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排序方式: 共有690条查询结果,搜索用时 15 毫秒
681.
Chi-Nung Hsiao M. Robert Leanna Lakshmi Bhagavatula Edwin De Lara Thomas M. Zydowsky Bruce W. Horrom 《合成通讯》2013,43(22):3507-3517
Efficient syntheses of N-(tert-butoxycarbonyl)-3-(4-thiazolyl)-L-alanine (11) are described. 相似文献
682.
Marino MJ Hsiao E Chen Y Eryilmaz OL Erdemir A Kim SH 《Langmuir : the ACS journal of surfaces and colloids》2011,27(20):12702-12708
The friction behavior of diamond-like carbon (DLC) is very sensitive to the test environment. For hydrogen-rich DLC tested in dry argon and hydrogen, there was always an induction period, so-called "run-in" period, during which the friction coefficient was high and gradually decreased before DLC showed an ultralow friction coefficient (less than 0.01) behavior. Regardless of friction coefficients and hydrogen contents, small amounts of wear were observed in dry argon, hydrogen, oxygen, and humid argon environments. Surprisingly, there were no wear or rubbing scar on DLC surfaces tested in n-pentanol vapor conditions, although the friction coefficient was relatively high among the five test environments. Ex situ X-ray photoelectron and near-edge X-ray absorption fine-structure spectroscopy analyses failed to reveal any differences in chemical composition attributable to the environment dependence of DLC friction and wear. The failure of getting chemical information of oxygenated surface species from the ex situ analysis was found to be due to facile oxidation of the DLC surface upon exposure to air. The removal or wear of this surface oxide layer is responsible for the run-in behavior of DLC. It was discovered that the alcohol vapor can also prevent the oxidized DLC surface from wear in humid air conditions. 相似文献
683.
Pore-spanning lipid membrane under indentation by a probe tip: a molecular dynamics simulation study
Huang CH Hsiao PY Tseng FG Fan SK Fu CC Pan RL 《Langmuir : the ACS journal of surfaces and colloids》2011,27(19):11930-11942
We study the indentation of a free-standing lipid membrane suspended over a nanopore on a hydrophobic substrate by means of molecular dynamics simulations. We find that in the course of indentation the membrane bends at the point of contact and the fringes of the membrane glide downward intermittently along the pore edges and stop gliding when the fringes reach the edge bottoms. The bending continues afterward, and the large strain eventually induces a phase transition in the membrane, transformed from a bilayered structure to an interdigitated structure. The membrane is finally ruptured when the indentation goes deep enough. Several local physical quantities in the pore regions are calculated, which include the tilt angle of lipid molecules, the nematic order, the included angle, and the distance between neighboring lipids. The variations of these quantities reveal many detailed, not-yet-specified local structural transitions of lipid molecules under indentation. The force-indentation curve is also studied and discussed. The results make a connection between the microscopic structure and the macroscopic properties and provide deep insight into the understanding of the stability of a lipid membrane spanning over nanopore. 相似文献
684.
Jr-Chiuan Chang Amitabha Datta Ching-Sheng Hsiao 《Journal of organometallic chemistry》2011,696(23):3673-3680
A series of aluminum compounds containing tridentate pyrrolyl ligands were obtained from related aluminum dihydride compounds via protonolysis. Treatment of tetranuclear aluminum compound [C4H2N{2,5-(CH2NMe2)2}Al2H5]2 (1) with two equivalents of [C4H3N{2,5-(CH2NMe2)2}] in methylene chloride at 0 °C led to the formation of [C4H2N{2,5-(CH2NMe2)2}]AlH2 (2). Similarly, when the deuterated aluminum compound 1D was used, the corresponding aluminum compound [C4H2N{2,5-(CH2NMe2)2}]AlD2 (2D) could be isolated. The reaction of 2 with one or two equivalents of phenylethyne, triphenylmethanethiol, 2,6-diisopropylaniline, or triphenylsilanol generated mononuclear aluminum compounds [[C4H2N{2,5-(CH2NMe2)2}]AlRR′ (3, R = -CCPh, R′ = H; 4, R = R′ = -CCPh; 5, R = -SCPh3, R′ = H; 6, R = R′ = -SCPh3; 7, R = -NH(2,6-iPr2Ph), R′ = H; 8, R = R′ = -NH(2,6-iPr2Ph); 9, R = -OSiPh3, R′ = H; 10, R = R′ = -OSiPh3). Related Al-D compounds of 3, 5, 7 and 9 were also synthesized and corresponding IR spectroscopic data well matched in comparison of the stretching frequencies of Al-H and Al-D. The molecular structures of 2D, 4, 5, 5D, 7, and 10 have been determined by X-ray crystallography. Compounds 2, 5, and 7 initiated the ring-opening polymerization of ?-caprolactone and produced high-molecular weight of poly-?-caprolactone. 相似文献
685.
