Solid-matrix luminescence analysis
Hurtubise, R.J.
1993-01-15
Several interactions with lumiphors adsorbed on filter paper were elucidated from experiments with moisture, modulus and heavy-atom salts. The data were interpreted using static and dynamic quenching models, heavy-atom theory, and a theory related to the modulus of paper. With cyclodextrin-salt matrices, it was shown that 10% [alpha]-cyclodextrin/NaCl was very effective for obtaining strong room-temperature fluorescence and moderate room-temperature phosphorescence from adsorbed stereoisomeric tetrols. Extensive photophysical information was obtained for the four tetrols on 10% [alpha]-cyclodextrin/NaCl. The photophysical information acquired was used to develop a method for characterizing two of the tetrols. Work with model compounds adsorbed on deuterated sodium acetate showed that C-H vibrations in the undeuterated sodium acetate were not responsible for the deactivation of the excited triplet state in the model phosphors investigated. A considerable amount of solution luminescence and solid-matrix luminescence data were compared. The most important finding was that in several cases the room-temperature solid-matrix luminescence quantum yields were greater than the solution low-temperature quantum yield values.
Ma, D.Q. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Jiao, W.T. [College of Education, Hebei Normal University of Science and Technology, Qinhuangdao 066004 (China); Zhang, Y.F. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Hebei Vocational and Technical College of Building Materials, Qinhuangdao 066004 (China); Wang, B.A.; Li, J.; Zhang, X.Y. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Ma, M.Z., E-mail: mz550509@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Liu, R.P. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China)
2015-03-05
Highlights: • Hardness of dendrite of TiZr-based BMGMCs increases. • Strong work-hardening behavior is obtained after solid solution strengthening. • Lattice distortions of dendrite suffering from rapid cooling are detected. - Abstract: A series of TiZr-based bulk metallic glass matrix composites (BMGMCs) with distinguished mechanical properties are successfully fabricated by adding different volume fractions of Ta (Ti{sub 38.8}Zr{sub 28.8}Cu{sub 6.2}Be{sub 16.2}Nb{sub 10} as the basic composition, denoted as Ta{sub 0.0}–Ta{sub 8.0}). Along with the growth of precipitated phase, typical dendritic morphology is fully developed in the TiZr-based BMGMCs of Ta{sub 8.0}. Energy-dispersive spectrometry analysis of the dendrites and glass matrix indicates that the metallic elements of Nb and Ta should preferentially form solid solution into dendrites. The chaotic structure of high-temperature precipitate phase is trapped down by the rapid cooling of the copper-mould. The detected lattice distortions in the dendrites are attributed to the strong solid solution strengthening of the metallic elements of Ti, Zr, Nb, and Ta. These lattice distortions increase the resistance of the dislocation motion and pin the dislocations, thus the strength and hardness of dendrite increase. Dendrites create a strong barrier for the shear band propagation and generate multiple shear bands after solid solution strengthening, thereby providing the TiZr-based BMGMCs with greatly improved capacity to sustain plastic deformation and resistance to brittle fracture. Thus, the TiZr-based BMGMCs possess distinguished work-hardening capability. Among these TiZr-based BMGMCs, the sample Ta{sub 0.5} possesses the largest plastic strain (ε{sub p}) at 20.3% and ultimate strength (σ{sub max}) of 2613 MPa during compressive loading. In addition, the sample of Ta{sub 0.5} exhibits work-hardening up to an ultrahigh tensile strength of 1680 MPa during the tensile process, and then progressively
The Constrained Solutions of Two Matrix Equations
An Ping LIAO; Zhong Zhi BAI
2002-01-01
We study the symmetric positive semidefinite solution of the matrix equation AX1AT +BX2BT = C, where A is a given real m × n matrix, B is a given real m × p matrix, and C is a givenreal m × m matrix, with m, n, p positive integers; and the bisymmetric positive semidefinite solutionof the matrix equation DTXD = C, where D is a given real n × m matrix, C is a given real m × mmatrix, with m, n positive integers. By making use of the generalized singular value decomposition, wederive general analytic formulae, and present necessary and sufficient conditions for guaranteeing theexistence of these solutions.
Modeling supercritical fluid extraction process involving solute-solid interaction
Goto, M.; Roy, B. Kodama, A.; Hirose, T. [Kumamoto Univ., Kumamoto (Japan)
1998-04-01
Extraction or leaching of solute from natural solid material is a mass transfer process involving dissolution or release of solutes from a solid matrix. Interaction between the solute and solid matrix often influences the supercritical fluid extraction process. A model accounting for the solute-solid interaction as well as mass transfer is developed. The BET equation is used to incorporate the interaction and the solubility of solutes into the local equilibrium in the model. Experimental data for the supercritical extraction of essential oil and cuticular wax from peppermint leaves are successfully analyzed by the model. The effects of parameters on the extraction behavior are demonstrated to illustrate the concept of the model. 18 refs., 5 figs., 1 tab.
Growth of Solid Solution Crystals
Lehoczky, S. L.; Szofran, F. R.; Holland, L. R.
1985-01-01
The major objective of this program is to determine the conditions under which single crystals of solid solutions can be grown from the melt in a Bridgman configuration with a high degree of chemical homogeneity. The central aim is to assess the role of gravity in the growth process and to explore the possible advantages for growth in the absence of gravity. The alloy system being investigated is the solid solution semiconductor with x-values appropriate for infrared detector applications in Hg sub (1-x) Cd sub x Te the 8 to 14 micro m wavelength region. Both melt and Te-solvent growth are being considered. The study consists of an extensive ground-based experimental and theoretical research effort followed by flight experimentation where appropriate. Experimental facilities have been established for the purification, casting, and crystal growth of the alloy system. Facilities have been also established for the metallurgical, compositional, electric and optical characterization of the alloys. Crystals are being grown by the Bridgman-Stockbarger method and are analyzed by various experimental techniques to evaluate the effects of growth conditions on the longitudinal and radial compositional variations and defect densities in the crystals.
Accelerated Solutions for Transcendental Stiffness Matrix Eigenproblems
F.W. Williams
1996-01-01
Full Text Available This article outlines many existing and forthcoming methods that can be used alone, or in various combinations, to accelerate the solutions of the transcendental stiffness matrix eigenproblems that arise when the stiffness matrix is assembled from exact member stiffnesses, which are obtained by solving the member differential equations exactly. Thus distributed member mass and/or the flexural effect of axial loading are incorporated exactly, and the solutions are the natural frequencies for vibration problems or the critical load factors for buckling problems.
Dichromatic laser photolysis of eosin in solid gelatinous matrix
Sizykh, A. G.; Slyusareva, E. A.
2004-05-01
The laser irradiation of the thin films of solid solution of eosin in gelatinous matrix in the first and some upper dyes absorption bands leads to decrease of films optical density due to reaction of photoreduction. In the paper the kinetic of photoreduction of the dye eosin K in polymeric matrix in three cases of irradiation was experimentally investigated: a) irradiation by N2 laser (λ=337nm, second band of absorption, π=2 nsec, repetition rate-100 Hz, average power-2,2 mW), b) irradiation by Ar-laser (λ=488 nm, first band of absorption, 6,5-12 mW), c) under a simultaneous action of both Ar and N2-lasers. It was demonstrated that the most effective reaction of photoreduction took place in case of direct populating of upper singlet states with probable following nonradiative transition into equienergetic triplet states (energy ranges 35000-45000 sm-1).
Solid-matrix luminescence analysis. Progress report, 15 June 1992--31 October 1994
Hurtubise, R.J.
1994-12-31
Interaction models were developed for moisture effects on room-temperature fluorescence (RTF) and room-temperature phosphorescence (RTP) of compounds adsorbed on filter paper. The models described both dynamic and matrix quenching and also related the Young modulus of filter paper to quenching of phosphor on moist filter paper. Photophysical parameters for lumiphors in solution and on solid matrices were compared. Results showed that for some compounds, solid-matrix luminescence has greater analytical potential than solution luminescence. Also, the solid-matrix systems into one of two categories depending on how the intersystem crossing rate constants change with temperature. The first study was carried out on effects of heavy atom on solid-matrix luminescence. With some heavy atoms, maximum solid-matrix phosphorescence quantum yield was obtained at room temperature, and there was no need to use low temperature to obtain a strong phosphorescence signal. By studying solid-matrix luminescence properties of phosphors adsorbed on sodium acetate and deuterated sodium acetate, an interaction model was developed for p-aminobenzoic acid anion adsorbed on sodium acetate. It was shown that the energy-gap law was applicable to solid-matrix luminescence. Also, deuterated phenanthrene and undeuterated phenanthrene were used to study nonradiative transition of excited triplet state of adsorbed phosphors. Heat capacities of several solid matrices were obtained vs temperature and related to vibrational coupling of solid matrix with phosphor. Photophysical study was performed on the hydrolysis products of benzo(a)pyrene-DNA adducts. Also, an analytical method was developed for tetrols in human lung fractions. Work was initiated on the formation of room temperature glasses with glucose and trehalose. Also, work has begun for the development of an oxygen sensor by measuring the RTP quenching of triphenylene on filter paper.
Solution-solid-solid mechanism: superionic conductors catalyze nanowire growth.
Wang, Junli; Chen, Kangmin; Gong, Ming; Xu, Bin; Yang, Qing
2013-09-11
The catalytic mechanism offers an efficient tool to produce crystalline semiconductor nanowires, in which the choice, state, and structure of catalysts are active research issues of much interest. Here we report a novel solution-solid-solid (SSS) mechanism for nanowire growth catalyzed by solid-phase superionic conductor nanocrystals in low-temperature solution. The preparation of Ag2Se-catalyzed ZnSe nanowires at 100-210 °C is exampled to elucidate the SSS model, which can be extendable to grow other II-VI semiconductor (e.g., CdSe, ZnS, and CdS) nanowires by the catalysis of nanoscale superionic-phase silver or copper(I) chalcogenides (Ag2Se, Ag2S, and Cu2S). The exceptional catalytic ability of these superionic conductors originates from their structure characteristics, known for high-density vacancies and fast mobility of silver or copper(I) cations in the rigid sublattice of Se(2-) or S(2-) ions. Insights into the SSS mechanism are provided based on the formation of solid solution and the solid-state ion diffusion/transport at solid-solid interface between catalyst and nanowire.
Polynomial Solutions to the Matrix Equation X−AXTB=C
Caiqin Song
2014-01-01
Full Text Available Solutions are constructed for the Kalman-Yakubovich-transpose equation X−AXTB=C. The solutions are stated as a polynomial of parameters of the matrix equation. One of the polynomial solutions is expressed by the symmetric operator matrix, controllability matrix, and observability matrix. Moreover, the explicit solution is proposed when the Kalman-Yakubovich-transpose matrix equation has a unique solution. The provided approach does not require the coefficient matrices to be in canonical form. In addition, the numerical example is given to illustrate the effectiveness of the derived method. Some applications in control theory are discussed at the end of this paper.
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 or...
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
Computer simulation of concentrated solid solution strengthening
Kuo, C. T. K.; Arsenault, R. J.
1976-01-01
The interaction forces between a straight edge dislocation moving through a three-dimensional block containing a random array of solute atoms were determined. The yield stress at 0 K was obtained by determining the average maximum solute-dislocation interaction force that is encountered by edge dislocation, and an expression relating the yield stress to the length of the dislocation and the solute concentration is provided. The magnitude of the solid solution strengthening due to solute atoms can be determined directly from the numerical results, provided the dislocation line length that moves as a unit is specified.
Chen, Qian; Lin, Yao; Tian, Yunfei; Wu, Li; Yang, Lu; Hou, Xiandeng; Zheng, Chengbin
2017-02-07
Sensitive quantification of mercury distribution in fish is challenging because of insufficient sensitivities of conventional analytical methods, the limited mass of organs (tens of micrograms to several milligrams), and dilution of analyte concentration from sample digestion. In this work, a simple and robust approach coupling multiwall carbon nanotubes assisted matrix solid-phase dispersion (MWCNTs-MSPD) to single-drop solution electrode glow discharge-induced cold vapor generation (SD-SEGD-CVG) was developed for the sensitive determination of mercury in limited amount of sample. Mercury species contained in a limited amount of sample can be efficiently extracted into a 100 μL of eluent by MWCNTs-MSPD, which are conveniently converted to Hg(0) by SD-SEGD-CVG and further transported to atomic fluorescence spectrometry for their determination. Therefore, analyte dilution resulted from sample preparation is avoided and sensitivity is significantly improved. On the basis of consumption of 1 mg of sample, a limit of detection of 0.01 μg L(-1) (0.2 pg) was obtained with relative standard deviations (RSDs) of 5.2% and 4.6% for 2 and 20 μg L(-1), respectively. The accuracy of the proposed method was validated by analysis of three Certified Reference Materials with satisfying results. To confirm that SD-SEGD-CVG-AFS coupling to MWCNTs-MSPD is a promising method to quantify mercury distribution in fish, this method was successfully applied for the sensitive determination of mercury in seven organs of common carps (muscle, gill, intestine, liver, gallbladder, brain, and eye) after dietary of mercury species. The proposed method provides advantages of minimum sample dilution, low blank, high sample introduction efficiency, high sensitivity, and minimum toxic chemicals and sample consumption.
Synthesis of solid solutions of perovskites
Dambekalne, M.Y.; Antonova, M.K.; Perro, I.T.; Plaude, A.V.
1986-03-01
The authors carry out thermographic studies, using a derivatograph, in order to understand the nature of the processes taking place during the synthesis of solid solutions of perovskites. Based on the detailed studies on the phase transformations occurring in the charges of the PSN-PMN solid solutions and on the selection of the optimum conditions for carrying out their synthesis, the authors obtained a powder containing a minimum quantity of the undesirable pyrochlore phase and by sintering it using the hot pressing method, they produced single phase ceramic specimens containing the perovskite phase alone with a density close to the theoretical value and showing zero apparent porosity and water absorption.
Constrained Solutions of a System of Matrix Equations
Qing-Wen Wang
2012-01-01
Full Text Available We derive the necessary and sufficient conditions of and the expressions for the orthogonal solutions, the symmetric orthogonal solutions, and the skew-symmetric orthogonal solutions of the system of matrix equations AX=B and XC=D, respectively. When the matrix equations are not consistent, the least squares symmetric orthogonal solutions and the least squares skew-symmetric orthogonal solutions are respectively given. As an auxiliary, an algorithm is provided to compute the least squares symmetric orthogonal solutions, and meanwhile an example is presented to show that it is reasonable.
Shrinking mechanism of a porous collagen matrix immersed in solution.
Chen, Po-Yang; Hsieh, Hsyue-Jen; Huang, Lynn L H
2014-12-01
The porous structure of collagen-based matrices enables the infiltration of cells both in in vitro and clinical applications. Reconstituted porous collagen matrices often collapse when they are in contact with aqueous solutions; however, the mechanism for the collapse of the pores is not understood. We, therefore, investigated the interactions between the collagen matrix and different solutions, and discuss the mechanisms for the change in microstructure of the matrix on immersing it in solution. When a dried collagen matrix was immersed in aqueous solutions, the matrix shrunk and pores close to the surface closed. The shrinkage ratio and thickness of the compact microstructure close to the superficial area decreased with increasing ethanol content in the solution. The original porous structure of the collagen matrix was preserved when the matrix was immersed in absolute ethanol. The shrinkage of a porous collagen matrix in contact with aqueous solutions was attributed to the liquid/gas interfacial tension. The average pore diameter of the matrix also significantly affected the shrinkage of the matrix. The shrinkage of the matrix, explained using the Young-Laplace equation, was found to result from the pressure drop, and especially in the pores located superficially, leading to the collapse of the matrix microstructure. The integrity of the porous microstructure allows better penetration of cells in medical applications. The numbers of NIH/3T3 fibroblasts penetrated through the hydrated Col/PBS porous collagen matrices pre-immersed in absolute ethanol with subsequent water and DMEM culture medium replacements were significantly higher than those through matrices hydrated directly in DMEM.
Magnetic Damping of Solid Solution Semiconductor Alloys
Szofran, Frank R.; Benz, K. W.; Croell, Arne; Dold, Peter; Cobb, Sharon D.; Volz, Martin P.; Motakef, Shariar
1999-01-01
The objective of this study is to: (1) experimentally test the validity of the modeling predictions applicable to the magnetic damping of convective flows in electrically conductive melts as this applies to the bulk growth of solid solution semiconducting materials; and (2) assess the effectiveness of steady magnetic fields in reducing the fluid flows occurring in these materials during processing. To achieve the objectives of this investigation, we are carrying out a comprehensive program in the Bridgman and floating-zone configurations using the solid solution alloy system Ge-Si. This alloy system has been studied extensively in environments that have not simultaneously included both low gravity and an applied magnetic field. Also, all compositions have a high electrical conductivity, and the materials parameters permit reasonable growth rates. An important supporting investigation is determining the role, if any, that thermoelectromagnetic convection (TEMC) plays during growth of these materials in a magnetic field. TEMC has significant implications for the deployment of a Magnetic Damping Furnace in space. This effect will be especially important in solid solutions where the growth interface is, in general, neither isothermal nor isoconcentrational. It could be important in single melting point materials, also, if faceting takes place producing a non-isothermal interface. In conclusion, magnetic fields up to 5 Tesla are sufficient to eliminate time-dependent convection in silicon floating zones and possibly Bridgman growth of Ge-Si alloys. In both cases, steady convection appears to be more significant for mass transport than diffusion, even at 5 Tesla in the geometries used here. These results are corroborated in both growth configurations by calculations.
ON SOLUTIONS OF MATRIX EQUATION AXAT + BYBT = C
Yuan-bei Deng; Xi-yan Hu
2005-01-01
By making use of the quotient singular value decomposition (QSVD) of a matrix pair,this paper establishes the necessary and sufficient conditions for the existence of and the expressions for the general solutions of the linear matrix equation AXAT + BYBT = C with the unknown X and Y, which may be both symmetric, skew-symmetric, nonnegative definite , positive definite or some cross combinations respectively. Also, the solutions of some optimal problems are derived.
On Suboptimal Solution of Antagonistic Matrix Games
Goryashko Alexander
2017-01-01
Full Text Available The paper examines resource allocation games such as Colonel Blotto and Colonel Lotto games with the goal to develop tractable method for building suboptimal solution in mixed strategies of these games without solving the relevant optimization problem. The foundation of proposed method lies in the specific combinatorial properties of the partition games. It turned out that as far as distribution of resource along battlefield is concerned that pure strategies participating in ε-optimal solution possessed specific structure. Numerical experiments showed that these specific structural peculiarities can be easily reproduced utilizing previously found combinatorial properties of partition. As a result, we get ε-optimal solution of partition games and support set mixed strategies can be computed in polynomial time.
Some Upper Matrix Bounds for the Solution of the Continuous Algebraic Riccati Matrix Equation
Zübeyde Ulukök
2013-01-01
Full Text Available We propose diverse upper bounds for the solution matrix of the continuous algebraic Riccati matrix equation (CARE by building the equivalent form of the CARE and using some matrix inequalities and linear algebraic techniques. Finally, numerical example is given to demonstrate the effectiveness of the obtained results in this work as compared with some existing results in the literature. These new bounds are less restrictive and provide more efficient results in some cases.
THE NEAREST BISYMMETRIC SOLUTIONS OF LINEAR MATRIX EQUATIONS
Zhen-yun Peng; Xi-yan Hu; Lei Zhang
2004-01-01
The necessary and sufficient conditions for the existence of and the expressions for bismmetric soutions of the matrix equation(Ⅰ)A1X1B1+A2X2B2+…AkXkBk=D,(Ⅱ)A1XB1+A2XB2+…+AkXBk=D and (Ⅲ)(A1XB1,A2XB2,…,AkXBK)=(D1,D2,…,Dk) are derived by using kronecker product and Moore-Penrose generalized inverse of matrices. In addition, in corresponding solution set of the matrix equations, the explicit expression of the nearest matrix to a given matrix in the Frobenius norm is given.Numerical methods and numerical experiments of finding the nearest solutions are also provided.
Matrix models with hard walls: geometry and solutions
Chekhov, L [Steklov Mathematical Institute, Moscow (Russian Federation); Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Poncelet Laboratoire International Franco-Russe, Moscow (Russian Federation); Department of Mathematics and Statistics, Concordia University, Montreal (Canada)
2006-07-14
We discuss various aspects of most general multisupport solutions to matrix models in the presence of hard walls, i.e., in the case where the eigenvalue support is confined to subdomains of the real axis. The structure of the solution at the leading order is described by semiclassical or generalized Whitham-Krichever hierarchies as in the unrestricted case. Derivatives of tau-functions for these solutions are associated with families of Riemann surfaces (with possible double points) and satisfy the Witten-Dijkgraaf-Verlinde-Verlinde equations. We then develop the diagrammatic technique for finding free energy of this model in all orders of the 't Hooft expansion in the reciprocal matrix size generalizing the Feynman diagrammatic technique for the Hermitian one-matrix model due to Eynard.
Matrix Kadomtsev-Petviashvili equation: matrix identities and explicit non-singular solutions
Sakhnovich, A L [Branch of Hydroacoustics, Marine Institute of Hydrophysics, National Academy of Sciences of Ukraine (Ukraine)
2003-05-09
A new version of the Baecklund-Darboux transformation for the matrix Kadomtsev-Petviashvili (KP) equation is used to construct and study explicit multi-parameter solutions and wavefunctions (in terms of the matrix exponents). A class of the self-adjoint non-singular solutions of KP I is introduced using the controllability notion from the system theory. A subclass of the rationally decaying self-adjoint non-singular solutions is studied, in particular. Several results prove new in the scalar case also.
Thermal transport investigation in a CNTs/solid matrix composite
Boulerouah, Aoumeur; Longuemart, Stéphane; Hus, Philippe; Sahraoui, Abdelhak Hadj
2013-02-01
The evolution of the thermal parameters of solid-solid composites based on carbon nanotubes (CNTs) (single-walled (SWNT) and multi-walled (MWNT)) were studied. A granular potassium bromide (KBr) material was chosen as a matrix. The evolutions of the dynamic thermal parameters (diffusivity, effusivity and conductivity) of the composites as a function of the weight fraction of the CNTs inclusions were obtained using the photoacoustic technique. The experimental evolution of the thermal conductivity of the composites with the CNTs loading showed two distinct behaviours, an increase up to around 2% of CNTs loading followed by a decrease. A heat transport model has been proposed to account for these two different observed trends providing a consistent explanation of the experimental data.
Ranks of the Common Solution to Six Quaternion Matrix Equations
Qing-wen Wang; Yan Zhou; Qin Zhang
2011-01-01
A new expression is established for the common solution to six classical linear quaternion matrix equations A1X = C1, XB1 = C3, A2X = C2, XB2 = C4, A3XB3 = C5, A4XB4 = C6 which was investigated recently by Wang, Chang and Ning (Q. Wang, H. Chang, Q. Ning, The common solution to six quaternion matrix equations with applications, Appl. Math. Comput. 195: 721-732 (2008)). Formulas are derived for the maximal and minimal ranks of the common solution to this system. Moreover, corresponding results on some special cases are presented. As an application, a necessary and sufficient condition is presented for the invariance of the rank of the general solution to this system. Some known results can be regarded as the special cases of the results in this paper.
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.
Growth of Solid Solution Single Crystals
Lehoczky, Sandor L.; Szofran, F. R.; Gillies, Donald C.
2001-01-01
The solidification of a solid solution semiconductor, having a wide separation between liquidus and solidus has been extensively studied in ground based, high magnetic field and Spacelab experiments. Two alloys of mercury cadmium telluride have been studied; with 80.0 mole percent of HgTe and 84.8 mole percent of HgTe respectively, the remainder being cadmium telluride. Such alloys are extremely difficult to grow by directional solidification on earth due to high solutal and thermal density differences that give rise to fluid flow and consequent loss of interface shape and composition. Diffusion controlled growth is therefore impossible to achieve in conventional directional solidification. The ground based experiments consisted of growing crystals in several different configurations of heat pipe furnaces, NASA's Advanced Automated Directional Solidification Furnace (AADSF), and a similar furnace incorporated in a superconducting magnet capable of operating at up to 5T. The first microgravity experiment took place during the flight of STS-62 in March 1994, with the AADSF installed on the second United States Microgravity Payload (USMP-2). The alloy was solidified at 3/4 inch per day over a 9 day period, and for the first time a detailed evaluation was performed correlating composition variations to measured residual acceleration. The second flight experiment took place in the fourth United States Microgravity Payload Mission (USMP-4) in November 1997. Due to contamination of the furnace system, analysis shows that the conditions prevailing during the experiment were quite different from the requirements requested prior to the mission. The results indicate that the sample did accomplish the desired objectives.
Orbifolds and Exact Solutions of Strongly-Coupled Matrix Models
Cordova, Clay; Popolitov, Alexandr; Shakirov, Shamil
2016-01-01
We find an exact solution to strongly-coupled matrix models with a single-trace monomial potential. Our solution yields closed form expressions for the partition function as well as averages of Schur functions. The results are fully factorized into a product of terms linear in the rank of the matrix and the parameters of the model. We extend our formulas to include both logarthmic and finite-difference deformations, thereby generalizing the celebrated Selberg and Kadell integrals. We conjecture a formula for correlators of two Schur functions in these models, and explain how our results follow from a general orbifold-like procedure that can be applied to any one-matrix model with a single-trace potential.
ANALYTIC SOLUTIONS OF MATRIX RICCATI EQUATIONS WITH ANALYTIC COEFFICIENTS
Curtain, Ruth; Rodman, Leiba
2010-01-01
For matrix Riccati equations of platoon-type systems and of systems arising from PDEs, assuming the coefficients are analytic or rational functions in a suitable domain, analyticity of the stabilizing solution is proved under various hypotheses. General results on analytic behavior of stabilizing so
Minimal solution of linear formed fuzzy matrix equations
Maryam Mosleh
2012-10-01
Full Text Available In this paper according to the structured element method, the $mimes n$ inconsistent fuzzy matrix equation $Ailde{X}=ilde{B},$ which are linear formed by fuzzy structured element, is investigated. The necessary and sufficient condition for the existence of a fuzzy solution is also discussed. some examples are presented to illustrate the proposed method.
Exact solution of some linear matrix equations using algebraic methods
Djaferis, T. E.; Mitter, S. K.
1977-01-01
A study is done of solution methods for Linear Matrix Equations including Lyapunov's equation, using methods of modern algebra. The emphasis is on the use of finite algebraic procedures which are easily implemented on a digital computer and which lead to an explicit solution to the problem. The action f sub BA is introduced a Basic Lemma is proven. The equation PA + BP = -C as well as the Lyapunov equation are analyzed. Algorithms are given for the solution of the Lyapunov and comment is given on its arithmetic complexity. The equation P - A'PA = Q is studied and numerical examples are given.
Compositional Segregation in Unidirectionally Solidified Solid Solution Crystals
Wang, J. C.
1983-01-01
A computer program was developed to model compositional segregation in unidrectionally solidified solid-solution-semiconducting crystals. The program takes into account the variations of the interface segregation constant and solidification rate with composition. Calculations are performed for the HgCdTe solid solution system that is compared with experimental data.
Forces between Hydrophobic Solids in Concentrated Aqueous Salt Solution
Mastropietro, Dean J; Ducker, William A.
2012-01-01
Much research has focused on the discovery and description of long-ranged forces between hydrophobic solids immersed in water. Here we show that the force between high contact-angle solids in concentrated salt solution (1 M KCl) agrees very well with van der Waals forces calculated from Lifshitz theory for separations greater than 5 nm. The hydrophobic solids are octadecyltrichlorosilane-coated glass, with an advancing contact angle of 108 degrees. Thus, in 1 M salt solution, it is unnecessar...
Radiation processes in crystal solid solutions
Gladyshev, Gennadi
2012-01-01
This is a monograph explaining processes occurring in two classes of crystal solids (metal alloys and doped alkali halide) under irradiation by various types of radiation (alpha, beta, gamma, X-radiations, ions). This e-book is a useful reference for advanced readers interested in the physics of radiation and solid state physics.
Solid lipid excipients - matrix agents for sustained drug delivery.
Rosiaux, Yvonne; Jannin, Vincent; Hughes, Sophie; Marchaud, Delphine
2014-08-28
Lipid excipients are attracting interest from drug developers due to their performance, ease of use, versatility and their potential to generate intellectual property through innovation in drug delivery particularly in the case of modifying drug release systems. Many articles have described the use of lipid excipients to develop matrix modified release dosage forms in a range of processing techniques, therefore a comprehensive review is timely to collect together and analyze key information. This review article focuses on the utility of lipid excipients in solid sustained drug delivery systems with emphasis on the efficiency and robustness of these systems with respect to: (i) the choice of the manufacturing process and impact on drug release, (ii) the fundamental drug release mechanisms, (iii) resistance of the drug formulation under physiological conditions and (iv) long-term stability. Understanding the functionality of these versatile excipients in formulation is elementary for the development of highly robust lipid-based sustained release medicines.
Matrix factorization for solutions of the Yang-Baxter equation
Chicherin, D
2015-01-01
We study solutions of the Yang-Baxter equation on a tensor product of an arbitrary finite-dimensional and an arbitrary infinite-dimensional representations of the rank one symmetry algebra. We consider the cases of the Lie algebra sl_2, the modular double (trigonometric deformation) and the Sklyanin algebra (elliptic deformation). The solutions are matrices with operator entries. The matrix elements are differential operators in the case of sl_2, finite-difference operators with trigonometric coefficients in the case of the modular double or finite-difference operators with coefficients constructed out of Jacobi theta functions in the case of the Sklyanin algebra. We find a new factorized form of the rational, trigonometric, and elliptic solutions, which drastically simplifies them. We show that they are products of several simply organized matrices and obtain for them explicit formulae.
Fluoride-conversion synthesis of homogeneous actinide oxide solid solutions
Silva, G W Chinthaka M [ORNL; Hunn, John D [ORNL; Yeamans, Charles B. [University of California, Berkeley; Cerefice, Gary S. [University of Nevada, Las Vegas; Czerwinski, Ken R. [University of Nevada, Las Vegas
2011-01-01
Here, a novel route to synthesize (U, Th)O2 solid solutions at a relatively low temperature of 1100 C is demonstrated. First, the separate actinide oxides reacted with ammonium bifluoride to form ammonium actinide fluorides at room temperature. Subsequently, this mixture was converted to the actinide oxide solid solution using a two-phased heat treatment, first at 610 C in static air, then at 1100 C in flowing argon. Solid solutions obeying Vegard s Law were synthesized for ThO2 content from 10 to 90 wt%. Microscopy showed that the (U, Th)O2 solid solutions synthesized with this method to have considerably high crystallinity and homogeneity, suggesting the suitability of material thus synthesized for sintering into nuclear fuel pellets at low temperatures.
Solid solution hardening of molecular crystals: tautomeric polymorphs of omeprazole.
Mishra, Manish Kumar; Ramamurty, Upadrasta; Desiraju, Gautam R
2015-02-11
In the context of processing of molecular solids, especially pharmaceuticals, hardness is an important property that often determines the manufacturing steps employed. Through nanoindentation studies on a series of omeprazole polymorphs, in which the proportions of the 5- and 6-methoxy tautomers vary systematically, we demonstrate that solid-solution strengthening can be effectively employed to engineer the hardness of organic solids. High hardness can be attained by increasing lattice resistance to shear sliding of molecular layers during plastic deformation.
Thermal vacancy formation energies of random solid solutions
Luo, H. B.; Hu, Q. M.; Du, J.; Yan, A. R.; Liu, J. P.
2017-01-01
Vacancy mechanism plays a dominant role in the atomic migration when a close-packed disordered alloy undergoes ordering transition. However, the calculation of thermal vacancy formation energies (VFEs) of random solid solutions is usually cumbersome due to the difficulty in considering various local atomic environments. Here, we propose a transparent way that combines coherent potential approximation and supercell-local cluster expansion to investigate VFEs of random solid solutions. This met...
Solid-matrix luminescence analysis. Progress report, 1 November 1991--15 January 1993
Hurtubise, R.J.
1993-01-15
Several interactions with lumiphors adsorbed on filter paper were elucidated from experiments with moisture, modulus and heavy-atom salts. The data were interpreted using static and dynamic quenching models, heavy-atom theory, and a theory related to the modulus of paper. With cyclodextrin-salt matrices, it was shown that 10% {alpha}-cyclodextrin/NaCl was very effective for obtaining strong room-temperature fluorescence and moderate room-temperature phosphorescence from adsorbed stereoisomeric tetrols. Extensive photophysical information was obtained for the four tetrols on 10% {alpha}-cyclodextrin/NaCl. The photophysical information acquired was used to develop a method for characterizing two of the tetrols. Work with model compounds adsorbed on deuterated sodium acetate showed that C-H vibrations in the undeuterated sodium acetate were not responsible for the deactivation of the excited triplet state in the model phosphors investigated. A considerable amount of solution luminescence and solid-matrix luminescence data were compared. The most important finding was that in several cases the room-temperature solid-matrix luminescence quantum yields were greater than the solution low-temperature quantum yield values.
Reduced M(atrix) theory models: ground state solutions
López, J L
2015-01-01
We propose a method to find exact ground state solutions to reduced models of the SU($N$) invariant matrix model arising from the quantization of the 11-dimensional supermembrane action in the light-cone gauge. We illustrate the method by applying it to lower dimensional toy models and for the SU(2) group. This approach could, in principle, be used to find ground state solutions to the complete 9-dimensional model and for any SU($N$) group. The Hamiltonian, the supercharges and the constraints related to the SU($2$) symmetry are built from operators that generate a multicomponent spinorial wave function. The procedure is based on representing the fermionic degrees of freedom by means of Dirac-like gamma matrices, as was already done in the first proposal of supersymmetric (SUSY) quantum cosmology. We exhibit a relation between these finite $N$ matrix theory ground state solutions and SUSY quantum cosmology wave functions giving a possible physical significance of the theory even for finite $N$.
Analytical Solution for Isentropic Flows in Solids
Heuzé, Olivier
2009-12-01
In the XIXth century, Riemann gave the equations system and the exact solution for the isentropic flows in the case of the ideal gas. But to our knowledge, nothing has been done to apply it to condensed media. Many materials of practical interest, for instance metals, obey to the linear law D = c+s u, where D is the shock velocity, u the particle velocity, and c and s properties of the material. We notice that s is strongly linked to the fundamental derivative. This means that the assumption of constant fundamental derivative is useful in this case, as it was with the isentropic gamma in the Riemann solution. Then we can apply the exact Riemann solution for these materials. Although the use of the hypergeometric function is complicated in this case, we obtain a very good approximation with the development in power series.
Organic solid solution composed of two structurally similar porphyrins for organic solar cells.
Zhen, Yonggang; Tanaka, Hideyuki; Harano, Koji; Okada, Satoshi; Matsuo, Yutaka; Nakamura, Eiichi
2015-02-18
A solid solution of a 75:25 mixture of tetrabenzoporphyrin (BP) and dichloroacenaphtho[q]tribenzo[b,g,l]porphyrin (CABP) forms when they are generated in a matrix of (dimethyl(o-anisyl)silylmethyl)(dimethylphenylsilylmethyl)[60]fullerene. This solid solution provides structural and optoelectronic properties entirely different from those of either pristine compounds or a mixture at other blending ratios. The use of this BP:CABP solid solution for organic solar cell (OSC) devices resulted in a power conversion efficiency (PCE) value higher by 16 and 300% than the PCE values obtained for the devices using the single donor BP and CABP, respectively, in a planar heterojunction architecture. This increase originates largely from the increase in short circuit current density, and hence by enhanced charge carrier separation at the donor/acceptor interface, which was probably caused by suitable energy level for the solid solution state, where electronic coupling between the two porphyrins occurred. The results suggest that physical and chemical modulation in solid solution is beneficial as an operationally simple method to enhance OSC performance.
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 solution • Solid 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.
Solid Tumors: Facts, Challenges and Solutions
Gavhane Y. N.
2011-01-01
Full Text Available In 2005, 7.6 million people died of cancer out of 58 million deaths worldwide. Based on projections, cancer deaths will continue to rise with an estimated 9 million people dying from cancer in 2015, and 11.4 million dying in 2030. The increasing trend of cancer incidence has forced the humanity to work more on the cancer prevention and treatments. It is important for the public health professionals to understand the dynamics and kinetics of tumor incidence for future strategies. Over here we have reviewed solid tumor modeling, their detail classification, treatment strategies available along with their merits and demerits. To overcome these limitations, design focus for future studies is suggested.
Alloy softening in binary iron solid solutions
Stephens, J. R.; Witzke, W. R.
1976-01-01
An investigation was conducted to determine softening and hardening behavior in 19 binary iron-alloy systems. Microhardness tests were conducted at four temperatures in the range 77 to 411 K. Alloy softening was exhibited by 17 of the 19 alloy systems. Alloy softening observed in 15 of the alloy systems was attributed to an intrinsic mechanism, believed to be lowering of the Peierls (lattice friction) stress. Softening and hardening rates could be correlated with the atomic radius ratio of solute to iron. Softening observed in two other systems was attributed to an extrinsic mechanism, believed to be associated with scavenging of interstitial impurities.
Efficient and Color-Tunable Oxyfluoride Solid Solution Phosphors for Solid-State White Lighting
Im, Won Bin; George, Nathan; Kurzman, Joshua; Brinkley, Stuart; Mikhailovsky, Alexander; Hu, Jerry; Chmelka, Bradley F.; DenBaars, Steven P.; Seshadri, Ram (UCSB)
2012-09-06
A solid solution strategy helps increase the efficiency of Ce{sup 3+} oxyfluoride phosphors for solid-state white lighting. The use of a phosphor-capping architecture provides additional light extraction. The accompanying image displays electroluminescence spectra from a 434-nm InGaN LED phosphor that has been capped with the oxyfluoride phosphor.
On matrix diffusion: formulations, solution methods and qualitative effects
Carrera, Jesús; Sánchez-Vila, Xavier; Benet, Inmaculada; Medina, Agustín; Galarza, Germán; Guimerà, Jordi
Matrix diffusion has become widely recognized as an important transport mechanism. Unfortunately, accounting for matrix diffusion complicates solute-transport simulations. This problem has led to simplified formulations, partly motivated by the solution method. As a result, some confusion has been generated about how to properly pose the problem. One of the objectives of this work is to find some unity among existing formulations and solution methods. In doing so, some asymptotic properties of matrix diffusion are derived. Specifically, early-time behavior (short tests) depends only on φm2RmDm / Lm2, whereas late-time behavior (long tracer tests) depends only on φmRm, and not on matrix diffusion coefficient or block size and shape. The latter is always true for mean arrival time. These properties help in: (a) analyzing the qualitative behavior of matrix diffusion; (b) explaining one paradox of solute transport through fractured rocks (the apparent dependence of porosity on travel time); (c) discriminating between matrix diffusion and other problems (such as kinetic sorption or heterogeneity); and (d) describing identifiability problems and ways to overcome them. RésuméLa diffusion matricielle est un phénomène reconnu maintenant comme un mécanisme de transport important. Malheureusement, la prise en compte de la diffusion matricielle complique la simulation du transport de soluté. Ce problème a conduit à des formulations simplifiées, en partie à cause de la méthode de résolution. Il s'en est suivi une certaine confusion sur la façon de poser correctement le problème. L'un des objectifs de ce travail est de trouver une certaine unité parmi les formulations et les méthodes de résolution. C'est ainsi que certaines propriétés asymptotiques de la diffusion matricielle ont été dérivées. En particulier, le comportement à l'origine (expériences de traçage courtes) dépend uniquement du terme φm2RmDm / Lm2, alors que le comportement à long terme
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.
Forces between hydrophobic solids in concentrated aqueous salt solution.
Mastropietro, Dean J; Ducker, William A
2012-03-09
Much research has focused on the discovery and description of long-ranged forces between hydrophobic solids immersed in water. Here we show that the force between high contact-angle solids in concentrated salt solution (1 M KCl) agrees very well with van der Waals forces calculated from Lifshitz theory for separations greater than 5 nm. The hydrophobic solids are octadecyltrichlorosilane-coated glass, with an advancing contact angle of 108°. Thus, in 1 M salt solution, it is unnecessary to invoke the presence of a hydrophobic force at separations greater than 5 nm. Through measurement in salt solution, we avoid the necessity of accounting for large electrostatic forces that frequently occur in pure water and may obscure resolution of other forces.
Solid-solution thermodynamics in Al-Li alloys
Alekseev, A. A.; Lukina, E. A.
2016-05-01
The relative equilibrium concentrations of lithium atoms distributed over different electron-structural states has been estimated. The possibility of the existence of various nonequilibrium electron-structural states of Li atoms in the solid solution in Al has been substantiated thermodynamically. Upon the decomposition of the supersaturated solid solution, the supersaturation on three electron-structural states of Li atoms that arises upon the quenching of the alloy can lead to the formation of lithium-containing phases in which the lithium atoms enter in one electron-structural state.
Synthesis and characterization of mesostructured ceria-zirconia solid solution
LI Changlin; GU Xin; WANG Yanqin; WANG Yaojun; WANG Yangang; LIU Xiaohui; LU Guanzhong
2009-01-01
Mesostructured Ce0.6Zr0.4O2 solid solutions were synthesized by coprecipitation combined with evaporation-induced self-assembly process. The obtained materials were characterized by X-ray diffractometer (XRD), Raman, transmission electron microscopy (TEM), N2 sorption, and hydrogen temperature programmed reduction (H2-TPR). The results showed that the solid solutions consisted of uniform nanocrystals, which piled homogeneous mesopores of about 4 nm. Furthermore, different surfactants had little influence on the mesoporous structures. All these samples exhibited high thermal stability.
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.
Solid waste bin level detection using gray level co-occurrence matrix feature extraction approach.
Arebey, Maher; Hannan, M A; Begum, R A; Basri, Hassan
2012-08-15
This paper presents solid waste bin level detection and classification using gray level co-occurrence matrix (GLCM) feature extraction methods. GLCM parameters, such as displacement, d, quantization, G, and the number of textural features, are investigated to determine the best parameter values of the bin images. The parameter values and number of texture features are used to form the GLCM database. The most appropriate features collected from the GLCM are then used as inputs to the multi-layer perceptron (MLP) and the K-nearest neighbor (KNN) classifiers for bin image classification and grading. The classification and grading performance for DB1, DB2 and DB3 features were selected with both MLP and KNN classifiers. The results demonstrated that the KNN classifier, at KNN = 3, d = 1 and maximum G values, performs better than using the MLP classifier with the same database. Based on the results, this method has the potential to be used in solid waste bin level classification and grading to provide a robust solution for solid waste bin level detection, monitoring and management.
On a Solution of the Quaternion Matrix Equation X - A (X～) B = C and Its Application
Tong Song JIANG; Mu Sheng WEI
2005-01-01
This paper first studies the solution of a complex matrix equation X - AXB = C,obtains an explicit solution of the equation by means of characteristic polynomial, and then studies the quaternion matrix equation X - A (X～) B = C, characterizes the existence of a solution to the matrix equation, and derives closed-form solutions of the matrix equation in explicit forms by means of real representations of quaternion matrices. This paper also gives an application to the complex matrix equation X - AX-B = C.
Continuum modeling of a porous solid with pressure-sensitive dilatant matrix
Guo, T. F.; Faleskog, J.; Shih, C. F.
The pressure-sensitive plastic response of a material has been studied in terms of the intrinsic sensitivity of its yield stress to pressure and the presence and growth of cavities. This work focuses on the interplay between these two distinctly different mechanisms and the attendant material behavior. To this end, a constitutive model is proposed taking both mechanisms into account. Using Gurson's homogenization, an upper bound model is developed for a voided solid with a plastically dilatant matrix material. This model is built around a three-parameter axisymmetric velocity field for a unit sphere containing a spherical void. The void is also subjected to internal pressure; this can be relevant for polymeric adhesives permeated by moisture that vaporizes at elevated temperatures. The plastic response of the matrix material is described by Drucker-Prager's yield criterion and an associated flow rule. The resulting yield surface and porosity evolution law of the homogenized constitutive model are presented in parametric form. Using the solutions to special cases as building blocks, approximate models with explicit forms are proposed. The parametric form and an approximate explicit form are compared against full-field solutions obtained from finite element analysis. They are also studied for loading under generalized tension conditions. These computational simulations shed light on the interplay between the two mechanisms and its enhanced effect on yield strength and plastic flow. Among other things, the tensile yield strength of the porous solid is greatly reduced by the internal void pressure, particularly when a liquid/vapor phase is the source of the internal pressure.
Improved parallel solution techniques for the integral transport matrix method
Zerr, R. Joseph, E-mail: rjz116@psu.edu [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, PA (United States); Azmy, Yousry Y., E-mail: yyazmy@ncsu.edu [Department of Nuclear Engineering, North Carolina State University, Burlington Engineering Laboratories, Raleigh, NC (United States)
2011-07-01
Alternative solution strategies to the parallel block Jacobi (PBJ) method for the solution of the global problem with the integral transport matrix method operators have been designed and tested. The most straightforward improvement to the Jacobi iterative method is the Gauss-Seidel alternative. The parallel red-black Gauss-Seidel (PGS) algorithm can improve on the number of iterations and reduce work per iteration by applying an alternating red-black color-set to the subdomains and assigning multiple sub-domains per processor. A parallel GMRES(m) method was implemented as an alternative to stationary iterations. Computational results show that the PGS method can improve on the PBJ method execution time by up to 10´ when eight sub-domains per processor are used. However, compared to traditional source iterations with diffusion synthetic acceleration, it is still approximately an order of magnitude slower. The best-performing cases are optically thick because sub-domains decouple, yielding faster convergence. Further tests revealed that 64 sub-domains per processor was the best performing level of sub-domain division. An acceleration technique that improves the convergence rate would greatly improve the ITMM. The GMRES(m) method with a diagonal block pre conditioner consumes approximately the same time as the PBJ solver but could be improved by an as yet undeveloped, more efficient pre conditioner. (author)
Improved parallel solution techniques for the integral transport matrix method
Zerr, Robert J [Los Alamos National Laboratory; Azmy, Yousry Y [NORTH CAROLINA STATE UNIV.
2010-11-23
Alternative solution strategies to the parallel block Jacobi (PBJ) method for the solution of the global problem with the integral transport matrix method operators have been designed and tested. The most straightforward improvement to the Jacobi iterative method is the Gauss-Seidel alternative. The parallel red-black Gauss-Seidel (PGS) algorithm can improve on the number of iterations and reduce work per iteration by applying an alternating red-black color-set to the subdomains and assigning multiple sub-domains per processor. A parallel GMRES(m) method was implemented as an alternative to stationary iterations. Computational results show that the PGS method can improve on the PBJ method execution by up to {approx}50% when eight sub-domains per processor are used. However, compared to traditional source iterations with diffusion synthetic acceleration, it is still approximately an order of magnitude slower. The best-performing case are opticaUy thick because sub-domains decouple, yielding faster convergence. Further tests revealed that 64 sub-domains per processor was the best performing level of sub-domain division. An acceleration technique that improves the convergence rate would greatly improve the ITMM. The GMRES(m) method with a diagonal block preconditioner consumes approximately the same time as the PBJ solver but could be improved by an as yet undeveloped, more efficient preconditioner.
Solid and solution phase combinatorial synthesis of ureas
Nieuwenhuijzen, JW; Conti, PGM; Ottenheijm, HCJ; Linders, JTM
1998-01-01
An efficient parallel synthesis of ureas based on amino acids is described, both in solution and on solid phase. 1,1'-Carbonylbisbenzotriazole 2 is used as the coupling reagent. The ureas 5 and 10 were obtained in high yield (80-100%) and purity (71-97%). (C) 1998 Elsevier Science Ltd. All rights re
KNH2-KH: a metal amide-hydride solid solution.
Santoru, Antonio; Pistidda, Claudio; Sørby, Magnus H; Chierotti, Michele R; Garroni, Sebastiano; Pinatel, Eugenio; Karimi, Fahim; Cao, Hujun; Bergemann, Nils; Le, Thi T; Puszkiel, Julián; Gobetto, Roberto; Baricco, Marcello; Hauback, Bjørn C; Klassen, Thomas; Dornheim, Martin
2016-09-27
We report for the first time the formation of a metal amide-hydride solid solution. The dissolution of KH into KNH2 leads to an anionic substitution, which decreases the interaction among NH2(-) ions. The rotational properties of the high temperature polymorphs of KNH2 are thereby retained down to room temperature.
THE GENERALIZED REFLEXIVE SOLUTION FOR A CLASS OF MATRIX EQUATIONS(AX=B,XC=D)
无
2008-01-01
In this article, the generalized reflexive solution of matrix equations (AX =B, XC = D) is considered. With special properties of generalized reflexive matrices, the necessary and sufficient conditions for the solvability and the general expression of the solution are obtained. Moreover, the related optimal approximation problem to a given matrix over the solution set is solved.
Solid-like mechanical behaviors of ovalbumin aqueous solutions.
Ikeda, S; Nishinari, K
2001-04-12
Flow and dynamic mechanical properties of ovalbumin (OVA) aqueous solutions were investigated. OVA solutions exhibited relatively large zero-shear viscosity values under steady shear flow and solid-like mechanical responses against oscillating small shear strains, that is, the storage modulus was always larger than the loss modulus in the examined frequency range (0.1--100 rad s(-1)). These results suggest that dispersed OVA molecules arranged into a colloidal crystal like array stabilized by large interparticle repulsive forces. However, marked solid-like mechanical behaviors were detected even when electrostatic repulsive forces among protein molecules were virtually absent, which could not be explained solely on the basis of conventional Derjaguin--Landau--Verwey--Overbeek (DLVO) theory. Large non-DLVO repulsive forces seem to stabilize native OVA aqueous solutions.
A single sorbent for tetracycline enrichment and subsequent solid-matrix time-resolved luminescence
Liu Linshu [Eastern Regional Research Center, Agriculture Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038 (United States)]. E-mail: lsliu@errc.ars.usda.gov; Chen Guoying [Eastern Regional Research Center, Agriculture Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038 (United States); Fishman, Marshall L. [Eastern Regional Research Center, Agriculture Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038 (United States)
2005-01-10
The aim of this study was to search for a sorbent that could act as an extraction phase and as a support for solid-matrix time-resolved luminescence (SMTRL). Four potential sorbents were investigated for this purpose using tetracycline (TC) as a model analyte. Sorbents prepared from C18 silica gel or calcium cross-linked pectin gel were able to extract TC from dilute solutions. Europium(III)-TC complex adsorbed on the surface of C18 generated the most intense TRL signal when measured at {lambda}{sub ex} = 388 nm and {lambda}{sub em} = 615 nm. This method achieved a 1 ng/ml limit of detection (LOD) with a 100 {mu}l sample solution in a repeated spotting mode. Hyphenation of sorbent extraction and SMTRL was demonstrated using C18. This method is suitable for screening of TC in foods or aqueous solutions and can be extended to other luminescent lanthanide-chelating analytes in physiological or environmental samples.
Quan, Guilan; Wu, Qiaoli; Zhang, Xiaoxu; Zhan, Zhengwen; Zhou, Chan; Chen, Bao; Zhang, Zhengzan; Li, Ge; Pan, Xin; Wu, Chuanbin
2016-05-01
Mesoporous silica Santa Barbara amorphous-15 (SBA-15), derived from supermolecular assemblies of surfactant Pluronic(®) P123 with well-ordered 2-D hexagonal pores, was investigated as a reservoir to construct a novel solid self-emulsifying matrix for enhancing the oral bioavailability of fenofibrate (FNB). The emulsification rate and droplet size of a liquid self-emulsifying delivery system (SEDDS) were analyzed for optimization. SBA-15 was then added to the ethanol solution containing liquid SEDDS, and the obtained suspension changed into solid SEDDS matrix via solvent evaporation. The characterizations by SEM and XRD revealed that the solid matrix consisted of particles with smooth surface and FNB was completely transformed into molecular or amorphous state in the formulation. When introduced to aqueous media under gentle agitation, the solid matrix exhibited excellent self-emulsification properties and formed a uniform microemulsion with mean diameter of 117.35 ± 2.33 nm. The solid SEDDS matrix showed faster in vitro release rate than the raw powder and commercial capsule. The absorption of FNB delivered by solid SEDDS matrix was significantly improved in beagle dogs, and its Cmax and AUC values were about 8- and 4-fold greater than those of commercial products, respectively. In conclusion, SBA-15 emerged as a promising reservoir for SEDDS to enhance the bioavailability of poorly water-soluble drugs, which may provide a new strategy for advanced therapies. Copyright © 2016 Elsevier B.V. All rights reserved.
Luminescence spectra and kinetics of disordered solid solutions
Klochikhin, A.; Reznitsky, A.; Permogorov, S.;
1999-01-01
We have studied both theoretically and experimentally the luminescence spectra and kinetics of crystalline, disordered solid solutions after pulsed excitation. First, we present the model calculations of the steady-state luminescence band shape caused by recombination of excitons localized in the......-time limit at excitation below the exciton mobility edge. At excitation by photons with higher energies the diffusion of electrons can account for the observed behavior of the luminescence. [S0163-1829(99)11419-X]....
Development and characterization of solid solution tri-carbides
Knight, Travis; Anghaie, Samim
2001-02-01
Solid-solution, binary uranium/refractory metal carbide fuels have been shown to be capable of performing at high temperatures for nuclear thermal propulsion applications. More recently, tri-carbide fuels such as (U, Zr, Nb)C1+x with less than 10% metal mole fraction uranium have been studied for their application in ultra-high temperature, high performance space nuclear power systems. These tri-carbide fuels require high processing temperatures greater than 2600 K owing to their high melting points in excess of 3600 K. This paper presents the results of recent studies involving hypostoichiometric, single-phase tri-carbide fuels. Processing techniques of cold uniaxial pressing and sintering were investigated to optimize the processing parameters necessary to produce high density (low porosity), single phase, solid solution mixed carbide nuclear fuels for testing. Scanning electron microscopy and xray diffraction were used to analyze samples. Liquid phase sintering with UC1+x at temperatures near 2700 K was shown to be instrumental in achieving good densification in hyper- and near-stoichiometric mixed carbides. Hypostoichiometric carbides require even higher processing temperatures greater than 2800 K in order to achieve liquid phase sintering with a UC liquid phase and good densification of the final solid solution, tri-carbide fuel. .
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.
Extended Hansen approach: calculating partial solubility parameters of solid solutes.
Wu, P L; Beerbower, A; Martin, A
1982-11-01
A multiple linear regression method, known as the extended Hansen solubility approach, was used to estimate the partial solubility parameters, delta d, delta p, and delta h for crystalline solutes. The method is useful, since organic compounds may decompose near their melting points, and it is not possible, to determine solubility parameters for these solid compounds by the methods used for liquid solvents. The method gives good partial and total solubility parameters for naphthalene; with related compounds, less satisfactory results were obtained. At least three conditions, pertaining to the regression equation and the solvent systems, must be met in order to obtain reasonable solute solubility parameters. In addition to providing partial solubility parameters, the regression equations afford a calculation of solute solubility in both polar and nonpolar solvents.
