc lieu vers 20 h 15. Ordre du jour habituel avec comptes rendus des Activités et finances, et présentations des projets pour le futur. Rejoignez-nous pour parler du solaire et des énergies renouvelables en général, proposer des projets et y participer. L’AG se termine avec le verre de l'amitié !

  2. Inhabiting Adaptive Architecture

    Directory of Open Access Journals (Sweden)

    Holger Schnädelbach

    2017-12-01

    Full Text Available Adaptive Architecture concerns buildings that are specifically designed to adapt to their inhabitants and to their environments. Work in this space has a very long history, with a number of adaptive buildings emerging during the modernist period, such as Rietveld’s Schröder house, Gaudi’s Casa Batlló and Chareau's Maison de Verre. Such early work included manual adaptivity, even if that was motor-assisted. Today, buildings have started to combine this with varying degrees of automation and designed-for adaptivity is commonplace in office buildings and eco homes, where lighting, air conditioning, access and energy generation respond to and influence the behaviour of people, and the internal and external climate.

  3. Contrainte supplémentaire de potentiel dans une simulation monte carlo inverse pour l'étude de l'electrolyte aqueux LICL-6H2O à l'etat vitreux.

    OpenAIRE

    HABCHI, Mohammed

    2015-01-01

    L’électrolyte aqueux de type LICI-6H2O est étudie a l’état vitreux (120k) . Ce système présente la proprette de former un verre en passant par l’état liquide métastable surfondu quand la température diminue . La méthode de simulation utilisée dette de monte Carlo inverse (RMC) de l'anglais reverse monte Carlo celle-ci présent l’intérêt de pouvoir être appliquée sans que les interaction interatomiques et intermoléculaires soient spécifies .

  4. Effect of the New Insulation Liner on Noise Levels in the CH124B (Sea King) Aircraft

    Science.gov (United States)

    2008-11-01

    du bruit. L’ancien isolant était une membrane imperméable Mylar MIL-C-7514B recouverte de chaque côté de fibre de verre . Récemment les hélicoptères...Sea King ont été équipés d’un nouveau type d’isolant fait de cellules fermées de mousse recouvertes de chaque côté d’un vinyl Herculight. En...pour vérifier le niveau de bruit avec et sans ce type d’isolant ([1]). Malheureusement ce dosimètre ne permet d’effectuer des mesures à chaque

  5. Verrerie de Passavant-la-Rochère/faïencerie de Salins

    OpenAIRE

    Barbe, Noël

    2007-01-01

    Le travail du verre est présent dès le Moyen Age à Passavant-la-Rochère. A Salins, la production céramique date du début du xviiie siècle. Sur chacun de ces sites subsiste une unité de production représentant par ailleurs la dernière activité de ce type dans la région administrative constituée par la Franche-Comté. La verrerie de Passavant-la-Rochère est une entreprise familiale employant 250 ouvriers. La faïencerie de Salins est aujourd'hui intégrée au groupe Sarreguemines-Digoin dont elle c...

  6. Contribution to the analytic study of ferrates; Contribution a l'etude analytique des ferrates

    Energy Technology Data Exchange (ETDEWEB)

    Becarud, N [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1965-06-01

    Preparation and chemical properties of potassium, strontium and barium ferrates are described. Separation by glass-paper chromatography, electrochemical studies and infrared spectra are shown. A polarographic determination of ferrate ion have been worked. The stability of these compounds is studied with differential thermal analysis. (author) [French] Ce travail concerne la preparation de divers ferrates ainsi que la recherche de leurs proprietes chimiques. On a etudie les moyens specifiques de les detecter, leur chromatographie sur papier a fibre de verre et leurs proprietes electrochimiques. Une methode de dosage polarographique des ferrates est decrite. Les spectres d'absorption infra-rouge sont fournis. Enfin on a etudie leur decomposition par analyse thermique differentielle. (auteur)

  7. Etude expérimentale et numérique de la résistance interlaminaire en mode I de thermoplastiques à renfort tissé = Experimental and numerical study of the mode I interlaminar resistance of thermoplastic composites

    OpenAIRE

    Avril , Christophe; Perreux , Dominique; Thiebaud , Frédéric; Reck , B.

    2009-01-01

    National audience; Les structures de maintien des projectiles accélérés à l'aide du lanceur électromagnétique PEGASUS de l'ISL sont réalisées sous la forme d'une stratification de couches de polymère renforcées de verre tissé. Une telle composition leur confère leur propriété d'isolant électrique et une résistance mécanique compatible avec les efforts extrêmes qu'ils sont appelés à subir. Le mode d'endommagement le plus couramment observé sur les radiographies-éclair prises en cours d'accélér...

  8. Italian comics and cinema: forms and functions of pornographic parody

    Directory of Open Access Journals (Sweden)

    Mauro Giori

    2016-12-01

    Full Text Available Il saggio si propone di indagare un fenomeno come il frequente ricorso alla parodia di testi preesistenti da parte della pornografia, un fenomeno tanto notorio quanto trascurato, anche dalla recente ondata di studi su questo particolare genere. Al centro dell’indagine viene posta una forma di pornografia che in Italia, tra gli anni ’60 e gli anni ’80, ha fatto da testa di ponte alla diffusione di quella cinematografica attraverso una produzione industriale vasta quanto peculiare: quella in forma di fumetto. Tale produzione verrà analizzata in una prospettiva intermediale, ovvero nelle sue molteplici relazioni con il mondo del cinema, che vanno dall’assegnazione di volti di attori celebri ad alcuni eroi delle sue serie fino alla vera e propria parodia di interi film. Si mettono così in luce caratteri e funzioni assolti dalla parodia nell’ambito specifico della pornografia.

  9. Interfon

    CERN Multimedia

    Interfon

    2011-01-01

    Prochaine journée « Portes ouvertes » Mercredi 5 octobre de 16 h 00 à 20 h 00 Salle Jean Monnet à St-Genis Au cours de laquelle vous pourrez rencontrer nos partenaires devant un agréable buffet campagnard. Notre nouveau partenaire Centre commercial de ValThoiry     Tourné vers le bien-être, Lissac propose notamment une collection aussi légère qu’une… plume ! Ces montures « aériennes » (10 g en moyenne) se déclinent en 8 formes et 8 couleurs, pour répondre à toutes les envies : petites formes tendances, design étudié pour les verres progressifs, habillage des branches, etc. - 10% sur tous vos achats * * * * * Savoie Cheminées nous informe … L'entreprise Savoie Cheminées dépositaire des cheminées BRISA...

  10. Méthodes quantitatives de caractérisation de l'imprégnation d'un fil multifilamentaire par une matrice cimentaire

    OpenAIRE

    Aljewifi , Hana; Fiorio , Bruno; Gallias , Jean-Louis

    2009-01-01

    International audience; Les bétons textiles utilisent comme renfort des fils multifilamentaires dont l'imprégnation par la matrice cimentaire conditionne largement les propriétés mécaniques. Deux méthodes expérimentales qui permettent de quantifier le niveau d'imprégnation du fil sont présentées ici. Ces méthodes ont été testées sur trois types de fils multifilamentaires de verre, pour trois niveaux d'imprégnation. Les résultats des deux méthodes proposées sont mis en parallèle avec la caract...

  11. Solidification of residual fission-product solutions; laboratory studies; Solidification de solutions residuaires concentrees de produits de fission: etudes de laboratoire

    Energy Technology Data Exchange (ETDEWEB)

    Boniaud, R; Cohen, P; Sombret, C [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1961-07-01

    This paper describes the results obtained, at laboratory scale, during the study of the incorporation of fission products into glasses and synthetic micas. The rate of leaching of fission products from the glass and their volatility during firing were measured. A hot cell was built to complete these results. (author) [French] Ce rapport resume le resultat des etudes faites en laboratoire (activite de l'ordre du millicurie) sur l'incorporation des produits de fission dans des verres et micas synthetiques. On a mesure le taux de lixiviation des produits de fission et leur volatilisation au cours de la cuisson. Une cellule chaude a ete installee pour completer ces resultats au moyen d'essais realises avec une activite superieure. (auteur)

  12. Physics colloquium: Electron counting in quantum dots in and out of equilibrium

    CERN Multimedia

    Geneva University

    2011-01-01

    GENEVA UNIVERSITY Ecole de physique Département de physique nucléaire et corspusculaire 24, quai Ernest-Ansermet 1211 Genève 4 Tél.: (022) 379 62 73 Fax: (022) 379 69 92olé   Lundi 31 octobre 2011 17h00 - Ecole de Physique, Auditoire Stueckelberg PHYSICS COLLOQUIUM « Electron counting in quantum dots in and out of equilibrium » Prof. Klaus Ensslin Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland   Electron transport through quantum dots is governed by Coulomb blockade. Using a nearby quantum point contact the time-dependent charge flow through quantum dots can be monitored on the basis of single electrons. This way electron transport has been investigated in equilibrium as well as out of equilibrium. Recently it has become possible to experimentally verify the fluctuation theorem. The talk will also address electron counting experiments in grapheme. Une verrée ...

  13. [Cynocephali and Blemmyae. Congenital anomalies and medieval exotic races].

    Science.gov (United States)

    Bos, C A; Baljet, B

    1999-12-18

    In the mediaeval Dutch manuscript Der naturen bloeme ('On the flowers of nature') by Jacob van Maerlant (circa 1230-circa 1296), an encyclopaedia of descriptions of people, animals, plants and minerals dating from about 1270, many illustrations refer to the text. An intriguing part of the book is called 'Vreemde volkeren' ('Exotic people'). In another manuscript of Van Maerlant, Dit is die istory van Troyen ('The history of Troyes') in the chapter 'De wonderen van het Verre Oosten' ('The miracles of the Far East') the exotic people are also described. These exotic people have many features similar to congenital malformations. 'Hippopodes' are probably based on the lobster claw syndrome, 'Cynocephali' on anencephaly, 'Arimaspi' on cyclopia, 'Blemmyae' on acardiacus, the double-faced on diprosopus, 'Sciopods' on polydactyly and 'Antipodes' on the sirenomelia sequence.

  14. Dischi (E Jet) Nelle Stelle Massicce Giovani

    Science.gov (United States)

    Cesaroni, Riccardo

    2017-11-01

    In questo contributo verrà discussa l'importanza dei dischi e jet ad essi asso- ciati per la formazione delle stelle di tipo spettrale OB e verranno presentati i risultati recentemente ottenuti con ALMA in questo ambito. In particolare mostr- eremo che la struttura del disco sembra risentire della complessità dell'ambiente circostante e che la probabilità di rivelare un disco attorno alle stelle di più alta massa è massima in una fase evolutiva intermedia. Infine discuteremo la possibilità che il fenomeno di accrescimento dal disco sulla stella possa avvenire in maniera discontinua mediante "burst", probabilmente dovuti ad instabilità nel disco.

  15. Molecular dynamics study of vacancy-like defects in a model glass : static behaviour

    Science.gov (United States)

    Delaye, J. M.; Limoge, Y.

    1993-10-01

    The possibility of defining vacancy-like defects in a Lennard-Jones glass is searched for in a systematic manner. Considering different relaxation levels of the same system, as well as different external pressures, we use a Molecular Dynamics simulation method, to study at constant volume or external pressure, the relaxation of a “piece” of glass, after the sudden removal of an atom. Three typical kinds of behaviour can be observed: the persistence of the empty volume left by the missing atom, its migration by clearly identifiable atomic jumps and the dissipation “on the spot”. A careful analysis of the probabilities of these three kinds of behaviour shows that a meaningful definition of vacancy-like defects can be given in a Lennard-Jones glass. Dans cet article, nous nous penchons de façon systématique sur la possibilité de définir des défauts de type lacunaire dans un verre de Lennard-Jones, à différents niveaux de relaxation et de pression, par une méthode de simulation numérique en dynamique moléculaire à volume ou à pression constants. Le défaut est créé en supprimant un atome et en suivant la réponse du système. Nous observons trois comportements typiques : la persistance sur place du “trou” laissé par l'atome supprimé, sa migration par des sauts atomiques clairement identifiés et enfin sa dissipation sur place. Une analyse détaillée de ces trois comportements montre qu'il est possible dans un verre de Lennard-Jones de définir des défauts de type lacunaire.

  16. Experiments on neutron-attenuation by ordinary concrete; Etude experimentale de l'attenuation des neutrons dans le beton ordinaire

    Energy Technology Data Exchange (ETDEWEB)

    Beauge, R; Millot, J P; Rastoin, J [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    The penetration of fission-neutrons in water and glass mixtures has been investigated in the NAIADE facility. The slopes of the thermal and fast fluxes (the latter measured with a dosimeter) remain similar when the volume proportion of water is greater than 15 per cent. For smaller water-contents the measurements show the evidence of streaming, presumably due to slowing-down neutrons of energy smaller than 300 keV. Since a volume proportion of about 15 per cent of water in glass corresponds to the composition of ordinary concrete, the present work enables to predict the effects of a desiccation of concrete. Moreover, it is seen that there is no interest in increasing the proportion of water in ordinary concrete beyond the usual values (15-20 per cent). (author) [French] La propagation des neutrons de fission a ete etudiee dans les melanges verre-eau au moyen du dispositif NAIADE. La pente du flux thermique et la pente du flux rapide (obtenue au moyen d'un dosimetre) restent voisines lorsque la proportion d'eau dans le melange depasse 15 pour cent en volume. Pour des proportions d'eau inferieures les mesures mettent en evidence un 'streaming' de neutrons en ralentissement d'energie probablement inferieure a 300 keV. La composition des melanges verre-eau aux environs de 15 pour cent d'eau en volume correspondant au beton ordinaire, la presente etude permet de prevoir les effets d'une dessication du beton, et montre, en outre, qu'il n'y a pas interet a essayer d'augmenter la proportion d'eau dans le beton ordinaire au dela des valeurs usuelles (15 a 20 pour cent). (auteur)

  17. Nanostructured inorganic materials: Synthesis and associated electrochemical properties

    Science.gov (United States)

    Yau, Shali Zhu

    Synthetic strategy for preparing potential battery materials at low temperature was developed. Magnetite (Fe3O4), silver hollandnite (AgxMn8O16), magnesium manganese oxide (MgxMnO 2˙yH2O), and silver vanadium phosphorous oxide (Ag 2VO2PO4) were studied. Magnetite (Fe3O4) was prepared by coprecipitation induced by triethylamine from aqueous iron(II) and iron(III) chloride solutions of varying concentrations. Variation of the iron(II) and iron(III) concentrations results in crystallite size control of the Fe3O4 products. Materials characterization of the Fe3O4 samples is reported, including Brunauer-Emmitt-Teller (BET) surface area, x-ray powder diffraction (XRD), transmission electron microscopy (TEM), particle size, and saturation magnetization results. A strong correlation between discharge capacity and voltage recovery behavior versus crystallite size was observed when tested as an electrode material in lithium electrochemical cells. Silver hollandite (AgxMn8O16) was successfully synthesized through a low temperature reflux reaction. The crystallite size and silver content of AgxMn8O16 by varying the reactant ratio of silver permanganate (AgMnO4) and manganese sulfate monohydrate (MnSO4˙H2O). Silver hollandite was characterized by Brunauer-Emmitt-Teller (BET) surface area, inductively coupled plasma-optical emission (ICP-OES) spectrometry, helium pycnometry, simultaneous thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), and x-ray powder diffraction (XRD). The crystallite size showed a strong correlation with silver content, BET surface area, and particle sizes. The silver hollandite cathode showed good discharge capacity retention in 30 cycles of discharge-charge. There were a good relationship between crystallite size and rate capability and pulse ability. Magnesium manganese oxide (MgxMnO2˙yH 2O) was made by redox reaction by mixing sodium hydroxide (NaOH), manganese sulfate monohydrate (MnSO4˙HO2), and potassium persulfate (K2S2O8

  18. High-pressure phase relations in the composition of albite NaAlSi3O8 constrained by an ab initio and quasi-harmonic Debye model, and their implications

    Science.gov (United States)

    Deng, L.; Liu, X.; Liu, H.; Dong, J.

    2010-12-01

    The high pressure physical-chemical behaviors of feldspar in subducted slab are very important to the geodynamic process in the deep interior of the Earth. Albite (NaAlSi3O8;Ab) is one of the few end members in the feldspar family, and its high-P behavior is obviously a prerequisite to the full understanding of the physical-chemical properties of feldspar at high pressures. So far it has been well accepted that Ab breaks down to the phase assemblage of Jadeite+Stishovite(NaAlSi2O6; Jd, SiO2; St,JS hereafter) at ~9-10 GPa. The JS phase assemblage might be stable up to ~23 GPa, and eventually directly change into the phase assemblage of calcium-ferrite type NaAlSiO4 (Cf) +2St (CS hereafter). However, some independent researches suggest there is an intermediate phase Na-hollandite (Na-Hall; a phase with the composition of NaAlSi3O8 and the structure of hollandite) between JS phase assemblage transition into CS phase assemblage (Liu 1978; Tutti 2007; Sekine and Ahrens, 1992; Beck et al., 2004). Whether Na-Hall is a thermodynamic stable phase under high P-T conditions remains unknown. In this work, phase relations in the composition of albite NaAlSi3O8 at pressures up to 40 GPa were constrained by a theoretical method that combines the ab initio calculation and quasi-harmonic Debyemodel. First, the P-T dependence of the thermodynamic potentials of the individual phase, St, Cf, Jd and the hypothetical Na-Holl were derived. Our results are generally in consistent agreement with available experimental data and previous theoretical predictions. Second, the Gibbs free energy of the hypothetical Na-Holl phase was compared with that of the phase assemblages JS and CS. Our results show that the Na-Holl phase is not a thermodynamically stable phase over the studied P-T conditions of 0-40 GPa and 100-600 K, which rules it out as a possible intermediate phase along the transition path from the JS phase assemblage to CS phase assemblage. Our calculations have predicted that the JS

  19. R7T7-type HLW glass alteration under irradiation. Study of the residual alteration rate regime

    International Nuclear Information System (INIS)

    Rolland, Severine

    2012-01-01

    In France, fission products and minor actinides remaining after reprocessing of spent nuclear fuel are confined in a borosilicate glass matrix, named R7T7, for disposal in a geological repository. However, in these conditions, after several thousand years, water could arrive in contact with glass and be radio-lysed. In this work, we investigated the irradiation influence and especially the influence of the energy deposition on the residual glass alteration rate regime in pure water. Two types of leaching tests have been carried out. The first were performed on radioactive glass and the second on a SON68 glass (nonradioactive surrogate of R7T7 glass) under external irradiation γ. (author) [fr

  20. Characterization of HLW glass samples Task 3 Characterization of radioactive waste forms a series of final reports (1985-89) No 20

    International Nuclear Information System (INIS)

    Malow, G.; Behrend, U.; Schubert, P.

    1991-01-01

    Due to a delay in the melting of the highly radioactive SON68 glass, a short-term post-investigation of the highly radioactive glass from the Pamela plant in Mol (Belgium) has been carried out, the aim being a check-up of the active LEWC glass SM 513 LW11. The results were compared with those obtained for non-radioactive glass samples. The final report of the present CEC programme shortly describes the planned investigations of the glass R7T7 for the whole period of the research contract and the results of the short-term post-investigation of the Pamela glass. 11 refs.; 9 figs.; 4 tabs

  1. Manganese deposition in drinking water distribution systems.

    Science.gov (United States)

    Gerke, Tammie L; Little, Brenda J; Barry Maynard, J

    2016-01-15

    This study provides a physicochemical assessment of manganese deposits on brass and lead components from two fully operational drinking water distributions systems. One of the systems was maintained with chlorine; the other, with secondary chloramine disinfection. Synchrotron-based in-situ micro X-ray adsorption near edge structure was used to assess the mineralogy. In-situ micro X-ray fluorescence mapping was used to demonstrate the spatial relationships between manganese and potentially toxic adsorbed metal ions. The Mn deposits ranged in thickness from 0.01 to 400 μm. They were composed primarily of Mn oxides/oxhydroxides, birnessite (Mn(3+) and Mn(4+)) and hollandite (Mn(2+) and Mn(4+)), and a Mn silicate, braunite (Mn(2+) and Mn(4+)), in varying proportions. Iron, chromium, and strontium, in addition to the alloying elements lead and copper, were co-located within manganese deposits. With the exception of iron, all are related to specific health issues and are of concern to the U.S. Environmental Protection Agency (U.S. EPA). The specific properties of Mn deposits, i.e., adsorption of metals ions, oxidation of metal ions and resuspension are discussed with respect to their influence on drinking water quality. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Continuous-flow leaching studies of crushed and cored SYNROC

    International Nuclear Information System (INIS)

    Coles, D.G.; Bazan, F.

    1982-01-01

    Both crushed (150- to 300- μm) and cored (1,8- mm-diam) samples of SYNROC have been leached with single-pass continuous-flow leaching equipment. Crushed samples of cesium-hollandite were also leached in a similar experiment. Temperatures used were 25 0 and 75 0 C and leachates were 0.03 N NaHCO 3 and distilled water. Leaching rates from SYNROC-C were ranked cesium > strontium greater than or equal to calcium > barium > zirconium. A comparison of leaching rates is made between crushed SYNROC, cored SYNROC, and Pacific Northwest Laboratory 76-68 glass beads. This comparison depends on how the surface areas are determined for each sample. Based on geometric surface areas for SYNROC cores and glass beads, cesium leach rates from SYNROC compare well with both sodium and neptunium leached from the glass. The other elements leached from SYNROC are lower than sodium and neptunium leached from glass. They also vary for each element, while glass shows nearly the same leach rate for both sodium and neptunium

  3. Continuous-flow leaching studies of crushed and cored SYNROC

    International Nuclear Information System (INIS)

    Coles, D.G.; Bazan, F.

    1981-01-01

    Both crushed (150 to 300 μm) and cored (1.8 mm diameter) samples of SYNROC have been leached with the single-pass continuous-flow leaching equipment. Crushed samples of Cs-hollandite were also leached in a similar experiment. Temperatures used were 25 and 75 0 C and leachates were 0.03 N NaHCO 3 and distilled water. Leaching rates from SYNROC C were ranked Cs > Sr greater than or equal to Ca > Ba > Zr. A comparison of leaching rates is made between crushed SYNROC, cored SYNROC, and PNL 76-68 glass beads. This comparison depends on how the surface areas are determined for each sample. Based on geometric surface areas for SYNROC cores and glass beads Cs leach rates from SYNROC compare well with both Na and Np leached from the glass. The other elements leached from SYNROC are lower than Na and Np leached from glass. They also vary for each element while glass shows nearly the same leach rate for both Na and Np

  4. Effect of Sulfur Concentration and PH Conditions on Akaganeite Formation: Understanding Akaganeite Formation Conditions in Yellowknife Bay, Gale Crater, Mars

    Science.gov (United States)

    Fox, A.; Peretyazhko, T.; Sutter, B.; Niles, P.; Ming, D. W.; Morris, R. V.

    2015-01-01

    The Chemistry and Mineralogy Instrument (CHEMIN) on board the Mars Science Laboratory (MSL) Curiosity Rover identified minor amounts of akaganeite (beta-FeOOH) at Yellowknife Bay, Mars. There is also evidence for akaganeite at other localities on Mars from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Akaganeite is an iron(III) hydroxide with a hollandite- like structure and Cl in its tunnels. Terrestrial akaganeite usually forms in Cl-rich environments under acidic, oxidizing conditions. Previous studies of akaganeite have revealed that akaganeite formation is affected by the presence of sulfate (hereafter denoted as S. The prediction of circumneutral pH coupled with the detection of S at Yellowknife Bay dictate that work is needed to determine how S and pH together affect akaganeite formation. The goal of this work is to study how changes in both S concentration and pH influence akaganeite precipitation. Akaganeite formation was investigated at S/Cl molar ratios of 0, 0.017, 0.083, 0.17 and 0.33 at pH 1.5, 2, and 4. Results are anticipated to provide combined S concentration and pH constraints on akaganeite formation in Yellowknife Bay and elsewhere on Mars. Knowledge of solution pH and S concentrations can be utilized in understanding microbial habitability potential on the Martian surface.

  5. Status of plutonium ceramic immobilization processes and immobilization forms

    Energy Technology Data Exchange (ETDEWEB)

    Ebbinghaus, B.B.; Van Konynenburg, R.A. [Lawrence Livermore National Lab., CA (United States); Vance, E.R.; Jostsons, A. [Australian Nuclear Science and Technology Organization, Menai (Australia)] [and others

    1996-05-01

    Immobilization in a ceramic followed by permanent emplacement in a repository or borehole is one of the alternatives currently being considered by the Fissile Materials Disposition Program for the ultimate disposal of excess weapons-grade plutonium. To make Pu recovery more difficult, radioactive cesium may also be incorporated into the immobilization form. Valuable data are already available for ceramics form R&D efforts to immobilize high-level and mixed wastes. Ceramics have a high capacity for actinides, cesium, and some neutron absorbers. A unique characteristic of ceramics is the existence of mineral analogues found in nature that have demonstrated actinide immobilization over geologic time periods. The ceramic form currently being considered for plutonium disposition is a synthetic rock (SYNROC) material composed primarily of zirconolite (CaZrTi{sub 2}O{sub 7}), the desired actinide host phase, with lesser amounts of hollandite (BaAl{sub 2}Ti{sub 6}O{sub 16}) and rutile (TiO{sub 2}). Alternative actinide host phases are also being considered. These include pyrochlore (Gd{sub 2}Ti{sub 2}O{sub 7}), zircon (ZrSiO{sub 4}), and monazite (CePO{sub 4}), to name a few of the most promising. R&D activities to address important technical issues are discussed. Primarily these include moderate scale hot press fabrications with plutonium, direct loading of PuO{sub 2} powder, cold press and sinter fabrication methods, and immobilization form formulation issues.

  6. Alteration history studies in the Exploratory Studies Facility, Yucca Mountain, Nevada, USA

    International Nuclear Information System (INIS)

    Levy, S.S.; Chipera, S.J.; Norman, D.I.

    1996-01-01

    By mid-1995, the Exploratory Studies Facility (ESF) extended about 1. 1 km from Exile Hill westward toward Yucca Mountain, mostly within densely welded, devitrfied Tiva Canyon Tuff. Secondary mineral occurrences in this unit include breccia cements of mordenite, a fibrous zeolite, and vapor-phase deposits of silica, alkali feldspar, apatite, hollandite, amphibole, and zircon. Calcite is also a common secondary mineral in faults and fractures. Studies of water and gas contents in fluid inclusions in calcites from a fault in nonwelded tuff and a fracture in densely welded tuff suggest mineral deposition under transient locally saturated conditions. Calcite in the nonwelded tuff incorporated air from the unsaturated tuff adjacent to the fault. A highly altered interval within pre-Pah Canyon tuffs just above the top of the Topopah Spring Tuff may be a fossil fumarole or other hydrothermal feature associated with cooling pyroclastic deposits, overprinted by later zeolitic alteration. The observed quartz, cristobalite, opal-CT, and fluorite have been widely identified as products of syngenetic devitrification and vapor-phase alteration in and above the Topopah Spring Tuff. Smectite, also an abundant secondary mineral at the ESF site, has been observed elsewhere at this stratigraphic level. Zeolitic alteration of nonwelded tuffs above the Topopah Spring Tuff, as seen in the ESF, has also been noted in drill core and outcrop at northeastern Yucca Mountain. The hydrologic and geochemical conditions that favored zeolitization only in certain areas of this stratigraphic interval have yet to be determined

  7. A state-of-the-art report on the formulation and characterization of synroc

    International Nuclear Information System (INIS)

    Jung, C. H.; Park, J. Y.; Oh, S. J.; Kim, H. Y.; Kim, I. T.

    1998-09-01

    Synroc (Synthetic Rock), a titanate-based ceramic originally proposed by Prof. A. Ringwood (ANU) and designed for the immobilization of high level nuclear waste (HLW), consists of three principal phases such as hollandite, zirconolite and perovskite. Nearly all the fission products and actinides in HLW can be incorporated as solid-solution in at least one of these phase. The preferred form of Synroc can be obtained up to 20 % of high level waste calcine to form dilute solid solution. The constituent minerals, or close structural analogues, have survived in a wide range of geochemical environments for periods of 20-2000 Myr while immobilizing the same elements present in nuclear waste. A dense, compact, and mechanically strong form of Synroc can be formed by hot pressing reactive precursor powders at about 1200 dg C and 20 MPa. In this state-of-the-art report, formulation method and characterization of Syroc with respect to the crystal structure, the consisting substances, types, etc. were reviewed. Additionally, a new promising powder process, C ombustion Process , was proposed and the properties of the combustion-synthesized powder were described. An international cooperative program between JAERI and ANSTO, and US patents for early Synroc research in Australia were also introduced. From the literatures review, Synroc is expected to have advantages in using as an immobilizer of HLW. Therefore, a systematic research to develop the Synroc is needed. (author). 53 refs., 2 tabs., 16 figs

  8. Testing and evaluation of solidified high-level waste forms

    International Nuclear Information System (INIS)

    Engelmann, C.

    1984-01-01

    The report describes research by several laboratories on the behaviour, in aqueous and salt environments, of borosilicate glass ceramics proposed for the solidification of nuclear wastes by the European Community. Results were obtained on inactive simulates, doped materials, and on borosilicate glass containing real radioactive waste. The influence of many important parameters were studied: leaching mode, nature of the leachant, pH, pressure, temperature, duration of the treatment, etc. The results of tests lasting for as little as a few hours or for as long as several hundred days, at temperatures up to 200 0 C or under pressures up to 200 bars, are presented. Numerous analytical techniques (ESCA, EMP, IRR, SEM, etc.) were used to determine the structure and the chemical composition of the altered layer developed by hydration at the glass surface. Information is also given on physical properties of the borosilicate glass: crystallization phase separation, alpha-irradiation stability, mechanical and thermal stability, etc. Finally, preliminary results on the structure and composition of hollandite ceramics are given

  9. Evaluation of the technical feasibility of new conditioning matrices for long-lived radionuclides

    International Nuclear Information System (INIS)

    Deschanels, X.

    2004-01-01

    Several matrices have been selected for the conditioning of long-lived radioactive wastes: a compound made of a iodo-apatite core coated with a densified matrice of vanadium-phosphorus-lead apatite for iodine; the hollandite ceramic for cesium; the britholite, zirconolite, thorium phosphate diphosphate, and the monazite-brabantite solid solution for minor actinides; and a Nb-based metal alloy and phosphate or titanate-type ceramics for technetium. This report presents the results of the researches carried out between 2002-2004 during the technical feasibility step. The main points described are: - the behaviour of matrices under irradiation. These studies were performed thanks to an approach combining the characterization of natural analogues, the doping of matrices with short-lived radionuclides and the use of external irradiations; - the behaviour of these matrices with respect to water alteration; - the sensibility of these structures with respect to the incorporation of chemical impurities; - a package-process approach including the optimization of the process and preliminary studies about the package concept retained. These studies show that important work remains to be done to develop conditioning matrices suitable for iodine and technetium, while for cesium and minor actinides, the first steps of the technical feasibility are made. However, it remains impossible today to determine the structure having the best global behaviour. (J.S.)

  10. Application of SYNROC to high-level defense wastes

    International Nuclear Information System (INIS)

    Tewhey, J.D.; Hoenig, C.L.; Newkirk, H.W.; Rozsa, R.B.; Coles, D.G.; Ryerson, F.J.

    1981-01-01

    The SYNROC method for immobilization of high-level nuclear reactor wastes is currently being applied to US defense wastes in tank storage at Savannah River, South Carolina. The minerals zirconolite, perovskite, and hollandite are used in SYNROC D formulations to immobilize fission products and actinides that comprise up to 10% of defense waste sludges and coexisting solutions. Additional phase in SYNROC D are nepheline, the host phase for sodium; and spinel, the host for excess aluminum and iron. Up to 70 wt % of calcined sludge can be incorporated with 30 wt % of SYNROC additives to produce a waste form consisting of 10% nepheline, 30% spinel, and approximately 20% each of the radioactive waste-bearing phases. Urea coprecipitation and spray drying/calcining methods have been used in the laboratory to produce homogeneous, reactive ceramic powders. Hot pressing and sintering at temperatures from 1000 to 1100 0 C result in waste form products with greater than 97% of theoretical density. Hot isostatic pressing has recently been implemented as a processing alternative. Characterization of waste-form mineralogy has been done by means of XRD, SEM, and electron microprobe. Leaching of SYNROC D samples is currently being carried out. Assessment of radiation damage effects and physical properties of SYNROC D will commence in FY81

  11. Status of plutonium ceramic immobilization processes and immobilization forms

    International Nuclear Information System (INIS)

    Ebbinghaus, B.B.; Van Konynenburg, R.A.; Vance, E.R.; Jostsons, A.

    1996-01-01

    Immobilization in a ceramic followed by permanent emplacement in a repository or borehole is one of the alternatives currently being considered by the Fissile Materials Disposition Program for the ultimate disposal of excess weapons-grade plutonium. To make Pu recovery more difficult, radioactive cesium may also be incorporated into the immobilization form. Valuable data are already available for ceramics form R ampersand D efforts to immobilize high-level and mixed wastes. Ceramics have a high capacity for actinides, cesium, and some neutron absorbers. A unique characteristic of ceramics is the existence of mineral analogues found in nature that have demonstrated actinide immobilization over geologic time periods. The ceramic form currently being considered for plutonium disposition is a synthetic rock (SYNROC) material composed primarily of zirconolite (CaZrTi 2 O 7 ), the desired actinide host phase, with lesser amounts of hollandite (BaAl 2 Ti 6 O 16 ) and rutile (TiO 2 ). Alternative actinide host phases are also being considered. These include pyrochlore (Gd 2 Ti 2 O 7 ), zircon (ZrSiO 4 ), and monazite (CePO 4 ), to name a few of the most promising. R ampersand D activities to address important technical issues are discussed. Primarily these include moderate scale hot press fabrications with plutonium, direct loading of PuO 2 powder, cold press and sinter fabrication methods, and immobilization form formulation issues

  12. On the solution of a few problems of multiple scattering by Monte Carlo method; Sur la solution de quelques problemes de diffusions multiples par la methode de Monte-Carlo

    Energy Technology Data Exchange (ETDEWEB)

    Bluet, J C [Commissariat a l' Energie Atomique, Cadarache (France)

    1966-02-01

    isotrope. 3.- La particule ne perd pas d'energie au cours des collisions successives. Ces hypotheses sont justifiees par les materiaux et les gammes d'energie etudies. 1er probleme: une cible de sodium de geometrie donnee est soumise a un flux de neutrons. Certains noyaux sont actives. L'activation est ensuite mesuree par un cristal au iodure de sodium. La methode de Monte-Carlo permet de calculer la distribution des noyaux actives dans l'echantillon en tenant compte des diffusions et l'efficacite du compteur. Un disque en verre au Li{sup 6} est soumis a un flux de neutrons perpendiculaire a ses faces planes. Si l'epaisseur du verre n'est pas negligeable devant le libre parcours de diffusion {lambda}, il y aura des collisions et le parcours moyen e' d'un neutron dans le verre sera different de l'epaisseur. e' est calcule par la methode de Monte-Carlo. On en tire une correction relative d'efficacite egale a (e' - e)/ e. 3eme probleme: un detecteur de neutrons est place au fond d'un cylindre entoure d'eau. Un flux de neutrons provient d'une source placee sur l'axe, en avant de la protection; on calcule le rapport du nombre de neutrons allant directement de la source au detecteur au nombre de neutrons faisant un trajet non direct avec des collisions dans l'eau. Pour les trois problemes on donne les resultats trouves pour quelques cas concrets tels qu'ils se sont poses experimentalement, et des courbes plus generales ou on utilise des variables reduites comme le rapport libre parcours/dimension geometrique ou son inverse. On donne egalement les listes d'instructions des programmes, avec les organigrammes complets et les tableaux de correspondances entre symboles. (auteur)

  13. Divinacija prieš Cecilijų Cicerono retorikos kontekste. Divinatio in Caecilium in the context of Cicero’s rhetoric

    Directory of Open Access Journals (Sweden)

    Audronė Kučinskienė

    2010-01-01

    Full Text Available In the well known episode in the Divination against Caecilius (Divinatio in Caecilium 27–46, Cicero, assuming the role of a teacher, expounds issues of rhetoric to his opponent. In this article the following points are examined: 1 the relation of this episode to the theory of rhetoric of the time, as represented in the unknown author’s Rhetorica ad Herennium and Cicero’s De inventione, which he wrote as a young man; 2 the repercussions of this episode in Cicero’s later works of rhetoric; 3 the relation of this episode to the other speeches against Verres.In Div. Caec. 27–46, Cicero does not try to set forth his material systematically and sequentially, as it is customary in rhetorical treatises, but directs his attention first at the moral qualities of a good orator, as well as on his education and the innate personal traits that form a perfect orator. This allows us to connect the Divination against Caecilius with Cicero’s later treatises on rhetoric, in particular De oratore. Being a supporter of philosophical rhetoric, Cicero disdains the traditional Hellenistic manuals that expound rhetorical technique. He does not try to teach these things – which would be the aim of a rhetoric manual – but he presumes that his audience would understand them from the small hints about the topics that must be recognised as coming from the school of rhetoric. Such a stance corresponds well to the spirit of the treatise De oratore: in that work, Cicero does not teach rules and does not explain rhetorical technique either, but, having mastered these things perfectly himself, he addresses his work to those readers who know the art of rhetoric and who would certainly recognise and appreciate the hints on the art of rhetoric, which are scattered through the text rather than explicitly demonstrated.In the episode Div. Caec. 27–46, Cicero uses va­rious rhetorical figures copiously and inventively. It is obvious that, in explaining the issues of

  14. Solidification of Radioactive Waste Solutions; Solidification des Effluents Radioactifs; 041e 0422 0412 0415 0420 0416 0414 0415 041d 0418 0415 0420 0410 0414 0418 041e 0410 041a 0422 0418 0412 041d 042b 0425 0421 0411 0420 041e 0421 041d 042b 0425 0420 0410 0421 0422 0412 041e 0420 041e 0412 ; Solidificacion de Efluentes Radiactivos

    Energy Technology Data Exchange (ETDEWEB)

    Brezhneva, N. E.; Golovanov, Ju. N.; Oziraner, S. N.; Eremin, A. A.; Rozanova, V. N.

    1963-02-15

    precipitation des solutions radioactives initiales. Le procede de solidification a ete elabore de maniere a reduire au minimum les gaz d'echappement necessitant une epuration en raison de la presence d*aerosols et d* elements radioactifs volatils. Au cours de leur travaux, les auteurs ont determine les conditions optima permettant d'obtenir du verre chimiquement stable et demontre qu'il est possible de reduire la temperature de fusion du verre en faisant varier les fondants ajoutes. Ils ont constate une diminution notable de la stabilite chimique du verre lorsque celui-ci a ete conserve pendant un temps prolonge a une temperature superieure a 300 - 350 Degree-Sign C. Ils ont examine dans quelle mesure le radiocesium risque d'etre elimine du verre par lixiviation. Ils ont egalement etudie la volatilite du radio- cesium et du radioruthenium au cours de la dessiccation et de la fusion et montre que la volatilite du ruthenium disparait entierement dans une atmosphere de gaz carbonique. Quant a la volatilite du radiocesium, elle se manifeste de facon sensible a partir de 700 Degree-Sign C et s'intensifie avec l'augmentation de la temperature. Les auteurs montrent que le radiocesium se condense sur les parois des tuyaux d'ecoulement a une temperature inferieure 3. 400 Degree-Sign C et qu'il peut etre facilement elue au moyen d'une faible solution d'acide nitrique et d'eau. Il ressort du calcul de la chaleur degagee par du verre radioactif que le rayon d'une boule de verre contenant une substance fortement radioactive (10 c/g) ne doit pas depasser 25 cm. Le memoire expose les diverses phases du procede de dessiccation et de vitrification des pates radioactives, qui est fonde sur l'utilisation du gaz comme conducteur thermique. Il indique en outre l'appareillage necessaire a cet effet. (author) [Spanish] Los autores exponen los resultados de la aplicacion de un metodo de laboratorio para la solidificacion de efluentes radiactivos, basado en el secado y la vitrificacion del hidroxido de

  15. Marcel Duchamp, Constantin Brancusi, Victor Brauner : leurs rencontres et les retombées sur leurs œuvres

    Directory of Open Access Journals (Sweden)

    Cristian-Robert Velescu

    2013-12-01

    Full Text Available Duchamp avait rencontré Brancusi en 1912, année qui marque le début d’une amitié consignée par l’histoire de l’art. Son parcours avait été fixé dans les pages de leur correspondance, conservées au Centre Georges Pompidou. Le lecteur est surpris de constater qu’il n’y a que des faits anodins qui soient consignés, tandis que les références aux conceptions artistiques sont presque totalement absentes. Toutefois, en lisant les témoignages de Duchamp conservés dans les célèbres Boîtes (verte et blanche, on se rend compte qu’il partage les conceptions platoniciennes de son ami sculpteur, chose importante, qui nous laisse formuler des suppositions concernant une influence dirigée de Brancusi dans la direction Duchamp. À son tour, durant l’intervalle 1925–1928, Victor Brauner était l’hôte de Brancusi dans l’atelier de l’impasse Ronsin. C’est ici qu’il a pu rencontrer Duchamp, qui s’y rendait fréquemment dans les années 20. Une rencontre qui a certainement eu des retombées sur l’oeuvre du futur peintre surréaliste. La preuve en est dans deux de ses toiles, Tête et deux boxeurs et Passivité courtoise. Faut-il s’étonner que le message que Duchamp avait mis dans les structures sémantiques de son chef-d’oeuvre La Mariée mise à nu par ses célibataires, même ou Le Grand Verre y avait été « logé » d’une manière évidente ? Mais alors on doit reconnaître que lors de leurs rencontres de chez Brancusi, Duchamp avait transmis à Brauner des informations très précises sur l’iconographie du Grand Verre, ainsi que sur la quatrième dimension, que le futur peintre surréaliste allait reconvertir dans les trois dimensions de l’espace ordinaire. Perçu dans cette perspective, l’atelier de l’impasse Ronsin nous semble un lieu où les idées des trois artistes ont pu communiquer d’une manière osmotique.

