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131.
132.
Amit S. Tiwary 《Molecular physics》2013,111(19):2063-2070
Of the four plausible isomeric structures of the mesitylene–ICl charge transfer (CT) complex, the most feasible one was determined by a detailed ab initio and DFT study at the HF, B3LYP and MPW1PW91 levels using the 6-31++G(d,p) basis set. Potential energy surface scans followed by frequency calculation and full optimization revealed that the I–Cl bond, with its I atom oriented towards the aromatic ring, stands vertically above an unsubstituted C-atom, being inclined at about 6° to the C 3-axis. Complexation increases the I–Cl bond length. Correction for basis set superposition error through a counterpoise calculation yields a binding energy close to the experimental value. The electronic CT transition energy (hν CT) with this ground-state structure as input was calculated in vacuo by the CIS method and in carbon tetrachloride medium by the TDDFT method under the polarizable continuum model. In a similar way the values of hν CT were calculated for complexes of ICl with p-xylene, durene and hexamethylbenzene. Throughout the series of methylbenzene complexes, the TDDFT-calculated values of hν CT were less than the experimental values and such underestimation may be attributed to the inherent difficulties of DFT to take into account long-range interactions. However, the trend of the variation of hν CT with the number and position of methyl groups in the series was reasonably similar to the trend followed by the experimental CT transition energies. 相似文献
133.
《应用有机金属化学》2017,31(10)
[Pd(L1)(C,N)]CF3SO3 and [Pd(L2)(C,N)]CF3SO3 (L1 = 2,2′ ‐bipyridine, L2 = 1,10‐phenanthroline and C,N = benzylamine) novel orthopalladated complexes have been synthesized and characterized using various techniques. The binding of the complexes with native calf thymus DNA (CT‐DNA) was monitored using UV–visible absorption spectrophotometry, fluorescence spectroscopy and thermal denaturation studies. Our results indicate that these complexes can strongly bind to CT‐DNA via partial intercalative mode. In addition, fluorescence spectrometry of bovine serum albumin (BSA) with the complexes shows that the fluorescence quenching mechanism of BSA is a static process. The results of site‐competitive replacement experiments with specific site markers clearly indicate that the complexes bind to site I of BSA. Notably, the complexes exhibit significant in vitro cytotoxicity against two human cancer cell lines (Jurkat and MCF‐7) with IC50 values varying from 37 to 53 μM. Finally, a molecular docking experiment effectively proves the binding of the Pd(II) complexes to DNA and BSA. 相似文献
134.
Mikhail Reibarkh Thomas P. Wyche Josep Saurí Tim S. Bugni Gary E. Martin R. Thomas Williamson 《Magnetic resonance in chemistry : MRC》2015,53(12):996-1002
Utilization of 2H, 13C, and 15N isotopically labeled proteins and peptides is now routine in biomolecular NMR investigations. The widespread availability of inexpensive, uniformly 13C enriched glucose now makes it possible to isolate uniformly 13C labeled natural products from microbial fermentation. We now wish to describe an approach for the rapid structural characterization of uniformly 13C labeled natural products that avoids the pitfalls of relying on parameters typically employed in biomolecular NMR studies. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
135.
Pacelli L. J. Zitha Quoc P. Nguyen Peter K. Currie Marten A. Buijse 《Transport in Porous Media》2006,64(3):301-313
We investigate the development foam in granular porous media and the subsequent flow of the surfactant solution, where the
fluid fraction variations are visualized and quantified using X-ray computed tomography. It is found that foam flows in a
front like manner leading to a residual liquid fraction of 0.18±0.01, far from the inlet surface of the porous sample. A desaturation
backward wave is also observed during foam development. We provided direct evidence that the flow of surfactant solution in
porous media containing foam gives rise to superposition of a drainage wave and a characteristic viscous fingering pattern.
In the wave the liquid fraction ranges from the above residual value to nearly 0.25±0.01. The liquid fraction associated with
the viscous fingering decays as a function of distance but the inlet value increases up to 0.06±0.01. Certain ideas about
the physics of foam flow in porous media are revised in the light of our findings. 相似文献
136.
137.
In the present paper, three dimensional analyses of some general constraint parameters and fracture parameters near the crack
tip. of Mode I CT specimens in two different thicknesses are carried out by employing ADINA program. The results reveal that
the constraints along the thickness direction are obviously separated into two parts: the keeping similar high constraint
field (Z1) and rapid reducing constraints one (Z2). The two fields are experimentally confiremed to correspond to the smooth region and the shear lip on the fracture face
respectively. So the three dimensional stress structure of Mode I specimens can be derived through discussing the two fields
respectively. The distribution of the Crack Tip Opening Displacement (CTOD) along the thickness direction and the three dimensional
distribution of the void growth ratio (Vg) near the crack tip are also obtained. The two fracture parameters are in similar trends along the thickness direction, and
both of them can reflect the effect of thickness and that of the loading level to a certain degree. 相似文献
138.
139.
Radiation dose is an important performance indicator of a dedicated breast CT (DBCT). In this paper, the method of putting thermoluminescent dosimeters (TLD) into a breast shaped PMMA phantom to study the dose distribution in breasts was improved by using smaller TLDs and a new half-ellipsoid PMMA phantom. Then the weighted CT dose index (CTDIw) was introduced to average glandular assessment in DBCT for the first time and two measurement modes were proposed for different sizes of breasts. The dose deviations caused by using cylindrical phantoms were simulated using the Monte Carlo method and a set of correction factors were calculated. The results of the confirmatory measurement with a cylindrical phantom (11 cm/8 cm) show that CTDIw gives a relatively conservative overestimate of the average glandular dose comparing to the results of Monte Carlo simulation and TLDs measurement. But with better practicability and stability, the CTDIw is suitable for dose evaluations in daily clinical practice. Both of the TLDs and CTDIw measurements demonstrate that the radiation dose of our DBCT system is lower than conventional two-view mammography. 相似文献
140.
基于计算机层析成像(CT)技术的梁山慈竹密度检测研究 总被引:2,自引:0,他引:2
密度是竹材重要的物理指标之一,与竹材的许多物理力学性能紧密相关。采用计算机层析成像(CT)技术,对2-5年生梁山慈竹(Dendroclamus farinosus)的密度时空变异特性进行了系统研究;利用正交试验设计确定了适宜的扫描参数,对其气干密度(Y)与相对应的CT值(X)之间的相关性进行分析研究,建立了线性回归模型(Y=0.001 X+1.148)并验证了该模型的准确性,得出两者之间存在着线性关系;同时利用模型计算出梁山慈竹径向和纵向的密度变化规律。为实现梁山慈竹密度的精准高效检测提供了新方法,也为深入研究竹材的材性和构造提供了新思路。 相似文献