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991.
Shih‐Sheng Wang Yu‐Hui Chen Jiun‐Yang Chang Tsong‐Long Hwang Chung‐Hsiung Chen Ashraf Taha Khalil Ya‐Ching Shen 《Helvetica chimica acta》2009,92(10):2092-2100
Chemical investigation of the Taiwanese gorgonian coral Junceella juncea resulted in the isolation of four new briarane‐type diterpenoids, juncenolides H, I, J, and K ( 1 – 4 ). Their structures were determined on the basis of spectroscopic analysis, especially 1‐ and 2D‐NMR. The inhibitory effects of compounds 1 – 4 on superoxide‐anion generation and elastase release by human neutrophils were evaluated. 相似文献
992.
Soon-Jae Lee Seung-Gun Chung Dong-Ju Kim Cheol Eui Lee Jae-Woo Choi 《Current Applied Physics》2009,9(6):1323-1325
We proposed a new method from which kinetic sorption parameters can be estimated using aqueous phase concentration versus time data commonly available from adsorption tests. The method relies on the analytical solution that was solved for two-site reversible sorption kinetics based on mass conservation law for solute in a batch reaction system. In order to validate the method, model parameters were compared with those of three-stage kinetic models available in the literature. It was revealed that model parameters of the two-site kinetics could accurately be estimated as much as other model parameters. Advantage of the new method is acquisition of additional parameter, distribution or partitioning coefficient (Kd) frequently used in the analysis of chemical transfer in the solid–liquid interface. 相似文献
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995.
A 1 × 4 polarization and wavelength independent optical power splitter is reported. This device is based on a novel wide-angle low-loss Y-junction structure which can give a theoretical TE junction excess loss of 0.26 dB at a branching angle of 16°. To the best of our knowledge, it is so far the lowest reported loss at such a large angle. The detailed design of the device and its fabrication are described. Our experimental results show the measured TE excess loss to be 1.2 dB and TM excess loss 1.8 dB for the whole splitter over the wavelength between 1.47 μm and 1.57 μm. 相似文献
996.
Hyun Woo Chung 《Applied Surface Science》2006,252(13):4545-4548
New ferroelectric Pb(Zr,Ti)O3-Pb(Mn,W,Sb,Nb)O3 (PZT-PMWSN) thin film has been deposited on a Pt/Ti/SiO2/Si substrate by pulsed laser deposition. Buffer layer was adopted between film and substrate to improve the ferroelectric properties of PZT-PMWSN films. Effect of a Pb(Zr0.52Ti0.48)O3 (PZT) and (Pb0.72La0.28)Ti0.93O3 (PLT) buffer layers on the stabilization of perovskite phase and the suppression of pyrochlore phase has been examined. Role of buffer layers was investigated depending on different types of buffer layer and thickness. The PZT-PMWSN thin films with buffer layer have higher remnant polarization and switching polarization values by suppressing pyrochlore phase formation. The remnant polarization, saturation polarization, coercive field and relative dielectric constant of 10-nm-thick PLT buffered PZT-PMWSN thin film with no pyrochlore phase were observed to be about 18.523 μC/cm2, 47.538 μC/cm2, 63.901 kV/cm and 854, respectively. 相似文献
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Wenhu Han Wenkai Liang Cheng Wang Jennifer X. Wen Chung K. Law 《Proceedings of the Combustion Institute》2021,38(3):3575-3583
This work studies numerically the spontaneous initiation and sustenance of a detonation wave from a hot spot with a nonuniform initial temperature embedded within an H2O2 mixture with and without O3 addition. For the case with either no or just a small amount of O3 addition, a weak reaction wave is auto-ignited at the hot spot, accelerates and then transitions to a pulsating detonation, which propagates along the temperature gradient and quenches as it runs into the cold fresh mixture. However, with increasing O3 addition, the possibility of sustenance of a developing detonation within the gradient is significantly enhanced as it enters the cold mixture. Furthermore, the reduced induction time by O3 addition leads to earlier appearance of the spontaneous reaction wave and detonation formation in the cold mixture, demonstrating that quenching of the detonation is largely related to the instability property of the mixture because the shortened induction time reduces substantially the instability. It is also noted that, for 5%O3 addition, a low-temperature flame produced by the O3 reactions is present in front of the spontaneous reaction wave, inducing a local pressure wave, which facilitates spontaneous initiation and sustains the detonation entering the cold mixture. Moreover, O3 addition renders the critical temperature to induce the minimum spontaneous wave speed higher than the crossover temperature, while they are very close for the case without O3. 相似文献