  16. Anomalous dielectric relaxation in lithium-potassium tantalate crystals

    Science.gov (United States)

    Doussineau, P.; Farssi, Y.; Frénois, C.; Levelut, A.; Toulouse, J.; Ziolkiewicz, S.

    1994-08-01

    In order to describe the unusual dielectric properties observed in Ki{1-χ}Li{χ}TaO3. crystals a new approchh is proposed. The dynamical Glauber theory, previously applied to spinglasses, is modifiéd by the introduction of the spectral distribution of the random interactions between the dipoles associated with the Li+ ions. Moreover, the dipole corrélations are taken into account by the Onsager réaction field. As a result, the calculated dielectric constant reproduces well the unusual features of the Argand diagrams and, in particular, their finite slope at low frequencies and infinite slope at high frequencies (strophoidal shape). The temperature dépendance of some parameters shows, however, the limits of a spin-glass type model in describing the collective behaviour of randomly distributed dipoles in a highly polarizable medium. Une nouvelle approche est présentée qui permet de décrire les propriétés diélectriques particulières de cristaux mixtes de Ki{1-χ}Li{χ}TaO3. Elle s'appuie sur la théorie dynamique de Glauber, déjà utilisée pour les verres de spins, et modifiée par l'introduction d'une distribution spectrale spécifique aux interactions aléatoires des dipôles électriques associés aux ions Li+. En outre, les corrélations entre dipôles sont prises en compte par le champ de réaction d'Onsager. II s'ensuit que la constante diélectrique complexe ainsi calculée reproduit fidèlement les particularités des diagrammes d'Argand, telles que la pente finie aux basses fréquences et la pente infinie aux hautes fréquences (forme strophoïdale). La dépendance en température de certains paramètres déterminés par le calcul montre les limites de l'analogie avec les verres de spins et met en évidence le rôle d'un réseau très polarisable dans le comportement collectif d'une assemblée de dipôles électriques.

  17. Efficacité du renforcement des poutres en béton armé par des matériaux composites Efficiency of strengthening concrete beams using FRP

    Directory of Open Access Journals (Sweden)

    Chemrouk M

    2012-09-01

    Full Text Available Pour réduire le coût et assurer un comportement relativement plus ductile pour des éléments en béton armés renforcés, l’addition des fibres de verre pourrait être considérée comme solution de rechange, puisqu’elles sont relativement plus déformables et meilleur marché que la fibre de carbone. Dans ce sens, le travail actuel vise à évaluer l’efficacité du renfort externe sur les poutres renforcées par le tissu de FRP (verre-carbone. Un total de sept poutres en béton armé a été renforcé en flexion et en cisaillement, et testé sous un chargement quatre points cyclique statique. Les champs des contraintes et de déformation ont été contrôlés par un système de caméra numérique “Gom-Aramis”. Les résultats ont été analysés en termes de résistance, rigidité, ductilité et mode de rupture. To reduce the cost and to ensure a behavior relatively more ductile for concrete strengthening elements, the addition of glass fibers could be regarded as solution of replacement, since they are relatively more deformable and cheaper than carbon fiber. In this sense, current work aims at evaluating the effectiveness of the external reinforcement on the beams strengthened by fabric of FRP (glass – carbon. Seven concrete beams reinforced were strengthening in bending and shearing, and were testing under four point cyclic static. The fields of the stresses and deformation were controlled by a numerical system of camera “Gom-Aramis”. The results were analyzing in term of resistance, rigidity, ductility and mode of failure

  18. Understanding of the mechanical and structural changes induced by alpha particles and heavy ions in the French simulated nuclear waste glass

    Energy Technology Data Exchange (ETDEWEB)

    Karakurt, G., E-mail: karakurt_gokhan@yahoo.fr [SUBATECH, UMR 6457CNRS-IN2P3, Ecole des Mines de Nantes, 4 rue Alfred Kastler, 44307 Nantes (France); Abdelouas, A. [SUBATECH, UMR 6457CNRS-IN2P3, Ecole des Mines de Nantes, 4 rue Alfred Kastler, 44307 Nantes (France); Guin, J.-P.; Nivard, M. [Institut de Physique de Rennes, Université de Rennes 1 – UMR 62051 IPR, 263 avenue du Général Leclerc, 35042 Rennes (France); Sauvage, T. [Laboratoire CEMHTI (Conditions Extrêmes et Matériaux: Haute Température et Irradiation), CNRS UPR, 3079 Orléans (France); Paris, M. [Institut des Matériaux Jean ROUXEL, Université de Nantes, UMR 6502 CNRS, 2 rue de la Houssinière, BP 32229, 44322 Nantes Cedex 03 (France); Bardeau, J.-F. [Institut des Molécules et Matériaux du Mans, UMR CNRS 6283, avenue Olivier Messiaen, 72085 Le Mans (France)

    2016-07-15

    Borosilicate glasses are considered for the long-term confinement of high-level nuclear wastes. External irradiations with 1 MeV He{sup +} ions and 7 MeV Au{sup 5+} ions were performed to simulate effects produced by alpha particles and by recoil nuclei in the simulated SON68 nuclear waste glass. To better understand the structural modifications, irradiations were also carried out on a 6-oxides borosilicate glass, a simplified version of the SON68 glass (ISG glass). The mechanical and macroscopic properties of the glasses were studied as function of the deposited electronic and nuclear energies. Alpha particles and gold ions induced a volume change up to −0.7% and −2.7%, respectively, depending on the glass composition. Nano-indentations tests were used to determine the mechanical properties of the irradiated glasses. A decrease of about −22% to −38% of the hardness and a decrease of the reduced Young's modulus by −8% were measured after irradiations. The evolution of the glass structure was studied by Raman spectroscopy, and also {sup 11}B and {sup 27}Al Nuclear Magnetic Resonance (MAS-NMR) on a 20 MeV Kr irradiated ISG glass powder. A decrease of the silica network connectivity after irradiation with alpha particles and gold ions is deduced from the structural changes observations. NMR spectra revealed a partial conversion of BO{sub 4} to BO{sub 3} units but also a formation of AlO{sub 5} and AlO{sub 6} species after irradiation with Kr ions. The relationships between the mechanical and structural changes are also discussed. - Highlights: • Mechanical and structural properties of two borosilicate glass compositions irradiated with alpha particles and heavy ions were investigated. • Both kinds of particles induced a decrease of the hardness, reduced Young's modulus and density. • Electronic and nuclear interactions are responsible for the changes observed. • The evolution of the mechanical properties under irradiation is linked

  19. Understanding of the mechanical and structural changes induced by alpha particles and heavy ions in the French simulated nuclear waste glass

    International Nuclear Information System (INIS)

    Karakurt, G.; Abdelouas, A.; Guin, J.-P.; Nivard, M.; Sauvage, T.; Paris, M.; Bardeau, J.-F.

    2016-01-01

    Borosilicate glasses are considered for the long-term confinement of high-level nuclear wastes. External irradiations with 1 MeV He + ions and 7 MeV Au 5+ ions were performed to simulate effects produced by alpha particles and by recoil nuclei in the simulated SON68 nuclear waste glass. To better understand the structural modifications, irradiations were also carried out on a 6-oxides borosilicate glass, a simplified version of the SON68 glass (ISG glass). The mechanical and macroscopic properties of the glasses were studied as function of the deposited electronic and nuclear energies. Alpha particles and gold ions induced a volume change up to −0.7% and −2.7%, respectively, depending on the glass composition. Nano-indentations tests were used to determine the mechanical properties of the irradiated glasses. A decrease of about −22% to −38% of the hardness and a decrease of the reduced Young's modulus by −8% were measured after irradiations. The evolution of the glass structure was studied by Raman spectroscopy, and also 11 B and 27 Al Nuclear Magnetic Resonance (MAS-NMR) on a 20 MeV Kr irradiated ISG glass powder. A decrease of the silica network connectivity after irradiation with alpha particles and gold ions is deduced from the structural changes observations. NMR spectra revealed a partial conversion of BO 4 to BO 3 units but also a formation of AlO 5 and AlO 6 species after irradiation with Kr ions. The relationships between the mechanical and structural changes are also discussed. - Highlights: • Mechanical and structural properties of two borosilicate glass compositions irradiated with alpha particles and heavy ions were investigated. • Both kinds of particles induced a decrease of the hardness, reduced Young's modulus and density. • Electronic and nuclear interactions are responsible for the changes observed. • The evolution of the mechanical properties under irradiation is linked to the changes occured in the

  20. Hydrogen initiative: An integrated approach toward rational nanocatalyst design for hydrogen production. Technical Report-Year 1

    Energy Technology Data Exchange (ETDEWEB)

    Vlachos, Dionisios G. [Univ. of Delaware, Newark, DE (United States); Buttrey, Douglas J. [Univ. of Delaware, Newark, DE (United States); Lauterbach, Jochen A. [Univ. of Delaware, Newark, DE (United States)

    2007-03-29

    , especially at lower temperatures. It has been found that the promoting effect is not limited to K but extendible to some other alkaline metals. In addition, we have studied a number of synthesis variables, including the effects of support, solvent used, calcination temperature and time. It has been found that solvent and support could have an important effect on activity. Advanced characterization of the Ru/K promoted catalyst has been carried via SEM, TEM, selected-area electron diffraction, and energy dispersive x-ray spectroscopy. It has been found that the Ru catalyst is composed of agglomerates, whereas the K-promoted catalyst of “nanowhiskers” with a KRu4O8 hollandite structure. Our detailed characterization studies strongly suggest for the first time a strong correlation between hollandite formation and the high activity of Ru catalyst. Future work should provide stronger evidence of this correlation and may enable us to further improve the catalyst. A number of microkinetic models for single metals have been developed and a methodology for linking models for bimetallic catalysts in a thermodynamically consistent manner has been implemented. This enables us for the first time to start exploring multi-site catalysts, using either mean-field or Monte Carlo approaches, and filling the materials gap from single crystals to supported catalysts. In addition, we are developing a multiscale model-based design of experiments methodology. This framework employs multiscale-based models combined with global search in experimental parameter space, identification of novel experimental conditions that maximize the kinetic information content, followed by statistical analysis that can guide the next iteration of experiments.

  1. L’arcipelago postmoderno. Oreste del Buono e gli anni Settanta

    Directory of Open Access Journals (Sweden)

    Andrea Chiurato

    2012-12-01

    Il tentativo di cooptazione postuma tra le file dei simpatizzanti da parte del Gruppo 63 avrà breve fortuna (verrà incluso nella prima antologia del gruppo, ma non nelle se-guenti, e Renato Barilli arriverà addirittura a porlo a capo di un improbabile «Polo Bu-tor» (Chiurato 14, uno sparuto gruppo di „infiltrati‟ (insieme a Raffaele La Capria, Emilio Tadini, e Giuliano Gramigna nelle file della compagine neoavanguardista. Quarant‟anni dopo la questione rimane aperta e l‟eredità di quel turbolento periodo è ancora oggetto di discussione. La nostra intenzione è proporre un approccio diverso, che cer-chi di restituire la fluidità e la ricchezza delle suggestioni di allora poi irrigiditesi in cate-gorie critiche spesso frutto di semplificazioni indebite. Del Buono, irriducibile outsider, ci permette così di riscoprire gli anni Settanta da un‟angolazione inedita e di colmare, nello stesso tempo, alcune improvvide lacune nella nostra memoria culturale

  2. Low field scaling properties of high Tc superconductor glasses

    Science.gov (United States)

    Giovannella, C.; Fruchter, L.; Chappert, C.

    We show that the zero field cooling (ZFC) M/H curves of both the YBaCuO and the LaSrCuO granular superconductor glasses (SuG) are subjected to scaling when plotted against the reduced variable t/H1/ψ . The breaking of the scaling for too weak or too strong magnetic fields is discussed and justified by the introduction of a phenomenological fractal picture, describing the behaviour of the disordered intergranular junction network. Nous montrons que les courbes M/H caractéristiques des verres de supraconducteurs granulaires sont sujettes à une loi d'échelle lorsqu'elles sont tracées en fonction de la variable réduite t/H1/ψ. La brisure de la loi d'échelle pour des champs trop forts ou trop faibles est justifiée par l'introduction d'un modèle phénoménologique fractal capable de décrire le comportement d'un réseau désordonné des jonctions.

  3. The Tragedy of Migrants. Gabriele Del Grande's Reportage

    Directory of Open Access Journals (Sweden)

    Luigi Franchi

    2017-11-01

    Full Text Available L’espressione "Tragedia dei migranti" che ciclicamente compare nei notiziari televisivi, seppur evocando la categoria del tragico, non suscita nessuno dei sentimenti che caratterizzano questa forma di spettacolo. Lo spettatore infatti è portato a considerare i naufragi nel Mediterraneo il frutto di un destino ineluttabile, senza quindi intravedere alcuna possibilità da parte sua di intervenire sulla realtà. Mamadou va a morire e Il mare di mezzo di Gabriele Del Grande dimostrano come i naufragi dei migranti nel Mediterraneo non siano parte del disegno divino di un deus absconditus, ma una delle drammatiche conseguenze della crisi economica della contemporaneità. Esibendo i meccanismi sottesi al fenomeno della migrazione, l’autore mostra i presupposti razionali sui quali questa si fonda e suggerisce come i suoi esiti drammatici possano essere contrastati a livello individuale e collettivo. Questo articolo si propone di dotare di un senso più pieno l’espressione "tragedia dei migranti": per fare ciò si rintraccerà all’interno dei reportage la riemersione di alcuni topoi della tragedia greca. Verrà inoltre individuata tra gli individui incontrati da Del Grande nei suoi viaggi e i personaggi della tragedia greca una serie di analogie in grado di restituire alla condizione del migrante una reale potenzialità tragica.

  4. Pétrographie du kérogène dans le Paléozoïque inférieur : méthode de préparation et exemple d'application Petrography of Lower-Paleozoic Kerogen: Preparation Method and Applied Example

    Directory of Open Access Journals (Sweden)

    Bertrand R.

    2006-11-01

    Full Text Available Une nouvelle méthode de préparation des matières organiques dispersées, destinées à être étudiées au microscope, est décrite et proposée. Le montage de la matière organique est fait par des lames de verre. Il permet de faire tous les types d'observations microscopiques (lumière transmise, réfléchie ou fluorescente sur une même préparation. Ses avantages sur la méthode classique d'imprégnation sur des briquettes sont illustrés par un exemple dans la séquence ordovicienne et siluro-dévonienne de l'île d'Anticosti et de l'est des Appalaches québécoises au Canada. This paper presents a new method to be used in the preparation of dispersed organic matter for microscopic studies. The organic matter is spread on a glass slide in order to permit all types of microscopic observation (transmitted, reflected or fluorescent light on a single mount. An example of its application, taken from the Ordovician and Siluro-Devonian sequence of Anticosti Island and Eastern Appalachians of Quebec, shows the advantages of this new method over the traditional plugmethod.

  5. Radial Fingering in a Porous Medium Digitation radiale dans un milieu poreux

    Directory of Open Access Journals (Sweden)

    Ni W.

    2006-11-01

    Full Text Available The theory of immiscible radial displacement in a Hele-Shaw cell is extended to the case of a porous medium contained between two closely-spaced parallel plates, and experiments are described for the displacement of glycerine by paraffin oil in such a system. Data are presented for the number of fingers, the breakthrough time, and the glycerine recovery, for a range of flowrates varying through three orders of magnitude. Good agreement between theory and experiment is observed. La théorie s'appliquant aux déplacements radiaux dans les cellules Hele-Shaw a été étendue à un système qui consiste en une couche mince de milieux poreux encapsulée entre deux plaques en verre. Dans cet article, on examine les déplacements de la glycérine par de l'huile de paraffine. En faisant varier le débit de l'huile de paraffine dans un intervalle de trois ordres de grandeur, on a étudié les variables telles que le nombre de digitations, le temps de percée et le taux de récupération de la glycérine. On a observé un bon accord entre la théorie et les résultats expérimentaux.

  6. Conoscere il patrimonio architettonico: il DARDUS dell’Università Politecnica delle Marche

    Directory of Open Access Journals (Sweden)

    Eva Savina Malinverni

    2007-03-01

    Full Text Available E’ in questa ottica che all’interno del Dipartimento collaborano docenti e ricercatori di vari settori scientificodisciplinari. Nella panoramica che viene qui presentata verrà posto l’accento maggiormente su due filoni di attività che sono anche più inerenti al contesto divulgativo di GEOmedia: il rilievo ed i sistemi informativi. Tematiche sulle quali il gruppo di ricerca del DARDUS ha avviato varie iniziative che verranno di seguito illustrate. Le dinamiche di collaborazione e di ricerca inerenti i temi del rilievo e della documentazione in banche datigeoreferenziate sviluppate nelle sale del Dipartimento riguardano non solo l’ambito architettonico ma anche quello ambientale. Queste attività sono svolte all’interno di laboratori debitamente attrezzati, nei quali docenti, ricercatori e tecnici istruiscono dottorandi, laureandi etirocinanti in stretta collaborazione e produttiva sinergia portando a sviluppare e collaudare nuove procedure e sistemi integrati di acquisizione e gestione dei dati raccoltinella varie esperienze di studio.

  7. RMQ13 – Commedia Quantistica Relativistica: un Teatro per la Scienza

    Directory of Open Access Journals (Sweden)

    Carlo Cosmelli

    2014-12-01

    Full Text Available Nel presente articolo si vogliono discutere brevemente le caratteristiche dei ‘prodotti’ che si possono trovare e che vengono catalogati usualmente come ‘Teatro Scienza’. In particolare ci si soffermerà sul tipo di spettacolo che esula dal semplice excursus storico di un fatto di rilevanza scientifica, o dalle vicende personali di una persona di scienza, così come dagli spettacoli che si dichiarano specificatamente didattici. Lo spettacolo tipo di cui si parlerà sarà uno spettacolo che, tralasciando le esemplificazioni formali, vuole trasmettere emozioni e idee scientifiche. Nello specifico verrà analizzato un esperimento in corso da due anni alla Sapienza nell’ambito del Corso di Laurea in Arti e Scienze dello Spettacolo. This article aims at analysing the features of works that come under the label of ‘Science Theatre’, not only in terms of plays that depict a scientific event or a scientist’s biography, but especially the ones that try to convey scientific emotions and ideas. The case study will focus on an experiment that has been carried for two years as part of BA course in Performing Arts at Sapienza Università di Roma.

  8. Geneva University

    CERN Multimedia

    2009-01-01

    École de physique - Département de physique nucléaire et corpusculaire 24, quai Ernest-Ansermet 1211 GENÈVE 4 Tél: (022) 379 62 73 - Fax: (022) 379 69 92 Lundi 6 avril 2009 PARTICLE PHYSICS SEMINAR àt 17:00 – Auditoire Stückelberg Hospital superbugs, nanomechanics and statistical physics Prof. Dr G. Aeppli / University College London The alarming growth of the antibiotic-resistant superbug, methicillin-resistant Staphylococcus aureus (MRSA) is driving the development of new technologies to investigate antibiotics and their modes of action. We report silicon cantilever based studies of self-assembled monolayers of mucopeptides which model drug-sensitive and resistant bacterial walls. The underlying concepts needed to understand the measurements will simplify the design of cantilevers and coatings for biosensing and could even impact our understanding of drug action on bacteria themselves. (Une verrée en compagnie du conférencier sera offerte après le colloque.) Organizer : Prof. Markus Büttiker ...

  9. Interfon

    CERN Multimedia

    Interfon

    2011-01-01

      Assemblée générale de la Mutuelle Vendredi 25 novembre à 18h30 Cafétéria Jean Monnet – St-Genis Au cours de cette soirée vous seront présentés : le compte-rendu des activités de l’année 2011, le bilan de la gestion financière pour l’année 2010, les nouvelles cotisations pour l’année 2012. Enfin le traditionnel verre de l’amitié sera offert à l'issue de cette soirée. * * * * * * * Idées de cadeaux de Noël !!!   Découvrez le site internet : www.viedetoffe.com * * * * * * * Z.A. de la Maladière 01210 Ornex www.imaginetson.com Votre spécialiste de l’image & du son dans le Pays de Gex Plus de 300 m² d’exposition dédiés &...

  10. Immagini dietro le sbarre: l’utilizzo della fotografia per lo sviluppo dell’intelligenza emotiva dei detenuti

    Directory of Open Access Journals (Sweden)

    Emanuela Saita

    2015-12-01

    Full Text Available Nel presente contributo verrà descritto un intervento che utilizza tecniche fotografiche in attività trattamentali rivolte a soggetti in condizione di detenzione, attività le cui finalità sono la risocializzazione e la rieducazione del reo. Scopo dell'intervento è favorire lo sviluppo dell'intelligenza emotiva (IE, intesa come la capacità di comprendere e riconoscere i propri e gli altrui stati emotivi; essa infatti è associata in letteratura ad una riduzione della recidiva e ad un aumentato benessere dei soggetti reclusi. Le tecniche fotografiche costituiscono uno strumento in grado di superare barriere linguistico-culturali ed eventuali resistenze individuali per far emergere contenuti simbolici connessi a stati emotivi, credenze o percezioni. L'intervento descritto prevede incontri di gruppo, una tipologia di setting che diviene possibile strumento di apprendimento, riflessione sul sé, oltre che luogo di confronto e possibile cambiamento. La struttura degli incontri è tale da perseguire sia l'obiettivo generale (sviluppo dell'IE che obiettivi più specifici, calibrati su differenti categorie di detenuti. Ad esempio, favorire il reinserimento dopo la detenzione in caso di pene medio/brevi, piuttosto che l’accettazione della pena e l’adattamento alla vita carceraria, nel caso di pene più lunghe. Il contributo si chiude con un’apertura sulle possibili modalità di valutazione di tale intervento, al fine di giungere alla formulazione di un protocollo generalizzabile e applicabile a differenti contesti.

  11. Ricerca empirico-sperimentale in pedagogia… Alcuni appunti su riflessione teorica e sistematicità metodologica.

    Directory of Open Access Journals (Sweden)

    Ira Vannini

    2009-07-01

    Full Text Available In questo breve saggio, si vogliono ripercorrere le fasi principali attraverso le quali si sviluppa un percorso di ricerca empirica e sperimentale in educazione, allo scopo di riflettere su alcune questioni importanti che si propongono al ricercatore durante il suo lavoro di indagine. Negli ultimi decenni, il dibattito nazionale e internazionale a questo proposito è stato molto vivace e complesso; la presente trattazione non pretende dunque di essere in alcun modo esaustiva, bensì mira a delineare i momenti più significativi che caratterizzano un itinerario di indagine e a sottolineare il valore del fare ricerca in educazione quale prassi – di pensiero e di azione – che esige di essere, da un lato, teoricamente fondata e, dall’altro lato, metodologicamente rigorosa. Nel saggio verrà prediletto l’approccio più propriamente sperimentale e quantitativo, al fine di evidenziarne le peculiarità e le valenze nell’ambito della ricerca empirica in pedagogia; tale approccio sarà tuttavia analizzato e discusso criticamente alla luce delle più recenti riflessioni sui paradigmi teorici della ricerca nelle scienze sociali e sulle possibilità e i limiti dell’integrazione, teorica e metodologica, tra approcci quantitativo e qualitativo.

  12. Il controllo di gestione e operativo delle commesse per una impresa di costruzioni: nuovo impianto di trattamento e recupero di rifiuti urbani.

    Directory of Open Access Journals (Sweden)

    Matteo Camprini

    2013-10-01

    Full Text Available Il mercato delle costruzioni in Italia soffre problemi di maturità da molto tempo. Dagli anni ’90, infatti, per superare i fatti di tangentopoli venne riformata la legislazione dei lavori pubblici per giungere a livelli di competizione maggiori e più simili a quelli esistenti in Europa.  In questo contesto le imprese che per la loro struttura culturale, organizzativa e produttiva mostravano maggiore sensibilità a tali aspetti avviarono processi di formazione e riorganizzazione introducendo specifiche procedure mirate alla gestione completa dei progetti trasformandosi così da imprese di sola produzione a imprese operanti per progetti.La presente memoria vuole descrivere il sistema di gestione attuato, le modifiche ed i miglioramenti che si sono susseguiti nel tempo,  la sua struttura organizzativa e gli strumenti di lavoro messi a disposizione.A conclusione verrà illustrata l’applicazione al caso concreto della costruzione del nuovo impianto di trattamento e recupero di rifiuti urbani.

  13. An experimental propane bubble chamber; Sur une chambre a bulles experimentale a propane

    Energy Technology Data Exchange (ETDEWEB)

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

    1957-07-01

    Describes a propane bubble chamber 10 cm in diameter and 5 cm deep. The body of the chamber is in stainless steel, and it has two windows of polished hardened glass. The compression and decompression of the propane are performed either through a piston in direct contact with the liquid, or by the action on the liquid, through a triple-mylar-Perbunan membrane, of a compressed gas. The general and also optimum working conditions of the chamber are described, and a few results are given concerning, in particular, the tests of the breakage-resistance of the windows and the measurements of the thermal expansion of the compressibility isotherm for the propane employed. (author) [French] Description d'une chambre a bulles a propane de 10 cm de diametre et de 5 cm de profondeur. La chambre, dont le corps est en acier inoxydable, est munie de deux fenetres en verre poli et trempe. La compression et la detente du propane sont effectuees, soit a l'aide d'un piston en contact direct avec le liquide, soit en faisant agir sur ce dernier un gaz comprime a travers une triple membrane de teflon-mylar-perbunan. On decrit les conditions generales, ainsi que les conditions optimales de fonctionnement de la chambre et l'on signale un certain nombre de resultats obtenus concernant, notamment, les essais de resistance a la rupture des fenetres et les mesures de dilatation thermique de compressibilite isotherme du propane utilise. (auteur)

  14. Úzkopásmová PLC komunikace s vysokou datovou rychlostí na bázi OFDM techniky

    OpenAIRE

    Csiba, Patrik

    2015-01-01

    Tato bakalářská práce se zabývá úzkopásmovou PLC komunikací. V práci je popisována historie, princip úzkopásmové komunikace a popis čtyř dostupných úzkopásmových standardů (PRIME, G3-PLC, G.hnem, IEEE P1901.2) s jejich porovnáním. V další části jsou popisována experimentální měření, která jsou prováděna v domácím prostředí za použití dostupných modemů TMDSPLCKIT od firmy Texas Instruments, MT39-L1-ver.R modemů od firmy ModemTec a EVALKITST7580-1 od firmy STMicroelectronics. This bachelor p...

  15. The isotope-dilution method of fluorine microestimation; Microdosage du fluor pur dilution isotopique; Mikroopredelenie ftora no metodu razbavleniya izotopov; Microvaloracion del fluor por dilucion isotopica

    Energy Technology Data Exchange (ETDEWEB)

    Kudahl, J N; Fremlin, J H; Hardwick, J L [Department of Physics, University of Birmingham (United Kingdom)

    1962-01-15

    Fluoride ions are adsorbed on glass from acid solution and, for solutions containing less than 100 ppm of fluorine, the amount adsorbed varies very regularly with concentration. A certain volume of a carrier-free solution of the unstable isotope F{sup 18} is added to each of a set of acid fluoride solutions which may be a few milligrams, or less, in size. If the solutions are applied to a defined area of glass, some of the F{sup 18} is adsorbed and this can be fixed by raising the pH when equilibrium has been reached. The radioactivity of the glass is a measure of the total amount of fluoride on the glass and can be used to draw an adsorption isotherm from which the fluorine content of an unknown solution in the set can be found. The effects of pH, and the presence of calcium and phosphate ions have been studied, and it has been shown that organic materials may be ashed safely if calcium or magnesium ions are present. The accuracy of the method is independent of the fluoride concentration down to concentrations of a fraction of a ppm. (author) [French] L'ion de fluorure d'une solution acide est adsorbe sur du verre; pour des solutions contenant moins de 100 ppm de fluor, la quantite adsorbee varie tres regulierement en fonction de la concentration. Un certain volume d'une solution, sans entraineur-, de l'isotope instable {sup 18}F est ajoute a une serie de solutions acides de fluorure; il peut s'agir de quantites de l'ordre de quelques milligrammes, ou meme moins. Si l'on applique les solutions sur une surface bien definie de verre, une partie du {sup 18}F est adsorbee; on peut la fixer en augmentant le pH des que l'equilibre a ete realise. La radioactivite du verre donne la mesure de la quantite totale de fluorure fixe sur le verre; elle peut servir a etablir l'isotherme d'adsorption, dont en peut deduire la teneur en fluor de toute solution de la serie. Les auteurs ont etudie les effets du pH et la presence d'ions de calcium et de magnesium; ils ont montre que

  16. Die Kunst des klugen Handelns 52 Irrwege, die Sie besser anderen überlassen

    CERN Document Server

    Dobelli, Rolf

    2012-01-01

    Unzählige Leser begeistern sich für Rolf Dobellis gescheite Texte über unsere häufigsten Denkfehler. Doch wer Dobellis Ratschläge zum klaren Denken beherzigt, ist noch lange nicht aus dem Schneider, denn auf dem Weg vom Denken zum Handeln lauern weitere Fallstricke. Glücklicherweise kann man die umgehen - wenn man weiß, wie. Genau das verrät "Die Kunst des klugen Handelns": In 52 Kapiteln zeigt Dobelli, warum es sich lohnt, Türen zu schließen und auf Optionen zu verzichten, warum Informationsüberfluss zu unklugem Handeln anstiftet, warum Geld stets in emotionale Kleider gehüllt ist und wir es darum oft unbedacht ausgeben. Rolf Dobelli gibt Ihnen das nötige Rüstzeug: Schlagen Sie nicht jeden Irrweg ein, nur weil andere ihn gehen. Lernen Sie aus den Fehlern, die andere freundlicherweise für Sie machen. Denken Sie klar und handeln Sie klug!

  17. A new LIFE: oltre la didattica d'aula.

    Directory of Open Access Journals (Sweden)

    Simona Scarsella

    2009-10-01

    Full Text Available A partire dal dibattito che oggi contrappone i Personal Learning Environment (PLE ai Virtual Learning Environment (VLE e le pratiche del cosidetto Learning 2.0 alle 'vecchie' pratiche educative on-line, il tutorial introdurrà€ gli uditori al Design di processi e ambienti educativi ispirati dall'idea che l'apprendimento è 'esperienza che si nutre di esperienze', nell'ambito delle quali deve essere possibile valorizzare sia le potenzialità€ della collettività€ che le caratteristiche del singolo.I partecipanti verranno altresì€ introdotti ad alcuni principi e metodiche del Design e del Co-Design che - secondo la filosofia del 'Person in Place Centered Design' - possono ispirare la trasformazione degli attuali 'learning space', spesso non-luoghi dell'apprendimento, in 'learning place', che in prospettiva potrebbero delocalizzarsi sino a diluirsi negli ambienti e nelle pratiche del vivere quotidiano assumendo caratteristiche di adattabilità€ e responsività€ tali da renderli 'place' ideali anche per trasformare e rendere più€ motivante l'attuale didattica d'aula.Il tutorial verrà€ sviluppato utilizzando LIFE (Learning in Interactive Framework to Experience, un ambiente di formazione on-line, open-source, il cui design è€ stato ispirato dai principi sopra descritti.

  18. Die Entdeckung des Higgs-Teilchens oder wie das Universum seine Masse bekam

    CERN Document Server

    2013-01-01

    Im Oktober 2013 setzte der Nobelpreis für Peter Higgs und François Englert den vorläufigen Höhepunkt in der verrückten Geschichte um das sogenannte Gottesteilchen, das Higgs-Boson. Schon im Juli des Vorjahres hatten die Physiker weltweit gejubelt: Mehr als fünfzig Jahre nachdem Peter Higgs und andere Wissenschaftler die Existenz des Teilchens theoretisch begründet hatten, war es im gigantischen Teilchenbeschleuniger CERN gefunden worden. Jetzt erzählen Harald Lesch und seine Co-Autoren, warum sich rund um das Higgs-Teilchen so viele skurrile Missverständnisse und mediale Sensationen ranken. Gewohnt kurzweilig und gut verständlich enthüllen sie, wie aus dem verzweifelt gesuchten „gottverdammten Teilchen“ das Gottesteilchen wurde, dass der Urknall nicht simuliert werden kann und dass Schwarze Löcher nicht unbedingt alles verschlingende Monster sind. Dabei wird deutlich, dass die Suche nach den geheimnisvollen Kräften, die das Universum, unsere Erde und letztlich auch uns Menschen zusammenhalten...

  19. Bis(s) ins Innere des Protons ein Science Slam durch die Welt der Elementarteilchen, der Beschleuniger und Supernerds

    CERN Document Server

    Lemmer, Boris

    2014-01-01

    Geben Sie's zu, wir alle fragen gerne mal: „Was ist da drin?“. Und einige, die hören mit dem Fragen einfach nicht mehr auf. Sie haken nach, bis es als Antwort nur noch gibt: „Das war’s, kleiner geht’s nicht mehr.“ Da wo's klein wird, wird die Welt plötzlich ganz verrückt: Aus purer Energie werden Teilchen erzeugt. Materieteilchen bekommen Geschwister aus Antimaterie. Teilchen, die es eigentlich gar nicht geben dürfte, entstehen plötzlich aus dem Nichts. Das ist die Welt der Teilchenphysik. Teilchenphysiker bauen die größten Experimente aller Zeiten, um die kleinsten Teilchen des Universums zu untersuchen. Sie gehen an die Grenzen des technisch Machbaren und überschreiten dabei die Grenzen unserer Länder. Wer das alles auch so spannend findet wie die Teilchenphysiker selbst, ist herzlich eingeladen, dieses Buch zu lesen. Wer glaubt, dass man ohne ein Studium in der Teilchenphysik nichts versteht, der auch. Quantenfeldtheorien, Teilchenbeschleuniger, Higgs-Mechanismus und Co werden hier...

  20. Device for sampling sodium from a circuit with a view to dosing its impurities (1963); Dispositif de prelevement de sodium sur un cuicuit en vue du dosage des impuretes (1063)

    Energy Technology Data Exchange (ETDEWEB)

    Sannier, J; Vingot, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1963-07-01

    The device described was developed with the two following essential conditions in mind: - absence of any pollution during the sampling operation and the transfer to the analysis apparatus; - simultaneous extraction of several samples, each one remaining representative of the sodium in the circuit. The sampling is therefore carried out completely in a vacuum in a Pyrex-glass apparatus, this limiting the sodium temperature to a maximum of 240 deg. C. The samples are in the form of bulbs sealed in vacuo containing 2 to 3 grams of sodium each. The analysis of the oxygen by the amalgamation technique, carried out on samples obtained by this method show a very satisfactory reproducibility for concentrations of under 20 ppm. (authors) [French] Le dispositif decrit a ete mis au point compte tenu des deux imperatifs essentiels suivants: - absence de toute pollution pendant les operations de prelevement et de transport vers l'appareil d'analyse; - obtention simultanee de plusieurs echantillons, chacun restant representatif du sodium du circuit. A cet effet, le prelevement est effectue entierement sous vide dans un appareillage en verre Pyrex, ce qui limite la temperature du sodium a 240 deg. C. Les echantillons se presentent sous la forme d'ampoules scellees sous vide et contenant chacune 2 a 3 grammes de sodium. L'analyse de l'oxygene par la technique d'amalgamation, effectuee sur des echantillons preleves par cette methode, revele une reproductibilite tres satisfaisante, dans le domaine des teneurs inferieures a 20 ppm. (auteurs)

  1. Technical note concerning the use of cellulose ester filtering membranes in the determination of plutonium in urine; Note technique sur l'utilisation des membranes filtrantes d'esters de cellulose dans le dosage du plutonium dans les urines

    Energy Technology Data Exchange (ETDEWEB)

    Harduin, J C; Montels, P [Commissariat a l' Energie Atomique, la Hague (France)

    1968-07-01

    During the last stage of the determination of plutonium in biological media, cellulose ester filtering membranes are used for collecting, with the help of a special device, the very fine precipitate resulting from the co-precipitation of plutonium and lanthanum fluorides. The membranes are then dried, and stuck on to flat watch-glasses for a {alpha} counting. A method is then given for purifying the lanthanum so as to keep the background noise during counting as low as possible. (author) [French] Dans la phase terminale du dosage du plutonium dans les milieux biologiques, on utilise les membranes filtrantes d'esters de cellulose pour recueillir, a l'aide d'un dispositif particulier, le precipite tres tenu resultant de la co-precipitation plutonium-lanthane sous forme de fluorure - Les membranes sont ensuite sechees puis collees sur verre de montre plat avant d'etre passees au compteur alpha. Un mode de purification du lanthane est ensuite donne afin de ne pas augmenter le bruit de fond des appareils de comptage. (auteur)

  2. Interfon

    CERN Multimedia

    Interfon

    2013-01-01

    www.interfon.fr   Rendez-vous sur notre site pour toutes les « News » Interfon « News »   Situé au 1, rue de Lyon à Saint-Genis-Pouilly, « Optique du Lion » vous réserve un accueil chaleureux et un service personnalisé du mardi au vendredi. Tél :  04 50 28 05 33 – www.optiquedulion.com   Présentez votre carte de sociétaire et profitez de 14 % de remise ou d’une deuxième paire de lunettes en verres anti reflets Nous sommes indépendants et libres de pratiquer le métier que nous aimons comme nous l’aimons. Nous proposons les produits que nous avons personnellement sélectionnés. Nous prenons toujours le temps de vous écouter, pour cerner précisément vos attentes et vous recomma...

  3. Architectural Kansei of ‘Wall’ in The Façade Design by Le Corbusier

    Science.gov (United States)

    Sendai, Shoichiro

    The purpose of this paper is to discuss the modern architect Le Corbusier's architectural Kansei (sensibility) on wall in site environment through the analysis of his façade design, using Œuvres complètes (1910-1965, 8 vols., Les éditions d'architecture, Artemis, Zurich) and Le Corbusier Archives (1982-1984, 32 vols., Garland Publishing, Inc. and Fondation Le Corbusier, New York, London, Paris). At first, I arrange five façade types, according to the explanation by Le Corbusier ; ‘fenêtre en longueur (strip window)’, ‘pan de verre (glass wall)’, ‘brise-soleil (sun-breaker)’, ‘loggia’ and ‘claustra’. Through the analysis of the relationship between these types and the design process of each building, we find that Le Corbusier's façade design includes the affirmation and the negation of the ‘wall’ at the same time. In fact, the nature of façade modification during design process is divers: increase in transparency, decrease in transparency and spatialization of façade. That means, Le Corbusier studied the environmental condition by these façade types, and tried to realize the phenomenal openness. This trial bases on the function of architectural Kansei as correspondence between body and environment beyond the physical design.

  4. A rapid method of dosing plutonium in radioactive effluents; Methode de dosage rapide du plutonium dans les effluents radioactifs (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Scheidhauer, J; Messainguiral, L [Commissariat a l' Energie Atomique, Centre de Production de Plutonium, Marcoule (France). Centre d' Etudes Nucleaires

    1961-07-01

    The plutonium is first separated by a lanthanum fluoride precipitation. The precipitated fluorides are dissolved in normal nitric acid solution in the presence of aluminium nitrate. The plutonium transformed to the tetravalent state is then extracted with thenoyltrifluoroacetone and returned to the aqueous phase with 10 N nitric acid. After evaporation on a watch glass the residue is calcined on a Meker burner and counted using a counting system fitted with a zinc sulphide scintillator. When necessary, the calcium is eliminated at the beginning of the dosage by a fluoride precipitation, the plutonium being oxidised to the valency IV. (authors) [French] Le plutonium est d'abord separe par entrainement au fluorure de lanthane. Le precipite des fluorures est remis en solution en milieu acide nitrique normal, en presence de nitrate d'aluminium. Le plutonium amene a la valence IV est alors extrait par la thenoyltrifluoroacetone et remis en phase aqueuse dans l'acide nitrique 10 N. Apres evaporation sur verre de montre, le residu est calcine sur bec Meker et compte sur un ensemble de comptage equipe d'un scintillateur au sulfure de zinc. Lorsque cela est necessaire, le calcium est elimine, au debut du dosage, par precipitation du fluorure, le plutonium etant oxyde a la valence VI. (auteurs)

  5. La devozione alle icone medievali riscritta dal Concilio di Trento

    Directory of Open Access Journals (Sweden)

    Anita Paolicchi

    2016-06-01

    Full Text Available Il Concilio di Trento (1545-1563 determinò nuove esigenze liturgiche, che portarono a una rapida trasformazione e a un drastico rinnovamento delle chiese sia dal punto di vista strutturale che dell’arredo. Questo articolo desidera indagare i caratteri fondamentali di un fenomeno poco conosciuto e sicuramente sottovalutato della storia dell’arte moderna legata a questi cambiamenti: la ri-funzionalizzazione delle immagini medievali e bizantine, prendendo come esempio il caso toscano. In particolare verrà evidenziato come la percezione da parte dei fedeli di queste immagini si evolva nel corso dei secoli. || The Council of Trent (1545-1563 determined new liturgical requirements and specifications which brought to a rapid transformation and a radical renovation of churches from both a structural and an ornamental perspective. This article aims at investigating the fundamental features of a rarely studied and certainly underestimated artistic phenomenon of the post-Tridentine era: the changes in the function of medieval and Byzantine images, with a focus on Tuscan examples. In particular, we will examine how the worshippers’ perception of such images evolved over the centuries.

  6. INTERFON

    CERN Multimedia

    INTERFON

    2010-01-01

    Assemblée Générale de la Mutuelle Mardi 16 novembre à 18h30 Salle du Business Center Technoparc de St-Genis (entrée nord)   Au cours de cette soirée vous seront présentés : Le compte-rendu des activités de l’année 2010 Le bilan de la gestion financière pour l’année 2009 Les nouvelles cotisations pour l’année 2011 Enfin le traditionnel verre de l’amitié Clôturera cette soirée.   ******   Nouveau … Nous venons de passer un accord de partenariat avec le Cellier Mövenpick (Ch. du Grand Pré à Meyrin) où vous pourrez prochainement bénéficier de tarifs avantageux sur tous les vins en provenance du monde entier. Cet avantage sera consenti, dès le dé...

