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41.
WJ Cho EK Kim MJ Park SU Choi CO Lee SH Cheon BG Choi BH Chung 《Canadian Metallurgical Quarterly》1998,6(12):2449-2458
In this study a series of 3-arylisoquinoline derivatives were synthesized and cytotoxicity against human melanoma tumor cell evaluated, and a three dimensional quantitative structure-activity relationship was investigated using the comparative molecular field analysis (CoMFA). The results suggested that the electrostatic, steric and hydrophobic factors of 3-arylisoquinolines were strongly correlated with the antitumor activity. Considerable predictive ability (cross-validated r2 as high as 0.721) was obtained through CoMFA. 相似文献
42.
H. G. Park A. B. Gokhale P. Kumar R. Abbaschian 《Metallurgical and Materials Transactions B》1990,21(5):845-853
The kinetics and mechanism of absorption/desorption of nitrogen in liquid Nb were investigated in the temperature range of
2470 °C to 2670 °C in samples levitated in a N2/Ar stream with various nitrogen partial pressures. The nitrogen solution reaction in liquid Nb was found to be exothermic,
with the standard enthalpy and entropy of solution of −236.4 ± 23.3 kJ/mol and −-5.3 ± 8.3 J/K · mol, respectively. Above
the threshold flow rate of the N2/Ar stream, the absorption process was determined to be second order with respect to nitrogen concentration, indicating that
the rate-controlling step is either the adsorption of nitrogen molecules on the liquid surface or dissociation of adsorbed
nitrogen molecules into surface-adsorbed atoms. The desorption process was found to be second order as well. At lower flow
rates, however, the absorption rate was found to depend on the gas-phase mass transfer rate. The rate equation for nitrogen
absorption in the range of 2470 °C to 2670 °C is given by
with the value ofQ calculated to be −327.2 ± 20.6 kJ/mol, while nitrogen desorption at 2670 °C follows the relation
相似文献
43.
Lee SH Park T Kim JH Kim CH 《IEEE transactions on visualization and computer graphics》2012,18(7):1135-1145
We address the computational resource requirements of 3D example-based synthesis with an adaptive synthesis technique that uses a tree-based synthesis map. A signed-distance field (SDF) is determined for the 3D exemplars, and then new models can be synthesized as SDFs by neighborhood matching. Unlike voxel synthesis approach, our input is posed in the real domain to preserve maximum detail. In comparison to straightforward extensions to the existing volume texture synthesis approach, we made several improvements in terms of memory requirements, computation times, and synthesis quality. The inherent parallelism in this method makes it suitable for a multicore CPU. Results show that computation times and memory requirements are very much reduced, and large synthesized scenes exhibit fine details which mimic the exemplars. 相似文献
44.
A programmed temperature technique has been developed for the measurement of the self-diffusion coefficients of additives in polymers. This has been applied to the diffusion of three dialkylphthalate plasticizers in poly(vinyl chloride). Values of the self-diffusion coefficients and the calculated activation energies obtained in this way have been compared with values previously obtained from measurements at constant temperature. It has been shown that the programmed temperature technique gives a very rapid method for the estimation of the activation energy of self-diffusion. 相似文献
45.
O Ok Park 《Korean Journal of Chemical Engineering》1986,3(2):153-163
Molecular model approach has been used to predict the dispersion characteristics of flexible polymer chains in confined geometries.
The analysis ranges from the early stage dispersion to the steady Taylor dispersion of the simple linear dumbbell model polymer
chains. For the early stasje dispersion the ray method was applied; an Aris type moments rnothod was useful for the Taylor
dispersion. Two parallel plates were chosen as a confining geometry and the specific initial condition of a point source in
the midway of the gap was chosen for simplicity. It was found that the qualitative difference in dispersion properties of
deformable polymer chains starts from the early stage compared with those of single Brownian particles. And it turns out that
one parameter, which is similar to the relative spacing of the dumbbell to the gap of confining geometries, is useful to see
the dispersion characteristics of the dumbbells. 相似文献
46.
