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Sample records for mixed solid solution

  1. Studies on mixed metal oxides solid solutions as heterogeneous catalysts

    H. R. Arandiyan

    2009-03-01

    Full Text Available In this work, a series of perovskite-type mixed oxide LaMo xV1-xO3+δ powder catalysts (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1.0, with 0.5 < δ < 1.5, prepared by the sol-gel process and calcined at 750ºC, provide an attractive and effective alternative means of synthesizing materials with better control of morphology. Structures of resins obtained during the gel formation process by FT-IR spectroscopy and XRD analysis showed that all the LaMo xV1-xO3+δ samples are single phase perovskite-type solid solutions. The surface area (BET between 2.5 - 5.0 m²/g (x = 0.1 and 1.0 respectively increases with increasing Mo ratio in the samples. They show high purity, good chemical homogeneity, and lower calcinations temperatures as compared with the solid-state chemistry route. SEM coupled to EDS and thermogravimetric analysis/differential thermal analyses (TGA/DTA have been carried out in order to evaluate the homogeneity of the catalyst. Finally, the experimental studies show that the calcination temperature and Mo content exhibited a significant influence on catalytic activity. Among the LaMo xV1-xO3+δ samples, LaMo0.7V0.3O4.2 showed the best catalytic activity for the topic reaction and the best activity and stability for ethane reforming at 850ºC under 8 bar.

  2. Thermal expansion studies on uranium-neodymium mixed oxide solid solutions

    Panneerselvam, G.; Venkata Krishnan, R.; Antony, M.P.; Nagarajan, K.

    2012-01-01

    Uranium-Neodymium mixed oxides solid solutions (U 1-y Nd y ) O 2 (y=0.2-0.95) were prepared by combustion synthesis using citric acid as fuel. Structural characterization and computation of lattice parameter was carried out from room temperature X-ray diffraction measurements. Single-phase fluorite structure was observed up to y=0.80. For solid solutions with y>0.80 additional Nd 2 O 3 lines were visible

  3. Synthesis, characterization and thermal expansion studies on thorium-praseodymium mixed oxide solid solutions

    Panneerselvam, G.; Antony, M.P.; Srinivasan, T.G.; Vasudeva Rao, P.R.

    2010-01-01

    Full text: Thorium-praseodymium mixed oxide solid solutions containing 15, 25, 40 and 55 mole percent of praseodymia were synthesized by mixing the solutions of thorium nitrate in water and praseodymium oxide (Pr 6 O 11 ) in conc. HNO 3 . Subsequently, their hydroxides were co-precipitated by the addition of aqueous ammonia. Further the precipitate was dried at 50 deg C, calcined at 600 deg C for 4 hours and sintered at 1200 deg C for 6 h in air. X-ray diffraction measurements were performed for phase identification and lattice parameter derivation. Single-phase fluorite structure was observed for all the compositions. Bulk and theoretical densities of solid solutions were also determined by immersion and X-ray techniques. Thermal expansion coefficients and percentage linear thermal expansion of the solid solutions were determined using high temperature X-ray diffraction technique in the temperature range 300 to 1700 K for the first time. The room temperature lattice constants estimated for above compositions are 0.5578, 0.5565, 0.5545 and 0.5526 nm, respectively. The mean linear thermal expansion coefficients for the solid solutions are 15.48 x 10 -6 K -1 , 18.35 x 10 -6 K -1 , 22.65 x 10 -6 K -1 and 26.95 x 10 -6 K -1 , respectively. The percentage linear thermal expansions in this temperature range are 1.68, 1.89, 2.21 and 2.51 respectively. It is seen that the solid solutions are stable up to 1700 K. It is also seen that the effect and nature of the dopant are the important parameters influencing the thermal expansion of the ThO 2 . The lattice parameter of the solid solutions exhibited a decreasing trend with respect to praseodymia addition. The percentage linear thermal expansion of the solid solutions increases steadily with increasing temperature

  4. High-temperature superconductivity in solid solutions based on mixed yttrium and barium cuprate

    Bazuev, G.V.; Kirsanov, N.A.; Makarova, O.V.; Zubkov, V.G.; Shveikin, G.P.

    1990-01-01

    The discovery of high-temperature superconductivity (T c = 30-40 K) in mixed lanthanum and alkaline earth cuprates La 2-x M x CuO 4 , where M = Ba and Ca (1-3) stimulated an extensive search for new superconducting phases based on mixed oxides of these elements. The superconducting transition temperature T c in LnBa 2 Cu 3 O 7-z phases is practically independent of the REE and lies between 90-96 K. The crystal structure of superconducting YBa 2 Cu 3 O 7-z is similar to perovskite, has orthorhombic symmetry (4,5), and is related to the lanthanum barium cuprite tetragonal defect structure La 3 Ba 3 Cu 6 O 14.1 (8). A study of possible solid solutions (SS) based on YBa 2 Cu 3 O 7-z through iso- or heterovalent substitution for Y 3+ and Ba 2+ and of their electrical properties seems warranted. In the present work, the authors report the synthesis, x-ray diffraction study, and specific electric resistivity of SS Y 1-x M x (Ba 1-y M y ') 2 Cu 3 O 7-z , where M = La, Lu, Sc, In, K, Zr, and Ce and M' = Ca, Sr, Mg, K, and La

  5. Continuous mixing of solids

    Raouf, M.S.

    1963-01-01

    The most important literature on theoretical aspects of mixing solids was reviewed.

    Only when the mixed materials showed no segregation it was possible to analyse the mixing process quantitatively. In this case the mixture could be described by the 'χ' Square test. Longitudinal mixing could be

  6. Study of the solid solution formation in mixed oxides by X-ray diffraction

    Riella, H.G.

    1984-01-01

    A method to determine the plutonium distribution in mixed oxides - UO 2 /PuO 2 is described. The distribution function and the medium size of crystallite are obtained from the X-ray diffraction profile. Through the deconvolution by Fourier analysis, the X-ray diffraction profile is obtained without the influence of the difractrometer. Some experimental results for different samples of UO 2 -PuO 2 discussed. (Author) [pt

  7. Nanoscale Mixing of Soft Solids

    Choi, Soo-Hyung; Lee, Sangwoo; Soto, Haidy E.; Lodge, Timothy P.; Bates, Frank S.

    2011-01-01

    Assessing the state of mixing on the molecular scale in soft solids is challenging. Concentrated solutions of micelles formed by self-assembly of polystyrene-block-poly(ethylene-alt-propylene) (PS-PEP) diblock copolymers in squalane (C 30 H 62 ) adopt a body-centered cubic (bcc) lattice, with glassy PS cores. Utilizing small-angle neutron scattering (SANS) and isotopic labeling ( 1 H and 2 H (D) polystyrene blocks) in a contrast-matching solvent (a mixture of squalane and perdeuterated squalane), we demonstrate quantitatively the remarkable fact that a commercial mixer can create completely random mixtures of micelles with either normal, PS(H), or deuterium-labeled, PS(D), cores on a well-defined bcc lattice. The resulting SANS intensity is quantitatively modeled by the form factor of a single spherical core. These results demonstrate both the possibility of achieving complete nanoscale mixing in a soft solid and the use of SANS to quantify the randomness.

  8. Mixing of solids

    Weinekötter, Ralf

    2000-01-01

    This book is a welcome edition to the Particle Technology Series, formerly Powder Technology Series. It is the second book in the series which describes powder mixing and we make no excuses for that. The topic of powder mixing is fundamental to powder technology and is one which always aroses interest. That will not change. As powder products become more complex they will pose new mixing problems. The solutions lie in the intelligent use of equipment, an understanding of powder properties and a good knowledge of basic statistics. The authors of this book have presented those three ingredients with great clarity. The book is based on long experience and deep thought, I have enjoyed reading it and am pleased to recommend it. Delft University of Technology, NL-Delft, July 1999 Brian Scarlett, Series Editor IX VII Foreword to the English Edition In response to many enquiries from industrial organisations and institutes involved with the technology of processing bulk materials, we are pleased to present the Englis...

  9. Method for Predicting Solubilities of Solids in Mixed Solvents

    Ellegaard, Martin Dela; Abildskov, Jens; O'Connell, J. P.

    2009-01-01

    A method is presented for predicting solubilities of solid solutes in mixed solvents, based on excess Henry's law constants. The basis is statistical mechanical fluctuation solution theory for composition derivatives of solute/solvent infinite dilution activity coefficients. Suitable approximatio...

  10. Mixing of solids in different mixing devices

    INGRID BAUMAN, DUŠKA ´CURI ´C and MATIJA BOBAN ... whose main cause is the difference in particle size, density shape and resilience. ..... Gyebis J, Katai F 1990 Determination and randomness in mixing of particulate solids, Chem.

  11. Thermodynamic mixing properties of the UO{sub 2}–HfO{sub 2} solid solution: Density functional theory and Monte Carlo simulations

    Yuan, Ke, E-mail: keyuan@umich.edu [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Ewing, Rodney C. [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Becker, Udo [Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

    2015-03-15

    HfO{sub 2} is a neutron absorber and has been mechanically mixed with UO{sub 2} in nuclear fuel in order to control the core power distribution. During nuclear fission, the temperature at the center of the fuel pellet can reach above 1300 K, where hafnium may substitute uranium and form the binary solid solution of UO{sub 2}–HfO{sub 2}. UO{sub 2} adopts the cubic fluorite structure, but HfO{sub 2} can occur in monoclinic, tetragonal, and cubic structures. The distribution of Hf and U ions in the UO{sub 2}–HfO{sub 2} binary and its atomic structure influence the thermal conductivity and melting point of the fuel. However, experimental data on the UO{sub 2}–HfO{sub 2} binary are limited. Therefore, the enthalpies of mixing of the UO{sub 2}–HfO{sub 2} binary with three different structures were calculated in this study using density functional theory and subsequent Monte Carlo simulations. The free energy of mixing was obtained from thermodynamic integration of the enthalpy of mixing over temperature. From the ΔG of mixing, a phase diagram of the binary was obtained. The calculated UO{sub 2}–HfO{sub 2} binary forms extensive solid solution across the entire compositional range, but there are a variety of possible exsolution phenomena associated with the different HfO{sub 2} polymorphs. As the structure of the HfO{sub 2} end member adopts lower symmetry and becomes less similar to cubic UO{sub 2}, the miscibility gap of the phase diagram expands, accompanied by an increase in cell volume by 7–10% as the structure transforms from cubic to monoclinic. Close to the UO{sub 2} end member, which is relevant to the nuclear fuel, the isometric uranium-rich solid solutions exsolve as the fuel cools, and there is a tendency to form the monoclinic hafnium-rich phase in the matrix of the isometric, uranium-rich solid solution phase.

  12. Thermotransport in interstitial solid solutions

    Fogel'son, R.L.

    1982-01-01

    On the basis of literature data the problem of thermotransport of impurities (H, N, O, C) in interstitial solid solutions is considered. It is shown that from experimental data on the thermotransport an important parameter of dissolved atoms can be found which characterizes atom state in these solutions-enthalpy of transport

  13. Pulse Jet Mixing Tests With Noncohesive Solids

    Meyer, Perry A.; Bamberger, Judith A.; Enderlin, Carl W.; Fort, James A.; Wells, Beric E.; Sundaram, S. K.; Scott, Paul A.; Minette, Michael J.; Smith, Gary L.; Burns, Carolyn A.; Greenwood, Margaret S.; Morgen, Gerald P.; Baer, Ellen BK; Snyder, Sandra F.; White, Michael K.; Piepel, Gregory F.; Amidan, Brett G.; Heredia-Langner, Alejandro

    2012-02-17

    This report summarizes results from pulse jet mixing (PJM) tests with noncohesive solids in Newtonian liquid. The tests were conducted during FY 2007 and 2008 to support the design of mixing systems for the Hanford Waste Treatment and Immobilization Plant (WTP). Tests were conducted at three geometric scales using noncohesive simulants, and the test data were used to develop models predicting two measures of mixing performance for full-scale WTP vessels. The models predict the cloud height (the height to which solids will be lifted by the PJM action) and the critical suspension velocity (the minimum velocity needed to ensure all solids are suspended off the floor, though not fully mixed). From the cloud height, the concentration of solids at the pump inlet can be estimated. The predicted critical suspension velocity for lifting all solids is not precisely the same as the mixing requirement for 'disturbing' a sufficient volume of solids, but the values will be similar and closely related. These predictive models were successfully benchmarked against larger scale tests and compared well with results from computational fluid dynamics simulations. The application of the models to assess mixing in WTP vessels is illustrated in examples for 13 distinct designs and selected operational conditions. The values selected for these examples are not final; thus, the estimates of performance should not be interpreted as final conclusions of design adequacy or inadequacy. However, this work does reveal that several vessels may require adjustments to design, operating features, or waste feed properties to ensure confidence in operation. The models described in this report will prove to be valuable engineering tools to evaluate options as designs are finalized for the WTP. Revision 1 refines data sets used for model development and summarizes models developed since the completion of Revision 0.

  14. Pulse Jet Mixing Tests With Noncohesive Solids

    Meyer, Perry A.; Bamberger, Judith A.; Enderlin, Carl W.; Fort, James A.; Wells, Beric E.; Sundaram, S. K.; Scott, Paul A.; Minette, Michael J.; Smith, Gary L.; Burns, Carolyn A.; Greenwood, Margaret S.; Morgen, Gerald P.; Baer, Ellen BK; Snyder, Sandra F.; White, Michael; Piepel, Gregory F.; Amidan, Brett G.; Heredia-Langner, Alejandro; Bailey, Sharon A.; Bower, John C.; Denslow, Kayte M.; Eakin, David E.; Elmore, Monte R.; Gauglitz, Phillip A.; Guzman, Anthony D.; Hatchell, Brian K.; Hopkins, Derek F.; Hurley, David E.; Johnson, Michael D.; Kirihara, Leslie J.; Lawler, Bruce D.; Loveland, Jesse S.; Mullen, O Dennis; Pekour, Mikhail S.; Peters, Timothy J.; Robinson, Peter J.; Russcher, Michael S.; Sande, Susan; Santoso, Christian; Shoemaker, Steven V.; Silva, Steve M.; Smith, Devin E.; Su, Yin-Fong; Toth, James J.; Wiberg, John D.; Yu, Xiao-Ying; Zuljevic, Nino

    2009-05-11

    This report summarizes results from pulse jet mixing (PJM) tests with noncohesive solids in Newtonian liquid conducted during FY 2007 and 2008 to support the design of mixing systems for the Hanford Waste Treatment and Immobilization Plant (WTP). Tests were conducted at three geometric scales using noncohesive simulants. The test data were used to independently develop mixing models that can be used to predict full-scale WTP vessel performance and to rate current WTP mixing system designs against two specific performance requirements. One requirement is to ensure that all solids have been disturbed during the mixing action, which is important to release gas from the solids. The second requirement is to maintain a suspended solids concentration below 20 weight percent at the pump inlet. The models predict the height to which solids will be lifted by the PJM action, and the minimum velocity needed to ensure all solids have been lifted from the floor. From the cloud height estimate we can calculate the concentration of solids at the pump inlet. The velocity needed to lift the solids is slightly more demanding than "disturbing" the solids, and is used as a surrogate for this metric. We applied the models to assess WTP mixing vessel performance with respect to the two perform¬ance requirements. Each mixing vessel was evaluated against these two criteria for two defined waste conditions. One of the wastes was defined by design limits and one was derived from Hanford waste characterization reports. The assessment predicts that three vessel types will satisfy the design criteria for all conditions evaluated. Seven vessel types will not satisfy the performance criteria used for any of the conditions evaluated. The remaining three vessel types provide varying assessments when the different particle characteristics are evaluated. The assessment predicts that three vessel types will satisfy the design criteria for all conditions evaluated. Seven vessel types will not satisfy

  15. Mercury removal from solid mixed waste

    Gates, D.D.; Morrissey, M.; Chava, K.K.; Chao, K.

    1994-01-01

    The removal of mercury from mixed wastes is an essential step in eliminating the temporary storage of large inventories of mixed waste throughout the Department of Energy (DOE) complex. Currently thermal treatment has been identified as a baseline technology and is being developed as part of the DOE Mixed Waste Integrated Program (MWIP). Since thermal treatment will not be applicable to all mercury containing mixed waste and the removal of mercury prior to thermal treatment may be desirable, laboratory studies have been initiated at Oak Ridge National Laboratory (ORNL) to develop alternative remediation technologies capable of removing mercury from certain mixed waste. This paper describes laboratory investigations of the KI/I 2 leaching processes to determine the applicability of this process to mercury containing solid mixed waste

  16. Wax Precipitation Modeled with Many Mixed Solid Phases

    Heidemann, Robert A.; Madsen, Jesper; Stenby, Erling Halfdan

    2005-01-01

    The behavior of the Coutinho UNIQUAC model for solid wax phases has been examined. The model can produce as many mixed solid phases as the number of waxy components. In binary mixtures, the solid rich in the lighter component contains little of the heavier component but the second phase shows sub......-temperature and low-temperature forms, are pure. Model calculations compare well with the data of Pauly et al. for C18 to C30 waxes precipitating from n-decane solutions. (C) 2004 American Institute of Chemical Engineers....

  17. Phase segregation in cerium-lanthanum solid solutions

    Belliere, V.; Joorst, G; Stephan, O; de Groot, FMF; Weckhuysen, BM

    2006-01-01

    Electron energy-loss spectroscopy (EELS) in combination with scanning transmission electron microscopy ( STEM) reveals that the La enrichment at the surface of cerium-lanthanum solid solutions is an averaged effect and that segregation occurs in a mixed oxide phase. This separation occurs within a

  18. Uranothorite solid solutions: From synthesis to dissolution

    Costin, Dan-Tiberiu

    2012-01-01

    USiO 4 coffinite appears as one of the potential phases formed in the back-end of the alteration of spent fuel, in reducing storage conditions. A study aiming to assess the thermodynamic data associated with coffinite through an approach based on the preparation of Th 1-x U x SiO 4 uranothorite solid solutions was then developed during this work. First, the preparation of uranothorite samples was successfully undertaken in hydrothermal conditions. However, the poly-phased samples systematically formed for x ≥ 0,2 underlined the kinetic hindering linked with the preparation of uranium-enriched samples, including coffinite end-member. Nevertheless, the characterization of the various samples led to confirm the formation of an ideal solid solution and allowed the constitution of a spectroscopic database. The purification of the samples was then performed by the means of different protocols based on physical (dispersion-centrifugation) or chemical (selective dissolution of secondary phases) methods. This latter led to a complete of the impurities (Th 1-y U y O 2 mixed oxide and amorphous silica) through successive washing steps in acid then basic media. Finally, dissolution experiments were undertaken on uranothorite samples (0 ≤ xexp. ≤ 0,5) and allowed pointing out the influence of composition, pH and temperature on the normalized dissolution rate of the compounds. Also, the associated thermodynamic data, such as activation energy, indicate that the reaction is controlled by surface reactions. Once the equilibrium is reached, the analogous solubility constants were determined for each composition studied, then allowing the extrapolation to coffinite value. It was then finally possible to conclude on the inversion of coffinitisation reaction with temperature. (author) [fr

  19. Synthesis, sintering and dissolution of thorium and uranium (IV) mixed oxide solid solutions: influence of the method of precursor preparation; Synthese, frittage et caracterisation de solutions solides d'oxydes mixtes de thorium et d'uranium (IV): influence de la methode de preparation du precurseur

    Hingant, N

    2008-12-15

    Mixed actinide dioxides are currently considered as potential fuels for the third and fourth generations of nuclear reactors. In this context, thorium-uranium (IV) dioxide solid solutions were studied as model compounds to underline the influence of the method of preparation on their physico-chemical properties. Two methods of synthesis, both based on the initial precipitation of oxalate precursors have been developed. The first consisted in the direct precipitation ('open' system) while the second involved hydrothermal conditions ('closed' system). The second method led to a significant improvement in the crystallization of the samples especially in the field of the increase of the grain size. In these conditions, the formation of a complete solid solution Th{sub 1-x}U{sub x}(C{sub 2}O{sub 4}){sub 2}.2H{sub 2}O was prepared between both end-members. Its crystal structure was also resolved. Whatever the initial method considered, these compounds led to the final dioxides after heating above 400 C. The various steps associated to this transformation, involving the dehydration of precursors then the decomposition of oxalate groups have been clarified. Moreover, the use of wet chemistry methods allowed to reduce the sintering temperature of the final thorium-uranium (IV) dioxide solid solutions. Whatever the method of preparation considered, dense samples (95% to 97% of the calculated value) were obtained after only 3 hours of heating at 1500 C. Additionally, the use of hydrothermal conditions significantly increased the grain size, leading to the reduction of the occurrence of the grain boundaries and of the global residual porosity. The significant improvement in the homogeneity of cations distribution in the samples was also highlighted. Finally, the chemical durability of thorium-uranium (IV) dioxide solid solutions was evaluated through the development of leaching tests in nitric acid. The optimized homogeneity especially in terms of the

  20. Radionuclide solubility control by solid solutions

    Brandt, F.; Klinkenberg, M.; Rozov, K.; Bosbach, D. [Forschungszentrum Juelich GmbH (Germany). Inst. of Energy and Climate Research - Nuclear Waste Management and Reactor Safety (IEK-6); Vinograd, V. [Frankfurt Univ. (Germany). Inst. of Geosciences

    2015-07-01

    The migration of radionuclides in the geosphere is to a large extend controlled by sorption processes onto minerals and colloids. On a molecular level, sorption phenomena involve surface complexation, ion exchange as well as solid solution formation. The formation of solid solutions leads to the structural incorporation of radionuclides in a host structure. Such solid solutions are ubiquitous in natural systems - most minerals in nature are atomistic mixtures of elements rather than pure compounds because their formation leads to a thermodynamically more stable situation compared to the formation of pure compounds. However, due to a lack of reliable data for the expected scenario at close-to equilibrium conditions, solid solution systems have so far not been considered in long-term safety assessments for nuclear waste repositories. In recent years, various solid-solution aqueous solution systems have been studied. Here we present state-of-the art results regarding the formation of (Ra,Ba)SO{sub 4} solid solutions. In some scenarios describing a waste repository system for spent nuclear fuel in crystalline rocks {sup 226}Ra dominates the radiological impact to the environment associated with the potential release of radionuclides from the repository in the future. The solubility of Ra in equilibrium with (Ra,Ba)SO{sub 4} is much lower than the one calculated with RaSO{sub 4} as solubility limiting phase. Especially, the available literature data for the interaction parameter W{sub BaRa}, which describes the non-ideality of the solid solution, vary by about one order of magnitude (Zhu, 2004; Curti et al., 2010). The final {sup 226}Ra concentration in this system is extremely sensitive to the amount of barite, the difference in the solubility products of the end-member phases, and the degree of non-ideality of the solid solution phase. Here, we have enhanced the fundamental understanding regarding (1) the thermodynamics of (Ra,Ba)SO{sub 4} solid solutions and (2) the

  1. Solid-soluted content of cerium in solid solution of sphene

    Zhao Wei; Teng Yuancheng; Li Yuxiang; Ren Xuetan; Huang Junjun

    2010-01-01

    The sphene solid solution was synthesized by solid-state method,with calcium carbonate, silica, titanium dioxide, cerium oxalate and alumina as raw materials. The solid-soluted content of cerium in sphene was researched by means of X-ray diffraction (XRD), backscattering scanning electron microscopy (BSE), energy dispersive spectroscopy (EDS) and so on. The influence of A l3+ ion introduction to sphene on the solid-soluted content of cerium in sphene solid solution was studied. The results indicate that when introducing Al 3+ to sphene as electrovalence compensation, Ce 4+ could be well solidified to Ca 1-x Ce x Ti 1-2x A l2x SiO 5 , and the solid-soluted content is approximately 12.61%. With no electrovalence compensation, Ce 4+ could be solidified to Ca 1-2x Ce x TiSiO 5 , and the solid-soluted content is approximately 10.98%. The appropriate synthesis temperature of sphene solid solution is 1 260 degree C.(authors)

  2. Superhard Rhenium/Tungsten Diboride Solid Solutions.

    Lech, Andrew T; Turner, Christopher L; Lei, Jialin; Mohammadi, Reza; Tolbert, Sarah H; Kaner, Richard B

    2016-11-02

    Rhenium diboride (ReB 2 ), containing corrugated layers of covalently bonded boron, is a superhard metallic compound with a microhardness reaching as high as 40.5 GPa (under an applied load of 0.49 N). Tungsten diboride (WB 2 ), which takes a structural hybrid between that of ReB 2 and AlB 2 , where half of the boron layers are planar (as in AlB 2 ) and half are corrugated (as in ReB 2 ), has been shown not to be superhard. Here, we demonstrate that the ReB 2 -type structure can be maintained for solid solutions of tungsten in ReB 2 with tungsten content up to a surprisingly large limit of nearly 50 atom %. The lattice parameters for the solid solutions linearly increase along both the a- and c-axes with increasing tungsten content, as evaluated by powder X-ray and neutron diffraction. From micro- and nanoindentation hardness testing, all of the compositions within the range of 0-48 atom % W are superhard, and the bulk modulus of the 48 atom % solid solution is nearly identical to that of pure ReB 2 . These results further indicate that ReB 2 -structured compounds are superhard, as has been predicted from first-principles calculations, and may warrant further studies into additional solid solutions or ternary compounds taking this structure type.

  3. Photochemical oxidation: A solution for the mixed waste dilemma

    Prellberg, J.W.; Thornton, L.M.; Cheuvront, D.A. [Vulcan Peroxidation Systems, Inc., Tucson, AZ (United States)] [and others

    1995-12-31

    Numerous technologies are available to remove organic contamination from water or wastewater. A variety of techniques also exist that are used to neutralize radioactive waste. However, few technologies can satisfactorily address the treatment of mixed organic/radioactive waste without creating unacceptable secondary waste products or resulting in extremely high treatment costs. An innovative solution to the mixed waste problem is on-site photochemical oxidation. Liquid-phase photochemical oxidation has a long- standing history of successful application to the destruction of organic compounds. By using photochemical oxidation, the organic contaminants are destroyed on-site leaving the water, with radionuclides, that can be reused or disposed of as appropriate. This technology offers advantages that include zero air emissions, no solid or liquid waste formation, and relatively low treatment cost. Discussion of the photochemical process will be described, and several case histories from recent design testing, including cost analyses for the resulting full-scale installations, will be presented as examples.

  4. Assessment of LANL solid low-level mixed waste documentation

    Jennrich, E.A.; Lund, D.M.; Davis, K.D.; Hoevemeyer, S.S.

    1991-04-01

    DOE Order 5820.2A requires that a system performance assessment be conducted to assure efficient and compliant management of all radioactive waste. The objective of this report is to determine the present status of the Radioactive Waste Operations Section and the Chemical Waste Operations Section capabilities regarding preparation and maintenance of appropriate criteria, plans, and procedures. Additionally, a comparison is made which identifies areas where these documents are not presently in existence or being fully implemented. The documents being assessed in this report are: Solid Low-Level Mixed Waste Acceptance Criteria, Solid Low-Level Mixed Waste Characterization Plan, Solid Low-Level Mixed waste Certification Plan, Solid Low-Level Mixed Waste Acceptance Procedures, Solid Low-Level Mixed Waste characterization Procedures, Solid Low-Level Mixed Waste Certification Procedures, Solid Low-Level Mixed Waste Training Procedures, and Solid Low-Level Mixed Waste Recordkeeping Requirements. This report compares the current status of preparation and implementation, by the Radioactive Waste Operations Section and the Chemical Waste Operations Section, of these documents to the requirements of DOE 5820.2A,. 40 CFR 260 to 270, and to recommended practice. Chapters 2 through 9 of the report presents the results of the comparison in tabular form for each of the documents being assessed, followed by narrative discussion of all areas which are perceived to be unsatisfactory or out of compliance with respect to the availability and content of the documents. The final subpart of each of the following chapters provides recommendations where documentation practices may be improved to achieve compliance or to follow the recommended practice

  5. Mixing of two solutions combined by gravity drainage.

    Leuptow, R M; Smith, K; Mockros, L F

    1995-01-01

    A variety of medical therapies require the mixing of solutions from two separate bags before use. One scenario for the mixing is to drain the solution from one bag into the other by gravity through a short connecting tube. The degree of mixing in the lower bag depends on the relative densities of the two solutions, the geometry of the two bags and the connecting tube, and the placement of the connecting tube. Solutions with densities differing by as much as 12% were mixed by draining the solution from an upper bag into a lower bag for a particular geometric configuration. The two solutions had different electrical conductivities, and the conductivity of the combined solution as it exited from the lower bag was used as a measure of the effectiveness of mixing. When the more dense solution was drained from the upper bag into the less dense solution in a lower bag, mixing was very effective. The incoming jet of high density solution entrained the low density solution. Flow visualization indicated that the incoming jet penetrated to the bottom of the lower bag, and resulting large vortical structures enhanced mixing. When the less dense solution was drained from the upper bag into the more dense solution in the lower bag mixing was less effective. The buoyancy force reduced the momentum of the incoming jet such that it did not penetrate to the bottom of the lower bag, resulting in stratification of the solutions.

  6. Synthesis of (U,Zr)C solid solutions under exothermic conditions

    Wang, L.L.; Moore, H.G.; Gladson, J.W.

    1993-01-01

    The reactions of forming (U,Zr)C solid solutions from their elemental components or similarly less stable reactants such as UC 2 are strongly exothermic due to the high stability of these solid solutions. A simple approach of utilizing this heat of formation energy to assist the solid solution reaction process is to intimately mix the less stable reactant powders and then pressed them into a compact. The compact is then heated to the ignition temperature of the reaction. The feasibility of this reaction method to synthesize (U,Zr)C solid solutions has been demonstrated in this study. The preliminary results also show that both the initial composition and the heating rate have a significant effect on the nature of the reaction process. As expected the degree of powder mixing was also found to affect the completeness of the reaction

  7. Mixing and solid suspension in a stirred precipitator

    Chang, T.P.

    1986-04-01

    Full-scale mixing and solid suspension studies have been conducted to determine the optimum agitator design for precipitators used in plutonium processing. Design considerations include the geometry of precipitator vessels, feed locations, flow patterns, and product requirements. Evaluations of various agitator designs are based on their capabilities: (1) to achieve uniform mixing of reactants in minimum time, (2) to suspend slurry uniformly throughout the vessel, and (3) to minimize power consumption without inducing air entrainment. Tests of full-scale agitator designs showed that significant improvements in mixing, solid suspension, and energy consumption were achieved

  8. Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition

    Nakayama, Hirokazu; Hayashi, Aki

    2014-01-01

    The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution...

  9. Thermodynamics of CoAl2O4-CoGa2O4 solid solutions

    Lilova, Kristina I.; Navrotsky, Alexandra; Melot, Brent C.; Seshadri, Ram

    2010-01-01

    CoAl 2 O 4 , CoGa 2 O 4 , and their solid solution Co(Ga z Al 1-z ) 2 O 4 have been studied using high temperature oxide melt solution calorimetry in molten 2PbO.B 2 O 3 at 973 K. There is an approximately linear correlation between lattice parameters, enthalpy of formation from oxides, and the Ga content. The experimental enthalpy of mixing is zero within experimental error. The cation distribution parameters are calculated using the O'Neill and Navrotsky thermodynamic model. The enthalpies of mixing calculated from these parameters are small and consistent with the calorimetric data. The entropies of mixing are calculated from site occupancies and compared to those for a random mixture of Ga and Al ions on octahedral site with all Co tetrahedral and for a completely random mixture of all cations on both sites. Despite a zero heat of mixing, the solid solution is not ideal in that activities do not obey Raoult's Law because of the more complex entropy of mixing. - Graphical abstract: Measured enthalpies of mixing of CoAl 2 O 4 -CoGa 2 O 4 solid solutions are close to zero but entropies of mixing reflect the complex cation distribution, so the system is not an ideal solution.

  10. Mixing of high density solution in vertical upward flow

    Kumamaru, Hiroshige; Hosogi, Nobuyoshi; Komada, Toshiaki; Fujiwara, Yoshiki

    1999-01-01

    Experimental and analytical studies have been performed in order to provide fundamental data and a numerical calculation model on the mixing of boric acid solution, injected from the standby liquid control system (SLCS), under a low natural circulation flow during an ATWS in a BWR. First, fundamental experiments on the mixing of high-density solution in vertically-upward water flow have been performed by using a small apparatus. Mixing patterns observed in the experiments have been classified to two groups, i.e. complete mixing (entrainment) and incomplete mixing (entrainment). In the complete mixing, the injected high-density solution is mixed (entrained) completely into the vertically-upward water flow. From the experiments, the minimum water flow rates in which the complete mixing (entrainment) is achieved have been obtained for various solution densities and solution injection rates. Secondly, two-dimensional numerical calculations have been performed. A continuity equation for total fluid, momentum equations in two directions and a continuity equation for solute are solved by using the finite difference method for discretization method and by following the MAC method for solution procedure. The calculations have predicted nearly the minimum water flow rate in which the complete mixing is achieved, while the calculations have been performed only for one combination of the solution density and solution injection rate until now. (author)

  11. Thermodynamic characteristics of systems with solid solutions composed of crystal hydrates of lanthanide and yttrium chlorides, at 250C. III. Systems of Roozeboom's type IV, with restricted solid solutions

    Sokolova, N.P.

    1983-01-01

    The values of the activity, the activity coefficients, the free energy of mixing and the excess free energy of mixing have been calculated for CeCl 3 -LnCl 3 -H 2 O systems (where Ln identical with Sm, Gd, Dy, Ho, Er, Y) containing solid solutions of types IV and IVa. It is shown that the stability of the solid solutions decreases with increasing difference between the radii of the cations of cerium and the second lanthanide, which enter into the composition of the components of the solid solutions. The factors determining the composition of a liquid solution corresponding to the eutonic point are specified

  12. End-Member Formulation of Solid Solutions and Reactive Transport

    Lichtner, Peter C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    A model for incorporating solid solutions into reactive transport equations is presented based on an end-member representation. Reactive transport equations are solved directly for the composition and bulk concentration of the solid solution. Reactions of a solid solution with an aqueous solution are formulated in terms of an overall stoichiometric reaction corresponding to a time-varying composition and exchange reactions, equivalent to reaction end-members. Reaction rates are treated kinetically using a transition state rate law for the overall reaction and a pseudo-kinetic rate law for exchange reactions. The composition of the solid solution at the onset of precipitation is assumed to correspond to the least soluble composition, equivalent to the composition at equilibrium. The stoichiometric saturation determines if the solid solution is super-saturated with respect to the aqueous solution. The method is implemented for a simple prototype batch reactor using Mathematica for a binary solid solution. Finally, the sensitivity of the results on the kinetic rate constant for a binary solid solution is investigated for reaction of an initially stoichiometric solid phase with an undersaturated aqueous solution.

  13. Gastric emptying of a physiologic mixed solid-liquid meal

    Fisher, R.S.; Malmud, L.S.; Bandini, P.; Rock, E.

    1982-05-01

    The purposes of this study were to use a noninvasive scintigraphic technique to measure gastric emptying of liquids and solids simultaneously, to study the interactions between emptying of the liquid and solid components of meals in normal subjects, and to employ dual isotope gastric scintigraphy to evaluate gastric emptying of liquids and solids in patients with clinical evidence of gastric outlet obstruction. The solid component of the test meal consisted of chicken liver, labeled in vivo with /sup 99m/Tc sulfur colloid, and the liquid component was water mixed with /sup 111/In DTPA. The rates of emptying were quantitated using a gamma camera on line to a digital computer. Twenty normal subjects were studied using this combined solid-liquid meal. Ten of them also ingested a liquid meal alone and ten a solid meal alone. Liquid emptied from the stomach significantly more rapidly than did solids. The emptying curve for liquids was exponential compared to a linear emptying curve for solids. The gastric emptying rate of the liquid component was slowed significantly by simultaneous ingestion of solids, but the emptying rate of solids was not affected by liquids. Several patients with clinical gastric outlet obstruction were evaluated. Both combined and selective abnormalities for gastric emptying of liquids and solids were demonstrated.

  14. Reaction paths and equilibrium end-points in solid-solution aqueous-solution systems

    Glynn, P.D.; Reardon, E.J.; Plummer, Niel; Busenberg, E.

    1990-01-01

    Equations are presented describing equilibrium in binary solid-solution aqueous-solution (SSAS) systems after a dissolution, precipitation, or recrystallization process, as a function of the composition and relative proportion of the initial phases. Equilibrium phase diagrams incorporating the concept of stoichiometric saturation are used to interpret possible reaction paths and to demonstrate relations between stoichiometric saturation, primary saturation, and thermodynamic equilibrium states. The concept of stoichiometric saturation is found useful in interpreting and putting limits on dissolution pathways, but there currently is no basis for possible application of this concept to the prediction and/ or understanding of precipitation processes. Previously published dissolution experiments for (Ba, Sr)SO4 and (Sr, Ca)C??O3orth. solids are interpreted using equilibrium phase diagrams. These studies show that stoichiometric saturation can control, or at least influence, initial congruent dissolution pathways. The results for (Sr, Ca)CO3orth. solids reveal that stoichiometric saturation can also control the initial stages of incongruent dissolution, despite the intrinsic instability of some of the initial solids. In contrast, recrystallisation experiments in the highly soluble KCl-KBr-H2O system demonstrate equilibrium. The excess free energy of mixing calculated for K(Cl, Br) solids is closely modeled by the relation GE = ??KBr??KClRT[a0 + a1(2??KBr-1)], where a0 is 1.40 ?? 0.02, a1, is -0.08 ?? 0.03 at 25??C, and ??KBr and ??KCl are the mole fractions of KBr and KCl in the solids. The phase diagram constructed using this fit reveals an alyotropic maximum located at ??KBr = 0.676 and at a total solubility product, ???? = [K+]([Cl-] + [Br-]) = 15.35. ?? 1990.

  15. Experimental and theoretical study of solid solution stability under irradiation

    Cauvin, Richard.

    1981-08-01

    The behavior of dilute alloys (Al-Zn, Al-Ag, Al-Si, Al-Ge and Al-Mg) under 1 MeV electron irradiation has been studied in a high voltage electron microscope. A phenomenon of homogeneous precipitation induced by irradiation in undersaturated solid solutions (Al-Zn, Al-Ag and Al-Si) has been discovered; the observed precipitates are either coherent or incoherent, but never associated with point defect sinks. The solubility limit is a function of irradiation temperature and flux; but, under irradiation, it does not behave as a true thermal solubility limit (without irradiation). The existing theories (kinetic or strictly thermodynamic) do not account for this phenomenon. It is shown that the irreversibility of the mutual recombination between trapped vacancies and mixed interstitials is the driving force of this homogeneous precipitation. Using a dilute solid solution model, we show that, under irradiation, the homogeneous stationary state, stable from a strictly thermodynamic point of view, can be unstable when the recombination reaction is taken into account. The solubility limit under irradiation is calculated with a nucleation-growth model taking account for this effect; it is proportional to the thermal solubility limit without irradiation. This model explains all the experimental observations [fr

  16. Radiation induced homogeneous precipitation in undersaturated solid-solutions

    Cauvin, Richard; Martin, Georges.

    1978-01-01

    The stability of various types of solid solutions under irradiation is studied. In this paper, observations made on AlZn solid solutions under 1 MeV electron irradiation are reported. Al-Zn was chosen as a prototype of solid solutions with a simple miscibility gap. It is shown that under appropriate irradiation conditions undersaturated AnZn solid solutions give rise to a homogeneous precipitation of coherent G.P. zones and of incoherent Zn precipitates the atomic volume of which is smaller than that of the matrix. We propose a more general treatment of solute concentration heterogeneities in solid solutions under irradiation and suggest how it might account for the nucleation of the observed phases. The growth of the observed precipitates is studied

  17. On calculation of lattice parameters of refractory metal solid solutions

    Barsukov, A.D.; Zhuravleva, A.D.; Pedos, A.A.

    1995-01-01

    Technique for calculating lattice periods of solid solutions is suggested. Experimental and calculation values of lattice periods of some solid solutions on the basis of refractory metals (V-Cr, Nb-Zr, Mo-W and other) are presented. Calculation error was correlated with experimental one. 7 refs.; 2 tabs

  18. Mixed Solutions of Electrical Energy Storage

    Chioncel Cristian Paul

    2012-01-01

    Full Text Available The paper presents electrical energy storage solutions using electricbatteries and supercapacitors powered from photovoltaic solarmodules, with possibilities of application in electric and hybrid vehicles.The future development of electric cars depends largely on electricalenergy storage solutions that should provide a higher range of roadand operating parameters comparable to those equipped with internalcombustion engines, that eliminate pollution.

  19. Mixing and combustion enhancement of Turbocharged Solid Propellant Ramjet

    Liu, Shichang; Li, Jiang; Zhu, Gen; Wang, Wei; Liu, Yang

    2018-02-01

    Turbocharged Solid Propellant Ramjet is a new concept engine that combines the advantages of both solid rocket ramjet and Air Turbo Rocket, with a wide operation envelope and high performance. There are three streams of the air, turbine-driving gas and augment gas to mix and combust in the afterburner, and the coaxial intake mode of the afterburner is disadvantageous to the mixing and combustion. Therefore, it is necessary to carry out mixing and combustion enhancement research. In this study, the numerical model of Turbocharged Solid Propellant Ramjet three-dimensional combustion flow field is established, and the numerical simulation of the mixing and combustion enhancement scheme is conducted from the aspects of head region intake mode to injection method in afterburner. The results show that by driving the compressed air to deflect inward and the turbine-driving gas to maintain strong rotation, radial and tangential momentum exchange of the two streams can be enhanced, thereby improving the efficiency of mixing and combustion in the afterburner. The method of injecting augment gas in the transverse direction and making sure the injection location is as close as possible to the head region is beneficial to improve the combustion efficiency. The outer combustion flow field of the afterburner is an oxidizer-rich environment, while the inner is a fuel-rich environment. To improve the efficiency of mixing and combustion, it is necessary to control the injection velocity of the augment gas to keep it in the oxygen-rich zone of the outer region. The numerical simulation for different flight conditions shows that the optimal mixing and combustion enhancement scheme can obtain high combustion efficiency and have excellent applicability in a wide working range.

  20. Thermal diffusivity of samarium-gadolinium zirconate solid solutions

    Pan, W.; Wan, C.L.; Xu, Q.; Wang, J.D.; Qu, Z.X.

    2007-01-01

    We synthesized samarium-gadolinium zirconate solid solutions and determined their thermal diffusivities, Young's moduli and thermal expansion coefficients, which are very important for their application in thermal barrier coatings. Samarium-gadolinium zirconate solid solutions have extremely low thermal diffusivity between 20 and 600 deg. C. The solid solutions have lower Young's moduli and higher thermal expansion coefficients than those of pure samarium and gadolinium zirconates. This combination of characteristics is promising for the application of samarium and gadolinium zirconates in gas turbines. The mechanism of phonon scattering by point defects is discussed

  1. SOLISOL-handling of solid solutions. Version 1.1

    Boerjesson, S.; Emren, A.

    1992-09-01

    SOLISOL is a C computer program designed to model geochemical reactions involving solid solutions. The program searches equilibrium concentrations of the components in the aqueous phase and the solid solution given by limited quantities of the solid solution components. The equilibrium code PHREEQE is used as a subprogram in SOLISOL. Subprograms external to PHREEQE extract information from PHREEQE results, take care of conserved properties, calculate solubilities and produce inputdata for PHREEQE. The essential idea in this process is to calculate solubilities for the components in terms of saturation indices, and give directions to PHREEQE on how to search for the equilibrium under those constraints. (au)

  2. The complex synthesis and solid state chemistry of ceria-lanthana solid solutions prepared via a hexamethylenetetramine precipitation

    Fleming, P.G.; Holmes, J.D.; Otway, D.J.; Morris, M.A.

    2011-01-01

    Mixed oxide solid solutions are becoming ever more commercially important across a range of applications. However, their synthesis can be problematical. Here, we show that ceria-lanthana solid solutions can be readily prepared via simple precipitation using hexamethylenetetramine. However, the solution chemistry can be complex, which results in the precipitated particles having a complex structure and morphology. Great care must be taken in both the synthesis and characterisation to quantify the complexity of the product. Even very high heat treatments were not able to produce highly homogeneous materials and X-ray diffractions reveals the non-equilibrium form of particles prepared in this way. Unexpected crystal structures are revealed including a new metastable cubic La 2 O 3 phase. - Graphical abstract: The suggested mechanism for the formation of dual fluorite phase particles, where Step 1 corresponds to room temperature aging, Step 2; heating the solution to 90 deg. C, Step 3; cooling of the solution to room temperature, Step 4; calcination to 500 deg. C, Step 5; calcination to 700 deg. C and Step 6; calcination to 1300 deg. C. The terminology of e.g. La 1-x Ce x (OH) 3 is used to indicate the formation of a mixed oxy-hydroxy participate rather than a definitive assignment of stoichiometry. Similarly, La 1-y Ce y O 2 only implies a mixed solid solution. Highlights: → Mol% of prepared Ce-La oxides did not follow that of reactant mol%. → Complex reaction pathway found to be dependent on metal solution concentrations. → At certain concentrations core shell particles were found to form. → A reaction model was produced based on cationic solubility. → Report lanthana solubility higher than previously reported in CeO 2 .

  3. Mixing of Process Heels, Process Solutions and Recycle Streams: Small-Scale Simulant

    Kaplan, D.I.

    2001-01-01

    The overall objective of this small-scale simulant mixing study was to identify the processes within the Hanford Site River Protection Project - Waste Treatment Plant (RPP-WTP) that may generate precipitates and to identify the types of precipitates formed. This information can be used to identify where mixtures of various solutions will cause precipitation of solids, potentially causing operational problems such as fouling equipment or increasing the amount of High Level Waste glass produced. Having this information will help guide protocols for flushing or draining tanks, mixing internal recycle streams, and mixing waste tank supernates. This report contains the discussion and thermodynamic chemical speciation modeling of the raw data

  4. Low temperature kinetics of In-Cd solid solution decomposition

    Pal-Val, P.P.; Pal-Val, L.N.; Ostapovets, A.A.; Vaněk, Přemysl

    2008-01-01

    Roč. 137, - (2008), s. 35-42 ISSN 1012-0394 Institutional research plan: CEZ:AV0Z10100520 Keywords : low temperatures * In-based alloys * solid solutions * isothermal structure instability * Young's modulus * electrical resistivity * phase diagrams Subject RIV: BM - Solid Matter Physics ; Magnetism http://www.scientific.net/3-908451-53-1/35/

  5. Synthesis and characterization of type solid solution in the binary ...

    We have investigated Bi2O3–Eu2O3 binary system by doping with Eu2O3 in the composition range from 1 to 10 mole% via solid state reactions and succeeded to stabilize -Bi2O3 ... Our experimental observations strongly suggested that oxygen deficiency type non-stoichiometry is present in doped type solid solutions.

  6. The thermodynamics and kinetics of interstitial solid solutions

    Silva, J.R.G. da.

    1976-04-01

    Studies of hydrogen metal systems where the hidrogen is disolved in a solid solution are presented. Particular items of interest are: the thermodynamics of the hydrogen-iron system; the solubility of hidrogen in super pure iron single crytals; the thermodinamic functions of hydrogen in solid solutions of Nb, Ta and V; and the solubility of hydrogen in α-manganese. The diffusion of carbon and nitrogen in BCC iron is also studied

  7. Thermodynamic properties of solid solutions in the system Ag2S–Ag2Se

    Pal’yanova, G.A.; Chudnenko, K.V.; Zhuravkova, T.V.

    2014-01-01

    We have summarized experimental data on the phase diagram of the system Ag 2 S–Ag 2 Se. Standard thermodynamic functions of four solid solutions in this system have been calculated using the model of regular and subregular solutions: a restricted fcc solid solution γ-Ag 2 S-Ag 2 S 1−x Se x (x 2 S–Ag 2 Se, monoclinic solid solution (α) from Ag 2 S to Ag 2 S 0.4 Se 0.6 , and orthorhombic solid solution (α) from Ag 2 S 0.3 Se 0.7 to the Ag 2 Se. G mix and S mix have been evaluated using the subregular model for asymmetric solution for the region Ag 2 S 0.4 Se 0.6 –Ag 2 S 0.3 Se 0.7 . The thermodynamic data can be used for modeling in complex natural systems and in matters of semiconductor materials

  8. Solid solution hardening in face centered binary alloys: Gliding statistics of a dislocation in random solid solution by atomistic simulation

    Patinet, S.

    2009-12-01

    The glide of edge and screw dislocation in solid solution is modeled through atomistic simulations in two model alloys of Ni(Al) and Al(Mg) described within the embedded atom method. Our approach is based on the study of the elementary interaction between dislocations and solutes to derive solid solution hardening of face centered cubic binary alloys. We identify the physical origins of the intensity and range of the interaction between a dislocation and a solute atom. The thermally activated crossing of a solute atom by a dislocation is studied at the atomistic scale. We show that hardening of edge and screw segments are similar. We develop a line tension model that reproduces quantitatively the atomistic calculations of the flow stress. We identify the universality class to which the dislocation depinning transition in solid solution belongs. (author)

  9. Mobilization and mixing of settled solids in horizontal storage tanks

    Cummins, R.L.

    1995-01-01

    Studies were conducted using submerged jets for the mobilization and mixing of settled solids to form a suspension that can easily be removed from storage tanks. These studies focus on the specific problems relating to horizontal, cylindrical storage tanks. Of primary consideration are the storage tanks located at the Oak Ridge National Laboratory which are used for the collection of remote-handled, radioactive liquid wastes. These wastes are in two phases. A layer of undissolved, settled solids varying from 2 to 4 feet in depth under a layer of supernate. Using a surrogate of the tank contents and an approximate 2/3 dimensional scale tank, tests were performed to determine the optimum design and location of suction and discharge nozzles as well as the minimum discharge velocity required to achieve complete mobilization of the solids in the tank

  10. Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition.

    Nakayama, Hirokazu; Hayashi, Aki

    2014-07-30

    The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution. However, no intercalation was achieved for sorbic acid. Although intercalation of sorbate and aspartate into chloride-type layered double hydroxide was possible, the uptakes for these intercalation compounds were lower than those obtained using nitrate-type layered double hydroxide. The intercalation under solid condition could be achieved to the same extent as for ion-exchange reaction in aqueous solution, and the reactivity was similar to that observed in aqueous solution. This method will enable the encapsulation of acidic drug in layered double hydroxide as nano level simply by mixing both solids.

  11. Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition

    Hirokazu Nakayama

    2014-07-01

    Full Text Available The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution. However, no intercalation was achieved for sorbic acid. Although intercalation of sorbate and aspartate into chloride-type layered double hydroxide was possible, the uptakes for these intercalation compounds were lower than those obtained using nitrate-type layered double hydroxide. The intercalation under solid condition could be achieved to the same extent as for ion-exchange reaction in aqueous solution, and the reactivity was similar to that observed in aqueous solution. This method will enable the encapsulation of acidic drug in layered double hydroxide as nano level simply by mixing both solids.

  12. On Analytic Solution of resonant Mixing for Solar Neutrino Oscillations

    Masatoshi, ITO; Takao, KANEKO; Masami, NAKAGAWA; Department of Physics, Meijo University; Department of Physics, Meijo University; Department of Physics, Meijo University

    1988-01-01

    Behavior of resonant mixing in matter-enhancing region for solar neutrino oscillation, the Mikheyev-Smirnov-Wolfenstein mechanism, is reanalyzed by means of an analytic treatment recently proposed. We give solutions in terms of confluent hypergeometric functions, which agree with "exact" solutions of coupled differential equations.

  13. Impact of chemistry on Standard High Solids Vessel Design mixing

    Poirier, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-03-02

    The plan for resolving technical issues regarding mixing performance within vessels of the Hanford Waste Treatment Plant Pretreatment Facility directs a chemical impact study to be performed. The vessels involved are those that will process higher (e.g., 5 wt % or more) concentrations of solids. The mixing equipment design for these vessels includes both pulse jet mixers (PJM) and air spargers. This study assesses the impact of feed chemistry on the effectiveness of PJM mixing in the Standard High Solids Vessel Design (SHSVD). The overall purpose of this study is to complement the Properties that Matter document in helping to establish an acceptable physical simulant for full-scale testing. The specific objectives for this study are (1) to identify the relevant properties and behavior of the in-process tank waste that control the performance of the system being tested, (2) to assess the solubility limits of key components that are likely to precipitate or crystallize due to PJM and sparger interaction with the waste feeds, (3) to evaluate the impact of waste chemistry on rheology and agglomeration, (4) to assess the impact of temperature on rheology and agglomeration, (5) to assess the impact of organic compounds on PJM mixing, and (6) to provide the technical basis for using a physical-rheological simulant rather than a physical-rheological-chemical simulant for full-scale vessel testing. Among the conclusions reached are the following: The primary impact of precipitation or crystallization of salts due to interactions between PJMs or spargers and waste feeds is to increase the insoluble solids concentration in the slurries, which will increase the slurry yield stress. Slurry yield stress is a function of pH, ionic strength, insoluble solids concentration, and particle size. Ionic strength and chemical composition can affect particle size. Changes in temperature can affect SHSVD mixing through its effect on properties such as viscosity, yield stress, solubility

  14. Features of solid solutions composition in magnesium with yttrium alloys

    Drits, M.E.; Rokhlin, L.L.; Tarytina, I.E.

    1983-01-01

    Additional data on features of yttrium solid solutions composition in magnesium in the course of their decomposition investigation in the case of aging are obtianed. The investigation has been carried out on the base of a binary magnesium-yttrium alloy the composition of which has been close to maximum solubility (at eutectic temperature) and magnesium-yttrium alloys additionally doped with zinc. It is shown that higher yttrium solubility in solid magnesium than it has been expected, issueing from the difference in atomic radii of these metals indicates electron yttrium-magnesium atoms interaction. In oversaturated magnesium-yttrium solid solutions at earlier decomposition stages Mg 3 Cd type ordering is observed. At aging temperatures up to 250 deg C and long exposures corresponding to highest strengthening in oversaturated magnesium yttrium solid solutions a rhombic crystal lattice phase with three symmetric orientations is formed

  15. Solid state synthesis, crystal growth and optical properties of urea and p-chloronitrobenzene solid solution

    Rai, R.N., E-mail: rn_rai@yahoo.co.in [Department of Chemistry, Centre of Advanced Study, Banaras Hindu University, Varanasi 221005 (India); Kant, Shiva; Reddi, R.S.B. [Department of Chemistry, Centre of Advanced Study, Banaras Hindu University, Varanasi 221005 (India); Ganesamoorthy, S. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India); Gupta, P.K. [Laser Materials Development & Devices Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

    2016-01-15

    Urea is an attractive material for frequency conversion of high power lasers to UV (for wavelength down to 190 nm), but its usage is hindered due to its hygroscopic nature, though there is no alternative organic NLO crystal which could be transparent up to 190 nm. The hygroscopic character of urea has been modified by making the solid solution (UCNB) of urea (U) and p-chloronitrobenzene (CNB). The formation of the solid solution of CNB in U is explained on the basis of phase diagram, powder XRD, FTIR, elemental analysis and single crystal XRD studies. The solubility of U, CNB and UCNB in ethanol solution is evaluated at different temperatures. Transparent single crystals of UCNB are grown from its saturated solution in ethanol. Optical properties e.g., second harmonic generation (SHG), refractive index and the band gap for UCNB crystal were measured and their values were compared with the parent compounds. Besides modification in hygroscopic nature, UCNB has also shown the higher SHG signal and mechanical hardness in comparison to urea crystal. - Highlights: • The hygroscopic character of urea was modified by making the solid solutionSolid solution formation is support by elemental, powder- and single crystal XRD • Crystal of solid solution has higher SHG signal and mechanical stability. • Refractive index and band gap of solid solution crystal have determined.

  16. Direct and indirect effects of radiation on polar solid solutions

    Ershov, V.G.; Gaponova, I.S.

    1982-01-01

    Radiation-chemical decomposition of a solute is due to the direct effect of ionizing radiation on it and also to its reaction with radical-ion products of radiolysis of the solution. At low temperature, the movement of the reagents is limited, and thus it is possible to isolate and evaluate the contribution of direct and indirect effects of radiation on the solute. The present paper is devoted to an investigation of the mechanism of formation of radicals from a solute (LiNO 2 ) in a polar solid solution (CH 3 OH) under the effect of γ-radiation

  17. Surface phase transitions in cu-based solid solutions

    Zhevnenko, S. N.; Chernyshikhin, S. V.

    2017-11-01

    We have measured surface energy in two-component Cu-based systems in H2 + Ar gas atmosphere. The experiments on solid Cu [Ag] and Cu [Co] solutions show presence of phase transitions on the surfaces. Isotherms of the surface energy have singularities (the minimum in the case of copper solid solutions with silver and the maximum in the case of solid solutions with cobalt). In both cases, the surface phase transitions cause deficiency of surface miscibility: formation of a monolayer (multilayer) (Cu-Ag) or of nanoscale particles (Cu-Co). At the same time, according to the volume phase diagrams, the concentration and temperature of the surface phase transitions correspond to the solid solution within the volume. The method permits determining the rate of diffusional creep in addition to the surface energy. The temperature and concentration dependence of the solid solutions' viscosity coefficient supports the fact of the surface phase transitions and provides insights into the diffusion properties of the transforming surfaces.

  18. Solute redistribution in dendritic solidification with diffusion in the solid

    Ganesan, S.; Poirier, D. R.

    1989-01-01

    An investigation of solute redistribution during dendritic solidification with diffusion in the solid has been performed using numerical techniques. The extent of diffusion is characterized by the instantaneous and average diffusion parameters. These parameters are functions of the diffusion Fourier number, the partition ratio and the fraction solid. Numerical results are presented as an approximate model, which is used to predict the average diffusion parameter and calculate the composition of the interdendritic liquid during solidification.

  19. Heterogeneous Ferroelectric Solid Solutions Phases and Domain States

    Topolov, Vitaly

    2012-01-01

    The book deals with perovskite-type ferroelectric solid solutions for modern materials science and applications, solving problems of complicated heterophase/domain structures near the morphotropic phase boundary and applications to various systems with morphotropic phases. In this book domain state–interface diagrams are presented for the interpretation of heterophase states in perovskite-type ferroelectric solid solutions. It allows to describe the stress relief in the presence of polydomain phases, the behavior of unit-cell parameters of coexisting phases and the effect of external electric fields. The novelty of the book consists in (i) the first systematization of data about heterophase states and their evolution in ferroelectric solid solutions (ii) the general interpretation of heterophase and domain structures at changing temperature, composition or electric field (iii) the complete analysis of interconnection domain structures, unit-cell parameters changes, heterophase structures and stress relief.

  20. The effects of additives on the microstructure and sinterability of molybdenum oxide - study of related solid solutions

    Kassem, M.

    2006-01-01

    This study focuses on the phase transformation induced during mixing a fixed quantity of MoO 3 with various concentration of V 2 O 5 , Bn 2 O 5 , Al 2 O 3 and pure aluminium. These concentrations are 2, 3, 4, 5, 10, 20, 40 and 50%. Employing several physical techniques such as x-ray powder diffraction, FTIR and DTA, different solid solution were identified. Also the compressibility and sintering of these solid solutions have been studied via the variation of the density of pellets prepared from these solid solutions (Author)

  1. Solid-state reaction in Fe/V multilayers by ion beam mixing with thermal annealing

    Borges, J.F.M.; Costa, M.I. da Jr.; Teixeira, S.R.; Cunha, J.B.M. da; Alves, M.C.M.

    2001-01-01

    We report a study on the structural and magnetic properties of iron-vanadium thin films, originally grown in multilayer form [Fe(20 A)/V(20 A)] 20 , and mixed by ion beam mixing (IBM) and a subsequent thermal treatment. The samples were structurally characterised by X-ray diffraction (XRD) in the θ-2θ geometry and X-ray absorption spectroscopy (XAS). The magnetic characterisation was made using conversion electron Moessbauer spectroscopy (CEMS). The XRD result for the as-deposited multilayer shows a high-degree crystallinity, while CEMS suggests abrupt interface, since no significant contribution from vanadium in iron is observed. After the IBM and thermal treatment, the results from XRD show an FeV solid solution indexed as a bcc-disordered structure (α phase). XAS structural results are consistent with the XRD observations. CEMS results show a magnetic moment reduction for mixed samples

  2. Analytical solution for the convectively-mixed atmospheric boundary layer

    Ouwersloot, H.G.; Vilà-Guerau de Arellano, J.

    2013-01-01

    Based on the prognostic equations of mixed-layer theory assuming a zeroth order jump at the entrainment zone, analytical solutions for the boundary-layer height evolution are derived with different degrees of accuracy. First, an exact implicit expression for the boundary-layer height for a situation

  3. First-Principles Modeling of ThO2 Solid Solutions with Oxides of Trivalent Cations

    Alexandrov, Vitaly; Asta, Mark; Gronbech-Jensen, Niels

    2010-03-01

    Solid solutions formed by doping ThO2 with oxides of trivalent cations, such as Y2O3 and La2O3, are suitable for solid electrolyte applications, similar to doped zirconia and ceria. ThO2 has also been gaining much attention as an alternative to UO2 in nuclear energy applications, the aforementioned trivalent cations being important fission products. In both cases the mixing energetics and short-range ordering/clustering are key to understanding structural and transport properties. Using first-principles atomistic calculations, we address intra- and intersublattice interactions for both cation and anion sublattices in ThO2-based fluorite-type solid solutions and compare the results with similar modeling studies for related trivalent-doped zirconia systems.

  4. Structure and high-piezoelectricity in lead oxide solid solutions

    Noheda, B.

    2002-01-01

    A review of the recent advances in the understanding of piezoelectricity in lead oxide solid solutions is presented, giving special attention to the structural aspects. It has now become clear that the very high electromechanical response in these materials is directly related to the existence of

  5. Dynamic Aspects of Solid Solution Cathodes for Electrochemical Power Sources

    Atlung, Sven; West, Keld; Jacobsen, Torben

    1979-01-01

    Battery systems based on alkali metal anodes and solid solution cathodes,i.e., cathodes based on the insertion of the alkali cation in a "host lattice,"show considerable promise for high energy density storage batteries. Thispaper discusses the interaction between battery requirements...

  6. Turbulent solutal convection and surface patterning in solid dissolution

    Sullivan, T.S.; Liu, Y.; Ecke, R.E.

    1996-01-01

    We describe experiments in which crystals of NaCl, KBr, and KCl are dissolved from below by aqueous solutions containing concentrations of the respective salts from zero concentration to near saturation. The solution near the solid-liquid interface is gravitationally unstable, producing turbulent hydrodynamic motion similar to thermal convection from a single surface cooled from above. The coupling of the fluid flow with the solid dissolution produces irregular patterns at the solid-liquid interface with a distribution of horizontal length scales. The dissolution mass flux and the pattern length scales are compared with a turbulent boundary layer model. Remarkable agreement is found, showing that the fluid motion controls both the dissolution rate and the interface patterning. copyright 1996 The American Physical Society

  7. The Role of Cohesive Particle Interactions on Solids Uniformity and Mobilization During Jet Mixing: Testing Recommendations

    Gauglitz, Phillip A.; Wells, Beric E.; Bamberger, Judith A.; Fort, James A.; Chun, Jaehun; Jenks, Jeromy WJ

    2010-04-01

    Radioactive waste that is currently stored in large underground tanks at the Hanford Site will be staged in selected double-shell tanks (DSTs) and then transferred to the Waste Treatment and Immobilization Plant (WTP). Before being transferred, the waste will be mixed, sampled, and characterized to determine if the waste composition and meets the waste feed specifications. Washington River Protection Solutions is conducting a Tank Mixing and Sampling Demonstration Program to determine the mixing effectiveness of the current baseline mixing system that uses two jet mixer pumps and the adequacy of the planned sampling method. The overall purpose of the demonstration program is to mitigate the technical risk associated with the mixing and sampling systems meeting the feed certification requirements for transferring waste to the WTP.The purpose of this report is to analyze existing data and evaluate whether scaled mixing tests with cohesive simulants are needed to meet the overall objectives of the small-scale mixing demonstration program. This evaluation will focus on estimating the role of cohesive particle interactions on various physical phenomena that occur in parts of the mixing process. A specific focus of the evaluation will be on the uniformity of suspended solids in the mixed region. Based on the evaluation presented in this report and the absence of definitive studies, the recommendation is to conduct scaled mixing tests with cohesive particles and augment the initial testing with non-cohesive particles. In addition, planning for the quantitative tests would benefit from having test results from some scoping experiments that would provide results on the general behavior when cohesive inter-particle forces are important.

  8. Hydrothermal crystallization of zirconia and zirconia solid solutions

    Pyda, W.; Haberko, K.; Bucko, M.M.

    1991-01-01

    Zirconia as well as yttria-zirconia and calcia-zirconia solid-solution powders were crystallized under hydrothermal conditions from (co)precipitated hydroxides. The morphology of the power particles is strongly dependent on the crystallization conditions. The powders crystallized in a water solution of Na, K, and Li hydroxides show elongated particles of much larger sizes than those which result from the process carried out in pure water or a water solution of Na, K, or Li chlorides. The shapes of the latter particles are isometric. In this paper the growth mechanism of the elongated particles is suggested

  9. Current state in adsorption from multicomponent solutions of nonelectrolytes on solids

    Borowko, M.; Jaroniec, M.

    1983-01-01

    This paper surveys the research carried out on the adsorption from multicomponent liquid mixtures of nonelectrolytes on solids with emphasis on the work performed by the authors. The consistent theoretical treatment of adsorption from concentrated and dilute multicomponent solutions and its application to the liquid adsorption chromatography with the mixed mobile phase are presented. This treatment involved nonideality of the bulk and surface phases, energetic heterogeneity of the adsorbent surface and it may be extended to multilayer adsorption from solutions. The multicomponent liquid/solid adsorption systems, studied experimentally, are reviewed. Many of them have been examined by means of the equations derived for liquid adsorption on heterogeneous surfaces. These studies are summarized in this paper. Moreover, the model studies illustrating the influence of solution nonideality and adsorbent heterogeneity on the excess adsorption isotherms and the distribution coefficient are discussed. (orig.)

  10. Local structure of Th1-xMO2 solid solutions (M = U, Pu)

    Hubert, S.; Heisbourg, G.; Moisy, Ph.; Dacheux, N.; Purans, J.E.

    2004-01-01

    X-ray absorption spectroscopy of Th 1-x U x O 2 and Th 1-x Pu x O 2 solid solutions was carried out on the Th, U L 3 -edges, and Pu L 3 edge to study the local structure environment of actinide mixed oxides. Various compositions of Th 1-x M x O 2 solid solutions have been prepared through the coprecipitation of the mixed oxalates from chloride or nitrate solutions: x = 0.11, 0.24, 0.37, 0.53, 0.67, 0.81, 0.91 and 1 for Th 1-x U x O 2 , and x = 0.13, 0.32, 0.66 and 1 for Th 1-x Pu x O 2 . They were characterized using X- ray diffraction. XRD analysis allowed to confirm that the variation of the lattice parameters varies linearly with the composition between the end members, suggesting that the atomic volume was conserved regardless of the details of the local distortions of the lattice, following the Vegard's law. Extending X-ray absorption fine structure (EXAFS) provides a direct characterization of the local distortions present in solid solutions. We found that opposite to the lattice parameter obtained by XRD, the interatomic distances given by EXAFS do not follow completely to neither the Vegard's law nor the virtual crystal approximation (VCA). However, the average lattice parameter obtained from EXAFS data for the first and the second shells agrees well with the one calculated from XRD data. (authors)

  11. Experimental solid state NMR of gas hydrates : problems and solutions

    Moudrakovski, I.; Lu, H.; Ripmeester, J. [National Research Council of Canada, Ottawa, ON (Canada). Steacie Inst. for Molecular Sciences; Kumar, R.; Susilo, R. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemical and Biological Engineering; Luzi, M. [GeoForschungsZentrum Potsdam, Potsdam (Germany)

    2008-07-01

    Solid State NMR is a suitable spectroscopic technique for hydrate research for several reasons, including its capability to distinguish between different structural types of hydrates, its quantitative nature and potential for both in-situ and time resolved experiments. This study illustrated the applications of solid state NMR for compositional and structural studies of clathrate hydrates, with particular emphasis on experimental techniques and potential ways to overcome technical difficulties. In order to use the method to its full capacity, some instrumental developments are needed to adapt it to the specific experimental requirements of hydrate studies, such as very low temperatures and high pressures. This presentation discussed the quantification of the Carbon-13 spectra with examples from natural and synthetic hydrates prepared from multi-component mixtures of hydrocarbons. The main approach used for the first two examples was Carbon-13 NMR with Magic Angle Spinning (MAS) at -100 degrees C. The detailed characterization of mixed hydrogen hydrates required low temperature hydrogen MAS. The quantification problems encountered during these experiments were also discussed. The purpose of these recent experimental developments was to prompt wider application of Solid State NMR in hydrate research. NMR proved to be a viable method for analyzing the composition and structure of multi-component mixed gas hydrates; characterizing natural gas hydrates; and, evaluating the formation conditions and properties of mixed hydrogen hydrates. The limitations of the method were highlighted and sensible choices of experimental conditions and techniques that ensure accurate results were discussed. 34 refs., 10 figs.