  7. Interfon

    CERN Multimedia

    Interfon

    2011-01-01

    Les membres du Conseil d’Administration ainsi que le personnel de la Coopérative et de la Mutuelle vous souhaitent un Joyeux Noël et une Bonne Année 2012 ! Nos bureaux seront fermés : Au CERN du 22 décembre au 4 janvier inclus Au Technoparc du 23 décembre au 1er janvier inclus Quelques idées de cadeaux à offrir ou à s’offrir ! Des billets d’entrée ou des abonnements, à tarifs réduits (15 % de réduction), pour le Vitam’Parc. A la Vinothèque du Leman (zone de l’Allondon à St-Genis) vous trouverez : verres à dégustation, carafes, paniers à bouteilles, écrins cadeaux … tout pour le parfait œnologue. Remise de 5 à 10 %. Mais également,  coffrets bois, panie...

  8. Itinerari Musicali con la Wiild

    Directory of Open Access Journals (Sweden)

    Elisabetta Nanni

    2013-03-01

    Full Text Available La Wiild, acronimo di Wiimote Lavagna Digitale, è uno strumento didattico che utilizza il telecomando della Wii, il famoso gioco della Nintendo, insieme a un software libero, rendendolo così estremamente versatile. Non vincolato a software proprietario, il suo utilizzo è legato alla capacità dell’insegnante di ripartire dalla didattica, dalle risorse selezionate e dall’epistemologia di ogni singola disciplina, trovando così nel proprio contesto un ruolo per le tecnologie. Il contributo presenta ipotesi di lavoro per l’educazione musicale nella scuola secondaria di primo grado che si sviluppano sia attraverso lo studio del rapporto suono/segno con affinità pittoriche e successiva codificazione grafica, sia attraverso un’attività di laboratorio in cui co-costruire percorsi storico-musicali. La Wiild diventerà davvero utile ed efficace nel momento in cui, affiancando le risorse selezionate dal docente, verrà utilizzata senza essere notata, giocando un ruolo di strumento tecnologico «normale e trasparente».

  9. Amorphous manganese-calcium oxides as a possible evolutionary origin for the CaMn₄ cluster in photosystem II.

    Science.gov (United States)

    Najafpour, Mohammad Mahdi

    2011-06-01

    In this paper a few calcium-manganese oxides and calcium-manganese minerals are studied as catalysts for water oxidation. The natural mineral marokite is also studied as a catalyst for water oxidation for the first time. Marokite is made up of edge-sharing Mn(3+) in a distorted octahedral environment and eight-coordinate Ca(2+) centered polyhedral layers. The structure is similar to recent models of the oxygen evolving complex in photosystem II. Thus, the oxygen evolving complex in photosystem II does not have an unusual structure and could be synthesized hydrothermally. Also in this paper, oxygen evolution is studied with marokite (CaMn₂O₄), pyrolusite (MnO₂) and compared with hollandite (Ba(0.2)Ca(0.15)K(0.3)Mn(6.9)Al(0.2)Si(0.3)O(16)), hausmannite (Mn₃O₄), Mn₂O₃.H₂O, Ca Mn₃O₆.H₂O, CaMn₄O₈.H₂O, CaMn₂O₄.H₂O and synthetic marokite (CaMn₂O₄). I propose that the origin of the oxygen evolving complex in photosystem II resulted from absorption of calcium and manganese ions that were precipitated together in the archean oceans by protocyanobacteria because of changing pH from ~5 to ~8-10. As reported in this paper, amorphous calcium-manganese oxides with different ratios of manganese and calcium are effective catalysts for water oxidation. The bond types and lengths of the calcium and manganese ions in the calcium-manganese oxides are directly comparable to those in the OEC. This primitive structure of these amorphous calcium-manganese compounds could be changed and modified by environmental groups (amino acids) to form the oxygen evolving complex in photosystem II.

  10. Some reduced ternary and quaternary oxides of molybdenum. A family of compounds with strong metal-metal bonds

    International Nuclear Information System (INIS)

    Torardi, C.C.; McCarley, R.E.

    1981-01-01

    Several new, reduced ternary and quaternary oxides of molybdenum are reported, each containing molybdenum in an average oxidation state 2 sealed in Mo tubes held at 1100 0 C for ca. 7 days. Refinement of the substructure of the new compound Ba 0 62 Mo 4 O 6 was based on an orthorhombic cells, with a = 9.509(2), b = 9.825(2), c = 2.853(1) A, Z = 2 in space group Pbam; weak supercell reflections indicate the true structure has c = 8(2.853) A. The chief structural feature is closely related to that of NaMo 4 O 6 which consists of infinite chains of Mo 6 octahedral clusters fused on opposite edges, bridged on the outer edges by O atoms and crosslinked by Mo-O-Mo bonding to create four-sided tunnels in which the Ba 2+ ions are located. The structure of Ba 1 13 Mo 8 O 16 is triclinic, a = 7.311(1), b = 7.453(1), c = 5.726(1) A, α = 101.49(2), β = 99.60(2), γ = 89.31(2) 0 , Z = 1, space group P1. It is a low-symmetry, metal-metal bonded variant of the hollandite structure, in which two different infinite chains, built up from Mo 4 O 8 2- and Mo 4 O 8 0 26- cluster units, respectively, are interlinked via Mo-O-Mo bridge bonding to create again four-sided tunnels in which the Ba 2+ ions reside. Other compounds prepared and characterized by analyses and x-ray powder diffraction data are Pb/sub x/Mo 4 O 6 (x approx. 0.6), LiZn 2 Mo 3 O 8 , , CaMo 5 O 8 , K 2 Mo 12 O 19 , and Na 2 Mo 12 O 19

  11. Manganese Ores from South Sulawesi: Their Potential Uses as Raw Materials for Metallurgical Industry

    Directory of Open Access Journals (Sweden)

    Sufriadin Sufriadin

    2017-03-01

    Full Text Available Characterization of manganese ores from Barru and Bone regencies of South Sulawesi has been conducted with the aim at clarification of their mineralogical and chemical composition for their potential uses as the raw materials for metallurgical industry. Mineralogical properties of the ores analyzed by means of optical microscopy and X-ray diffractometry (XRD show that samples from Barru consist mainly of rhodochrosite (MnCO3 with less cryptomelane, groutite, bixbyite, and todorokite. Goethite, calcite and small amount of quartz present as impurities. Manganese ore samples from Bone are predominantly composed of pyrolusite (MnO2 with subordinate ramsdellite and hollandite. Barite, quartz, hematite and clay are present as gangue minerals. Chemical compositions determined by using XRF method revealed that Barru samples contain higher in MnO (average is 40.07 wt% than the Bone samples (average is 34.36 wt%. Similarly, Fe2O3 and CaO are also higher in Barru than those of the Bone samples. In contrast, concentrations of SiO2 and total alkali (K2O + Na2O are lower in the Barru samples. The average P2O5 content of samples in both areas is low (<0.2 wt%. Relatively higher grade of Fe2O3 in the Barru ore implies that it has potential application for ferromanganese production; whereas the elevated SiO2 content of the Bone ore is a good indication for silicomanganese manufacture. However, both ores may not favorable to be directly used as raw materials in metallurgical uses. Prior to be used, the ores should be treated by applying physical beneficiation in order to reduce deleterious elements.

  12. DEVELOPMENT OF CERAMIC WASTE FORMS FOR AN ADVANCED NUCLEAR FUEL CYCLE

    Energy Technology Data Exchange (ETDEWEB)

    Marra, J.; Billings, A.; Brinkman, K.; Fox, K.

    2010-11-30

    A series of ceramic waste forms were developed and characterized for the immobilization of a Cesium/Lanthanide (CS/LN) waste stream anticipated to result from nuclear fuel reprocessing. Simple raw materials, including Al{sub 2}O{sub 3} and TiO{sub 2} were combined with simulated waste components to produce multiphase ceramics containing hollandite-type phases, perovskites (particularly BaTiO{sub 3}), pyrochlores and other minor metal titanate phases. Three fabrication methodologies were used, including melting and crystallizing, pressing and sintering, and Spark Plasma Sintering (SPS), with the intent of studying phase evolution under various sintering conditions. X-Ray Diffraction (XRD) and Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM/EDS) results showed that the partitioning of the waste elements in the sintered materials was very similar, despite varying stoichiometry of the phases formed. Identification of excess Al{sub 2}O{sub 3} via XRD and SEM/EDS in the first series of compositions led to a Phase II study, with significantly reduced Al{sub 2}O{sub 3} concentrations and increased waste loadings. The Phase II compositions generally contained a reduced amount of unreacted Al{sub 2}O{sub 3} as identified by XRD. Chemical composition measurements showed no significant issues with meeting the target compositions. However, volatilization of Cs and Mo was identified, particularly during melting, since sintering of the pressed pellets and SPS were performed at lower temperatures. Partitioning of some of the waste components was difficult to determine via XRD. SEM/EDS mapping showed that those elements, which were generally present in small concentrations, were well distributed throughout the waste forms.

  13. Perovskite as a matrix for incorporation of long-lived radionuclides

    International Nuclear Information System (INIS)

    Chernyavskaya, N.E.; Ochkin, A.V.; Chizhevskaya, S.V.; Stefanovskij, S.V.

    1998-01-01

    SYNROC is titanate ceramics consisting mainly of zirconolite, perovskite, and hollandite, developed to immobilize high level waste. Perovskite is able to incorporate strontium, yttrium, and trivalent lanthanides and actinides. The main goal of the present work is leaching study of various radionuclides from perovskite. Samples of perovskite-rich ceramics were produced by cold pressing of oxide mixture followed by firing in resistive furnace at 1350 degC for 3 hours. For leaching tests, ceramic pellets were crushed and surface areas were measured using argon thermal desorption technique. Leach rate was measured by boiling in a Soxhlet apparatus for 5 hours. Leach rates in 0.1 M HNO 3 and NaCl solutions were measured by boiling with stirrer and reverse cooler. Leach rate was controlled with radioactive indicator technique. Density of the perovskite-rich ceramic samples prepared was about 75% of theoretical. From XRD examination, the target phase (perovskite) yield was found to be about 95 vol.%. Minor rutile (≤ 5 vol.%) was also present. Leach rate of 90 Sr from Sr-doped perovskites with specified composition Ca 1-x Sr x TiO 3 did not depend on x until certain x value. Leach rate of 90 Sr from control zirconolite sample was by one order of magnitude higher than from perovskite. Leach rates of 147 Pm, 238 Pu, and 241 Am from perovskite ceramics with nominal perovskite composition had the same order of magnitude (about 10 -4 g/(m 2 day)). Substitution of 5 at.% Ce for Ca and 5 at.% Al for Ti lowered leach rate of 238 Pu by a factor of 6. Leach rates of 90 Sr in 0.1 M HNO 3 and NaCl solutions were three and one orders of magnitude higher than in distilled water

  14. Mineralogical characteristics of Mn coatings from different weathering environments in China: clues on their formation

    Science.gov (United States)

    Xu, Xiaoming; Ding, Hongrui; Li, Yan; Lu, Anhuai; Li, Yan; Wang, Changqiu

    2018-03-01

    Identification of Mn oxides in natural Mn coatings is very difficult due to their poor crystallinity, fine grains, complex chemistry and tiny amounts. In this work, we investigated three types of Mn coatings including rock varnish, dendrite and soil Fe-Mn cutan from different weathering environments in China. Optical microscope, scanning electron microscope, energy dispersive X-ray spectroscopy and micro-Raman spectrometer were employed to achieve non-destructive, sensitive, in-situ and micro analysis on their mineral assemblages, micromorphological features and elemental distribution characteristics. The observed results suggest that rock varnish and soil cutan comprise birnessite, while dendrite is mainly composed of hollandite. Rock varnish with a layered structure has a clear boundary with its substrate, and microlaminations which arise from the fluctuations in Mn content (6.42-17.07 wt%) within the sample profile are obvious on closer inspection. Branch-like dendrite is rich in Mn (32.53-42.96 wt%) but poor in Si and Al, which shows a pilotaxitic texture with its substrate. Soil Fe-Mn cutan can be further divided into an outer black Mn-rich (8.26-13.58 wt%) belt and an inner yellowish-brown Fe-rich (2.06-4.85 wt%) belt, and a clear border can be identified between these two belts. Mn in the substrate of rock varnish and soil cutan is below detection limit while it can be detected in the substrate of dendrite (1.43-7.83 wt%). Our in-situ analysis provides more precise results than traditional powder test. These mineralogical characteristics indicate that dendrite is most likely endogenic, while rock varnish and soil cutan are external accretion formed under different weathering environments.

  15. New insight into the origin of manganese oxide ore deposits in the Appalachian Valley and Ridge of northeastern Tennessee and northern Virginia, USA

    Science.gov (United States)

    Carmichael, Sarah K.; Doctor, Daniel H.; Wilson, Crystal G.; Feierstein, Joshua; McAleer, Ryan J.

    2017-01-01

    Manganese oxide deposits have long been observed in association with carbonates within the Appalachian Mountains, but their origin has remained enigmatic for well over a century. Ore deposits of Mn oxides from several productive sites located in eastern Tennessee and northern Virginia display morphologies that include botryoidal and branching forms, massive nodules, breccia matrix cements, and fracture fills. The primary ore minerals include hollandite, cryptomelane, and romanèchite. Samples of Mn oxides from multiple localities in these regions were analyzed using electron microscopy, X-ray analysis, Fourier transform infrared spectroscopy, and trace and rare earth element (REE) geochemistry. The samples from eastern Tennessee have biological morphologies, contain residual biopolymers, and exhibit REE signatures that suggest the ore formation was due to supergene enrichment (likely coupled with microbial activity). In contrast, several northern Virginia ores hosted within quartz-sandstone breccias exhibit petrographic relations, mineral morphologies, and REE signatures indicating inorganic precipitation, and a likely hydrothermal origin with supergene overprinting. Nodular accumulations of Mn oxides within weathered alluvial deposits that occur close to breccia-hosted Mn deposits in Virginia show geochemical signatures that are distinct from the breccia matrices and appear to reflect remobilization of earlier-emplaced Mn and concentration within supergene traps. Based on the proximity of all of the productive ore deposits to mapped faults or other zones of deformation, we suggest that the primary source of all of the Mn may have been deep seated, and that Mn oxides with supergene and/or biological characteristics resulted from the local remobilization and concentration of this primary Mn.

  16. Minerals in fractures of the saturated zone from drill core USW G-4, Yucca Mountain, Nye County, Nevada

    International Nuclear Information System (INIS)

    Carlos, B.A.

    1987-04-01

    The minerals in fractures in drill core USW G-4, from the static water level (SWL) at 1770 ft to the base of the hole at 3000 ft, were studied to determine their identity and depositional sequence and to compare them with those found above the SWL in the same drill hole. There is no change in mineralogy or mineral morphology across the SWL. The significant change in mineralogy and relationship to the host rock occurs at 1381 ft, well above the present water table. Below 1381 ft clinoptilolite appears in the fractures and rock matrix instead of heulandite, and the fracture mineralogy correlates with the host rock mineralogy. Throughout most of the saturated zone (below the SWL) in USW G-4, zeolites occur in fractures only in zeolitic tuff; however, zeolites persist in fracture below the base of the deepest zeolitic tuff interval. Nonzeolitic intervals of tuff have fewer fractures, and many of these have no coatings; a few have quartz and feldspar coatings. One interval in zeolitic tuff (2125-2140 ft) contains abundant crisobalite coatings in the fractures. Calcite occurs in fractures from 2575 to 2660 ft, usually with the manganese mineral hollandite, and from 2750 to 2765 ft, usually alone. Manganese minerals occur in several intervals. The spatial correlation of zeolites in fractures with zeolitic host rock suggests that both may have been zeolitized at the same time, possibly by water moving laterally through more permeable zones in the tuff. The continuation of zeolites in fractures below the lowest zeolitic interval in this hole suggests that vertical fracture flow may have been important in the deposition of these coatings. Core from deeper intervals in another hole will be examined to determine if that relationship continues. 17 refs., 19 figs

  17. Alteration of French waste glass matrix of R7T7 type in deep geological disposal conditions

    International Nuclear Information System (INIS)

    Combarieu, G. de

    2007-02-01

    The Geological disposal is a possible option for safe and long term management of long lived and highly radioactive wastes. In order to predict the release of radionuclides in the environment, the comprehensive knowledge of glass dissolution rates as well as the properties of near- and far-field in which migration will occur is necessary. This thesis is aimed to describe the alteration of SON68 glass, inactive analog of French R7T7 glass, in contact with disposal materials: metallic iron and Callovo-Oxfordian argilite. Therefore, original experiments have been carried out on a laboratory scaled system involving 'glass-iron-argilite' interactions. The transformations of chemistry and crystal-chemistry are investigated with multi-scale probing tools: SEM, TEM, XRD, XRF, EXAFS and Raman spectroscopies. In the same time, the glass alteration is modeled to obtain a source term in good agreement with the major phenomena observed in common experiments. As an end, geochemical models of iron and argilite transformations are also developed and set together in the transport-chemistry code HYTEC to simulate chemical reactions (iron corrosion, argilite evolution, and glass alteration). Simulations and comparison with experiments have improved the overall knowledge of the glass-iron-clay system. (author)

  18. Elemental and isotopic (Si-{sup 29} and O-{sup 18}) tracing of glass alteration mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Verney-Carron, A.; Libourel, G.; Deloule, E. [CNRS, Ctr Rech Petrog and Geochim, UPR 2300, F-54501 Vandoeuvre Les Nancy (France); Valle, N. [Ctr Rech Publ Gabriel Lippmann, Dept Sci and Anal Mat, L-4422 Belvaux (Luxembourg); Sterpenich, J. [Univ H Poincare, G2R, CNRS, UMR 7566, F-54501 Vandoeuvre Les Nancy (France); Jollivet, P. [CEA Marcoule, DEN, Lab Comportement Long Terme, F-30207 Bagnols Sur Ceze (France)

    2010-07-01

    To better understand glass alteration mechanisms, especially alteration layers formation, leaching experiments of a borosilicate glass (SON68) doped with a different rare earth element (La, Ce, or Nd) with solutions rich in {sup 29}Si and {sup 18}O were carried out. The coupled analyses of glass, alteration products, and solution led to a complete elemental and isotopic ({sup 29}Si and {sup 18}O) budget. They revealed different behaviours of elements that depend not only on their structural role in the glass, but also on their affinity for alteration products (gel, phyllosilicates, phosphates). However, analyses of both glass and solution are not sufficient to describe the real exchanges occurring between glass and solution. The use of {sup 29}Si and {sup 18}O tracers gives new insights on the formation of alteration layers. During alteration the phyllosilicates records the isotopic variations of the leaching solution. Their isotopic signatures highlight a mechanism of dissolution/precipitation, which implies equilibrium between the secondary phases and the solution. On the other hand the gel isotopic signature, that is intermediate between the glass and the solution, substantiates the hypothesis that the gel is formed by hydrolysis/condensation reactions. This mechanism can thus explain the influence of the gel formation conditions (alteration conditions, solution saturation) on the structure (reorganisation) and texture (porosity) of this layer and on its protective effect. These hydrolysis/condensation reactions are also certainly involved in the aluminosilicate glass alteration and in the formation of palagonite. (authors)

  19. Alteration of R7T7-type nuclear glass in deep geological storage conditions

    International Nuclear Information System (INIS)

    Combarieu, G. de

    2007-02-01

    This PhD thesis is aimed to study the alteration of SON68 glass, French inactive glass of R7T7-type, in contact with near field materials of a deep geological storage (French concept from ANDRA) which are mainly metallic iron and Callovo-Oxfordian clay. Therefore, experiments involving a 'glass-iron-clay' system at lab-scale have been carried out. Interactions between glass, iron and clay have been characterised from submicron to millimeter scale by means of SEM, TEM, XRD and XAS and Raman spectroscopies in terms of chemistry and crystal-chemistry. In the mean time, a conceptual model of glass alteration has been developed to account for most of the experimental observations and known mechanisms of alteration. The model has been then transposed within the transport-chemistry code HYTEC, together with developed models of clay and iron corrosion, to simulate the experiments described above. This work is thus a contribution to the understanding of iron corrosion in Callovo-Oxfordian clay and subsequent glass alteration in the newly formed corrosion products, the whole process being considered as a lab-scale model of a deep geological storage of radioactive wastes. (author)

  20. Improved organic scintillation detectors; Possibilites de perfectionnement des detecteurs organiques a scintillations; Usovershenstvovannye organicheskie stsintillyatsionnye detektory; Detectores organicos de centelleo perfeccionados

    Energy Technology Data Exchange (ETDEWEB)

    Birks, J B [University of Manchester, Manchester (United Kingdom)

    1962-04-15

    Equations have been derived for the practical scintillation efficiency (photo-electrons/MeV) of organic crystals and solutions in terms of molecular parameters and these have been applied to the more important scintillator systems, for photomultipliers with S11 (glass window) and S13 (quartz window) responses. The results suggest several improvements in current organic scintillation detector practice: the use of binary rather than ternary solutions; the use of quartz rather than glass windows; and the reconsideration of mixed crystal scintillators based on naphthalene. Improvements by factors of 2 or more in the figure of merit (practical efficiency/decay time) for fast-scintillation counting can be obtained. (author) [French] L'auteur a etabli des equations pour determiner le rendement de scintillation (photoelectrons/MeV) de cristaux et solutions organiques, en faisant intervenir des parametres moleculaires. Il a applique ces equations a des appareils a scintillations plus importantes pour determiner la reponse des photomultiplicateurs a fenetre en verre (S11) et a fenetre en quartz (S13). Les resultats obtenus ont fait apparaitre la possibilite d'ameliorer, a plusieurs egards, les detecteurs organiques a scintillations du type courant, par exemple en remplacant les solutions ternaires par des solutions binaires, les fenetres en verre par des fenetres en quartz, ou en reexaminant les possibilites offertes par les scintillateurs a cristaux mixtes a base de naphtalene. L'introduction de ces perfectionnements conduirait a une amelioration, du simple au double ou plus, du facteur de qualite (efficacite/temps de decroissance) des dispositifs de comptage a scintillations. (author) [Spanish] Se han establecido ecuaciones que permiten calcular el rendimiento practico de centelleo (fotoelectrones/MeV) de los cristales y soluciones organicos en funcion de parametros moleculares; estas ecuaciones han sido aplicadas a los sistemas de centelleo mas importantes, para

  1. Tests on dynamic corrosion by water. Influence of the passage of a heat flux on the corrosion kinetics. pH measurement in water at high temperature; Essais de corrosion dynamique par l'eau. Influence du passage d'un flux thermique sur la cinetique de corrosion. Mesure du pH dans l'eau a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Coriou, H.; Grall, L.; Hure, J.; Saint-James, R. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Berthod [Societe Grenobloise d' Etudes et d' Applications Hydrauliques, 38 (France); Le peintre [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France)

    1958-07-01

    'eau sous pression a une temperature voisine de 280 deg. C, la vitesse de circulation atteint 6 m/s. On etudie, du point de vue de la corrosion, les resultats obtenus, sur des gaines en aluminium, en attachant beaucoup d'attention aux phenomenes de cavitation susceptibles de causer de graves degats dans certaines circonstances particulieres. Apres avoir mis au point un dispositif d'electrode en verre pouvant supporter des pressions elevees les auteurs ont fait des recherches concernant les materiaux susceptibles de fonctionner comme electrode d'hydrogene et capables de resister convenablement a la corrosion par l'eau a 200 deg. C. Diverses possibilites ont ete examinees: electrodes de verres speciaux, de quartz, metallique, a membrane etc. On donne les resultats des differents essais et les limites pratiques d'utilisation. (auteur)

  2. Some Questions on the Fixation of Radioisotopes in Connexion with the Problem of their Safe Burial; Quelques Aspects de la Fixation des Isotopes Radioactifs en Rapport avec le Probleme de leur Elimination dans le Sol; 041d 0414 ; Algunos Aspectos de la Fijacion de los Isotopos Radiactivos en Relacion con los Problemas de su Evacuacion sin Riesgos en el Suelo

    Energy Technology Data Exchange (ETDEWEB)

    Zimakov, P. V.; Kulichenko, V. V.

    1960-07-01

    The results given in this paper are based on the fact that the best way of burying fission products is to incorporate them in vitrified fused blocks containing these fission products. The physico-chemical bases of the transformation of liquid waste into solid blocks are shown. The thermogram of this process is presented and the analysis of its characteristics given. The conditions of fusion of the vitrified mass, in particular those contributing to the fixation of radioactive aerosols, are shown. Some results of studies on the chemical state of radioactive fission products in the solid mass in connexion with the leaching of their radioactivity are given. In conclusion, the results of calculations of the temperatures up to which the radioactive blocks may be heated according to their characteristics are presented. (author) [French] Le present memoire est base sur l'hypothese que le meilleur procede d'elimination des dechets radioactifs dans le sous:sol consiste a les enfouir sous forme de blocs coules dans lesquels ils seraient intimement meles a du verre. Les auteurs decrivent les phenomenes physico-chimiques qui permettent la transformation des dechets radioactifs liquides en blocs solides. Ils donnent le thermogramme de ce processus et examinent certaines de ses particularites. Ils exposent en outre les conditions de coulage de la masse de verre, notamment celles qui facilitent la formation d'aerosols radioactifs. Les auteurs donnent quelques resultats des etudes effectuees sur l'etat chimique des elements radioactifs au sein de la masse solide, dans la mesure ou ces resultats touchent aux problemes que pose la fuite de la radioactivite due au 'lessivage' du bloc par l'eau. En conclusion, les auteurs indiquent les resultats du calcul des temperatures maxima auxquelles on peut porter les blocs radioactifs compte tenu de leurs caracteristiques. (author) [Spanish] Los autores de la memoria parten del supuesto de que la mejor manera de evacuar en el suelo los

  3. Some physical approaches to protein folding

    Science.gov (United States)

    Bascle, J.; Garel, T.; Orland, H.

    1993-02-01

    To understand how a protein folds is a problem which has important biological implications. In this article, we would like to present a physics-oriented point of view, which is twofold. First of all, we introduce simple statistical mechanics models which display, in the thermodynamic limit, folding and related transitions. These models can be divided into (i) crude spin glass-like models (with their Mattis analogs), where one may look for possible correlations between the chain self-interactions and the folded structure, (ii) glass-like models, where one emphasizes the geometrical competition between one- or two-dimensional local order (mimicking α helix or β sheet structures), and the requirement of global compactness. Both models are too simple to predict the spatial organization of a realistic protein, but are useful for the physicist and should have some feedback in other glassy systems (glasses, collapsed polymers .... ). These remarks lead us to the second physical approach, namely a new Monte-Carlo method, where one grows the protein atom-by-atom (or residue-by-residue), using a standard form (CHARMM .... ) for the total energy. A detailed comparison with other Monte-Carlo schemes, or Molecular Dynamics calculations, is then possible; we will sketch such a comparison for poly-alanines. Our twofold approach illustrates some of the difficulties one encounters in the protein folding problem, in particular those associated with the existence of a large number of metastable states. Le repliement des protéines est un problème qui a de nombreuses implications biologiques. Dans cet article, nous présentons, de deux façons différentes, un point de vue de physicien. Nous introduisons tout d'abord des modèles simples de mécanique statistique qui exhibent, à la limite thermodynamique, des transitions de repliement. Ces modèles peuvent être divisés en (i) verres de spin (éventuellement à la Mattis), où l'on peut chercher des corrélations entre les

  4. Evaluation experimentale et theorique du comportement a la flexion de nouveaux poteaux en materiaux composites

    Science.gov (United States)

    Metiche, Slimane

    La demande croissante en poteaux pour les differents reseaux d'electricite et de telecommunications a rendu necessaire l'utilisation de materiaux innovants, qui preservent l'environnement. La majorite des poteaux electriques existants au Canada ainsi qu'a travers le monde, sont fabriques a partir de materiaux traditionnels tel que le bois, le beton ou l'acier. Les motivations des industriels et des chercheurs a penser a d'autres solutions sont diverses, citons entre autre: La limitation en longueur des poteaux en bois ainsi que la vulnerabilite des poteaux fabriques en beton ou en acier aux agressions climatiques. Les nouveaux poteaux en materiaux composites se presentent comme de bons candidats a cet effet, cependant; leur comportement structural n'est pas connu et des etudes theoriques et experimentales approfondies sont necessaires avant leur mise en marche a grande echelle. Un programme de recherche intensif comportant plusieurs projets experimentaux, analytiques et numeriques est en cours a l'Universite de Sherbrooke afin d'evaluer le comportement a court et a long termes de ces nouveaux poteaux en Polymeres Renforces de Fibres (PRF). C'est dans ce contexte que s'inscrit la presente these, et notre recherche vise a evaluer le comportement a la flexion de nouveaux poteaux tubulaires coniques fabriques en materiaux composites par enroulement filamentaire et ce, a travers une etude theorique, ainsi qu'a travers une serie d'essais de flexion en "grandeur reelle" afin de comprendre le comportement structural de ces poteaux, d'optimiser la conception et de proposer une procedure de dimensionnement pour les utilisateurs. Les poteaux en Polymeres Renforces de Fibres (PRF) etudies dans cette these sont fabriques avec une resine epoxyde renforcee de fibres de verre type E. Chaque type poteaux est constitue principalement de trois zones ou les proprietes geometriques (epaisseur, diametre) et les proprietes mecaniques sont differentes d'une zone a l'autre. La difference

  5. Tests on dynamic corrosion by water. Influence of the passage of a heat flux on the corrosion kinetics. pH measurement in water at high temperature; Essais de corrosion dynamique par l'eau. Influence du passage d'un flux thermique sur la cinetique de corrosion. Mesure du pH dans l'eau a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Coriou, H; Grall, L; Hure, J; Saint-James, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Berthod, [Societe Grenobloise d' Etudes et d' Applications Hydrauliques, 38 (France); peintre, Le [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France)

    1958-07-01

    voisine de 280 deg. C, la vitesse de circulation atteint 6 m/s. On etudie, du point de vue de la corrosion, les resultats obtenus, sur des gaines en aluminium, en attachant beaucoup d'attention aux phenomenes de cavitation susceptibles de causer de graves degats dans certaines circonstances particulieres. Apres avoir mis au point un dispositif d'electrode en verre pouvant supporter des pressions elevees les auteurs ont fait des recherches concernant les materiaux susceptibles de fonctionner comme electrode d'hydrogene et capables de resister convenablement a la corrosion par l'eau a 200 deg. C. Diverses possibilites ont ete examinees: electrodes de verres speciaux, de quartz, metallique, a membrane etc. On donne les resultats des differents essais et les limites pratiques d'utilisation. (auteur)

  6. Contribution to the study of hydrogenated and oxygenated impurities in liquid sodium; Contribution a l'etude des impuretees hydrogenees et oxygenees dans le sodium liquide

    Energy Technology Data Exchange (ETDEWEB)

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

    1964-07-15

    This study is made up essentially of two parts. The first is devoted to the development of dosage methods for selectively determining the oxygenated and hydrogenated impurities present in sodium, that is the oxide, the hydride and the hydroxide. The second makes use of these methods for a study of the Na-H{sub 2}-O{sub 2} system, as well as of the related problem of the attack of pyrex glass by molten sodium. The conventional method for dosing oxygen by amalgamation was first adapted to the simultaneous measurement of the hydride. We then developed a method for dosing the total hydrogen by measuring successively the concentrations of gas present in the hydride and hydroxide form. This method is based on the thermal decomposition of the hydride and the reaction between sodium and the hydroxide. Our contribution to the study of the Na-H{sub 2}-O{sub 2} System consists first of all in the study of the reaction between hydrogen and sodium in the temperature range from 150 to 250 deg C and at a pressure of about 150 mm of mercury. The study of the thermal decomposition of the hydride in sodium was then studied. It was possible to make some qualitative observations concerning the reaction between sodium and sodium hydroxide. Finally some complementary tests made it possible to define the nature of the phenomena occurring during the attack of pyrex glass by sodium. (author) [French] Cette etude comporte essentiellement deux parties. La premiere est consacree a la mise au point de methodes de dosages permettant de determiner selectivement les impuretes oxygenees et hydrogenees presentes dans le sodium, a savoir l'oxyde, l'hydrure et l'hydroxyde. La seconde met a profit ces methodes en vue de l'etude du systeme Na-H{sub 2}-O{sub 2}. ainsi que du phenomene connexe d'attaque du verre pyrex par le sodium fondu. La methode classique de dosage de l'oxygene par amalgamation a d'abord ete adaptee au dosage simultane de l'hydrure. Nous avons ensuite mis au point le dosage de l

  7. Improvement of Heavy Oil Recovery in the VAPEX Process using Montmorillonite Nanoclays Amélioration de la récupération d’huile lourde par utilisation de nanoargiles de Montmorillonite dans le procédé VAPEX

    Directory of Open Access Journals (Sweden)

    Pourabdollah K.

    2011-10-01

    hydrocarbures dans les chambres balayees au cours des procedes VAPEX nano-assiste et conventionnel. Les experiences ont ete realisees en utilisant une huile lourde iranienne et du propane : le dispositif experimental consistait en deux cellules garnies de sable, l’une garnie uniquement avec des billes de verre en tant que milieu poreux et l’autre avec des billes de verre et de la montmorillonite modifiee en tant que nanoargile; les deux avaient la meme porosite et la meme permeabilite. La teneur en asphaltene depose dans les zones balayees, le profil de propagation des chambres de vapeur ainsi que les taux de consommation de solvant et de production d’huile ont ete determines. Les resultats ont mis en evidence que la montmorillonite a modifie l’heterogeneite du milieu poreux et a conduit a former des percees accrues, a augmenter la surface interfaciale solvant/bitume et a accelerer la production d’huile. Il s’est avere que non seulement le debit d’injection de solvant a ete diminue, mais que la recuperation d’huile lourde a egalement ete sensiblement accrue de 30 (±4 %.

  8. Systèmes multimatériaux – Assemblage par collage Multimaterial systems – Adhesive bonding

    Directory of Open Access Journals (Sweden)

    Zuanna C. Dalla

    2013-11-01

    Full Text Available L'assemblage par collage multimatériaux (métal/composite, métal/verre, métal/plastiques, verre/plastiques… offre de nombreux avantages par rapport aux techniques d'assemblages traditionnelles (pas d'affaiblissement des matériaux par la température, tenues en fatigue et à la corrosion améliorées, esthétisme, étanchéité…. Cependant la qualité et la durabilité à long terme des assemblages collés dépendent d'une bonne conception de ces assemblages : Le choix de préparations de surfaces efficaces, robustes, facilement industrialisables et respectueuses de l'environnement, Le choix d'adhésifs aptes à répondre au cahier des charges fonctionnel de l'assemblage (performances mécaniques, thermiques, chimiques… dont la mise en œuvre est compatible avec les contraintes d'industrialisation (cadences, temps de manipulation des pièces, environnement du poste collage…, Le dessin et le dimensionnement de la liaison de façon à transmettre les efforts mécaniques spécifiés dans la plage de températures de fonctionnement des pièces collées (en tenant compte des dilatations différentielles des matériaux assemblés. Cette démarche sera développée en donnant l'état de l'art actuel et les avancées les plus récentes sur les trois thèmes cités ci-dessus. Adhesive-bonding offers many advantages over traditional joining techniques (no weakening of materials by temperature, required fatigue and improved corrosion resistance, aesthetics, sealing… for multimaterial assembly (metal/composite, metal/glass, metal/plastic, glass/plastic…. However the quality and long term durability of bonded assemblies depend on a correct design of the joint: Choice of eco-efficient surfaces preparations, robust, and easily processed, Choice of adhesive in good adequation with the functional specifications of the assembly (mechanical performance, thermal, chemical… whose implementation is compatible with industrialization constraints

  9. Coleridge e il Novecento italiano: Luzi, Fenoglio e Giudici traduttori della Rime of the Ancient Mariner

    Directory of Open Access Journals (Sweden)

    Laura Organte

    2015-05-01

    Full Text Available Questo lavoro propone un’analisi stilistica comparativa delle prime tre versioni “d’autore” novecentesche della Rime of the Ancient Mariner – quella di Mario Luzi (1949, quella di Beppe Fenoglio (1955, e quella di Giovanni Giudici (1987, con lo scopo di valutare i rapporti di forza che agiscono di volta in volta fra la tradizione letteraria del testo di partenza, quella della cultura di arrivo e gli idioletti dei traduttori. Verranno dunque messe a confronto in primo luogo le scelte – radicalmente diverse – adottate per trasporre il complesso e rigoroso meccanismo metrico della Rime, i suoi versi brevi e fortemente cadenzati e il fitto sistema delle rime e delle rispondenze foniche. In un secondo momento verrà esaminato l’atteggiamento di ciascun traduttore di fronte alla lingua, e la rassegna delle scelte lessicali sarà, infine, mirata a vagliare le tonalità utilizzate per rendere la difficile miscela messa a punto da Coleridge tra vocabolario poetico e «language really used by men».This paper provides a comparative stylistic analysis of the first three translations “d’autore” of the Rime of the Ancient Mariner published in Italy in the 20th century by Mario Luzi (1949, Beppe Fenoglio (1955 and Giovanni Giudici (1987. Such analysis aims to appraise the relationships acting in the translation process among the literary tradition of the original text, the Italian culture, and the translators’ idiolects. Therefore, the essay will compare the differences among the choices adopted to transpose the complex and rigorous metric mechanism of Coleridge’s Rime, the short and strongly rhythmic verses, and the dense system of rhymes and phonic correspondences. Secondly, the attitude of each translator will be addressed concerning the language, while the review of the lexical choices will finally aim to examine the tonalities deployed to convey the difficult mixture of poetic dictionary and “language really used by man”.

  10. High speed pulsed magnetic fields measurements, using the Faraday effect; Mesures de champs magnetiques pulses rapides a l'aide de l'effet Faraday

    Energy Technology Data Exchange (ETDEWEB)

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

    1964-12-01

    For these measures, the information used is the light polarization plane rotation induced by the magnetic field in a glass probe. This rotation is detected using a polarizer-analyzer couple. The detector is a photomultiplier used with high-current and pulsed light. In a distributed magnet (gap: 6 x 3 x 3 cm) magnetic fields to measure are 300 gauss, lasting 0.1 {mu}s, with rise times {<=} 35 ns, repetition rate: 1/s. An oscilloscope is used to view the magnetic field from the P.M. plate signal. The value of the field is computed from a previous static calibration. Magnetic fields from 50 to 2000 gauss (with the probe now used) can be measured to about 20 gauss {+-} 5 per cent, with a frequency range of 30 MHz. (author) [French] Pour faire de telles mesures, on utilise comme information la rotation du plan de polarisation de la lumiere provoquee par le champ magnetique dans une sonde en verre. On detecte cette rotation au moyen d'un polariseur et d'un analyseur, qui sont regles a 45 deg. pour conserver un phenomene lineaire. Le detecteur est un photomultiplicateur travaillant en fort courant en lumiere pulsee. Dans un aimant distribue d'entrefer 6 x 3 x 3 cm, on obtient des champs magnetiques a mesurer de 300 gauss, durant 0.1 {mu}s, avec des temps de montee {<=} 35 ns; au taux de 1 fois par seconde. L'observation du champ se fait sur oscilloscope a partir du signal de plaque du P.M. La valeur absolue du champ est obtenue au moyen d'un etalonnage statique prealable. On peut ainsi mesurer a 20 gauss et {+-} 5 pour cent pres environ des champs magnetiques de 50 a 2000 gauss (avec la sonde actuelle) et avec une bande passante de 30 MHz. (auteur)

  11. Recording hydrometer for liquids especially adapted to the continuous measurement of heavy water (1962); Densimetre enregistreur pour liquides specialement adapte au dosage continu de l'eau lourde (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Chatel, S; Nief, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    A glass float, containing a magnetic device, is immersed in the water whose density is to be measured. It is free to move between two stops inside a differential transformer excited by an alternating current. The signal thus produced has an amplitude which increases with the distance separating the float from the lower stop. This signal is amplified, rectified, filtered and re-amplified. The current obtained passes through a coil which attracts the float downwards. The float sets to the level which the ascensional forces is exactly compensated. The intensity of the corresponding current is recorded. The concentration of D{sub 2}O in water can be measured between 0 and 8 per cent with a relative error of about 0.3 per cent without however an absolute possible error of under 20 deuterium atoms per million approximately (0.002 per cent). (authors) [French] Un flotteur en verre, contenant un equipage magnetique, baigne dans l'eau dont on veut mesurer la densite. Il est mobile entre deux butees a l'interieur d'un transformateur differentiel excite par un courant alternatif. Il en resulte un signal dont l'amplitude croit avec la distance du flotteur a la butee inferieure. Ce signal est amplifie, redresse, filtre, amplifie a nouveau. Le courant obtenu est envoye dans une bobine qui attire le flotteur vers le bas. Ce dernier se fixe au niveau pour lequel sa force ascensionnelle est exactement compensee. On enregistre la valeur du courant correspondant. La teneur d'une eau en D{sub 2}O peut etre mesuree entre 0 et 8 pour cent avec une erreur relative de l'ordre de 0,3 pour cent sans que l'erreur absolue, possible puisse descendre cependant au-dessous de 20 atomes de deuterium par million environ (0,002 pour cent). (auteurs)

  12. Effets de l'exposition à un insecticide carbamate, le carbofuran, sur les performances de jeunes stades de brochet (Esox lucius L., 1758 : résultats préliminaires

    Directory of Open Access Journals (Sweden)

    AMBLARD G.