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/sup 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/sub 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.
Thixoforming of SiC ceramic matrix composites in pseudo-semi-solid state
CHENG Yuan-sheng; LUO Shou-jing; DU Zhi-ming
2005-01-01
A new forming process, ceramic matrix composites thixoforming in pseudo-semi-solid state, was proposed based on powder metallurgy technology combined with the semi-solid metal forming process. The satellite angle-frames were prepared by this technology with Alp and SiCp materials mixed with different volume fractions. It is proved that it is feasible for the forming of the ceramic matrix composites by this technology through metallographic analyses and tensile tests. The results also show that the microstructures of samples are homogeneous and they have high hardness and certain plasticity.
BN-coated Ca(1-x)Sr(x)S:Eu solid-solution nanowires with tunable red light emission.
Lin, Jing; Huang, Yang; Mi, Jiao; Zhang, Xinghua; Lu, Zunming; Xu, Xuewen; Fan, Ying; Zou, Jin; Tang, Chengchun
2013-10-11
We report on the controlled growth of novel BN-coated Ca(1-x)Sr(x)S:Eu nanowires via a solid-liquid-solid process. The Ca(1-x)Sr(x)S solid solution forms as one-dimensional nanowires and has been coated with homogeneous protective BN nanolayers. The structure and luminescence properties of this new nanocomposite have been systematically investigated. High-spatial-resolution cathodoluminescence investigations reveal that effective red color tuning has been achieved by tailoring the composition of the Ca(1-x)Sr(x)S nanowires. Moreover, codoping of Ce(3+) and Eu(2+) in the CaS nanowire can induce energy transfer in the matrix and make it possible to obtain enhanced orange color in the nanowires. The BN-coated Ca(1-x)Sr(x)S:Eu solid-solution nanowires are envisaged to be valuable red-emitting nanophosphors and useful in advanced nanodevices and white LEDs.
1966-01-01
SINGLE CRYSTALS WITH RHENIUM IN DILUTE SOLID SOLUTION Sby M. Garfinkle Lewis Research Center Cleveland, Ohio 20060516196 NATIONAL AERONAUTICS AND...WITH RHENIUM IN DILUTE SOLID SOLUTION By M. Garfinkle Lewis Research Center Cleveland, Ohio NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by...ORIENTED TUNGSTEN SINGLE CRYSTALS WITH RHENIUM IN DILUTE SOLID SOLUTION * by M. Garfinkle Lewis Research Center SUMMARY Tungsten single crystals
An explicit solution to the matrix equation AV+BW=EV J
Aiguo WU; Guangren DUAN; Bin ZHOU
2007-01-01
In this note,the matrix equation AV+BW=EV J is considered,where E,A and B are given matrices of appropriate dimensions,J is an arbitrarily given Jordan matrix,V and W are the matrices to be determined.Firstly,a right factorization of(sE-A)-1 B is given based on the Leverriver algorithm for descriptor systems.Then based on this factorization and a proposed parametric solution,an alternative parametric solution to this matrix equation is established in terms of the R-controllability matrix of(E,A,B),the generalized symmetric operator and the observability matrix associated with the Jordan matrix J and a free parameter matrix.The proposed results provide great convenience for many analysis and design problems.Moreover,some equivalent forms are proposed.A numerical example is employed to illustrate the effect of the proposed approach.
On the complete perturbative solution of one-matrix models
A. Mironov
2017-08-01
Full Text Available We summarize the recent results about complete solvability of Hermitian and rectangular complex matrix models. Partition functions have very simple character expansions with coefficients made from dimensions of representation of the linear group GL(N, and arbitrary correlators in the Gaussian phase are given by finite sums over Young diagrams of a given size, which involve also the well known characters of symmetric group. The previously known integrability and Virasoro constraints are simple corollaries, but no vice versa: complete solvability is a peculiar property of the matrix model (hypergeometric τ-functions, which is actually a combination of these two complementary requirements.
Solution of the Lyapunov matrix equation for a system with a time-dependent stiffness matrix
Pommer, Christian; Kliem, Wolfhard
2004-01-01
The stability of the linearized model of a rotor system with non-symmetric strain and axial loads is investigated. Since we are using a fixed reference system, the differential equations have the advantage to be free of Coriolis and centrifugal forces. A disadvantage is nevertheless the occurrenc...... of time-dependent periodic terms in the stiffness matrix. However, by solving the Lyapunov matrix equation we can formulate several stability conditions for the rotor system. Hereby the positive definiteness of a certain averaged stiffness matrix plays a crucial role....
Stabilization of pH in solid-matrix hydroponic systems
Frick, J.; Mitchell, C. A.
1993-01-01
2-[N-morpholino]ethanesulfonic acid (MES) buffer or Amberlite DP-1 (cation-exchange resin beads) were used to stabilize substrate pH of passive-wicking, solid-matrix hydroponic systems in which small canopies of Brassica napus L. (CrGC 5-2, genome : ACaacc) were grown to maturity. Two concentrations of MES (5 or 10 mM) were included in Hoagland 1 nutrient solution. Alternatively, resin beads were incorporated into the 2 vermiculite : 1 perlite (v/v) growth medium at 6% or 12% of total substrate volume. Both strategies stabilized pH without toxic side effects on plants. Average seed yield rates for all four pH stabilization treatments (13.3 to 16.9 g m-2 day-1) were about double that of the control (8.2 g m-2 day-1), for which there was no attempt to buffer substrate pH. Both the highest canopy seed yield rate (16.9 g m-2 day-1) and the highest shoot harvest index (19.5%) occurred with the 6% resin bead treatment, even though the 10 mM MES and 12% bead treatments maintained pH within the narrowest limits. The pH stabilization methods tested did not significantly affect seed oil and protein contents.
Application Of Density Matrix Methods To Quadrupolar Spins In Solid State Nmr And Nqr
Ageev, S Z
1997-01-01
Spin dynamics in solid state NMR and NQR are studied using spin density matrix theory. First, the response of spin 7/2 subject to the first order quadrupolar interaction, excited by one and two pulse sequences is examined. Specific pulse sequences with appropriate phase cycling designed for detection of MQ coherences developed during the first pulse are calculated analytically. The results are applied to the determination of quadrupolar parameters and true chemical shifts utilizing a 1D nutation experiment. Solomon echoes under soft pulse excitation are also considered for spin 7/2. Second, analytical solutions of off-resonance nutation line intensities for spin 3/2 are presented. The first order quadrupolar interaction is retained during the pulse. The third case puts forward a new theory of composite pulses in NQR. Shaped pulses are also considered. The calculation is valid for a non-zero asymmetry parameter and arbitrary orientation of the rf field. The results are generalized for half integer spins of mag...
Upper solution bounds of the continuous coupled algebraic Riccati matrix equation
Liu, Jianzhou; Zhang, Juan
2011-04-01
In this article, by using some matrix identities, we construct the equivalent form of the continuous coupled algebraic Riccati equation (CCARE). Further, with the aid of the eigenvalue inequalities of matrix's product, by solving the linear inequalities utilising the properties of M-matrix and its inverse matrix, new upper matrix bounds for the solutions of the CCARE are established, which improve and extend some of the recent results. Finally, a corresponding numerical example is proposed to illustrate the effectiveness of the derived results.
Yifan Tu; Jin Xu; Jianfu Zhang; Boping Zhang; Dongliang Zhao
2007-01-01
The influence of solid-solution temperature on the dissolution of carbide precipitates,the average grain size and the microhardness of the austenite matrix in an Fe-Ni based high strength low thermal expansion (HSLTE) alloy was investigated to obtain the proper temperature range of the solid-solution process.The XRD analysis,microstructure observations,and the theoretical calculations showed that the Mo-rich M2C-type precipitates in the Fe-Ni based HSLTE alloy dissolve completely at about 1100 ℃.The average grain size of the studied alloys increases from 14 to 46 μm in the temperature range of 1050 to 1200 ℃.The microhardness of the matrix decreases first for the sake of solid-solution treatment,but then increases later with increasing solution temperature because of the solution strengthening effect.
Bin ZHOU; Guangren DUAN
2006-01-01
In this paper, an explicit solution to polynomial matrix right coprime factorization of input-state transfer function is obtained in terms of the Krylov matrix and the Pseudo-controllability indices of the pair of coefficient matrices.The proposed approach only needs to solve a series of line ar equations. Applications of this solution to a type of generalized Sylvester matrix equations and the problem of parametric eigenstructure assignment by state feedback are investigated.These new solutions are simple, they possess better structural properties and are very convenient to use. An example shows the effect of the proposed results.
Rebelo, Q.H.F.; Cotta, E.A. [Departamento de Física, Universidade Federal do Amazonas, 69077-000 Manaus, Amazonas (Brazil); Souza, S.M. de, E-mail: s.michielon@gmail.com [Departamento de Física, Universidade Federal do Amazonas, 69077-000 Manaus, Amazonas (Brazil); Trichês, D.M. [Departamento de Física, Universidade Federal do Amazonas, 69077-000 Manaus, Amazonas (Brazil); Machado, K.D. [Departamento de Física, Centro Politécnico, Universidade Federal do Paraná, 81531-990 Curitiba, Paraná (Brazil); Lima, J.C. de; Grandi, T.A. [Departamento de Física, Centro de Ciências Exatas, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina (Brazil); Poffo, C.M. [Departamento de Eng. Mecânica, Centro de Ciências Tecnológicas, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina (Brazil); Manzato, L. [Instituto Federal de Educação, Ciência e Tecnologia do Amazonas, 69075-351 Manaus, Amazonas (Brazil)
2013-10-25
Highlights: •A Ge{sub 34}Sb{sub 66} solid solution was prepared by mechanical alloying. •X-ray diffraction results indicate complete dissolution of Ge on the Sb matrix. •Raman measurements indicate the presence of nanocrystalline Ge dispersed in the matrix. -- Abstract: A nanostructured solid solution Ge{sub 34}Sb{sub 66} was produced from Ge and Sb by mechanical alloying and its structural and vibrational properties were investigated by X-ray diffraction (XRD) and micro-Raman spectroscopy. The Rietveld refinement of the XRD measurements allowed the investigation of the evolution of the solid solution with the milling time. The Bragg peaks of the Sb solvent phase showed a strongly reflection-indices-dependent line broadening due to the spatial variation of the Sb/Ge ratio. The asymmetric broadening in the deformed peaks was analyzed considering the Stephens model. Volume fractions of crystalline and interfacial components of the milled powder were estimated from the XRD patterns. Although XRD measurements indicated the formation of a solid solution, Raman measurements revealed the presence of nanocrystalline Ge, and its crystallite size was estimated from the Raman analysis.
Least-Squares Mirrorsymmetric Solution for Matrix Equations (AX=B, XC=D)
Fanliang Li; Xiyan Hu; Lei Zhang
2006-01-01
In this paper, least-squares mirrorsymmetric solution for matrix equations (AX =B, XC=D) and its optimal approximation is considered. With special expression of mirrorsymmetric matrices, a general representation of solution for the least-squares problem is obtained. In addition, the optimal approximate solution and some algorithms to obtain the optimal approximation are provided.
ON SOLUTIONS OF QUATERNION MATRIX EQUATIONS XF-AX =BY AND XF-A(X) =BY
Song Caiqin; Chen Guoliang; Wang Xiaodong
2012-01-01
In this paper,the quaternion matrix equations XF-AX =BY and XF-A(X) =BY are investigated.For convenience,they were called generalized Sylvesterquaternion matrix equation and generalized Sylvester-j-conjugate quaternion matrix equation,which include the Sylvester matrix equation and Lyapunov matrix equation as special cases.By applying of Kronecker map and complex representation of a quaternion matrix,the sufficient conditions to compute the solution can be given and the expressions of the explicit solutions to the above two quaternion matrix equations XF-AX =BY and XF-A(X) =BY are also obtained.By the established expressions,it is easy to compute the solution of the quaternion matrix equation in the above two forms.In addition,two practical algorithms for these two quaternion matrix equations are give.One is complex representation matrix method and the other is a direct algorithm by the given expression.Furthermore,two illustrative examples are proposed to show the efficiency of the given method.
S Valizadeh
2015-08-01
Full Text Available Background and Objective: Significant increase in population and as a result, the production of excessive waste has recently made attention to municipal solid waste management a necessary issue. The objective of this study was to use matrix-based EIA process in order to determine best waste management option in Birjand City and to suggest appropriate solutions to managers and planners of this city. Materials and Methods: Assessing the environmental impacts of waste management options was done using Iranian Leopold Matrix. Through this method, the environmental impacts of waste management options were determined in the Birjand City. The options were Open dumping, Recycling, Composting, and Sanitary damping. Results: The results indicated that Open dumping with a final score of -3.06 had the highest environmental impact and was introduced as the fourth preference. In addition, composting with final score of -2.34 has the lowest environmental impact compared with other options. Conclusion: About 76.95% of the composition of municipal solid waste of Birjand City is household waste; therefore, putrescible organic materials are the predominant waste. Thus, according to the results of the Iranian Leopold matrix method, composting option was introduced as the first priority and the most logical option for waste management in the Birjand City.
Isomorphism and solid solutions among Ag- and Au-selenides
Palyanova, Galina A.; Seryotkin, Yurii V. [Sobolev Institute of Geology and Mineralogy, Novosibirsk (Russian Federation); Novosibirsk State University (Russian Federation); Kokh, Konstantin A., E-mail: k.a.kokh@gmail.com [Sobolev Institute of Geology and Mineralogy, Novosibirsk (Russian Federation); Novosibirsk State University (Russian Federation); Tomsk State University (Russian Federation); Bakakin, Vladimir V. [Nikolaev Institute of Inorganic Chemistry, Novosibirsk (Russian Federation)
2016-09-15
Au-Ag selenides were synthesized by heating stoichiometric mixtures of elementary substances of initial compositions Ag{sub 2−x}Au{sub x}Se with a step of x=0.25 (0≤x≤2) to 1050 °C and annealing at 500 °C. Scanning electron microscopy, optical microscopy, electron microprobe analysis and X-ray powder diffraction methods have been applied to study synthesized samples. Results of studies of synthesized products revealed the existence of three solid solutions with limited isomorphism Ag↔Au: naumannite Ag{sub 2}Se – Ag{sub 1.94}Au{sub 0.06}Se, fischesserite Ag{sub 3}AuSe{sub 2} - Ag{sub 3.2}Au{sub 0.8}Se{sub 2} and gold selenide AuSe - Au{sub 0.94}Ag{sub 0.06}Se. Solid solutions and AgAuSe phases were added to the phase diagram of Ag-Au-Se system. Crystal-chemical interpretation of Ag-Au isomorphism in selenides was made on the basis of structural features of fischesserite, naumannite, and AuSe. - Highlights: • Au-Ag selenides were synthesized. • Limited Ag-Au isomorphism in the selenides is affected by structural features. • Some new phases were introduced to the phase diagram Ag-Au-Se.
Atomistic interpretation of solid solution hardening from spectral analysis.
Plendl, J N
1971-05-01
From analysis of a series of vibrational spectra of ir energy absorption and laser Raman, an attempt is made to interpret solid solution hardening from an atomistic point of view for the system CaF(2)/SrF(2). It is shown to be caused by the combined action of three atomic characteristics, i.e., their changes as a function of composition. They are deformation of the atomic coordination polyhedrons, overlap of the outer electron shells of the atom pairs, and the ratio of the ionic to covalent share of binding. A striking nonlinear behavior of the three characteristics, as a function of composition, gives maximum atomic bond strength to the 55/45 position of the system CaF(2)/SrF(2), in agreement with the measured data of the solid solution hardening. The curve for atomic bond strength, derived from the three characteristics, is almost identical to the curve for measured microhardness data. This result suggests that the atomistic interpretation, put forward in this paper, is correct.
Zn₃P₂-Zn₃As₂ solid solution nanowires.
Im, Hyung Soon; Park, Kidong; Jang, Dong Myung; Jung, Chan Su; Park, Jeunghee; Yoo, Seung Jo; Kim, Jin-Gyu
2015-02-11
Semiconductor alloy nanowires (NWs) have recently attracted considerable attention for applications in optoelectronic nanodevices because of many notable properties, including band gap tunability. Zinc phosphide (Zn3P2) and zinc arsenide (Zn3As2) belong to a unique pseudocubic tetragonal system, but their solid solution has rarely been studied. Here In this study, we synthesized composition-tuned Zn3(P1-xAsx)2 NWs with different crystal structures by controlling the growth conditions during chemical vapor deposition. A first type of synthesized NWs were single-crystalline and grew uniformly along the [110] direction (in a cubic unit cell) over the entire compositional range (0 ≤ x ≤ 1) explored. The use of an indium source enabled the growth of a second type of NWs, with remarkable cubic-hexagonal polytypic twinned superlattice and bicrystalline structures. The growth direction of the Zn3P2 and Zn3As2 NWs was also switched to [111] and [112], respectively. These structural changes are attributable to the Zn-depleted indium catalytic nanoparticles which favor the growth of hexagonal phases. The formation of a solid solution at all compositions allowed the continuous tuning of the band gap (1.0-1.5 eV). Photocurrent measurements were performed on individual NWs by fabricating photodetector devices; the single-crystalline NWs with [110] growth direction exhibit a higher photoconversion efficiency compared to the twinned crystalline NWs with [111] or [112] growth direction.
Ly, Xuan Nam; Yang, S.; Qin, Y.
2017-03-01
The influence of solid-solution treatment on microstructure, mechanical property and corrosion behavior of Mg-Zn-Ca alloy was studied in the present investigation by SEM, tensile test, electrochemical and immersion test. The results show that the microstructure of Mg alloys after solid solution treatment significantly changed, a large number of the second phase (Ca2Mg6Zn3, Mg2Ca) dissolved into the α-Mg matrix reaching a supersaturated state, and the grains size was bigger than before solid solution treatment; the mechanical properties were obviously improved. In particular the tensile strength of 0.5wt.% Ca of Mg alloy reached 220MPa and the ductility reached 16.6%. Compared with the as-cast Mg alloys, the corrosion potential after solid-solution treatment slightly shifted negative, but the corrosion current density significantly decreased. After solid solution treatment, the surface corrosion was not serious and the result of weight gain was lower compared with those of the as-cast Mg alloys.
Houen, G.; Olsen, D.T.; Hansen, P.R.;
2003-01-01
A solid-phase conjugation method utilizing carrier protein bound to an ion exchange matrix was developed. Ovalbumin was adsorbed to an anion exchange matrix using a batch procedure, and the immobilized protein was then derivatized with iodoacetic acid N-hydroxysuccinimid ester. The activated......, and immunization experiments with the eluted conjugates showed that the more substituted conjugates gave rise to the highest titers of glutathione antibodies. Direct immunization with the conjugates adsorbed to the ion exchange matrix was possible and gave rise to high titers of glutathione antibodies. Conjugates...... of ovalbumin and various peptides were prepared in a similar manner and used for production of peptide antisera by direct immunization with the conjugates bound to the ion exchanger. Advantages of the method are its solid-phase nature, allowing fast and efficient reactions and intermediate washings...
Rai, R. N.; Kant, Shiva; Reddi, R. S. B.; Ganesamoorthy, S.; Gupta, P. K.
2016-01-01
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.
ON HERMITIAN POSITIVE DEFINITE SOLUTION OF NONLINEAR MATRIX EQUATION X + A*X-2A = Q
Xiao-xia Guo
2005-01-01
Based on the fixed-point theory, we study the existence and the uniqueness of the maximal Hermitian positive definite solution of the nonlinear matrix equation X + A* X-2A =Q, where Q is a square Hermitian positive definite matrix and A* is the conjugate transpose of the matrix A. We also demonstrate some essential properties and analyze the sensitivity of this solution. In addition, we derive computable error bounds about the approximations to the maximal Hermitian positive definite solution of the nonlinear matrix equation X + A*X-2A = Q. At last, we further generalize these results to the nonlinear matrix equation X + A*X-nA = Q, where n ≥ 2 is a given positive integer.
Creep Behavior of Solid Solution Strengthened Y3Al5O12
2007-11-02
DATES COVERED Final Technical Report 15 Feb 97 to 29 Aug 97 4. TITLE AND SUBTITLE Creep Behavior of Solid Solution Strengthened Y3A15012 6...Final Report Title: Creep Behavior of Solid Solution Strengthened Y3AI5012 Award Number: F49620-97-1-0097 For the period of: 2/14/97-8/31/97...been investigated at present in these oxides is through the formation of solid solution alloys. For the case of oxides two different possible solid
Purdy, B.B.
1992-01-01
The solid-matrix luminescence limits of detection, percent relative standard deviation, and linear concentration ranges were obtained for model compounds adsorbed on four different solid-matrices. Filter paper showed the best analytical merit. Several solid-matrix luminescence properties of phenylphenol isomers adsorbed on Whatman filter paper were investigated. In the presence of sodium halide salts, the luminescence intensity, lifetime, quantum yield and modulus data were obtained to study heavy-atom effects, quenching effects by salts and moisture, and photophysical processes and molecular interactions in the solid-matrix. For 4-phenylphenol, 3-phenylphenol, and 2-phenylphenol, heavy-atom effects were observed for the room-temperature luminescence intensities. The room-temperature phosphorescence was sensitive to the structural differences among the isomers. The quenching of room-temperature fluorescence by halides was best described by a modified Perrin quenching model which considered a quenching sphere volume and residual fluorescence. At room temperature, the phosphorescence intensities were quenched by moisture while the phosphorescence lifetimes and fluorescence intensities were slightly affected by moisture for 4-phenylphenol and 2-phenylphenol with sodium halides. It was concluded that the adsorption of moisture on the filter paper matrix decreased the matrix rigidity, and thus the phosphorescence intensities of adsorbed phosphors were diminished. The phosphors were well-protected in the matrix, and water molecules could not diffuse effectively to the phosphor molecules. The photophysical data showed how the absorbed energy was channeled into the various radiative and nonradiative processes. Modulus experiments showed there were no differences in the Young's modulus values of filter paper containing NaCl, NaBr, or NaI. A correlation was found between Young's modulus and phosphorescence intensity as a function of the water content adsorbed on
Reaction paths and equilibrium end-points in solid-solution aqueous-solution systems
Glynn, P.D.; Reardon, E.J.; Plummer, L.N.; 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.
Hierarchical matrix techniques for the solution of elliptic equations
Chávez, Gustavo
2014-05-04
Hierarchical matrix approximations are a promising tool for approximating low-rank matrices given the compactness of their representation and the economy of the operations between them. Integral and differential operators have been the major applications of this technology, but they can be applied into other areas where low-rank properties exist. Such is the case of the Block Cyclic Reduction algorithm, which is used as a direct solver for the constant-coefficient Poisson quation. We explore the variable-coefficient case, also using Block Cyclic reduction, with the addition of Hierarchical Matrices to represent matrix blocks, hence improving the otherwise O(N2) algorithm, into an efficient O(N) algorithm.
Spectroscopy of lithium atoms sublimated from isolation matrix of solid Ne
Sacramento, R. L.; Scudeller, L. A.; Lambo, R.; Crivelli, P.; Cesar, C. L.
2011-10-01
We have studied, via laser absorption spectroscopy, the velocity distribution of 7Li atoms released from a solid neon matrix at cryogenic temperatures. The Li atoms are implanted into the Ne matrix by laser ablation of a solid Li precursor. A heat pulse is then applied to the sapphire substrate sublimating the matrix together with the isolated atoms at around 12 K. We find interesting differences in the velocity distribution of the released Li atoms from the model developed for our previous experiment with Cr [R. Lambo, C. C. Rodegheri, D. M. Silveira, and C. L. Cesar, Phys. Rev. A 76, 061401-R (2007)], 10.1103/PhysRevA.76.061401. This may be due to the sublimation regime, which is at much lower flux for the Li experiment than for the Cr experiment, as well as to the different collisional cross sections between those species to the Ne gas. We find a drift velocity compatible with Li being thermally sublimated at 11-13 K, while the velocity dispersion around this drift velocity is low, around 5-7 K. With a slow sublimation of the matrix we can determine the penetration depth of the laser ablated Li atoms into the Ne matrix, an important information that is not usually available in most matrix isolation spectroscopy setups. The present results with Li, together with the previous results with Cr suggest this to be a general technique for obtaining cryogenic atoms, for spectroscopic studies, as well as for trap loading. The release of the isolated atoms is also a useful tool to study and confirm details of the matrix isolated atoms which are masked or poorly understood in the solid.
Spectroscopy of lithium atoms sublimated from isolation matrix of solid Ne.
Sacramento, R L; Scudeller, L A; Lambo, R; Crivelli, P; Cesar, C L
2011-10-07
We have studied, via laser absorption spectroscopy, the velocity distribution of (7)Li atoms released from a solid neon matrix at cryogenic temperatures. The Li atoms are implanted into the Ne matrix by laser ablation of a solid Li precursor. A heat pulse is then applied to the sapphire substrate sublimating the matrix together with the isolated atoms at around 12 K. We find interesting differences in the velocity distribution of the released Li atoms from the model developed for our previous experiment with Cr [R. Lambo, C. C. Rodegheri, D. M. Silveira, and C. L. Cesar, Phys. Rev. A 76, 061401(R) (2007)]. This may be due to the sublimation regime, which is at much lower flux for the Li experiment than for the Cr experiment, as well as to the different collisional cross sections between those species to the Ne gas. We find a drift velocity compatible with Li being thermally sublimated at 11-13 K, while the velocity dispersion around this drift velocity is low, around 5-7 K. With a slow sublimation of the matrix we can determine the penetration depth of the laser ablated Li atoms into the Ne matrix, an important information that is not usually available in most matrix isolation spectroscopy setups. The present results with Li, together with the previous results with Cr suggest this to be a general technique for obtaining cryogenic atoms, for spectroscopic studies, as well as for trap loading. The release of the isolated atoms is also a useful tool to study and confirm details of the matrix isolated atoms which are masked or poorly understood in the solid. © 2011 American Institute of Physics
On the eigenvalue-eigenvector method for solution of the stationary discrete matrix Riccati equation
Michelsen, Michael Locht
1979-01-01
The purpose of this correspondence is to point out that certain numerical problems encountered in the solution of the stationary discrete matrix Riccati equation by the eigenvalue-eigenvector method of Vanghan [1] can be avoided by a simple reformulation....
Mixed matrix membranes for efficient adsorption of copper ions from aqueous solutions
Tetala, K.K.R.; Stamatialis, Dimitrios
2013-01-01
This work presents adsorption of copper (Cu2+) ions from aqueous solutions using mixed matrix membrane (MMM) and its elution afterwards. The developed flat sheet MMM, comprises of chitosan beads incorporated in Ethylene vinyl alcohol (EVAL) polymer porous matrix and exhibits static Cu2+ ion
Solutions of random-phase approximation equation for positive-semidefinite stability matrix
Nakada, H
2016-01-01
It is mathematically proven that, if the stability matrix $\\mathsf{S}$ is positive-semidefinite, solutions of the random-phase approximation (RPA) equation are all physical or belong to Nambu-Goldstone (NG) modes, and the NG-mode solutions may form Jordan blocks of $\\mathsf{N\\,S}$ ($\\mathsf{N}$ is the norm matrix) but their dimension is not more than two. This guarantees that the NG modes in the RPA can be separated out via canonically conjugate variables.
OPTIMAL APPROXIMATE SOLUTION OF THE MATRIX EQUATION AXB=C OVER SYMMETRIC MATRICES
Anping Liao; Yuan Lei
2007-01-01
Let SE denote the least-squares symmetric solution set of the matrix equation AXB=C,where A,B and C are given matrices of suitable size.To find the optimal approximate solution in the set SE to a given matrix,we give a new feasible method based on the projection theorem,the generalized SVD and the canonical correction decomposition.
Solid state and solution nitrate photochemistry: photochemical evolution of the solid state lattice.
Asher, Sanford A; Tuschel, David D; Vargson, Todd A; Wang, Luling; Geib, Steven J
2011-05-01
We examined the deep UV 229 nm photochemistry of NaNO(3) in solution and in the solid state. In aqueous solution excitation within the deep UV NO(3)¯ strong π → π* transition causes the photochemical reaction NO(3)¯ → NO(2)¯ + O·. We used UV resonance Raman spectroscopy to examine the photon dose dependence of the NO(2)¯ band intensities and measure a photochemical quantum yield of 0.04 at pH 6.5. We also examined the response of solid NaNO(3) samples to 229 nm excitation and also observe formation of NO(2)¯. The quantum yield is much smaller at ∼10(-8). The solid state NaNO(3) photochemistry phenomena appear complex by showing a significant dependence on the UV excitation flux and dose. At low flux/dose conditions NO(2)¯ resonance Raman bands appear, accompanied by perturbed NO(3)¯ bands, indicating stress in the NaNO(3) lattice. Higher flux/dose conditions show less lattice perturbation but SEM shows surface eruptions that alleviate the stress induced by the photochemistry. Higher flux/dose measurements cause cratering and destruction of the NaNO(3) surface as the surface layers are converted to NO(2)¯. Modest laser excitation UV beams excavate surface layers in the solid NaNO(3) samples. At the lowest incident fluxes a pressure buildup competes with effusion to reach a steady state giving rise to perturbed NO(3)¯ bands. Increased fluxes result in pressures that cause the sample to erupt, relieving the pressure.
Recent advances in lipid nanoparticle formulations with solid matrix for oral drug delivery.
Das, Surajit; Chaudhury, Anumita
2011-03-01
Lipid nanoparticles based on solid matrix have emerged as potential drug carriers to improve gastrointestinal (GI) absorption and oral bioavailability of several drugs, especially lipophilic compounds. These formulations may also be used for sustained drug release. Solid lipid nanoparticle (SLN) and the newer generation lipid nanoparticle, nanostructured lipid carrier (NLC), have been studied for their capability as oral drug carriers. Biodegradable, biocompatible, and physiological lipids are generally used to prepare these nanoparticles. Hence, toxicity problems related with the polymeric nanoparticles can be minimized. Furthermore, stability of the formulations might increase than other liquid nano-carriers due to the solid matrix of these lipid nanoparticles. These nanoparticles can be produced by different formulation techniques. Scaling up of the production process from lab scale to industrial scale can be easily achieved. Reasonably high drug encapsulation efficiency of the nanoparticles was documented. Oral absorption and bioavailability of several drugs were improved after oral administration of the drug-loaded SLNs or NLCs. In this review, pros and cons, different formulation and characterization techniques, drug incorporation models, GI absorption and oral bioavailability enhancement mechanisms, stability and storage condition of the formulations, and recent advances in oral delivery of the lipid nanoparticles based on solid matrix will be discussed. © 2010 American Association of Pharmaceutical Scientists
Numerical solution of Sylvester matrix equations: Application to dynamical systems
Shukooh Sadat Asari
2016-01-01
Full Text Available Many problems of control theory specially dynamical system lead to Sylvester equations. In this paper, we employ an iterative method of optimization based on partial swarm theory to solve the Sylvester system. To this purpose we consider dynamical system with different construction of state observer which lead to Sylvester observer equation. Using Pso to optimize the solution, obtain the solution with high accuracy comparison with other numerical methods, since the stability analysis of particle dynamics of PSO associated with the best particle is based on nonlinear feedback systems. Finally, some examples demonstrate the efficiency of the proposed method.
Ma, Shuangqin; Tu, Xijuan; Dong, Jiangtao; Long, Peng; Yang, Wenchao; Miao, Xiaoqing; Chen, Wenbin; Wu, Zhenhong
2015-11-15
Soxhlet-assisted matrix solid phase dispersion (SA-MSPD) method was developed to extract flavonoids from rape (Brassica campestris) bee pollen. Extraction parameters including the extraction solvent, the extraction time, and the solid support conditions were investigated and optimized. The best extraction yields were obtained using ethanol as the extraction solvent, silica gel as the solid support with 1:2 samples to solid support ratio, and the extraction time of one hour. Comparing with the conventional solvent extraction and Soxhlet method, our results show that SA-MSPD method is a more effective technique with clean-up ability. In the test of six different samples of rape bee pollen, the extracted content of flavonoids was close to 10mg/g. The present work provided a simple and effective method for extracting flavonoids from rape bee pollen, and it could be applied in the studies of other kinds of bee pollen.
Decay of oxygen solid solution in plastically deformed silicon
Yarykin, N. [Institute of Microelectronics Technology RAS, Chernogolovka (Russian Federation); Vdovin, V.I. [Institute for Chemical Problems of Microelectronics, Moscow (Russian Federation)
2005-04-01
Decay of the oxygen solid solution in silicon during annealing at 550-700 C is studied by the IR absorption technique in the single crystalline samples subjected to the plastic deformation to a high dislocation density at 680 C. The deformation is shown to significantly enhance the rate of the decay in the whole temperature range studied. Based on the simple model, which assumes the heterogeneous oxygen aggregation at dislocations, the effective oxygen diffusivity is calculated from the experimental data. The activation energy of oxygen diffusion in this temperature range is found to be about 1.6 eV, which is essentially lower than that for the isolated interstitial oxygen atom. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
Nucleation of the diamond phase in aluminium-solid solutions
Hornbogen, E.; Mukhopadhyay, A. K.; Starke, E. A., Jr.
1993-01-01
Precipitation was studied from fcc solid solutions with silicon, germanium, copper and magnesium. Of all these elements only silicon and germanium form diamond cubic (DC) precipitates in fcc Al. Nucleation of the DC structure is enhanced if both types of atom are dissolved in the fcc lattice. This is interpreted as due to atomic size effects in the prenucleation stage. There are two modes of interference of fourth elements with nucleation of the DC phase in Al + Si, Ge. The formation of the DC phase is hardly affected if the atoms (for example, copper) are rejected from the (Si, Ge)-rich clusters. If additional types of atom are attracted by silicon and/or germanium, DC nuclei are replaced by intermetallic compounds (for example Mg2Si).
Magneto-volume effects in Fe-Cu solid solutions
Gorria, P. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain)]. E-mail: pgorria@uniovi.es; Martinez-Blanco, D. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Iglesias, R. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Palacios, S.L. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Perez, M.J. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Blanco, J.A. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Fernandez Barquin, L. [Departamento CITIMAC, F. Ciencias, Universidad de Cantabria, 39005 Santander (Spain); Hernando, A. [Instituto de Magnetismo Aplicado, UCM-RENFE, 28230 Las Rozas, Madrid (Spain); Gonzalez, M.A. [Instituto de Ciencia de Materiales de Aragon, CSIC, 50009 Zaragoza (Spain); Institut Laue-Langevin, BP 156, F-38042 Grenoble Cedex 9 (France)
2006-05-15
The magnetic properties of Fe-Cu metastable solid solutions have been investigated by means of neutron diffraction and magnetisation measurements. These compounds exhibit ferromagnetic order with Curie temperatures above room temperature for concentrations beyond 40 at% in Fe. The magnetic moment at 5 K can reach values over 2 {mu} {sub B}, while the high field susceptibility is similar to that found in FCC-FeNi Invar alloys. These features together with the low values for the linear coefficient for thermal expansion in the ferromagnetic region suggest that magneto-volume anomalies, including Invar behaviour, play a major role in the magnetic properties of this system when the crystal structure is face centred cubic. Such behaviour could be explained using theoretical total-band energy calculations.
Preparation and characterization of barium titanate stannate solid solutions
Horchidan, Nadejda, E-mail: NHorchidan@stoner.phys.uaic.ro [Department of Physics, ' Al. I. Cuza' University, Bv. Carol 11, Iasi 700506 (Romania); Ianculescu, Adelina C. [Department of Oxide Materials Science and Engineering, Polytechnics University, 1-7 Gh. Polizu, P.O. Box 12-134, 011061 Bucharest (Romania); Curecheriu, Lavinia P.; Tudorache, Florin [Department of Physics, ' Al. I. Cuza' University, Bv. Carol 11, Iasi 700506 (Romania); Musteata, Valentina [Institute of Macromolecular Chemistry ' Petru Poni' , Aleea Grigore Ghica Voda 41A, 700487 Iasi (Romania); Stoleriu, Stefania [Department of Oxide Materials Science and Engineering, Polytechnics University, 1-7 Gh. Polizu, P.O. Box 12-134, 011061 Bucharest (Romania); Dragan, Nicolae; Crisan, Dorel [Institute of Physical Chemistry ' Ilie Murgulescu' , Lab. of Oxide Materials Science, 202 Splaiul Independentei, 060021 Bucharest (Romania); Tascu, Sorin; Mitoseriu, Liliana [Department of Physics, ' Al. I. Cuza' University, Bv. Carol 11, Iasi 700506 (Romania)
2011-04-07
Research highlights: > BaSnxTi1-xO3 (x = 0; 0.05; 0.1; 0.15; 0.2) ceramics were prepared by solid state reaction and sintered at 13000C for 4h. > The phase purity, structural parameters and microstructural characteristics were investigated. > The dielectric properties were studied as function of temperature and frequency and empirical parameters {eta} and {delta} were calcutate. > The non-linear dielectric properties (tunability) of the samples were studied at room temperature. > By increasing the Sn addition, the {epsilon}(E) dependence tends to reduce its hysteresis behaviour. - Abstract: BaSn{sub x}Ti{sub 1-x}O{sub 3} (x = 0; 0.05; 0.1; 0.15; 0.2) solid solutions were prepared via conventional solid state reaction and sintered at 1300 {sup o}C for 4 h, resulting in dense single phase ceramics with homogeneous microstructures. Tetragonal symmetry for x {<=} 0.1, cubic for x = 0.2 and a superposition of tetragonal and cubic for x = 0.15 compositions were found by X-ray diffraction analysis. The temperature and frequency dependence of the complex dielectric constant and dc tunability were determined. A transformation from normal ferroelectric to relaxor with diffuse phase transition was observed with increasing the Sn concentration. All the investigated compositions show a relative tunability between 0.55 (for x = 0.2) and 0.74 (for x = 0.1), at a field amplitude of E = 20 kV/cm.
Ultra-thin Solid-State Li-Ion Electrolyte Membrane Facilitated by a Self-Healing Polymer Matrix.
Whiteley, Justin M; Taynton, Philip; Zhang, Wei; Lee, Se-Hee
2015-11-18
Thin solid membranes are formed by a new strategy, whereby an in situ derived self-healing polymer matrix that penetrates the void space of an inorganic solid is created. The concept is applied as a separator in an all-solid-state battery with an FeS2 -based cathode and achieves tremendous performance for over 200 cycles. Processing in dry conditions represents a paradigm shift for incorporating high active-material mass loadings into mixed-matrix membranes.
Microstructural Evolution of Solid-solution-treated Zn-22Al in the Semisolid State
M.A.M.Arif; M.Z.Omar; N.Muhamad; J.Syarif; P.Kapranos
2013-01-01
The effect of solid-solution-treatment on the semisolid microstructure of Zn-22Al with developed dendrites was investigated.Forming Zn-22Al products by semisolid metal processing offers significant advantages,such as reductions in macro-segregation,porosity and forming costs.Thermal and microstructural analyses of the formed Zn-22Al alloy were performed by differential scanning calorimetry,scanning electron microscopy and optical microscopy.The changes in the microstructures and phase transformation in response to various solidsolution-treatments were analysed.In this study,as-cast samples were held isothermally at 330 ℃ for 0.5-5 h and then partially remelted at a semisolid temperature of 438 ℃ for 1 h to produce a solid-globular grain structure in a liquid matrix.A non-dendritic semisolid microstructure could not be obtained when the traditionally cast Zn-22Al alloy with developed dendrites was subjected directly to partial remelting.After solid-solution-treatment at 330 ℃,the black interdendritic eutectics were dissolved,and the dendritic structures gradually transformed into uniform β structures when the treatment time was increased.The coarsened and merged dendrites were separated as a result of penetration by the liquid phase and melting of the residual eutectic at sites along the former grain boundaries.The microstructure of the solid-solutiontreated sample transformed into a small globular structure; the best shape factor of 0.9,corresponding to a particle size of 40 ± 16 μm,is achieved when the sample was treated for 3 h followed by direct partial remelting into its semisolid zone.
Thakur, Neha; Kumar, Sanjukta A.; Wagh, D.N. [Analytical Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Das, Sadananda; Pandey, Ashok K. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Kumar, Sangita D., E-mail: sangdk@barc.gov.in [Analytical Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Reddy, A.V.R. [Analytical Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)
2012-01-30
Highlights: Black-Right-Pointing-Pointer Th complexed with poly (bis[2-(methacryloyloxy)-ethyl]phosphate) as tailored polymer membranes. Black-Right-Pointing-Pointer Membranes offered high capacity and selectivity for fluoride in aqueous media. Black-Right-Pointing-Pointer Quantitative uptake (80 {+-} 5%) of fluoride. Black-Right-Pointing-Pointer Fast sorption kinetics. Black-Right-Pointing-Pointer Reusability of polymer membranes. - Abstract: Fluoride related health hazards (fluorosis) are a major environmental problem in many regions of the world. It affects teeth; skeleton and its accumulation over a long period can lead to changes in the DNA structure. It is thus absolutely essential to bring down the fluoride levels to acceptable limits. Here, we present a new inorganic-organic hybrid polymer sorbent having tailored fixed-sites for fluoride sorption. The matrix supported poly (bis[2-(methacryloyloxy)-ethyl]phosphate) was prepared by photo-initiator induced graft-polymerization in fibrous and microporous (sheet) host poly(propylene) substrates. These substrates were conditioned for selective fluoride sorption by forming thorium complex with phosphate groups on bis[2-methacryloyloxy)-ethyl] phosphate (MEP). These tailored sorbents were studied for their selectivity towards fluoride in aqueous media having different chemical conditions. The fibrous sorbent was found to take up fluoride with a faster rate (15 min for Almost-Equal-To 76% sorption) than the sheet sorbent. But, the fluoride loading capacity of sheet sorbent (4320 mg kg{sup -1}), was higher than fibrous and any other sorbent reported in the literature so far. The sorbent developed in the present work was found to be reusable after desorption of fluoride using NaOH solution. It was tested for solid phase extraction of fluoride from natural water samples.
Posmyk A.
2016-06-01
Full Text Available The paper presents the theoretical basis of manufacturing and chosen applications of composite coatings with ceramic matrix containing nanomaterials as a solid lubricant (AHC+NL. From a theoretical point of view, in order to reduce the friction coefficient of sliding contacts, two materials are required, i.e. one with a high hardness and the other with low shear strength. In case of composite coatings AHC+NL the matrix is a very hard and wear resistant anodic oxide coating (AHC whereas the solid lubricant used is the nanomaterial (NL featuring a low shear strength such as glassy carbon nanotubes (GC. Friction coefficient of cast iron GJL-350 sliding against the coating itself is much higher (0.18-0.22 than when it slides against a composite coating (0.08-0.14. It is possible to reduce the friction due to the presence of carbon nanotubes, or metal nanowires.
Legendre Wavelet Operational Matrix Method for Solution of Riccati Differential Equation
S. Balaji
2014-01-01
Full Text Available A Legendre wavelet operational matrix method (LWM is presented for the solution of nonlinear fractional-order Riccati differential equations, having variety of applications in quantum chemistry and quantum mechanics. The fractional-order Riccati differential equations converted into a system of algebraic equations using Legendre wavelet operational matrix. Solutions given by the proposed scheme are more accurate and reliable and they are compared with recently developed numerical, analytical, and stochastic approaches. Comparison shows that the proposed LWM approach has a greater performance and less computational effort for getting accurate solutions. Further existence and uniqueness of the proposed problem are given and moreover the condition of convergence is verified.
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
2016-01-01
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. PMID:27991504
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.
Tackenberg, Markus W; Geisthövel, Carola; Marmann, Andreas; Schuchmann, Heike P; Kleinebudde, Peter; Thommes, Markus
2015-01-30
Essential oils and other liquid active pharmaceutical ingredients (APIs) are frequently microencapsulated to improve shelf life, handling, and for tailoring release. A glassy solid solution (GSS), a single-phase system, where the excipient is plasticized by the API, could be an alternative formulation system. Thus this study focuses on the investigation of two formulation strategies using carvacrol as a model compound, namely a microcapsule (MC) and a glassy solid solution (GSS). Applying the solubility parameter approach, polyvinylpyrrolidone (PVP) was chosen as a suitable matrix material for a GSS system, whereas maltodextrin and sucrose served as excipients for a microcapsule (MC) system. Differential scanning calorimetry (DSC) measurements of the excipients' glass transition temperatures and the melting point of carvacrol verified plasticizing properties of carvacrol on PVP. Batch mixing processes, as preliminary experiments for future extrusion processes, were performed to prepare GSSs and MCs with various amounts of carvacrol, followed by crushing and sieving. Maximally 4.5% carvacrol was encapsulated in the carbohydrate material, whereas up to 16.3% were stabilized as GSS, which is an outstanding amount. However, grinding of the samples led to a loss of up to 30% of carvacrol.
Xie, Jiaquan; Huang, Qingxue; Yang, Xia
2016-01-01
In this paper, we are concerned with nonlinear one-dimensional fractional convection diffusion equations. An effective approach based on Chebyshev operational matrix is constructed to obtain the numerical solution of fractional convection diffusion equations with variable coefficients. The principal characteristic of the approach is the new orthogonal functions based on Chebyshev polynomials to the fractional calculus. The corresponding fractional differential operational matrix is derived. Then the matrix with the Tau method is utilized to transform the solution of this problem into the solution of a system of linear algebraic equations. By solving the linear algebraic equations, the numerical solution is obtained. The approach is tested via examples. It is shown that the proposed algorithm yields better results. Finally, error analysis shows that the algorithm is convergent.
Xiu, Junshan; Dong, Lili; Qin, Hua; Liu, Yunyan; Yu, Jin
2016-12-01
The detection limit of trace metals in liquids has been improved greatly by laser-induced breakdown spectroscopy (LIBS) using solid substrate. A paper substrate and a metallic substrate were used as a solid substrate for the detection of trace metals in aqueous solutions and viscous liquids (lubricating oils) respectively. The matrix effect on quantitative analysis of trace metals in two types of liquids was investigated. For trace metals in aqueous solutions using paper substrate, the calibration curves established for pure solutions and mixed solutions samples presented large variation on both the slope and the intercept for the Cu, Cd, and Cr. The matrix effects among the different elements in mixed solutions were observed. However, good agreement was obtained between the measured and known values in real wastewater. For trace metals in lubricating oils, the matrix effect between the different oils is relatively small and reasonably negligible under the conditions of our experiment. A universal calibration curve can be established for trace metals in different types of oils. The two approaches are verified that it is possible to develop a feasible and sensitive method with accuracy results for rapid detection of trace metals in industrial wastewater and viscous liquids by laser-induced breakdown spectroscopy. © The Author(s) 2016.
Moroz, Pavel
matrix-encapsulated PbS nanocrystal films containing a tunable fraction of insulating ZnS domains, we uniquely distinguish the dynamics of charge scattering on defects from other processes of exciton dissociation. The measured times are subsequently used to estimate the diffusion length and the carrier mobility for each film type within hopping transport regime. It is demonstrated that nanocrystal films encapsulated into semiconductor matrices exhibit a lower probability of charge scattering than nanocrystal solids cross-linked with either 3-mercaptopropionic acid or 1,2-ethanedithiol molecular linkers. The suppression of carrier scattering in matrix-encapsulated nanocrystal films is attributed to a relatively low density of surface defects at nanocrystal/matrix interfaces. High stability and low density of defects made it possible to fabricate infrared-emitting nanocrystal solids. Presently, an important challenge facing the development of nanocrystal infrared emitters concerns the fact that both the emission quantum yield and the stability of colloidal nanoparticles become compromised when nanoparticle solutions are processed into solids. Here, we address this issue by developing an assembly technique that encapsulates infrared-emitting PbS NCs into crystalline CdS matrices, designed to preserve NC emission characteristics upon film processing. Here, the morphology of these matrices was designed to suppress the nonradiative carrier decay, whereby increasing the exciton lifetime up to 1 mus, and boosting the emission quantum yield to an unprecedented 3.7% for inorganically encapsulated PbS NC solids.
Investigation of Propellant and Explosive Solid Solution Systems II X-Ray Studies
1978-03-01
A\\Yj* ^\\C/*^ ^ 1 tatf AD 7t ott w AD-E400 125 TECHNICAL REPORT ARLCD-TR-77066 INVESTIGATION OF PROPELLANT AND EXPLOSIVE SOLID SOLUTION SYSTEMS...Report ARLCD-TR-77066 2. GOVT ACCESSION NO. *. TITLE (and Subtitle) INVESTIGATION OF PROPELLANT AND EXPLOSIVE SOLID SOLUTION SYSTEMS II X-RAY...Interplanar spacings and x-ray diffraction 9 intensities of AP, KP and their physical mixtures and solid solutions 4 X-ray data of 3 AN: KP solid solution and
Yudanova, L. I.; Logvinenko, V. A.; Sheludyakova, L. A.; Ishchenko, A. V.; Rudina, N. A.
2017-01-01
XRD phase analysis and thermal analysis are used to confirm the formation of a continuous series of solid solutions in which one cation is substituted for another in the systems Co(II) hydrogen maleate-Ni(II) hydrogen maleate; Fe(II) hydrogen maleate-Co(II) hydrogen maleate; and Fe(II) hydrogen maleate-Ni(II) hydrogen maleate. The unit cell volume of these solid solutions is shown to depend linearly on their composition. The linear character of changes in the initial temperatures of dehydration and thermal decomposition is established. Using the example of the first of these systems, it is shown that when heated, bimetallic nanoparticles embedded in the polymeric matrix of composites obtained via the thermal decomposition of solid solutions of hydrogen maleates undergo a second-order phase transition, resulting in decomposition of the solid solutions of metals at the Curie temperature.
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
Ateshian, Gerard A; Nims, Robert J; Maas, Steve; Weiss, Jeffrey A
2014-10-01
Mechanobiological processes are rooted in mechanics and chemistry, and such processes may be modeled in a framework that couples their governing equations starting from fundamental principles. In many biological applications, the reactants and products of chemical reactions may be electrically charged, and these charge effects may produce driving forces and constraints that significantly influence outcomes. In this study, a novel formulation and computational implementation are presented for modeling chemical reactions in biological tissues that involve charged solutes and solid-bound molecules within a deformable porous hydrated solid matrix, coupling mechanics with chemistry while accounting for electric charges. The deposition or removal of solid-bound molecules contributes to the growth and remodeling of the solid matrix; in particular, volumetric growth may be driven by Donnan osmotic swelling, resulting from charged molecular species fixed to the solid matrix. This formulation incorporates the state of strain as a state variable in the production rate of chemical reactions, explicitly tying chemistry with mechanics for the purpose of modeling mechanobiology. To achieve these objectives, this treatment identifies the specific theoretical and computational challenges faced in modeling complex systems of interacting neutral and charged constituents while accommodating any number of simultaneous reactions where reactants and products may be modeled explicitly or implicitly. Several finite element verification problems are shown to agree with closed-form analytical solutions. An illustrative tissue engineering analysis demonstrates tissue growth and swelling resulting from the deposition of chondroitin sulfate, a charged solid-bound molecular species. This implementation is released in the open-source program FEBio ( www.febio.org ). The availability of this framework may be particularly beneficial to optimizing tissue engineering culture systems by examining the
On the Parametric Solution to the Second-Order Sylvester Matrix Equation EVF2−AVF−CV=BW
Wang Guo-Sheng
2007-01-01
Full Text Available This paper considers the solution to a class of the second-order Sylvester matrix equation EVF2−AVF−CV=BW. Under the controllability of the matrix triple (E,A,B, a complete, general, and explicit parametric solution to the second-order Sylvester matrix equation, with the matrix F in a diagonal form, is proposed. The results provide great convenience to the analysis of the solution to the second-order Sylvester matrix equation, and can perform important functions in many analysis and design problems in control systems theory. As a demonstration, an illustrative example is given to show the effectiveness of the proposed solution.
Sustainable solutions for solid waste management in Southeast Asian countries.
Ngoc, Uyen Nguyen; Schnitzer, Hans
2009-06-01
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.
Study of solid solution strengthening of alloying element with phase structure factors
无
2003-01-01
Using the empirical electron theory of solids and molecules (EET), the phase structure factors, nA and nB, of the carbon-containing structural units with mass fraction of carbon (wC) below 0.8% and the mono-alloy structural units with wC at 0.2% in austenite and martensite are calculated. The solid solution strengthening brought by C-containing interstitial solid solution and alloy-substitutional solid solution in γ-Fe and α-Fe is discussed at electron structural level. The coefficient (s) of solid solution strengthening is advanced according to the bonding force between atoms. The study shows that when the criterion is applied to the carbonaceous or alloying element-containing solid solution the results of calculation will coincide with the experimental result very well.
(Anti-Hermitian Generalized (Anti-Hamiltonian Solution to a System of Matrix Equations
Juan Yu
2014-01-01
Full Text Available We mainly solve three problems. Firstly, by the decomposition of the (anti-Hermitian generalized (anti-Hamiltonian matrices, the necessary and sufficient conditions for the existence of and the expression for the (anti-Hermitian generalized (anti-Hamiltonian solutions to the system of matrix equations AX=B,XC=D are derived, respectively. Secondly, the optimal approximation solution minX∈K∥X^-X∥ is obtained, where K is the (anti-Hermitian generalized (anti-Hamiltonian solution set of the above system and X^ is the given matrix. Thirdly, the least squares (anti-Hermitian generalized (anti-Hamiltonian solutions are considered. In addition, algorithms about computing the least squares (anti-Hermitian generalized (anti-Hamiltonian solution and the corresponding numerical examples are presented.
Thermodynamic properties of the cubic plutonium hydride solid solution
Haschke, J M
1981-12-01
Pressure, temperature, and composition data for the cubic solid solution plutonium hydride phase, PuH/sub x/, have been measured by microbalance methods. Integral enthalpies and entropies of formation have been evaluated for the composition range 1.90 less than or equal to X less than or equal to 3.00. At 550/sup 0/K, ..delta..H/sup 0/ /sub f/(PuH/sub x/(s)) varies linearly from approximately (-38 +- 1) kcal mol/sup -1/ at PuH/sub 190/ to (-50 +- 1 kcal mol/sup -1/) at PuH/sub 3/ /sub 00/. Thermochemical values obtained by reevaluating tensimetric data from the literature are in excellent agreement with these results. Isotopic effects have been quantified by comparing the results for hydride and deuteride, and equations are presented for predicting ..delta..H/sup 0/ /sub f/ and ..delta..S/sup 0/ /sub f/ values for PuH/sub x/(s) and PuD/sub x/(s).
Extended solid solutions and coherent transformations in nanoscale olivine cathodes.
