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81.
J. Moche S. J. Rubaschkin S. M. Gutman S. L. Yovanovitch W. L. Miller B. L. Clarke L. A. Wooten C. Luke A. Winkel und G. Proske 《Fresenius' Journal of Analytical Chemistry》1938,112(7-8):266-271
Ohne Zusammenfassung 相似文献
82.
Stephen D. Bond Jehanzeb Hameed Chaudhry Eric C. Cyr Luke N. Olson 《Journal of computational chemistry》2010,31(8):1625-1635
The Poisson‐Boltzmann equation is an important tool in modeling solvent in biomolecular systems. In this article, we focus on numerical approximations to the electrostatic potential expressed in the regularized linear Poisson‐Boltzmann equation. We expose the flux directly through a first‐order system form of the equation. Using this formulation, we propose a system that yields a tractable least‐squares finite element formulation and establish theory to support this approach. The least‐squares finite element approximation naturally provides an a posteriori error estimator and we present numerical evidence in support of the method. The computational results highlight optimality in the case of adaptive mesh refinement for a variety of molecular configurations. In particular, we show promising performance for the Born ion, Fasciculin 1, methanol, and a dipole, which highlights robustness of our approach. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
83.
Luke Chimuka Titus A.M. Msagati Ewa Cukrowska Hlanganani Tutu 《Journal of chromatography. A》2010,1217(16):2318-2325
The reviews cover important critical parameters that are often optimized in a supported liquid membrane extraction technique in both flat sheet and hollow fibre designs for ionizable organic molecules. Understanding of these parameters can enable one to predict the behavior of the compound before hand and thus reduce the number of optimization experiments. Moreover, less number of experiments can be also generated using statistical techniques which are now becoming more commonly used. Supported liquid membrane extraction optimal parameters such as the conditions of the pH of the acceptor and donor phases should easily be fixed from the pKa values of the compounds. Other parameters, including the polarity of the compound can help to predict the partitioning into the membrane and the behavior of the compound. The influence of parameters such as temperature on the mass transfer in supported liquid membrane depends on the design of the module, experimental design and type of mass transfer controlling the extraction process. 相似文献
84.
Let An be the group of n×n even permutation matrices, and let Vn be the real linear space spanned by An. The purpose of this note is to characterize those linear operators φ on Vn satisfying φ(An)=An. This answers a question raised by C.K. Li, B.S. Tam, N.K. Tsing [Linear Algebra Appl., to appear]. 相似文献
85.
Luke J. Batchelor Emma Fitzgerald Dr. Joanna Wolowska Dr. Joseph J. W. McDouall Prof. Eric J. L. McInnes 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(36):11082-11088
The synthesis, structural and magnetic characterisation of [VIII3O(tmme)2(diimine)2Cl] [diimine=2,2′‐bipyridine ( 1 ) or 1,10‐phenanthroline ( 2 )] and (HNEt3)2[VIII4O(tmme)4] ( 3 ) is reported, in which H3tmme is tris(mercaptomethyl)ethane, MeC(CH2SH)3, the thiol analogue of the famous tripodal alcohol ligands typified by H3thme [tris(hydroxymethyl)ethane, MeC(CH2OH)3]. Complexes 1 and 3 have “T‐shaped” and square topologies, respectively, and the latter is centred on a rare example of a square‐planar oxide. The tri‐thiolate ligands bind the periphery of the clusters and provide such strong antiferromagnetic exchange pathways that in both cases only a single total spin state is occupied up to room temperature, in the absence of metal–metal bonding. Magnetic data, electronic structure calculations and electrochemical data are reported. 相似文献
86.
87.
Nishar Hameed Qipeng Guo Tracey Hanley Yiu‐Wing Mai 《Journal of Polymer Science.Polymer Physics》2010,48(7):790-800
Hydrogen bonding interactions, phase behavior, crystallization, and surface hydrophobicity in nanostructured blend of bisphenol A‐type epoxy resin (ER), for example, diglycidyl ether of bisphenol A (DGEBA) and poly(ε‐caprolactone)‐block‐poly(dimethyl siloxane)‐block‐poly(ε‐caprolactone) (PCL–PDMS–PCL) triblock copolymer were investigated by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, transmission electron microscopy, small‐angle X‐ray scattering, and contact angle measurements. The PCL–PDMS–PCL triblock copolymer consisted of two epoxy‐miscible PCL blocks and an epoxy‐immiscible PDMS block. The cured ER/PCL–PDMS–PCL blends showed composition‐dependent nanostructures from spherical and worm‐like microdomains to lamellar morphology. FTIR study revealed the existence of hydrogen bonding interactions between the PCL blocks and the cured epoxy, which was responsible for their miscibility. The overall crystallization rate of the PCL blocks in the blend decreased remarkably with increasing ER content, whereas the melting point was slightly depressed in the blends. The surface hydrophobicity of the cured ER increased upon addition of the block copolymer, whereas the surface free energy (γs) values decreased with increasing block copolymer concentration. The hydrophilicity of the epoxy could be reduced through blending with the PCL–PDMS–PCL block copolymer that contained a hydrophobic PDMS block. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 790–800, 2010 相似文献
88.