    1998-07-01

    Full Text Available Des lots de jeunes brochets au stade embryon libre, stabulés dans des béchers en verre, ont été exposés en conditions statiques à des solutions (0-250 µg.L-1 de carbofuran, un insecticide carbamate inhibiteur de l'activité de l'acétylcholinestérase (AchE. A partir de 10 µg.L-1, une inhibition significative de l'activité globale de l'AchE des embryons libres a été constatée. A partir de 50 µg.L-1, une diminution significative de la hauteur moyenne de fixation des embryons libres sur les parois des béchers a été observée. L'exposition au carbofuran n'a pas eu d'effet significatif sur le nombre de proies zooplanctoniques ingérées par les jeunes brochets parvenus au début de la phase larvaire ; une diminution de ce paramètre en fonction de concentrations croissantes de carbofuran a cependant été enregistrée. A 250 µg.L-1 , la résorption de la vésicule vitelline ne s'effectuant plus que très partiellement, les embryons libres exposés ne se sont pas transformés en larves. Cette étude montre que l'exposition à des concentrations sublétales de carbofuran est susceptible d'affecter le développement ontogénétique et les performances de jeunes stades de brochet. Un approfondissement de ces travaux est envisagé dans différentes directions.

  13. Transition management. Key to a sustainable society; Transitiemanagement. Sleutel voor een duurzame samenleving

    Energy Technology Data Exchange (ETDEWEB)

    Rotmans, J. [International Centre for Integrative Studies ICIS, Universiteit Maastricht, Maastricht (Netherlands)

    2003-07-01

    Via transitions outdated societal systems need to be replaced by new societal and sustainable systems. In this book attention is paid to how the renewal process can be steered. The first part deals with the transition philosophy, while the second part is dedicated to a series of practical examples in the field of water, agriculture, energy, construction, mobility and biodiversity which must bring us to a new, sustainable society. [Dutch] Het creeren van een duurzame samenleving is van levensbelang voor de huidige en toekomstige generaties. Toch krijgt duurzaamheid van de politiek nog steeds niet de aandacht die zij verdient. Dit boek biedt daarom een vernieuwende en uitdagende kijk op deze grote maatschappelijke opgave. Onze tegenwoordige samenleving is verre van duurzaam; ondanks het veelgeroemde 'poldermodel' zijn we er tot nu toe niet in geslaagd de hardnekkige problemen in sectoren als de landbouw, de gezondheidszorg en de energievoorziening het hoofd te bieden. Meer en meer wordt duidelijk dat een duurzame samenleving een echte cultuuromslag vergt. Via transities - maatschappelijke overgangen die tijd, durf en energie vergen - zullen verouderde maatschappelijke systemen (deels) moeten worden afgebroken om vervolgens opnieuw te worden opgebouwd. Dit boek gaat in op de wijze waarop dit noodzakelijke vernieuwingsproces kan worden gestuurd. Het eerste deel behandelt het transitiedenken, inclusief de achterliggende filosofie. In het tweede deel staat het transitiehandelen centraal, aan de hand van een serie praktijkvoorbeelden op de terreinen water, landbouw, energie, de bouwsector, mobiliteit en biodiversiteit. Een inspirerend boek voor iedereen die een bijdrage wil leveren aan de totstandkoming van een nieuwe, duurzame samenleving.

  14. L’AZIONE DI CANCELLAZIONE - TUTELA DEI DIRITTI TAVOLARI

    Directory of Open Access Journals (Sweden)

    Zrinka Radić

    2017-01-01

    Full Text Available Il titolare di un diritto tavolare, leso dall’iscrizione a favore di altro soggetto, al fi ne di tutelare il proprio diritto è autorizzato a pretendere la cancellazione di qualsiasi iscrizione che lo offenda ed a ripristinare nel libro fondiario lo stato precedente. Se l’iscrizione di un diritto tavolare a favore di altro soggetto sia o no fondata, verrà stabilito dal tribunale in sede contenziosa. L’autore del lavoro si occupa della questione della legittimazione attiva e passiva e dei termini quali presupposti incontrovertibili volti alla presentazione della domanda di cancellazione. Si disaminano le questioni che sono problematiche in giurisprudenza ed in dottrina. Precisamente: la valutazione della legittimazione attiva, le questioni riguardanti dunque l’individuazione di coloro che in qualità di «lesi nel proprio diritto tavolare» possano intraprendere l’azione di cancellazione e la questione circa i tipi di iscrizione in occasione delle quali si possa giungere ad una tale lesione. Ancora, si valuta se l’attore debba in caso di azione di cancellazione provare il suo diritto sostanziale e quali eccezioni possa sollevare nell’azione. Al centro dell’attenzione v’è anche la questione della legittimazione passiva e dei termini quali presupposti incontrovertibili ai fi ni della presentazione della domanda di cancellazione; come pure l’interrogativo se l’azione di cancellazione sia giustifi cata soltanto nel caso di un’iniziale nullità del titolo o se sia suffi ciente anche una nullità successiva.

  15. ZnO layers prepared by spray pyrolysis

    Science.gov (United States)

    Messaoudi, C.; Abd-Lefdil, S.; Sayah, D.; Cadene, M.

    1998-02-01

    Highly transparent undoped and indium doped ZnO thin films have been grown on glass substrates by using the spray pyrolysis process. Conditions of preparation have been optimized to get good quality and reproducible films with required properties. Polycrystalline films with an hexagonal Wurtzite-type structure were easily obtained under the optimum spraying conditions. Both of samples have shown high transmission coefficient in the visible and infrared wavelength range with sharp absorption edge around 380 nm which closely corresponds to the intrinsic band-gap of ZnO (3.2 eV). Orientation and crystallites size were remarkably modified by deposition temperature and indium doping. Des couches minces de ZnO, hautement transparentes, non dopées et dopées à l'indium ont été élaborées sur un substrat en verre par le procédé de pulvérisation chimique réactive spray. Les conditions de préparation ont été optimisées pour l'obtention de couches reproductibles, de bonne qualité et ayant les propriétés requises. Des films polycristallins, présentant une structure hexagonale de type Wurtzite, ont été aisément obtenus dans les conditions optimales de pulvérisation. Tous les échantillons ont présenté un coefficient de transmission élevé dans le domaine du visible et du proche infrarouge, avec une absorption brutale au voisinage de 380 nm, correspondant au gap optique du ZnO (3,2 eV). L'orientation et la taille des cristallites ont été remarquablement modifiées par la température du dépôt et par le dopage à l'indium.

  16. Shielded enclosure for handling radioactive material; Sorbonnes blindees pour manipulations radioactives

    Energy Technology Data Exchange (ETDEWEB)

    Laurent, H; Courouble, J M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1959-07-01

    Two enclosures linked by an air-lock are described: they are designed for the safe handling of 5 curies 0.3 to 0.5 MeV {gamma} emitters, and each is composed of a semi-tight case, ventilated, clad in 80 mm steel plate, and suited for a wide variety of physics and chemistry operations. The equipment required for any given operation can be installed in the shortest possible time, access to the enclosure being via a removable front. Visual control is assured through a lead-glass screen. Each enclosure is fitted with a master-slave manipulator, Argon model 7, and plugs and air-locks are provided for the introduction of liquids and solids. (author) [French] On decrit deux enceintes reliees par un sas pour manipulation sur 5 curies d'emetteurs {gamma} de 0,3 a 0,5 MeV. Chacune des enceintes est constituee d'une boite semi-etanche, ventilee, entouree de toles d'acier de 80 mm. L'ensemble est concu pour y effectuer les operations physiques ou chimiques les plus variees. L'equipement necessaire a une manipulation donnee peut y etre installe dans le minimum de temps, l'acces se faisant par la face avant qui peut se deplacer. Une dalle de verre au plomb assure la vision. Chacune des sorbonnes est equipee d'une paire de telemanipulateurs Argonne modele 7. Des sas et des bouchons assurent le passage des solides et des fluides. (auteur)

  17. The development of a cell-assembly for the treatment of irradiated fuels on a semi-industrial scale; Etude concernant la realisation d'un ensemble de cellules destinees a des traitements de combustibles irradies a l'echelle semi-industrielle

    Energy Technology Data Exchange (ETDEWEB)

    Faugeras, P; Couture, J; Lefort, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1961-07-01

    The main studies and experiments involved in the development of a cell-assembly for the treatment of irradiated fuels on a semi-industrial scale are described. It must be possible to modify or transform each of these cells without interrupting the rest of the pilot. A full-scale prototype cell (3 x 4 x 6 m) has been built with an {alpha}-protection independent of the {gamma}-protection. It features all the main characteristics: tightness to {gamma} losses, dense glass lighting, ventilation. This cell has made possible trials on transfer, remote-controls and tele-dismantling, as well as the development of new methods of rapidly connecting hydraulic circuits. In conclusion the final form is given of the cells selected for the pilot. (author) [French] Il est decrit les principales etudes et experiences faites en vue de la realisation d'un ensemble de cellules destinees a des traitements de combustibles irradies a l'echelle semi-industrielle. Chacune de ces cellules doit pouvoir etre modifiee ou transformee sans interrompre le reste du pilote. Une cellule prototype vraie grandeur (3x4x6 m) est construite avec une protection {alpha} independante de la protection {gamma}. Elle comporte tous les elements importants: porte {gamma} etanche, eclairage verre dense, ventilation. Cette cellule a permis des experiences de transferts de telemanipulateurs et de teledemontages, ainsi que la mise au point de nouveaux procedes de jonction rapide pour des circuits hydrauliques. En conclusion, on indique la forme definitive des cellules retenues pour le pilote. (auteur)

  18. Simboli apparenti: ricerca qualitativa sull'estetica dell'ipod

    Directory of Open Access Journals (Sweden)

    Riccardo Esposito

    2009-04-01

    Full Text Available Ormai i lettori di file mp3 - l’algoritmo di compressione per i brani musicali digitalizzati - sono entrati nel ventaglio delle tecnologie di uso comune, soprattutto per quanto concerne l’universo giovanile. All’interno dell’infinita varietà di marche e modelli però, possiamo sostenere con buona sicurezza che l’iPod, il lettore mp3 della Apple, ha saputo conquistarsi una buona fetta di mercato. I motivi del suo successo commerciale si legano a diversi elementi, tra i quali non possiamo far a meno di citare la capacità dell’iPod di assorbire le interpretazioni simboliche proposte dai suoi fruitori, un processo quasi sconosciuto agli altri lettori mp3. L’iPod non viene inteso sic et simpliciter come un oggetto con relativa funzione ma anche come simbolo, un contenitore di significati mutevoli che gli individui utilizzano per comunicare ai propri simili la loro solidarietà nei confronti del “pensiero Apple”. Ma non solo: se tutto ciò fosse vero, potremmo anche immaginare questo lettore mp3 investito da valori estetici a tal punto da trasfigurarsi in orpello da abbinare con il soprabito. È possibile, quindi, pensare all’iPod non solo come lettore di file mp3 ma anche come un qualsiasi monile, gioiello e/o accessorio del proprio abbigliamento? Questa domanda rappresenta la base della ricerca che verrà approfondita nel seguente saggio, un lavoro che tramite l’utilizzo di tecniche appartenenti all’universo della ricerca qualitativa cerca di dare possibili risposte - mai definitive - ai precedenti quesiti.

  19. Laparoscopic ovariectomy using sequential electrocoagulation and sharp transection of the equine mesovarium.

    Science.gov (United States)

    Rodgerson, D H; Belknap, J K; Wilson, D A

    2001-01-01

    To describe in horses and ponies a laparoscopic ovariectomy technique facilitated by electrosurgical instrumentation. Elective ovariectomy was performed in 23 mares using laparoscopic electrosurgical instrumentation. Twenty-three mares (13 horses, 10 ponies), aged from 2 to 21 years and weighing 90 to 545 kg. Food was withheld for a minimum of 12 hours. Mares were sedated with detomidine hydrochloride (0.02 to 0.03 mg/kg) or xylazine hydrochloride (0.5 to 1.0 mg/kg). Excluding the pony mares, all other mares were restrained in stocks. Portal sites in the paralumbar fossa region were desensitized with 2% mepivacaine. Abdominal insufflation was achieved through a teat cannula positioned in the ventral abdomen or a Verres-type needle placed through the paralumbar fossa. After trocar and laparoscope insertion, the ipsilateral ovary and mesovarium were identified, and the mesovarium, tubal membrane, and proper ligament were infiltrated with 2% mepivacaine. The mesovarium was coagulated using bipolar or monopolar electrosurgical forceps and transected sequentially from cranial to caudal until the ovary was completely freed and then removed. The contralateral ovary was removed in a similar fashion through the opposite paralumbar fossa. Bipolar and monopolar electrosurgical forceps were easy to use and provided adequate coagulation of vessels within the mesovarium. Two mares were euthanatized after the procedure for unrelated reasons. One mare had mild signs of colic 24 hours after ovariectomy. In 1 pony mare, the incision used to remove one ovary dehisced on the 5th postoperative day and was allowed to heal by second-intention. No long-term complications had occurred in 11 horses and 10 ponies, 6 to 24 months after surgery. Laparoscopic ovariectomy and hemostasis of the mesovarium can be easily accomplished using electrosurgical instrumentation. Standing laparoscopic ovariectomy, using electrosurgical instrumentation, is an effective and safe technique to provide

  20. The national project for Roma, Sinti and Caminanti children inclusion: A Socio-Anthropological overview

    Directory of Open Access Journals (Sweden)

    Greta Persico

    2017-07-01

    Full Text Available Questo articolo sperimenta una prospettiva critica, applicata ed interdisciplinare al contrasto all’antiziganismo. La ricerca è stata svolta nell’ambito del Progetto Nazionale per l'Inclusione e l'integrazione dei bambini rom, sinti e caminanti, realizzato nell'arco dell'anno scolastico 2013/14 nella città di Milano. La cornice teorica di riferimento afferisce a differenti orizzonti: verranno presi in considerazione il paradigma del contrasto all’antiziganismo, le ricerche relative alle politiche educative nei confronti dei bambini e delle bambine rom e verrà fatto un accenno alla teoria della didattica inclusiva. In questo quadro analizzeremo le premesse sulle quali si basava la declinazione milanese dell’intervento nonché le attività formative realizzate all’interno di due scuole cittadine. Tali azioni hanno coinvolto le due autrici in qualità di formatrici. A partire da una analisi delle azioni del progetto verranno evidenziati gli elementi di continuità e discontinuità rispetto a politiche educative rivolte ai minori rom e alle loro famiglie attuate in città nel passato. Infine, a partire dagli esiti della formazione verranno esaminati gli effetti prodotti dall'interazione tra il mondo della ricerca e la realtà sociale. Il quadro che ne deriva evidenzia come il paradigma dell’antiziganismo sia la condizione necessaria per far emergere il paradigma opposto, quello dell’anti-antiziganismo, entro cui si producono discorsi, si destinano finanziamenti, si elaborano progetti e carriere degli “oppositori dell'antiziganismo”.

  1. The application of {beta}-ray excitation fluorescence to the measurement of the thickness of deposits and to analysis; Applications de la fluorescence excitee au moyen des rayons {beta} a la mesure des epaisseurs des depots et a l'analyse

    Energy Technology Data Exchange (ETDEWEB)

    Martinelli, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Seibel, G [Institut de Recherches de la Siderurgie Francaise (IRSID), 78 - Saint-Germain-en-Laye (France)

    1961-07-01

    Principles of the method are first outlined and the instrumentation used is described. The different types of radiation detectors are subject of a detailed study. As a source of {beta}-radiation {sup 90}(Sr + Y) was used as well as {sup 147}Pm. Great care was taken to eliminate back-diffused electrons by deflection by a strong permanent magnet. The method was applied to the measurement of the thickness of deposits of Cr, Zn, Sn, Cd and Cu on iron as well as Zn, Cr, Ag and Au on copper and the results obtained are discussed. An attempt was made, to use {beta}-X-ray fluorescence for the analysis of minerals, iron ore and glass and for routine control of Si-Mn, Si-Ca, Fe-Mn and Fe-W. Finally the method of {beta}-X-ray fluorescence is compared with normal-X-ray fluorescence and possibilities of further development are cited. (author) [French] Les principes de la methode et l'instrumentation utilisee sont presentes. On decrit en particulier les detecteurs de rayonnement utilises. Comme source de rayonnement on utilise {sup 90}(Sr + Y) et {sup 147}Pm. Pour eliminer les electrons retrodiffuses on utilise un aimant permanent place sur le trajet du faisceau. La methode est appliquee a la mesure des epaisseurs des depots metalliques tels que le Cr, Zn, Sn, Cd et Cu sur fer et le Zn, Cr, Ag et Au sur cuivre. D'autre part, la fluorescence {beta}-X etait utilisee pour l'analyse des minerais et des verres et pour le controle des alliages Fe-Mn, Fe-W, Si-Mn, Si-Ca. Enfin, on passe a une comparaison entre la fluorescence {beta}-X et la fluorescence X normale et on discute les possibilites d'un developpement futur. (auteur)

  2. Final report for Allied-Signal Aerospace Company, Kansas City Division on protective glove permeation analysis

    International Nuclear Information System (INIS)

    Swearengen, P.M.; Johnson, J.S.; Priante, S.J.

    1990-01-01

    We conducted 25 separate glove fabric permeation studies during this project. The permeations were carried out in the small (1 inch) glass ASTM cell. One other permeation study was carded out with a large (two inch) modified ASTM cell for comparison with the small cell results. We also compared the LLNL procedure from both large and small cells with the standard ASTM test procedure which uses a liquid solution on the breakthrough side of the fabric (the liquid is then sampled on a periodic basis). In all comparisons we observed a close-correlation in breakthrough times between the two procedures and the two cell sizes. In the course of this study, we tested ten different glove materials. These included neoprene (original ASTM round-robin sheet stock, 16 mil thickness), Edmont Sol-Vex (nitrile), Pioneer nitrile, Pioneer Pylox (polyvinyl chloride), North Viton (trademark for fluoroelastomers), North SilverShield (Norfoil, trademark for a flexible metallized laminate), Safety 4 4H (patented plastic laminate), and QRP PolyTuff (polyurethane) 20G-2000 (5 mil), 23G-2300 (1.5 mil), and 25G-2500 (1.5 mil). Three of the glove materials, Viton and Silver Shield (North), and 4H (Safety 4), did not allow any permeation measurable by our system to either 1,2-dichloroethane or 3% diphenylmercury (in 1,2-dichloroethane) for a period greater than six hours. A fourth material, QRP Poly Tuff 2OG-2000, did not allow any measurable penetration of Asilamine (an aromatic diamine) for a time pedod of greater than 4 hours. Breakthrough times and curves were obtained for all other tested materials. Eleven different chemicals were used to challenge the glove materials. These included acetone, Asilamine, 1,2-dichloroethane, dichloromethane, isopropyl alcohol, a mixture of 3% diphenylmercury in 1,2-dichloroethane (w/w), phenol, and lso Verre Stripper, 4,4'-methylenedianil (MDA), 1,3-phenylenediamine (MPDA), and Shell Epon (R) curing agent Z

  3. Dėl cirkumfleksinės metatonijos lietuvių kalbos dūriniuose

    Directory of Open Access Journals (Sweden)

    Danguolė Mikulėnienė

    2011-11-01

    Full Text Available ZUM PROBLEM DER ZIRKUMFLEXEN METATONIE IN LITAUISCHEN ZUSAMMEN­SETZUNGENZusammenfassungEs wird die Hypothese aufgestellt, daß die Metatonie in den litauischen Zusammensetzungen eine relativ späte Erscheinung ist, die bei der Umgestaltung des Paradigmas mit beweglichem Wortakzent entstanden ist, d. h. sie tauchte in der Zeit auf, als sich der Wortakzent in den Zusammensetzungen nach rechts verschob. Diese Annahme wird durch folgende Argumente bekräftigt: 1. Durch die im litauischen Schrifttum des 16. Jh. belegten Akzentuierungsvarianten, z. B. bei M. Daukša bedievỹs, -i und bediẽvis, -ė, svetimmóteris:svetimmotẽris; 2. Durch das Vorliegen der schwankenden Akzentuierung in den Zusammensetzungen der litauischen Sprache der Gegenwart – man tendiert dazu, den Akzent in Richtung der Morphemgrenze zu verrücken: jaunavedýs, aber auch jauñvedis; 3. Durch Fakten der lettischen Sprache, wo die Metatonie durch Verbreitung des Akuts in der entgegengesetzten Richtung zustande kam, vgl.: grūtdiẽnis ‘Armseliger’: dìena ‘Tag’.Obwohl sich die Akzentuierungssysteme der litauischen und lettischen Zusammensetzungen selbständig entwickelten, vollzog sich dieser Prozeß nach der Stimmbewegung auf Basis desselben bal­tischen modells:Es kann gefolgert werden, daß die in den litauischen Zusammensetzungen erscheinende Metato­nie, die als Ergebnis der Akzentverrückung anzusehen ist, funktionell mit der Verlegung des Akzents nach rechts während der Herausbildung der suffixalen Akzentuierung zusammenfällt.

  4. Comparative Studies with N-Methyl-2-Pyrrolidone and Furfural As Solvents for Extraction of Lube Distillates Etude comparative de deux solvants, la n-methyl-2 pyrrolidone et le furfural, pour l'extraction de distillats pour huiles lubrifiantes

    Directory of Open Access Journals (Sweden)

    Krishna R.

    2006-11-01

    Full Text Available Solvent extraction of spindle raw lube distillate from Oman crude using n-methyl pyrrolidone (NMP containing 1. 5wt. % water has been studied using a six-stage all-glass mixer-settler. Results of three operating temperatures with NMP are reported. A 65-55°C extraction temperature appears to be most appropriate for this stock. Data obtained at this temperature have been compared with those for furfural on the basis of phase boundary curves, extraction and lube refining indices and selectivity. Comparison of the results shows NMP to be more selective as far as raffinate yield is concerned. It requires lower operating solvent-to-feed ratios and lower temperatures. On étudie dans cet article l'extraction par solvant de distillats bruts pour huiles lubrifiantes spindles au moyen de n-méthyl pyrrolydone (NMP contenant 1,5 % d'eau en poids, dans une unité en verre constituée par une batterie de six mélangeurs-décanteurs. On présente les résultats relatifs à trois températures de fonctionnement avec la NMP. Une température d'extraction de 66-55°C est celle qui convient le mieux pour cette huile de base. On compare les résultats obtenus à cette température avec ceux du furfural, en ce qui concerne les courbes de solubilité, les indices de raffinage et d'extraction, et les sélectivités. La comparaison des résultats montre que la NMP est plus sélective et conduit à un rendement de raffinat plus élevé. Elle nécessite des taux de solvant par rapport à la charge plus faibles ainsi que des températures d'extraction plus basses.

  5. Ripensare l’integrazione attraverso lo sport: la partecipazione sportiva a livello comunitario dei migranti turchi in Francia

    Directory of Open Access Journals (Sweden)

    William Gasparini

    2013-04-01

    Full Text Available Storicamente, la Francia è una terra d’immigrazione già a partire dal XIX secolo, periodo in cui lo sport moderno si è sviluppato. Progressivamente, i migranti e i loro discendenti si sono mescolati nello “creuset français” anche attraverso il contributo che lo sport ha dato all’integrazione sociale di numerosi sportivi migranti. Lo sport (e più particolarmente il calcio si presenta dunque come un terreno di studio particolarmente interessante sia sull’ambito delle espressioni di identità che sulle nuove forme del “vivere insieme”. L’articolo propone di mettere questi aspetti alla prova dei fatti analizzando la pratica sportiva dei migranti turchi, l’ultima grande onda di migranti in Francia e prima comunità di migranti in Europa. I dati empirici raccolti nell’ambito dei club turchi nella regione d’Alsazia (nord-est della Francia mostrano la presenza, chiara, di un raggruppamento comunitario che pone una serie di domande: tali raggruppamenti esistono poiché costretti o derivano da una scelta fatta in senso militante ? Da questo punto di vista, in che modo lo sport permette la loro coesione e la loro integrazione sociale ? Al di là della sola “identità turca” verrà dimostrato che l’esistenza di un club “turco” nell’ambito della società di accoglienza e la partecipazione sportiva a livello comunitario sono legati a dei fattori sociali e politici. Nel mettere in luce le cause sociali dei raggruppamenti sportivi, l’articolo intende inoltre superare l’opposizione classica tra la socializzazione comunitaria e la socializzazione societaria.

  6. Crystal structures and thermal decomposition of permanganates AE[MnO_4]_2 . n H_2O with the heavy alkaline earth elements (AE=Ca, Sr and Ba)

    International Nuclear Information System (INIS)

    Henning, Harald; Bauchert, Joerg M.; Conrad, Maurice; Schleid, Thomas

    2017-01-01

    Reexamination of the syntheses and crystal structures as well as studies of the thermal decomposition of the heavy alkaline earth metal permanganates Ca[MnO_4]_2 . 4 H_2O, Sr[MnO_4]_2 . 3 H_2O and Ba[MnO_4]_2 are the focus of this work. As an alternative to the very inelegant Muthmann method, established for the synthesis of Ba[MnO_4]_2 a long time ago, we employed a cation-exchange column loaded with Ba"2"+ cations and passed through an aqueous potassium-permanganate solution. We later used this alternative also with strontium- and calcium-loaded columns and all the compounds synthesized this way were indistinguishable from the products of the established methods. Ca[MnO_4]_2 . 4 H_2O exhibiting [CaO_8] polyhedra crystallizes in the orthorhombic space group Pccn with the lattice parameters a=1397.15(9), b=554.06(4) and c=1338.97(9) pm with Z=4, whereas Sr[MnO_4]_2 . 3 H_2O with [SrO_1_0] polyhedra adopts the cubic space group P2_13 with a=964.19(7) pm and Z=4. So the harder the AE"2"+ cation, the higher its demand for hydration in aqueous solution. Consequently, the crystal structure of Ba[MnO_4]_2 in the orthorhombic space group Fddd with a=742.36(5), b=1191.23(7) and c=1477.14(9) pm with Z=8 lacks any crystal water, but contains [BaO_1_2] polyhedra. During the thermal decomposition of Ca[MnO_4]_2 . 4 H_2O, the compound expels up to two water molecules of hydration, before the crystal structure collapses after the loss of the third H_2O molecule at 157 C. The crystal structure of Sr[MnO_4]_2 . 3 H_2O breaks down after the expulsion of the third water molecule as well, but this already occurs at 148 C. For both the calcium and the strontium permanganate samples, orthobixbyite-type α-Mn_2O_3 and the oxomanganates(III,IV) AEMn_3O_6 (AE=Ca and Sr) remain as final decomposition products at 800 C next to amorphous phases. On the other hand, the already anhydrous Ba[MnO_4]_2 thermally decomposes to hollandite-type BaMn_8O_1_6 and BaMnO_3 at 800 C.

  7. Anelasticity maps for acoustic dissipation associated with phase transitions in minerals

    Science.gov (United States)

    Carpenter, Michael A.; Zhang, Zhiying

    2011-07-01

    Acoustic dissipation due to structural phase transitions in minerals could give rise to large seismic attenuation effects superimposed on the high temperature background contribution from dislocations and grain boundaries in the Earth. In addition to the possibility of a sharp peak actually at a transition point for both compressional and shear waves, significant attenuation might arise over wider temperature intervals due to the mobility of transformation twins or other defects associated with the transition. Attenuation due to structural phase transitions in quartz, pyroxenes, perovskites, stishovite and hollandite, or to spin state transitions of Fe2+ in magnesiowüstite and perovskite and the hcp/bcc transition in iron-nickel (Fe-Ni) alloy, are reviewed from this perspective. To these can be added possible loss behaviour associated with reconstructive transitions which might occur by a ledge mechanism on topotactic interfaces (orthopyroxene/clinopyroxene, olivine/spinel and perovskite/postperovskite), with impurities (Snoek effect) or with mobility of protons. There are experimental difficulties associated with measuring dissipation effects in situ at simultaneous high pressures and temperatures, so reliance is currently placed on investigation of analogue phases such as LaCoO3 for spin-state behaviour and LaAlO3 for the dynamics of ferroelastic twin walls. Similarly, it is not possible to measure loss dynamics simultaneously at the low stresses and low frequencies that pertain in seismic waves, so reliance must be placed on combining different techniques, such as dynamic mechanical analysis (low frequency, relatively high stress) and resonant ultrasound spectroscopy (high frequency, low stress), to extrapolate acoustic loss behaviour over wide frequency, temperature and stress intervals. In this context 'anelasticity maps' provide a convenient means of representing different loss mechanisms. Contouring of the inverse mechanical quality factor, Q-1, can be

  8. Comparison of the properties of simulated synroc synthesized by sol-gel and a novel co - precipitation method

    International Nuclear Information System (INIS)

    Potdar, H.S.; Vijayanand, S.; Khaja Mohaideen, K.; Joy, P.A.; Raja Madhavan, R.; Kutty, K.V.G.; Ambashta, R.D.; Wattal, P.K.

    2009-01-01

    Synroc is a multiphase dense titanate based ceramic designed for the incorporation of high-level waste (HLW) from the reprocessing of spent nuclear fuel. Synroc or synthetic rock consists of four main titanate phases - zirconolite (CaZrTi 2 O 7 ), hollandite (BaAlO 2 Ti 6 O 16 ), perovskite (CaTiO 3 ) and rutile (TiO 2 ), with the matrix composition as shown in Table 1. It is known that these phases have the capacity to incorporate most of the elements into their crystal structures which are present in the HLW derived from the reprocessing of spent nuclear fuel from power reactors. Synroc is considered as the most effective and durable means of immobilising various forms of high-level radioactive wastes for disposal. Synroc is also considered as a low-risk, tailored waste form, offering higher waste loading and over all cost savings. Simulated synroc precursor powders are typically produced by advanced wet chemical methods such as alkoxide hydrolysis and sol-gel routes. These routes were developed to produce powders with well defined physical and chemical characteristics such as correct chemical composition, high degree of homogeneity, reactivity and readily densifiable material to 99% of theoretical density during hot isostatic pressing. However, the reported alkoxide hydrolysis and hydroxide routes suffer from several disadvantages such as use of large quantities of organic solvents and their disposal as effluent, difficulty in maintaining exact chemical composition, use of costly alkoxide precursors which are moisture sensitive and require critical processing conditions to control their rate of hydrolysis, etc. In the present work we report a comparative study the characteristics of synroc-C (14% waste loading) powders and sintered pellets synthesized by the known alkoxide hydrolysis method and a simple chemical co-precipitation route developed by us. The advantages of the co-precipitation route are its simplicity, ease of handling and utilization of cheaper raw

  9. PRELIMINARY STUDY OF CERAMICS FOR IMMOBILIZATION OF ADVANCED FUEL CYCLE REPROCESSING WASTES

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K.; Billings, A.; Brinkman, K.; Marra, J.

    2010-09-22

    The Savannah River National Laboratory (SRNL) developed a series of ceramic waste forms for the immobilization of Cesium/Lanthanide (CS/LN) and Cesium/Lanthanide/Transition Metal (CS/LN/TM) waste streams anticipated to result from nuclear fuel reprocessing. Simple raw materials, including Al{sub 2}O{sub 3}, CaO, and TiO{sub 2} were combined with simulated waste components to produce multiphase ceramics containing hollandite-type phases, perovskites (particularly BaTiO{sub 3}), pyrochlores, zirconolite, and other minor metal titanate phases. Identification of excess Al{sub 2}O{sub 3} via X-ray Diffraction (XRD) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS) in the first series of compositions led to a Phase II study, with significantly reduced Al{sub 2}O{sub 3} concentrations and increased waste loadings. Three fabrication methodologies were used, including melting and crystallizing, pressing and sintering, and Spark Plasma Sintering (SPS), with the intent of studying phase evolution under various sintering conditions. XRD and SEM/EDS results showed that the partitioning of the waste elements in the sintered materials was very similar, despite varying stoichiometry of the phases formed. The Phase II compositions generally contained a reduced amount of unreacted Al{sub 2}O{sub 3} as identified by XRD, and had phase assemblages that were closer to the initial targets. Chemical composition measurements showed no significant issues with meeting the target compositions. However, volatilization of Cs and Mo was identified, particularly during melting, since sintering of the pressed pellets and SPS were performed at lower temperatures. Partitioning of some of the waste components was difficult to determine via XRD. SEM/EDS mapping showed that those elements, which were generally present in small concentrations, were well distributed throughout the waste forms. Initial studies of radiation damage tolerance using ion beam irradiation at Los

  10. Transformation from layered to tunnel structures: Synthesis, characterization, and applications of manganese oxide octahedral molecular sieves

    Science.gov (United States)

    Xia, Guan-Guang

    Manganese oxide based octahedral molecular sieves (OMS) have been found to have a wide variety of applications as catalysts, absorbents, and battery materials due to their unique structures and physical and chemical properties. OMS materials are made up of manganese oxide octahedral building blocks sharing comers and edges to form tunnel structures. Manganese species in the framework of OMS materials are mixed valent with various ion-exchangeable cations residing in the tunnels playing important roles in charge balancing and special chemical activities. With different synthetic parameters such as the template used, temperature, pressure, and the pH of the synthetic media, layered birnessite materials were hydrothermally transformed into distinct tunnel structures with different tunnel sizes, including Mg-3x3 (OMS-1), NH4-2x2 (NH4-OMS-2), Na-2x4 (OMS-5), and other manganese oxides. Characterization of the OMS materials with a wide variety of instruments has revealed that most of them are nano-fibrous hollow crystals ith large surface areas, high ion-exchange capabilities, and relatively high thermal stabilities. The Na-2x4 tunnel structure sodium MnOx has been synthesized for the first time and studied in detail, including synthetic strategies, structural analyses, and other physical and chemical property analyses. As catalysts, the synthetic OMS materials show high catalytic activities and shape-selective properties. For example, the results of the competitive oxidation of cycloalkanes with tertiary butyl hydrogen peroxide (TBHP) over different tunnel sized ONIS materials have proven that the OMS materials with larger tunnels are more favorable for the oxidation of the biggest molecule, cyclooctane, than the smallest one, cyclohexane. Besides the tunnel size effects, tunnel cations in the OMS materials also have influences on their catalytic activities. The study of carbon monoxide cleanup for fuel cell applications demonstrates that Ag-OMS-2 (a hollandite

  11. Geodynamic and metabolic cycles in the Hadean

    Directory of Open Access Journals (Sweden)

    M. J. Russell

    2005-01-01

    interred in minerals such as ranciéite and hollandite in shallow marine manganiferous sediments, were sequestered and invaginated within the cyanobacterial precursor where, energized by light, they could oxidize water. Thus, a chemical sedimentary environment was required both for the emergence of chemosynthesis and of oxygenic photosynthesis, the two innovations that did most to change the nature of our planet.

  12. A novel hydrothermal method to convert incineration ash into pollucite for the immobilization of a simulant radioactive cesium

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Zhenzi, E-mail: zzjing@tongji.edu.cn [Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, Tongji University, 4800 Cao’an Road, Shanghai 201804 (China); Hao, Wenbo; He, Xiaojun; Fan, Junjie; Zhang, Yi; Miao, Jiajun [Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, Tongji University, 4800 Cao’an Road, Shanghai 201804 (China); Jin, Fangming [School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2016-04-05

    Highlights: • Incineration ash could be converted hydrothermally to pollucite to immobilize Cs. • Pollucite could be synthesized readily with a wide range of Cs/Si ratios. • With Ca(OH){sub 2} added, a tough pollucite could be used to solidify Cs-polluted RHA. • Leaching results showed that the amount of Cs leached from specimen was very low. - Abstract: The Fukushima nuclear accident in Japan on March 11, 2011 produced huge amounts of Cs-polluted incineration ashes; conventional solidification methods seem unsuitable for the treatment of large amounts of Cs-polluted ashes. A novel hydrothermal method was developed to directly convert Cs-polluted incineration ash (rice husk ash) into pollucite to immobilize Cs in its crystal structure in situ. Results revealed that pollucite could be synthesized readily over a wide range of added Cs (Cs/Si = 0.2–0.6); the addition of more Cs (Cs/Si ≥ 0.5) caused the formation of a small amount of cesium aluminosilicate (CsAlSiO{sub 4}), which exhibits poor immobilization behavior for Cs. Pollucite could be formed even for a short curing time (1 h) or at a low curing temperature (150 °C). However, a high curing temperature or a long curing time favored the formation of a pure pollucite. With the added calcium hydroxide, a tough specimen with a flexural strength of approximately 22 MPa could be obtained, which suggested that this technology may be applied directly to the solidification of Cs-polluted incineration ashes. Hydrogarnet and tobermorite formations enhanced the strength of the solidified specimens, and meanwhile the formed pollucite was present in a matrix steadily. Leaching test demonstrated that the amount of Cs that leached from the synthesized specimens was very low (0.49 × 10{sup −5}–2.31 × 10{sup −5}) and even lower than that from the reference hollandite-rich synroc (2.0 × 10{sup −2}), although a higher content of Cs was found in the synthesized pollucite specimens (6.0–31.7%) than in the

  13. 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

  14. Vitrification of Concentrated Solutions of Fission Products: Technological Studies; Vitrification des Solutions Concentrees de Produits de Fission: Etudes Technologiques; 041e 0421 0422 0415 041a 041b 041e 0412 042b 0412 0410 041d 0418 0415 041a 041e 041d 0426 0415 041d 0422 0420 0418 0420 041e 0412 0410 041d 041d 042b 0425 0420 0410 0421 0422 0412 041e 0420 041e 0412 041f 0420 041e 0414 0423 041a 0422 041e 0412 0414 0415 041b 0415 041d 0418 042f : 0422 0415 0425 041d 0418 0427 0415 0421 041a 041e 0415 0418 0421 0421 041b 0415 0414 041e 0412 0410 041d 0418 0415 ; Vitrificacion de Soluciones Concentradas de Productos de Fision: Estudios Tecnologicos

    Energy Technology Data Exchange (ETDEWEB)

    Bonniaud, R.; Rancon, P. [Centre d' Etudes NuclEaires, Fontenay-aux-Roses (France)

    1963-02-15

    prior mixing, glass tapping conditions. Work is in progress on an installation having an induction-heated pot of 2 m high and some 20 cm in diam. (author) [French] La vitrification en creusets presente un certain nombre d'avantages: simplicite operatoire, perte faible d'activite a la cuisson; en revanche, pour une production donnee, l'encombrement des installations est considerable et la masse a stocker reste relativement importante. Deux procedes capables d'assurer une production importante avec un faible volume d'appareillages ont ete developpes. L'un permet la vitrification en continu, l'autre est un procede de vitrification semi-continu dit 'en pot'. L'installation de vitrification en continu experimentee a une capacite de production d'environ 100 l de solution par jour. Elle est composee d'un calcinateur rotatif relie a un four de fusion continue constitue par un creuset a trop plein chauffe par un four a resistances en super-kanthal. Ce creuset a trop plein, qui etait a l'origine en silico-alumineux ordinaire' a ete remplace par un creuset en silicate de zirconium electrofondu pour resister a l'action corrosive des verres phosphates. L'installation a fonctionne par campagnes d'environ 100 heures avec une activite 'traceur' d'une dizaine de millicuries par jour. Deux problemes importants sont a noter: a) Le taux de poussieres entrainees: intensemble de barboteurs en cascade recycle les poussieres dans le calcinateur; son efficacite est de l'ordre de 90%. b) La volatilite du ruthenium qui est encore importante. L'installation de vitrification ' en pot ' est un procede intermediaire entre le procede ci-dessus et le procede en creusets. La solution active, apres addition de fritte de verre et d'argile gelifiante est coulee en continu dans un pot maintenu a 500 Degree-Sign C jusqu'aiLremplissage complet. La calcination et l'alimentation sont simultanees. Le niveau de remplissage est determine pat mesure des temperatures internes. Apres calcination de la charge totale

  15. Fixation of Simulated Highly Radioactive Wastes in Glassy Solids; Fixation de Dechets Simules de Haute Activite dans des Soudes Vitreux; 0424 0418 041a 0421 0410 0426 0418 042f 0418 041c 0418 0422 0418 0420 041e 0412 0410 041d 041d 042b 0425 0420 0410 0414 0418 041e 0410 041a 0422 0418 0412 041d 042b 0425 041e 0422 0425 041e 0414 041e 0412 0412 042b 0421 041e 041a 041e 0419 0410 041a 0422 0418 0412 041d 041e 0421 0422 0418 0421 0422 0415 041a 041b 041e 041e 0411 0420 0410 0417 041d 042b 041c 0418 0422 0412 0415 0420 0414 042b 041c 0418 0412 0415 0429 0415 0421 0422 0412 0410 041c 0418 ; Fijacion de Desechos Simulados de Elevada Radiactividad en Solidos Vitreos

    Energy Technology Data Exchange (ETDEWEB)

    Clark, W. E.; Godbee, H. W. [Oak Ridge National Laboratory, Oak Ridge, TN (United States)

    1963-02-15

    on TBP-25 waste and from 8 to 140 mil/ month on Purex waste. Operation above 900 Degree-Sign C with Purex waste plus fluxing agents may result in catastrophic local corrosion. (author) [French] Le Laboratoire national d'Oak Ridge s'efforce actuellement de mettre au point un methode d'incorporation des dechets de haute activite dans des verres insolubles de densite elevee, tous les elements radioactifs se trouvant contenus dans la partie solide. Des experiences avec des dechets simules resultant des procedes TBP-25 (aluminium, HNO{sub 3}), Purex et Darex (acier inoxydable, HNO{sub 3}) montrent qu'une telle methode est techniquement realisable. Des solides denses, de structure microcristalline, peuvent convenir aussi bien que de veritables, verres; leur meilleure conductibilite thermique compense dans une certaine mesure le fait que la surface doit etre plus grande que dans le cas des verres. Avec les types de dechets susmentionnes, on a prepare des verres au phosphate et au borophosphate. La volatilite du cesium etait limitee a 0,1% environ du fait de l'entrainement mecanique et la volatilite du ruthenium a ete abaissee a moins de 0,5% par addition de phosphite ou d'hypophosphite. Parmi les autres additifs figuraient PbO, Ca(OH){sub 2}, NaOH et MgO. Les densites brutes variaient entre 2,36 et 2,90 g/cm{sup 3} pour les dechets du procede TBP-25 et entre 2,63 et 2,80 g/cms pour les dechets du procede Purex. Les reductions de volume correspondantes, a partir des solutions concentrees de dechets, etaient comprises entre 7,2 et 9,3 et entre 5,7 et 8,3; le passage initial a l'etat pateux se produisait entre 875 et 1000 Degree-Sign C et entre 830 et 975 Degree-Sign C respectivement. Les essais avec les dechets Darex en sont encore au stade preliminaire. En operant de maniere semi-continue a l'echelle semi-industrielle' on a obtenu un verre veritable a partir de dechets TBP-25 et un solide microcristallin a partir de dechets Purex. La conductibilite thermique du verre variait

  16. Pore-Level Investigation of Heavy Oil Recovery using Steam Assisted Gravity Drainage (SAGD Étude à l’échelle des pores de la récupération d’huiles lourdes par drainage gravitaire assisté par injection de vapeur (SAGD

    Directory of Open Access Journals (Sweden)

    Mohammadzadeh O.