  12. Experimental Studies on Combustion Characteristics of Mixed Municipal Solid Waste

    Fan Jiang; Zhonggang Pan; Shi Liu; Haigang Wang

    2003-01-01

    In our country, municipal solid wastes (MSW) are always burnt in their original forms and only a few pretreatments are taken. Therefore it is vital to study the combustion characteristics of mixed waste. In this paper,thermogravimetric analysis and a lab scale fluidized bed facility were used as experimental means. The data in two different experimental systems were introduced and compared. It took MSW 3~3.5 rain to burn out in FB, but in thermogravimetric analyzer, the time is 20~25 min. It can be concluded that, in general, the behavior of a mixture of waste in TGA can be expressed by simple combination of individual components of the waste mixtures.Only minor deviations from the rule were observed. Yet, in Fluidized Bed, it was found that, for some mixtures,there was interference among the components during fluidized bed combustion.

  13. Photoelectrochemical properties of CdSesub(x)Tesub(1-x) semiconducting solid solutions

    Kolbasov, G.Ya.; Karpov, I.I.; Pavelets, A.M.; Khanat, L.N.

    1985-01-01

    Photoelectrochemical properties of polycrystalline films of solid solutions CdSesub(x)Tesub(1-x) at x=0.5-0.8 are studied. Films from 5 to 30 μm thickness had hexagonal or mixed cubic and hexogonal structures depending on the compositions. All compositions had the electron type of conductivity. Alkali solutions of Na 2 S and S were used as electrolyte. Polarization characteristics of the CdSesub(0.5)Tesub(0.5) photoelectrode, curves of spectral dependence of photo electrochemical current and of the changes of photo-e.m.f. on electrode potential are plotted

  14. Investigation of samarium solubility in the magnesium based solid solution

    Rokhlin, L.L.; Padezhnova, E.M.; Guzej, L.S.

    1976-01-01

    Electric resistance measurements and microscopic analysis were used to investigate the solubility of samarium in a magnesium-based solid solution. The constitutional diagram Mg-Sm on the magnesium side is of an eutectic type with the temperature of the eutectic transformation of 542 deg C. Samarium is partly soluble in solid magnesium, the less so, the lower is the temperature. The maximum solubility of samarium in magnesium (at the eutectic transformation point) is 5.8 % by mass (0.99 at. %). At 200 deg C, the solubility of samarium in magnesium is 0.4 % by mass (0.063 at. %)

  15. Dislocation cross-slip in fcc solid solution alloys

    Nöhring, Wolfram Georg; Curtin, W.A.

    2017-01-01

    Cross-slip is a fundamental process of screw dislocation motion and plays an important role in the evolution of work hardening and dislocation structuring in metals. Cross-slip has been widely studied in pure FCC metals but rarely in FCC solid solutions. Here, the cross-slip transition path in solid solutions is calculated using atomistic methods for three representative systems of Ni-Al, Cu-Ni and Al-Mg over a range of solute concentrations. Studies using both true random alloys and their corresponding average-alloy counterparts allow for the independent assessment of the roles of (i) fluctuations in the spatial solute distribution in the true random alloy randomness and (ii) average alloy properties such as stacking fault energy. The results show that the solute fluctuations dominate the activation energy barrier, i.e. there are large sample-to-sample variations around the average activation barrier. The variations in activation barrier correlate linearly with the energy difference between the initial and final states. The distribution of this energy difference can be computed analytically in terms of the solute/dislocation interaction energies. Thus, the distribution of cross-slip activation energies can be accurately determined from a parameter-free analytic model. The implications of the statistical distribution of activation energies on the rate of cross-slip in real alloys are then identified.

  16. A multigrid solution method for mixed hybrid finite elements

    Schmid, W. [Universitaet Augsburg (Germany)

    1996-12-31

    We consider the multigrid solution of linear equations arising within the discretization of elliptic second order boundary value problems of the form by mixed hybrid finite elements. Using the equivalence of mixed hybrid finite elements and non-conforming nodal finite elements, we construct a multigrid scheme for the corresponding non-conforming finite elements, and, by this equivalence, for the mixed hybrid finite elements, following guidelines from Arbogast/Chen. For a rectangular triangulation of the computational domain, this non-conforming schemes are the so-called nodal finite elements. We explicitly construct prolongation and restriction operators for this type of non-conforming finite elements. We discuss the use of plain multigrid and the multilevel-preconditioned cg-method and compare their efficiency in numerical tests.

  17. Lipschitz Regularity of Solutions for Mixed Integro-Differential Equations

    Barles, Guy; Chasseigne, Emmanuel; Ciomaga, Adina; Imbert, Cyril

    2011-01-01

    We establish new Hoelder and Lipschitz estimates for viscosity solutions of a large class of elliptic and parabolic nonlinear integro-differential equations, by the classical Ishii-Lions's method. We thus extend the Hoelder regularity results recently obtained by Barles, Chasseigne and Imbert (2011). In addition, we deal with a new class of nonlocal equations that we term mixed integro-differential equations. These equations are particularly interesting, as they are degenerate both in the loc...

  18. Advances on reverse strike co-precipitation method of uranium-plutonium mixed solutions

    Menghini, Jorge E.; Marchi, Daniel E.; Orosco, Edgardo H.; Greco, Luis

    2000-01-01

    The reverse strike coprecipitation of uranium-plutonium mixed solutions, is an alternative way to obtain MOX fuel pellets. Previous tests, carried out in the Alpha Laboratory, included a stabilization step for transforming 100 % of plutonium into Pu +4 . Therefore, the plutonium precipitated as Pu(OH) 4 . In this second step, the stabilization process was suppressed. In this way, besides Pu(OH) 4 , a part of the precipitated is composed of a mixed salt: AD(U,Pu). Then, a homogeneous solid solution is formed in the early steps of the process. The powders showed higher tap density, better performance during the pressing and lower sinterability than the powders obtained in previous tests. The advantageous and disadvantageous effects of the stabilization step are analyzed in this paper. (author)

  19. Solid solutions of hydrogen in niobium, molybdenum and their alloys

    Ishikawa, T.T.

    1981-01-01

    The solubility of hydrogen in niobium, molybdenum and niobium-molybdenum alloys with varying atomic fraction of molybdenum from 0.15 to 0.75 was measured on the temperature range of 673 0 K to 1273 0 k for one atmosphere hydrogen pressure. The experimental technique involved the saturation of the solvent metal or alloy with hydrogen, followed by quenching and analysis of the solid solution. The results obtained of hydrogen solubility are consistent with the quasi-regular model for the dilute interstitial solid solutions. The partial molar enthalpy and partial molar entropy in excess of the dissolved hydrogen atoms were calculated from data of solubility versus reciprocal doping temperature. The variation of the relative partial molar enthalpy of hydrogen dissolved in niobium-molybdenum alloys, with the increase of molybdenum content of the alloy was analized. (Author) [pt

  20. A decontamination system for chemical weapons agents using a liquid solution on a solid sorbent.

    Waysbort, Daniel; McGarvey, David J; Creasy, William R; Morrissey, Kevin M; Hendrickson, David M; Durst, H Dupont

    2009-01-30

    A decontamination system for chemical warfare agents was developed and tested that combines a liquid decontamination reagent solution with solid sorbent particles. The components have fewer safety and environmental concerns than traditional chlorine bleach-based products or highly caustic solutions. The liquid solution, based on Decon Greentrade mark, has hydrogen peroxide and a carbonate buffer as active ingredients. The best solid sorbents were found to be a copolymer of ethylene glycol dimethacrylate and n-lauryl methacrylate (Polytrap 6603 Adsorber); or an allyl methacrylate cross-linked polymer (Poly-Pore E200 Adsorber). These solids are human and environmentally friendly and are commonly used in cosmetics. The decontaminant system was tested for reactivity with pinacolyl methylphosphonofluoridate (Soman, GD), bis(2-chloroethyl)sulfide (Mustard, HD), and S-(2-diisopropylaminoethyl) O-ethyl methylphosphonothioate (VX) by using NMR Spectroscopy. Molybdate ion (MoO(4)(-2)) was added to the decontaminant to catalyze the oxidation of HD. The molybdate ion provided a color change from pink to white when the oxidizing capacity of the system was exhausted. The decontaminant was effective for ratios of agent to decontaminant of up to 1:50 for VX (t(1/2) decontamination solution were measured to show that the sorbent decreased the vapor concentration of GD. The E200 sorbent had the additional advantage of absorbing aqueous decontamination solution without the addition of an organic co-solvent such as isopropanol, but the rate depended strongly on mixing for HD.

  1. Mixed waste: An alternative solution. The utility perspective

    Seizert, R.D.

    1988-01-01

    The issue of mixed waste is one of significant interest to the utility industry. The interest is focused on the current regulatory scheme of dual regulation. A fundamental concern of the commercial nuclear utilities resulting from dual regulation is that there are currently no facilities in the US to dispose of mixed low-level radioactive and hazardous waste. The lack of available sites renders mixed waste an orphan, requiring generators of such material to store the waste on-site. This in turn causes commercial nuclear power plants to be subjected to the full gamut of Environmental Protection Agency (EPA) Resource Conservation and Recovery Act (RCRA) regulation in addition to the existing Nuclear Regulatory Commission (NRC) regulations. Superimposing dual regulatory schemes will have impacts which extend far beyond the mere management of mixed waste. Certainly the burdens, complexities and costs of complying with the overlapping regulatory schemes will not have a commensurate increase in protection from the real risks being addressed. For these reasons, the commercial nuclear utility industry is working toward an alternative solution which will protect the public health and the environment from all hazards of mixed waste and will minimize the impacts on both the regulators and the regulated community

  2. Magnetic clusters in ilmenite-hematite solid solutions

    Frandsen, Cathrine; Burton, B. P.; Rasmussen, Helge Kildahl

    2010-01-01

    We report the use of high-field 57Fe Mössbauer spectroscopy to resolve the magnetic ordering of ilmenite-hematite [xFeTiO3−(1−x)Fe2O3] solid solutions with x>0.5. We find that nanometer-sized hematite clusters exist within an ilmenite-like matrix. Although both phases are antiferromagnetically...

  3. Fabrication of nanocrystalline alloys Cu–Cr–Mo super satured solid solution by mechanical alloying

    Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Guzmán, D. [Departamento de Ingeniería en Metalurgia, Facultad de Ingeniería, Universidad de Atacama y Centro Regional de Investigación y Desarrollo Sustentable de Atacama (CRIDESAT), Av. Copayapu 485, Copiapó (Chile); Castro, F.; Martínez, V.; Cuevas, F. de las [Centro de Estudios e Investigaciones Técnicas de Gipuzkoa, Paseo de Manuel Lardizábal, N° 15, 20018 San Sebastián (Spain); Lascano, S. [Departamento de Ingeniería Mecánica, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Muthiah, T. [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile)

    2014-08-01

    This work discusses the extension of solid solubility of Cr and Mo in Cu processed by mechanical alloying. Three alloys processed, Cu–5Cr–5Mo, Cu–10Cr–10Mo and Cu–15Cr–15Mo (weight%) using a SPEX mill. Gibbs free energy of mixing values 10, 15 and 20 kJ mol{sup −1} were calculated for these three alloys respectively by using the Miedema's model. The crystallite size decreases and dislocation density increases when the milling time increases, so Gibbs free energy storage in powders increases by the presence of crystalline defects. The energy produced by crystallite boundaries and strain dislocations were estimated and compared with Gibbs free energy of mixing values. The energy storage values by the presence of crystalline defects were higher than Gibbs free energy of mixing at 120 h for Cu–5Cr–5Mo, 130 h for Cu–10Cr–10Mo and 150 h for Cu–15Cr–15Mo. During milling, crystalline defects are produced that increases the Gibbs free energy storage and thus the Gibbs free energy curves are moved upwards and hence the solubility limit changes. Therefore, the three alloys form solid solutions after these milling time, which are supported with the XRD results. - Highlights: • Extension of solid solution Cr and Mo in Cu achieved by mechanical alloying. • X-ray characterization of Cu–Cr–Mo system processed by mechanical alloying. • Thermodynamics analysis of formation of solid solution of the Cu–Cr–Mo system.

  4. X-Ray Characterization of Non-Equilibrium Solid Solutions

    Brown, A; Rosdahl, Oe

    1975-07-01

    The Rudman approach to composition line broadening in X-ray diffraction patterns, originally designed for the study of diffusion in alloys, is seen to provide a basis for characterizing inhomogeneous solid solutions. Limitations, imposed on this treatment when the cell dimensions of the primary components differ by less than 0.1 A, are attributable to experimental effects such as instrument broadening. These limitations can be overcome by a rigorous numerical treatment of the measured data. Thus, separate elimination of the Kalpha{sub 2} radiation component followed by iterative deconvolution are advocated for the recovery of the intrinsic broadening. This course of action is made possible chiefly through the availability of large, fast memory computers and primary data recorded in the form of a step scan on punched paper tape. The characteristics of inhomogeneous solid solutions made available by the above treatment are the identity of closely similar, solid solution phases, the frequency distribution curve for a chosen component, and the degree of homogeneity of the X-ray sample

  5. X-Ray Characterization of Non-Equilibrium Solid Solutions

    Brown, A.; Rosdahl, Oe.

    1975-01-01

    The Rudman approach to composition line broadening in X-ray diffraction patterns, originally designed for the study of diffusion in alloys, is seen to provide a basis for characterizing inhomogeneous solid solutions. Limitations, imposed on this treatment when the cell dimensions of the primary components differ by less than 0.1 A, are attributable to experimental effects such as instrument broadening. These limitations can be overcome by a rigorous numerical treatment of the measured data. Thus, separate elimination of the Kα 2 radiation component followed by iterative deconvolution are advocated for the recovery of the intrinsic broadening. This course of action is made possible chiefly through the availability of large, fast memory computers and primary data recorded in the form of a step scan on punched paper tape. The characteristics of inhomogeneous solid solutions made available by the above treatment are the identity of closely similar, solid solution phases, the frequency distribution curve for a chosen component, and the degree of homogeneity of the X-ray sample

  6. High temperature thermodynamics of H2 and D2 in titanium, and in dilute titanium oxygen solid solutions

    Dantzer, P.

    1983-01-01

    The Tian Calvet microcalorimetric method has been improved in order to determine ΔH-barsub(H)(D), the partial molar enthalpy of mixing of hydrogen (deuterium) in the Ti-H 2 (D 2 ) solid systems for compositions 0 2 solid solutions (y = (O/Ti)) at 745 K. The combined calorimetric and equilibrium method allows a precise evaluation of the partial molar entropies. The results of this study differ substantially from earlier published data. (author)

  7. Theromdynamics of carbon in nickel-based multicomponent solid solutions

    Bradley, D.J.

    1978-04-01

    The activity coefficient of carbon in nickel, nickel-titanium, nickel-titanium-chromium, nickel-titanium-molybdenum and nickel-titanium-molybdenum-chromium alloys has been measured at 900, 1100 and 1215 0 C. The results indicate that carbon obeys Henry's Law over the range studied (0 to 2 at. percent). The literature for the nickel-carbon and iron-carbon systems are reviewed and corrected. For the activity of carbon in iron as a function of composition, a new relationship based on re-evaluation of the thermodynamics of the CO/CO 2 equilibrium is proposed. Calculations using this relationship reproduce the data to within 2.5 percent, but the accuracy of the calibrating standards used by many investigators to analyze for carbon is at best 5 percent. This explains the lack of agreement between the many precise sets of data. The values of the activity coefficient of carbon in the various solid solutions are used to calculate a set of parameters for the Kohler-Kaufman equation. The calculations indicate that binary interaction energies are not sufficient to describe the thermodynamics of carbon in some of the nickel-based solid solutions. The results of previous workers for carbon in nickel-iron alloys are completely described by inclusion of ternary terms in the Kohler-Kaufman equation. Most of the carbon solid solution at high temperatures in nickel and nickel-titantium alloys precipitates from solution on quenching in water. The precipitate is composed of very small particles (greater than 2.5 nm) of elemental carbon. The results of some preliminary thermomigration experiments are discussed and recommendations for further work are presented

  8. Synthesis and characterization of solid solutions in ABCO 4 system

    Novoselov, A.; Zimina, G.; Komissarova, L.; Pajaczkowska, A.

    2006-01-01

    Formation of continuous solid solutions with a tetragonal structure of K 2NiF 4-type was investigated by direct solid-state synthesis, carbonate precipitations, the freeze-drying method and the Czochralski crystal growth technique. In the systems of SrLaAlO 4-CaLaAlO 4, SrNdAlO 4-CaNdAlO 4, SrPrAlO 4-CaPrAlO 4, SrLaAlO 4-SrLaGaO 4 and SrLaAlO 4-SrLaFeO 4 solid solutions are formed in the whole concentration range (0.0⩽ x⩽1.0) and in the systems of SrLaAlO 4-SrLaMnO 4 and SrLaAlO 4-SrLaCrO 4 in the limited compositional interval of (0.0⩽ x⩽0.20) and (0.0⩽ x⩽0.25), respectively, with composition dependency of lattice constants following Vegard's law.

  9. Thorium-d-metals compounds and solid solutions

    Chachkhiani, Z.B.; Chechernikov, V.I.; Chachkhiani, L.G.

    1986-01-01

    Thorium compounds with Fe, Co, Ni dependence of their magnetic properties on temperature, pressure and concentration of the second element are considered. Anomalous magnetic behaviour of alloys in the Th-Fe system is noted. Special attention is paid to compounds with CaCu 5 type hexagonal structure and their solid solutions. Th-Co-Ni specimens containing up to 25% Ni are ferromagnetics and the rest are paramagnetics. Specimens with 60% cobalt content do not display ferromagnetic properties up to 4.2 K. Hydrides of Th 7 M 3 H 30 type (M - Fe, Co, Ni) are also considered. Highly hydrogenized specimens (under high pressure) appear to be stronger ferromagnetics

  10. The X-ray electronic spectra of TiC-NbC solid solution

    Cherkashenko, V.M.; Ezhov, A.V.; Nazarova, S.Z.; Kurmaev, Eh.Z.; Nojmann, M.

    2001-01-01

    X-ray photoelectronic spectra of inner levels and valency lands in TiC-NbC solid solutions were studied. Results of combining TiL α -, NbL β2.15 -, CK α - X-ray emission spectra and photoelectronic spectra of valency bands in one energy scale in reference to the Fermi level were analyzed. It is shown that a change in crystal lattice parameters, as well as charge redistribution between titanium and niobium atoms, produce a strong effect on electronic structure formation in the mixed carbides mentioned [ru

  11. Np(V) carbonates in solid state and aqueous solution

    Meinrath, G.

    1994-01-01

    The solubility of NaNpO 2 CO 3 (s) in 0.1M perchlorate solution at 25 deg C in equilibrium with 1.0% CO 2 /N 2 atmosphere has been investigated as a function of pH/lg [CO 3 2- ]. The solid phase was found hexagonal with a=1008.1±0.3 pm and c=991.1±0.2 pm. A solubility product of lg Ksp(NaNpO 2 CO 3 ) = -10.22±0.02 and a formation constant of the first Np(V) carbonato species of lg β 01 = 4.52±0.02 was evaluated. For the dicarbonato species an upper limit of lg lg β 02 2 partial pressure gave evidence that carbonato species are prevailing in solutions at both 1% and 0.03% CO 2 partial pressures. (author) 26 refs.; 4 figs.; 3 tabs

  12. Multi-component solid solution alloys having high mixing entropy

    Bei, Hongbin

    2015-10-06

    A multi-component high-entropy alloy includes a composition selected from the following group: VNbTaTiMoWRe, VNbTaTiMoW, VNbTaTiMoRe, VNbTaTiWRe, VNbTaMoWRe, VNbTiMoWRe, VTaTiMoWRe, NbTaTiMoWRe, VNbTaTiMo, VNbTaTiW, VNbTaMoW, VNbTiMoW, VTaTiMoW, NbTaTiMoW, VNbTaTiRe, VNbTaMoRe, VNbTiMoRe, VTaTiMoRe, NbTaTiMoRe, VNbTaWRe, VNbTiWRe, VTaTiWRe, NbTaTiWRe, VNbMoWRe, VTaMoWRe, NbTaMoWRe, VTiMoWRe, NbTiMoWRe, TaTiMoWRe, wherein relative amounts of each element vary by no more than .+-.15 atomic %.

  13. The removal of mercury from solid mixed waste using chemical leaching processes

    Gates, D.D.; Chao, K.K.; Cameron, P.A.

    1995-07-01

    The focus of this research was to evaluate chemical leaching as a technique to treat soils, sediments, and glass contaminated with either elemental mercury or a combination of several mercury species. Potassium iodide/iodine solutions were investigated as chemical leaching agents for contaminated soils and sediments. Clean, synthetic soil material and surrogate storm sewer sediments contaminated with mercury were treated with KI/I 2 solutions. It was observed that these leaching solutions could reduce the mercury concentration in soil and sediments by 99.8%. Evaluation of selected posttreatment sediment samples revealed that leachable mercury levels in the treated solids exceeded RCRA requirements. The results of these studies suggest that KI/I 2 leaching is a treatment process that can be used to remove large quantities of mercury from contaminated soils and sediments and may be the only treatment required if treatment goals are established on Hg residual concentrations in solid matrices. Fluorescent bulbs were used to simulate mercury contaminated glass mixed waste. To achieve mercury contamination levels similar to those found in larger bulbs such as those used in DOE facilities a small amount of Hg was added to the crushed bulbs. The most effective agents for leaching mercury from the crushed fluorescent bulbs were KI/I 2 , NaOCl, and NaBr + acid. Radionuclide surrogates were added to both the EPA synthetic soil material and the crushed fluorescent bulbs to determine the fate of radionuclides following chemical leaching with the leaching agents determined to be the most promising. These experiments revealed that although over 98% of the dosed mercury solubilized and was found in the leaching solution, no Cerium was measured in the posttreatment leaching solution. This finding suggest that Uranium, for which Ce was used as a surrogate, would not solubilize during leaching of mercury contaminated soil or glass

  14. Existence of a solid solution from brucite to {beta}-Co(OH){sub 2}

    Giovannelli, F., E-mail: fabien.giovannelli@univ-tours.fr [LEMA, UMR 6157 CNRS - CEA, Universite Francois Rabelais, 15 rue de la chocolaterie, 41000 Blois (France); Delorme, F.; Autret-Lambert, C. [LEMA, UMR 6157 CNRS - CEA, Universite Francois Rabelais, 15 rue de la chocolaterie, 41000 Blois (France); Seron, A.; Jean-Prost, V. [BRGM, 3 Avenue Claude Guillemin, BP 36009, 45060 Orleans Cedex 2 (France)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer A solid solution exist between Mg(OH){sub 2} and {beta}-Co(OH){sub 2}. Black-Right-Pointing-Pointer Synthesis has been performed through an easy and fast coprecipitation route. Black-Right-Pointing-Pointer No long range-ordering of the cations occurs. -- Abstract: This study shows that between brucite (Mg(OH){sub 2}) and {beta}-Co(OH){sub 2}, all the compositions are possible. The solid solution Mg{sub 1-x}Co{sub x}(OH){sub 2} has been synthesized by an easy and fast coprecipitation route and characterized by XRD and TEM. Single phase powders have been obtained. The particles exhibit platelets morphology with a size close to one hundred nanometers. XRD analysis shows an evolution of the cell parameters when x increases and demonstrates that no ordering of the cations occurs. However, extra reflections on TEM electron diffraction patterns seem to indicate that local ordering can exist. The compounds issued from this solid solution could be good candidates as precursors in order to obtain Mg-Co mixed oxide with all possible cationic ratios.

  15. Existence of a solid solution from brucite to β-Co(OH)2

    Giovannelli, F.; Delorme, F.; Autret-Lambert, C.; Seron, A.; Jean-Prost, V.

    2012-01-01

    Highlights: ► A solid solution exist between Mg(OH) 2 and β-Co(OH) 2 . ► Synthesis has been performed through an easy and fast coprecipitation route. ► No long range-ordering of the cations occurs. -- Abstract: This study shows that between brucite (Mg(OH) 2 ) and β-Co(OH) 2 , all the compositions are possible. The solid solution Mg 1−x Co x (OH) 2 has been synthesized by an easy and fast coprecipitation route and characterized by XRD and TEM. Single phase powders have been obtained. The particles exhibit platelets morphology with a size close to one hundred nanometers. XRD analysis shows an evolution of the cell parameters when x increases and demonstrates that no ordering of the cations occurs. However, extra reflections on TEM electron diffraction patterns seem to indicate that local ordering can exist. The compounds issued from this solid solution could be good candidates as precursors in order to obtain Mg–Co mixed oxide with all possible cationic ratios.

  16. Phase stability in wear-induced supersaturated Al-Ti solid solution

    Watanabe, Y.; Yokoyama, K. [Dept. of Functional Machinery Mechanics Shinshu Univ., Ueda (Japan); Hosoda, H. [Precision and Intelligence Lab., Tokyo Inst. of Tech., Nagatsuta, Midori-ku, Yokohama (Japan)

    2002-07-01

    Al-Ti supersaturated solid solutions were introduced by wear testing and the rapid quenching of an Al/Al{sub 3}Ti composite (part of an Al/Al{sub 3}Ti functionally graded material) that was fabricated using the centrifugal method. The phase stability of the supersaturated solid solution was studied through systematic annealing of the supersaturated solid solution. It was found that the Al-Ti supersaturated solid solution decomposed into Al and Al{sub 3}Ti intermetallic compound phases during the heat treatment. The Al-Ti supersaturated solid solutions fabricated were, therefore, not an equilibrium phase, and thus decomposed into the equilibrium phases during heat treatment. It was also found that heat treatment leads to a significant hardness increase for the Al-Ti supersaturated solid solution. Finally, it was concluded that formation of the wear-induced supersaturated solid solution layer was a result of severe plastic deformation. (orig.)

  17. All-proportional solid-solution Rh–Pd–Pt alloy nanoparticles by femtosecond laser irradiation of aqueous solution with surfactant

    Sarker, Md. Samiul Islam, E-mail: samiul-phy@ru.ac.bd; Nakamura, Takahiro; Sato, Shunichi [Tohoku University, Institute of Multidisciplinary Research for Advanced Materials (Japan)

    2015-06-15

    Formation of Rh–Pd–Pt solid-solution alloy nanoparticles (NPs) by femtosecond laser irradiation of aqueous solution in the presence of polyvinylpyrrolidone (PVP) or citrate as a stabilizer was studied. It was found that the addition of surfactant (PVP or citrate) significantly contributed to reduce the mean size of the particles to 3 nm for PVP and 10 nm for citrate, which was much smaller than that of the particles fabricated without any surfactants (20 nm), and improved the dispersion state as well as the colloidal stability. The solid-solution formation of the Rh–Pd–Pt alloy NPs was confirmed by the XRD results that the diffraction pattern was a single peak, which was found between the positions corresponding to each pure Rh, Pd, and Pt NPs. Moreover, all the elements were homogeneously distributed in every particle by STEM-EDS elemental mapping, strongly indicating the formation of homogeneous solid-solution alloy. Although the Rh–Pd–Pt alloy NPs fabricated with PVP was found to be Pt rich by EDS observation, the composition of NPs fabricated with citrate almost exactly preserved the feeding ratio of ions in the mixed solution. To our best knowledge, these results demonstrated for the first time, the formation of all-proportional solid-solution Rh–Pd–Pt alloy NPs with well size control.

  18. Radiation induced homogeneous precipitation in undersaturated solid-solutions

    Cauvin, R.; Martin, G.

    1979-01-01

    A TEM study of 1 MeV electron irradiated Al 1.9 at% Zn solid solution shows that Zn precipitates form, under irradiation at temperatures well above the Zn solvus temperature outside irradiation. The corresponding upward shift of this temperature is dose rate dependent. This new example of radiation-induced precipitation exhibits unexpected features, which are not accounted for by the available models: (1) no correlation exists between the location of the precipitates and that of the point defects sinks; (2) the precipitation of incoherent β-phase with atomic volume smaller than that of the matrix, and of coherent G.P. zones both occurs; (3) the size of the coherent β precipitates saturates at large dose. A general mechanism for solute concentration fluctuations under irradiation is proposed which qualitatively accounts for the formation of coherent G.P. zones and for the nucleation of solute clusters with more complex structures. A reanalysis of Russell's model (1977) for the growth of incoherent precipitates shows that it may qualitatively account for the observed behavior of the β phase precipitates. (Auth.)

  19. Diffuse neutron scattering study of metallic interstitial solid solutions

    Barberis, P.

    1991-10-01

    We studied two interstitial solid solutions (Ni-C(1at%) and Nb-O(2at%) and two stabilized zirconia (ZrO2-CaO(13.6mol%) and ZrO2-Y2O3(9.6mol%) by elastic diffuse neutron scattering. We used polarized neutron scattering in the case of the ferromagnetic Ni-based sample, in order to determine the magnetic perturbation induced by the C atoms. Measurements were made on single crystals in the Laboratoire Leon Brillouin (CEA-CNRS, Saclay, France). An original algorithm to deconvolve time-of-flight spectra improved the separation between elastically and inelastically scattered intensities. In the case of metallic solutions, we used a simple non-linear model, assuming that interstitials are isolated and located in octahedral sites. Results are: - in both compounds, nearest neighbours are widely displaced away from the interstitial, while next nearest neighbours come slightly closer. - the large magnetic perturbation induced by carbon in Nickel decreases with increasing distance on the three first neighbour shells and is in good agreement with the total magnetization variation. - no chemical order between solute atoms could be evidenced. Stabilized zirconia exhibit a strong correlation between chemical order and the large displacements around vacancies and dopants. (Author). 132 refs., 38 figs., 13 tabs

  20. Solubility of jarosite solid solutions precipitated from acid mine waters, Iron Mountain, California

    Alpers, Charles N.; Nordstrom, D. Kirk; Ball, J.W.

    1989-01-01

    Because of the common occurrence of 15 to 25 mole percent hydronium substitution on the alkali site in jarosites, it is necessary to consider the hydronium content of jarosites in any attempt at rigorous evaluation of jarosite solubility or of the saturation state of natural waters with respect to jarosite. A Gibbs free energy of 3293.5±2.1 kJ mol-1 is recommended for a jarosite solid solution of composition K.77Na.03(H3O).20Fe3(SO4)2(OH)6. Solubility determinations for a wider range of natural and synthetic jarosite solid solutions will be necessary to quantify the binary and ternary mixing parameters in the (K-Na-H3O) system. In the absence of such studies, molar volume data for endmember minerals indicate that the K-H3O substitution in jarosite is probably closer to ideal mixing than either the Na-K or Na-H3O substitution.

  1. A decontamination system for chemical weapons agents using a liquid solution on a solid sorbent

    Waysbort, Daniel [Israel Institute for Biological Research, PO Box 19, Ness-Ziona 74100 (Israel); McGarvey, David J. [R and T Directorate, Edgewood Chemical and Biological Center (ECBC), Aberdeen Proving Ground-Edgewood Area, MD 21010 (United States)], E-mail: david.mcgarvey@us.army.mil; Creasy, William R.; Morrissey, Kevin M.; Hendrickson, David M. [SAIC, P.O. Box 68, Gunpowder Branch, Aberdeen Proving Ground, MD 21010 (United States); Durst, H. Dupont [R and T Directorate, Edgewood Chemical and Biological Center (ECBC), Aberdeen Proving Ground-Edgewood Area, MD 21010 (United States)

    2009-01-30

    A decontamination system for chemical warfare agents was developed and tested that combines a liquid decontamination reagent solution with solid sorbent particles. The components have fewer safety and environmental concerns than traditional chlorine bleach-based products or highly caustic solutions. The liquid solution, based on Decon Green{sup TM}, has hydrogen peroxide and a carbonate buffer as active ingredients. The best solid sorbents were found to be a copolymer of ethylene glycol dimethacrylate and n-lauryl methacrylate (Polytrap 6603 Adsorber); or an allyl methacrylate cross-linked polymer (Poly-Pore E200 Adsorber). These solids are human and environmentally friendly and are commonly used in cosmetics. The decontaminant system was tested for reactivity with pinacolyl methylphosphonofluoridate (Soman, GD), bis(2-chloroethyl)sulfide (Mustard, HD), and S-(2-diisopropylaminoethyl) O-ethyl methylphosphonothioate (VX) by using NMR Spectroscopy. Molybdate ion (MoO{sub 4}{sup -2}) was added to the decontaminant to catalyze the oxidation of HD. The molybdate ion provided a color change from pink to white when the oxidizing capacity of the system was exhausted. The decontaminant was effective for ratios of agent to decontaminant of up to 1:50 for VX (t{sub 1/2} {<=} 4 min), 1:10 for HD (t{sub 1/2} < 2 min with molybdate), and 1:10 for GD (t{sub 1/2} < 2 min). The vapor concentrations of GD above the dry sorbent and the sorbent with decontamination solution were measured to show that the sorbent decreased the vapor concentration of GD. The E200 sorbent had the additional advantage of absorbing aqueous decontamination solution without the addition of an organic co-solvent such as isopropanol, but the rate depended strongly on mixing for HD.

  2. A decontamination system for chemical weapons agents using a liquid solution on a solid sorbent

    Waysbort, Daniel; McGarvey, David J.; Creasy, William R.; Morrissey, Kevin M.; Hendrickson, David M.; Durst, H. Dupont

    2009-01-01

    A decontamination system for chemical warfare agents was developed and tested that combines a liquid decontamination reagent solution with solid sorbent particles. The components have fewer safety and environmental concerns than traditional chlorine bleach-based products or highly caustic solutions. The liquid solution, based on Decon Green TM , has hydrogen peroxide and a carbonate buffer as active ingredients. The best solid sorbents were found to be a copolymer of ethylene glycol dimethacrylate and n-lauryl methacrylate (Polytrap 6603 Adsorber); or an allyl methacrylate cross-linked polymer (Poly-Pore E200 Adsorber). These solids are human and environmentally friendly and are commonly used in cosmetics. The decontaminant system was tested for reactivity with pinacolyl methylphosphonofluoridate (Soman, GD), bis(2-chloroethyl)sulfide (Mustard, HD), and S-(2-diisopropylaminoethyl) O-ethyl methylphosphonothioate (VX) by using NMR Spectroscopy. Molybdate ion (MoO 4 -2 ) was added to the decontaminant to catalyze the oxidation of HD. The molybdate ion provided a color change from pink to white when the oxidizing capacity of the system was exhausted. The decontaminant was effective for ratios of agent to decontaminant of up to 1:50 for VX (t 1/2 ≤ 4 min), 1:10 for HD (t 1/2 1/2 < 2 min). The vapor concentrations of GD above the dry sorbent and the sorbent with decontamination solution were measured to show that the sorbent decreased the vapor concentration of GD. The E200 sorbent had the additional advantage of absorbing aqueous decontamination solution without the addition of an organic co-solvent such as isopropanol, but the rate depended strongly on mixing for HD

  3. Radiotracer aided optimization of batch mixing of solids

    Kolar, Z.I.; Bergh, W.J.B. van den; Scarlett, B.

    1989-01-01

    A method for the determination of mixing times has been developed and tested in a model Nauta mixer filled with sand. 128 I-labelled sand particles were used as radiotracer and the progress of mixing was monitored with two radiation detectors located externally. The variance of the radiation intensity decreases with time until a constant value is reached indicating an equilibrium mixture of tracer and sand. The time necessary to achieve this condition (mixing time) appears to be dependent on the rotational speed of the hopper as well as the screw of the mixer. Optimal mixing performance (shortest mixing time) corresponds to the maximal rotational speeds of both rotating parts of the mixer. (author)

  4. Engineering solutions to the management of solid radioactive waste

    1991-01-01

    The management of radioactive waste, its safe handling and ultimate disposal, is of vital concern to engineers in the nuclear industry. The international conference 'Engineering Solutions to the Management of Solid Radioactive Waste', organized by the Institution of Mechanical Engineers and held in Manchester in November 1991, provided a forum for the discussion and comparison of the different methods of waste management used in Europe and America. Papers presented and discussed included: the interaction between the design of containers for low level radioactive waste and the design of a deep repository, commercial low level waste disposal sites in the United States, and the development of radioactive waste monitoring systems at the Sellafield reprocessing complex. This volume is a collection of 22 papers presented at the conference. All are indexed separately. (author)

  5. Applicability of Solid Solution Heat Treatments to Aluminum Foams

    Miguel Rodríguez-Pérez

    2012-12-01

    Full Text Available Present research work evaluates the influence of both density and size on the treatability of Aluminum-based (6000 series foam-parts subjected to a typical solid solution heat treatment (water quenching. The results are compared with those obtained for the bulk alloy, evaluating the fulfilment of cooling requirements. Density of the foams was modeled by tomography analysis and the thermal properties calculated, based on validated density-scaled models. With this basis, cooling velocity maps during water quenching were predicted by finite element modeling (FEM in which boundary conditions were obtained by solving the inverse heat conduction problem. Simulations under such conditions have been validated experimentally. Obtained results address incomplete matrix hardening for foam-parts bigger than 70 mm in diameter with a density below 650 kg/m3. An excellent agreement has been found in between the predicted cooling maps and final measured microhardness profiles.

  6. Thermodynamic Mixing Behavior Of F-OH Apatite Crystalline Solutions

    Hovis, G. L.

    2011-12-01

    It is important to establish a thermodynamic data base for accessory minerals and mineral series that are useful in determining fluid composition during petrologic processes. As a starting point for apatite-system thermodynamics, Hovis and Harlov (2010, American Mineralogist 95, 946-952) reported enthalpies of mixing for a F-Cl apatite series. Harlov synthesized all such crystalline solutions at the GFZ-Potsdam using a slow-cooled molten-flux method. In order to expand thermodynamic characterization of the F-Cl-OH apatite system, a new study has been initiated along the F-OH apatite binary. Synthesis of this new series made use of National Institute of Standards and Technology (NIST) 2910a hydroxylapatite, a standard reference material made at NIST "by solution reaction of calcium hydroxide with phosphoric acid." Synthesis efforts at Lafayette College have been successful in producing fluorapatite through ion exchange between hydroxylapatite 2910a and fluorite. In these experiments, a thin layer of hydroxylapatite powder was placed on a polished CaF2 disc (obtained from a supplier of high-purity crystals for spectroscopy), pressed firmly against the disc, then annealed at 750 °C (1 bar) for three days. Longer annealing times did not produce further change in unit-cell dimensions of the resulting fluorapatite, but it is uncertain at this time whether this procedure produces a pure-F end member (chemical analyses to be performed in the near future). It is clear from the unit-cell dimensions, however, that the newly synthesized apatite contains a high percentage of fluorine, probably greater than 90 mol % F. Intermediate compositions for a F-OH apatite series were made by combining 2910a hydroxylapatite powder with the newly synthesized fluorapatite in various proportions, then conducting chemical homogenization experiments at 750 °C on each mixture. X-ray powder diffraction data indicated that these experiments were successful in producing chemically homogeneous

  7. Crystal-chemical features of the solid solutions

    Titov, V.V.; Kesler, Ya.A.; Gordeev, I.V.; Mozhaev, A.P.

    1988-04-01

    The unusual magnetic properties of the solid solutions of CuCr/sub 2/S/sub 4/ in Cu/sub 0.5/Mo/sub 0.5/Cr/sub 2/S/sub 4/ (M = Al, Ga, In) are closely related to the crystal chemistry of these compounds. Specimens for structural investigation were obtained by solid-phase synthesis in evacuated quartz capsules. X-ray phase analysis of all the compounds was made by the powder method in a DRON-1 diffractometer with Cu K..cap alpha.. filtered radiation. The experimental confirmation of the ordering of the cations in the tetrahedral sublattice of the investigated spinels was obtained by the authors from their IR absorption spectra taken in the range 400-33 cm/sup /minus/1/. The presence of seven intense absorption bands in the spectra of the specimens indicates that these materials belong to the space group F/anti/43m, i.e., that there is ordering in the A sublattice. Their investigation led them to the conclusion that in a number of cases the vibrational spectra of the crystals are more sensitive in the investigation of atomic ordering than the spectra of x-ray and neutron diffraction, in agreement with the theoretical predictions.

  8. MERCURY REMOVAL FROM DOE SOLID MIXED WASTE USING THE GEMEP(sm) TECHNOLOGY

    None

    1999-03-01

    Under the sponsorship of the Federal Energy Technology Center (FETC), Metcalf and Eddy (M and E), in association with General Electric Corporate Research and Development Center (GE-CRD), Colorado Minerals Research Institute (CMRI), and Oak Ridge National Laboratory (ORNL), conducted laboratory-scale and bench-scale tests of the General Electric Mercury Extraction Process technology on two mercury-contaminated mixed solid wastes from U. S. Department of Energy sites: sediment from the East Fork of Poplar Creek, Oak Ridge (samples supplied by Oak Ridge National Laboratory), and drummed soils from Idaho National Environmental and Engineering Laboratory (INEEL). Fluorescent lamps provided by GE-CRD were also studied. The GEMEP technology, invented and patented by the General Electric Company, uses an extraction solution composed of aqueous potassium iodide plus iodine to remove mercury from soils and other wastes. The extraction solution is regenerated by chemical oxidation and reused, after the solubilized mercury is removed from solution by reducing it to the metallic state. The results of the laboratory- and bench-scale testing conducted for this project included: (1) GEMEP extraction tests to optimize extraction conditions and determine the extent of co-extraction of radionuclides; (2) pre-screening (pre-segregation) tests to determine if initial separation steps could be used effectively to reduce the volume of material needing GEMEP extraction; and (3) demonstration of the complete extraction, mercury recovery, and iodine recovery and regeneration process (known as locked-cycle testing).

  9. Fabrication and Application of (1-x) NaCl+xKCl Solid Solution

    Kyi Kyi Lwin

    2011-12-01

    (1-X)NaCl+xKCl solid solution are prepared by the starting materials NaCl (0.9, 0.95) in equal molar ratio. The solid solutions are heat-treated at various temperature and XRD analyses are carried out for the solid solutions to examine the crystalline phase, crystallographic orientation and lattice parameters. The electrical properties of the solutions are determined by using the conductometer. The solid solutions are utilized as crystal oscillator and outcoming frequencies, capacitances and dielectric constants are also investigated.

  10. Solution properties of solid and liquid potassium-indium alloys

    Takenaka, T.; Saboungi, M.L.

    1987-01-01

    It was recently shown by a combination of electrical resistivity, thermodynamic, and structural measurements that equiatomic alloys formed between K or Na and either Bi, Sb, Te, or Pb show pronounced deviations from ordinary metallic behavior and from ideal solution behavior, e.g., small values for the electrical conductivity and sharp peaks for the Darken excess stability function. Physical explanation of this behavior has been advanced on the basis of the formation of complex structural species similar to those reported for the corresponding solid alloys. The authors have chosen K-In alloys for several reasons. Phase diagram considerations coupled with small electronegativity differences between K and In would lead one to predict small deviations from ideal behavior, thus, this system would be suitable to test for oddities in alloy solution behavior in systems which deviate little from ideal behavior. Others have demonstrated that the position of the peak in the electrical resistivity changed in going from Li to Na and to K in the following sequence X/sub In/ ≅ 0.25, 0.40, and 0.50, respectively. The thermodynamic properties of these alloys would be expected to present similar trends

  11. Synthesis and properties of γ-Ga2O3-Al2O3 solid solutions

    Afonasenko, T. N.; Leont'eva, N. N.; Talzi, V. P.; Smirnova, N. S.; Savel'eva, G. G.; Shilova, A. V.; Tsyrul'nikov, P. G.

    2017-10-01

    The textural and structural properties of mixed oxides Ga2O3-Al2O3, obtained via impregnating γ-Al2O3 with a solution of Ga(NO3)3 and subsequent heat treatment, are studied. According to the results from X-ray powder diffraction, gallium ions are incorporated into the structure of aluminum oxide to form a solid solution of spinel-type γ-Ga2O3-Al2O3 up to a Ga2O3 content of 50 wt % of the total weight of the sample, accompanied by a reduction in the specific surface area, volume, and average pore diameter. It is concluded that when the Ga2O3 content exceeds 50 wt %, the β-Ga2O3 phase is observed along with γ-Ga2O3-Al2O3 solid solution. 71Ga and 27Al NMR spectroscopy shows that gallium replaces aluminum atoms from the tetrahedral position to the octahedral coordination in the structure of γ-Ga2O3-Al2O3.

  12. Detailed simulations of liquid and solid-liquid mixing : Turbulent agitated flow and mass transfer

    Hartmann, H.

    2005-01-01

    This thesis aims at a contribution to reliable and accurate predictions of complex, multi-phase processes. The reader is presented detailed simulations on liquid and solid-liquid mixing using large eddy simulations (LES) including scalar mixing and particle transport in a Rushton turbine stirred

  13. Temperature control in a continuously mixed bioreactor for solid-state fermentation

    Nagel, F.J.J.I.; Tramper, J.; Bakker, M.S.N.; Rinzema, A.

    2001-01-01

    A continuously mixed, aseptic paddle mixer was used successfully for solid-state fermentation (SSF) with Aspergillus oryzae on whole wheat kernels. Continuous mixing improved temperature control and prevented inhomogeneities in the bed. Respiration rates found in this system were comparable to those

  14. Fuel mix electricity 2020, inventory, problems and solutions

    Seebregts, A.J.; Snoep, H.J.M.; Van Deurzen, J.; Lensink, S.M.; Van der Welle, A.J.; Wetzels, W.

    2010-04-01

    ECN made an inventory of the fuel mix of the electricity generation in the Netherlands for the year 2020. The inventory is derived from the updated Reference Projections that are based on the Global Economy scenario. This scenario has a relatively high growth of the domestic electricity demand (156 TWh in 2020 compared to about 118 TWh in 2008). Besides the factual inventory, ECN made a quickscan of potential problems associated with high penetration of electricity from wind energy, up to 12,000 MW in 2020. The conclusion is that the so-called 'offpeak hours issue' (in Dutch: 'het daluren issue') is a real potential problem under such scenario assumptions. In case of full wind availability, the total generating capacity consisting of must-run capacity and typical base load power plants with low variable cost of production (nuclear and coal) may exceed the electricity demand (domestic plus net export) in part of these off-peak situations, e.g. during nighttime. The must-run capacity consists, among others, of part of the decentralised CHP installations and waste incinerators. Potential solutions to this 'off-peak hours issue' are: (1) Flexibility in electricity demand ('demand response'); (2) Additional interconnection with neighbouring countries and appropriate market design rules; (3) Storage of electricity; (4) Flexibility of conventional (fossil) supply; (5) Flexibility of the intermittent renewable generation itself; (6) Intelligent grids ('Smart Grids'). Additional detailed analyses and research are needed to address the magnitude of the problem and to analyse the contribution of the various solutions. Such an analysis can provide an indication of an optimal and feasible combination of the solutions identified. Relevant issues are: (a) How often, with which magnitude and under which circumstances will the problem occur?; (b) What will be the effect on the curtailing of wind energy, and is curtailing plausible given current market rules and renewable energy

  15. A Thermodynamic Mixed-Solid Asphaltene Precipitation Model

    Lindeloff, Niels; Heidemann, R.A.; Andersen, Simon Ivar

    1998-01-01

    A simple model for the prediction of asphaltene precipitation is proposed. The model is based on an equation of state and uses standard thermodynamics, thus assuming that the precipitation phenomenon is a reversible process. The solid phase is treated as an ideal multicomponent mixture. An activity...

  16. Uptake of ozone to mixed sodium bromide/ citric acid solutions

    Lee, Ming-Tao; Steimle, Emilie; Bartels-Rausch, Thorsten; Kato, Shunsuke; Lampimäki, Markus; Brown, Matthew; van Bokhoven, Jeroen; Nolting, Frithjof; Kleibert, Armin; Türler, Andreas; Ammann, Markus

    2013-04-01

    Sea-salt solution - air interfaces play an important role in the chemistry of the marine boundary layer. The reaction of ozone (O3) with bromide is of interest in the context of formation of photolabile halogens (Br2, BrCl) in the marine boundary layer. Recent experiments have suggested that the bromide oxidation rate is related to the surface concentration of bromide [1] and inversely related to the gas phase concentration of O3, an indication for a precursor mediated reaction at the surface [2]. So far, the effect of organics (such as those occurring at the ocean surface or in marine aerosols) on the reaction of O3 with bromide aerosols has not been studied yet. In our study we investigate the uptake kinetics of O3 to a mixed solution of sodium bromide (NaBr) and citric acid (CA), which represents highly oxidized organic compounds present in the environment, with a well-established coated wall flow tube technique, which leads to exposure of the film to O3 allowing the heterogeneous reactions to take place and the loss of O3 being measured. The results indicate that the uptake of O3 to the films with the higher bromide concentrations (0.34M and 4M) is independent of the gas phase concentration and roughly consistent with uptake limited by reaction in the bulk. For the lower bromide concentration (84mM), however, we observe a trend of the uptake coefficient to decrease with increasing O3 concentration, indicating an increasing importance of a surface reaction. In an attempt to constrain the kinetic data, we employed X-ray photoelectron spectroscopy (XPS) to get insight into the surface composition of the aqueous solution - air interface. Previous XPS studies have shown that halide ion concentrations are enhanced at the aqueous solution air interface [3-4], which likely promotes the surface reactions of bromide or iodide with O3. A first XPS study of ternary solutions of KI with butanol indicated the importance of specific interactions of the cation with the alcohol

  17. Purification of uranothorite solid solutions from polyphase systems

    Clavier, Nicolas, E-mail: nicolas.clavier@icsm.fr [ICSM, UMR 5257 CEA/CNRS/UM2/ENSCM, Site de Marcoule – Bât. 426, BP 17171, 30207 Bagnols/Cèze cedex (France); Szenknect, Stéphanie; Costin, Dan Tiberiu; Mesbah, Adel; Ravaux, Johann [ICSM, UMR 5257 CEA/CNRS/UM2/ENSCM, Site de Marcoule – Bât. 426, BP 17171, 30207 Bagnols/Cèze cedex (France); Poinssot, Christophe [CEA/DEN/DRCP/DIR, Site de Marcoule – Bât. 400, BP 17171, 30207 Bagnols/Cèze cedex (France); Dacheux, Nicolas [ICSM, UMR 5257 CEA/CNRS/UM2/ENSCM, Site de Marcoule – Bât. 426, BP 17171, 30207 Bagnols/Cèze cedex (France)

    2013-10-15

    Graphical abstract: Display Omitted -- Highlights: •Purification of Th{sub 1−x}U{sub x}SiO{sub 4} uranothorites from oxide mixture was investigated. •Repetition of centrifugation steps was discarded due to poor recovery yields. •Successive washings in acid and basic media allowed the elimination of oxide secondary phases. •Structural and microstructural characterization of the purified samples was provided. -- Abstract: The mineral coffinite, nominally USiO{sub 4}, and associated Th{sub 1−x}U{sub x}SiO{sub 4} uranothorite solid solutions are of great interest from a geochemical point of view and in the case of the direct storage of spent nuclear fuels. Nevertheless, they clearly exhibit a lack in the evaluation of their thermodynamic data, mainly because of the difficulties linked with their preparation as pure phases. This paper thus presents physical and chemical methods aiming to separate uranothorite solid solutions from oxide additional phases such as amorphous SiO{sub 2} and nanometric crystallized Th{sub 1−y}U{sub y}O{sub 2}. The repetition of centrifugation steps envisaged in first place was rapidly dropped due to poor recovery yields, to the benefit of successive washings in acid then basic media. Under both static and dynamic flow rates (i.e. low or high rate of leachate renewal), ICP-AES (Inductively Coupled Plasma – Atomic Emission Spectroscopy) analyses revealed the systematic elimination of Th{sub 1−y}U{sub y}O{sub 2} in acid media and of SiO{sub 2} in basic media. Nevertheless, two successive steps were always needed to reach pure samples. On this basis, a first cycle performed in static conditions was chosen to eliminate the major part of the accessory phases while a second one, in dynamic conditions, allowed the elimination of the residual impurities. The complete purification of the samples was finally evidenced through the characterization of the samples by the means of PXRD (Powder X-Ray Diffraction), SEM (Scanning Electron

  18. Mixing and solid suspension of up-down agitators in a slab tank

    Ramsey, C.J.

    1989-01-01

    Seven different up-down agitators were studied for their ability to produce mixing and solid suspension in a slab tank. Mixing times were measured as the time needed to disperse injected dye. The solid suspension studies determined the minimum stroke frequency of the agitators needed for complete off-bottom suspension. The effects of stroke frequency, n; amplitude, a; blade width, w; blade clearance, c; and liquid depth, h, and weight percent solids, X, were studied. The most effective geometry, in terms of mixing, solid suspension and design simplicity, was a single flat blade with minimum off-bottom clearance and a blade width/tank thickness ratio, w/T, of 0.74 at the maximum stroke amplitude studied. 15 refs., 7 figs

  19. Geological constraints on the thermodynamic properties of the stilbite - stellerite solid solution in low-grade metabasalts

    Fridriksson, Thráinn; Neuhoff, Philip S.; Arnórsson, Stefán; Bird, Dennis K.

    2001-11-01

    Standard state thermodynamic data for stilbite (Ca2NaAl5Si13O36∗16H2O) and stellerite (Ca2Al4Si14O36∗14H2O), together with mixing properties of the stilbite -stellerite solid solution (stilbite SS) are derived through assessment of geological observations of stilbite SS compositions in metabasalts, experimental phase equilibria, and calorimetric observations. Measured compositions of stilbite SS in Tertiary metabasalts in Iceland and Icelandic geothermal systems change systematically towards the stellerite endmember with increasing stratigraphic depth and temperature. Standard molal volumes, heat capacities, and entropies for the endmembers of the solid solution are derived through critical review of published crystallographic and calorimetric data for natural stilbite SS. Standard molal Gibbs energies of formation at 298.15 K and 1 bar for stilbite (-4,946,475cal mol-1) and stellerite (-4,762,036 cal mol-1) and the mixing properties of the solid solution are retrieved from observed phase- and compositional-relations in metabasalts at Berufjördur, Iceland, measured temperatures of zeolite mineral distribution in active geothermal systems, and published observations of reversed phase equilibria. Mixing in stilbite SS can be described with an athermal solid solution model. Thermodynamic data resulting from our analysis provide close correlation between compositions of stilbite SS in Icelandic geothermal systems predicted from compositions of geothermal solutions and observed compositions of these minerals in low-grade metabasalts of Iceland, as well as the observed temperature of the stilbite SS to laumontite (leonhardite) transition in Icelandic geothermal systems. Stilbite SS composition in metabasalts is a sensitive function of temperature, fluid composition, coexisting minerals (especially silica polymorphs) and geothermal gradient.

  20. Sustainable solutions for solid waste management in Southeast Asian countries

    Uyen Nguyen Ngoc; Schnitzer, Hans

    2009-01-01

    Human activities generate waste and the amounts tend to increase as the demand for quality of life increases. Today's rate in the Southeast Asian Nations (ASEANs) is alarming, posing a challenge to governments regarding environmental pollution in the recent years. The expectation is that eventually waste treatment and waste prevention approaches will develop towards sustainable waste management solutions. This expectation is for instance reflected in the term 'zero emission systems'. The concept of zero emissions can be applied successfully with today's technical possibilities in the agro-based processing industry. First, the state-of-the-art of waste management in Southeast Asian countries will be outlined in this paper, followed by waste generation rates, sources, and composition, as well as future trends of waste. Further on, solutions for solid waste management will be reviewed in the discussions of sustainable waste management. The paper emphasizes the concept of waste prevention through utilization of all wastes as process inputs, leading to the possibility of creating an ecosystem in a loop of materials. Also, a case study, focusing on the citrus processing industry, is displayed to illustrate the application of the aggregated material input-output model in a widespread processing industry in ASEAN. The model can be shown as a closed cluster, which permits an identification of opportunities for reducing environmental impacts at the process level in the food processing industry. Throughout the discussion in this paper, the utilization of renewable energy and economic aspects are considered to adapt to environmental and economic issues and the aim of eco-efficiency. Additionally, the opportunities and constraints of waste management will be discussed.

  1. The influence of precipitation temperature on the properties of ceria–zirconia solid solution composites

    Cui, Yajuan; Fang, Ruimei; Shang, Hongyan; Shi, Zhonghua; Gong, Maochu; Chen, Yaoqiang

    2015-01-01

    Highlights: • The crystallite size of precipitate increases as the precipitation temperature rises. • The stack of large crystallite can form nanoparticles with big pore size. • Big pore sizes are advantageous to improve the thermal stability. • Phase segregation is restricted in CZ solid solution precipitated at 70 °C. • The reducibility and OSC of the solid solution precipitated at 70 °C are improved. - Abstract: The ceria–zirconia composites (CZ) with a Ce/Zr mass ratio of 1/1 were synthesized by a back-titration method, in which the influence of precipitation temperature on the properties of ceria–zirconia precipitates was investigated. The resulting precipitation and mixed oxides at different precipitation temperatures were then characterized by a range of techniques, including textural properties, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), H 2 -temperature programmed reduction (H 2 -TPR) as well as oxygen storage capacity (OSC) measurement. The results revealed that ceria–zirconia composites were formed as solid solution and such structure is favored of thermostability and texture properties. In particular, the composite CZ-70 synthesized at 70 °C exhibited prominent thermostability with a surface area of 32 m 2 /g as well as a pore volume of 0.15 cc/g after aging treatment at 1000 °C for 5 h. And this was found to be associated with the wider pore size distribution which maybe owed to the formation of large crystal at the primary stage of precipitation. Additionally, the composite CZ-70 showed excellent reduction property and OSC benefiting from stable texture and structure

  2. Impact of vacancy-solute clusters on the aging of α-Fe solid solutions

    Schuler, Thomas

    2015-01-01

    Understanding and monitoring the aging of steels under vacancy supersaturation is a challenge of great practical interest for many industrial groups, and most of all for those related to nuclear energy. These steels always contain interstitial solutes, either as alloying elements or as impurities, and vacancies (V) that are equilibrium structural defects of materials. We have chosen the Fe-V -X system (X = C, N or O) as a model system for ferritic steels. Vacancy-solute clusters are likely to form in such systems because, despite the very low concentrations of their components, these cluster show very high attractive bonding. First of all, we have been working on the computation of intrinsic equilibrium properties of individual clusters, both thermodynamic (free binding energies) and kinetic (mobilities, dissociation coefficients, and their relationship with continuum diffusion) properties. Thanks to this atomic-scale characterization procedure, we have been able to highlight various effects of these clusters on a macroscopic system containing different cluster types: increase of solute solubility limits and total vacancy concentrations, flux couplings between interstitial solutes and vacancies, acceleration of solute precipitation kinetics and precipitate dissolution by solid solution stabilization due to vacancies. These results would not have been obtained without the development and/or extension of analytical methods in statistical physics which are able to describe cluster's components and their interactions at the atomic scale. Finally, we have also been working on cavities in α-iron, the study of which requires a different approach. Our study highlights the impact of the atomic discrete lattice on the equilibrium shape of cavities, and describes various kinetic mechanisms of these objects at the atomic scale. (author) [fr

  3. Solid on liquid deposition, a review of technological solutions

    Homsy, Alexandra; Laux, Edith; Jeandupeux, Laure; Charmet, Jérôme; Bitterli, Roland; Botta, Chiara; Rebetez, Yves; Banakh, Oksana; Keppner, Herbert

    2015-01-01

    Solid-on-liquid deposition (SOLID) techniques are of great interest to the MEMS and NEMS (Micro- and Nano Electro Mechanical Systems) community because of potential applications in biomedical engineering, on-chip liquid trapping, tunable micro-lenses, and replacements of gate oxides. However, depositing solids on liquid with subsequent hermetic sealing is difficult because liquids tend to have a lower density than solids. Furthermore, current systems seen in nature lack thermal, mechanical or...

  4. Solid solution cermet: (Ti,Nb)(CN)-Ni cermet.

    Kwon, Hanjung; Jung, Sun-A

    2014-11-01

    Solid solution powders without W, (Ti,Nb)(CN) powders with a B1 structure (NaCl like), were synthesized by high energy milling and carbothermal reduction in nitrogen. The range of molar ratios of Ti/Nb for forming complete (Ti,Nb)(CN) phase was broader than that of Ti/W for the (Ti,W)(CN) phase because carbide or carbonitride of Nb had a B1 crystal structure identical to Ti(CN) while WC had a hexagonal crystal structure. The results revealed that the hardness of (Ti,Nb)(CN)-Ni cermets was higher than that of (Ti,W)(CN)-Ni cermets. The lower density of the (Ti,Nb)(CN) powder contributed to the higher hardness compared to (Ti,W)(CN) because the volumetric ratio of (Ti,Nb)(CN) in the (Ti,Nb)(CN)-Ni cermets was higher than that of (Ti,Nb)(CN) in the (Ti,W)(CN)-Ni cermets at the same weight ratio of Ni. Additionally, it was assumed that intrinsic the properties of (Ti,Nb)(CN) could also be the cause for the high hardness of the (Ti,Nb)(CN)-Ni cermets.

  5. Mercury removal from liquid and solid mixed waste

    Gates, D.D.; Klasson, K.T.; Corder, S.L.; Cameron, P.A.; Perona, J.J.

    1995-01-01

    Based on bench-scale laboratory experiments, the following conclusions were reached: Sulfur-impregnated, activated, carbon pellets (Mersorb) can be used to remove mercury (Hg 2+ ) to below EPA's toxic characteristic level (0.2 mg/L). Mersorb works under acid conditions (pH 2) but its capacity is reduced by approximately 50% compared with neutral conditions. Competing ions present in the target waste stream reduced the Mersorb capacity by 50%. Mersorb appears to be economical compared with leading ion exchange resin. KI/I 2 leaching solution can be used to remove up to 99% of Hg in contaminated soil and glass. KI/I 2 leaching solution worked well with several mercury species, including Hg 0 , HgO, HgS, and HgCl 2 . KI/I 2 leaching solution worked well with a wide variety of initial mercury concentrations. Radionuclide surrogate studies suggested that uranium will not partition into KI/I 2 leaching solutions. Cesium may partition into the KI/I 2 leaching solution because of the high solubility of cesium salts

  6. Local structural relaxation around Co2+ along the hardystonite-Co-åkermanite melilite solid solution

    Ardit, Matteo; Cruciani, Giuseppe; Dondi, Michele

    2012-10-01

    Six pure compounds belonging to the hardystonite (Ca2ZnSi2O7)-Co-åkermanite (Ca2CoSi2O7) solid solution were investigated by the combined application of X-ray powder diffraction and electronic absorption spectroscopy. Structural refinements of the XRPD data revealed a negative excess volume of mixing due to the single isovalent substitution of Co for Zn in the tetrahedral site. In agreement with the diffraction data, deconvolution of the optical spectra showed a progressive decreasing of the crystal field strength parameter 10 Dq moving toward the Co-åkermanite end-member, meaning that the local cobalt-oxygen bond distance, Co}}{-}{{O}}rangle^{{local}} , increased along the join with the amount of cobalt. The calculated structural relaxation coefficient around the fourfold coordinated Co2+ in the Ca2(Zn1- x Co x )Si2O7 join was ɛ = 0.69, very far from the one predicted by the Vegard's law ( ɛ = 0) and at variance with ɛ = 0.47 previously found for tetrahedrally coordinated Co2+ in gahnite-Co-aluminate spinel solid solution. This difference is consistent with the largest constraints existing on the spinel structure, based on cubic closest packing, compared to the more flexible layered melilite structure.

  7. The theory of neutron scattering from mixed harmonic solids

    Warner, M.; Lovesey, S.W.; Smith, J.

    1982-12-01

    The dynamic structure factor for incoherent neutron scattering from light mass particles substituted in a solid is calculated for two model systems. One model is appropriate for a dilute concentration of light particles in a matrix, and the second is a binary system with various masses and force constants. The exact calculations are used to assess the value of approximation schemes for the dynamic structure factor which exploit the separation of time scales in the motions of the light and the heavier lattice particles. (author)

  8. Investigation of physicochemical and pigment properties of solid solutions of cadmium, manganese, zinc sulfides

    Grigor'eva, L.I.; Ignat'eva, I.V.; Kalinskaya, T.V.

    1985-01-01

    Mixed sulfides (Cd, Mn)S and (Cd, Mn, Zn)S with manganese sulfide content upto 50 mol% are synthesized. The possibility of preparing solid solutions both on the basis of silfides (Cd, Mn)S and in the ternary system (Cd, Mn, Zn)S with the temperature of polymorphic transformation of a cubic structure into a hexagonal one, being lower (500 deg C) than in the absence of MnS, is shown by the X-ray diffraction method. The colour analysis of the pigment specimens obtained has shown that the quantity of oxidized manganese compounds, producing no effect of the system colour, should not exceed 0.05 mol% on conversion to MnS. Among the mixed specimens (Cd, Mn)S the brightest colour background is obtained for specimens calcinated at 500-550 deg C. The mixed sulfide of the composition 0.77CdSx0.15MnSx0.08ZnS, calcinated at 500 deg C, gives a pigment corresponding to a commercial one by colour

  9. OSMOTIC COEFFICIENTS, SOLUBILITIES, AND DELIQUESCENCE RELATIONS IN MIXED AQUEOUS SALT SOLUTIONS AT ELEVATED TEMPERATURE

    M.S. Gruszkiewicz; D.A. Palmer

    2006-01-01

    While thermodynamic properties of pure aqueous electrolytes are relatively well known at ambient temperature, there are far fewer data for binary systems extending to elevated temperatures and high concentrations. There is no general theoretically sound basis for prediction of the temperature dependence of ionic activities, and consequently temperature extrapolations based on ambient temperature data and empirical equations are uncertain and require empirical verification. Thermodynamic properties of mixed brines in a wide range of concentrations would enhance the understanding and precise modeling of the effects of deliquescence of initially dry solids in humid air in geological environments and in modeling the composition of waters during heating, cooling, evaporation or condensation processes. These conditions are of interest in the analysis of waters on metal surfaces at the proposed radioactive waste repository at Yucca Mountain, Nevada. The results obtained in this project will be useful for modeling the long-term evolution of the chemical environment, and this in turn is useful for the analysis of the corrosion of waste packages. In particular, there are few reliable experimental data available on the relationship between relative humidity and composition that reveals the eutonic points of the mixtures and the mixture deliquescence RH. The deliquescence RH for multicomponent mixtures is lower than that of pure component or binary solutions, but is not easy to predict quantitatively since the solutions are highly nonideal. In this work we used the ORNL low-temperature and high-temperature isopiestic facilities, capable of precise measurements of vapor pressure between ambient temperature and 250 C for determination of not only osmotic coefficients, but also solubilities and deliquescence points of aqueous mixed solutions in a range of temperatures. In addition to standard solutions of CaCl 2 , LiCl, and NaCl used as references, precise direct

  10. A New Class of Ternary Compound for Lithium-Ion Battery: from Composite to Solid Solution.

    Wang, Jiali; Wu, Hailong; Cui, Yanhua; Liu, Shengzhou; Tian, Xiaoqing; Cui, Yixiu; Liu, Xiaojiang; Yang, Yin

    2018-02-14

    Searching for high-performance cathode materials is a crucial task to develop advanced lithium-ion batteries (LIBs) with high-energy densities for electrical vehicles (EVs). As a promising lithium-rich material, Li 2 MnO 3 delivers high capacity over 200 mAh g -1 but suffers from poor structural stability and electronic conductivity. Replacing Mn 4+ ions by relatively larger Sn 4+ ions is regarded as a possible strategy to improve structural stability and thus cycling performance of Li 2 MnO 3 material. However, large difference in ionic radii of Mn 4+ and Sn 4+ ions leads to phase separation of Li 2 MnO 3 and Li 2 SnO 3 during high-temperature synthesis. To prepare solid-solution phase of Li 2 MnO 3 -Li 2 SnO 3 , a buffer agent of Ru 4+ , whose ionic radius is in between that of Mn 4+ and Sn 4+ ions, is introduced to assist the formation of a single solid-solution phase. The results show that the Li 2 RuO 3 -Li 2 MnO 3 -Li 2 SnO 3 ternary system evolves from mixed composite phases into a single solid-solution phase with increasing Ru content. Meanwhile, discharge capacity of this ternary system shows significantly increase at the transformation point which is ascribed to the improvement of Li + /e - transportation kinetics and anionic redox chemistry for solid-solution phase. The role of Mn/Sn molar ratio of Li 2 RuO 3 -Li 2 MnO 3 -Li 2 SnO 3 ternary system has also been studied. It is revealed that higher Sn content benefits cycling stability of the system because Sn 4+ ions with larger sizes could partially block the migration of Mn 4+ and Ru 4+ from transition metal layer to Li layer, thus suppressing structural transformation of the system from layered-to-spinel phase. These findings may enable a new route for exploring ternary or even quaternary lithium-rich cathode materials for LIBs.

  11. Mixed ligand chelates of rare earths in aqueous solution

    Lakhani, S.U.; Thakur, G.S.; Sangal, S.P.