Ravnsbæk, D B; Xiang, K; Xing, W; Borkiewicz, O J; Wiaderek, K M; Gionet, P; Chapman, K W; Chupas, P J; Chiang, Y-M
2014-03-12
Nanoparticle LiFePO4, the basis for an entire class of high power Li-ion batteries, has recently been shown to exist in binary lithiated/delithiated states at intermediate states of charge. The Mn-bearing version, LiMn(y)Fe(1-y)PO4, exhibits even higher rate capability as a lithium battery cathode than LiFePO4 of comparable particle size. To gain insight into the cause(s) of this desirable performance, the electrochemically driven phase transformation during battery charge and discharge of nanoscale LiMn0.4Fe0.6PO4 of three different average particle sizes, 52, 106, and 152 nm, is investigated by operando synchrotron radiation powder X-ray diffraction. In stark contrast to the binary lithiation states of pure LiFePO4 revealed in recent investigations, the formations of metastable solid solutions covering a remarkable wide compositional range, including while in two-phase coexistence, are observed. Detailed analysis correlates this behavior with small elastic misfits between phases compared to either pure LiFePO4 or LiMnPO4. On the basis of time- and state-of-charge dependence of the olivine structure parameters, we propose a coherent transformation mechanism. These findings illustrate a second, completely different phase transformation mode for pure well-ordered nanoscale olivines compared to the well-studied case of LiFePO4.
Solidification and crystal growth of solid solution semiconducting alloys
Lehoczky, S.L.; Szofran, F.R.
1984-10-01
Problems associated with the solidification and crytal growth of solid-solution semiconducting alloy crystals in a terrestrial environment are described. A detailed description is given of the results for the growth of mercury cadmium telluride (HgCdTe) alloy crystals by directional solidification, because of their considerable technological importance. A series of HgCdTe alloy crystals are grown from pseudobinary melts by a vertical Bridgman method using a wide range of growth rates and thermal conditions. Precision measurements are performed to establish compositional profiles for the crystals. The compositional variations are related to compositional variations in the melts that can result from two-dimensional diffusion or density gradient driven flow effects ahead of the growth interface. These effects are discussed in terms of the alloy phase equilibrium properties, the recent high temperature thermophysical data for the alloys and the highly unusual heat transfer characteristics of the alloy/ampule/furnace system that may readily lead to double diffusive convective flows in a gravitational environment.
Solidification and crystal growth of solid solution semiconducting alloys
Lehoczky, S. L.; Szofran, F. R.
1984-01-01
Problems associated with the solidification and crytal growth of solid-solution semiconducting alloy crystals in a terrestrial environment are described. A detailed description is given of the results for the growth of mercury cadmium telluride (HgCdTe) alloy crystals by directional solidification, because of their considerable technological importance. A series of HgCdTe alloy crystals are grown from pseudobinary melts by a vertical Bridgman method using a wide range of growth rates and thermal conditions. Precision measurements are performed to establish compositional profiles for the crystals. The compositional variations are related to compositional variations in the melts that can result from two-dimensional diffusion or density gradient driven flow effects ahead of the growth interface. These effects are discussed in terms of the alloy phase equilibrium properties, the recent high temperature thermophysical data for the alloys and the highly unusual heat transfer characteristics of the alloy/ampule/furnace system that may readily lead to double diffusive convective flows in a gravitational environment.
Matrix integral solutions to the discrete KP hierarchy and its Pfaffianized version
Lafortune, Stéphane; Li, Chun-Xia
2016-11-01
Matrix integrals used in random matrix theory for the study of eigenvalues of Hermitian ensembles have been shown to provide τ-functions for several hierarchies of integrable equations. In this article, we extend this relation by showing that such integrals can also provide τ-functions for the discrete KP hierarchy and a coupled version of the same hierarchy obtained through the process of Pfaffianization. To do so, we consider the first equation of the discrete KP hierarchy, the Hirota-Miwa equation. We write the Wronskian determinant solutions to the Hirota-Miwa equation and consider a particular form of matrix integrals, which we show is an example of those Wronskian solutions. The argument is then generalized to the whole hierarchy. A similar strategy is used for the Pfaffianized version of the hierarchy except that in that case, the solutions are written in terms of Pfaffians rather than determinants.
无
2007-01-01
A real n × n symmetric matrix X = (xij)n×n is called a bisymmetric matrix if xij = xn+1-j,n+1-i. Based on the projection theorem, the canonical correlation decomposition and the generalized singular value decomposition, a method useful for finding the least-squares solutions of the matrix equation ATXA = B over bisymmetric matrices is proposed. The expression of the least-squares solutions is given. Moreover, in the corresponding solution set, the optimal approximate solution to a given matrix is also derived. A numerical algorithm for finding the optimal approximate solution is also described.
Exact solution of qubit decoherence models by a transfer matrix method
Nghiem, D; Joynt, Robert; Nghiem, Diu
2005-01-01
We present a new method for the solution of the behavior of an enesemble of qubits in a random time-dependent external field. The forward evolution in time is governed by a transfer matrix. The elements of this matrix determine the various decoherence times. The method provides an exact solution in cases where the noise is piecewise constant in time. We show that it applies, for example, to a realistic model of decoherence of electron spins in semiconductors. Results are obtained for the non-perturbative regimes of the models, and we see a transition from weak relaxation to overdamped behavior as a function of noise anisotropy.
Kisel, V V; Red'kov, V M; Tokarevskaya, N G
2009-01-01
The Riemann -- Silberstein -- Majorana -- Oppenheimer approach to the Maxwell electrodynamics in vacuum is investigated within the matrix formalism. The matrix form of electrodynamics includes three real 4 \\times 4 matrices. Within the squaring procedure we construct four formal solutions of the Maxwell equations on the base of scalar Klein -- Fock -- Gordon solutions. The problem of separating physical electromagnetic waves in the linear space \\lambda_{0}\\Psi^{0}+\\lambda_{1}\\Psi^{1}+\\lambda_{2}\\Psi^{2}+ lambda_{3}\\Psi^{3} is investigated, several particular cases, plane waves and cylindrical waves, are considered in detail.
Integrating matrix solution of the hybrid state vector equations for beam vibration
Lehman, L. L.
1982-01-01
A simple, versatile, and efficient computational technique has been developed for dynamic analysis of linear elastic beam and rod type of structures. Moreover, the method provides a rather general solution approach for two-point boundary value problems that are described by a single independent spatial variable. For structural problems, the method is implemented by a mixed state vector formulation of the differential equations, combined with an integrating matrix solution procedure. Highly accurate solutions are easily achieved with this approach. Example solutions are given for beam vibration problems including discontinuous stiffness and mass parameters, elastic restraint boundary conditions, concentrated inertia loading, and rigid body modes
SDP-based approximation of stabilising solutions for periodic matrix Riccati differential equations
Gusev, Sergei V.; Shiriaev, Anton S.; Freidovich, Leonid B.
2016-07-01
Numerically finding stabilising feedback control laws for linear systems of periodic differential equations is a nontrivial task with no known reliable solutions. The most successful method requires solving matrix differential Riccati equations with periodic coefficients. All previously proposed techniques for solving such equations involve numerical integration of unstable differential equations and consequently fail whenever the period is too large or the coefficients vary too much. Here, a new method for numerical computation of stabilising solutions for matrix differential Riccati equations with periodic coefficients is proposed. Our approach does not involve numerical solution of any differential equations. The approximation for a stabilising solution is found in the form of a trigonometric polynomial, matrix coefficients of which are found solving a specially constructed finite-dimensional semidefinite programming (SDP) problem. This problem is obtained using maximality property of the stabilising solution of the Riccati equation for the associated Riccati inequality and sampling technique. Our previously published numerical comparisons with other methods shows that for a class of problems only this technique provides a working solution. Asymptotic convergence of the computed approximations to the stabilising solution is proved below under the assumption that certain combinations of the key parameters are sufficiently large. Although the rate of convergence is not analysed, it appeared to be exponential in our numerical studies.
CH{sub 3} spin probe in solid Kr: Matrix structure and guest–host interaction
Dmitriev, Yu.A., E-mail: dmitrievyurij@gmail.com [Ioffe Institute, 26 Politekhnicheskaya ul., 194021 St. Petersburg (Russian Federation); Melnikov, V.D. [Ioffe Institute, 26 Politekhnicheskaya ul., 194021 St. Petersburg (Russian Federation); Styrov, K.G. [Institute of Computing and Control, St. Petersburg State Polytechnical University, 29 Politekhnicheskaya ul., 195251 St. Petersburg (Russian Federation); Benetis, N.P. [Department of Pollution Control, Technological Education Institution, TEI, West Macedonia, Kozani 501 00 (Greece)
2015-02-01
Experimental EPR data obtained for the methyl, CH{sub 3}, radical trapped in quench condensed solid Kr are analyzed rendering the radical a probe for determination of regional disorder in Kr and similar solid matrices. Formation of regions of a highly disordered local matrix structure is proved. An attempt is presented of assessing a disorder parameter, based on the line broadening. The new structure is shown to be very effective in accumulating the radicals which are transiently mobile at the Kr 4.2 K surface. We discuss a model of the trapped radical rotation, which includes somewhat different mechanism than the hindrance of the rotation about the C{sub 3} axis and the rotation about the in-plane C{sub 2} axes. The level of the thermal contact of the radical spin-rotation motion with the lattice degrees of freedom in regions of varying order in the Kr solid matrix was assessed by progressive saturation curve-fitting parameters related to the spin-lattice relaxation time T{sub 1} of the radical.
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...
Alloying Solid Solution Strengthening of Fe-Ga Alloys: A First-Principle Study
2006-01-01
effect from alloying additions of Nb, Mo, V, Cr and Co in cubic solid solution of Fe-Ga alloys. Mayer bond order "BO" values were used to evaluate the...that transition metal Nb achieves the best strengthening effect in Fe-Ga alloys. The solid solution strengthening follows a trend from larger to
Iterative solutions to the steady-state density matrix for optomechanical systems
Nation, P. D.; Johansson, J. R.; Blencowe, M. P.; Rimberg, A. J.
2015-01-01
We present a sparse matrix permutation from graph theory that gives stable incomplete lower-upper preconditioners necessary for iterative solutions to the steady-state density matrix for quantum optomechanical systems. This reordering is efficient, adding little overhead to the computation, and results in a marked reduction in both memory and runtime requirements compared to other solution methods, with performance gains increasing with system size. Either of these benchmarks can be tuned via the preconditioner accuracy and solution tolerance. This reordering optimizes the condition number of the approximate inverse and is the only method found to be stable at large Hilbert space dimensions. This allows for steady-state solutions to otherwise intractable quantum optomechanical systems.
Iterative solutions to the steady state density matrix for optomechanical systems
Nation, P D; Blencowe, M P; Rimberg, A J
2014-01-01
We present a sparse matrix permutation from graph theory that gives stable incomplete Lower-Upper (LU) preconditioners necessary for iterative solutions to the steady state density matrix for quantum optomechanical systems. This reordering is efficient, adding little overhead to the computation, and results in a marked reduction in both memory and runtime requirements compared to other solution methods, with performance gains increasing with system size. Either of these benchmarks can be tuned via the preconditioner accuracy and solution tolerance. This reordering optimizes the condition number of the approximate inverse, and is the only method found to be stable at large Hilbert space dimensions. This allows for steady state solutions to otherwise intractable quantum optomechanical systems.
Solid solution, phase separation, and cathodoluminescence of GaP-ZnS nanostructures.
Liu, Baodan; Bando, Yoshio; Dierre, Benjamin; Sekiguchi, Takashi; Golberg, Dmitri; Jiang, Xin
2013-09-25
Quaternary solid-solution nanowires made of GaP and ZnS have been synthesized through well-designed synthetic routines. The as-synthesized GaP-ZnS solid-solution nanowires exhibit decent crystallinity with the GaP phase as the host, while a large amount of twin structural defects are observed in ZnS-rich nanowires. Cathodoluminescence studies showed that GaP-rich solid-solution nanowires have a strong visible emission centered at 600 nm and the ZnS-rich solid-solution nanowires exhibited a weak emission peak in the UV range and a broad band in the range 400-600 nm. The formation mechanism, processes, and optical emissions of GaP-ZnS solid-solution nanowires were discussed in detail.
Surfactant-free solid dispersion of fat-soluble flavour in an amorphous sugar matrix.
Satoh, Tomo; Hidaka, Fumihiro; Miyake, Kento; Yoshiyama, Natsuki; Takeda, Koji; Matsuura, Tsutashi; Imanaka, Hiroyuki; Ishida, Naoyuki; Imamura, Koreyoshi
2016-04-15
A solid dispersion technique to homogeneously disperse hydrophobic ingredients in a water-soluble solid without using surfactant was examined as follows: first, freeze-dried amorphous sugar was dissolved in an organic medium that contained a soluble model hydrophobic component. Second, the mixed solution of sugar and the model hydrophobic component was vacuum dried into a solid (solid dispersion). Methanol and six fat-soluble flavours, including cinnamaldehyde, were used as organic media and model hydrophobic components. The retention of flavours in the solid dispersion during drying and storage under vacuum was evaluated. The amorphised disaccharides dissolved in methanol up to 100mg/mL, even temporarily (20s to 10 days) and could be solidified without any evidence of crystallisation and segregation from flavour. The solid dispersion, prepared using α-maltose usually showed 65-95% flavour retention during drying (and storage for cinnamaldehyde), whereas ⩾ 50% of the flavour was lost when the flavour was O/W emulsified with a surfactant and then freeze-dried with sugar.
SOLID POLYMERIC MATRIX BASED ON CHITOSAN AND XANTHAN FOR CONTROLLED RELEASE OF FERTILIZERS
Mariana A. Melaj
2012-03-01
Full Text Available The main purpose of this work was to optimize the preparation conditions of solid polymeric matrix based on Chitosan and Xanthan, to be used in the controlled release of fertilizers. KNO3 was chosen as model agrochemical to be released. Both individual polymers and the Xanthan:Chitosan complex are biocompatible, leaving a residue on the soil which is non-toxic. The influence of different variables on the release pattern was studied: the type of polymer, the pressed conditions of the tablets and the presence of a drug-free polymeric coating. The polymer that presented a more promising release profile was Xanthan. The compression pressure applied to prepare the tablets was a more relevant variable than the compression time, in its effect on the kinetics of release. It was determined that the coating of the polymer matrix with crosslinked chitosan-glutaraldehyde allows getting a larger release time.
Mechanism of the radiation-induced transformations of fluoroform in solid noble gas matrixes
Sosulin, Ilya S.; Shiryaeva, Ekaterina S.; Feldman, Vladimir I.
2017-09-01
The X-ray induced transformations in the CHF3/Ng systems (Ng=Ne, Ar, Kr or Xe) at 6 K were studied by FTIR spectroscopy. The radiation-induced decomposition of CHF3 was found to be rather inefficient in solid xenon with low ionization energy, which suggests primary significance of the positive hole transfer from matrix to the fluoroform molecule. CF3•, :CF2, CHF2• and CF4 were identified as the products of low-temperature radiolysis in all the noble gas matrixes. In addition, the anionic complex HF ⋯ CF2- was detected in Ne and Ar matrixes. The radiolysis also resulted in formation of noble gas compounds (HArF in argon, HKrF in krypton, and XeF2 in xenon). While XeF2 and HArF were essentially formed directly after irradiation (presumably due to reactions of 'hot' fluorine atoms), HKrF mainly resulted from annealing of irradiated samples below 20 K due to thermally induced mobility of trapped fluorine atoms. In both krypton and xenon matrixes, the thermally induced reactions of F atoms occur at lower temperatures than those of H atoms, while the opposite situation is observed in argon. The mechanisms of the radiation-induced processes and their implications are discussed.
Solid-matrix luminescence analysis. Final technical report, June 15, 1986--June 14, 1995
Hurtubise, R.J.
1996-09-01
In this report, the major results and conclusions of the research over the last two years and five months will be considered. The report discusses the physicochemical interactions discovered that are important for solid-matrix luminescence (SML), and the development of new interaction models which are very useful for the understanding the phenomena that are relevant for SML. The SML of 4-phenylphenol and 2-phenyl phenol adsorbed on filter paper is described. In addition, some new analytical methodology and applications are discussed.
Solutions to the generalized Sylvester matrix equations by a singular value decomposition
无
2007-01-01
In this paper,solutions to the generalized Sylvester matrix equations AX-XF=BY and MXN-X=TY with A,M∈Rn×n,B,T∈Rn×n,F,N∈Rp×p and the matrices N,F being in companion form,are established by a singular value decomposition of a matrix with dimensions n×(n+pr).The algorithm proposed in this paper for the euqation AX-XF=BY does not require the controllability of matrix pair(A,B)andthe restriction that A,F do not have common eigenvalues.Since singular value decomposition is adopted,the algorithm is numerically stable and may provide great convenience to the computation of the solution to these equations,and can perform important functions in many design problems in control systems theory.
Classification of all 1/2 BPS solutions of the tiny graviton matrix theory
Sheikh-Jabbari, Mohammad M. [Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Torabian, Mahdi [Institute for Studies in Theoretical Physics and Mathematics (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)
2005-04-01
The tiny graviton Matrix theory [1] is proposed to describe DLCQ of type IIB string theory on the maximally supersymmetric plane-wave or AdS{sub 5} x S{sup 5} background. In this paper we provide further evidence in support of the tiny graviton conjecture by focusing on the zero energy, half BPS configurations of this matrix theory and classify all of them. These vacua are generically of the form of various three sphere giant gravitons. We clarify the connection between our solutions and the half BPS configuration in N = 4 SYM theory and their gravity duals. Moreover, using our half BPS solutions, we show how the tiny graviton Matrix theory and the mass deformed D = 3,N = 8 superconformal field theories are related to each other.
Matrix Bounds for the Solution of the Continuous Algebraic Riccati Equation
Juan Zhang
2010-01-01
Full Text Available We propose new upper and lower matrix bounds for the solution of the continuous algebraic Riccati equation (CARE. In certain cases, these lower bounds improve and extend the previous results. Finally, we give a corresponding numerical example to illustrate the effectiveness of our results.
ANALYSIS OF TWO-MACHINE CONWIP SYSTEM:MATRIX GEOMETRIC SOLUTION
LIU Bin; YUE Dequan; CAO Jinhua; WANG Huanqiu
2000-01-01
In this paper we consider a two-machine CONWIP system. Firstly, we mathematically model the system as a QBD process. By using the matrix geometric solution technique, we obtain the equilibrium conditions of the system. Next, we derive the stationary probability distribution of the process. Finally, we give some important performance measures of the system.
A biomimetic composite from solution self-assembly of chitin nanofibers in a silk fibroin matrix.
Jin, Jungho; Hassanzadeh, Pegah; Perotto, Giovanni; Sun, Wei; Brenckle, Mark A; Kaplan, David; Omenetto, Fiorenzo G; Rolandi, Marco
2013-08-27
A chitin nanofiber-silk biomimetic nanocomposite with enhanced mechanical properties is self-assembled from solution to yield ultrafine chitin nanofibers embedded in a silk matrix. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Espinoza, D. N.; Vandamme, M.; Dangla, P.; Pereira, J.-M.; Vidal-Gilbert, S.
2013-12-01
Understanding the adsorption-induced swelling in coal is critical for predictable and enhanced coal bed methane production. The coal matrix is a natural anisotropic disordered microporous solid. We develop an elastic transverse isotropic poromechanical model for microporous solids which couples adsorption and strain through adsorption stress functions and expresses the adsorption isotherm as a multivariate function depending on fluid pressure and solid strains. Experimental data from the literature help invert the anisotropic adsorptive-mechanical properties of Brzeszcze coal samples exposed to CO2. The main findings include the following: (1) adsorption-induced swelling can be modeled by including fluid-specific and pressure-dependent adsorption stress functions into equilibrium equations, (2) modeling results suggest that swelling anisotropy is mostly caused by anisotropy of the solid mechanical properties, and (3) the total amount of adsorbed gas measured by immersing coal in the adsorbate overestimates adsorption amount compared to in situ conditions up to ˜20%. The developed fully coupled model can be upscaled to determine the coal seam permeability through permeability-stress relationships.
Solonenko, O. P.
2012-12-01
A theoretical model has been developed to describe the splats formation from composite particles of several tens of micrometers in size whose liquid metal binder contains a high volume concentration of ultra-fine refractory solid inclusions uniformly distributed in the binder. A theoretical solution was derived, enabling evaluation of splat thickness and diameter, and also the contact temperature at the particle-substrate interface, under complete control of key physical parameters (KPPs) of the spray process (impact velocity, temperature, and size of the particle, and substrate temperature) versus the concentration of solid inclusions suspended in the metal-binder melt. Using the solution obtained, the calculations performed demonstrate the possibility of formulating adequate requirements on the KPPs of particle-substrate interaction providing a deposition of ceramic-metal coatings with predictable splat thickness and degree of particle flattening on the substrate, and also with desired contact temperature during the formation of the first coating monolayer.
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.
(Anti-)Hermitian Generalized (Anti-)Hamiltonian Solution to a System of Matrix Equations
Juan Yu; Qing-Wen Wang; Chang-Zhou Dong
2014-01-01
We mainly solve three problems. Firstly, by the decomposition of the (anti-)Hermitian generalized (anti-)Hamiltonian matrices, the necessary and sufficient conditions for the existence of and the expression for the (anti-)Hermitian generalized (anti-)Hamiltonian solutions to the system of matrix equations AX=B,XC=D are derived, respectively. Secondly, the optimal approximation solution minX∈K∥X^-X∥ is obtained, where K is the (anti-)Hermitian generalized (anti-)Hamiltonian solution set of t...
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....
Evolution of mixed surfactant aggregates in solutions and at solid/solution interfaces
Zhang, Rui
Surfactant systems have been widely used in such as enhanced oil recovery, waste treatment and metallurgy, etc., in order to solve the problem of global energy crisis, to remove the pollutants and to generate novel energy resources. Almost all surfactant systems are invariably mixtures due to beneficial and economic considerations. The sizes and shapes of aggregates in solutions and at solid/solution interfaces become important, since the nanostructures of mixed aggregates determine solution and adsorption properties. A major hurdle in science is the lack of information on the type of complexes and aggregates formed by mixtures and the lack of techniques for deriving such information. Using techniques such as analytical ultracentrifuge, small angle neutron scattering, surface tension, fluorescence, cryo-TEM, light scattering and ultrafiltration, the nanostructures of aggregates of sugar based n-dodecyl-beta-D-maltoside (DM) and nonionic pentaethyleneglycol monododecyl ether or nonyl phenol ethoxylated decyl ether (NP-10) and their mixtures have been investigated to prove the hypothesis that the aggregation behavior is linked to packing of the surfactant governed by the molecular interactions as well as the molecular structures. The results from both sedimentation velocity and sedimentation equilibrium experiments suggest coexistence of two types of micelles in nonyl phenol ethoxylated decyl ether solutions and its mixtures with n-dodecyl-beta-D-maltoside while only one micellar species is present in n-dodecyl-beta-D-maltoside solutions, in good agreement with those from small angle neutron scattering, cryo-TEM, light scattering and ultrafiltration. Type I micelles were primary micelles at cmc while type II micelles were elongated micelles. On the other hand, the nanostructures of mixed surface aggregates have been quantitatively predicted for the first time using a modified packing index. As a continuation of the Somasundaran-Fuersteneau adsorption model, a
Zheng, Ping; Sheng, Xuan; Yu, Xiaofeng; Hu, Yanyun
2006-01-01
A new method based on matrix solid-phase dispersion (MSPD) extraction with neutral alumina and co-column purification with graphitized carbon black has been developed to determine aflatoxins B1, B2, G1, G2 in hot chilli products. The method includes liquid chromatography and fluorescence detection with on-line post-column derivatization with bromine. Optimization of different parameters, such as the type of solid supports for matrix dispersion and co-column clean-up was carried out. The recoveries of aflatoxins B1, B2, G1 and G2 were 95.4%, 87.3%, 91.5% and 92.6%, respectively, with relative standard deviations ranging from 3.3% to 6.1%. The limits of detection were in the range of 0.10 ng/g (B2, G2) to 0.25 ng/g (B1, G1). In addition, the comparison of the extraction and purification effect of MSPD with immunity affinity column showed that, MSPD is a valid method to analyze aflatoxins in hot chilli products.
Determination of aflatoxins in rice samples by ultrasound-assisted matrix solid-phase dispersion.
Manoochehri, Mahboobeh; Asgharinezhad, Ali Akbar; Safaei, Mahdi
2015-01-01
This work describes the application of ultrasound-assisted matrix solid-phase dispersion as an extraction and sample preparation approach for aflatoxins (B1, B2, G1 and G2) and subsequent determination of them by high-performance liquid chromatography-fluorescence detection. A Box-Behnken design in combination with response surface methodology was used to determine the affecting parameters on the extraction procedure. The influence of different variables including type of dispersing phase, sample-to-dispersing phase ratio, type and quantity of clean-up phase, ultrasonication time, ultrasonication temperature, nature and volume of the elution solvent was investigated in the optimization study. C18, primary-secondary amine (PSA) and acetonitrile were selected as dispersing phase, clean-up phase and elution solvent, respectively. The obtained optimized values were sample-to-dispersing phase ratio of 1 : 1, 60 mg of PSA, 11 min ultrasonication time, 30°C ultrasonication temperature and 4 mL acetonitrile. Under the optimal conditions, the limits of detection were ranged from 0.09 to 0.14 ng g(-1) and the precisions [relative standard deviation (RSD%)] were <8.6%. The recoveries of the matrix solid-phase dispersion process ranged from 78 to 83% with RSD <10% in all cases. Finally, this method was successfully applied to the extraction of trace amounts of aflatoxins in rice samples. © The Author [2014]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Exact matrix product solutions in the Heisenberg picture of an open quantum spin chain
Clark, S R; Jaksch, D [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore); Prior, J [Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU (United Kingdom); Hartmann, M J [Technische Universitaet Muenchen, Physik Department I, James Franck Strasse, 85748 Garching (Germany); Plenio, M B [Institute for Mathematical Sciences, Imperial College London, SW7 2PG (United Kingdom)], E-mail: s.clark@physics.ox.ac.uk
2010-02-15
In recent work, Hartmann et al (2009 Phys. Rev. Lett. 102 057202) demonstrated that the classical simulation of the dynamics of open 1D quantum systems with matrix product algorithms can often be dramatically improved by performing time evolution in the Heisenberg picture. For a closed system this was exemplified by an exact matrix product operator (MPO) solution of the time-evolved creation operator of a quadratic fermi chain with a matrix dimension of just two. In this work, we show that this exact solution can be significantly generalized to include the case of an open quadratic fermi chain subjected to master equation evolution with Lindblad operators that are linear in the fermionic operators. Remarkably even in this open system the time evolution of operators continues to be described by MPOs with the same fixed dimension as that required by the solution of a coherent quadratic fermi chain for all times. Through the use of matrix product algorithms the dynamical behaviour of operators in this non-equilibrium open quantum system can be computed with a cost that is linear in the system size. We present some simple numerical examples that highlight how useful this might be for the more detailed study of open system dynamics. Given that Heisenberg picture simulations have been demonstrated to offer significant accuracy improvements for other open systems that are not exactly solvable, our work also provides further insight into how and why this advantage arises.
Qi Song
2013-01-01
Full Text Available This paper proposes a partial refactorization for faster nonlinear analysis based on sparse matrix solution, which is nowadays the default solution choice in finite element analysis and can solve finite element models up to millions degrees of freedom. Among various fill-in’s reducing strategies for sparse matrix solution, the graph partition is in general the best in terms of resultant fill-ins and floating-point operations and furthermore produces a particular graph of sparse matrix that prevents local change of entries from wide spreading in factorization. Based on this feature, an explicit partial triangular refactorization with local change is efficiently constructed with limited additional storage requirement in row-sparse storage scheme. The partial refactorization of the changed stiffness matrix inherits a big percentage of the original factor and is carried out only on partial factor entries. The proposed method provides a new possibility for faster nonlinear analysis and is mainly suitable for material nonlinear problems and optimization problems. Compared to full factorization, it can significantly reduce the factorization time and can make nonlinear analysis more efficient.
Preparation and Photocatalytic Properties of Ti1-xZrxO2 Solid Solution
GAO,Bi-Fen; MA,Ying; CAO,Ya-An; GU,Zhan-Jun; ZHANG,Guang-Jin; YAO,Jian-Nian
2007-01-01
A series of Ti1-xZrxO2 materials were synthesized through a multistep sol-gel process.The structural characteristics were investigated using X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and Raman measurements.The experimental results showed that a solid solution could be obtained at low Zr/(Ti+Zr)molar ratios(x≤0.319).Raman measurements exhibited that the presence of zirconium in the solid solutions greatly retarded the amoorphous-anatase and anatase-rutile transitions.The diffuse reflectance UV-Vis spectra revealed that the bandgap of the solid solution was enlarged gradually with the increment of incorporated zirconium content.The Til-xZrxO2solid solutions exhibited higher photocatalytic activity than pure TiO2 for the degradation of 4-chlorophenol aqueous solution.
Comparisons of species and coagulation effects of PFS solution and solid PFS from pyrite cinders
郑雅杰; 龚竹青; 刘立华; 陈白珍
2002-01-01
Pyrite cinder is a kind of solid waste of sulfuric acid industry. After mixing pyrite cinders with sulfuric acid, ferric sulfate was obtained by heating, maturing, dissolving and filtrating. Suitable amounts of FeSO4 * 7H2O and NaClO3 were added into ferric sulfate solution and polyferric sulfate(PFS) solution was produced. Solid PFS was made by concentrating and drying PFS solution. Time-dependent complex colorimetric tests were done while ferron agent reacted with Fe3+ in the solution. The results show that the proportion of transitional low polymeric species and high polymeric species are increased after PFS solution is transferred into solid PFS. It was discovered by jar tests that solid PFS has very good coagulation effects relevant to the increase of transitional lower polymeric species.
Wang, J. C.
1982-01-01
Compositional segregation of solid solution semiconducting alloys in the radial direction during unidirectional solidification was investigated by calculating the effect of a curved solid liquid interface on solute concentration at the interface on the solid. The formulation is similar to that given by Coriell, Boisvert, Rehm, and Sekerka except that a more realistic cylindrical coordinate system which is moving with the interface is used. Analytical results were obtained for very small and very large values of beta with beta = VR/D, where V is the velocity of solidification, R the radius of the specimen, and D the diffusivity of solute in the liquid. For both very small and very large beta, the solute concentration at the interface in the solid C(si) approaches C(o) (original solute concentration) i.e., the deviation is minimal. The maximum deviation of C(si) from C(o) occurs for some intermediate value of beta.
Xue, Yaosuo [ORNL
2016-01-01
The matrix converter solid state transformer (MC-SST), formed from the back-to-back connection of two three-to-single-phase matrix converters, is studied for use in the interconnection of two ac grids. The matrix converter topology provides a light weight and low volume single-stage bidirectional ac-ac power conversion without the need for a dc link. Thus, the lifetime limitations of dc-bus storage capacitors are avoided. However, space vector modulation of this type of MC-SST requires to compute vectors for each of the two MCs, which must be carefully coordinated to avoid commutation failure. An additional controller is also required to control power exchange between the two ac grids. In this paper, model predictive control (MPC) is proposed for an MC-SST connecting two different ac power grids. The proposed MPC predicts the circuit variables based on the discrete model of MC-SST system and the cost function is formulated so that the optimal switch vector for the next sample period is selected, thereby generating the required grid currents for the SST. Simulation and experimental studies are carried out to demonstrate the effectiveness and simplicity of the proposed MPC for such MC-SST-based grid interfacing systems.
Kamal, Ayman; Giurgiutiu, Victor
2014-03-01
This paper discusses combined transfer matrix method (TMM) with stiffness matrix method (SMM) for obtaining a stable solution for dispersion curves of Lamb wave propagation in non-isotropic layers. TMM developed by Thomson and Haskell experiences numerical deficiency at high frequency thickness simulations. SMM was proposed by different researchers to solve the instability issue of TMM. This study shows that stable SMM is good at high frequencies, and TMM needs to be combined with SMM to obtain stable and robust behavior over the frequency range. Numerical simulations of dispersion curves are presented for wave propagation in orthotropic unidirectional fiber composites and cross ply composites. The paper ends with conclusions and future work.
Schmidt, Moritz; Heck, Stephanie; Bosbach, Dirk; Ganschow, Steffen; Walther, Clemens; Stumpf, Thorsten
2013-01-01
We present a comprehensive study of the solid solution system Ca-2(MoO4)(2)-NaGd(MoO4)(2) on the molecular scale, by means of site-selective time resolved laser fluorescence spectroscopy (TRLFS). Eu3+ is used as a trace fluorescent probe, homogeneously substituting for Gd3+ in the solid solution crystal structure. Site-selective TRLFS of a series of polycrystalline samples covering the whole composition range of the solid solution series from 10% substitution of Ca2+ to the NaGd end-member re...
Iron salts in solid state and in frozen solutions as dosimeters for low irradiation temperatures
Martinez, T. [Facultad de Quimica UNAM, Ciudad Universitaria, D.F. Mexico (Mexico); Lartigue, J. [Facultad de Quimica UNAM, Ciudad Universitaria, D.F. Mexico (Mexico); Ramos-Bernal, S. [Instituto de Ciencias Nucleares, UNAM, A.P. 70-543 C.P.4510, Ciudad Universitaria, D.F. Mexico (Mexico); Ramos, A. [Instituto de Ciencias Nucleares, UNAM, A.P. 70-543 C.P.4510, Ciudad Universitaria, D.F. Mexico (Mexico); Mosqueira, G.F. [Direccion General de Divulgacion de la Ciencia de la UNAM, A.P. 70-487, C:P, D.F. Mexico 04510 (Mexico); Negron-Mendoza, A. [Instituto de Ciencias Nucleares, UNAM, A.P. 70-543 C.P.4510, Ciudad Universitaria, D.F. Mexico (Mexico)]. E-mail: negron@nuclecu.unam.mx
2005-12-01
The aim of this work is to study the irradiation of iron salts in solid state (heptahydrated ferrous sulfate) and in frozen acid solutions. The study is focused on finding their possible use as dosimeters for low temperature irradiations and high doses. The analysis of the samples was made by UV-visible and Moessbauer spectroscopies. The output signal was linear from 0 to 10 MGy for the solid samples, and 0-600 Gy for the frozen solutions. The obtained data is reproducible and easy to handle. For these reasons, heptahydrate iron sulfate is a suitable dosimeter for low temperature and high irradiation doses, in solid state, and in frozen solution.
Local structure in the disordered solid solution of cis- and trans-perinones
Teteruk, Jaroslav L.; Glinnemann, Juergen; Heyse, Winfried;
2016-01-01
The cis- and trans-isomers of the polycyclic aromatic compound perinone, C26H12N4O2, form a solid solution (Vat Red 14). This solid solution is isotypic to the crystal structures of cis-perinone (Pigment Red 194) and trans-perinone (Pigment Orange 34) and exhibits a combined positional....... 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...
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.
The Effect of Hydrogen on the Solid Solution Strengthening and Softening of Nickel.
1981-11-01
Afl-A108 654e ILLINOIS UNIV AT URBANA DEPT OF METALLURGY AND MININS--ETC F/6 11/6 THE EFFECT OF HYDROGEN ON THE SOLID SOLUTION STRFNSTNFNING ANfl...RESOLUTION TEST CHART NATIONAL HUR[AU OF STANDARDS 1963 A, " , ..... . .... .. i ....... .. .. . t , LEVEL THE EFFECT OF HYDROGEN ON THE SOLID SOLUTION STRENGTHENING...Availability Codes IIAvail and/or Dist Special THE EFFECT OF HYDROGEN ON THE SOLID SOLUTION STRENGTHENING AND SOFTENING OF NICKEL J. Eastman, F. Heuhaum, T
N.Natarajan
2010-10-01
Full Text Available Modeling of solute transport through fractured rock is an important component of in many disciplines especially groundwater contamination and nuclear waste disposal. Several studies have been conducted on single rock fracture using parallel plate model and recently solute and thermal transport has been numerically modeled in the sinusoidal fracture matrix coupled system. The effect of linear sorption has been studied on the same. Results suggest the high matrix porosity and matrix diffusion coefficient enhance the sorption process and reduce the matrix diffusion of solutes. The velocity of the fluid reduces with increment in fracture aperture.
Thiagamani, Senthil Muthu Kumar; Nagarajan, Rajini; Jawaid, Mohammad; Anumakonda, Varadarajulu; Siengchin, Suchart
2017-07-31
As the annual production of the solid waste generable in the form of spent coffee bean powder (SCBP) is over 6 million tons, its utilization in the generation of green energy, waste water treatment and as a filler in biocomposites is desirable. The objective of this article is to analyze the possibilities to valorize coffee bean powder as a filler in cellulose matrix. Cellulose matrix was dissolved in the relatively safer aqueous solution mixture (8% LiOH and 15% Urea) precooled to -12.5°C. To the cellulose solution (SCBP) was added in 5-25wt% and the composite films were prepared by regeneration method using ethyl alcohol as a coagulant. Some SCBP was treated with aq. 5% NaOH and the composite films were also prepared using alkali treated SCBP as a filler. The films of composites were uniform with brown in color. The cellulose/SCBP films without and with alkali treated SCBP were characterized by FTIR, XRD, optical and polarized optical microscopy, thermogravimetric analysis (TGA) and tensile tests. The maximum tensile strength of the composite films with alkali treated SCBP varied between (106-149MPa) and increased with SCBP content when compared to the composites with untreated SCBP. The thermal stability of the composite was higher at elevated temperatures when alkali treated SCBP was used. Based on the improved tensile properties and photo resistivity, the cellulose/SCBP composite films with alkali treated SCBP may be considered for packaging and wrapping of flowers and vegetables. Copyright © 2017 Elsevier Ltd. All rights reserved.
Temporal moment analysis of solute transport in a coupled fracture-skin-matrix system
V Renu; G Suresh Kumar
2014-04-01
In the present study, method of temporal moments has been used to analyse the transport characteristics of reactive solute along fracture in a coupled fracture-skin-matrix system. In order to obtain the concentration distribution within the fracture, a system of coupled partial differential equations for fracture, fractureskin and rock-matrix has been solved numerically in a pseudo two-dimensional domain using implicit finite difference method. Subsequently, lower order temporal moments of solute have been computed from the concentration distribution to analyse the transport characteristics of solutes in the fracture. This study has been done by considering an inlet boundary condition of constant continuous source in a single fracture. The effect of various fracture-skin parameters like porosity, thickness and diffusion coefficient on the transport of solutes have been studied by doing sensitivity analyses. The effect of nonlinear sorption and radioactive decay of solutes have also been analysed by carrying out simulations for different sorption intensities and decay constants. Numerical results suggested that the presence of fracture-skin significantly influences the transport characteristics of reactive solutes along the fracture.
邓远北; 胡锡炎; 张磊
2003-01-01
This paper discusses the solutions of the linear matrix equation BT X B=Don some linear manifolds.Some necessary and sufficient conditions for the existenceof the solution and the expression of the general solution are given.And also someoptimal approximation solutions are discussed.
Numerical Solution of Duffing Equation by Using an Improved Taylor Matrix Method
Berna Bülbül
2013-01-01
Full Text Available We have suggested a numerical approach, which is based on an improved Taylor matrix method, for solving Duffing differential equations. The method is based on the approximation by the truncated Taylor series about center zero. Duffing equation and conditions are transformed into the matrix equations, which corresponds to a system of nonlinear algebraic equations with the unknown coefficients, via collocation points. Combining these matrix equations and then solving the system yield the unknown coefficients of the solution function. Numerical examples are included to demonstrate the validity and the applicability of the technique. The results show the efficiency and the accuracy of the present work. Also, the method can be easily applied to engineering and science problems.
The growth and tensile deformation behavior of the silver solid solution phase with zinc
Wu, Jiaqi, E-mail: jiaqw10@uci.edu [Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697-2660 (United States); Materials and Manufacturing Technology, University of California, Irvine, CA 92697-2660 (United States); Lee, Chin C. [Department of Electrical Engineering and Computer Science, University of California, Irvine, CA 92697-2660 (United States); Materials and Manufacturing Technology, University of California, Irvine, CA 92697-2660 (United States)
2016-06-21
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.
Local Structure and Short-Range Order in a NiCoCr Solid Solution Alloy
Zhang, F. X.; Zhao, Shijun; Jin, Ke; Xue, H.; Velisa, G.; Bei, H.; Huang, R.; Ko, J. Y. P.; Pagan, D. C.; Neuefeind, J. C.; Weber, W. J.; Zhang, Yanwen
2017-05-01
Multielement solid solution alloys are intrinsically disordered on the atomic scale, and many of their advanced properties originate from the local structural characteristics. The local structure of a NiCoCr solid solution alloy is measured with x-ray or neutron total scattering and extended x-ray absorption fine structure (EXAFS) techniques. The atomic pair distribution function analysis does not exhibit an observable structural distortion. However, an EXAFS analysis suggests that the Cr atoms are favorably bonded with Ni and Co in the solid solution alloys. This short-range order (SRO) may make an important contribution to the low values of the electrical and thermal conductivities of the Cr-alloyed solid solutions. In addition, an EXAFS analysis of Ni ion irradiated samples reveals that the degree of SRO in NiCoCr alloys is enhanced after irradiation.
THE ROLE OF ELECTRON CONFIGURATION ON PROPERTIES IN DILUTE SOLID SOLUTION ALLOYS
THE ROLE OF ELECTRON CONFIGURATION ON THE PROPERTIES OF DILUTE SOLID SOLUTION ALLOYS IS DISCUSSED IN TERMS OF THE EFFECT OF DILUTE IMPURITIES ON THE RECRYSTALLIZATION CHARACTERISTICS OF PURE METALLIC ELEMENTS.
Miller, Philip J.; Tong, William G.
1980-01-01
Presents a physical inorganic experiment in which large single crystals of the alkali halides doped with divalent ion impurities are prepared easily. Demonstrates the ion pairing of inorganic ions in solid solution. (CS)
Ohsaku, T; Yamaki, D; Yamaguchi, K
2002-01-01
For studying the group theoretical classification of the solutions of the density functional theory in relativistic framework, we propose quantum electrodynamical density-matrix functional theory (QED-DMFT). QED-DMFT gives the energy as a functional of a local one-body $4\\times4$ matrix $Q(x)\\equiv -$, where $\\psi$ and $\\bar{\\psi}$ are 4-component Dirac field and its Dirac conjugate, respectively. We examine some characters of QED-DMFT. After these preparations, by using Q(x), we classify the solutions of QED-DMFT under O(3) rotation, time reversal and spatial inversion. The behavior of Q(x) under nonrelativistic and ultrarelativistic limits are also presented. Finally, we give plans for several extensions and applications of QED-DMFT.
Viability of bi-maximal solution of the Zee mass matrix
Brahmachari, B; Brahmachari, Biswajoy; Choubey, Sandhya
2002-01-01
We know $L_e-L_\\mu-L_\\tau$ symmetry gives $m^2_1= m^2_2 >> m^2_3$ pattern in Zee model. $\\Delta m^2_\\odot$ emerges from a small breaking of this symmetry. Because this symmetry is broken very weakly $\\theta_\\odot$ does not deviate much from $\\tan^2 \\theta_\\odot=1$ which is its value in the symmetric limit. This gives a mismatch with LMA solution where mixing is large but not exactly maximal. We confront this property of Zee mass matrix by phenomenologically analyzing recent results from solar and atmospheric neutrino oscillation experiments at various confidence levels. We conclude that LOW type solution is compatible with the Zee mass matrix at 99% confidence level when atmospheric neutrino deficit is explained by maximal $\
Levy, Evgeniya; Puzenko, Alexander; Kaatze, Udo; Ben Ishai, Paul; Feldman, Yuri
2012-03-21
In this, the second part of our series on the dielectric spectrum symmetrical broadening of water, we consider ionic aqueous solutions. If in Part I, dipole-dipole interaction was the dominant feature, now ion-dipole interplay is shown to be the critical element in the dipole-matrix interaction. We present the results of high-frequency dielectric measurements of different concentrations of NaCl/KCl aqueous solutions. We observed Cole-Cole broadening of the main relaxation peak of the solvent in the both electrolytes. The 3D trajectory approach (described in detail in Part I) is applied in order to highlight the differences between the dynamics and structure of solutions of salts on one hand and dipolar solutes on the other hand.
Numerical solution of point kinetic equations by matrix decomposition and T series expansions
Silva, Jeronimo J.A.; Alvim, Antonio C.M., E-mail: shaolin.jr@gmail.com, E-mail: alvim@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil); Vilhena, Marco T.M.B., E-mail: vilhena@pq.cnpq.br [Universidade Federal do Rio Grande do Sul (PROMEC/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica
2013-07-01
Recently, an analytical solution of the Point Kinetics equations free from stiffness problems has been presented. The equations, cast in matrix form are split into diagonal plus off-diagonal matrices and a series expansion of neutron density and precursor concentrations is done, producing a recurrent system which is then solved analytically. In this paper, a numerical finite differences equivalent of this decomposition plus expansion method is derived and applied to the same problems tested in the analytical case. As a result, the number of terms in the expansions needed for holding steady state is obtained, as well as results for the transient cases, with good agreement between solutions. (author)
Yu Liu
2009-01-01
Full Text Available By using diagonalizable matrix decomposition and majorization inequalities, we propose new trace bounds for the product of two real square matrices in which one is diagonalizable. These bounds improve and extend the previous results. Furthermore, we give some trace bounds for the solution of the algebraic Riccati equations, which improve some of the previous results under certain conditions. Finally, numerical examples have illustrated that our results are effective and superior.
Luminescence properties of solid solutions of borates doped with rare-earth ions
Levushkina, V. S.; Mikhailin, V. V.; Spassky, D. A.; Zadneprovski, B. I.; Tret'yakova, M. S.
2014-11-01
The structural and luminescence properties of LuxY1 - xBO3 solid solutions doped with Ce3+ or Eu+3 have been investigated. It has been found that the solid solutions crystallize in the vaterite phase with a lutetium concentration x spectra are characterized by intensive impurity emission under excitation with the synchrotron radiation in the X-ray and ultraviolet spectral ranges. It has been shown that, as the lutetium concentration x in the LuxY1 - xBO3: Ce3+ solid solutions increases, the emission intensity smoothly decreases, which is associated with a gradual shift of the Ce3+ 5 d(1) level toward the bottom of the conduction band, as well as with a decrease in the band gap. It has been established that, in the LuxY1 - xBO3: Eu3+ solid solutions with intermediate concentrations x, the efficiency of energy transfer to luminescence centers increases. This effect is explained by the limited spatial separation of electrons and holes in the solid solutions. It has been demonstrated that the calcite phase adversely affects the luminescence properties of the solid solutions.
Removal of Cl adsorbed on Mn-Ce-La solid solution catalysts during CVOC combustion.
Wang, Xingyi; Ran, Le; Dai, Yu; Lu, Yuanjiao; Dai, Qiguang
2014-07-15
Mn-Ce-La oxide-mixed catalysts prepared by the method of complexation followed by calcination at 750°C were tested in the catalytic combustion of chlorobenzene (CB) taken as a model of chlorinated aromatics. XRD analyses show that Mn and La enter CeO2 matrix with a fluorite-like structure to form solid solution. The catalysts with high ratio of Mn/Mn+Ce+La exhibit high activity for CB combustion, due to high oxygen mobility. For all Mn-Ce-La catalysts, deactivation due to Cl adsorption is observed at different temperatures, depending on composition. At 330°C or higher temperature, the removal of Cl species from the surface in the forms of Cl2 (produced through Deacon reaction) and HCl (produced through hydrolysis of Cl) occurs and the activity of catalysts for CB combustion becomes thus stable. Either the addition of water or the increase in gaseous oxygen concentration can promote the removal of Cl species, and thus to increase the activity for CB combustion. High stable activity of Mn-Ce-La catalysts can be related to the combination of good oxidation and Deacon reaction performances.
Analysis of Valence Electron Structure of RE in Solid Solution in Medium and Low Carbon Steel
朱莹光; 刘艳; 刘志林; 刘伟东
2004-01-01
According to EET theory,the valence electron structures of RE in the solid solution of austenite,pearlite and martensite were calculated.The influence of RE in solid solution on phase transformation of pearlite and recrystallization of martensite was explained by the valence electron structure data of phases.Calculating results indicate that C element is favorite to enhance the number of RE in the solid solution.RE in the solute solution shortens the incubation period of proeutectoid ferrite,increases its quantity and carbon content,decreases the quantity of pearlite and thickness of its lamellas and lamellar spacing,then the strength and hardness of pearlite are improved and granular pearlite can be obtained.RE dissolved in martensite intensifies martensite,enhances tempering stability of martensite,increases its recrystallization temperature and prolongs the holding time needed during tempering.
Zou, Qiong-Hui; Wang, Jin; Wang, Xiang-Feng; Liu, Yuan; Han, Jie; Hou, Feier; Xie, Meng-Xia
2008-01-01
A novel method for simultaneous determination of 8 sulfonamide residues (sulfathiazole, sulfapyridine, sulfadiazine, sulfamerazine, sulfamonome-thoxine, sulfachloropyridazine, sulfamethoxazole, and sulfadimethoxine) in honey samples by high-performance liquid chromatography (HPLC) has been developed on the basis of precolumn derivatization with 9-fluorenylmethyl-chloroformate (FMOC-Cl). Sulfonamide residues in honey samples were extracted and purified by matrix solid-phase dispersion with C18 as the solid support. The residues were derivatized by FMOC-CI, and the FMOC-sulfonamide derivatives were further purified by solid-phase extraction with silica gel as the solid support prior to HPLC analysis. The average recoveries for most sulfonamide compounds at different spiking levels (from 10 to 250 microg/kg) were > 70% with relative standard deviations < 16%, and their limits of detection were 4.0 microg/kg. The established analytical method has high sensitivity and repeatability and can be applicable for determining the sulfonamide residues in various honey matrixes.
Rolland, A.; Aufray, B.
1985-10-01
This paper deals with a comparative study of surface segragation of Pb and Ni respectively from Ag(Pb)(111) and Ag(Ni)(111) solid solutions. A high level of segregation of the solute is observed for both systems characterized by very low solute solubility. However, the superficial composition strongly depends on the relative surface tensions of the pure elements: the solute atoms are strictly on superficial sites when γ solute is smaller than γ solvent; in contrast uppermost layer consists purely of solvent when γ solute is greater than γ solvent. Two schematic distributions in close proximity to the surface are proposed in the last case.
Study of complex matrix effect on solid phase microextraction for biological sample analysis.
Jiang, Ruifen; Xu, Jianqiao; Zhu, Fang; Luan, Tiangang; Zeng, Feng; Shen, Yong; Ouyang, Gangfeng
2015-09-11
Solid phase microextraction (SPME) has become a useful tool for in vivo monitoring the behavior of environmental organic pollutants in biological species due to its simplicity, relatively non-invasive, and cost-effective manner. However, the complex matrices in biological samples could significantly influence the extraction kinetic, and bias the quantification result. In this study, we investigated the effect of complex matrix on the extraction kinetic of SPME for biological sample analysis. Two sample matrices, phosphate-buffered saline (PBS) with bovine serum albumin (BSA) and agarose gel with BSA were used to simulate the biological fluid and tissue. Results showed that the addition of BSA significantly enhanced the mass transfer of organic compounds onto SPME fiber in both PBS buffer and gel sample. Enhancement factors ranging from 1.3 to 27, and 2.0 to 80 were found for all selected polyaromatic hydrocarbons (PAHs) in PBS buffer and agarose gel with BSA concentration of 0.1-5%, respectively. Then, an improved theoretical model was applied to quantify the observed enhancement effect, and the result showed that the predicted sampling time constant agreed well with the experimental one in complex matrix. Furthermore, a simplified equation was proposed for the real biological sample analysis.
Evaluation of Solid Modeling Software for Finite Element Analysis of Woven Ceramic Matrix Composites
Nemeth, Noel N.; Mital, Subodh; Lang, Jerry
2010-01-01
Three computer programs, used for the purpose of generating 3-D finite element models of the Repeating Unit Cell (RUC) of a textile, were examined for suitability to model woven Ceramic Matrix Composites (CMCs). The programs evaluated were the open-source available TexGen, the commercially available WiseTex, and the proprietary Composite Material Evaluator (COMATE). A five-harness-satin (5HS) weave for a melt-infiltrated (MI) silicon carbide matrix and silicon carbide fiber was selected as an example problem and the programs were tested for their ability to generate a finite element model of the RUC. The programs were also evaluated for ease-of-use and capability, particularly for the capability to introduce various defect types such as porosity, ply shifting, and nesting of a laminate. Overall, it was found that TexGen and WiseTex were useful for generating solid models of the tow geometry; however, there was a lack of consistency in generating well-conditioned finite element meshes of the tows and matrix. TexGen and WiseTex were both capable of allowing collective and individual shifting of tows within a ply and WiseTex also had a ply nesting capability. TexGen and WiseTex were sufficiently userfriendly and both included a Graphical User Interface (GUI). COMATE was satisfactory in generating a 5HS finite element mesh of an idealized weave geometry but COMATE lacked a GUI and was limited to only 5HS and 8HS weaves compared to the larger amount of weave selections available with TexGen and WiseTex.
Naccarato, Attilio; Pawliszyn, Janusz
2016-09-01
This work proposes the novel PDMS/DVB/PDMS fiber as a greener strategy for analysis by direct immersion solid phase microextraction (SPME) in vegetables. SPME is an established sample preparation approach that has not yet been adequately explored for food analysis in direct immersion mode due to the limitations of the available commercial coatings. The robustness and endurance of this new coating were investigated by direct immersion extractions in raw blended vegetables without any further sample preparation steps. The PDMS/DVB/PDMS coating exhibited superior features related to the capability of the external PDMS layer to protect the commercial coating, and showed improvements in terms of extraction capability and in the cleanability of the coating surface. In addition to having contributed to the recognition of the superior features of this new fiber concept before commercialization, the outcomes of this work serve to confirm advancements in the matrix compatibility of the PDMS-modified fiber, and open new prospects for the development of greener high-throughput analytical methods in food analysis using solid phase microextraction in the near future.
