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101.
We consider an index-guiding silica photonic crystal fiber with a triangular hole pattern and a periodically poled quadratic nonlinearity. By tuning the pitch and the relative hole size, second-harmonic generation with zero group-velocity mismatch is found for any fundamental wavelength above 780 nm. The nonlinear strength is optimized when the fundamental has maximum confinement in the core. The conversion bandwidth allows for femtosecond-pulse conversion, and 4%-180%W(-1)cm(-2) relative efficiencies were found. 相似文献
102.
Feifei Zhang Qi Gao Bang Chen Wei Sun Dongxu Lv 《Phosphorus, sulfur, and silicon and the related elements》2016,191(5):786-789
An efficient one-pot, cyclocondensation of ammonium acetate, 1,2-diphenyl ethanedione, aromatic aldehyde or arylamine, and catalyzed by boric acid is achieved to form multisubstituted imidazole derivatives. Boric acid as green property is harmless to the environment and has improved the yield of multisubstituted imidazole derivatives. Moreover, we have tested the biological activities of imidazole derivatives by the four fungi. And the investigations showed most of imidazole derivatives have antifungal action on four fungus. 相似文献
103.
104.
Thi Bang Tam Dao Kim Ngoc Pham Yi-Lung Cheng Sang Sub Kim Bach Thang Phan 《Current Applied Physics》2014,14(12):1707-1712
The as-deposited WO3 thin films were post-annealed at different temperatures (300 °C and 600 °C) in air to investigate a correlation between crystallinity and switching behavior of WO3 thin films. Associating the results of XRD, FTIR, XPS and FESEM measurements, the annealing-caused crystallinity change contributes to the variation of the switching behaviors of the WO3 thin films. The as-deposited WO3 films with low crystalline structure are preferred for random Ag conducting path, resulting in large switching ratio but fluctuating I–V hysteresis, whereas the annealed WO3 films with crystallized compact structure limits Ag conducting path, favoring the stable I–V hysteresis but small switching ratio. It is therefore concluded that electrochemical redox reaction-controlled resistance switching depends not only on electrode materials (inert and reactive electrodes) but also on crystallinity of host oxide. 相似文献
105.
To search for anti-diabetic and insulin-sensitising natural products, the effect on adipocyte differentiation was investigated by assessing fat accumulation in 3T3-L1 preadipocytes using Oil Red O staining. Fractionation and separation of n-hexane and CHCl? fractions of Morinda officinalis (Rubiaceae) using several chromatographic methods led to the isolation of three anthraquinones, 1,2-dimethoxyanthraquinone (1), alizarin-2-methyl ether (2) and rubiadin-1-methyl ether (3). Among them, alizarin-2-methyl ether (2) showed the strongest enhancing activity, followed by rubiadin-1-methyl ether (3) and 1,2-dimethoxyanthraquinone (1). At a concentration of 100?μM, alizarin-2-methyl ether (2) enhanced adipocyte differentiation by up to 131% (compared to insulin-treated cells). Thus, these compounds could be beneficial in the treatment of diabetes. 相似文献
106.
DL Thomsen T Kurtén S Jørgensen TJ Wallington SB Baggesen C Aalling HG Kjaergaard 《Physical chemistry chemical physics : PCCP》2012,14(37):12992-12999
The gas phase hydrogen abstraction reaction between OH and CY(2)XH, where X = H, F, OH, or NH(2) and Y = H, CH(3) or F, in the absence and presence of a single water molecule is investigated using both density function theory, B3LYP, and explicitly correlated coupled cluster theory, CCSD(T)-F12. We find that a single water molecule could have a catalytic effect at low temperatures possible in laboratory experiments, but does not seem to catalyze these reactions at 298 K, and will not play a role under relevant atmospheric conditions. 相似文献
107.
Qian Wu Myun-Ho Bang Dae-Young Lee Jin-Gyeong Cho Rak-Hun Jeong Sabina Shrestha Kyung-Tae Lee Hae-Gon Chung Eun-Mi Ahn Nam-In Baek 《Chemistry of Natural Compounds》2012,48(2):281-284
Two new indoles, 2-C-β-D-glucopyranosyl-1-methoxyindole-3-acetonitrile (1) and 6-hydroxy-1-methylindole3-acetonitrile (2), along with two known indoles [caulilexin C (3) and arvelexin (4)], were isolated from turnip roots (Brassica rapa ssp. campestris L.). The structures of the compounds were established on the basis of NMR, FAB-MS, and IR spectroscopic data. 相似文献
108.
Choon Kyung Cho Bang Soo Ha Sungkwon Kang 《Journal of Applied Mathematics and Computing》2001,8(2):325-336
Spatial distribution of groundwater contaminant concentration has special characteristics such as approximate symmetric profile, for example, in the transversal direction to groundwater flow direction, a certain ratio in directional propagation distances, etc. To obtain a geophysically appropriate semivariogram which is a key factor in estimation of groundwater contaminant concentration at desired locations, these special characteristics should be considered. Specifically, the concepts of symmetry and ratio are considered in this paper. By applying these two concepts, significant improvement of semivariograms, estimation variances, and final estimation results compared with the ones by conventional approaches which usually do not account for symmetry and ratio are shown using field experimental data. 相似文献
109.
Jun‐Ting Xu Yin‐Bang Zhu Zhi‐Qiang Fan Lin‐Xian Feng 《Journal of polymer science. Part A, Polymer chemistry》2001,39(19):3294-3303
The copolymerization of propylene with 1‐hexene, 1‐octene, 1‐decene, and 1‐dodecene was carried out with silica‐supported rac‐Me2Si(Ind)2ZrCl2 as a catalyst. The copolymerization activities of the homogeneous and supported catalysts and the microstructures of the resulting copolymers were compared. The activity of the supported catalyst was only one‐half to one‐eighth of that of the homogeneous catalyst, depending on the comonomer type. The supported catalyst copolymerized more comonomer into the polymer chain than the homogeneous catalyst at the same monomer feed ratio. Data of reactivity ratios showed that the depression in the activity of propylene instead of an enhancement in the activity of olefinic comonomer was responsible for this phenomenon. We also found that copolymerization with α‐olefins and supporting the metallocene on a carrier improved the stereoregularity and regioregularity of the copolymers. The melting temperature of all the copolymers decreased linearly with growing comonomer content, regardless of the comonomer type and catalyst system. Low mobility of the propagation chain in the supported catalyst was suggested as the reason for the different polymerization behaviors of the supported catalyst with the homogeneous system. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3294–3303, 2001 相似文献
110.
Five novel Schiff's bases p‐tert‐butylcalix[4]arenes have been synthesized in high yields by the reaction of 1,3‐distally disubstituted p‐tert‐butylcalix[4]arene amine (1) with the corresponding aromatic aldehydes, and their cation binding abilities and selectivities with alkali and heavy metal ions have been evaluated by solvent extraction of aqueous metal picrates to show the highest Ag+ extractability for Schiff's base p‐tert‐butylcalix[4]arene (6) and the best Na+/Li+ and Ag+/Ti+ selectivities for Schiff's base p‐tert‐butylcalix[4]arene (4 and 2) over any other calix[4]arene derivatives, respectively. 相似文献