    1981-01-01

    Mixed ligand chelates of the 1:1 trivalent lanthanoids-EDTA, HEDTA and NTA chelates-1, 2-Dihydroxybenzene (Pyrocatechol) have been investigated at 35degC and 0.2 M ionic strength maintained by NaC10 4 . The formation of mixed ligand chelates has been found in all cases. The formation of mixed ligand chelates with EDTA shows the coordination number of lanthanoids to be eight, while the mixed ligand chelates with HEDTA and NTA shows the coordination number to be seven and six respectively. The stability constants of mixed ligand chelates are smaller than the binary complexes. The order of stability constants with respect to primary ligands follows the order NTA>HEDTA>EDTA. With respect to metal ions the stability constants increases with the decrease in ionic radii such as Gd< Er< Yb. (author)

  12. Comparative solution and solid-phase glycosylations toward a disaccharide library

    Agoston, K.; Kröger, Lars; Agoston, Agnes

    2009-01-01

    A comparative study on solution-phase and solid-phase oligosaccharide synthesis was performed. A 16-member library containing all regioisomers of Glc-Glc, Glc-Gal, Gal-Glc, and Gal-Gal disaccharides was synthesized both in solution and on solid phase. The various reaction conditions for different...

  13. Crystal chemical analysis of formation of solid solutions on the basis of compounds with garnet structure

    Kuz'micheva, G.M.; Kozlikin, S.N.

    1989-01-01

    Crystal chemical formulas permitting to evaluate the character of changes in interatomic distances during isomorphous substitution and, hence, the probability of formation of internal solid solutions and successive isomorphous substitution, are presented. The possibility of formation of introduction solid solutions is considered, using as an example Sc, Y oxides, rare earths with garnet structure

  14. Optimization of soymilk, mango nectar and sucrose solution mixes for better quality of soymilk based beverage.

    Getu, Rahel; Tola, Yetenayet B; Neela, Satheesh

    2017-01-01

    Soy milk-based beverages play an important role as a healthy food alternative for human consumption. However, the ‘beany’ flavor and chalky mouth feel of soy milk often makes it unpalatable to consumers. The objective of the present study is to optimize a blend of soy milk, mango nectar and sucrose solution for the best quality soy milk-based beverage. This study was designed to develop a soy milk blended beverage, with mango nectar and sucrose solutions, with the best physicochemical and sensory properties. Fourteen combinations of formulations were determined by D-optimal mixture simplex lattice design, by using Design expert. The blended beverages were prepared by mixing the three basic ingredients with the range of 60−100% soy milk, 0–25% mango nectar and 0–15% sucrose solution. The prepared blended beverage was analyzed for selected physicochemical and sensory properties. The statistical significance of the terms in the regression equations were examined by Analysis of Variance (ANOVA) for each response and the significance test level was set at 5% (p nectar and sucrose solution increased, total color change, total soluble solid, gross energy, titratable acidity, and beta-carotene contents increased but with a decrease in moisture , ash, protein, ether extract, minerals and phytic acid contents was observed. Fi- nally, numerical optimization determined that 81% soy milk, 16% Mango nectar and 3% sugar solution will give by a soy milk blended beverage with the best physicochemical and sensory properties, with a desirability of 0.564. Blending soy milk with fruit juice such as mango is beneficial, as it improves sensory as well as selected nutritional parameters.

  15. Isotopic exchange in mixed valence compounds in the solid state

    Fernandez Valverde, S.M.

    1986-01-01

    This work aims at the determination of isotopic exchange kinetics and mechanism in two mixed valence compounds: Cs 10 (Sbsup(V)Cl 6 ) (Sbsup(III)Cl 6 ) 3 and Tl 3 sup(I)(Tlsup(III)Cl 6 ). The synthesis of the first compound is very difficult because in most of the cases mixtures of chloroantimoniates are obtained. Exchange in Tl 4 Cl 6 labelled on Tlsup(III) is studied in detail by radiochemical analysis and physical techniques: ionic conductivity and positon annihilation. Cation vacancies are easily created in the lattice with formation enthalpy of 0.35 eV and migration enthalpy of 0.52 eV. Isochronic and isothermal exchange curves are described by a kinetic based on species diffusion. Models are given. Exchange is increased by grinding probably because extrinseque defects are introduced [fr

  16. A local mixing model for deuterium replacement in solids

    Doyle, B.L.; Brice, D.K.; Wampler, W.R.

    1980-01-01

    A new model for hydrogen isotope exchange by ion implantation has been developed. The basic difference between the present approach and previous work is that the depth distribution of the implanted species is included. The outstanding feature of this local mixing model is that the only adjustable parameter is the saturation hydrogen concentration which is specific to the target material and dependent only on temperature. The model is shown to give excellent agreement both with new data on H/D exchange in the low Z coating materials VB 2 , TiC, TiB 2 , and B reported here and with previously reported data on stainless steel. The saturation hydrogen concentrations used to fit these data were 0.15, 0.25, 0.15, 0.45, and 1.00 times atomic density respectively. This model should be useful in predicting the recycling behavior of hydrogen isotopes in tokamak limiter and wall materials. (author)

  17. The calcium oxide influence on formation of manganese, calcium pyrovanadate solid solutions

    Vatolin, N.A.; Volkova, P.I.; Sapozhnikova, T.V.; Ovchinnikova, L.A.

    1988-01-01

    The X-ray graphic, derivatographic, microscopic and chemical methods are used to study solid solutions of manganese, calcium pyrovanadates containing 1-10 mass% CaO and the products of interaction of reprocessing charges of vanadium-containing converter slags intended for he formation of manganese and calcium pyrovanadates with additions of calcium oxide within 10-90 mass%. It is established that in the case of 1-6 mass% CaO content in manganese pyrovanadate solid interstitial solutions appear, while at 6-20 mass% CaO - solid substitution solutions form. The results of calculating elementary cell parameters as well as melting temperatures and pyrovanadate solid solution solubility depending on CaO content are presented. The best solubility of introduction solid solutions during vanadium extraction according to the lime technology is found

  18. Numerical investigation of solid mixing in a fluidized bed coating process

    Kenche, Venkatakrishna; Feng, Yuqing; Ying, Danyang; Solnordal, Chris; Lim, Seng; Witt, Peter J.

    2013-06-01

    Fluidized beds are widely used in many process industries including the food and pharmaceutical sectors. Despite being an intensive research area, there are no design rules or correlations that can be used to quantitatively predict the solid mixing in a specific system for a given set of operating conditions. This paper presents a numerical study of the gas and solid dynamics in a laboratory scale fluidized bed coating process used for food and pharmaceutical industries. An Eulerian-Eulerian model (EEM) with kinetic theory of granular flow is selected as the modeling technique, with the commercial computational fluid dynamics (CFD) software package ANSYS/Fluent being the numerical platform. The flow structure is investigated in terms of the spatial distribution of gas and solid flow. The solid mixing has been evaluated under different operating conditions. It was found that the solid mixing rate in the horizontal direction is similar to that in the vertical direction under the current design and operating conditions. It takes about 5 s to achieve good mixing.

  19. Mixed chimerism to induce tolerance for solid organ transplantation

    Wren, S.M.; Nalesnik, M.; Hronakes, M.L.; Oh, E.; Ildstad, S.T.

    1991-01-01

    Chimerism, or the coexistence of tissue elements from more than one genetically different strain or species in an organism, is the only experimental state that results in the induction of donor-specific transplantation tolerance. Transplantation of a mixture of T-cell-depleted syngeneic (host-type) plus T-cell-depleted allogeneic (donor) bone marrow into a normal adult recipient mouse (A + B----A) results in mixed allogeneic chimerism. Recipient mice exhibit donor-specific transplantation tolerance, yet have full immunocompetence to recognize and respond to third-party transplantation antigens. After complete hematolymphopoietic repopulation at 28 days, animals accept a donor-specific skin graft but reject major histocompatibility complex (MHC) locus-disparate third-party grafts. We now report that permanent graft acceptance can also be achieved when the graft is placed at the time of bone marrow transplantation. Histologically, grafts were viable and had only minimal inflammatory changes. This model may have potential future clinical application for the induction of donor-specific transplantation tolerance

  20. A Local Composition Model for Paraffinic Solid Solutions

    Coutinho, A.P. João; Knudsen, Kim; Andersen, Simon Ivar

    1996-01-01

    The description of the solid-phase non-ideality remains the main obstacle in modelling the solid-liquid equilibrium of hydrocarbons. A theoretical model, based on the local composition concept, is developed for the orthorhombic phase of n-alkanes and tested against experimental data for binary sy...... systems. It is shown that it can adequately predict the experimental phase behaviour of paraffinic mixtures. This work extends the applicability of local composition models to the solid phase. Copyright (C) 1996 Elsevier Science Ltd....

  1. Solid lipid nanoparticles suspension versus commercial solutions for dermal delivery of minoxidil.

    Padois, Karine; Cantiéni, Céline; Bertholle, Valérie; Bardel, Claire; Pirot, Fabrice; Falson, Françoise

    2011-09-15

    Solid lipid nanoparticles have been reported as possible carrier for skin drug delivery. Solid lipid nanoparticles are produced from biocompatible and biodegradable lipids. Solid lipid nanoparticles made of semi-synthetic triglycerides stabilized with a mixture of polysorbate and sorbitan oleate were loaded with 5% of minoxidil. The prepared systems were characterized for particle size, pH and drug content. Ex vivo skin penetration studies were performed using Franz-type glass diffusion cells and pig ear skin. Ex vivo skin corrosion studies were realized with a method derived from the Corrositex(®) test. Solid lipid nanoparticles suspensions were compared to commercial solutions in terms of skin penetration and skin corrosion. Solid lipid nanoparticles suspensions have been shown as efficient as commercial solutions for skin penetration; and were non-corrosive while commercial solutions presented a corrosive potential. Solid lipid nanoparticles suspensions would constitute a promising formulation for hair loss treatment. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Precipitation in Al–Mg solid solution prepared by solidification under high pressure

    Jie, J.C.; Wang, H.W.; Zou, C.M.; Wei, Z.J.; Li, T.J.

    2014-01-01

    The precipitation in Al–Mg solid solution containing 21.6 at.% Mg prepared by solidification under 2 GPa was investigated. The results show that the γ-Al 12 Mg 17 phase is formed and the β′ phase cannot be observed in the solid solution during ageing process. The precipitation of γ and β phases takes place in a non-uniform manner during heating process, i.e. the γ and β phases are first formed in the interdendritic region, which is caused by the inhomogeneous distribution of Mg atoms in the solid solution solidified under high pressure. Peak splitting of X-ray diffraction patterns of Al(Mg) solid solution appears, and then disappears when the samples are aged at 423 K for different times, due to the non-uniform precipitation in Al–Mg solid solution. The direct transformation from the γ to β phase is observed after ageing at 423 K for 24 h. It is considered that the β phase is formed through a peritectoid reaction of α + γ → β which needs the diffusion of Mg atoms across the interface of α/γ phases. - Highlights: • The γ phase is formed and the β′ phase is be observed in Al(Mg) solid solution. • Peak splitting of XRD pattern of Al(Mg) solid solution appears during aged at 150 °C. • The β phase is formed through a peritectoid reaction of α + γ → β

  3. Ab initio Thermodynamic Approach to Identify Mixed Solid Sorbents for CO2 Capture Technology

    Yuhua eDuan

    2015-10-01

    Full Text Available Because the current technologies for capturing CO2 are still too energy intensive, new materials must be developed that can capture CO2 reversibly with acceptable energy costs. At a given CO2 pressure, the turnover temperature (Tt of the reaction of an individual solid that can capture CO2 is fixed. Such Tt may be outside the operating temperature range (ΔTo for a practical capture technology. To adjust Tt to fit the practical ΔTo, in this study, three scenarios of mixing schemes are explored by combining thermodynamic database mining with first principles density functional theory and phonon lattice dynamics calculations. Our calculated results demonstrate that by mixing different types of solids, it’s possible to shift Tt to the range of practical operating temperature conditions. According to the requirements imposed by the pre- and post- combustion technologies and based on our calculated thermodynamic properties for the CO2 capture reactions by the mixed solids of interest, we were able to identify the mixing ratios of two or more solids to form new sorbent materials for which lower capture energy costs are expected at the desired pressure and temperature conditions.

  4. Computationally efficient and quantitatively accurate multiscale simulation of solid-solution strengthening by ab initio calculation

    Ma, Duancheng; Friák, Martin; Pezold, Johann von; Raabe, Dierk; Neugebauer, Jörg

    2015-01-01

    We propose an approach for the computationally efficient and quantitatively accurate prediction of solid-solution strengthening. It combines the 2-D Peierls–Nabarro model and a recently developed solid-solution strengthening model. Solid-solution strengthening is examined with Al–Mg and Al–Li as representative alloy systems, demonstrating a good agreement between theory and experiments within the temperature range in which the dislocation motion is overdamped. Through a parametric study, two guideline maps of the misfit parameters against (i) the critical resolved shear stress, τ 0 , at 0 K and (ii) the energy barrier, ΔE b , against dislocation motion in a solid solution with randomly distributed solute atoms are created. With these two guideline maps, τ 0 at finite temperatures is predicted for other Al binary systems, and compared with available experiments, achieving good agreement

  5. Face-centered-cubic Nb-Si solid solutions produced by picosecond pulsed laser quenching

    Wang, W.K.; Spaepen, F.

    1985-01-01

    Face-centered-cubic Nb/sub 100-x/Si/sub x/ solid solutions (10 2 . The lattice parameters of these solutions suggest that the solute atoms can be interstitial or substitutional, probably as a result of a change in the quenching conditions

  6. Nanometric solid solutions of the fluorite and perovskite type crystal structures: Synthesis and properties

    Snežana Bošković

    2012-09-01

    Full Text Available In this paper a short review of our results on the synthesis of nanosized CeO2, CaMnO3 and BaCeO3 solid solutions are presented. The nanopowders were prepared by two innovative methods: self propagating room temperature synthesis (SPRT and modified glycine/nitrate procedure (MGNP. Different types of solid solutions with rare earth dopants in concentrations ranging from 0–0.25 mol% were synthesized. The reactions forming solid solutions were studied. In addition, the characteristics of prepared nanopowders, phenomena during sintering and the properties of sintered samples are discussed.

  7. Solubility behaviour of antimony(III) and antimony(V) solids in basic aqueous solutions at 300oC

    Lemire, R.J.; Tosello, N.B.; Halliday, J.D.

    1999-12-01

    The major contributions of the isotopes 122 Sb and 124 Sb to activity transport in a CANDU reactor primary heat transport system (HTS), have been associated with oxygen ingress during reactor shutdown. As part of a program to minimize the release and redeposition of these isotopes, the solubilities of antimony(III) and (V) oxides and salts have been measured in basic solutions at temperatures from 25 to 300 o C. The results provide information on the charge and the stability as a function of temperature of antimony solution species and, hence, a guide to the trends in the temperature dependence of the solubilities of antimony solids. In solutions in which oxidation of antimony(III) to antimony(V) is minimized, the solubility of Sb 2 O 3 increases by about two orders of magnitude between 25 and 200 o C, and then levels out or decreases slightly. At 250 o C, in oxidizing solutions, Sb 2 O 5 ·xH 2 O and simple sodium antimonate(V) were found to be unstable in sodium hydroxide solutions with respect to the solid, Na 2α [H(H 2 O)] 2-2α Sb 2 O 6 , which has a pyrochlore structure. The solubility of this partially protonated sodium antimonate increases from 25 to 200 o C and decreases at temperatures above 250 o C. These solubility changes for the antimony (V) solids reflect changes in the stability of the anionic antimony solution species (SbO 3 - or Sb(OH) 6 - ), even though the compositions of antimony-containing solids in basic oxidizing solutions are strongly dependent on the cations and their aqueous phase concentrations. All solids used in the present experiments would be expected to generate total solution antimony concentrations ≥ 0.00005 mol·dm -3 in any neutral or basic aqueous solutions (assuming no added sodium salts). Therefore, under HTS conditions, precipitation of any antimony oxides or mixed oxides is unlikely. It cannot be ruled out that hydrated Sb 2 O 5 (especially the pyrochlore form) might be less soluble in near-neutral, low

  8. Towards a unified solution of localization failure with mixed finite elements

    Benedetti, Lorenzo; Cervera, Miguel; Chiumenti, Michele; Zeidler, Antonia; Fischer, Jan-Thomas

    2015-04-01

    interpolations. As a fundamental enhancement of the displacement-pressure formulation above mentioned, this kind of formulation benefits of the following advantages: it provides enhanced rate of convergence for the strain (and stress) and it is able to deal with incompressible situations. The method is completed with constitutive laws from Von Mises and Drucker-Prager local plasticity models with nonlinear strain softening. Moreover, global and local error norms are discussed to support the advantages of the proposed method. Then, numerical examples of stability analysis of slopes are presented to demonstrate the capability of the method. It will be shown that not only soil slopes can be modeled but also snow avalanche release and their weak layer fracture can be similarly treated. Consequently, this formulation appears to be a general and accurate tool for the solution of mechanical problem involving failure with localization bands [3,4]. References [1] Y.R. Rashid, 'Ultimate strength analysis of prestressed concrete pressure vessels', Nuclear Engineering and Design, Volume 7, Issue 4, April, Pages 334-344, 1968. [2] M. Cervera, M. Chiumenti, D. Di Capua. 'Benchmarking on bifurcation and localization in J 2 plasticity for plane stress and plane strain conditions.' Computer Methods in Applied Mechanics and Engineering, Vol. 241-244, Pages 206-224, 2012. [3] L. Benedetti, M. Cervera, M. Chiumenti. 'Stress-accurate mixed FEM for soil failure under shallow foundations involving strain localization in plasticity' Computers and Geotechnics, Vol. 64, pp. 32-47, 2015. [4] Cervera, M., Chiumenti, M., Benedetti, L., Codina, R. 'Mixed stabilized finite element methods in nonlinear solid mechanics. Part III: Compressible and incompressible plasticity' Computer Methods in Applied Mechanics and Engineering, to appear, 2015.

  9. Training Course of Experimental Chemistry in the Nuclear Fuel Cycle: Solid State and Solution Chemistry

    Lee, Ju hyeong; Park, Kwangheon; Kim, Tae hoon; Park, Hyoung gyu; Kim, Jisu [Kyunghee University, Yongin (Korea, Republic of); Song, Hyuk jin [Dongguk University, Gyeongju (Korea, Republic of); Lee, Chan ki; Kang, Do kyu; Jeong, Hyeon jun [UNIST, Ulsan (Korea, Republic of)

    2016-10-15

    In this experimental study program in Tohoku University, basic experiments were done by the participants. First one is the hydrogen reduction experiment of the mixture of UO{sub 2} and ZrO{sub 2}. Second one is to observe microscopic structure of solid solution of UO{sub 2} and ZrO{sub 2} using SEM/EDX and XRD system, simulated fuel debris. Third one is milking process of {sup 239}Np from {sup 243}Am by solvent extraction using Tri-n-Octylamine (TOA). Last one is solvent extraction in PUREX by the simulated mixed aqueous solution of U, {sup 85}Sr and {sup 239}Np which is represented minor actinide elements included in the spent nuclear fuel. Uranium is separated from aqueous phase to organic phase during solvent extraction procedure using TBP and dodecane. Also, neptunium can be extracted to organic phase as nitric acid concentration change. The extraction behavior of neptunium is different by oxidation state in aqueous phase. The behavior of neptunium is represented as a combined form of these oxidation states in experiment. Therefore, because the oxidation states of neptunium can be controlled by controlling the concentration of nitric acid, the extractability of neptunium can be controlled.

  10. Effects of turbulent hyporheic mixing on reach-scale solute transport

    Roche, K. R.; Li, A.; Packman, A. I.

    2017-12-01

    Turbulence rapidly mixes solutes and fine particles into coarse-grained streambeds. Both hyporheic exchange rates and spatial variability of hyporheic mixing are known to be controlled by turbulence, but it is unclear how turbulent mixing influences mass transport at the scale of stream reaches. We used a process-based particle-tracking model to simulate local- and reach-scale solute transport for a coarse-bed stream. Two vertical mixing profiles, one with a smooth transition from in-stream to hyporheic transport conditions and a second with enhanced turbulent transport at the sediment-water interface, were fit to steady-state subsurface concentration profiles observed in laboratory experiments. The mixing profile with enhanced interfacial transport better matched the observed concentration profiles and overall mass retention in the streambed. The best-fit mixing profiles were then used to simulate upscaled solute transport in a stream. Enhanced mixing coupled in-stream and hyporheic solute transport, causing solutes exchanged into the shallow subsurface to have travel times similar to the water column. This extended the exponential region of the in-stream solute breakthrough curve, and delayed the onset of the heavy power-law tailing induced by deeper and slower hyporheic porewater velocities. Slopes of observed power-law tails were greater than those predicted from stochastic transport theory, and also changed in time. In addition, rapid hyporheic transport velocities truncated the hyporheic residence time distribution by causing mass to exit the stream reach via subsurface advection, yielding strong exponential tempering in the in-stream breakthrough curves at the timescale of advective hyporheic transport through the reach. These results show that strong turbulent mixing across the sediment-water interface violates the conventional separation of surface and subsurface flows used in current models for solute transport in rivers. Instead, the full distribution of

  11. Excess Gibbs Energy for Ternary Lattice Solutions of Nonrandom Mixing

    Jung, Hae Young [DukSung Womens University, Seoul (Korea, Republic of)

    2008-12-15

    It is assumed for three components lattice solution that the number of ways of arranging particles randomly on the lattice follows a normal distribution of a linear combination of N{sub 12}, N{sub 23}, N{sub 13} which are the number of the nearest neighbor interactions between different molecules. It is shown by random number simulations that this assumption is reasonable. From this distribution, an approximate equation for the excess Gibbs energy of three components lattice solution is derived. Using this equation, several liquid-vapor equilibria are calculated and compared with the results from other equations.

  12. Existence of Solutions of Abstract Nonlinear Mixed Functional Integrodifferential equation with nonlocal conditions

    Dhakne Machindra B.

    2017-04-01

    Full Text Available In this paper we discuss the existence of mild and strong solutions of abstract nonlinear mixed functional integrodifferential equation with nonlocal condition by using Sadovskii’s fixed point theorem and theory of fractional power of operators.

  13. Alloying Solid Solution Strengthening of Fe-Ga Alloys: A First-Principle Study

    Chen, Kuiying; Cheng, Leon M

    2006-01-01

    ... and Co in cubic solid solution of Fe-Ga alloys. Mayer bond order "BO" values were used to evaluate the atomic bond strengths in the alloys, and were then used to assess the alloying strengthening characteristics...

  14. The growth and tensile deformation behavior of the silver solid solution phase with zinc

    Wu, Jiaqi; Lee, Chin C.

    2016-01-01

    The growth of homogeneous silver solid solution phase with zinc are conducted at two different compositions. X-ray diffraction (XRD) and Scanning electron microscope/Energy dispersive X-ray spectroscopy (SEM/EDX) are carried out for phase identification and chemical composition verification. The mechanical properties of silver solid solution phase with zinc are evaluated by tensile test. The engineering and true stress vs. strain curves are presented and analyzed, with those of pure silver in comparison. According to the experimental results, silver solid solution phase with zinc at both compositions show tempered yield strength, high tensile strength and large uniform strain compared to those of pure silver. Fractography further confirmed the superior ductility of silver solid solution phase with zinc at both compositions. Our preliminary but encouraging results may pave the way for the silver based alloys to be applied in industries such as electronic packaging and structure engineering.

  15. Investigation into mixing capability and solid dispersion preparation using the DSM Xplore Pharma Micro Extruder.

    Sakai, Toshiro; Thommes, Markus

    2014-02-01

    The goal of this investigation was to qualify the DSM Xplore Pharma Micro Extruder as a formulation screening tool for early-stage hot-melt extrusion. Dispersive and distributive mixing was investigated using soluplus, copovidone or basic butylated methacrylate copolymer with sodium chloride (NaCl) in a batch size of 5 g. Eleven types of solid dispersions were prepared using various drugs and carriers in batches of 5 g in accordance with the literature. The dispersive mixing was a function of screw speed and recirculation time and the particle size was remarkably reduced after 1 min of processing, regardless of the polymers. An inverse relationship between the particle size and specific mechanical energy (SME) was also found. The SME values were higher than those in large-scale extruders. After 1 min recirculation at 200 rpm, the uniformity of NaCl content met the criteria of the European Pharmacopoeia, indicating that distributive mixing was achieved in this time. For the solid dispersions preparations, the results from different scanning calorimetry, powder X-ray diffractometry and in-vitro dissolution tests confirmed that all solid-dispersion systems were successfully prepared. These findings demonstrated that the extruder is a useful tool to screen solid-dispersion formulations and their material properties on a small scale. © 2013 Royal Pharmaceutical Society.

  16. Phase relations and Gibbs energies of spinel phases and solid solutions in the system Mg-Rh-O

    Jacob, K.T., E-mail: katob@materials.iisc.ernet.in [Department of Materials Engineering, Indian Institute of Science, Bangalore 560 012 (India); Prusty, Debadutta [Department of Materials Engineering, Indian Institute of Science, Bangalore 560 012 (India); Kale, G.M. [Institute for Materials Research, University of Leeds, Leeds, LS2 9JT (United Kingdom)

    2012-02-05

    Highlights: Black-Right-Pointing-Pointer Refinement of phase diagram for the system Mg-Rh-O and thermodynamic data for spinel compounds MgRh{sub 2}O{sub 4} and Mg{sub 2}RhO{sub 4} is presented. Black-Right-Pointing-Pointer A solid-state electrochemical cell is used for thermodynamic measurement. Black-Right-Pointing-Pointer An advanced design of the solid-state electrochemical cell incorporating buffer electrodes is deployed to minimize polarization of working electrode. Black-Right-Pointing-Pointer Regular solution model for the spinel solid solution MgRh{sub 2}O{sub 4} - Mg{sub 2}RhO{sub 4} based on ideal mixing of cations on the octahedral site is proposed. Black-Right-Pointing-Pointer Factors responsible for stabilization of tetravalent rhodium in spinel compounds are identified. - Abstract: Pure stoichiometric MgRh{sub 2}O{sub 4} could not be prepared by solid state reaction from an equimolar mixture of MgO and Rh{sub 2}O{sub 3} in air. The spinel phase formed always contained excess of Mg and traces of Rh or Rh{sub 2}O{sub 3}. The spinel phase can be considered as a solid solution of Mg{sub 2}RhO{sub 4} in MgRh{sub 2}O{sub 4}. The compositions of the spinel solid solution in equilibrium with different phases in the ternary system Mg-Rh-O were determined by electron probe microanalysis. The oxygen potential established by the equilibrium between Rh + MgO + Mg{sub 1+x}Rh{sub 2-x}O{sub 4} was measured as a function of temperature using a solid-state cell incorporating yttria-stabilized zirconia as an electrolyte and pure oxygen at 0.1 MPa as the reference electrode. To avoid polarization of the working electrode during the measurements, an improved design of the cell with a buffer electrode was used. The standard Gibbs energies of formation of MgRh{sub 2}O{sub 4} and Mg{sub 2}RhO{sub 4} were deduced from the measured electromotive force (e.m.f.) by invoking a model for the spinel solid solution. The parameters of the model were optimized using the measured

  17. Colloidal quantum dot solids for solution-processed solar cells

    Yuan, Mingjian; Liu, Mengxia; Sargent, Edward H.

    2016-01-01

    Solution-processed photovoltaic technologies represent a promising way to reduce the cost and increase the efficiency of solar energy harvesting. Among these, colloidal semiconductor quantum dot photovoltaics have the advantage of a spectrally

  18. Computationally efficient and quantitatively accurate multiscale simulation of solid-solution strengthening by ab initio calculation

    Ma, D.; Friák, Martin; von Pezold, J.; Raabe, D.; Neugebauer, J.

    2015-01-01

    Roč. 85, FEB (2015), s. 53-66 ISSN 1359-6454 Institutional support: RVO:68081723 Keywords : Solid-solution strengthening * DFT * Peierls–Nabarro model * Ab initio * Al alloys Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 5.058, year: 2015

  19. Formation of solid solution during mutual diffusion of tungsten and molybdenum in the process of sintering

    Timofeeva, A.A.; Bulat, I.B.; Voronin, Yu.V.; Fedoseev, G.K.; Karasev, V.M.

    1984-01-01

    A process of a solid solution homogenization during sintering of W-15Mo and W-5Mo alloys is studied by the methods of density measurements, analysis of the X-ray lines physical broadening and determination of crystalline lattice constant. Study of the process of solid solution formation under conditions of powder composite sintering is shown to be conducted with account of peculiarities of tungsten and molybdenum mutual diffusion in the investigated temperature range of concentrations

  20. Modelling solid solutions with cluster expansion, special quasirandom structures, and thermodynamic approaches

    Saltas, V.; Horlait, D.; Sgourou, E. N.; Vallianatos, F.; Chroneos, A.

    2017-12-01

    Modelling solid solutions is fundamental in understanding the properties of numerous materials which are important for a range of applications in various fields including nanoelectronics and energy materials such as fuel cells, nuclear materials, and batteries, as the systematic understanding throughout the composition range of solid solutions for a range of conditions can be challenging from an experimental viewpoint. The main motivation of this review is to contribute to the discussion in the community of the applicability of methods that constitute the investigation of solid solutions computationally tractable. This is important as computational modelling is required to calculate numerous defect properties and to act synergistically with experiment to understand these materials. This review will examine in detail two examples: silicon germanium alloys and MAX phase solid solutions. Silicon germanium alloys are technologically important in nanoelectronic devices and are also relevant considering the recent advances in ternary and quaternary groups IV and III-V semiconductor alloys. MAX phase solid solutions display a palette of ceramic and metallic properties and it is anticipated that via their tuning they can have applications ranging from nuclear to aerospace industries as well as being precursors for particular MXenes. In the final part, a brief summary assesses the limitations and possibilities of the methodologies discussed, whereas there is discussion on the future directions and examples of solid solution systems that should prove fruitful to consider.

  1. Cefuroxime axetil solid dispersions prepared using solution enhanced dispersion by supercritical fluids.

    Jun, Seoung Wook; Kim, Min-Soo; Jo, Guk Hyun; Lee, Sibeum; Woo, Jong Soo; Park, Jeong-Sook; Hwang, Sung-Joo

    2005-12-01

    Cefuroxime axetil (CA) solid dispersions with HPMC 2910/PVP K-30 were prepared using solution enhanced dispersion by supercritical fluids (SEDS) in an effort to increase the dissolution rate of poorly water-soluble drugs. Their physicochemical properties in solid state were characterized by differential scanning calorimeter (DSC), powder X-ray diffraction (PXRD), Fourier transform infrared spectrometry (FT-IR) and scanning electron microscopy. No endothermic and characteristic diffraction peaks corresponding to CA were observed for the solid dispersions in DSC and PXRD. FTIR analysis demonstrated the presence of intermolecular hydrogen bonds between CA and HPMC 2910/PVP K-30 in solid dispersions, resulting in the formation of amorphous or non-crystalline CA. Dissolution studies indicated that the dissolution rates were remarkably increased in solid dispersions compared with those in the physical mixture and drug alone. In conclusion, an amorphous or non-crystalline CA solid dispersion prepared using SEDS could be very useful for the formulation of solid dosage forms.

  2. Mixing effect on thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste

    Ghanimeh, Sophia A.

    2012-08-01

    This paper examines the effect of mixing on the performance of thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste during the start-up phase and in the absence of an acclimated seed. For this purpose, two digesters were used under similar starting conditions and operated for 235days with different mixing schemes. While both digesters exhibited a successful startup with comparable specific methane yield of 0.327 and 0.314l CH 4/gVS, continuous slow stirring improved stability by reducing average VFA accumulation from 2890 to 825mg HAc/l, propionate content from 2073 to 488mg/l, and VFA-to-alkalinity ratio from 0.32 to 0.07. As a result, the startup with slow mixing was faster and smoother accomplishing a higher loading capacity of 2.5gVS/l/d in comparison to 1.9gVS/l/d for non-mixing. Mixing equally improved microbial abundance from 6.6 to 10gVSS/l and enhanced solids and soluble COD removal. © 2012 Elsevier Ltd.

  3. Mixing effect on thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste

    Ghanimeh, Sophia A.; El-Fadel, Mutasem E.; Saikaly, Pascal

    2012-01-01

    This paper examines the effect of mixing on the performance of thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste during the start-up phase and in the absence of an acclimated seed. For this purpose, two digesters were used under similar starting conditions and operated for 235days with different mixing schemes. While both digesters exhibited a successful startup with comparable specific methane yield of 0.327 and 0.314l CH 4/gVS, continuous slow stirring improved stability by reducing average VFA accumulation from 2890 to 825mg HAc/l, propionate content from 2073 to 488mg/l, and VFA-to-alkalinity ratio from 0.32 to 0.07. As a result, the startup with slow mixing was faster and smoother accomplishing a higher loading capacity of 2.5gVS/l/d in comparison to 1.9gVS/l/d for non-mixing. Mixing equally improved microbial abundance from 6.6 to 10gVSS/l and enhanced solids and soluble COD removal. © 2012 Elsevier Ltd.

  4. Contribution to the study of the structure of silver krypton solid solutions; Contribution a l'etude de la structure des solutions solides argent-krypton

    Levy, V; Tullairet, J; Delaplace, J; Antolin-Baudier, J; Adda, Y [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The silver-krypton solid solutions formed by electrical discharge have been studied by X-rays, electrical resistivity and electronic transmission microscopy. The crystalline parameter and residual resistivity measurements have shown that the krypton atom behaves very differently to those of other elements of the periodic classification when dissolved in silver. The recovery of the crystalline parameter and of the electrical resistivity has been studied as a function of temperature. (authors) [French] Les solutions solides argent, krypton, realisees par decharges electrique ont ete etudiees par Rayons X, resistivite electrique et microscopie electronique en transmission. Les mesures de parametre cristallin et de resistivite residuelle ont montre que le comportement de l'atome de krypton est tres different de celui des autres elements de la classification periodique en solution dans l'argent. La restauration du parametre cristallin et de la resistivite electrique en fonction de la temperature a ete etudiee. (auteurs)

  5. Precipitation of Nd-Ca carbonate solid solution at 25 degrees C

    Carroll, S.A.

    1993-01-01

    The formation of a Nd-Ca carbonate solid solution was studied by monitoring the reactions of calcite with aqueous Nd, orthorhombic NdOHCO 3 (s) with aqueous Ca, and calcite with hexagonal Nd-carbonate solid phase as a function of time at 25 degrees C and controlled pCO 2 (g). All experiments reached steady state after 200 h of reaction. The dominant mechanism controlling the formation of the solid solution was precipitation of a Nd-Ca carbonate phase from the bulk solution as individual crystals or at the orthorhombic NdOHCO 3 (s)-solution interface. The lack of Nd adsorption or solid solution at the calcite-solution interface suggests that the solid solution was orthorhombic and may be modeled as a mixture of orthorhombic NdOHCO 3 (s) and aragonite. Orthorhombic NdOHCO 3 (s) was determined to be the stable Nd-carbonate phase in the Nd-CO 2 -H 2 O system at pCO 2 (g) 0.1 atmospheres at 25 degrees C. The equilibrium constant corrected to zero ionic strength for orthorhombic NdOHCO 3 (s) solubility is 10 10.41(±0.29) for the following: NdOHCO 3 (s) + 3H + = Nd 3+ + CO 2 (g) + H 2 O. Results are discussed in relation to radioactive waste disposal by burial, and specifically in relation to americium chemistry

  6. The effect of mixing on fermentation of primary solids, glycerol, and biodiesel waste.

    Ghasemi, Marzieh; Randall, Andrew A

    2018-03-01

    In this study, the effect of mixing on volatile fatty acid (VFA) production and composition was investigated through running five identical bench-scale reactors that were filled with primary solid and dosed with either pure glycerol or biodiesel waste. Experimental results revealed that there was an inverse correlation between the mixing intensity and the VFA production. The total VFA production in the un-mixed reactor was 9,787 ± 3,601 mg COD/L, whereas in the reactor mixed at 100 rpm this dropped to 3,927 ± 1,175 mg COD/L, while both types of reactor were dosed with pure glycerol at the beginning of each cycle to reach the initial concentration of 1,000 mg/L (1,217 mg COD/L). Propionic acid was the dominant VFA in all the reactors except the reactor mixed at 30 rpm. It is hypothesized that low mixing facilitated hydrogen transfer between obligate hydrogen producing acetogens (OHPA) and hydrogen consuming acidogens in these non-methanogenic reactors. Also, in a narrower range of mixing (0 or 7 rpm), the total VFA production in biodiesel waste-fed reactors was considerably higher than that of pure glycerol-fed reactors.

  7. Multiferroic properties in NdFeO3-PbTiO3 solid solutions

    Kumar, Sunil; Pal, Jaswinder; Kaur, Shubhpreet; Agrawal, P.; Singh, Mandeep; Singh, Anupinder

    2018-05-01

    The x(NdFeO3) - 1-x(PbTiO3) where x = 0.2 solid solution was prepared using solid state reaction route. The X-ray diffraction (XRD) data reveals the single phase formation. The microstructure shows grain growth with lesser porosity. The energy dispersive analysis confirms the presence of elements in stochiometric proportion. The polarization vs. Electric field loop estabilished a ferroelectric type behavior but lossy in nature. This lossy nature may be due to the presence of large leakage current in solid solution. The Magnetization vs. Magnetic field plot exhibits a unsaturated hysteriss loop indicates that the sample is not purely ferromagnetic.

  8. Municipal solid waste management. Strategies and technologies for sustainable solutions

    Ludwig, C.; Hellweg, S.; Stucki, S. (eds.)

    2002-10-01

    The way municipal solid waste is handled greatly determines its impact on the local as well as the global environment. New technologies habe emerged for the treatment of waste, for the recovery of raw materials and energy, and for safe final disposal. The environmental performance of technologies, their social acceptance and their economic viability are key issues to be considered in sustainable waste management. This book provides an overview of current practices in waste management and a synthesis of new developments achieved through interdisciplinary discussions of recent research results. (orig.)

  9. Three-dimensional simulation of grain mixing in three different rotating drum designs for solid-state fermentation

    Schutyser, M.A.I.; Weber, F.J.; Briels, W.J.; Boom, R.M.; Rinzema, A.

    2002-01-01

    A previously published two-dimensional discrete particle simulation model for radial mixing behavior of various slowly rotating drums for solid-state fermentation (SSF) has been extended to a three-dimensional model that also predicts axial mixing. Radial and axial mixing characteristics were

  10. Subdiffusion kinetics of nanoprecipitate growth and destruction in solid solutions

    Sibatov, R. T.; Svetukhin, V. V.

    2015-06-01

    Based on fractional differential generalizations of the Ham and Aaron-Kotler precipitation models, we study the kinetics of subdiffusion-limited growth and dissolution of new-phase precipitates. We obtain the time dependence of the number of impurities and dimensions of new-phase precipitates. The solutions agree with the Monte Carlo simulation results.

  11. Influence of mixing and solid concentration on sodium bicarbonate secondary nucleation rate in stirred tank

    Wylock, C.; Debaste, F.; Haut, B. [Transfers, Interfaces and Processes - Chemical Engineering Unit, ULB, Brussels (Belgium); Gutierrez, V.; Delplancke-Ogletree, M.P. [Chemicals and Materials Department, ULB, Brussels (Belgium); Cartage, T. [Solvay SA, Brussels (Belgium)

    2010-09-15

    This work aims to investigate the influence of the solid concentration in suspension on the contact secondary nucleation rate of sodium bicarbonate crystallization in a stirred tank crystallizer and to show the necessity of a local description of the mixing for a nucleation rate influence study. Experiments and computational fluid dynamics (CFD) simulations are realized. Crystallization kinetic parameters are extracted from experimental data using a mass distribution fitting approach. CFD and the experimental results allow identifying that a mixing property correlated with the measurements of the secondary nucleation rate in the stirred tank crystallizer appears to be the turbulent dissipation rate on the edge of the impeller. Its influence and the influence of the solid concentration in the suspension on the secondary nucleation rate are estimated by the evaluation of their exponents in a kinetic law. The obtained exponent values are then discussed qualitatively. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. New results of almost periodic solutions for cellular neural networks with mixed delays

    Zhao Weirui; Zhang Huanshui

    2009-01-01

    In this paper, for cellular neural networks with mixed delays, we prove some new results on the existence of almost periodic solutions by contraction principle. The global exponential stability of almost periodic solutions is discussed further, and conditions for exponential convergence are given. The conditions we obtained are weaker than the previously known ones and can be easily reduced to several special cases.

  13. Existence of solutions for nonlinear mixed type integrodifferential equation of second order

    Haribhau Laxman Tidke

    2010-04-01

    Full Text Available In this paper, we investigate the existence of solutions for nonlinear mixed Volterra-Fredholm integrodifferential equation of second order with nonlocal conditions in Banach spaces. Our analysis is based on Leray-Schauder alternative, rely on a priori bounds of solutions and the inequality established by B. G. Pachpatte.

  14. Distributed mixed-integer fuzzy hierarchical programming for municipal solid waste management. Part I: System identification and methodology development.

    Cheng, Guanhui; Huang, Guohe; Dong, Cong; Xu, Ye; Chen, Xiujuan; Chen, Jiapei

    2017-03-01

    Due to the existence of complexities of heterogeneities, hierarchy, discreteness, and interactions in municipal solid waste management (MSWM) systems such as Beijing, China, a series of socio-economic and eco-environmental problems may emerge or worsen and result in irredeemable damages in the following decades. Meanwhile, existing studies, especially ones focusing on MSWM in Beijing, could hardly reflect these complexities in system simulations and provide reliable decision support for management practices. Thus, a framework of distributed mixed-integer fuzzy hierarchical programming (DMIFHP) is developed in this study for MSWM under these complexities. Beijing is selected as a representative case. The Beijing MSWM system is comprehensively analyzed in many aspects such as socio-economic conditions, natural conditions, spatial heterogeneities, treatment facilities, and system complexities, building a solid foundation for system simulation and optimization. Correspondingly, the MSWM system in Beijing is discretized as 235 grids to reflect spatial heterogeneity. A DMIFHP model which is a nonlinear programming problem is constructed to parameterize the Beijing MSWM system. To enable scientific solving of it, a solution algorithm is proposed based on coupling of fuzzy programming and mixed-integer linear programming. Innovations and advantages of the DMIFHP framework are discussed. The optimal MSWM schemes and mechanism revelations will be discussed in another companion paper due to length limitation.

  15. Influence of isotopic disorder on solid state amorphization and polyamorphism in solid H2O -D2O solutions

    Gromnitskaya, E. L.; Danilov, I. V.; Lyapin, A. G.; Brazhkin, V. V.

    2015-10-01

    We present a low-temperature and high-pressure ultrasonic study of elastic properties of isotopic H2O-D2O solid solutions, comparing their properties with those of the isotopically pure H2O and D2O ices. Measurements were carried out for solid state amorphization (SSA) from 1h to high-density amorphous (HDA) ice upon compression up to 1.8 GPa at 77 K and for the temperature-induced (77 -190 K ) u-HDA (unrelaxed HDA) → e-HDA (expanded HDA) → low-density amorphous (LDA )→1 c cascade of ice transformations near room pressure. There are many similarities in the elasticity behaviour of H2O ,D2O , and H2O-D2O solid solutions, including the softening of the shear elastic modulus as a precursor of SSA and the HDA →LDA transition. We have found significant isotopic effects during H/D substitution, including elastic softening of H2O -D2O solid solutions with respect to the isotopically pure ices in the case of the bulk moduli of ices 1c and 1h and for both bulk and shear elastic moduli of HDA ice at high pressures (>1 GPa ) . This softening is related to the configurational isotopic disorder in the solid solutions. At low pressures, the isotope concentration dependence of the elastic moduli of u-HDA ice changes remarkably and becomes monotonic with pronounced change of the bulk modulus (≈20 %) .

  16. The Systematics of Activity-Composition Relations in Mg-Fe2+ Oxide and Silicate Solid Solutions

    O'Neill, H. S.

    2006-12-01

    The need to quantify activity-composition relations of mineral solid solutions for petrologic modelling has prompted many experimental studies, but different studies on the same system often appear to show a startling lack of consistency. A good example is Mg-Fe2+ mixing in garnet (the pyrope-almandine join). This is understandable because the energies of mixing in solid solutions are often obtained experimentally as small difference between large numbers. In particular, the fallacy of using a sequential approach to data fitting to a thermodynamic model leads to the accumulated errors being artificially concentrated onto the last step of the fitting process, which is usually that part of the model dealing with the excess energies of mixing. This gives rise to erroneous activity-composition relations, often apparently showing complex deviations from ideality. Systemizing the results of many studies can reveal underlying patterns of behaviour while also identifying outliers and anomalies that may be worth reinvestigating. Davies and Navrotsky [1] showed that the energies of mixing of many different pairs of ions with the same charge correlated well with the difference in molar volumes of the end-members, within a particular crystal structure. This empirical work is now supported by theoretical calculations. It underlies the modern approach to melt/crystal trace-element partitioning. Provided an internally consistent dataset is used, an analogous correlation may be demonstrated across different crystal structures for the mixing of one pair of ions, such as Mg and Fe2+. Activity-composition relations in MgO-"FeO" magnesiowuestite solutions in equilibrium with iron metal were used to obtain the properties of Mg-Fe olivine solutions from magnesiowuestite/olivine partitioning [2]. New results at 1400 K, 1 bar and 1473 K, 25 kb (O'Neill and Pownceby, in prep.) confirm previous work that mixing in Mg-Fe olivine is regular (symmetrical) with W Mg-Fe = 2.5 kJ/mol, with an

  17. Bench-scale feasibility testing of pulsed-air technology for in-tank mixing of dry cementitious solids with tank liquids and settled solids

    Whyatt, G.A.; Hymas, C.R.

    1997-09-01

    This report documents the results of testing performed to determine the feasibility of using a pulsed-air mixing technology (equipment developed by Pulsair Systems, Inc., Bellevue, WA) to mix cementitious dry solids with supernatant and settled solids within a horizontal tank. The mixing technology is being considered to provide in situ stabilization of the open-quotes Vclose quotes tanks at the Idaho National Engineering and Environmental Laboratory (INEEL). The testing was performed in a vessel roughly 1/6 the scale of the INEEL tanks. The tests used a fine soil to simulate settled solids and water to simulate tank supernatants. The cementitious dry materials consisted of Portland cement and Aquaset-2H (a product of Fluid Tech Inc. consisting of clay and Portland cement). Two scoping tests were conducted to allow suitable mixing parameters to be selected. The scoping tests used only visual observations during grout disassembly to assess mixing performance. After the scoping tests indicated the approach may be feasible, an additional two mixing tests were conducted. In addition to visual observations during disassembly of the solidified grout, these tests included addition of chemical tracers and chemical analysis of samples to determine the degree of mixing uniformity achieved. The final two mixing tests demonstrated that the pulsed-air mixing technique is capable of producing slurries containing substantially more cementitious dry solids than indicated by the formulations suggested by INEEL staff. Including additional cement in the formulation may have benefits in terms of increasing mobilization of solids, reducing water separation during curing, and increasing the strength of the solidified product. During addition to the tank, the cementitious solids had a tendency to form clumps which broke down with continued mixing

  18. Colloidal quantum dot solids for solution-processed solar cells

    Yuan, Mingjian

    2016-02-29

    Solution-processed photovoltaic technologies represent a promising way to reduce the cost and increase the efficiency of solar energy harvesting. Among these, colloidal semiconductor quantum dot photovoltaics have the advantage of a spectrally tuneable infrared bandgap, which enables use in multi-junction cells, as well as the benefit of generating and harvesting multiple charge carrier pairs per absorbed photon. Here we review recent progress in colloidal quantum dot photovoltaics, focusing on three fronts. First, we examine strategies to manage the abundant surfaces of quantum dots, strategies that have led to progress in the removal of electronic trap states. Second, we consider new device architectures that have improved device performance to certified efficiencies of 10.6%. Third, we focus on progress in solution-phase chemical processing, such as spray-coating and centrifugal casting, which has led to the demonstration of manufacturing-ready process technologies.

  19. An analytical solution for the Marangoni mixed convection boundary layer flow

    Moghimi, M. A.; Kimiaeifar, Amin; Rahimpour, M.

    2010-01-01

    In this article, an analytical solution for a Marangoni mixed convection boundary layer flow is presented. A similarity transform reduces the Navier-Stokes equations to a set of nonlinear ordinary differential equations, which are solved analytically by means of the homotopy analysis method (HAM...... the convergence of the solution. The numerical solution of the similarity equations is developed and the results are in good agreement with the analytical results based on the HAM....

  20. Updating and testing of a Finnish method for mixed municipal solid waste composition studies.

    Liikanen, M; Sahimaa, O; Hupponen, M; Havukainen, J; Sorvari, J; Horttanainen, M

    2016-06-01

    More efficient recycling of municipal solid waste (MSW) is an essential precondition for turning Europe into a circular economy. Thus, the recycling of MSW must increase significantly in several member states, including Finland. This has increased the interest in the composition of mixed MSW. Due to increased information needs, a method for mixed MSW composition studies was introduced in Finland in order to improve the national comparability of composition study results. The aim of this study was to further develop the method so that it corresponds to the information needed about the composition of mixed MSW and still works in practice. A survey and two mixed MSW composition studies were carried out in the study. According to the responses of the survey, the intensification of recycling, the landfill ban on organic waste and the producer responsibility for packaging waste have particularly influenced the need for information about the composition of mixed MSW. The share of biowaste in mixed MSW interested the respondents most. Additionally, biowaste proved to be the largest waste fraction in mixed MSW in the composition studies. It constituted over 40% of mixed MSW in both composition studies. For these reasons, the classification system of the method was updated by further defining the classifications of biowaste. The classifications of paper as well as paperboard and cardboard were also updated. The updated classification system provides more information on the share of avoidable food waste and waste materials suitable for recycling in mixed MSW. The updated method and the information gained from the composition studies are important in ensuring that the method will be adopted by municipal waste management companies and thus used widely in Finland. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Thermal conductivities of (ZrxPu(1-x)/2Am(1-x)/2)N solid solutions

    Nishi, Tsuyoshi; Takano, Masahide; Akabori, Mitsuo; Arai, Yasuo

    2011-01-01

    The thermal conductivity of Zr-based transuranium (TRU) nitride solid solutions is important for designing subcritical cores in nitride-fueled ADS. Some results have been reported concerning the thermal conductivities of (Zr,Pu)N. However, there have been no experimental data on the thermal conductivities of Zr-based nitride solid solutions containing MA. In this study, the authors prepared sintered samples of (Zr x Pu (1-x)/2 Am (1-x)/2) N (x=0.0, 0.58, 0.80) solid solutions. The thermal diffusivity and heat capacity of (Zr x Pu (1-x)/2 Am (1-x)/2) N solid solutions were measured using a laser flash method and drop calorimetry, respectively. Thermal conductivities were determined from the measured thermal diffusivities, heat capacities and bulk densities over a temperature range of 473 to 1473 K. The thermal conductivities of (Zr 0.58 Pu 0.21 Am 0.21 )N and (Zr 0.80 Pu 0.10 Am 0.10 )N solid solutions were found to be higher than that of (Pu 0.5 Am 0.5 )N due to the high thermal conductivity of ZrN as the principal component, although they were lower than that of ZrN due to the impurifying effect of the transuranium elements. Thus, the thermal conductivities of (Zr x Pu (1-x)/2 Am (1-x)/2) N solid solutions increased with increasing ZrN concentration. Moreover, in order to help to promote the design study of nitride-fueled ADS, the thermal conductivity of the (Zr x Pu (1-x)/2 Am (1-x)/2) N solid solutions were fitted to an equation using the least squares method. (author)

  2. Computational Modeling of Mixed Solids for CO2 CaptureSorbents

    Duan, Yuhua

    2015-01-01

    Since current technologies for capturing CO2 to fight global climate change are still too energy intensive, there is a critical need for development of new materials that can capture CO2 reversibly with acceptable energy costs. Accordingly, solid sorbents have been proposed to be used for CO2 capture applications through a reversible chemical transformation. By combining thermodynamic database mining with first principles density functional theory and phonon lattice dynamics calculations, a theoretical screening methodology to identify the most promising CO2 sorbent candidates from the vast array of possible solid materials has been proposed and validated. The calculated thermodynamic properties of different classes of solid materials versus temperature and pressure changes were further used to evaluate the equilibrium properties for the CO2 adsorption/desorption cycles. According to the requirements imposed by the pre- and post- combustion technologies and based on our calculated thermodynamic properties for the CO2 capture reactions by the solids of interest, we were able to screen only those solid materials for which lower capture energy costs are expected at the desired pressure and temperature conditions. Only those selected CO2 sorbent candidates were further considered for experimental validations. The ab initio thermodynamic technique has the advantage of identifying thermodynamic properties of CO2 capture reactions without any experimental input beyond crystallographic structural information of the solid phases involved. Such methodology not only can be used to search for good candidates from existing database of solid materials, but also can provide some guidelines for synthesis new materials. In this presentation, we apply our screening methodology to mixing solid systems to adjust the turnover temperature to help on developing CO2 capture Technologies.

  3. First-principles thermodynamics study of phase stability in inorganic halide perovskite solid solutions

    Bechtel, Jonathon S.; Van der Ven, Anton

    2018-04-01

    Halide substitution gives rise to a tunable band gap as a function of composition in halide perovskite materials. However, photoinduced phase segregation, observed at room temperature in mixed halide A Pb (IxBr1-x) 3 systems, limits open circuit voltages and decreases photovoltaic device efficiencies. We investigate equilibrium phase stability of orthorhombic P n m a γ -phase CsM (XxY1-x) 3 perovskites where M is Pb or Sn, and X and Y are Br, Cl, or I. Finite-temperature phase diagrams are constructed using a cluster expansion effective Hamiltonian parameterized from first-principles density-functional-theory calculations. Solid solution phases for CsM (IxBr1-x) 3 and CsM (BrxCl1-x) 3 are predicted to be stable well below room temperature while CsM (IxCl1-x) 3 systems have miscibility gaps that extend above 400 K. The height of the miscibility gap correlates with the difference in volume between end members. Also layered ground states are found on the convex hull at x =2 /3 for CsSnBr2Cl ,CsPbI2Br , and CsPbBrCl2. The impact of these ground states on the finite temperature phase diagram is discussed in the context of the experimentally observed photoinduced phase segregation.

  4. Drag reduction behavior of hydrolyzed polyacrylamide/xanthan gum mixed polymer solutions

    Mehdi Habibpour; Peter E.Clark

    2017-01-01

    Partially hydrolyzed polyacrylamide (HPAM) as the main component of slickwater fracturing fluid is a shear-sensitive polymer,which suffers from mechanical degradation at turbulent flow rates.Five different concentrations of HPAM as well as mixtures of polyacrylamide/xanthan gum were prepared to investigate the possibility of improving shear stability of HPAM.Drag reduction (DR)measurements were performed in a closed flow loop.For HPAM solutions,the extent of DR increased from 30% to 67% with increasing HPAM concentration from 100 to 1000 wppm.All the HPAM solutions suffered from mechanical degradation and loss of DR efficiency over the shearing period.Results indicated that the resistance to shear degradation increased with increasing polymer concentration.DR efficiency of 600 wppm xanthan gum (XG)was 38%,indicating that XG was not as good a drag reducer as HPAM.But with only 6% DR decline,XG solution exhibited a better shear stability compared to HPAM solutions.Mixed HPAM/XG solutions initially exhibited greater DR (40% and 55%) compared to XG,but due to shear degradation,DR% dropped for HPAM/XG solutions.Compared to 200 wppm HPAM solution,addition of XG did not improve the drag reduction efficiency of HPAM/XG mixed solutions though XG slightly improved the resistance against mechanical degradation in HPAM/XG mixed polymer solutions.

  5. Uncertainties associated with lacking data for predictions of solid-solution partitioning of metals in soil

    Le, T.T. Yen; Hendriks, A. Jan

    2014-01-01

    Soil properties, i.e., pH and contents of soil organic matter (SOM), dissolved organic carbon (DOC), clay, oxides, and reactive metals, are required inputs to both mechanistic and empirical modeling in assessing metal solid-solution partitioning. Several of these properties are rarely measured in site-specific risk assessment. We compared the uncertainties induced by lacking data on these soil properties in estimating metal soil solution concentrations. The predictions by the Orchestra framework were more sensitive to lacking soil property data than the predictions by the transfer functions. The deviations between soil solution concentrations of Cd, Ni, Zn, Ba, and Co estimated with measured SOM and those estimated with generic SOM by the Orchestra framework were about 10 times larger than the deviations in the predictions by the transfer functions. High uncertainties were induced by lacking data in assessing solid-solution partitioning of oxy-anions like As, Mo, Sb, Se, and V. Deviations associated with lacking data in predicting soil solution concentrations of these metals by the Orchestra framework reached three-to-six orders of magnitude. The solid-solution partitioning of metal cations was strongly influenced by pH and contents of organic matter, oxides, and reactive metals. Deviations of more than two orders of magnitude were frequently observed between the estimates of soil solution concentrations with the generic values of these properties and the estimates based on the measured data. Reliable information on these properties is preferred to be included in the assessment by either the Orchestra framework or transfer functions. - Highlights: • Estimates of metal solid-solution partitioning sensitive to soil property data. • Uncertainty mainly due to lacking reactive metal contents, pH, and organic matter. • Soil solution concentrations of oxy-anions highly influenced by oxide contents. • Clay contents had least effects on solid-solution partitioning

  6. Uncertainties associated with lacking data for predictions of solid-solution partitioning of metals in soil

    Le, T.T. Yen, E-mail: YenLe@science.ru.nl; Hendriks, A. Jan

    2014-08-15

    Soil properties, i.e., pH and contents of soil organic matter (SOM), dissolved organic carbon (DOC), clay, oxides, and reactive metals, are required inputs to both mechanistic and empirical modeling in assessing metal solid-solution partitioning. Several of these properties are rarely measured in site-specific risk assessment. We compared the uncertainties induced by lacking data on these soil properties in estimating metal soil solution concentrations. The predictions by the Orchestra framework were more sensitive to lacking soil property data than the predictions by the transfer functions. The deviations between soil solution concentrations of Cd, Ni, Zn, Ba, and Co estimated with measured SOM and those estimated with generic SOM by the Orchestra framework were about 10 times larger than the deviations in the predictions by the transfer functions. High uncertainties were induced by lacking data in assessing solid-solution partitioning of oxy-anions like As, Mo, Sb, Se, and V. Deviations associated with lacking data in predicting soil solution concentrations of these metals by the Orchestra framework reached three-to-six orders of magnitude. The solid-solution partitioning of metal cations was strongly influenced by pH and contents of organic matter, oxides, and reactive metals. Deviations of more than two orders of magnitude were frequently observed between the estimates of soil solution concentrations with the generic values of these properties and the estimates based on the measured data. Reliable information on these properties is preferred to be included in the assessment by either the Orchestra framework or transfer functions. - Highlights: • Estimates of metal solid-solution partitioning sensitive to soil property data. • Uncertainty mainly due to lacking reactive metal contents, pH, and organic matter. • Soil solution concentrations of oxy-anions highly influenced by oxide contents. • Clay contents had least effects on solid-solution partitioning

  7. Zirconium-cerin solid solutions: thermodynamic model and thermal stability at high temperature; Solutions solides de zirconium dans la cerine: modele thermodynamique et stabilite thermique a haute temperature

    Janvier, C.

    1998-04-02

    The oxides-gaseous dioxygen equilibria and the textural thermal stability of six zirconium-cerin solutions Ce{sub 1-x}Zr{sub x}O{sub 2} (0solid solutions and the gaseous oxygen by thermal gravimetric analysis at 600 degrees Celsius has shown that these solutions have not a ideal behaviour. A thermodynamic model where the point defects of solutions are included describe them the best. It becomes then possible to know the variations of the concentrations of the point defects in terms of temperature, oxygen pressure and zirconium concentration. A kinetic study (by calcination at 950 degrees Celsius of the solid solutions) of the specific surface area decrease has revealed a minima (0

  8. Active Edge Sites Engineering in Nickel Cobalt Selenide Solid Solutions for Highly Efficient Hydrogen Evolution

    Xia, Chuan

    2017-01-06

    An effective multifaceted strategy is demonstrated to increase active edge site concentration in NiCoSe solid solutions prepared by in situ selenization process of nickel cobalt precursor. The simultaneous control of surface, phase, and morphology result in as-prepared ternary solid solution with extremely high electrochemically active surface area (C = 197 mF cm), suggesting significant exposure of active sites in this ternary compound. Coupled with metallic-like electrical conductivity and lower free energy for atomic hydrogen adsorption in NiCoSe, identified by temperature-dependent conductivities and density functional theory calculations, the authors have achieved unprecedented fast hydrogen evolution kinetics, approaching that of Pt. Specifically, the NiCoSe solid solutions show a low overpotential of 65 mV at -10 mV cm, with onset potential of mere 18 mV, an impressive small Tafel slope of 35 mV dec, and a large exchange current density of 184 μA cm in acidic electrolyte. Further, it is shown that the as-prepared NiCoSe solid solution not only works very well in acidic electrolyte but also delivers exceptional hydrogen evolution reaction (HER) performance in alkaline media. The outstanding HER performance makes this solid solution a promising candidate for mass hydrogen production.

  9. Hydrothermal synthesis of pollucite, analcime and their solid solutions and analysis of their properties

    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); Cai, Kunchuan; Li, Yan; Fan, Junjie; Zhang, Yi; Miao, Jiajun; Chen, Yuqian [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)

    2017-05-15

    Pollucite, as a perfect long-term potential host for radioactive Cs immobilization, barely exists in pure form naturally but in an isomorphism form between pollucite and analcime due to coexistence of Cs and Na. Pollucite could be hydrothermally synthesized with Cs-polluted soil or clay minerals which contain Cs and Na, and it is necessary to study the properties of the synthesis if Cs and Na contained. Pure pollucite, analcime and their solid solutions were hydrothermally synthesized with chemicals, and it was found that the most formed pollucite analcime solid solutions with Cs/(Cs + Na) ratios of 2/6–5/6 had very similar properties in mineral composition, morphology and size, structural water (Cs cations) and coordination environment to pollucite. This also suggests that even coexistence of Cs and Na in nature, pollucite favors to form due to site preference for Cs over Na, which leads to the property and the structure of the most solid solutions similar to that of pollucite. - Highlights: •Pure pollucite barely exists in nature due to coexistence of Cs and Na. •Pollucite, analcime and their solid solutions could be hydrothermally synthesized. •Most formed solid solutions were found to have similar properties to pollucite. •Even coexistence in nature, pollucite favors to form due to site preference for Cs over Na.

  10. The elastic solid solution model for minerals at high pressures and temperatures

    Myhill, R.

    2018-02-01

    Non-ideality in mineral solid solutions affects their elastic and thermodynamic properties, their thermobaric stability, and the equilibrium phase relations in multiphase assemblages. At a given composition and state of order, non-ideality in minerals is typically modelled via excesses in Gibbs free energy which are either constant or linear with respect to pressure and temperature. This approach has been extremely successful when modelling near-ideal solutions. However, when the lattice parameters of the solution endmembers differ significantly, extrapolations of thermodynamic properties to high pressures using these models may result in significant errors. In this paper, I investigate the effect of parameterising solution models in terms of the Helmholtz free energy, treating volume (or lattice parameters) rather than pressure as an independent variable. This approach has been previously applied to models of order-disorder, but the implications for the thermodynamics and elasticity of solid solutions have not been fully explored. Solid solution models based on the Helmholtz free energy are intuitive at a microscopic level, as they automatically include the energetic contribution from elastic deformation of the endmember lattices. A chemical contribution must also be included in such models, which arises from atomic exchange within the solution. Derivations are provided for the thermodynamic properties of n-endmember solutions. Examples of the use of the elastic model are presented for the alkali halides, pyroxene, garnet, and bridgmanite solid solutions. Elastic theory provides insights into the microscopic origins of non-ideality in a range of solutions, and can make accurate predictions of excess enthalpies, entropies, and volumes as a function of volume and temperature. In solutions where experimental data are sparse or contradictory, the Helmholtz free energy approach can be used to assess the magnitude of excess properties and their variation as a function

  11. Photoluminescence of ZnBeMnSe solid solutions

    Strzałkowski, K., E-mail: skaroll@fizyka.umk.pl; Firszt, F.; Marasek, A.

    2017-04-15

    In this paper optical properties of Zn{sub 1-x-y}Be{sub x}Mn{sub y}Se mixed semiconductors were studied as a function of both, temperature and excitation power. The crystals under investigation were grown by the high-pressure, high-temperature vertical Bridgman technique within the range of the composition 0.05≤x, y≤0.2. Photoluminescence spectra for the lowest content of Mn and Be exhibit character typical for II-VI semiconductors together with intensive yellow-orange manganese emission. Evolution of the excitonic emission as the function of temperature allowed determining the energy gap of the investigated semiconductors. Absorbance and photoluminescence excitation spectra confirmed crystal field splitting of excited atomic terms of manganese ions into the states, denoted according to the crystal field theory in the case of tetrahedral symmetry. Temperature and laser power dependences of luminescence showed anomalous behavior of the manganese emission. It turned out that the position of the Mn{sup 2+} related luminescence band does not change monotonically with the variation of the temperature or the excitation power. Finally, switching of the manganese emission has been observed. By increasing laser power of exciting radiation, the Mn-related emission could be quenched by almost two orders in magnitude. This effect was especially strong at low temperature and it was fully reversible.

  12. Cutting solid figures by plane - analytical solution and spreadsheet implementation

    Benacka, Jan

    2012-07-01

    In some secondary mathematics curricula, there is a topic called Stereometry that deals with investigating the position and finding the intersection, angle, and distance of lines and planes defined within a prism or pyramid. Coordinate system is not used. The metric tasks are solved using Pythagoras' theorem, trigonometric functions, and sine and cosine rules. The basic problem is to find the section of the figure by a plane that is defined by three points related to the figure. In this article, a formula is derived that gives the positions of the intersection points of such a plane and the figure edges, that is, the vertices of the section polygon. Spreadsheet implementations of the formula for cuboid and right rectangular pyramids are presented. The user can check his/her graphical solution, or proceed if he/she is not able to complete the section.

  13. Use of mixed solid waste as a soil amendment for saline-sodic soil remediation and oat seedling growth improvement.

    Fan, Yuan; Ge, Tian; Zheng, Yanli; Li, Hua; Cheng, Fangqin

    2016-11-01

    Soil salinization has become a worldwide problem that imposes restrictions on crop production and food quality. This study utilizes a soil column experiment to address the potential of using mixed solid waste (vinegar residue, fly ash, and sewage sludge) as soil amendment to ameliorate saline-sodic soil and enhance crop growth. Mixed solid waste with vinegar residue content ranging from 60-90 %, sewage sludge of 8.7-30 %, and fly ash of 1.3-10 % was added to saline-sodic soil (electrical conductivity (EC 1:5 ) = 1.83 dS m -1 , sodium adsorption ratio (SAR 1:5 ) = 129.3 (mmol c L -1 ) 1/2 , pH = 9.73) at rates of 0 (control), 130, 260, and 650 kg ha -1 . Results showed that the application of waste amendment significantly reduced SAR, while increasing soil soluble K + , Ca 2+ , and Mg 2+ , at a dose of 650 kg ha -1 . The wet stability of macro-aggregates (>1 mm) was improved 90.7-133.7 % when the application rate of amendment was greater than 260 kg ha -1 . The application of this amendment significantly reduced soil pH. Germination rates and plant heights of oats were improved with the increasing rate of application. There was a positive correlation between the percentage of vinegar residue and the K/Na ratio in the soil solutions and roots. These findings suggest that applying a mixed waste amendment (vinegar residue, fly ash, and sewage sludge) could be a cost-effective method for the reclamation of saline-sodic soil and the improvement of the growth of salt-tolerant plants.

  14. Soil solid-phase controls lead activity in soil solution.

    Badawy, S H; Helal, M I D; Chaudri, A M; Lawlor, K; McGrath, S P

    2002-01-01

    Lead pollution of the environment is synonymous with civilization. It has no known biological function, and is naturally present in soil, but its presence in food crops is deemed undesirable. The concern regarding Pb is mostly due to chronic human and animal health effects, rather then phytotoxicity. However, not much is known about the chemistry and speciation of Pb in soils. We determined the activity of Pb2+, in near neutral and alkaline soils, representative of alluvial, desertic and calcareous soils of Egypt, using the competitive chelation method. Lead activity ranged from 10(-6.73) to 10(-4.83) M, and was negatively correlated with soil and soil solution pH (R2 = -0.92, P soil solution from the equation: log(Pb2+) = 9.9 - 2pH. A solubility diagram for the various Pb minerals found in soil was constructed using published thermodynamic data obtained from the literature, and our measured Pb2+ activities compared with this information. The measured Pb2+ activities were undersaturated with regard to the solubility of PbSiO3 in equilibrium with SiO2 (soil). However, they were supersaturated with regard to the solubilities of the Pb carbonate minerals PbCO3 (cerussite) and Pb3(CO3)2(OH)2 in equilibrium with atmospheric CO2 and hydroxide Pb(OH)2. They were also supersaturated with regard to the solubilities of the Pb phosphate minerals Pb3(PO4)2, Pb5(PO4)3OH, and Pb4O(PO4)2 in equilibrium with tricalcium phosphate and CaCO3. The activity of Pb2+ was not regulated by any mineral of known solubility in our soils, but possibly by a mixture of Pb carbonate and phosphate minerals.