Quasi-solid-state dye-sensitized solar cells with cyanoacrylate as electrolyte matrix
Lu, Shengli [Linz Institute for Organic Solar Cells (LIOS), Johannes Kepler University Linz, Altenbergerstr. 69, A-4040 Linz (Austria); Institute for Organic Solar Energy Opto-Electronic Materials, College of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310012 (China); Koeppe, Robert; Guenes, Serap; Sariciftci, Niyazi Serdar [Linz Institute for Organic Solar Cells (LIOS), Johannes Kepler University Linz, Altenbergerstr. 69, A-4040 Linz (Austria)
2007-07-23
A quasi-solid-state dye-sensitized solar cells (DSSCs) employing a commercial glue (''SuperGlue {sup registered} '') as electrolyte matrix was fabricated. The cyano groups of the cyanoacrylate can form a supramolecular complex with tetrapropylammonium cations. This immobilizes the cations and therefore might lead to a favored anionic charge transport necessary for a good performance of the iodide/triiodide electrolytic conductor. Obtaining energy conversion efficiencies of more than 4% under 100 mW/cm{sup 2} of simulated A.M. 1.5 illumination, the cyanoacrylate quasi-solid-state electrolyte is an ordinary and low-cost compound which has fast drying property and offers significant advantages in the fabrication of solar cells and modules as it is in itself is a very good laminating agent. The influences of different porous layer thicknesses of titanium oxide and various kinds of cations on DSSC performance and long-term stability are presented. (author)
Fabrication of metal matrix composite by semi-solid powder processing
Wu, Yufeng [Iowa State Univ., Ames, IA (United States)
2011-01-01
Various metal matrix composites (MMCs) are widely used in the automotive, aerospace and electrical industries due to their capability and flexibility in improving the mechanical, thermal and electrical properties of a component. However, current manufacturing technologies may suffer from insufficient process stability and reliability and inadequate economic efficiency and may not be able to satisfy the increasing demands placed on MMCs. Semi-solid powder processing (SPP), a technology that combines traditional powder metallurgy and semi-solid forming methods, has potential to produce MMCs with low cost and high efficiency. In this work, the analytical study and experimental investigation of SPP on the fabrication of MMCs were explored. An analytical model was developed to understand the deformation mechanism of the powder compact in the semi-solid state. The densification behavior of the Al6061 and SiC powder mixtures was investigated with different liquid fractions and SiC volume fractions. The limits of SPP were analyzed in terms of reinforcement phase loading and its impact on the composite microstructure. To explore adoption of new materials, carbon nanotube (CNT) was investigated as a reinforcing material in aluminum matrix using SPP. The process was successfully modeled for the mono-phase powder (Al6061) compaction and the density and density distribution were predicted. The deformation mechanism at low and high liquid fractions was discussed. In addition, the compaction behavior of the ceramic-metal powder mixture was understood, and the SiC loading limit was identified by parametric study. For the fabrication of CNT reinforced Al6061 composite, the mechanical alloying of Al6061-CNT powders was first investigated. A mathematical model was developed to predict the CNT length change during the mechanical alloying process. The effects of mechanical alloying time and processing temperature during SPP were studied on the mechanical, microstructural and
Na, Y. W.; Park, C. E.; Lee, S. Y. [KOPEC, Daejeon (Korea, Republic of)
2009-10-15
As a part of the Ministry of Knowledge Economy (MKE) project, 'Development of safety analysis codes for nuclear power plants', KOPEC has been developing the hydraulic solver code package applicable to the safety analyses of nuclear power plants (NPP's). The matrices of the hydraulic solver are usually sparse and may be asymmetric. In the earlier stage of this project, typical direct matrix solver packages MA48 and MA28 had been tested as matrix solver for the hydraulic solver code, SPACE. The selection was based on the reasonably reliable performance experience from their former version MA18 in RELAP computer code. In the later stage of this project, the iterative methodologies have been being tested in the SPACE code. Among a few candidate iterative solution methodologies tested so far, the biconjugate gradient stabilization methodology (BICGSTAB) has shown the best performance in the applicability test and in the application to the SPACE code. Regardless of all the merits of using the direct solver packages, there are some other aspects of tackling the iterative solution methodologies. The algorithm is much simpler and easier to handle. The potential problems related to the robustness of the iterative solution methodologies have been resolved by applying pre-conditioning methods adjusted and modified as appropriate to the application in the SPACE code. The application strategy of conjugate gradient method was introduced in detail by Schewchuk, Golub and Saad in the middle of 1990's. The application of his methodology to nuclear engineering in Korea started about the same time and is still going on and there are quite a few examples of application to neutronics. Besides, Yang introduced a conjugate gradient method programmed in C++ language. The purpose of this study is to assess the performance and behavior of the iterative solution methodology compared to those of the direct solution methodology still being preferred due to its robustness and
Effect of current density on distribution coefficient of solute at solid-liquid interface
常国威; 王自东; 吴春京; 胡汉起
2003-01-01
When current passes through the solid-liquid interface, the growth rate of crystal, solid-liquid interfaceenergy and radius of curvature at dendritic tip will change. Based on this fact, the theoretical relation between thedistribution of solute at solid-liquid interface and current density was established, and the effect of current on thedistribution coefficient of solute through effecting the rate of crystal growth, the solid-liquid interface energy and theradius of curvature at the dendritic tip was discussed. The results show that as the current density increases, thedistribution coefficient of solute tends to rise in a whole, and when the former is larger than about 400 A/cm2 , thelatter varies significantly.
Theoretical and Experimental Study of LiBH4-LiCl Solid Solution
Torben R. Jensen
2012-03-01
Full Text Available Anion substitution is at present one of the pathways to destabilize metal borohydrides for solid state hydrogen storage. In this work, a solid solution of LiBH4 and LiCl is studied by density functional theory (DFT calculations, thermodynamic modeling, X-ray diffraction, and infrared spectroscopy. It is shown that Cl substitution has minor effects on thermodynamic stability of either the orthorhombic or the hexagonal phase of LiBH4. The transformation into the orthorhombic phase in LiBH4 shortly after annealing with LiCl is for the first time followed by infrared measurements. Our findings are in a good agreement with an experimental study of the LiBH4-LiCl solid solution structure and dynamics. This demonstrates the validity of the adopted combined theoretical (DFT calculations and experimental (vibrational spectroscopy approach, to investigate the solid solution formation of complex hydrides.
Levy, Evgeniya; Puzenko, Alexander; Kaatze, Udo; Ishai, Paul Ben; Feldman, Yuri
2012-03-21
Whenever water interacts with another dipolar entity, a broadening of its dielectric relaxation occurs. Often this broadening can be described by the Cole-Cole (CC) spectral function. A new phenomenological approach has been recently presented [A. Puzenko, P. Ben Ishai, and Y. Feldman, Phys. Rev. Lett. 105, 037601 (2010)] that illustrates a physical mechanism of the dipole-matrix interaction underlying the CC behavior in complex systems. By considering the relaxation amplitude Δε, the relaxation time τ, and the broadening parameter α, one can construct a set of 3D trajectories, representing the dynamic behavior of different systems under diverse conditions. Our hypothesis is that these trajectories will contribute to a deeper understanding of the dielectric properties of complex systems. The paper demonstrates how the model describes the state of water in aqueous solutions of non-ionic solutes. For this purpose complex dielectric spectra for aqueous solutions of D-glucose and D-fructose are analyzed.
Narayanan, Amal; Chandel, Shubham; Ghosh, Nirmalya; De, Priyadarsi
2015-09-15
Probing volume phase transition behavior of superdiluted polymer solutions both micro- and macroscopically still persists as an outstanding challenge. In this regard, we have explored 4 × 4 spectral Mueller matrix measurement and its inverse analysis for excavating the microarchitectural facts about stimuli responsiveness of "smart" polymers. Phase separation behavior of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) and pH responsive poly(N,N-(dimethylamino)ethyl methacrylate) (PDMAEMA) and their copolymers were analyzed in terms of Mueller matrix derived polarization parameters, namely, depolarization (Δ), diattenuation (d), and linear retardance (δ). The Δ, d, and δ parameters provided useful information on both macro- and microstructural alterations during the phase separation. Additionally, the two step action ((i) breakage of polymer-water hydrogen bonding and (ii) polymer-polymer aggregation) at the molecular microenvironment during the cloud point generation was successfully probed via these parameters. It is demonstrated that, in comparison to the present techniques available for assessing the hydrophobic-hydrophilic switch over of simple stimuli-responsive polymers, Mueller matrix polarimetry offers an important advantage requiring a few hundred times dilute polymer solution (0.01 mg/mL, 1.1-1.4 μM) at a low-volume format.
Closed-form Solutions to the Matrix Equation AX-EXF=BY with F in Companion Form
Bin Zhou; Guang-Ren Duan
2009-01-01
A closed-form solution to the linear matrix equation AX-EXF=BY with X and Y unknown and matrix F being in a companion form is proposed, and two equivalent forms of this solution are also presented. The results provide great convenience to the computation and analysis of the solutions to this class of equations, and can perform important functions in many analysis and design problems in descriptor system theory. The results proposed here axe parallel to and more general than our early work about the linear matrix equation AX-XF=BY.
An-ping Liao; Yuan Lei; Xi-yan Hu
2007-01-01
An efficient method based on the projection theorem,the generalized singular value decomposition and the canonical correlation decomposition is presented to find the least-squares solution with the minimumnorm for the matrix equation ATXB+BTXTA=D.Analytical solution to the matrix equation is also derived.Furthermore,we apply this result to determine the least-squares symmetric and sub-antisymmetrie solution of the matrix equation CTXC=D with minimum-norm.Finally,some numerical results are reported to support the theories established in this paper.
Study on solid solution and aging process of AZ91D magnesium alloy with cerium
GUO
2010-01-01
The influence of Ce on solid solution and aging process of AZ91D magnesium alloy was analyzed.The results showed that the decomposition of β-Mg17Al12 phase in AZ91D magnesium alloy at 420 ℃ could be completed within 12 h,while this process in the Ce-containing alloy required more time.In subsequent aging process at 175 ℃,Ce obviously delayed the aging process of AZglD.It was inferred that the influence of Ce on process of solid solution and aging was relative to the Ce that existed in β-Mg17Al12 phase of original structure in the form of solid solution,and the interaction of the Ce and Al was an important factor to get process of solution and aging slowly.
Asmus, Lutz R; Gurny, Robert; Möller, Michael
2011-02-01
The purpose of this study was to investigate the polyester hexylsubstituted poly(lactide) (hexPLA) as a possible solvent for lipophilic substances and excipient for pharmaceutical formulations. HexPLA is a biodegradable and semi-solid polymer, which allows the incorporation of active substances by simple mixing and local or systemic application to the patient through injection. The solvent behavior of hexPLA was investigated by adding the lipophilic dye Sudan III to the polymer matrix and optical monitoring of the dissolution process over time by microscopy. As a drug, the antipsychotic compound haloperidol was analyzed for its solubility in hexPLA of different molecular weights by preparing saturated solutions, and measuring the amount of incorporated drug with UV spectroscopy. The influence of the rate of solubilized to suspended drug on the burst release behavior of haloperidol from hexPLA-formulations was investigated in release tests. It is demonstrated that hexPLA dissolves both lipophilic substances, Sudan III and Haloperidol. In the molecular weight range between 2,000 g/mol and 10,000 g/mol, a lower molecular weight hexPLA resulted in a higher incorporation capacity for haloperidol. By changing from a suspension formulation of haloperidol to a solution formulation, the initial burst release established for classical PLA and PLGA systems could be minimized. HexPLA is shown to be a potent solvent and excipient for lipophilic drugs, allowing the initial burst of drug release to be modified and controlled.
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.
Colloidal quantum dot solids for solution-processed solar cells
Yuan, Mingjian; Liu, Mengxia; Sargent, Edward H.
2016-03-01
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 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.
Lapinski, Leszek; Nowak, Maciej J.; Rostkowska, Hanna
2017-03-01
UV-induced transformations have been studied for 4(3H)-pyrimidinone monomers isolated in low-temperature Ar, Ne, n-D2, and n-H2 matrices. The observed photochemical behavior of the compound drastically depended on the solid matrix environment. For 4(3H)-pyrimidinone isolated in solid Ar, the UV-induced phototautomeric transformation was clearly the dominating process, leading to a nearly quantitative conversion of the oxo reactant into the hydroxy product. For solid Ne environment, the oxo → hydroxy transformation was still the major photoprocess, but yielding less of the hydroxy product (ca. 64% of the yield in solid Ar). For 4(3H)-pyrimidinone isolated in solid n-H2, the oxo → hydroxy phototautomeric conversion did not occur (or occurred at a very tiny scale). Also for deuterated 4(3D)-pyrimidinone isolated in solid hydrogen, the analogous oxo → deuteroxy phototransformation was not observed. Finally, for the compound trapped in solid n-D2, the oxo → hydroxy phototautomerism clearly occurred, but the yield of the hydroxy tautomer was small (ca. 18% of the yield in solid Ar). Apart from hydrogen-atom-transfer processes, two other phototransformations: generation of open-ring conjugated ketene and valence Dewar isomer were observed for the compound isolated in Ar, Ne, n-D2, and n-H2 matrices.
Radiolytic formation of Ag clusters in aqueous polyvinyl alcohol solution and hydrogel matrix
Kumar, Manmohan [Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)]. E-mail: manmoku@magnum.barc.ernet.in; Varshney, Lalit [Radiation Technology Development Section, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Francis, Sanju [Radiation Technology Development Section, Bhabha Atomic Research Centre, Mumbai 400 085 (India)
2005-05-01
Ag{sup +} ions, in aqueous polyvinyl alcohol (PVA) solution and in PVA hydrogel matrix have been gamma radiolytically reduced to produce Ag clusters. UV-visible absorption spectral characteristics of Ag clusters obtained under different gamma dose, Ag{sup +} concentration, PVA concentration and crosslinking density of the gel used have been studied. The effect of Ag{sup +} ions on the radiation crosslinking of the PVA chains, have also been investigated by viscosity measurements. The radiation-induced Ag{sup +} ion reduction was followed by crosslinking of the PVA chains. PVA was found to be a very efficient stabilizer to prevent aggregation of Ag clusters. The clusters produced in the hydrogel matrix were expected to be smaller than the pore size ({approx}2-20 nm) of the gels used in the study. These Ag clusters were unable to reduce methyl viologen (MV{sup 2+}) chloride and were stable in air.
Radiolytic formation of Ag clusters in aqueous polyvinyl alcohol solution and hydrogel matrix
Kumar, Manmohan; Varshney, Lalit; Francis, Sanju
2005-05-01
Ag+ ions, in aqueous polyvinyl alcohol (PVA) solution and in PVA hydrogel matrix have been gamma radiolytically reduced to produce Ag clusters. UV-visible absorption spectral characteristics of Ag clusters obtained under different gamma dose, Ag+ concentration, PVA concentration and crosslinking density of the gel used have been studied. The effect of Ag+ ions on the radiation crosslinking of the PVA chains, have also been investigated by viscosity measurements. The radiation-induced Ag+ ion reduction was followed by crosslinking of the PVA chains. PVA was found to be a very efficient stabilizer to prevent aggregation of Ag clusters. The clusters produced in the hydrogel matrix were expected to be smaller than the pore size (∼2-20 nm) of the gels used in the study. These Ag clusters were unable to reduce methyl viologen (MV2+) chloride and were stable in air.
Matrix method for the solution of RF field perturbations due to local frequency shifts
SUN Zhi-Rui; PENG Jun; FU Shi-Nian
2009-01-01
To tune the accelerating field to the design value in a periodical radio frequency accelerating structure, Slater's perturbation theorem is commonly used. This theorem solves a second-order differential equation to obtain the electrical field variation due to a local frequency shift. The solution becomes very difficult for a complex distribution of the local frequency shifts. Noticing the similarity between the field perturbation equation and the equation describing the transverse motion of a particle in a quadrupole channel, we propose in this paper a new method in which the transfer matrix method is applied to the field calculation instead of directly solving the differential equation. The advantage of the matrix method is illustrated in examples.
矩阵方程AXB+CYD=E的Toeplitz矩阵解%Toeplitz Matrix Solutions of Matrix Equation AXB+CYD=E
孙庆娟; 郭文彬; 王柄中
2012-01-01
The expressions of the Toeplitz matrix solution and symmetric Toeplitz matrix solution of the matrix equation AXB + CYD = E were given in this paper by using the Kronecker product of matrices, matrices straight operator and Moore-Penrose generalized inverse. And also the expressions of the least squares solution was given.%利用矩阵的Kronecker积、矩阵的拉直算子和Moore-Penrose广义逆的有关知识,给出了矩阵方程AXB+CYD=E的Toeplitz矩阵解和对称Toeplitz矩阵解的表达式,并给出了其最小二乘解的一般形式.
Pootawang, Panuphong; Kim, Seong Cheol; Kim, Jung Wan; Lee, Sang Yul
2013-01-01
The environmental concern pays much attention to the recent cause of the global warming effect. The reduction of the chemical uses is one of many ways to avoid this crucial problem. Herein, the green process for silver nanometallic particle formation and incorporation in gelatin are proposed. By using a novel discharge process in solution named solution plasma, the silver nanometallic particle formation and its incorporation in gelatin could be accomplished in one-batch reactor during discharge by using silver nitrate (AgNO3) solution as the precursor and controlling systematical parameters. The three-dimensional scaffolds of gelatin/silver biocomposite were fabricated using lyophilizer and the water-soluble property of gelatin was improved by irradiation of ultraviolet ray. The well dispersed silver nanoparticles with the mean particle size 10-20 nm in the good texture of gelatin matrix were obtained. The density of micropore in gelatin/silver scaffold was proportional to the gelatin concentration. In addition, thermal stability of prepared samples had no change comparing with pure gelatin, indicating that the incorporation of silver nanoparticles in gelatin matrix did not affect to the nature of gelatin.
Electrochemical Behavior of Al-B4C Metal Matrix Composites in NaCl Solution
Yu-Mei Han
2015-09-01
Full Text Available Aluminum based metal matrix composites (MMCs have received considerable attention in the automotive, aerospace and nuclear industries. One of the main challenges using Al-based MMCs is the influence of the reinforcement particles on the corrosion resistance. In the present study, the corrosion behavior of Al-B4C MMCs in a 3.5 wt.% NaCl solution were investigated using potentiodynamic polarization (PDP and electrochemical impedance spectroscopy (EIS techniques. Results indicated that the corrosion resistance of the composites decreased when increasing the B4C volume fraction. Al-B4C composite was susceptible to pitting corrosion and two types of pits were observed on the composite surface. The corrosion mechanism of the composite in the NaCl solution was primarily controlled by oxygen diffusion in the solution. In addition, the galvanic couples that formed between Al matrix and B4C particles could also be responsible for the lower corrosion resistance of the composites.
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.
Surface Defects Enhanced Visible Light Photocatalytic H2 Production for Zn-Cd-S Solid Solution.
Zhang, Xiaoyan; Zhao, Zhao; Zhang, Wanwan; Zhang, Guoqiang; Qu, Dan; Miao, Xiang; Sun, Shaorui; Sun, Zaicheng
2016-02-10
In order to investigate the defect effect on photocatalytic performance of the visible light photocatalyst, Zn-Cd-S solid solution with surface defects is prepared in the hydrazine hydrate. X-ray photoelectron spectra and photoluminescence results confirm the existence of defects, such as sulfur vacancies, interstitial metal, and Zn and Cd in the low valence state on the top surface of solid solutions. The surface defects can be effectively removed by treating with sulfur vapor. The solid solution with surface defect exhibits a narrower band gap, wider light absorption range, and better photocatalytic perfomance. The optimized solid solution with defects exhibits 571 μmol h(-1) for 50 mg photocatalyst without loading Pt as cocatalyst under visible light irradiation, which is fourfold better than that of sulfur vapor treated samples. The wavelength dependence of photocatalytic activity discloses that the enhancement happens at each wavelength within the whole absorption range. The theoretical calculation shows that the surface defects induce the conduction band minimum and valence band maximum shift downward and upward, respectively. This constructs a type I junction between bulk and surface of solid solution, which promotes the migration of photogenerated charges toward the surface of nanostructure and leads to enhanced photocatalytic activity. Thus a new method to construct highly efficient visible light photocatalysts is opened.
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} (0
Resin Matrix/Fiber Reinforced Composite Material, Ⅱ: Method of Solution and Computer Code
Li Chensha(李辰砂); Jiao Caishan; Liu Ying; Wang Zhengping; Wang Hongjie; Cao Maosheng
2003-01-01
According to a mathematical model which describes the curing process of composites constructed from continuous fiber-reinforced, thermosetting resin matrix prepreg materials, and the consolidation of the composites, the solution method to the model is made and a computer code is developed, which for flat-plate composites cured by a specified cure cycle, provides the variation of temperature distribution, the cure reaction process in the resin, the resin flow and fibers stress inside the composite, the void variation and the residual stress distribution.
无
2002-01-01
Polarimetric scattering from inhomogeneous random media of non-spherical scatterers under a pulse incidence is studied. The time-dependent Mueller matrix solution of vector radiative transfer for layering random media is derived. Co-polarized and cross-polarized bistatic and back-scattering are numerically simulated. The shape and intensity of polarized echoes well depict the inhomogeneous fraction profile of random scatterers. Its functional dependence upon the fraction profile, layering thickness, and other parameters are discussed. This technique is applicable to reconstruction of inhomogeneous fraction profile and inversion of the media thickness.
Bottom-up and top-down solid-state NMR approaches for bacterial biofilm matrix composition
Cegelski, Lynette
2015-04-01
The genomics and proteomics revolutions have been enormously successful in providing crucial "parts lists" for biological systems. Yet, formidable challenges exist in generating complete descriptions of how the parts function and assemble into macromolecular complexes and whole-cell assemblies. Bacterial biofilms are complex multicellular bacterial communities protected by a slime-like extracellular matrix that confers protection to environmental stress and enhances resistance to antibiotics and host defenses. As a non-crystalline, insoluble, heterogeneous assembly, the biofilm extracellular matrix poses a challenge to compositional analysis by conventional methods. In this perspective, bottom-up and top-down solid-state NMR approaches are described for defining chemical composition in complex macrosystems. The "sum-of-the-parts" bottom-up approach was introduced to examine the amyloid-integrated biofilms formed by Escherichia coli and permitted the first determination of the composition of the intact extracellular matrix from a bacterial biofilm. An alternative top-down approach was developed to define composition in Vibrio cholerae biofilms and relied on an extensive panel of NMR measurements to tease out specific carbon pools from a single sample of the intact extracellular matrix. These two approaches are widely applicable to other heterogeneous assemblies. For bacterial biofilms, quantitative parameters of matrix composition are needed to understand how biofilms are assembled, to improve the development of biofilm inhibitors, and to dissect inhibitor modes of action. Solid-state NMR approaches will also be invaluable in obtaining parameters of matrix architecture.
Polymer-nanocomposite brush-like architectures as an all-solid electrolyte matrix.
Gowneni, Soujanya; Ramanjaneyulu, Kota; Basak, Pratyay
2014-11-25
Herein, we report on polymer-nanocomposites with brush-like architectures and evaluate their feasibility as an all-solid electrolyte matrix supporting Li(+)-ion conduction. Showcased as a first example in the domain of electrolyte research, the study probes several key factors, such as (i) core morphology, (ii) surface modifiers/functionality, (iii) grafting length, and (iv) density of the brushes, and determines their role on the overall electrochemical properties of these nanostructured organic-inorganic hybrids. Nanostructured titania was synthesized via wet-chemical approaches using either controlled hydrolysis or hydrothermal methods. Exercising suitable control on reaction parameters led to well-defined morphologies/phases, such as nanoparticles, nanospindles, nanourchins, nanorods or nanotubes, in either anatase, rutile or mixed forms. Covalent anchoring on titania nanostructures was achieved using dopamine, gallic acid and glycerol as small organic moieties. A one-pot process of priming the available surface functional groups postmodification with isocyanate chemistry was followed by grafting polyethylene glycol monomethyl ethers of desired chain lengths. Finally, complexation with lithium salt yielded electrolyte compositions where the ethylene oxide (EO) fractions aid in ion-solvation with ease. The synthesized materials were characterized in detail employing XRD, TEM, DRS-UV, FTIR, micro-Raman, TG-DTA and DSC at each stage to confirm the products and ascertain the physicochemical properties. Comprehensive evaluation using temperature-step electrochemical impedance spectroscopy (EIS) of these brush-like nanocomposites provided crucial leads toward establishing a plausible physical model for the system and understanding the mechanism of ion transport in these all-solid matrices. The preliminary results on ionic conductivity (σ) obtained for some of the compositions are estimated to be within the range of ∼10(-4) to 10(-5) S cm(-1) in the temperature
Ab initio identified design principles of solid-solution strengthening in Al
Duancheng Ma, Martin Friák, Johann von Pezold, Dierk Raabe and Jörg Neugebauer
2013-01-01
Full Text Available 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.
Montoya-Martinez, Jair; Artes-Rodriguez, Antonio; Pontil, Massimiliano;
2014-01-01
We consider the estimation of the Brain Electrical Sources (BES) matrix from noisy electroencephalographic (EEG) measurements, commonly named as the EEG inverse problem. We propose a new method to induce neurophysiological meaningful solutions, which takes into account the smoothness, structured...... sparsity, and low rank of the BES matrix. The method is based on the factorization of the BES matrix as a product of a sparse coding matrix and a dense latent source matrix. The structured sparse-low-rank structure is enforced by minimizing a regularized functional that includes the ℓ21-norm of the coding...... matrix and the squared Frobenius norm of the latent source matrix. We develop an alternating optimization algorithm to solve the resulting nonsmooth-nonconvex minimization problem. We analyze the convergence of the optimization procedure, and we compare, under different synthetic scenarios...
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.
Elastic and viscoelastic solutions to rotating functionally graded hollow and solid cylinders
无
2008-01-01
Analytical solutions to rotating functionally graded hollow and solid long cylinders are developed. Young's modulus and material density of the cylinder are as* sumed to vary exponentially in the radial direction, and Poisson's ratio is assumed to be constant. A unified governing equation is derived from the equilibrium equations, compat-ibility equation, deformation theory of elasticity and the stress-strain relationship. The governing second-order differential equation is solved in terms of a hypergeometric func-tion for the elastic deformation of rotating functionally graded cylinders. Dependence of stresses in the cylinder on the inhomogeneous parameters, geometry and boundary conditions is examined and discussed. The proposed solution is validated by comparing the results for rotating functionally graded hollow and solid cylinders with the results for rotating homogeneous isotropic cylinders. In addition, a viscoelastic solution to the rotating viscoelastic cylinder is presented, and dependence of stresses in hollow and solid cylinders on the time parameter is examined.
Semi solid matrix formulations of meloxicam and tenoxicam: an in vitro and in vivo evaluation.
Alladi, Saritha; Shastri, Nalini R
2015-01-01
The objective of this study was to improve the dissolution and subsequently the therapeutic efficacy of poorly water soluble BCS class-II drugs meloxicam and tenoxicam, by lipid semi solid matrix (SSM) systems filled in hard gelatin capsules by liquid fill technology. The present research involved preparation of SSM formulations using Gelucire 44/14 as a carrier due to its self emulsifying, wetting and hydrophilic properties. The SSM capsules were characterized by assay, in vitro dissolution studies, moisture uptake, FTIR and DSC. The optimized formulations were also evaluated for their in vivo anti inflammatory activity in rat model. Six to ten fold enhancement in vitro drug release, in both acidic and basic media, was obtained with formulations containing drug to carrier in 1:6 ratio. The absence of drug peak in DSC scans indicated complete dissolution of the drug in carrier, while IR revealed no chemical interaction of pure drug and Gelucire 44/14. The optimized SSM formulations of meloxicam and tenoxicam showed a rapid decrease in paw edema with a significant increase in anti-inflammatory activity. The SSM formulations were successful in providing rapid release of drugs with improved dissolution and in vivo anti-inflammatory activity by liquid fill technology in hard gelatin capsules.
Xiaocui Duan
2014-01-01
Full Text Available The study based on the chemiluminescence (CL reaction of potassium ferricyanide and luminol in sodium hydroxide medium, enrofloxacin (ENRO could dramatically enhance CL intensities and incorporated with matrix solid-phase dispersion (MSPD technique (Florisil used as dispersant, dichloromethane eluted the target compounds. A simple flow injection chemiluminescence (FL-CL method with MSPD technique for determination of ENRO in eggs was described. Under optimal conditions, the CL intensities were linearly related to ENRO concentration ranging from 4.0×10-8 g.L−1 to 5.0×10-5 g.L−1, with a correlation coefficient of 0.9989 and detection limit of 5.0×10-9 g.L−1. The relative standard deviation was 3.6% at an ENRO concentration of 2.0×10-6 g.L−1. Our testing technique can help ensure food safety, and thus, protect public health.
Effect of Preparation Method on Surface Area and Crystalline Form of CeO2-ZrO2 Solid Solution
王晓红; 郭耘; 卢冠忠; 郭杨龙; 王筠松; 张志刚; 刘晓晖
2004-01-01
The CeO2-ZrO2 solid solutions were prepared by a reverse microemulsion method. The effect of preparation parameters on the surface area and crystalline form of the solid solutions were studied by the BET surface area and XRD analysis. The studies indicate that the separation of the microemulsion phase during the preparation procedure can decrease the specific surface area of sample, adding hydrogen peroxide in the matrix solution can increase the specific surface area and stability of sample. The surface area of sample calcined at 550 ℃ for 5 h is 149 m2·g-1, and that calcined at 900 ℃ for 6 h is 88 m2·g-1.The sample with tetragonal symmetry Ce0.5Zr0.5O2 phase has a higher stability.
Bochenek, Dariusz; Zachariasz, Radosław; Niemiec, Przemysław; Ilczuk, Jan; Bartkowska, Joanna; Brzezińska, Dagmara
2016-10-01
In the presented work, a ferroelectromagnetic solid solutions based on PZT and ferrite powders have been obtained. The main aim of combination of ferroelectric and magnetic powders was to obtain material showing both electric and magnetic properties. Ferroelectric ceramic powder (in amount of 90%) was based on the doped PZT type solid solution while magnetic component was nickel-zinc ferrite Ni1-xZnxFe2O4 (in amount of 10%). The synthesis of components of ferroelectromagnetic solid solutions was performed using the solid phase sintering. Final densification of synthesized powder has been done using free sintering. The aim of the work was to obtain and examine in the first multicomponent PZT type ceramics admixed with chromium with the following chemical composition Pb0.94Sr0.06(Zr0.46Ti0.54)O3+0.25 at% Cr2O3 and next ferroelectromagnetic solid solution based on a PZT type ferroelectric powder (Pb0.94Sr0.06(Zr0.46Ti0.54)O3+0.25 at% Cr2O3) and nickel-zinc ferrite (Ni0.64Zn0.36Fe2O4), from the point of view of their mechanical and electric properties, such as: electric permittivity, ε; dielectric loss, tanδ; mechanical losses, Q-1; and Young modulus, E.
Explicit thin-lens solution for an arbitrary four by four uncoupled beam transfer matrix
Balandin, V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Orlov, S. [Moscow State Univ. (Russian Federation). Faculty of Computational Mathematics and Cybernetics
2011-10-15
In the design of beam transport lines one often meets the problem of constructing a quadrupole lens system that will produce desired transfer matrices in both the horizontal and vertical planes. Nowadays this problem is typically approached with the help of computer routines, but searching for the numerical solution one has to remember that it is not proven yet that an arbitrary four by four uncoupled beam transfer matrix can be represented by using a finite number of drifts and quadrupoles (representation problem) and the answer to this questions is not known not only for more or less realistic quadrupole field models but also for the both most commonly used approximations of quadrupole focusing, namely thick and thin quadrupole lenses. In this paper we make a step forward in resolving the representation problem and, by giving an explicit solution, we prove that an arbitrary four by four uncoupled beam transfer matrix actually can be obtained as a product of a finite number of thin-lenses and drifts. (orig.)
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.
Researches on the Structure and Properties of Mullite Solid Solution Made from Industrial Waste
RUAN Yu-Zhong; YU Yan; WU Ren-Ping
2006-01-01
The waste slag from aluminum profile factory and silicon fine powder from ferroalloy factory were utilized as the main raw materials to synthesize mullite solid solution Al4+2xSi2-xO10-x/2, whose defect formation mechanism, crystalline phase composition, crystal cell parameters, microstructures and morphologies were characterized in detail by XRD and SEM. The results show that because of the ultrafine particle size of the materials, the content of mullite solid solution synthesized by this method is higher than that by regular method.
Simple multipurpose apparatus for solubility measurement of solid solutes in liquids
Malwade, Chandrakant Ramkrishna; Christensen, Lars Porskjær
2016-01-01
, solubility measurement of solid solutes in different solvents or solvent mixtures as a function of temperature can be of great significance to the university students and researchers. In this article, comparatively inexpensive apparatus for solubility measurement of solid solutes in pure or mixture......-hexane-ethyl acetate mixtures of varying composition at different temperatures to demonstrate the suitability and reliability of the proposed solubility measurement apparatus. The proposed apparatus has been used to conduct laboratory exercises in the course “Industrial Separation Technology” offered to undergraduate...
一矩阵方程组的反射解%Reflexive solution to a system of matrix equations
常海霞; 王卿文
2007-01-01
We derive necessary and sufficient conditions for the existence and an expression of the (anti)reflexive solution with respect to the nontrivial generalized reflection matrix P to the system of complex matrix equations AX = B and XC = D.The explicit solutions of the approximation problem minX∈φ‖X- E‖F was given, where E is a given complex matrix and o is it was pointed that some results in a recent paper are special cases of this paper.
Abdel-Shakoor M Sarhan
2016-05-01
Full Text Available Abstract We consider two nonlinear matrix equations X r ± ∑ i = 1 m A i ∗ X δ i A i = I $X^{r} \\pm \\sum_{i = 1}^{m} A_{i}^{*}X^{\\delta_{i}}A_{i} = I$ , where − 1 < δ i < 0 $- 1 < \\delta_{i} < 0$ , and r, m are positive integers. For the first equation (plus case, we prove the existence of positive definite solutions and extremal solutions. Two algorithms and proofs of their convergence to the extremal positive definite solutions are constructed. For the second equation (negative case, we prove the existence and the uniqueness of a positive definite solution. Moreover, the algorithm given in (Duan et al. in Linear Algebra Appl. 429:110-121, 2008 (actually, in (Shi et al. in Linear Multilinear Algebra 52:1-15, 2004 for r = 1 $r = 1$ is proved to be valid for any r. Numerical examples are given to illustrate the performance and effectiveness of all the constructed algorithms. In Appendix, we analyze the ordering on the positive cone P ( n ‾ $\\overline{P(n}$ .
Activities of the components in a spinel solid solution of the Fe-Al-O system
Lykasov, A. A.; Kimyashev, A. A.
2011-09-01
The conditions of the equilibrium between the Fe3O4-FeAl2O4 solution and wustite are determined by measuring the EMF of galvanic cells containing a solid electrolyte, and the activities of the components in the Fe3O4-FeAl2O4 solution are calculated by treating the results of the experiment on the equilibrium between the spinel solution and wustite. Their properties are found to be different from those of ideal solutions at temperatures of 1000-1300 K. A significant positive deviation from the Raoult's law is believed to indicate the tendency of the solution to decompose. The experimental data are treated in terms of the theory of regular solutions, assuming the energy of mixing to be a function of temperature only. The critical temperature of decomposition for the Fe3O4-FeAl2O4 solution is found to be 1084 K.
Panneerselvam, G.; Antony, M.P. [Fuel Chemistry Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Vasudevan, T. [Department of Industrial Chemistry, Alagappa University, Karaikkudi 630 003 (India)
2004-10-01
A series of solid solutions containing LaO{sub 1.5} in thoria (ThO{sub 2}) were prepared by coprecipitation method. These solid solutions were characterized for their composition by standard wet-chemical analysis. Their bulk and theoretical densities were determined by immersion and X-ray techniques. The extent of solid solubility of LaO{sub 1.5} in ThO{sub 2} matrix was determined using X-ray diffraction (XRD). The measured solubility of LaO{sub 1.5} is found to be in the range 49.7-50.3 mol% at 1473 K.
Facile synthesis of catalytically active CeO2-Gd2O3 solid solutions for soot oxidation
D Naga Durgasri; T Vinodkumar; Benjaram M Reddy
2014-03-01
CeO2-Gd2O3 oxides were synthesized by a modified coprecipitation method and subjected to thermal treatments at different temperatures to understand their thermal behaviour. The obtained samples were characterized by XRD, BET, TEM, Raman and TPR techniques. Catalytic efficiencies for oxygen storage/release capacity (OSC) and soot oxidation were evaluated by a thermogravimetric (TG) method. XRD and Raman results indicated the formation of Ce0.8Gd0.2O2− (CG) solid solutions at lower calcination temperatures, and TEM studies confirmed nanosized nature of the particles. Raman studies further confirmed the presence of oxygen vacancies and lattice defects in the CG sample. TPR measurements indicated a facile reduction of ceria after Gd3+ addition. Activity studies revealed that incorporation of Gd3+ into the ceria matrix favoured the creation of more structural defects, which accelerates the oxidation rate of soot compared to pure ceria.
Cazacu, Oana; Stewart, Joel B.
2013-05-01
A new analytic plastic potential is developed using a rigorous limit analysis approach. Conditions of homogeneous boundary strain rate are imposed on every cylinder concentric with the cavity. It is shown that, due to the tension-compression asymmetry of the incompressible matrix, the third invariant of the stress deviator has a strong influence on the yielding of the porous solid. New and intriguing results are obtained; namely, for axisymmetric loadings and plane strain conditions, the stress state at yielding is not hydrostatic. In the case when the matrix has the same yield in tension as in compression, the new criterion reduces to Gurson's criterion for cylindrical voids.
Wear of semi-solid rheocast SiCp/Al metal matrix composites
Curle, UA
2010-09-01
Full Text Available casting of SiC metal matrix composites. The metal matrix consisting of nearly spherical proeutectic a(Al) globules was produced. Spheroidization of fibrous eutectic silicon took place upon heat treatment of the as-cast metal matrix composites (MMCs...
Study of acid solution bonding in epoxy matrix for sealed radioactive sources production
Benega, Marcos A.G.; Nagatomi, Helio R.; Rostelato, Maria Elisa C.M.; Tiezzi, Rodrigo; Rodrigues, Bruna T.; Peleias Junior, Fernando; Souza, Carla D.; Souza, Daiane C.C. de; Souza, Anderson S. de; Silva, Thais H. da, E-mail: carladdsouza@yahoo.com.br, E-mail: marcosagbenega@gmail.com, E-mail: hrnagato@ipen.br, E-mail: elisaros@ipen.br, E-mail: rktiezzi@gmail.com, E-mail: bteigarodrigues@gmail.com, E-mail: fernandopeleias@gmail.com, E-mail: dcsouza@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)
2014-07-01
The present work aims to analyze different resin formulations. These formulations are used in the production of radioactive sealed sources that are used in many fields such as nuclear medicine; environmental analyzes, radiation detectors accuracy check, and so on. These sources can be produced with different radioisotopes and different activities, it all depending on the use they will have. Certain types of resins have the same density water. This property is appreciated when we consider that radiotracers used in nuclear medicine are applied in aqueous solutions. So the sources used for checking and calibrating equipment must have their radioisotopes sealed in a material having similar properties, thus the measures are reproducible and repetitive. The most important aspect that is brought to attention in this work is the miscibility those resins have with water. The radioisotopes for the production of the sources are supplied in an aqueous form. In case the resin and the radioisotope solution do not mix, the source will not be sturdy enough to seal the radioisotopes in its structure and the source will not be safe. There were prepared different formulations with different amounts of acid solution, and the cured formulations were analyzed by Wipe Test, DSC (Differential Splanatory Calorimetry) and also, the possible volatile aspect of the radionuclide used. All to evaluate the integrity of the sources. The obtained results were satisfactory and show that when the resin is well cured, the radioisotope remains sealed in the matrix, making it possible to produce radioactive sealed sources. (author)
Hollow nanoshell formation and collapse in binary solid solutions with large range of solubility
Gusak, A M; Zaporozhets, T V, E-mail: gusak@cdu.edu.u, E-mail: tvz@phys.cdu.edu.u [Cherkasy National University, 81, Boulevard Shevchenko, Cherkasy, 18031 (Ukraine)
2009-10-14
The formation of a solid solution hollow nanoshell from core-shell structure and collapse of this nanoshell into a compact particle is modelled by a phenomenological scheme and by Monte Carlo simulation. The cross-over between formation and collapse, and the criteria of nanoshell formation are analysed.
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
Thermochemical stability and nonstoichiometry of yttria-stabilized bismuth oxide solid solutions
Kruidhof, H.; Vries, de K.J.; Burggraaf, A.J.
1990-01-01
The thermochemical stability of fast oxygen ion conducting yttria stabilized bismuthoxide (YSB) solid solutions containing 22.0–32.5 mol% of yttria was investigated. It was shown that in the temperature range between 650–740 C the stabilized cubic δ-phase containing less than 31.8 mol% of yttria is
Fourier Transform Infrared Spectroscopic Study of Sodium Phosphate Solids and Solutions
龚文琪
2001-01-01
Solids and solutions of sodium phosphates with various chain lengths have been studied by using the techniques of diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, respectively. A systematic study of the infrared spectra of the solid sodium phosphates has been conducted on the basis of the information available in the literatures to establish the assignments of the infrared vibrations of the different groups in the phosphate molecules. The infrared spectra of the solutions of sodium phosphates have been analyzed according to the infrared study on the relevant solids, in conjunction with the study of the phosphate species distribution in solution on the basis of the acid-base reaction equilibria. The results obtained have revealed the correlations between the infrared absorption spectra and the structure of the different P-O groups in different kinds of phosphates and are useful in the analysis of phosphate solids and solutions widely used in the various operations of mineral processing.
Vapor-Liquid-Solid Equilibria of Sulfur Dioxide in Aqueous Electrolyte Solutions
Pereda, Selva; Thomsen, Kaj; Rasmussen, Peter
2000-01-01
The Extended UNIQUAC model for electrolyte systems, combined with the Soave-Redlich-Kwong equation of state is used to describe the complex vapor-liquid-solid equilibria of sulfur dioxide in electrolyte solutions. Model parameters based on 1500 experimental data points are presented. The paramete...
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…
Khundzhua; A.G.; Brovkina; E.A.
2005-01-01
The analysis of experiments demonstrates that in TiNi with dope d-transition elements of Ⅴ-Ⅷ subgroups the type of solid solution is determined not by the specific dope element, but by pertaining of the alloy to one of three main sections of state diagram forthe system Ti-Ni-Me.……
无
2005-01-01
@@ The analysis of experiments demonstrates that in TiNi with dope d-transition elements of Ⅴ-Ⅷ subgroups the type of solid solution is determined not by the specific dope element, but by pertaining of the alloy to one of three main sections of state diagram forthe system Ti-Ni-Me.
Experimental and theoretical investigation of Cr1-xScxN solid solutions for thermoelectrics
Kerdsongpanya, Sit; Sun, Bo; Eriksson, Fredrik
2016-01-01
. Here, we demonstrate an approach to tailor their thermoelectric properties by solid solutions. The trends in mixing thermodynamics and densities-of-states (DOS) of rocksalt-Cr1-xScxN solid solutions (0 ≤ x ≤ 1) are investigated by first-principles calculations, and Cr1-xScxN thin films are synthesized...... by magnetron sputtering. Pure CrN exhibits a high power factor, 1.7 × 10−3 W m−1 K−2 at 720 K, enabled by a high electron concentration thermally activated from N vacancies. Disordered rocksalt-Cr1-xScxN solid solutions are thermodynamically stable, and calculated DOS suggest the possibility for power......-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...
Gervais, C.; Grimbergen, R.F.P.; Markovits, I.; Ariaans, G.J.A.; Kaptein, B.; Bruggink, A.; Broxterman, Q.B.
2004-01-01
The possibility of solid solution behavior of diastereomeric salts, containing multiple resolving agents of the same family (Dutch Resolution), is predicted by molecular modeling. Super-cells containing different ratios of resolving agents in the diastereomeric salt are constructed and optimized, an
The synthesis and chemical durability of Nd-doped single-phase zirconolite solid solutions
Cai, Xin; Teng, Yuancheng; Wu, Lang; Zhang, Kuibao; Huang, Yi
2016-10-01
Nd-doped single-phase zirconolite solid solutions was synthesized by solid-state reaction and following two steps of acid treatment. The phase composition, microstructure, and chemical durability of the zirconolite solid solutions were investigated. About 15 at% Nd was successfully stabilized into the zirconolite. The element mapping images of Ca, Zr, Nd and Ti show that all the elements are almost distributed homogeneously in the zirconolite waste forms. Product Consistency Test (PCT) was conducted under different pH values (pH = 5, 7 and 9) to evaluate the chemical durability of the Nd-doped zirconolite waste forms. The normalized element release rate of Ca (LRCa) in pH = 5 medium is higher than that of pH = 7 and 9, while the LRNd value remains almost unchanged under different pH values. The LRNd value is as low as 10-5 g m-2 d-1 after 42 days.
Preparation, Characterization and Catalytic Performance of Nanometer Ceria-Zirconia Solid Solution
Hu Yucai; Wang Yinghui; Pan Junyan
2004-01-01
Ce0.6Zr0.4O2 solid solution was prepared by co-precipitation technique using hydrazine hydrate as precipitator.Various physico-chemical techniques such as XRD, FT-Raman, SEM, TEM, etc.were used to characterize the resultant powder.Meanwhile, its catalytic activity was evaluated in the synthesis of n-butyl acetate by the reaction of acetic acid and n-butyl alcohol.The results show that ceria-zirconia solid solution forms single cubic structure and its particle diameter is less than 100 nm.As a sort of solid acid, it possesses high catalytic activity and can be easily separated from reaction liquid.After it is used for ten times, its activity basically kees unchanging.
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)
Zhai, Yujuan; Cheng, Jianhua
2015-09-01
A method based on matrix solid-phase dispersion and high-performance liquid chromatography was applied to the determination of four Sudan red residues in sausage. The proposed method required only 0.5 g sample. The neutral alumina was used as the dispersant sorbent while n-hexane containing 10% (v/v) acetone was used as the eluting solvent. The recoveries in samples ranged from 76.4 to 111.0% and relative standard deviations were sausage.
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.
Low temperature anomaly of heat capacity of CD4 rotors in solid CD4-Kr solution
Bagatskii, M.I.; Dudkin, V. V.; Manzhelii, V. G.; Mashchenko, D. A.; Feodosiev, S. B.
2004-01-01
The heat capacity of the solid Kr-CD4 (13% CD4) solution has been investigated. It is shown that the temperature dependence of the heat capacity Crot of the rotational subsystem in this solution is radically different from the corresponding dependences in the previously studied Kr-CD4 (1%, 5% CD4) and Kr-CH4 (5-60%) solutions. A model is proposed to explain the observed dependence Crot(T). The experimental results can be described taking into account the contribution to the heat capacity from...
Ahmad, Javed; Amin, Saima; Rahman, Mahfoozur; Rub, Rehan Abdur; Singhal, Madhur; Ahmad, Mohammad Zaki; Rahman, Ziyaur; Addo, Richard T; Ahmad, Farhan Jalees; Mushtaq, Gohar; Kamal, Mohammad Amjad; Akhter, Sohail
2015-01-01
Chemotherapeutic delivery by oral route in cancer patients has the potential to create "hospitalization free chemotherapy" which is a vision of oncologists, formulation scientists and patients. Such a therapeutic approach will improve patients' compliance, ease the burden of the patients' caregivers and significantly reduce the cost of treatment. In current clinical practice, chemotherapy carried out by intravenous injection or infusion leads to undesired side-effects such as plasma concentrations crossing the maximum safe concentration, rapid body clearance and lower bioavailability. Despite the presence of challenges such as poor aqueous solubility and stability of drugs and the presence of biological barriers like multidrug efflux transporter in the GI tract, oral cancer chemotherapy has the potential to surmount those obstacles. Lipid nanoparticles (LNPs) such as solid lipid nanoparticle, nanostructured lipid carriers, nano lipid-drug conjugates, mixed micelles, liposomes and nanoemulsions have shown some promising results for use in oral anticancer drug delivery through nanotechnological approach. LNPs demonstrate enhanced oral bioavailability owing to their ability to inhibit first pass metabolism via lymphatic absorption by chylomicron-linked and/or M-cell uptake. LNPs reduce the inter- and intrasubject pharmacokinetics variability of administrated drugs. Moreover, certain classes of phospholipids and surfactants used in the formulations of LNPs can suppress the P-glycoprotein efflux system. Here, we shall be discussing the biopharmaceutical challenges in oral cancer chemotherapy and how the LNPs may provide solutions to such challenges. The effect of GI tract environment on LNPs and pharmacokinetics shall also be discussed.
Real-time Numerical Solution for the Plasma Response Matrix for Disruption Avoidance in ITER
Glasser, Alexander; Kolemen, Egemen; Glasser, A. H.
2016-10-01
Real-time analysis of plasma stability is essential to any active feedback control system that performs ideal MHD disruption avoidance. Due to singularities and poor numerical conditioning endemic to ideal MHD models of tokamak plasmas, current state-of-the-art codes require serial operation, and are as yet inoperable on the sub- O (1s) timescale required by ITER's MHD evolution time. In this work, low-toroidal-n ideal MHD modes are found in near real-time as solutions to a well-posed boundary value problem. Using a modified parallel shooting technique and linear methods to subdue numerical instability, such modes are integrated with parallelization across spatial and ``temporal'' parts, via a Riccati approach. The resulting state transition matrix is shown to yield the desired plasma response matrix, which describes how magnetic perturbations may be employed to maintain plasma stability. Such an algorithm may be helpful in designing a control system to achieve ITER's high-performance operational objectives. Sponsored by US DOE under DE-SC0015878 and DE-FC02-04ER54698.
Gañán, Judith; Morante-Zarcero, Sonia; Gallego-Picó, Alejandrina; Garcinuño, Rosa María; Fernández-Hernando, Pilar; Sierra, Isabel
2014-08-01
A molecularly imprinted polymer-matrix solid-phase dispersion methodology for simultaneous determination of five steroids in goat milk samples was proposed. Factors affecting the extraction recovery such as sample/dispersant ratio and washing and elution solvents were investigated. The molecularly imprinted polymer used as dispersant in the matrix solid-phase dispersion procedure showed high affinity to steroids, and the obtained extracts were sufficiently cleaned to be directly analyzed. Analytical separation was performed by micellar electrokinetic chromatography using a capillary electrophoresis system equipped with a diode array detector. A background electrolyte composed of borate buffer (25mM, pH 9.3), sodium dodecyl sulfate (10mM) and acetonitrile (20%) was used. The developed MIP-MSPD methodology was applied for direct determination of testosterone (T), estrone (E1), 17β-estradiol (17β-E2), 17α-ethinylestradiol (EE2) and progesterone (P) in different goat milk samples. Mean recoveries obtained ranged from 81% to 110%, with relative standard deviations (RSD)≤12%. The molecularly imprinted polymer-matrix solid-phase dispersion method is fast, selective, cost-effective and environment-friendly compared with other pretreatment methods used for extraction of steroids in milk.
Different routes towards oscillatory zoning in the growth of solid solutions.
Lubashevsky, Ihor; Mues, Tanja; Heuer, Andreas
2008-10-01
Oscillatory zoning, i.e., self-formation of spatial quasiperiodic oscillations in the composition of solid growing from aqueous solution, is analyzed theoretically. Keeping in mind systems like (Ba,Sr)SO4 , we propose a one-dimensional model that takes into account the nonideality of the solid solution and the system asymmetry, in particular, reflecting itself in different solubilities for such systems. Based on a linear stability analysis, different parameter regions can be identified. Even an ideal solution with a sufficiently large asymmetry can display oscillatory zoning. Numerical simulations complement the linear stability analysis as well as the qualitative consideration of the instability development and reveal the nature of the limit cycles.
Dongping TAO
2011-01-01
The molecular interaction vacancy model (MIVM) is used to estimate simultaneously activities of all components in a range of entire composition of six binary oxide solid solutions and the MnO-FeO-CaO ternary solid solution by their binary infinite dilute activity coefficients.The average errors are the 0.03%-5.0% for the binaries and the 4.11%-25.2% for the ternary which is less than that (4.84%-41.2%) of the sub-regular solution model (SRSM).This shows that MIVM is more effective and reliable than SRSM for the ternary and does not depend on a polynomial approximation with some ternary adjustable parameters.
Zhao, Yanran; Wu, Chuan; Peng, Gang; Chen, Xiaotian; Yao, Xiayin; Bai, Ying; Wu, Feng; Chen, Shaojie; Xu, Xiaoxiong
2016-01-01
Li10GeP2S12 (LGPS) is incorporated into polyethylene oxide (PEO) matrix to fabricate composite solid polymer electrolyte (SPE) membranes. The lithium ion conductivities of as-prepared composite membranes are evaluated, and the optimal composite membrane exhibits a maximum ionic conductivity of 1.21 × 10-3 S cm-1 at 80 °C and an electrochemical window of 0-5.7 V. The phase transition behaviors for electrolytes are characterized by DSC, and the possible reasons for their enhanced ionic conductivities are discussed. The LGPS microparticles, acting as active fillers incorporation into the PEO matrix, have a positive effect on the ionic conductivity, lithium ion transference number and electrochemical stabilities. In addition, two kinds of all-solid-state lithium batteries (LiFeO4/SPE/Li and LiCoO2/SPE/Li) are fabricated to demonstrate the good compatibility between this new SPE membrane and different electrodes. And the LiFePO4/Li battery exhibits fascinating electrochemical performance with high capacity retention (92.5% after 50 cycles at 60 °C) and attractive capacities of 158, 148, 138 and 99 mAh g-1 at current rates of 0.1 C, 0.2 C, 0.5 C and 1 C at 60 °C, respectively. It is demonstrated that this new composite SPE should be a promising electrolyte applied in solid state batteries based on lithium metal electrode.
Takeda, Koji; Gotoda, Yuto; Hirota, Daichi; Hidaka, Fumihiro; Sato, Tomo; Matsuura, Tsutashi; Imanaka, Hiroyuki; Ishida, Naoyuki; Imamura, Koreyoshi
2017-03-06
The technique for homogeneously dispersing hydrophobic drugs in a water-soluble solid matrix (solid dispersion) is a subject that has been extensively investigated in the pharmaceutical industry. Herein, a novel technique for dispersing a solid, without the need to use a surfactant, is reported. A freeze-dried amorphous sugar sample was dissolved in an organic solvent, which contained a soluble model hydrophobic component. The suspension of the sugar and the model hydrophobic component was vacuum foam dried to give a solid powder. Four types of sugars and methanol were used as representative sugars and the organic medium. Four model drugs (indomethacin, ibuprofen, gliclazide, and nifedipine) were employed. Differential scanning calorimetry analyses indicated that the sugar and model drug (100:1) did not undergo segregation during the drying process. The dissolution of the hydrophobic drugs in water from the solid dispersion was then evaluated, and the results indicated that the Cmax and AUC0-60 min of the hydrophobic drug in water were increased when the surfactant-free solid dispersion was used. Palatinose and/or α-maltose were superior to the other tested carbohydrates in increasing Cmax and AUC0-60 min for all tested model drugs, and the model drug with a lower water solubility tended to exhibit a greater extent of over-dissolution.