    2010-12-01

    entrapment of steam due to the capillarity followed by condensation, steam condensation at the interface due to temperature gradient, and snap-off of liquid films are also illustrated using glass micromodels in pore-level visualization experiments. L’application réussie du procédé de drainage gravitaire assisté par injection de vapeur à l’aide de puits horizontaux lors de divers essais de champ, essentiellement au Canada, montre qu’on peut atteindre un taux de récupération élevé et des rapports vapeur injectée/pétrole récupéré économiquement viables. Le procédé de récupération par SAGD a été développé sur le plan théorique, testé sur pilote et commercialisé, tout cela au Canada; il reste cependant encore plusieurs problèmes techniques à résoudre dans ce procédé. Les phénomènes qui se développent à l’échelle des pores lors de la récupération d’huiles lourdes à l’aide du procédé SAGD ne sont pas encore très bien compris, ce qui conduit à intégrer la physique du processus au niveau des pores dans des modèles mathématiques. L’étude à l’échelle des pores des phénomènes physiques concernant la distribution des fluides et les types d’écoulement dans le milieu poreux dans ce procédé devrait apporter une nette amélioration de la compréhension des phénomènes macroscopiques observés aussi bien en laboratoire que sur le terrain. L’objectif principal de cet article est l’étude visuelle et la description des phénomènes à l’échelle des pores par l’utilisation d’un micromodèle en verre. Des expériences de SAGD ont été effectuées au laboratoire sur des micromodèles de réseaux capillaires gravés sur des plaques de verre qui, au départ, ont été saturés d’huile lourde. Ces expériences furent réalisées dans une chambre à vide pour éviter des pertes de chaleur excessives vers l’extérieur. Les premiers résultats montrent que lorsque l’interface huile lourde/vapeur est établie, un

  17. Borges, Ariosto e la vita segreta dei personaggi minori

    Directory of Open Access Journals (Sweden)

    Marco Dorigatti

    2013-12-01

    Full Text Available Inteso quale omaggio a Emilio Bigi, sia pure indiretto, lo studio prende spunto da un’intervista, tuttora inedita, rilasciata nel 1984 dallo scrittore argentino Jorge Luis Borges, in cui aveva citato, credendoli ariosteschi, dei versi che per lui, giunto in età ormai avanzata, erano diventati, più che un motto, una metafora di vita. Poco importa che, come verrà chiarito vagliando la loro storia e le relative fonti, quei versi, facenti capo alla misteriosa figura di un personaggio saraceno, Alibante di Toledo, in realtà appartenessero all’officina poetica di Francesco Berni: essi vengono ciò nondimeno assunti quale filo conduttore per un percorso esplorativo all’interno dell’Orlando furioso che ne vaglia la valenza per così dire “ariostesca”, giusta la reminiscenza borgesiana. Approdata infine a Cervantes, la discussione si conclude facendo ritorno a Borges e misurando l’impatto che quei medesimi versi hanno avuto sulla sua propria opera poetica.Intended as a heartfelt tribute to Emilio Bigi, albeit an indirect one, this essay draws on an interview, still unpublished, given by Argentine writer Jorge Luis Borges in 1984, in which he quoted a couple of lines of poetry which he firmly believed to be by Ariosto, and which for him, by then an old man, had become, more than a motto, a metaphor of life. It does not really matter that, as will become apparent retracing their history as well as their sources, these lines, centring on the mysterious figure of a Saracen character called Alibante of Toledo, actually belonged to Francesco Berni: they are here assumed as the main motif to be explored within Orlando furioso, in order to ascertain to what extent their nature may be regarded to be Ariostan, just as Borges thought. Having finally reached Cervantes, the discussion concludes by returning once more to Borges and considering the impact that these lines, which had remained engrained in his memory throughout his life, had on his own

  18. Identification et prise en charge des femmes ayant des antécédents familiaux de cancer du sein

    Science.gov (United States)

    Heisey, Ruth; Carroll, June C.

    2016-01-01

    Résumé Objectif Résumer les meilleures données portant sur les stratégies d’identification et de prise en charge des femmes qui présentent des antécédents familiaux de cancer du sein. Sources d’information Une recherche a été effectuée sur PubMed à l’aide des mots-clés anglais suivants : breast cancer, guidelines, risk, family history, management et magnetic resonance imaging screening, entre 2000 et 2016. La plupart des données sont de niveau II. Message principal Une bonne anamnèse familiale est essentielle lors de l’évaluation du risque de cancer du sein afin d’identifier les femmes qui sont candidates à une recommandation en counseling génétique pour un éventuel test génétique. On peut sauver des vies en offrant aux femmes porteuses d’une mutation au gène BRCA des interventions chirurgicales de réduction des risques (mastectomie bilatérale prophylactique, salpingo-ovariectomie bilatérale). Il faut encourager toutes les femmes qui présentent des antécédents familiaux de cancer du sein à demeurer actives et à limiter leur consommation d’alcool à moins de 1 verre par jour; certaines femmes sont admissibles à la chimioprévention. Il faut offrir aux femmes dont le risque à vie de cancer du sein est de 20 à 25 % ou plus un dépistage poussé par imagerie par résonance magnétique en plus d’une mammographie. Conclusion Une vie saine et la chimioprévention (chez les candidates) pourraient réduire l’incidence du cancer du sein; le dépistage poussé pourrait entraîner une détection plus précoce. Le fait d’aiguiller des femmes porteuses d’une mutation au BRCA vers la chirurgie de réduction des risques sauve des vies. PMID:27737991

  19. Entraînement de globules d'huile par un tensio-actif. Etude de la formation du banc Mobilization of Oil Ganglia by a Surfactant Analysis of Bank Formation

    Directory of Open Access Journals (Sweden)

    Moulu J. C.

    2006-11-01

    Full Text Available Lors de l'injection d'une solution de tensio-actif dans un gisement déjà balayé par de l'eau, l'huile résiduelle, piégée sous la forme de globules discontinus, est remise en mouvement et se regroupe éventuellement sous la forme d'un banc d'huile. Le but de la présente étude est d'expliquer la formation de ce banc au cours d'un tel déplacement. Les résultats d'expériences réalisées en micromodèles de billes de verre permettent de constater que : - la récupération globale est corrélable avec le nombre capillaire Nc= uVdf/O, u et Vdf étant la viscosité et la vitesse de Darcy du fluide injecté, O la tension interfaciale avec l'huile en place ; - la vitesse des globules varie différemment avec u, Vdf, O et tend vers la même limite plus grande que la vitesse du fluide injecté pour de grandes valeurs du nombre capillaire Nc ; - le banc d'huile ne se forme que dans le cas où la vitesse des globules atteint celle du fluide injecté. L'huile déplacée reste alors groupée avec une saturation importante au niveau du front de tensio-actif. When a surfactant solution is injected into a reservoir previously waterflooded, the residual oil trapped as discontinuous ganglia is mobilized and eventually bunched together forming an oil bank. The aim of this study is to explain the formation of this bank during such a drive. The results of experiments performed in micromodels of glass beads show that: a Overall recovery can be correlated with the capillary number, Nc = uVfd/O, in which u and Vfd are the viscosity a and Darcy velocity of the injected fluid and O is the interfacial tension with the oil in place. b Ganglia velocity varies differently with u, Vfd and O, and it tends towards the same limit faster than the velocity of the injected fluid for high values of the capillary number Nc. c The oil bank is formed only in the case where globule velocity attaints that of injected fluid. the dispaced oil then remains bunched, with high

  20. Incontri e riflessioni con studentesse universitarie in Europa / Rencontres et réflexions avec des étudiantes universitaires en Europe / Meetings and reflections with European female university students

    Directory of Open Access Journals (Sweden)

    Sette Raffaella

    2013-07-01

    Full Text Available Con riferimento alla ricerca europea “Gender-Based Violence, Stalking and Fear of Crime – Prevention and Intervention”, nell’articolo vengono messi a confronto alcuni dati ricavati dalla somministrazione di un questionario a studentesse di 34 università ubicate in Germania, Inghilterra, Italia, Polonia e Spagna. In particolare, ci si soffermerà su aspetti relativi alle difficoltà riscontrate nel riconoscere la violenza e al raccontarla ad altri e su caratteristiche dell’esperienza subìta.Infine, verrà focalizzata l’attenzione su alcune tematiche che si collegano all’identificazione di buone prassi per prevenire ed intervenire in casi di violenza di genere a danno di studentesse universitarie. RésuméEn référence à la recherche européenne “Gender-Based Violence, Stalking and Fear of Crime – Prevention and Intervention”, dans cet article, l’auteur analyse des données provenant d’un questionnaire soumis aux étudiantes de 34 universités situées en Allemagne, en Angleterre, en Italie, en Pologne et en Espagne. L’auteur se concentre tout particulièrement sur certains aspects liés aux difficultés rencontrées pour reconnaître la violence et pour la raconter aux autres, et sur certaines caractéristiques de l’expérience vécue. Enfin, l’auteur concentre son attention sur les bonnes pratiques à adopter pour prévenir la violence de genre infligée aux étudiantes universitaires et intervenir contre celle-ci.AbstractReferring to the European research “Gender-Based Violence, Stalking and Fear of Crime – Prevention and Intervention”, in this article the author will compare some data gathered from a questionnaire carried out among female students of 34 universities situated in Germany, England, Italy, Poland and Spain. In particular, the author will dwell on some aspects related to difficulties in recognizing violence, disclosing this experience, and on some characteristics of it.In conclusion, the

  1. Development of Geiger-Mueller counters for operation at high temperatures; Mise au point de compteurs Geiger-Mueller fonctionnant a haute temperature; Razrabotka schetchikov Gejgera-Myullera, rabotayushchikh pri povyshennoj temperature; Contadores Geiger-Mueller que funcionan a temperaturas elevadas

    Energy Technology Data Exchange (ETDEWEB)

    Draghicescu, M [Institut de Physique Atomique, Bucarest (Romania)

    1962-04-15

    Counters of this type are necessary for radioactive logging at great depths; they have to operate normally at temperatures up to 180{sup o}C. In order to preserve their characteristics under such conditions, the work function of the cathode has been improved by a special treatment. Tests have been made on counters with graphite, copper and wolfram cathodes in a glass envelope. The method is simple, and can easily be employed in industry. (author) [French] De tels compteurs sont necessaires pour le sondage radioactif aux grandes profondeurs; ils doivent fonctionner dans des conditions normales jusqu'a la temperature de 180{sup o}C. Afin qu'ils puissent conserver leurs caracteristiques jusqu'a cette temperature, on a agi sur le travail de sortie de la cathode par un traitement adequat. On a fait l'essai sur des compteurs avec cathode de graphite, de cuivre ou de tungstene, dans un ballon de verre. La methode proposee est simple et peut etre appliquee facilement dans l'industrie. (author) [Spanish] Se requiere este tipo de contador para la determinacion de la radiactividad a grandes profundidades; debe ser capaz de funcionar normalmente a temperaturas hasta de 180{sup o}C. A fin de que sus caracteristicas se conserven inalteradas hasta tales temperaturas, se ha modificado la funcion de trabajo del catodo mediante un tratamiento adecuando. Se han ensayado contadores con catodo de grafito, de cobre o de wolframio en un balon de vidrio. El metodo propuesto es simple y puede aplicarse facilmente en la industria. (author) [Russian] Podobnye schetchiki neobkhodimy dlya radioaktivnogo karottazha na bol'shikh glubinakh; oni dolzhny funktsionirovat' v normal'nykh usloviyakh pri temperature do 180{sup o}C. Nakonets, dlya togo, chtoby oni mogli sokhranyat' svoi osobennosti pri ehtoj temperature, bylo obrashcheno vnimanie na rabotu katodnogo vykhoda pri pomoshchi sootvetstvuyushchej obrabotki. Byl proveden opyt na schetchikakh s grafitovym, mednym ili vol'framovym katodom v

  2. Les milieux extrêmes. Journées d'études du CESTA, Paris, 4-5 octobre 1983 Extreme Environments. Cesta Conference, Paris, 4-5 October 1983

    Directory of Open Access Journals (Sweden)

    Bertrand A. R. V.

    2006-11-01

    Full Text Available Ces journées d'études étaient consacrées aux problèmes impliqués par l'exploration et l'exploitation des milieux extrêmes. On n'a pas cherché à approfondir la notion de milieu extrême mais à en étudier trois principaux : l'espace, les grands fonds marins, les enceintes soumises à de forts rayonnements nucléaires, à travers quatre thèmes de problèmes communs : la robotique, la sécurité, les matériaux et l'intervention humaine. Cette réunion a mis en évidence : - le dilemme constitué par la nécessité d'assurer d'une part la sécurité de la population par l'emploi de techniques fiables donc éprouvées et d'autre part le progrès scientifique dont les techniques nouvelles peuvent être fiables sans être encore éprouvées ; - l'emploi généralisé de la robotique (soudage sous-marin profond, engin submersible non habité à intelligence artificielle. . . ; - la création de matériaux nouveaux (composites à matrice métallique, fibres optique en verre chloré, lubrifiant opérant sous vide. . . - la mise au point de méthodes nouvelles pour l'analyse probabiliste des risques. This conference concentrated on the problems raised by the exploration and productive use of extreme environments. No effort was made to define the concept of an extreme environnent, but three specific ones were considered: space, great sea depths, enclosures subjected Io intense nuclear radiation. There were four topics covering problems encountered in such environments: robotics, safety, materials and human intervention. This meeting brought out the following points: - The dilemma brought on by the need to ensure part of the safety of the population by using reliable, hence proven, techniques at the saure time as scientific progress in which new techniques may be reliable without yet being proven. - The generalized use of robotics (deep subsea welding, unmanned submersible with artificial intelligence, etc. . - The creation of new materials

  3. Thermic decomposition of biphenyl; Decomposition thermique du biphenyle

    Energy Technology Data Exchange (ETDEWEB)

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

    1966-03-01

    Liquid and vapour phase pyrolysis of very pure biphenyl obtained by methods described in the text was carried out at 400 C in sealed ampoules, the fraction transformed being always less than 0.1 per cent. The main products were hydrogen, benzene, terphenyls, and a deposit of polyphenyls strongly adhering to the walls. Small quantities of the lower aliphatic hydrocarbons were also found. The variation of the yields of these products with a) the pyrolysis time, b) the state (gas or liquid) of the biphenyl, and c) the pressure of the vapour was measured. Varying the area and nature of the walls showed that in the absence of a liquid phase, the pyrolytic decomposition takes place in the adsorbed layer, and that metallic walls promote the reaction more actively than do those of glass (pyrex or silica). A mechanism is proposed to explain the results pertaining to this decomposition in the adsorbed phase. The adsorption seems to obey a Langmuir isotherm, and the chemical act which determines the overall rate of decomposition is unimolecular. (author) [French] Du biphenyle tres pur, dont la purification est decrite, est pyrolyse a 400 C en phase vapeur et en phase liquide dans des ampoules scellees sous vide, a des taux de decomposition n'ayant jamais depasse 0,1 pour cent. Les produits provenant de la pyrolyse sont essentiellement: l' hydrogene, le benzene, les therphenyles, et un depot de polyphenyles adherant fortement aux parois. En plus il se forme de faibles quantites d'hydrocarbures aliphatiques gazeux. On indique la variation des rendements des differents produits avec la duree de pyrolyse, l'etat gazeux ou liquide du biphenyle, et la pression de la vapeur. Variant la superficie et la nature des parois, on montre qu'en absence de liquide la pyrolyse se fait en phase adsorbee. La pyrolyse est plus active au contact de parois metalliques que de celles de verres (pyrex ou silice). A partir des resultats experimentaux un mecanisme de degradation du biphenyle en phase

  4. Vibrations et relaxations dans les molécules biologiques. Apports de la diffusion incohérente inélastique de neutrons

    Science.gov (United States)

    Zanotti, J.-M.

    2005-11-01

    Le présent document ne se veut pas un article de revue mais plutôt un élément d'initiation à une technique encore marginale en Biologie. Le lecteur est supposé être un non spécialiste de la diffusion de neutrons poursuivant une thématique à connotation biologique ou biophysique mettant en jeu des phénomènes dynamiques. En raison de la forte section de diffusion incohérente de l'atome d'hydrogène et de l'abondance de cet élément dans les protéines, la diffusion incohérente inélastique de neutrons est une technique irremplaçable pour sonder la dynamique interne des macromolécules biologiques. Après un rappel succinct des éléments théoriques de base, nous décrivons le fonctionnement de différents types de spectromètres inélastiques par temps de vol sur source continue ou pulsée et discutons leurs mérites respectifs. Les deux alternatives utilisées pour décrire la dynamique des protéines sont abordées: (i)l'une en termes de physique statistique, issue de la physique des verres, (ii) la seconde est une interprétation mécanistique. Nous montrons dans ce cas, comment mettre à profit les complémentarités de domaines en vecteur de diffusion et de résolution en énergie de différents spectromètres inélastiques de neutrons (temps de vol, backscattering et spin-écho) pour accéder, à l'aide d'un modèle physique simple, à la dynamique des protéines sur une échelle de temps allant d'une fraction de picoseconde à quelques nanosecondes.

  5. Study of various processes for marking sediments with gold-198; Etude de divers procedes de marquages de sediments par l'or 198

    Energy Technology Data Exchange (ETDEWEB)

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

    1967-12-15

    The use of radioactive isotopes for the study of sediment deposits is based mainly on two methods: marking in the mass - a glass of an element which can be activated replaces the sediment; surface marking - a physico-chemical process is used to deposit a radio-element at the surface of the sediment. The second process is used in particular for sands when it is advantageous to have a large number of particles for statistical analysis. The aim of this work was to develop a rapid and simple method of marking which could be applied on the actual site of the experiment where equipment, may be limited. The method recommended for marking sand with gold-198 is a combination of the Petersen (treatment with tin chloride) and Campbell (treatment with silver) methods combined with prior treatments with nitric acid and caustic soda. Using this method it is possible to deposit 125 mg of gold per kilo of sediment with a yield of 95 per cent (i.e. 10 Ci/kg) using a hydrochloric acid solution containing gold. The problem of the solidity of the deposits, of their value and of their reproducibility is discussed from the point of view of the mineral constitution of the sand. (author) [French] L'utilisation d'isotopes radioactifs pour l'etude des deplacements sedimentaires fait, principalement appel a deux methodes: le marquage massique - un verre contenant un element activable remplace le sediment; le marquage superficiel - un traitement physico-chimique permet de deposer un radioelement a la surface du sediment. Le second procede est surtout employe pour les sables lorsqu'il est utile de disposer d'un grand nombre de grains pour des raisons statistiques. Le but de ce travail etait de mettre au point une methode simple et rapide de marquage pouvant etre appliquee sur le site meme de l'experience pour les utilisateurs disposant d'un equipement limite. Le procede preconise pour le marquage des sables par l'or 198 est une combinaison des methodes Petersen (traitement au chlorure d

  6. The effect of surface roughness on the heat exchange and pressure-drop coefficients; Influence des rugosites de paroi sur les coefficients d'echange thermique et de perte de charge

    Energy Technology Data Exchange (ETDEWEB)

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

    1963-02-15

    The effect of various types of roughness on the wall of an axial tube in an annular space of 15-25 mm cooled by an air-flow has been studied in the case of steady turbulence. Roughness of the type 'disrupter of the boundary layer' was set up using triangular threads of 0.2 to 0.4 mm thickness machined in the tube itself, or brass or glass wire wound on a smooth tube. Tests were also carried out using the roughness provided by regularly spaced pyramids 0.4 mm high. The results obtained showed that the heat exchange increased because of the presence of this roughness. A maximum in the heat exchange and pressure-drop coefficients was observed when the pitch equals about eight times the height of the thread. An analytical method has been developed and experiments have been carried out in which the two walls of the annular space were heated in such a way as to transmit unequal heat flows. The region considered is limited to Reynolds's numbers of between 5 X 10{sup 3} and 5 x 10{sup 4} and wall temperatures of under 250 deg C. (author) [French] L'effet de diverses rugosites sur la paroi du tube central d'un espace annulaire de diametre 15-25 mm refroidi par un ecoulement d'air a ete etudie en regime turbulent etabli. Des rugosites du type 'interrupteur de couche limite' etaient realisees au moyen de filets triangulaires, de 0,2 a 0,4 mm de hauteur usines dans l'epaisseur du tube ou de fils de laiton, ou de verre, enroules sur un tube lisse. Les essais ont porte egalement sur des rugosites constituees par des pyramides de 0,4 mm de hauteur et regulierement espacees. Les resultats obtenus ont mis en evidence une augmentation de transfert de chaleur due a la presence des elements rugueux. L'existence d'un maximum pour les coefficients d'echange thermique et de perte de charge a ete constate lorsque le pas atteint huit fois la hauteur des rugosites. Une methode analytique a ete etablie et des experiences ont ete realisees au cours desquelles les deux parois de l

  7. Setting-Up of a Neutron Dosimeter Using Ionographic Tracks in an Insulating Solid; Realisation d'un Dosimetre a Neutrons Utilisant les Traces Ionographiques dans un Solide Isolant

    Energy Technology Data Exchange (ETDEWEB)

    Carfi, N.; Dugnani Lonati, R.; Mangialajo, M. [Centro Informazioni Studi Esperienze, Segrate, Milan (Italy)

    1971-06-15

    The use of dielectrics such as mica, glasses and plastic materials for charged particle track recording has been developed in the past years; track recording of fission fragments produced in fissile materials under neutron irradiation is particularly interesting. The method has not as yet been applied to neutron dosimetry owing to the difficulties of track observation and counting using optical microscopes. A method has recently been proposed which results in markedly reduced counting times, electronic counting of the electric discharges between two electrodes through the dielectric which was perforated by the fission fragments. The reasons for adopting this new technique to set-up a neutron dosimeter are: (a) economic advantages, since a rather simple electronic instrumentation will give a reading of the dosimeter, preparation of which can be carried out immediately and at a modest cost; (b) fast reading, since the response can be obtained in less than two hours from irradiation; (c) dosimetric advantages owing to the lack of fading and insensitivity to {beta} or {gamma} radiations. The present work describes the method adopted and the equipment used to set up the dosimeter. Results are reported and briefly discussed. (author) [French] Au cours des dernieres annees on a assiste a un developpement remarquable de l' utilisation d' isolants tels que le mica, les verres et les materiaux plastiques pour l' enregistrement des traces de particules chargees; l' enregistrement des traces de fragments de fission produits dans les materiaux fissiles sous irradiation neutronique est particulierement interessant. Cette methode n'a pas, jusqu a present, ete appliquee a la dosimetrie des neutrons a cause des difficultes que presentent l' observation et le comptage des traces au microscope optique. On a propose recemment une methode qui permet de reduire considerablement la duree de l' operation en comptant electroniquement les decharges electriques qui se produisent entre deux

  8. Impact of nutrition since early life on cardiovascular prevention

    Directory of Open Access Journals (Sweden)

    Guardamagna Ornella

    2012-12-01

    nutrizione svolge un ruolo preventivo fondamentale sin dall’epoca prenatale e nelle diverse età della crescita. La condizione metabolica e neuro-endocrino cui è sottoposto il feto è rilevante per la “programmazione metabolica”. E’ dimostrata inoltre l’importanza delle modalità di allattamento e divezzamento con particolare interesse per l’assunzione di proteine nel controllo dei fattori di rischio cardiovascolari. La corretta distribuzione di macronutrienti (lipidi, proteine e carboidrati dall’infanzia all’adolescenza favorisce una crescita corretta e risulta utile a prevenire l’insorgenza dei determinanti di rischio di malattia cardiovascolare in età adulta. Nella presente review verrà esaminato l’impatto della nutrizione dalle più precoci fasi delle vita sul rischio cardiovascolare.

  9. Analytic implementation of the GRAAL model: Application to a R7T7-type glass package in a geological disposal environment

    Energy Technology Data Exchange (ETDEWEB)

    Minet, Y., E-mail: yves.minet@cea.f [CEA Marcoule, DTCD/SECM/LCLT, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France); Bonin, B. [CEA Saclay, DEN/DIR/DS, 91191 Gif-sur-Yvette Cedex (France); Gin, S.; Frugier, P. [CEA Marcoule, DTCD/SECM/LCLT, BP 17171, 30207 Bagnols-sur-Ceze Cedex (France)

    2010-09-30

    The Glass Reactivity with Allowance for the Alteration Layer Model (GRAAL) was proposed in 2008 to describe borosilicate nuclear glass alteration based on coupling an affinity law with the formation and dissolution of a passivating reactive interface. It is examined here in a simplified form in which only the affinity with respect to silicon is taken into account with a concentration at saturation C{sub sat}, and the precipitation of neoformed phases is described by an affine relation for silicon above a precipitation threshold C{sub sat}{sup '}. This simplified 'analytical GRAAL' model is capable of predicting the quantities of altered glass and the silicon and boron concentration variations in analytical or semi-analytical form, and thereby identify the main characteristic quantities of the system. The model was tested against a series of laboratory experiments lasting from a few days to a few years; its sensitivity to the parameter values was examined, and the model was validated with respect to SON68 glass alteration in initially pure water. It was then applied to the alteration of a glass package in a repository over periods of up to a million years, by means of exploratory calculations comprising a sensitivity study of the internal model parameters and extrapolation to the temperatures expected in a geological repository in order to identify the parameters and mechanisms having the greatest impact on the residual alteration rate. Alteration is controlled by the precipitation of neoformed phases in every case. The transient conditions are of very limited duration with respect to either silicon or boron (no more than a 100 years, with less than 0.01% alteration of the package). In the precipitation law used in the model, the residual alteration rate and total package lifetime are determined primarily by two parameters: k' (the precipitation kinetics) and {sigma}' (the precipitate surface area per unit volume in the geological barrier

  10. 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

  11. Understanding the residence of Co in ore minerals - towards the development of novel Co extraction strategies for laterite deposits

    Science.gov (United States)

    Dybowska, Agnieszka; Norman, Rachel; Schofield, Paul; Herrington, Richard

    2017-04-01

    XRD. These low abundance minerals, identified in the samples using Raman spectroscopy, µXRD and EPMA, proved however to be very important Co-hosting phases. Electron microscopy and µ-XRF mapping revealed a strong Mn and Co association in all samples but little correlation between Co and Fe. The important determinant of Co concentration is thus its association with Mn oxides, a variety of which have been found in the samples studied. For example, in Shevchenko laterite asbolane was identified with Co concentrations varying from 0.25 to 12.4 wt% (6.3 wt% on average). Goethite was found to carry only minor Co i.e. below 0.03 wt% or 0.1-0.2 wt%. In samples from the Nkamouna laterite Mn oxide minerals were found to contain Co ranging widely from below 1 wt% in tectomanganate phases such as hollandite and pyrolusite, 5.5% wt% in lithiophorite and up to 21 wt% in lithiophorite-asbolane intermediates. No Co or minor Co (<0.1 wt%) was detected in Fe oxides and oxy-hydroxides. XANES spectroscopy shows that Co is bound in a range of Mn oxide minerals as Co3+. The structural environment of Co in these minerals is very similar with Co in octahedral coordination. Analysis of the EXAFS data for asbolane shows an apparent high degree of structural order around Co which suggest that Co is present as clustered aggregates. Our results indicate that Co should be efficiently and selectively removed from the studied laterites by targeted solubilisation of Mn oxides, which can be achieved via, for example, microbially mediated reductive mineral dissolution.

  12. Mineralogy of subducted clay and clay restite in the lower mantle

    Science.gov (United States)

    Armstrong, L.; Skora, S. E.; Walter, M. J.

    2012-12-01

    Seismic tomography indicates that subducting oceanic lithosphere often penetrates the transition zone and eventually the lower mantle [e.g. 1, 2]. While mineralogical changes in the mafic and ultramafic portions of slabs have been well documented experimentally, the phase relations of overlying sediments at pressures above 25 GPa remain poorly studied. This is in part because sediments are expected to partially melt at sub-arc depth (P~2.5-4.5 GPa), and contribute to the genesis of arc magmas. Sediment restites left behind after the extraction of low pressure melts undergo major chemical changes, according to the melting reaction: Coe+Phen+Cpx+H2O = Grt+Ky+Melt [3]. However, sediments may not always melt depending on the thermal regime and volatile availability and composition [3]. Hence, chemically unmodified sediments as well as restites may be entrained to greater depths and contribute to compositional heterogeneity in the deep mantle. Indeed, mineral inclusions with compositions indicative of subducted sedimentary protoliths (CAS-phase; K-hollandite; stishovite) have been reported in 'ultradeep' diamonds and suggest that deep subduction and survival of sediments occurs to at least transition zone depths [4]. With this in mind, we have performed laser heated diamond anvil cell experiments at pressures of 8-80 GPa on two anhydrous glass starting materials: a marine clay and the restite that is left after 50% melt extraction of this clay at 3 GPa and 800 °C [3]. We chose to work with an anhydrous version of the marine clay given that the investigated pressure range exceeds that of phengite stability [5], and phengite is the only hydrous phase in subducted sediments at UHP conditions. The clay was heated along a P-T path representative of a cold subduction geotherm, whereas the clay restite was heated along a hotter subduction geotherm consistent with low pressure melting. Phases were identified by synchrotron X-ray micro-diffraction at beamline I15 of the Diamond

  13. Crystal structures and thermal decomposition of permanganates AE[MnO{sub 4}]{sub 2} . n H{sub 2}O with the heavy alkaline earth elements (AE=Ca, Sr and Ba)

    Energy Technology Data Exchange (ETDEWEB)

    Henning, Harald; Bauchert, Joerg M.; Conrad, Maurice; Schleid, Thomas [Stuttgart Univ. (Germany). Inst. fuer Anorganische Chemie

    2017-10-01

    next to amorphous phases. On the other hand, the already anhydrous Ba[MnO{sub 4}]{sub 2} thermally decomposes to hollandite-type BaMn{sub 8}O{sub 16} and BaMnO{sub 3} at 800 C.

  14. Crystalline Ceramic Waste Forms: Comparison Of Reference Process For Ceramic Waste Form Fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Brinkman, K. S. [Savannah River National Laboratory; Marra, J. C. [Savannah River National Laboratory; Amoroso, J. [Savannah River National Laboratory; Tang, M. [Los Alamos National Laboratory

    2013-08-22

    The research conducted in this work package is aimed at taking advantage of the long term thermodynamic stability of crystalline ceramics to create more durable waste forms (as compared to high level waste glass) in order to reduce the reliance on engineered and natural barrier systems. Durable ceramic waste forms that incorporate a wide range of radionuclides have the potential to broaden the available disposal options and to lower the storage and disposal costs associated with advanced fuel cycles. Assemblages of several titanate phases have been successfully demonstrated to incorporate radioactive waste elements, and the multiphase nature of these materials allows them to accommodate variation in the waste composition. Recent work has shown that they can be produced from a melting and crystallization process. The objective of this report is to explore the phase formation and microstructural differences between lab scale melt processing in varying gas environments with alternative densification processes such as Hot Pressing (HP) and Spark Plasma Sintering (SPS). The waste stream used as the basis for the development and testing is a simulant derived from a combination of the projected Cs/Sr separated stream, the Trivalent Actinide - Lanthanide Separation by Phosphorous reagent Extraction from Aqueous Komplexes (TALSPEAK) waste stream consisting of lanthanide fission products, the transition metal fission product waste stream resulting from the transuranic extraction (TRUEX) process, and a high molybdenum concentration with relatively low noble metal concentrations. Melt processing as well as solid state sintering routes SPS and HP demonstrated the formation of the targeted phases; however differences in microstructure and elemental partitioning were observed. In SPS and HP samples, hollandite, pervoskite/pyrochlore, zirconolite, metallic alloy and TiO{sub 2} and Al{sub 2}O{sub 3} were observed distributed in a network of fine grains with small residual pores

  15. Effects of Interfacial Reaction on the Radial Displacement of Oil by Alkaline Solutions Effets des réactions interfaciales sur le déplacement radial de l'huile par les solutions alcalines

    Directory of Open Access Journals (Sweden)

    Nasr-El-Din H. A.

    2006-11-01

    'eau, de géométrie radiale. Pour visualiser le processus de déplacement, on utilise un milieu poreux constitué de perles de verre fritté placées entre deux plaques de verre. Le milieu est initialement saturé avec la phase huileuse, à savoir l'huile de paraffine (non réactive, ou l'huile de paraffine enrichie de 1 % en poids d'acide linoléique (réactif. On étudie expérimentalement les effets du débit de l'injection et de la concentration en NaOH dans la phase aqueuse sur le schéma du déplacement. On mesure également la récupération en volume d'huile à l'épreuve de la filtration. Des mesures de tension interfaciale (IFT du système réactif ont été prises à l'aide d'un tensiomètre à goutte tournante. Une chute importante de la tension interfaciale traduit la réaction chimique à l'interface entre l'acide linéoléique de la phase huileuse et la soude NaOH de la phase aqueuse. On a également trouvé que l'évolution de la tension interfaciale IFT par rapport au temps dépendait de la concentration en NaOH, avec une activité interfaciale maximum (IFT minimum pour une concentration de 0,1 % de NaOH en poids. Les essais de déplacement font apparaître un changement significatif des schémas de déplacement au cours de la récupération secondaire du système réactif par rapport à ceux du système non réactif. Une chute significative de la récupération par filtration est obtenue pour les systèmes réactifs, particulièrement pour les débits d'injection élevés. On a trouvé que la récupération du système réactif variait suivant la concentration de NaOH dans la phase aqueuse, avec une récupération minimum pour 0,1 % de NaOH en poids.

  16. Axisymmetric Drainage in Hydrophobic Porous Media Micromodels Drainage en géométrie axisymétrique dans des milieux poreux hydrophobes à deux dimensions

    Directory of Open Access Journals (Sweden)

    Cuenca A.

    2013-01-01

    capillaires (Ca communément rencontrés lors des opérations d’extraction pétrolière. Nous utilisons deux types de micromodèles mouillables à l’huile : le premier est basé sur une méthode de déposition innovante permettant d’obtenir des monocouches de billes de verre de taille micronique, tandis que le second est microfabriqué dans du verre à partir de réseaux poreux aléatoires générés informatiquement. Chacun des modèles utilise un schéma d’injection central dans une géométrie radiale, ce qui engendre une variation continue du nombre capillaire pendant le drainage. Nous menons tout d’abord une analyse du drainage à l’échelle globale du micromodèle en couplant analyse d’image et mesures de pression et de débit. Les paramètres de base tels que perméabilité, porosité et saturation résiduelle en huile des modèles sont extraits dans cette première phase. Nous exploitons ensuite les possibilités de visualisation offertes par les micromodèles transparents pour mener une analyse locale du phénomène d’invasion. Les saturations locales et la largeur de front sont mesurées en fonction du nombre capillaire local. De façon intéressante, du fait de la géométrie radiale, nos expériences permettent de tracer continûment les courbes de désaturation capillaire sur plusieurs décades. Comme inféré, mais jamais observé précisément, les mesures de diverses expériences se regroupent sur une courbe maîtresse pour un micromodèle donné. Nous observons cependant des différences notables entre les deux types de micromodèle. Ces observations sont discutées à la lumière des différences géométriques existant entre les deux micromodèles à l’échelle du pore.

  17. Specific outcomes of the research on the radiation stability of the French nuclear glass towards alpha decay accumulation

    Science.gov (United States)

    Peuget, S.; Delaye, J.-M.; Jégou, C.

    2014-01-01

    This paper presents an overview of the main results of the French research on the long-term behavior of SON68 nuclear glass towards alpha decay accumulation. The effect of the radiation damage induced by alpha decay and also helium build-up were investigated by examining glass specimens, doped with a short-lived actinide 244Cm, irradiated by light and heavy ions. Additionally, atomistic simulations by molecular dynamics have provided further information on the atomic-scale effects of the macroscopic phenomena observed. These studies have shown that some macroscopic properties vary with the accumulation of alpha decay, but then stabilize after integrated doses of the order of 4 × 1018 α g-1. For example, the glass density diminishes by about 0.6%, its Young's modulus by about 15%, and its hardness by about 30%, while its fracture toughness increases by around 50%. The SEM and TEM characterization showed that the glass is still homogeneous. No phase separation, crystallization or bubbles formation was noticed up to an alpha decay dose corresponding to several thousand years of disposal of nuclear glass canister. Moreover the initial alteration rate of the glass is not significantly affected by the glass damage induced by alpha decays or heavy ions irradiations. The comparison of the macroscopic evolutions of the Cm doped glass with those obtained for glasses irradiated with light or heavy ions (from either experimental and molecular dynamic studies) suggests that the macroscopic evolutions are induced by the nuclear interactions induced by the recoil nuclei of alpha decay. The analysis of the behavior of the glass structure subjected to ballistic effects with various spectroscopic studies, together with the results of atomistic modeling by molecular dynamics, have identified some slight changes in the local order around some cations. Moreover a modification of the medium-range order has also been demonstrated through changes in the bond angles between network

  18. Specific outcomes of the research on the radiation stability of the French nuclear glass towards alpha decay accumulation

    Energy Technology Data Exchange (ETDEWEB)

    Peuget, S., E-mail: sylvain.peuget@cea.fr; Delaye, J.-M.; Jégou, C.