  15. Ab initio identified design principles of solid-solution strengthening in Al

    Ma Duancheng; Friák, Martin; Pezold, Johann von; Raabe, Dierk; Neugebauer, Jörg

    2013-01-01

    Solid-solution strengthening in six Al–X binary systems is investigated using first-principle methods. The volumetric mismatch parameter and the solubility enthalpy per solute were calculated. We derive three rules for designing solid-solution strengthened alloys: (i) the solubility enthalpy per solute is related to the volumetric mismatch by a power law; (ii) for each annealing temperature, there exists an optimal solute–volume mismatch to achieve maximum strength; and (iii) the strengthening potential of high volumetric mismatch solutes is severely limited by their low solubility. Our results thus show that the thermodynamic properties of the system (here Al–X alloys) set clear upper bounds to the achievable strengthening effects owing to the reduced solubility with increasing volume mismatch. (paper)

  16. Analysis of the Forward-Backward Trajectory Solution for the Mixed Quantum-Classical Liouville Equation

    Hsieh, Chang-Yu; Kapral, Raymond

    2013-01-01

    Mixed quantum-classical methods provide powerful algorithms for the simulation of quantum processes in large and complex systems. The forward-backward trajectory solution of the mixed quantum-classical Liouville equation in the mapping basis [J. Chem. Phys. 137, 22A507 (2012)] is one such scheme. It simulates the dynamics via the propagation of forward and backward trajectories of quantum coherent state variables, and the propagation of bath trajectories on a mean-field potential determined j...

  17. Onset of solid state mantle convection and mixing during magma ocean solidification

    Maurice, Maxime; Tosi, Nicola; Samuel, Henri; Plesa, Ana-Catalina; Hüttig, Christian; Breuer, Doris

    2017-04-01

    The fractional crystallization of a magma ocean can cause the formation of a compositional layering that can play a fundamental role for the subsequent long-term dynamics of the interior, for the evolution of geochemical reservoirs, and for surface tectonics. In order to assess to what extent primordial compositional heterogeneities generated by magma ocean solidification can be preserved, we investigate the solidification of a whole-mantle Martian magma ocean, and in particular the conditions that allow solid state convection to start mixing the mantle before solidification is completed. To this end, we performed 2-D numerical simulations in a cylindrical geometry. We treat the liquid magma ocean in a parametrized way while we self-consistently solve the conservation equations of thermochemical convection in the growing solid cumulates accounting for pressure-, temperature- and, where it applies, melt-dependent viscosity as well as parametrized yield stress to account for plastic yielding. By testing the effects of different cooling rates and convective vigor, we show that for a lifetime of the liquid magma ocean of 1 Myr or longer, the onset of solid state convection prior to complete mantle crystallization is likely and that a significant part of the compositional heterogeneities generated by fractionation can be erased by efficient mantle mixing.

  18. Regularities in electroconductivity and thermo-emf in systems of binary continuous solid solutions of metals

    Vedernikov, M.V.; Dvunitkin, V.G.; Zhumagulov, A.

    1978-01-01

    Given are new experimental data about specific electric resistance of 10 systems of binary continuous solid metal solutions at the temperatures of 293 and 4.2 K: Cr-V, Mo-Nb, Mo-V, Cr-Mo, Nb-V, Ti-Zr, Hf-Zr, Hf-Ti, Sc-Zr, Sc-Hf. For the first time a comparative analysis of all available data on the resistance dependence on the composition of systems of continuous solid solutions, which covers 21 systems, is carried out. The ''resistance-composition'' dependence for such alloy systems is found to be of two types. The dependence of the first type is characteristic of the systems, formed by two isoelectronic metals, the dependence of the second type - for the systems, formed by non-isoelectronic metals. Thermo-emf of each type of solid solutions differently depends on their compositions

  19. Research on ration selection of mixed absorbent solution for membrane air-conditioning system

    Li, Xiu-Wei; Zhang, Xiao-Song; Wang, Fang; Zhao, Xiao; Zhang, Zhuo

    2015-01-01

    Highlights: • We derive models of the membrane air-conditioning system with mixed absorbents. • We make analysis on system COP, cost-effectiveness and economy. • The paper provides a new method for ideal absorbent selection. • The solutes concentration of 50% achieves the best cost-effectiveness and the economy. - Abstract: Absorption air-conditioning system is a good alternative to vapor compression system for developing low carbon society. To improve the performance of the traditional absorption system, the membrane air-conditioning system is configured and its COP can reach as high as 6. Mixed absorbents are potential for cost reduction of the membrane system while maintaining a high COP. On the purpose of finding ideal mixed absorbent groups, this paper makes analysis on COP, cost-effectiveness and economy of the membrane system with mixed LiBr–CaCl 2 absorbent solution. The models of the system have been developed for the analysis. The results show the COP is higher for the absorbent groups with lower concentration of the total solute and higher concentration ratio of LiBr. It also reveals when the total solutes concentration is about 50%, it achieves the best cost-effectiveness and the economy. The process of the analysis provides a useful method for mixed absorbents selection

  20. [Selected enhancement of different order stokes lines of SRS by using fluorescence of mixed dye solution].

    Zuo, Hao-yi; Gao, Jie; Yang, Jing-guo

    2007-03-01

    A new method to enhance the intensity of the different orders of Stokes lines of SRS by using mixed dye fluorescence is reported. The Stokes lines from the second-order to the fifth-order of CCl4 were enhanced by the fluorescence of mixed R6G and RB solutions in different proportions of 20:2, 20:13 and 20:40 (R6g:Rb), respectively. It is considered that the Stokes lines from the second-order to the fifth-order are near the fluorescence peaks of the three mixed solutions, and far from the absorption peaks of R6g and Rb, so the enhancement effect dominates the absorption effect; as a result, these stokes lines are enhanced. On the contrary, the first-order stokes line is near the absorption peak of RB and far from the fluorescence peaks of the mixed solutions, which leads to the weakening of this stokes line. It is also reported that the first-order, the second-order and the third-order Stokes lines of benzene were enhanced by the fluorescence of mixed solutions of R6g and DCM with of different proportions. The potential application of this method is forecasted.

  1. The LiBH4-LiI Solid Solution as an Electrolyte in an All-Solid-State Battery

    Sveinbjörnsson, Dadi Þorsteinn; Christiansen, Ane Sælland; Viskinde, Rasmus

    2014-01-01

    The charge and discharge performance of an all-solid-state lithium battery with the LiBH4-LiI solid solution as an electrolyte is reported. Lithium titanate (Li4Ti5O12) was used as the positive electrode and lithium metal as the negative electrode. The performance of the all-solid-state cell...

  2. Solid solution and amorphous phase in Ti–Nb–Ta–Mn systems synthesized by mechanical alloying

    Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Guzman, P. [Departamento de Ingeniería Metalúrgica y Materiales, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Lascano, S. [Departamento de Ingeniería Mecánica, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Parra, C. [Departamento de Física, Universidad Técnica Federico Santa María, Av. España 1680, Valparaíso (Chile); Bejar, L. [Instituto de Investigaciones Metalúrgicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, Morelia C.P. 58000, Michoacán (Mexico); Medina, A. [Facultad de Ingeniería Mecánica, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, C.P. 58000, Michoacán (Mexico); Guzman, D. [Departamento de Metalurgia, Universidad de Atacama, Av. España 485, Copiapó (Chile)

    2016-06-15

    This work discusses the formation of Ti–30Nb–13Ta–xMn (x: 2, 4 and 6 wt%) solid solution by mechanical alloying using a shaker mill. A solid solution was formed after 15 h of milling and an amorphous phase was formed after 30 h of milling, according to X-ray diffraction results. Disappearance of strongest X-ray diffraction peaks of Nb, Ta and Mn indicated the formation of solid solution, while, X-ray diffraction patterns of powders milled for 30 h showed an amorphous hump with crystalline peaks in the angular range of 35–45° in 2θ. TEM image analysis showed the presence of nanocrystalline intermetallic compounds embedded in an amorphous matrix. Mn{sub 2}Ti, MnTi and NbTi{sub 4} intermetallic compounds were detected and revealed crystallites with size ranging from 3 to 20 nm. The Gibbs free energy for the formation of solid solution and amorphous phase of three ternary systems (Ti–Nb–Ta, Ti–Nb–Mn and Ti–Ta–Mn) was calculated using extended Miedema's model. Experimental and thermodynamic data confirmed that solid solution was first formed in the alloy with 6wt% Mn followed by the formation of an amorphous phase as milling time increases. The presence of Mn promoted the formation of amorphous phase because the atomic radius difference between Mn with Ti, Nb and Ta. - Highlights: • Thermodynamics analysis of extension of solid solution of the Ti–Nb–Ta–Mn system. • Formation of amorphous phase and intermetallic compounds were observed. • Nanocrystalline intermetallic compounds were formed with the sizes between 3 and 20 nm.

  3. Radiation induced polymerization of MMA in imidazolium ionic liquids and their mixed solutions with organic solvents

    Qi Mingying [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Wu Guozhong [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China)], E-mail: wuguozhong@sinap.ac.cn; Sha Maolin; Liu Yusheng [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, P.O. Box 800-204, Shanghai 201800 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China)

    2008-10-15

    Considerably higher molecular weight (M{sub w}) and multi-modal molecular weight distribution (MWD) of poly(methyl methacrylate) (PMMA) were observed in neat ionic liquids ([bmim][PF{sub 6}] and [bmim][BF{sub 4}]), as well as their mixed solutions with organic solvents, probably due to the high viscosity and inhomogeneity of ionic liquids. FTIR spectra for PMMA showed that a slight amount of ionic liquid remained in the resulting polymer, and DSC measurement indicated the increase of glass transition point of PMMA with increasing of ionic liquid fraction in mixed solutions.

  4. A Moessbauer study on the photolysis of potassium trisoxalatoferrate(III) in solid and solutions

    Sato, H.; Tominaga, T.

    1977-01-01

    The photolysis of potassium trisoxalatoferrate(III) in solid and aqueous solutions was studied by Moessbauer spectroscopy. A ferrous species was mainly detected as an intermediate product in the photoirradiated solutions. A tentative mechanism was proposed for the overall reactions in and after the photolysis of this compound. The Moessbauer spectra were measured with a Hitachi AA-40 or Shimadzu MEG-2 Moessbauer spectrometer against Co-57 in copper foil. Acrylic holders (32 mm in diameter) were used for measurements of solutions: the irradiated solution was quickly frozen before measurement by adding it dropwise into the acrylic holder which had been cooled with liquid nitrogen or dry-ice. (T.I.)

  5. A thermodynamic model for solid solutions and its application to the C-Fe-Co, C-Fe-Ni and Mn-Cr-Pt solid dilutions

    Tao, D.P.

    2004-01-01

    Based on the free volume theory and the lattice model, the partition functions of pure solids and their mixtures were expressed. This resulted in the establishment of a thermodynamic model for solid solutions. The model naturally combines the excess entropy and excess enthalpy of a solution by means of new expressions of the configurational partition functions of solids and their mixtures derived from statistical thermodynamics, which is approximate to real solid solutions, that is S E ≠0 (V E ≠0) and H E ≠0. It can describe the thermodynamic properties of partially miscible systems and predict the thermodynamic properties in a multicomponent solid solution system using only the related binary infinite dilute activity coefficients. The predicted activity coefficients from the model are in good agreement with the experimental data of the ternary solid dilutions. This shows that the prediction effect of the proposed model is of better stability and reliability because it has a good physical basis

  6. Light refractive index in indium phosphide and InP-containing solid solutions

    Yas'kov, A.D.

    1983-01-01

    Spectral and temperatUre dependences of the InP and Gasub(x)Insub(1-x)P refractive indexes in the range of 0.98-1.3 μm are measured. The obtained in this case and published earlier experimental data on refractive index dispersion of the InP and solid solutions with its participation are generalized within the framework of a simple model approach based on a consecutiVe account of measured parameters of zone structure with the solid solution composition

  7. Phase coexistence in ferroelectric solid solutions: Formation of monoclinic phase with enhanced piezoelectricity

    Xiaoyan Lu

    2016-10-01

    Full Text Available Phase morphology and corresponding piezoelectricity in ferroelectric solid solutions were studied by using a phenomenological theory with the consideration of phase coexistence. Results have shown that phases with similar energy potentials can coexist, thus induce interfacial stresses which lead to the formation of adaptive monoclinic phases. A new tetragonal-like monoclinic to rhombohedral-like monoclinic phase transition was predicted in a shear stress state. Enhanced piezoelectricity can be achieved by manipulating the stress state close to a critical stress field. Phase coexistence is universal in ferroelectric solid solutions and may provide a way to optimize ultra-fine structures and proper stress states to achieve ultrahigh piezoelectricity.

  8. Specific features of kinetics of He3-He4 solid solution transformations at superlow temperatures

    Mikheev, V.A.; Majdanov, V.A.; Mikhin, N.P.

    1986-01-01

    The NMR data on the phase transition kinetics of 3 He- 4 He solid solutions at T=100 mK are considered. Studied are solid helium samples of a molecular volume of 20.55 cm 2 /mol with a 3 He content of 0.54 %. An unusually long phase transition time is found which is dependent on the prehistory of sample. The spin diffusion of 3 He in the transformated solution concentrated phase is found to be of a quasi-one-dimensional nature with the diffusion coefficient value typical of liquid

  9. Characterization of solid-solution interface by potentiometric titration and electrophoretic mobility

    Lindecker, C.; Drot, R.; Fourest, B.; Simoni, E.

    1999-01-01

    The study of nuclear waste storage in deep geological sites involves the understanding of processes which could produce a possible dispersion or retention of radioelements. The dispersion of solid particles in aqueous solution is consequently important to be characterized. In this bi-phased system it is necessary to determine the characteristics of the solid-solution interface. The method used of this study is the techniques of potentiometric titration applied to heterogeneous systems. The material studied were phosphate matrices which were synthesized in the laboratory. The dependence of their surface change upon the nature of the electrolytes was investigated

  10. Decomposition features of a supersaturated solid solution in the Mg-3.3 wt. % Yb alloy

    Dobromyslov, A.V.; Kajgorodova, L.I.; Sukhanov, V.D.; Dobatkina, T.V.

    2007-01-01

    Methods of electron microscopy, hardness measuring and X-ray diffraction analysis are applied to study decomposition kinetics for a supersaturated solid solution in a Mg-3.3 mas. % alloy on aging within a temperature range of 150-225 deg C. The mechanism of supersaturation solid solution decomposition is revealed along with the nature of phases precipitated at various stages of aging: on incomplete and extended aging as well as at maximum hardness. The types of structural constituents responsible for changes of hardness on aging are determined [ru

  11. Air Emissions Sampling from Vacuum Thermal Desorption for Mixed Wastes Designated with a Combustion Treatment Code for the Energy Solutions LLC Mixed Waste Facility

    Christensen, M.E.; Willoughby, O.H.

    2009-01-01

    EnergySolutions LLC is permitted by the State of Utah to treat organically-contaminated Mixed Waste by a vacuum thermal desorption (VTD) treatment process at its Clive, Utah treatment, storage, and disposal facility. The VTD process separates organics from organically-contaminated waste by heating the material in an inert atmosphere, and captures them as concentrated liquid by condensation. The majority of the radioactive materials present in the feed to the VTD are retained with the treated solids; the recovered aqueous and organic condensates are not radioactive. This is generally true when the radioactivity is present in solid form such as inorganic salts, metals or metallic oxides. The exception is when volatile radioactive materials are present such as radon gas, tritium, or carbon-14 organic chemicals. Volatile radioactive materials are a small fraction of the feed material. On August 28, 2006, EnergySolutions submitted a request to the USEPA for a variance to the Land Disposal Restrictions (LDR) standards for wastes designated with the combustion treatment code (CMBST). The final rule granting a site specific treatment variance was effective June 13, 2008. This variance is an alternative treatment standard to treatment by CMBST required for these wastes under USEPA's rules. The State of Utah provides oversight of the VTD processing operations. A demonstration test for treating CMBST-coded wastes was performed on April 29, 2008 through May 1, 2008. Three separate process cycles were conducted during this test. Both solid/liquid samples and emission samples were collected each day during the demonstration test. To adequately challenge the unit, feed material was spiked with trichloroethylene, o-cresol, dibenzofuran, and coal tar. Emission testing was conducted by EnergySolutions' emissions test contractor and sampling for radioactivity within the off-gas was completed by EnergySolutions' Health Physics department. This report discusses the emission testing

  12. Direct measurements of the enthalpy of solution of solid solute in supercritical fluids: study on the CO2-naphthalene system.

    Zhang, X; Han, B; Zhang, J; Li, H; He, J; Yan, H

    2001-10-01

    A setup for a calorimeter for simultaneously measuring the solubility and the solution enthalpy of solid solutes in supercritical fluids (SCFs) has been established. The enthalpy of solution of naphthalene in supercritical CO2 was measured at 308.15 K in the pressure range from 8.0-11.0 MPa. It was found that the enthalpy of solution (deltaH) was negative in the pressure range from 8.0 to 9.5 MPa, and the absolute value decreased with increasing pressure. In this pressure range, the dissolution of the solute was enthalpy driven. However, the deltaH became positive at pressures higher than 9.5 MPa, and the dissolution was entropy driven. Monte Carlo simulation was performed to analyze the local structural environment of the solvated naphthalene molecules in supercritical CO2 under the experimental conditions for the calorimetric measurements. By combining the enthalpy data and the simulation results, it can be deduced that the energy level of CO2 in the high compressible region is higher than that at higher pressures, which results in the large negative enthalpy of solution and the larger degree of solvent-solute clustering in the high compressible region.

  13. Mixed municipal solid waste (MSW) treatment in Waste centre Spodnji Stari Grad, Krško

    Kortnik, Jože; Leskovar, Jože

    2015-01-01

    Review paper Received: October 25, 2013 Accepted: November 7, 2013 Mixed municipal solid waste (MSW) treatment in Waste centre Spodnji Stari Grad, Krško Ravnanje z mešanimi komunalnimi odpadki v Zbirnem centru Spodnji Stari Grad, Krško Jože Kortnik1'*, Jože Leskovar2 University of Ljubljana, Faculty of Natural Sciences and Engineering, Department of Mining and Geotechnology, Aškerčeva 12, 1000 Ljubljana, Slovenia 2Kostak, d. d., Leskovška cesta 2a, 8270 Krško, Slovenia Correspo...

  14. Hydrogen production characteristics of the organic fraction of municipal solid wastes by anaerobic mixed culture fermentation

    Dong, Li; Yu, Zhang [Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640 (China)]|[Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Zhenhong, Yuan; Yongming, Sun; Xiaoying, Kong [Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640 (China)

    2009-01-15

    The hydrogen production from the organic fraction of municipal solid waste (OFMSW) by anaerobic mixed culture fermentation was investigated using batch experiments at 37 C. Seven varieties of typical individual components of OFMSW including rice, potato, lettuce, lean meat, oil, fat and banyan leaves were selected to estimate the hydrogen production potential. Experimental results showed that the boiling treated anaerobic sludge was effective mixed inoculum for fermentative hydrogen production from OFMSW. Mechanism of fermentative hydrogen production indicates that, among the OFMSW, carbohydrates is the most optimal substrate for fermentative hydrogen production compared with proteins, lipids and lignocelluloses. This conclusion was also substantiated by experimental results of this study. The hydrogen production potentials of rice, potato and lettuce were 134 mL/g-VS, 106 mL/g-VS, and 50 mL/g-VS respectively. The hydrogen percentages of the total gas produced from rice, potato and lettuce were 57-70%, 41-55% and 37-67%. (author)

  15. Diffusion kinetics and spinodal decay of quasi-equilibrium solid solutions

    Zakharov, M.A.

    2000-01-01

    Phenomenological theory for rearrangement of solid solutions with the hierarchy of the component atomic mobilities is elaborated in the approximation of the local equilibrium. The hydrodynamic stage of the evolution of these solutions is studied as a sequence of quasi-equilibrium states characterized by implementation of some conditions of the total equilibrium. On the basis of separation of fast and slow constituents of diffusion and on the basis of the method of reduced description one derived equation for evolution of separations of fast components in quasi-equilibrium solid solutions at the arbitrary stages of rearrangement in terms of the generalized lattice model taking account of the proper volumes of the components. The conditions of the stability of quasi-equilibrium solutions to the spinodal decomposition are determined and the equations of metastability boundaries of such systems are derived [ru

  16. Localized solid-state amorphization at grain boundaries in a nanocrystalline Al solid solution subjected to surface mechanical attrition

    Wu, X [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080 (China); Tao, N [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Hong, Y [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080 (China); Lu, J [LASMIS, University of Technology of Troyes, 10000, Troyes (France); Lu, K [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2005-11-21

    Using high-resolution electron microscopy, localized solid-state amorphization (SSA) was observed in a nanocrystalline (NC) Al solid solution (weight per cent 4.2 Cu, 0.3 Mn, the rest being Al) subjected to a surface mechanical attrition treatment. It was found that the deformation-induced SSA may occur at the grain boundary (GB) where either the high density dislocations or dislocation complexes are present. It is suggested that lattice instability due to elastic distortion within the dislocation core region plays a significant role in the initiation of the localized SSA at defective sites. Meanwhile, the GB of severely deformed NC grains exhibits a continuously varying atomic structure in such a way that while most of the GB is ordered but reveals corrugated configurations, localized amorphization may occur along the same GB.

  17. Cementation of the solid radioactive waste with polymer-cement solutions using the method of impregnation

    Gorbunova, O.

    2015-01-01

    Cementation of solid radioactive waste (SRW), i.e. inclusion of solid radioactive waste into cement matrix without cavities - is one of the main technological processes used for conditioning low and intermediate level radioactive waste. At FSUE 'Radon' the industrialized method of impregnation has been developed and since 2003 has been using for cementation of solid radioactive waste. The technology is that the polymer-cement solution, having high penetrating properties, is supplied under pressure through a tube to the bottom of the container in which solid radioactive waste has preliminarily been placed. The polymer-cement solution is evenly moving upwards through the channels between the particles of solid radioactive waste, fills the voids in the bulk volume of the waste and hardens, forming a cement compound, the amount of which is equal to the original volume. The aim of the investigation was a selection of a cement solution suitable for SRW impregnation (including fine particles) without solution depletion and bottom layers stuffing. It has been chosen a polymer: PHMG (polyhexamethylene-guanidine), which is a stabilizing and water-retaining component of the cement solution. The experiments confirm that the polymer increases the permeability of the cement solution by a 2-2.5 factor, the viscosity by a 1.2 factor, the stability of the consistency by a 1.5-1.7 factor, and extends the operating range of the W/C ratio to 0.5-1.1. So it is possible to penetrate a volume of SRW bigger by a 1.5-2.0 factor. It has been proved, that PHMG polymer increases strength and frost-resistance of the final compounds by a 1.8-2.7 factor, and contributes to fast strength development at the beginning of hardening and it decreases Cs-137 leashing rate by a 1.5-2 factor

  18. SAVANNAH RIVER SITE INCIPIENT SLUDGE MIXING IN RADIOACTIVE LIQUID WASTE STORAGE TANKS DURING SALT SOLUTION BLENDING

    Leishear, R.; Poirier, M.; Lee, S.; Steeper, T.; Fowley, M.; Parkinson, K.

    2011-01-12

    This paper is the second in a series of four publications to document ongoing pilot scale testing and computational fluid dynamics (CFD) modeling of mixing processes in 85 foot diameter, 1.3 million gallon, radioactive liquid waste, storage tanks at Savannah River Site (SRS). Homogeneous blending of salt solutions is required in waste tanks. Settled solids (i.e., sludge) are required to remain undisturbed on the bottom of waste tanks during blending. Suspension of sludge during blending may potentially release radiolytically generated hydrogen trapped in the sludge, which is a safety concern. The first paper (Leishear, et. al. [1]) presented pilot scale blending experiments of miscible fluids to provide initial design requirements for a full scale blending pump. Scaling techniques for an 8 foot diameter pilot scale tank were also justified in that work. This second paper describes the overall reasons to perform tests, and documents pilot scale experiments performed to investigate disturbance of sludge, using non-radioactive sludge simulants. A third paper will document pilot scale CFD modeling for comparison to experimental pilot scale test results for both blending tests and sludge disturbance tests. That paper will also describe full scale CFD results. The final paper will document additional blending test results for stratified layers in salt solutions, scale up techniques, final full scale pump design recommendations, and operational recommendations. Specifically, this paper documents a series of pilot scale tests, where sludge simulant disturbance due to a blending pump or transfer pump are investigated. A principle design requirement for a blending pump is UoD, where Uo is the pump discharge nozzle velocity, and D is the nozzle diameter. Pilot scale test results showed that sludge was undisturbed below UoD = 0.47 ft{sup 2}/s, and that below UoD = 0.58 ft{sup 2}/s minimal sludge disturbance was observed. If sludge is minimally disturbed, hydrogen will not be

  19. The Solution Set Characterization and Error Bound for the Extended Mixed Linear Complementarity Problem

    Hongchun Sun

    2012-01-01

    Full Text Available For the extended mixed linear complementarity problem (EML CP, we first present the characterization of the solution set for the EMLCP. Based on this, its global error bound is also established under milder conditions. The results obtained in this paper can be taken as an extension for the classical linear complementarity problems.

  20. Magnetic susceptibilities of Ca/sub y/U/sub 1-y/O/sub 2+x/ solid solutions

    Hinatsu, Y.; Fujino, T.

    1988-01-01

    Magnetic susceptibilities of Ca/sub y/U/sub 1-y/O/sub 2+x/ solid solutions with fluorite structure were measured from 4.2 K to room temperature. An antiferromagnetic transition was observed for all the solid solutions examined in this study (y ≤ 0.33). The Neel temperature of the oxygen-hypostoichiometric solid solutions (x 2 solid solutions, but different from that of (U,Th)O 2 solid solutions. The effective magnetic moment decreased with increasing calcium concentration, which indicates the oxidation of uranium in the solid solutions. From the analysis of the magnetic susceptibility data, it was found that the oxidation state of uranium was either tetravalent or pentavalent. The Neel temperature of the hyperstoichiometric solid solutions (x > 0) did not change appreciably with calcium concentrations. From the comparison of the magnetic susceptibility data of the hypostoichiometric solid solutions with those of the hyperstoichiometric solid solutions, the effect of oxygen vacancies is more significant than that of interstitial oxygens on the decrease of magnetic interactions between uranium ions

  1. Use of Raman spectroscopy to assess the efficiency of MgAl mixed oxides in removing cyanide from aqueous solutions

    Cosano, Daniel; Esquinas, Carlos; Jiménez-Sanchidrián, César; Ruiz, José Rafael

    2016-01-01

    Graphical abstract: - Highlights: • Raman is used by first time for adsorption of cyanide on calcined LDHs. • Raman is an effective, accurate and expeditious method for monitoring this process. • Cyanide is adsorbed by a rehydration process based on the “memory effect”. • The metal ratio of the LDH has a crucial influence on the adsorption capacity. - Abstract: Calcining magnesium/aluminium layered double hydroxides (Mg/Al LDHs) at 450 °C provides excellent sorbents for removing cyanide from aqueous solutions. The process is based on the “memory effect” of LDHs; thus, rehydrating a calcined LDH in an aqueous solution restores its initial structure. The process, which conforms to a first-order kinetics, was examined by Raman spectroscopy. The metal ratio of the LDH was found to have a crucial influence on the adsorption capacity of the resulting mixed oxide. In this work, Raman spectroscopy was for the first time use to monitor the adsorption process. Based on the results, this technique is an effective, expeditious choice for the intended purpose and affords in situ monitoring of the adsorption process. The target solids were characterized by using various instrumental techniques including X-ray diffraction spectroscopy, which confirmed the layered structure of the LDHs and the periclase-like structure of the mixed oxides obtained by calcination.

  2. Use of Raman spectroscopy to assess the efficiency of MgAl mixed oxides in removing cyanide from aqueous solutions

    Cosano, Daniel; Esquinas, Carlos; Jiménez-Sanchidrián, César; Ruiz, José Rafael, E-mail: qo1ruarj@uco.es

    2016-02-28

    Graphical abstract: - Highlights: • Raman is used by first time for adsorption of cyanide on calcined LDHs. • Raman is an effective, accurate and expeditious method for monitoring this process. • Cyanide is adsorbed by a rehydration process based on the “memory effect”. • The metal ratio of the LDH has a crucial influence on the adsorption capacity. - Abstract: Calcining magnesium/aluminium layered double hydroxides (Mg/Al LDHs) at 450 °C provides excellent sorbents for removing cyanide from aqueous solutions. The process is based on the “memory effect” of LDHs; thus, rehydrating a calcined LDH in an aqueous solution restores its initial structure. The process, which conforms to a first-order kinetics, was examined by Raman spectroscopy. The metal ratio of the LDH was found to have a crucial influence on the adsorption capacity of the resulting mixed oxide. In this work, Raman spectroscopy was for the first time use to monitor the adsorption process. Based on the results, this technique is an effective, expeditious choice for the intended purpose and affords in situ monitoring of the adsorption process. The target solids were characterized by using various instrumental techniques including X-ray diffraction spectroscopy, which confirmed the layered structure of the LDHs and the periclase-like structure of the mixed oxides obtained by calcination.

  3. Use of Residual Solids from Pulp and Paper Mills for Enhancing Strength and Durability of Ready-Mixed Concrete

    Tarun R. Naik; Yoon-moon Chun; Rudolph N. Kraus

    2003-09-18

    This research was conducted to establish mixture proportioning and production technologies for ready-mixed concrete containing pulp and paper mill residual solids and to study technical, economical, and performance benefits of using the residual solids in the concrete. Fibrous residuals generated from pulp and paper mills were used, and concrete mixture proportions and productions technologies were first optimized under controlled laboratory conditions. Based on the mixture proportions established in the laboratory, prototype field concrete mixtures were manufactured at a ready-mixed concrete plant. Afterward, a field construction demonstration was held to demonstrate the production and placement of structural-grade cold-weather-resistant concrete containing residual solids.

  4. Investigation of Different Colloidal Porous Silicon Solutions and Their Composite Solid Matrix Rods by Optical Techniques

    Khan, M. Naziruddin; Aldalbahi, Ali; Almohammedi, Abdullah

    2018-03-01

    Colloidal porous silicon (PSi) in different solvents was synthesized by simple chemical etching. Colloidal solutions were then prepared using different quantities of silicon wafer pieces (Pcs) and chloroplatinic (Pt) acid in catalyst solution. The effect on the properties of the colloidal solutions and composite rods were investigated using various optical characterization techniques. Absorption and photoluminescence (PL) intensity of the colloidal PSi solutions are observed to depend on the quantity of wafer Pcs, the Pt-solution, and the porosity formation on the wafer surface. The morphological structure of the PSi in a solvent and the solid-rod environments were studied using field-emission scanning electron microscopy (FE-SEM) and were observed to have different structures. A mono-oriented structure of PSi exists in tetrahydrofuran, which has stereo orientation in dioxane and dimethylsulfoxide (approximately 5-8 nm as confirmed using high resolution transmission electron microscopy). Subsequently, some colloidal PSi solutions were directly embedded in three types of sol-gel-based matrices, silica, ormosils (or organically modified silica) and polymer, which easily generated solid rods. Spontaneous emission (SE) of the PSi solutions and their composite rods were examined using a high power picosecond 355 nm laser source. The emitted PL and SE signals of the colloidal PSi solutions were dependent on the Pt volume, nature of the solvent, quantity of Si wafer piece, and pumping energy. The response of SE signals from the PSi composites rods is an interesting phenomenon, and such nanocomposites may be used for future research on light amplification.

  5. Influence of Ce 0.68 Zr 0.32 O 2 solid solution on depositing ...

    Home; Journals; Bulletin of Materials Science; Volume 29; Issue 1. Influence of Ce0.68Zr0.32O2 solid solution on depositing -alumina washcoat on FeCrAl foils. Mei-Qing Shen Li-Wei Jia Wen-Long Zhou Jun Wang Ying Huang. Composites Volume 29 Issue 1 February 2006 pp 73-76 ...

  6. Contribution of Lattice Distortion to Solid Solution Strengthening in a Series of Refractory High Entropy Alloys

    Chen, H.; Kauffmann, A.; Laube, S.; Choi, I.-C.; Schwaiger, R.; Huang, Y.; Lichtenberg, K.; Müller, F.; Gorr, B.; Christ, H.-J.; Heilmaier, M.

    2018-03-01

    We present an experimental approach for revealing the impact of lattice distortion on solid solution strengthening in a series of body-centered-cubic (bcc) Al-containing, refractory high entropy alloys (HEAs) from the Nb-Mo-Cr-Ti-Al system. By systematically varying the Nb and Cr content, a wide range of atomic size difference as a common measure for the lattice distortion was obtained. Single-phase, bcc solid solutions were achieved by arc melting and homogenization as well as verified by means of scanning electron microscopy and X-ray diffraction. The atomic radii of the alloying elements for determination of atomic size difference were recalculated on the basis of the mean atomic radii in and the chemical compositions of the solid solutions. Microhardness (μH) at room temperature correlates well with the deduced atomic size difference. Nevertheless, the mechanisms of microscopic slip lead to pronounced temperature dependence of mechanical strength. In order to account for this particular feature, we present a combined approach, using μH, nanoindentation, and compression tests. The athermal proportion to the yield stress of the investigated equimolar alloys is revealed. These parameters support the universality of this aforementioned correlation. Hence, the pertinence of lattice distortion for solid solution strengthening in bcc HEAs is proven.

  7. Defect structure of cubic solid solutions of alkaline earth and rare earth fluorides

    DenHartog, HW

    1996-01-01

    In this paper we will consider the disorder in some cubic solid solutions consisting of one of the alkaline earth fluorides and one of the rare earth fluorides. This is an attractive group of model materials, because these materials have a rather simple overall cubic structure. We will discuss the

  8. Thermal expansion of TRU nitride solid solutions as fuel materials for transmutation of minor actinides

    Takano, Masahide; Akabori, Mitsuo; Arai, Yasuo; Minato, Kazuo

    2009-01-01

    The lattice thermal expansion of the transuranium nitride solid solutions was measured to investigate the composition dependence. The single-phase solid solution samples of (Np 0.55 Am 0.45 )N, (Pu 0.59 Am 0.41 )N, (Np 0.21 Pu 0.52 Am 0.22 Cm 0.05 )N and (Pu 0.21 Am 0.18 Zr 0.61 )N were prepared by carbothermic nitridation of the respective transuranium dioxides and nitridation of Zr metal through hydride. The lattice parameters were measured by the high temperature X-ray diffraction method from room temperature up to 1478 K. The linear thermal expansion of each sample was determined as a function of temperature. The average thermal expansion coefficients over the temperature range of 293-1273 K for the solid solution samples were 10.1, 11.5, 10.8 and 8.8 x 10 -6 K -1 , respectively. Comparison of these values with those for the constituent nitrides showed that the average thermal expansion coefficients of the solid solution samples could be approximated by the linear mixture rule within the error of 2-3%.

  9. The preparation method of solid boron solution in silicon carbide in the form of micro powder

    Pampuch, R.; Stobierski, L.; Lis, J.; Bialoskorski, J.; Ermer, E.

    1993-01-01

    The preparation method of solid boron solution in silicon carbide in the form of micro power has been worked out. The method consists in introducing mixture of boron, carbon and silicon and heating in the atmosphere of inert gas to the 1573 K

  10. Solid solution in Al-4.5 wt% Cu produced by mechanical alloying

    Fogagnolo, J.B.; Amador, D.; Ruiz-Navas, E.M.; Torralba, J.M.

    2006-01-01

    Mechanical alloying has been used to produce oxide dispersion strengthened alloys, intermetallic compounds, aluminium alloys and to obtain nanostructured and amorphous materials, as well as to extend the solid solution limit. In this work, Al and Cu elemental powders were subjected to high-energy milling to produce Al-4.5 wt% Cu powder alloy. The powders obtained were characterized by scanning electron microscopy, X-ray diffraction (XRD) and differential scanning calorimetry (DSC), aiming to explore if the copper is present in solid solution or as small particles after high-energy milling. Related to the formation of a supersaturated solid solution, the results of scanning electron microscopy and X-ray diffraction are non-conclusive: the copper could be dispersed with a very small size, undetectable to both techniques. The Al 2 Cu precipitation at temperatures between 160 and 230 deg. C, verified by DSC and XRD analyses, substantiated that mechanical alloying had produced a supersaturated solid solution of copper in aluminium. The crystallite size as a function of milling time and annealing temperature was also determined by X-ray techniques

  11. Solution and solid-phase halogen and C-H hydrogen bonding to perrhenate.

    Massena, Casey J; Riel, Asia Marie S; Neuhaus, George F; Decato, Daniel A; Berryman, Orion B

    2015-01-28

    (1)H NMR spectroscopic and X-ray crystallographic investigations of a 1,3-bis(4-ethynyl-3-iodopyridinium)benzene scaffold with perrhenate reveal strong halogen bonding in solution, and bidentate association in the solid state. A nearly isostructural host molecule demonstrates significant C-H hydrogen bonding to perrhenate in the same phases.

  12. Fine interstitial clusters as recombinators in decomposing solid solutions under irradiation

    Trushin, Yu.V.

    1991-01-01

    Behaviour of interstitial clusters and their roll in processes of radiation swelling of metals are described. It is shown that occurrence of coherent advanced precipitations during decomposition of solid solutions under irradiation leads to matrix supersaturation over interstitial atoms. This enhances recombination of unlike defects due to vacancy precipitation on fine interstitial clusters. Evaluation of cluster sizes was conducted

  13. Bridging phases at the morphotropic boundaries of lead oxide solid solutions

    Noheda, Beatriz; Cox, DE

    2006-01-01

    Ceramic solid solutions of PbZr1-xTixO3 (PZT) with compositions x similar or equal to 0.50 are well-known for their extraordinarily large piezoelectric responses. The latter are highly anisotropic, and it was recently shown that, for the rhombohedral compositions (x less than or similar to 0.5), the

  14. Study of reaction sequences for formation of solid solution: 0,48 ...

    ... of a low concentration of ions forming the perovskite structure PZT (Pb2+, Zr4+ et Ti4+) by other ions (Zn2+, Cr3+ et Sb+5 in our study) alters the reaction sequences training of the solid solution PZT and especially the formation of intermediate phase. Keywords: PZT / Calcination / TGA / DTA / RX / Piezoelectric Ceramics ...

  15. Exact Solution of the Two-Level System and the Einstein Solid in the Microcanonical Formalism

    Bertoldi, Dalia S.; Bringa, Eduardo M.; Miranda, E. N.

    2011-01-01

    The two-level system and the Einstein model of a crystalline solid are taught in every course of statistical mechanics and they are solved in the microcanonical formalism because the number of accessible microstates can be easily evaluated. However, their solutions are usually presented using the Stirling approximation to deal with factorials. In…

  16. Dynamic nuclear polarization methods in solids and solutions to explore membrane proteins and membrane systems.

    Cheng, Chi-Yuan; Han, Songi

    2013-01-01

    Membrane proteins regulate vital cellular processes, including signaling, ion transport, and vesicular trafficking. Obtaining experimental access to their structures, conformational fluctuations, orientations, locations, and hydration in membrane environments, as well as the lipid membrane properties, is critical to understanding their functions. Dynamic nuclear polarization (DNP) of frozen solids can dramatically boost the sensitivity of current solid-state nuclear magnetic resonance tools to enhance access to membrane protein structures in native membrane environments. Overhauser DNP in the solution state can map out the local and site-specific hydration dynamics landscape of membrane proteins and lipid membranes, critically complementing the structural and dynamics information obtained by electron paramagnetic resonance spectroscopy. Here, we provide an overview of how DNP methods in solids and solutions can significantly increase our understanding of membrane protein structures, dynamics, functions, and hydration in complex biological membrane environments.

  17. Platform construction and extraction mechanism study of magnetic mixed hemimicelles solid-phase extraction

    Xiao, Deli; Zhang, Chan; He, Jia; Zeng, Rong; Chen, Rong; He, Hua

    2016-12-01

    Simple, accurate and high-throughput pretreatment method would facilitate large-scale studies of trace analysis in complex samples. Magnetic mixed hemimicelles solid-phase extraction has the power to become a key pretreatment method in biological, environmental and clinical research. However, lacking of experimental predictability and unsharpness of extraction mechanism limit the development of this promising method. Herein, this work tries to establish theoretical-based experimental designs for extraction of trace analytes from complex samples using magnetic mixed hemimicelles solid-phase extraction. We selected three categories and six sub-types of compounds for systematic comparative study of extraction mechanism, and comprehensively illustrated the roles of different force (hydrophobic interaction, π-π stacking interactions, hydrogen-bonding interaction, electrostatic interaction) for the first time. What’s more, the application guidelines for supporting materials, surfactants and sample matrix were also summarized. The extraction mechanism and platform established in the study render its future promising for foreseeable and efficient pretreatment under theoretical based experimental design for trace analytes from environmental, biological and clinical samples.

  18. The effect of mixing ratio variation of sludge and organic solid waste on biodrying process

    Nasution, A. C.; Kristanto, G. A.

    2018-01-01

    In this study, organic waste was co-biodried with sludge cake to determine which mixing ratio gave the best result. The organic waste was consisted of dried leaves and green leaves, while the sludge cake was obtained from a waste water treatment plant in Bekasi. The experiment was performed on 3 lab-scale reactors with same specifications. After 21 days of experiment, it was found that the reactor with the lowest mixing fraction of sludge (5:1) has the best temperature profile and highest moisture content depletion compared with others. Initial moisture content and initial volatile solid content of this reactor’s feedstock was 52.25% and 82.4% respectively. The airflow rate was 10 lpm. After biodrying was done, the final moisture content of the feedstock from Reactor C was 22.0% and the final volatile solid content was 75.9%.The final calorific value after biodrying process was 3179,28kcal/kg.

  19. Properties of PP/MWCNT-COOH /PP composites made by melt mixing versus solution cast /melt mixing methods

    Reinholds, I; Roja, Z; Zicans, J; Meri, R Merijs; Bitenieks, J

    2015-01-01

    An approach on improvement of the properties of polypropylene / carbon nanotube (PP/CNT) composites is reported. PP blend compositions with carboxylic acid functionalized multi-walled carbon nanotubes (MWCNT-COOH) at filler content 1.0 wt.% were researched. One part of the composites was manufactured by direct thermoplastic mixing PP with the filler, but the other one was made from solution casted masterbatch with the following thermoplastic mixing. An increase of mechanical properties (Young's modulus, storage modulus and tensile strength), compared to an increase of glass transition temperature indicated a reinforcement effect of CNTs on PP matrix, determined from the tensile tests and differential mechanical analysis (DMA), while the elongation was reduced, compared to PP matrix. By differential scanning calorimetry (DSC) analysis, the effect of nanofiller on the reorganization of PP crystallites was observed. A noticeable enhanced effect on increase of the crystallization temperature was indicated for masterbatch manufactured composite. An increase of thermal stability was also observed, compared to pristine PP and the composite made by direct thermoplastic mixing PP with the filler

  20. Geochemical and numerical modelling of interactions between solid solutions and an aqueous solution. Extension of a reactive transport computer code called Archimede and application to reservoirs diagenesis; Modelisation geochimique et numerique des interactions entre des solutions solides et une solution aqueuse: extension du logiciel de reaction-transport archimede et application a la diagenese des reservoirs

    Nourtier-Mazauric, E.

    2003-03-15

    This thesis presents a thermodynamic and kinetic model of interactions between a fluid and ideal solid solutions represented by several end-members. The reaction between a solid solution and the aqueous solution results from the competition between the stoichiometric dissolution of the initial solid solution and the co-precipitation of the least soluble solid solution in the fluid at considered time. This model was implemented in ARCHIMEDE, a computer code of reactive transport in porous media, then applied to various examples. In the case of binary solid solutions, a graphical method allowed to determine the compositions of the precipitating solid solutions, with the aid of the end-member chemical potentials. The obtained program could be used to notably model the diagenesis of clayey or carbonated oil reservoirs, or the ground pollutant dispersion. (author)

  1. Calculating excess volumes of binary solutions with allowance for structural differences between mixed components

    Balankina, E. S.

    2016-06-01

    Analytical dependences of a volume's properties on the differences between the geometric structures of initial monosystems are obtained for binary systems simulated by a grain medium. The effect of microstructural parameter k (the ratio of volumes of molecules of mixed components) on the concentration behavior of the relative excess molar volume of different types of real binary solutions is analyzed. It is established that the contribution due to differences between the volumes of molecules and coefficients of the packing density of mixed components is ~80-100% for mutual solutions of n-alkanes and ~55-80% of the experimental value of the relative excess molar volume for water solutions of n-alcohols.

  2. Investigation of water and saline solution drops evaporation on a solid substrate

    Orlova Evgenija G.

    2014-01-01

    Full Text Available Experimental investigation water and saline solution drops evaporation on a solid substrate made of anodized aluminum is presented in the paper. Parameters characterizing drop profile have been obtained (contact angle, contact diameter, height. The specific evaporation rate has been calculated from obtained values. It was found that water and saline solution drops with concentration up to 9.1% evaporate in the pinning mode. However, with increasing the salt concentration in the solution up to 16.7% spreading mode was observed. Two stages of drop evaporation depending on change of the evaporation rate have been separated.

  3. Experimental heat capacities, excess entropies, and magnetic properties of bulk and nano Fe3O4-Co3O4 and Fe3O4-Mn3O4 spinel solid solutions

    Schliesser, Jacob M.; Huang, Baiyu; Sahu, Sulata K.; Asplund, Megan; Navrotsky, Alexandra; Woodfield, Brian F.

    2018-03-01

    We have measured the heat capacities of several well-characterized bulk and nanophase Fe3O4-Co3O4 and Fe3O4-Mn3O4 spinel solid solution samples from which magnetic properties of transitions and third-law entropies have been determined. The magnetic transitions show several features common to effects of particle and magnetic domain sizes. From the standard molar entropies, excess entropies of mixing have been generated for these solid solutions and compared with configurational entropies determined previously by assuming appropriate cation and valence distributions. The vibrational and magnetic excess entropies for bulk materials are comparable in magnitude to the respective configurational entropies indicating that excess entropies of mixing must be included when analyzing entropies of mixing. The excess entropies for nanophase materials are even larger than the configurational entropies. Changes in valence, cation distribution, bonding and microstructure between the mixing ions are the likely sources of the positive excess entropies of mixing.

  4. Failure criterion effect on solid production prediction and selection of completion solution

    Dariush Javani

    2017-12-01

    Full Text Available Production of fines together with reservoir fluid is called solid production. It varies from a few grams or less per ton of reservoir fluid posing only minor problems, to catastrophic amount possibly leading to erosion and complete filling of the borehole. This paper assesses solid production potential in a carbonate gas reservoir located in the south of Iran. Petrophysical logs obtained from the vertical well were employed to construct mechanical earth model. Then, two failure criteria, i.e. Mohr–Coulomb and Mogi–Coulomb, were used to investigate the potential of solid production of the well in the initial and depleted conditions of the reservoir. Using these two criteria, we estimated critical collapse pressure and compared them to the reservoir pressure. Solid production occurs if collapse pressure is greater than pore pressure. Results indicate that the two failure criteria show different estimations of solid production potential of the studied reservoir. Mohr–Coulomb failure criterion estimated solid production in both initial and depleted conditions, where Mogi–Coulomb criterion predicted no solid production in the initial condition of reservoir. Based on Mogi–Coulomb criterion, the well may not require completion solutions like perforated liner, until at least 60% of reservoir pressure was depleted which leads to decrease in operation cost and time.

  5. Flow Strength of Shocked Aluminum in the Solid-Liquid Mixed Phase Region

    Reinhart, William

    2011-06-01

    Shock waves have been used to determine material properties under high shock stresses and very-high loading rates. The determination of mechanical properties such as compressive strength under shock compression has proven to be difficult and estimates of strength have been limited to approximately 100 GPa or less in aluminum. The term ``strength'' has been used in different ways. For a Von-Mises solid, the yield strength is equal to twice the shear strength of the material and represents the maximum shear stress that can be supported before yield. Many of these concepts have been applied to materials that undergo high strain-rate dynamic deformation, as in uni-axial strain shock experiments. In shock experiments, it has been observed that the shear stress in the shocked state is not equal to the shear strength, as evidenced by elastic recompressions in reshock experiments. This has led to an assumption that there is a yield surface with maximum (loading)and minimum (unloading), shear strength yet the actual shear stress lies somewhere between these values. This work provides the first simultaneous measurements of unloading velocity and flow strength for transition of solid aluminum to the liquid phase. The investigation describes the flow strength observed in 1100 (pure), 6061-T6, and 2024 aluminum in the solid-liquid mixed phase region. Reloading and unloading techniques were utilized to provide independent data on the two unknowns (τc and τo) , so that the actual critical shear strength and the shear stress at the shock state could be estimated. Three different observations indicate a change in material response for stresses of 100 to 160 GPa; 1) release wave speed (reloading where applicable) measurements, 2) yield strength measurements, and 3) estimates of Poisson's ratio, all of which provide information on the melt process including internal consistency and/or non-equilibrium and rate-dependent melt behavior. The study investigates the strength properties

  6. Norfloxacin mixed solvency based solid dispersions: An in-vitro and in-vivo investigation

    Ravindra Kamble

    2017-05-01

    Full Text Available Norfloxacin (NF is a synthetic fluoro-quinolone molecule that is used for the treatment of urinary tract infections. However, due to its poor aqueous solubility, it has low oral bioavailability. The aim of the present study was to improve the aqueous solubility and dissolution profile of NF by formulating its mixed-solvency based solid dispersions (SDs. The NF-loaded SDs were prepared by a solvent evaporation technique using urea, sodium benzoate and a niacinamide hydrotropic mixture. The prepared SDs were evaluated regarding their solubility, mean particle size, in-vitro drug release and oral bioavailability. The optimized batch showed a high percentage yield of 99.04% , with a mean particle size of 132.91 μm. Optimized SDs Exhibit 96.48% drug release. The oral bioavailabilities of NF from the optimized SDs, drug alone and marketed formulation were evaluated in Wistar rats at a dose of 20.0 mg/kg. In comparison to the drug alone, approximately 6.90- and 5.0-fold increases in AUC and Cmax, respectively, were observed for NF from mixed-solvency based SDs. The superior dissolution rate due to its reduced particle size may have contributed to the increased oral bioavailability. This study demonstrated that mixed-solvency may be an alternative approach for poorly soluble drugs to improve their solubility and oral bioavailability.

  7. The effects of different mixing intensities during anaerobic digestion of the organic fraction of municipal solid waste

    Lindmark, Johan; Eriksson, Per; Thorin, Eva

    2014-01-01

    Highlights: • Effects of mixing on the anaerobic digestion of municipal solid waste. • Digestion of fresh substrate and post-digestion at three mixing intensities were evaluated. • Mixing performed at 150 RPM, 25 RPM and minimally intermittently. • Increased biogas production rates and yields at lower mixing intensities. - Abstract: Mixing inside an anaerobic digester is often continuous and is not actively controlled. The selected mixing regime can however affect both gas production and the energy efficiency of the biogas plant. This study aims to evaluate these effects and compare three different mixing regimes, 150 RPM and 25 RPM continuous mixing and minimally intermittent mixing for both digestion of fresh substrate and post-digestion of the organic fraction of municipal solid waste. The results show that a lower mixing intensity leads to a higher biogas production rate and higher total biogas production in both cases. 25 RPM continuous mixing and minimally intermittent mixing resulted in similar biogas production after process stabilization, while 150 RPM continuous mixing resulted in lower production throughout the experiment. The lower gas production at 150 RPM could not be explained by the inhibition of volatile fatty acids. Cumulative biogas production until day 31 was 295 ± 2.9, 317 ± 1.9 and 304 ± 2.8 N ml/g VS added during digestion of fresh feed and 113 ± 1.3, 134 ± 1.1 and 130 ± 2.3 N ml/g VS added during post digestion for the 150 RPM, 25 RPM and minimally mixed intensities respectively. As well as increasing gas production, optimal mixing can improve the energy efficiency of the anaerobic digestion process

  8. The effects of different mixing intensities during anaerobic digestion of the organic fraction of municipal solid waste

    Lindmark, Johan, E-mail: Johan.lindmark@mdh.se; Eriksson, Per; Thorin, Eva, E-mail: Eva.Thorin@mdh.se

    2014-08-15

    Highlights: • Effects of mixing on the anaerobic digestion of municipal solid waste. • Digestion of fresh substrate and post-digestion at three mixing intensities were evaluated. • Mixing performed at 150 RPM, 25 RPM and minimally intermittently. • Increased biogas production rates and yields at lower mixing intensities. - Abstract: Mixing inside an anaerobic digester is often continuous and is not actively controlled. The selected mixing regime can however affect both gas production and the energy efficiency of the biogas plant. This study aims to evaluate these effects and compare three different mixing regimes, 150 RPM and 25 RPM continuous mixing and minimally intermittent mixing for both digestion of fresh substrate and post-digestion of the organic fraction of municipal solid waste. The results show that a lower mixing intensity leads to a higher biogas production rate and higher total biogas production in both cases. 25 RPM continuous mixing and minimally intermittent mixing resulted in similar biogas production after process stabilization, while 150 RPM continuous mixing resulted in lower production throughout the experiment. The lower gas production at 150 RPM could not be explained by the inhibition of volatile fatty acids. Cumulative biogas production until day 31 was 295 ± 2.9, 317 ± 1.9 and 304 ± 2.8 N ml/g VS added during digestion of fresh feed and 113 ± 1.3, 134 ± 1.1 and 130 ± 2.3 N ml/g VS added during post digestion for the 150 RPM, 25 RPM and minimally mixed intensities respectively. As well as increasing gas production, optimal mixing can improve the energy efficiency of the anaerobic digestion process.

  9. Phase Behaviour and Miscibility Studies of Collagen/Silk Fibroin Macromolecular System in Dilute Solutions and Solid State.

    Ghaeli, Ima; de Moraes, Mariana A; Beppu, Marisa M; Lewandowska, Katarzyna; Sionkowska, Alina; Ferreira-da-Silva, Frederico; Ferraz, Maria P; Monteiro, Fernando J

    2017-08-18

    Miscibility is an important issue in biopolymer blends for analysis of the behavior of polymer pairs through the detection of phase separation and improvement of the mechanical and physical properties of the blend. This study presents the formulation of a stable and one-phase mixture of collagen and regenerated silk fibroin (RSF), with the highest miscibility ratio between these two macromolecules, through inducing electrostatic interactions, using salt ions. For this aim, a ternary phase diagram was experimentally built for the mixtures, based on observations of phase behavior of blend solutions with various ratios. The miscibility behavior of the blend solutions in the miscible zones of the phase diagram was confirmed quantitatively by viscosimetric measurements. Assessing the effects of biopolymer mixing ratio and salt ions, before and after dialysis of blend solutions, revealed the importance of ion-specific interactions in the formation of coacervate-based materials containing collagen and RSF blends that can be used in pharmaceutical, drug delivery, and biomedical applications. Moreover, the conformational change of silk fibroin from random coil to beta sheet, in solution and in the final solid films, was detected by circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR), respectively. Scanning electron microscopy (SEM) exhibited alterations of surface morphology for the biocomposite films with different ratios. Surface contact angle measurement illustrated different hydrophobic properties for the blended film surfaces. Differential scanning calorimetry (DSC) showed that the formation of the beta sheet structure of silk fibroin enhances the thermal stability of the final blend films. Therefore, the novel method presented in this study resulted in the formation of biocomposite films whose physico-chemical properties can be tuned by silk fibroin conformational changes by applying different component mixing ratios.

  10. Solid solution strengthening and diffusion in nickel- and cobalt-based superalloys

    Rehman, Hamad ur

    2016-07-01

    Nickel and cobalt-based superalloys with a γ-γ{sup '} microstructure are known for their excellent creep resistance at high temperatures. Their microstructure is engineered using different alloying elements, that partition either to the fcc γ matrix or to the ordered γ{sup '} phase. In the present work the effect of alloying elements on their segregation behaviour in nickel-based superalloys, diffusion in cobalt-based superalloys and the temperature dependent solid solution strengthening in nickel-based alloys is investigated. The effect of dendritic segregation on the local mechanical properties of individual phases in the as-cast, heat treated and creep deformed state of a nickel-based superalloy is investigated. The local chemical composition is characterized using Electron Probe Micro Analysis and then correlated with the mechanical properties of individual phases using nanoindentation. Furthermore, the temperature dependant solid solution hardening contribution of Ta, W and Re towards fcc nickel is studied. The room temperature hardening is determined by a diffusion couple approach using nanoindentation and energy dispersive X-ray analysis for relating hardness to the chemical composition. The high temperature properties are determined using compression strain rate jump tests. The results show that at lower temperatures, the solute size is prevalent and the elements with the largest size difference with nickel, induce the greatest hardening consistent with a classical solid solution strengthening theory. At higher temperatures, the solutes interact with the dislocations such that the slowest diffusing solute poses maximal resistance to dislocation glide and climb. Lastly, the diffusion of different technically relevant solutes in fcc cobalt is investigated using diffusion couples. The results show that the large atoms diffuse faster in cobalt-based superalloys similar to their nickel-based counterparts.

  11. Solid solution strengthening and diffusion in nickel- and cobalt-based superalloys

    Rehman, Hamad ur

    2016-01-01

    Nickel and cobalt-based superalloys with a γ-γ ' microstructure are known for their excellent creep resistance at high temperatures. Their microstructure is engineered using different alloying elements, that partition either to the fcc γ matrix or to the ordered γ ' phase. In the present work the effect of alloying elements on their segregation behaviour in nickel-based superalloys, diffusion in cobalt-based superalloys and the temperature dependent solid solution strengthening in nickel-based alloys is investigated. The effect of dendritic segregation on the local mechanical properties of individual phases in the as-cast, heat treated and creep deformed state of a nickel-based superalloy is investigated. The local chemical composition is characterized using Electron Probe Micro Analysis and then correlated with the mechanical properties of individual phases using nanoindentation. Furthermore, the temperature dependant solid solution hardening contribution of Ta, W and Re towards fcc nickel is studied. The room temperature hardening is determined by a diffusion couple approach using nanoindentation and energy dispersive X-ray analysis for relating hardness to the chemical composition. The high temperature properties are determined using compression strain rate jump tests. The results show that at lower temperatures, the solute size is prevalent and the elements with the largest size difference with nickel, induce the greatest hardening consistent with a classical solid solution strengthening theory. At higher temperatures, the solutes interact with the dislocations such that the slowest diffusing solute poses maximal resistance to dislocation glide and climb. Lastly, the diffusion of different technically relevant solutes in fcc cobalt is investigated using diffusion couples. The results show that the large atoms diffuse faster in cobalt-based superalloys similar to their nickel-based counterparts.

  12. phase formation and thermal stability of fcc (fluorite) Ce1-xTbxO2-d solid solutions

    de Vries, Karel Jan; de Vries, K.J.; Meng, G.Y.

    1998-01-01

    Ce1−xTbxO2−δ solid solutions (x = 0.3, 0.4, and 0.5) were synthesized by a coprecipitation method, using ammonia. The formation process of the solid solutions was studied as a function of temperature up to 1200°C by X-ray diffraction, thermogravimetric analysis, and differential scanning

  13. Ionic thermocurrents and ionic conductivity of solid solutions of SrF2 and YbF3

    Meuldijk, J.; Hartog, den H.W.

    1983-01-01

    We report dielectric [ionic thermocurrent (!TC)] experiments and ionic conductivity of cubic solid solutions of the type Sr1-xYbxF2+x. These combined experiments provide us with new information concerning the ionic conductivity mechanisms which play an important role in solid solutions Sr1-xRxF2+x

  14. Studies on Al-Mg solid solutions using electrical resistivity and microhardness measurements

    Gaber, A.; Afify, N.; El-Halawany, S.M.; Mossad, A. [Assiut Univ. (Egypt). Dept. of Physics

    1999-08-01

    Al-C at% Mg alloys (C = 0.82, 1.84, 3.76, 5.74 and 12.18) have been selected for this study. From the electrical resistivity measurements it is concluded that the resistivity increment of Al-Mg alloys (in a solid solution state) is proportional to the atomic fractional constituents (Mg and Al) as {delta}{rho}{sub all} = 64.66 c(1-c) {mu}{omega} cm. In addition, both the temperature coefficient of resistivity, {alpha}{sub all} and the relaxation time of the free electrons {tau}{sub all} in the alloys diminish with increasing the solute Mg concentration. The increase of the scattering power, {eta}, with increasing C is interpreted to be due to the contribution of electron-impurity scattering. The percentage increase due to electron-impurity scattering per one atomic percent Mg has been determined as 12.99%. The Debye temperature {theta} decreases as the Mg concentration increases. The microhardness results showed that the solid solution hardening obeys the relation {delta}HV{sub s} = 135.5C{sup 0.778} MPa which is comparable to the theory of solid solution hardening for all alloys; {delta}HV{sub s} {approx} C{sup 0.5-0.67} MPa. (orig.)

  15. KEMOD: A mixed chemical kinetic and equilibrium model of aqueous and solid phase geochemical reactions

    Yeh, G.T.; Iskra, G.A.

    1995-01-01

    This report presents the development of a mixed chemical Kinetic and Equilibrium MODel in which every chemical species can be treated either as a equilibrium-controlled or as a kinetically controlled reaction. The reaction processes include aqueous complexation, adsorption/desorption, ion exchange, precipitation/dissolution, oxidation/reduction, and acid/base reactions. Further development and modification of KEMOD can be made in: (1) inclusion of species switching solution algorithms, (2) incorporation of the effect of temperature and pressure on equilibrium and rate constants, and (3) extension to high ionic strength

  16. Synthesis, characterization, kinetic and thermodynamic studies of the dissolution of ThO2 and of solid solutions Th1-xMxO2 (M = U, Pu)

    Heisbourg, G.

    2003-12-01

    The aim of this work was to understand the mechanisms of dissolution of ThO 2 and of thorium mixed oxides such as Th 1-x U x O 2 and Th 1-x Pu x O 2 in aqueous, oxygenated or inert media. Several solids have been synthesized by precipitation in oxalic medium: Th 1-x U x O 2 (x= 0.11; 0.24; 0.37; 0.53; 0.67; 0.81 and 0.91) and Th 1-x Pu x O 2 (x= 0.13; 0.32 and 0.66). They have been characterized by XRD, SEM, TEM, XPS, XAS, PIXE and EPMA. The sintering conditions of these materials have been studied and optimized in order to obtain sintered samples with a measured density very near the theoretical densities. A kinetic study of the dissolution of ThO 2 and of solid solutions Th 1-x U x O 2 has been carried out in several aqueous media (HNO 3 , HCl, H 2 SO 4 ) in terms of several parameters: protons concentration, temperature, pH, ionic strength, nature of the electrolyte solution and uranium molar ratio for the solid solutions Th 1-x U x O 2 in order to determine the kinetic laws of dissolution of the solid solutions having different compositions comparatively to ThO 2 . The leaching tests carried out in natural waters of compositions near those of the deep geologic sites considered for the storage of nuclear wastes have shown that the dissolution of the solids was bound to the complexing effect of the constitutional ions of the water considered. The leaching tests carried out on sintered samples of the same composition have led to the same normalized dissolution velocities. The thermodynamic aspect of the dissolution of the solid solutions Th 1-x U x O 2 in nitric medium has been studied at last. (O.M.)

  17. Relating hydrogen-bonding interactions with the phase behavior of naproxen/PVP K 25 solid dispersions: evaluation of solution-cast and quench-cooled films.

    Paudel, Amrit; Nies, Erik; Van den Mooter, Guy

    2012-11-05

    In this work, we investigated the relationship between various intermolecular hydrogen-bonding (H-bonding) interactions and the miscibility of the model hydrophobic drug naproxen with the hydrophilic polymer polyvinylpyrrolidone (PVP) across an entire composition range of solid dispersions prepared by quasi-equilibrium film casting and nonequilibrium melt quench cooling. The binary phase behavior in solid dispersions exhibited substantial processing method dependence. The solid state solubility of crystalline naproxen in PVP to form amorphous solid dispersions was 35% and 70% w/w naproxen in solution-cast films and quench-cooled films, respectively. However, the presence of a single mixed phase glass transition indicated the amorphous miscibility to be 20% w/w naproxen for the films, beyond which amorphous-amorphous and/or crystalline phase separations were apparent. This was further supported by the solution state interactions data such as PVP globular size distribution and solution infrared spectral profiles. The borderline melt composition showed cooling rate dependence of amorphization. The glass transition and melting point depression profiles of the system were treated with the analytical expressions based on Flory-Huggins mixing theory to interpolate the equilibrium solid solubility. FTIR analysis and subsequent spectral deconvolution revealed composition and miscibility dependent variations in the strength of drug-polymer intermolecular H-bonding. Two types of H-bonded populations were evidenced from 25% w/w and 35% w/w naproxen in solution-cast films and quench-cooled films, respectively, with the higher fraction of strongly H-bonded population in the drug rich domains of phase separated amorphous film compositions and highly drug loaded amorphous quench-cooled dispersions.

  18. EPR of gamma irradiated solid sucrose and UV spectra of its solution. An attempt for calibration of solid state/EPR dosimetry

    Yordanov, N.D.; Karakirova, Y.

    2007-01-01

    A simple new approach for independent calibration of solid state/EPR (SS/EPR) dosimetry system is reported. It is based on the fact that: (i) gamma-irradiation of solid sucrose (sugar) induces stable EPR detectable free radicals accompanied by UV detectable brown colour stable in the solid state and in solution; (ii) both the EPR intensity of gamma-irradiated solid sucrose and its solution UV absorbance linearly depend on the absorbed dose high energy radiation and may be independently used for dosimetric purpose; (iii) UV spectrometers are calibrated. The correlation between EPR response and absorbed dose radiation of solid sucrose and UV absorption of its solutions is used in the present communication for calibration purpose. The procedure of sucrose extraction from sucrose-paraffin dosimeters is described. The calibration procedure may be applied to any other (alanine, self-calibrated, etc.) SS/EPR dosimeters, simultaneously irradiated with sucrose

  19. Exact solutions for oscillators with quadratic damping and mixed-parity nonlinearity

    Lai, S K; Chow, K W

    2012-01-01

    Exact vibration modes of a nonlinear oscillator, which contains both quadratic friction and a mixed-parity restoring force, are derived analytically. Two families of exact solutions are obtained in terms of rational expressions for classical Jacobi elliptic functions. The present solutions allow the investigation of the dynamical behaviour of the system in response to changes in physical parameters that concern nonlinearity. The physical significance of the signs (i.e. attractive or repulsive nature) of the linear, quadratic and cubic restoring forces is discussed. A qualitative analysis is also conducted to provide valuable physical insight into the nature of the system. (paper)

  20. A fluorescent chemosensor for Zn(II). Exciplex formation in solution and the solid state.

    Bencini, Andrea; Berni, Emanuela; Bianchi, Antonio; Fornasari, Patrizia; Giorgi, Claudia; Lima, Joao C; Lodeiro, Carlos; Melo, Maria J; de Melo, J Seixas; Parola, Antonio Jorge; Pina, Fernando; Pina, Joao; Valtancoli, Barbara

    2004-07-21

    The macrocyclic phenanthrolinophane 2,9-[2,5,8-triaza-5-(N-anthracene-9-methylamino)ethyl]-[9]-1,10-phenanthrolinophane (L) bearing a pendant arm containing a coordinating amine and an anthracene group forms stable complexes with Zn(II), Cd(II) and Hg(II) in solution. Stability constants of these complexes were determined in 0.10 mol dm(-3) NMe(4)Cl H(2)O-MeCN (1:1, v/v) solution at 298.1 +/- 0.1 K by means of potentiometric (pH metric) titration. The fluorescence emission properties of these complexes were studied in this solvent. For the Zn(II) complex, steady-state and time-resolved fluorescence studies were performed in ethanol solution and in the solid state. In solution, intramolecular pi-stacking interaction between phenanthroline and anthracene in the ground state and exciplex emission in the excited state were observed. From the temperature dependence of the photostationary ratio (I(Exc)/I(M)), the activation energy for the exciplex formation (E(a)) and the binding energy of the exciplex (-DeltaH) were determined. The crystal structure of the [ZnLBr](ClO(4)).H(2)O compound was resolved, showing that in the solid state both intra- and inter-molecular pi-stacking interactions are present. Such interactions were also evidenced by UV-vis absorption and emission spectra in the solid state. The absorption spectrum of a thin film of the solid complex is red-shifted compared with the solution spectra, whereas its emission spectrum reveals the unique featureless exciplex band, blue shifted compared with the solution. In conjunction with X-ray data the solid-state data was interpreted as being due to a new exciplex where no pi-stacking (full overlap of the pi-electron cloud of the two chromophores - anthracene and phenanthroline) is observed. L is a fluorescent chemosensor able to signal Zn(II) in presence of Cd(II) and Hg(II), since the last two metal ions do not give rise either to the formation of pi-stacking complexes or to exciplex emission in solution.