The {P,Q,k+1}-Reflexive Solution to System of Matrix Equations AX=C, XB=D
Chang-Zhou Dong
2015-01-01
Full Text Available Let P∈Cm×m and Q∈Cn×n be Hermitian and {k+1}-potent matrices; that is, Pk+1=P=P⁎ and Qk+1=Q=Q⁎, where ·⁎ stands for the conjugate transpose of a matrix. A matrix X∈Cm×n is called {P,Q,k+1}-reflexive (antireflexive if PXQ=X (PXQ=-X. In this paper, the system of matrix equations AX=C and XB=D subject to {P,Q,k+1}-reflexive and antireflexive constraints is studied by converting into two simpler cases: k=1 and k=2. We give the solvability conditions and the general solution to this system; in addition, the least squares solution is derived; finally, the associated optimal approximation problem for a given matrix is considered.
Minuti, Lucio; Pellegrino, Roberto
2008-03-21
A novel matrix solid-phase dispersion (MSPD) extraction method was developed to extract simultaneously 23 phenolic compounds from wine samples prior to determination by gas chromatography with mass spectrometric detection in the selected ion monitoring mode. Different parameters of the MSPD technique such as dispersant solid-phase, eluting solvent, and sample ionic strength and pH were optimized. The optimized MSPD procedure requires a small volume of wine (1 mL), commercial silica gel (1.5 g) as dispersant solid-phase and a small volume of ethyl acetate (5 mL) as eluting solvent. Under these conditions, the extraction of the studied compounds was almost complete (mean values of recoveries between 87 and 109%) in a short time (15 min). Moreover, satisfactory standard deviations of repeatability (RSD0.993) and detection limits (wines. Application was illustrated by analysis of different wine samples.
Synthesis of Platinum Nanoparticles from K2PtCl4 Solution Using Bacterial Cellulose Matrix
H. F. Aritonang
2014-01-01
Full Text Available Platinum (Pt nanoparticles have been synthesized from a precursor solution of potassium tetrachloroplatinate (K2PtCl4 using a matrix of bacterial cellulose (BC. The formation of Pt nanoparticles occurs at the surface and the inside of the BC membrane by reducing the precursor solution with a hydrogen gas reductant. The Pt nanoparticles obtained from the variations of precursor concentration, between 3 mM and 30 mM, and the formation of Pt nanoparticles have been studied using X-ray diffraction (XRD, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS, and thermogravimetry analysis (TGA. Based on X-ray diffraction patterns, Pt particles have sizes between 6.3 nm and 9.3 nm, and the Pt particle size increases with an increase in precursor concentration. The morphology of the Pt nanoparticles was observed by SEM-EDS and the content of Pt particles inside the membrane is higher than that on the surface of BC membranes. This analysis corresponds to the TGA analysis, but the TGA analysis is more representative in how it describes the content of Pt particles in the BC membrane.
On the Centro-symmetric Solution of a System of Matrix Equations over a Regular Ring with Identity
Qingwen Wang; Haixia Chang; Chunyan Lin
2007-01-01
In this paper, we find the centro-symmetric solution of a system of matrix equations over an arbitrary regular ring R with identity. We first derive some necessary and sufficient conditions for the existence and an explicit expression of the general solution of the system of matrix equations A1X1 = C1, A2X1 = C2, A3X2 = C3, A4X2 = C4 and A5X1B5 + A6X2B6= C5 over R. By using the above results, we establish two criteria for the existence and the representation of the general centro-symmetric solution of the system of matrix equations AaX = Ca, AbX = Cb and AcXBc = Cc over the ring R.
Cheng Zhang
2017-07-01
Full Text Available The thermogravimetric analysis on TaC, HfC, and their solid solutions has been carried out in air up to 1400 °C. Three solid solution compositions have been chosen: 80TaC-20 vol % HfC (T80H20, 50TaC-50 vol % HfC (T50H50, and 20TaC-80 vol % HfC (T20H80, in addition to pure TaC and HfC. Solid solutions exhibit better oxidation resistance than the pure carbides. The onset of oxidation is delayed in solid solutions from 750 °C for pure TaC, to 940 °C for the T50H50 sample. Moreover, T50H50 samples display the highest resistance to oxidation with the retention of the initial carbides. The oxide scale formed on the T50H50 sample displays mechanical integrity to prevent the oxidation of the underlying carbide solid solution. The improved oxidation resistance of the solid solution is attributed to the reaction between Ta2O5 and HfC, which stabilizes the volume changes induced by the formation of Ta2O5 and diminishes the generation of gaseous products. Also, the formation of solid solutions disturbs the atomic arrangement inside the lattice, which delays the reaction between Ta and O. Both of these mechanisms lead to the improved oxidation resistances of TaC-HfC solid solutions.
The mechanism and kinetics of decomposition of a highly supersaturated solid solution in an alloy is of importance in stating the proper technology...that during annealing up to 250 C, there is a great density of dislocations. A hypothesis is presented concerning the structural changes occurring at heating the highly supersaturated solid solution of this alloy.
Wang, Lu; Wu, Qian; Duan, Chunfeng; Wu, Dapeng; Guan, Yafeng
2011-09-01
A method for the analysis of gibberellin A1 (GA1), gibberellin A3 (GA3) and gibberellin A4 (GA4) in Arabidopsis thaliana by matrix solid-phase dispersion extraction (MSPD) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. The solid sample of Arabidopsis thaliana was gently blended with C18 to obtain a homogeneous mixture. This mixture was transferred to an SPE cartridge filled with 0.5 g C18 to form a MSPD column. GA1, GA3 and GA4 were eluted with cold 80% methanol aqueous solution. The target compounds were separated on a C18 column with a gradient elution of 0.05% formic acid aqueous solution and acetonitrile as the mobile phase. The identification and quantification were carried out by using electrospray ionization in negative ion mode (ESI-) with multiple reaction monitoring (MRM). The linear ranges for GA1, GA3 and GA4 were all from 10 to 300 ng/g with correlation coefficients greater than 0.98. The limits of detection were in the range of 1.1-4.1 ng/g. The average recoveries and relative standard deviations were 54.7%-102.6% and 3.2%-12.8% respectively in the spiked range of 10-50 ng/g. The method is simple, sensitive, efficient and accurate. It is suitable for the confirmation and quantitative determination of GA1, GA3 and GA4 in Arabidopsis thaliana.
Hirsch, A.; Kegler, P.; Alencar, I.; Ruiz-Fuertes, J.; Shelyug, A.; Peters, L.; Schreinemachers, C.; Neumann, A.; Neumeier, S.; Liermann, H.-P.; Navrotsky, A.; Roth, G.
2017-01-01
The monazite-type solid solution La1-xPrxPO4 was synthesized by solid-state reaction and extensively investigated using electron microprobe and thermogravimetric analyses, differential scanning and high-temperature oxide melt solution calorimetry, powder X-ray diffraction, infrared and Raman spectroscopy. Lattice parameters and Ln-O bond lengths show a decrease with increasing Pr content. A small excess volume is observed for the solid solution. IR spectra of the solid solution members present no detectable differences, while a blue shift of the PO4-related modes is seen in the Raman data. This shift can be attributed to the lanthanide contraction. Within errors, calorimetry data show no systematic deviation from an ideal behavior, though one might interpret the data as an indication of a slightly asymmetric mixture. All data indicate that deviations from ideality of the solid solution - if present - are very small.
AbstractFour tetrols of benzo[a]pyrene-DNA adducts were separated using reversed-phase high performance liquid chromatography. Chromatographic fractions containing a given tetrol were readily characterized with solid-matrix room temperature luminescence techniques. So...
Co-existence of Distinct Supramolecular Assemblies in Solution and in the Solid State.
Reddy, G N Manjunatha; Huqi, Aida; Iuga, Dinu; Sakurai, Satoshi; Marsh, Andrew; Davis, Jeffery T; Masiero, Stefano; Brown, Steven P
2017-02-16
The formation of distinct supramolecular assemblies, including a metastable species, is revealed for a lipophilic guanosine (G) derivative in solution and in the solid state. Structurally different G-quartet-based assemblies are formed in chloroform depending on the nature of the cation, anion and the salt concentration, as characterized by circular dichroism and time course diffusion-ordered NMR spectroscopy data. Intriguingly, even the presence of potassium ions that stabilize G-quartets in chloroform was insufficient to exclusively retain such assemblies in the solid state, leading to the formation of mixed quartet and ribbon-like assemblies as revealed by fast magic-angle spinning (MAS) NMR spectroscopy. Distinct N-H⋅⋅⋅N and N-H⋅⋅⋅O intermolecular hydrogen bonding interactions drive quartet and ribbon-like self-assembly resulting in markedly different 2D (1) H solid-state NMR spectra, thus facilitating a direct identification of mixed assemblies. A dissolution NMR experiment confirmed that the quartet and ribbon interconversion is reversible-further demonstrating the changes that occur in the self-assembly process of a lipophilic nucleoside upon a solid-state to solution-state transition and vice versa. A systematic study for complexation with different cations (K(+) , Sr(2+) ) and anions (picrate, ethanoate and iodide) emphasizes that the existence of a stable solution or solid-state structure may not reflect the stability of the same supramolecular entity in another phase. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
In situ study of the solid-state formation of U(1-x)Am(x)O(2±δ) solid solution.
Lebreton, Florent; Belin, Renaud C; Prieur, Damien; Delahaye, Thibaud; Blanchart, Philippe
2012-09-03
In order to reduce the nuclear waste inventory and radiotoxicity, U(1-x)Am(x)O(2±δ) materials are promising fuels for heterogeneous transmutation. In this context, they are generally fabricated from UO(2+δ) and AmO(2-δ) dioxide powders. In the subsequent solid solution, americium is assumed to be trivalent whereas uranium exhibits a mixed-valence (+IV/+V) state. However, no formation mechanisms were ever evidenced and, more particularly, it was not possible to know whether the reduction of Am(IV) to Am(III) occurs before the solid-solution formation, or only once it is established. In this study, we used high-temperature X-ray diffraction on a UO(2±δ)/AmO(2-δ) (15 mol %) mixture to observe in situ the formation of the U(1-x)Am(x)O(2±δ) solid solution. We show that UO(2+δ) is, at relatively low temperature (solid solution starts forming at 1740 K. The UO(2) fluorite phase vanishes after 4 h at 1970 K, indicating that the formation of the solid solution is completed, which proves that this solid solution is formed after the complete reduction of Am(IV) to Am(III).
Zhang, Yanwen; Stocks, G Malcolm; Jin, Ke; Lu, Chenyang; Bei, Hongbin; Sales, Brian C; Wang, Lumin; Béland, Laurent K; Stoller, Roger E; Samolyuk, German D; Caro, Magdalena; Caro, Alfredo; Weber, William J
2015-10-28
A grand challenge in materials research is to understand complex electronic correlation and non-equilibrium atomic interactions, and how such intrinsic properties and dynamic processes affect energy transfer and defect evolution in irradiated materials. Here we report that chemical disorder, with an increasing number of principal elements and/or altered concentrations of specific elements, in single-phase concentrated solid solution alloys can lead to substantial reduction in electron mean free path and orders of magnitude decrease in electrical and thermal conductivity. The subsequently slow energy dissipation affects defect dynamics at the early stages, and consequentially may result in less deleterious defects. Suppressed damage accumulation with increasing chemical disorder from pure nickel to binary and to more complex quaternary solid solutions is observed. Understanding and controlling energy dissipation and defect dynamics by altering alloy complexity may pave the way for new design principles of radiation-tolerant structural alloys for energy applications.
Effect of shear stress in ferroelectric solid solutions with coexisting phases
Lu, Xiaoyan; Zhang, Hangbo; Zheng, Limei; Cao, Wenwu
2017-08-01
One common feature of ferroelectric solid solutions with large piezoelectricity is the coexistence of two or more phases. Due to the strain mismatch among coexisting phases, adaptive structures near the interfaces or domain walls develop to maintain the atomic coherency. Shear stresses commonly exist, especially when the domain size is small. The effect of shear stresses on phase morphology in Pb(Zr1-xTix)O3 solid solutions with compositions within the morphotropic phase boundary region was studied within the framework of Landau phenomenological theory. Our results show that the coexisting rhombohedral (R) and tetragonal (T) phases can be modified to form stable or metastable R-like and/or T-like monoclinic phases under shear stresses. Large stresses may also induce first order or second order phase transitions.
Elastic and thermal properties of Zr z Nb1 - z C x N y solid solutions
Gusev, A. I.
2013-07-01
The temperature and concentration dependences of the elastic moduli and the thermal linear expansion coefficient of Zr z Nb1 - z C x N y solid solutions containing from 3 to 8 at % of structural vacancies in a nonmetallic sublattice have been found. The temperature dependences of the Debye temperature ΘD( T) have been calculated using the elastic data and the data on the heat capacity. It has been shown, using carbide NbC0.97 as an example, that the ΘD( T) dependences found from the elastic properties and the heat capacity coincide in the temperature range ˜220-300 K. By analogy with the niobium carbide, the heat capacity C p (300) of Zr z Nb1 - z C x N y solid solutions of various compositions is calculated based on the values of ΘD(300) determined from the elastic properties.
Accelerated exploration of multi-principal element alloys with solid solution phases
Senkov, O. N.; Miller, J. D.; Miracle, D. B.; Woodward, C.
2015-03-01
Recent multi-principal element, high entropy alloy (HEA) development strategies vastly expand the number of candidate alloy systems, but also pose a new challenge—how to rapidly screen thousands of candidate alloy systems for targeted properties. Here we develop a new approach to rapidly assess structural metals by combining calculated phase diagrams with simple rules based on the phases present, their transformation temperatures and useful microstructures. We evaluate over 130,000 alloy systems, identifying promising compositions for more time-intensive experimental studies. We find the surprising result that solid solution alloys become less likely as the number of alloy elements increases. This contradicts the major premise of HEAs—that increased configurational entropy increases the stability of disordered solid solution phases. As the number of elements increases, the configurational entropy rises slowly while the probability of at least one pair of elements favouring formation of intermetallic compounds increases more rapidly, explaining this apparent contradiction.
Modeling of Vapor-Liquid-Solid Equilibria in Acidic Aqueous Solutions
Christensen, Søren Gregers; Thomsen, Kaj
2003-01-01
The phase behavior (vapor - liquid equilibria (VLE) and solid - liquid equilibria (SLE)) and thermal properties of aqueous solutions of ions like (K+, Na+, NH4+, Ca2+, Cl-) in the presence of phosphoric acid (H3PO4, H2PO4-, HPO42- ) and nitric acid (HNO3, NO3-) are described by means of the Exten......The phase behavior (vapor - liquid equilibria (VLE) and solid - liquid equilibria (SLE)) and thermal properties of aqueous solutions of ions like (K+, Na+, NH4+, Ca2+, Cl-) in the presence of phosphoric acid (H3PO4, H2PO4-, HPO42- ) and nitric acid (HNO3, NO3-) are described by means...
Liu, Si-Yang; Zhou, Dong-Dong; He, Chun-Ting; Liao, Pei-Qin; Cheng, Xiao-Ning; Xu, Yan-Tong; Ye, Jia-Wen; Zhang, Jie-Peng; Chen, Xiao-Ming
2016-12-23
Mixing molecular building blocks in the solid solution manner is a valuable strategy to obtain structures and properties in between the isostructural parent metal-organic frameworks (MOFs). We report nonlinear/synergistic solid-solution effects using highly related yet non-isostructural, phosphorescent Cu(I) triazolate frameworks as parent phases. Near the phase boundaries associated with conformational diversity and ligand heterogeneity, the porosity (+150 %) and optical O2 sensitivity (410 times, limit of detection 0.07 ppm) can be drastically improved from the best-performing parent MOFs and even exceeds the records hold by precious-metal complexes (3 ppm) and C70 (0.2 ppm).
Accelerated exploration of multi-principal element alloys with solid solution phases.
Senkov, O N; Miller, J D; Miracle, D B; Woodward, C
2015-03-05
Recent multi-principal element, high entropy alloy (HEA) development strategies vastly expand the number of candidate alloy systems, but also pose a new challenge--how to rapidly screen thousands of candidate alloy systems for targeted properties. Here we develop a new approach to rapidly assess structural metals by combining calculated phase diagrams with simple rules based on the phases present, their transformation temperatures and useful microstructures. We evaluate over 130,000 alloy systems, identifying promising compositions for more time-intensive experimental studies. We find the surprising result that solid solution alloys become less likely as the number of alloy elements increases. This contradicts the major premise of HEAs--that increased configurational entropy increases the stability of disordered solid solution phases. As the number of elements increases, the configurational entropy rises slowly while the probability of at least one pair of elements favouring formation of intermetallic compounds increases more rapidly, explaining this apparent contradiction.
Aguirre-Díaz, Lina María; Gándara, Felipe; Iglesias, Marta; Snejko, Natalia; Gutiérrez-Puebla, Enrique; Monge, M Ángeles
2015-05-20
The aim of this research is to establish how metal-organic frameworks (MOFs) composed of more than one metal in equivalent crystallographic sites (solid solution MOFs) exhibit catalytic activity, which is tunable by virtue of the metal ions ratio. New MOFs with general formula [InxGa1-x(O2C2H4)0.5(hfipbb)] were prepared by the combination of Ga and In. They are isostructural with their monometal counterparts, synthesized with Al, Ga, and In. Differences in their behavior as heterogeneous catalysts in the three-component, one pot Strecker reaction illustrate the potential of solid solution MOFs to provide the ability to address the various stages involved in the reaction mechanism.
Isomorphism and solid solution as shown by an accurate high-resolution diffraction experiment.
Poulain, Agnieszka; Kubicki, Maciej; Lecomte, Claude
2014-12-01
High-resolution crystal structure determination and spherical and multipolar refinement enabled an organic solid solution of 1-(4'-chlorophenyl)-2-methyl-4-nitro-1H-imidazole-5-carbonitrile and 5-bromo-1-(4'-chlorophenyl)-2-methyl-4-nitro-1H-imidazole to be found, which would not normally be revealed using only standard resolution data (ca 0.8 Å), as the disordered part is only visible at high resolution. Therefore, this new structure would have been reported as just another polymorphic form, even more reasonably as isostructural with other derivatives. To the best of our knowledge this is the first example of organic solid solution modelled via charge density Hansen-Coppens formalism and analysed by means of quantum theory of atoms in molecules (QTAIM) theory.
Takahashi, Daisuke A
2015-01-01
The matrix-generalized Bogoliubov-de Gennes systems are recently considered by the present author [arXiv:1509.04242], and the time-dependent and self-consistent multi-soliton solutions are constructed based on the ansatz method. In this paper, restricting the problem to the static case, we exhaustively determine the self-consistent solutions using the inverse scattering theory. Solving the gap equation, we rigorously prove that the self-consistent potential must be reflectionless. As a supplementary topic, we elucidate the relation between the stationary self-consistent potentials and the soliton solutions in the matrix nonlinear Schr\\"odinger equation. The asymptotic formulae of multi-soliton solutions for sufficiently isolated solitons are also presented.
General solution of cumulative second harmonic by Lamb wave propagation in a solid plate
Deng Mingxi
2008-01-01
A straightforward approach has been developed for the general solution of cumulative second harmonic by Lamb wave propagation in a solid plate. The present analyses of second-harmonic generation by Lamb waves focus on the cases where the phase velocity of the fundamental Lamb wave is exactly or approximately equal to that of the double frequency Lamb wave (DFLW). Based on the general solution obtained, the numerical analyses show that the cumulative second-harmonic fields are associated with the position of excitation source and the difference between the phase velocity of the fundamental Lamb wave and that of the dominant DFLW component.
On the effect of concentrated solid solutions on properties of clusters in a model binary alloy
Lepinoux, J.; Sigli, C.
2016-04-01
In a series of papers aimed at better understanding precipitation in binary alloys, it was shown that Cluster Dynamics (CD) is a valuable tool to bridge the gap between microscopic and macroscopic scales, provided that cluster-free energies are carefully derived from Monte Carlo calculations. Indeed, in such conditions, CD predictions compare well with Atomistic Kinetic MC simulations. Nevertheless, in a recent work, the authors pointed out some limitations of this approach at high solute concentration. The present work aims at revisiting the notion of cluster-free energy in the context of concentrated solid solutions at thermal equilibrium.
Xu, Xiaomin; Xiao, Ting; Gu, Xiao; Yang, Xuejin; Kershaw, Stephen V; Zhao, Ni; Xu, Jianbin; Miao, Qian
2015-12-30
Here, we report solid solution of p- and n-type organic semiconductors as a new type of p-n blend for solution-processed ambipolar organic thin film transistors (OTFTs). This study compares the solid-solution films of silylethynylated tetraazapentacene 1 (acceptor) and silylethynylated pentacene 2 (donor) with the microphase-separated films of 1 and 3, a heptagon-embedded analogue of 2. It is found that the solid solutions of (1)x(2)1-x function as ambipolar semiconductors, whose hole and electron mobilities are tunable by varying the ratio of 1 and 2 in the solid solution. The OTFTs of (1)0.5(2)0.5 exhibit relatively balanced hole and electron mobilities comparable to the highest values as reported for ambipolar OTFTs of stoichiometric donor-acceptor cocrystals and microphase-separated p-n bulk heterojunctions. The solid solution of (1)0.5(2)0.5 and the microphase-separated blend of 1:3 (0.5:0.5) in OTFTs exhibit different responses to light in terms of absorption and photoeffect of OTFTs because the donor and acceptor are mixed at molecular level with π-π stacking in the solid solution.
Choonara, Bibi F; Choonara, Yahya E; Kumar, Pradeep; du Toit, Lisa C; Tomar, Lomas K; Tyagi, Charu; Pillay, Viness
2015-08-01
A menthol-based solid dispersion was designed to improve the intrinsic solubility of the poorly soluble sulfamethoxazole- a class II drug molecule of Biopharmaceutics Classification System (BCS) displaying widespread antibacterial activity. Solid dispersions of menthol and sulfamethoxazole were compressed with hydroxypropyl methylcellulose (HPMC) into suitable sulfamethoxazole-loaded matrix tablets for oral drug delivery. The sulfamethoxazole-loaded solid dispersions and compressed tablets were characterized for their physicochemical and physicomechanical properties such as changes in crystallinity, melting point, molecular transitions, and textural analysis for critical analysis of their effects on the solubility and dissolution of sulfamethoxazole. The formulations were further evaluated for swelling, degradation, solubility, and in vitro drug release behavior. In vitro drug release from the sulfamethoxazole-loaded matrix tablets displayed a minimum and maximum fractional release of 0.714 and 0.970, respectively. The tablets further displayed different release rate profiles over the study periods of 12, 16, 48, and 56 h which were attributed to the varying concentrations of menthol within each formulation. Menthol was determined as a suitable hydrophilic carrier for sulfamethoxazole since it functioned as a solubilizing and release-retarding agent for improving the solubility and dissolution of sulfamethoxazole as well as controlling the rate at which it was released.
Homogenization of. beta. -solid solution during fast heating of two-phase titanium alloys
Gridnev, V.N.; Zhuravlev, A.F.; Zhuravlev, B.F.; Ivasishin, O.M.; Markovskij, P.E. (AN Ukrainskoj SSR, Kiev. Inst. Metallofiziki)
1985-01-01
Using model alloy Ti-10%Mo as an example the homogenization of high-temperature ..beta..-phase during fast heating has been studied by calculational and experimental methods. The effect of heating rate and the initial structure disoersion on the homogenization is shown. A method is suggested for evaluation of the concentration state of ..beta..-solid solution depleted parts of commercial two-phase titanium alloys. The method has been used to study the homogenization process.
Properties of solid solutions, doped film, and nanocomposite structures based on zinc oxide
Lashkarev, G. V.; Shtepliuk, I. I.; Ievtushenko, A. I.; Khyzhun, O. Y.; Kartuzov, V. V.; Ovsiannikova, L. I.; Karpyna, V. A.; Myroniuk, D. V.; Khomyak, V. V.; Tkach, V. N.; Timofeeva, I. I.; Popovich, V. I.; Dranchuk, N. V.; Khranovskyy, V. D.; Demydiuk, P. V.
2015-02-01
A study of the properties of materials based on the wide bandgap zinc oxide semiconductor, which are promising for application in optoelectronics, photovoltaics and nanoplasmonics. The structural and optical properties of solid solution Zn1-xCdxO films with different cadmium content, are studied. The samples are grown using magnetron sputtering on sapphire backing. Low-temperature photoluminescence spectra revealed emission peaks associated with radiative recombination processes in those areas of the film that have varying amounts of cadmium. X-ray phase analysis showed the presence of a cadmium oxide cubic phase in these films. Theoretical studies of the solid solution thermodynamic properties allowed for a qualitative interpretation of the observed experimental phenomena. It is established that the growth of the homogeneous solid solution film is possible only at high temperatures, whereas regions of inhomogeneous composition can be narrowed through elastic deformation, caused by the mismatch of the film-backing lattice constants. The driving forces of the spinodal decomposition of the Zn1-xCdxO system are identified. Fullerene-like clusters of Znn-xCdxOn are used to calculate the bandgap and the cohesive energy of ZnCdO solid solutions. The properties of transparent conductive ZnO films, doped with Group III donor impurities (Al, Ga, In), are examined. It is shown that oxygen vacancies are responsible for the hole trap centers in the zinc oxide photoconductivity process. We also examine the photoluminescence properties of metal-ZnO nanocomposite structures, caused by surface plasmons.
GENERAL SOLUTION FOR THE COUPLED EQUATIONS OF TRANSVERSELY ISOTROPIC MAGNETOELECTROELASTIC SOLIDS
刘金喜; 王祥琴; 王彪
2003-01-01
The coupling feature of transversely isotropic magnetoelectroelastic solids aregoverned by a system of five partial differential equations with respect to the elasticdisplacerments, the electric potential and the magnetic potential. Based on the potentialtheory, the coupled equations are reduced to the five uncoupled generalized Laplaceequations with respect to five potential functions. Further, the elastic fields andelectromagnetic fields are expressed in terms of the potential functions. These expressionsconstruct the general solution of transversely isotropic magnetoelectroelastic media.
Experimental and theoretical investigation of Cr1-xScxN solid solutions for thermoelectrics
Kerdsongpanya, Sit; Sun, Bo; Eriksson, Fredrik; Jensen, Jens; Lu, Jun; Koh, Yee Kan; Nong, Ngo Van; Balke, Benjamin; Alling, Björn; Eklund, Per
2016-12-01
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. Here, we demonstrate an approach to tailor their thermoelectric properties by solid solutions. The trends in mixing thermodynamics and densities-of-states (DOS) of rocksalt-Cr1-xScxN solid solutions (0 ≤ x ≤ 1) are investigated by first-principles calculations, and Cr1-xScxN thin films are synthesized by magnetron sputtering. Pure CrN exhibits a high power factor, 1.7 × 10-3 W m-1 K-2 at 720 K, enabled by a high electron concentration thermally activated from N vacancies. Disordered rocksalt-Cr1-xScxN solid solutions are thermodynamically stable, and calculated DOS suggest the possibility for power-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 factors above that expected from the rule-of-mixture. These results corroborate the theoretical predictions and enable tailoring and understanding of structure-transport-property correlations of Cr1-xScxN.
Babanov, Yu.A., E-mail: babanov@imp.uran.ru [M.N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, Ekaterinburg 620990 (Russian Federation); Ponomarev, D.A.; Ustinov, V.V. [M.N. Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, Ekaterinburg 620990 (Russian Federation); Baranov, A.N. [M.V. Lomonosov Moscow State University, Moscow 119991 (Russian Federation); Zubavichus, Ya.V. [Russian Research Centre “Kurchatov Institute”, 123182 Moscow (Russian Federation)
2016-08-15
Highlights: • A method for determining bond lengths from combined EXAFS spectra for solid oxide solutions is proposed. • We have demonstrated a high resolution in r-space of close spacing atoms in the Periodical Table. • These results were obtained without any assumptions concerning interatomic distances for multi-component systems. • Coordinates ions for the solid solution with rock salt structure are determined. - Abstract: The regularization method of solving ill-posed problem is used to determine five partial interatomic distances on the basis of combined two EXAFS spectra. Mathematical algorithm and experimental results of the EXAFS analysis for Ni{sub c}Zn{sub 1−c}O (c = 0.0, 0.3, 0.5, 0.7, 1.0) solid solutions with the rock salt (rs) crystal structure are discussed. Samples were synthesized from the binary oxide powders at pressure of 7.7 GPa and temperatures 1450–1650 K. The measurements were performed using synchrotron facilities (Russian Research Centre “Kurchatov Institute”, Moscow). The Ni and Zn K absorption spectra were recorded in transmission mode under room temperature. It is shown, the ideal rock salt lattice is distorted and long-range order exists only in the average (Vegard law). In order to determine coordinates ions for the solid solution with rock salt structure, we used the Pauling model. The simulation is performed for 343,000 cluster of oxide ions. The distribution functions for ions (Ni−O, Ni−Ni, Ni−Zn, Zn−Zn, Zn−O, O−O) depending on the distance are obtained. The width of the Gaussian distribution function is determined by the difference of the radii of the metal ions. The results are consistent with the data both X-ray diffraction and the EXAFS spectroscopy.
High-Performance Hydrogen Evolution from MoS2(1-x) P(x) Solid Solution.
Ye, Ruquan; del Angel-Vicente, Paz; Liu, Yuanyue; Arellano-Jimenez, M Josefina; Peng, Zhiwei; Wang, Tuo; Li, Yilun; Yakobson, Boris I; Wei, Su-Huai; Yacaman, Miguel Jose; Tour, James M
2016-02-17
A MoS2(1-x) P(x) solid solution (x = 0 to 1) is formed by thermally annealing mixtures of MoS2 and red phosphorus. The effective and stable electrocatalyst for hydrogen evolution in acidic solution holds promise for replacing scarce and expensive platinum that is used in present catalyst systems. The high performance originates from the increased surface area and roughness of the solid solution.
Homogenization of. beta. -solid solution upon rapid heating of two-phase titanium alloys
Grudnev, V.N.; Zhuravlav, A.F.; Zhuravlev, B.F.; Ivasishin, O.M.; Markovskiy, P.E.
1985-01-01
High temperature ..beta.. phase homogenization during rapid heating was studied in a Ti-Mo alloy by mathematical simulation and experimental observation. The method used allows quantitative estimation of the influence of the two major factors determining development of the process of homogenization of the ..beta.. solid solution: heating rate and initial structure dispersion. Successive quenching of specimens from increasing temperatures in the ..beta.. area provides a simple and reliable method of observing the process of homogenization. This method allows experimental development of equations similar to those calculated for the ..beta.. solid solution area with minimum alloying element content. The experimental and calculated results are similar for a heating rate of 300/sup 0/K per second. Heating rate and initial structure dispersion are found to be quite significant in the Ti-10% Mo alloy studied. A method is suggested for estimating the concentration state of impoverished sectors of the ..beta.. solid solution in commercial alloys during rapid heating and used to analyze the inhomogenization. 8 references, 6 figures.
Structural study of nanocrystalline solid solution of Cu-Mo obtained by mechanical alloying
Aguilar, C., E-mail: claudio.aguilar@usm.cl [Departamento de Ingenieria Metalurgica y de Materiales, Universidad Tecnica Federico Santa Maria, Avenida Espana 1680, Valparaiso (Chile); Instituto de Materiales y Procesos Termomecanicos, Universidad Austral de Chile, General Lagos 2086, Valdivia (Chile); Castro, F. [Centro de Estudios e Investigaciones Tecnicas de Gipuzkoa, Paseo de Manuel Lardizabal, N Degree-Sign 15 20018, San Sebastian (Spain); Martinez, V. [TEKMETALL, Metallurgical Solutions S.L., Paseo neinor, Iribar Kalea 5, F1. B. de Igara 20018, San Sebastian (Spain); Guzman, D. [Departamento de Ingenieria en Metalurgia, Facultad de Ingenieria, Universidad de Atacama y Centro Regional de Investigacion y Desarrollo Sustentable de Atacama (CRIDESAT), Av. Copayapu 485, Copiapo (Chile); Cuevas, F. de las; Lozada, L.; Vielma, N. [Centro de Estudios e Investigaciones Tecnicas de Gipuzkoa, Paseo de Manuel Lardizabal, N Degree-Sign 15 20018, San Sebastian (Spain)
2012-06-30
Highlights: Black-Right-Pointing-Pointer Extension of solid solution in Cu-Mo system achieved by mechanical alloying. Black-Right-Pointing-Pointer X-ray characterization of Cu-Mo system processed by mechanical alloying. Black-Right-Pointing-Pointer Structural study of nanocrystalline solid solution of Cu-Mo obtained by mechanical alloying. - Abstract: This work studied the structural evolution of Cu-xMo (x = 5 and 8 wt.%) alloys processed by mechanical alloying using x-ray diffraction profiles, scanning electron microscopy, differential scanning calorimetric and microhardness. X-ray diffraction analysis was done using the modified Williamson-Hall and Warren-Averbach methods. These were used to determine structural properties, such as crystallite size, stacking fault probability and energy, dislocation density of metallic powder as a function of the amount of Mo and milling time. The main results obtained for both alloys were higher dislocation density and Vickers microhardness values were measured and crystallites sizes of around 10 nm were measured for both systems at 50 h of milling. Lattice defects increase the free energy and the free energy curves shift upwards, therefore the solubility limits change and Cu-Mo solid solution is formed.
Cluster-based composition rule for Laves phase-related BCC solid solution hydrogen storage alloys
WANG Qing; CHEN Feng; WU Jiang; QIANG Jianbing; DONG Chuang; ZHANG Yao; XU Fen; SUN Lixian
2006-01-01
A new cluster line approach for the composition rule of Laves phase-related BCC solid solution hydrogen-storage alloys was presented. The cluster line in a ternary phase diagram refers to a straight composition line linking a specific binary cluster to the third element. In the Laves phase-related BCC solid solution alloy system such as Ti-Cr-V, Ti-Cr tends to form binary Cr2Ti Laves phase while Ti-V and Cr-V to form solid solutions. This Laves phase is characterized by a close-packing icosahedral cluster Cr7Ti6. A cluster line Cr7Ti6-V is then constructed in this system. Alloy rods with a diameter of 3 mm of compositions along this line were prepared by copper-mould suction method. The alloy structure is found to vary with the V contents. Furthermore, the P-C-T measurements indicate that the cluster-line (Cr7Ti6)1-xVx alloys have large hydrogen storage capacities.
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.
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.
Zhou, Peng; Wang, Xin; Yan, Shicheng; Zou, Zhigang
2016-08-23
Decreasing the recombination of photogenerated carriers is a major challenge for efficiently converting solar energy into chemical energy by photocatalysis. Here, we have demonstrated that growth of a polar GaN:ZnO solid solution single crystal along its polarization axis is beneficial to efficient separation of photogenerated carriers, owing to the periodic potential barriers and wells generated from the periodically positive and negative atom arrangements in crystal structure. Local charge imbalance caused by replacing Ga(3+) with Zn(2+) leads to a polarization vector in the {0 0 0 1} planes of GaN:ZnO solid solution, thus forming a 1 D electron transport path along [2 1‾ 1‾ 0] in the {0 0 0 1} planes of GaN:ZnO solid solution to decrease recombination. Shorting the hole-transport distance by synthesizing porous nanoplates can further decrease recombination under the polarization field and improve the performance of polar photocatalyst in photoreduction of CO2 into CH4 .
Local structure in the disordered solid solution of cis- and trans-perinones.
Teteruk, Jaroslav L; Glinnemann, Jürgen; Heyse, Winfried; Johansson, Kristoffer E; van de Streek, Jacco; Schmidt, Martin U
2016-06-01
The cis- and trans-isomers of the polycyclic aromatic compound perinone, C26H12N4O2, form a solid solution (Vat Red 14). This solid solution is isotypic to the crystal structures of cis-perinone (Pigment Red 194) and trans-perinone (Pigment Orange 34) and exhibits a combined positional and orientational disorder: In the crystal, each molecular position is occupied by either a cis- or trans-perinone molecule, both of which have two possible molecular orientations. The structure of cis-perinone exhibits a twofold orientational disorder, whereas the structure of trans-perinone is ordered. 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 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 positions, but also the site occupancies and anisotropic displacement parameters.
Jebrail, Mais J; Renzi, Ronald F; Sinha, Anupama; Van De Vreugde, Jim; Gondhalekar, Carmen; Ambriz, Cesar; Meagher, Robert J; Branda, Steven S
2015-01-07
Digital microfluidics (DMF) is a powerful technique for sample preparation and analysis for a broad range of biological and chemical applications. In many cases, it is desirable to carry out DMF on an open surface, such that the matrix surrounding the droplets is ambient air. However, the utility of the air-matrix DMF format has been severely limited by problems with droplet evaporation, especially when the droplet-based biochemical reactions require high temperatures for long periods of time. We present a simple solution for managing evaporation in air-matrix DMF: just-in-time replenishment of the reaction volume using droplets of solvent. We demonstrate that this solution enables DMF-mediated execution of several different biochemical reactions (RNA fragmentation, first-strand cDNA synthesis, and PCR) over a range of temperatures (4-95 °C) and incubation times (up to 1 h or more) without use of oil, humidifying chambers, or off-chip heating modules. Reaction volumes and temperatures were maintained roughly constant over the course of each experiment, such that the reaction kinetics and products generated by the air-matrix DMF device were comparable to those of conventional benchscale reactions. This simple yet effective solution for evaporation management is an important advance in developing air-matrix DMF for a wide variety of new, high-impact applications, particularly in the biomedical sciences.
Yao, Wei; Yang, Dingfeng; Yan, Yanci; Peng, Kunling; Zhan, Heng; Liu, Anping; Lu, Xu; Wang, Guoyu; Zhou, Xiaoyuan
2017-03-17
High thermal conductivity of CoSbS-based limited its own prospect application in thermoelectric energy conversion. Solid solution is an effective approach to optimize the performance of thermoelectric materials with high lattice thermal conductivity because of the enhanced phonons scattering from disorder atoms. In this paper, we have synthesized and measured the thermoelectric properties of solid solution CoSbS1-xSex (x = 0, 0.05, 0.10, 0.15, 0.20, 0.30) series samples. The collaborative optimization (enhancing the power factors and reducing the thermal conductivities) to add zT values were realized via substitution of S atoms with the isoelectronic Se atoms in the matrix. Meanwhile, the lowest room temperature lattice thermal conductivity in CoSbS-based materials is obtained (4.72 W m(-1) K(-1)) at present. Benefiting from the results of synergistic strategy, a zT of 0.35 was achieved at 923 K for sample CoSbS0.85Se0.15, a 59% improvement as compared with that of the pristine CoSbS. Band calculation demonstrated that CoSbS0.85Se0.15 present a similar band dispersion with CoSbS. The mechanism of point defect scattering for reducing the lattice thermal conductivity at room temperature, was also analyzed by the Callaway model. The contributions to decrease the room temperature lattice thermal conductivity from the mass and the strain fluctuation in the crystal are comparable. These results can also be extended to other high-efficiency thermoelectric materials with stiff bond and smaller Gruneisen parameters.
Adya Prasad Mishra; T K Balasubramanian
2001-10-01
Rovibrational matrix elements of the multipole moments ℓ up to rank 10 and of the linear polarizability of the H2 molecule in the condensed phase have been computed taking into account the effect of the intermolecular potential. Comparison with gas phase matrix elements shows that the effect of solid state interactions is marginal.
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.
Numerical solutions of matrix Riccati equations for radiative transfer in a plane-parallel geometry
Chang, Hung-Wen; Wu, Tso-Lun
1997-01-01
In this paper, we conduct numerical experiments with matrix Riccati equations (MREs) which describe the reflection ( R) and transmission ( T) matrices of the specific intensities in a layer containing randomly distributed scattering particles. The theoretical formulation of MREs is discussed in our previous paper where we show that R and T for a thick layer can be efficiently computed by successively doubling R and T matrices for a thin layer (with small optical thickness 0959-7174/7/1/010/img1). We can compute 0959-7174/7/1/010/img2 and 0959-7174/7/1/010/img3 very accurately using either a fourth-order Runge - Kutta scheme or the fourth-order iterative solution. The differences between these results and those computed by the eigenmode expansion technique (EMET) are very small (< 0.1%). Although the MRE formulation cannot be extended to handle the inhomogeneous term (source term) in the differential equation, we show that the force term can be reformulated as an equivalent boundary condition which is consistent with MRE methods. MRE methods offer an alternative way of solving plane-parallel radiative transport problems. For large problems that do not fit into computer memory, the MRE method provides a significant reduction in computer memory and computational time.
Athanasios A. Pantelous
2010-01-01
Full Text Available In some interesting applications in control and system theory, linear descriptor (singular matrix differential equations of higher order with time-invariant coefficients and (non- consistent initial conditions have been used. In this paper, we provide a study for the solution properties of a more general class of the Apostol-Kolodner-type equations with consistent and nonconsistent initial conditions.
Salem Abdelmalek
2014-11-01
Full Text Available In this article we construct the invariant regions for m-component reaction-diffusion systems with a tridiagonal symmetric Toeplitz matrix of diffusion coefficients and with nonhomogeneous boundary conditions. We establish the existence of global solutions, and use Lyapunov functional methods. The nonlinear reaction term is assumed to be of polynomial growth.
Jian Liu
2015-09-01
Full Text Available Liquid–solid extrusion directly following vacuum infiltration (LSEVI is an infiltration–extrusion integrated forming technique, and transverse weld between upper residual magnesium alloy and magnesium matrix composites is a common internal defect, which can severely reduce the yield of composite products. To improve current understanding on the mechanism of transverse welding phenomenon, a thermo-mechanical numerical model of LSEVI for magnesium matrix composites was developed. The formation of transverse weld during extrusion was visualized using finite element simulation method, and the formation mechanism was discussed from the aspect of velocity field using a point tracking technique. The simulation results were verified by the experimental results in term of weld shape.
Eilmes, Andrzej; Kubisiak, Piotr
2008-09-18
The Polarizable Continuum Model has been used to study the effect of polymer matrix on Li (+) and Mg (2+) complexation in poly(ethylene oxide)-based solid electrolyte. Structures of complexes, stabilization energies, and vibrational frequencies are compared with corresponding vacuum values. The solvent effect of the polymer decreases with increasing cation coordination number. Optimized complex geometries do not differ significantly compared to vacuum calculations. Calculated shifts in vibrational frequencies depend on the complex structure; for hexacoordinated ion most frequencies are slightly red-shifted. The most important effect is the decrease of differences between relative stabilities of different structures in the solvent.
Portnoi, V. K.; Leonov, A. V.; Streletskii, A. N.; Logacheva, A. I.
2014-03-01
Solid solutions Ni(Al, Mo, C) are formed via milling the Ni2.8Al1Mo0.2 and Ni3Al0.8Mo0.2 and graphite-containing Ni2.8Al1Mo0.2C(0.25, 0.5) and Ni3Al0.8Mo0.2C(0.25, 0.5) mixtures. In this case, some amount of Mo remains beyond the solid solution. Graphite added to a starting mixture decreases the Mo solubility and favors the amorphization of solid solutions. The complete amorphization was found for the mixture with the 5 at % C and 5 at % Mo, which was added instead of Ni. The heating of mechanically synthesized (MS) powder alloys leads to the ordering of carbon-free and carbon-containing solid solutions with the formation of the L12 and E21 structure, respectively. In the course of the ordering of the Ni(Al, Mo, C) solid solutions, Mo and carbon precipitate in the form of the molybdenum carbide (Mo2C) second phase. The hardness of the MS three-phase Ni-Al-Mo-C solid solutions subjected to hot isostatic pressing is determined by the mass fraction of the formed Mo2C carbide. It is shown that the carbon content in the multicomponent antiperovskite can be estimated by analyzing the ratio of integral intensities of superlattice reflections I (100)/ I (110).
Luciani-Giacobbe, Laura C; Ramírez-Rigo, María V; Garro-Linck, Yamila; Monti, Gustavo A; Manzo, Ruben H; Olivera, María E
2017-01-01
One of the main obstacles to the successful treatment of tuberculosis is the poor and variable oral bioavailability of rifampicin (RIF), which is mainly due to its low hydrophilicity and dissolution rate. The aim of this work was to obtain a hydrophilic new material that allows a very fast dissolution rate of RIF and therefore is potentially useful in the development of oral solid dosage forms. The acid form of carboxymethylcellulose (CMC) was co-processed with RIF by solvent impregnation to obtain CMC-RIF powder, which was characterized by polarized optical microscopy, powder x-ray diffraction, DSC-TGA, hot stage microscopy, (13)C and (15)N solid-state NMR and FT-IR spectroscopy. In addition, the CMC-RIF matrices were subjected to water uptake and dissolution studies to assess hydrophilicity and release kinetics. CMC-RIF is a crystalline solid dispersion. Solid-state characterization indicated that no ionic interaction occurred between the components, but RIF crystallized as a zwitterion over the surface of CMC, which drastically increased the hydrophilicity of the solid. The CMC-RIF matrices significantly improved the water uptake of RIF and disintegrated in a very short period immediately releasing RIF. As CMC improves the hydrophilicity and delivery properties of RIF, CMC-RIF is very useful in the design of oral solid dosage forms with very fast dissolution of RIF, either alone or in combination with other antitubercular drugs. Copyright © 2016 Elsevier B.V. All rights reserved.
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2009-01-01
A series of diblock copolymers composed of methyl methacrylate and 2-perfluorooctylethyl methacry-late(PMMA144-b-PFMAn) with various PFMA block lengths were prepared by atom transfer radical po-lymerization(ATRP).The surface structures and properties of these polymers in the solid state and in solution were investigated using contact angle measurement,X-ray photoelectron spectroscopy(XPS),sum frequency generation(SFG) vibrational spectroscopy,surface tension and dynamic laser light scattering(DLS).It was found that with increasing PFMA block length,water and oil repellency de-creased,the ratio of F/C increased with increasing film depth,and the degree of ordered packing of the perfluoroalkyl side chains at the surface decreased.When the number of PFMA block units reached 10,PMMA segments were detected at the copolymer surface,which was attributed to the PFMA block length affecting molecular aggregation structure of the copolymer in the solution and the interfacial structure at the air/liquid interface,which in turn affects surface structure formation during solution solidification.The results suggest that copolymer solution properties play an important role in struc-ture formation on the solid surface.
NI HuaGang; XUE DongWu; WANG XiaoFang; ZHANG Wei; WANG XinPing; SHEN ZhiQuan
2009-01-01
A series of diblock copolymers composed of methyl methacrylate and 2-perfluorooctylethyl methacry-late (PMMA144-b-PFMAn) with various PFMA block lengths were prepared by atom transfer radical po-lymerization (ATRP). The surface structures and properties of these polymers in the solid state and in solution were investigated using contact angle measurement, X-ray photoelectron spectroscopy (XPS), sum frequency generation (SFG) vibrational spectroscopy, surface tension and dynamic laser light scattering (DLS). It was found that with increasing PFMA block length, water and oil repellency de-creased, the ratio of F/C increased with increasing film depth, and the degree of ordered packing of the perfluoroalkyl side chains at the surface decreased. When the number of PFMA block units reached 10, PMMA segments were detected at the copolymer surface, which was attributed to the PFMA block length affecting molecular aggregation structure of the copolymer in the solution and the interfacial structure at the air/liquid interface, which in turn affects surface structure formation during solution solidification. The results suggest that copolymer solution properties play an important role in struc-ture formation on the solid surface.
Buttini, Francesca; Miozzi, Michele; Balducci, Anna Giulia; Royall, Paul G; Brambilla, Gaetano; Colombo, Paolo; Bettini, Ruggero; Forbes, Ben
2014-04-25
Solution composition alters the dynamics of beclomethasone diproprionate (BDP) particle formation from droplets emitted by pressurised metered dose inhalers (pMDIs). The hypothesis that differences in inhaler solutions result in different solid particle physical chemistry was tested using a suite of complementary calorimetric techniques. The atomisation of BDP-ethanol solutions from commercial HFA-pMDI produced aerodynamically-equivalent solid particle aerosols. However, differences in particle physico-chemistry (morphology and solvate/clathrate formation) were detected by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and supported by hot stage microscopy (HSM). Increasing the ethanol content of the formulation from 8 to 12% (w/w), which retards the evaporation of propellant and slows the increase in droplet surface viscosity, enhanced the likelihood of particles drying with a smooth surface. The dissolution rate of BDP from the 12% (w/w) ethanol formulation-derived particles (63% dissolved over 120 min) was reduced compared to the 8% (w/w) ethanol formulation-derived particles (86% dissolved over 120 min). The addition of 0.01% (w/w) formoterol fumarate or 1.3% (w/w) glycerol to the inhaler solution modified the particles and reduced the BDP dissolution rate further to 34% and 16% dissolved in 120 min, respectively. These data provide evidence that therapeutic aerosols from apparently similar inhaler products, including those with similar aerodynamic performance, may behave non-equivalently after deposition in the lungs. Copyright © 2014 Elsevier B.V. All rights reserved.
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.
Mesnukul A
2009-01-01
Full Text Available The purpose of this study is to fabricate the polyethylene glycol matrix tablet by mold technique. Indomethacin and hydroxypropylmethylcellulose were used as model drug and polymer, respectively, in PEG matrix system. The physical and drug release characteristics of developed matrix tablet were studied. This inert carrier system comprising 7:3 polyethylene glycol 4000: polyethylene glycol 400 could effectively enhance the solubility of indomethacin and an addition of hydroxypropylmethylcellulose could sustain the drug release. Scanning electron microscope photomicrograph indicated the drug diffusion outward through the porous network of this developed matrix tablet into the dissolution fluid. Least square fitting the experimental dissolution data to the mathematical expressions (power law, first-order, Higuchi′s and zero-order indicated the drug release kinetics primarily as Fickian diffusion. Both the enhancement of drug dissolution and the prolongation of the drug release could be achieved for aqueous insoluble drug such as, indomethacin, by using polyethylene glycol-hydroxypropylmethylcellulose matrix system prepared with melting and mold technique.
A Study of Diffusivity in the BCC Solid Solution of Nb-Al and Nb-Ti-Al System
1990-01-01
A STUDY OF DIFFUSIVITY IN THE BCC SOLID SOLUTION OF Nb-Al AND Nb-Ti-Al SYSTEM P DTIC ELECTE NOV 3o01993 A- J.BY JOSE GUADALUPE LUIS RUIZ APARICIO A...analysis was employed for the evaluation of composition profiles in all the diffusion couples. Tne interdiffusion coefficient for the 0 solid solution of Nb...system suggest that Ti is the fastest element in the J0 solid solution . Qualitatively the penetration tendencies correlate with the melting point of
Decay property of regularity-loss type for solutions in elastic solids with voids
Djouamai, Leila
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.
From solid solution to cluster formation of Fe and Cr in α-Zr
Burr, P. A.; Wenman, M. R.; Gault, B.; Moody, M. P.; Ivermark, M.; Rushton, M. J. D.; Preuss, M.; Edwards, L.; Grimes, R. W.
2015-12-01
To understand the mechanisms by which the re-solution of Fe and Cr additions increase the corrosion rate of irradiated Zr alloys, the solubility and clustering of Fe and Cr in model binary Zr alloys was investigated using a combination of experimental and modelling techniques - atom probe tomography (APT), x-ray diffraction (XRD), thermoelectric power (TEP) and density functional theory (DFT). Cr occupies both interstitial and substitutional sites in the α-Zr lattice; Fe favours interstitial sites, and a low-symmetry site that was not previously modelled is found to be the most favourable for Fe. Lattice expansion as a function of Fe and Cr content in the α-Zr matrix deviates from Vegard's law and is strongly anisotropic for Fe additions, expanding the c-axis while contracting the a-axis. Matrix content of solutes cannot be reliably estimated from lattice parameter measurements, instead a combination of TEP and APT was employed. Defect clusters form at higher solution concentrations, which induce a smaller lattice strain compared to the dilute defects. In the presence of a Zr vacancy, all two-atom clusters are more soluble than individual point defects and as many as four Fe or three Cr atoms could be accommodated in a single Zr vacancy. The Zr vacancy is critical for the increased apparent solubility of defect clusters; the implications for irradiation induced microstructure changes in Zr alloys are discussed.
Carlos von Plessing Rossel
2000-12-01
Full Text Available Complexation between acyclovir (ACV, an antiviral drug used for the treatment of herpes simplex virus infection, and beta-cyclodextrin (beta-CD was studied in solution and in solid states. Complexation in solution was evaluated using solubility studies and nuclear magnetic resonance spectroscopy (¹H-NMR. In the solid state, X-ray diffraction, differential scanning calorimetry (DSC, thermal gravimetric analysis (TGA and dissolution studies were used. Solubility studies suggested the existence of a 1:1 complex between ACV and beta-CD. ¹H-NMR spectroscopy studies showed that the complex formed occurs with a stoichiometry ratio of 1:1. Powder X-ray diffraction indicated that ACV exists in a semicrystalline state in the complexed form with beta-CD. DSC studies showed the existence of a complex of ACV with beta-CD. The TGA studies confirmed the DSC results of the complex. Solubility of ACV in solid complexes was studied by the dissolution method and it was found to be much more soluble than the uncomplexed drug.
Luminescence properties of the Ca-alpha-sialon:Eu solid solution
Pawlik, Tomasz; Michalik, Daniel; Sopicka-Lizer, Malgorzata; Lisiecki, Radosław; Adamczyk, Barbara; Pławecki, Materusz; Mieszczak, Łukasz; Walerczyk, Wiktoria
2016-09-01
The Ca,Eu-α-sialon powders with the mixed solid solution composition have been manufactured via the solid-state reaction process in flowing nitrogen in a graphite furnace at a relatively low temperature of 1650 °C without an external overpressure. XRD data with Rielveld refinement and XPS measurements were used for characterization of the lattice constants and the surface chemical composition. The monophase Ca-Eu-α-sialon was obtained with the nominal composition of Eu0.048Ca0.702Si7.75Al2.25O0.75N15.25. The highest emission intensity in a yellow-orange region at 590 nm and quantum efficiency of 66% was found for this pure Ca,Eu-α-sialon. Estimation of m,n values from the lattice constant and EDS results showed a small deviation from the nominal composition of designed α-sialon. XPS results demonstrated significant changes of the chemical composition in the oxidized surface of phosphor particles. Possible reasons of emission redshift and relationship between the actual solid solution composition and luminescence properties are discussed in terms of simultaneous presence of Eu2+ and Eu3+ ions in the sialon crystal lattice and residual oxynitride glass.
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.
Long-term behavior of refractory thorium-plutonium dioxide solid solutions
Claparede, Laurent; Guigue, Mireille; Jouan, Gauthier; Nadah, Nassima; Dacheux, Nicolas; Moisy, Philippe
2017-01-01
The long-term behavior of Th0.87Pu0.13O2 was examined in nitric acid concentrations. The normalized dissolution rates after 3380 days, range from (1.4 ± 0.2) × 10-6 g m-2 d-1 in 5 M HNO3 down to (3.2 ± 0.4) × 10-8 g m-2 d-1 in 10-3 M HNO3, 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 HNO3, respectively. In such conditions, the time required to reach the full dissolution of the material varies from 430 years (5 M HNO3) to 18,000 years (10-3 M HNO3). 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.