    2014-01-15

    This paper presents an overview of the main results of the French research on the long-term behavior of SON68 nuclear glass towards alpha decay accumulation. The effect of the radiation damage induced by alpha decay and also helium build-up were investigated by examining glass specimens, doped with a short-lived actinide {sup 244}Cm, irradiated by light and heavy ions. Additionally, atomistic simulations by molecular dynamics have provided further information on the atomic-scale effects of the macroscopic phenomena observed. These studies have shown that some macroscopic properties vary with the accumulation of alpha decay, but then stabilize after integrated doses of the order of 4 × 10{sup 18} α g{sup −1}. For example, the glass density diminishes by about 0.6%, its Young’s modulus by about 15%, and its hardness by about 30%, while its fracture toughness increases by around 50%. The SEM and TEM characterization showed that the glass is still homogeneous. No phase separation, crystallization or bubbles formation was noticed up to an alpha decay dose corresponding to several thousand years of disposal of nuclear glass canister. Moreover the initial alteration rate of the glass is not significantly affected by the glass damage induced by alpha decays or heavy ions irradiations. The comparison of the macroscopic evolutions of the Cm doped glass with those obtained for glasses irradiated with light or heavy ions (from either experimental and molecular dynamic studies) suggests that the macroscopic evolutions are induced by the nuclear interactions induced by the recoil nuclei of alpha decay. The analysis of the behavior of the glass structure subjected to ballistic effects with various spectroscopic studies, together with the results of atomistic modeling by molecular dynamics, have identified some slight changes in the local order around some cations. Moreover a modification of the medium-range order has also been demonstrated through changes in the bond angles

  19. In Vivo and Air Dosimetry of Fission-Spectrum Neutrons; Dosimetrie In Vivo et dans l'Air du Spectre des Neutrons de Fission; Dozimetriya v vozdukhe i dozimetriya In Vivo nejtronov spektra deleniya; Dosimetria In Vivo y en el Aire de Neutrones de un Espectro de Fision

    Energy Technology Data Exchange (ETDEWEB)

    Mobley, T. S.; Engel, R. E.; Godden, W. R. [Kirtland Airforce Base, New Mexico (United States); Penikas, V. T. [AFIT, Wright-Patterson Air Force Base, Ohio, with Duty Station at University of Rochester, School of Medicine and Dentistry, Rochester, NY (United States)

    1964-03-15

    internal package varied with burst temperature rise, distance from the reactor, orientation of the foils with respect to the reactor, and the thickness and composition of the attenuating tissues. (author) [French] En vue d'evaluer la dose profonde du fait de l'exposition au spectre des neutrons de fission, les auteurs ont mis au point une methode de dosimetrie in vivo sur le mouton. On a utilise pour ces etudes un reacteur a flux puise semblable a l'appareil GODIVA II du Laboratoire scientifique de Los Alamos. En regime puise, le reacteur donne une impulsion d'une largeur de 50 {mu}s a la moitie du maximum d'amplitude pour une elevation de temperature du combustible d'environ 100 Degree-Sign C. Une insertion sous-cutanee contient une feuille d'or recouverte de cadmium, une feuille d'or nue et trois dosimetres en verre thermoluminescent places dans un etui de lithium et de plomb double de verre. On a place les insertions dans le tissu sous-cutane des deux cotes du corps pour detecter la dose totale de neutrons thermiques-gamma, les neutrons etant delivres sur les flancs. Des insertions abdominales sont preparees a peu pres de la meme facon que les insertions sous-cutanees; elles sont constituees d'une boule de bore contenant des feuilles a seuil de fission (Pu, Np, Ue) recouvertes de cadmium, d'un comprime de soufre et de trois dosimetres identiques a ceux des insertions sous-cutanees. On les a placees dans l'abdomen des sujets 18 h avant l'exposition, en les fixant au pilier anterieur du rumen. Les auteurs decrivent un procede de rumenotomie. On a determine la dose de neutrons au moyen de la feuille a seuil. On a utilise les feuilles d'or et les feuilles d'or recouvertes de cadmium pour determiner le flux integre de neutrons thermiques, le plutonium-239, le neptumum-237, l'uranium-238 et le soufre-32 pour determiner le flux integre de neutrons rapides, et les batonnets de verre radiophotoluminescents pour determiner la dose gamma. Les moutons ont subi des expositions

  20. Incorporation of Radioisotopes into Melted Silicates; Incorporation de Radioisotopes dans des Silicates Fondus; 0412 0412 0415 0414 0415 041d 0418 0415 0420 0410 0414 0418 041e 0418 0417 041e 0422 041e 041f 041e 0412 0412 0420 0410 0421 041f 041b 0410 0412 041b 0415 041d 041d 042b 0415 0421 0418 041b 0418 041a 0410 0422 042b ; Incorporacion de Radioisotopos en Silicatos Fundidos

    Energy Technology Data Exchange (ETDEWEB)

    Rakova, J.; Saidl, J. [Nuclear Research Institute Rez near Prague, Czechoslovak Socialist Republic (Czech Republic)

    1963-02-15

    exclude any possible contact with water, the safety of this disposal can be guaranteed. (author) [French] Le memoire rend compte de travaux de recherche qui avaient pour but: 1. De choisir des materiaux (roche fondue ou silicate vitrifiable) se pretant a l'incorporation de radio- isotopes a longue periode biologiquement dangereux. 2. De determiner les facteurs susceptibles de diminuer la vitesse de liberation des radioisotopes incorpores, afin qu'ils ne constituent pas un danger pour la biosphere. Les auteurs ont utilise 14 echantillons de basaltes fondus provenant de la Boheme septentrionale et occidentale et trois echantillons de verres selectionnes. Au cours des experiences, on a tenu dument compte de la diffusion de radioisotopes dans les verres et les roches fondues et de la resistance chimique de ces materiaux. Pour etudier la diffusion de {sup 90}Sr et de {sup 134}Cs, on a choisi la methode de la ' couche mince ' decrite par Kryoukov et Jouchovitski, consideree comme la plus avantageuse. Dans la gamme de temperatures de 300 Degree-Sign a 600 Degree-Sign C, on a note des coefficients de diffusion de 10{sup -13} a 10{sup -11}cm{sup 2}/s. Le fait que l'energie d'activation est plus basse pour le cesium que pour le sodium confirme l'hypothese d'apres laquelle le cesium aurait une liaison plus faible que les autres coips simples vitri- fiables. En mesurant la vitesse de lixiviation du cesium et du strontium incorpores a des roches fondues, on a constate que la majeure partie de la radioactivite entrainee l'etait dans la phase initiale du processus. Apres 100 heures, le pourcentage entraine devenait constant. La vitesse de lixiviation ulterieure est probablement limitee par la corrosivite du milieu et par la diffusion interne des elements solubles, de l'interieur vers la surface du solide. On a etudie la corrosivite des verres et des roches fondues dans des conditions statiques a temperature constante (35, 60 et 90 Degree-Sign C) et on a trouve des coefficients de

  1. Thermoluminescent Dosimeter as the Gamma Component of a Nuclear Accident Dosimeter; Utilisation du Dosimetre Thermoluminescent Comme Element Detecteur Gamma d'un Dosimetre pour les cas d'Accident Nucleaire; 0422 0415 0420 041c 0414 ; Los Detectores de Termoluminiscencia Como Elemento Gammametrico de un Dosimetro para Casos de Accidente Nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Handloser, J. S. [Edgerton, Germeshausen and Grier, Inc., Santa Barbara, CA (United States)

    1965-06-15

    dans les dosimetres a utiliser en cas d'accident. Il a essaye diverses sortes de dosimetres en verre, de dosimetres a films, de dosimetres chimiques et de dosimetres a polymerisation, mais le dosimetre thermoluminescent est celui qui presente le plus d'avantages. En raison de sa grande etendue de mesure, le dosimetre thermoluminescent peut etre utilise a la fois comme appareil de controle radiologique quotidien et comme dosimetre en cas d'accident. Ce systeme rend inutile remploi d'instruments speciaux pour la dosimetrie des accidents et permet d'utiliser a cette fin les instruments bien calibres d'usage quotidien. Habituellement, l'etendue de mesure d'un dosimetre thermoluminescent est de 5 mr a 100 000 r, avec une reproductibilite de {+-} 10%. L'auteur a concu et fabrique un modele unique de dosimetre a fluorure de calcium avec dispositif de lecture pouvant mesurer de 5 mr a 5000 r. La lecture du dosimetre est realisee par chauffage du phosphore et mesure de la lumiere emise. On dispose d'instruments de lecture a six echelles de graduation et des systemes entierement automatises sont prevus. La lecture a l'aide de chacun de ces appareils ne prend pas plus de 20 s par dosimetre. Un autre avantage du dosimetre thermoluminescent est sa faible reponse aux neutrons. La reponse aux neutrons varie selon le type du support et le type de phosphore. Un modele de dosimetre au fluorure de calcium a une reponse aux neutrons de 0.27 x 10{sup -9} rad/n/cm{sup 2}. L'auteur examine deux formes physiques de dosimetres thermoluminescents. Le premier est un dosimetre a chauffage interne place sous vide dans une capsule de verre; il a approximativement les dimensions suivantes: diametre 1 cm, longueur 6 cm. Le second modele est constitue par un tube de verre de faible section dans lequel le phosphore est scelle. Ce dosimetre a un diametre de 0,8 mm et une longueur de 6 mm. L'auteur a concu des ecrans de correction de la reponse a l 'energie pour ces deux types de dosimetres. (author

  2. Study of the {rho}-bar, {beta}-bar and {lambda} parameters of a light-water reactor; Etude des parametres {rho}-bar, {beta}-bar et {lambda} d'une pile a eau legere

    Energy Technology Data Exchange (ETDEWEB)

    Riche, R. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1965-09-01

    cinetique par des equations dependant purement du temps, font apparaitre la valeur effective {beta}-bar. A partir de la cinetique, nous determinons le rapport b par analyse de transitoire de puissance consecutif a l'injection d'une variation rapide de reactivite realisee par l'implosion d'une boule de verre vide. Un depouillement relativement simple est propose. L'appareillage est reduit et se transforme aisement en reactimetre. De la theorie de la perturbation, nous deduisons une mesure de {beta}-bar, qui consiste a ponderer les effets en reactivite d'une feuille de cuivre, mesures en differents emplacements du coeur. Les valeurs calculees de l'efficacite des neutrons retardes {gamma} = {beta}-bar/{beta} 1.23 et du temps de generation des neutrons prompts {lambda} = 59 {mu}s sont en bon accord avec les resultats experimentaux: {beta}-bar = 795 pcm et {beta}-bar/{lambda} 129 s{sup -1}, les nombres precites etant relatifs a un reacteur a eau legere et a uranium enrichi (90 pour cent U-235), le coeur presentant des trous d'eau. (auteur)

  3. L’aggressività della coppia criminale: la strage di Erba analizzata nell’ottica della coscienza intersoggettiva di D. Stern/L'agressivité des couples criminels : le massacre de Erba analysé par l'approche de la conscience intersubjective de Daniel Stern/The agressiveness of the criminal couples: the analysed massacre of Erba using the approach of the intersubjective conscience of Daniel Stern

    Directory of Open Access Journals (Sweden)

    Pasquale Caponnetto

    2013-12-01

    Full Text Available La coppia criminale è un fenomeno poco comune nell'ambito dei delitti in quanto la maggior parte dei criminali commette il crimine da solo o coinvolge altri individui solo per caso. Ciò nonostante, la letteratura rivela una serie di coppie criminali che hanno commesso diversi crimini, fino ad arrivare all’omicidio. Alcuni hanno ucciso per denaro, altri per odio, altri ancora per amore, per vendetta, per perversione. Bonnie e Clyde, Olindo e Rosa, Erika e Omar sono espressione di un viaggio nel fenomeno del “crimine di coppia” in cui manifestazioni di follia a due, al di là dell’infatuazione reciproca e della dipendenza psicologica, si svuotano di qualsiasi accezione romantica per concretizzarsi in qualcosa di spaventoso e incontenibile, capace di sfuggire ad ogni tipo di catalogazione e comprensione. Nel presente lavoro, in particolare, si andrà ad analizzare la coppia criminale degli autori della strage di Erba, che verrà esaminata nell’ottica della coscienza intersoggettiva di Stern. Le couple criminel est un phénomène rare puisque la majorité des crimes sont commis par des criminels seuls ou ce n’est que par hasard qu’ils impliquent d’autres personnes. Toutefois, la littérature parle d’une série de couples criminels qui ont commis des différents types de crimes (homicide inclus. Certains d’entre eux tuent pour de l’argent, certains autres à cause de la haine, de l’amour, de la revanche ou de la perversion. Bonnie et Clyde, Olindo et Rosa, Erika et Omar constituent des exemples du phénomène du « crime en couple ». Ce sont des situations de folie à deux qui n’ont aucune acception romantique et qui se traduisent en quelque chose d’horrifiant et d’incontrôlé. Dans cet article, les auteurs vont analyser le couple criminel composé par les responsables du massacre de Erba (Italie du Nord. L’objectif est d’examiner ce couple en utilisant l’approche de la conscience intersubjective de Daniel

  4. Identicars: uno strumento per migliorare la resa testimoniale nelle indagini per omissione di soccorso stradale/Le système Identicars : un outil pour améliorer la qualité du témoignage dans les enquêtes pour le délit de fuite à la suite d’un accident de la circulation/Identicars system: a tool for improving the quality of witness in the investigations on hit-and-run driving accidents

    Directory of Open Access Journals (Sweden)

    Griggi Manuela

    2017-04-01

    Full Text Available L’articolo descrive uno studio sperimentale volto a testare l’efficacia dello strumento Identicars, un catalogo di immagini di automobili e di parti di esse ideato per aiutare i testimoni di omissione di soccorso stradale nel compito di riconoscimento dell’auto fuggita senza prestare soccorso. L’ipotesi di partenza dei ricercatori è quella per cui tale strumento dovrebbe aiutare i testimoni a fornire una descrizione più dettagliata e più accurata dell’auto che si è data alla fuga. Nell’articolo verrà dimostrata la potenziale utilità dello strumento Identicars attraverso l’esposizione dei risultati di un esperimento condotto presso l’Alma Mater Studiorum Università di Bologna, i cui risultati mostrano un’accuratezza maggiore del resoconto testimoniale per i soggetti che hanno utilizzato Identicars rispetto ai soggetti che hanno fornito un resoconto testimoniale con il metodo tradizionale di assunzione delle informazioni. L’article décrit une étude pilote conçue pour vérifier l’efficacité du système Identicars. Cet outil est un catalogue d’images de voitures et de pièces de voiture créé pour aider les témoins de délits de fuite à reconnaître la voiture en question. L’hypothèse des chercheurs est que cet outil devrait effectivement aider les témoins à fournir des descriptions plus détaillées et précises. Les auteurs veulent démontrer l’utilité potentielle du système Identicars par le biais des résultats obtenus par une expérience réalisée à l’Université de Bologne (Italie. Ces résultats montrent une plus grande qualité du témoignage de la part des personnes qui ont employé l’outil Identicars par rapport à celles qui ont témoigné en employant les méthodes traditionnelles pour obtenir les informations. The article describes a pilot study designed to test the effectiveness of the Identicars system. This tool is a catalogue of images of cars and car parts created to help the

  5. Les usages de la flexibilité temporelle chez les enseignantes du secondaire The uses of flexible time by female secondary-school teachers

    Directory of Open Access Journals (Sweden)

    Julie Jarty

    2009-09-01

    Full Text Available De par sa flexibilité temporelle, il existe une perception largement répandue selon laquelle la profession enseignante serait woman-friendly, « bien pour une femme ». Le « plafond de verre » est pourtant une réalité pour de nombreuses femmes au sein de l’enseignement du second degré. Centré sur une étude des perceptions et des pratiques temporelles au sein de ce groupe professionnel dans une perspective de genre, cet article s’appuie sur une analyse critique des discours de 40 entretiens individuels réalisés auprès d’hommes et de femmes enseignant-e-s du secondaire et de leurs « carnets-temps ». Il s’agit d’explorer la manière dont ils et elles utilisent leur temps et cette flexibilité professionnelle. Le résultat de cette recherche permet de montrer que les expériences temporelles sexuées sont particulièrement prédominantes, ce qui contribue à expliquer les difficultés des femmes enseignantes à accéder aux positions les plus prestigieuses et les mieux rémunérées de la hiérarchie. Néanmoins, la mobilisation d’une typologie des expériences temporelles des enseignantes nous conduit à identifier l’existence de discours alternatifs, reconnaissant ainsi les contrastes du degré selon lequel les rapports sociaux de sexe sont reproduits, reconfigurés ou transformés au sein de la profession.Because of its temporal flexibility, there is a widespread notion that the teaching profession is ‘woman-friendly’ or “good for women”. However, there is extensive evidence that a ‘glass ceiling’ exists for female secondary school teachers too. Based on a study of temporal perceptions and practices within the teaching profession in a gendered perspective, this paper draws on the critical discourse analysis of forty individual interviews conducted with male and female secondary school teachers and of their schedules. The aim was to examine the use they make of their time and professional flexibility

  6. “Wit larded with malice” – Translating Shakespeare’s culinary language

    Directory of Open Access Journals (Sweden)

    Federica Scarpa

    2015-12-01

    pubblicazioni più recenti (Fitzpatrick 2007, 2011 sul linguaggio shakespeariano in riferimento al gusto, al cibo e alla sua cottura, nell’articolo vengono presentati alcuni esempi delle diverse traduzioni in italiano del linguaggio e della terminologia – storicamente distanti da noi e spesso culturalmente connotati – che veicolano il sapere culinario di Shakespeare, evidenziando le difficoltà incontrate dai traduttori per cercare di mantenere le immagini gastronomiche anche nella lingua di arrivo. Questa lingua altamente specializzata può infatti essere fatta rientrare in quel più ampio “linguaggio delle cose” del Bardo che è maggiormente a rischio di diventare arcaico e di diventare quindi un problema di traduzione per epoche e contesti culturali diversi. Gli esempi sono stati tratti soprattutto dalle fasi di due diverse operazioni culinarie: la preparazione e cottura del pane e dei dolci, e la preparazione e la cottura della carne. L’approccio del traduttore che viene considerato più adatto a tradurre i riferimenti al cibo nelle opere di Shakespeare è quello che si incentra sul lettore di arrivo. In sede di conclusione verrà fatto riferimento anche ad altri approcci al linguaggio shakespeariano che, pur essendo al di fuori dei confini dei Translation Studies, sono anch’essi incentrati sul destinatario in quanto finalizzati a rivitalizzare il teatro di Shakespeare per un pubblico contemporaneo.

  7. Composites organiques-inorganiques pour la substitution et la réparation osseuse : concepts, premiers résultats et potentialités Organic-inorganic composites for bone substitute and bone repair applications: concepts, first results and potentialities

    Directory of Open Access Journals (Sweden)

    Peroglio Marianna

    2013-11-01

    Full Text Available Ce document présente un très bref aperçu de l'intérêt des matériaux composites organique – inorganique pour la substitution et la réparation osseuse. Deux types de composites sont présentés. Dans une première partie, des matériaux poreux en céramique ou bio-verre élaborés par la technologie des poudres sont imprégnés par un polymère. Cette imprégnation se traduit par une forte augmentation de l'énergie à la rupture du squelette céramique, permettant de limiter le risque de rupture fragile. L'augmentation des propriétés mécaniques des substituts osseux céramiques par une phase polymère peut être mise en regard des mécanismes de renforcement présents dans l'os et du rôle du collagène sur la ténacité de celui-ci. Dans une deuxième partie, des composites denses sont élaborés par des technologies de plasturgie, qui permettent de réaliser des produits de formes complexes. Les phases polymères et céramiques sont ici choisies pour leurs caractères respectifs résorbable et ostéo-inducteur. Ces composites permettent la création rapide d'hydroxyapatite à leur surface et accélèrent la guérison osseuse. A terme, ils sont résorbés. Ces deux exemples démontrent les potentialités de tels multi-matériaux architecturés pour la réalisation de substituts osseux plus résistants mécaniquement et apportant de nouvelles fonctionnalités, ainsi que pour la production de produits d'ostéosynthèse favorisant les processus de guérison osseuse. Here we show a brief outline of organic-inorganic composites for bone substitute and bone repair applications. Two types of composites are presented. In a first strategy, porous ceramics and bioactive glasses processed by sintering methods are impregnated by a polymer. The strong improvement of the mechanical properties of the ceramic scaffolds by a polymer phase can be linked to the one present in bone with the role of collagen on bone toughness. In a second strategy, a

  8. Disordered porous solids : from chord distributions to small angle scattering

    Science.gov (United States)

    Levitz, P.; Tchoubar, D.

    1992-06-01

    proposée par Mering et Tchoubar (MT). Mettant à profit la possibilité actuelle d'une comparaison quantitative entre les techniques d'imagerie et la diffusion aux petits angles, ce papier tente de compléter et d'étendre l'approche MT. Dans un premier temps, nous montrons en quoi la connaissance de ces distributions de cordes permet de distinguer certains types de désordres structuraux. Une relation explicite entre le spectre de diffusion aux petits angles et les distributions de cordes est alors proposée. Dans une troisième partie, l'application à différents types de désordre est discutée et les prédictions du modèle comparées aux résultats expérimentaux disponibles. Par utilisation du traitement d'images, nous nous intéressons à trois types de désordre : le milieu aléatoire de Debye, pour ses propriétés à grandes distances, le désordre “ corrélé " avec une attention particulière pour le cas d'un verre poreux (le Vycor) et enfin des organisations complexes où des propriétés d'invariance d'échelle de longueur peuvent être observées.

  9. Competition entre supraconductivite et magnetisme au voisinage de la transition de Mott dans le conducteur organique quasi-bidimensionnel k-(BEDT-TTF)2copper[N(CN)2]bromine

    Science.gov (United States)

    Fournier, David

    variation judicieuse du cycle thermique s'est averee etre equivalente a une modification de la pression chimique. Cette derniere est modifiee par l'intermediaire d'une relaxation structurale autour de 85 K appelee la transition de verre d'ethylenes. Cela nous a permis de suivre l'evolution de cette coexistence en s'approchant de la transition de premier ordre, et ainsi de statuer sur la competition entre la supraconductivite et le magnetisme ainsi que sur l'existence d'une separation de phase d'ordre macroscopique. De plus, nous avons observe une anisotropie similaire sur les mesures de vitesse ultrasonore entre le regime de pseudogap et la supraconductivite. Ce resultat tend a confirmer l'existence d'une physique commune entre le regime de pseudogap et l'etat supraconducteur. Le regime de pseudogap, encore meconnu a ce jour, est probablement relie a des fluctuations antiferromagnetiques, dont l'origine pourrait etre un emboitement de la surface de Fermi quasi-unidimensionnelle de ce compose, ou bien relie a la proximite de la physique de Mott. Enfin, l'analyse de la symetrie du parametre d'ordre supraconducteur, qui est probablement de type s+d, tend a demontrer que les processus de couplage interplan sont d'une importance cruciale. L'approche theorique de Hubbard purement 2D dans le plan conducteur semble donc insuffisante pour la recherche du mecanisme d'appariement.

  10. Effet de la substitution du cuivre par du lithium sur les proprietes de l'oxyde spinelle lithium(x)cuivre(y-x)cobalt(3-y)oxygen(4) etudie pour l'electrocatalyse de la reaction de degagement de l'oxygene en milieu alcalin

    Science.gov (United States)

    Fatih, Khalid

    de nickel avec une tendance a l'agglomeration lorsque le taux de Li est accru. Les micrographies AFM revelent une micro-porosite de ces particules d'oxyde. Les films minces deposes sur un substrat de verre ont montre une conductivite tres interessante de l'ordre de 103O-1 cm-1 pour LixCuy-x Co3-yO4 comparee a 2,8 O-1 cm-1 pour Co3O4. La spectroscopie d'impedance a permis de distinguer les processus de la surface interne des films d'oxydes de ceux de l'interface electrode/electrolyte. Les courbes Mott-Schottky (1/C2 en fonction du potentiel) montrent que les films d'oxyde se comportent comme des semi-conducteurs de type p tres dopes (degeneres). Le potentiel de bandes plates et la densite des porteurs de charge majoritaires des oxydes LixCuy-xCo3-yO4 sont de l'ordre de 0,48 a 0,52 V et 1019 a 10 20 cm-3 respectivement. Pour Co 3O4 ces parametres sont de 0,47 V et ≈10 18 cm-3. (Abstract shortened by UMI.)

  11. L’exposition contrôlée à la lumière et à l’obscurité ajuste le rythme du cortisol salivaire chez les travailleurs de nuit

    Directory of Open Access Journals (Sweden)

    Anny Casademont

    2005-05-01

    Full Text Available Dans cette étude réalisée sur le terrain et en laboratoire, nous avons testé l’efficacité d’une intervention consistant à contrôler l’exposition à la lumière/obscurité de façon à favoriser l’adaptation circadienne au travail de nuit. Six travailleurs permanents de nuit (moyenne d’âge 37,1 ± σ : 8,1 ans avaient comme consigne de s’exposer de façon intermittente à une lumière blanche vive plein spectre (~2 000 lux au cours des 6 premières heures de leur quart de travail de 8 heures. Il leur était demandé de se protéger de la lumière solaire du matin avec des verres teintés (densité gris neutre, transmission visuelle de la lumière 15 % et de maintenir des épisodes réguliers de sommeil/obscurité dans une pièce très sombre. Ces épisodes devaient commencer 2 heures après la fin de chaque quart de travail de nuit. Cinq travailleurs du groupe contrôle (41,1 ± σ : 9,9 ans ont été étudiés alors qu’ils devaient uniquement maintenir un horaire régulier de sommeil/obscurité. Des procédures de routine constante, réalisées avant et après une série d’environ 12 quarts de travail de nuit s’échelonnant sur 3 semaines, ont montré chez les travailleurs du groupe traitement une variation significative dans l’heure d’apparition du pic de cortisol ainsi qu’un ajustement de ce rythme à un horaire de travail de nuit. Un plus petit changement de phase a été observé dans le groupe contrôle, ce qui suggère une adaptation partielle à l’horaire de travail de nuit. Nos résultats démontrent l’efficacité d’une exposition judicieuse à la lumière et à l’obscurité pour favoriser l’adaptation des rythmes physiologiques au travail de nuit.The efficacy of a light/darkness intervention designed to promote circadian adaptation to night shift work was tested in this combined field and laboratory study. Six permanent night shift workers (mean age: 37.1 / s: 8.1 years were instructed to

  12. Applications of electron spin resonance to some problems of radiation chemistry; Applications de la resonance paramagnetique electronique a quelques problemes de chimie sous rayonnements

    Energy Technology Data Exchange (ETDEWEB)

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

    1968-06-01

    The electron spin resonance (E.S.R.) spectra of gamma irradiated polar organic glasses, at 77 K, shows a single line centered at g {approx} 2, attributed to solvated electrons. The radicals produced on scavenging this species by electron acceptors, such as aromatic hydrocarbons, nitro-compounds and azines have been studied by E.S.R. In most cases, the radicals from these solutes, the spectra of which are observed after elimination by warming of the radicals from the matrices, are produced by protonation of the anions formed by scavenging of electrons at 77 K. Thus, in the case of glassy solutions of nitro-compounds, the radicals R NO{sub 2}H are formed. They are characterized by a{sub N} = 15 G (nitrobenzene) or a{sub N} = 28 G (nitro-alkane). These radicals are also generated by U.V, photolysis at room temperature of solutions of nitro-compounds in alcohols and are shown to be the precursors of nitroxide radicals R - N - R (with N - O) observed simultaneously. Gamma irradiation of solutions of pyridine and of the three diazines, in alcohol glasses at 77 K, produces the radical formed by hydrogen addition to these compounds. The value of the coupling constant of the additional proton (7-10 G) indicates that it is bound to a nitrogen in the sp{sup 2} hydridation state. One has shown, taking pyridine as an example, that the addition to a carbon gives a much greater value of the coupling constant, of the order of 50-60 G. (author) [French] Les spectres de resonance paramagnetique electronique (R.P.E.) obtenus apres irradiation gamma, a 77 K, de verres organiques polaires tels que les alcools, comportent une bande unique centree a g {approx} 2, attribuable aux electrons solvates. On etudie par R.P.E. les radicaux provenant de leur capture par des solutes ayant une affinite electronique, en particulier les hydrocarbures aromatiques, les composes nitres et les azines. En general, les radicaux provenant de ces solutes, dont on observe les spectres apres elimination

  13. Thermal and hydrodynamic study of a whirling liquid hydrogen layer under high heat flux; Etude thermique et hydrodynamique d'une couche tourbillonnaire d'hydrogenen liquide sous flux de chaleur eleve

    Energy Technology Data Exchange (ETDEWEB)

    Ewald, R. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1968-03-01

    In order to achieve a cold neutrons source ({lambda} {>=} 4.10{sup -10} m) in a high flux reactor ({approx} 10{sup 15} neutrons/cm{sup 2}.s), a whirling liquid hydrogen layer (145 mm OD, effective thickness 15 mm, height about 180 mm) was formed, out-of-pile, in a cylindrical transparent glass vessel. The whirling motion was obtained by tangential injection of the liquid, near the wall. Thermal and hydrodynamical conditions of formation and laws of similarity of such a layer were studied. The characteristics of this whirling flow were observed as a function of mass flow rate (5 to 27 g/s; 4.3 to 23 l/mn), and of spillway width (18 and 25 mm). Six different nozzles were used : 1.0; 1.5; 1.9; 2.25; 2.65 and 3.0 mm ID. The total heat influx was found between 8.6 and 10.4 kW. The heat flux density was about 9.4 W/cm{sup 2} and the mean layer density around 80 per cent of that of the liquid hydrogen at 20.4 Kelvin. High speed movies were used to analyze the boiling regime. (author) [French] En vue de realiser une source de neutrons froids ({lambda} {>=} 4.10{sup -10} m) dans un reacteur a haut flux ({approx} 10{sup 15} neutrons thermiques/cm{sup 2}.s), on a forme dans un vase cylindrique transparent en verre, hors-pile, une couche tourbillonnaire ('vortex') d'hydrogene liquide (diametre exterieur 145 mm, epaisseur effective 15 mm, hauteur 180 mm environ). Le mouvement giratoire est obtenu par injection tangentielle du liquide pres de la paroi. L'etude porte sur la determination des conditions thermiques et hydrodynamiques de la formation d'une telle couche et sur les regles de similitude de ce phenomene. On a observe les caracteristiques de l'ecoulement giratoire en fonction du debit (de 5 a 27 g/s, soit de 4.3 a 23 1/mn), de la vitesse d'injection (entre 10 et 110 m/s) et de la largeur du deversoir (18 et 25 mm), ceci pour six diametres differents d'injecteur (1.0 ; 1.5; 1.9; 2.25; 2.65 et 3.0 mm). Le flux de chaleur total mesure

  14. Proposta di uno studio multicentrico per la valutazione del fenomeno delle infezioni correlate a pratiche assistenziali in residenze socioassistenziali in Italia

    Directory of Open Access Journals (Sweden)

    S. Brusaferro

    2003-05-01

    Full Text Available

    Razionale dello studio proposto In contesti come le Residenze Sanitarie Assistenziali (RSA, le Residenze Protette (RP, l’Assistenza Domiciliare Integrata (ADI la letteratura e le prime esperirne italiane evidenziano come il problema ICPA sia importante e, pur variando le tipologie di infezione prevalenti, i costi individuali, sociali ed economici ad esse collegati rimangono molto elevati.

    In questo scenario diventa importante che i Comitati per il Controllo delle Infezioni Ospedaliere (CIO aziendali affrontino il problema del controllo delle infezioni in ambito extraospedaliero e comincino a strutturare modelli organizzativi in grado di operare efficacemente. Il dimensionamento del problema, ovvero l’attività di sorveglianza epidemiologica, anche in questo caso è tra le prime attività necessarie di provata efficacia.

    Obiettivo dello studio: una prima valutazione della dimensione del problema ICPA nelle strutture RSA presenti nelle diverse regioni italiane attraverso uno studio di prevalenza nazionale. Materiali e metodi: l progetto prevede una prima fase con l’individuazione dei centri partecipanti e dei rispettivi referenti medici ed infermieristici. Successivamente si procederà, utilizzando la metodologia già testata in uno studio pilota, alla formazione del personale sull’uso degli strumenti. Saranno arruolati tutti i pazienti degenti da oltre 48 ore nelle RSA partecipanti, escludendo quelli in dimissione o in trasferimento nel giorno di rilevazione. I rilevatori, esterni alla struttura, raccoglieranno i dati consultando il quaderno infermieristico, il quaderno terapia, il diario clinico, la cartella clinica ed esaminando ciascun paziente per validare la eventuale presenza di “devices” e confermare sintomi e segni rientranti nelle definizioni di caso. Laddove necessario verrà consultato il personale medico ed infermieristico della struttura. Le variabili raccolte saranno centrate su dati

  15. Study of the {rho}-bar, {beta}-bar and {lambda} parameters of a light-water reactor; Etude des parametres {rho}-bar, {beta}-bar et {lambda} d'une pile a eau legere

    Energy Technology Data Exchange (ETDEWEB)

    Riche, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1965-09-01

    temps, font apparaitre la valeur effective {beta}-bar. A partir de la cinetique, nous determinons le rapport b par analyse de transitoire de puissance consecutif a l'injection d'une variation rapide de reactivite realisee par l'implosion d'une boule de verre vide. Un depouillement relativement simple est propose. L'appareillage est reduit et se transforme aisement en reactimetre. De la theorie de la perturbation, nous deduisons une mesure de {beta}-bar, qui consiste a ponderer les effets en reactivite d'une feuille de cuivre, mesures en differents emplacements du coeur. Les valeurs calculees de l'efficacite des neutrons retardes {gamma} = {beta}-bar/{beta} 1.23 et du temps de generation des neutrons prompts {lambda} = 59 {mu}s sont en bon accord avec les resultats experimentaux: {beta}-bar = 795 pcm et {beta}-bar/{lambda} 129 s{sup -1}, les nombres precites etant relatifs a un reacteur a eau legere et a uranium enrichi (90 pour cent U-235), le coeur presentant des trous d'eau. (auteur)

  16. Granulometric study of plutonium oxide particles in suspension in the atmosphere of a furnace enclosure during the preparation of U-Pu alloys; Etude granulometrique des particules d'oxyde de plutonium en suspension dans l'atmosphere d'une enceinte de fonderie pendant la fabrication d'alliages U-PU

    Energy Technology Data Exchange (ETDEWEB)

    Bataller, G; Lenkauer, S [Commissariat a l' Energie Atomique, Cadarache (France). Centre d' Etudes Nucleaires

    1964-07-01

    Since the extent of an internal contamination by respiration depends on the diameter of the radioactive particles in the atmosphere, a particle size study has been made of the particles present in the air of a working enclosure at the Plutonium Fuel Element Production Section during the preparation of Uranium Plutonium alloy bars. The air of this vessel is drawn through a glass fibre filter on which the dust is deposited. On these filters the radioactive particles are localized first of all by the luminous spots which they produce on a photographic plate when a scintillator is interposed (silver-activated zinc sulphide). An autoradiographic method then makes it possible to distinguish between, and to measure the particles of the oxides of uranium 235, uranium 238 and plutonium 239. On carrying out a microscopic scanning of the relevant parts of the filter, particles are seen surrounded by radial marks the length of which indicates the nature of the grains, and the number of which makes it possible to calculate the theoretical diameter of the radioactive grain. This latter can be compared with the diameter observed with the microscope. Thus for each category of particles it is possible to define a mean diameter and therefore to predict the path of the various inhaled particles in the human body. These results are compared with the very few weakly positive biological samples taken from the personnel working in this enclosure. (authors) [French] L'importance d'une contamination interne par inhalation etant fonction du diametre des particules radioactives en suspension dans l'atmosphere, une etude granulometrique a ete effectuee sur les poussieres existant dans l'air d'une enceinte de travail a la Section de Fabrication des Elements Combustibles au Plutonium pendant une fabrication de barreaux d'alliage Uranium Plutonium, L'air de ce caisson est aspire a travers un filtre en fibre de verre sur lequel restent fixees les poussieres. Sur ces filtres, les particules

  17. Extrusion and drawing of zircaloy 2. Production of pressure tubes for EL-4; Filage et etirage du zircaloy 2. Realisation des tubes de force pour EL-4

    Energy Technology Data Exchange (ETDEWEB)

    Thevenet, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Buffet, J [Cefilac (France)

    1964-07-01

    difficultes rencontrees du fait de cet alliage: - protection contre l'atmosphere - calage sur les outillages - mauvaise conductibilite thermique - economie de metal (prix) - les facteurs influencant la qualite des produits files - filage sous gaine cuivre et sous verre lubrifiant - structure a grains fins - homogeneite de temperature - temperature de travail Le cycle de transformation 'lingot de 550 kg - ebauches pour etirage des tubes EL-4 (112 x 120 L 12 m)' est decrit en detail (filage ou forgeage du lingot de {phi} 340 en billettes de {phi} 220, tronconnage puis percage a chaud a {phi} 125, mise sous gaine cuivre et filage en ebauche). Etirage: Les principales difficultes proviennent du grippage sur les outils et de la necessite de proteger l'alliage contre l'atmosphere pendant les recuits. L'etirage sur mandrin court, sur mandrin long, le laminage sur machine a reduire et l'execution des recuits sont decrits succintement ainsi que la fabrication par etirage sur mandrins longs de tubes EL-4 ({phi} = 107 x 113 L 4,30 m) a partir d'ebauche 112 x 120. Conclusions: On peut realiser par filage et etirage des tubes de zircaloy 2 semblables a ce qu'on obtiendrait couramment avec de l'inox. (auteurs)

  18. La vocazione territoriale tra approccio sistemico e situazionista: analisi di una collaborazione culture driven tra aziende del made in Italy attraverso il caso del Contratto di Rete Polo Alta Moda Area Vestina / The territorial vocation between the “systemic” approach and the “situationist” approach: analysis of a culture-driven collaboration between Made-in-Italy firms. The case of the network contract of “Polo Alta Moda Area Vestina

    Directory of Open Access Journals (Sweden)

    Elena Cedrola

    2014-06-01

    Full Text Available Il presente lavoro si propone di mostrare come una collaborazione culture driven tra aziende del made in Italy possa innescare un processo virtuoso capace di alimentare la competitività d’impresa. Nello specifico, intende verificare la validità di una nuova chiave di lettura dei processi di governance del territorio, detta situazionista, che affianca la concezione prevalente in letteratura, definita unitaria o sistemica. Il punto di discrepanza principale tra le due visioni sembra essere quello della vocazione territoriale. Pur riconoscendo entrambe la presenza di interessi condivisi tra gli attori, la visione situazionista non riconosce alla vocazione la funzione “razionalizzante” riscontrabile nell’approccio sistemico. A seguito di una sintetica review della letteratura sui temi del territorio come cultura condivisa, sulla dimensione reticolare territoriale ed extraterritoriale e sul contratto di rete, verrà introdotto lo studio di un contratto di rete stipulato l’8 giugno 2010 tra le aziende che costituiscono il Polo Alta Moda Area Vestina. Attraverso le evidenze emerse da alcune interviste in profondità, sarà indagato il ruolo dell’azienda Brioni nella duplice veste di key player del territorio e di impresa capofila del contratto di rete analizzato e saranno esaminati gli altri attori che compongono il Polo Alta Moda. Le interviste realizzate hanno coinvolto i manager dell’impresa capofila del contratto di rete, il vice presidente Confindustria Pescara e presidente della Sezione Unificata Sistema Moda Chieti Pescara e il direttore delle fondazioni partecipanti al contratto.   This case study aims to validate how a culture-driven collaboration between firms could trigger the competitiveness of a Country, starting from a specific territorial culture. Specifically, it intends to investigate the validity of a new interpretation of the territorial governance processes, named “situationist”, that supports the prevailing

  19. Determinismo, analogia e preveggenza in Pierre Mabille. Basi per un raffronto con Juan Larrea

    Directory of Open Access Journals (Sweden)

    A. D’Urso

    2012-08-01

    col materialismo dialettico, in particolare mostrando quei passaggi del testo che sembrano rimandare ad alcune opere (anche minori di Marx ed Engels, piuttosto che indugiare sulla ricostruzione bio-bibliografica e approfondire l’influenza del monismo materialista, dell’ermetismo alchemico e della massoneria rivoluzionaria sulla costruzione “stilistica” stessa di questo breve saggio di Mabille.Intorno alle tematiche del determinismo, dell’analogia e della preveggenza verrà quindi messa in risalto l’originale rilettura di tesi fondamentali della dialettica hegeliana e del materialismo marxista, nella loro pos¬sibile sintesi coi principi del monismo cosmico. Interpretazione che consente di affrontare tali questioni dall’interno di un punto di vista pienamente surrealista, piuttosto che dall’esterno (e un po’ più metafisica¬mente come pretendeva Juan Larrea, così permettendo di gettare le basi per un possibile confronto tra quest’ultimo e l’amico Mabille, i quali non hanno mancato di influenzarsi a vicenda.Parole chiave: monismo; surrealismo; materialismo; Engels; marxismo.

