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41.
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An analysis is performed to study the free convection of a dusty‐gas flow along a semi‐infinite isothermal vertical cylinder. The governing equations of the flow problem are transformed into non‐dimensional form and the resulting nonlinear, coupled parabolic partial differential equations have been solved numerically using an implicit finite difference scheme of Crank–Nicholson type. The flow variables such as gas–velocity, dust‐particle velocity and temperature, shearing stress and heat transfer coefficients are calculated numerically for various parameters occurring in the problem. It is observed that due to the presence of dust particles, the gas velocity is found to decrease. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
43.
Abstract A new Monte Carlo sampling scheme, namely High Directional Monte Carlo procedure, is used to obtain the global energy minimum conformations of polypeptides such as enkephalin and melittin. The resultant structures of enkephalin and melittin agree well with previous results of theoretical and experimental studies. Particularly, it is shown that some important parts in the conformation, such as the hinge region that principally determines the tertiary structure of proteins, are correctly described by the new method. The resultant structures are compared with those of other works and their stereoscopic views are shown. 相似文献
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45.
Kyung Ju Lee Muhammad Salman Maqbool Pullur Anil Kumar Kwang Ho Song Heon Phil Ha 《Research on Chemical Intermediates》2013,39(7):3265-3277
Economic production of titanium dioxide (yield >98 %) from ilmenite has been achieved by use of a modified sulfate reduction process. A series of samples were prepared by varying the concentration of titanium dioxide nuclei (0.2, 0.3, and 0.6 %) and further impregnation with antimony and vanadia. The structural and acidic properties of the samples were comprehensively studied by X-ray diffraction (XRD), transmission electron microscopy, BJH pore size distribution, and temperature-programmed desorption of NH3. The XRD results revealed the presence of intense peaks from anatase titanium dioxide. Enhancement of surface area was observed for second-time filtered samples, possibly because of loss of iron from the bulk. As a result, formation of additional micropores was apparent from N2 adsorption and desorption isotherms. Among all the antimony and vanadia-doped samples, the first-time filtered sample with the low concentration of nuclei (0.2 %) had the highest catalytic activity at low temperatures, owing to its larger pore size and abundant acidic species. 相似文献
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Hyun Ook Seo Myung‐Geun Jeong Kwang‐Dae Kim Dae Han Kim Young Dok Kim Dong Chan Lim 《Surface and interface analysis : SIA》2014,46(8):544-549
Degradation behaviors of poly(3‐hexylthiophene‐2,5‐diyl) (P3HT) layers on NiO in the presence of H2O at ambient pressure and dark conditions were studied using X‐ray photoelectron spectroscopy (XPS). Upon H2O exposure at 120 °C, partial oxidation of P3HT together with molecular water incorporation, but with the maintained local ring‐structure, were deduced by XPS. Valence band spectra of XPS evidenced that the partial oxidation of P3HT local structure could alter π‐conjugation systems of P3HT layers, forming additional electronic states close to its original highest occupied molecular orbital. For comparison, P3HT surface was also exposed to O2, and no change in the S 2p and C 1s spectra was found by O2 exposure at 120 °C, implying that H2O plays a major role at the initial stage of P3HT oxidation. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
48.
Keng Yoon Yeong Mohamed Ashraf Ali Chee Wei Ang Soo Choon Tan Hasnah Osman 《Tetrahedron letters》2014
A facile method to synthesize various 1,2-disubstituted benzimidazoles is developed. It is suggested that formation of a Meisenheimer adduct between the substrate, amine, and solvent aids the N-arylation process. The generality of the protocol is demonstrated by the efficient reactions involving numerous substituents ranging from electron-withdrawing groups to electron-donating groups. 相似文献
49.
Jeong Hwa Lee Kwang Pyo Kim Young Hwan Kim Hark Kyun Kim Jinsoo Chung 《Journal of mass spectrometry : JMS》2014,49(5):409-416
Histopathologic diagnosis of renal cell carcinoma (RCC) may sometimes be difficult with small biopsy samples. We applied histology‐directed matrix‐assisted laser desorption/ionization mass spectrometry to RCC samples to evaluate whether and how lipid profiles are different between RCC and normal tissue. We evaluated 59 RCC samples and 24 adjacent normal tissue samples collected from patients who underwent surgery. Five peaks were significantly differently expressed (p < 10?7) between RCCs and adjacent normal tissue samples. C24‐OH sulfatide (ST‐OH {18:1/24:0}[M‐H]?; m/z 906.7 in the negative ion mode) and C22‐OH sulfatide (ST‐OH {18:1/22:0}[M‐H]?; m/z 878.6 in the negative ion mode) were most significantly underexpressed in RCC samples, compared with adjacent normal tissue samples. With 100 random training‐to‐test partitions within these samples, the median prediction accuracy (RCC vs. normal) ranged from 96.3% to 100% at p cutoff values for feature selection ranging from 0.001 to 10?7. Two oncocytoma samples were predicted as normal tissue by five lipids that were differentially expressed between RCC and normal tissue at p < 10?7. Clear‐cell, papillary, and chromophobe RCCs were different in lipid profiles. Permutation p‐ values for 0.632+ bootstrap cross‐validated misclassification rates were less than 0.05 for all the classifiers. Thus, lipid profiles differentiate RCC from normal tissue and may possibly classify the histology of RCC. © 2014 The Authors. Journal of Mass Spectrometry published by John Wiley & Sons, Ltd. 相似文献
50.
Dae Woo Ihm Soo Young Park Cheol Gyu Chang Yoon Sung Kim Hwan Kwang Lee 《Journal of polymer science. Part A, Polymer chemistry》1996,34(14):2841-2850
The effects of transesterification on the miscibility of poly(ethylene terephthalate)/poly(ethylene 2,6-naphthalate) were studied. Blends were obtained by solution precipitation at room temperature to avoid transesterification during blend preparation. The physical blends and transesterified products were analyzed by wide-angle x-ray scattering, differential scanning calorimetry, and nuclear magnetic resonance spectroscopy. It was found that the physical blends are immiscible and when the extent of transesterification reaches 50% of the completely randomized state, independent of blend composition, the blends are not crystallizable and show a single glass transition temperature between those of starting polymers. The interchange reactions were significantly influenced by annealing temperature and time but negligibly by blend composition. © 1996 John Wiley & Sons, Inc. 相似文献