Misochko, Eugenii Ya; Akimov, Alexander V; Belov, Vasilii A; Tyurin, Daniil A; Bubnov, Vyacheslav P; Kareev, Ivan E; Yagubskii, Eduard B
2010-08-21
The EPR spectrum of the Y@C(82) molecules isolated in solid argon matrix was recorded for the first time at a temperature of 5 K. The isotropic hyperfine coupling constant (hfcc) A(iso) = 0.12 +/- 0.02 mT on the nucleus (89)Y as derived from the EPR spectrum is found in more than two times greater than that obtained in previous EPR measurements in liquid solutions. Comparison of the measured hfcc on a metal atom with that predicted by density-functional theory calculations (PBE/L22) indicate that relativistic method provides good agreement between experiment in solid argon and theory. Analysis of the DFT calculated dipole-dipole hf-interaction tensor and electron spin distribution in the endometallofullerenes with encaged group 3 metal atoms Sc, Y and La has been performed. It shows that spin density on the scandium atom represents the Sc d(yz) orbital lying in the symmetry plane of the C(2v) fullerene isomer and interacting with two carbon atoms located in the para-position on the fullerene hexagon. In contrast, the configuration of electron spin density on the heavier atoms, Y and La, is associated with the hybridized orbital formed by interaction of the metal d(yz) and p(y) electronic orbitals.
Umari, A.M.; Gorelick, S.M.
1986-01-01
It is possible to obtain analytic solutions to the groundwater flow and solute transport equations if space variables are discretized but time is left continuous. From these solutions, hydraulic head and concentration fields for any future time can be obtained without ' marching ' through intermediate time steps. This analytical approach involves matrix exponentiation and is referred to as the Matrix Exponential Time Advancement (META) method. Two algorithms are presented for the META method, one for symmetric and the other for non-symmetric exponent matrices. A numerical accuracy indicator, referred to as the matrix condition number, was defined and used to determine the maximum number of significant figures that may be lost in the META method computations. The relative computational and storage requirements of the META method with respect to the time marching method increase with the number of nodes in the discretized problem. The potential greater accuracy of the META method and the associated greater reliability through use of the matrix condition number have to be weighed against this increased relative computational and storage requirements of this approach as the number of nodes becomes large. For a particular number of nodes, the META method may be computationally more efficient than the time-marching method, depending on the size of time steps used in the latter. A numerical example illustrates application of the META method to a sample ground-water-flow problem. (Author 's abstract)
Supramolecular stabilization of metastable tautomers in solution and the solid state.
Juribašić, Marina; Bregović, Nikola; Stilinović, Vladimir; Tomišić, Vladislav; Cindrić, Marina; Sket, Primož; Plavec, Janez; Rubčić, Mirta; Užarević, Krunoslav
2014-12-22
This work presents a successful application of a recently reported supramolecular strategy for stabilization of metastable tautomers in cocrystals to monocomponent, non-heterocyclic, tautomeric solids. Quantum-chemical computations and solution studies show that the investigated Schiff base molecule, derived from 3-methoxysalicylaldehyde and 2-amino-3-hydroxypyridine (ap), is far more stable as the enol tautomer. In the solid state, however, in all three obtained polymorphic forms it exists solely as the keto tautomer, in each case stabilized by an unexpected hydrogen-bonding pattern. Computations have shown that hydrogen bonding of the investigated Schiff base with suitable molecules shifts the tautomeric equilibrium to the less stable keto form. The extremes to which supramolecular stabilization can lead are demonstrated by the two polymorphs of molecular complexes of the Schiff base with ap. The molecules of both constituents of molecular complexes are present as metastable tautomers (keto anion and protonated pyridine, respectively), which stabilize each other through a very strong hydrogen bond. All the obtained solid forms proved stable in various solid-state and solvent-mediated methods used to establish their relative thermodynamic stabilities and possible interconversion conditions.
Pellizzoni, Elena; Ravalico, Fabio; Scaini, Denis; Delneri, Ambra; Rizzo, Roberto; Cescutti, Paola
2016-02-01
Bacteria usually grow forming biofilms, which are communities of cells embedded in a self-produced dynamic polymeric matrix, characterized by a complex three-dimensional structure. The matrix holds cells together and above a surface, and eventually releases them, resulting in colonization of other surfaces. Although exopolysaccharides (EPOLs) are important components of the matrix, determination of their structure is usually performed on samples produced in non-biofilm conditions, or indirectly through genetic studies. Among the Burkholderia cepacia complex species, Burkholderia cenocepacia is an important pathogen in cystic fibrosis (CF) patients and is generally more aggressive than other species. In the present investigation, B. cenocepacia strain BTS2, a CF isolate, was grown in biofilm mode on glass slides and cellulose membranes, using five growth media, one of which mimics the nutritional content of CF sputum. The structure of the matrix EPOLs was determined by 1H-NMR spectroscopy, while visualization of the biofilms on glass slides was obtained by means of confocal laser microscopy, phase-contrast microscopy and atomic force microscopy. The results confirmed that the type of EPOLs biosynthesized depends both on the medium used and on the type of support, and showed that mucoid conditions do not always lead to significant biofilm production, while bacteria in a non-mucoid state can still form biofilm containing EPOLs.
Matrix-Matched Iron-Oxide Laser Ablation ICP-MS U–Pb Geochronology Using Mixed Solution Standards
Liam Courtney-Davies; Zhiyong Zhu; Cristiana L. Ciobanu; Benjamin P. Wade; Nigel J. Cook; Kathy Ehrig; Cabral, Alexandre R.; Allen Kennedy
2016-01-01
U–Pb dating of the common iron-oxide hematite (α-Fe2O3), using laser-ablation inductively-coupled-plasma mass-spectrometry (LA-ICP-MS), provides unparalleled insight into the timing and processes of mineral deposit formation. Until now, the full potential of this method has been negatively impacted by the lack of suitable matrix-matched standards. To achieve matrix-matching, we report an approach in which a U–Pb solution and ablated material from 99.99% synthetic hematite are simultaneously m...
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)
Joule-Thomson Inversion in Vapor-Liquid-Solid Solution Systems
Nichita, Dan Vladimir; Pauly, Jerome; Daridon, Jean-Luc
2009-07-01
Solid phase precipitation can greatly affect thermal effects in isenthalpic expansions; wax precipitation may occur in natural hydrocarbon systems in the range of operating conditions, the wax appearance temperature being significantly higher (as high as 350 K) for hyperbaric fluids. Recently, methods for calculating the Joule-Thomson inversion curve (JTIC) for two-phase mixtures, and for three-phase vapor-liquid-multisolid systems have been proposed. In this study, an approach for calculating the JTIC for the vapor-liquid-solid solution systems is presented. The JTIC is located by tracking extrema and angular points of enthalpy departure variations versus pressure at isothermal conditions. The proposed method is applied to several complex synthetic and naturally occurring hydrocarbon systems. The JTIC can exhibit several distinct branches (which may lie within two- or three-phase regions or follow phase boundaries), multiple inversion temperatures at fixed pressure, as well as multiple inversion pressures at given temperature.
Kauranen, P. S.
1993-04-01
In the solid state concept of a direct methanol fuel cell (DMFC), methanol is directly oxidized at the anode of a solid polymer electrolyte fuel cell (SPEFC). Mathematical modelling of the transport and reaction phenomena within the electrodes and the electrolyte membrane is needed in order to get a closer insight into the operation of the fuel cell. In the work, macro-homogenous porous electrode and dilute solution theories are used to derive the phenomenological equations describing the transport and reaction mechanisms in a SPEFC single cell. The equations are first derived for a conventional H2/air SPEFC, and then extended for a DMFC. The basic model is derived in a one dimensional form in which it is assumed that species transport take place only in the direction crossing the cell sandwich. In addition, two dimensional descriptions of the catalyst layer are reviewed.
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.
2003-04-03
Strontium Titanate-Based Solid Solution Thin Films Deposited on Ceramic Substrates by Pulsed Laser Deposition DISTRIBUTION: Approved for public...Society H2.4 Microstructural and Electrical Characterization of Barium Strontium Titanate- based Solid Solution Thin Films Deposited on Ceramic...investigated and report the microstructural and electrical characterization of selected barium strontium titanate-based solid solution thin films
EXAFS STUDY OF THE SHORT RANGE STRUCTURE OF NANOCRYSTALLINE BCC-Fe80Cu20 SOLID SOLUTION
Y.Z. Yang; X.J. Bai; T.C. Kuang; G.M. Wang; S. Q. Wei
2002-01-01
The structure of bcc-Fe80 Cu2o solid solution produced by mechanical alloying of theelemental bcc-Fe and fcc-Cu powders has been studied using X-ray diffraction and theextended X-ray absorption fine structure (EXAFS) techniques. The disappearance ofelemental Fe and Cu X-ray diffraction (XRD) peaks and the presence of bcc structuralXRD peaks illustrate the formation of a nanocrystalline single-phase bcc-Fe80 Gu20solid solution. From the EXAFS results, the clear observation of Cu atoms taking onbcc coordination in the solid solution and Fe atoms remaining bcc structure furtherverifies the reality of atomic alloying between Fe and Cu atoms and the lattice changeof Cu from fcc to bcc. However, the supersaturated bcc solid solution is not chemicallyuniform, i.e., some regions are rich in Fe atoms and other regions rich in Cu atoms.
Leeuwenburgh, MA; Geurink, PP; Klein, T; Kauffman, HF; van der Marel, GA; Bischoff, R; Overkleeft, HS
2006-01-01
A novel solid-phase synthesis strategy toward succinylhydroxamate peptides, using an appropriately protected hydroxamate building block, is described. Rapid and efficient access is gained to amine-functionalized peptides, which can be decorated with, for instance, a fluorescent label. In addition, w
Xu, Ying; Chen, Yu
2015-07-01
The chelator [S,S]-ethylene diamine disuccinic acid, citric acid, and biosurfactant saponin are selected as leaching agents. In this study, the leaching effect of saponin mixed with either ethylene diamine disuccinic acid or citric acid on the levels of copper, zinc, lead, and cadmium in municipal solid waste incinerator fly ash is investigated. Results indicate that saponin separately mixed with ethylene diamine disuccinic acid and citric acid exhibits a synergistic solubilisation effect on copper, zinc, lead, and cadmium leaching from fly ash. However, saponin and ethylene diamine disuccinic acid mixed solution exhibits a synergistic solubilisation effect that is superior to that of a saponin and citric acid mixed solution. The extraction rate of heavy metal in fly ash leached with a saponin and chelator mixed solution is related to the pH of the leaching solution, and the optimal range of the pH is suggested to be approximately neutral. After leaching with a saponin and chelator mixed solution, copper, zinc, lead, and cadmium contents significantly decreased (p < 0.05) in the extractable or acid-soluble and reducible fractions. By adopting the proposed approach, the leaching concentrations of copper, zinc, lead, and cadmium in treated fly ash are in accordance with Standard for Pollution Control on the Security Landfill Site for Hazardous Wastes GB18598-2001.
薛强; 梁冰; 刘晓丽; 李宏艳
2003-01-01
The process of contaminant transport is a problem of multicomponent and multiphase flow in unsaturated zone. Under the presupposition that gas existence affects water transport , a coupled mathematical model of contaminant transport in unsaturated zone has been established based on fluid-solid interaction mechanics theory. The asymptotical solutions to the nonlinear coupling mathematical model were accomplished by the perturbation and integral transformation method. The distribution law of pore pressure,pore water velocity and contaminant concentration in unsaturated zone has been presented under the conditions of with coupling and without coupling gas phase. An example problem was used to provide a quantitative verification and validation of the model. The asymptotical solution was compared with Faust model solution. The comparison results show reasonable agreement between asymptotical solution and Faust solution, and the gas effect and media deformation has a large impact on the contaminant transport. The theoretical basis is provided for forecasting contaminant transport and the determination of the relationship among pressure-saturation-permeability in laboratory.
Sinigoi, Loris; Bravin, Paola; Ebert, Cynthia; D'Amelio, Nicola; Vaccari, Lisa; Ciccarelli, Laura; Cantone, Sara; Basso, Alessandra; Gardossi, Lucia
2009-01-01
Porous and rigid methacrylic Synbeads were optimized and applied efficiently to the solid phase peptide synthesis with the objective of improving significantly volumetric yields (0.33 mol/L calculated on the basis of maximum chemical accessibility, i.e. the maximum number of functional groups that can be acylated by FmocCl) as compared to swelling commercial polymers (from 0.06 to 0.12 mol/L). The effects of the density of functional groups and spacer length were investigated obtaining a chemical accessibility of the functional groups up to 1 mmol/g(dry). High resolution magic angle spinning (HR-MAS) was exploited to evidence the presence of "solution-like" flexible linkers anchored on the rigid methacrylic backbone of Synbeads and to study the degree of functionalization by the Wang linker. To demonstrate the efficiency of the optimized Synbeads, the peptides Somatostatin and Terlipressin were synthesized. In the case of Somatostatin, final synthetic yields of 45 and 60% were achieved by following the HCTU/DIPEA and DIC/HOBt routes respectively, with the HPLC purity always higher than 83%. In the case of Terlipressin, the synthesis was carried out in parallel on Synbeads and also on TentaGel, ChemMatrix, and PS-DVB for comparison (DIC/HOBt route). The profiles describing the synthetic efficiency demonstrated that Synbeads leads to synthetic efficiency (86%) comparable to PS-DVB (96%) or ChemMatrix (84%). In order to gain a more precise picture of chemical and morphological features of Synbeads, their matrix was also characterized by exploiting innovative approaches based on FTIR microspectroscopy with a conventional source and with synchrotron radiation. A uniform distribution of the functional groups was evidenced through a detailed chemical mapping.
Chen-fan YU; Zheng-liang XUE; Wu-tao JIN
2016-01-01
The properties of titanium carbonitride Ti(Cx N1-x )inclusions precipitated during solidification of tire cord steels and the thermodynamic conditions for their decomposition and solid solution during billet heating were investigated using a thermodynamics method.The solid solution of Ti(Cx N1 -x )inclusions during high-temperature heating was also studied experimentally.The results revealed that:(1)the higher the content of carbon in the tire cord steel is, the greater the value of x in the Ti(Cx N1 -x )inclusions is;(2)the higher the content of carbon in the tire cord steel is,the earlier the Ti(Cx N1 -x )inclusions precipitated during the solidification process and the lower the solidification front temperature is during precipitation;(3)when an 82A steel sample was heated to 1 087 ℃,the Ti(Cx N1 -x )in-clusions possess the thermodynamic conditions of decomposition and solid solution;and (4)when 82A samples were heated to 1 1 50 and 1 250 ℃,the total number of Ti(Cx N1 -x )inclusions larger than 5 μm in diameter decreased by 55.0% and 70.3%,respectively.In addition,although smaller inclusions with diameter less than 2 μm continued to decompose when the sample was heated at 1 250 ℃ for 2 h and then cooled to 1 000 ℃ in the furnace,the number of inclusions larger than 5 μm in diameter increased.
Cui, Yajuan [College of Architecture and Environment, Sichuan University, Chengdu 610065, Sichuan (China); Fang, Ruimei; Shang, Hongyan [College of Chemical Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Shi, Zhonghua; Gong, Maochu [Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, Sichuan (China); Center of Engineering of Vehicular Exhaust Gases Abatement, Chengdu 610064, Sichuan (China); Center of Engineering of Environmental Catalytic Material, Chengdu 610064, Sichuan (China); Chen, Yaoqiang, E-mail: nic7501@scu.edu.cn [College of Architecture and Environment, Sichuan University, Chengdu 610065, Sichuan (China); College of Chemical Engineering, Sichuan University, Chengdu 610064, Sichuan (China); Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, Sichuan (China); Center of Engineering of Vehicular Exhaust Gases Abatement, Chengdu 610064, Sichuan (China); Center of Engineering of Environmental Catalytic Material, Chengdu 610064, Sichuan (China)
2015-04-15
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{sub 2}-temperature programmed reduction (H{sub 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{sup 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.
SOLID SOLUTION CARBIDES ARE THE KEY FUELS FOR FUTURE NUCLEAR THERMAL PROPULSION
Panda, Binayak; Hickman, Robert R.; Shah, Sandeep
2005-01-01
Nuclear thermal propulsion uses nuclear energy to directly heat a propellant (such as liquid hydrogen) to generate thrust for space transportation. In the 1960 s, the early Rover/Nuclear Engine for Rocket Propulsion Application (NERVA) program showed very encouraging test results for space nuclear propulsion but, in recent years, fuel research has been dismal. With NASA s renewed interest in long-term space exploration, fuel researchers are now revisiting the RoverMERVA findings, which indicated several problems with such fuels (such as erosion, chemical reaction of the fuel with propellant, fuel cracking, and cladding issues) that must be addressed. It is also well known that the higher the temperature reached by a propellant, the larger the thrust generated from the same weight of propellant. Better use of fuel and propellant requires development of fuels capable of reaching very high temperatures. Carbides have the highest melting points of any known material. Efforts are underway to develop carbide mixtures and solid solutions that contain uranium carbide, in order to achieve very high fuel temperatures. Binary solid solution carbides (U, Zr)C have proven to be very effective in this regard. Ternary carbides such as (U, Zr, X) carbides (where X represents Nb, Ta, W, and Hf) also hold great promise as fuel material, since the carbide mixtures in solid solution generate a very hard and tough compact material. This paper highlights past experience with early fuel materials and bi-carbides, technical problems associated with consolidation of the ingredients, and current techniques being developed to consolidate ternary carbides as fuel materials.
Ab Initio Calculations and Synthesis of Sc2InC-Y2InC Solid Solution
2010-02-03
tribological materials. It will study a solid solution of this fascinating new class of nanolaminated materials using both theoretical and experimental means...Sc2InC-Y2InC solid solution using ab initio calculations and 2) to synthesize Sc2InC-Y2InC thin films using magnetron sputtering and to determine the correlation between composition, structure, and mechanical properties thereof.
PZT-like structural phase transitions in the BiFeO3-KNbO3 solid solution.
Lennox, Robert C; Taylor, Daniel D; Vera Stimpson, Laura J; Stenning, Gavin B G; Jura, Marek; Price, Mark C; Rodriguez, Efrain E; Arnold, Donna C
2015-06-21
Despite the high prominence of the perovskites BiFeO(3) and KNbO(3) the solid solution between the two has received little attention. We report a detailed neutron and synchrotron X-ray powder diffraction, and Raman spectroscopy study which demonstrates an R3c→P4mm→Amm2 series of structural phase transitions similar to that exhibited by the PbZrO(3)-PbTiO(3) solid solution.
Neutron diffraction studies on Ca1-BaZr4P6O24 solid solutions
S N Achary; O D Jayakumar; S J Patwe; A B Shinde; P S R Krishna; S K Kulshreshtha; A K Tyagi
2008-11-01
Herein we report the results of detailed crystallographic studies of Ca1-BaZr4P6O24 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 the systematic variation of unit cell parameters. The variation of unit cell parameters with the composition indicates decreasing trend in parameter with increasing Ba2+ concentration contrast to an increasing trend in parameter.
NMR in Chevrel-phase solid solution Mo 6Se 8- xTe x
Hamard, C.; Le Floch, M.; Peña, O.; Wojakowski, A.
1999-01-01
The Mo 6Se 8-Mo 6Te 8 solid solution was studied by X-ray diffraction, magnetic susceptibility and 77Se and 125Te NMR. Dynamic studies show that substitution occurs differently when Se replaces Te in Mo 6Te 8 than when Te replaces Se in Mo 6Se 8. Selenium first fills the high-symmetry sites and then it becomes statistically distributed on the 6f positions of the R3¯ symmetry. In the second case, Te occupies randomly the 8 X sites of the Mo 6X 8 structure, creating large perturbations of the 125Te NMR spectra over the whole range of x.
Structural and optical properties of AlN grown by solid source solution growth method
Kangawa, Yoshihiro; Suetsugu, Hiroshige; Knetzger, Michael; Meissner, Elke; Hazu, Kouji; Chichibu, Shigefusa F.; Kajiwara, Takashi; Tanaka, Satoru; Iwasaki, Yosuke; Kakimoto, Koichi
2015-08-01
Structural and optical properties of AlN grown on AlN(0001) by the solid source solution growth (3SG) method were investigated. Transmission electron microscopy (TEM) analysis revealed that the geometrical relationship between the growth directions and slip planes influenced the dislocation propagation behaviors and annihilation mechanisms. Panchromatic and monochromatic images in the cathodoluminescence (CL) spectrum further revealed that C impurities were segregated near the surface, while Al vacancies were widely distributed in the AlN/AlN(0001) grown using the 3SG method.
Study of Microwave Absorbing Performances of Nanometer Fe-Al Solid solution
Xiaohui Wang; Xiaoping Liang; Shaobo Xin
2006-01-01
In this paper, Fe-Al solid solution was prepared by mechanical alloying technology, and Fe-Al powder was dispersed into unsaturated polyester (UP) with different contents as absorber to form mixture Fe-Al-UP. The results indicate that the alloying process is almost accomplished and most of the particles are nanometer. Meanwhile, the microwave absorbability of Fe-Al-UP samples in frequency from 0.3 MHz to 1.5 GHz was studied. The results indicate that the more the absorber, the better the absorbing property. The absorbing property of Fe-50Al-UP was slightly higher than Fe-28Al-UP.
Photovoltaic properties of Zr(x)Ti(1-x)O2 solid solution nanowire arrays.
Gu, Xuehui; Liu, Guohua; Zhang, Min; Zhang, Haifeng; Zhou, Jingran; Guo, Wenbin; Chen, Yu; Ruan, Shengping
2014-05-01
In this paper, Zr(0.05Ti(0.95)O2 solid solution nanowire arrays (NWs) were prepared by a low temperature hydrothermal method. The as-prepared NWs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-visible (UV-vis) spectroscopy. With the doping of Zr content, the band gap of the composite can be varied in a wide range and excellent photoelectric properties of the arrays could be obtained. Moreover, a preliminary study on the photoelectric properties was conducted, which indicates potential applications of the arrays for fabricating high performance ultraviolet photodetectors.
The application of Ce-Zr oxide solid solution to oxygen storage promoters in automotive catalysts
Ozawa, Msakuni (Toyota Central Research and Development Labs. Inc., Aichi (Japan)); Kimura, Mareo (Toyota Central Research and Development Labs. Inc., Aichi (Japan)); Isogai, Akio (Toyota Central Research and Development Labs. Inc., Aichi (Japan))
1993-03-15
The complex oxides in the CeO[sub 2]-ZrO[sub 2] system were examined for the improvement of oxygen storage capacity in automotive catalysts. The formation of Ce-Zr oxide solid solution improved the thermal stability and activity of CeO[sub 2]. The Ce-Zr addition enhanced the removal activity for CO, NO[sub x] and hydrocarbons under dynamic air-fuel ratio condition. The automotive catalyst was designed and developed through research on the oxides in the CeO[sub 2]-ZrO[sub 2] system. (orig.)
Methods of deoxygenating metals having oxygen dissolved therein in a solid solution
Zhang, Ying; Fang, Zhigang Zak; Sun, Pei; Xia, Yang; Zhou, Chengshang
2017-06-06
A method of deoxygenating metal can include forming a mixture of: a metal having oxygen dissolved therein in a solid solution, at least one of metallic magnesium and magnesium hydride, and a magnesium-containing salt. The mixture can be heated at a deoxygenation temperature for a period of time under a hydrogen-containing atmosphere to form a deoxygenated metal. The deoxygenated metal can then be cooled. The deoxygenated metal can optionally be subjected to leaching to remove by-products, followed by washing and drying to produce a final deoxygenated metal.
Synthesis and Characterization of Nanocapsules of α-Fe(NiCoAl) Solid-solution
Dianyu GENG; J.C. Kim; C.J. Choi; Chonglin CHEN; Xinguo ZHAO; Zhidong ZHANG
2005-01-01
α-Fe(NiCoAl) solid-solution nanocapsules were prepared with pure powders of Fe, Ni, Co and Al by the plasma arc-discharging using a copper crucible. The shapes of the nanocapsules are in polyhedrons with the core/shell structure. The body centered cubic (BCC) phase is formed in the core. The size of the nanocapsules is in the range of 10～120 nm and the thickness of the shell is 4～11 nm. Saturation magnetization Js=150 Am2/kg and coercivity iHC=24.3 kA/m are achieved for the nanocapsules.
Matrix-Matched Iron-Oxide Laser Ablation ICP-MS U–Pb Geochronology Using Mixed Solution Standards
Liam Courtney-Davies
2016-08-01
Full Text Available U–Pb dating of the common iron-oxide hematite (α-Fe2O3, using laser-ablation inductively-coupled-plasma mass-spectrometry (LA-ICP-MS, provides unparalleled insight into the timing and processes of mineral deposit formation. Until now, the full potential of this method has been negatively impacted by the lack of suitable matrix-matched standards. To achieve matrix-matching, we report an approach in which a U–Pb solution and ablated material from 99.99% synthetic hematite are simultaneously mixed in a nebulizer chamber and introduced to the ICP-MS. The standard solution contains fixed U- and Pb-isotope ratios, calibrated independently, and aspiration of the isotopically homogeneous solution negates the need for a matrix-matched, isotopically homogenous natural iron-oxide standard. An additional advantage of using the solution is that the individual U–Pb concentrations and isotope ratios can be adjusted to approximate that in the unknown, making the method efficient for dating hematite containing low (~10 ppm to high (>1 wt % U concentrations. The above-mentioned advantage to this solution method results in reliable datasets, with arguably-better accuracy in measuring U–Pb ratios than using GJ-1 Zircon as the primary standard, which cannot be employed for such low U concentrations. Statistical overlaps between 207Pb/206Pb weighted average ages (using GJ-1 Zircon and U–Pb upper intercept ages (using the U–Pb mixed solution method of two samples from iron-oxide copper-gold (IOCG deposits in South Australia demonstrate that, although fractionation associated with a non-matrix matched standard does occur when using GJ-1 Zircon as the primary standard, it does not impact the 207Pb/206Pb or upper intercept age. Thus, GJ-1 Zircon can be considered reliable for dating hematite using LA-ICP-MS. Downhole fractionation of 206Pb/238U is observed to occur in spot analyses of hematite. The use of rasters in future studies will hopefully minimize
Effect of doping elements on catalytic performance of CeO2-ZrO2 solid solutions
LI Mei; LIU Zhaogang; HU Yanhong; WANG Mitang; LI Hangquan
2008-01-01
CeZr, CeYZr, LaCeZr, LaCePrZr, LaCePrYZr, and LaCePr solid solutions were prepared via the coprecipitation method, and characterized by means of X-Ray Diffraction (XRD) and Brunauer-Emmett-Teller (BET) techniques. The oxygen storage capacity (OSC) of the solid solutions was evaluated by the pulse technique and the catalytic activity was assessed using a 4-channel catalysis device. It was seen that the solid solutions presented cubic structure. The specific surface area and thermal stability could be enhanced by doping Y into the solid solutions. Doping a small amount of La had a positive effect on the thermal durability while doping a large amount of La decreased the specific surface area and the thermal stability. LaCePrZr and LaCePrYZr solid solutions synthesized using Baotou rare earth mineral residue enriched with LaCePr after Nd extraction presented a certain higher value in specific surface area and thermal stability, thereby enabling to be used as economic catalysts for automobile exhaust purification. Coating Al2O3 or SiO2 layer on the surface of ceria-zirconia solid solutions increased the specific surface area and thermal resistance.
Soares, Karina Lotz; Cerqueira, Maristela Barnes Rodrigues; Caldas, Sergiane Souza; Primel, Ednei Gilberto
2017-09-01
This study describes the development, optimization and validation of a method for the extraction of 15 pesticides of different chemical classes in drinking water treatment sludge (DWTS) by vortex-assisted Matrix Solid Phase Dispersion (MSPD) with determination by gas chromatography coupled to mass spectrometry. It focused on the application of alternative and different solid supports to the extraction step of the MSPD. The main parameters that influenced the extraction were studied in order to obtain better recovery responses. Recoveries ranged from 70 to 120% with RSD below 20% for all analytes. Limits of quantification (LOQ) of the method ranged from 5 to 500 μg kg(-1) whereas the analytical curves showed correlation coefficients above 0.997. The method under investigation used low volume of solvent (5 mL), low sample mass (1.5 g) and low mass of chitin (0.5 g), an environmentally friendly support. It has advantages, such as speed, simplicity and low cost material, over other methods. When the method was applied, 4 out of 15 pesticides were detected in the DWTS samples in concentrations below the LOQ. Copyright © 2017 Elsevier Ltd. All rights reserved.
Continuous supercritical synthesis and dielectric behaviour of the whole BST solid solution
Reveron, H; Elissalde, C; Aymonier, C; Bousquet, C; Maglione, M; Cansell, F [Institut de Chimie de la Matiere Condensee de Bordeaux (ICMCB), CNRS-UPR 9048, Bordeaux I University, 87, avenue du Dr Schweitzer, 33608 PESSAC Cedex (France)
2006-07-28
In this study we show that pure and well crystallized nanoparticles of Ba{sub x}Sr{sub 1-x}TiO{sub 3} (BST) can be synthesized over the entire range of composition through the hydrolysis and further crystallization of alkoxide precursors under supercritical conditions. To our knowledge, this is the first time that the whole ferroelectric solid solution has been produced in a continuous way, using the same experimental conditions. The composition of the powder can be easily controlled by adjusting the feed solution composition. The powders consist of soft-aggregated monocrystalline nanoparticles with an average particle size ranging from {approx}20 to 40 nm. Ferroelectric ceramics with accurately adjustable Curie temperature (100-390 K) can thus be obtained by sintering.
Yeh, H. C.; Sanders, W. A.; Fiyalko, J. L.
1975-01-01
Stirred-ball-mill-blended Si3N4 and Al2O3 powders were pressure sintered in order to investigate the mechanism of solid solution formation and densification in the Si3N4-Al2O3 system. Powder blends with Si3N4:Al2O3 mole ratios of 4:1, 3:2, and 2:3 were pressure sintered at 27.6-MN/sq m pressure at temperatures to 17000 C (3090 F). The compaction behavior of the powder blends during pressure sintering was determined by observing the density of the powder compact as a function of temperature and time starting from room temperature. This information, combined with the results of X-ray diffraction and metallographic analyses regarding solutioning and phase transformation phenomena in the Si3N4-Al2O3 system, was used to describe the densification behavior.
Adaptation response of Pseudomonas fragi on refrigerated solid matrix to a moderate electric field
Chen, Wenbo; HU, HONGHAI; Zhang, Chunjiang; HUANG, Feng; Zhang, Dequan; Zhang, Hong
2017-01-01
Background Moderate electric field (MEF) technology is a promising food preservation strategy since it relies on physical properties—rather than chemical additives—to preserve solid cellular foods during storage. However, the effectiveness of long-term MEF exposure on the psychrotrophic microorganisms responsible for the food spoilage at cool temperatures remains unclear. Results The spoilage-associated psychrotroph Pseudomonas fragi MC16 was obtained from pork samples stored at 7 °C. Continu...
LIN Xiao-Min; LI,Li-Ping; LI,Guang-She; SU,Wen-Hui
2001-01-01
Ce1-xNdx O2-δ(x = 0.05-0. 55) solid solutions prepared by sol-gel route were crystallized in a cubic fluorite structure. The solid limit was determined to be as high as x = 0.45. Ra man spectra of the solid solutions with lower composition ex hibited only one band, which was assigned to F2g mode. In creasing composition produced broad and asymmetric F2g mode with an appearance of low frequency tail. The new broad peak observed at higher frequency side of the F2g mode associated with the oxygen vacancy in the lattice. The impedance spectra of the solid solutions showed definitely ionic conduction, and Ce0.80 Nd0.20 O2-δ solid solution possessed a maximum conductivity. At 500℃, the conductivity and acti vation energy were 2.65 × 10-3S/cm and 0.82 eV, respectively.
Alex, K.; Mclellan, R. B.
1971-01-01
A previous calculation of the thermodynamic properties of interstitial solid solutions based on the technique of Kirkwood expansions has been extended to include the effects of second nearest neighbor solute atom mutual interactions. The error inherent in the first order (or quasi-chemical) counting of the degeneracy of the solution crystal is avoided. It is shown that, at high temperatures, even strong second nearest neighbor solute mutual interactions have a negligible effect on the entropy of the solution and a small, temperature-dependent effect on the solute partial enthalpy.
Spectroscopic study of mimetite-vanadinite solid solution series - preliminary results
Janicka, Urszula; Bajda, Tomasz; Topolska, Justyna; Manecki, Maciej
2014-05-01
Mimetite Pb5(AsO4)3Cl and vanadinite Pb5(VO4)3Cl are minerals from the Pb-apatites family which belong to the apatite supergroup. Most often they crystalize under hypergenic conditions, in oxidation zones of Pb ore deposits, where they form paragenesis with pyromorphite Pb5(PO4)3Cl. These minerals are used in the techniques of soils reclamation. Their crystal structure allows substituting of metal cations as well as of anionic complexes. Natural mimetite often contains admixture of phosphates and/or vanadates. Similarly, vanadinite contains admixtures of phosphates and/or arsenates. Among the lead apatites, properties of the minerals from pyromorphite-mimetite solid solution series are well known, while the knowledge about the mimetite-vanadinite series is incomplete. The aim of this research was synthesis and spectroscopic characterization of mimetite-vanadinite solid solution series. Mimetite, vanadinite and their solid solution were synthesized from aqueous solutions by dropwise mixing of Pb(NO3)2, Na3VO4, Na2HAsO4×7H2O and NaCl at 25 ºC and pH = 3.5. Products of the syntheses were analyzed by X-Ray diffraction (XRD), Infrared absorption spectroscopy (FTIR) and Raman spectroscopy. The precipitates formed in the syntheses were identified by the XRD method as mimetite, vanadinite and their solid solutions. Other crystalline phases were not present in synthetic precipitates within the detection limit of XRD. In the Mid-IR spectra of mimetite-vanadinite solid solutions series, bands characteristic for vibrations of As-O bonds of the AsO4 tetrahedra and vibrations of V-O bonds of the VO4 tetrahedra were observed. The band corresponding to stretching ν3vibrations of AsO4 and VO4 occured in the range 700-900 cm-1. In the Raman spectra, bands which are characteristic for vibrations of As-O bonds of the AsO4 tetrahedra and vibrations of V-O bonds of the VO4 tetrahedra were also observed. The bands attributed to vibrations in the AsO4 tetrahedra appeared at 880-740 cm
Kangawa, Yoshihiro; Kusaba, Akira; Sumiyoshi, Hiroaki; Miyake, Hideto; Boćkowski, Michał; Kakimoto, Koichi
2015-06-01
Interfacial phenomena at the liquid/solid interface under high temperatures were observed in real time to understand the growth process of AlN during solid-source solution growth. In this study, we used an AlN/α-Al2O3 template as the substrate; these wide-bandgap materials made the substrate transparent to visible light. Therefore, we observed the morphology of the liquid/solid interface through the template from the bottom. In this investigation, a polycrystal formed because of melt-back etching during the initial stage of growth; nevertheless, we succeeded in obtaining real-time images of interfacial phenomena.
Grate, Jay W.; Gonzalez, Jhanis J.; O' Hara, Matthew J.; Kellogg, Cynthia M.; Morrison, Samuel S.; Koppenaal, David W.; Chan, George C.; Mao, Xianglei; Zorba, Vassilia; Russo, Richard
2017-09-08
Laser ablation (LA) is a means of sample introduction to inductively coupled plasma (ICP) mass spectrometry (MS) that avoids acid dissolution and chemical separation steps conventionally associated with solid sample analysis. At the same time, certain features of LA-ICP-MS are often mentioned in critical reviews including solid matrix variability and its influence on the ablation process, matrix dependent elemental fractionation, lack of matrix matched standards for external calibration, and limitations to internal calibration because it is challenging to add and distribute spikes into solid samples. In this paper we introduce the concept of a synergistic minimal sample preparation method that is used in combination with LA-ICP-MS as a means to overcome these limitations. The aim of this minimal sample preparation procedure is to reactively transform the original matrix to a more consistent matrix for LA-based analysis, thus reducing the effects of matrix variability, while enabling the addition of tracers. In conjunction with ICP-MS, we call this MTR-LA-ICP-MS, where MTR is derived from matrix transformation including the option to add tracers
Coreño-Alonso, O.; Coreño-Alonso, J.
2015-01-01
The possibility of solid solution formation in high entropy alloys (HEAs) has been calculated for alloys with four to seven elements, using a rule previously reported. Thirty elements were included: transition elements of the fourth, fifth and sixth periods of the periodic table, and aluminum. A total of 2,799,486 systems were analyzed. The percentage of solid solutions that would be formed in HEAs decreases from 35.9% to 26.4%, as the number of elements increases from four to seven. The stru...
Optimizing the formation of solid solutions with components of different shapes
Escobedo, Fernando A.
2017-04-01
A key challenge to engineer ordered solids from the co-assembly of two differently shaped building blocks is to predict the key particle characteristics that lead to maximal mutual ordered-phase compatibility (MaxOC). While both entropy disparity, as captured by the relative size of the components, and energetic inter-species selectivity affect MaxOC, it is the former whose effect is less intuitive and the main focus of this work. Such MaxOC predictive rules are formulated and validated by using Monte Carlo simulation results for hard-core mixtures of octahedra and spheres and of other previously studied mixtures. Specifically, it is proposed that component size ratios should maximize their "substitutional symmetry" and hence minimize the combined free-energy cost associated with mutating a host-particle into a guest-particle in each of the solid phases. For the hard-core mixtures examined, packing entropy stabilizes substitutionally disordered solid solutions but not stoichiometric compounds. Additional molecular simulations were hence used to demonstrate, consistent with recent experimental findings, that such compounds can be formed by strengthening the inter-species compatibility via orientation-dependent attractions.
Matrix solution for the wall impedance of infinitely long multilayer circular beam tubes
H. Hahn
2010-01-01
Full Text Available The coupling impedance of beam tubes is a long-standing important topic for particle accelerators that many authors have addressed. The present study was initiated in view of a specific problem, but its novel approach is broadly applicable to the longitudinal and transverse coupling impedances of coated beam tubes or multilayer tubes. The matrix method presented here derives the wall impedance by treating the radial wave propagation of the beam-excited electromagnetic fields in full analogy to longitudinal transmission lines. Starting from the Maxwell equations, the radially transverse magnetic field components are described for monopole and dipole modes by a 2×2 matrix. Assuming isotropic material properties within one layer, the transverse field components at the inner boundary of a layer uniquely are determined by matrix transfer of the field components at its outer boundary. By imposing power-flow constraints on the matrix, wave impedance mapping and field matching between layers is enforced and replaced by matrix multiplication. The longitudinal and transverse coupling impedances are derived from the wall impedance at the innermost boundary, and the different procedures for its determination are discussed. The matrix method is demonstrated via selected yet representative examples of the well-documented cases of a stainless-steel tube, and of a graphite collimator.
CO oxidation on Ta-Modified SnO2 solid solution catalysts
Han, Xue; Xu, Xianglan; Liu, Wenming; Wang, Xiang; Zhang, Rongbin
2013-06-01
Co-precipitation method was adopted to prepare Sn-Ta mixed oxide catalysts with different Sn/Ta molar ratios and used for CO oxidation. The catalysts were investigated by N2-Brunauer-Emmett-Teller (N2-BET), X-ray diffraction patterns (XRD), H2-temperature programmed reduction (H2-TPR), Thermal Gravity Analysis - Differential Scanning Calorimetry (TGA-DSC) techniques. It is revealed that a small amount of Ta cations can be doped into SnO2 lattice to form solid solution by co-precipitation method, which resulted in samples having higher surface areas, improved thermal stability and more deficient oxygen species on the surface of SnO2. As a result, those Sn rich Sn-Ta solid solution catalysts with an Sn/Ta molar ratio higher than 4/2 showed significantly enhanced activity as well as good resistance to water deactivation. It is noted here that if tantala disperses onto SnO2 surface instead of doping into its lattice, it will then have negative effect on its activity.
Chromate and selenate hydrocalumite solid solutions and their applications in waste treatment
ZHANG Min; Eric J. Reardon
2005-01-01
Hydrocalumite, a calcium aluminate hydrate phase, consists of positively-charged structure units, and is therefore an ideal candidate for accommodating anionic contaminants. In this study, a series of batch experiments was carried out to examine the uptake of chromate and selenate by hydrocalumite. To determine the uptake capacity and long-term stability, hydrocalumite solid solutions between chromate/selenate and hydroxyl were synthesized over a reaction time of more than one year. At a ratio of water to initial solids added (CaAl2O4+CaO) of 75: 1, the maximum uptake capacities were over 77 and 114 g/kg for Cr and Se, respectively.These values are very close to the theoretical uptake capacities of chromate and selenate hydrocalumite end-members (81 and 118 g/kg, respectively). The oxyanion removal efficiency from solution was above 95%. Due to the high uptake capacity and anion removal efficiency of hydrocalumites, their application in wastewater treatment is promising. Hydrocalumites are also important hydration products of cementitious materials and the long-term stability of these phases is of significance for application in solidification/stabilization technology.
Yan, Xin; Liang, Lan-Ju; Ding, Xin; Yao, Jian-Quan
2017-02-01
A high-sensitivity sensing technique was demonstrated based on a flexible terahertz dual-band metamaterial absorber. The absorber has two perfect absorption peaks, one with a fundamental resonance (f1) of the structure and another with a high-order resonance (f2) originating from the interactions of adjacent unit cells. The quality factor (Q) and figure of merit of f2 are 6 and 14 times larger than that of f1, respectively. For the solid analyte, the changes in resonance frequency are monitored upon variation of analyte thickness and index; a linear relation between the amplitude absorption with the analyte thickness is achieved for f2. The sensitivity (S) is 31.2% refractive index units (RIU-1) for f2 and 13.7% RIU-1 for f1. For the aqueous solutions, the amplitude of absorption decreases linearly with increasing the dielectric constant for the ethanol-water mixture of f1. These results show that the designed absorber cannot only identify a solid analyte but also characterize aqueous solutions through the frequency shift and amplitude absorption. Therefore, the proposed absorber is promising for future applications in high-sensitivity monitoring biomolecular, chemical, ecological water systems, and aqueous biosystems.
Mechanical Properties of Mg-Gd and Mg-Y Solid Solutions
Kula, Anna; Jia, Xiaohui; Mishra, Raj K.; Niewczas, Marek
2016-12-01
The mechanical properties of Mg-Gd and Mg-Y solid solutions have been studied under uniaxial tension and compression between 4 K and 298 K (-269 °C and 25 °C). The results reveal that Mg-Gd alloys exhibit higher strength and ductility under tension and compression attributed to the more effective solid solution strengthening and grain-boundary strengthening effects. Profuse twinning has been observed under compression, resulting in a material texture with strong dominance of basal component parallel to compression axis. Under tension, twining is less active and the texture evolution is controlled mostly by slip. The alloys exhibit pronounced yield stress asymmetry and significantly different work-hardening behavior under tension and compression. Increasing of Gd and/or Y concentration leads to the reduction of the tension-compression asymmetry due to the weakening of the recrystallization texture and more balanced twinning and slip activity during plastic deformation. The results suggest that under compression of Mg-Y alloys slip is more active than twinning in comparison to Mg-Gd alloys.
FTIR assessment of poly(ethylene oxide) irradiated in solid state, melt and aqeuous solution
Pucić, Irina; Jurkin, Tanja
2012-09-01
FTIR spectroscopy was used to study poly(ethylene oxide), PEO, irradiated in solid and molten aggregate states and as aqueous solutions of various concentrations. The changes in shape and width of -C-O-C- complex absorption intensities at around 1112 cm-1 were the most prominent. On irradiation of solid samples in contact with air shrinking of -C-O-C- complex and increase in its absorption intensities indicated predominant degradation. Crosslinking prevailed on irradiation of molten PEO and of its aqueous solutions in nitrogen atmosphere and manifested itself as widening of -C-O-C- absorption and decrease of corresponding intensities. Partial or complete merging of CH2 wagging vibrations at 1342 cm-1 and 1360 cm-1 that are characteristic of crystalline PEO into a single absorption at around 1350 cm-1 indicated amorphization what was observed for samples that had reduced degree of crystallinity determined by differential scanning calorimetry. DSC could not discriminate between degradation and crosslinking while the changes in width and shape of -C-O-C- complex were independent of the changes in crystallinity. Comparison of FTIR spectra of the same PEO samples obtained as thin film and as KBr pellets revealed that pellet preparation results in a number of spectral artefacts.
Stability of phases in (Ba, Gd)MnO3 solid solution system
Migaku Kobayashi; Hidenori Tamura; Hiromi Nakano; Hirohisa Satoh; Naoki Kamegashira
2008-01-01
The existing phases in BaxGd1-xMnO3 solid solution system (0≦x≦1) were studied by analyzing the detailed crystal structure of each composition from the results of the Rietveld method using powder X-ray diffraction data. For a small substitution of Ba for Gd (0≦x<0.1), the orthorhombic phase with a perovskite type structure (Pnma space group) was stably formed and this fact was supported by the electron diffraction data. There existed an intermediate phase of Ba0.33Gd0.67MnO3, which was characterized as the tetragonal phase with perovskite structure. The composition range of this phase was narrow and almost line compound. Between the regions of these phases, there existed two-phase region. There was also a two-phase region between the intermediate tetragonal phase and BaMnO3. Measurement of electrical conductivities of these orthorhombic solid solutions and tetragonal phases showed semiconducting behaviors for both phases and the existence of the phase transition at high temperature for the orthorhombic phase. The transition temperature decreased as the Ba content increased.
Thermoelectric properties of the Ca(5)Al(2-x)In(x)Sb(6) solid solution.
Zevalkink, Alex; Swallow, Jessica; Ohno, Saneyuki; Aydemir, Umut; Bux, Sabah; Snyder, G Jeffrey
2014-11-14
Zintl phases are attractive for thermoelectric applications due to their complex structures and bonding environments. The Zintl compounds Ca(5)Al(2)In(x)Sb(6)and Ca(5)Al(2)In(x)Sb(6) have both been shown to have promising thermoelectric properties, with zT values of 0.6 and 0.7, respectively, when doped to control the carrier concentration. Alloying can often be used to further improve thermoelectric materials in cases when the decrease in lattice thermal conductivity outweighs reductions to the electronic mobility. Here we present the high temperature thermoelectric properties of the Ca(5)Al(2-x)In(x)Sb(6)solid solution. Undoped and optimally Zn-doped samples were investigated. X-ray diffraction confirms that a full solid solution exists between the Al and In end-members. We find that the Al : In ratio does not greatly influence the carrier concentration or Seebeck effect. The primary effect of alloying is thus increased scattering of both charge carriers and phonons, leading to significantly reduced electronic mobility and lattice thermal conductivity at room temperature. Ultimately, the figure of merit is unaffected by alloying in this system, due to the competing effects of reduced mobility and lattice thermal conductivity.
Pressureless sintered beta prime-Si3N4 solid solution: Fabrication, microstructure, and strength
Dutta, S.
1977-01-01
Si3N4, AlN, and Al2O3 were used as basic constituents in a study of the pressureless sintering of beta prime-Si3N4 solid solution as a function of temperature. Y2O3-SiO2 additions were used to promote liquid-phase sintering. The sintered specimens were characterized with respect to density, microstructure, strength, oxidation, and thermal shock resistance. Density greater than 98 percent of theoretical was achieved by pressureless sintering at 1750 C. The microstructure consisted essentially of fine-grained beta prime-Si3N4 solid solution as the major phase. Modulus of rupture strengths up to 483 MPa were achieved at moderate temperature (1000 C), but decreased to 228 MPa at 1380 C. This substantial strength loss was attributed to a glassy grain boundary phase formed during cooling from the sintering temperature. The best oxidation resistance was exhibited by a composition containing 3 mol % Y2O3-SiO2 additives. Water quench thermal shock resistance was equivalent to that of reaction sintered silicon nitride but lower than hot-pressed silicon nitride.
Pressureless sintered beta-prime-Si3N4 solid solution - Fabrication, microstructure, and strength
Dutta, S.
1977-01-01
Pressureless sintering of beta-prime-Si3N4 solid solution was studied as a function of temperature using Si3N4, A1N, and Al2O3 as basic constituents. Y2O3-SiO2 additions were used to promote liquid-phase sintering. The sintered specimens were characterized with respect to density, microstructure, strength, oxidation, and thermal shock resistance. Density greater than 98 percent of theoretical was achieved by pressureless sintering at 1750 C. The microstructure consisted essentially of fine-grained beta-prime-Si3N4 solid solution as the major phase. Modulus of rupture strengths up to 483 M Pa were achieved at moderate temperature (1000 C), but decreased to 228 M Pa at 1380 C. This substantial strength loss was attributed to a 'glassy' grain boundary phase formed during cooling from the sintering temperature. The best oxidation resistance was exhibited by a composition containing 3 mol % Y2O3-SiO2 additives. Water quench thermal shock resistance was equivalent to that of reaction sintered silicon nitride but lower than hot-pressed silicon nitride.
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.
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.
Valence electron structure of the（ZrTi）B2 solid solutions calculated by the three models
无
2009-01-01
The Zr-rich(Zr0.8Ti0.2)B2 and the Ti-rich(Ti0.8Zr0.2)B2 solid solutions are formed when TiB2 and ZrB2 are hot-pressed.To forecast the properties of the two solid solutions,their valence electron structure was analyzed based on the empirical electron theory(EET) of solids and molecules.We used three different models,the average atom model,the average cell model and the real cell model,and compared with the calculation results from the three models.In the real cell model,the lattice constants of the solid solu-tions were supposed to be changed or unchanged.The results showed that different models could only result in slight change in the hybridization levels of the metal atoms in the two solid solutions and little difference between the calculation values.However,they can not change the variant trend of the va-lence electron structure nor the properties of the solid solutions.Thus,the three models and the methods are appropriate and the calculation results are reasonable and consistent.
Valence electron structure of the (ZrTi)B2 solid solutions calculated by the three models
LI JinPing; HAN JieCai; MENG SongHe; WANG BaoLin
2009-01-01
The Zr-rich (Zr0.8Ti0.2)B2 and the Ti-rich Zr0.8Ti0.2)B2 solid solutions are formed when TiB2 and ZrB2 are hot-pressed. To forecast the properties of the two solid solutions, their valence electron structure was analyzed based on the empirical electron theory (EET) of solids and molecules. We used three differen tmodels, the average atom model, the average cell model and the real cell model, and compared with the calculation results from the three models. In the real cell model, the lattice constants of the solid solu-tions were supposed to be changed or unchanged. The results showed that different models could only result in slight change in the hybridization levels of the metal atoms in the two solid solutions and little difference between the calculation values. However, they can not change the variant trend of the va-lence electron structure nor the properties of the solid solutions. Thus, the three models and the methods are appropriate and the calculation results are reasonable and consistent.
Plummer, L.N.; Busenberg, E.; Glynn, P.D.; Blum, A.E.
1992-01-01
Synthetic strontianite-aragonite solid-solution minerals were dissolved in CO2-saturated non-stoichiometric solutions of Sr(HCO3)2 and Ca(HCO3)2 at 25??C. The results show that none of the dissolution reactions reach thermodynamic equilibrium. Congruent dissolution in Ca(HCO3)2 solutions either attains or closely approaches stoichiometric saturation with respect to the dissolving solid. In Sr(HCO3)2 solutions the reactions usually become incongruent, precipitating a Sr-rich phase before reaching stoichiometric saturation. Dissolution of mechanical mixtures of solids approaches stoichiometric saturation with respect to the least stable solid in the mixture. Surface uptake from subsaturated bulk solutions was observed in the initial minutes of dissolution. This surficial phase is 0-10 atomic layers thick in Sr(HCO3)2 solutions and 0-4 layers thick in Ca(HCO3)2 solutions, and subsequently dissolves and/or recrystallizes, usually within 6 min of reaction. The initial transient surface precipitation (recrystallization) process is followed by congruent dissolution of the original solid which proceeds to stoichiometric saturation, or until the precipitation of a more stable Sr-rich solid. The compositions of secondary precipitates do not correspond to thermodynamic equilibrium or stoichiometric saturation states. X-ray photoelectron spectroscopy (XPS) measurements indicate the formation of solid solutions on surfaces of aragonite and strontianite single crystals immersed in Sr(HCO3)2 and Ca(HCO3)2 solutions, respectively. In Sr(HCO3)2 solutions, the XPS signal from the outer ~ 60 A?? on aragonite indicates a composition of 16 mol% SrCO3 after only 2 min of contact, and 14-18 mol% SrCO3 after 3 weeks of contact. The strontianite surface averages approximately 22 mol% CaCO3 after 2 min of contact with Ca(HCO3)2 solution, and is 34-39 mol% CaCO3 after 3 weeks of contact. XPS analysis suggests the surface composition is zoned with somewhat greater enrichment in the outer ~25
Benabderrahmane, Wassila; Lores, Marta; Lamas, Juan Pablo; Benayache, Samir
2017-05-15
The use of a matrix solid-phase dispersion (MSPD) process to extract polyphenols from hawthorn (Crataegus oxyacantha L.) a deciduous shrub with an expected rich phytochemical profile, has been evaluated. MSPD extracts of fruits and leaves have an outstanding content of polyphenols, although the particular phenolic profile is solvent dependent. The extracts were analysed by HPLC-DAD for the accurate identification of the major bioactive polyphenols, some of which have never been described for this species. MSPD has proven to be a good alternative to the classic methods of obtaining natural extracts, fast and with low consumption of organic solvents, therefore, environmentally friendly. The bioactivities can be considered also very remarkable, revealing extracts with high levels of antioxidant activity.