  1. In-core LOCA-s: analytical solution for the delayed mixing model for moderator poison concentration

    Firla, A.P.

    1995-01-01

    Solutions to dynamic moderator poison concentration model with delayed mixing under single pressure tube / calandria tube rupture scenario are discussed. Such a model is described by a delay differential equation, and for such equations the standard ways of solution are not directly applicable. In the paper an exact, direct time-domain analytical solution to the delayed mixing model is presented and discussed. The obtained solution has a 'marching' form and is easy to calculate numerically. Results of the numerical calculations based on the analytical solution indicate that for the expected range of mixing times the existing uniform mixing model is a good representation of the moderator poison mixing process for single PT/CT breaks. However, for postulated multi-pipe breaks ( which is very unlikely to occur ) the uniform mixing model is not adequate any more; at the same time an 'approximate' solution based on Laplace transform significantly overpredicts the rate of poison concentration decrease, resulting in excessive increase in the moderator dilution factor. In this situation the true, analytical solution must be used. The analytical solution presented in the paper may also serve as a bench-mark test for the accuracy of the existing poison mixing models. Moreover, because of the existing oscillatory tendency of the solution, special care must be taken in using delay differential models in other applications. (author). 3 refs., 3 tabs., 8 figs

  2. Performance Issues Along the Six Elements of Holcim Solusi Rumah's Marketing Mix and Solution Recommedations

    Susana, Apriliani Dewi; Titus, Amol

    2013-01-01

    This study aims at identifying key issues in SR franchise business along the six elements of marketing mix: people, partner, place, product, promotion, and price, and then propose solution recommendations for the identified issues. Data is collected through a method of in-depth interviews with key SR stakeholders, internally and externally, namely end customers, SR personnels, and SR franchisees. Issues identified are mapped into a Problem Tree Analysis diagram to determine causal relations...

  3. Performance of direct alcohol fuel cells fed with mixed methanol/ethanol solutions

    Wongyao, N. [The Joint Graduate School of Energy and Environment, King Mongkut' s University of Technology Thonburi, 126 Pracha-Uthit Rd., Bang Mod, Thung Khru, Bangkok 10140 (Thailand); Therdthianwong, A., E-mail: apichai.the@kmutt.ac.t [Fuel Cell and Hydrogen Research and Engineering Center, Clean Energy System Group, PDTI, King Mongkut' s University of Technology Thonburi, 126 Pracha-Uthit Rd., Bang Mod, Thung Khru, Bangkok 10140 (Thailand); Therdthianwong, S. [Department of Chemical Engineering, Faculty of Engineering, King Mongkut' s University of Technology Thonburi, 126 Pracha-Uthit Rd., Bang Mod, Thung Khru, Bangkok 10140 (Thailand)

    2011-07-15

    Research highlights: {yields} We examined the performance of direct alcohol fuel cells fed with mixed alcohol. {yields} PtRu-PtSn/C and PtRu/C as catalysts for mixed alcohol electrooxidation reaction. {yields} Misplace adsorption of ethanol on PtRu/C caused the cell performance drop. {yields} PtRu/C showed higher performance than PtRu-PtSn/C for mixed alcohol fuel. -- Abstract: In combining the advantages of both methanol and ethanol, direct alcohol fuel cells fed with mixed alcohol solutions (1 M methanol and 1 M ethanol in varying volume ratios) were tested for performance. Employing a PtRu-PtSn/C catalyst as anode, cell performance was found to diminish rapidly even at 2.5% by volume ethanol mixture. Further increase of ethanol exceeded 10%, the cell performance gradually decreased and finally approached that of direct ethanol fuel cells. The causes of the decrease in the cell performance were the slow electro-oxidation of ethanol and the misplaced adsorption of ethanol on PtRu/C. By comparing the PtRu-PtSn/C cell with the PtRu/C cell operated with mixed alcohol solutions, the cell using PtRu/C as an anode catalyst provided higher power density since more PtRu/C surface was available for methanol oxidation reaction and less ohmic resistance of PtRu/C than that of PtRu-PtSn/C. In order to reach optimization of DAFC performance fed with mixed alcohol, the electrocatalyst used for the anode must selectively adsorb an alcohol, especially ethanol.

  4. Performance of direct alcohol fuel cells fed with mixed methanol/ethanol solutions

    Wongyao, N.; Therdthianwong, A.; Therdthianwong, S.

    2011-01-01

    Research highlights: → We examined the performance of direct alcohol fuel cells fed with mixed alcohol. → PtRu-PtSn/C and PtRu/C as catalysts for mixed alcohol electrooxidation reaction. → Misplace adsorption of ethanol on PtRu/C caused the cell performance drop. → PtRu/C showed higher performance than PtRu-PtSn/C for mixed alcohol fuel. -- Abstract: In combining the advantages of both methanol and ethanol, direct alcohol fuel cells fed with mixed alcohol solutions (1 M methanol and 1 M ethanol in varying volume ratios) were tested for performance. Employing a PtRu-PtSn/C catalyst as anode, cell performance was found to diminish rapidly even at 2.5% by volume ethanol mixture. Further increase of ethanol exceeded 10%, the cell performance gradually decreased and finally approached that of direct ethanol fuel cells. The causes of the decrease in the cell performance were the slow electro-oxidation of ethanol and the misplaced adsorption of ethanol on PtRu/C. By comparing the PtRu-PtSn/C cell with the PtRu/C cell operated with mixed alcohol solutions, the cell using PtRu/C as an anode catalyst provided higher power density since more PtRu/C surface was available for methanol oxidation reaction and less ohmic resistance of PtRu/C than that of PtRu-PtSn/C. In order to reach optimization of DAFC performance fed with mixed alcohol, the electrocatalyst used for the anode must selectively adsorb an alcohol, especially ethanol.

  5. New Portland cement-based materials for endodontics mixed with articaine solution: a study of cellular response.

    Gandolfi, Maria Giovanna; Perut, Francesca; Ciapetti, Gabriela; Mongiorgi, Romano; Prati, Carlo

    2008-01-01

    The biocompatibility of innovative tetrasilicate cements proposed for root-end filling restorations was tested. White ProRoot-MTA and AH Plus were used as control. The new cements were mixed with a local anesthetic solution (4% articaine) to form a paste. Human osteoblast-like cells Saos-2 were challenged in short-term cultures (72 hours) with solid materials and with material extracts prepared in culture medium. Cell growth and viability, cellular attachment, and morphologic features were assessed to verify cell/material interactions. No acute toxicity was exerted by the experimental cements in the assay systems. On solid samples Saos-2 adhered and proliferated on all the experimental cements and on MTA. The ultrastructural findings revealed that Saos-2 were able to adhere and to spread. The maintenance of the osteoblastic phenotype on the innovative cements was confirmed by the alkaline phosphatase assay. All experimental cements prepared with articaine supported the growth of bone-like cells, showing suitable properties to be used as canal sealers and root-end filling materials.

  6. Cathodic electrodeposition of mixed molybdenum tungsten oxides from peroxo-polymolybdotungstate solutions.

    Kondrachova, Lilia; Hahn, Benjamin P; Vijayaraghavan, Ganesh; Williams, Ryan D; Stevenson, Keith J

    2006-12-05

    Mixed molybdenum tungsten trioxide films of varying stoichiometry (MoxW1 - xO3, 0 cathodic electrodeposition on indium tin oxide (ITO)-coated glass substrates from aqueous peroxo-polymolybdotungstate solutions. Electrochemical quartz crystal microbalance (EQCM), cyclic voltammetry, and chronocoulometry were used to gain insight into the electrodeposition mechanism. The compositional and structural properties were characterized for MoxW1 - xO3 films deposited at intermediate potentials (-0.35 V vs Ag/AgCl) and sintered at 250 degrees C using energy-dispersive spectroscopy, X-ray diffraction, and Raman spectroscopy. These studies reveal that films consist of homogeneously mixed MoxW1 - xO3, with an enriched Mo content ranging in composition from 0.4 < x < 0.7 depending upon the mol % Mo present in the deposition solution. Chronoamperometry and spectroelectrochemical measurements were conducted to estimate lithium ion diffusion coefficients and coloration efficiencies for the mixed metal oxide films in 1 M LiClO4/propylene carbonate. The subtle interplay between structural and compositional properties due to the uniform mixing of Mo and W oxide components shows that electrochromic and lithium ion transport properties are moderately enhanced relative to those of single-component WO3 and MoO3 and demonstrate improved structural stability over pure MoO3 polymorphs during electrochemical cycling.

  7. Giant asymmetry of separation and homogenization processes in solid 3He-4He solutions

    Grigor'ev, V.N.; Majdanov, V.A.; Penzev, A.A.; Polev, A.V.; Rubets, S.P.; Rudavskij, Eh.Ya.; Rybalko, A.S.; Syrnikov, E.V.

    2005-01-01

    The kinetics of the processes of separation and homogenization of solid 3 He- 4 He solutions is compared by using the precision barometry. The experiments were made with the initial specimens of three types: weak 3 He- 4 He and 4 He- 3 He solutions and concentrated 3 He- 4 He ones. It is found that the homogenization rate at the initial stage may be more than 500 times higher that the rate of separation. This is the case for all types of the solutions studied. The appreciable rate of phase separation in the concentrated solutions where, according to the modern concepts, impurity atoms in quantum crystals should be localized, suggests that in such conditions there is a new unknown mechanism of mass-transfer, while the fast homogenization points to a nondiffusion nature of the process

  8. The crystallization of a solid solution in a solvent and the stability of a growth interface

    Malmejac, Yves

    1971-03-01

    The potential uses of germanium-silicon alloys as thermoelectric generators in hitherto unexploited temperature ranges initiated the present study. Many delicate problems are encountered in the classical methods of preparation. An original technique was sought for crystallization in a metallic solvent. The thermodynamic equilibria between the various phases of the ternary System used were studied in order to justify the method used. The conditions (temperature and composition) were determined in which the cooling of a ternary liquid mixture induces the precipitation of a binary solid solution with the desired composition. If large crystals are to be obtained from the solid solution, metallic solvent precipitation must be replaced by a mono-directional solvent crystallization. The combined effect of a certain number of simple physical phenomena on the stability of a crystal liquid interface was studied: the morphological stability of the crystal growth interface is the first step towards obtaining perfect crystals. (author) [fr

  9. The investigation of solid solutions thin interlayers in CdS/CdTe film heterosystems

    Khrypunov, G.; Boyko, B.; Chernykh, O.

    1999-01-01

    The photo-response spectral dependence of ITO/CdTe/Au/Cu and ITO/CdS/CdTe/Au/Cu film heterosystems were investigated. At illuminations ITO/CdS/CdTe/Au/Cu heterosystems on ITO side a photo-response maximum was observed for photon absorption with a wavelength of 0.87 μm that is stipulated by formation of CdS x Te 1-x solid solutions interlayer with band gap width less than in CdTe layer. By use optical measurement transmittance spectra was selected a spectral photosensitivity interval appropriate to the contribution of non-equilibrium charge carriers generated in solid solutions interlayer by photon absorption with energy less than CdTe film band gap

  10. Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

    Zhang, Yanwen; Wang, Lumin; Caro, Alfredo; Weber, William J.; Univ. of Tennessee, Knoxville, TN

    2015-01-01

    A long-standing objective in materials research is to understand how energy is dissipated in both the electronic and atomic subsystems in irradiated materials, and how related non-equilibrium processes may affect defect dynamics and microstructure evolution. Here we show that alloy complexity in concentrated solid solution alloys having both an increasing number of principal elements and altered concentrations of specific elements can lead to substantial reduction in the electron mean free path and thermal conductivity, which has a significant impact on energy dissipation and consequentially on defect evolution during ion irradiation. Enhanced radiation resistance with increasing complexity from pure nickel to binary and to more complex quaternary solid solutions is observed under ion irradiation up to an average damage level of 1 displacement per atom. Understanding how materials properties can be tailored by alloy complexity and their influence on defect dynamics may pave the way for new principles for the design of radiation tolerant structural alloys

  11. Calorimetric measurements on plutonium rich (U,Pu)O2 solid solutions

    Kandan, R.; Babu, R.; Nagarajan, K.; Vasudeva Rao, P.R.

    2008-01-01

    Enthalpy increments of U (1-y) Pu y O 2 solid solutions with y = 0.45, 0.55 and 0.65 were measured using a high-temperature differential calorimeter by employing the method of inverse drop calorimetry in the temperature range 956-1803 K. From the fit equations for the enthalpy increments, other thermodynamic functions such as heat capacity, entropy and Gibbs energy function have been computed in the temperature range 298-1800 K. The results are presented and compared with the data available in the literature. The results indicate that the enthalpies of U (1-y) Pu y O 2 solid solutions with y = 0.45, 0.55 and 0.65 obey the Neumann-Kopp's molar additivity rule

  12. Influence of chemical heterogeneity of solid solutions on brittleness in chromium steels

    Madyanov, S.A.; Sedov, V.K.; Apaev, B.A.

    1985-01-01

    The role of chemical heterogeneity of solid solutions in formation of mechanical properties of Kh09, Kh15, Kh20, Kh19N2G5T chromium steels has been investigated. It is established that besides the known regioA of chemical heterogeneity in the vicinity of 475 deg C exists a high-temperature region (1000-1050 deg C), where maximum heteroge=- neity of chromium distribution in solid solution, is observed. Both types of chemical heterogeneity cause essential hardening of alloys, which becomes apparent in abrupt change of capability to microplastic deformation The mechanism of occurrence of the given temper brittleness consists in carbon diffusion into microvolunes enriched in carbide-forming elements

  13. Formation of soft magnetic high entropy amorphous alloys composites containing in situ solid solution phase

    Wei, Ran; Sun, Huan; Chen, Chen; Tao, Juan; Li, Fushan

    2018-03-01

    Fe-Co-Ni-Si-B high entropy amorphous alloys composites (HEAACs), which containing high entropy solid solution phase in amorphous matrix, show good soft magnetic properties and bending ductility even in optimal annealed state, were successfully developed by melt spinning method. The crystallization phase of the HEAACs is solid solution phase with body centered cubic (BCC) structure instead of brittle intermetallic phase. In addition, the BCC phase can transformed into face centered cubic (FCC) phase with temperature rise. Accordingly, Fe-Co-Ni-Si-B high entropy alloys (HEAs) with FCC structure and a small amount of BCC phase was prepared by copper mold casting method. The HEAs exhibit high yield strength (about 1200 MPa) and good plastic strain (about 18%). Meanwhile, soft magnetic characteristics of the HEAs are largely reserved from HEAACs. This work provides a new strategy to overcome the annealing induced brittleness of amorphous alloys and design new advanced materials with excellent comprehensive properties.

  14. Microstructure and Mechanical Strengths of Metastable FCC Solid Solutions in Al-Ce-Fe System

    A., Inoue; H., Yamaguchi; M., Kikuchi; T., Masumoto; Institute for Materials Research; Institute for Materials Research; Institute for Materials Research; Institute for Materials Research

    1990-01-01

    A metastable fcc solid solution (SS) with high mechanical strengths and good bending ductility was found to be formed in rapidly solidified Al-Ce-Fe alloys containing the solute elements below about 6 at%. The SS consists of equiaxed grains with a size of about 2μm and contains a high density of internal defects. The highest hardness (H_v) and tensile fracture strengtn (σ_f) are 440 and 860 MPa in the as-quenched state and remain almost unchanged up to about 600 K for 1 h, though fine compoun...

  15. Phase transitions in solid Kr-CH4 solutions and rotational excitations in phase II

    Bagatskii, M.I.; Mashchenko, D.A.; Dudkin, V.V.

    2007-01-01

    The heat capacity C p of solid Kr-n CH 4 solutions with the CH 4 concentrations n=0.82, 0.86, 0.90 as well as solutions with n=0.90, 0.95 doped with 0.002 O 2 impurity has been investigated under equilibrium vapor pressure over the internal 1-24 K. The (T,n)-phase diagram was refined and the region of two-phase states was determined for Kr-n CH 4 solid solutions. The contribution of the rotational subsystem, C r ot, to the heat capacity of the solutions has been separated. Analysis of C r ot(T) at T 1 and E 2 between the tunnel levels of the A-, T- and A-, E--nuclear-spin species of CH 4 molecules in the orientationally ordered subsystem, and to determine the effective energy gaps E 1 between lowest levels of the A- and T- species. The relations τ(n) and E 1 (n) stem from changes of the effective potential field caused as the replacement of CH 4 molecules by Kr atoms at sites of the ordered sublattices. The effective gaps E L between a group of tunnel levels of the ground-state liberation state and the nearest group of excited levels of the liberation state of the ordered CH 4 molecules in the solutions with n=0.90 (E L =52 K) and 0.95 (E L =55 K) has been estimated

  16. Three wave mixing test of hyperelasticity in highly nonlinear solids: sedimentary rocks.

    D'Angelo, R M; Winkler, K W; Johnson, D L

    2008-02-01

    Measurements of three-wave mixing amplitudes on solids whose third order elastic constants have also been measured by means of the elasto-acoustic effect are reported. Because attenuation and diffraction are important aspects of the measurement technique results are analyzed using a frequency domain version of the KZK equation, modified to accommodate an arbitrary frequency dependence to the attenuation. It is found that the value of beta so deduced for poly(methylmethacrylate) (PMMA) agrees quite well with that predicted from the stress-dependent sound speed measurements, establishing that PMMA may be considered a hyperelastic solid, in this context. The beta values of sedimentary rocks, though they are typically two orders of magnitude larger than, e.g., PMMA's, are still a factor of 3-10 less than those predicted from the elasto-acoustic effect. Moreover, these samples exhibit significant heterogeneity on a centimeter scale, which heterogeneity is not apparent from a measurement of the position dependent sound speed.

  17. Tensometrical properties of volumetric crystals of germanium-silicon solid solutions irradiated by fast electrons

    Abbasov, Sh.M.

    2002-01-01

    Full Text: In the present work the tensometrical properties of Ge1-xSix solid solution monocrystal contended of up to 15 at. % Si were investigated. The radiation-proof strain gauges of researched crystals were made. For this purpose the site was cutted out from a sample, perpendicularly or in parallel of a crystal axes. After polishing the samples had thickness of 30-40 microns, and length of 2 mm

  18. First-principles investigations of solid solution strengthening in Al alloys

    Ma, Duancheng

    2012-01-01

    Any material properties, in principle, can be reproduced or predicted by performing firstprinciples calculations. Nowadays, however, we are dealing with complex alloy compositions and processes. The complexities cannot be fully described by first-principles, because of the limited computational power. The primary objective of this study is to investigate an important engineering problem, solid solution strengthening, in a simplified manner. The simplified scheme should allow fast and reliable...

  19. Studying the Super-cooled Solid Solution Breakdown of V-1341 Aluminum Alloy

    Yu. A. Puchkov

    2017-01-01

    Full Text Available Deformable alloys of the Al-Mg-Si system are widely used in aviation industry, rocket engineering, shipbuilding, as well as on railway and highway transport. These alloys are characterized by high stamping ability, weld-ability, and machinability with a comparatively high strength and corrosion resistance in a heat-strengthened state. A promising alloy of the Al-Mg-Si system with increased structural strength and manufacturability is on par with foreign analogues in properties is the V-1341 alloy [1, 2].The properties of heat-treatable aluminum alloys strongly depend on the cooling rate of the product during quenching [3-12], which determines the structure and level of residual stresses. Decrease in structural strength, tendency to pitting and inter-crystalline corrosion with slow cooling from the quenching temperature is caused by formation of coarse unequiaxed precipitate, precipitates-free zones, and also by decreasing proportion of inclusions of the strengthening phase [3-12].Thus, the relevant task is to study the effect of isothermal quenching modes on the structure of deformable V-1341 aluminum alloy thermally hardened.The paper studies the impact of isothermal time in quenching on the composition and morphology of breakdown products of the V-1341 alloy solid solution. It is shown that at isothermal time under the solid solution breakdown, at first on the dispersoid surface and then in the solid solution are formed and grow large needle-like crystals of the β'-phase which are structural concentrators of stresses. An increasing isothermal time leads to decreasing solid solution super-saturation by doping elements and vacancies. This leads to a decrease in the fraction of the coherent finely dispersed hardening β '' phase, and also to an increase in the width of the precipitates-free zone.

  20. Long-term behavior of refractory thorium-plutonium dioxide solid solutions

    Claparede, Laurent, E-mail: laurent.claparede@umontpellier.fr [ICSM, UMR 5257 CNRS/CEA/Univ. Montpellier/ENSCM, Site de Marcoule, Bât. 426, BP 17171, 30207 Bagnols/Cèze (France); Guigue, Mireille [CEA, Nuclear Energy Division, RadioChemistry & Processes Department, BP 17171, 30207 Bagnols/Cèze (France); Jouan, Gauthier [CEA, Nuclear Energy Division, DTEC Department, BP 17171, 30207 Bagnols/Cèze (France); Nadah, Nassima [CEA, Nuclear Energy Division, RadioChemistry & Processes Department, BP 17171, 30207 Bagnols/Cèze (France); Dacheux, Nicolas [ICSM, UMR 5257 CNRS/CEA/Univ. Montpellier/ENSCM, Site de Marcoule, Bât. 426, BP 17171, 30207 Bagnols/Cèze (France); Moisy, Philippe [CEA, Nuclear Energy Division, RadioChemistry & Processes Department, BP 17171, 30207 Bagnols/Cèze (France)

    2017-01-15

    The long-term behavior of Th{sub 0.87}Pu{sub 0.13}O{sub 2} was examined in nitric acid concentrations. The normalized dissolution rates after 3380 days, range from (1.4 ± 0.2) × 10{sup −6} g m{sup −2} d{sup −1} in 5 M HNO{sub 3} down to (3.2 ± 0.4) × 10{sup −8} g m{sup −2} d{sup −1} in 10{sup −3} M HNO{sub 3}, which confirms the high chemical durability of this solid solution. The amounts of plutonium measured in solution lead to 0.9% and 2.1% of dissolved solid in 1 M and 5 M HNO{sub 3}, respectively. In such conditions, the time required to reach the full dissolution of the material varies from 430 years (5 M HNO{sub 3}) to 18,000 years (10{sup −3} M HNO{sub 3}). Moreover, the partial order related to the proton activity (n = 0.45 ± 0.03) suggests that the dissolution is mainly driven by surface reactions occurring at the solid/liquid interface. The characterization of the leached samples by SEM shows small microstructural modifications (i.e. detachment of crystallites) and the absence of neoformed phase while from PXRD, the unit cell parameter and crystallite size are not significantly affected. - Highlights: • Leaching tests of Th{sub 0.87}Pu{sub 0.13}O{sub 2} were performed for 9 years in several nitric acid solutions. • The high chemical durability of thorium-plutonium oxide solid solutions was confirmed. • The solubility of plutonium(IV) was not controlled by the precipitation of plutonium tetrahydroxide in these experiments.

  1. Mesoporous yttria-zirconia and metal-yttria-zirconia solid solutions for fuel cells

    Mamak, M.; Coombs, N.; Ozin, G. [Toronto Univ., ON (Canada). Dept. of Chemistry

    2000-02-03

    A new class of binary mesoporous yttria-zirconia (YZ) and ternary mesoporous metal-YZ materials (M = electroactive Ni/Pt) is presented here that displays the highest surface area of any known form of yttria-stabilized zirconia. These mesoporous materials form as solid solutions and retain their structural integrity to 800 C, which bodes well for their possible utilization in fuel cells. (orig.)

  2. Structural transformation in mechanosynthesized bcc Fe-Al-Si(Ge) solid solutions during heating

    Kubalova, L.M.; Sviridov, I.A.; Vasilyeva, O.Ya.; Fadeeva, V.I.

    2007-01-01

    X-ray diffractometry and Moessbauer spectroscopy study of Fe 50 Al 25 Si 25 and Fe 50 Al 25 Ge 25 alloys obtained by mechanical alloying (MA) of elementary powders was carried out. Phase transformation during heating of synthesized products was studied using differential scanning calorimetry (DSC). After 2.5 h of MA monophase alloys containing bcc Fe(Al, Ge) solid solutions Fe(Al, Si) are formed. Fe(Al, Si) is partially ordered B2 type and Fe(Al, Ge) is completely disordered. DSC curves of synthesized alloys displayed the presence of exothermal peaks caused by phase transformation. The metastable Fe(Al, Si) solid solution transformed into FeAl 1-x Si x (B2) and FeSi 1-x Al x (B20) equilibrium phases. The Fe(Al, Ge) solid solution transformed into equilibrium phases through intermediate stage of Fe 6 Ge 3 Al 2 metastable phase formation. The Fe 6 Ge 3 Al 2 phase dissociated into three equilibrium phases: FeAl 1-x Ge x (B2), χ-Fe 6 Ge 5 and η-Fe 13 (Ge, Al) 8 (B8 2 ). The structure of Fe 6 Ge 3 Al 2 was calculated by Rietveld method, the distribution of Al and Ge in the elementary cell and its parameters were calculated. Moessbauer study showed that Fe(Al, Si) and Fe(Al, Ge) solid solutions are paramagnetic. In the equilibrium state the alloy containing Si is also paramagnetic while the alloy with Ge showed ferromagnetic properties

  3. Electron paramagnetic resonance response and magnetic interactions in ordered solid solutions of lithium nickel oxides

    Azzoni, C.B. [Istituto Nazionale di Fisica della Materia, Dipartimento di Fisica ' Alessandro Volta' , Universita di Pavia, Pavia (Italy); Paleari, A. [Istituto Nazionale di Fisica della Materia, Dipartimento di Fisica, Universita di Milano, Milan (Italy); Massarotti, V.; Capsoni, D. [Dipartimento di Chimica-Fisica, Universita di Pavia, Pavia (Italy)

    1996-09-23

    EPR data of ordered solid solutions of lithium nickel oxides are reported as a function of the lithium content. The features of the signal and the EPR centre density are analysed by a model of dynamical trapping of holes in [(Ni{sup 2+}-O-Ni{sup 2+})-h{sup +}] complexes. The possible origin of the interactions responsible for the magnetic ordering and some features of the transport properties are also discussed. (author)

  4. Contribution to the study of the structure of silver krypton solid solutions

    Levy, V.; Tullairet, J.; Delaplace, J.; Antolin-Baudier, J.; Adda, Y.

    1964-01-01

    The silver-krypton solid solutions formed by electrical discharge have been studied by X-rays, electrical resistivity and electronic transmission microscopy. The crystalline parameter and residual resistivity measurements have shown that the krypton atom behaves very differently to those of other elements of the periodic classification when dissolved in silver. The recovery of the crystalline parameter and of the electrical resistivity has been studied as a function of temperature. (authors) [fr

  5. Small interstitial clusters as opposite defect recombinators in decomposing solid solutions under irradiation

    Orlov, A.N.; Trushin, Yu.V.

    1988-01-01

    An attempt was made to make allowance for the role of binary and ternary interstitials in the kinetics of radiation point defects both in the presence and in the absence of coherent preseparation. It is shown that in solid solutions, decomposing under irradiation, recombination with binary and ternary interstitials proceeds more quickly than directly, and this difference is more pronounced (from 2 up to 20 time growth) due to defect flow for preseparation at the stage of coherent preseparation formation

  6. Solid solution inhomogeneity in DC-cast AlMn(Fe,Si) ingots

    Lakner, J.; Kovacs-Csetenyi, E.; Lal, K.

    1990-01-01

    The aim of this work was to characterize the structure in cast state of the AlMn1 alloy containing different Fe and Si concentration. The casting parameters were intended to keep constant and the effect of impurities was studied. The inhomogeneity along the diameter of cast billet was characterized by the dendrite arm spacing and by the solid solution content. To explain the results the model developed for binary AlFe and AlMn alloys was applied

  7. Decomposition of supersaturated solid solutions Mg-Ho and Mg-Gd

    Sukhanov, V.D.; Dobromyslov, A.V.; Rokhlin, L.L.; Dobatkina, T.V.

    2002-01-01

    Methods of electron microscopy and X-ray diffraction analysis are applied to study ageing magnesium base alloys with holmium and gadolinium. It is shown that the precipitation of supersaturated Mg base solid solutions goes through several subsequent stages and is accompanied by a considerable precipitation hardening effect at the stage of metastable phase precipitation. The influence of aging time and temperature on precipitation kinetics is established [ru

  8. Photophysical processes study for poly (P-substituted styrenes) in solid films and in solutions

    Al-Hakeem, I.A.

    1985-01-01

    In this work, the absorption and emission spectra of poly (P-NN dimethyl amino styrene), poly (P-Fluoro Styrene), poly (P-CH2OCH3 styrene), poly (P-Methyl (styrene), poly(P-Tertiary butyl styrene) have been studied in solid films and solutions. The effect of added dimethylterph-thalate as a quencher to the fluorescence emission of the polymers used in this work were studied.(5 tabs., 39 figs., 60 refs.)

  9. Mixed fuel strategy for carbon deposition mitigation in solid oxide fuel cells at intermediate temperatures.

    Su, Chao; Chen, Yubo; Wang, Wei; Ran, Ran; Shao, Zongping; Diniz da Costa, João C; Liu, Shaomin

    2014-06-17

    In this study, we propose and experimentally verified that methane and formic acid mixed fuel can be employed to sustain solid oxide fuel cells (SOFCs) to deliver high power outputs at intermediate temperatures and simultaneously reduce the coke formation over the anode catalyst. In this SOFC system, methane itself was one part of the fuel, but it also played as the carrier gas to deliver the formic acid to reach the anode chamber. On the other hand, the products from the thermal decomposition of formic acid helped to reduce the carbon deposition from methane cracking. In order to clarify the reaction pathways for carbon formation and elimination occurring in the anode chamber during the SOFC operation, O2-TPO and SEM analysis were carried out together with the theoretical calculation. Electrochemical tests demonstrated that stable and high power output at an intermediate temperature range was well-maintained with a peak power density of 1061 mW cm(-2) at 750 °C. With the synergic functions provided by the mixed fuel, the SOFC was running for 3 days without any sign of cell performance decay. In sharp contrast, fuelled by pure methane and tested at similar conditions, the SOFC immediately failed after running for only 30 min due to significant carbon deposition. This work opens a new way for SOFC to conquer the annoying problem of carbon deposition just by properly selecting the fuel components to realize their synergic effects.

  10. Hydrogen storage in TiCr1.2(FeV)x BCC solid solutions

    Santos, Sydney F.; Huot, Jacques

    2009-01-01

    The Ti-V-based BCC solid solutions have been considered attractive candidates for hydrogen storage due to their relatively large hydrogen absorbing capacities near room temperature. In spite of this, improvements of some issues should be achieved to allow the technological applications of these alloys. Higher reversible hydrogen storage capacity, decreasing the hysteresis of PCI curves, and decrease in the cost of the raw materials are needed. In the case of vanadium-rich BCC solid solutions, which usually have large hydrogen storage capacities, the search for raw materials with lower cost is mandatory since pure vanadium is quite expensive. Recently, the substitutions of vanadium in these alloys have been tried and some interesting results were achieved by replacing vanadium by commercial ferrovanadium (FeV) alloy. In the present work, this approach was also adopted and TiCr 1.2 (FeV) x alloy series was investigated. The XRD patterns showed the co-existence of a BCC solid solution and a C14 Laves phase in these alloys. SEM analysis showed the alloys consisted of dendritic microstructure and C14 colonies. The amount of C14 phase increases when the amount of (FeV) decreases in these alloys. Concerning the hydrogen storage, the best results were obtained for the TiCr 1.2 (FeV) 0.4 alloy, which achieved 2.79 mass% of hydrogen storage capacity and 1.36 mass% of reversible hydrogen storage capacity

  11. Vaporization study on vanadium-oxygen solid solution by mass spectrometric method

    Banchorndhevakul, W.; Matsui, Tsuneo; Naito, Keiji

    1986-01-01

    The vapor pressures over vanadium-oxygen solid solution (0.001 ≤ O/V ≤ 0.145) were measured by mass-spectrometric method in the temperature range of 1,855 ∼ 2,117 K. The main vapor species were observed to be V(g) and VO(g). The vapor pressure of V(g) is higher than that of VO(g) over the solid solutions with all O/V ratios except for O/V = 0.145. The vapor pressure of V(g) is nearly independent of O/V ratio. The vapor pressure of VO(g) decreases with decreasing O/V ratio. The oxygen partial pressure was calculated as a function of temperature and O/V ratio from the vapor pressures of V(g) and VO(g), from which the partial molar enthalpy and entropy of oxygen in the solid solution were determined. The partial molar enthalpy of oxygen was observed to be independent of composition, suggesting the presence of very weak interaction between interstitial oxygens. The compositional dependence of the partial molar entropy of oxygen can be explained by assuming the occupation of the octahedral site in bcc vanadium lattice by the interstitial oxygens. The excess partial molar entropy of oxygen was compared with the value derived from the sum of the contributions from the volume expansion, electronic heat capacity and vibrational terms. (author)

  12. CSBB-ConeExclusion, adapting structure based solution virtual screening to libraries on solid support.

    Shave, Steven; Auer, Manfred

    2013-12-23

    Combinatorial chemical libraries produced on solid support offer fast and cost-effective access to a large number of unique compounds. If such libraries are screened directly on-bead, the speed at which chemical space can be explored by chemists is much greater than that addressable using solution based synthesis and screening methods. Solution based screening has a large supporting body of software such as structure-based virtual screening tools which enable the prediction of protein-ligand complexes. Use of these techniques to predict the protein bound complexes of compounds synthesized on solid support neglects to take into account the conjugation site on the small molecule ligand. This may invalidate predicted binding modes, the linker may be clashing with protein atoms. We present CSBB-ConeExclusion, a methodology and computer program which provides a measure of the applicability of solution dockings to solid support. Output is given in the form of statistics for each docking pose, a unique 2D visualization method which can be used to determine applicability at a glance, and automatically generated PyMol scripts allowing visualization of protein atom incursion into a defined exclusion volume. CSBB-ConeExclusion is then exemplarically used to determine the optimum attachment point for a purine library targeting cyclin-dependent kinase 2 CDK2.

  13. Studies on thermal expansion and XPS of urania-thoria solid solutions

    Anthonysamy, S.; Panneerselvam, G.; Bera, Santanu; Narasimhan, S.V.; Vasudeva Rao, P.R.

    2000-01-01

    The thermal expansion characteristics of polycrystalline (U y Th 1-y )O 2 solid solutions with y=0.13, 0.55 and 0.91 were determined in the temperature range from 298 to 1973 K by means of X-ray diffraction technique. For these temperatures, the average linear thermal expansion coefficients for (U 0.13 Th 0.87 )O 2 , (U 0.55 Th 0.45 )O 2 and (U 0.91 Th 0.09 )O 2 are 1.033x10 -5 , 1.083x10 -5 and 1.145x10 -5 K -1 , respectively. The measured thermal expansion values were compared with those calculated by applying the equations for linear thermal expansion of pure urania and thoria. It was shown that the stoichiometric (U, Th)O 2 solid solutions are almost ideal at least up to 2000 K. The binding energies of U 4f 7/2 and Th 4f 7/2 electrons of (U 0.1 Th 0.9 )O 2 , (U 0.25 Th 0.75 )O 2 , (U 0.50 Th 0.50 )O 2 , (U 0.75 Th 0.25 )O 2 and (U 0.90 Th 0.10 )O 2 were experimentally determined by X-ray photoelectron spectroscopy. The result showed the presence of only U 4+ and Th 4+ chemical states in the stoichiometric urania-thoria solid solutions

  14. Morphology, composition, and mixing state of primary particles from combustion sources ? crop residue, wood, and solid waste

    Liu, Lei; Kong, Shaofei; Zhang, Yinxiao; Wang, Yuanyuan; Xu, Liang; Yan, Qin; Lingaswamy, A. P.; Shi, Zongbo; Lv, Senlin; Niu, Hongya; Shao, Longyi; Hu, Min; Zhang, Daizhou; Chen, Jianmin; Zhang, Xiaoye

    2017-01-01

    Morphology, composition, and mixing state of individual particles emitted from crop residue, wood, and solid waste combustion in a residential stove were analyzed using transmission electron microscopy (TEM). Our study showed that particles from crop residue and apple wood combustion were mainly organic matter (OM) in smoldering phase, whereas soot-OM internally mixed with K in flaming phase. Wild grass combustion in flaming phase released some Cl-rich-OM/soot particles and cardboard combusti...

  15. Solid solutions of hydrogen uranyl phosphate and hydrogen uranyl arsenate. A family of luminescent, lamellar hosts

    Dorhout, P.K.; Rosenthal, G.L.; Ellis, A.B.

    1988-01-01

    Hydrogen uranyl phosphate, HUO 2 PO 4 x 4H 2 O (HUP), and hydrogen uranyl arsenate, HUO 2 AsO 4 x 4H 2 O (HUAs), form solid solutions of composition HUO 2 (PO 4 ) 1-x (AsO 4 )x (HUPAs), representing a family of lamellar, luminescent solids that can serve as hosts for intercalation chemistry. The solids are prepared by aqueous precipitation reactions from uranyl nitrate and mixtures of phosphoric and arsenic acids; thermogravimetric analysis indicates that the phases are tetrahydrates, like HUP and HUAs. Powder x-ray diffraction data reveal the HUPAs solids to be single phases whose lattice constants increase with X, in rough accord with Vegard's law Spectral shifts observed for the HUPAs samples. Emission from the solids is efficient (quantum yields of ∼ 0.2) and long-lived (lifetimes of ∼ 150 μs), although the measured values are uniformly smaller than those of HUP and HUAs; unimolecular radiative and nonradiative rate constants for excited-state decay of ∼ 1500 and 5000 s -1 , respectively, have been calculated for the compounds. 18 refs., 5 figs., 2 tabs

  16. Mixed field radiation effects on dry and acidic solution saturated polyamide 6,6

    Brown, L. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ont., K7K 7B4 (Canada); Bonin, H.W. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ont., K7K 7B4 (Canada)]. E-mail: bonin-h@rmc.ca; Bui, V.T. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ont., K7K 7B4 (Canada)

    2005-05-15

    The disposal of Canada's radioactive waste materials has been the focus of ongoing research at the Royal Military College of Canada, in the use of polymer-based composite materials for the fabrication of disposal containers. An evaluation of the performance of polyamide 6,6 after exposure to radiation and acidic aqueous solutions provides the basis for the assessment of the lifetime performance of a polymeric-based storage container. This work demonstrates the importance of the combined effects of aqueous solution diffusion and radiation exposure on the mechanical performance and molecular structure of polyamide 6,6. Irradiation of dry samples initially results in a marked reduction of mechanical performance, however, post-irradiation aging allows for the return to pre-irradiation mechanical strength. Samples irradiated after exposure to either distilled water or 0.1 M sulfuric acid solutions exhibited increases in mechanical performance upon exposure to a mixed field radioactive environment.

  17. Mixed field radiation effects on dry and acidic solution saturated polyamide 6,6

    Brown, L.; Bonin, H.W.; Bui, V.T.

    2005-01-01

    The disposal of Canada's radioactive waste materials has been the focus of ongoing research at the Royal Military College of Canada, in the use of polymer-based composite materials for the fabrication of disposal containers. An evaluation of the performance of polyamide 6,6 after exposure to radiation and acidic aqueous solutions provides the basis for the assessment of the lifetime performance of a polymeric-based storage container. This work demonstrates the importance of the combined effects of aqueous solution diffusion and radiation exposure on the mechanical performance and molecular structure of polyamide 6,6. Irradiation of dry samples initially results in a marked reduction of mechanical performance, however, post-irradiation aging allows for the return to pre-irradiation mechanical strength. Samples irradiated after exposure to either distilled water or 0.1 M sulfuric acid solutions exhibited increases in mechanical performance upon exposure to a mixed field radioactive environment

  18. Solution of the Fokker-Planck equation with a logarithmic potential and mixed eigenvalue spectrum

    Guarnieri, F.; Moon, W.; Wettlaufer, J. S.

    2017-09-01

    Motivated by a problem in climate dynamics, we investigate the solution of a Bessel-like process with a negative constant drift, described by a Fokker-Planck equation with a potential V (x ) =-[b ln(x ) +a x ] , for b >0 and a finance. The Bessel-like process we consider can be solved by seeking solutions through an expansion into a complete set of eigenfunctions. The associated imaginary-time Schrödinger equation exhibits a mix of discrete and continuous eigenvalue spectra, corresponding to the quantum Coulomb potential describing the bound states of the hydrogen atom. We present a technique to evaluate the normalization factor of the continuous spectrum of eigenfunctions that relies solely upon their asymptotic behavior. We demonstrate the technique by solving the Brownian motion problem and the Bessel process both with a constant negative drift. We conclude with a comparison to other analytical methods and with numerical solutions.

  19. Study of the sintering process and the formation of a (Th, U) O2 solid solution

    Tomasi, Roberto

    1979-01-01

    The effect of some variables in the (Th, U) O 2 sintering process and solid solution formation was studied. ThO 2 , U 3 O 8 and UO 2 powder were prepared. The ThO 2 powders were obtained by calcination of thorium at 500 and 750 deg C; the U 3 O 8 powders were derived from the calcination of ADU at 660 and 750 deg C; the UO 2 powder were prepared from ADU and from ATCU. The different characteristics of these materials were determined by measurements of surface area, by scanning electron microscopy, tap density tests, X-ray diffractometry and by measurements of the O/U ratios. The oxide mixtures were chosen in order to produce a final composition with 10 w/o of UO 2 . A mixture of thorium oxalate and ADU was also prepared by calcining these salts in air at 700 deg C, in order to obtain certain amount of solid solution prior to sintering. The sintering operations were developed in an argon atmosphere at temperatures between 1400 and 1700 deg C, during interval varying from 1 to 4 hours. The effect of the mixture characteristics on the sintering process and solid solution formation were studied considering the results of densification, microstructure development and X-ray diffractometry. The ThO 2 powder characteristics have a main effect on the mixtures compactability and sinterability, the higher calcining temperatures increasing the green density, but decreasing the final density of the sintered pellets. In the sintering of mixtures containing U 3 O 3 , this oxide is reduced to UO 2 and it is possible to obtain pellets with density and microstructures similar to those produced from mixtures containing UO 2 . But if oxygen in excess is present during sintering, the process is affected, occurring exaggerated grain growth. The densification results were related to the Coble's kinetics equation for second stage of sintering, valid for bulk diffusion, grain boundary acting as vacancy sinks. The sintering activation energy is independent from the powder starting

  20. Transport properties of dilute α -Fe (X ) solid solutions (X = C, N, O)

    Schuler, Thomas; Nastar, Maylise

    2016-06-01

    We extend the self-consistent mean field (SCMF) method to the calculation of the Onsager matrix of Fe-based interstitial solid solutions. Both interstitial jumps and substitutional atom-vacancy exchanges are accounted for. A general procedure is introduced to split the Onsager matrix of a dilute solid solution into intrinsic cluster Onsager matrices, and extract from them flux-coupling ratios, mobilities, and association-dissociation rates for each cluster. The formalism is applied to vacancy-interstitial solute pairs in α -Fe (V X pairs, X = C, N, O), with ab initio based thermodynamic and kinetic parameters. Convergence of the cluster mobility contribution gives a controlled estimation of the cluster definition distance, taking into account both its thermodynamic and kinetic properties. Then, the flux-coupling behavior of each V X pair is discussed, and qualitative understanding is achieved from the comparison between various contributions to the Onsager matrix. Also, the effect of low-activation energy second-nearest-neighbor interstitial solute jumps around a vacancy on these results is addressed.

  1. Formation of solid solutions of gallium in Fe–Cr and Fe–Co alloys: Mössbauer studies and first-principles calculations

    Serikov, V.V. [Institute of Metal Physics UB RAS, S. Kovalevskaya str. 18, 620990 Ekaterinburg (Russian Federation); Kleinerman, N.M., E-mail: kleinerman@imp.uran.ru [Institute of Metal Physics UB RAS, S. Kovalevskaya str. 18, 620990 Ekaterinburg (Russian Federation); Vershinin, A.V.; Mushnikov, N.V.; Protasov, A.V.; Stashkova, L.A. [Institute of Metal Physics UB RAS, S. Kovalevskaya str. 18, 620990 Ekaterinburg (Russian Federation); Gorbatov, O.I. [Institute of Metal Physics UB RAS, S. Kovalevskaya str. 18, 620990 Ekaterinburg (Russian Federation); Department of Materials Science and Engineering, KTH Royal Institute of Technology, SE - 100 44 Stockholm (Sweden); Ruban, A.V. [Department of Materials Science and Engineering, KTH Royal Institute of Technology, SE - 100 44 Stockholm (Sweden); Gornostyrev, Yu.N. [Institute of Metal Physics UB RAS, S. Kovalevskaya str. 18, 620990 Ekaterinburg (Russian Federation)

    2014-11-25

    Highlights: • Structure features of the formation of quasibinary solid solutions Fe–Co–Ga and Fe–Cr–Ga are found. • The first-principles calculation of mixing and solubility energies for Ga in an Fe–X alloy are given. • Ga handicaps the processes of phase separation in the Fe–Cr system and ordering in the Fe–Co system. • Preference of Ga entering in the neighborhood of a second element can help study multielement alloys. - Abstract: Investigation of Ga influence on the structure of Fe–Cr and Fe–Co alloys was performed with the use of Mössbauer spectroscopy and X-ray diffraction methods. The experimental results are compared with results of first-principles calculations of the mixing and solubility energies for Ga in an Fe–X (X = Co, Cr) alloy both in ferromagnetic and paramagnetic states. It is shown that Ga mainly goes into the solid solutions of the base alloys. In the alloys of the Fe–Cr system, doping with Ga handicaps the decomposition of solid solutions, observed in the binary alloys, and increases its stability. In the alloys with Co, Ga also favors the uniformity of solid solutions. The results of the first-principles calculations testify in favor of a preferable dissolution of Ga in the FeCo regions of a multicomponent structure rather than FeCr regions, both types of regions being in the ferromagnetic state at the temperature of annealing. The analysis of Mössbauer experiments gives some grounds to conclude that if, owing to liquation, clusterization, or initial stages of phase separation, there exist regions enriched in iron, some amount of Ga atoms prefer to enter the nearest surroundings of iron atoms, thus forming binary Fe–Ga regions (or phases)

  2. [Mechanism of gold solid extraction from aurocyanide solution using D3520 resin impregnated with TRPO].

    Yang, Xiang-Jun; Wang, Shi-Xiong; Zou, An-Qin; Chen, Jing; Guo, Hong

    2014-02-01

    Trialkyphosphine oxides (TRPO) was successfully used for the impregnation of D3520 resin to prepare an extractant-impregnated resin (EIR). Solid extraction of Au(I) from alkaline cyanide solution was studied using this extractant-impregnated resin (EIR), with addition of cetyltrimethylammonium bromide (CTMAB), directly into the aurous aqueous phase in advance. The mechanism of solid extraction was further investigated by means of FTIR, XPS and SEM. The column separation studies have shown that cationic surfactant CTMAB played a key role in the solid phase extraction, and the resin containing TRPO were effective for the extraction of gold when the molar ratio of CTMAB: Au( I ) reached 1:1. FTIR spectroscopy of gold loaded EIR showed that the frequency of C[triple bond]N stretching vibration was at 2144 cm(-1), and the frequency of P=O stretching vibration shifted to lower frequency from 1153 to 1150 cm(-1). The XPS spectrum of N(1s), Au(4f7/2) and Au(4f5/2) sugges- ted that the coordination environment of gold did not change before and after extraction, and gold was still as the form of Au (CN)2(-) anion exiting in the loaded resin; O(1s) spectrum showed that the chemically combined water significantly increased after solid extraction from 30.74% to 42.34%; Comparing to the P(2p) spectrum before and after extraction, the binding energy increased from 132. 15 to 132. 45 eV, indicating there maybe existing hydrogen-bond interaction between P=O and water molecule, such as P=O...H-O-H. The above results obtained established that in the solid extraction process, the hydrophobic ion association [CTMA+ x Au(CN)] diffused from the bulk solution into the pores of the EIR, and then be solvated by TRPO adsorbed in the pores through hydrogen bonding bridged by the water molecules.

  3. Decay property of regularity-loss type for solutions in elastic solids with voids

    Djouamai, Leila; Said-Houari, Belkacem

    2014-01-01

    In this paper, we consider the Cauchy problem for a system of elastic solids with voids. First, we show that a linear porous dissipation leads to decay rates of regularity-loss type of the solution. We show some decay estimates for initial data in Hs(R)∩L1(R). Furthermore, we prove that by restricting the initial data to be in Hs(R)∩L1,γ(R) and γ. ∈. [0, 1], we can derive faster decay estimates of the solution. Second, we show that by adding a viscoelastic damping term, then we gain the regularity of the solution and obtain the optimal decay rate. © 2013 Elsevier Ltd.

  4. Large-scale fluctuations in the diffusive decomposition of solid solutions

    Karpov, V.G.; Grimsditch, M.

    1995-01-01

    The concept of an instability in the classic Ostwald ripening theory with respect to compositional fluctuations is suggested. We show that small statistical fluctuations in the precipitate phase lead to gigantic Coulomb-like fluctuations in the solute concentration which in turn affect the ripening. As a result large-scale fluctuations in both the precipitate and solute concentrations appear. These fluctuations are characterized by amplitudes of the order of the average values of the corresponding quantities and by a space scale L∼(na) -1/2 which is considerably greater than both the average nuclear radius and internuclear distance. The Lifshitz-Slyozov theory of ripening is shown to remain locally applicable, over length scales much less than L. The implications of these findings for elastic light scattering in solid solutions that have undergone Ostwald ripening are considered

  5. Large-scale fluctuations in the diffusive decomposition of solid solutions

    Karpov, V. G.; Grimsditch, M.

    1995-04-01

    The concept of an instability in the classic Ostwald ripening theory with respect to compositional fluctuations is suggested. We show that small statistical fluctuations in the precipitate phase lead to gigantic Coulomb-like fluctuations in the solute concentration which in turn affect the ripening. As a result large-scale fluctuations in both the precipitate and solute concentrations appear. These fluctuations are characterized by amplitudes of the order of the average values of the corresponding quantities and by a space scale L~(na)-1/2 which is considerably greater than both the average nuclear radius and internuclear distance. The Lifshitz-Slyozov theory of ripening is shown to remain locally applicable, over length scales much less than L. The implications of these findings for elastic light scattering in solid solutions that have undergone Ostwald ripening are considered.

  6. Equilibrium of adsorption of mixed milk protein/surfactant solutions at the water/air interface.

    Kotsmar, C; Grigoriev, D O; Xu, F; Aksenenko, E V; Fainerman, V B; Leser, M E; Miller, R

    2008-12-16

    Ellipsometry and surface profile analysis tensiometry were used to study and compare the adsorption behavior of beta-lactoglobulin (BLG)/C10DMPO, beta-casein (BCS)/C10DMPO and BCS/C12DMPO mixtures at the air/solution interface. The adsorption from protein/surfactant mixed solutions is of competitive nature. The obtained adsorption isotherms suggest a gradual replacement of the protein molecules at the interface with increasing surfactant concentration for all studied mixed systems. The thickness, refractive index, and the adsorbed amount of the respective adsorption layers, determined by ellipsometry, decrease monotonically and reach values close to those for a surface covered only by surfactant molecules, indicating the absence of proteins from a certain surfactant concentration on. These results correlate with the surface tension data. A continuous increase of adsorption layer thickness was observed up to this concentration, caused by the desorption of segments of the protein and transforming the thin surface layer into a rather diffuse and thick one. Replacement and structural changes of the protein molecules are discussed in terms of protein structure and surface activity of surfactant molecules. Theoretical models derived recently were used for the quantitative description of the equilibrium state of the mixed surface layers.

  7. Influence of hydrostatic pressure on BCC-lattice parameter in molybdenum, niobium and vanadium with rhenium solid solutions

    Smol'yaninova, Eh.A.; Stribuk, E.K.; Tyavlovskij, V.I.

    1987-01-01

    Data on the effect of 1.8GPa hydrostatic pressure on bcc lattice parameters of solid solutions in Mo-Re, Nb-Re, V-re systems are presented. It is shown that after the application hydrostatic pressure a decrease in bcc lattice parameter is observed and the greatest change in the lattice parameter takes place in bcc of solid solutions in the Nb-Re system (DELTA A ∼ 0.0035 nm). Analysis of the experimental data obtained on the basis of calculations made for packing density change in the above-mentioned solid solutions under the pressure is carried out

  8. Substrate aggregation due to aerial hyphae during discontinuously mixed solid-state fermentation with Aspergillus oryzae: Experiments and modeling

    Schutyser, M.A.I.; Schutyser, M.A.I.; de Pagter, P.; Weber, F.J.; Briels, Willem J.; Boom, R.M.; Boom, R.M.; Rinzema, A.

    2003-01-01

    Solid-state fermentation (SSF) is prone to process failure due to channeling caused by evaporative cooling and the formation of an interparticle mycelium network. Mixing is needed to break the mycelium network and to avoid such failure. This study presents the first attempt to quantify and predict

  9. Substrate aggregation due to aerial hyphae during discontinously mixed solid-state fermentation with aspergillus oryzae: experiments and modeling

    Schutyser, M.A.I.; Pagter, de P.; Weber, F.J.; Briels, W.J.; Boom, R.M.; Rinzema, A.

    2003-01-01

    Solid-state fermentation (SSF) is prone to process failure due to channeling caused by evaporative cooling and the formation of an interparticle mycelium network. Mixing is needed to break the mycelium network and to avoid such failure. This study presents the first attempt to quantify and predict

  10. Solubility behaviour of antimony(III) and antimony(V) solids in basic aqueous solutions at 300{sup o}C

    Lemire, R.J.; Tosello, N.B.; Halliday, J.D

    1999-12-01

    The major contributions of the isotopes {sup 122}Sb and {sup 124}Sb to activity transport in a CANDU reactor primary heat transport system (HTS), have been associated with oxygen ingress during reactor shutdown. As part of a program to minimize the release and redeposition of these isotopes, the solubilities of antimony(III) and (V) oxides and salts have been measured in basic solutions at temperatures from 25 to 300{sup o}C. The results provide information on the charge and the stability as a function of temperature of antimony solution species and, hence, a guide to the trends in the temperature dependence of the solubilities of antimony solids. In solutions in which oxidation of antimony(III) to antimony(V) is minimized, the solubility of Sb{sub 2}O{sub 3} increases by about two orders of magnitude between 25 and 200{sup o}C, and then levels out or decreases slightly. At 250{sup o}C, in oxidizing solutions, Sb{sub 2}O{sub 5}{center_dot}xH{sub 2}O and simple sodium antimonate(V) were found to be unstable in sodium hydroxide solutions with respect to the solid, Na{sub 2{alpha}}[H(H{sub 2}O)]{sub 2-2{alpha}}Sb{sub 2}O{sub 6}, which has a pyrochlore structure. The solubility of this partially protonated sodium antimonate increases from 25 to 200{sup o}C and decreases at temperatures above 250{sup o}C. These solubility changes for the antimony (V) solids reflect changes in the stability of the anionic antimony solution species (SbO{sub 3}{sup -} or Sb(OH){sub 6}{sup -}), even though the compositions of antimony-containing solids in basic oxidizing solutions are strongly dependent on the cations and their aqueous phase concentrations. All solids used in the present experiments would be expected to generate total solution antimony concentrations {>=} 0.00005 mol{center_dot}dm{sup -3} in any neutral or basic aqueous solutions (assuming no added sodium salts). Therefore, under HTS conditions, precipitation of any antimony oxides or mixed oxides is unlikely. It cannot be

  11. Effects of minor Si on microstructures and room temperature fracture toughness of niobium solid solution alloys

    Kong, Bin, E-mail: kongbin@buaa.edu.cn; Jia, Lina, E-mail: jialina@buaa.edu.cn; Su, Linfen, E-mail: sulinfen@mse.buaa.edu.cn; Guan, Kai, E-mail: guankai@mse.buaa.edu.cn; Weng, Junfei, E-mail: wengjf@mse.buaa.edu.cn; Zhang, Hu, E-mail: zhanghu@buaa.edu.cn

    2015-07-15

    Controlling the elements content in the niobium solid solution (Nb{sub SS}) is significant for the better comprehensive performance of Nb-silicide-based alloys. In this paper, the effects of minor Si on the microstructures and room temperature fracture toughness of Nb–(0/0.5/1/2)Si–27.63Ti–12.92Cr–2.07Al–1.12Hf (at%, unless stated otherwise) solid solution alloys were investigated. The alloys were processed by vacuum arc-casting (AC), and then heat treated (HT) at 1425 °C for 10 h. In HT alloys, Nb{sub SS} grains are refined gradually with the increase of Si content. Meanwhile, the volume fraction of Cr{sub 2}Nb and silicides phases precipitates increases. The fracture toughness of HT alloys decreases at first but then increases in the range of 0 to 2% Si, because it is a combinatorial process of positive and negative effects caused by the addition of Si. The refinement of Nb{sub SS} grains displays positive effect on fracture toughness, while the increase of solid solubility of Si in Nb{sub SS} and brittle Cr{sub 2}Nb and Nb-silicides precipitate phases display negative effect.

  12. Nanostructured sodium lithium niobate and lithium niobium tantalate solid solutions obtained by controlled crystallization of glass

    Radonjic, L.; Todorovic, M.; Miladinovic, J.

    2005-01-01

    Transparent, nanostructured glass ceramics based on ferroelectric solid solutions of the type Na 1-x Li x NbO 3 (in very narrow composition regions for x = 0.12 and 0.93) and LiNb 1-y Ta y O 3 (y = 0.5 unlimited solid solubility), can be obtained by controlled crystallization of glass. The parent glass samples were prepared by conventional melt-quenching technique. Heat-treatment of the parent glasses was performed at the various temperatures, for the same time. The glass structure evolution during the controlled crystallization was examined by FT-IR spectroscopy analysis. Crystalline phases were identified by X-ray diffraction analysis and SEM was used for microstructure characterization. Densities of the crystallized glasses were measured by Archimedean principle. The capacitance and dielectric loss tangent were measured at a frequency of 1 kHz, at the room temperature. It was found that in the all investigated systems crystallize solid solutions Na 1-x Li x NbO 3 and LiNb 1-y Ta y O 3 in the glassy matrix, have crystal size on nanoscale (less than 100 nm), which is one of requirements to get a transparent glass ceramic that could be a good ferroelectric material regarding to the measured properties

  13. Excess Gibbs energy for six binary solid solutions of molecularly simple substances

    Lobo, L J; Staveley, L A.K.

    1985-01-01

    In this paper we apply the method developed in a previous study of Ar + CH/sub 4/ to the evaluation of the excess Gibbs energy G /SUP E.S/ for solid solutions of two molecularly simple components. The method depends on combining information on the excess Gibbs energy G /SUP E.L/ for the liquid mixture of the two components with a knowledge of the (T, x) solid-liquid phase diagram. Certain thermal properties o the pure substances are also needed. G /SUP E.S/ has been calculated for binary mixtures of Ar + Kr, Kr + CH/sub 4/, CO + N/sub 2/, Kr + Xe, Ar + N/sub 2/, and Ar + CO. In general, but not always, the solid mixtures are more non-ideal than the liquid mixtures of the same composition at the same temperature. Except for the Kr + CH/sub 4/ system, the ratio r = G /SUP E.S/ /G /SUP E.L/ is larger the richer the solution in the component with the smaller molecules.

  14. B-site substituted solid solutions on the base of sodium-bismuth titanate

    V. M. Ishchuk

    2016-12-01

    Full Text Available The paper presents results of studies of the formation of phases during the solid-state synthesis in the [(Na0.5Bi0.50.80Ba0.20](Ti1–yByO3 system of solid solutions with B-site substitutions. The substitutions by zirconium, tin and ion complexes (In0.5Nb0.5 and (Fe0.5Nb0.5 have been studied. It has been found that the synthesis is a multi-step process associated with the formation of a number of intermediate phases (depending on the compositions and calcination temperatures. Single-phase solid solutions have been produced at the calcination temperatures in the interval 1000–1100∘C. An increase in the substituting ions concentration leads to a linear increase of the crystal cell size. At the same time, the tolerance factor gets reduced boosting the stability of the antiferroelectric phase as compared to that of the ferroelectric phase.

  15. Entropy of adsorption of mixed surfactants from solutions onto the air/water interface

    Chen, L.-W.; Chen, J.-H.; Zhou, N.-F.

    1995-01-01

    The partial molar entropy change for mixed surfactant molecules adsorbed from solution at the air/water interface has been investigated by surface thermodynamics based upon the experimental surface tension isotherms at various temperatures. Results for different surfactant mixtures of sodium dodecyl sulfate and sodium tetradecyl sulfate, decylpyridinium chloride and sodium alkylsulfonates have shown that the partial molar entropy changes for adsorption of the mixed surfactants were generally negative and decreased with increasing adsorption to a minimum near the maximum adsorption and then increased abruptly. The entropy decrease can be explained by the adsorption-orientation of surfactant molecules in the adsorbed monolayer and the abrupt entropy increase at the maximum adsorption is possible due to the strong repulsion between the adsorbed molecules.

  16. Synthesis, characterization and thermal expansion studies on ThO2-SmO1.5 solid solutions

    Panneerselvam, G.; Antony, M.P.

    2008-01-01

    Full text: A highly homogeneous Th 1-x Sm x O 2 ; 0 ≤ x ≤ 0.8 solid solutions were synthesized by co-precipitation technique and the co-precipitated samples were sintered at 1473 K. Compositions of the solid solutions were characterized by standard wet-chemical analysis. X-ray diffraction measurements were performed in the sintered pellets for structural analysis, lattice parameter calculation and determination of solid solubility of SmO 1.5 in ThO 2 matrix. Bulk and theoretical densities of solid solutions were also determined. A fluorite structure was observed for ThO 2 -SmO 1.5 solid solutions with 0-55.2 mol % SmO 1.5 . Their thermal expansion coefficients were measured using high temperature X-ray diffraction technique. The mean linear thermal expansivity, αm for ThO 2 -SmO 1.5 solid solutions containing 17.9, 41.7 and 52.0 mole percent of SmO 1.5 were determined in the temperature range 298 to 2000 K for the first time. The mean linear thermal expansion coefficients for ThO 2 -SmO 1.5 solid solutions are 10.47x10 -6 K -1 , 11.16x10 -6 K -1 and 11.45x10 -6 K -1 , respectively. The percentage linear thermal expansion in this temperature range, for ThO 2 -SmO 1.5 solid solutions containing 17.9, 41.7 and 52.0 mol % SmO 1.5 are 1.82,1.94 and 1.99 respectively. It is suggested that the solid solutions are stable up to 2000 K. It is also suggested that the effect and nature of the dopant are the important parameters influenced in the thermal expansion of the ThO 2

  17. Structural analysis and magnetic properties of solid solutions of Co–Cr system obtained by mechanical alloying

    Betancourt-Cantera, J.A. [Área Académica de Ciencias de la Tierra y Materiales, UAEH Carr., Pachuca-Tulancingo Km. 4.5, Pachuca, Hidalgo 42184 (Mexico); Sánchez-De Jesús, F., E-mail: fsanchez@uaeh.edu.mx [Área Académica de Ciencias de la Tierra y Materiales, UAEH Carr., Pachuca-Tulancingo Km. 4.5, Pachuca, Hidalgo 42184 (Mexico); Bolarín-Miró, A.M. [Área Académica de Ciencias de la Tierra y Materiales, UAEH Carr., Pachuca-Tulancingo Km. 4.5, Pachuca, Hidalgo 42184 (Mexico); Betancourt, I.; Torres-Villaseñor, G. [Departamento de Materiales Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México D.F. 04510 (Mexico)

    2014-03-15

    In this paper, a systematic study on the structural and magnetic properties of Co{sub 100−x}Cr{sub x} alloys (0mixed in an adequate weight ratio to obtain Co{sub 1−x}Cr{sub x} (0solid solutions based on Co-hcp, Co-fcc and Cr-bcc structures were obtained. The saturation polarization indicated a maximum value of 1.17 T (144 Am{sup 2}/kg) for the Co{sub 90}Cr{sub 10}, which decreases with the increasing of the Cr content up to x=80, as a consequence of the dilution effect of the magnetic moment which is caused by the Cr content and by the competition between ferromagnetic and antiferromagnetic exchange interactions. The coercivity increases up to 34 kA/m (435 Oe) for Co{sub 40}Cr{sub 60}. For Cr rich compositions, it is observed an important decrease reaching 21 kA/m (272 Oe) for Co{sub 10}Cr{sub 90,} it is related to the grain size and the structural change. Besides, the magnetic anisotropy constant was determined for each composition. Magnetic thermogravimetric analysis allowed to obtain Curie temperatures corresponding to the formation of hcp-Co(Cr) and fcc-Co(Cr) solid solutions. - Highlights: • Mechanical alloying (MA) induces the formation of solid solutions of Co–Cr system in non-equilibrium. • We report the crystal structure and the magnetic behavior of Co–Cr alloys produced by MA. • MA improves the magnetic properties of Co–Cr system.

  18. Dissolution of britholites and monazite / brabantite solid solutions doped with actinides; Etude de la dissolution de britholites et de solutions solides monazite / brabantite dopees avec des actinides

    Du Fou De Kerdaniel, E

    2007-12-15

    In the field of the radwaste storage in underground repository, several matrices were considered as promising ceramics for the specific immobilization of actinides. Two of them, britholites and monazite/ brabantite solid solution, have been considered during this work. In order to examine the dissolution mechanisms occurring at the solid liquid interface, several leaching experiments have been conducted on (Ln{sup III}PO{sub 4} ), brabantite (Ca{sup II}An{sup IV}(PO{sub 4}){sub 2}: An = Th, U) and britholites (Ca{sub 9}Nd{sub 0.5}An{sub 0.5}{sup IV} (PO{sub 4}){sub 4.5}(SiO{sub 4}){sub 1.5}F{sub 2}: An = Th, U). Some steady experiments, performed in under saturation conditions for various pH and temperature conditions allowed to evaluate the long term behaviour of such matrices through their chemical durability. On the contrary, the thermodynamic equilibria were examined through the leaching experiments performed near the saturation conditions. By the way, various secondary phases, precipitated onto the surface of altered samples have been identified and characterized. Among them, the (Nd, Ca, Th) - rhabdophane, novelly prepared in over- saturation experiments for a thorium weight loading lower than 11 % appeared to be metastable. Indeed, it turns into TPHPH (Th{sub 2}(PO{sub 4}){sub 2}HPO{sub 4}.H{sub 2}O) and Nd - rhabdophane (NdPO{sub 4}.1/2H{sub 2}O) when increasing leaching time. (author)

  19. An ordered metallic glass solid solution phase that grows from the melt like a crystal

    Chapman, Karena W.; Chupas, Peter J.; Long, Gabrielle G.; Bendersky, Leonid A.; Levine, Lyle E.; Mompiou, Frédéric; Stalick, Judith K.; Cahn, John W.

    2014-01-01

    We report structural studies of an Al–Fe–Si glassy solid that is a solid solution phase in the classical thermodynamic sense. We demonstrate that it is neither a frozen melt nor nanocrystalline. The glass has a well-defined solubility limit and rejects Al during formation from the melt. The pair distribution function of the glass reveals chemical ordering out to at least 12 Å that resembles the ordering within a stable crystalline intermetallic phase of neighboring composition. Under isothermal annealing at 305 °C the glass first rejects Al, then persists for approximately 1 h with no detectable change in structure, and finally is transformed by a first-order phase transition to a crystalline phase with a structure that is different from that within the glass. It is possible that this remarkable glass phase has a fully ordered atomic structure that nevertheless possesses no long-range translational symmetry and is isotropic

  20. Multivalent-Counterion-Induced Surfactant Multilayer Formation at Hydrophobic and Hydrophilic Solid-Solution Interfaces.

    Penfold, Jeffrey; Thomas, Robert K; Li, Peixun; Xu, Hui; Tucker, Ian M; Petkov, Jordan T; Sivia, Devinderjit S

    2015-06-23

    Surface multilayer formation from the anionic-nonionic surfactant mixture of sodium dodecyl dioxyethylene sulfate, SLES, and monododecyl dodecaethylene glycol, C12E12, by the addition of multivalent Al(3+) counterions at the solid-solution interface is observed and characterized by neutron reflectivity, NR. The ability to form surface multilayer structures on hydrophobic and hydrophilic silica and cellulose surfaces is demonstrated. The surface multilayer formation is more pronounced and more well developed on the hydrophilic and hydrophobic silica surfaces than on the hydrophilic and hydrophobic cellulose surfaces. The less well developed multilayer formation on the cellulose surfaces is attributed to the greater surface inhomogeneities of the cellulose surface which partially inhibit lateral coherence and growth of the multilayer domains at the surface. The surface multilayer formation is associated with extreme wetting properties and offers the potential for the manipulation of the solid surfaces for enhanced adsorption and control of the wetting behavior.