Luke Bartkus Dulasiri Amarasiriwardena Bernardo Arriaza David Bellis Jorge Yaez 《Microchemical Journal》2011,98(2):267-274
Lead exposure has received increased attention over the past few decades since it has been shown to have adverse effects on physical and intellectual development in humans. The use of biological tissues such as blood, teeth, hair, and bone for assessment of lead exposure has been previously demonstrated. While analysis of blood for trace metals provides information concerning recent exposure, hair offers insight into a period of several months, and is preferable since it is non-invasively collected and easily stored. The present study analyzed total of 49 ancient hair samples for lead (PbH) using LA-ICP-MS. Samples belonged to an ancient fisher hunter–gatherer culture called the “Chinchorro,” and who occupied regions of the Atacama Desert on the northern coast of Chile from approximately 5000–1500 B.C. and practiced the first-known form of artificial mummification. Several samples from a post-Chinchorro agricultural community (n = 12) ca. 1000–1400 A.D. were also analyzed. A suite of hair standards was developed using contemporary hair from the same region and was subsequently used to make linear calibration functions for lead determination in single strands of hair using LA-ICP-MS. Three linear scans ranged from 500 to 1000 μm were performed for each sample and signal intensities were normalized over 13C. The distribution of lead in the central medulla in a 100 μm cross-section scan of hair strand demonstrated minimal exogenous contamination. Hair lead (PbH) concentrations ranged between 2.2 μg/g and 12.8 μg/g could be accurately quantified with these standards. Twenty one out of 49 samples (43%) showed PbH concentrations higher than the average value of 5 μg/g for unexposed individuals (range 1.1–228.0 μg/g). Median hair lead concentrations by burial sites and are shown in order of decreasing concentration: Morro (13.8 μg/g) > Iquique (6.6 μg/g) > Azapa (4.5 μg/g) > Yungay (4.1 μg/g) > Camarones (2.7 μg/g). Most of the burial sites showed PbH concentrations greater than the normal value for unexposed individuals and outliers heavily influenced average concentrations. The results suggest that the Chinchorro and later agro-pastoral populations were not widely exposed to naturally elevated lead. 相似文献
89.
Ecevit Bilgili Juan Yepes Luke Stephenson Kerry Johanson Brian Scarlett 《Particle & Particle Systems Characterization》2004,21(4):293-302
In the mechanical characterization of powders using the direct shear testers such as the Jenike shear cell, the existence of a uniform or well‐defined stress field in a powder specimen is assumed. This assumption has not been subjected to any serious scrutiny in the literature. In this study, the normal stress variation in a silica powder was locally determined by locating a pressure‐sensitive TekScan pad at the bottom section of a Jenike shear cell. A computer simulation of the consolidation and pre‐shearing stages of the Jenike test procedure was performed using the Discrete Element Method (DEM). The paper presents both experimental and computational evidence for the existence of a complex stress field in the powder specimen, thus clearly invalidating the long‐standing stress homogeneity assumption in the direct shear testing of powders. The implications of the stress inhomogeneity in terms of the accuracy of the material properties extracted from the Jenike test are also presented. 相似文献
90.
I. Mirebeau M. Hennion M.J.P. Gingras A. Keren K. Kojima M. Larkin G.M. Luke B. Nachumi W.D. Wu Y.J. Uemura I.A. Campbell G.D. Morris 《Hyperfine Interactions》1997,104(1-4):343-348
In the amorphous ( Fe1-x Mn_x)75 P16 B_6 Al_3 alloys, muon and neutron depolarization data, combined with the results of small angle neutron scattering, magnetization and Mössbauer spectroscopy, probe the existence of three distinct magnetic transitions at TC, TK and TF (TF < K < C). 相似文献