The channel is the only kinematically allowed baryonic D decay. It proceeds solely through the W-annihilation topology. Hence, a recent observation of this mode by CLEO will shed light on the dynamics of W-annihilation. At the short-distance level, its branching ratio is very small, of order 10−6, owing to chiral suppression. It receives long-distance contributions through final-state scattering of the leading tree and color-suppressed amplitudes. Assuming that the long-distance enhancement of W-annihilation in the baryonic D decay is similar to that in the mesonic decay, where the latter can be obtained from the analysis of the diagrammatic approach, we find that becomes visible. The observation of this baryonic D decay implies the dynamical enhancement of the W-annihilation topology in the decay. 相似文献
686.
利用自制TiO2纳米粒子研究敏化染敏太阳能电池. 使用自制的旋转涂布加热平台装置将产出的TiO2粒子均匀的涂布在ITO导电玻璃上形成薄膜,浸泡于N-719 染料中12小时以上作为DSSCs的光电极
元件,最后完成染料敏化太阳能电池的系统组装并进行光电转换效率测量. 实验结果表明,放电过程产出的TiO2纳米粒子具有锐钛矿晶相,粒径尺寸可控制在20~70 nm,粒子表面电位约为-30 mV,是稳定的纳米悬浮夜. 添加0.5 mL 的Triton X-100在导电玻璃表面上,利用的旋转涂布加热到22 oC可以制得厚度均匀缜密的薄膜结构,不但粒子不受到热处理效应与介面活性剂的影响而发生晶相改变,并且薄膜也有良好的染料吸附效果. 较厚二氧化钛薄膜的光电极会提升敏化染敏太阳能电池的效率. 实验结果得知,以15 μm的二氧化钛薄膜组装DSSCs测得最高效率2.15%,但是当薄膜厚度超过15 μm 则会导致开路电压与充填因子逐渐下降,光电转换效率变差. 相似文献
687.
Chien-Hsiu Li Ming-Hsien Chan Yu-Chan Chang Michael Hsiao 《Molecules (Basel, Switzerland)》2023,28(1)
Molecular biology applications based on gold nanotechnology have revolutionary impacts, especially in diagnosing and treating molecular and cellular levels. The combination of plasmonic resonance, biochemistry, and optoelectronic engineering has increased the detection of molecules and the possibility of atoms. These advantages have brought medical research to the cellular level for application potential. Many research groups are working towards this. The superior analytical properties of gold nanoparticles can not only be used as an effective drug screening instrument for gene sequencing in new drug development but also as an essential tool for detecting physiological functions, such as blood glucose, antigen-antibody analysis, etc. The review introduces the principles of biomedical sensing systems, the principles of nanomaterial analysis applied to biomedicine at home and abroad, and the chemical surface modification of various gold nanoparticles. 相似文献
688.
Sheng-Yen Hsiao Chih-Hsin Tang Po-Chun Chen Tien-Huang Lin Chia-Chia Chao 《Molecules (Basel, Switzerland)》2022,27(24)
Melatonin, a naturally biosynthesized molecule secreted by the pineal gland, exhibits antitumor activities against several different types of cancer. The mechanisms of action of melatonin against tumor progression involve cellular apoptosis, antimetastatic activity, antioxidant and mutagenic effects, antiangiogenic activity, and the restoration of cancer immune surveillance. Melatonin has anticancer activity when administered alone or in combination with standard chemotherapeutic agents, with measurable improvements seen in the clinical endpoints of tumor regression and patient survival. However, scant clinical evidence supports the use of melatonin in bladder cancer treatment. Our study has found that melatonin treatment suppresses the bladder cancer cell migratory ability by inhibiting the epithelial-mesenchymal transition (EMT) process, which appears to be linked to melatonin-induced decreases in bladder cancer cell autophagy. Finally, an evaluation of in vivo melatonin-induced antitumor effects in an orthotopic animal model of bladder cancer indicated that melatonin treatment slightly prolonged the survival of tumor-bearing mice. Our study offers novel insights into the use of melatonin in bladder cancer treatment. 相似文献
689.
Chung-Hsiung Huang Shun-Yuan Hsiao Yung-Hsiang Lin Guo-Jane Tsai 《Molecules (Basel, Switzerland)》2022,27(24)
Although citrus peel is a waste material, it contains a variety of bioactive components. As our preliminary findings showed that citrus peels fermented with Saccharomyces cerevisiae T1 contained increased levels of anti-obesity flavonoids, the objective of this study was to prepare fermented citrus peel and to investigate its effect on ameliorating obesity in Sprague Dawley (SD) rats fed with a high-fat diet (HFD). After fermentation, the amounts of limonene, nobiletin and 3-methoxynobiletin in citrus peel were markedly increased. SD rats were fed with an HFD for 10 weeks, followed by fermented citrus peel-containing HFD (0.3% or 0.9% w/w) for 6 weeks. Compared with those fed with an HFD alone, lower levels of body weight, visceral fat, body fat percentage, blood triglyceride, total cholesterol, low-density lipoprotein, malondialdehyde and hepatic adipose accumulation were observed in rats fed with fermented citrus peel. In parallel, hepatic levels of acetyl-CoA carboxylase and fatty acid synthase were diminished, and the level of hormone sensitivity lipase in visceral fat was elevated. These results reveal fermented citrus peel is a promising natural product with beneficial effects of alleviating HFD-induced obesity. 相似文献
690.