  1. Four Thermochromic o-Hydroxy Schiff Bases of α-Aminodiphenylmethane: Solution and Solid State Study

    Marija Zbačnik

    2017-01-01

    Full Text Available More than a hundred years after the first studies of the photo- and thermochromism of o-hydroxy Schiff bases (imines, it is still an intriguing topic that fascinates several research groups around the world. The reasons for such behavior are still under investigation, and this work is a part of it. We report the solution-based and mechanochemical synthesis of four o-hydroxy imines derived from α-aminodiphenylmethane. The thermochromic properties were studied for the single crystal and polycrystalline samples of the imines. The supramolecular impact on the keto-enol tautomerism in the solid state was studied using SCXRD and NMR, while NMR spectroscopy was used for the solution state. All four imines are thermochromic, although the color changes of the single crystals are not as strong as of the polycrystalline samples. One of the imines shows negative thermochromism, and that one is in keto-amine tautomeric form, both in the solid state as in solution.

  2. Effect of ionizing radiation on solid and water solution Penicillin G

    Ben Salem, I.; Amine, Kh.M.; Mabrouk, Y.; Saidi, M.; Mezni, M; Boulila, N; Hafez, E

    2015-01-01

    Penicillin G is a conventional antibiotic used for treatment of different kinds of infectious diseases. Due to its huge quantity production and resistance to biodegradability, this molecule has been a serious concern for clinicians and environmentalists. In this study, the effect of ionizing radiation on the penicillin G powder and in water solution was investigated. The Nuclear Magnetic Resonance (NMR) and fourier transform infrared spectroscopy (FTIR) analysis showed that the ionizing radiation at 50 kGy has no effect on the integrity of solid Penicillin G. The anti-microbial assays revealed that the activity of irradiated solid Penicillin G did not reduce and was stable after storage for one month. Ionizing radiation at 50 kGy led to degradation of water solution Penicillin G. The complete disappear of peaks observed in the control sample confirmed the broken of β-lactam ring, the decarboxylation and cleavage of the thiazolidine ring. The product issued from the irradiation of Penicillin G, was completely removed by the bacterium Cupriavidus.metallidurans. Thus, the ionizing irradiation followed by a biological treatment was very effective method for removing of Penicillin G antibiotics residuals from water solution.

  3. Supported liquid membrane based removal of lead(II) and cadmium(II) from mixed feed: Conversion to solid waste by precipitation

    Bhatluri, Kamal Kumar; Manna, Mriganka Sekhar; Ghoshal, Aloke Kumar; Saha, Prabirkumar, E-mail: p.saha@iitg.ac.in

    2015-12-15

    Highlights: • Simultaneous removal of two heavy metals lead and cadmium. • Conversion of liquid waste to solid precipitation. • Precipitation facilitates the metals transportation through LM. • Solidification of liquid waste minimizes the final removal of waste. - Abstract: Simultaneous removal of two heavy metals, lead(II) and cadmium(II), from mixed feed using supported liquid membrane (SLM) based technique is investigated in this work. The carrier-solvent combination of “sodium salt of Di-2-ethylhexylphosphoric acid (D2EHPA) (4% w/w) in environmentally benign coconut oil” was immobilized into the pores of solid polymeric polyvinylidene fluoride (PVDF) support. Sodium carbonate (Na{sub 2}CO{sub 3}) was used as the stripping agent. Carbonate salts of lead(II) and cadmium(II) were formed in the stripping side interface and they were insoluble in water leading to precipitation inside the stripping solution. The transportation of solute is positively affected due to the precipitation. Lead(II) removal was found to be preferential due to its favorable electronic configuration. The conversion of the liquid waste to the solid one was added advantage for the final removal of hazardous heavy metals.

  4. Solution of the atmospheric diffusion equation with a realistic diffusion coefficient and time dependent mixing height

    Mayhoub, A.B.; Etman, S.M.

    1997-01-01

    One dimensional model for the dispersion of a passive atmospheric contaminant (neglecting chemical reactions) in the atmospheric boundary layer is introduced. The differential equation representing the dispersion of pollutants is solved on the basis of gradient-transfer theory (K- theory). The present approach deals with a more appropriate and realistic profile for the diffusion coefficient K, which is expressed in terms of the friction velocity U, the vertical coordinate z and the depth of the mixing layer h, which is taken time dependent. After some mathematical simplification, the equation analytic obtained solution can be easily applied to case study concerning atmospheric dispersion of pollutants

  5. Approximate solutions for the two-dimensional integral transport equation. The critically mixed methods of resolution

    Sanchez, Richard.

    1980-11-01

    This work is divided into two part the first part (note CEA-N-2165) deals with the solution of complex two-dimensional transport problems, the second one treats the critically mixed methods of resolution. These methods are applied for one-dimensional geometries with highly anisotropic scattering. In order to simplify the set of integral equation provided by the integral transport equation, the integro-differential equation is used to obtain relations that allow to lower the number of integral equation to solve; a general mathematical and numerical study is presented [fr

  6. An overview of solution methods for multi-objective mixed integer linear programming programs

    Andersen, Kim Allan; Stidsen, Thomas Riis

    Multiple objective mixed integer linear programming (MOMIP) problems are notoriously hard to solve to optimality, i.e. finding the complete set of non-dominated solutions. We will give an overview of existing methods. Among those are interactive methods, the two phases method and enumeration...... methods. In particular we will discuss the existing branch and bound approaches for solving multiple objective integer programming problems. Despite the fact that branch and bound methods has been applied successfully to integer programming problems with one criterion only a few attempts has been made...

  7. Mixing Construction, Demolition and Excavation Waste and Solid Waste Compost for the Derivation of a Planting Medium for Use in the Rehabilitation of Quarries

    Assaf, Eleni

    2015-04-01

    Lebanon's very high population density has been increasing since the end of the civil war in the early 1990s reaching 416.36 people per square kilometer. Furthermore, the influx of refugees from conflicts in the region has increased the resident population significantly. All these are exerting pressure on the country's natural resources, pushing the Lebanese to convert more forest and agricultural land into roads, buildings and houses. This has led to a building boom and rapid urbanization which in turn has created a demand for construction material - mainly rock, gravel, sand, etc. nearly all of which are locally acquired through quarrying to the tune of three million cubic meters annually. This boom has been interrupted by a war with Israel in 2006 which resulted in thousands of tonnes of debris. The increase in population has also led to an increase in solid waste generation with 1.57 million tonnes of solid waste generated in Lebanon per year. The combination of construction, demolition and excavation (CDE) waste along with the increase in solid waste generation has put a major stress on the country and on the management of its solid waste. Compounding this problem are the issues of quarries closure and rehabilitation and a decrease in forest and vegetative cover. The on-going research reported in this paper aims to provide an integrated solution to the stated problem by developing a "soil mix" derived from a mélange of the organic matter of the solid waste (compost), the CDE waste, and soil. Excavation and construction debris were ground to several sizes and mixed with compost and soil at different ratios. Replicates of these mixes and a set of control (regular soil) were used. In this mix, native and indicator plants are planted (in pots) from which the most productive mix will be selected for further testing at field level in later experiments. The plant species used are Mathiolla crassifolia, a native Lebanese plant and Zea mays (Corn), which is commonly

  8. Formation of fine solid particles from aqueous solutions of sodium chloropalladate by gamma-ray irradiation

    Hatada, Motoyoshi; Fujita, Iwao; Korekawa, Kei-ichi.

    1994-10-01

    Studies have been carried out on the radiation chemical formation of palladium fine particles in argon saturated aqueous solutions of sodium chloropalladate without organic stabilizer. The solutions were irradiated with gamma-rays from a cobalt gamma-ray source and the irradiated solutions were subjected to the dynamic light scattering analysis for the particle diameter measurements, and to the UV-visible optical absorption spectroscopy for the measurements of turbidity (absorption at 700 nm) and remaining chloropalladate ion concentrations in the solution. In the solution of pH = 1.95 by HCl, the turbidity increased after the irradiation and then decreased with time. The concentration of remaining palladate ion in the solution decreased by the irradiation, but it gradually increased with time after the irradiation. These phenomena were qualitatively explained by the reaction scheme in that a precursor to the solid particles still exists in the solution after the irradiation was terminated, and that intermediates including the precursor reacted with chloride ion to re-form chloropalladate ions. The average diameter of the particles after the irradiation was ca. 20 nm and it increased with time to 40 nm at 2.75 kGy, and to 80 nm at 8.25 kGy absorption of radiation. The solution of pH = 0.65 by HCl was found to give lower yields of particles than those observed for the solution of pH = 1.95, and to give the particles of diameters about 150-200 nm. In the solution containing HClO 4 instead of HCl, palladium particles were also formed by the irradiation, whereas no backward reaction after the irradiation was observed due to the low concentration of chloride ion in the solution. The average diameter of the particles after the irradiation was about 300 nm and increased with time after the irradiation to a final values which was found to depend on pH of the solution and dose. (author)

  9. Comparing the Titrations of Mixed-Acid Solutions Using Dropwise and Constant-Flow Techniques

    Charlesworth, Paul; Seguin, Matthew J.; Chesney, David J.

    2003-11-01

    A mixed-acid solution containing hydrochloric and phosphoric acids was used to determine the error associated with performing a real-time titration. The results were compared against those obtained by performing the titration in a more traditional dropwise addition of titrant near the equivalence points. It was found that the real-time techniques resulted in significantly decreased analysis times while maintaining a low experimental error. The constant-flow techniques were implemented into two different levels of chemistry. It was found that students could successfully utilize the modified experiments. Problems associated with the techniques, major sources of error, and their solutions are discussed. In both cases, the use of the constant-flow setup has increased student recollection of key concepts, such as pKa determination, proper indicator choice, and recognizing the shape of specific titration curves by increasing student interest in the experiment.

  10. On mixed derivatives type high dimensional multi-term fractional partial differential equations approximate solutions

    Talib, Imran; Belgacem, Fethi Bin Muhammad; Asif, Naseer Ahmad; Khalil, Hammad

    2017-01-01

    In this research article, we derive and analyze an efficient spectral method based on the operational matrices of three dimensional orthogonal Jacobi polynomials to solve numerically the mixed partial derivatives type multi-terms high dimensions generalized class of fractional order partial differential equations. We transform the considered fractional order problem to an easily solvable algebraic equations with the aid of the operational matrices. Being easily solvable, the associated algebraic system leads to finding the solution of the problem. Some test problems are considered to confirm the accuracy and validity of the proposed numerical method. The convergence of the method is ensured by comparing our Matlab software simulations based obtained results with the exact solutions in the literature, yielding negligible errors. Moreover, comparative results discussed in the literature are extended and improved in this study.

  11. Coupling between magnetic and optical properties of stable Au-Fe solid solution nanoparticles

    De Julian Fernandez, C; Novak, R L; Bogani, L; Caneschi, A [INSTM RU at the Department of Chemistry of the University of Firenze, via della Lastruccia 3, 50019 Sesto Fiorentino (Italy); Mattei, G; Mazzoldi, P [Department of Physics, CNISM and University of Padova, via Marzolo 8, 35131 Padova (Italy); Paz, E; Palomares, F J [Instituto de Ciencia de Materiales de Madrid (CSIC), Cantoblanco, 28049 Madrid (Spain); Cavigli, L, E-mail: cesar.dejulian@unifi.it [Department of Physics-LENS, University of Florence, via Sansone 1, 50019 Sesto Fiorentino (Italy)

    2010-04-23

    Au-Fe nanoparticles constitute one of the simplest prototypes of a multifunctional nanomaterial that can exhibit both magnetic and optical (plasmonic) properties. This solid solution, not feasible in the bulk phase diagram in thermal equilibrium, can be formed as a nanostructure by out-of-equilibrium processes. Here, the novel magnetic, optical and magneto-optical properties of ion-implanted Au-Fe solid solution nanoparticles dispersed in a SiO{sub 2} matrix are investigated and correlated. The surface plasmon resonance of the Au-Fe nanoparticles with almost equicomposition is strongly damped when compared to pure Au and to Au-rich Au-Fe nanoparticles. In all cases, the Au atoms are magnetically polarized, as measured by x-ray magnetic circular dichroism, and ferromagnetically coupled with Fe atoms. Although the chemical stability of Au-Fe nanoparticles is larger than that of Fe nanoparticles, both the magnetic moment per Fe atom and the order temperature are smaller. These results suggest that electronic and magnetic properties are more influenced by the hybridization of the electronic bands in the Au-Fe solid solution than by size effects. On the other hand, the magneto-optical transitions allowed in the vis-nIR spectral regions are very similar. In addition, we also observe, after studying the properties of thermally treated samples, that the Au-Fe alloy is stabilized, not by surface effects, but by the combination of the out-of-equilibrium nature of the ion implantation technique and by changes in the properties due to size effects.

  12. Coupling between magnetic and optical properties of stable Au-Fe solid solution nanoparticles

    De Julian Fernandez, C; Novak, R L; Bogani, L; Caneschi, A; Mattei, G; Mazzoldi, P; Paz, E; Palomares, F J; Cavigli, L

    2010-01-01

    Au-Fe nanoparticles constitute one of the simplest prototypes of a multifunctional nanomaterial that can exhibit both magnetic and optical (plasmonic) properties. This solid solution, not feasible in the bulk phase diagram in thermal equilibrium, can be formed as a nanostructure by out-of-equilibrium processes. Here, the novel magnetic, optical and magneto-optical properties of ion-implanted Au-Fe solid solution nanoparticles dispersed in a SiO 2 matrix are investigated and correlated. The surface plasmon resonance of the Au-Fe nanoparticles with almost equicomposition is strongly damped when compared to pure Au and to Au-rich Au-Fe nanoparticles. In all cases, the Au atoms are magnetically polarized, as measured by x-ray magnetic circular dichroism, and ferromagnetically coupled with Fe atoms. Although the chemical stability of Au-Fe nanoparticles is larger than that of Fe nanoparticles, both the magnetic moment per Fe atom and the order temperature are smaller. These results suggest that electronic and magnetic properties are more influenced by the hybridization of the electronic bands in the Au-Fe solid solution than by size effects. On the other hand, the magneto-optical transitions allowed in the vis-nIR spectral regions are very similar. In addition, we also observe, after studying the properties of thermally treated samples, that the Au-Fe alloy is stabilized, not by surface effects, but by the combination of the out-of-equilibrium nature of the ion implantation technique and by changes in the properties due to size effects.

  13. Coupling between magnetic and optical properties of stable Au-Fe solid solution nanoparticles

    de Julián Fernández, C.; Mattei, G.; Paz, E.; Novak, R. L.; Cavigli, L.; Bogani, L.; Palomares, F. J.; Mazzoldi, P.; Caneschi, A.

    2010-04-01

    Au-Fe nanoparticles constitute one of the simplest prototypes of a multifunctional nanomaterial that can exhibit both magnetic and optical (plasmonic) properties. This solid solution, not feasible in the bulk phase diagram in thermal equilibrium, can be formed as a nanostructure by out-of-equilibrium processes. Here, the novel magnetic, optical and magneto-optical properties of ion-implanted Au-Fe solid solution nanoparticles dispersed in a SiO2 matrix are investigated and correlated. The surface plasmon resonance of the Au-Fe nanoparticles with almost equicomposition is strongly damped when compared to pure Au and to Au-rich Au-Fe nanoparticles. In all cases, the Au atoms are magnetically polarized, as measured by x-ray magnetic circular dichroism, and ferromagnetically coupled with Fe atoms. Although the chemical stability of Au-Fe nanoparticles is larger than that of Fe nanoparticles, both the magnetic moment per Fe atom and the order temperature are smaller. These results suggest that electronic and magnetic properties are more influenced by the hybridization of the electronic bands in the Au-Fe solid solution than by size effects. On the other hand, the magneto-optical transitions allowed in the vis-nIR spectral regions are very similar. In addition, we also observe, after studying the properties of thermally treated samples, that the Au-Fe alloy is stabilized, not by surface effects, but by the combination of the out-of-equilibrium nature of the ion implantation technique and by changes in the properties due to size effects.

  14. Atomic mean-square displacements and the critical-voltage effect in cubic solid solutions

    Shirley, C.G.; Fisher, R.M.

    1979-01-01

    The critical-voltage phenomena observed in high-voltage electron microscope images of bend contours as well as in corresponding Kikuchi or convergent-beam diffraction patterns provide sensitive methods of determining submicroscopic alloy parameters such as Debye temperatures, short-range order, and atomic scattering factors. Only a very limited number of critical voltages can be observed in metal crystals in the voltage range usually available, 100 to 1200 kV, so that quantitative interpretation of the data must be based on a few-parameter model which incorporates all the pertinent factors. A satisfactory two-parameter model has been developed which can be used to interpret or compute the critical voltages of substitutional solid solutions as functions of composition, temperature and short-range order. In the alloy systems Fe-Cr, Ni-Au, Cu-Au and Cu-Al, sufficient critical voltage data are available to derive the model parameters which pertain to atomic bonding in the lattice. In addition to atomic scattering amplitudes, the critical voltage depends strongly on the atomic mean-square displacements. The static contribution to the mean-square displacements is large in alloys with large atomic-radius disparity, and is especially sensitive to short-range order in f.c.c. solid solutions. Well-defined best estimates for the model parameters are used to predict the critical voltage and its sensitivity to composition, temperature and short-range order for a large number of solid solutions. Systems for which critical-voltage studies may be of considerable interest are indicated. (author)

  15. Thermogravimetric analysis of phase transitions in cement compositions mixed by sodium silicate solution

    Fedosov Sergey Viktorovich

    2014-01-01

    Full Text Available This paper presents a study of the capability to modify cement by mechanical activation of sodium silicate water solution. Admixtures or blends of binding agents were employed for modifying concrete properties. The liquid glass is applied to protect from chemically or physically unfavorable environmental impacts, such as acidic medium and high temperature. The sodium silicate is a high-capacity setting accelerator. The increasing of the liquid glass proportion in the mix leads to the degradation of the cement paste plasticity and for this reason it is necessary to reduce the amount of liquid glass in the cement paste. The activation of dilute water solution of sodium silicate into rotary pulsating apparatus directly before tempering of the cement paste is an effective way to decrease mass fraction of liquid glass in the cement paste. The results of the combined influence of liquid glass and mechanical activation on physicochemical processes taking place in cement stone are represented in this research. Thermogravimetric analysis was used in order to study cement blends. Thermogravimetric analysis of modified cement stone assays was performed by thermo analyzer SETARAM TGA 92-24. The results of the analysis of phase transition taking place under high-temperature heating of cement stone modified by the mechanical activation of the water solution of the sodium silicate were introduced. Thermograms of cement stone assays were obtained at different hardening age. The comparison of these thermograms allows us to come to a conclusion on the formation and the retention during long time of a more dense structure of the composite matrix mixed by the mechanical activation of sodium silicate water solution. The relation between the concrete composition and its strength properties was stated. Perhaps, the capability of modified concrete to keep calcium ions in sparingly soluble hydrosilicates leads to the increase in its durability and corrosion resistance.

  16. A quadratic approximation-based algorithm for the solution of multiparametric mixed-integer nonlinear programming problems

    Domí nguez, Luis F.; Pistikopoulos, Efstratios N.

    2012-01-01

    An algorithm for the solution of convex multiparametric mixed-integer nonlinear programming problems arising in process engineering problems under uncertainty is introduced. The proposed algorithm iterates between a multiparametric nonlinear

  17. Processing results of 1,800 gallons of mercury and radioactively contaminated mixed waste rinse solution

    Thiesen, B.P.

    1993-01-01

    The mercury-contaminated rinse solution (INEL waste ID number-sign 123; File 8 waste) was successfully treated at the Idaho National Engineering Laboratory (INEL). This waste was generated during the decontamination of the Heat Transfer Reactor Experiment 3 (HTRE-3) reactor shield tank. Approximately 1,800 gal of waste was generated and was placed into 33 drums. Each drum contained precipitated sludge material ranging from 1--10 in. in depth, with the average depth of about 2.5 in. The pH of each drum varied from 3--11. The bulk liquid waste had a mercury level of 7.0 mg/l, which exceeded the Resource Conservation and Recovery Act (RCRA) limit of 0.2 mg/l. The average liquid bulk radioactivity was about 2.1 pCi/ml, while the average sludge contamination was about 13,800 pci/g. Treatment of the waste required separation of the liquid from the sludge, filtration, pH adjustment, and ion exchange. Because of difficulties in processing, three trials were required to reduce the mercury levels to below the RCRA limit. In the first trial, insufficient filtration of the waste allowed solid particulate produced during pH adjustment to enter into the ion exchange columns and ultimately the waste storage tank. In the second trial, the waste was filtered down to 0.1 μ to remove all solid mercury compounds. However, before filtration could take place, a solid mercury complex dissolved and mercury levels exceeded the RCRA limit after filtration. In the third trial, the waste was filtered through 0.3-A filters and then passed through the S-920 resin to remove the dissolved mercury. The resulting solut

  18. Calculations of oscillation spectra of disordered interstitial solid solutions of vanadium-oxygen system

    Danilkin, S.A.

    1978-01-01

    The frequency spectra calculation of disordered solid interstitial solutions of a vanadium-oxygen system for oxygen concentration of 5.9% and 15.8% (V 16 O and V 16 O 3 ) is carried out. The axially-symmetric model of crystal lattice dinamics with consideration of vanadium-oxygen and vanadium-vanadium interactions up to the second coordination sphere is used. On the whole, the obtained spectra are in qualitative agreement with experiment and reflect correctly all the changes in frequency spectra of pure vanadium on doping with oxygen

  19. The role of solid-solution strengthening in the development of alloys for HTR applications

    Dean, A.V.

    1978-09-01

    In this paper the fundamental factors (lattice distortion, stacking fault energy and diffusion rates) which contribute to solid-solution strengthening are examined and used as a basis for indicating the composition of alloys likely to posses the highest strength at elevated temperatures. Alloys based on Ni-Cr-W-Mo should possess the best properties but alloys based on Ni-Cr-Nb-Ti are also recommended for further study. The effect of alloy composition on corrosion resistance has been excluded from this examination but it should be possible to adjust alloy composition in order to optimise corrosion resistance. (orig./IHOE) [de

  20. Growth of binary solid solution single crystals and calculation of melt surface displacement velocity

    Agamaliyev, Z.A.; Tahirov, V.I.; Hasanov, Z.Y.; Quliyev, A.F.

    2007-01-01

    A binary solid solution single crystal growth method has been worked out. Cylinder feeding alloy with complex content distribution and truncated cone crucible are used. Second component distribution coefficient is more than unit. Content distribution along grown crystal is found by solving continuity equation. After reaching dynamic equilibrium state second component concentration in grown crystal is saturated the value of which is less than the average ona in the feeding alloy. Using the method Ge-Si perfect single crystals has been grown. Calculation method of melt surface displacement velocity has been offered as well

  1. Formation of solid solutions on the boundary of zinc oxidezinc telluride heterojunction

    Tsurkan, A.E.; Buzhor, L.V.

    1987-01-01

    Distribution of ZnO x Te 1-x alloy composition on the interface of zinc oxide-zinc telluride heterojunction depending on the production conditions is investigated. A regularity in the formation of an extended area with constant alloy composition is detected. The regularity is explained by the fact that electric Peltier field conditioned by contact of two heterogeneous semiconductors participates in the solid solution formation process. Peltier field levels off the composition at the end length section. So, a possibility of creating a section with the assigned minor thickness alloy constant composition controlled in the interface of heterojunction occurs

  2. Solid solution barium–strontium chlorides with tunable ammonia desorption properties and superior storage capacity

    Bialy, Agata; Jensen, Peter Bjerre; Blanchard, Didier

    2015-01-01

    with spray drying and in situ thermogravimetric and structural characterization, we synthesize a range of new, stable barium-strontium chloride solid solutions with superior ammonia storage densities. By tuning the barium/strontium ratio, different crystallographic phases and compositions can be obtained...... with different ammonia ab- and desorption properties. In particular it is shown, that in the molar range of 35–50% barium and 65–50% strontium, stable materials can be produced with a practically usable ammonia density (both volumetric and gravimetric) that is higher than any of the pure metal halides...

  3. Local structure in the disordered solid solution of cis- and trans-perinones

    Teteruk, Jaroslav L.; Glinnemann, Juergen; Heyse, Winfried

    2016-01-01

    preferred local arrangements, ordering lengths, and probabilities for the arrangement of neighbouring molecules. The superposition of the atomic positions of all energetically favourable calculated models corresponds well with the experimentally determined crystal structures, explaining not only the atomic....... The crystal structure of the solid solution was determined by single-crystal X-ray analysis. Extensive lattice-energy minimizations with force-field and DFT-D methods were carried out on combinatorially complete sets of ordered models. For the disordered systems, local structures were calculated, including...

  4. Photoluminescence study in solid solutions of CdMgMnTe semimagnetic semiconductors

    Kusraev, Yu.G.; Averkieva, G.K.

    1993-01-01

    Luminescence and resonant Raman scattering in quaternary solid solutions of CdMgMnTe semimagnetic semiconductors are investigated. It is shown that the intensity and position of the luminescence band, conditioned by the 4 T 1 --> 6 A 1 optical transitions in the Mn d-shell, depend on the local crystal environment. Temperature variations of the photoluminescence spectra are interpreted on the base of a model of electron excitation energy transport from Mn 2+ to different recombination centers. In the resonant Raman scattering spectrum were observed three longitudinal vibrational modes with energies near to phonon energies of corresponding binary compounds

  5. Experimental and theoretical investigation of Cr1-xScxN solid solutions for thermoelectrics

    Kerdsongpanya, Sit; Sun, Bo; Eriksson, Fredrik

    2016-01-01

    The ScN- and CrN-based transition-metal nitrides have recently emerged as a novel and unexpected class of materials for thermoelectrics. These materials constitute well-defined model systems for investigating mixing thermodynamics, phase stability, and band structure aiming for property tailoring......-factor improvement by Sc3d orbital delocalization on Cr3d electrons giving decreasing electrical resistivity, while localized Cr3d orbitals with a large DOS slope may yield an improved Seebeck coefficient. Sc-rich solid solutions show a large improvement in power factor compared to pure ScN, and all films have power...

  6. Final Report - Montana State University - Microbial Activity and Precipitation at Solution-Solution Mixing Zones in Porous Media

    Gerlach, Robin [Montana State University

    2014-10-31

    Background. The use of biological and chemical processes that degrade or immobilize contaminants in subsurface environments is a cornerstone of remediation technology. The enhancement of biological and chemical processes in situ, involves the transport, displacement, distribution and mixing of one or more reactive agents. Biological and chemical reactions all require diffusive transport of solutes to reaction sites at the molecular scale and accordingly, the success of processes at the meter-scale and larger is dictated by the success of phenomena that occur at the micron-scale. However, current understanding of scaling effects on the mixing and delivery of nutrients in biogeochemically dynamic porous media systems is limited, despite the limitations this imposes on the efficiency and effectiveness of the remediation challenges at hand. Objectives. We therefore proposed to experimentally characterize and computationally describe the growth, evolution, and distribution of microbial activity and mineral formation as well as changes in transport processes in porous media that receive two or more reactive amendments. The model system chosen for this project was based on a method for immobilizing 90Sr, which involves stimulating microbial urea hydrolysis with ensuing mineral precipitation (CaCO3), and co-precipitation of Sr. Studies at different laboratory scales were used to visualize and quantitatively describe the spatial relationships between amendment transport and consumption that stimulate the production of biomass and mineral phases that subsequently modify the permeability and heterogeneity of porous media. Biomass growth, activity, and mass deposition in mixing zones was investigated using two-dimensional micro-model flow cells as well as flow cells that could be analyzed using synchrotron-based x-ray tomography. Larger-scale flow-cell experiments were conducted where the spatial distribution of media properties, flow, segregation of biological activity and

  7. Study of valence of cerium and praseodymium ions in Pr1-xCexO2 solid solutions

    Gartsman, K.G.; Kartenko, N.F.; Melekh, B.T.

    1990-01-01

    Effect of preparation conditions of Pr 1-x Ce x O 2 solid solutions on Ce and Pr ion valence within Pr 1-x Ce x O 2 system is studied. The data obtained enable to conclude that praseodymium may depending on annealing conditions change its state from Pr 3+ to Pr 4+ , while Ce 4+ is stable in Pr 1-x Ce x O 2 solid solutions

  8. Optical CT imaging of solid radiochromic dosimeters in mismatched refractive index solutions using a scanning laser and large area detector.

    Dekker, Kurtis H; Battista, Jerry J; Jordan, Kevin J

    2016-08-01

    The practical use of the PRESAGE® solid plastic dosimeter is limited by the inconvenience of immersing it in high-viscosity oils to achieve refractive index matching for optical computed tomography (CT) scanning. The oils are slow to mix and difficult to clean from surfaces, and the dosimeter rotation can generate dynamic Schlieren inhomogeneity patterns in the reference liquid, limiting the rotational and overall scan speed. Therefore, it would be beneficial if lower-viscosity, water-based solutions with slightly unmatched refractive index could be used instead. The purpose of this work is to demonstrate the feasibility of allowing mismatched conditions when using a scanning laser system with a large acceptance angle detector. A fiducial-based ray path measurement technique is combined with an iterative CT reconstruction algorithm to reconstruct images. A water based surrounding liquid with a low viscosity was selected for imaging PRESAGE® solid dosimeters. Liquid selection was optimized to achieve as high a refractive index as possible while avoiding rotation-induced Schlieren effects. This led to a refractive index mismatch of 6% between liquid and dosimeters. Optical CT scans were performed with a fan-beam scanning-laser optical CT system with a large area detector to capture most of the refracted rays. A fiducial marker placed on the wall of a cylindrical sample occludes a given light ray twice. With knowledge of the rotation angle and the radius of the cylindrical object, the actual internal path of each ray through the dosimeter can be calculated. Scans were performed with 1024 projections of 512 data samples each, and rays were rebinned to form 512 parallel-beam projections. Reconstructions were performed on a 512 × 512 grid using 100 iterations of the SIRT iterative CT algorithm. Proof of concept was demonstrated with a uniformly attenuating solution phantom. PRESAGE® dosimeters (11 cm diameter) were irradiated with Cobalt-60 irradiator to achieve

  9. ASSESSMENT OF THE ABILITY OF STANDARD SLURRY PUMPS TO MIX SOLIDS WITH LIQUIDS IN TANK 50H

    Poirier, M.

    2011-11-11

    Tank 50H is the feed tank for the Saltstone Production Facility (SPF). In the summer of 2011, Tank 50H contained two standard slurry pumps and two quad volute slurry pumps. Current requirements for mixing operation is to run three pumps for one hour prior to initiating a feed transfer to SPF. Savannah River Site (SRS) Liquid Waste moved both of the Quad Volute pumps from Tank 50H to Tank 51H to replace pumps in Tank 51H that were failing. In addition, one of the standard pumps in Tank 50H exhibits high seal leakage and vibration. SRS Liquid Waste requested Savannah River National Laboratory (SRNL) to conduct a study to evaluate the feasibility of mixing the contents of Tank 50H with one to three standard slurry pumps. To determine the pump requirements to mix solids with liquids in Tank 50H, the author reviewed the pilot-scale blending work performed for the Small Column Ion Exchange Process (SCIX), SRNL computational fluid dynamics (CFD) modeling, Tank 50H operating experience, and the technical literature, and applied the results to Tank 50H to determine the number, size, and operating parameters of pumps needed to mix the solid particles with the liquid in Tank 50H. The analysis determined pump requirements to suspend the solids with no 'dead zones', but did not determine the pump requirements to produce a homogeneous suspension. In addition, the analysis determined the pump requirements to prevent the accumulation of a large amount of solid particles under the telescoping transfer pump. The conclusions from this analysis follow: (1) The analysis shows that three Quad Volute pumps should be able to suspend the solid particles expected ({approx}0.6 g/L insoluble solids, {approx}5 micron) in Tank 50H. (2) Three standard slurry pumps may not be able to suspend the solid particles in Tank 50H; (3) The ability of two Quad Volute pumps to fully suspend all of the solid particles in Tank 50H is marginal; and (4) One standard slurry pump should be able to

  10. Pulse and gamma radiolytic studies of Ag, Cd and mixed clusters in aqueous solutions of carboxymethyl cellulose and gelatin

    Kapoor, Sudhir; Gopinathan, C.

    1996-01-01

    Pulse and gamma radiolytic studies in aqueous solutions of Ag, Cd and mixed clusters were carried out in carboxymethylcellulose (CMC) or gelatin. The reaction rate of e aq - with Ag + is lower in the presence of CMC or gelatin and oligomeric clusters of silver, Cd and mixed clusters get stabilized in their presence. (author). 2 refs., 2 figs

  11. Formation of Ni(Al, Mo) solid solutions by mechanical alloying and their ordering on heating

    Portnoj, V.K.; Tomilin, I.A.; Blinov, A.M.; Kulik, T.

    2002-01-01

    The Ni(Al, Mo) solid solutions with different crystalline lattice periods (0.3592 and 0.3570 nm correspondingly) are formed in the course of the Ni 70 Al 25 Mo 5 and Ni 75 Al 20 Mo 5 powder mixtures mechanical alloying (MA) (through the mechanical activation in a vibrating mill). After MA the Mo atoms in the Ni 75 Al 20 Mo 5 mixture completely replace the aluminium positions with formation of the Ni 75 (AlMo) 25 (the L1 2 -type) ternary ordered phase, whereby such a distribution remains after heating up to 700 deg C. The Ni(Al, Mo) metastable solution is formed by MA in the Ni 75 Al 20 Mo 5 mixture, which decays with the release of molybdenum and the remained aluminide undergoes ordering by the L1 2 -type [ru

  12. Effect of Alkaline Solution with Varying Mix Proportion on Geopolymer Mortar

    Karuppuchamy, K.; Ananthkumar, M.; Raghavapriya, S. M.

    2018-02-01

    Cement production is attributed by emission of carbon dioxide which causes severe environmental impacts. This has led to the invention of special construction materials which can replace cement. On the other hand, these construction materials (like Fly ash, Metakaolin) also need to be inexpensive and should possess all the characteristics of cementitious materials. In this project, the effect of geopolymerization on the properties of the end product were studied with varying distillation of NaOH solution (10M, 12M and 15M) for different mix proportion (1:1, 1:2 and 1:3). Curing was done for 1 day at a temperature of 60°C and 80°C respectively. The densities, compressive strength, alkalinity, co-efficient of absorption were determined. As a result, the experiments showed the effect of factors such as mix proportion, curing temperature and curing day on the physical and mechanical properties such as mix proportion of the geopolymer concrete. Results of NaOH concentration of 12M concentration cured for 24 hours at 80°C and 60°C showed better mechanical performance than the rest of the concentrations.

  13. Thermodynamics of mixed-ligand complex formation of mercury (II) ethylenediaminetetraacetate with amino acids in solution

    Pyreu, Dmitrii, E-mail: pyreu@mail.ru [Department of Inorganic and Analytic Chemistry, Ivanovo State University, Ermak 39, Ivanovo 153025 (Russian Federation); Kozlovskii, Eugenii [Department of Inorganic and Analytic Chemistry, Ivanovo State University, Ermak 39, Ivanovo 153025 (Russian Federation); Gruzdev, Matvei; Kumeev, Roman [Institute of Solution Chemistry, Ivanovo (Russian Federation)

    2012-11-20

    Highlights: Black-Right-Pointing-Pointer Stable mixed ligand complexes of HgEdta with amino acids at physiological pH value. Black-Right-Pointing-Pointer The thermodynamic and NMR data evident the ambidentate coordination mode of arginine. Black-Right-Pointing-Pointer Participation of the guanidinic group of Arg in coordination process. Black-Right-Pointing-Pointer Binuclear complexes (HgEdta){sub 2}L with the bridging function of amino acid. - Abstract: The mixed-ligand complex formation in the systems Hg{sup 2+} - Edta{sup 4-} - L{sup -}(L = Arg, Orn, Ser) has been studied by means of calorimetry, pH-potentiometry and NMR spectroscopy in aqueous solution at 298.15 K and the ionic strength of I = 0.5 (KNO{sub 3}). The thermodynamic parameters of formation of the HgEdtaL, HgEdtaHL and (HgEdta){sub 2}L complexes have been determined. The most probable coordination mode for the complexone and the amino acid in the mixed-ligand complexes was discussed.

  14. Microstructural and microchemical studies of phase stability in V-O solid solution

    Ghosh, Chanchal, E-mail: chanchal@igcar.gov.in [Metallurgy & Materials Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam 603102, Tamil Nadu (India); Singh, Akash [Metallurgy & Materials Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam 603102, Tamil Nadu (India); Basu, Joysurya [Metallurgy & Materials Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam 603102, Tamil Nadu (India); Department of Metallurgical Engineering, Indian Institute of Technology (BHU), Varanasi 221005, Uttar Pradesh (India); Ramachandran, Divakar; Mohandas, E [Metallurgy & Materials Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam 603102, Tamil Nadu (India)

    2017-02-15

    Over the last couple of decades vanadium and V-based alloys have received significant attention as a potential structural material for fusion power applications because of their favourable mechanical properties under irradiation and at elevated temperatures. They are also considered as the advanced options of storage materials for hydrogen and its isotopes. However, the higher affinity of V for O, C and N poses critical challenges in its engineering applications since they lead to degradation of mechanical properties. They can further interact with the matrix to produce metallic oxy-carbo-nitride precipitates. To a certain limit, these precipitates are beneficial and can be exploited to enhance the mechanical behaviour of the alloy through suitable microstructural design. However, this requires a prior knowledge of the interaction between the alloy and the impurity solutes. In the present work vanadium specific experiments have been designed and carried out to bring out the V-interstitial solute interaction by charging oxygen in the near surface region of vanadium. Microstructural and microchemical behaviour of the V-O solid solution has been studied through HRTEM (high resolution transmission electron microscopy) and HAADF (high angle annular dark field) coupled with EELS. Quantitative electron microscopy has been carried out to study structural modification of the alloy in atomic level caused by O charging. - Highlights: •Controlled experiments were carried out in pulsed laser ablation set-up to promote V-O interaction. • As a consequence of O dissolution, V transformed into a bct structure which is otherwise a bcc structure. •In V-O solid solution, dissolved O in the V matrix introduces significant amount of lattice strain. • Present work can be extended for introducing interstitial O in other pure transition metals and their alloys.

  15. Complexon Solutions in Freon for Decontamination of Solids and SNF Treatment

    Kamachev, V.; Shadrin, A.; Murzin, A.

    2008-01-01

    Full text of publication follows: The possibility of using complexon solutions in supercritical and compressed carbon dioxide for decontamination of solid surfaces and for spent nuclear fuel (SNF) treatment was demonstrated in the works of Japanese, Russian and American researchers. The obtained data showed that the use of complexon solutions in carbon dioxide sharply decreases the volume of secondary radioactive wastes because it can be easily evaporated, purified and recycled. Moreover, high penetrability of carbon dioxide allows decontamination of surfaces with complex shape. However, one of the disadvantages of carbon dioxide is its high working pressure (10-20 MPa for supercritical CO 2 and 7 MPa for compressed CO 2 ). Moreover, in case of SNF treatment, carbon dioxide solvent will be contaminated with 14 C, which in the course of SNF dissolution in CO 2 containing TBP*HNO 3 adduct stage will be oxidized into CO 2 . These main disadvantages can be eliminated by using complexon solutions in ozone-friendly Freon HFC-134a for decontamination and SNF treatment. Our experimental data for real contaminated materials showed that the decontamination factor for complexon solutions in liquid Freon HFC-134a at 1,2 MPa and 25 deg. C is close to that attained in carbon dioxide. Moreover, the possibility of SNF treatment in Freon HFC-134a was demonstrated in trials using real SNF and its imitators. (authors)

  16. Crystalline structure and electrical properties of Dy1-XCaXMnO3 solid solution

    Durán, P.

    2002-12-01

    Full Text Available Solid solutions corresponding to the Dy1-xCaXMnO3 system, x=0.0 to 0.60 have been studied. The powders were prepared by solid state reaction of the corresponding oxides and carbonates. Sintered bodies were obtained by firing between 1250 and 1450ºC. All the compositions showed single-phased perovskite-type structure with orthorhombic symmetry and Space Group Pbnm. Increase of the CaO content leads to a monotonic decrease of the orthorhombicity factor b/a with the Ca2+ concentration up to x=0.60. All the solid solutions crystallised with the same O’-type orthorhombic perovskite structure such as pure DyMnO3. Electrical measurements have shown semiconducting behaviour for all the solid solutions. The room temperature conductivity increases monotonically with the CaO content. The 60/40 Ca/Dy composition showed a high value of the electrical conductivity and a correlative very low value of the activation energy. Thermally activated small polaron hopping mechanism controls the conductivity of these perovskite ceramics.Se han estudiado soluciones sólidas correspondientes al sistema Dy1-xCaxMnO3, x=0.0 a 0.60. Los polvos cerámicos fueron preparados por reacción en estado sólido de los correspondientes óxidos y carbonatos. Los materiales cerámicos se obtuvieron por sinterización entre 1250º y 1450ºC. Todas las composiciones fueron monofásicas y mostraron una estructura tipo perovskita, con simetría ortorrómbica y Grupo Espacial Pbnm. El aumento del contenido en CaO llevó a una disminución monótona del factor de ortorrombicidad, b/a. Todas las soluciones sólidas cristalizaron con el mismo tipo de estructura perovskita ortorrómbica O’, como la del compuesto puro DyMnO3. Las medidas eléctricas mostraron comportamiento semiconductor en todas las soluciones sólidas. La conductividad a temperatura ambiente aumenta monótonamente con el contenido de CaO. La composición 60/40 mostró un elevado valor de conductividad y un correlativo

  17. Lattice parameters and electrical resistivity of Ceria-Yttria solid solutions

    Rey, Jose Fernando Queiruga

    2002-01-01

    Ce0 2 :u mol% Y 2 O 3 (u=0, 4, 6, 8, 10 and 12) solid solutions were prepared by the conventional powder mixture technique. The main purposes of this work are: the study of the dependence of the lattice parameter of the Ceria cubic phase on the Yttria content, comparing the experimental data with data calculated according to the existing theoretical models; to determine the dependence of the ionic conductivity on the Yttria content; and to study the stability of the cubic fluorite phase after extensive thermal treatments (aging) of the Ceria-Yttria specimens. The results show that the lattice parameter of the solid solutions follows the Vegard's law and can be described by the two reported theoretical models. The 8 mol% Yttria-doped Ceria was found to present the largest value of ionic conductivity. Preliminary results show that a large decrease is found for only 1 h aging at 700 deg C and that the ionic conductivity decreases for ceramic specimens aged for times up to 10 h. (author)

  18. Combined solid state and solution NMR studies of α,ε-15N labeled bovine rhodopsin

    Werner, Karla; Lehner, Ines; Dhiman, Harpreet Kaur; Richter, Christian; Glaubitz, Clemens; Schwalbe, Harald; Klein-Seetharaman, Judith; Khorana, H. Gobind

    2007-01-01

    Rhodopsin is the visual pigment of the vertebrate rod photoreceptor cell and is the only member of the G protein coupled receptor family for which a crystal structure is available. Towards the study of dynamics in rhodopsin, we report NMR-spectroscopic investigations of α,ε- 15 N-tryptophan labeled rhodopsin in detergent micelles and reconstituted in phospholipids. Using a combination of solid state 13 C, 15 N-REDOR and HETCOR experiments of all possible 13 C' i-1 carbonyl/ 15 N i -tryptophan isotope labeled amide pairs, and H/D exchange 1 H, 15 N-HSQC experiments conducted in solution, we assigned chemical shifts to all five rhodopsin tryptophan backbone 15 N nuclei and partially to their bound protons. 1 H, 15 N chemical shift assignment was achieved for indole side chains of Trp35 1.30 and Trp175 4.65 . 15 N chemical shifts were found to be similar when comparing those obtained in the native like reconstituted lipid environment and those obtained in detergent micelles for all tryptophans except Trp175 4.65 at the membrane interface. The results suggest that the integrated solution and solid state NMR approach presented provides highly complementary information in the study of structure and dynamics of large membrane proteins like rhodopsin

  19. The origin of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution crystals

    Li, Fei; Zhang, Shujun; Yang, Tiannan; Xu, Zhuo; Zhang, Nan; Liu, Gang; Wang, Jianjun; Wang, Jianli; Cheng, Zhenxiang; Ye, Zuo-Guang; Luo, Jun; Shrout, Thomas R.; Chen, Long-Qing (Penn); (Xian Jiaotong); (CIW); (Simon); (TRS Techn); (Wollongong)

    2016-12-19

    The discovery of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution single crystals is a breakthrough in ferroelectric materials. A key signature of relaxor-ferroelectric solid solutions is the existence of polar nanoregions, a nanoscale inhomogeneity, that coexist with normal ferroelectric domains. Despite two decades of extensive studies, the contribution of polar nanoregions to the underlying piezoelectric properties of relaxor ferroelectrics has yet to be established. Here we quantitatively characterize the contribution of polar nanoregions to the dielectric/piezoelectric responses of relaxor-ferroelectric crystals using a combination of cryogenic experiments and phase-field simulations. The contribution of polar nanoregions to the room-temperature dielectric and piezoelectric properties is in the range of 50–80%. A mesoscale mechanism is proposed to reveal the origin of the high piezoelectricity in relaxor ferroelectrics, where the polar nanoregions aligned in a ferroelectric matrix can facilitate polarization rotation. This mechanism emphasizes the critical role of local structure on the macroscopic properties of ferroelectric materials.

  20. The origin of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution crystals.

    Li, Fei; Zhang, Shujun; Yang, Tiannan; Xu, Zhuo; Zhang, Nan; Liu, Gang; Wang, Jianjun; Wang, Jianli; Cheng, Zhenxiang; Ye, Zuo-Guang; Luo, Jun; Shrout, Thomas R; Chen, Long-Qing

    2016-12-19

    The discovery of ultrahigh piezoelectricity in relaxor-ferroelectric solid solution single crystals is a breakthrough in ferroelectric materials. A key signature of relaxor-ferroelectric solid solutions is the existence of polar nanoregions, a nanoscale inhomogeneity, that coexist with normal ferroelectric domains. Despite two decades of extensive studies, the contribution of polar nanoregions to the underlying piezoelectric properties of relaxor ferroelectrics has yet to be established. Here we quantitatively characterize the contribution of polar nanoregions to the dielectric/piezoelectric responses of relaxor-ferroelectric crystals using a combination of cryogenic experiments and phase-field simulations. The contribution of polar nanoregions to the room-temperature dielectric and piezoelectric properties is in the range of 50-80%. A mesoscale mechanism is proposed to reveal the origin of the high piezoelectricity in relaxor ferroelectrics, where the polar nanoregions aligned in a ferroelectric matrix can facilitate polarization rotation. This mechanism emphasizes the critical role of local structure on the macroscopic properties of ferroelectric materials.

  1. Highly photoluminescent europium tetraphenylimidodiphosphinate ternary complexes with heteroaromatic co-ligands. Solution and solid state studies

    Pietraszkiewicz, Marek, E-mail: mpietraszkiewicz@ichf.edu.pl [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Pietraszkiewicz, Oksana; Karpiuk, Jerzy; Majka, Alina [Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw (Poland); Dutkiewicz, Grzegorz; Borowiak, Teresa [Adam Mickiewicz University, Faculty of Chemistry, Department of Crystallography, Grunwaldzka 6, 60-780 Poznań (Poland); Kaczmarek, Anna M. [L3–Luminescent Lanthanide Lab, f-element coordination chemistry, Ghent University, Department of Inorganic and Physical Chemistry, Krijgslaan 281, Building S3, 9000 Gent (Belgium); Van Deun, Rik, E-mail: rik.vandeun@ugent.be [L3–Luminescent Lanthanide Lab, f-element coordination chemistry, Ghent University, Department of Inorganic and Physical Chemistry, Krijgslaan 281, Building S3, 9000 Gent (Belgium)

    2016-02-15

    Tetraphenylimidodiphosphinate (tpip) forms neutral 3:1 complexes with lanthanide ions. These complexes can accommodate one ancillary planar heterocyclic ligand to complement their coordination sphere of Eu{sup 3+} to coordination number 8. Several co-ligands were tested to form new complexes: 1,10-phenanthroline, bathophenanthroline, 2,4,6-tris(2-pyridyl)-1,3,5-triazine, dipyrido[3,2-f:2′,3′-h]quinoxaline and 2,2′:6′,2′′-terpyridine. The addition of heterocyclic N,N-bidentate co-ligands to the coordination sphere results in a dramatic (by a factor of 45–50) luminescence enhancement of the parent Eu(tpip){sub 3}. The solid-state measurements confirmed that the ancillary ligands strongly increased the photoluminescence quantum yield (PLQY) of the investigated complexes. - Highlights: • We have disovered highly photoluminescent ternary Eu(III) complexes. • They consist of Eu(III) tetraphenylimidodiphosphinate, and planar heterocyclic ligands. • The increase in photoluminescence quantum yields in solution is enhanced up to 50 times in solution. • The solid-state photoluminescence exceeds 80% at room temperature.

  2. Multiple Multidentate Halogen Bonding in Solution, in the Solid State, and in the (Calculated) Gas Phase.

    Jungbauer, Stefan H; Schindler, Severin; Herdtweck, Eberhardt; Keller, Sandro; Huber, Stefan M

    2015-09-21

    The binding properties of neutral halogen-bond donors (XB donors) bearing two multidentate Lewis acidic motifs toward halides were investigated. Employing polyfluorinated and polyiodinated terphenyl and quaterphenyl derivatives as anion receptors, we obtained X-ray crystallographic data of the adducts of three structurally related XB donors with tetraalkylammonium chloride, bromide, and iodide. The stability of these XB complexes in solution was determined by isothermal titration calorimetry (ITC), and the results were compared to X-ray analyses as well as to calculated binding patterns in the gas phase. Density functional theory (DFT) calculations on the gas-phase complexes indicated that the experimentally observed distortion of the XB donors during multiple multidentate binding can be reproduced in 1:1 complexes with halides, whereas adducts with two halides show a symmetric binding pattern in the gas phase that is markedly different from the solid state structures. Overall, this study demonstrates the limitations in the transferability of binding data between solid state, solution, and gas phase in the study of complex multidentate XB donors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Highly photoluminescent europium tetraphenylimidodiphosphinate ternary complexes with heteroaromatic co-ligands. Solution and solid state studies

    Pietraszkiewicz, Marek; Pietraszkiewicz, Oksana; Karpiuk, Jerzy; Majka, Alina; Dutkiewicz, Grzegorz; Borowiak, Teresa; Kaczmarek, Anna M.; Van Deun, Rik

    2016-01-01

    Tetraphenylimidodiphosphinate (tpip) forms neutral 3:1 complexes with lanthanide ions. These complexes can accommodate one ancillary planar heterocyclic ligand to complement their coordination sphere of Eu 3+ to coordination number 8. Several co-ligands were tested to form new complexes: 1,10-phenanthroline, bathophenanthroline, 2,4,6-tris(2-pyridyl)-1,3,5-triazine, dipyrido[3,2-f:2′,3′-h]quinoxaline and 2,2′:6′,2′′-terpyridine. The addition of heterocyclic N,N-bidentate co-ligands to the coordination sphere results in a dramatic (by a factor of 45–50) luminescence enhancement of the parent Eu(tpip) 3 . The solid-state measurements confirmed that the ancillary ligands strongly increased the photoluminescence quantum yield (PLQY) of the investigated complexes. - Highlights: • We have disovered highly photoluminescent ternary Eu(III) complexes. • They consist of Eu(III) tetraphenylimidodiphosphinate, and planar heterocyclic ligands. • The increase in photoluminescence quantum yields in solution is enhanced up to 50 times in solution. • The solid-state photoluminescence exceeds 80% at room temperature.

  4. Dissolution of thorium/uranium mixed oxide in nitric acid-hydrofluoric acid solution

    Filgueiras, S.A.C.

    1984-01-01

    The dissolution process of thorium oxide and mixed uranium-thorium oxide is studied, as a step of the head-end of the fuel reprocessing. An extensive bibliography was analysed, concerning the main aspects of the system, specially the most important process variables. Proposed mechanisms and models for the thorium oxide dissolution are presented. The laboratory tests were performed in two phases: at first, powdered thoria was used as the material to be dissolved. The objective was to know how changes in he concentrations of the dissolvent solution components HNO 3 , HF and Al(NO 3 ) 3 affect the dissolution rate. The tests were planned according to the fractional factorial method. Thes results showed that it is advantageous to work with powdered material, since the reaction occurs rapidly. And, if the Thorex solution (HNO 3 13M, HF 0.05M and Al(NO 3 ) 3 0.10M) is a suitable dissolvent, it was verified that it is possible to reduce the concentration of either nitric or fluoridric acid, without reducing the reaction rate to an undesirable value. It was also observed significant interaction between the components of the dissolvent solution. In the second phase of the tests, (Th, 5%U)O 2 sintered pellets were used. The main goals were to know the pellets dissolution behaviour and to compare the results for different pellets among themselves. It was observed that the metallurgical history of the material strongly influences its dissolution, specially the density and the microstructure. It was also studied how the (Th,U)O 2 mass/Thorex solution volume ratio affects the time needed to obtain an 1 M Th/liter solution. The activation energy for the reaction was obtained. (Author) [pt

  5. 3He release characteristics of metal tritides and scandium--tritium solid solutions

    Perkins, W.G.; Kass, W.J.; Beavis, L.C.

    1976-01-01

    Tritides of such metals as Sc, Ti, and Er are useful materials for determining the effects of He accumulation in metallic solids, for example, CTR first wall materials. Such effects include lattice strain and gross deformation which are related to 3 He retention and ultimate release. Long term gas release studies have indicated that, during the early life of a metal ditritide, a large fraction of the 3 He is retained in the solid. At more advanced ages, the 3 He release rate becomes comparable to the generation rate. Statistical analysis of the data indicates that the acceleration in 3 He release rate depends on accumulated 3 He concentration rather than strictly on age. 3 He outgassing results are presented for thin films of ScT 2 , TiT 2 , and ErT 2 , and the critical 3 He concentrations are discussed in terms of a percolation model. Phase transformations which occur on tritide formation cast some doubt on the validity of extrapolating results obtained for metal tritides to predictions regarding the accumulation of helium in metals. Sc is unique among the early transition and rare-earth metals in that the metal exhibits a very high room temperature T solubility (T/Sc = 0.4) with no phase transformation. Indeed, even the lattice parameters of the hcp Sc lattice are only minimally changed by T solution. Single crystal ScT/sub 0.3/ samples in two crystallographic orientations were obtained. Using a very sensitive technique, 3 He emission was measured from both these samples, as well as from fine-grained thin film Sc--T solid solution samples (ScT/sub 0.3-0.4/). The fine-grained film samples release 3 He at 2-3 percent of the generation rate, while the emission rate from the single-crystal samples is approximately 0.05 percent of the generation rate, indicating a strong grain size effect

  6. Investigating conceptual models for physical property couplings in solid solution models of cement

    Benbow, Steven; Watson, Claire; Savage, David

    2005-11-01

    The long-term behaviour of cementitious engineered barriers is an important process to consider when modelling the migration of radionuclides from a geological repository for nuclear waste. The modelling of cement is complicated by the fact that the cement is dominated by the behaviour of calcium silicate hydrate (CSH) gel which is a complex solid exhibiting incongruent dissolution behaviour. In this report, we have demonstrated the implementation of a solid-solution CSH gel model within a geochemical transport modelling framework using the Raiden computer code to investigate cement/concrete-groundwater interactions. The modelling conducted here shows that it is possible to couple various conceptual models for the evolution of physical properties of concrete with a solid solution model for cement degradation in a fully coupled geochemical transport model to describe the interaction of cement/concrete engineered barriers with groundwater. The results show that changes to the conceptual models and flow rates can give rise to very different evolutions. Most simulations were carried out at a reduced 'experimental' scale rather than full repository scale. The work has shown the possibility to investigate also the changing physical properties of degrading cement. To further develop the model more emphasis is needed on kinetics and the detailed development of a nearly clogged pore space. Modelling of the full repository scale could be another way forward to understand the behaviour of degrading concrete. A general conclusion is that the combined effects of chemical evolution and physical degradation should be analysed in performance assessments of cementitious repositories. Moreover, the project results will be used as one basis in coming reviews of SKB's safety assessments of repositories for spent fuel and low-and intermediate level waste

  7. Investigating conceptual models for physical property couplings in solid solution models of cement

    Benbow, Steven; Watson, Claire; Savage, David [Quintesssa Ltd., Henley-on-Thames (United Kingdom)

    2005-11-15

    The long-term behaviour of cementitious engineered barriers is an important process to consider when modelling the migration of radionuclides from a geological repository for nuclear waste. The modelling of cement is complicated by the fact that the cement is dominated by the behaviour of calcium silicate hydrate (CSH) gel which is a complex solid exhibiting incongruent dissolution behaviour. In this report, we have demonstrated the implementation of a solid-solution CSH gel model within a geochemical transport modelling framework using the Raiden computer code to investigate cement/concrete-groundwater interactions. The modelling conducted here shows that it is possible to couple various conceptual models for the evolution of physical properties of concrete with a solid solution model for cement degradation in a fully coupled geochemical transport model to describe the interaction of cement/concrete engineered barriers with groundwater. The results show that changes to the conceptual models and flow rates can give rise to very different evolutions. Most simulations were carried out at a reduced 'experimental' scale rather than full repository scale. The work has shown the possibility to investigate also the changing physical properties of degrading cement. To further develop the model more emphasis is needed on kinetics and the detailed development of a nearly clogged pore space. Modelling of the full repository scale could be another way forward to understand the behaviour of degrading concrete. A general conclusion is that the combined effects of chemical evolution and physical degradation should be analysed in performance assessments of cementitious repositories. Moreover, the project results will be used as one basis in coming reviews of SKB's safety assessments of repositories for spent fuel and low-and intermediate level waste.

  8. Report: risk factors associated with treatment of mixed municipal solid waste in the Indian context.

    Nema, Asit

    2009-12-01

    Across India, all small and large urban local bodies (ULB) alike are grappling with the problem of municipal solid waste (MSW), which has reached critical dimensions because of, among others, rapidly increasing quantities and complex characteristics, inadequate regulation, lack of awareness, concern and cooperation on the part of the urban residents, limited resources for collection, transport and safe disposal, and limited expertise on the part of the ULBs. A number of ULBs have attempted to address the two-fold constraint of resources and land by setting up treatment plants under the premise of generating revenue and reducing liability of safe disposal. Over the last three decades, under the paradigms of converting 'waste to energy' and 'waste to wealth' various technologies have been tried out, however time and again it is seen that irrespective of the technology, MSW treatment plants run in to difficulties and/or close down. The issues do not pertain just to technology but are systemic and encompass project development, feedstock delivery system including quality and quantity, climate, high life-cycle costs, low value realization on outputs and adverse environmental and social impacts. With such a wide range of risk factors, experience has shown that the probability of manifestation of any one of them or a combination thereof at one or the other stages of the project is quite high. Investment in a mixed MSW treatment plant therefore can not deliver positive financial returns, rather it can become a non-performing asset without even guaranteeing the desired environmental and public health benefits. This paper therefore argues for the adoption of a robust, elastic and most forgiving option of sanitary landfill as a dependable and safe disposal system for MSW.

  9. Reducing beryllium content in mixed bed solid-type breeder blankets

    Shimwell, J., E-mail: mail@jshimwell.com [Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Lilley, S.; Morgan, L.; Packer, L.; Kovari, M.; Zheng, S. [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom); McMillan, J. [Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom)

    2016-11-01

    Highlights: • The ratio of breeder ceramic to neutron multiplier of breeder blankets was varied linearly with depth. • Blankets with varying composition were found to perform better than uniform composition breeder blankets. • It was also possible to reduce the amount of beryllium required by the blanket. - Abstract: Beryllium (Be) is a precious resource with many high value uses, the low energy threshold (n,2n) reaction makes Be an excellent neutron multiplier for use in fusion breeder blankets. Estimates of Be requirements and available resources suggest that this could represent a major supply difficulty for solid-type blanket concepts. Reducing the quantity of Be required by breeder blankets would help to alleviate the problem to some extent. In addition, it is important that the reduction in the Be quantity does not diminish the blanket's performance in key aspects such as the tritium breeding ratio (TBR), energy multiplication and peak nuclear heating. Mixed pebble bed designs allow for the multiplier fraction to be varied throughout the blanket. This neutronics study used MCNP 6 to investigate linear variations of the multiplier fraction in relation to blanket depth, in order to better utilise the important multiplying Be(n,2n) and breeding reactions. Blankets with a uniform multiplier fraction showed little scope for reduction in Be mass. Blankets with varying multiplier fractions were able to simultaneously use 10% less Be, increase the energy amplification by 1%, reduce the peak heating by 7% and maintaining a sufficient TBR when compared to the performance achievable using a uniform composition.

  10. Critical test of vibrational dephasing theories in solids using spontaneous Raman scattering in isotopically mixed crystals

    Marks, S.; Cornelius, P.A.; Harris, C.B.

    1980-01-01

    A series of experiments have been conducted in order to evaluate the relative importance of several recent theories of vibrational dephasing in solids. The theories are discussed briefly, and are used to interpret the temperature dependence of the C--H and C--D stretch bands in the spontaneous Raman spectra of h 14 - and d 14 -1,2,4,5-tetramethyl benzene (durene). The infrared spectra of these same molecules are also reported in the region of the combination bands involving C--H (or C--D) stretches and low-frequency modes. The results support the applicability of the model of Harris et al., [C. B. Harris, R. M. Shelby and P. A. Cornelius, Phys. Rev. Lett. 38, 1415 (1977); Chem Phys. Lett. 57, 8 (1978); R. M. Shelby, C. B. Harris, and P. A. Cornelius, J. Chem. Phys. 70, 34 (1979)], based on energy exchange in anharmonically coupled low-frequency modes. This theory is then used, in connection with Raman spectra obtained in isotopically mixed samples of durene, to elucidate the vibrational dynamics underlying the dephasing. It is found that the results are consistent with the hypothesis that some low-frequency modes in this molecule are significantly delocalized or ''excitonic'' in character, and that this delocalization may be studied by means of Raman spectroscopy on the low-frequency modes themselves, as well as by exchange analysis of the coupled high-frequency modes. These conclusions represent a generalization and extension of the previously published exchange model [R. M. Shelby, C. B. Harris, and P. A. Cornelius, J. Chem Phys. 70, 34 (1979)

  11. Calculational assessment of critical experiments with mixed-oxide fuel pin arrays moderated by organic solution

    Smolen, G.R.; Funabashi, H.

    1987-01-01

    Critical experiments have been conducted with organically moderated mixed-oxide (MOX) fuel pin assemblies at the Pacific Northwest Lab. Critical Mass Lab. These experiments are part of a joint exchange program between the US Dept. of Energy and the Power Reactor and Nuclear Fuel Development Corp. of Japan in the area of criticality data development. The purpose of these experiments is to benchmark computer codes and cross-section libraries and to assess the reactivity difference between systems moderated by water and those moderated by an organic solution. Past studies have indicated that some organic mixtures may be better moderators than water. This topic is of particular importance to the criticality safety of fuel processing plants where fissile material is dissolved in organic solutions during the solvent extraction process. In the past, it has been assumed that the codes and libraries benchmarked with water-moderated experiments were adequate when performing design and licensing studies of organically moderated systems. Calculations presented in this paper indicated that the Scale code system and the 27-energy-group cross-section library accurately compute k/sub eff/ for organically moderated MOX fuel pin assemblies. Furthermore, the reactivity of an organic solution with a 32 vol % TBP/68 vol% NPH mixture in a heterogeneous configuration is the same, for practical purposes, as water

  12. Calculational assessment of critical experiments with mixed oxide fuel pin arrays moderated by organic solution

    Smolen, G.R.

    1987-01-01

    Critical experiments have been conducted with organic-moderated mixed oxide (MOX) fuel pin assemblies at the Pacific Northwest Laboratory (PNL) Critical Mass Laboratory (CML). These experiments are part of a joint exchange program between the United States Department of Energy (USDOE) and the Power Reactor and Nuclear Fuel Development Corporation (PNC) of Japan in the area of criticality data development. The purpose of these experiments is to benchmark computer codes and cross-section libraries and to assess the reactivity difference between systems moderated by water and those moderated by an organic solution. Past studies have indicated that some organic mixtures may be better moderators than water. This topic is of particular importance to the criticality safety of fuel processing plants where fissile material is dissolved in organic solutions during the solvent extraction process. In the past, it has been assumed that the codes and libraries benchmarked with water-moderated experiments were adequate when performing design and licensing studies of organic-moderated systems. Calculations presented in this paper indicated that the SCALE code system and the 27-energy-group cross-section accurately compute k-effectives for organic moderated MOX fuel-pin assemblies. Furthermore, the reactivity of an organic solution with a 32-vol-% TBP/68-vol-% NPH mixture in a heterogeneous configuration is the same, for practical purposes, as water. 5 refs

  13. Efficient green phosphorescent tandem organic light emitting diodes with solution processable mixed hosts charge generating layer

    Talik, N.A.; Yeoh, K.H.; Ng, C.Y.B [Low Dimensional Research Center, Department of Physics, University Malaya, 50603 Kuala Lumpur (Malaysia); ItraMAS Corporation. Sdn. Bhd., 542A-B Mukim 1, Lorong Perusahaan Baru 2, Kawasan Perindustrian, Perai 13600, Penang (Malaysia); Yap, B.K. [Center of Microelectronic and Nanotechnology Engineering (CeMNE), College of Engineering, Universiti Tenaga Nasional, Jln. Uniten-Ikram, 4300 Kajang, Selangor (Malaysia); Woon, K.L., E-mail: ph7klw76@um.edu.my [Low Dimensional Research Center, Department of Physics, University Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-10-15

    A novel solution processable charge generating layer (CGL) that consists of 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HATCN{sub 6})/Poly(N-vinylcarbazole) (PVK): 1,1-bis-(4-bis(4-tolyl)-aminophenyl) cyclohexene (TAPC) for a tandem green phosphorescent organic light emitting diode (PHOLED) is demonstrated. The use of orthogonal solvent to dissolve HATCN{sub 6} and PVK:TAPC is the key to overcome the interface erosion problem for the solution processed CGL. The current efficiency of the 2 wt% TAPC mixed with PVK is the highest at 24.2 cd/A, which is more than three-folds higher than that of the single device at 1000 cd/m{sup 2}. - Highlights: • A solution processable tandem OLED is built using a novel charge generating layer. • HATCN{sub 6} and PVK:TAPC are shown to be effective charge generating layers. • The turn on voltages for tandem devices are almost similar to single unit. • 2 wt% TAPC blended with PVK exhibits three-folds increase in efficiency.

  14. (Nbx, Zr1-x)4AlC3 MAX Phase Solid Solutions: Processing, Mechanical Properties, and Density Functional Theory Calculations.

    Lapauw, Thomas; Tytko, Darius; Vanmeensel, Kim; Huang, Shuigen; Choi, Pyuck-Pa; Raabe, Dierk; Caspi, El'ad N; Ozeri, Offir; To Baben, Moritz; Schneider, Jochen M; Lambrinou, Konstantina; Vleugels, Jozef

    2016-06-06

    The solubility of zirconium (Zr) in the Nb4AlC3 host lattice was investigated by combining the experimental synthesis of (Nbx, Zr1-x)4AlC3 solid solutions with density functional theory calculations. High-purity solid solutions were prepared by reactive hot pressing of NbH0.89, ZrH2, Al, and C starting powder mixtures. The crystal structure of the produced solid solutions was determined using X-ray and neutron diffraction. The limited Zr solubility (maximum of 18.5% of the Nb content in the host lattice) in Nb4AlC3 observed experimentally is consistent with the calculated minimum in the energy of mixing. The lattice parameters and microstructure were evaluated over the entire solubility range, while the chemical composition of (Nb0.85, Zr0.15)4AlC3 was mapped using atom probe tomography. The hardness, Young's modulus, and fracture toughness at room temperature as well as the high-temperature flexural strength and E-modulus of (Nb0.85, Zr0.15)4AlC3 were investigated and compared to those of pure Nb4AlC3. Quite remarkably, an appreciable increase in fracture toughness was observed from 6.6 ± 0.1 MPa/m(1/2) for pure Nb4AlC3 to 10.1 ± 0.3 MPa/m(1/2) for the (Nb0.85, Zr0.15)4AlC3 solid solution.

  15. Evolutions and equilibrium parameters of foam films from individual solutions of Bovine serum albumin, n-dodecyl-β-D-maltoside and from their mixed solutions

    Gerasimova, Anelia Tsvetanova; Angarska, Jana Krumova; Tachev, Krasimir Dimov

    2017-03-01

    The evolutions of thinning of films from individual solutions of BSA, C12G2 and from their mixed solutions with molar ratios 1:1, 1:7.5, 1:50 and 1:100 with pH = 4.9 were recorded by modified (with video camera) interferometric method. Based on them the stages through which the film goes from its formation to the equilibrium state were distinguished. It was shown that: (i) the difference between the kinetic of drainage of films stabilized by high and low molecular surfactants is drastic; (ii) only the change of the pH solution under or above isoelectric point strongly retards the film drainage; (iii) the transition of the kinetic of thinning of films from mixed solutions from a kinetic typical for high molecular substances towards a kinetic for low substances depends on the molar ratio between the components in the solution. From the picture of film corresponding to its equilibrium state the type of film was determined. From the analysis of this picture the equilibrium thickness and contact angle were calculated. It was found that the criterion for Newtonium black films (based on the values of film thickness and contact angle) is not directly applicable for films from protein solutions or mixed solutions with the participation of proteins.