Well-defined Ln2Sn2O7 powders (Ln = La, Sm and Gd) with a phase-pure pyrochlore structure were synthesized by hydrothermal reaction. The catalytic activities of Ln2Sn2O7 powders for methane combustion were measured. Methane oxidation started at 500 °C and increased with oxidation temperature. Catalytic methane combustion is strongly influenced by the presence of oxygen vacancies that form by breaking Sn–O lattice bonds as the temperature increases. Addition of manganese to the rare earth pyrochlores improved methane oxidation activity. Manganese-doped samarium stannate pyrochlore (Sm2Sn1.8Mn0.2O7) shows highest the catalytic activity. Light-off and complete oxidation temperatures were measured at about 400 and 650 °C, respectively. 相似文献
47.
Optimization of reduction potential for electroseparation was studied for the recovery of gold, copper, and lead from acidic
solution. A linear sweep voltammetric method enabled us to determine characteristic reduction potentials for each metal and
the kinetics of the metal deposition indicated by current-voltage curves. In order to precipitate the metal species sequentially,
reduction potentials were examined for the individual and mixed solutions of Au(III), Cu(II), and Pb(II). The three metals
were reasonably well isolated from the mixed solutions such as Cu(II)/ Pb(II) and Au(III)/Cu(II)/Pb(II) in the order of the
corresponding reduction potentials, in particular, the mass transfer controlled reduction potentials, obtained from linear
sweep voltammetry (LSV) measurement. 相似文献
48.
This paper presents a rational method (based on Bayes' Theorem) for transferring information on parameter values from one experiment to another, in situations where the mathematical models for the two experiments share some parameters in common. The uncertainty in the estimates of the parameters, which reflects the experimental error in the initial experiment, is properly transferred as well. The use of the method is demonstrated by applying it to a fairly complicated system, typical in chemical reaction engineering, in which the kinetic parameters in a model for the hydrogenolysis of butane reaction were estimated using data obtained from a bench-scale, integral packed-bed reactor. These parameter estimates were then transferred to a model for a fluidized bed reactor in which the same chemical reaction occurred. Using the fluidized bed data they were updated and two additional parameters in the fluidized bed model were also estimated. This procedure allows a more realistic estimate of the uncertainty in all parameter values in the model for the fluidized bed reactor. 相似文献
49.
Soap‐free emulsion copolymerization of perfluoroalkyl acrylate (FA)/methyl methacrylate (MMA)/n‐butyl acrylate (n‐BA) was carried out in the presence of sodium 2‐acrylamide‐2‐methyl propanesulfonate (AMPSNa) as a reactive surfactant and potassium persulfate (KPS) as an initiator. An analysis of the effects of concentration of AMPSNa, KPS, FA as well as polymerization temperature on the kinetic features (rate of polymerization) and colloidal characteristics (mean particle diameter, particle disperse index, particle numbers, and surface charge density) was followed. NMR, FTIR, AFM, and fluorine‐selective electrode analysis were used to characterize the composition and morphology of the FA copolymers. Both AFM analysis and contact angle measurements strongly implied that the fluorinated segments migrated to the outmost surface and created films with lower surface energy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2438–2444, 2007 相似文献
50.
The effects of estrogen-induced hyperlipidemia on plasma lipid peroxidation, fatty acid composition and osmotic fragility
of erythrocytes in chickens were studied. Young male chickens implanted with estrogen for three wk developed a marked hyperlipidemia.
Plasma levels of triglyceride, cholesterol and phospholipid were elevated 68-, four- and 24-fold, respectively, over controls.
There was also a two-fold increase in plasma lipid peroxidation measured by the thiobarbituric acid test. Vitamin E supplement
(1,000 IU/kg diet) reduced the plasma lipid peroxidation to the control level, but had no effect on the plasma lipid content.
Estrogen-induced hyperlipidemia resulted in changes in the fatty acid composition of membrane lipids of erythrocytes. The
major changes were an increase in oleic acid from 10.0% to 14.2% and a decrease in linoleic acid from 31.3% to 26.0%. The
erytrocytes with an altered membrane fatty acid composition were found to have an increased osmotic fragility. It was apparent
that there was a direct correlation between the oleic acid content and the osmotic fragility of erythrocytes. 相似文献