González-López, Jorge; Ruiz-Hernández, Sergio E.; Fernández-González, Ángeles; Jiménez, Amalia; de Leeuw, Nora H.; Grau-Crespo, Ricardo
2015-04-01
The incorporation of cobalt in mixed metal carbonates is a possible route to the immobilization of this toxic element in the environment. However, the thermodynamics of (Ca,Co)CO3 solid solutions are still unclear due to conflicting data from experiment and from the observation of natural ocurrences. Atomistic computer simulations, which allow the evaluation of thermodynamic properties without the interference of unknown kinetic factors, have been increasingly used in recent years for the investigation of the thermodynamics of mixing and impurity incorporation in carbonate. We report here the results of a computer simulation study of the mixing of calcite (CaCO3) and spherocobaltite (CoCO3), using density functional theory calculations. Our simulations suggest that previously proposed thermodynamic models, based only on observed compositions, significantly overestimate the solubility between the two solids and therefore underestimate the extension of the miscibility gap under ambient conditions. The enthalpy of mixing of the disordered solid solution is strongly positive and moderately asymmetric: calcium incorporation in spherocobaltite is more endothermic than cobalt incorporation in calcite. Ordering of the impurities in (0001) layers is energetically favourable with respect to the disordered solid solution at low temperatures and intermediate compositions, but the ordered phase is still unstable to demixing. The solvus and spinodal lines in the phase diagram using a sub-regular solution model has been also calculated, and conclude that many Ca1-xCoxCO3 mineral solid solutions (with observed compositions of up to x=0.027, and above x=0.93) are metastable with respect to phase separation. The strong non-ideality of this solid solution has an important effect on the solid solution / aqueous solution thermodynamic partitioning: the equilibrium level of substitutional impurities in the endmember solids is always low, regardless of the composition of the aqueous
Todorowsky, D. [Sofia Univ. (Bulgaria). Khimicheski Fakultet; Terziev, A. [Sofia Univ. (Bulgaria). Khimicheski Fakultet; Minkova, N. [Sofia Univ. (Bulgaria). Khimicheski Fakultet
1996-12-31
The effect of the mechanoactivation on Y{sub 2}O{sub 3}, Nd{sub 2}O{sub 3} and CeO{sub 2}, on mixtures of La{sub 2}O{sub 3} with each of these oxides as well as on the solid solutions La{sub 2}O{sub 3}-CeO{sub 2} is studied. The activation causes a decrease of the individual oxides` unit cell parameters. The formation of solid solutions of La{sub 2}O{sub 3} with the oxides studied is found. Under the conditions of activation in air no decomposition of La{sub 2}O{sub 3}-CeO{sub 2} solid solution is detected. The solution is, however, destroyed when the activation is carried out in the presence of acids. (orig.)
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.
Mariana Braic
2014-08-01
The deposited films exhibited only solid solution (fcc, bcc or hcp or amorphous phases, no intermetallic components being detected. It was found that the hcp structure was stabilized by the presence of Hf or Y, bcc by Nb or Al and fcc by Cu. For the investigated films, the atomic size difference, mixing enthalpy, mixing entropy, Gibbs free energy of mixing and the electronegativity difference for solid solution and amorphous phases were calculated based on Miedema׳s approach of the regular solution model. It was shown that the atomic size difference and the ratio between the Gibbs free energies of mixing of the solid solution and amorphous phases were the most significant parameters controlling the film crystallinity.
A Matrix Approach to Numerical Solution of the DGLAP Evolution Equations
Ratcliffe, P G
2001-01-01
A matrix-based approach to numerical integration of the DGLAP evolution equations is presented. The method arises naturally on discretisation of the Bjorken x variable, a necessary procedure for numerical integration. Owing to peculiar properties of the matrices involved, the resulting equations take on a particularly simple form and may be solved in closed analytical form in the variable t=ln(alpha_0/alpha). Such an approach affords parametrisation via data x bins, rather than fixed functional forms. Thus, with the aid of the full correlation matrix, appraisal of the behaviour in different x regions is rendered more transparent and free of pollution from unphysical cross-correlations inherent to functional parametrisations. Computationally, the entire programme results in greater speed and stability; the matrix representation developed is extremely compact. Moreover, since the parameter dependence is linear, fitting is very stable and may be performed analytically in a single pass over the data values.
The LiBH_{4}-LiI Solid Solution as an Electrolyte in an All-Solid-State Battery
Sveinbjörnsson, Dadi Þorsteinn; Christiansen, Ane Sælland; Viskinde, Rasmus;
2014-01-01
.6% per charge-discharge cycle is observed. The electrochemical stability of the LiBH4-LiI solid solution was investigated using cyclic voltammetry and is found to be limited to 3 V. The impedance of the battery cells was measured using impedance spectroscopy. A strong correlation is found between...
Lipid nanoparticles with a solid matrix (SLN, NLC, LDC) for oral drug delivery.
Muchow, Marc; Maincent, Philippe; Muller, Rainer H
2008-12-01
Solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), and lipid-drug conjugates (LDC), commonly produced by high-pressure homogenization, are interesting vectors for oral delivery of lipophilic and, to a certain extent, hydrophilic substances. Their production can be done without the use of organic solvents. Techniques to make them a physically stable delivery system have been developed. Scaling up of the production process from lab-size to large-scale dimensions using high-pressure homogenization can be easily achieved by using a different type of homogenizer. The machines used for large-scale production often yield an even better product quality than the lab-scale types. This review article covers the methods of production, characterization, mechanisms of oral bioavailability enhancement, scale-up, final oral dosage forms, and regulatory aspects of lipid nanoparticles for oral drug delivery. It focuses mainly on high-pressure homogenization production methods.
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
Chauhan, Harsh; Kuldipkumar, Anuj; Barder, Timothy; Medek, Ales; Gu, Chong-Hui; Atef, Eman
2014-02-01
To correlate the polymer's degree of precipitation inhibition of indomethacin in solution to the amorphous stabilization in solid state. Precipitation of indomethacin (IMC) in presence of polymers was continuously monitored by a UV spectrophotometer. Precipitates were characterized by PXRD, IR and SEM. Solid dispersions with different polymer to drug ratios were prepared using solvent evaporation. Crystallization of the solid dispersion was monitored using PXRD. Modulated differential scanning calorimetry (MDSC), IR, Raman and solid state NMR were used to explore the possible interactions between IMC and polymers. PVP K90, HPMC and Eudragit E100 showed precipitation inhibitory effects in solution whereas Eudragit L100, Eudragit S100 and PEG 8000 showed no effect on IMC precipitation. The rank order of precipitation inhibitory effect on IMC was found to be PVP K90 > Eudragit E100 > HPMC. In the solid state, polymers showing precipitation inhibitory effect also exhibited amorphous stabilization of IMC with the same rank order of effectiveness. IR, Raman and solid state NMR studies showed that rank order of crystallization inhibition correlates with strength of molecular interaction between IMC and polymers. Correlation is observed in the polymers ability to inhibit precipitation in solution and amorphous stabilization in the solid state for IMC and can be explained by the strength of drug polymer interactions.
Rokhlin, L. L.; Luk'yanova, E. A.; Tabachkova, N. Yu.; Dobatkina, T. V.; Tarytina, I. E.; Korol'kova, I. G.
2017-03-01
The effect of dysprosium added in the amounts such that it does not form an individual phase in equilibrium with solid magnesium on the decomposition of the supersaturated magnesium solid solution in Mg-Sm alloys is studied. The presence of dysprosium in Mg-Sm alloys is found to retard the decomposition of the supersaturated magnesium solid solution and to increase the hardening effect upon aging. When these alloys are aged, dysprosium is partly retained in the magnesium solid solution and partly enters into the compositions of the phases that form during the decomposition of the solid solution and are characteristic of Mg-Sm alloys.
Metal–organic framework based mixed matrix membranes: a solution for highly efficient CO2 capture?
Seoane, B.; Coronas, J.; Gascon, I.; Benavides, M.E.; Karvan, O.; Caro, J.; Kapteijn, F.; Gascon, J.
2015-01-01
The field of metal–organic framework based mixed matrix membranes (M4s) is critically reviewed, with special emphasis on their application in CO2 capture during energy generation. After introducing the most relevant parameters affecting membrane performance, we define targets in terms of selectivity
Lyapunov Functions and Solutions of the Lyapunov Matrix Equation for Marginally Stable Systems
Kliem, Wolfhard; Pommer, Christian
2000-01-01
of the Lyapunov matrix equation and characterize the set of matrices $(B, C)$ which guarantees marginal stability. The theory is applied to gyroscopic systems, to indefinite damped systems, and to circulatory systems, showing how to choose certain parameter matrices to get sufficient conditions for marginal...
Matrix Solution of Coupled Differential Equations and Looped Car Following Models
McCartney, Mark
2008-01-01
A simple mathematical model for the behaviour of how vehicles follow each other along a looped stretch of road is described. The resulting coupled first order differential equations are solved using appropriate matrix techniques and the physical significance of the model is discussed. A number possible classroom exercises are suggested to help…
On the Solution of a Class of Nonlinear Systems Governed by an -Matrix
Woula Themistoclakis
2012-01-01
Full Text Available We consider a weakly nonlinear system of the form (+(=, where ( is a real function of the unknown vector , and (+( is an -matrix. We propose to solve it by means of a sequence of linear systems defined by the iteration procedure (+(+1=, =0,1,…. The global convergence is proved by considering a related fixed-point problem.
Molecular Dynamics Study of Stability of Solid Solutions and Amorphous Phase in the Cu-Al System
YANG Bin; LAI Wen-Sheng
2009-01-01
The relative stability of fcc and bcc solid solutions and amorphous phase with different compositions in the Cu-Al system is studied by molecular dynamics simulations with n-body potentials.For Cu1-xAlx alloys,the calculations show that the fcc solid solution has the lowest energies in the composition region with x＜0.32 or x＞0.72,while the bcc solid solution has the lowest energies in the central composition range,in agreement with the ball-milling experiments that a single bcc solid solution with 0.30＜x＜ 0.70 is obtained.The evolution of structures in solid solutions and amorphous phase is studied by the coordination number (CN) and bond-length analysis so as to unveil the underlying physics.It is found that the energy sequence among three phases is determined by the competition in energy change originating from the bond length and CNs (or the number of bonds).
Temperature evolution of the crystal structure of Bi1 - xPrxFeO3 solid solutions
Karpinsky, D. V.; Troyanchuk, I. O.; Sikolenko, V. V.; Efimov, V.; Efimova, E.; Silibin, M. V.; Chobot, G. M.; Willinger, E.
2014-11-01
The crystal structure of solid solutions in the Bi1 - xPrxFeO3 system near the structural transition between the rhombohedral and orthorhombic phases (0.125 ≤ x ≤ 0.15) has been studied. The structural phase transitions induced by changes in the concentration of praseodymium ions and in the temperature have been investigated using X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. It has been established that the sequence of phase transformations in the crystal structure of Bi1 - xPrxFeO3 solid solutions with variations in the temperature differs significantly from the evolution of the crystal structure of the BiFeO3 compounds with the substitution of other rare-earth elements for bismuth ions. The regions of the existence of the single-phase structural state and regions of the coexistence of the structural phases have been determined in the investigation of the crystal structure of the Bi1 - xPrxFeO3 solid solutions. A three-phase structural state has been revealed for the solid solution with x = 0.125 at temperatures near 400°C. The specific features of the structural phase transitions of the compounds in the vicinity of the morphotropic phase boundary have been determined by analyzing the obtained results. It has been found that the solid solutions based on bismuth ferrite demonstrate a significant improvement in their physical properties.
Donglai Zhu
2016-09-01
Full Text Available A series of ceria-zirconia solid solutions were synthesized using tobacco leaves, stems and stem-silks as biotemplates. A combination of physicochemical techniques such as powder X-ray diffraction (XRD, N2 adsorption/desorption measurement, scanning electron microscopy (SEM, and transmission electron microscopy (TEM were used to characterize the as-synthesized samples. The results show that the morphologies of the templates were well replicated in the obtained ceria-zirconia solid solutions. Catalytic oxidation activities of CO over the ceria-zirconia solid solutions were then investigated. The catalyst templated by tobacco stem-silk exhibited higher conversion of CO at lower temperature than that of ceria-zirconia solid solutions templated by tobacco leaves and stems or without templates due to its special morphology. The catalyst even showed similar CO conversion when compared to ceria-zirconia solid solutions doped with 1.0 wt % noble metals such as Pt, Ag and Au. The results highlighted the advantages of using tobacco as biotemplate.
Martínez-Villegas, Nadia; Martínez, Carmen Enid
2008-04-15
Copper retention by ferrihydrite, leaf compost, and montmorillonite was studied over 8 months in systems that emulate a natural soil where different solid phases compete for Cu through a common solution in a compartmentalized batch reactor. Copper speciation in solution (total dissolved, DPASV-labile, and free) and exchangeable and total Cu in individual solid phases were determined. Organic carbon in solution (DOC) and that retained by the mineral phases were also determined. Cu sorption reached steady-state after 4 months and accounted for 80% of the Cu initially added to the system (0.15 mg L(-1)). The remaining 20% stayed in solution as nonlabile (82.8%), labile (17%), and free (0.2%) Cu species. Copper sorption followed the order organic matter > silicate clays > iron oxides. Within each solid phase, exchangeable Cu was < or = 10% of the total Cu sorbed. DOC reached steady state (22 mg L(-1)) after 4 months and seemed to control Cu solubility and sorption behavior by the formation of soluble Cu-DOC complexes and by sorbing onto the mineral phases. DOC sorption onto ferrihydrite prevented Cu retention by this solid phase. Using a multicomponent system and 8 months equilibrations, we were able to capture some of the more important aspects of the complexity of soil environments bytaking into account diffusion processes and competition among solid- and solution-phase soil constituents in the retention of a metal cation.
Optical limiting effect in a two-photon absorption dye doped solid matrix
He, Guang S.; Bhawalkar, Jayant D.; Zhao, Chan F.; Prasad, Paras N.
1995-10-01
We recently reported a new lasing dye, trans-4-[p-(N-ethyl-N-hydroxylethylamino)styryl]-N-methylpyridinium tetraphenylborate (ASPT), which has also been shown to possess a strong two-photon absorption (TPA) and subsequent frequency upconversion fluorescence behavior when excited with near infrared laser radiation. Based on the TPA mechanism, a highly efficient optical limiting performance has been demonstrated in a 2 cm long ASPT-doped epoxy rod pumped with 1.06 μm Q-switched laser pulses at 50-250 MW/cm2 intensity levels. The measured nonlinear absorption coefficient reached 6 cm/GW for the tested sample of dopant concentration d0=4×10-3 M/L. The molecular TPA cross section of ASPT in the epoxy matrix is estimated as σ2=2.5×10-18 cm4/GW or σ2'=4.7×10-46 cm4/photon/s, respectively. Two-photon pumped cavity lasing is also observed in an ASPT-doped polymer rod.
Thermodynamics of magnesian calcite solid-solutions at 25°C and 1 atm total pressure
Busenberg, Eurybiades; Plummer, L. Niel
1989-01-01
The stability of magnesian calcites was reexamined, and new results are presented for 28 natural inorganic, 12 biogenic, and 32 synthetic magnesian calcites. The magnesian calcite solid-solutions were separated into two groups on the basis of differences in stoichiometric solubility and other physical and chemical properties. Group I consists of solids of mainly metamorphic and hydrothermal origin, synthetic calcites prepared at high temperatures and pressures, and synthetic solids prepared at low temperature and very low calcite supersaturations () from artificial sea water or NaClMgCl2CaCl2solutions. Group I solids are essentially binary s of CaCO2 and MgCO2, and are thought to be relatively free of structural defects. Group II solid-solutions are of either biogenic origin or are synthetic magnesian calcites and protodolomites (0–20 and ∼ 45 mole percent MgCO3) prepared at high calcite supersaturations () from NaClNa2SO4MgCl2CaCl2 or NaClMgCl2CaCl2 solutions. Group II solid-solutions are treated as massively defective solids. The defects include substitution foreign ions (Na+ and SO42−) in the magnesian calcite lattice (point defects) and dislocations (~2 · 109 cm−2). Within each group, the excess free energy of mixing, GE, is described by the mixing model , where x is the mole fraction of the end-member Ca0.5Mg0.5CO3 in the solid-solution. The values of A0and A1 for Group I and II solids were evaluated at 25°C. The equilibrium constants of all the solids are closely described by the equation ln , where KC and KD are the equilibrium constants of calcite and Ca0.5Mg0.5CO3. Group I magnesian calcites were modeled as sub-regular solid-solutions between calcite and dolomite, and between calcite and “disordered dolomite”. Both models yield almost identical equilibrium constants for these magnesian calcites. The Group II magnesian calcites were modeled as sub-regular solid-solutions between defective calcite and
Montes, R; Canosa, P; Lamas, J Pablo; Piñeiro, A; Orriols, I; Cela, R; Rodríguez, I
2009-12-01
The fate of the acaricide fenbutatin oxide (FBTO) during the elaboration of white wine is evaluated. Matrix solid-phase dispersion (MSPD) and solid-phase microextraction (SPME) were used as sample preparation techniques applied to the semi-solid and the liquid matrices involved in this research, respectively. Selective determination of FBTO was achieved by gas chromatography with atomic emission detection (GC-AED). GC coupled to mass spectrometry was also used to establish the identity of FBTO by-products detected in must and wine samples. MSPD extractions were accomplished using C18 as dispersant and co-sorbent. Sugars and other polar interferences were first removed with water and water/acetone mixtures, then FBTO was recovered with 8 mL of acetone. When used in combination with GC-AED, the MSPD method provided limits of quantification (LOQs) in the low nanogram per gram range, recoveries around 90% and relative standard deviations below 13% for extractions performed in different days. Performance of SPME for must and wine was mainly controlled by the extraction temperature, time and fibre coating. Under final conditions, FBTO was extracted in the headspace mode for 45 min at 100 degrees C, using a 100 microm poly(dimethylsiloxane)-coated fibre. The achieved LOQs remained around or below 0.1 ng mL(-1), depending on the type of sample, and the inter-day precision ranged from 10% to 13%. FBTO residues in grapes stayed mostly on the skin of the fruit. Although FBTO was not removed during must and white wine elaboration, it remained associated with suspended particles existing in must and lees, settled after must fermentation, with a negligible risk of being transferred to commercialised wine. On the other hand, two by-products of FBTO (bis and mono (2-methyl-2-phenylpropyl) tin) were identified, for first time, in must and final white wines obtained from FBTO treated grapes. Found values for the first species ranged from 0.03 to 0.9 ng mL(-1).
Wang, Chengwei; Wang, Yuan; Graser, Jake; Zhao, Ran; Gao, Fei; O'Connell, Michael J
2013-12-23
A facile and scalable solution-based, spray pyrolysis synthesis technique was used to synthesize individual carbon nanospheres with specific surface area (SSA) up to 1106 m(2)/g using a novel metal-salt catalyzed reaction. The carbon nanosphere diameters were tunable from 10 nm to several micrometers by varying the precursor concentrations. Solid, hollow, and porous carbon nanospheres were achieved by simply varying the ratio of catalyst and carbon source without using any templates. These hollow carbon nanospheres showed adsorption of to 300 mg of dye per gram of carbon, which is more than 15 times higher than that observed for conventional carbon black particles. When evaluated as supercapacitor electrode materials, specific capacitances of up to 112 F/g at a current density of 0.1 A/g were observed, with no capacitance loss after 20,000 cycles.
Stranius, K.; Börjesson, K.
2017-01-01
Photoswitchable molecules are able to isomerize between two metastable forms through light stimuli. Originally being studied by photochemists, this type of molecule has now found a wide range of applications within physics, chemistry and biology. The extensive usage of photochromic molecules is due to the two isomers having fundamentally different physical and chemical properties. The most important attribute of a photoswitch is the photoisomerization quantum yield, which defines the efficiency of the photoisomerization event. Here we show how to determine the photoisomerization quantum yield in the solid state and in solution when taking thermal processes into account. The described method together with provided software allows for rapid and accurate determination of the isomerization process for this important class of molecules.
Solid Solution Quantum Dots with Tunable Dual or Ultrabroadband Emission for LEDs.
Gugula, Krzysztof; Entrup, Michael; Stegemann, Linda; Seidel, Stefan; Pöttgen, Rainer; Strassert, Cristian A; Bredol, Michael
2017-01-11
Quantum dots that efficiently emit white light directly or feature a "candle-like" orange photoluminescence with a high Stokes shift are presented. The key to obtaining these unique emission properties is through controlled annealing of the core Cu-In-Ga-S quantum dots in the presence of zinc ions, thus forming Zn-Cu-In-Ga-S solid solutions with different distributions of the substitution and dopant elements. The as-obtained nanocrystals feature excellent quantum yields of up to 82% with limited or even eliminated reabsorption and a color rendering index of bare particles of up to 88, enabling the production of high-quality white LEDs using a single color converter layer. Furthermore, the color properties can be tuned by changing the experimental conditions as well as by varying the excitation wavelength. The multicomponent luminescence mechanism is discussed in detail based on similar literature reports. White LEDs with unparalleled color quality and competitive luminous efficacies are presented herein.
Anomalous birefringence in andradite-grossular solid solutions: a quantum-mechanical approach
Lacivita, Valentina; D'Arco, Philippe; Orlando, Roberto; Dovesi, Roberto; Meyer, Alessio
2013-11-01
The static linear optical properties (refractive indices, birefringence and axial angle) of andradite-grossular (Ca3Fe2Si3O12-Ca3Al2Si3O12) solid solutions have been computed at the ab initio quantum-mechanical level through the Coupled Perturbed Kohn-Sham scheme, using an all-electron Gaussian-type basis set. Geometry relaxation after substitution of 1-8 Al for Fe atoms in the primitive cell of andradite yields 23 non-equivalent configurations ranging from cubic to triclinic symmetry. Refractive indices vary quite regularly between the andradite (1.860) and grossular (1.671) end-members; the birefringence δ and the axial angle 2 V at intermediate compositions can be as large as 0.02° and 89°, respectively. Comparison with experiments suffers from inhomogeneities and impurities of natural samples; however, semi-quantitative agreement is observed.
Analysis of electrostatic stability and ordering in quaternary perovskite solid solutions
Caetano, Clovis; Butler, Keith T.; Walsh, Aron
2016-04-01
There are three distinct classes of perovskite structured metal oxides, defined by the charge states of the cations: AIBVO3,AIIBIVO3 , and AIIIBIIIO3 . We investigated the stability of cubic quaternary solid solutions A B O3-A'B'O3 using a model of point-charge lattices. The mixing enthalpies were calculated and compared for the three possible types of combinations of the compounds, both for the random alloys and the ground-state-ordered configurations. The mixing enthalpy of the (I,V)O3-(III,III)O3 alloy is always larger than the other alloys. We found that, different from homovalent alloys, for these heterovalent alloys a lattice constant mismatch between the constituent compounds could contribute to stabilize the alloy. At low temperatures, the alloys present a tendency to spontaneous ordering, forming superlattices consisting of alternated layers of AB O 3 and A'B'O3 along the [110 ] direction.
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.
Magnetic properties of Ho1- x Lu x B12 solid solutions
Gabáni, S.; Gaz̆o, E.; Pristás̆, G.; Takác̆ová, I.; Flachbart, K.; Shitsevalova, N.; Siemensmeyer, K.; Sluchanko, N.
2013-05-01
Magnetic properties of the geometrically frustrated antiferromagnet HoB12 (with T N = 7.4 K) modified by substitution of magnetic Ho atoms through non-magnetic Lu ones are presented and discussed. In this case, in Ho1- x Lu x B12 solid solutions, both chemical pressure resulting from different Lu3+ and Ho3+ radii and magnetic dilution take place with increasing Lu content ( x) that change properties of the system. The received results show strong indication for the existence of a quantum critical point near x = 0.9, which separates the region of magnetic order (starting with HoB12 for x = 0) and the nonmagnetic region (ending with superconducting LuB12 for x = 1).
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)
Diffuse scattering measurements of static atomic displacements in crystalline binary solid solutions
Ice, G.E.; Sparks, C.J.; Jiang, X.; Robertson, L.
1997-09-01
Diffuse x-ray scattering from crystalline solid solutions is sensitive to both local chemical order and local bond distances. In short-range ordered alloys, fluctuations of chemistry and bond distances break the long-range symmetry of the crystal within a local region and contribute to the total energy of the alloy. Recent use of tunable synchrotron radiation to change the x-ray scattering contrast between elements has greatly advanced the measurement of bond distances between the three kinds of atom pairs found in crystalline binary alloys. The estimated standard deviation on these recovered static displacements approaches {+-}0.001 {angstrom} (0.0001 nm) which is an order of magnitude more precise than obtained with EXAFS. In addition, both the radial and tangential displacements can be recovered to five near neighbors and beyond. These static displacement measurements provide new information which challenges the most advanced theoretical models of binary crystalline alloys. 29 refs., 8 figs., 2 tabs.
Effect of oxygen defects on thermal conductivity of thorium-cerium dioxide solid solutions
Muta, Hiroaki; Kado, Hirohisa; Ohishi, Yuji; Kurosaki, Ken; Yamanaka, Shinsuke
2017-01-01
Thermal conductivity of thorium-cerium dioxide solid solutions has been measured and analyzed using the relaxation time approximation. Despite the presence of oxygen defects, the partially reduced Th0.8Ce0.2O1.97 exhibited higher thermal conductivity than the stoichiometric one, Th0.8Ce0.2O2.00, showing the same tendency as that previously reported for Th0.7Pu0.3O2-δ. The increase in thermal conductivity with the oxygen defects can be explained by assuming that cerium ions have an average ionic radius of the ionic radii of Ce3+ and Ce4+ in the description of phonon-impurity scattering. This result indicates that the small reduction of (Th,Pu)O2-δ fuel increases the thermal conductivity, especially at high temperatures.
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)
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......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 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...
Thermal stability of a supersaturated Fe-Ge-Nb solid solution produced by ball milling
Ipus, J J; Blazquez, J S; Conde, A, E-mail: conde@us.e [Dpto. Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, PO Box 1065, 41080, Sevilla (Spain)
2010-03-01
Thermal evolution of Fe neighbourhood in a supersaturated bcc Fe(Ge,Nb) solid solution, obtained as the final product of mechanical alloying of Fe{sub 75}Ge{sub 20}Nb{sub 5}, was studied. No changes in Fe neighbourhood were detected after heating up to 473 K, although differential scanning calorimetry shows a clear deviation of the baseline at 400 K. After heating up to 723 K, a similar nanocrystalline microstructure is derived from X-ray diffraction. However, Moessbauer spectra evidence changes in the Fe neighbourhood. A proposed deconvolution of the hyperfine field distribution yields a Ge content of {approx}10 at. %, in agreement with the maximum solubility of Ge in bcc Fe in thermodynamical equilibrium.
Multi-component solid solution and cluster hardening of Al–Mn–Si alloys
Zhao, Qinglong [Department of Materials Science and Engineering, Norwegian University of Science and Technology, Trondheim N-7491 (Norway); Holmedal, Bjørn, E-mail: bjorn.holmedal@ntnu.no [Department of Materials Science and Engineering, Norwegian University of Science and Technology, Trondheim N-7491 (Norway); Li, Yanjun [Department of Materials Science and Engineering, Norwegian University of Science and Technology, Trondheim N-7491 (Norway); Sagvolden, Espen; Løvvik, Ole Martin [SINTEF Materials and Chemistry, Oslo N-0314 (Norway)
2015-02-11
Tensile tests on Al–Mn–Si ternary alloys show that a small amount of Si increases significantly the strength compared to Al–Mn binary alloys with the same concentration of Mn. This cannot be explained by classical theories for multi-element substitutional solid solution hardening under the assumption of no interaction between different alloying elements. A new simplified cluster strengthening model which addresses both the chemical and size misfit effects of atom dimers is proposed this work. The binding energies and misfit of dimers were estimated by first principles atomistic simulations. The prediction results of the model are reasonably consistent with the experimental results. It shows that the main strengthening contribution is due to the misfit of dimers.
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.
Free Volumes Associated with Sintering in Gadolinium Doped Ceria Solid Solutions
Tomomi Kosaka
2010-01-01
Full Text Available Gadolinium-doped ceria (GDC solid solution prepared by the oxalate coprecipitation method is investigated by X-ray diffraction (XRD, complex impedance analysis, and positron lifetime spectroscopy. XRD reveals an expansion of GDC lattice constant by doping gadolinium into a ceria host crystal, in agreement with an oxygen vacancy model. The ionic conductivity of GDC measured at 773 K in air is two orders of magnitude higher than that of undoped ceria. Positron lifetime spectroscopy reveals the presence of vacancy-sized free volumes and nanovoids in interfaces among crystallites. It is found that the vacancy-sized free volumes shrink with increasing sintering temperatures. In the present paper, recent advances in the studies of GDC by XRD, complex impedance measurement, and positron lifetime spectroscopy are reviewed to gain an insight into the sintering mechanism.
Lawson, C. A.; Nord, G. L., Jr.
1984-01-01
In the ilmenite-hematite solid solution series, compositions more ilmenite-rich than Ilm(73)Hem(27) are classically thought to be paramagnetic at room temperature. Ilm(80)Hem(20) samples have nevertheless been synthesized that acquire hard saturation remanent and thermoremanent moments. From analysis of AC demagnetization data, the source of the measured remanence is believed to be a single-domain (SD) like material within the IlM(80)Hem(20) grains themselves. On the basis of transmission electron microscope observations, it is suggested that transformation-induced domain boundaries, which in part are enriched in hematite component relative to the bulk composition of the grains, could act as the magnetic carrier of the SD-like remanence.
Discreet Solutions for Matrix Systems in Partial Derivatives Hyperbolic and Singular
Salazar, Manuel J
2011-01-01
In this paper we study the construction of a discrete solution for a hyperbolic system of partial differentials of the strongly coupled type. In its construction, the discrete separation of matricial variable method was followed. Two separate equations in differences were obtained: a singular matricial and the other one a Sturm Liouville vectorial problem, which by the superposition principle yield a stable discrete solution.
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
Adaptation response of Pseudomonas fragi on refrigerated solid matrix to a moderate electric field.
Chen, Wenbo; Hu, Honghai; Zhang, Chunjiang; Huang, Feng; Zhang, Dequan; Zhang, Hong
2017-02-10
Moderate electric field (MEF) technology is a promising food preservation strategy since it relies on physical properties-rather than chemical additives-to preserve solid cellular foods during storage. However, the effectiveness of long-term MEF exposure on the psychrotrophic microorganisms responsible for the food spoilage at cool temperatures remains unclear. The spoilage-associated psychrotroph Pseudomonas fragi MC16 was obtained from pork samples stored at 7 °C. Continuous MEF treatment attenuated growth and resulted in subsequent adaptation of M16 cultured on nutrient agar plates at 7 °C, compared to the control cultures, as determined by biomass analysis and plating procedures. Moreover, intracellular dehydrogenase activity and ATP levels also indicated an initial effect of MEF treatment followed by cellular recovery, and extracellular β-galactosidase activity assays indicated no obvious changes in cell membrane permeability. Furthermore, microscopic observations using scanning and transmission electron microscopy revealed that MEF induced sublethal cellular injury during early treatment stages, but no notable changes in morphology or cytology on subsequent days. Our study provides direct evidence that psychrotrophic P. fragi MC16 cultured on nutrient agar plates at 7 °C are capable of adapting to MEF treatment.
Nanocrystalline Ce1- x La x O2- δ Solid Solutions Synthesized by Hydrolyzing and Oxidizing
Hou, Xueling; Xue, Yun; Han, Ning; Lu, Qianqian; Wang, Xiaochen; Phan, Manh-Huong; Zhong, Yunbo
2016-05-01
We undertook a novel batch production approach for the synthesis of CeO2 nanopowders doped with rare earth elements. Solid solution nanopowders of Ce1- x La x O2- δ ( x = 0.15) were successfully synthesized in a large-scale and low-cost production by hydrolyzing and oxidizing Ce-La-C alloys at room temperature and subsequent calcining of their powders at different temperatures (873-1073 K) for 1 h. The Ce-La-C alloys were prepared in a vacuum induction melting furnace. The final products were characterized by x-ray diffraction, transmission electron microscopy, Brunner-Emmet-Teller (BET) surface area analyzer, and Raman spectroscopy. The calculated lattice parameters of the cubic fluorite-type phase of CeO2 tended to increase when La3+ was incorporated into CeO2. The F 2g band shift and the absence of a peak corresponding to La2O3 in the Raman spectra consistently confirmed the incorporation of the La3+ ion into CeO2, and the formation of Ce1- x La x O2- δ solid solutions as manifested by increased oxygen vacancy defects. High-quality Ce1- x La x O2- δ nanopowders of ~10-15 nm diameter with a high BET surface area of ~77 m2 g-1 were obtained. The average crystallite size of Ce1- x La x O2- δ was found to be smaller than that of CeO2 for the same calcination temperature of 1073 K, demonstrating that the introduction of La3+ into CeO2 can stabilize the host lattice and refine the grain size at high temperatures.
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.
Boev, Victor I.; Soloviev, Alexei; Silva, Carlos J. R.; Gomes, Maria J. M.
2006-01-01
Nanocomposite materials based on an organic-inorganic ureasilicate matrix with embedded CdS nanoparticles were produced and characterized by optical (UV/Vis), FTIR, secondary ion mass spectroscopy, inductively-coupled plasma optical emission and steady-state photoluminescence measurements. The ureasilicate precursor was obtained by the reaction between silicon alkoxyde modified by isocyanate groups and polyethylene glycol oligomers with amine terminal groups. The final nanocomposites were prepared by introducing a colloidal solution of CdS nanoparticles with various sizes into the ureasilicate precursor followed by gelation of the mixture in the presence of ammonia/water vapours. The reliable preservation of the quantum-size effect of nanoparticles after their incorporation into the ureasilicate matrix was observed in all samples. The obtained materials were optically transparent at visible range, exhibiting high flexibility and long-term stability.
Kandouci Chahr-Eddine; Adjal Yassine
2014-01-01
This present paper deals with a mathematical description of linear axial and torsional vibrations. The normal and tangential stress tensor components produced by axial-torsional deformations and vibrations in the propeller and intermediate shafts, under the influence of propeller-induced static and variable hydrodynamic excitations are also studied. The transfer matrix method related to the constant coefficients of differential equation solutions is used. The advantage of the latter as compared with a well-known method of transfer matrix associated with state vector is the possibility of reducing the number of multiplied matrices when adjacent shaft segments have the same material properties and diameters. The results show that there is no risk of buckling and confirm that the strength of the shaft line depends on the value of the static tangential stresses which is the most important component of the stress tensor.
Solid Solution Nitriding Technology of 15Cr-7.5Mn-2.6Mo Duplex Stainless Steel
FU Rui-dong; ZHAO Pin; WANG Chun-Yu; QIU Liang; ZHENG Yang-zeng
2004-01-01
Solid solution nitriding technologies of 15Cr-7.5Mn-2.6Mo duplex stainless steel were investigated by using of orthogonal tests. The results show that the best technology would be the processes of 1050℃× 2h + 1150℃× 3h +1050℃× 2h + 1150℃× 4h under pure N2 with PN2=0.15MPa. The high nitrogen austenitic case with the depth of1.62mm can be obtained. Orthogonal tests show that the type of atmosphere has the most notable effect on solid solution nitriding process; the pressure in the furnace and the nitriding processes has a notable effect. X-ray diffraction analyses results indicate that the main phases in the cases of the solution-nitrided samples cooled in the furnace are high nitrogen austenite, CrN, Fe3O4 and nitrogen containing ferrite. In the other samples experienced solid solution nitriding and solution treatment the obtained phase in the cases is high nitrogen austenite only. The results show that solid solution nitriding is a process that nitrogen absolutely diffuses in the austenite. The diffusing activation energy in the conditions of PN2 = 0.15MPa and 1050℃～ 1200℃ is 186.6K J/mol.
Transport properties in dilute UN (X ) solid solutions (X =Xe ,Kr )
Claisse, Antoine; Schuler, Thomas; Lopes, Denise Adorno; Olsson, Pär
2016-11-01
Uranium nitride (UN) is a candidate fuel for current GEN III fission reactors, for which it is investigated as an accident-tolerant fuel, as well as for future GEN IV reactors. In this study, we investigate the kinetic properties of gas fission products (Xe and Kr) in UN. Binding and migration energies are obtained using density functional theory, with an added Hubbard correlation to model f electrons, and the occupation matrix control scheme to avoid metastable states. These energies are then used as input for the self-consistent mean field method which enables to determine transport coefficients for vacancy-mediated diffusion of Xe and Kr on the U sublattice. The magnetic ordering of the UN structure is explicitly taken into account, for both energetic and transport properties. Solute diffusivities are compared with experimental measurements and the effect of various parameters on the theoretical model is carefully investigated. We find that kinetic correlations are very strong in this system, and that despite atomic migration anisotropy, macroscopic solute diffusivities show limited anisotropy. Our model indicates that the discrepancy between experimental measurements probably results from different irradiation conditions, and hence different defect concentrations.
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
Selin, Emma
2013-01-01
This report investigates the possibilities and solutions for a sustainable municipal solid waste management in the community of Mutomo, situated in Kitui County, Kenya. The aim was to formulate an action plan to start reaching for a sustainable development in the waste sector, with citizen participation. Specific research questions were to find requests and ideas from the community members. Also, how the Swedish solid waste management system is built up in order to find potential good example...
Legorreta Garcia, Felipe [Universite de Toulouse, CIRIMAT, CNRS-UPS-INP, Universite Paul-Sabatier, 31062 Toulouse cedex 9 (France); Resende, Valdirene Gonzaga de; De Grave, Eddy [NUMAT, Department of Subatomic and Radiation Physics, University of Ghent, Proeftuinstraat 86, B-9000 Gent (Belgium); Peigney, Alain; Barnabe, Antoine [Universite de Toulouse, CIRIMAT, CNRS-UPS-INP, Universite Paul-Sabatier, 31062 Toulouse cedex 9 (France); Laurent, Christophe, E-mail: laurent@chimie.ups-tlse.fr [Universite de Toulouse, CIRIMAT, CNRS-UPS-INP, Universite Paul-Sabatier, 31062 Toulouse cedex 9 (France)
2009-06-03
The synthesis of Fe{sup 3+}-stabilized zirconia by the nitrate/urea combustion route was investigated. Using several characterization techniques, including X-ray diffraction, field-emission-gun scanning electron microscopy and notably Moessbauer spectroscopy, it was possible to determine the appropriate amount of urea that allows to obtain a totally stabilized Zr{sub 0.9}Fe{sub 0.1}O{sub 1.95} solid solution. The nanocrystalline zirconia solid solution is mostly tetragonal, but the presence of the cubic phase could not be ruled out. An in-depth study of the thermal stability in air showed that the Fe{sup 3+} solubility in the stabilized solid solution starts to decrease at about 875 deg. C which results in the formation of hematite (possibly containing some Zr{sup 4+}) at the surface of the zirconia grains and further provokes the progressive transformation into the monoclinic zirconia phase.
Matrix regeneration therapy：a solution to enhance healing in fungal keratitis
Siti Raihan Ishak; Ahmad Nurfahmi Akhtar Ali; Hayati Abdul Aziz; Mohtar Ibrahim; Denis Barritault; Wan Hazabbah Wan Hitam
2014-01-01
Corneal ulcers, especially of fungal origin, are a relatively common clinical entity within the spectrum of keratitis in tropical countries. The persistence of a non-healing epithelial defect is a known complication of these ulcers. Despite advances in medical therapy, the management of this condition is still challenging. CACICOL20® is a new ophthalmic matrix therapy that has been proved efficient as a corneal healing agent. To the best of our knowledge there have been reports of the limited use of matrix therapy in ocular healing, specifically in fungal keratitis. We report 2 cases of the efficacy of it as an adjuvant to topical amphotericin B in treating non-healing epithelial defects secondary to fungal corneal ulcers.
Matrix regeneration therapy: a solution to enhance healing in fungal keratitis
Siti Raihan Ishak
2014-01-01
Full Text Available Corneal ulcers, especially of fungal origin, are a relatively common clinical entity within the spectrum of keratitis in tropical countries. The persistence of a non-healing epithelial defect is a known complication of these ulcers. Despite advances in medical therapy, the management of this condition is still challenging. CACICOL20® is a new ophthalmic matrix therapy that has been proved efficient as a corneal healing agent. To the best of our knowledge there have been reports of the limited use of matrix therapy in ocular healing, specifically in fungal keratitis. We report 2 cases of the efficacy of it as an adjuvant to topical amphotericin B in treating non-healing epithelial defects secondary to fungal corneal ulcers.
A sparse matrix iterative method for efficiently computing multiple simultaneous solutions
Boyse, W.E.; Seidl, A.A. [Lockheed Palo Alto Research Labs., CA (United States)
1994-12-31
The authors consider the solution of large sparse complex symmetric indefinite systems of equations where multiple solutions are required. This type of problem occurs in calculating monostatic radar cross sections in electromagnetic scattering using the finite element method. The Quasi Minimum Residual (QMR) method, ideally suited for these matrices, is generalized using the block Lanozos algorithm to solve blocks of solutions simultaneously. The algorithm is presented and a natural convergence criterion is proposed which is shown to be as effective as the usual equation residual in monitoring convergence.
Zimmermann, C.; Chabbi, S.; Schaaf, W.
2009-04-01
During the initial phase of soil formation mineral weathering, interactions between the solid and liquid phases as well as accumulation of organic matter play an important role for the development of soil properties and for the establishment of vegetation and the colonization of soil biota. Our study is part of the Transregional Collaborative Research Centre (SFB/TRR 38) ‘Patterns and processes of initial ecosystem development in an artificial catchment' funded by the Deutsche Forschungsgemeinschaft (DFG). The catchment ´Chicken Creeḱ close to Cottbus (Germany) has a size of 6 ha and is composed of a 3-4 m layer of Quaternary loamy to sandy sediments overlying a 1-2 m clay layer. To connect interactions between the soil solid phase and soil solution at the micro-scale with observed processes at the catchment scale we perform microcosm experiments with soil samples from the catchment under controlled laboratory conditions. The microcosm experiments are carried out in a climate chamber at constant 10 °C corresponding to the mean annual temperature of the region. In total 48 soil columns with a diameter of 14.4 cm and height of 30 cm were filled with substrates of two textural compositions reflecting the gradients observed at the catchment and a bulk density of 1.4-1.5 g*cm3. Within the microcosms it is possible to control the gaseous phase and the water fluxes by artificial irrigation. The irrigation runs automated and quasi-continuously four times a day with 6.6 ml each (in total 600 mm*yr-1). Irrigation amount and chemical composition of the artificial rainwater are based on the annual mean at the field site. Litter of two different plant species occurring at the catchment site (Lotus corniculatus, Calamagrostis epigejos) labelled with stable isotopes (δ13C; δ15N) is used for the experiments. All treatments including a control run with four replicates. The gaseous phase in the headspace of the microcosms is analysed continuously for CO2 and N2O contents
Terra, O.; Dacheux, N.; Clavier, N. [Univ Paris 11, IPNO, Grp Radiochim, F-91406 Orsay, (France); Terra, O.; Audubert, F. [CEA Cadarache, DEN/DEC, F-13108 St Paul Les Durance, (France); Dacheux, N.; Clavier, N.; Podor, R. [ICMS UMR 5257, CNRS/CEA/UM2/ENSCM, F-30207 Bagnols Sur Ceze, (France); Podor, R. [Univ Nancy 1, LCSM, F-54506 Vandoeuvre Les Nancy, (France)
2008-07-01
The simultaneous incorporation of thorium and uranium(IV) in the rare-earth ortho-phosphates from a mixture of powdered AnO{sub 2}, (NH{sub 4})(H{sub 2}PO{sub 4}), and Ca(HPO{sub 4}).2H{sub 2}O was successfully performed, leading to the formation of single-phase Th-brabantite (Ca{sub 0.5}Th{sub 0.5}PO{sub 4}), U-brabantite (Ca{sub 0.5}U{sub 0.5}PO{sub 4}), and (Th,U)-brabantites (Ca{sub 0.5}Th{sub 0.5-y}U{sub y}PO{sub 4}). The repetition of several cycles composed of a grinding step (30 Hz, 15 min) and of a heat treatment (T=1200 degrees C, 10 h, Ar atmosphere) allowed preparation of single-phase and homogeneous compounds. The complete characterization of the samples by the means of X-Ray powder diffraction, electron probe micro-analyses, and {mu}-Raman spectrometry did not reveal either the presence of minor phases or the partial oxidation of uranium(IV) into uranyl. This study also evidenced the formation of a complete Ca{sub 0.5}Th{sub 0.5-y}U{sub y}PO{sub 4} solid solution with the associated linear decrease of a, b, and c unit cell parameters and beta increase versus the uranium mole loading. Even if the samples were found to be single phase, the significant improvement of the cation distribution in the materials was reached by the mean of the repetition of grinding/heating cycles. The same solid-state process was applied with success to the preparation of homogeneous and single-phase (Th,U)-monazite/brabantite solid solutions with general formula Ln{sub 1-2x}Ca{sub x}Th{sub x-y}U{sub y}PO{sub 4} (with 0.1 {<=} x {<=} 0.4 and y=x/5). (authors)
Matrix Continued Fraction Solution to the Relativistic Spin-0 Feshbach-Villars Equations
Brown, N. C.; Papp, Z.; Woodhouse, R.
2016-03-01
The Feshbach-Villars equations, like the Klein-Gordon equation, are relativistic quantum mechanical equations for spin-0 particles.We write the Feshbach-Villars equations into an integral equation form and solve them by applying the Coulomb-Sturmian potential separable expansion method. We consider boundstate problems in a Coulomb plus short range potential. The corresponding Feshbach-Villars CoulombGreen's operator is represented by a matrix continued fraction.
Matrix solution to longitudinal impedance of multi-layer circular structures
Hahn,H.
2008-10-01
A matrix method in which radial wave propagation is treated in analogy to longitudinal transmission lines is presented and applied to finding the longitudinal coupling impedance of axially symmetric multi-layer beam tubes. The method is demonstrated in the case of a Higher Order Mode ferrite absorber with an inserted coated ceramic beam tube. The screening of the ferrite damping properties by the dielectric beam tube is discussed.
Valderrama, Gustavo; Kiennemann, Alain; Goldwasser, Mireya R.
La 1- xSr xNi 0.4Co 0.6O 3 and La 0.8Sr 0.2Ni 1- yCo yO 3 solid solutions with perovskite-type structure were synthesized by the sol-gel resin method and used as catalytic precursors in the dry reforming of methane with CO 2 to syngas, between 873 and 1073 K at atmospheric pressure under continuous flow of reactant gases with CH 4/CO 2 = 1 ratio. These quaternary oxides were characterized by X-ray diffraction (XRD), BET specific surface area and temperature-programmed reduction (TPR) techniques. XRD analyses of the more intense diffraction peaks and cell parameter measurements showed formation of La-Sr-Ni-Co-O solid solutions with La 0.9Sr 0.1CoO 3 and/or La 0.9Sr 0.1NiO 3 as the main crystallographic phases present on the solids depending on the degree of substitution. TPR analyses showed that Sr doping decreases the temperature of reduction via formation of intermediary species producing Ni 0, Co 0 with particle sizes in the range of nanometers over the SrO and La 2O 3 phases. These metallic nano particles highly dispersed in the solid matrix are responsible for the high activity shown during the reaction and avoid carbon formation. The presence of Sr in doping quantities also promotes the secondary reactions of carbon formation and water-gas shift in a very small extension during the dry reforming reaction.
Valderrama, Gustavo [Laboratorio de Catalisis, Petroleo y Petroquimica, Unidad de Estudios Basicos, Universidad de Oriente - Nucleo Bolivar, La Sabanita - Calle San Simon, Estado Bolivar 8001 (Venezuela); Kiennemann, Alain [Laboratoire des Materiaux et Procedes pour la Catalyse, UMR 7515, ECPM, Universite Louis Pasteur, 25 rue Becquerel, 67087 Strasbourg Cedex 2 (France); Goldwasser, Mireya R. [Centro de Catalisis, Petroleo y Petroquimica, Facultad de Ciencias - Universidad Central de Venezuela. Paseo los Ilustres, Los Chaguaramos, Caracas 1040 (Venezuela)
2010-04-02
La{sub 1-x}Sr{sub x}Ni{sub 0.4}Co{sub 0.6}O{sub 3} and La{sub 0.8}Sr{sub 0.2}Ni{sub 1-y}Co{sub y}O{sub 3} solid solutions with perovskite-type structure were synthesized by the sol-gel resin method and used as catalytic precursors in the dry reforming of methane with CO{sub 2} to syngas, between 873 and 1073 K at atmospheric pressure under continuous flow of reactant gases with CH{sub 4}/CO{sub 2} = 1 ratio. These quaternary oxides were characterized by X-ray diffraction (XRD), BET specific surface area and temperature-programmed reduction (TPR) techniques. XRD analyses of the more intense diffraction peaks and cell parameter measurements showed formation of La-Sr-Ni-Co-O solid solutions with La{sub 0.9}Sr{sub 0.1}CoO{sub 3} and/or La{sub 0.9}Sr{sub 0.1}NiO{sub 3} as the main crystallographic phases present on the solids depending on the degree of substitution. TPR analyses showed that Sr doping decreases the temperature of reduction via formation of intermediary species producing Ni{sup 0}, Co{sup 0} with particle sizes in the range of nanometers over the SrO and La{sub 2}O{sub 3} phases. These metallic nano particles highly dispersed in the solid matrix are responsible for the high activity shown during the reaction and avoid carbon formation. The presence of Sr in doping quantities also promotes the secondary reactions of carbon formation and water-gas shift in a very small extension during the dry reforming reaction. (author)
Wei, Zuofu; Pan, Youzhi; Li, Lu; Huang, Yuyang; Qi, Xiaolin; Luo, Meng; Zu, Yuangang; Fu, Yujie
2014-11-01
A method based on matrix solid-phase dispersion extraction followed by ultra high performance liquid chromatography with tandem mass spectrometry is presented for the extraction and determination of phenolic compounds in Equisetum palustre. This method combines the high efficiency of matrix solid-phase dispersion extraction and the rapidity, sensitivity, and accuracy of ultra high performance liquid chromatography with tandem mass spectrometry. The influential parameters of the matrix solid-phase dispersion extraction were investigated and optimized. The optimized conditions were as follows: silica gel was selected as dispersing sorbent, the ratio of silica gel to sample was selected to be 2:1 (400/200 mg), and 8 mL of 80% methanol was used as elution solvent. Furthermore, a fast and sensitive ultra high performance liquid chromatography with tandem mass spectrometry method was developed for the determination of nine phenolic compounds in E. palustre. This method was carried out within <6 min, and exhibited satisfactory linearity, precision, and recovery. Compared with ultrasound-assisted extraction, the proposed matrix solid-phase dispersion procedure possessed higher extraction efficiency, and was more convenient and time saving with reduced requirements on sample and solvent amounts. All these results suggest that the developed method represents an excellent alternative for the extraction and determination of active components in plant matrices.
Ce1-xLaxOy solid solution prepared from mixed rare earth chloride for soot oxidation
韩雪; 王亚飞; 郝红蕊; 郭荣贵; 胡运生; 蒋文全
2016-01-01
Ce1–xLaxOy solid solution was simply prepared using mixed rare earth chloride (RECl3·xH2O, RE=Ce, La>99%, containing unseparated Ce and La from rare earth metallurgical industry) as precursor by ultrasonic-assisted co-precipitation method with differ-ent ultrasonic frequencies (CLf,f=200, 400, 600, 800, 1000 Hz). A compared Ce1–xLaxOy solid solution (CL*) was also prepared by the same mothod with 10% less precipitant. X-ray diffraction results confirmed the formation of Ce1–xLaxOy solid solution, and the crystal structures of these catalysts were not very sensitive to ultrasonic frequency and precipitant amount. However, both of the fac-tors had obvious effect on morphology and surface area of CL, and precipitant amount seem to play a more crucial role than ultra-sonic frequency for Ce1–xLaxOy solid solution preparation. When soot and catalyst were tight contacted, the peak temperature (Tpeak) of soot oxidation and oxygen reducing temperature for CLf catalysts decreased linearly with increasing surface area. Under loose contact condition, theTpeak had obvious negative correlation with H2 consumption. It was inferred that good reducibility of the Ce1–xLaxOy solid solution favored the soot oxidation reaction. The Ce1–xLaxOy solid solution prepared from unseparated rare earth chloride showed a good soot oxidaiton activity. Controlling the preparation conditions to prepare a CL catalyst would high surface area will enhance its reducibility and activity.
Analytical solution of linear ordinary differential equations by differential transfer matrix method
Sina Khorasani
2003-08-01
Full Text Available We report a new analytical method for finding the exact solution of homogeneous linear ordinary differential equations with arbitrary order and variable coefficients. The method is based on the definition of jump transfer matrices and their extension into limiting differential form. The approach reduces the $n$th-order differential equation to a system of $n$ linear differential equations with unity order. The full analytical solution is then found by the perturbation technique. The important feature of the presented method is that it deals with the evolution of independent solutions, rather than its derivatives. We prove the validity of method by direct substitution of the solution in the original differential equation. We discuss the general properties of differential transfer matrices and present several analytical examples, showing the applicability of the method.
Waleed M. Abd-Elhameed
2016-09-01
Full Text Available Herein, two numerical algorithms for solving some linear and nonlinear fractional-order differential equations are presented and analyzed. For this purpose, a novel operational matrix of fractional-order derivatives of Fibonacci polynomials was constructed and employed along with the application of the tau and collocation spectral methods. The convergence and error analysis of the suggested Fibonacci expansion were carefully investigated. Some numerical examples with comparisons are presented to ensure the efficiency, applicability and high accuracy of the proposed algorithms. Two accurate semi-analytic polynomial solutions for linear and nonlinear fractional differential equations are the result.
Emran Tohidi
2016-01-01
Full Text Available This article contributes a matrix approach by using Taylor approximation to obtain the numerical solution of one-dimensional time-dependent parabolic partial differential equations (PDEs subject to nonlocal boundary integral conditions. We first impose the initial and boundary conditions to the main problems and then reach to the associated integro-PDEs. By using operational matrices and also the completeness of the monomials basis, the obtained integro-PDEs will be reduced to the generalized Sylvester equations. For solving these algebraic systems, we apply a famous technique in Krylov subspace iterative methods. A numerical example is considered to show the efficiency of the proposed idea.
Solution-Processed Organic Thin-Film Transistor Array for Active-Matrix Organic Light-Emitting Diode
Harada, Chihiro; Hata, Takuya; Chuman, Takashi; Ishizuka, Shinichi; Yoshizawa, Atsushi
2013-05-01
We developed a 3-in. organic thin-film transistor (OTFT) array with an ink-jetted organic semiconductor. All layers except electrodes were fabricated by solution processes. The OTFT performed well without hysteresis, and the field-effect mobility in the saturation region was 0.45 cm2 V-1 s-1, the threshold voltage was 3.3 V, and the on/off current ratio was more than 106. We demonstrated a 3-in. active-matrix organic light-emitting diode (AMOLED) display driven by the OTFT array. The display could provide clear moving images. The peak luminance of the display was 170 cd/m2.