  16. Derivation of an empirical formula for determining water content of mixed uranyl nitrate-thorium nitrate solutions

    Min, Duck Kee; Choi, Byung Il; Ro, Seung Gy; Eom, Tae Yoon; Kim, Zong Goo

    1986-01-01

    Densities of a large number of mixed uranyl nitrate-thorium nitrate solutions were measured with pycnometer. By the least squares analysis of the experimental result, an empirical formula for determining water content of mixed uranyl nitrate-thorium nitrate solutions as functions of uranium concentration, thorium concentration and nitric acid normality is derived; W=1.0-0.3580 C u -0.4538 C Th -0.0307H + where W, C u , C Th , and H + stand for water content(g/cc), uranium concentration (g/cc), thorium concentration(g/cc), and nitric acid normality, respectively. Water contents of the mixed uranyl nitrate-thorium nitrate solutions are calculated by using the empirical formular, and compared with the values calculated by Bouly's equation in which an additional data, solution density, is required. The two results show good agreements within 2.7%. (Author)

  17. MANAGEMENT OF SOLID WASTE GENERATED BY THE INTEGRATED STEELWORKS ACTIVITY AND SOLUTIONS TO REDUCE THE ENVIRONMENTAL IMPACT

    Anişoara CIOCAN

    2010-05-01

    Full Text Available The development of steel industry is subject to solve major problems arising from industry-nature relationship, strictly targeted on pollution control and protection of natural resources and energy. In this paper we discussed about the management of solid waste generated by an integrated steelwork located near a major urban area and the adopted solutions for the reduction of environmental impact. There are summarized technical solutions that are currently applied and were proposed some solutions that can be applied in accordance with the environmental legislations. The new solutions are proposed for integrated management of solid wastes in accordance with: the exact quantification (quantitative, qualitative and the generation sources of emissions and solid wastes; controlled storage; minimization of the wastes and its harmfulness; transformation of the wastes into valuable by-products used directly by the company in a subsequent process, or by external down-stream user.

  18. Analytic Closed-Form Solution of a Mixed Layer Model for Stratocumulus Clouds

    Akyurek, Bengu Ozge

    Stratocumulus clouds play an important role in climate cooling and are hard to predict using global climate and weather forecast models. Thus, previous studies in the literature use observations and numerical simulation tools, such as large-eddy simulation (LES), to solve the governing equations for the evolution of stratocumulus clouds. In contrast to the previous works, this work provides an analytic closed-form solution to the cloud thickness evolution of stratocumulus clouds in a mixed-layer model framework. With a focus on application over coastal lands, the diurnal cycle of cloud thickness and whether or not clouds dissipate are of particular interest. An analytic solution enables the sensitivity analysis of implicitly interdependent variables and extrema analysis of cloud variables that are hard to achieve using numerical solutions. In this work, the sensitivity of inversion height, cloud-base height, and cloud thickness with respect to initial and boundary conditions, such as Bowen ratio, subsidence, surface temperature, and initial inversion height, are studied. A critical initial cloud thickness value that can be dissipated pre- and post-sunrise is provided. Furthermore, an extrema analysis is provided to obtain the minima and maxima of the inversion height and cloud thickness within 24 h. The proposed solution is validated against LES results under the same initial and boundary conditions. Then, the proposed analytic framework is extended to incorporate multiple vertical columns that are coupled by advection through wind flow. This enables a bridge between the micro-scale and the mesoscale relations. The effect of advection on cloud evolution is studied and a sensitivity analysis is provided.

  19. Iron site occupancies in magnetite-ulvospinel solid solution: A new approach using XMCD

    Pearce, C. I.; Henderson, C. M. B.; Telling, N. D.; Pattrick, R. A.D.; Vaughan, D. J.; Charnock, J. M.; Arenholz, E.; Tuna, F.; Coker, V.S.; Laan, G. van der

    2009-06-22

    Ordering of Fe{sup 3+} and Fe{sup 2+} between octahedral (Oh) and tetrahedral (Td) sites in synthetic members of the magnetite (Fe{sub 3}O{sub 4}) - ulvoespinel (Fe{sub 2}TiO{sub 4}) solid-solution series was determined using Fe L{sub 2,3}-edge X-ray magnetic circular dichroism (XMCD) coupled with electron microprobe and chemical analysis, Ti L-edge spectroscopy, Fe K-edge EXAFS and XANES, Fe{sub 57} Moessbauer spectroscopy, and unit cell parameters. Microprobe analysis, cell edges and chemical FeO determinations showed that the bulk compositions of the samples were stoichiometric magnetite-ulvoespinel solid-solutions. Surface sensitive XMCD showed that the surfaces of these oxide minerals were more sensitive to redox conditions and some samples required re-equilibration with suitable solid-solid buffers. Detailed site-occupancy analysis of these samples gave XMCD-Fe{sup 2+}/Fe{sup 3+} ratios very close to stoichiometric values. L{sub 2,3}-edge spectroscopy showed that Ti{sup 4+} was restricted to Oh sites. XMCD results showed that significant Fe{sup 2+} only entered Td when the Ti content was > 0.40 apfu while Fe{sup 2+} in Oh increased from 1 a.p.f.u in magnetite to a maximum of {approx}1.4 apfu in USP45. As the Ti content increased from this point, the steady increase in Fe{sup 2+} in Td sites was clearly observable in the XMCD spectra, concurrent with a slow decrease in Fe{sup 2+} in Oh sites. Calculated magnetic moments showed a steady decrease from magnetite (4.06 {mu}{sub B}) to USP45 (1.5 {mu}{sub B}) and then a slower decrease towards the value for ulvoespinel (0 {mu}{sub B}). Two of the synthesized samples were also partially maghemitized by re-equilibrating with an oxidizing Ni-NiO buffer and XMCD showed that Fe{sup 2+} oxidation only occurred at Oh sites, with concomitant vacancy formation restricted to this site. This study shows the advantage of using XMCD as a direct measurement of Fe oxidation state in these complex magnetic spinels. These results

  20. Research and demonstration results for a new "Double-Solution" technology for municipal solid waste treatment.

    Erping, Li; Haoyun, Chen; Yanyang, Shang; Jun, Pan; Qing, Hu

    2017-11-01

    In this paper, the pyrolysis characteristics of six typical components in municipal solid waste (MSW) were investigated through a TG-FTIR combined technique and it was concluded that the main pyrolysis process of the biomass components (including food residues, sawdust and paper) occurred at 150-600°C. The main volatiles were multi-component gas including H 2 O, CO 2 , and CO. The main pyrolysis temperatures of three artificial products (PP, PVC and leather) was ranged from 200to 500°C. The wavelength of small molecule gases (CH 4 , CO 2 and CO) and the the chemical bonds (CO and CC) were observed in the infrared spectrum Based on the pyrolysis temperature interval and volatile constituent, a new "double-solution" process of pyrolysis and oxygen-enrichment decomposition MSW was designed. To achieve this process, a double-solution project was built for the direct treatment of MSW (10t/d). The complete setup of equipment and analysis of the byproducts has been reported in this paper to indicate the performance of this process. Energy balance and economic benefits were analysed for the process supporting. It was successfully demonstrated that the double-solution process was the environmentally friendly alternative method for MSW treatment in Chinese rural areas. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Theoretical multi-physics approaches to solid-solution strengthening of Al

    Ma, Duancheng; Friak, Martin; Raabe, Dierk; Neugebauer, Joerg [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)

    2009-07-01

    The strengthening of soft metallic materials has a long tradition and is an important metallurgical topic since the time when ancient smiths forged the first swords. Intense materials research revealed a combination of three mechanisms as decisive for solid-solution strengthening phenomena: (i) the size mismatch of components (Mott and Nabarro's parelastic concept), (ii) the elastic modulus mismatch of atoms (Fleischer's dielastic contribution), and (iii) the concentration of solutes (statistical concept of Friedel and Labusch). Combining density functional theory calculations and linear-elasticity theory, the key parameters that are essential for the classical strengthening theories are determined in order to test them and identify their possible validity limits. The strengthening of fcc aluminium is chosen as an example and a series of binary systems Al-X (with X=Ca,Sr,Ir,Li,Mg,Cu) was considered. Comparing our results with those obtained by applying classical theories we find clear deviations. These deviations originate from non-classical lattice distortions due to the size mismatch of solute atoms in their first coordination shells.

  2. Corrosion Performance of Nano-ZrO₂ Modified Coatings in Hot Mixed Acid Solutions.

    Xu, Wenhua; Wang, Zhenyu; Han, En-Hou; Wang, Shuai; Liu, Qian

    2018-06-01

    A nano-ZrO₂ modified coating system was prepared by incorporation of nano-ZrO₂ concentrates into phenolic-epoxy resin. The corrosion performance of the coatings was evaluated in hot mixed acid solution, using electrochemical methods combined with surface characterization, and the effects of nano-ZrO₂ content were specially focused on. The results showed that 1% and 3% nano-ZrO₂ addition enhanced the corrosion resistance of the coatings, while 5% nano-ZrO₂ addition declined it. The coating with 3% nano-ZrO₂ presented the minimum amount of species diffusion, the lowest average roughness (5.94 nm), and the highest C/O ratio (4.55) and coating resistance, and it demonstrated the best corrosion performance among the coating specimens.

  3. Hydrothermal synthesis of a layered-type W-Ti-O mixed metal oxide and its solid acid activity

    Murayama, T.; Nakajima, K.; Hirata, J.; Omata, K.; Hensen, E.J.M.; Ueda, W.

    2017-01-01

    A layered-type W–Ti–O mixed oxide was synthesized by hydrothermal synthesis from an aqueous solution of ammonium metatungstate and titanium sulfate. To avoid the formation of titania, oxalic acid was used as a reductant. Optimized synthesis led to rod-like particles comprised of MO6 (M = W, Ti)

  4. Robustness of third family solutions for hybrid stars against mixed phase effects

    Ayriyan, A.; Bastian, N.-U.; Blaschke, D.; Grigorian, H.; Maslov, K.; Voskresensky, D. N.

    2018-04-01

    We investigate the robustness of third family solutions for hybrid compact stars with a quark matter core that correspond to the occurrence of high-mass twin stars against a softening of the phase transition by means of a construction that mimics the effects of pasta structures in the mixed phase. We consider a class of hybrid equations of state that exploits a relativistic mean-field model for the hadronic as well as for the quark matter phase. We present parametrizations that correspond to branches of high-mass twin star pairs with maximum masses between 2.05 M⊙ and 1.48 M⊙ having radius differences between 3.2 and 1.5 km, respectively. When compared to a Maxwell construction with a fixed value of critical pressure Pc, the effect of the mixed phase construction consists in the occurrence of a region of pressures around Pc belonging to the coexistence of hadronic and quark matter phases between the onset pressure at PH and the end of the transition at PQ. The maximum broadening which would still allow mass-twin compact stars is found to be (PQ-PH)max≈Pc for all parametrizations within the present class of models. At least the heavier of the neutron stars of the binary merger GW170817 could have been a member of the third family of hybrid stars. We present the example of another class of hybrid star equations of state for which the appearance of the third family branch is not as robust against mixed phase effects as that of the present work.

  5. STABILITY OF SYNTHESIZED SILVER NANOPARTICLES IN CITRATE AND MIXED GELATIN/CITRATE SOLUTION

    Jana Kavuličová

    2018-04-01

    Full Text Available The study focuses on an investigation of the influence of both citrate and mixed gelatin/citrate as a reductant and stabilizer on the colloidal stability of silver nanoparticles (AgNPssynthesized by a chemical reduction of Ag+ ions after a short - (7th day - and long - (118th day - term storage. Formed AgNPs were characterized by a UV–vis Spectroscopy, Transmission Electron Microscope (TEM, Dynamic light scattering (DLS and Zeta-potential (ZP. The obtained results revealed that a short-term stability of the synthesized AgNPs was greatly influenced by a citrate stabilizer with the absence of gelatin. Smaller-sized AgNPs (average particle diameter of 3 nm, roughly spherical in a shape, were obtained with a narrow size distribution. The very negative value of the Zeta-potential confirmed a strong stability of the citrate capped AgNPs. However, a surface coating of the AgNPs by a gelatin/citrate stabilizer was found to be a dominant contributor in improving a long-term stability of the AgNPs (average particle diameter of 26 nm. The use of gelatin in mixed stabilizer solution provided the AgNPs with higher monodispersity and a controllable size after both the short and long-term storage.

  6. Mixed and Doped Solid Sorbents for CO2 Capture Applications

    Duan, Yuhua [National Energy Technology Lab. (NETL), Albany, OR (United States)

    2016-06-14

    The objectives of this presentation are to capture CO2 we need materials with optimal performance and low costs; establish a theoretical procedure to identify most potential candidates of CO2 solid sorbents from a large solid material databank; computational synthesis new materials to fit industrial needs; and explore the optimal working conditions for the promised CO2 solid sorbents, especially from room to warm T ranges with optimal energy usage.

  7. Supported liquid membrane based removal of lead(II) and cadmium(II) from mixed feed: Conversion to solid waste by precipitation.

    Bhatluri, Kamal Kumar; Manna, Mriganka Sekhar; Ghoshal, Aloke Kumar; Saha, Prabirkumar

    2015-12-15

    Simultaneous removal of two heavy metals, lead(II) and cadmium(II), from mixed feed using supported liquid membrane (SLM) based technique is investigated in this work. The carrier-solvent combination of "sodium salt of Di-2-ethylhexylphosphoric acid (D2EHPA) (4% w/w) in environmentally benign coconut oil" was immobilized into the pores of solid polymeric polyvinylidene fluoride (PVDF) support. Sodium carbonate (Na2CO3) was used as the stripping agent. Carbonate salts of lead(II) and cadmium(II) were formed in the stripping side interface and they were insoluble in water leading to precipitation inside the stripping solution. The transportation of solute is positively affected due to the precipitation. Lead(II) removal was found to be preferential due to its favorable electronic configuration. The conversion of the liquid waste to the solid one was added advantage for the final removal of hazardous heavy metals. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Two-Phase Flow Modeling of Solid Dissolution in Liquid for Nutrient Mixing Improvement in Algal Raceway Ponds

    Haider Ali

    2018-04-01

    Full Text Available Achieving optimal nutrient concentrations is essential to increasing the biomass productivity of algal raceway ponds. Nutrient mixing or distribution in raceway ponds is significantly affected by hydrodynamic and geometric properties. The nutrient mixing in algal raceway ponds under the influence of hydrodynamic and geometric properties of ponds is yet to be explored. Such a study is required to ensure optimal nutrient concentrations in algal raceway ponds. A novel computational fluid dynamics (CFD model based on the Euler–Euler numerical scheme was developed to investigate nutrient mixing in raceway ponds under the effects of hydrodynamic and geometric properties. Nutrient mixing was investigated by estimating the dissolution of nutrients in raceway pond water. Experimental and CFD results were compared and verified using solid–liquid mass transfer coefficient and nutrient concentrations. Solid–liquid mass transfer coefficient, solid holdup, and nutrient concentrations in algal pond were estimated with the effects of pond aspect ratios, water depths, paddle wheel speeds, and particle sizes of nutrients. From the results, it was found that the proposed CFD model effectively simulated nutrient mixing in raceway ponds. Nutrient mixing increased in narrow and shallow raceway ponds due to effective solid–liquid mass transfer. High paddle wheel speeds increased the dissolution rate of nutrients in raceway ponds.

  9. High strength Ni based composite reinforced by solid solution W(Al) obtained by powder metallurgy

    Zhao Bo; Zhu Changjun; Ma Xianfeng; Zhao Wei; Tang Huaguo; Cai Shuguang; Qiao Zhuhui

    2007-01-01

    The solid-solution-particle reinforced W(Al)-Ni composites were successfully fabricated by using mechanical alloying (MA) and hot-pressing (HP) technique when the content of Ni is between 45 wt% and 55 wt%. Besides, samples of various original component ratio of Al 50 W 50 to Ni have been fabricated, and the corresponding microcomponents and mechanical properties such as microhardness, ultimate tensile strength and elongation were characterized and discussed. The optimum ultimate tensile strength under the experiment conditions is 1868 MPa with elongation of 10.21% and hardness of 6.62 GPa. X-ray diffraction (XRD), FE-SEM and energy dispersive analysis of X-rays (EDS) were given to analysis the components and morphology of the composite bulk specimens

  10. Synthesis, characterization and thermal stability of solid solutions Zr (Y, Fe, MoO2

    Felipe Legorreta-García

    2015-05-01

    Full Text Available The synthesis of Fe3+, Mo4+ and Y3+ fully stabilized zirconia by the nitrate/urea combustion route and thermal stability in air was investigated. The solid solution obtained was characterized by X ray diffraction (XRD, scanning electron microscopy (SEM and used the BET method for determining specific surface. The ceramic powders obtained were calcined at 1473 K in air atmosphere in order to determine their thermal stability. The scanning electron microscopy (SEM results showed a homogeneous grain surface, measuring several tens of micrometers across. The crystallographic study revealed that by this method it was successfully achieved zirconia doped with Fe3+, Mo4+ and Y3+ ions in the zirconia tetragonal monophase, even after calcinations.

  11. Structural parameters of polyethylenes obtained using a palladium catalyst: dilute solution and solid state studies

    Meneghetti, Simoni Plentz; Lutz, Pierre J.; Duval, M.; Kress, Jacky; Lapp, A.

    2001-01-01

    Polyethylenes were obtained using palladium catalyst [(Ar N=C(Me)-C(Me)=N Ar) Pd(CH 2 ) 3 (COOMe)] + BAr' 4 - (VERSIPOL TM ); Ar2,6-i-Pr 2 -C 6 H 3 and Ar'3,5-(CF 3 ) 2 -C 6 H 3 . The combination of dilute solution and solid state characterization of these polyethylenes revealed strong differences between structural parameters of samples prepared under almost identical conditions except ethylene pressure (6, 3 and 1 bar). These differences can be explained by the fact that samples prepared at 6 bar are almost linear, with only a few short branches, whereas those synthesized at 1 bar are highly branched or even hyper branched. (author)

  12. Synthesis, characterization and thermal stability of solid solutions Zr (Y, Fe, Mo)O {sub 2}

    Legorreta-Garcia, F.; Esperanza Hernandez-Cruz, L.; Villanueva-Ibanez, M.; Flores-Gonzalez, M. A.

    2015-10-01

    The synthesis of Fe{sup 3}+, Mo{sup 4+} and Y{sup 3+} fully stabilized zirconia by the nitrate/urea combustion route and thermal stability in air was investigated. The solid solution obtained was characterized by X ray diffraction (XRD), scanning electron microscopy (SEM) and used the BET method for determining specific surface. The ceramic powders obtained were calcined at 1473 K in air atmosphere in order to determine their thermal stability. The scanning electron microscopy (SEM) results showed a homogeneous grain surface, measuring several tens of micrometers across. The crystallographic study revealed that by this method it was successfully achieved zirconia doped with Fe{sup 3+}, Mo{sup 4+} and Y{sup 3+} ions in the zirconia tetragonal monophase, even after calcinations. (Author)

  13. Dielectric properties of lead orthovanadate and orthophosphate and some solid solutions on theirs basis

    Dudnik, E.F.; Sinyakov, E.V.; Gene, V.V.

    1977-01-01

    The dielectric properties of the monocrystals of the ferroelastics Pb 3 (PO 4 ) 2 and Pb 3 (VO 4 ) 2 were investigated. The dependencies of dielectric permeability and double refraction upon temperature were measured. The domain structure and the effect of pressure upon it were studied. The influence of BaO, CaO and Cr 2 O 3 additions upon the properties of Pb 3 (V 4 ) 2 monocrystals and upon the system of monocrystalline solid solutions of Pb 3 (VO 4 ) 2 - Pb 3 (PO 4 ) 2 was also examined. Similar to the case of usual segnetoelectrics, introduction of additions into segnetoelastic crystals was found to lead to spreading of the phase transition

  14. Internal friction and dislocation collective pinning in disordered quenched solid solutions

    D'Anna, G.; Benoit, W.; Vinokur, V. M.

    1997-12-01

    We introduce the collective pinning of dislocations in disordered quenched solid solutions and calculate the macroscopic mechanical response to a small dc or ac applied stress. This work is a generalization of the Granato-Lücke string model, able to describe self-consistently short and long range dislocation motion. Under dc applied stress the long distance dislocation creep has at the microscopic level avalanche features, which result in a macroscopic nonlinear "glassy" velocity-stress characteristic. Under ac conditions the model predicts, in addition to the anelastic internal friction relaxation in the high frequency regime, a linear internal friction background which remains amplitude-independent down to a crossover frequency to a strongly nonlinear internal friction regime.

  15. Synthesis, solid and solution studies of paraquat dichloride calixarene complexes. Molecular modelling

    Garcia S, I.; Ramirez, F. M.

    2010-01-01

    The interaction of the herbicide paraquat dichloride (P Q, substrate) with p-tert-butylcalix arenas (L, receptor) was investigated in both the solution and solid states. The isolated paraquat calixarene complexes were characterised by UV-visible, 1 H NMR, ESI-Ms, Luminescence and IR spectroscopies and elemental analysis. The stoichiometry of complexes 1 and 2 was 1:1 (1 herbicide: 1 calixarene) and both revealed a biexponential luminescence decay with lifetimes depending on the size and the conformational particularity of the calixarenes. Molecular modelling suggested that both calixarenes interact with the herbicide through cation-π interaction. P Q in included in the p-tert butylcalix a rene cavity, a situation favoured by its pinched conformation in polar solvent while it is partially included in the p-tert butylcalix a rene cavity because of its in-out cone conformation. The theoretical results, in particular using Mopac procedures, were in agreement with the experimental findings. (Author)

  16. Synthesis, solid and solution studies of paraquat dichloride calixarene complexes. Molecular modelling

    Garcia S, I.; Ramirez, F. M., E-mail: flor.ramirez@inin.gob.m [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2010-07-01

    The interaction of the herbicide paraquat dichloride (P Q, substrate) with p-tert-butylcalix arenas (L, receptor) was investigated in both the solution and solid states. The isolated paraquat calixarene complexes were characterised by UV-visible, {sup 1}H NMR, ESI-Ms, Luminescence and IR spectroscopies and elemental analysis. The stoichiometry of complexes 1 and 2 was 1:1 (1 herbicide: 1 calixarene) and both revealed a biexponential luminescence decay with lifetimes depending on the size and the conformational particularity of the calixarenes. Molecular modelling suggested that both calixarenes interact with the herbicide through cation-{pi} interaction. P Q in included in the p-tert butylcalix a rene cavity, a situation favoured by its pinched conformation in polar solvent while it is partially included in the p-tert butylcalix a rene cavity because of its in-out cone conformation. The theoretical results, in particular using Mopac procedures, were in agreement with the experimental findings. (Author)

  17. Double crystal X-ray analysis of phosphorus precipitation in supersaturated Si-P solid solutions

    Servidori, M.; Zini, Q.; Dal Monte, C.

    1983-01-01

    The physical nature of the electrically inactive phosphorus in silicon is investigated by double crystal X-ray diffraction measurements. This analysis is performed on laser annealed supersaturated samples, doped by ion implantation up to 5 x 10 21 cm -3 . After isothermal heat treatments, these solid solutions show marked reductions in the electrically active phosphorus concentration. In particular, 850 0 C heatings give rise to a carrier concentration which corresponds to the phosphorus solubility in equilibrium with the inactive dopant. This dopant is characterized by means of lattice strain measurements: they are found consistent with the presence of perfectly coherent cubic SiP precipitates. This result is in agreement with the one obtained in preceeding works by electrical measurements and transmission electron microscopy observations and contradicts the hypothesis that the excess dopant atoms are, at least in part, charged point defects (E-centres). (author)

  18. Measurement test on creep strain rate of uranium-zirconium solid solutions

    Ogata, Takanari; Akabori, Mitsuo; Ogawa, Toru

    1996-11-01

    In order to measure creep strain rate of a small specimen of U-Zr solid solution, authors proposed an estimation method which was based upon the stress relaxation after compression. It was applied to measurement test on creep strain rate of the U-10wt%Zr specimen in the temperature range of 757 to 911degC. It may be concluded that the proposed method is valid, provided that the strain is within the appropriate range and that sufficient amount of the load decrement is observed. The obtained creep rate of U-10wt%Zr alloy indicated significantly smaller value, compared to the experimental data for pure U metal and evaluated data for U-Pu-Zr alloy. However, more careful measurement is desired in future since the present data are thought to be influenced by the precipitations included in the specimen. (author)

  19. Magnetic and electrical properties in BaNiS2-type solid solutions

    Irizawa, Akinori; Yoshimura, Kazuyoshi; Kosuge, Koji

    2000-01-01

    The magnetic and electrical properties are reported in the new solid solutions BaCo 1-x Cu x S 2 and BaNi 1-x Fe x S 2 . Both compounds show spin-glass-like behavior, although the type of spin frustrations is different with each other. BaCo 1-x Cu x S 2 shows a competition type spin-glass behavior with reentrant phenomenon from antiferromagnetic to spin-glass at low temperatures. BaNi 1-x Fe x S 2 shows a dilute type spin-glass behavior together with super-paramagnetic properties. The temperature variation of 57 Fe Moessbauer spectra in BaNi 0.8 Fe 0.2 S 2 is explicable in a framework of cluster-glass. (author)

  20. Variable valence of praseodymium in rare-earth oxide solid solutions

    Kravchinskaya, M.V.; Merezhinskii, K.Y.; Tikhonov, P.A.

    1986-01-01

    Solid solutions of elevated praseodymium oxide content have interesting electrical properties, making them the basis for the manufacture of high-temperature electrically conducting materials. Establishment of the composition-structure-valence state relationships enables control of the material properties. The authors performed investigations using a thermogravimetric apparatus with an electronic microbalance of type EM-5-3M, and using x-ray phase analysis of powders (DRON-1 diffractometer, CuK /SUB alpha/ -radiation). The authors also studied the kinetics of praseodymium oxidation with a thermogravimetric apparatus under isothermal conditions. Evaluation of the results with the equation of Kolmogorov, Erofeev, and Avraam indicates that the process is limited by the chemical oxidation of praseodymium and not by diffusion

  1. Solid-Phase and Oscillating Solution Crystallization Behavior of (+)- and (-)-N-Methylephedrine.

    Tulashie, Samuel Kofi; Polenske, Daniel; Seidel-Morgenstern, Andreas; Lorenz, Heike

    2016-11-01

    This work involves the study of the solid-phase and solution crystallization behavior of the N-methylephedrine enantiomers. A systematic investigation of the melt phase diagram of the enantiomeric N-methylephedrine system was performed considering polymorphism. Two monotropically related modifications of the enantiomer were found. Solubilities and the ternary solubility phase diagrams of N-methylephedrine enantiomers in 2 solvents [isopropanol:water, 1:3 (Vol) and (2R, 3R)-diethyl tartrate] were determined in the temperature ranges between 15°C and 25°C, and 25°C and 40°C, respectively. Preferential nucleation and crystallization experiments at higher supersaturation leading to an unusual oscillatory crystallization behavior as well as a successful preferential crystallization experiment at lower supersaturation are presented and discussed. Copyright © 2016. Published by Elsevier Inc.

  2. Theoretical study on phase coexistence in ferroelectric solid solutions near the tricritical point

    Lu, Xiaoyan, E-mail: luxy@hit.edu.cn, E-mail: dzk@psu.edu; Li, Hui [Key Lab of Structures Dynamic Behavior and Control of the Ministry of Education, School of Civil Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zheng, Limei [Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin 150001 (China); Cao, Wenwu [Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin 150001 (China); Department of Mathematics and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2015-04-07

    Phase coexistence in ferroelectric solid solutions near the tricritical point has been theoretically analyzed by using the Landau-Devonshire theory. Results revealed that different phases having similar potential wells could coexist in a narrow composition range near the tricritical point in the classical Pb(Zr{sub 1−x}Ti{sub x})O{sub 3} system. The potential barrier between potential wells increases with the decrease of temperature. Coexisting phases or different domains of the same phase can produce adaptive strains to maintain atomic coherency at the interfaces or domain walls. Such compatibility strains have influence on the energy potential as well as the stability of relative phases, leading to the appearance of energetically unfavorable monoclinic phases. Those competing and coexisting phases also construct an easy phase transition path with small energy barrier in between, so that very small stimuli can produce large response in compositions near the morphotropic phase boundary, especially near the tricritical point.

  3. Theoretical study on phase coexistence in ferroelectric solid solutions near the tricritical point

    Lu, Xiaoyan; Li, Hui; Zheng, Limei; Cao, Wenwu

    2015-01-01

    Phase coexistence in ferroelectric solid solutions near the tricritical point has been theoretically analyzed by using the Landau-Devonshire theory. Results revealed that different phases having similar potential wells could coexist in a narrow composition range near the tricritical point in the classical Pb(Zr 1−x Ti x )O 3 system. The potential barrier between potential wells increases with the decrease of temperature. Coexisting phases or different domains of the same phase can produce adaptive strains to maintain atomic coherency at the interfaces or domain walls. Such compatibility strains have influence on the energy potential as well as the stability of relative phases, leading to the appearance of energetically unfavorable monoclinic phases. Those competing and coexisting phases also construct an easy phase transition path with small energy barrier in between, so that very small stimuli can produce large response in compositions near the morphotropic phase boundary, especially near the tricritical point

  4. Distribution of rare-earths in solid solution crandalita- goyazita of Sapucaia (Bonito-Para)

    Costa, M.L. da; Melo Costa, W.A. de

    1987-01-01

    The Crandallite are predominant in the lateritic phosphates of Sapucaia, in the form of the solid solution Crandallite (Cn)- Goyazite (Gz)-Florencite (Fl). The Crandallite-Goyazite is predominant, where the maximum proportion of Florencite is Cn 60 Cz 34.8 Fl 5.2 - This proportion of Florencite is relatively high for laterites, and for this case having up to 1,374% weight of TR 2 O 3 in the total sample. The light rare elements are predominant over the heavy ores, and are illustrated in the distribution curve normalized for the chondrites. This curve is partially comparable with the curve for Apatite presents slight negative anomaly for the element Europium, and slight positive anomaly for The elements Thulium. The geochemical caracteristics for the rare earths in this group allow the prediction for the original rock for the laterites. (author) [pt

  5. Paramagnetic properties of the (U1-xTbx)Co2Ge2 solid solutions

    Kuznietz, Moshe; Pinto, Haim; Ettedgui, Hanania

    1995-01-01

    Polycrystalline (U 1-x Tb x )Co 2 Ge 2 solid solutions have the ThCr 2 Si 2 -type crystal structure and order antiferromagnetically. AC-susceptibility at 80-295 K yields paramagnetic Curie temperatures θ=-350±50, -15±5, -50±15, -12±5, and -80±5 K, and effective magnetic moments μ eff =4.5, 5.9, 7.3, 8.5, and 12.0 (±0.5)μ B , for samples with x=0, 0.25, 0.50, 0.75 and 1, respectively. The high μ eff values are related to occurrence of paramagnetic moments on U, Tb and Co, of which only U and Tb moments order magnetically. ((orig.))

  6. Flow-Solution-Liquid-Solid Growth of Semiconductor Nanowires: A Novel Approach for Controlled Synthesis

    Hollingsworth, Jennifer A. [Los Alamos National Laboratory; Palaniappan, Kumaranand [Los Alamos National Laboratory; Laocharoensuk, Rawiwan [National Science and Technology Center, Thailand; Smith, Nickolaus A. [Los Alamos National Laboratory; Dickerson, Robert M. [Los Alamos National Laboratory; Casson, Joanna L. [Los Alamos National Laboratory; Baldwin, Jon K. [Los Alamos National Laboratory

    2012-06-07

    Semiconductor nanowires (SC-NWs) have potential applications in diverse technologies from nanoelectronics and photonics to energy harvesting and storage due to their quantum-confined opto-electronic properties coupled with their highly anisotropic shape. Here, we explore new approaches to an important solution-based growth method known as solution-liquid-solid (SLS) growth. In SLS, molecular precursors are reacted in the presence of low-melting metal nanoparticles that serve as molten fluxes to catalyze the growth of the SC-NWs. The mechanism of growth is assumed to be similar to that of vapor-liquid-solid (VLS) growth, with the clear distinctions of being conducted in solution in the presence of coordinating ligands and at relatively lower temperatures (<300 C). The resultant SC-NWs are soluble in common organic solvents and solution processable, offering advantages such as simplified processing, scale-up, ultra-small diameters for quantum-confinement effects, and flexible choice of materials from group III-V to groups II-VI, IV-VI, as well as truly ternary I-III-VI semiconductors as we recently demonstrates. Despite these advantages of SLS growth, VLS offers several clear opportunities not allowed by conventional SLS. Namely, VLS allows sequential addition of precursors for facile synthesis of complex axial heterostructures. In addition, growth proceeds relatively slowly compared to SLS, allowing clear assessments of growth kinetics. In order to retain the materials and processing flexibility afforded by SLS, but add the elements of controlled growth afforded by VLS, we transformed SLS into a flow based method by adapting it to synthesis in a microfluidic system. By this new method - so-called 'flow-SLS' (FSLS) - we have now demonstrated unprecedented fabrication of multi-segmented SC-NWs, e.g., 8-segmented CdSe/ZnSe defined by either compositionally abrupt or alloyed interfaces as a function of growth conditions. In addition, we have studied growth

  7. Investigating the effect of compression on solute transport through degrading municipal solid waste

    Woodman, N.D., E-mail: n.d.woodman@soton.ac.uk; Rees-White, T.C.; Stringfellow, A.M.; Beaven, R.P.; Hudson, A.P.

    2014-11-15

    Highlights: • The influence of compression on MSW flushing was evaluated using 13 tracer tests. • Compression has little effect on solute diffusion times in MSW. • Lithium tracer was conservative in non-degrading waste but not in degrading waste. • Bromide tracer was conservative, but deuterium was not. - Abstract: The effect of applied compression on the nature of liquid flow and hence the movement of contaminants within municipal solid waste was examined by means of thirteen tracer tests conducted on five separate waste samples. The conservative nature of bromide, lithium and deuterium tracers was evaluated and linked to the presence of degradation in the sample. Lithium and deuterium tracers were non-conservative in the presence of degradation, whereas the bromide remained effectively conservative under all conditions. Solute diffusion times into and out of less mobile blocks of waste were compared for each test under the assumption of dominantly dual-porosity flow. Despite the fact that hydraulic conductivity changed strongly with applied stress, the block diffusion times were found to be much less sensitive to compression. A simple conceptual model, whereby flow is dominated by sub-parallel low permeability obstructions which define predominantly horizontally aligned less mobile zones, is able to explain this result. Compression tends to narrow the gap between the obstructions, but not significantly alter the horizontal length scale. Irrespective of knowledge of the true flow pattern, these results show that simple models of solute flushing from landfill which do not include depth dependent changes in solute transport parameters are justified.

  8. Hammerhead ribozyme activity and oligonucleotide duplex stability in mixed solutions of water and organic compounds

    Shu-ichi Nakano

    2014-01-01

    Full Text Available Nucleic acids are useful for biomedical targeting and sensing applications in which the molecular environment is different from that of a dilute aqueous solution. In this study, the influence of various types of mixed solutions of water and water-soluble organic compounds on RNA was investigated by measuring the catalytic activity of the hammerhead ribozyme and the thermodynamic stability of an oligonucleotide duplex. The compounds with a net neutral charge, such as poly(ethylene glycol, small primary alcohols, amide compounds, and aprotic solvent molecules, added at high concentrations changed the ribozyme-catalyzed RNA cleavage rate, with the magnitude of the effect dependent on the NaCl concentration. These compounds also changed the thermodynamic stability of RNA base pairs of an oligonucleotide duplex and its dependence on the NaCl concentration. Specific interactions with RNA molecules and reduced water activity could account for the inhibiting effects on the ribozyme catalysis and destabilizing effects on the duplex stability. The salt concentration dependence data correlated with the dielectric constant, but not with water activity, viscosity, and the size of organic compounds. This observation suggests the significance of the dielectric constant effects on the RNA reactions under molecular crowding conditions created by organic compounds.

  9. Thermosetting microemulsions and mixed micellar solutions as drug delivery systems for periodontal anesthesia.

    Scherlund, M; Malmsten, M; Holmqvist, P; Brodin, A

    2000-01-20

    In the present study, thermosetting microemulsions and mixed micellar solutions were investigated as drug delivery systems for anesthetizing the periodontal pocket. The structure of the systems, consisting of the active ingredients lidocaine and prilocaine, as well as two block copolymers (Lutrol F127 and Lutrol F68), was investigated by NMR spectroscopy and photon correlation spectroscopy (PCS). The results obtained for dilute (1-3% w/w) solutions show discrete micelles with a diameter of 20-30 nm and a critical micellization temperature of 25-35 degrees C. Gel permeation chromatography (GPC) was used to study the distribution of the active ingredients, and indicates a preferential solubilization of the active components in micelles over unimers. Analogous to the Lutrol F127 single component system these formulations display an abrupt gelation on increasing temperature. The gelation temperature was found to depend on both the drug ionization and concentration. These systems have several advantages over emulsion-based formulations including good stability, ease of preparation, increased drug release rate, and improved handling due to the transparency of the formulations.

  10. Prediction of Intrinsic Cesium Desorption from Na-Smectite in Mixed Cation Solutions.

    Fukushi, Keisuke; Fukiage, Tomo

    2015-09-01

    Quantitative understanding of the stability of sorbed radionuclides in smectite is necessary to assess the performance of engineering barriers used for nuclear waste disposal. Our previous study demonstrated that the spatial organization of the smectite platelets triggered by the divalent cations led to the apparent fixation of intrinsic Cs in smectite, because some Cs is retained inside the formed tactoids. Natural water is usually a mixture of Na(+) and divalent cations (Ca(2+) and Mg(2+)). This study therefore investigated the desorption behavior of intrinsic Cs in Na-smecite in mixed Na(+)-divalent cation solutions under widely various cation concentrations using batch experiments, grain size measurements, and cation exchange modeling (CEM). Results show that increased Na(+) concentrations facilitate Cs desorption because Na(+) serves as the dispersion agent. A linear relation was obtained between the logarithm of the Na(+) fraction and the accessible Cs fraction in smectite. That relation enables the prediction of accessible Cs fraction as a function of solution cationic compositions. The corrected CEM considering the effects of the spatial organization suggests that the stability of intrinsic Cs in the smectite is governed by the Na(+) concentration, and suggests that it is almost independent of the concentrations of divalent cations in natural water.

  11. Dissolution of britholites and monazite / brabantite solid solutions doped with actinides

    Du Fou De Kerdaniel, E.

    2007-12-01

    In the field of the radwaste storage in underground repository, several matrices were considered as promising ceramics for the specific immobilization of actinides. Two of them, britholites and monazite/ brabantite solid solution, have been considered during this work. In order to examine the dissolution mechanisms occurring at the solid liquid interface, several leaching experiments have been conducted on (Ln III PO 4 ), brabantite (Ca II An IV (PO 4 ) 2 : An = Th, U) and britholites (Ca 9 Nd 0.5 An 0.5 IV (PO 4 ) 4.5 (SiO 4 ) 1.5 F 2 : An = Th, U). Some steady experiments, performed in under saturation conditions for various pH and temperature conditions allowed to evaluate the long term behaviour of such matrices through their chemical durability. On the contrary, the thermodynamic equilibria were examined through the leaching experiments performed near the saturation conditions. By the way, various secondary phases, precipitated onto the surface of altered samples have been identified and characterized. Among them, the (Nd, Ca, Th) - rhabdophane, novelly prepared in over- saturation experiments for a thorium weight loading lower than 11 % appeared to be metastable. Indeed, it turns into TPHPH (Th 2 (PO 4 ) 2 HPO 4 .H 2 O) and Nd - rhabdophane (NdPO 4 .1/2H 2 O) when increasing leaching time. (author)

  12. Solid solution barium–strontium chlorides with tunable ammonia desorption properties and superior storage capacity

    Bialy, Agata [Amminex Emissions Technology A/S, Gladsaxevej 363, 2860 Soeborg (Denmark); Jensen, Peter B. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Center for Atomic-scale Materials Design, Department of Physics, Technical University of Denmark, Fysikvej 311, DK-2800 Kgs. Lyngby (Denmark); Blanchard, Didier [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Vegge, Tejs, E-mail: teve@dtu.dk [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Quaade, Ulrich J., E-mail: ujq@amminex.com [Amminex Emissions Technology A/S, Gladsaxevej 363, 2860 Soeborg (Denmark)

    2015-01-15

    Metal halide ammines are very attractive materials for ammonia absorption and storage—applications where the practically accessible or usable gravimetric and volumetric storage densities are of critical importance. Here we present, that by combining advanced computational materials prediction with spray drying and in situ thermogravimetric and structural characterization, we synthesize a range of new, stable barium-strontium chloride solid solutions with superior ammonia storage densities. By tuning the barium/strontium ratio, different crystallographic phases and compositions can be obtained with different ammonia ab- and desorption properties. In particular it is shown, that in the molar range of 35–50% barium and 65–50% strontium, stable materials can be produced with a practically usable ammonia density (both volumetric and gravimetric) that is higher than any of the pure metal halides, and with a practically accessible volumetric ammonia densities in excess of 99% of liquid ammonia. - Graphical abstract: Thermal desorption curves of ammonia from Ba{sub x}Sr{sub (1−x)}Cl{sub 2} mixtures with x equal to 0.125, 0.25 and 0.5 and atomic structure of Sr(NH{sub 3}){sub 8}Cl{sub 2}. - Highlights: • Solid solutions of strontium and barium chloride were synthesized by spray drying. • Adjusting molar ratios led to different crystallographic phases and compositions. • Different molar ratios led to different ammonia ab-/desorption properties. • 35–50 mol% BaCl{sub 2} in SrCl{sub 2} yields higher ammonia density than any other metal halide. • DFT calculations can be used to predict properties of the mixtures.

  13. Effect of Heat Treatment on the Lithium Ion Conduction of the LiBH4–LiI Solid Solution

    Sveinbjörnsson, Dadi Þorsteinn; Mýrdal, Jón Steinar Garðarsson; Blanchard, Didier

    2013-01-01

    The LiBH4–LiI solid solution is a good Li+ conductor and a promising crystalline electrolyte for all-solid-state lithium based batteries. The focus of the present work is on the effect of heat treatment on the Li+ conduction. Solid solutions with a LiI content of 6.25–50% were synthesized by high...

  14. Characterization of the solid low level mixed waste inventory for the solid waste thermal treatment activity - III

    Place, B.G., Westinghouse Hanford

    1996-09-24

    The existing thermally treatable, radioactive mixed waste inventory is characterized to support implementation of the commercial, 1214 thermal treatment contract. The existing thermally treatable waste inventory has been identified using a decision matrix developed by Josephson et al. (1996). Similar to earlier waste characterization reports (Place 1993 and 1994), hazardous materials, radionuclides, physical properties, and waste container data are statistically analyzed. In addition, the waste inventory data is analyzed to correlate waste constituent data that are important to the implementation of the commercial thermal treatment contract for obtaining permits and for process design. The specific waste parameters, which were analyzed, include the following: ``dose equivalent`` curie content, polychlorinated biphenyl (PCB) content, identification of containers with PA-related mobile radionuclides (14C, 12 79Se, 99Tc, and U isotopes), tritium content, debris and non-debris content, container free liquid content, fissile isotope content, identification of dangerous waste codes, asbestos containers, high mercury containers, beryllium dust containers, lead containers, overall waste quantities, analysis of container types, and an estimate of the waste compositional split based on the thermal treatment contractor`s proposed process. A qualitative description of the thermally treatable mixed waste inventory is also provided.

  15. Acceleration of Lateral Equilibration in Mixed Lipid Bilayers Using Replica Exchange with Solute Tempering.

    Huang, Kun; García, Angel E

    2014-10-14

    The lateral heterogeneity of cellular membranes plays an important role in many biological functions such as signaling and regulating membrane proteins. This heterogeneity can result from preferential interactions between membrane components or interactions with membrane proteins. One major difficulty in molecular dynamics simulations aimed at studying the membrane heterogeneity is that lipids diffuse slowly and collectively in bilayers, and therefore, it is difficult to reach equilibrium in lateral organization in bilayer mixtures. Here, we propose the use of the replica exchange with solute tempering (REST) approach to accelerate lateral relaxation in heterogeneous bilayers. REST is based on the replica exchange method but tempers only the solute, leaving the temperature of the solvent fixed. Since the number of replicas in REST scales approximately only with the degrees of freedom in the solute, REST enables us to enhance the configuration sampling of lipid bilayers with fewer replicas, in comparison with the temperature replica exchange molecular dynamics simulation (T-REMD) where the number of replicas scales with the degrees of freedom of the entire system. We apply the REST method to a cholesterol and 1,2-dipalmitoyl- sn -glycero-3-phosphocholine (DPPC) bilayer mixture and find that the lateral distribution functions of all molecular pair types converge much faster than in the standard MD simulation. The relative diffusion rate between molecules in REST is, on average, an order of magnitude faster than in the standard MD simulation. Although REST was initially proposed to study protein folding and its efficiency in protein folding is still under debate, we find a unique application of REST to accelerate lateral equilibration in mixed lipid membranes and suggest a promising way to probe membrane lateral heterogeneity through molecular dynamics simulation.

  16. High-temperature, Knudsen cell-mass spectroscopic studies on lanthanum oxide/uranium dioxide solid solutions

    Sunder, S.; McEachern, R.; LeBlanc, J.C.

    2001-01-01

    Knudsen cell-mass spectroscopic experiments were carried out with lanthanum oxide/uranium oxide solid solutions (1%, 2% and 5% (metal at.% basis)) to assess the volatilization characteristics of rare earths present in irradiated nuclear fuel. The oxidation state of each sample used was conditioned to the 'uranium dioxide stage' by heating in the Knudsen cell under an atmosphere of 10% CO 2 in CO. The mass spectra were analyzed to obtain the vapour pressures of the lanthanum and uranium species. It was found that the vapour pressure of lanthanum oxide follows Henry's law, i.e., its value is directly proportional to its concentration in the solid phase. Also, the vapour pressure of lanthanum oxide over the solid solution, after correction for its concentration in the solid phase, is similar to that of uranium dioxide. (authors)

  17. Smooth and robust solutions for Dirichlet boundary control of fluid-solid conjugate heat transfer problems

    Yan, Yan

    2015-01-01

    We study a new optimization scheme that generates smooth and robust solutions for Dirichlet velocity boundary control (DVBC) of conjugate heat transfer (CHT) processes. The solutions to the DVBC of the incompressible Navier-Stokes equations are typically nonsmooth, due to the regularity degradation of the boundary stress in the adjoint Navier-Stokes equations. This nonsmoothness is inherited by the solutions to the DVBC of CHT processes, since the CHT process couples the Navier-Stokes equations of fluid motion with the convection-diffusion equations of fluid-solid thermal interaction. Our objective in the CHT boundary control problem is to select optimally the fluid inflow profile that minimizes an objective function that involves the sum of the mismatch between the temperature distribution in the fluid system and a prescribed temperature profile and the cost of the control.Our strategy to resolve the nonsmoothness of the boundary control solution is based on two features, namely, the objective function with a regularization term on the gradient of the control profile on both the continuous and the discrete levels, and the optimization scheme with either explicit or implicit smoothing effects, such as the smoothed Steepest Descent and the Limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) methods. Our strategy to achieve the robustness of the solution process is based on combining the smoothed optimization scheme with the numerical continuation technique on the regularization parameters in the objective function. In the section of numerical studies, we present two suites of experiments. In the first one, we demonstrate the feasibility and effectiveness of our numerical schemes in recovering the boundary control profile of the standard case of a Poiseuille flow. In the second one, we illustrate the robustness of our optimization schemes via solving more challenging DVBC problems for both the channel flow and the flow past a square cylinder, which use initial

  18. 3He release characteristics of metal tritides and scandium--tritium solid solutions

    Perkins, W.G.; Kass, W.J.; Beavis, L.C.

    1975-01-01

    Tritides of such metals as scandium, titanium, and erbium are useful materials for determining the effects of helium accumulation in metallic solids, for example, CTR first wall materials. Such effects include lattice strain and gross deformation, as reported elsewhere, which are related to 3 He retention and ultimate release. Long term gas release studies have indicated that, during the early life of a metal ditritide, a large fraction of the 3 He is retained in the solid. At more advanced ages (2 to 4 years, depending on the parent metal), the 3 He release rate becomes comparable to the generation rate. Statistical analysis of the data indicates that the acceleration in 3 He release rate depends on accumulated 3 He concentration rather than strictly on age. 3 He outgassing results are presented for thin films of ScT 2 , TiT 2 , and ErT 2 , and the critical 3 He concentrations are discussed in terms of a percolation model. Phase transformations which occur on tritide formation cast some doubt on the validity of extrapolating results obtained for metal tritides to predictions regarding the accumulation of helium in metals. Scandium is unique among the early transition and rare-earth metals in that the metal exhibits a very high room temperature tritium solubility (T/Sc = 0.4) with no phase transformation. Indeed, even the lattice parameters of the hcp scandium lattice are only minimally changed by tritium solution, and we have succeeded in obtaining single crystal ScT 0 . 3 samples in two crystallographic orientations. Using a very sensitive technique, we have measured 3 He emission from both these samples, as well as from fine-grained thin film scandium-tritium solid solution samples (ScT 0 . 3 - 0 . 4 ). The fine-grained film samples release 3 He at 2 to 3 percent of the generation rate, while the emission rate from the single-crystal samples is approximately 0.05 percent of the generation rate, indicating a strong grain size effect

  19. Crystalline structure and electrical properties of solid solutions YNixMn1-xO3

    Moure, C.

    1999-12-01

    Full Text Available Solid solutions belonging to the Mn-rich region of the YNiXMn1-XO3 system have been studied. The powders were prepared by solid state reaction between the corresponding oxides. Sintered ceramics were obtained by firing at 1325-1350ºC. The incorporation of 20 atomic % Ni2+ to the Yttrium manganite induces the formation of a perovskite phase, with orthorhombic symmetry. Increase of the Ni amount leads to an increase of the orthorhombicity factor b/a, up to an amount of 50 atomic % Ni2+. Above this Ni amount, a biphasic system has been observed, with the presence of unreacted Y2O3. DC electrical conductivity measurements have shown semiconducting behaviour for all the solid solutions with perovskite-type structure. The room temperature conductivity increases with Ni until ~33 atomic % Ni, and then decreases. The 50/50 Ni/Mn composition has different values of conductivity and activation energy against those corresponding to samples with lower values of that ionic ratio. Small polaron hopping mechanism controls the conductivity in these ceramics. Results are discussed as a function of the Mn3+/Mn4+ ratio for each composition.Se han estudiado las soluciones sólidas correspondientes a la región rica en Mn del sistema YNiXMn1-XO3, entre 0 y 50 atomic % Ni. Los compuestos fueron preparados por reacción en estado sólido de los óxidos correspondientes. Se sinterizaron materiales cerámicos a 1325-1350ºC. Con cantidades de 20 atomic % Ni se produce la formación de una fase con estructura de perovskita, y simetría ortorrómbica. La distorsión ortorrómbica crece con el contenido de Ni. Por encima de 50 atomic % Ni, aparece Y2O3 sin reaccionar. Las soluciones sólidas muestran semiconducción con valores de σ que aumentan con el contenido de Ni hasta ~33 atomic %, para luego decrecer, hasta x=0.5. La composición 50/50 Ni/Mn muestra un comportamiento eléctrico algo diferente. Se discuten los resultados en función de la razón Mn3+/Mn4+ para cada

  20. Synthesis and photocatalytic degradation study of methylene blue dye under visible light irradiation by Fe1-xBixVO4 solid solutions (0 ≤ x ≤ 1.0)

    Bera, Ganesh; Reddy, V. R.; Mal, Priyanath; Das, Pradip; Turpu, G. R.

    2018-05-01

    The novel hetero-structures Fe1-xBixVO4 solid solutions (0 ≤ x ≤ 1.0) with the two dissimilar end member of FeVO4 - BiVO4, were successfully synthesized by the standard solid state reaction method. The structural and chemical properties of as prepared photo-catalyst samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and UV-visible absorption spectroscopy techniques. It is confirmed from the results of XRD, Raman and FT-IR that FeVO4 and BiVO4 are in triclinic (space group P-1 (2)) and monoclinic (space group I2/b (15)) phases respectively. The Bi incorporation into Fe site of FeVO4 emerges as hetero-structures of both the end members of the solid solutions. In addition, the photocatalytic activity in the degradation of methylene blue (MB) dye under visible light irradiation was carried out through UV-visible spectroscopy measurement of photo-catalysts FeVO4, BiVO4 and mixed phases of both photo-catalyst. The results indicate that under visible light irradiation the photocatalytic activity of mixed phases were very effective and higher than the both single phases of the solid solutions. The composition x= 0.25 exhibits an excellent photocatalytic property for the degradation of MB solution under visible light irradiation rather than other.

  1. Mixing of process heels, process solutions, and recycle streams: Results of the small-scale radioactive tests

    Lumetta, G.J.; Bramson, J.P.; Farmer III, O.T.; Greenwood, L.R.; Hoopes, F.V.; Mann, M.A.; Steele, M.J.; Steele, R.T.; Swoboda, R.G.; Urie, M.W.

    2000-01-01

    Various recycle streams will be combined with the low-activity waste (LAW) or the high-level waste (HLW) feed solutions during the processing of the Hanford tank wastes by BNFL, Inc. In addition, the LAW and HLW feed solutions will also be mixed with heels present in the processing equipment. This report describes the results of a test conducted by Battelle to assess the effects of mixing specific process streams. Observations were made regarding adverse reactions (mainly precipitation) and effects on the Tc oxidation state (as indicated by K d measurements with SuperLigreg s ign 639). The work was conducted according to test plan BNFL-TP-29953-023, Rev. 0, Small Scale Mixing of Process Heels, Solutions, and Recycle Streams. The test went according to plan, with only minor deviations from the test plan. The deviations from the test plan are discussed in the experimental section

  2. Stability of Almost Periodic Solution for a General Class of Discontinuous Neural Networks with Mixed Time-Varying Delays

    Yingwei Li

    2013-01-01

    Full Text Available The global exponential stability issues are considered for almost periodic solution of the neural networks with mixed time-varying delays and discontinuous neuron activations. Some sufficient conditions for the existence, uniqueness, and global exponential stability of almost periodic solution are achieved in terms of certain linear matrix inequalities (LMIs, by applying differential inclusions theory, matrix inequality analysis technique, and generalized Lyapunov functional approach. In addition, the existence and asymptotically almost periodic behavior of the solution of the neural networks are also investigated under the framework of the solution in the sense of Filippov. Two simulation examples are given to illustrate the validity of the theoretical results.

  3. High-temperature x-ray diffraction study of HfTiO4-HfO2 solid solutions

    Carpenter, D.A.

    1975-01-01

    High-temperature x-ray diffraction techniques were used to determine the axial thermal expansion curves of HfTiO 4 -HfO 2 solid solutions as a function of composition. Data show increasing anisotropy with increasing HfO 2 content. An orthorhombic-to-monoclinic phase transformation was detected near room temperature for compositions near the high HfO 2 end of the orthorhombic phase field and for compositions within the two-phase region (HfTiO 4 solid solution plus HfO 2 solid solution). An orthorhombic-to-cubic phase transformation is indicated by data from oxygen-deficient materials at greater than 1873 0 K. (U.S.)

  4. XAFS spectroscopic study of uranyl coordination in solids and aqueous solution

    Thompson, H.A.; Brown, G.E. Jr.; Parks, G.A.

    1997-01-01

    To evaluate the ability of X-ray absorption fine structure (XAFS) spectroscopy to elucidate the coordination environment of U 6+ at the solid-water interface, we conducted an in-depth analysis of experimental XAFS data from U 6+ solid and solution model compounds. Using the ab initio XAFS code FEFF6, we calculated phase-shift and amplitude functions for fitting experimental data. The code FEFF6 does a good job of reproducing experimental data and is particularly valuable for providing phase-shift and amplitude functions for neighboring atoms whose spectral contributions are difficult to isolate from experimental data because of overlap of Fourier transform features. In solid-phase model compounds at ambient temperature, we were able to fit spectral contributions from axial O (1.8 Angstrom), equatorial O (2.2-2.5 Angstrom), N (2.9 Angstrom), C (2.9 Angstrom), Si (3.2 Angstrom), P (3.6 Angstrom), distant 0 (4.3 Angstrom), and U (4.0, 4.3, 4.9, and 5.2 Angstrom) atoms. Contributions from N, C, Si, P, distant O, and distant U (4.9 and 5.2 Angstrom) are weak and therefore might go undetected in a sample of unknown composition. Lowering the temperature to 10 K extends detection of U neighbors to 7.0 Angstrom. The ability to detect these atoms suggests that XAFS might be capable of discerning inner-sphere U sorption at solid aluminosilicate-water interfaces. XAFS should definitely detect multinuclear U complexes and precipitates. Multiple-scattering paths are minor contributors to uranyl XAFS beyond k = 3 Angstrom -1 . Allowing shell-dependent disorder parameters (σ 2 ) to vary, we observed narrow ranges of σ 2 values for similar shells of neighboring atoms. Knowledge of these ranges is necessary to constrain the fit of XAFS spectra for unknowns. Finally, we found that structures reported in the literature for uranyl diacetate and rutherfordine are not completely correct. 50 refs., 6 figs., 2 tabs

  5. Dispersion of dielectric permittivity and magnetic properties of solid solution PZT–PFT

    Skulski Ryszard

    2015-09-01

    Full Text Available In this paper we present the results of investigations into ceramic samples of solid solution (1-x(PbZr0.53Ti0.47O3- x(PbFe0.5Ta0.503 (i.e. (1-xPZT-xPFT with x = 0.25, 0.35 and 0.45. We try to find the relation between the character of dielectric dispersion at various temperatures and the composition of this solution. We also describe the magnetic properties of investigated samples. With increasing the content of PFT also mass magnetization and mass susceptibility increase (i.e. magnetic properties are more pronounced at every temperature. The temperature dependences of mass magnetization and re­ciprocal of mass susceptibility have similar runs for all the compositions. However, our magnetic investigations exhibit weak antiferromagnetic ordering instead of the ferromagnetic one at room temperature. We can also say that up to room tempera­ture any magnetic phase transition has not occurred. It may be a result of the conditions of the technological process during producing our PZT-PFT ceramics.

  6. Evolution of microstructures in nickel solid solution fatigued at high temperature: occurence of an intragranular cavitation

    Arnaud, B.

    1986-06-01

    We studied by T.E.M. the microstructures appearing in Nickel solid solution fatigued in push-pull between 0.4 Tm and 0.6 Tm (Tm=melting temperature), the maximum amplitude of stress was imposed: +- 100 MPa, three frequencies were used: 1.25 Hz, 2.5 Hz and 10 Hz. In Ni 6% at Ge the structure of dislocations evolves continuously with the number of cycles: homogeneous distribution of dislocations, cell structure, then development of sub-grains 5 times as big as the cell; these sub-grains are not stable, they break up into cells. This succession of structures suggests a cyclic evolution. The cavities appear for number of cycles greater than a threshold number depending on the temperature and the frequency. The cavities are not distributed uniformly, they are located in zone. According to the conditions of sollicitation, the shape (equiaxe of small stick) and the distribution (uniform, in band, in crown) of the cavities fluctuate. This cavitation exists equally in other materials (Ni 4% at Si, Ni). This intra-granular cavitation has been observed in the same domain of temperatures as the domain of swelling in the same material under bombardment with ions Ni + . Due to this similitude we searched for a segregation of solute (like the induced precipitation by irradiation) but this phenomenon did not occur with our experimental conditions [fr

  7. A new variable temperature solution-solid interface scanning tunneling microscope.

    Jahanbekam, Abdolreza; Mazur, Ursula; Hipps, K W

    2014-10-01

    We present a new solution-solid (SS) interface scanning tunneling microscope design that enables imaging at high temperatures with low thermal drift and with volatile solvents. In this new design, distinct from the conventional designs, the entire microscope is surrounded in a controlled-temperature and controlled-atmosphere chamber. This allows users to take measurements at high temperatures while minimizing thermal drift. By incorporating an open solution reservoir in the chamber, solvent evaporation from the sample is minimized; allowing users to use volatile solvents for temperature dependent studies at high temperatures. The new design enables the user to image at the SS interface with some volatile solvents for long periods of time (>24 h). An increase in the nonlinearity of the piezoelectric scanner in the lateral direction as a function of temperature is addressed. A temperature dependent study of cobalt(II) octaethylporphyrin (CoOEP) at the toluene/Au(111) interface has been performed with this instrument. It is demonstrated that the lattice parameters remain constant within experimental error from 24 °C to 75 °C. Similar quality images were obtained over the entire temperature range. We report the unit cell of CoOEP at the toluene/Au(111) interface (based on two molecules per unit cell) to be A = (1.36 ± 0.04) nm, B = (2.51 ± 0.04) nm, and α = 97° ± 2°.

  8. Fabrication and Performance of All-Solid-State Chloride Sensors in Synthetic Concrete Pore Solutions

    Hongwei Deng

    2010-11-01

    Full Text Available One type of all-solid-state chloride sensor was fabricated using a MnO2 electrode and a Ag/AgCl electrode. The potentiometric response of the sensor to chloride in synthetic concrete pore solutions was systematically studied, and the polarization performance was also evaluated. The results show a good linear relationship between the potential reading of the sensor and the logarithm of chloride activity (concentration ranges from 0.05 to 5.0 M, and the potential value remains stable with increasing immersion time. The existence of K+, Ca2+, Na+ and SO42− ions have little influence on the potentiometric response of the sensor to chloride, but the pH has a significant influence on the potential value of the sensor at low chloride concentration. The potential reading of the sensor increases linearly with the solution temperature over the range from 5 to 45 °C. Meanwhile, an excellent polarization behavior is proven by galvanostatic and potentiodynamic tests. All of the results reveal that the developed sensor has a great potential for monitoring chloride ions in concrete environments.

  9. Fabrication and performance of all-solid-state chloride sensors in synthetic concrete pore solutions.

    Gao, Xiaojian; Zhang, Jian; Yang, Yingzi; Deng, Hongwei

    2010-01-01

    One type of all-solid-state chloride sensor was fabricated using a MnO(2) electrode and a Ag/AgCl electrode. The potentiometric response of the sensor to chloride in synthetic concrete pore solutions was systematically studied, and the polarization performance was also evaluated. The results show a good linear relationship between the potential reading of the sensor and the logarithm of chloride activity (concentration ranges from 0.05 to 5.0 M), and the potential value remains stable with increasing immersion time. The existence of K(+), Ca(2+), Na(+) and SO(4) (2-) ions have little influence on the potentiometric response of the sensor to chloride, but the pH has a significant influence on the potential value of the sensor at low chloride concentration. The potential reading of the sensor increases linearly with the solution temperature over the range from 5 to 45 °C. Meanwhile, an excellent polarization behavior is proven by galvanostatic and potentiodynamic tests. All of the results reveal that the developed sensor has a great potential for monitoring chloride ions in concrete environments.

  10. Mixed Valence in Conjugated Anion Radicals. Solution and Solid State Studies

    1991-05-24

    voltammetry was performed using a BAS-100 electrochemical analyzer. Bulk electrolyses were performed with a Princeton Applied Research (PAR) model 173...extracted with several small portions of CH 2 CI 2. The combined organic layers are then washed once again with water . After drying over Na2 SO4 the

  11. Photocatalytic hydrogen production over solid solutions between BiFeO{sub 3} and SrTiO{sub 3}

    Lu, Lingwei; Lv, Meilin [Shanghai Key Lab of Chemical Assessment and Sustainability, Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai, 200092 (China); Liu, Gang [Shenyang National laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, 72 Wenhua Road, Shenyang 110016 (China); Xu, Xiaoxiang, E-mail: xxxu@tongji.edu.cn [Shanghai Key Lab of Chemical Assessment and Sustainability, Department of Chemistry, Tongji University, 1239 Siping Road, Shanghai, 200092 (China)

    2017-01-01

    Graphical abstract: We have successfully prepared a series of SrTiO{sub 3}-BiFeO{sub 3} solid solutions. These materials own strong visible light absorption and demonstrate appealing photocatalytic activity under both full range and visible light irradiation. - Highlights: • Band gap values can be tuned by adjusting molar ratios between SrTiO{sub 3} and BiFeO{sub 3}. • Photocatalytic activity is greatly improved after constituting solid solutions. • Photocatalytic activity is influenced by surface area and light absorption. • Fe plays an important role for band gap reduction and catalytic activity. - Abstract: Constituting solid solutions has been an appealing means to gain control over various physicochemical properties. In this work, we synthesized a series of SrTiO{sub 3}-BiFeO{sub 3} solid solutions and systematically explored their structural, optical and photocatalytic properties. Our results show that all solid solutions crystallize in a primitive cubic structure and their band gap values can be easily tuned by adjusting molar ratios between SrTiO{sub 3} and BiFeO{sub 3}. Photocatalytic hydrogen production under both full range and visible light irradiation is greatly improved after forming solid solutions. The highest hydrogen production rate obtained is ∼180 μmol/h under full range irradiation (λ ≥ 250 nm) and ∼4.2 μmol/h under visible light irradiation (λ ≥ 400 nm), corresponding to apparent quantum efficiency ∼2.28% and ∼0.10%, respectively. The activity is found to be strongly influenced by surface area and light absorption. Theoretical calculation suggests that Fe contributes to the formation of spin-polarized bands in the middle of original band gap and is responsible for the band gap reduction and visible light photocatalytic activity.

  12. Bright-Dark Mixed N-Soliton Solutions of the Multi-Component Mel'nikov System

    Han, Zhong; Chen, Yong; Chen, Junchao

    2017-10-01

    By virtue of the Kadomtsev-Petviashvili (KP) hierarchy reduction technique, we construct the general bright-dark mixed N-soliton solution to the multi-component Mel'nikov system. This multi-component system comprised of multiple (say M) short-wave components and one long-wave component with all possible combinations of nonlinearities including all-positive, all-negative and mixed types. Firstly, the two-bright-one-dark (2-b-1-d) and one-bright-two-dark (1-b-2-d) mixed N-soliton solutions in short-wave components of the three-component Mel'nikov system are derived in detail. Then we extend our analysis to the M-component Mel'nikov system to obtain its general mixed N-soliton solution. The formula obtained unifies the all-bright, all-dark and bright-dark mixed N-soliton solutions. For the collision of two solitons, an asymptotic analysis shows that for an M-component Mel'nikov system with M ≥ 3, inelastic collision takes place, resulting in energy exchange among the short-wave components supporting bright solitons only if the bright solitons appear in at least two short-wave components. In contrast, the dark solitons in the short-wave components and the bright solitons in the long-wave component always undergo elastic collision which is only accompanied by a position shift.

  13. Applications of Canonical transformations and nontrivial vacuum solutions to flavor mixing and critical phenomena in quantum field theory

    Mishchenko, Yuriy

    2004-01-01

    MISHCHENKO, YURIY. Applications of Canonical Transformations and Nontrivial Vacuum Solutions to flavor mixing and critical phenomena in Quantum Field Theory. (Under the direction of Chueng-Ryong Ji.) In this dissertation we consider two recent applications of Bogoliubov Transformation to the phenomenology of quantum mixing and the theory of critical phenomena. In recent years quantum mixing got in the focus of the searches for New Physics due to its unparalleled sensitivity to SM parameters and indications of neutrino mixing. It was recently suggested that Bogoliubov Transformation may be important in proper definition of the flavor states that otherwise results in problems in perturbative treatment. As first part of this dissertation we investigate this conjecture and develop a complete formulation of such a mixing field theory involving introduction of general formalism, analysis of space-time conversion and phenomenological implications. As second part of this dissertati

  14. Applications of Canonical transformations and nontrivial vacuum solutions to flavor mixing and critical phenomena in quantum field theory

    Mishchenko, Yuriy [North Carolina State Univ., Raleigh, NC (United States)

    2004-12-01

    MISHCHENKO, YURIY. Applications of Canonical Transformations and Nontrivial Vacuum Solutions to flavor mixing and critical phenomena in Quantum Field Theory. (Under the direction of Chueng-Ryong Ji.) In this dissertation we consider two recent applications of Bogoliubov Transformation to the phenomenology of quantum mixing and the theory of critical phenomena. In recent years quantum mixing got in the focus of the searches for New Physics due to its unparalleled sensitivity to SM parameters and indications of neutrino mixing. It was recently suggested that Bogoliubov Transformation may be important in proper definition of the flavor states that otherwise results in problems in perturbative treatment. As first part of this dissertation we investigate this conjecture and develop a complete formulation of such a mixing field theory involving introduction of general formalism, analysis of space-time conversion and phenomenological implications. As second part of this dissertati

  15. Influence of Dy in solid solution on the degradation behavior of binary Mg-Dy alloys in cell culture medium.

    Yang, Lei; Ma, Liangong; Huang, Yuanding; Feyerabend, Frank; Blawert, Carsten; Höche, Daniel; Willumeit-Römer, Regine; Zhang, Erlin; Kainer, Karl Ulrich; Hort, Norbert

    2017-06-01

    Rare earth element Dy is one of the promising alloying elements for magnesium alloy as biodegradable implants. To understand the effect of Dy in solid solution on the degradation of Mg-Dy alloys in simulated physiological conditions, the present work studied the microstructure and degradation behavior of Mg-Dy alloys in cell culture medium. It is found the corrosion resistance enhances with the increase of Dy content in solid solution in Mg. This can be attributed to the formation of a relatively more corrosion resistant Dy-enriched film which decreases the anodic dissolution of Mg. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. A Review of Solid-Solution Models of High-Entropy Alloys Based on Ab Initio Calculations

    Fuyang Tian

    2017-11-01

    Full Text Available Similar to the importance of XRD in experiments, ab initio calculations, as a powerful tool, have been applied to predict the new potential materials and investigate the intrinsic properties of materials in theory. As a typical solid-solution material, the large degree of uncertainty of high-entropy alloys (HEAs results in the difficulty of ab initio calculations application to HEAs. The present review focuses on the available ab initio based solid-solution models (virtual lattice approximation, coherent potential approximation, special quasirandom structure, similar local atomic environment, maximum-entropy method, and hybrid Monte Carlo/molecular dynamics and their applications and limits in single phase HEAs.