  20. Thermal and hydrodynamic study of a whirling liquid hydrogen layer under high heat flux; Etude thermique et hydrodynamique d'une couche tourbillonnaire d'hydrogenen liquide sous flux de chaleur eleve

    Energy Technology Data Exchange (ETDEWEB)

    Ewald, R [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1968-03-01

    In order to achieve a cold neutrons source ({lambda} {>=} 4.10{sup -10} m) in a high flux reactor ({approx} 10{sup 15} neutrons/cm{sup 2}.s), a whirling liquid hydrogen layer (145 mm OD, effective thickness 15 mm, height about 180 mm) was formed, out-of-pile, in a cylindrical transparent glass vessel. The whirling motion was obtained by tangential injection of the liquid, near the wall. Thermal and hydrodynamical conditions of formation and laws of similarity of such a layer were studied. The characteristics of this whirling flow were observed as a function of mass flow rate (5 to 27 g/s; 4.3 to 23 l/mn), and of spillway width (18 and 25 mm). Six different nozzles were used : 1.0; 1.5; 1.9; 2.25; 2.65 and 3.0 mm ID. The total heat influx was found between 8.6 and 10.4 kW. The heat flux density was about 9.4 W/cm{sup 2} and the mean layer density around 80 per cent of that of the liquid hydrogen at 20.4 Kelvin. High speed movies were used to analyze the boiling regime. (author) [French] En vue de realiser une source de neutrons froids ({lambda} {>=} 4.10{sup -10} m) dans un reacteur a haut flux ({approx} 10{sup 15} neutrons thermiques/cm{sup 2}.s), on a forme dans un vase cylindrique transparent en verre, hors-pile, une couche tourbillonnaire ('vortex') d'hydrogene liquide (diametre exterieur 145 mm, epaisseur effective 15 mm, hauteur 180 mm environ). Le mouvement giratoire est obtenu par injection tangentielle du liquide pres de la paroi. L'etude porte sur la determination des conditions thermiques et hydrodynamiques de la formation d'une telle couche et sur les regles de similitude de ce phenomene. On a observe les caracteristiques de l'ecoulement giratoire en fonction du debit (de 5 a 27 g/s, soit de 4.3 a 23 1/mn), de la vitesse d'injection (entre 10 et 110 m/s) et de la largeur du deversoir (18 et 25 mm), ceci pour six diametres differents d'injecteur (1.0 ; 1.5; 1.9; 2.25; 2.65 et 3.0 mm). Le flux de chaleur total mesure est compris entre 8.6 et 10.4 kW et la

  1. Micro-striction 1 and 2 (1961); Microstriction 1 and 2 (1961)

    Energy Technology Data Exchange (ETDEWEB)

    Alddieres, M; Aymar, R; Jourdan, P; Samain, A [Association Euratom-CEA Cadarache, 13 - Saint-Paul-lez-Durance (France)

    1961-07-01

    A certain quantity of gas is enclosed between two co-axial glass tubes (diameters 67 and 87 mm). In this annular space thus formed exists a permanent magnetic configuration, whose lines of force are perpendicular to the surface of the tubes (0-500 gauss). An electric field is then produced by induction such that its lines of force are circles whose axis coincides with that of the tubes (200 V/cm). The electric field lasts for 0.5 {mu}s. This field ionises the gas and causes an electric current to flow perpendicularly to the magnetic field. The corresponding Laplacian force accelerates the plasma along the axis of the tubes. In a first series of measurements, the discharge characteristics in the absence of a permanent field were studied. It is, in particular, convenient to group together all the irreversible phenomena which occur by assuming the existence of an electrical discharge resistance. The plasma movement in the permanent magnetic field induces in this latter a back-e.m.f. By taking into account the discharge resistance, the electric current and the forces tending to accelerate the plasma can be evaluated. The efficiency of the acceleration process has been measured. It passes through a maximum for a certain value of the permanent magnetic field. The experimental results have been compared with the simple model described above. (authors) [French] Une certaines quantite de gaz est enfermee entre deux tubes en verre de meme axe (diametres 6V et 87 mm). L'espace annulaire ainsi defini est le siege d'une configuration magnetique permanente, dont les lignes de force sont perpendiculaires a la surface des tubes (0-500 gauss). On fait apparaitre par induction un champ electrique dont les lignes de force sont des cercles dont l'axe coincide avec l'axe des tubes (200 V/cm). Ce champ electrique persiste pendant 0,5 {mu}s. Ce champ electrique ionise le gaz et fait circuler un courant electrique perpendiculaire au champ magnetique. La force de Laplace correspondante

  2. MONA, LISA and VINCI Soon Ready to Travel to Paranal

    Science.gov (United States)

    2000-11-01

    Spatiale (DESPA) of the Paris Observatory. It was used in 1991 at the Kitt Peak National Observatory (Arizona, USA), for the first (coherent) combination of the light beams from two independent telescopes by means of optical fibers of fluoride glass. It has since been in operation for five years as a focal instrument at the IOTA Interferometer (Mount Hopkins, Arizona, USA) within a collaboration with the Harvard Smithsonian Center for Astrophysics), producing a rich harvest of scientific data. The VINCI partners The VINCI instrument is constructed in a collaboration between ESO (that also finances it) and the following laboratories and institutes: * DESPA (Paris Observatory) provides the expertise, the general concept, the development and integration of the optomechanics (with the exception of the camera) and the electronics, * Observatoire Midi-Pyrénées that produces the control software * The LISA infrared camera is developed by the Max-Planck-Institut für Extraterrestrische Physik (Garching, Germany), and * ESO provides the IR camera electronics and the overall observational software and is also responsible for the final integration. DESPA delivered VINCI to ESO in Garching on September 27, 2000, and is now assembling the instrument in the ESO optical workshop. It will stay here during three months, until it has been fully integrated and thoroughly tested. It will then be shipped to Paranal at the beginning of next year. After set-up and further tests, the first observations on the sky are expected in late March 2001. Fluoride fibers guide the light The heart of VINCI - named MONA - is a fiber optics beam combine unit. It is the outcome of a fertile, 10-year research partnership between Science (DESPA) and Industry ("Le Verre Fluoré" [2]). Optical fibers will be used to combine the light from two telescopes inside VINCI . Since the instrument will be working in the near-infrared region of the spectrum (wavelength 2-2.5 µm), it is necessary to use optical fibers

  3. From dust to varnish: Geochemical constraints on rock varnish formation in the Negev Desert, Israel

    Science.gov (United States)

    Goldsmith, Yonaton; Stein, Mordechai; Enzel, Yehouda

    2014-02-01

    Chemical compositions of rock varnish from the Negev Desert of Israel and local settled dust were used to constrain the mechanisms of varnish formation and patterns of Mn enrichment and accumulation in the varnish. Rock varnish was sampled from coeval, undisturbed prehistoric flint artifacts along a south-north climatic transect (˜30-120 mm/yr of rain). Our analyses indicate that Mn, Ba and Pb in the varnish are significantly enriched (˜100×) in respect to the local settling dust and that Mn content systematically fluctuates with depth in the varnish. The varnish and settled dust data combined with basic thermodynamic and kinetic reasoning are used to constrain the following geochemical model of rock varnish formation: dust accumulates in micro-basins on exposed rock surfaces, under pH ˜8 (common Negev value) and during wetting by dew and rain, Mn in the dust is mobilized and leached to a depth of ˜5 μm under the varnish surface where Hollandite Mn-oxides precipitate and are adsorbed onto and between the porous clay minerals that comprise most of the varnish. During its mobile phase Mn-oxide is negatively charged and adsorbs rare earth elements. Once the solution dries abrasion removes the upper, weakly cemented dust sediment, which contains mainly Si, Al and Fe (which are not mobile at pH ˜8). Ca is also removed in large quantities. Mn, Ba, Pb and the REE are deposited at a depth and thus, protected from erosion. Reoccurrences of these processes result in a noticeable accumulation of these elements, but not of Si, Al or Fe. The alternating Mn-rich and Mn-poor laminas form as a result of a competition between the leaching rate of Mn and the adhesion rate of the clay minerals. When moisture is high (low), lamina with high (low) Mn/clay mineral ratio forms. The oxidation states involved in the varnish formation are unknown, therefore, to use Morgan's calculations we must assume, in agreement with the thermodynamic considerations (presented above), that during

  4. Distribution of Aerially Applied Malathion-S{sup 35} in a Forest Ecosystem; Distribution du malathion- {sup 35}S pulverise par avion dans un ensemble ecologique forestier; Raspredelenie malationa, mechennogo S35 i raspylyaemogo s vozdukha dlya izucheniya ehkologicheskoj sistemy lesnykh massivov; Distribucion en un sistema ecologico forestal de malation- 35S pulverizado desde el aire

    Energy Technology Data Exchange (ETDEWEB)

    Giles, Jr., R. H.; Peterle, T. J. [Ohio Co-Operative Wildlife Research Unit, Columbus, OH (United States)

    1963-09-15

    xylene, du triton X-155 comme emulsifiant et de l'eau. Le malathion avait ete marque avec {sup 35}S par le Radiochemical Centre d'Amersham (Royaume-Uni). On a pulverise par avion une quantite correspondant a une activite de 1 c dans l'un des deux secteurs forestiers de huit hectares, les 15 et 25 mai 1962. L'activite specifique du malathion marque etait de 17,5 m c/m M. On a mesure la distribution des composants de la pulverisation aerienne dans la foret. Des echantillonneurs d'air electriques ont permis d'estimer les quantites emportees hors du secteur d'experience; des ballons d'helium portant des disques de verre depoli ont permis de mesurer la quantite en suspension au-dessus de la frondaison; des disques de verre suspendus verticalement et des echantillons d'ecorces ont permis de mesurer les quantites a diverses hauteurs de la frondaison; des disques de verre et du papier pour analyse a la touche ont permis, non seulement de mesurer la distribution horizontale, mais aussi, de controler un appareil courant de detection de la distribution des produits pulverises. Des echantillons du sol et des pieux marques ont permis d'etudier la distribution au-dessous de la surface. Des echantillons d'eau provenant de cours d'eau intermittents,'des insectes, des mammiferes, des reptiles et des oiseaux ont indique la distribution initiale et ulterieure de l'insecticide et de ses metabolites dans l'ensemble ecologique. Des etudes de la faune ont continue pendant les etes 1961 et 1962 et certaines observations seront encore faites au cours de l'ete 1963. Les resultats preliminaires indiquent que les populations d'insectes sont revenues a la normale au bout d'environ trois semaines et qu'il n'y a pas eu d'effets decelables sur la densite des vertebres dans la surface traitee. (author) [Spanish] Durante el verano de 1962 se estudio la distribucion del malation (0,0-dimetil ditiofosfato del mercaprosuccinato de dietilo) en una zona forestal de la region centro-oriental de Ohio (Estados

  5. Present Status of Nitrogen Fixation by Reactor Radiation; Etat Actuel des Recherches sur l'oxydation directe de l'azote sous irradiation dans des reacteurs; Sovremennoe sostoyani opytov po okisleniyu azota izlucheniem iz reaktorov; Estado actual de las investigaciones sobre fijacion del nitrogeno por irradiacion en reactores

    Energy Technology Data Exchange (ETDEWEB)

    Harteck, P; Dondes, S [Rensselaer Polytechnic Institute, Troy, NY (United States)

    1960-07-15

    'oxydation directe de l'azote sous irradiation, entreprises depuis plusieurs annees par le Rensselaer Polytechnic Institute et le Brookhaven National Laboratory, utilisent directement les particules de recul de fission comme rayonnements ionisants, au moyen de la dispersion d'uranium-235 dans des fibres de verre de cinq microns de diametre environ. Les auteurs ont determine les effets de la temperature, de la pression et du rapport azote/oxygene sur la valeur de G pour l'oxydation de l'azote et ont publie le compte rendu de leurs travaux. Ils en donnent un bref apercu. Les recherches en question ont ete effectuees avec des systemes statiques; plus recemment des systemes statiques et des systemes a circulation ont ete utilises a la fois. Avec les systemes statiques, les auteurs se sont surtout attaches a etudier l'effet de l'intensite des rayonnements, notamment sur la cinetique d'equilibre sous irradiation. Ils ont constate que dans des melanges ou le rapport azote/oxygene est de 4 a 1 et de 2 a 1 N0{sub 2} et N{sub 2}0 se forment jusqu'a epuisement de tout l'oxygene present. Un systeme a circulation continue (cycling) fonctionne maintenant dans une boucle a l'interieur du reacteur de Brookhaven. Les auteurs fournissent sur les effets de la temperature, de la pression, du rapport azote/oxygene et de l'intensite des rayonnements des donnees que l'on pourra utiliser pour etablir un projet de reacteur de chimie nucleaire. Le systeme actuel fonctionne sous 10 atmospheres et a 150{sup o}C. La temperature est fonction de l'energie de fission liberee dans les fibres de verre et de la resistance thermique du circuit. Une autre boucle, qui doit fonctionner sous 50 - 75 atmospheres et a 600{sup o} C, est en construction. Il est possible, grace a ces boucles, d'etudier les caracteristiques d'un systeme continu, y compris le comportement des produits de fission liberes dans le courant, gazeux. Les auteurs distinguent trois stades dans la cinetique complexe de l'oxydation de l'azote: reactions

  6. On the Behaviour of Radioisotopes Incorporated in Glass Blocks; Le Comportement des Radioisotopes Vitrifies; O Povedenii Radioaktivnyh Izotopov, Lokalizovannyh v Steklovidnyh Blokah; Comportamiento de los Radioisotopos Vitrificados

    Energy Technology Data Exchange (ETDEWEB)

    Zimakov, P. V.; Kulichenko, V. V.; Duhovich, F. S.; Salamatmn, B. A.

    1963-02-15

    carefully selected so as to ensure that the radioisotopes remain securely fixed in the buried blocks. In this connection, titanium compounds are especially interesting as fluxes. (author) [French] Etant donne la longue periode de certains radio- isotopes, il est necessaire de les contenir pendant un temps prolonge, en evitant toute fuite; il faut donc etudier leur comportement dans des blocs de verre lors d'une conservation de longue duree: auto-echauffement, irradiation reciproque, influence du milieu ambiant. Si l'on cherche a limiter la dimension des blocs aux fins d'enfouissement, et a reduire la volatilite des radioisotopes en cours de preparation (temperature maximum: 1200'C), on obtient des blocs de structure peu homogene. Ceux-ci se composent d'ailleurs non pas de verre veritable, mais de melanges 'vitreux'. Les proprietes de ces blocs, notamment leur aptitude a fixer d'une facon durable les produits de fission radioactifs, dependent dans une large mesure de leur composition chimique (quantite et nature des fondants), ainsi que des conditions de leur preparation et de leur conservation ulterieure. La chaleur degagee par les blocs fortement radioactifs, dans l'entrepOt souterrain, donne lieu a des modifications chimiques et physiques de leur structure et influe fortement sur la duree de la fixation des produits de fission, notamment pres de la surface des blocs. Le risque de lixiviation s'accroit, en regle generale, loisque la temperature depasse 400UC. Il est donc souhaitable d'eviter la formation de temperatures trop elevees dans les entrepots. D'aune part, la forte densite des rayonnements emis par les blocs influe sensiblement sur la transformation de la structure des blocs et, de ce fait, sur la duree de la fixation des produits de fission qui s'y trouvent. D'ailleurs, ces transformations se produisent avant tout a partir de la surface, au contact du milieu exterieur (air, eau). D'une maniere generale, le risque de lixiviation va croissant. Les experiences ont

  7. Nucléation, ascension et éclatement d'une bulle de champagne

    Science.gov (United States)

    Liger-Belair, G.

    2006-03-01

    People have long been fascinated by bubbles and foams dynamics, and since the pioneering work of Leonardo da Vinci in the early 16th century, this subject has generated a huge bibliography. However, only quite recently, much interest was devoted to bubbles in Champagne wines and carbonated beverages. Since the time of the benedictine monk dom Pierre Perignon (1638-1715), champagne is the wine of celebration. This fame is largely linked to the elegance of its effervescence and foaming properties. In this book, the latest results about the chemical physics behind the bubbling properties of Champagne and sparkling wines are collected and fully illustrated. The first chapter is devoted to the history of champagne and to a presentation of the tools of the physical chemistry of interfaces needed for a whole comprehension of the book. Then, the three main steps of a fleeting champagne bubble's life are presented in chronological order, that is, the bubble nucleation on the glass wall (Chap.2), the bubble ascent and growth through the liquid matrix (Chap.3), and the bursting of bubbles at the liquid surface (Chap.4), which constitutes the most intriguing, functional, and visually appealing step. L'objectif général de ce travail consacré à l'étude des processus physicochimiques liés à l'effervescence des vins de Champagne était de décortiquer les différentes étapes de la vie d'une bulle de champagne en conditions réelles de consommation, dans une flûte. Nous résumons ci-après les principaux résultats obtenus pour chacune des étapes de la vie de la bulle, depuis sa naissance sur les parois d'une flûte, jusqu'à son éclatement en surface. Nucléation À l'aide d'une caméra rapide munie d'un objectif de microscope, nous avons pu mettre à mal une idée largement répandue. Ce ne sont pas les anfractuosités de la surface du verre ou de la flûte qui sont responsable de la nucléation hétérogène des bulles, mais des particules adsorbées sur les parois du

  8. Visual Investigation of Retrograde Phenomena and Gas Condensate Flow in Porous Media Étude visuelle des phénomènes rétrogrades et de l'écoulement des gaz de condensat en milieux poreux

    Directory of Open Access Journals (Sweden)

    Danesh A.

    2006-11-01

    Full Text Available The mechanism of retrograde condensation and the flow of gas-condensate in horizontal porous media under simulated reservoir conditions were visually studied. Two-dimensional glass micromodels with homogeneous pore structures, as well as heterogeneous patterns, reproduced from real rock micrographs were employed in this study. Depletion tests were carried out using synthetic multicomponent hydrocarbon gas mixtures and also a North Sea gas condensate. The multiphase flow behaviour of the tested systems, as observed and recorded on video, is presented here along with the measured data. In water-wet pores, condensate was observed to be formed as a continuous thin film on connate water, which was the preferred site for condensation. Pressure reduction below the system cricondenbar resulted in the growth of the condensate almost exclusively on water rings at pore throats and dead end pores. The condensate was observed to flow through thin films even at low saturations, with little contribution to the condensate recovery. The rate of pressure depletion influenced the gas flow shear and was found to strongly affect the condensate propagation. Local instabilities could promote significant condensate movement in pore sections which would only be retarded further downstream by capillary effects diminishing the condensate recovery. Relative permeability-saturation relation-ships for gas-condensate flow should not be expected to take the same form as the oil-gas relative permeability for solution gas or external gas drive. Le mécanisme de la condensation rétrograde et l'écoulement des gaz de condensat en milieu poreux horizontal dans une simulation des conditions naturelles ont fait l'objet d'études visuelles. Des micromodèles en verre bi-dimensionnels à structure poreuse homogène, et des éléments hétérogènes reproduisant des micrographies de roches réelles, ont été utilisés pour cette étude. Des essais d'épuisement ont été effectu

  9. Restrizioni strutturali e teoria linguistica nel discorso bilingue

    Directory of Open Access Journals (Sweden)

    Antonio Piga

    2015-01-01

    grammatical’ and which on the other hand are those considered as ‘non-grammatical’ or ‘impossible’, (c the possible existence of grammatical constraints and models that may govern the compatibility of constituents of the two codes in contact. Riassunto - L’obiettivo del presente contributo è quello di offrire un panorama rappresentativo di un fenomeno largamente diffuso in Sardegna: l’alternanza linguistica da parte degli immigranti durante le varie interazioni con i parlanti sardi. La commutazione di codice rappresenta infatti una di quelle strategie discorsive cui ricorrono gli apprendenti durante le varie fasi di acquisizione di una L2, allo scopo di soddisfare eventuali esigenze comunicative e compensare le carenze nella competenza linguistica durante i vari scambi interazionali con gli interlocutori nativi nel paese in cui temporaneamente soggiornano. In questa indagine verrà esaminata non tanto la commutazione di codice italiano/inglese, italiano/spagnolo, ecc. quanto piuttosto l’inclusione della varietà dialettale sarda fra le lingue che gli immigrati adoperano nelle diverse interazioni sociali con i parlanti nativi allo scopo di “accelerare l’assimilazione nel gruppo dominante” (Loi Corvetto 2000: 42.Il corpus consiste di circa trenta ore di registrazione di parlato spontaneo. Si è ritenuta infatti prioritaria la possibilità di osservare e esaminare la produzione linguistica di parlanti che interagissero in contesti situazionali i più naturali possibili, pertanto le tecniche adoperate nella raccolta del corpus rispondono principalmente all’ esigenza di poter ottenere dati relativi al parlato naturale, non sorvegliato, di cui è possibile disporre solamente se i parlanti non sanno di essere registrati.Da un punto di vista metodologico, si tratterà in primo luogo di individuare: (a le caratteristiche morfologiche e sintattiche del discorso bilingue italiano/campidanese da parte degli apprendenti italiano L2, vale a dire quali categorie

  10. Composite Risers for Deepwater Applications Risers composites pour applications en mer profonde

    Directory of Open Access Journals (Sweden)

    Metivaud G.

    2006-11-01

    Full Text Available This paper is devoted to the high performance composite tubes developed by the Institut Français du Pétrole (IFP and Aerospatiale for deepwater risers applications. The design principles of the tubes are first presented, along with results of preliminary work carried out as part of the initial feasibility study. Applications of composite tubes to drilling riser Kill and Choke lines and to TLP production risers, both of which have been studied in detail, are then described. Technical and operational advantages obtained from such applications are discussed. Cet article présente les travaux réalisés par l'Institut Français du Pétrole et l'Aerospatiale dans le domaine des tubes composites haute performance pour les applications aux liaisons fond-surface de forage et de production en mer profonde. Les matériaux composites avancés sont une classe de matériaux très particulière, présentant à la fois des caractéristiques mécaniques élevées et une densité spécifique faible. Ils sont utilisés principalement par les industries de l'aéronautique et de l'espace, mais l'industrie pétrolière en mer profonde est un secteur où ils peuvent trouver dans l'avenir des applications très intéressantes, notamment les tubes de risers. Les tubes de risers pétroliers en mer présentent en effet une gamme de spécifications élevées (diamètres, pression, traction, fatigue dans un environnement sévère et leur poids suspendu peut pénaliser fortement les systèmes de forage ou de production par grande profondeur d'eau. Un premier concept de tube composite haute performance a été développé par IFP et Aerospatiale au début des années 1980 ; sa partie courante, réalisée par enroulement filamentaire de fibres de verre R ou de fibres de carbone, et son système d'embout ont été soumis à une série d'essais mécaniques (pression interne jusqu'à 105 MPa, traction supérieure à 1 000 kN pour un diamètre nominal de 0,1 m, millions de

  11. Conception et calibration d'un sonoreacteur pour l'oxydation de la cellulose par le systeme TEMPO/NaOCl/NaBr

    Science.gov (United States)

    Paquin, Michel

    grande consommation d'energie et de reactif qui rend le procede difficilement accessible au milieu industriel. L'utilisation des ultrasons lors de la reaction d'oxydation permet de reduire de 50% le temps de reaction et d'autant la consommation de produits chimiques. Actuellement le processus d'oxydation s'effectue en mode discontinu pour une quantite de 20 grammes de pate dans un reacteur en verre dans un bain a ultrason. L'objectif principal de ce travail est d'elaborer un sonoreacteur en mode semi-continu afin d'etre en mesure de transferer une reaction d'oxydation du mode discontinu en mode semi-continu. Le transfert de reaction sera effectue en realisant la calibration de l'activite acoustique des deux differents reacteurs, discontinu et semi-continu, par la methode de Weissler. La methode de Weissler quantifie le taux de production radicalaire en mesurant la formation d'iode moleculaire d'une solution aqueuse d'iodure de potassium sous ultrason. Suite a sa calibration, le sonoreacteur pilote (mode semi-continu) a demontre une augmentation de la production radicalaire de 683 % a 170 kHz en comparaison avec l'utilisation d'un bain a ultrason a la meme frequence. Lors de la reaction d'oxydation, la puissance optimale utilisee dans le bain a ultrason a 170 kHz est de 1000 W. La puissance utilisee selon les resultats de calibration obtenue dans le sonoreacteur pilote est de 125 W soit une diminution de l'energie appliquee de 87,5 %. Lors de la reaction d'oxydation, le taux de production des groupements carboxylates est de 2,6 mmol COOH kg/min dans le bain a ultrason et de 6,87 mmol COOH kg/min dans le sonoreacteur pilote soit une augmentation de 164% du taux de formation. Selon les resultats obtenus, l'utilisation d'un sonoreacteur en mode continu peut etre envisageable pour la reaction d'oxydation de la cellulose par le systeme TEMPO-NaOCl-NaBr en industrie au niveau industriel.

  12. Crack propagation in disordered materials: how to decipher fracture surfaces

    Science.gov (United States)

    Ponson, L.

    prédictions, il est nécessaire de comprendre comment le désordre structural du matériau influe sur le comportement d'une fissure. Dans cette optique, les surfaces de rupture représentent un champ d'investigation très prometteur. À travers une étude portant sur divers matériaux hétérogènes, nous caractérisons les propriétés statistiques de leur rugosité et déterminons dans quelle mesure elles sont indépendantes du matériau. Nous montrons notamment que les surfaces de rupture présentent des propriétés d'invariance d'échelle anisotropes, caractérisées par deux exposants universels. Étudiant ensuite une céramique de verre, matériau hétérogène modèle dont on peut contrôler la microstructure, on montre qu'il existe une seconde classe de surfaces de rupture caractérisée par la même structure anisotrope mais présentant des exposants plus faibles. Utilisant enfin des outils théoriques issus de la physique statistique hors équilibre combinés avec la mécanique de la rupture, nous établissons le lien entre ces propriétés et les mécanismes généraux de rupture à l'échelle microscopique. Cette étude nous permet notamment d'associer les deux classes de surfaces de rupture à un processus de fissuration mettant en jeux de l'endommagement pour l'un et à une rupture parfaitement fragile pour l'autre.

  13. Determining concentration fields of tracer plumes for layered porous media in flow-tank experiments

    Science.gov (United States)

    Yu, Zhongbo; Schwartz, Franklin W.

    In the laboratory, computer-assisted image analysis provides an accurate and efficient way to monitor tracer experiments. This paper describes the determination of detailed temporal concentration distributions of tracers in a flow-tank experiment by analyzing photographs of plumes of Rhodamine dye through the glass wall of the tank. The methodology developed for this purpose consists of four steps: (1) digitally scanning black and white negatives obtained from photographs of the flow-tank experiment; (2) calibrating and normalizing each digitized image to a standard optical-density scale by determining the relation between the optical density and pixel value for each image; (3) constructing standard curves relating the concentration in an optical density from five experimental runs with predetermined concentrations (2-97mg/L) and (4) converting the optical density to concentration. The spatial distribution of concentration for two photographs was determined by applying these calibration and conversion procedures to all pixels of the digitized images. This approach provides an efficient way to study patterns of plume evolution and transport mechanisms. Résumé Au laboratoire, l'analyse d'images assistée par ordinateur est un moyen précis et efficace pour suivre certaines expériences de traçage. Ce papier présente comment sont déterminées dans le détail les distributions temporelles de la concentration en traceur au cours d'une expérience d'écoulement en réservoir au moyen de l'analyse de photographies de panaches de rhodamine à travers la paroi de verre du réservoir. La méthodologie développée dans cette expérience suit quatre étapes: (1) digitalisation par balayage des négatifs noir et blanc des prises de vue de l'expérience d'écoulement en réservoir (2) calibration et normalisation de chaque image digitalisée par rapport à une échelle étalon de densité optique en déterminant la relation entre la densité optique et la valeur des pixels

  14. Configuration de piégeage dans un milieu poreux à saturation résiduelle en huile Configuration of Trapping in a Porous Medium with Residual Oil Saturation

    Directory of Open Access Journals (Sweden)

    Sylvestre L.

    2006-11-01

    Full Text Available Cette étude est consacrée à l'analyse de l'hydrodynamique et de la répartition spatiale des phases liquides dans un milieu poreux à saturation résiduelle en huile. Les expériences ont été réalisées dans un milieu poreux constitué de billes de verres, empilées dans une colonne; par balayage à l'eau, nous avons réalisé des saturations en décane, allant jusqu'à 30 % du volume des pores. Pour chaque expérience, nous avons tracé l'eau de balayage à l'aide d'un colorant insoluble dans l'huile. L'analyse des courbes de distribution des temps de séjour du traceur, obtenues à la sortie du milieu, a été faite grâce à un modèle chromatographique de type piston-dispersion avec échange (PDE : ce modèle fait intervenir un ensemble de pores dans lesquels la phase de balayage est en écoulement et, d'autre part, des domaines stagnants contenant l'eau et l'huile piégées. Dans une première étape, l'analyse des équations nous a conduit à définir, sous forme de variables adimensionnelles, la pénétrabilité du milieu poreux et les constantes de temps caractérisant respectivement l'écoulement dans la phase mobile et la diffusion dans les zones stagnantes. L'examen de l'influence de ces variables sur les flux transférés nous conduit à définir un état d'équilibre de distribution du soluté entre phase stagnante et phase mobile. Nous avons sélectionné deux situations de référence - équilibre quasiment atteint et pénétration négligeable des zones stagnantes; sur ces bases, nous avons établi des corrélations entre les paramètres du modèle caractérisant respectivement ces deux états. Dans une deuxième étape, nous avons interprété les résultats expérimentaux à l'aide du modèle PDE. En tenant compte des conditions opératoires et de la sensibilité du modèle vis-à-vis de ses différents paramètres, nous avons mis en évidence les paramètres qui pourraient être raisonnablement identifiés. Nous avons pu

  15. The Problem of Storing Fission Products Arising from the Processing of Irradiated Uranium-Molybdenum Alloys; Probleme du Stockage des Produits de Fission en Provenance du Traitement des Alliages Uranium-Molybdene Irradies; 041f 0420 041e 0411 041b 0415 041c 0410 0425 0420 0410 041d 0415 041d 0418 042f 041e 0422 0425 041e 0414 041e 0412 041f 041e 0421 041b 0415 041f 0415 0420 0415 0420 0410 0411 041e 0422 041a 0418 041e 0411 041b 0423 0427 0415 041d 041d 041e 0413 041e 0421 041f 041b 0410 0412 0410 0423 0420 0410 041d - 041c 041e 041b 0418 0411 0414 0415 041d ; El Problema del Almacenamiento de los Productos de Fision Procedentes del Tratamiento de las Aleaciones Uranio-Molibdeno Irradiadas

    Energy Technology Data Exchange (ETDEWEB)

    Faugeras, P.; Kikindai, T. [Commissariat a l' Energie Atomique, Paris (France)

    1963-02-15

    Uranium-molybdenum alloys are of value thanks to their in-pile behaviour but serious disadvantages arise in connection with the storing of fission products resulting from the processing of these alloys. Because of the insolubility of molybdenum it is impossible to concentrate a solution of fission products by evaporation, and for this reason we have directed our efforts towards the solubilization of molybdenum through the addition of reagents such as iron or phosphoric ions. In this way one can obtain final solutions of 60 g/l Mo with Fe 100 g/l Mo with PO{sub 4}H{sub 3}. The volumes to be stored are still considerable (especially with Fe) and the possibility of nitrate calcination in a fluidized bed was considered. The reaction takes place at about 400 Degree-Sign C. The behaviour of the ruthenium and the friability of the calcined solid (formation of considerable amounts of fine material) have led us to abandon this process in favour of the preparation of phosphate glasses. (author) [French] Les alliages U-Mo sont interessants par leur tenue en pile, mais ils presentent des inconvenients serieux quant au stockage des produits de fission resultant de leur traitement. L'insolubilite du molybdene interdit toute concentration par evaporation de la solution de produits de fission. C'est pourquoi les auteurs ont oriente leurs etudes vers la solubilisation du molybdene par addition de reactifs tels que le fer ou les ions phosphoriques. Ainsi, on peut obtenir les solutions finales a 60 g/l Mo avec Fe, 100 g/l Mo avec PO{sub 4}H{sub 3} Les volumes a stocker sont encore importants (surtout avec Fe) et la calcination des nitrates dans un lit fluidise a ete etudiee. La reaction a lieu vers 400 Degree-Sign C. Le comportement du ruthenium et la friabilite du solide calcine (formation importante de fines) a conduit a abandonner ce procede au profit de la confection de verres phosphates. (author) [Spanish] Las aleaciones U-Mo son interesantes por la forma en que se comportan en

  16. Trace Analysis of Boron in Nuclear Graphite by Means of Gas Chromatography; Analyse de traces de bore dans le graphite nucleaire au moyen de la chromatographie gazeuse; Analiz metodom gazovoj khromatografii sledov bora v yadernom grafite; Analisis de vestigios de boro en el grafito nuclear por cromatografia de gases

    Energy Technology Data Exchange (ETDEWEB)

    Zado, F. [Rudjer Boskovlc Institute, Zagreb, Yugoslavia (Croatia)

    1963-11-15

    No literature is available about the application of gas chromatography in trace analysis of boron in graphite. The following methods of transformation of boron into its volatile compounds are discussed: (a) Ignition of graphite in a stream of oxygen and subsequent transformation of boron oxide into volatile methyl borate which is then analysed on a Dilkens Aerograph H Model 96 gas chromatograph with silicone column and hydrogen as carrier (concentration method). (b) Extraction of boron from the graphite by means of sodium fluoride at 2800{sup o}C with simultaneous chlorination and trapping of boron trichloride, which is then analysed (direct method). A home-made gas chromatograph with a thermal conductivity detector and nitrogen as a carrier was used. The column was made of glass with a 20% (wt./wt.) fluorocarbon oil on kieselguhr. Special precautions were taken on account of the sensitivity of boron trichloride to moisture. (author) [French] Rien n'a ete publie sur l'application de la chromatographie gazeuse a l'analyse de traces de bore dans le graphite. L'auteur examine les methodes suivantes de transformation du bore en composes volatils: a) Brulage du graphite dans un courant d'oxygene, puis transformation de l'oxyde de bore en borate de methyle volatil, que l'on analyse ensuite a l'aide d'un appareil a chromatographie gazeuse Dilkens Aerograph H, Modele 96, utilisant une colonne de silicium et de rhydrogene comme entrafheur (methode de concentration). b) Extraction du bore contenu dans le graphite par chauffage avec du fluorure de sodium a 2800{sup o}C, avec chloruration simultanee et captage du trichlorure de bore qui est ensuite analyse (methode directe). On s' est servi d'un appareil a chromatographie gazeuse construit sur place, dote d'un detecteur a conductibilite thermique et utilisant l'azote comme entrafheur. La colonne etait faite de verre contenant 20% en poids de fluorocarbure huileux sur du kieselguhr. Des precautions particulieres ont ete prises

  17. Caracterisation experimentale de la transmission acoustique de structures aeronautiques

    Science.gov (United States)

    Pointel, Vincent

    Le confort des passagers à l'intérieur des avions pendant le vol est un axe en voie d'amélioration constante. L'augmentation de la proportion des matériaux composites dans la fabrication des structures aéronautiques amène de nouvelles problématiques à résoudre. Le faible amortissement de ces structures, en contre partie de leur poids/raideur faible, est non favorable sur le plan acoustique, ce qui oblige les concepteurs à devoir trouver des moyens d'amélioration. De plus, les mécanismes de transmission du son au travers d'un système double paroi de type aéronautique ne sont pas complètement compris, c'est la raison qui motive cette étude. L'objectif principal de ce projet est de constituer une base de données pour le partenaire industriel de ce projet : Bombardier Aéronautique. En effet, les données expérimentales de performance d'isolation acoustique, de systèmes complets représentatifs d'un fuselage d'avion sont très rares dans la littérature scientifique. C'est pourquoi une méthodologie expérimentale est utilisée dans ce projet. Deux conceptions différentes de fuselage sont comparées. La première possède une peau (partie extérieure du fuselage) métallique raidie, alors que la deuxième est constituée d'un panneau sandwich composite. Dans les deux cas, un panneau de finition de fabrication sandwich est utilisé. Un traitement acoustique en laine de verre est placé à l'intérieur de chacun des fuselages. Des isolateurs vibratoires sont utilisés pour connecter les deux panneaux du fuselage. La simulation en laboratoire de la couche limite turbulente, qui est la source d'excitation prépondérante pendant la phase de vol, n'est pas encore possible hormis en soufflerie. C'est pourquoi deux cas d'excitation sont considérés pour essayer d'approcher cette sollicitation : une excitation mécanique (pot vibrant) et une acoustique (champ diffus). La validation et l'analyse des résultats sont effectuées par le biais des logiciels

  18. Effets de l'interaction avec l'oxygène sur le comportement de couches semi-conductrices de ZnO, SnO{2} et CdSe

    Science.gov (United States)

    Ain-Souya, A.; Ghers, M.; Haddad, A.; Tebib, W.; Rehamnia, R.; Messsalhi, A.; Bounouala, M.; Djouama, M. C.

    2005-05-01

    Les propriétés superficielles des matériaux solides diffèrent de celles du volume. A la surface, des défauts de différentes natures peuvent être présents. Ils permettent à la surface d'être interactive avec le milieu ambiant. Les multiples interactions entre les états de surface et des éléments du milieu extérieur peuvent modifier les propriétés superficielles. Ce travail étudie la régénération de couches semi-conductrices après adsorption isotherme d'oxygène à différentes températures effectuées entre 20 ° C et 300 ° C. Les matériaux qui ont servi à l'étude sont des couches de ZnO, SnO{2} et CdSe. Celles de CdSe ont été obtenues par co-évaporation, sous vide, de cadmium et de sélénium. Les échantillons de ZnO et SnO{2} ont été élaborés par oxydation, à des températures respectives de 450 ° C et 200 ° , de Zn et Sn déposés par électrolyse et par évaporation sous vide. Les matériaux évaporés ont été déposés sur des plaquettes en verre, les autres ont été électrodéposés sur des substrats métalliques. Les variations des propriétés électriques des couches ont été suivies par mesure de leur résistance électrique superficielle R. Les courbes LogR = f (103 /T (K)), relevées sous vide à différentes températures, sont caractéristiques d'un comportement de semi-conducteur. Des essais d'adsorption d'O{2} à différentes températures montrent des variations considérables de R. En effet, la chimisorption forte d'un gaz par une surface semi-conductrice est telle que l'échange électronique entre adsorbant et adsorbat provoque la formation d'une zone de charge d'espace modifiant la conduction superficielle. Les résultats mettent en évidence des domaines de température de plus haute sensibilité à l'oxygène. Pour le CdSe, certaines désorptions isothermes ont été suffisantes pour une régénération totale des échantillons. Les couches de ZnO ont souvent nécessité des désorptions programm

  19. Investigations of the chemical states of carrier-free phosphorus-32 as extracted into water from pile-irradiated sulphur; Recherches sur les etats chimiques du phosphore-32 sans entraineur obtenu par extraction aqueuse a partir de soufre irradie dans un reacteur; Issledovanie khimicheskogo sostoyaniya svobodnogo ot nositelya fosfora-32 pri izvlechenii ego v vodu iz obluchennoj v yadernom reaktore sery; Estudio de los estados quimicos del fosforo-32 libre de portador que se obtiene por extraccion acuosa del azufre irradiado en un reactor

    Energy Technology Data Exchange (ETDEWEB)

    Dahl, J B; Birkelund, O R [Institutt for Atomenergi, Kjeller, Lillestrom (Norway)

    1962-01-15

    {>=} 5). Aucun metaphosphate (cyclique) n'a ete decele dans la solution lors de la production et du stockage. Les resultats indiquent que les composes de polyphosphore ont ete formes dans le materiau de cible au cours de l'irradiation. On a etudie plus particulierement l'adsorption des composes du phosphore-32 sans entraineur par le verre dans les conditions de l'experience. (author) [Spanish] Uno de los metodos que se emplean para obtener fosforo-32 libre de portador consiste en irradiar azufre en un reactor y extraer con agua el fosforo formado. La presente memoria informa sobre los estados quimicos del fosforo-32 en soluciones acuosas durante las diversas fases del proceso normal de obtencion. Los autores han estudiado tambien las modificaciones que el estado quimico de los compuestos de fosforo-32 experimenta en el producto final, en funcion del tiempo de almacenamiento. Han encontrado que el fosforo-32 aparece principalmente en forma de orto-fosfato. La proporcion de ortofosfato aumenta durante el tratamiento quimico; al comenzar la extraccion, es del orden del 70 por ciento, en tanto que alrededor del 98 por ciento del fosforo-32 libre de portador obtenido como producto final se encuentra bajo forma de ortofosfato. Los componentes restantes de la mezcla consisten en piro-, tri-, tetra- y polifosfatos de cadena larga (con un numero de atomos de fosforo {>=} 5). Durante la elaboracion y almacenamiento los autores no han encontrado metafosfatos (ciclicos) en ninguna de las soluciones. Los resultados obtenidos indican que los compuestos polifosforicos se formaron en el material del blanco durante la irradiacion. Los autores han prestado especial atencion al estudio de la adsorcion de compuestos de fosforo-32 libre de portador por el material de vidrio en las condiciones experimentales. (author) [Russian] Odnim iz sovremennykh metodov polucheniya svobodnogo ot nositelya fosfora-32 yavlyaetsya izvlechenie ego v vodu iz obluchennoj v yader- nom reaktore sery. V

  20. Calibrazioni a terra e prestazioni in volo di spettrometri ad immagine nel visibile e nel vicino infrarosso per l'esplorazione planetaria

    Science.gov (United States)

    Filacchione, Gianrico

    2006-10-01

    progettuale e realizzativa dei parametri e de lle prestazioni strumentali; in generale infatti non solo sarà necessario mantenere le dimensioni, il peso, i consumi elettrici ed il data-volume entro i requisiti disponibili del satellite ma anche ottimizzare i disegni ottici, meccanici ed elettronici al fine di ottenere le massime prestazioni possibili in funzione della natura del target osservato e dei parametri orbitali della missione. Questa tesi descrive i metodi utilizzati per caratterizzare il funzionamento di spettrometri ad immagine per l’esplorazione planetaria. L’attività svolta ha riguardato sia la misura in laboratorio dei parametri strumentali fondamentali sia l’analisi dei dati in volo su cui verificarne ed eventualmente correggerne la risposta. Il funzionamento degli strumenti e la metodologia di calibrazione vengono descritti nelle due parti principali e nelle appendici di questa tesi per gli esperimenti Cassini-VIMS-V e Rosetta-VIRTIS-M. La prima parte è dedicata all’esperimento VIMS-V sul satellite Cassini, il cui disegno ottico, originariamente proposto da Francis Reininger, verrà successivamente riutilizzato e perfezionato su VIRTIS-M (Reininger et al., 1994; Miller et al., 1996). Il capitolo 1 contiene una descrizione dei parametri ottici, strutturali, termici ed elettronici di VIMS-V mettendone in risalto gli aspetti più innovativi del progetto. Vengono inoltre descritti la collocazione dell’esperimento sul satellite Cassini, il coallineamento con gli altri strumenti di remote sensing, i possibili modi operativi ed il formato dei dati scientifici. Il capitolo 2 riguarda il processo di calibrazione ed analisi dei dati in volo di VIMS-V. La procedura eseguita per calibrare radiometricamente lo strumento utilizzando i dati della superficie della Luna e per stimare il flat-field mediante i dati dell’atmosfera di Venere viene dettagliatamente descritta assieme agli algoritmi utilizzati per la rimozione di diversi effetti strumentali (read

  1. Le stéréorestituteur Kelsh

    Science.gov (United States)

    Kelsh, H.T.