Mechanosynthesis of supersaturated solid solutions of Sn in near-equiatomic bcc FeCo
Loureiro, J.M. [CEMDRX, Physics Department, University of Coimbra, P-3004-516 Coimbra (Portugal); Costa, B.F.O., E-mail: benilde@ci.uc.pt [CEMDRX, Physics Department, University of Coimbra, P-3004-516 Coimbra (Portugal); Le Caeer, G. [IPR, UMR URI-CNRS 6251, Universite de Rennes I, Campus de Beaulieu, Bat 11A, F-35042 Rennes Cedex (France)
2012-09-25
Highlights: Black-Right-Pointing-Pointer (Fe{sub 50-x/2}Co{sub 50-x/2})Sn{sub x} mixtures are mechanically alloyed for x {<=} 33 at.%. Black-Right-Pointing-Pointer As-ground powders are studied by X-ray diffraction and {sup 57}Fe and {sup 119}Sn Moessbauer spectroscopy. Black-Right-Pointing-Pointer Supersaturated solutions of Sn in disordered bcc FeCo alloys are formed in our dynamical conditions up to x {<=} 20 at.%. Black-Right-Pointing-Pointer This maximum Sn solubility found is much larger than the equilibrium solubility which is about 0.5 at.%. Black-Right-Pointing-Pointer The mean {sup 119}Sn hyperfine field in the bcc alloys is essentially constant with x and equal to 9.6 T at room temperature. - Abstract: The mechanosynthesis of Fe-Co-Sn ternary alloys from initial powder mixtures of composition (Fe{sub 50-x/2}Co{sub 50-x/2})Sn{sub x} is studied for x {<=} 33 at.%. Disordered nanocrystalline bcc solid solutions are formed in that way up to Sn contents as large as {approx}20 at.%. The dissolution of Sn in near-equiatomic bcc Fe-Co is unambiguously proven by X-ray diffraction and {sup 57}Fe and {sup 119}Sn Moessbauer spectroscopy.
Corrosion behavior of solid solution (Ti,Al)N as a function of Al concentration
Larijani, M.M.; Seyedi, H. [Nuclear Science and Technology Research Institute, P. O. Box 31485-498, Karaj (Iran, Islamic Republic of); Manouchehrian, M. [Department of Physics, Science Faculty, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Yari, M. [Engineering Department Materials, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)
2012-08-15
In this work, a series of (Ti, Al) N coatings with different Al contents were deposited on 304 stainless steel substrates by Hollow Cathode Discharge (HCD) method. The coatings were grown on 304 stainless steel substrates at 400 C. The coatings were characterized using energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), atomic force microscopy (AFM), and microhardness test. The XRD confirmed the transition from TiN phase to (Ti, Al) N phase and then to AlN phase with increasing Al concentration in the solid solution. It was found that with increasing Al concentration the hardness of the coatings initially increased up to a maximum value of about 30 GPa at around 32 at.% of Al and then the coating hardness decreased rapidly with further increase of Al content (Al > 32 at.%). The potentiodynamic polarization analysis was carried out in 3.5 wt.% NaCl solutions to study the corrosion resistance of the coatings. From the corrosion test it can be inferred that the amount of Al atoms in the coatings plays an important role for reducing the corrosion. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Cadmium Extraction from Solutions by Solid-Phase and its Trace Determination
Ashrafi, F.; Attaran, A. M. [Payame Noor University, Sari (Iran, Islamic Republic of); Kermani, N. Memar [Islamic Azad University, Tehran (Iran, Islamic Republic of)
2008-04-15
A new sensitive and selective spectrophotometric method for determination of trace amounts of cadmium using a polyvinyl chloride membrane containing bis-(2-ethylhexyl)phthalate as a solid phase extraction medium was investigated. Bis-(2-ethylhexyl)phthalate has used as a plasticizer. Cd(II) in an aqueous solution was trapped on the membrane in the form of colorful Cd (II)-I{sup -} - MG complexes (which MG is malachite green) and the cadmium complex was concentrated in the membrane. The absorbance of the green membrane was measured at 629 nm using a spectrophotometer, and then, the concentration of the cadmium was calculated using a calibration curve, which expressed the relationship between the Cd(II) concentration and the membrane absorbance after coloring for 25 min. The calibration curve was linear in the range of 10-760 μgL{sup -1} cadmium in the test solution. The detection limit based on the 3S{sub bl} criterion was 1.8199 μgL{sup -1} and the relative standard deviations (RSD) were less than 4 % (n=5). The proposed method has been successfully applied to the determination of trace amounts of cadmium in the Tadjan River water sample (Sari-Iran), and the mean value of 28.7 μgL{sup -1} was obtained.
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.
THE SUPPORTING SOLUTION SYSTEMS FOR MATRIX TRICKS%矩阵计策的支撑解系
姜殿玉
2001-01-01
令[aij]n×n是二人零和对策的支付矩阵.局中人1可用其"计策"得到最大支付a＝max{aij|1≤i≤n,1≤j≤n},然而,一个开放问题是如何找到全体计策解,本文首先引进计策解系的一种特殊类型--支撑解系.然后研究支撑解系的特征、性质、代数结构.最后给出寻找全体基本支撑解系的一个算法.%Let [aij]n×n be the payoff matrix of a two-person zero-sum game. The player 1 can obtain the greatest payment a=max{aij[I≤i≤m,1≤j≤n} by using his "trick". But,it is an open problem to find all trick solutions. In this paper,we, first ,introduce the concept of supporting solution system that is a special form of trick solution system. Then we research the character ,properties ,and algebraic structure of supporting solution systems. Finally,we give an algorithm for finding all basic supporting solution systems.
CP276铝-锂合金的固溶温度研究%Study on Solid Solution Treatment Temperature for Al-Li Alloy CP276
谢绍俊
2001-01-01
探讨了固溶温度对CP276铝-锂合金显微组织和力学性能的影响.研究证明，提高固溶温度可以促进Cu、Li原子向基体溶解，进而提高合金时效的沉淀强化效果.并且发现，该合金经固溶处理后可得到未完全再结晶组织，这种微观组织将对基体产生"组织强化效应"，随着固溶温度升高，合金的再结晶程度也有所增加，从而使组织强化效应受到削弱.力学性能测定结果显示，CP276合金的理想固溶温度为530℃左右.%The effect of solid solution treatment (SST) temperature on the microstructure and mechanical properties for aluminium-lithium alloy CP276 was experimentally explored. It is verified that the increasing of SST temperature promoted the dissolving of Cu, Li atoms to solid solution matrix, and hence improved the ageing strengthening effect upon the alloy. It is also found that, incompletely recrystallized structure could be obtained after solid solution treatment, which helpfully providing "structure-strengthening effect" for this alloy. However, the recrystallization degree improved along with the increasing of SST temperature, making the structure-strengthening effect somewhat weakened. The results of mechanical tensile tests show the desirable SST temperature for alloy CP276 is about 530 ℃.
Synthesis and solubility of Pb-Ca and P-As hydroxylapatite solid solutions
Puzio, Bartosz; Młynarska, Maria; Motyka, Joanna; Oknińska, Joanna; Mandelt, Agnieszka; Chlebowska, Patrycja; Kwaśniak-Kominek, Monika; Manecki, Maciej
2016-04-01
The objective of the study are three solid solution series: - HPY hydroxylpyromorphite Pb5(PO4)3OH - HAP hydroxylapatite Ca5(PO4)3OH - HAP hydroxylapatite Ca5(PO4)3OH - JBM johnbaumite Ca5(AsO4)3OH - JBM johnbaumite Ca5(AsO4)3OH - HMI hydroxylmimetite Pb5(AsO4)3OH The phases were synthesized from aqueous solutions at high pH (over 8) at ambient temperature by dropwise mixing of chemical reagents: Pb(NO3)2, Ca(NO3)2.4H2O, (NH4)H2PO4, and Na2AsHO4.7H2O. The products of all syntheses are crystalline, monomineral fine powders (crystal size less than 1 μm). Their chemical composition is close to theoretical. Systematic shift of XRD peaks and FTIR or Raman bands is observed within the solid solution series. Dissolution experiments were run at 5oC, 25oC, 45oC, and 65oC. An aliquot of 0.5g of each phase was dissolved in 250 mL of 0.05M NH4NO3 (pH between 3 and 5) for about 3 months. In all cases dissolution resulted in increase of pH by about 1. The systems were considered in equilibrium when three consecutive samplings (ca. two weeks apart) resulted in similar concentrations (within 3 standard deviations). The dissolution of all phases in question is incongruent. The amount of precipitating secondary phases was too small for identification. The results of HPY - HAP dissolution experiments are inconclusive due to strongly incongruent dissolution. This is partially in contrary to recent report by Zhu et al. (2015). Systematic increase of solubility is observed in HAP - JBM series. Also, the solubility of these phases increases with the increase of temperature. This is more pronounced for HAP than for JBM. Systematic increase of solubility is also observed in HMI - JBM series. This work is partially funded by AGH research grant no 11.11.140.319 and partially by Polish NCN grant No 2014/01/M/ST10/00355. Zhu,Y., Zhu, Z., Zhao, X., Liang, Y., Huang, Y., 2015. Characterization, dissolution, and solubility of lead hydroxypyromorphite Pb5(PO4)3OH at 25-45oC. Journal of Chemistry
无
2010-01-01
A general method was described to synthesize a highly hydrophobic cyclic peptide,cyclo[LWLWLWLWLQ]where underlines indicate D-configuration of the amino acid,by a two-step solid-phase/solution synthesis strategy.The linear decapeptide was assembled by standard Boc chemistry on solid-phase and subsequently cyclized in solution with high efficiency and reproducibility. In subsequent purification by semi-preparative HPLC,50%(v/v) DMF/H_2O was employed as the solvent to overcome the difficulty of solubilizat...
Franiv, A. V.; Stadnyk, V. Y.; Kashuba, A. I.; Brezvin, R. S.; Bovgira, O. V.; Futei, A. V.
2017-07-01
Results of studying the optical properties of In x Tl1- x I solid solutions in the concentration domain of 0.4 ≤ x ≤ 0.9 are presented. The dependence of relative linear expansion of In x Tl1- x I crystals ( T = 300-520 K) has been obtained. In x Tl1- x I crystals ( T = 300-520 K). Based on this, the temperature dependence of thermal-expansion coefficient α has been found. Dependence of birefringence Δ n i on temperature and concentration of the TlI component in the solid solution has been studied.
Blazquez, J.S.; Ipus, J.J.; Millan, M.; Franco, V. [Departamento de Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, Apartado 1065, 41080 Sevilla (Spain); Conde, A. [Departamento de Fisica de la Materia Condensada, ICMSE-CSIC, Universidad de Sevilla, P.O. Box 1065, Apartado 1065, 41080 Sevilla (Spain)], E-mail: conde@us.es; Oleszak, D.; Kulik, T. [Faculty of Materials Science and Engineering, Warsaw University of Technology, ul. Woloska 141, 02-507 Warsaw (Poland)
2009-02-05
Mechanical alloying process of Fe{sub 75}Ge{sub 20}Nb{sub 5} composition has been studied at different milling frequencies from initial pure powder mixture to the development of a single bcc phase (supersaturated solid solution). As an intermediate state, an intermetallic phase is formed, which disappears after further milling or after thermal treatment (ascribed to an endothermic process at 700-800 K). A preferential partition of Nb and Ge to the boundaries between nanocrystals of bcc Fe-Ge-Nb supersaturated solid solution is observed from X-ray diffraction (XRD) and Moessbauer results.
Emmons, Erik D; Guicheteau, Jason A; Fountain, Augustus W; Christesen, Steven D
2012-06-01
Raman cross-sections of explosives in solution and in the solid state have been measured using visible and near-infrared excitation via secondary calibration. These measurements are valuable for both fundamental scientific purposes and applications in the standoff detection of explosives. The explosive compounds RDX, HMX, TNT, 2,4-DNT, 2,6-DNT, and ammonium nitrate were measured using discrete excitation wavelengths ranging from 532 nm to 785 nm. A comparison of the spectral features and cross-sections between the solid state and solution was performed. Comparison is also made to cross-sections measured with deep ultraviolet excitation.
Audette-Stuart, Marilyne [Atomic Energy of Canada Limited, CANDU Life Sciences Center, Chalk River Laboratories, Chalk River Ont., K0J 1J0 (Canada); Houee-Levin, Chantal [Laboratoire de Chimie Physique, UMR-8000 CNRS-Universite Paris XI, Centre Universitaire, F-91405 Orsay Cedex (France)]. E-mail: chantal.houee-levin@lcp.u-psud.fr; Potier, Michel [Service de genetique medicale, Hopital Sainte-Justine, Universite de Montreal, Montreal Que., H3 T 1C5 (Canada)
2005-02-01
Irradiation of proteins in diluted liquid aqueous solutions produces cleavages and polymerizations of the peptidic chains. In frozen solutions, fragmentation is observed but polymerization products are absent. Loss of activity occurs in both cases. In the solid state, yields of fragmentation do not vary with the quantity of water. The use of scavengers indicates that hydroxyl radical does not contribute significantly to fragmentation and to inactivation in the solid state. Electrons within the water molecules closely associated with the protein are involved in the processes leading to protein fragmentation.
Formation of a 25 mol% Fe2O3-Al2O3 solid solution prepared by ball milling
Jiang, Jianzhong; Mørup, Steen; Linderoth, Søren
1996-01-01
The phase transformation process of a 25 mol% Fe2O3-Al2O3 powder mixture during high-energy ball milling has been studied by x-ray diffraction and Mossbauer spectroscopy. A metastable solid solution of 25 mol % Fe2O3 in Al2O3 with corundum structure has successfully been prepared after a milling...... time of 122 h. This demonstrates that the high-energy ball milling technique is able to prepare metastable solid solutions with an extended range of compositions in ceramic/ceramic systems with a positive hear of mixing....
Plummer, L.N.; Busenberg, E.
1987-01-01
Dissolution of synthetic strontianite-aragonite solid solutions was followed analytically to stoichiometric saturation using large solid to solution ratios in CO2-H2O solution at 25 and 76°C. The compositional dependence of the equilibrium constant was calculated from the composition of saturated (stoichiometric) solutions and used to calculate the activities and activity coefficients of CaCO3 and SrCO3 in the solid Ca(1−x)SrxCO3 at 25 and 76°C. The results show that the solid-solution is not regular but unsymmetrical. The excess free energy of mixing is closely modeled for all compositions by the relation where A0 is 8.49 ± 0.30 and 7.71 ± 0.20 KJ/mole and A1 is −4.51 ± 0.20 and −3.36 ± 0.40 KJ/mole at 25 and 76°C, respectively. The equilibrium constant is denned as a function of the SrCO3 mole fraction, x, by the relation where R is the gas constant, T is in Kelvins and KA and KS are the aragonite and strontianite equilibrium constants.
Brouwers, Joachim; Geboers, Sophie; Mols, Raf; Tack, Jan; Augustijns, Patrick
2017-06-15
This study evaluated the fasted state gastrointestinal behavior of the lipophilic drug itraconazole, orally administered to healthy volunteers as either a solid dispersion (Sporanox(®) capsules) or a cyclodextrin-based solution (Sporanox(®) solution). Following intake of the drug products, gastric and duodenal fluids were aspirated and analyzed for itraconazole concentration, total content and solubilizing capacity. Release of itraconazole from the solid dispersion generated high and metastable supersaturated levels in the stomach, but the dissolved fraction in the duodenum remained extremely low (median 2.5%). After intake of the itraconazole solution, precipitation was limited in the stomach but pronounced in the small intestine. Still, the dissolved fraction of itraconazole in the duodenum (median 38%) appeared much higher than after intake of the solid dispersion, possibly explaining the improved absorption of itraconazole from the solution. As for the solid dispersion, the absorption-enabling ability of the solution appeared mainly related to increased intraluminal concentrations by means of supersaturation. Cyclodextrin-based solubilization of itraconazole occurred only in the case of limited intraluminal dilution, but did not further enhance itraconazole absorption. The obtained data will help to understand critical aspects of supersaturating drug delivery systems and act as direct reference for the optimization of in vitro simulation tools for gastrointestinal drug behavior. Copyright © 2017 Elsevier B.V. All rights reserved.
Jung, Jin-Young; Cho, Seho; Lee, Young-Seak, E-mail: youngslee@cnu.ac.kr
2014-11-25
Highlights: • Novel hollow shaped nanofibers with (Ti, Sn)O{sub 2} solid-solutions were synthesized. • Uniformly distributed hollow shaped nanofibers were formed in the optimum weight ratio of the TTIP. • The highest degradation ratio of photocatalysts exhibited more than 3.5 times that of TiO{sub 2}. - Abstract: Novel hollow shaped nanofibers with (Ti, Sn)O{sub 2} solid-solutions have been synthesized for photocatalysts by the impregnation method using tin chloride (SnCl{sub 2}) and titanium tetraisopropoxide (TTIP), and further characterized by SEM, EDS, TGA, and XRD. The results showed that uniformly distributed hollow shaped nanofibers with (Ti, Sn)O{sub 2} solid-solutions was successfully formed in the case of the optimum weight ratio of the Ti precursor. These hollow shaped nanofibers exhibited the higher photocatalytic reactivity by the conversion of methylene blue in aqueous solution under UV irradiation than not only prepared SnO{sub 2} but also TiO{sub 2} hollow shaped nanofibers. The highest degradation ratio was about 85% at 70 min using hollow shaped nanofibers with (Ti, Sn)O{sub 2} solid-solutions photocatalysts, which exhibited more than 3.5 times that of TiO{sub 2}. It has been found that enhanced MB degradation efficiency is not only due to the charge separation of electron–hole pairs but also increasing the photocatalytic reactive site.
Ridder, Barbara; Foertsch, Tobias C.; Welle, Alexander; Mattes, Daniela S.; von Bojnicic-Kninski, Clemens M.; Loeffler, Felix F.; Nesterov-Mueller, Alexander; Meier, Michael A. R.; Breitling, Frank
2016-12-01
Poly(dimethylacrylamide) (PDMA) based matrix materials were developed for laser-based in situ solid phase peptide synthesis to produce high density arrays. In this specific array synthesis approach, amino acid derivatives are embedded into a matrix material, serving as a "solid" solvent material at room temperature. Then, a laser pulse transfers this mixture to the target position on a synthesis slide, where the peptide array is synthesized. Upon heating above the glass transition temperature of the matrix material, it softens, allowing diffusion of the amino acid derivatives to the synthesis surface and serving as a solvent for peptide bond formation. Here, we synthesized PDMA six-arm star polymers, offering the desired matrix material properties, using atom transfer radical polymerization. With the synthesized polymers as matrix material, we structured and synthesized arrays with combinatorial laser transfer. With densities of up to 20,000 peptide spots per cm2, the resolution could be increased compared to the commercially available standard matrix material. Time-of-Flight Secondary Ion Mass Spectrometry experiments revealed the penetration behavior of an amino acid derivative into the prepared acceptor synthesis surface and the effectiveness of the washing protocols.
Samanidou, Victoria; Kehagia, Maria; Kabir, Abuzar; Furton, Kenneth G
2016-03-31
Highly selective and efficient chloramphenicol imprinted sol-gel silica based inorganic polymeric sorbent (sol-gel MIP) was synthesized via matrix imprinting approach for the extraction of chloramphenicol in milk. Chloramphenicol was used as the template molecule, 3-aminopropyltriethoxysilane (3-APTES) and triethoxyphenylsilane (TEPS) as the functional precursors, tetramethyl orthosilicate (TMOS) as the cross-linker, isopropanol as the solvent/porogen, and HCl as the sol-gel catalyst. Non-imprinted sol-gel polymer (sol-gel NIP) was synthesized under identical conditions in absence of template molecules for comparison purpose. Both synthesized materials were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR) and nitrogen adsorption porosimetry, which unambiguously confirmed their significant structural and morphological differences. The synthesized MIP and NIP materials were evaluated as sorbents for molecularly imprinted solid phase extraction (MISPE) of chloramphenicol in milk. The effect of critical extraction parameters (flow rate, elution solvent, sample and eluent volume, selectivity coefficient, retention capacity) was studied in terms of retention and desorption of chloramphenicol. Competition and cross reactivity tests have proved that sol-gel MIP sorbent possesses significantly higher specific retention and enrichment capacity for chloramphenicol compared to its non-imprinted analogue. The maximum imprinting factor (IF) was found as 9.7, whereas the highest adsorption capacity of chloramphenicol by sol-gel MIP was 23 mg/g. The sol-gel MIP was found to be adequately selective towards chloramphenicol to provide the necessary minimum required performance limit (MRPL) of 0.3 μg/kg set forth by European Commission after analysis by LC-MS even without requiring time consuming solvent evaporation and sample reconstitution step, often considered as an integral part in solid phase extraction work-flow. Intra and
Míguez-Framil, Martha; Cabarcos, Pamela; Tabernero, María Jesús; Bermejo, Ana María; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio
2013-11-05
The possibility of assisting enzymatic hydrolysis (EH) procedures by sample disruption mechanisms inherent to matrix solid phase dispersion (MSPD) has been explored in the current study. EH of hair specimens from poly-drug abusers was assisted by dispersing/blending the sample (0.05 g) with alumina (2.25 g) before loading the dissolved enzyme (6 mL of 1 mg mL(-1) Pronase E in 1.4 M/1.4 M Tris/HCl, pH 7.3) through the hair-alumina solid phase packaged inside a disposable MSPD syringe. The MSPD-EH method was developed, and it proved to offer quantitative results when isolating cocaine, benzoylecgonine (BZE), codeine, morphine and 6-monoacethylmorphine (6-MAM) from human hair samples. The procedure allows an on column clean-up/pre-concentration procedure of the isolated targets by attaching a previously conditioned Oasis HLB cartridge to the end of the MSPD syringe. The EH procedure of human hair with Pronase E can therefore be shortened to approximately 30 min. Within this time, sample blending/dispersion, MSPD syringe package, elution (EH when dissolved Pronase E is passing through the sample-dispersant bed), and extract clean-up and target pre-concentration stages are achieved. Gas chromatography-mass spectrometry (GC-MS) was used for determining each target after elution from the Oasis HLB cartridges with 2 mL of 2% (v/v) acetic acid in methanol, concentration by N2 stream evaporation, and dried extract derivatization with N-methyl-tert-butylsilyltrifluoroacetamide (BSTFA) and chlorotrimethylsilane (TMCS). The method was validated according to the guidance for bioanalytical method validation of the US Department of Health and Human Services, Food and Drug Administration. The simplicity of the proposed approach makes it a useful procedure for screening/quantifying drugs of abuse in hair specimens from poly-drug abusers.
James, J. N.; Gross, C. D.; Butman, D. E.; Harrison, R. B.
2016-12-01
Dissolved organic matter (DOM) is a crucial conduit for internal cycling of carbon within soils as well as for the transfer of organic matter out of soil and into aquatic systems. Little is known about how the quantity, quality, lability and chemical characteristics of DOM changes in response to human management of forest soils. To examine the processes that release soil organic matter (SOM) into solution, we gathered samples from adjacent native and industrially managed Eucalyptus grandis plantation forests across Sao Paulo State, Brazil and from adjacent old-growth and Douglas-fir (Pseudotsuga menzisii) plantation forests in the coastal Pacific Northwest. Samples from each soil horizon were taken from soil profiles excavated to at least 1.5 m at each site. Water extractable organic matter (WEOM) was extracted twice from each sample using 0.5 M K2SO4 and Milli-Q water to quantify both dissolved and exchange phase organic matter. These extracts were measured for total organic carbon (TOC), 13C and 14C, and chemical characteristics were assessed by fluorescence spectroscopy (EEMs and SUVA254). At the same time, solid phase characteristics of the soil samples were quantified, including bulk density, pH, total carbon and nitrogen, microbial biomass, and 13C and 14C. Characterization of bulk SOM was undertaken by Fourier Transform Infrared Spectroscopy (FTIR) by subtracting mineral matrix spectra of each sample from the bulk spectra. Organic matter lability was assessed by incubations using difference in TOC for WEOM extracts and repeated measurement of CO2 efflux for bulk SOM. All together, these analyses permit a unique snapshot of the natural separation of organic matter from solid into liquid phase through the entire soil profile. Initial results reveal that small but measureable quantities of WEOM may be released from deep B and C horizons in soil, and that this material is labile to microbial decomposition. By identifying differences in SOM and DOM cycling due to
Using a two-step matrix solution to reduce the run time in KULL's magnetic diffusion package
Brunner, T A; Kolev, T V
2010-12-17
Recently a Resistive Magnetohydrodynamics (MHD) package has been added to the KULL code. In order to be compatible with the underlying hydrodynamics algorithm, a new sub-zonal magnetics discretization was developed that supports arbitrary polygonal and polyhedral zones. This flexibility comes at the cost of many more unknowns per zone - approximately ten times more for a hexahedral mesh. We can eliminate some (or all, depending on the dimensionality) of the extra unknowns from the global matrix during assembly by using a Schur complement approach. This trades expensive global work for cache-friendly local work, while still allowing solution for the full system. Significant improvements in the solution time are observed for several test problems.
Feng, Sheng-Ya
2011-01-01
In this paper, we study a class of second order differential operators with quadratic potentials $L$ and its principal part $L_{S}$. Thanks to Hamiltonian formalism and a multiplier technique, we first obtain heat kernel of $L_{S}$, then we, by use of the action function and volume element, solve a matrix Riccati equations and a scalar differential equation which leads us to the heat kernel of $L$ via a probabilistic ansatz. As application, we finally recover and generalise several classical results on celebrated operators.
Tan, S. P.; Kargel, J. S.; Adidharma, H.; Marion, G. M.
2016-12-01
In the extremely cold conditions on Triton, Pluto and other Kuiper Belt Objects, and Titan's tropopause and lower stratosphere, the atmospheres as a whole, not components individually, are subject to freeze into solid phases as solutions, notpure ices. This is in contrast to water ice in Earth's atmosphere, where the atmosphere stays in gaseous phase when water freezes into a solid phase of presumably pure water due to the much higher temperatures involved. A molecular-based thermodynamic model for cryogenic chemical systems, referred to as CRYOCHEM, has been developed to include the phase equilibria involving multi-component solid solutions. Calculations using CRYOCHEM, therefore, can provide us with compositions of solid solutions that are in equilibrium with the gaseous atmosphere. There is no longer a need to assume pure solids conventionally used in modeling, or even as binary (two-component) mixtures, which commonly consider only nitrogen and methane. Two examples will be discussed: (1) on Titan where ethane plays a significant role in precipitation of high-altitude solid aerosols; and (2) on Pluto where carbon monoxide may also play some important role in the sublimation/condensation cycle at the surface and shallow subsurface, e.g., zone of solid-state greenhouse heating. The presence of these third components essentially affects the solid-gas phase equilibria of nitrogen-methane binary system at their respective conditions on Titan and Pluto, the information of which is useful for future modeling, including those on other bodies in the outer Solar System and comets that share similar volatiles.
1992-12-01
AD-A258 804 Final Technical Report Ii Growth, Nitrogen Vacancy Reduction and Solid Solution Formation in Cubic GaN Thin Films and the Subsequent...Technical 6/1/86-12/31/92 4. TITLE AND SUBTITLE Growth, Nitrogen Vacancy Reduction and 5. FUNDING NUMBERS Solid Solution Formation in Cubic GaN Thin...According to the structural and chemical analyses, there is no reason to believe that a homogeneous solid solution close to this composition had
Ros, William; Vignoles, Gérard L.; Germain, Christian
2010-05-01
A numerical tool for the simulation of Chemical Vapor Infiltration of carbon/carbon composites is introduced. The structure of the fibrous medium can be studied by high resolution X-Ray Computed Micro Tomography. Gas transport in various regimes is simulated by a random walk technique whilst the morphological evolution of the fluid/solid interface is handled by a Marching Cube technique. The program can be used to evaluate effective diffusivity and first order reaction rate. The numerical tool is validated by comparing computed effective properties of a straight slit pore with reactive walls to their analytical expression. Simulation of CVI processing of a real complex media is then presented.
Holota, Petr; Nesvadba, Otakar
2015-04-01
In this paper the reciprocal distance is used for generating Galerkin's approximations in the weak solution of Neumann's problem that has an important role in Earth's gravity field studies. The reciprocal distance has a natural tie to the fundamental solution of Laplace's partial differential equation and in the paper it is represented by means of an expansion into a series of oblate spheroidal harmonics. Subsequently, the gradient vector of the reciprocal distance is constructed. In the computation of its components the expansion mentioned above is employed. The paper then focuses on the scalar product of reciprocal distance gradients in two different points and in particular on a series representation of a volume integral of the scalar product spread over an unbounded domain given by the exterior of an oblate spheroid (oblate ellipsoid of revolution). The integral yields the entries of Galerkin's matrix. The numerical interpretation of all the expansions used as well as the respective software implementation within the OpenCL framework is treated, which concerns also a numerical evaluation of Legendre functions of a real and an imaginary argument. In parallel an approximate closed formula expressing the entries of Galerkin's matrix (with an accuracy up to terms multiplied by the square of numerical eccentricity) is derived for convenience and comparison. The paper is added extensive numerical examples that illustrate the approach applied and demonstrate the accuracy of the derived formulas. Aspects related to practical applications are discussed.
Yan, Shaomin; Li, Zhenchong; Wu, Guang
2010-04-01
The understanding of evolutionary mechanism is important, and equally important is to describe the evolutionary process. If so, we would know where the biological evolution will go. At species level, we would know whether and when a species will extinct or be prosperous. At protein level, we would know when a protein family will mutate more. In our previous study, we explored the possibility of using the differential equation to describe the evolution of protein family from influenza A virus based on the assumption that the mutation process is the exchange of entropy between protein family and its environment. In this study, we use the analytical solution of system of differential equations to fit the evolution of matrix protein 1 family from influenza A virus. Because the evolutionary process goes along the time course, it can be described by differential equation. The results show that the evolution of a protein family can be fitted by the analytical solution. With the obtained fitted parameters, we may predict the evolution of matrix protein 1 family from influenza A virus. Our model would be the first step towards the systematical modeling of biological evolution and paves the way for further modeling.
Ait Ouarabi, Mohand; Antonaci, Paola; Boubenider, Fouad; Gliozzi, Antonio S; Scalerandi, Marco
2017-01-07
Alkaline solutions, such as sodium, potassium or lithium silicates, appear to be very promising as healing agents for the development of encapsulated self-healing concretes. However, the evolution of their mechanical and acoustic properties in time has not yet been completely clarified, especially regarding their behavior and related kinetics when they are used in the form of a thin layer in contact with a hardened cement matrix. This study aims to monitor, using linear and nonlinear ultrasonic methods, the evolution of a sodium silicate solution interacting with a cement matrix in the presence of localized cracks. The ultrasonic inspection via linear methods revealed that an almost complete recovery of the elastic and acoustic properties occurred within a few days of healing. The nonlinear ultrasonic measurements contributed to provide further insight into the kinetics of the recovery due to the presence of the healing agent. A good regain of mechanical performance was ascertained through flexural tests at the end of the healing process, confirming the suitability of sodium silicate as a healing agent for self-healing cementitious systems.
Mohand Ait Ouarabi
2017-01-01
Full Text Available Alkaline solutions, such as sodium, potassium or lithium silicates, appear to be very promising as healing agents for the development of encapsulated self-healing concretes. However, the evolution of their mechanical and acoustic properties in time has not yet been completely clarified, especially regarding their behavior and related kinetics when they are used in the form of a thin layer in contact with a hardened cement matrix. This study aims to monitor, using linear and nonlinear ultrasonic methods, the evolution of a sodium silicate solution interacting with a cement matrix in the presence of localized cracks. The ultrasonic inspection via linear methods revealed that an almost complete recovery of the elastic and acoustic properties occurred within a few days of healing. The nonlinear ultrasonic measurements contributed to provide further insight into the kinetics of the recovery due to the presence of the healing agent. A good regain of mechanical performance was ascertained through flexural tests at the end of the healing process, confirming the suitability of sodium silicate as a healing agent for self-healing cementitious systems.
Krebs, Derek; Budynas, Richard G.
A common procedure for performing a cross orthogonality check for the purpose of modal correlation between the test and the finite element analysis results incorporates the Guyan reduction method to obtain a reduced mass matrix. This paper describes a procedure which uses NASTRAN's Generalized Dynamic Reduction solution routine which is much more accurate than the standard Guyan reduction solution and which offers the advantage of not requiring the selection of mdof. Using NASTRAN's DMAP programming methods, a modal reduction of the full analytical mass matrix is performed based on the accelerometer locations and the analytical modal matrix results. The accuracy of the procedure is illustrated in two case studies.
Semianalytical Solutions for Transport in Aquifer and Fractured Clay Matrix System
A three-dimensional mathematical model that describes transport of contaminant in a horizontal aquifer with simultaneous diffusion into a fractured clay formation is proposed. A group of analytical solutions is derived based on specific initial and boundary conditions as well as ...
Fernandes, Paulo R N; Soares, Sandra de A; Nascimento, Ronaldo F; Soares, Jorge B; Cavalcante, Rivelino M
2009-10-01
A method developed for the extraction and analysis of polycyclic aromatic hydrocarbons (PAHs) in the asphalt binder using a matrix solid-phase dispersion (MSPD) and gas chromatography is presented. The MSPD method was proposed as a rapid and easy approach to determining PAHs present in the maltenic phase of asphalt binder extracted through a mechanical shaking and sonication of the material. The recovery rates ranged from 62.77-89.92% (shaking) and from 56.54-93.6% (sonication) with relative standard deviations lower than 8.8%. The study shows that the recovery rates using shaking and sonication extractions are not significantly different at the p asphalt binder from Brazil. The main PAHs found were BbF, BaP, Per, IncdP, DahA, and BghiP, with average concentrations of 10.2-20.7 mg/kg, but the PAHs Ace and Acy were not detected. However, Nap, Fl, Phen, Ant, Flr, Pyr, Chry, BaA, and BkF were present in average concentrations amounting to less than 10 mg/kg. The results showed that the MSPD method is potentially a valuable tool for the determination of PAHs in the asphalt binder.
He, Xiufen; Chen, Lixia; Chen, Xin; Yu, Huamei; Peng, Lixu; Han, Bingjun
2016-12-01
Toxic metals in rice pose great risks to human health. Metal bioaccumulation in rice grains is a criterion of breeding. Rice breeding requires a sensitive method to determine metal content in single rice grains to assist the variety selection. In the present study, four toxic metals of arsenic (As), cadmium (Cd), chromium (Cr) and lead (Pb) in a single rice grain were determined by a simple and rapid method. The developed method is based on matrix solid phase dispersion using multi-wall carbon nanotubes (MWCNTs) as dispersing agent and analyzed by inductively coupled plasma mass spectrometry. The experimental parameters were systematically investigated. The limits of detection (LOD) were 5.0, 0.6, 10 and 2.1 ng g‑1 for As, Cd, Cr, and Pb, respectively, with relative standard deviations (n = 6) of microwave digestion. The amount of sample required was reduced approximately 100 fold in comparison with the microwave digestion. The method has a high application potential for other sample matrices and elements with high sensitivity and sample throughput.
Peng, Li-Qing; Yi, Ling; Yang, Qiu-Cheng; Cao, Jun; Du, Li-Jing; Zhang, Qi-Dong
2017-08-08
A simple, rapid and eco-friendly approach based on matrix solid-phase dispersion microextraction (MSPDM) followed by ultrahigh performance liquid chromatography coupled with electrochemical detection (UHPLC-ECD) was presented for the microextraction and determination of six phenolic acids in a plant preparation (Danshen tablets). The parameters that influenced the extraction performance of phenolic acids were investigated and optimized. The optimal MSPDM conditions were determined as follows: sorbent, using graphene nanoplatelets with sample/sorbent ratio of 1:1, grinding time set at 60 s, and 0.2 mL of water as elution solvent. Under the optimum conditions, the validation experiments indicated that the proposed method exhibited good linearity (r(2) ≥ 0.9991), excellent precision (RSD ≤ 4.57%), and satisfactory recoveries (82.34-98.34%). The limits of detection were from 1.19 to 4.62 ng/mL for six phenolic acids. Compared with other reported methods, this proposal required less sample, solvent and extraction time. Consequently, the proposed method was successfully used to the extraction and determination of phenolic acids in Danshen tablets.
Sun, Xiaoli; Wang, Jincheng; Li, Yun; Yang, Jiajia; Jin, Jing; Shah, Syed Mazhar; Chen, Jiping
2014-09-12
A series of novel dummy molecularly imprinted polymers (DMIPs) were prepared as highly class-selective sorbents for fluoroquinolones. A non-poisonous dummy template, daidzein, was used for the first time to create specific molecular recognition sites for fluoroquinolones in the synthesized polymers. The influence of porogen polarity on dummy molecular imprinting effect was studied. The DMIP prepared using dimethylsulfoxide-acetonitrile (1:1.8, v/v) as porogen achieved the highest imprinting factors (IF) for fluoroquinolones over a range of IF 13.4-84.0. This DMIP was then used for selective extraction of eight fluoroquinolones (fleroxacin, ofloxacin, norfloxacin, pefloxacin, ciprofloxacin, lomefloxacin, enrofloxacin and gatifloxacin) from fish samples based on dummy molecularly imprinted matrix solid-phase dispersion (DMI-MSPD). The extracted fluoroquinolones were subsequently analyzed by high-performance liquid chromatography (HPLC) equipped with a fluorescence detector (FLD). The developed method had acceptable recoveries (64.4-102.7%) and precision (RSDs: 1.7-8.5%, n=5) for determination of fluoroquinolones in fish samples fortified at levels of 10 and 100ngg(-1). The limits of detection (LODs) for identification of eight fluoroquinolones ranged between 0.06 and 0.22ngg(-1). The results demonstrated great potential of the optimized method for sample preparation in routine analysis of trace fluoroquinolones in fish samples. Copyright © 2014 Elsevier B.V. All rights reserved.
Loeffler, Felix F; Foertsch, Tobias C; Popov, Roman; Mattes, Daniela S; Schlageter, Martin; Sedlmayr, Martyna; Ridder, Barbara; Dang, Florian-Xuan; von Bojničić-Kninski, Clemens; Weber, Laura K; Fischer, Andrea; Greifenstein, Juliane; Bykovskaya, Valentina; Buliev, Ivan; Bischoff, F Ralf; Hahn, Lothar; Meier, Michael A R; Bräse, Stefan; Powell, Annie K; Balaban, Teodor Silviu; Breitling, Frank; Nesterov-Mueller, Alexander
2016-06-14
Laser writing is used to structure surfaces in many different ways in materials and life sciences. However, combinatorial patterning applications are still limited. Here we present a method for cost-efficient combinatorial synthesis of very-high-density peptide arrays with natural and synthetic monomers. A laser automatically transfers nanometre-thin solid material spots from different donor slides to an acceptor. Each donor bears a thin polymer film, embedding one type of monomer. Coupling occurs in a separate heating step, where the matrix becomes viscous and building blocks diffuse and couple to the acceptor surface. Furthermore, we can consecutively deposit two material layers of activation reagents and amino acids. Subsequent heat-induced mixing facilitates an in situ activation and coupling of the monomers. This allows us to incorporate building blocks with click chemistry compatibility or a large variety of commercially available non-activated, for example, posttranslationally modified building blocks into the array's peptides with >17,000 spots per cm(2).
Ghani, Milad; Font Picó, Maria Francesca; Salehinia, Shima; Palomino Cabello, Carlos; Maya, Fernando; Berlier, Gloria; Saraji, Mohammad; Cerdà, Víctor; Turnes Palomino, Gemma
2017-03-10
We present for the first time the application of metal-organic framework (MOF) mixed-matrix disks (MMD) for the automated flow-through solid-phase extraction (SPE) of environmental pollutants. Zirconium terephthalate UiO-66 and UiO-66-NH2 MOFs with different size (90, 200 and 300nm) have been incorporated into mechanically stable polyvinylidene difluoride (PVDF) disks. The performance of the MOF-MMDs for automated SPE of seven substituted phenols prior to HPLC analysis has been evaluated using the sequential injection analysis technique. MOF-MMDs enabled the simultaneous extraction of phenols with the concomitant size exclusion of molecules of larger size. The best extraction performance was obtained using a MOF-MMD containing 90nm UiO-66-NH2 crystals. Using the selected MOF-MMD, detection limits ranging from 0.1 to 0.2μgL(-1) were obtained. Relative standard deviations ranged from 3.9 to 5.3% intra-day, and 4.7-5.7% inter-day. Membrane batch-to-batch reproducibility was from 5.2 to 6.4%. Three different groundwater samples were analyzed with the proposed method using MOF-MMDs, obtaining recoveries ranging from 90 to 98% for all tested analytes.
Loeffler, Felix F.; Foertsch, Tobias C.; Popov, Roman; Mattes, Daniela S.; Schlageter, Martin; Sedlmayr, Martyna; Ridder, Barbara; Dang, Florian-Xuan; von Bojničić-Kninski, Clemens; Weber, Laura K.; Fischer, Andrea; Greifenstein, Juliane; Bykovskaya, Valentina; Buliev, Ivan; Bischoff, F. Ralf; Hahn, Lothar; Meier, Michael A. R.; Bräse, Stefan; Powell, Annie K.; Balaban, Teodor Silviu; Breitling, Frank; Nesterov-Mueller, Alexander
2016-06-01
Laser writing is used to structure surfaces in many different ways in materials and life sciences. However, combinatorial patterning applications are still limited. Here we present a method for cost-efficient combinatorial synthesis of very-high-density peptide arrays with natural and synthetic monomers. A laser automatically transfers nanometre-thin solid material spots from different donor slides to an acceptor. Each donor bears a thin polymer film, embedding one type of monomer. Coupling occurs in a separate heating step, where the matrix becomes viscous and building blocks diffuse and couple to the acceptor surface. Furthermore, we can consecutively deposit two material layers of activation reagents and amino acids. Subsequent heat-induced mixing facilitates an in situ activation and coupling of the monomers. This allows us to incorporate building blocks with click chemistry compatibility or a large variety of commercially available non-activated, for example, posttranslationally modified building blocks into the array's peptides with >17,000 spots per cm2.
Xu, Jing-Jing; Yang, Rui; Ye, Li-Hong; Cao, Jun; Cao, Wan; Hu, Shuai-Shuai; Peng, Li-Qing
2016-08-01
In this work, two flavonoid glycosides (neohesperidin and naringin) in lime fruit were effectively extracted by miniaturized matrix solid phase dispersion (MSPD), followed by ultra-performance liquid chromatography-ultraviolet detection. The best results were obtained using Florisil (150mg) as the sorbent and 1-butyl-3-methylimidazolium tetrafluoroborate (0.4mL, 250mM) as the elution solvent. This work represents the first attempt of using ionic liquids as a green eluent for extraction of the investigated compounds in miniaturized MSPD. Compared with the conventional methods, the proposed method is advantageous due to improved enrichment factor and reduced reagent consumption. A good linearity was observed with r(2) values (>0.998). Meanwhile, the method gave acceptable recoveries (90.16-96.47%) for the determination of flavonoids in plant samples. The limits of detection of the two analytes ranged between 4.08 and 5.04μg/g. The results showed that the optimized method has a great potential for sample preparation in routine analysis of complex plant samples.
Thermodynamic Destabilization of Ti-O Solid Solution by H2 and Deoxygenation of Ti Using Mg.
Zhang, Ying; Fang, Zhigang Zak; Sun, Pei; Zhang, Tuoyang; Xia, Yang; Zhou, Chengshang; Huang, Zhe
2016-06-08
Reactive metals including Ti, Zr, Hf, and V, among others, have a strong chemical affinity to oxygen, which makes them difficult to produce and costly to use. It is especially challenging to produce pure or metal alloy powders of these elements when extremely low oxygen content is required, because they have high solubility for oxygen, and the solid solution of these metals with oxygen is often more stable thermodynamically than their oxides. We report a novel thermochemical approach to destabilize Ti(O) solid solutions using hydrogen, thus enabling deoxygenation of Ti powder using Mg, which has not been possible before because of the thermodynamic stability of Ti(O) solid solutions relative to MgO. The work on Ti serves as an example for other reactive metals. Both analytical modeling and experimental results show that hydrogen can indeed increase the oxygen potential of Ti-O solid solution alloys; in other words, the stability of Ti-O solid solutions is effectively decreased, thus increasing the thermodynamic driving force for Mg to react with oxygen in Ti. Because hydrogen can be easily removed from Ti by a simple heat treatment, it is used only as a temporary alloying element to destabilize the Ti-O systems. The thermodynamic approach described here is a breakthrough and is applicable to a range of different materials. This work is expected to provide an enabling solution to overcome one of the key scientific and technological hurdles to the additive manufacturing of metals, which is emerging rapidly as the future of the manufacturing industry.
Raposo, F; de la Rubia, M A; Borja, R; Alaiz, M
2008-07-15
A modified approach to determine the chemical oxygen demand (COD) of solid substrates based on the DIN 38414-S9 standard method is proposed. The adapted procedure is assessed and compared with standard methods widely used for water and wastewater such as the American Public Health Association-American Water Works Association-Water Pollution Control Federation (APHA-AWWA-WPCF) standard methods 5220 B-open reflux (SM-OR) and 5220 D-closed reflux colorimetric (SM-CR). Solutions with high suspended concentration of solids, as well as digestates from an anaerobic reactor, were used during the comparative test. For solid substrates, the COD recovery was about 100% when the proposed method was used. For solutions with solid content higher than 20 g TS L(-1), the recovery was only completed when the proposed method was used, showing that the methods traditionally employed are not very appropriate for samples with the described characteristics. For instance, percentages of COD recovery in the ranges of 77.3-87.1% and 89.4-94.1% were achieved when the SM-OR and SM-CR methods were used, respectively.
Solution of the nonlinear inverse scattering problem by T -matrix completion. II. Simulations
Levinson, Howard W.; Markel, Vadim A.
2016-10-01
This is Part II of the paper series on data-compatible T -matrix completion (DCTMC), which is a method for solving nonlinear inverse problems. Part I of the series [H. W. Levinson and V. A. Markel, Phys. Rev. E 94, 043317 (2016), 10.1103/PhysRevE.94.043317] contains theory and here we present simulations for inverse scattering of scalar waves. The underlying mathematical model is the scalar wave equation and the object function that is reconstructed is the medium susceptibility. The simulations are relevant to ultrasound tomographic imaging and seismic tomography. It is shown that DCTMC is a viable method for solving strongly nonlinear inverse problems with large data sets. It provides not only the overall shape of the object, but the quantitative contrast, which can correspond, for instance, to the variable speed of sound in the imaged medium.
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…
Lexa, D.; Kematick, R.J.; Myers, C.E. [Binghamton Univ. - SUNY, NY (United States). Dept. of Chemistry and Institute for Materials Research
1997-08-01
The activities of cobalt and silicon at 1463 K have been determined across the whole composition range in the Co - Si system, including the {alpha} - Co solid solution, for which no activity data were previously available. Simple and reactive Knudsen effusion mass spectroscopy employed in this work were shown to successfully overcome problems normally encountered in studying high-temperature solid binary systems, such as slow equilibration and low partial pressures of the components. The composition dependence of the cobalt activities within the {alpha} - Co solid solution phase was used to calculate the self-interaction coefficients of silicon in {alpha} - Co: ln {gamma}{sub Si} = 10.4 {+-} 0.2 and {epsilon}{sub Si}{sup (Si)} = 18.6 {+-} 0.8. The regular solution model was shown to be a fairly good description of the {alpha} - Co solid solution, with an energy parameter Z{sub CoSi} of -120 {+-} 5 kJ{center_dot}mol{sup -1}. The results compare well with literature data on similar systems, such as Fe - Si and Ni - Si.
Xiang-Hong, He; Zhao-Lian, Ye; Ming-Yun, Guan; Ning, Lian; Jian-Hua, Sun
2016-02-01
Pr3+-activated barium tungsto-molybdate solid solution phosphor Ba(Mo1-zWz)O4:Pr3+ is successfully fabricated via a facile molten-salt approach. The as-synthesized microcrystal is of truncated octahedron and exhibits deep-red-emitting upon blue light excitation. Powder x-ray diffraction and Raman spectroscopy techniques are utilized to investigate the formation of solid solution phosphor. The luminescence behaviors depend on the resulting composition of the microcrystals with fixed Pr3+-doping concentration, while the host lattices remain in a scheelite structure. The forming solid solution via the substitution of [WO4] for [MoO4] can significantly enhance its luminescence, which may be due to the fact that Ba(Mo1-zWz)O4:Pr3+ owns well-defined facets and uniform morphologies. Owing to its properties of high phase purity, well-defined facets, highly uniform morphologies, exceptional chemical and thermal stabilities, and stronger emission intensity, the resulting solid solution phosphor is expected to find potential applications in phosphor-converted white light-emitting diodes (LEDs). Project supported by the Construction Fund for Science and Technology Innovation Group from Jiangsu University of Technology, China, the Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, China (Grant No. KHK1409), the Priority Academic Program Development of Jiangsu Higher Education Institutions, China, and the National Natural Science Foundation of China (Grant No. 21373103).
An Yuan; Li Li; Wang Jun; Shen Meiqing
2005-01-01
Ce0.6Zr0.4O2 solid solution ultrafine particle was prepared in the cyclohexane/water/OP-10/n-hexanol reversed microemulsion. The quasi-ternary phase diagram investigations showed that the system has narrow W/O type microemulison region, so it is the proper system to prepare Ce0.6Zr0.4O2 solid solution ultrafine particle. Some physical-chemical techniques such as TG/DTA, XRD, BET, and HRTEM are used to characterize the resultant powders. The results show that the fluorite cubic Ce0.6Zr0.4O2 solid solution is obtained at 400 ℃. The surface area is (146.7 m2·g-1), which is higher than the surface area for sol-gel prepared sample (59.5 m2·g-1). HRTEM images indicated that the Ce0.6Zr0.4O2 solid solution ultrafine particle is well-crystallized, narrow size distribution, less agglomeration, within mean size of 5～7 nm.
Takeuchi, T.; Iijima, Y.; Inoue, K.; Wada, H.; Haken, ten B.; Kate, ten H.H.J.; Fukuda, K.; Iwaki, G.; Sakai, S.; Moriai, H.
1997-01-01
Strain effects on critical current densities have been examined for conductors containing nearly stoichiometric Nb3Al filaments with fine grains. The Nb3Al phase in these multifilamentary conductors are prepared by phase transformation from supersaturated Nb(Al) bcc solid solution and show high-fiel
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.
Wang, Zhibing; He, Mengyu; Jiang, Chunzhu; Zhang, Fengqing; Du, Shanshan; Feng, Wennan; Zhang, Hanqi
2015-12-01
Matrix solid-phase dispersion coupled with homogeneous ionic liquid microextraction was developed and applied to the extraction of some sulfonamides, including sulfamerazine, sulfamethazine, sulfathiazole, sulfachloropyridazine, sulfadoxine, sulfisoxazole, and sulfaphenazole, in animal tissues. High-performance liquid chromatography was applied to the separation and determination of the target analytes. The solid sample was directly treated by matrix solid-phase dispersion and the eluate obtained was treated by homogeneous ionic liquid microextraction. The ionic liquid was used as the extraction solvent in this method, which may result in the improvement of the recoveries of the target analytes. To avoid using organic solvent and reduce environmental pollution, water was used as the elution solvent of matrix solid-phase dispersion. The effects of the experimental parameters on recoveries, including the type and volume of ionic liquid, type of dispersant, ratio of sample to dispersant, pH value of elution solvent, volume of elution solvent, amount of salt in eluate, amount of ion-pairing agent (NH4 PF6 ), and centrifuging time, were evaluated. When the present method was applied to the analysis of animal tissues, the recoveries of the analytes ranged from 85.4 to 118.0%, and the relative standard deviations were lower than 9.30%. The detection limits for the analytes were 4.3-13.4 μg/kg.
Pan, X.F. [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi’an 710016 (China); Yan, G., E-mail: gyan@c-nin.com [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi’an 710016 (China); Qi, M. [Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi’an 710016 (China); Cui, L.J. [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Chen, Y.L.; Zhao, Y. [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity and New Energy R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Li, C.S. [Superconducting Materials Center, Northwest Institute for Nonferrous Metal Research, Xi’an 710016 (China); Liu, X.H. [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Feng, Y.; Zhang, P.X. [National Engineering Laboratory for Superconducting Material, Western Superconducting Technologies (WST) Co., Ltd., Xi’an 710018 (China); Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity and New Energy R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Liu, H.J. [Institute of Plasma Physics, Chinese Academy of Sciences (CAS), Hefei 230031 (China); and others
2014-07-15
Highlights: • This paper reported superconducting properties of the powder-in-tube Nb{sub 3}Al wires. • The Nb{sub 3}Al wires were made by using Nb(Al){sub ss} supersaturated solid solution powders. • The Cu-matrix Nb{sub 3}Al superconducting wires have been successfully fabricated. • The transport J{sub c} of Nb{sub 3}Al wires at 4.2 K, 10 T is up to 12,700 A/cm{sup 2}. - Abstract: High-performance Nb{sub 3}Al superconducting wire is a promising candidate to the application of high-field magnets. However, due to the production problem of km-grade wires that are free from low magnetic field instability, the Nb{sub 3}Al wires made by rapid heating, quenching and transformation (RHQT) are still not available to the large-scale engineering application. In this paper, we reported the properties of the in situ powder-in-tube (PIT) Nb{sub 3}Al superconducting wires, which were made by using the mechanically alloyed Nb(Al){sub ss} supersaturated solid solution, as well as the low temperature heat-treatment at 800 °C for 10 h. The results show that Nb{sub 3}Al superconductors in this method possess very fine grains and well superconducting properties, though a little of Nb{sub 2}Al and Nb impurities still keep being existence at present work. At the Nb{sub 3}Al with a nominal 26 at.% Al content, the onset T{sub c} reaches 15.8 K. Furthermore, a series of Nb{sub 3}Al wires and tapes with various sizes have been fabricated; for the 1.0 mm-diameter wire, the J{sub c} at 4.2 K, 10 T and 14 T have achieved 12,700 and 6900 A/cm{sup 2}, respectively. This work suggests it is possible to develop high-performance Cu-matrix Nb{sub 3}Al superconducting wires by directly using the Nb(Al){sub ss} supersaturated solid-solution without the complex RHQT heat-treatment process.
Leathers, Andrew S.; Micha, David A.; Kilin, Dmitri S.
2009-10-01
The interaction of an excited adsorbate with a medium undergoing electronic and vibrational transitions leads to fast dissipation due to electronic energy relaxation and slow (or delayed) dissipation from vibrational energy relaxation. A theoretical and computational treatment of these phenomena has been done in terms of a reduced density matrix satisfying a generalized Liouville-von Neumann equation, with instantaneous dissipation constructed from state-to-state transition rates, and delayed dissipation given by a memory term derived from the time-correlation function (TCF) of atomic displacements in the medium. Two representative applications are presented here, where electronic excitation may enhance vibrational relaxation of an adsorbate. They involve femtosecond excitation of (a) a CO molecule adsorbed on the Cu(001) metal surface and (b) a metal cluster on a semiconductor surface, Ag3Si(111):H, both electronically excited by visible light and undergoing electron transfer and dissipative dynamics by electronic and vibrational relaxations. Models have been parametrized in both cases from electronic structure calculations and known TCFs for the medium, which are slowly decaying in case (a) and fast decaying in case (b). This requires different numerical procedures in the solution of the integrodifferential equations for the reduced density matrix, which have been solved with an extension of the Runge-Kutta algorithm. Results for the populations of vibronic states versus time show that they oscillate due to vibrational coupling through dissipative interaction with the substrate and show quantum coherence. The total population of electronic states is, however, little affected by vibrational motions. Vibrational relaxation is important only at very long times to establish thermal equilibrium.