  17. Deep and shallow acceptor levels in solid solutions Pb0.98Sm0.02S

    Hasanov, H.A.; Rahimov, R.Sh.

    2010-01-01

    It is well known that the metal vacancies the energy levels of which take place between permitted energies of valency band, are the main acceptor centers in the led salts and solid solutions on their base. The aim of the given paper is founding of character of acceptor levels in single crystals Pb 0 .98Sm 0 .02S with low concentrations of charge carrier. The deep and shallow acceptor levels are found at investigation of Hall effect in Pb 0 .98Sm 0 .02S solid solution with character of low concentrations of charge carriers in crystals

  18. Chemically and compositionally modified solid solution disordered multiphase nickel hydroxide positive electrode for alkaline rechargeable electrochemical cells

    Ovshinsky, Stanford R.; Corrigan, Dennis; Venkatesan, Srini; Young, Rosa; Fierro, Christian; Fetcenko, Michael A.

    1994-01-01

    A high capacity, long cycle life positive electrode for use in an alkaline rechargeable electrochemical cell comprising: a solid solution nickel hydroxide material having a multiphase structure that comprises at least one polycrystalline .gamma.-phase including a polycrystalline .gamma.-phase unit cell comprising spacedly disposed plates with at least one chemical modifier incorporated around the plates, the plates having a range of stable intersheet distances corresponding to a 2.sup.+ oxidation state and a 3.5.sup.+, or greater, oxidation state; and at least one compositional modifier incorporated into the solid solution nickel hydroxide material to promote the multiphase structure.

  19. Neutron diffraction radiation of solid solution of carbon and hydrogen in the α-titanium in the homogeneity domain

    Mirzaev, B.B.; Khidirov, I.; Mukhtarova, N.N.

    2005-01-01

    In the work by the neutron-graph the homogeneity domain of the introduction solid solution TiC x H y is determined. The sample neutron grams have been taken on the neutron diffractometer (λ=.1085 nm) installed at the thermal column of the WWR-SM reactor (INF AN RUz). For the phase analysis and estimation of solid solutions homogeneity the X-ray graph was used. X-ray grams were taken on the X-ray diffractometer DRON-3M with use of CuK α radiation (λ=0.015418 nm)

  20. Thermoelectric properties of Bi2Te3-Bi2Se3 solid solutions prepared by attrition milling and hot pressing

    Lee, Go-Eun; Kim, Il-Ho; Choi, Soon-Mok; Lim, Young-Soo; Seo, Won-Seon; Park, Jae-Soung; Yang, Seung-Ho

    2014-01-01

    Bi 2 Te 3-y Se y (y = 0.15 - 0.6) solid solutions were prepared by attrition milling and hot pressing. The lattice constants decreased with increasing Se content, indicating that the Se atoms were successfully substituted into the Te sites. All specimens exhibited n-type conduction, and their electrical resistivities increased slightly with increasing temperature. With increasing Se content, the Seebeck coefficients increased while the thermal conductivity decreased due to the increase in phonon scattering. The maximum figure of merit obtained was 0.63 at 440 K for the undoped Bi 2 Te 2.4 Se 0.6 solid solution.

  1. Specific features of kinetics of He/sup 3/-He/sup 4/ solid solution transformations at superlow temperatures

    Mikheev, V A; Majdanov, V A; Mikhin, N P

    1986-06-01

    The NMR data on the phase transition kinetics of /sup 3/He-/sup 4/He solid solutions at T=100 mK are considered. Studied are solid helium samples of a molecular volume of 20.55 cm/sup 2//mol with a /sup 3/He content of 0.54%. An unusually long phase transition time is found which is dependent on the prehistory of sample. The spin diffusion of /sup 3/He in the transformated solution concentrated phase is found to be of a quasi-one-dimensional nature with the diffusion coefficient value typical of liquid.

  2. Numerical Solution of Mixed Problems of the Theory of Elasticity with One-Sided Constraints

    I. V. Stankevich

    2017-01-01

    enable us to ensure continuous approximation of not only displacements, but also stresses and strains. Mixed schemes to solve the boundary value problems lead to the saddle-point problems. Their solutions use various iterative techniques. One of the most effective techniques is a modified SSOR (MSSOR method, based on the SOR (Successive Over Relaxation one.The paper considers one of the options of the finite element method in the framework of mixed scheme that uses a Reissner functional. The procedures of the algorithm proposed in the paper are used to solve the problem of contact interaction when an elastic body of the finite dimensions, being under a load of the external forces, relies on the absolutely rigid half-space. The contact occurs with the distinguished contact surface, which in the general case can change its size during thermo-mechanical loading. The algorithm is implemented as an application software complex. The numerical study of the one-sided contact interaction between the elastic plate and the perfectly rigid half-space has shown a fairly high efficiency of the developed algorithm and the code that implements it.

  3. Existence and Uniqueness of Solutions for a Discrete Fractional Mixed Type Sum-Difference Equation Boundary Value Problem

    Weidong Lv

    2015-01-01

    Full Text Available By means of Schauder’s fixed point theorem and contraction mapping principle, we establish the existence and uniqueness of solutions to a boundary value problem for a discrete fractional mixed type sum-difference equation with the nonlinear term dependent on a fractional difference of lower order. Moreover, a suitable choice of a Banach space allows the solutions to be unbounded and two representative examples are presented to illustrate the effectiveness of the main results.

  4. A Mixed Monotone Operator Method for the Existence and Uniqueness of Positive Solutions to Impulsive Caputo Fractional Differential Equations

    Jieming Zhang

    2013-01-01

    Full Text Available We establish some sufficient conditions for the existence and uniqueness of positive solutions to a class of initial value problem for impulsive fractional differential equations involving the Caputo fractional derivative. Our analysis relies on a fixed point theorem for mixed monotone operators. Our result can not only guarantee the existence of a unique positive solution but also be applied to construct an iterative scheme for approximating it. An example is given to illustrate our main result.

  5. Mixed

    Pau Baya

    2011-05-01

    Full Text Available Remenat (Catalan (Mixed, "revoltillo" (Scrambled in Spanish, is a dish which, in Catalunya, consists of a beaten egg cooked with vegetables or other ingredients, normally prawns or asparagus. It is delicious. Scrambled refers to the action of mixing the beaten egg with other ingredients in a pan, normally using a wooden spoon Thought is frequently an amalgam of past ideas put through a spinner and rhythmically shaken around like a cocktail until a uniform and dense paste is made. This malleable product, rather like a cake mixture can be deformed pulling it out, rolling it around, adapting its shape to the commands of one’s hands or the tool which is being used on it. In the piece Mixed, the contortion of the wood seeks to reproduce the plasticity of this slow heavy movement. Each piece lays itself on the next piece consecutively like a tongue of incandescent lava slowly advancing but with unstoppable inertia.

  6. Optical CT imaging of solid radiochromic dosimeters in mismatched refractive index solutions using a scanning laser and large area detector

    Dekker, Kurtis H., E-mail: kdekker2@uwo.ca [Department of Medical Biophysics, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario N6A 5C1 (Canada); Battista, Jerry J.; Jordan, Kevin J. [Departments of Medical Biophysics and Oncology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada and Department of Physics and Engineering, London Regional Cancer Program, London Health Sciences Centre, 790 Commissioners Road East, London, Ontario N6A 4L6 (Canada)

    2016-08-15

    Purpose: The practical use of the PRESAGE® solid plastic dosimeter is limited by the inconvenience of immersing it in high-viscosity oils to achieve refractive index matching for optical computed tomography (CT) scanning. The oils are slow to mix and difficult to clean from surfaces, and the dosimeter rotation can generate dynamic Schlieren inhomogeneity patterns in the reference liquid, limiting the rotational and overall scan speed. Therefore, it would be beneficial if lower-viscosity, water-based solutions with slightly unmatched refractive index could be used instead. The purpose of this work is to demonstrate the feasibility of allowing mismatched conditions when using a scanning laser system with a large acceptance angle detector. A fiducial-based ray path measurement technique is combined with an iterative CT reconstruction algorithm to reconstruct images. Methods: A water based surrounding liquid with a low viscosity was selected for imaging PRESAGE® solid dosimeters. Liquid selection was optimized to achieve as high a refractive index as possible while avoiding rotation-induced Schlieren effects. This led to a refractive index mismatch of 6% between liquid and dosimeters. Optical CT scans were performed with a fan-beam scanning-laser optical CT system with a large area detector to capture most of the refracted rays. A fiducial marker placed on the wall of a cylindrical sample occludes a given light ray twice. With knowledge of the rotation angle and the radius of the cylindrical object, the actual internal path of each ray through the dosimeter can be calculated. Scans were performed with 1024 projections of 512 data samples each, and rays were rebinned to form 512 parallel-beam projections. Reconstructions were performed on a 512 × 512 grid using 100 iterations of the SIRT iterative CT algorithm. Proof of concept was demonstrated with a uniformly attenuating solution phantom. PRESAGE® dosimeters (11 cm diameter) were irradiated with Cobalt-60

  7. Solid ceramic based on mixed-frame titanium phosphate and calcium synthesized in solar furnace

    Salikhov, T. P.; Kan, V. V.; Urazaeva, Eh. M.; Savatyugina, T. V.; Arushanov, G. M.

    2012-01-01

    The authors synthesized of mixed orthophosphates Ca 0 . 5 Ti 2 (PO 4 ) 3 using concentrated solar radiation. We obtained a porous ceramic filter with the given type of NZP structure and high thermal and hydrolytic stability. (authors)

  8. Alternatives to land disposal of solid radioactive mixed wastes on the Hanford Site

    Jacobsen, P.H.

    1992-03-01

    This report is a detailed description of the generation and management of land disposal restricted mixed waste generated, treated, and stored at the Hanford Site. This report discusses the land disposal restricted waste (mixed waste) managed at the Hanford Site by point of generation and current storage locations. The waste is separated into groups on the future treatment of the waste before disposal. This grouping resulted in the definition of 16 groups or streams of land disposal restricted waste

  9. Enhanced viability of Lactobacillus reuteri for probiotics production in mixed solid-state fermentation in the presence of Bacillus subtilis.

    Zhang, Yi-Ran; Xiong, Hai-Rong; Guo, Xiao-Hua

    2014-01-01

    In order to develop a multi-microbe probiotic preparation of Lactobacillus reuteri G8-5 and Bacillus subtilis MA139 in solid-state fermentation, a series of parameters were optimized sequentially in shake flask culture. The effect of supplementation of B. subtilis MA139 as starters on the viability of L. reuteri G8-5 was also explored. The results showed that the optimized process was as follows: water content, 50 %; initial pH of diluted molasses, 6.5; inocula volume, 2 %; flask dry contents, 30∼35 g/250 g without sterilization; and fermentation time, 2 days. The multi-microbial preparations finally provided the maximum concentration of Lactobacillus of about 9.01 ± 0.15 log CFU/g and spores of Bacillus of about 10.30 ± 0.08 log CFU/g. Compared with pure fermentation of L. reuteri G8-5, significantly high viable cells, low value of pH, and reducing sugar in solid substrates were achieved in mixed fermentation in the presence of B. subtilis MA139 (P fermentation showed the significantly higher antimicrobial activity against E. coli K88 (P solid-state fermentation with low cost. Moreover, the viability of L. reuteri G8-5 could be significantly enhanced in the presence of B. subtilis MA139 in solid-state fermentation, which favored the production of probiotics for animal use.

  10. Cellulase production by Trichoderma harzianum in static and mixed solid-state fermentation reactors under nonaseptic conditions

    Deschamps, F.; Giuliano, C.; Asther, M.; Huet, M.C.; Roussos, S.

    1985-09-01

    Cellulase production from lignocellulosic materials was studied in solid-state cultivation by both static and mixed techniques under nonaseptic conditions. The effects of fermentation conditions, such as moisture content, pH, temperature, and aeration, on cellulase production by Trichoderma harzianum using a mixture of wheat straw (80%) and bran (20%) were investigated. With a moisture content of 74% and a pH of 5.8, 18 IU filter paper activity and 198 IU endoglucanase activity/g initial substrate content were obtained in 66 hours. The extension from static column cultivation to stirred tank reactor of 65 l capacity gave similar yields of cellulase.

  11. Solution and solid-state electrochemiluminescence of a fac-tris(2-phenylpyridyl)iridium(III)-cored dendrimer

    Reid, Ellen F.; Burn, Paul L.; Lo, Shih-Chun; Hogan, Conor F.

    2013-01-01

    The solution phase and solid-state electrochemistry and electrochemiluminescence (ECL) of an iridium(III) complex-cored dendrimeric analogue of Ir(ppy) 3 , (G1pIr), are reported. The solid-state electrochemistry and solid-state ECL of Ir(ppy) 3 itself is also described for the first time. In solution phase, the dendrimer displays greater immunity to oxygen quenching in photoluminescence (PL) experiments and exhibits greater ECL efficiency compared to the parent Ir(ppy) 3 core under the same conditions, despite a lower photoluminescence quantum yield. It is proposed that the dendrons which effectively shield the core from PL quenching interactions in the solid-state counteract the effects of parasitic side-reactions during the solution ECL experiments. Electroactive and ECL-active solid-state films of both Ir(ppy) 3 and G1pIr were produced by drop-coating on boron doped diamond electrodes. Films of Ir(ppy) 3 produced stable co-reactant ECL. However, films of G1pIr produced lower than expected ECL intensity. This was attributed to poorer charge transport and the lipophilicity of the film limiting the rate of interaction with the co-reactant required for formation of the excited state

  12. The oxygen potential of near- and non-stoichiometric urania-25 mol% plutonia solid solutions: a comparison of thermogravimetric and galavanic cell measurements

    Woodley, R.E.; Adamson, M.G.

    1979-01-01

    To resolve discrepancies between the existing low temperature ΔGsub(0 2 )(mean) data for solid solution mixed (U, Pu)-oxide nuclear fuel material, additional measurements have been performed on Usub(0.75)Pusub(0.25) employing a combined thermogravimetric (TGA) and solid-electrolyte galvanic cell technique. These measurements, which were performed at temperatures between 800 and 1000 0 C, and for O:M ratios in the range 1.940 to 2.028, are reasonably self-consistent and show good agreement with the results of previous TGA measurements. However, they do not corroborate the earlier EMF cell measurements of Markin and McIver. (1967). Possible explanations for errors in these earlier EMF cell results are examined. The new results indicate that the ΔGsub(O 2 )(mean) of stoichiometric mixed oxide at typical outer surface fuel temperature is close to -100 kcal/mol 0 2 (-419 kJ/mol O 2 ). Attempts have been made to fit the new ΔGsub(O 2 )(mean) data to two equations derived from recent defect models, and it is shown that neither equation accurately represents the experimental psub(O 2 ) - x data over more than a short range of x. (Auth.)

  13. Mechanism of redox reactions induced by light and electron pulse in solutions of mixed ligand iron(II) complex cyanides

    Horvath, A.; Szoeke, J.; Wojnarovits, L.

    1991-01-01

    Redox reactions induced by light and electron pulse have been studied in aqueous solutions of mixed ligand iron(II) complex cyanides. The short lived intermediates have been identified by time resolved specroscopy, the results of detailed kinetic analysis have been discussed. (author) 6 refs.; 3 figs.; 2 tabs

  14. Calculation of radiation effects in solids by direct numerical solution of the adjoint transport equation

    Matthes, W.K.

    1998-01-01

    The 'adjoint transport equation in its integro-differential form' is derived for the radiation damage produced by atoms injected into solids. We reduce it to the one-dimensional form and prepare it for a numerical solution by: --discretizing the continuous variables energy, space and direction, --replacing the partial differential quotients by finite differences and --evaluating the collision integral by a double sum. By a proper manipulation of this double sum the adjoint transport equation turns into a (very large) set of linear equations with tridiagonal matrix which can be solved by a special (simple and fast) algorithm. The solution of this set of linear equations contains complete information on a specified damage type (e.g. the energy deposited in a volume V) in terms of the function D(i,E,c,x) which gives the damage produced by all particles generated in a cascade initiated by a particle of type i starting at x with energy E in direction c. It is essential to remark that one calculation gives the damage function D for the complete ranges of the variables {i,E,c and x} (for numerical reasons of course on grid-points in the {E,c,x}-space). This is most useful to applications where a general source-distribution S(i,E,c,x) of particles is given by the experimental setup (e.g. beam-window and and target in proton accelerator work. The beam-protons along their path through the window--or target material generate recoil atoms by elastic collisions or nuclear reactions. These recoil atoms form the particle source S). The total damage produced then is eventually given by: D = (Σ)i ∫ ∫ ∫ S(i, E, c, x)*D(i, E, c, x)*dE*dc*dx A Fortran-77 program running on a PC-486 was written for the overall procedure and applied to some problems

  15. Numerical Simulation of Solid Combustion with a Robust Conjugate-Gradient Solution for Pressure

    Wang, Yi-Zun

    2002-01-01

    A Bi-Conjugate Gradient method (Bi-CGSTAB) is studied and tested for solid combustion in which the gas and solid phases are coupled by a set of conditions describing mass, momentum and heat transport across the interface...

  16. Quinary wurtzite Zn-Ga-Ge-N-O solid solutions and their photocatalytic properties under visible light irradiation

    Xie, Yinghao; Wu, Fangfang; Sun, Xiaoqin; Chen, Hongmei; Lv, Meilin; Ni, Shuang; Liu, Gang; Xu, Xiaoxiang

    2016-01-01

    Wurtzite solid solutions between GaN and ZnO highlight an intriguing paradigm for water splitting into hydrogen and oxygen using solar energy. However, large composition discrepancy often occurs inside the compound owing to the volatile nature of Zn, thereby prescribing rigorous terms on synthetic conditions. Here we demonstrate the merits of constituting quinary Zn-Ga-Ge-N-O solid solutions by introducing Ge into the wurtzite framework. The presence of Ge not only mitigates the vaporization of Zn but also strongly promotes particle crystallization. Synthetic details for these quinary compounds were systematically explored and their photocatalytic properties were thoroughly investigated. Proper starting molar ratios of Zn/Ga/Ge are of primary importance for single phase formation, high particle crystallinity and good photocatalytic performance. Efficient photocatalytic hydrogen and oxygen production from water were achieved for these quinary solid solutions which is strongly correlated with Ge content in the structure. Apparent quantum efficiency for optimized sample approaches 1.01% for hydrogen production and 1.14% for oxygen production. Theoretical calculation reveals the critical role of Zn for the band gap reduction in these solid solutions and their superior photocatalytic acitivity can be understood by the preservation of Zn in the structure as well as a good crystallinity after introducing Ge.

  17. Community Solutions to Solid Waste Pollution. Operation Waste Watch: The New Three Rs for Elementary School. Grade 6. [Second Edition.

    Virginia State Dept. of Waste Management, Richmond. Div. of Litter & Recycling.

    This publication, the last in a series of seven for elementary schools, is an environmental education curriculum guide with a focus on waste management issues. It contains a unit of exercises selected for sixth grade students focusing on community solutions to solid waste pollution. Waste management activities included in this unit seek to…

  18. Phase Relations in Ternary Systems in the Subsolidus Region: Methods to Formulate Solid Solution Equations and to Find Particular Compositions

    Alvarez-Montan~o, Victor E.; Farías, Mario H.; Brown, Francisco; Mun~oz-Palma, Iliana C.; Cubillas, Fernando; Castillon-Barraza, Felipe F.

    2017-01-01

    A good understanding of ternary phase diagrams is required to advance and/or to reproduce experimental research in solid-state and materials chemistry. The aim of this paper is to describe the solutions to problems that appear when studying or determining ternary phase diagrams. A brief description of the principal features shown in phase diagrams…

  19. About thermal properties of TIIn1-xNdxS2 (0≤X≤0.10) solid solutions

    Zarbaliev, M.M.; Agaeva, U.M.; Sardarova, N.S.

    2013-01-01

    This report is devoted to investigation of thermal expansion and thermal conductivity of TIIn 1 -xNd x S 2 (0≤X≤0.10) solid solutions, depending on the concentration and temperature at 80-450 K. The measurements were carried out on the thermal expansion of polycrystalline, and the thermal conductivity of single-crystal samples

  20. Laminating solution-processed silver nanowire mesh electrodes onto solid-state dye-sensitized solar cells

    Hardin, Brian E.; Gaynor, Whitney; Ding, I-Kang; Rim, Seung-Bum; Peumans, Peter; McGehee, Michael D.

    2011-01-01

    Solution processed silver nanowire meshes (Ag NWs) were laminated on top of solid-state dye-sensitized solar cells (ss-DSCs) as a reflective counter electrode. Ag NWs were deposited in <1 min and were less reflective compared to evaporated Ag

  1. Neutron diffraction studies on Ca1− xBaxZr4P6O24 solid solutions

    P6O24 compositions from combined Rietveld refinements of powder X-ray and neutron diffraction data. All the studied compositions crystallize in rhombohedral lattice (space group R-3 No. 148). A continuous solid solution is concluded from ...

  2. Measurement of flow characteristics of solid particles mixed with gas in pipelines

    Siberev, S P; Nazarov, S I; Soldatkin, G I

    1983-01-01

    A mathematical model of the interaction of solid particles in a gas stream flowing through a pipeline comprises equations for the energy and material balances in the system and for force and energy interactions between the solid particles and transducers located within the pipeline. Soviet researchers confirmed that the average value of stress recorded by a transducer is proportional to the average kinetic energy of the particles; for a constant particle speed, the stress is proportional to the mass flow of the particles. The analysis and flow transducer measurements are valuable in measuring and controlling flowline sand and soil in natural gas transport from gas wells and undergound storage facilities.

  3. Regenerable mixed copper-iron-inert support oxygen carriers for solid fuel chemical looping combustion process

    Siriwardane, Ranjani V.; Tian, Hanjing

    2016-12-20

    The disclosure provides an oxygen carrier for a chemical looping cycle, such as the chemical looping combustion of solid carbonaceous fuels, such as coal, coke, coal and biomass char, and the like. The oxygen carrier is comprised of at least 24 weight % (wt %) CuO, at least 10 wt % Fe2O3, and an inert support, and is typically a calcine. The oxygen carrier exhibits a CuO crystalline structure and an absence of iron oxide crystalline structures under XRD crystallography, and provides an improved and sustained combustion reactivity in the temperature range of 600.degree. C.-1000.degree. C. particularly for solid fuels such as carbon and coal.

  4. Optical and Piezoelectric Study of KNN Solid Solutions Co-Doped with La-Mn and Eu-Fe

    Jesús-Alejandro Peña-Jiménez

    2016-09-01

    Full Text Available The solid-state method was used to synthesize single phase potassium-sodium niobate (KNN co-doped with the La3+–Mn4+ and Eu3+–Fe3+ ion pairs. Structural determination of all studied solid solutions was accomplished by XRD and Rietveld refinement method. Electron paramagnetic resonance (EPR studies were performed to determine the oxidation state of paramagnetic centers. Optical spectroscopy measurements, excitation, emission and decay lifetime were carried out for each solid solution. The present study reveals that doping KNN with La3+–Mn4+ and Eu3+–Fe3+ at concentrations of 0.5 mol % and 1 mol %, respectively, improves the ferroelectric and piezoelectric behavior and induce the generation of optical properties in the material for potential applications.

  5. The unbounded solution of a periodic mixed Sturm–Liouville problem in an infinite strip for the Laplacian

    M.G. Elsheikh

    2013-10-01

    Full Text Available The unbounded solution, at the points where the boundary conditions change, for a mixed Sturm–Liouville problem of the Dirichlet–Neumann type can be obtained using the method of the integral equation formulation. Since this formulation is usually reduced to an infinite algebraic system in which the unknowns are the Fourier coefficients of the unknown unbounded entity, a study of ℓp-solutions imposes itself concerning the influence of the truncation on such systems. This study is achieved and the well-known theorem on the ℓ2-solutions of the infinite algebraic systems is generalized.

  6. Planet Patrol. An Environmental Unit on Solid Waste Solutions for Grades 4-6.

    Procter and Gamble Educational Services, Cincinnati, OH.

    This classroom unit was developed for use in grades 4-6 to help teach the concept of solid waste management. The teacher's guide provides an overview of the issue of solid waste disposal, a description of government, industry, and consumer roles in resolving the solid waste issue, and four lessons involving sanitary landfills, the reduction of…

  7. Evolution of ion damage at 773K in Ni- containing concentrated solid-solution alloys

    Shi, Shi; He, Mo-Rigen; Jin, Ke; Bei, Hongbin; Robertson, Ian M.

    2018-04-01

    Quantitative analysis of the impact of the compositional complexity in a series of Ni-containing concentrated solid-solution alloys, Ni, NiCo, NiFe, NiCoCr, NiCoFeCr, NiCoFeCrMn and NiCoFeCrPd, on the evolution of defects produced by 1 MeV Kr ion irradiation at 773 K is reported. The dynamics of the evolution of the damage structure during irradiation to a dose of 2 displacements per atom were observed directly by performing the ion irradiations in electron transparent foils in a transmission electron microscope coupled to an ion accelerator. The defect evolution was assessed through measurement of the defect density, defect size and fraction of perfect and Frank loops. These three parameters were dependent on the alloying element as well as the number of elements. The population of loops was sensitive to the ion dose and alloy composition as faulted Frank loops were observed to unfault to perfect loops with increasing ion dose. These dependences are explained in terms of the influence of each element on the lifetime of the displacement cascade as well as on defect formation and migration energies.

  8. Cerium valence change in the solid solutions Ce(Rh1-xRux)Sn

    Niehaus, Oliver; Riecken, Jan F.; Winter, Florian; Poettgen, Rainer; Muenster Univ.; Abdala, Paula M.; Chevalier, Bernard

    2013-01-01

    The solid solutions Ce(Rh 1-x Ru x )Sn were investigated by means of susceptibility measurements, specific heat, electrical resistivity, X-ray absorption spectroscopy (XAS), and 119 Sn Moessbauer spectroscopy. Magnetic measurements as well as XAS data show a cerium valence change in dependence on the ruthenium content. Higher ruthenium content causes an increase from 3.22 to 3.45 at 300 K. Furthermore χ and χ -1 data indicate valence fluctuation for cerium as a function of temperature. For example, Ce(Rh 0.8 Ru 0.2 )Sn exhibits valence fluctuations between 3.42 and 3.32 in the temperature range of 10 to 300 K. This could be proven by using the interconfiguration fluctuation (ICF) model introduced by Sales and Wohlleben. Cerium valence change does not influence the tin atoms as proven by 119 Sn Moessbauer spectroscopy, but it influences the electrical properties. Ce(Rh 0.9 Ru 0.1 )Sn behaves like a typical valence fluctuating compound, and higher ruthenium content causes an increase of the metallic behavior. (orig.)

  9. Radiation-induced segregation on defect clusters in single-phase concentrated solid-solution alloys

    Lu, Chenyang; Yang, Taini; Jin, Ke; Gao, Ning; Xiu, Pengyuan; Zhang, Yanwen; Gao, Fei; Bei, Hongbin; Weber, William J.; Sun, Kai; Dong, Yan; Wang, Lumin

    2017-01-01

    A group of single-phase concentrated solid-solution alloys (SP-CSAs), including NiFe, NiCoFe, NiCoFeCr, as well as a high entropy alloy NiCoFeCrMn, was irradiated with 3 MeV Ni"2"+ ions at 773 K to a fluence of 5 × 10"1"6 ions/cm"2 for the study of radiation response with increasing compositional complexity. Advanced transmission electron microscopy (TEM) with electron energy loss spectroscopy (EELS) was used to characterize the dislocation loop distribution and radiation-induced segregation (RIS) on defect clusters in the SP-CSAs. The results show that a higher fraction of faulted loops exists in the more compositionally complex alloys, which indicate that increasing compositional complexity can extend the incubation period and delay loop growth. The RIS behaviors of each element in the SP-CSAs were observed as follows: Ni and Co tend to enrich, but Cr, Fe and Mn prefer to deplete near the defect clusters. RIS level can be significantly suppressed by increasing compositional complexity due to the sluggish atom diffusion. According to molecular static (MS) simulations, “disk” like segregations may form near the faulted dislocation loops in the SP-CSAs. Segregated elements tend to distribute around the whole faulted loop as a disk rather than only around the edge of the loop.

  10. Structure and adhesive properties of solid solution specimen surfaces based on bismuth tellurides after cutting

    Dik, M.G.; Rybina, L.N.; Dubrovina, A.N.; Abdinov, D.Sh.

    1988-01-01

    Structure and depth of broken layer, occuring at electroerosion cutting along ingot samples axis of Bi 2 Te 3 -Bi 2 Se 3 , Bi 2 Te 3 -Sb 2 Te 3 systems solid solutions (obtained by methods of directed crystallization and extrusion), and equilibrium contact angle θ, adhesion effort A and contact resistance r c of these crystals contacts with eutectic alloy of Bi-Sn system are investigated. Depth and structure of the broken layer were determined by means of stage-by-stage scouring-etching and X-ray investigation of cutting surface. It is shown, that etching during ∼50 c in large-block material eliminates polycrystalline layer, lattice bendings, resulting in Laue spots asterism, but does not remove their fragmentation and wash-out. Slots wash-out reduces, while fragmentation remains even after continuous etching. Etching with duration from ∼50 c up to 30-40 min practically does not change the character of polycrystalline samples diffraction pattern

  11. Stacking fault energy measurements in solid solution strengthened Ni-Cr-Fe alloys using synchrotron radiation

    Unfried-Silgado, Jimy [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil); Universidade Estadual de Campinas UNICAMP, Faculdade de Engenharia Mecanica FEM, Campinas (Brazil); Universidad Autonoma del Caribe, Grupo IMTEF, Ingenieria Mecanica, Barranquilla (Colombia); Wu, Leonardo [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil); Furlan Ferreira, Fabio [Universidade Federal do ABC, Centro de Ciencias Naturais e Humanas (CCNH), Sao Paulo (Brazil); Mario Garzon, Carlos [Universidad Nacional de Colombia, Departamento de Fisica, Bogota (Colombia); Ramirez, Antonio J, E-mail: antonio.ramirez@lnnano.org.br [Metals Characterization and Processing Laboratory, Brazilian Nanothecnology National Laboratory - CNPEM/ABTLuS, Caixa Postal 6192, CEP 13083-970, Campinas, Sao Paulo (Brazil)

    2012-12-15

    The stacking fault energy (SFE) in a set of experimental Ni-Cr-Fe alloys was determined using line profile analysis on synchrotron X-ray diffraction measurements. The methodology used here is supported by the Warren-Averbach calculations and the relationships among the stacking fault probability ({alpha}) and the mean-square microstrain (<{epsilon}{sup 2}{sub L}>). These parameters were obtained experimentally from cold-worked and annealed specimens extracted from the set of studied Ni-alloys. The obtained results show that the SFE in these alloys is strongly influenced by the kind and quantity of addition elements. Different effects due to the action of carbide-forming elements and the solid solution hardening elements on the SFE are discussed here. The simultaneous addition of Nb, Hf, and, Mo, in the studied Ni-Cr-Fe alloys have generated the stronger decreasing of the SFE. The relationships between SFE and the contributions on electronic structure from each element of additions were established.

  12. Solid solutions of gadolinium doped zinc oxide nanorods by combined microwave-ultrasonic irradiation assisted crystallization

    Kiani, Armin; Dastafkan, Kamran; Obeydavi, Ali; Rahimi, Mohammad

    2017-12-01

    Nanocrystalline solid solutions consisting of un-doped and gadolinium doped zinc oxide nanorods were fabricated by a modified sol-gel process utilizing combined ultrasonic-microwave irradiations. Polyvinylpyrrolidone, diethylene glycol, and triethylenetetramine respectively as capping, structure directing, and complexing agents were used under ultrasound dynamic aging and microwave heating to obtain crystalline nanorods. Crystalline phase monitoring, lattice parameters and variation, morphology and shape, elemental analysis, functional groups, reducibility, and the oxidation state of emerged species were examined by PXRD, FESEM, TEM, EDX, FTIR, micro Raman, H2-TPR, and EPR techniques. Results have verified that irradiation mechanism of gelation and crystallization reduces the reaction time, augments the crystal quality, and formation of hexagonal close pack structure of Wurtzite morphology. Besides, dissolution of gadolinium within host lattice involves lattice deformation, unit cell distortion, and angular position variation. Structure related shape and growth along with compositional purity were observed through microscopic and spectroscopic surveys. Furthermore, TPR and EPR studies elucidated more detailed behavior upon exposure to the exerted irradiations and subsequent air-annealing including the formed oxidation states and electron trapping centers, presence of gadolinium, zinc, and oxygen disarrays and defects, as well as alteration in the host unit cell via gadolinium addition.

  13. Bioadsorption of a reactive dye from aqueous solution by municipal solid waste

    Abdelkader Berrazoum

    2015-09-01

    Full Text Available The biosorbent was obtained from municipal solid waste (MSW of the Mostaganem city. Before use the MSW was dried in air for three days and washed several times. The sorption of yellow procion reactive dye MX-3R onto biomass from aqueous solution was investigated as function of pH, contact time and temperature. The adsorption capacity of MX-3R was 45.84 mg/g at pH 2–3 and room temperature. MX-3R adsorption decreases with increasing temperature. The Langmuir, Freundlich and Langmuir–Freundlich adsorption models were applied to describe the related isotherms. Langmuir–Freundlich equation has shown the best fitting with the experimental data. The pseudo first-order, pseudo second-order and intra-particle diffusion kinetic models were used to describe the kinetic sorption. The results clearly showed that the adsorption of MX-3R onto biosorbent followed the pseudo second-order model. The enthalpy (ΔH°, entropy (ΔS° and Gibbs free energy (ΔG° changes of adsorption were calculated. The results indicated that the adsorption of MX-3R occurs spontaneously as an exothermic process.

  14. Understanding the defect chemistry of alkali metal strontium silicate solid solutions: insights from experiment and theory

    Bayliss, Ryan D.; Cook, Stuart N.; Scanlon, David O.; Fearn, Sarah; Cabana, Jordi; Greaves, Colin; Kilner, John A.; Skinner, Stephen J.

    2014-01-01

    © the Partner Organisations 2014. Recent reports of remarkably high oxide ion conduction in a new family of strontium silicates have been challenged. It has recently been demonstrated that, in the nominally potassium substituted strontium germanium silicate material, the dominant charge carrier was not the oxygen ion, and furthermore that the material was not single phase (R. D. Bayliss et. al., Energy Environ. Sci., 2014, DOI: 10.1039/c4ee00734d). In this work we re-investigate the sodium-doped strontium silicate material that was reported to exhibit the highest oxide ion conductivity in the solid solution, nominally Sr0.55Na0.45SiO2.775. The results show lower levels of total conductivity than previously reported and sub-micron elemental mapping demonstrates, in a similar manner to that reported for the Sr0.8K0.2Si0.5Ge0.5O2.9 composition, an inhomogeneous chemical distribution correlating with a multiphase material. It is also shown that the conductivity is not related to protonic mobility. A density functional theory computational approach provides a theoretical justification for these new results, related to the high energetic costs associated with oxygen vacancy formation. This journal is

  15. Adsorption mechanisms of removing heavy metals and dyes from aqueous solution using date pits solid adsorbent

    Al-Ghouti, Mohammad A.; Li, Juiki; Salamh, Yousef; Al-Laqtah, Nasir; Walker, Gavin; Ahmad, Mohammad N.M.

    2010-01-01

    A potential usefulness of raw date pits as an inexpensive solid adsorbent for methylene blue (MB), copper ion (Cu 2+ ), and cadmium ion (Cd 2+ ) has been demonstrated in this work. This work was conducted to provide fundamental information from the study of equilibrium adsorption isotherms and to investigate the adsorption mechanisms in the adsorption of MB, Cu 2+ , and Cd 2+ onto raw date pits. The fit of two models, namely Langmuir and Freundlich models, to experimental data obtained from the adsorption isotherms was checked. The adsorption capacities of the raw date pits towards MB and both Cu 2+ and Cd 2+ ions obtained from Langmuir and Freundlich models were found to be 277.8, 35.9, and 39.5 mg g -1 , respectively. Surface functional groups on the raw date pits surface substantially influence the adsorption characteristics of MB, Cu 2+ , and Cd 2+ onto the raw date pits. The Fourier transform infrared spectroscopy (FTIR) studies show clear differences in both absorbances and shapes of the bands and in their locations before and after solute adsorption. Two mechanisms were observed for MB adsorption, hydrogen bonding and electrostatic attraction, while other mechanisms were observed for Cu 2+ and Cd 2+ . For Cu 2+ , binding two cellulose/lignin units together is the predominant mechanism. For Cd 2+ , the predominant mechanism is by binding itself using two hydroxyl groups in the cellulose/lignin unit.

  16. A Unified Physical Model for Creep and Hot Working of Al-Mg Solid Solution Alloys

    Stefano Spigarelli

    2017-12-01

    Full Text Available The description of the dependence of steady-state creep rate on applied stress and temperature is almost invariably based on the Norton equation or on derived power-law relationships. In hot working, the Norton equation does not work, and is therefore usually replaced with the Garofalo (sinh equation. Both of these equations are phenomenological in nature and can be seldom unambiguously related to microstructural parameters, such as dislocation density, although early efforts in this sense led to the introduction of the “natural power law” with exponent 3. In an attempt to overcome this deficiency, a recent model with sound physical basis has been successfully used to describe the creep response of fcc metals, such as copper. The main advantage of this model is that it does not require any data fitting to predict the strain rate dependence on applied stress and temperature, which is a particularly attractive peculiarity when studying the hot workability of metals. Thus, the model, properly modified to take into account solid solution strengthening effects, has been here applied to the study of the creep and hot-working of simple Al-Mg single phase alloys. The model demonstrated an excellent accuracy in describing both creep and hot working regimes, still maintaining its most important feature, that is, it does not require any fitting of the experimental data.

  17. Carbonation of municipal solid waste incineration electrostatic precipitator fly ashes in solution.

    De Boom, Aurore; Aubert, Jean-Emmanuel; Degrez, Marc

    2014-05-01

    Carbonation was applied to a Pb- and Zn-contaminated fraction of municipal solid waste incineration electrofilter fly ashes in order to reduce heavy metal leaching. Carbonation tests were performed in solution, by Na2CO3 addition or CO2 bubbling, and were compared with washing (with water only). The injection of CO2 during the washing did not modify the mineralogy, but the addition of Na2CO3 induced the reaction with anhydrite, forming calcite. Microprobe analyses showed that Pb and Zn contamination was rather diffuse and that the various treatments had no effect on Pb and Zn speciation in the residues. The leaching tests indicated that carbonation using Na2CO3 was successful because it gave a residue that could be considered as non-hazardous material. With CO2 bubbling, Pb and Zn leaching was strongly decreased compared with material washed with water alone, but the amount of chromium extracted became higher than the non-hazardous waste limits for landfilling.

  18. Understanding the defect chemistry of alkali metal strontium silicate solid solutions: insights from experiment and theory

    Bayliss, Ryan D.

    2014-09-24

    © the Partner Organisations 2014. Recent reports of remarkably high oxide ion conduction in a new family of strontium silicates have been challenged. It has recently been demonstrated that, in the nominally potassium substituted strontium germanium silicate material, the dominant charge carrier was not the oxygen ion, and furthermore that the material was not single phase (R. D. Bayliss et. al., Energy Environ. Sci., 2014, DOI: 10.1039/c4ee00734d). In this work we re-investigate the sodium-doped strontium silicate material that was reported to exhibit the highest oxide ion conductivity in the solid solution, nominally Sr0.55Na0.45SiO2.775. The results show lower levels of total conductivity than previously reported and sub-micron elemental mapping demonstrates, in a similar manner to that reported for the Sr0.8K0.2Si0.5Ge0.5O2.9 composition, an inhomogeneous chemical distribution correlating with a multiphase material. It is also shown that the conductivity is not related to protonic mobility. A density functional theory computational approach provides a theoretical justification for these new results, related to the high energetic costs associated with oxygen vacancy formation. This journal is

  19. Determination of boron in aqueous solutions by solid state nuclear track detectors technique, using a filtered neutron beam

    Moraes, M.A.P.V. de; Pugliesi, R.; Khouri, M.T.F.C.

    1985-11-01

    The solid state nuclear track detectors technique has been used for determination of boron in aqueous solutions, using a filtered neutron beam. The particles tracks from the 10 B(n,α)Li 7 reaction were registered in the CR-39 film, chemically etched in a (30%) KOH solution 70 0 C during 90 minutes. The obtained results showed the usefulness of this technique for boron determination in the ppm range. The inferior detectable limit was 9 ppm. The combined track registration efficiency factor K has been evaluated in the solutions, for the CR-39 detector and its values is K= (4,60 - + 0,06). 10 -4 cm. (Author) [pt

  20. High-pressure densified solid solutions of alkaline earth hexaborides (Ca/Sr, Ca/Ba, Sr/Ba) and their high-temperature thermoelectric properties

    Gürsoy, M.; Takeda, M.; Albert, B.

    2015-01-01

    Solid solutions of alkaline earth hexaborides were synthesized and densified by spark plasma sintering at 100 MPa. The high-temperature thermoelectric properties (Seebeck coefficients, electrical and thermal diffusivities, heat capacities) were measured between room temperature and 1073 K. CaB 6 , SrB 6 , BaB 6 and the ternary hexaborides Ca x Sr 1−x B 6 , Ca x Ba 1−x B 6 , Sr x Ba 1−x B 6 (x = 0.25, 0.5, 0.75) are n-type conducting compounds over the whole compositional and thermal ranges. The values of the figure of merit ZT for CaB 6 (ca. 0.3 at 1073 K) were found to be significantly increased compared to earlier investigations which is attributed to the densification process. - Highlights: • Solid solutions of alkaline earth hexaborides were synthesized. • High-temperature thermoelectric properties of mixed calcium borides are excellent. • Spark plasma source densification results in high ZT values. • Borides are rare-earth free and refractory materials

  1. Bulk diffusion and solubility of silver and nickel in lead, lead-silver and lead-nickel solid solutions

    Amenzou-Badrour, H.; Moya, G.; Bernardini, J.

    1988-01-01

    The results of a study of solubility and bulk diffusion of /sup 110/Ag and /sup 63/Ni in lead, lead-silver and lead-nickel solid solutions in the temperature range 220 to 88 0 C are reported. Owing to the low solubility of silver and nickel in lead, Fick's solution corresponding to the boundary condition of a constant concentration of solute at the surface has been used. Depth profile concentration analysis suggests a fundamental difference between the diffusion mechanisms of silver and nickel. Since silver penetration profiles in pure lead give diffusion coefficients independent of the penetration depth and silver concentration, it is suggested that slight decreases of silver diffusivity in lead-silver solid solutions have no significance. This implies that the interstitial silver atoms do not associate significantly with each other to form Ag-Ag dimers. In contrast, different behaviors of /sup 63/Ni depth profile concentration in pure lead and saturated PbNi solid solutions agree with a Ni-Ni interaction leading to the formation of less mobile dimers near the surface in pure lead

  2. Simple thermodynamic model of the extension of solid solution of Cu-Mo alloys processed by mechanical alloying

    Aguilar, C.; Guzman, D.; Rojas, P.A.; Ordonez, Stella; Rios, R.

    2011-01-01

    Highlights: → Extension of solid solution in Cu-Mo systems achieved by mechanical alloying. → Simple thermodynamic model to explain extension of solid solution of Mo in Cu. → Model gives results that are consistent with the solubility limit extension reported in other works. - Abstract: The objective of this work is proposing a simple thermodynamic model to explain the increase in the solubility limit of the powders of the Cu-Mo systems or other binary systems processed by mechanical alloying. In the regular solution model, the effects of crystalline defects, such as; dislocations and grain boundary produced during milling were introduced. The model gives results that are consistent with the solubility limit extension reported in other works for the Cu-Cr, Cu-Nb and Cu-Fe systems processed by mechanical alloying.

  3. Convergent solid-phase and solution approaches in the synthesis of the cysteine-rich Mdm2 RING finger domain.

    Vasileiou, Zoe; Barlos, Kostas; Gatos, Dimitrios

    2009-12-01

    The RING finger domain of the Mdm2, located at the C-terminus of the protein, is necessary for regulation of p53, a tumor suppressor protein. The 48-residues long Mdm2 peptide is an important target for studying its interaction with small anticancer drug candidates. For the chemical synthesis of the Mdm2 RING finger domain, the fragment condensation on solid-phase and the fragment condensation in solution were studied. The latter method was performed using either protected or free peptides at the C-terminus as the amino component. Best results were achieved using solution condensation where the N-component was applied with the C-terminal carboxyl group left unprotected. The developed method is well suited for large-scale synthesis of Mdm2 RING finger domain, combining the advantages of both solid-phase and solution synthesis. (c) 2009 European Peptide Society and John Wiley & Sons, Ltd.

  4. Chromium–tungsten–titanium mixed oxides solid catalyst for fatty acid methyl ester synthesis from palm fatty acid distillate

    Wan, Zuraida; Hameed, B.H.

    2014-01-01

    Highlights: • Chromium–tungsten–titanium mixed oxides as solid catalyst. • Catalyst used for esterification of palm fatty acid distillate to methyl esters. • The maximum methyl ester content is 83%. • Catalyst has shown good activity and can be recycled for 4 times. - Abstract: Chromium–tungsten–titanium mixed oxides solid catalysts were prepared and evaluated in the esterification of palm fatty acid distillate (PFAD) to produce fatty acid methyl ester (FAME). Esterification was conducted in a batch reactor at 110–200 °C temperature ranges. The catalysts were characterized by several techniques such as BET, TEM, FTIR, TGA, XRD, EDX and SEM. The treatment conditions during catalyst preparation, effect of reaction parameters, leaching of the active species and the recycled use of the catalyst were investigated. The catalyst with formula CrWTiO 2 was found to be the most active with maximum FAME content of 83% obtained at best reaction conditions of 170 °C for 3 h, 2:1 (methanol to oil molar ratio) and 2 wt.% catalyst dosage. The catalyst can be recycled for 4 times. The results revealed CrWTiO 2 good potentials for use in esterification of high acid value oil

  5. A novel Canadian solution for processing and disposal of mixed liquid wastes

    Suryanarayan, S.; Husain, A.; Husain, S.; Grey, M.; Elwood, C.; White, T.; Wigle, K.

    2011-01-01

    In 2009, Bruce Power contracted with Kinectrics for the disposal of its accumulated mixed liquid waste (MLW) inventory. The waste consists of solvent, PCB (Poly Chlorinated Biphenyls) and non-PCB contaminated oils and aqueous waste drums. The radioactivity in the wastes is principally due to cobalt-60, cesium-137 and tritium. Historically, MLW drums originating from Canadian utilities were shipped to a licensed US facility for destruction via incineration. This option is relatively expensive considering the significant logistics and destruction costs involved. In addition, restrictions now apply on importation of PCB containing wastes in to the US. Because of this, Kinectrics developed a wholly Canadian solution for the disposal of the MLW. Disposal of Bruce Power's MLW was conceived to be carried out in three phases. Phase 1: Develop an overall plan for disposal of the accumulated wastes, Phase 2: Dispose the PCB oil waste drums (highest priority), and Phase 3: Dispose all other waste drums. Phases 1 & 2 have been completed and Phase 3 is currently underway with 17 drums having been disposed so far. A description of the key activities undertaken to date are described in this paper. This work sets the stage for the future management of MLW based exclusively or largely on disposal within Canada. All key technical, regulatory and logistical issues pertaining to the receipt, handling, processing and shipment of the wastes were addressed. Equipment was installed for basic processing of the incoming wastes. Based on Pathways methodology, it was shown that the wastes can be shipped to unlicensed facilities within Canada without exceeding the 10 μSv per annum exposure to the critical individual. Despite this and for compliance with ALARA, wastes exceeding self-imposed threshold levels of radioactivity will be solidified and shipped for storage as radioactive waste. (author)

  6. A novel Canadian solution for processing and disposal of mixed liquid wastes

    Suryanarayan, S.; Husain, A. [Kinectrics Inc., Toronto, ON (Canada); Husain, S.; Grey, M. [Candesco, Toronto, ON (Canada); Elwood, C.; White, T.; Wigle, K. [Bruce Power, Tiverton, ON (Canada)

    2011-07-01

    In 2009, Bruce Power contracted with Kinectrics for the disposal of its accumulated mixed liquid waste (MLW) inventory. The waste consists of solvent, PCB (Poly Chlorinated Biphenyls) and non-PCB contaminated oils and aqueous waste drums. The radioactivity in the wastes is principally due to cobalt-60, cesium-137 and tritium. Historically, MLW drums originating from Canadian utilities were shipped to a licensed US facility for destruction via incineration. This option is relatively expensive considering the significant logistics and destruction costs involved. In addition, restrictions now apply on importation of PCB containing wastes in to the US. Because of this, Kinectrics developed a wholly Canadian solution for the disposal of the MLW. Disposal of Bruce Power's MLW was conceived to be carried out in three phases. Phase 1: Develop an overall plan for disposal of the accumulated wastes, Phase 2: Dispose the PCB oil waste drums (highest priority), and Phase 3: Dispose all other waste drums. Phases 1 & 2 have been completed and Phase 3 is currently underway with 17 drums having been disposed so far. A description of the key activities undertaken to date are described in this paper. This work sets the stage for the future management of MLW based exclusively or largely on disposal within Canada. All key technical, regulatory and logistical issues pertaining to the receipt, handling, processing and shipment of the wastes were addressed. Equipment was installed for basic processing of the incoming wastes. Based on Pathways methodology, it was shown that the wastes can be shipped to unlicensed facilities within Canada without exceeding the 10 μSv per annum exposure to the critical individual. Despite this and for compliance with ALARA, wastes exceeding self-imposed threshold levels of radioactivity will be solidified and shipped for storage as radioactive waste. (author)

  7. Structure-property relationships of new bismuth and lead oxide based perovskite ternary solid solutions

    Dwivedi, Akansha

    Two new bismuth and lead oxide based perovskite ternary solid solutions, namely xBi(Zn1/2Ti1/2)O3-yPbZrO3-zPbTiO3 [xBZT-yPZ-zPT] and xBi(Mg1/2Ti1/2)O3-yBi(Zn 1/2Ti1/2)O3-zPbTiO3 [xBMT-yBZT-zPT] have been developed and their structural and electrical properties have been determined. Various characterization techniques such as X-ray diffraction, calorimetery, electron microscopy, dielectric and piezoelectric measurements have been performed to determine the details of the phase diagram, crystal structure, and domain structure. The selection of these materials is based on the hypothesis that the presence of BZT-PT (Case I ferroelectric (FE)) will increase the transition temperature of MPB systems BMT-PT (Case II FE), and PZ-PT (Case III FE), and subsequently a MPB will be observed in the ternary phase diagrams. The Case I, II, and III classification has been outlined by Stringer et al., is on the basis of the transition temperatures (TC) behavior with composition in the Bi and Pb oxide based binary systems. Several pseudobinary lines have been investigated across the xBZT-yPZ-zPT ternary phase diagram which exhibit varied TC behavior with composition, showing both Case I- and Case III-like TC trends in different regions. A MPB between rhombohedral to tetragonal phases has been located on a pseudobinary line 0.1BZT-0.9[xPT-(1-x)PZ]. Compositions near MPB exhibit mainly soft PZT-like properties with the TC around 60°C lower than the unmodified PZT near its MPB. Electrical properties are reported for the MPB composition, TC = 325°C, Pr = 35 microC/cm2, d33 = 300 pC/N and kP =0.45. Rhombohedral compositions show diffuse phase transition with small frequency dispersion, similar to relaxors. Two transition peaks in the permittivity as well as in the latent heat has been observed in some compositions near the BZT-PT binary. This leads to the speculation for the existence of miscibility gap in the solid solutions in these regions. Transmission electron microscopy (TEM

  8. Kinetics and thermodynamics of the dissolution of Th1-xMxO2 solid solutions (M = U, Pu)

    Hubert, S.; Heisbourg, G.; Dacheux, N.; Moisy, Ph.; Purans, J.

    2004-01-01

    Kinetics of the dissolution of Th 1-x M x O 2 (M = U, Pu) solid solutions was investigated as a function of several chemical parameters such as pH, substitution ratio, temperature, ionic strength, and electrolyte. Several compositions of Th 1-x U x O 2 and Th 1-x Pu x O 2 were synthesized and characterized before and after leaching by using several methods such as XRD, EXAFS, BET, PIXE, SEM, and XPS. Leaching tests were performed in nitric, hydrochloric or sulfuric media and groundwater. The normalized dissolution rates were evaluated for Th 1-x U x O 2 , and Th 0.88 Pu 0.12 O 2 leading to the determination of the partial order related to the proton concentration, n, and to the corresponding normalized dissolution rate constant at pH = 0, k'T. While for Th enriched solids, the solid solutions Th 1-x U x O 2 have the same dissolution behaviour than ThO 2 with a partial order n ∼ 0.3, in the case of uranium enriched solids, Th 1-x U x O 2 has the same dissolution behaviour than UO 2 with a partial order of n = 1, indicating that uranium oxidation rate becomes the limiting step of the dissolution process. The stoichiometry of the release of both actinides (U or Pu, Th) was verified until the precipitation of thorium occurred in the leachate for pH > 2, while uranium was released in the solution as an uranyl form. For uranium enriched solid solutions, thermodynamic equilibrium was reached after 100 days, and solubility constant of secondary phase was determined. In the case of Th 1-x Pu x O 2 , the dissolution behaviour is similar to that of ThO 2 , but only kinetic aspect of the dissolution can be studied. From the analysis of XPS and EXAFS data on leached and un-leached Th 1-x U x O 2 samples, the dissolution mechanism of solid solutions was explained and will be discussed. The role of the electrolytes on the dissolution of the solid solutions is discussed. Kinetics parameters of dissolution are also given in groundwater and in neutral media

  9. Development of a mixed culture chain elongation process based on municipal solid waste and ethanol

    Grootscholten, T.I.M.

    2013-01-01

    Keywords: mixed culture fermentation; Carboxylates; Caproate; Heptanoate; ethanol; OFMSW

    To reduce dependence on oil, alternative fuel and chemical production processes are investigates. In this thesis, we investigated the production of medium chain fatty acids (MCFAs) using an anaerobic

  10. Partitioning of rhodium and ruthenium between Pd–Rh–Ru and (Ru,Rh)O{sub 2} solid solutions in high-level radioactive waste glass

    Sugawara, Toru, E-mail: toru@gipc.akita-u.ac.jp [Center for Engineering Science, Akita University, 1-1, Tegatagakuenmachi, Akita City, Akita 010-8502 (Japan); Ohira, Toshiaki [Center for Engineering Science, Akita University, 1-1, Tegatagakuenmachi, Akita City, Akita 010-8502 (Japan); Komamine, Satoshi; Ochi, Eiji [Research and Development Department, Reprocessing Business Division, Japan Nuclear Fuel Limited, 4-108, Okitsuke, Obuchi, Rokkasho-mura, Aomori 039-3212 (Japan)

    2015-10-15

    The partitioning of rhodium and ruthenium between Pd–Rh–Ru alloy with a face-centered cubic (FCC) structure and (Ru,Rh)O{sub 2} solid solution has been investigated between 1273 and 1573 K at atmospheric oxygen fugacity. The rhodium and ruthenium contents in FCC increase, while the RhO{sub 2} content in (Ru,Rh)O{sub 2} decreases with increasing temperature due to progressive reduction of the system. Based on the experimental results and previously reported thermodynamic data, the thermodynamic mixing properties of FCC phase and (Ru,Rh)O{sub 2} have been calibrated in an internally consistent manner. Phase equilibrium of platinum grope metals in an HLW glass was calculated by using the obtained thermodynamic parameters.

  11. NMR study of the dynamics of cationic gemini surfactant 14-2-14 in mixed solutions with conventional surfactants.

    Jiang, Yan; Lu, Xing-Yu; Chen, Hong; Mao, Shi-Zhen; Liu, Mai-Li; Luo, Ping-Ya; Du, You-Ru

    2009-06-18

    Three kinds of conventional surfactants, namely, two nonionic surfactants [polyethylene glycol (23) lauryl ether (Brij-35) and Triton X-100 (TX-100)], one cationic surfactant [n-tetradecyltrimethyl ammonium bromide (TTAB)], and an anionic surfactant [sodium n-dodecyl sulfate (SDS)}, were mixed into the quaternary ammonium gemini surfactant [C(14)H(29)N(+)(CH(3))(2)](2)(CH(2))(2).2Br(-) (14-2-14) in aqueous solution. The exchange rate constants between 14-2-14 molecules in the mixed micelles and those in the bulk solution were detected using two nuclear magnetic resonance (NMR) methods: one-dimensional (1D) line shape analysis and two-dimensional (2D) exchange spectroscopy (EXSY). The results obtained from these two methods were consistent. Both showed that mixing a nonionic conventional surfactant, either Brij-35 or TX-100, enhanced the exchange process between the 14-2-14 molecules in the mixed micelles and those in the bulk solution. In contrast, the anionic surfactant SDS and the cationic surfactant TTAB slowed the process slightly.

  12. Thermal and solutal stratification in mixed convection three-dimensional flow of an Oldroyd-B nanofluid

    Tasawar Hayat

    Full Text Available This paper investigates the double stratified effects in mixed convection three-dimensional flow of an Oldroyd-B nanofluid. The flow is due to a bidirectional stretching surface. Mathematical analysis is carried out using the temperature and concentration stratification effects. Brownian motion, thermophoresis and chemical reaction effects are also considered. The governing nonlinear boundary layer equations are first converted into the dimensionless ordinary differential equations and then solved for the convergent series solutions of velocity, temperature and nanoparticles concentration. Convergence analysis of the obtained series solutions is also checked and verified. Effects of various emerging parameters are studied in details. Numerical values of local Nusselt and Sherwood numbers are tabulated and analyzed. It is noticed that the impact of mixed convection parameter on temperature and nanoparticles concentration is quite similar. Both temperature and nanoparticles concentration are reduced for larger mixed convection parameter. Keywords: Three-dimensional flow, Oldroyd-B fluid, Nanoparticles, Mixed convection, Thermal and solutal stratification, Chemically reactive species

  13. Direct Succinic Acid Production from Minimally Pretreated Biomass Using Sequential Solid-State and Slurry Fermentation with Mixed Fungal Cultures

    Jerico Alcantara

    2017-06-01

    Full Text Available Conventional bio-based succinic acid production involves anaerobic bacterial fermentation of pure sugars. This study explored a new route for directly producing succinic acid from minimally-pretreated lignocellulosic biomass via a consolidated bioprocessing technology employing a mixed lignocellulolytic and acidogenic fungal co-culture. The process involved a solid-state pre-fermentation stage followed by a two-phase slurry fermentation stage. During the solid-state pre-fermentation stage, Aspergillus niger and Trichoderma reesei were co-cultured in a nitrogen-rich substrate (e.g., soybean hull to induce cellulolytic enzyme activity. The ligninolytic fungus Phanerochaete chrysosporium was grown separately on carbon-rich birch wood chips to induce ligninolytic enzymes, rendering the biomass more susceptible to cellulase attack. The solid-state pre-cultures were then combined in a slurry fermentation culture to achieve simultaneous enzymatic cellulolysis and succinic acid production. This approach generated succinic acid at maximum titers of 32.43 g/L after 72 h of batch slurry fermentation (~10 g/L production, and 61.12 g/L after 36 h of addition of fresh birch wood chips at the onset of the slurry fermentation stage (~26 g/L production. Based on this result, this approach is a promising alternative to current bacterial succinic acid production due to its minimal substrate pretreatment requirements, which could reduce production costs.

  14. The effect of random matter density perturbations on the large mixing angle solution to the solar neutrino problem

    Guzzo, M. M.; Holanda, P. C.; Reggiani, N.

    2003-08-01

    The neutrino energy spectrum observed in KamLAND is compatible with the predictions based on the Large Mixing Angle realization of the MSW (Mikheyev-Smirnov-Wolfenstein) mechanism, which provides the best solution to the solar neutrino anomaly. From the agreement between solar neutrino data and KamLAND observations, we can obtain the best fit values of the mixing angle and square difference mass. When doing the fitting of the MSW predictions to the solar neutrino data, it is assumed the solar matter do not have any kind of perturbations, that is, it is assumed the the matter density monothonically decays from the center to the surface of the Sun. There are reasons to believe, nevertheless, that the solar matter density fluctuates around the equilibrium profile. In this work, we analysed the effect on the Large Mixing Angle parameters when the density matter randomically fluctuates around the equilibrium profile, solving the evolution equation in this case. We find that, in the presence of these density perturbations, the best fit values of the mixing angle and the square difference mass assume smaller values, compared with the values obtained for the standard Large Mixing Angle Solution without noise. Considering this effect of the random perturbations, the lowest island of allowed region for KamLAND spectral data in the parameter space must be considered and we call it very-low region.

  15. Comparison of ethylcellulose matrix characteristics prepared by solid dispersion technique or physical mixing

    Fatemeh Sadeghi

    2003-07-01

    Full Text Available The characteristics of ethylcellulose matrices prepared from solid dispersion systems were compared with those prepared from physical mixture of drug and polymer. Sodium diclofenac was used as a model drug and the effect of the drug:polymer ratio and the method of matrix production on tablet crushing strength, friability, drug release profile and drug release mechanism were evaluated. The results showed that increasing the polymer content in matrices increased the crushing strengths of tablets. However the friability of tablets was independent of polymer content. Drug release rate was greatly affected by the amount of polymer in the matrices and considerable decrease in release rate was observed by increasing the polymer content. It was also found that the type of mixture used for matrix production had great influence on the tablet crushing strength and drug release rate. Matrices prepared from physical mixtures of drug and polymer was harder than those prepared from solid dispersion systems, but their release rates were considerably faster. This phenomenon was attributed to the encapsulation of drug particles by polymer in matrices prepared from solid dispersion system which caused a great delay in diffusion of the drug through polymer and made diffusion as a rate retarding process in drug release mechanism.

  16. Preparation, structural, dielectric and magnetic properties of LaFeO3–PbTiO3 solid solutions

    Ivanov, S.A.; Tellgren, R.; Porcher, F.; Ericsson, T.; Mosunov, A.; Beran, P.; Korchagina, S.K.; Kumar, P. Anil; Mathieu, R.; Nordblad, P.

    2012-01-01

    Highlights: ► Solid-solutions of (1−x)LaFeO 3 –(x)PbTiO 3 were synthesized by solid-state reaction. ► XRPD and NPD evidence orthorhombic (x 0.8) crystal structures. ► LaFeO 3 -rich compositions order antiferromagnetically (x 3 -rich compositions exhibit ferroelectric order (x larger than 0.8). ► Magnetic and dielectric (relaxor) ordering coexist near room-temperature around x = 0.4. -- Abstract: Solid solutions of (1−x)LaFeO 3 –(x)PbTiO 3 (0 3+ cations in the B-site with propagation vector k = (0,0,0). Based on the obtained experimental data, a combined structural and magnetic phase diagram has been constructed. The factors governing the structural, dielectric and magnetic properties of (1−x)LaFeO 3 –(x)PbTiO 3 solid solutions are discussed, as well as their possible multiferroicity.

  17. Ionic conductivity of LISICON solid solutions, Li 2+2 xZn 1- xGeO 4

    Bruce, P. G.; West, A. R.

    1982-10-01

    The conductivity of LISICON γII-type solid solutions of general formula Li 2+2 xZn 1- xGeO 4 (-0.36 class of Li + ion conductors, was measured over the temperature range ˜25 to 300°C. Conductivities appear to be very composition dependent near the stoichiometric composition x = 0, but less so in the range 0.15 ≲ x ≲ 0.87. It is shown that interstitial Li + ions rather than cation vacancies give rise to high conductivities. The solid electrolyte properties and possible applications of the solid solutions are evaluated. The LISICON composition, x = 0.75, decomposes readily above ˜300°C by precipitation of Li 4GeO 4, thereby limiting its possible usefulness, but compositions in the range x = 0.45 to 0.55 appear to be stable at all temperatures. However, irreversible decreases in conductivity (aging effects) occur on annealing, even at room temperature. The conductivity data of quenched samples give linear Arrhenius plots, but with anomalously high prefactors, over the range ˜25 to 130°C; at higher temperatures reversible changes of slope to lower activation energies occur. A variety of minor polymorphic transitions occur on annealing γII solid solutions below ˜300°C and their relationship to the conductivity was also determined.

  18. Mathematical modelling and numerical solution of swelling of cartilaginous tissues. Part II: Mixed hybrid finite element solution

    Malakpoor, K.; Kaasschieter, E.F.; Huyghe, J.M.R.J.

    2007-01-01

    The swelling and shrinkage of biological tissues are modelled by a four-component mixture theory [J.M. Huyghe and J.D. Janssen, Int. J. Engng. Sci. 35 (1997) 793-802; K. Malakpoor, E.F. Kaasschieter and J.M. Huyghe, Mathematical modelling and numerical solution of swelling of cartilaginous tissues.

  19. Morphology, composition, and mixing state of primary particles from combustion sources - crop residue, wood, and solid waste.

    Liu, Lei; Kong, Shaofei; Zhang, Yinxiao; Wang, Yuanyuan; Xu, Liang; Yan, Qin; Lingaswamy, A P; Shi, Zongbo; Lv, Senlin; Niu, Hongya; Shao, Longyi; Hu, Min; Zhang, Daizhou; Chen, Jianmin; Zhang, Xiaoye; Li, Weijun

    2017-07-11

    Morphology, composition, and mixing state of individual particles emitted from crop residue, wood, and solid waste combustion in a residential stove were analyzed using transmission electron microscopy (TEM). Our study showed that particles from crop residue and apple wood combustion were mainly organic matter (OM) in smoldering phase, whereas soot-OM internally mixed with K in flaming phase. Wild grass combustion in flaming phase released some Cl-rich-OM/soot particles and cardboard combustion released OM and S-rich particles. Interestingly, particles from hardwood (pear wood and bamboo) and softwood (cypress and pine wood) combustion were mainly soot and OM in the flaming phase, respectively. The combustion of foam boxes, rubber tires, and plastic bottles/bags in the flaming phase released large amounts of soot internally mixed with a small amount of OM, whereas the combustion of printed circuit boards and copper-core cables emitted large amounts of OM with Br-rich inclusions. In addition, the printed circuit board combustion released toxic metals containing Pb, Zn, Sn, and Sb. The results are important to document properties of primary particles from combustion sources, which can be used to trace the sources of ambient particles and to know their potential impacts in human health and radiative forcing in the air.

  20. Effectiveness of anode in a solid oxide fuel cell with hydrogen/oxygen mixed gases

    Kellogg, Isaiah D. [Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, MO (United States); Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO (United States); Koylu, Umit O. [Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, Rolla, MO (United States); Petrovsky, Vladimir; Dogan, Fatih [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO (United States)

    2009-06-15

    A porous Ni/YSZ cermet in mixed hydrogen and oxygen was investigated for its ability to decrease oxygen activity as the anode of a single chamber SOFC. A cell with a dense 300 {mu}m YSZ electrolyte was operated in a double chamber configuration. The Ni-YSZ anode was exposed to a mixture of hydrogen and oxygen of varying compositions while the cathode was exposed to oxygen. Double chamber tests with mixed gas on the anode revealed voltage oscillations linked to lowered power generation and increased resistance. Resistance measurements of the anode during operation revealed a Ni/NiO redox cycle causing the voltage oscillations. The results of these tests, and future tests of similar format, could be useful in the development of single chamber SOFC using hydrogen as fuel. (author)