    1949-01-01

    Le ste??re??orestituteur Kelsh est un appareil de restitution a?? double projection base?? sur le principe des anaglyphes, comme le Multiplex par exemple, mais il a une plus grande pre??cision que ce dernier, vu que les ne??gatifs sont utilise??s directement pour la restitution, sans que l'on soit oblige?? de les re??duire au pre??alable. Une telle solution devient possible lorsque l'e??chelle de l'image plastique (mode??le) est au moins 7 fois plus grande que celle des cliche??s. L'appareil comprend un support reposant par 4 pieds sur la table a?? dessin. Sa partie supe??rieure porte, par l'interme??diaire de trois vis calantes, un cadre dans lequel les deux chambres de projection sont suspendues. Des leviers de commande, agissant sur les chambres, permettent d'introduire la base, le de??versement et les inclinaisons transversale et longitudinale. Les cliche??s conjugue??s ou des diapositifs sont directement place??s dans les chambres de projection munies d'objectifs. En projetant les deux cliche??s au moyen de couleurs comple??mentaires, l'observateur - muni de lunettes a?? verres colore??s (couleurs comple??mentaires) - observe l'image plastique audessus de la table a?? dessin, l'orientation relative des chambres ayant e??te?? e??tablie au pre??alable. Pour le report des points de l'image plastique sur la minute, l'ope??rateur dispose d'une tablette amovible a?? marque-repe??re lumineuse qu'il de??place a?? la main et dont la hauteur au-dessus de la table a?? dessin peut e??tre commande??e par une molette. Pour e??tablir l'orientation absolue de l'image plastique, il suffit d'incliner convenablement le cadre de suspension a?? l'aide des vis calantes, l'orientation relative n'e??tant pas de??truite par cette ope??ration. Les deux cliche??s sont e??claire??s par des projecteurs munis d'une suspension a?? la cardan et relie??s a?? la tablette de restitution par des tiges te??lescopiques. Moyennant ce dispositif, l'e??clairage est concentre?? sur deux petites re

  2. 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

  3. Radio Column Chromatographic Assay of H{sup 3}-Labelled Substances; Analyse par radiochromatographie en colonne, de substances marquees par le tritium; Radiokhromatograficheskoe ispytanie mechennykh tritiem veshchestv na kolonke; Analisis por radiocromatografia en columna de sustancias marcadas con {sup 3}H

    Energy Technology Data Exchange (ETDEWEB)

    Scharpenseel, H W; Menke, K H [Institute of Soil Science and Institute of Animal Husbandry, Bonn University, Bonn (Germany)

    1962-01-15

    auteurs ont compares: 1. Le liquide sortant de la colonne passe a travers un tube scintillateur en matiere plastique, enroule en spirale autour d'un cylindre en ''Plexiglas'' et place dans un bain d'huile de silicone, dans un guide de lumiere avec reflecteurs en TiO{sub 2}. Ou encore, le liquide tritie sortant de la colonne passe par un flacon rempli d'un scintillateur en matiere plastique sous forme de perles, comme dans la methode de Steinberg. Ces deux variantes, qui donnent des resultats tres satisfaisants pour le carbone-14, ont un rendement de comptage inferieur a 1% pour le tritium, par suite du rapport defavorable entre la surface et le volume. 2. Avant d'etre analyse, le liquide sortant de la colonne est melange, dans la proportion de 1 a 30, avec du toluene/ethanol 3:2 au moyen d'un agitateur magnetique; ensuite, on fait passer ce melange dans un serpentin en verre exempt de potassium-40, entre le phototube d'analyse et celui de controle. Afin d'assurer un ecoulement laminaire et un rapport constant de volume entre les substances melangees, des pompes de dosage sont utilisees pour ajouter une substance-tampon a la colonne et pour maintenir le rapport 1:30 du melange en volume. Le rendement de comptage de {sup 3}H est de 2,5 a 4% en moyenne, lorsque la spirale couvre tout le diametre du phototube. 3. Le liquide aqueux sortant de la colonne passe par un tube en verre rempli d'anthracene, et le tritium est compte a 1% pres. (author) [Spanish] En la mayoria de los casos, las determinaciones radiocromatograficas combinadas de compuestos tritiados forman parte integrante de los experimentos bioquimicos con compuestos marcados con {sup 3}H. Al emplear aparatos de exploracion con contadores de flujo sin ventana, la radiocromatografi a sobre papel de los compuestos tritiados da rendimientos de recuento del 0,5 al 1,5%, segun el espesor del papel y la autoabsorcion en el compuesto marcado. La radiocromatografi a en fase gaseosa de dichos compuestos tampoco presenta

  4. Containment of Radioactive Waste for Sea Disposal and Fisheries Off the Canadian Pacific Coast; La Mise en Recipients des Dechets Radioactifs en Vue de leur Elimination dans la Mer et la Protection des Pecheries Operant au Large de la Cote Canadienne de l'Ocean Pacifique; 0423 0414 0414 ; Confinamiento de Desechos Radiactivos para su Evacuacion en el Mar, en Relacion con las Pesquerias de la Costa Canadiense del Pacifico

    Energy Technology Data Exchange (ETDEWEB)

    Waldichuk, Michael [Fisheries Research Board of Canada Biological Station, Nanaimo, BC (Canada)

    1960-07-01

    1946 a 1957 inclusivement, on a immerge, au large de la cote de Californie, un total de 16.288 bidons de 230 litres environ, remplis de dechets a faible radioactivite. Au cours de ces operations d'evacuation dans les eaux des Etats-Unis, on s'est efforce d'observer deux criteres principaux: 1) assurer la securite des manipulations entre la source des dechets et le lieu d'evacuation et 2) d'engloutir de facon appropriee les dechets dans la mer. Aucune condition n'a ete fixee au sujet de l'integrite du recipient ou du contenu, une fois parvenus dans les profondeurs de la mer. Le memoire expose d'autres methodes pour renfermer des dechets radioactifs qui ont ete utilisees ou suggerees precedemment: mise en recipients metalliques, adsorption sur de l'argile et integration dans du verre. Afin de rendre les dechets radioactifs inoffensifs pour les poissons et autres organismes aquatiques, il faut 1) soit les isoler du milieu environnant, 2) soit les disperser afin d'abaisser leur radioactivite a, la concentration autorisee. Il a ete propose, pour isoler les dechets du milieu environnant, de les placer dans un recipient spherique construit selon un plan approprie, scelle hermetiquement et capable de resister a de hautes pressions; il servirait pour l'elimination des dechets solides a radioactivite faible ou moyenne. Les poissons peuvent etre affectes par les dechets radioactifs de plusieurs manieres : 1) par rayonnement direct des matieres radioactives eliminees; ' 2) par ingestion d'organismes alimentaires contenant des radioisotopes concentres ; 3) par irradiation de l'eau contenant des ions ou particules radioactifs et 4) par contamination, au contact de matieres riches en radioisotopes precipitees en profondeur. L'auteur pense qu'il est bon de poursuivre les recherches avant d'autoriser l'elimination en grand des dechets radioactifs dans la mer. (author) [Spanish] Los desechos de baja radiactividad suelen ser, por lo general, basuras de laboratorio contaminadas, piezas de

  5. Preparation of Uranium Dioxide by Electrochemical Reduction in Ammonium Carbonate Solutions and Subsequent Precipitation; Preparation de bioxyde d'uranium par reduction electrochimique dans des solutions de carbonate d'ammonium et precipitation; Prigotovlenie dvuokisi urana metodom ehlektrokhimicheskogo vosstanovleniya v rastvore karbonata ammoniya s posleduyushchim osazhdeniem; Preparacion de dioxido de uranio por reduccion electroquimica en soluciones de carbonato amonico u precipitacion subsiguiente

    Energy Technology Data Exchange (ETDEWEB)

    Pravdic, V.; Branica, M.; Pucar, Z. [Department of Physical Chemistry, Rudjer Boskovic Institute, Zagreb, Yugoslavia (Serbia)

    1963-11-15

    'il est possible d'obtenir, avec un bon rendement, de l'uranium (IV) en solution carbonatee. Il suffit de chauffer la solution pour faire precipiter l'hydroxyde d'uranium (IV). Afin d'obtenir des matieres en quantites plus importantes, pour les essais technologiques, les auteurs ont fait une experience en plus grand. Ils ont construit une cellule d'electrolyse en chlorure de polyvynile dur, avec une cathode de mercure (environ 2,5dm{sup 2} ) et des anodes de platine. Le catholyte etait separe de l'anolyte par des membranes echangeuses de cations. Le catholyte circulait entre deux reservoirs de 50 1 et passait sur la cathode de mercure soumise a une agitation energique. Le potentiel du mercure etait controle par reference a une electrode temoin de Ag/AgCl/KCl (sat.), et maintenu constant a -1,5 V. Le rendement du courant etait d'environ 90% et la consommation d'energie, pour l'operation de reduction, d'environ 0,8 kWh/kg de bioxyde d'uranium. A la fin de l'electrolyse, on a provoque la precipitation par simple chauffage de la solution (limpide, d'un vert fonce) jusqu'a une temperature de 70 deg. C, dans un autre recipient tout en verre, de 60 1. Sur 50 1 de solution catholytique, on a obtenu 1 kg de produit centrifuge (contenant environ 20% d'eau). L'analyse coulombmetrique du rapport O/U a toujours donne des resultats compris entre 2,04 et 2,09. La methode decrite permet de faire precipiter l'hydroxyde d'uranium (IV) seul et le rapport O/U dans le precipite est independant du degre atteint par la reduction. En analysant la poudre par diffraction des rayons X, on a identifie le produit comme etant la phase alpha du bioxyde d'uranium. On procede maintenant a des experiences de frittage et a l'etude des caracteristiques du bioxyde d'uranium ainsi obtenu pour determiner s'il peut servir a la fabrication de combustible nucleaire ceramique. (author) [Spanish] Se intento ampliar la escala del proceso con el fin de obtener las cantidades de material que requieren los ensayos

  6. Fission-Product Separation as a Final Solution to the Problem of Storing Highly Radioactive Waste; La Separation des Produits de Fission Comme Solution Definitive du Stockage des Dechets Fortement Radioactifs; 0412 042b 0414 ; La Separacion de los Productos de Fision Como Solucion Definitiva del Problema del Almacenamiento de los Desechos de Elevada Radiactividad

    Energy Technology Data Exchange (ETDEWEB)

    Raggenbass, A.; Lefevre, J. [Centre d' Etudes Nucleaires, Saclay (France)

    1963-02-15

    'isolement du cesium-137 et du strontium-90 avec un facteur de decontamination d'au moins 10{sup 4}, ce qui permettrait d'envisager le rejet, apres un traitement d'effluents classique, au bout d'une periode de 10 a 20 ans. Le but du memoire est de faire le point de cette question en l'annee 1962. Les progres realises dans les methodes de separation du cesium et du strontium permettent d'envisager l'obtention de ce facteur 10{sup 4} dans des conditions exploitables industriellement. Des methodes pleines de promesses sont: a) Pour le cesium-137, la precipitation par l'acide phosphotungstique, l'echange sur un sel d'ammonium d'un heteropolyacide, la fixation par un phosphate de zirconium. b) Pour le strontium-90, la precipitation d'oxalate, l'extraction par l'acide di-2-ethyl-hexylphosphorique, l'echange sur des sels varies, sulfate de strontium, etc. Ces progres chimiques sont renforces par les progres realises dans le traitement industriel des effluents et permettent de considerer comme techniquement possible la solution preconisee par Glueckauf. Parallelement, le developpement de l'utilisation de grandes quantites de produits de fission, particulierement dans les programmes SNAP, justifie des investissements qui seront au moins pairtiellement recuperes par la vente des produits fabriques. Il est certain que des sources refractaires, a resistance tres elevee a tous les agents d'agression exterieurs, constituent le mode de stockage le plus satisfaisant pour des produits aussi dangereux et d'aussi longue periode. L'auteur considere done, techniquement et psychologiquement, Inverted-Exclamation-Mark /utilisation de sources concentrees a gainage riche comme le moyen de stockage presentant le plus de garanties. Une discussion comparative de cette methode avec la methode d'incorporation dans les verres meriterait un examen complet et approfondi. (author) [Spanish] En la Conferencia de Ginebra de 1955, Glueckauf formplo la hipotesis de que los problemas planteados por las soluciones de

  7. Intergranular Pressure Solution in Nacl: Grain-To-Grain Contact Experiments under the Optical Microscope Dissolution sous contrainte dans NaCl : expériences de contact grain à grain sous microscope optique

    Directory of Open Access Journals (Sweden)

    Spiers C. J.

    2006-12-01

    effective diffusivity varying with contact force and on-going convergence. The results agree broadly with those of previous compaction creep experiments performed using wet halite powder. Discrepancies with other workers results for single-contact dissolution experiments can be explained in terms of differences in experimental configuration and competition between driving forces. La dissolution sous contrainte (IPS - Intergranular Pressure Solution représente un mécanisme de lithification, de compaction et de déformation à l'échelle géologique pour une large gamme de roches. Les études expérimentales d'IPS réalisées sur des agrégats de quartz n'ont pas été couronnées de succès en raison d'un taux faible d'IPS, et les expériences IPS réalisées en utilisant une halite saturée comme analogue de roche (Spiers et Schutjens, 1990 ; Hickman et Evans, 1991 ont laissé des incertitudes quant au détail des mécanismes IPS et à la structure/saturation au contact du grain dans ce matériau. La présente étude fait état de quatre expériences de dissolution de contact réalisées sous microscope optique afin d'étudier le mécanisme et la cinétique de l'IPS pour des contacts simples halite/halite et halite/verre, chargés en eau salée (température ambiante. Des forces normales de contact dans la gamme de 1,0 à 2,6 N ont été appliquées en présence d'eau salée saturée en NaCl, induisant des pressions de 0,8 à 7,4 MPa. Des pertes de masse et des convergences - fonction du temps - ont été observées pour tous les contacts. Dans tous les cas, le fait de charger le contact (ou d'augmenter la charge sur le contact a conduit à la formation immédiate d'une morphologie de contact rugueuse, composée d'un motif d'îles et de canaux, contrôlé par des caractéristiques cristallographiques, à l'échelle de quelques microns. Cette microstructure non équilibrée a évolué dans le temps vers une face de contact optiquement plate. Le processus de convergence

  8. The Combined Use of Autoradiographic and Electron Microscopic Techniques for Studies on Ultra-Thin Sections of Tritium-Labelled Cells of the Intestinal Epithelium; Emploi Combine de l'Autoradiographie et du Microscope Electronique pour L'Etude de Coupes Ultra-Fines de Cellules Tritiees de l'Epithelium Intestinal; 0421 043e 0432 043c 0435 0414 ; Empleo Combinado de Tecnicas de Autorradiografia y de MicroscopiA Electronica para Estudiar Cortes Ultrafinos de Celulas Tritiadas del Epitelio Intestinal

    Energy Technology Data Exchange (ETDEWEB)

    Hampton, J. C. [Division of Experimental Biology, Baylor University College of Medicine, TX (United States); Quastler, H. [Brookhaven National Laboratory, Upton, Long Island, NY (United States)

    1962-02-15

    dans la cellule. Les travaux presentes dans ce memoire demontrent qu'il est possible d'etudier au microscope electronique des coupes ultrafines de cellules marquees, de recuperer l'echantillon apres avoir pris des micrographies electroniques convenables, de l'enduire d'une emulsion suffisamment epaisse pour obtenir une autoradiographie, mais tout de meme assez mince pour permettre un nouvel examen au microscope electronique et obtenir des images micrographiques des autoradiographies deja faites. L'emulsion autoradiographique a ete appliquee comme suit: formation d'une mince pellicule sur une petite boucle de fil metallique plongee dans l'emulsion liquide, puis transfert de la pellicule par passage de la boucle sur l'echantillon monte, fixe a l'extremite d'une chevillette en plastique. On peut effectuer un controle satisfaisant en prenant, lorsqu'on fait les coupes, une coupe d'un demimicron apres chaque coupe ultrafine en la montant sur une lamelle de verre et en appliquant les techniques autoradiographiques classiques. En raison de la fragilite des coupes ultrafines, le nombre d'autoradiographies reussies est tres faible. Malgre cet inconvenient, on peut esperer qu'avec une plus grande experience et un perfectionnement des techniques, cette methode aidera a mieux comprendre les processus des cellules vitales. (author) [Spanish] Merced al elevado grado de resolucion que puede alcanzarse actualmente por observacion de cortes de celulas en el microscopio electronico, resulta posible estudiar algunos de los procesos intracelulares que conducen a la sintesis de las proteinas. La especificidad de la incorporacion de timidina tritiada en la molecula de acido desoxirribonucleico permite seguir detenidamente el desarrollo del proceso en funcion del tiempo y su localizacion dentro de la celula. Los trabajos descritos en la presente memoria demuestran que es posible estudiar por microscopia electronica cortes ultrafinos de celulas tritiadas, retirar la muestra una vez que se han

  9. A Method of Identification and Inspection for Inventory Control of Irradiated Fuel Elements; Methode d'Identification et d'Inspection Permettant de Proceder a l'Inventaire des Elements Combustibles Irradies; Metod identifikatsii i proverki pri inventarnom kontrole obluchennykh toplivnykh ehlementov; Metodos de Identificacion e Inspeccion para el Control de las Existencias de Elementos Combustibles Irradiados

    Energy Technology Data Exchange (ETDEWEB)

    Kinderman, E. M.; Mills, J. S. [Stanford Research Institute, Menlo Park, CA (United States)

    1966-02-15

    des difficultes materielles particulieres au verificateur ou a l'agent charge de l'inventaire. En effet, ces deux emplacements, la distance entre l'objet et l'observateur, le mauvais eclairage et la distorsion optique provoquee par les protections (eau, verre au plomb) genent les operations d'inventaire. Pour surmonter ces difficultes et pouvoir identifier positivement le combustible decharge, les auteurs ont mis au point un systeme optique peu encombrant et commode comprenant un poste fixe d'observation, un periscope, un telescope et un appareil photographique. Ce systeme a ete soumis a des essais consistant a examiner, dans une piscined'irradiation au cobalt, des echantillons portant differentes marques d'identification, qui ont ete traites dans une boucle de haute activite a circulation d'eau. Ces essais ont ete faits avec un periscope rempli d'eau, de 3,35 m de long, un telescope catadioptrique place a 4,9 m du periscope et un appareil photographique (format 35 mm) pour enregistrer les observations. Le telescope, la camera et les supports sont facilement transportables car ils pesent moins de 10 kg en tout et leurs dimensions maximales n'excedent pas 75 cm. Les photographies dans l'air de mires graduees servant a determiner le pouvoir de resolution et situees a 6 m de l'objectif du telescope ont montre que ce systeme permet de discriminer des graduations de 22 {mu}m, ce qui correspond a un pouvoir de resolution de 0,8 secondesd'arc. Les essais effectues dans l'eau ont montre qu'a une distance de 6m, ce systeme peut resoudre des marques de moins de 50 {mu}, ce qui correspond a un pouvoir de resolution de 1 seconde d 'arc environ. Il est evident que le pouvoir de resolution ne peut jamais etre superieur a celui du systeme utilise dans l'air. Le systeme experimente doit permettre de distinguer toutes marques faites en vue de l'inventaire du combustible. (author) [Spanish] Cuando se hace un inventario completo de materiales nucleares especiales hay que inspeccionar el

  10. Les édifices néogothiques parisiens et leurs verrières : églises et chapelles catholiques

    Directory of Open Access Journals (Sweden)

    Martine Callias Bey

    2012-04-01

    une technique très maîtrisée, qui cependant s’ouvre à des procédés nouveaux comme l’impression de motifs répétitifs sur les verres de bordure ou de fond. Considérant l’éclectisme architectural du XIXe siècle comme un style à part entière, il convient de qualifier de même ce mélange fréquent des styles, pas nécessairement cohérents, utilisés soit pour les personnages soit pour les encadrements dans les verrières dites « archéologiques » ou les « verrières-tableaux ».Despite the interest elicited by 19th century religious art over the past thirty years, Paris has lost much of its 19th century religious stained glass. It was urgent to carry out an inventory of what remains. The aim of this article is to present the Catholic Gothic revival buildings in Paris and their stained glass. The corpus comprises five parish churches, 19 congregational chapels or chapel transformed into parish churches, and two other ancillary buildings. A total of 526 stained-glass works was surveyed and studied; 286 are designs with figures, 37 of these classifiable as stained-glass picture compositions. The remaining 240 works are ornamental. Behind this production, we find some 22 different stained-glass producers, amongst the most important of which are Didron, Lusson, Champigneulle, Hirsch and Gsell. Paris played a leading role in the revival of stained glass during the early years of the 19th century, thanks in part to the perspicacious inspiration of certain figures in power, such as the Prefect of Paris, the Comte de Chabrol, who was at the origins of the ‘resurrection’ of the skill of stained-glass painters with the 1825 creation of the works at the Foire Saint-Laurent. Further inspiration came from the first restoration work carried out on older stained-glass works, and the decisive role of diocesan architects. The iconography of these works reflects the evolution of France’s religious life during the period, from the liberty of the Concordat to

  11. Microbiological Studies on the Influence of Combined Processes of Heat and Irradiation on the Survival of Saccharomyces Cerevisiae Var. Ellipsoideus; Etudes Microbiologiques sur l'Influence d'un Traitement Mixte par Chauffage et Irradiation sur la Survie de Saccharomyces Cerevisiae Var. Ellipsoideus; Mikrobiologicheskie issledovaniya vliyaniya sovmestnykh protsessov nagreva i oblucheniya na vyzhivanie saccharomyces Cerevisiae Var. Ellipsoideus; Estudios Microbiologicos de la Influencia del Calentamiento e Irradiacion Combinados Sobre la Supervivencia del Saccharomyces Cerevisiae Var. Ellipsoideus

    Energy Technology Data Exchange (ETDEWEB)

    Stehlik, G.; Kaindl, K. [Institute for Biology and Agriculture, Reaktorzentrum, Seibersdorf (Austria)

    1966-11-15

    this treatment are under investigation on apple and grape juice. (author) [French] L'un des principaux sujets de recherche inscrits au programme international sur la conservation des fruits et jus de fruits par irradiation, execute a Seibersdorf, est le probleme de la radiosensibilisation des micro-organismes. En vue d'etudier l'effet d'un traitement par la chaleur et l'irradiation sur la survie des cellules de levures (formation de colonies), une souche a forte radioresistance - Saccharomyces cerevisiae var. ellipsoideus - cultivee sur un milieu nutritif semi-synthetique, a ete soumise des le debut de sa phase logarithmique a un traitement combine par chauffage et irradiation gamma (source au cobalt-60). Le traitement thermique a ete applique, soit immediatement avant l'irradiation, soit pendant ou immediatement apres celle-ci. On a fait varier la temperature entre 20 et 52,5 Degree-Sign C. Pour l'irradiation, effectuee dans Bullet un tube en verre bien aere, on a utilise des doses allant jusqu'a 0, 3 x 10{sup 6} rad. L'effet d'inhibition de ce traitement mixte depend de l'ordre de succession du chauffage et de l'irradiation; les resultats obtenus sont les suivants: la combinaison la plus efficace est un traitement simultane par chauffage et irradiation; la combinaison qui consiste a faire suivre le chauffage d'une irradiation a la temperature ambiante est moins efficace; le moindre effet a ete obtenu par chauffage apres irradiation a la temperature ambiante. Le traitement mixte chaleur/irradiation donne des courbes de survie (fractions d'organismes survivants) qui sont des lignes droites ayant pour coordonnees la dose d'irradiation a une echelle semi-logarithimique, et la temperature dans l'intervalle compris entre la temperature ambiante et 45 Degree-Sign C. Au-dessus de 45 Degree-Sign C, les courbes indiquent, a des doses inferieures a 30 krad, un accroissement du nombre des survivants par rapport a l'echantillon non irradie. En comparant les pentes des courbes de

  12. Étude de la mouillabilité des roches réservoir à l'échelle du pore par cryomicroscopie électronique à balayage Wettability of Reservoir Rock At the Pore Scale: Contribution of Cryo-Scanning Electron Microscopy

    Directory of Open Access Journals (Sweden)

    Fassi-Fihri O.

    2006-11-01

    Full Text Available Le but de cette étude est de caractériser, à l'échelle du pore, la mouillabilité des roches réservoir, en relation avec leur géométrie et/ou leur minéralogie. Cette caractérisation se fait, après congélation des échantillons, par l'observation de la distribution des fluides au sein du milieu poreux (saumure et huile brute, en microscopie électronique à balayage. Les expériences ont d'abord été effectuées sur des roches modèles parfaitement mouillables à l'eau, verre fritté et grès naturels. Certains de ces minéraux ont été rendus hydrophobes par greffage de silane. L'étude de ces systèmes a mis en évidence une corrélation entre la mouillabilité et la distribution des fluides. Puis, une roche réservoir (grès argileux de la formation de Brent, de mer du Nord connue comme étant de mouillabilité intermédiaire a été étudiée. Un travail précédent (étude de déplacements eau/huile par tomographie X avait abouti à la conclusion que si ces roches présentaient des hétérogénéités de mouillabilité, l'échelle de ces hétérogénéités devait être inférieure au millimètre. Les études de cryomicroscopie ont montré le caractère hydrophobe de la kaolinite, tandis que les illites, le quartz et les feldspaths sont préférentiellement mouillables à l'eau. L'imbibition spontanée d'huile pourrait ainsi être attribuée à l'existence au sein de la roche d'un réseau de kaolinite, tandis que l'imbibition spontanée de saumure serait due à l'existence d'un second réseau plus ou moins imbriqué avec le premier et constitué des autres minéraux. Un autre cas de roche réservoir a été étudié, à savoir un carbonate du Moyen-Orient. Les mésopores intergranulaires y ont été observés comme étant mouillables à l'huile tandis que les micropores restaient mouillables à l'eau. Dans ce cas, la mouillabilité intermédiaire de ces échantillons s'explique par la géométrie plutôt que par la min

  13. Containment of Plasma Trapped in a Magnetic Well; Confinement d'un Plasma Piege dans un Puits Magnetique; Uderzhanie plazmy, zakhvachennoj v magnitnoj yame; Confinamiento de un Plasma Atrapado en un Pozo Magnetico

    Energy Technology Data Exchange (ETDEWEB)

    Francis, G.; Hill, J. W.; Mason, D. W. [United Kingdom Atomic Energy Authority, Culham Laboratory, Abingdon, Berks. (United Kingdom)

    1966-04-15

    of neutral gas. (author) [French] Le plasma forme dans un canon coaxial est dirige le long d'une ligne d'injection et amene dans une chambre a vide centrale en verre par un champ magnetique convergent. Dans cette chambre, une partie du plasma est reflechie par un miroir magnetique, puis piegee par un autre champ a miroir cree par une impulsion rapide. On peut aussi appliquer des champs stabilisateurs produits par des courants circulant dans six barres de Joffe disposees parallelement a l'axe. Ces champs, a court temps de montee, se'maintiennent a une valeur presque constante pendant 1 ms. Au cours d'experiences faites precedemment avec un plasma dont la densite moyenne etait de 4 x 10{sup 10} cm{sup -3} et l'energie des ions de 1 keV, les auteurs ont constate une instabilite tournante en cannelures dans une configuration a miroir simple, le plasma disparaissant en 60 {mu}s. En appliquant des champs stabilisateurs, la duree de vie des ions de haute energie (mesuree grace a l'emission des atomes neutres ayant subi l'echange de charge) a pu atteindre 250 a 400 {mu}s. Cette decroissance plus rapide que celle qui serait due a l'echange de charge a la pression du gaz residuel de 3 x 10{sup -7} Torr indique un afflux transitoire important de gaz venant des parois de la chambre. Des experiences faites ulterieurement avec des plasmas de densite plus elevee (n Tilde-Operator 10{sup 13} cm{sup -3}, #Greek Lunate Epsilon Symbol# Tilde-Operator 5 keV) ont confirme ces resultats. Au cours'de ces experiences, le flux d'atomes rapides durait de 140 a 200 {mu}s, tant dans les champs simples a miroir que dans les champs combines. Le signal provoque par l'emission due a l'echange de charge presentait un maximum de 30 {mu}s apres le piegeage. Cesignal mesure le produit de la densite des ions rapides par celle du gaz neutre. Une augmentation deliberee de la pression du gaz residuel fusqu'a 10{sup -5} Torr n'a guere modifie l'amplitude du signal. Les essais effectues en vue de modifier l

  14. Injection of Plasma Blobs into A Mirror Trap With Adiabatic Plasma Compression: ''ASPA'' Device; Injection d'Amas de Plasma dans un Piege a Miroirs avec Compression Adiaba Tique - Machine 'ASPA'; Inzhektsiya plazmennykh sgustkov v probochnuyu lovushku s adiabaticheskim szhatiem plazmy. Ustanovka ''ASPA''; Inyeccion de Plasmoides en una Trampa de Espejos con Compresion Adiabatica. La Instalacion 'ASPA'

    Energy Technology Data Exchange (ETDEWEB)

    Babichev, A. P.; Burjak, E. M.; Gorbunova, E. F.; Karchevskij, A. I.; Muromkin, Ju. A. [Institut Atomnoj Ehnergii, Im. I.V. Kurchatova, Moskva, SSSR (Russian Federation)

    1966-04-15

    on the intensity and hardness of this radiation. (author) [French] Les auteurs decrivent les principales caracteristiques de la machine ASPA qui a ete construite en vue d'etudier la compression adiabatique du plasma dans un piege a miroirs magnetiques. La chambre a vide du dispositif se trouve dans un solenoiede (de 4 m de longueur et 1 m de diametre) sur l'axe duquel on peut creer un champ magnetique de guidage longitudinal quasi stationnaire d'une intensite maximum de 5 kOe. Pour produire le plasma, on a utilise un injecteur a.titane ou un canon a plasma coaxial. L'amas de plasma etait injecte le long de l'axe de l'installation et penetrait dans une zone de compression formee d'un tube en verre de 10 cm de diametre. Le champ magnetique a miroirs etait cree a l'aide de deux bobines distantes de 20. cm l'une de l'autre (rapport de miroir 1/2). Le champ magnetique puise maximum dans les miroirs s'elevait a 40 kOe, le temps de montee du champ a Tilde-Operator 40 {mu}s et son temps de chute a 350 {mu}s. La composition et la distribution selon l'energie de la composante ioniquedu plasma dans l'injecteur a titane et dans l'injecteur coaxial ont ete etudiees par spectroscopie de masse. A l'aide d'un interferometre a micro-ondes, ona mesure la densite de l'amasde plasma au cours de son deplacement de l'injecteur vers la zone de compression. On a egalement etudie le passage de cet amas a travers le piege a miroirs pour des champs de 20 kOe. Dans certaines experiences, le champ de miroir etait parallele au champ magnetique de guidage, alors que dans d'autres il etait antiparallele; en d'autres termes, un champ du type 'diverteur' se formait avec deux regions de champ nul. On montre que dans le cas de l'injecteur a titane, comme dans celui de l'injecteur coaxial, l'amas de plasma injecte passe assez facilement a travers le miroir magnetique lorsque la direction de celui-ci coincide avec celle du champ magnetique de guidage, alors qu'il ne le traverse pratiquement pas en

  15. The Technology and Applications of Large Fission Product Beta Sources; Technologie et applications des grandes sources beta de fission; Tekhnologiya i primenenie krupnykh istochnikov beta-izluchenij, ispuskaemykh produktami deleniya; Tecnologia y utilizacion de los productos de fision como fuentes de irradiacion beta de elevada intensidad

    Energy Technology Data Exchange (ETDEWEB)

    Silverman, Joseph [Radiation Applications Incorporated (United States)

    1960-07-15

    perspectives interessantes s'ouvrent a l'application commerciale des emetteurs beta de fission dans le domaine de la radiochimie industrielle, notamment dans celui de la modification superficielle par copolymerisatio n greffee des objets en matiere plastique et des textiles synthetiques. 2. Le developpement approprie des methodes existantes pourrait permettre la production de sources beta massives, resistantes, chimiquement inertes, ne presentant aucun danger et d'un prix peu eleve. Les sources enrobees de verre semblent particulieremen t riches en promesses. 3. Les calculs du taux d'absorption beta montrent qu'il est possible de concevoir des sources de grandes dimensions produisant jusqu'a 20 pour cent d'energie utile. On a etabli des equations et des courbes indiquant la dose et le coefficient d'utilisation en fonction de la forme geometrique et de la composition des divers ensembles source-cible. On est en train de realiser un programme d'experiences pour verifier l'exactitude de ces calculs. 4. Une analyse du cout de l'equipement montre que, du point de vue du prix de l'energie obtenue, les sources beta de fission peuvent rivaliser avec d'autres sources de rayonnements. (author) [Spanish] Hasta hace poco no se habia considerado la posibilidad de utilizar los emisores beta como fuentes de radiacion de elevada intensidad, pues todos los tratamientos por irradiacion que ofrecen interes se basaban en el empleo de particulas de gran poder de penetracion; por ello, se daba mucha importancia a las particulas gamma y a los electrones artificialmente acelerados. Hace unos cuatro anos comenzo a vislumbrarse la posibilidad de aplicar los tratamientos por irradiacion superficial en multiples campos, por ejemplo, para la modificacion por copolimerizacio n de injerto de la superficie de los materiales plasticos moldeados y para la pasteurizacion superficial de los alimentos. En estos casos la penetracion de las radiaciones en las capas internas de los materiales es innecesaria e

  16. Construction and operating characteristics of flexible Geiger counters; Caracteristiques de construction et d'utilisation de compteurs Geiger flexibles; Konstruktsionnaya i operativnaya kharakteristiki gibkikh schetchikov Gejgera; Construccion y caracteristicas de funcionamiento de contadores Geiger flexibles

    Energy Technology Data Exchange (ETDEWEB)

    Richter, H G; Ballard, L F [Research Triangle Institute, Durham, NC (United States)

    1962-04-15

    point une methode de construction de compteurs Geiger flexibles ayant des dimensions tres variees. Les compteurs sont tres flexibles : un compteur de 3 cm de diametre peut etre plie avec un rayon de courbure de 5 cm. En utilisant du gaz Q (98,3% d'helium et 1,7% de n-butane) comme milieu de comptage, les paliers ont une longueur de plusieurs centaines de volts avec une pente de 3% et sont independants de la configuration geometrique du compteur. Les compteurs sont construits avec des tubes en chlorure de polyvinyle (PVC-744 - Alpha Wire Corp.). De courts segments du tube (longueur egale a environ 3 fois le diametre) sont glisses sur un mandrin d'aluminium grossierement filete et entoures d'un fil fortement serre. Le tout est place dans un four a 110{sup o}C pendant 20 minutes. Apres refroidissement, le segment de matiere plastique ainsi cannele est degage du mandrin. Ce traitement du tube empeche sa rupture lorsqu'il est enroule. Un disque de polystyrene, perfore de trous relativement grands a la peripherie pour l'ecoulement du gaz et d'un trou central de 0,6 mm pour le passage de l'anode, est attache a une extremite de chaque segment. En enfilant les segments ainsi prepares sur une anode en tungstene de 3 mm, en glissant une extremite de chaque segment sur le segment adjacent et en les fixant solidement avec un adhesif, on peut construire un compteur d'une longueur quelconque. On attache aux extremites des pieces en verre pour la fixation de l'anode et pour l'admission et l'evacuation du gaz. Un fil de cuivre nu, entoure en spirale dans les cannelures du compteur, donne une cathode externe satisfaisante, qui fonctionne suivant le mode observe par Maze. Un compteur de 3 cm de diametre et de 1 metre de longueur, lineaire ou enroule, possede un palier commencant a 1400 volts et allant jusqu'a 1700 volts avec une pente de 2,9%. On a enregistre des taux de comptage de plus de 300000 coups par minute, avec peu de pertes par coincidences. Comme le compteur est en fait une

  17. Studies on radiation-image detectors; Etudes sur les detecteurs a images de rayonnements; Izuchenie detektorov izobrazheniya radiatsii; Estudios sobre detectores de radiaciones productores de imagenes

    Energy Technology Data Exchange (ETDEWEB)

    Reiffel, L [Armour Research Foundation, Chicago, IL (United States)

    1962-04-15

    collimateur etait constitue par un tube droit de 1 cm sur 1 cm. L'auteur expose l'application de ces compteurs a d'autres etudes neutroniques et presente des observations sur le plus grand pouvoir de resolution que l'on puisse obtenir avec de plus faibles ecartements des electrodes, en procedant a un depouillement dynamique et, eventuellement, par filtrage de l'image optique. Une autre methode generale de detection des rayonnements par l'image consiste dans l'emploi d'ecrans de conversion luminescents ou phosphorescents. Des matrices en fibres luminescentes, composees de tubes de verre tres minces contenant un scintillateur liquide, ont fait l'objet d'essais. Ces matrices sont tres utiles pour la detection des rayons X et des rayonnements {gamma}; les matieres constituant la paroi, ou bien le liquide du coeur, peuvent etre en vue de les rendre sensibles aux neutrons. Le memoire expose de nouvelles methodes de fabrication de divers types d'ecrans en fibres luminescentes, ainsi que des donnees sur le comportement optique, qui ont des rapports avec la technologie de la chambre a scintillation. L'auteur examine brievement des detecteurs a images qui emploieraient des blocs epais de materiaux et qui seraient capables d'emmagasiner des energies non negligeables et d'emettre une phosphorescence stimulee par irradiation; il passe egalement en revue les methodes de lecture utilisant un procede de depouillement optique pour obvier a la diminution du pouvoir de resolution occasionnee par l'epaisseur finie du scintillateur. (author) [Spanish] El autor describe los trabajos sobre detectores de radiaciones capaces de proporcionar informacion sobre la distribucion espacial de estas. Las investigaciones se refieren principalmente al problema de determinar la distribucion de intensidades en un plano, o, si es posible, en una superficie cilindrica. Ello implica estudios sobre difraccion y radiografia neutronicas, sobre radiografia con rayos X y con rayos gamma o sobre la dispersion

  18. Fast Plasma from a Coaxial Gun; Plasma Rapide Produit par un Canon Coaxial; Bystraya plazma iz koaksial'nogo inzhektora; Produccion de Plasma Rapido Mediante un Inyector Coaxial

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, J.; Henins, I. [Los Alamos Scientific Laboratory, Los Alamos, NM (United States)

    1966-04-15

    -electrique complexe se produisant en avant de l'ouverture du canon. Le processus d'acceleration depend de la difference des densites de gaz dont l'une, en avant de l'ouverture du canon, est faible et l'autre, a l'interieur du canon, est forte. Le plasma rapide est en grande partie produit a partir du gaz adsorbe sur les electrodes. Il faut par consequent obtenir un vide propre de maniere a eviter la contamination par des ions rapides d'impuretes fortement ionisees (C{sup 5+}, 10{sup 8} cm/s). La matiere constituant l'electrode s'evapore mais elle ne semble pas etre un agent de contamination important car ce phenomene se produit trop tard. La haute tension qui accelere en realite les ions est liee a l'extension rapide dans le vide d'un volume du flux magnetique autour du jet. Le plasma rapide est emis dans une distribution conique etroite a centre ouvert. La haute tension qui accelere les deuterons rapides accelere aussi des ions provenant des parois lorsque le plasma rapide bombarde une paroi de verre et provoque son evaporation. (author) [Spanish] El inyector coaxial utilizado en el experimento consiste en una fuente de dos plasmas diferentes, producidos por mecanismos separados. Se obtiene directamente un plasma de deuterio abundante y lento, (10{sup 7} cm/s) por interaccion del tipo j x B de la corriente del plasma radial y el campo magnetico de la corriente de alimentacion a lo largo del electrodo central. La perturbacion de la corriente se desplaza a traves del gas inyectado, hacia la boca del inyector, a razon de Tilde-Operator 2,5 x 10{sup 7} cm/s, almacenando energia detras de ella en forma de campo magnetico y de energia cinetica. El inyector, con su energia almacenada, actua como un generador electrico de baja impedancia y gran potencia, lanzando en el vacio situado mas alla de la boca del inyector, un chorro de corriente que es la fuente del plasma rapido ( Tilde-Operator 5 x 10{sup 17} deuterones, Tilde-Operator 10{sup 8} cm/s). El chorro de corriente y el plasma que

  19. Tritium and Autoradiography in Cell Biology; Tritium et Autoradiographie en Biologie Cellulaire; 0422 0440 0438 0414 ; El Tritio 0443 la Tecnica Autorradiografica en Citobiologia

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, J. H. [Departments of Botany and Zoology, Columbia University, New York, NY (United States)

    1962-02-15

    control of the sequence are being sought along with other related processes that involve the synthesis of chromosomal proteins and the other class of nucleic acids, ribonucleic acids. (author) [French] Du fait qu'il emet des rayons beta de faible energie, le tritium est l'isotope le plus utile pour l'autoradiographie a resolution elevee. Etant donne l'abondance relative de l'hydrogene dans la plupart des substances importantes du point de vue biologique et la periode radioactive assez courte du tritium, on peut marquer des constituants cellulaires a des activites specifiques qui sont souvent decelables au niveau intracellulaire a l'aide d'emulsions nucleaires. Les cellules sont fixees sur du verre par divers procedes cytologiques et, apres fixation, on applique directement a la surface de la cellule une emulsion photographique, humide ou fluide, qu'on laisse secher. Apres exposition, l'emulsion est developpee alors qu'elle se trouve encore en contact avec le specimen biologique. Lorsque la preparation, qui constitue un autoradiogramme, est examinee au microscope, on peut observer les structures cellulaires et l'emplacement de l'isotope, avec une resolution inferieure a un micron. On a pu ainsi determiner pendant deux ou trois divisions cellulaires la repartition de l'acide desoxyribonucleique (ADN) tritie de divers chromosomes. Ces etudes ont ete rendues possibles par la preparation de thymidine tritiee qui est un indicateur hautement selectif pour l'ADN et dont l'activite diminue rapidement lorsque l'on retire la cellule du milieu qui contient la thymidine marquee. On a egalement obtenu des renseignements sur le mecanisme de renouvellement de l'ADN, sur la structure et la reproduction des chromosomes, la cinetique de la division cellulaire et, plus recemment, sur les schemas et les phases de la reproduction des differents chromosomes d'un meme noyau ainsi que sur les differentes parties d'un meme chromosome. Dans tous les chromosomes etudies jusqu'a present on a constate

  20. Radioautography in the Study of Radioisotopically-Tagged Substances in Insect Control; L'autoradiographie dans l'etude de substances marquees au moy en de radioisotopes utilisees dans la lutte contre les insectes; Primenenie radioavtografii pri izuchenii substantsij, mechennykh radioizotopami, v bor'be s nasekomymi; La autorradiografia en el estudio de las sustancias marcadas con radioisotopos utilizadas en la lucha contra los insectos

    Energy Technology Data Exchange (ETDEWEB)

    Joftes, D. L. [New England Deaconess Hospital, Boston, MA (United States)

    1963-09-15

    marque en un point de la molecule tel que le radioindicateur demeure lie a la portion que l'on desire etudier. Une fois que l'insecticide a ete absorbe ou administre, on prepare les echantillons en appliquant les methodes histologiques courantes: fixation, enrobage, decoupage et pose sur lamelle de verre. Les tissus sont ensuite deparaffines et hydrates; ils sont alors prets pour l'application de l'emulsion nucleaire. Si les composes radioactifs se trouvent a l'etat soluble dans les tissus, on peut faire appel, aux methodes de dessication par congelation pour eviter toute perte ou tout mouvement du radioisotope* Des films a emulsion seche peuvent etre utilises pour ces preparations. La coloration peut etre faite avant ou apres application de l'emulsion nucleaire, selon la nature de la couleur desiree. Il est preferable, en general, que la coloration intervienne apres l'application et le traitement photographique de l'emulsion. Si l'on utilise des radioisotopes ayant une energie suffisante, on peut proceder a l'autoradiographie de plantes entieres ou de parties de plantes, et supprimer ainsi la preparation histologiquee; la partie a autoradiographier est simplement comprimee avec le film dans une presse ou dans tout autre appareil approprie. La methode la plus pratique pour appliquer les emulsions nucleaires aux preparations histologiques consiste a plonger l'echantillon dans une emulsion fondue et a nettoyer ensuite la partie inferieure de la lamelle. Les lamelles sont ensuite placees en chambre noire, dans une atmosphere seche et inerte, et exposees pendant une duree qui doit etre determinee empiriquement. Apres quoi, elles font l'objet d'un traitement photographique, sont soigneusement lavees et revetues d'une protection. On peut alors les etudier comme des echantillons histologiques normaux, avec le grossissement voulu. Un leger deplacement du foyer vers le haut permet de voir l'autoradiographie, que l'on peut ainsi facilement etudier en regard du tissu. Le memoire