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971.
Hayashi T Caranto JD Matsumura H Kurtz DM Moënne-Loccoz P 《Journal of the American Chemical Society》2012,134(15):6878-6884
Flavodiiron proteins (FDPs) play important roles in the microbial nitrosative stress response in low-oxygen environments by reductively scavenging nitric oxide (NO). Recently, we showed that FMN-free diferrous FDP from Thermotoga maritima exposed to 1 equiv NO forms a stable diiron-mononitrosyl complex (deflavo-FDP(NO)) that can react further with NO to form N(2)O [Hayashi, T.; Caranto, J. D.; Wampler, D. A; Kurtz, D. M., Jr.; Mo?nne-Loccoz, P. Biochemistry 2010, 49, 7040-7049]. Here we report resonance Raman and low-temperature photolysis FTIR data that better define the structure of this diiron-mononitrosyl complex. We first validate this approach using the stable diiron-mononitrosyl complex of hemerythrin, Hr(NO), for which we observe a ν(NO) at 1658 cm(-1), the lowest ν(NO) ever reported for a nonheme {FeNO}(7) species. Both deflavo-FDP(NO) and the mononitrosyl adduct of the flavinated FPD (FDP(NO)) show ν(NO) at 1681 cm(-1), which is also unusually low. These results indicate that, in Hr(NO) and FDP(NO), the coordinated NO is exceptionally electron rich, more closely approaching the Fe(III)(NO(-)) resonance structure. In the case of Hr(NO), this polarization may be promoted by steric enforcement of an unusually small FeNO angle, while in FDP(NO), the Fe(III)(NO(-)) structure may be due to a semibridging electrostatic interaction with the second Fe(II) ion. In Hr(NO), accessibility and steric constraints prevent further reaction of the diiron-mononitrosyl complex with NO, whereas in FDP(NO) the increased nucleophilicity of the nitrosyl group may promote attack by a second NO to produce N(2)O. This latter scenario is supported by theoretical modeling [Blomberg, L. M.; Blomberg, M. R.; Siegbahn, P. E. J. Biol. Inorg. Chem. 2007, 12, 79-89]. Published vibrational data on bioengineered models of denitrifying heme-nonheme NO reductases [Hayashi, T.; Miner, K. D.; Yeung, N.; Lin, Y.-W.; Lu, Y.; Mo?nne-Loccoz, P. Biochemistry 2011, 50, 5939-5947 ] support a similar mode of activation of a heme {FeNO}(7) species by the nearby nonheme Fe(II). 相似文献
972.
紧致方法对流动换热及静态分岔的模拟 总被引:1,自引:0,他引:1
发展了基于投影法的紧致方法求解流动换热问题,对顶盖驱动流和侧壁加热的方腔内自然对流换热问题进行了数值模拟。与其它传统方法相比,紧致方法能在较少的网格结点下获得精度较高的计算结果。进一步,采用所发展的紧致方法对不同工况下的Rayleigh-Benard对流及其静态分岔现象进行了数值模拟。数值计算结果表明当长宽比变大时,底部努塞尔数会有小幅度增加。当长宽比为8时,用所发展的紧致方法不同的初场可以得出三种不同的流场和温度场。与基于QUICK格式的SIMPLE算法相比,所发展的紧致方法可以多预测一种静态分岔现象。 相似文献
973.
Perturbation method of studying the EI Nifio oscillation with two parameters by using the delay sea-air oscillator model 下载免费PDF全文
The EI Nio-southern oscillation (ENSO) is an interannual phenomenon involved in tropical Pacific oceanatmosphere interactions. In this paper, we develop an asymptotic method of solving the nonlinear equation using the ENSO model. Based on a class of the oscillator of the ENSO model, a approximate solution of the corresponding problem is studied employing the perturbation method. 相似文献
974.
S. H. Wu M. F. Lo Z. Y. Chen T. W. Ng X. Hu H. W. Mo C. Wu W. L. Li C. S. Lee 《固体物理学:研究快报》2012,6(3):129-131
We have demonstrated a simple near‐infrared (NIR) photodetector (PD) based on charge transfer complex (CTC) formed in molybdenum trioxide (MoO3) doped N,N′‐di(naphthalene‐1‐yl)‐N,N′‐diphenyl‐benzidine (NPB), which shows a photocurrent of about 0.35 A/cm2 at –3 V under 980 nm illumination. The existence of CTC formation promotes photocurrent generation which is investigated by comparison with MoO3 doped 2‐methyl‐9,10‐di(2‐naphthyl)anthracene (MADN) film which has no CTC absorption. It can be evolved that this kind of simple‐structure photodetector has potential application in the near‐infrared (NIR) detection area. It is shown in this Letter that although both MoO3 and NPB have larger energy gaps of about 3 eV and weak absorption in the NIR region, the charge transfer complexes formed by mixing the two materials show an extra absorption band and good photoelectric response in the NIR region.
975.
Shen Z Ni Z Mo S Wang J Zhu Y 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(16):4859-4865
Give me a ring? An efficient approach has been developed for the intramolecular decarboxylative coupling of arene carboxylic acids/esters with aryl bromides catalyzed by palladium (see scheme). From a synthetic viewpoint, this method is highly attractive because the catalyst loading is low, the optimized reaction conditions are mild, and the substrate scope is broad. 相似文献
976.
S. Li G. Fang H. Huang H. Long H. Wang X. Mo B. Dong X. Zhao 《Applied physics. B, Lasers and optics》2012,107(2):497-502
n-ZnO:Al/n ?-ZnO/i-MgO/n-GaN heterostructured diodes have been fabricated by radio frequency magnetron sputtering. The electroluminescence (EL) of the n-ZnO:Al/n ?-ZnO/i-MgO/n-GaN diodes has been investigated. All EL spectra are dominated by ultraviolet (UV) emission peaked at around 368 nm. However, EL performances of the devices can be tuned through controlling the electrical parameters of ZnO:Al films. With the variation of the ZnO:Al films, EL spectra could evolve into random lasing action from conventional EL. The electrical parameters of the corresponding ZnO:Al films were researched, and the related UV emission mechanism is discussed in terms of the energy-band theory of the heterojunctions. 相似文献
977.
978.
对高功率激光系统采用宽带激光消除菲涅耳衍射问题进行了研究,指出只有数百nm的宽带啁啾光脉冲才对近场衍射有一定的平滑作用,数nm的宽带啁啾光脉冲对近场衍射几乎没有平滑作用;同时,还对宽带啁啾光的B积分表征方式和最快增长频率问题进行了研究,并与原型装置上开展的窄带脉冲、宽带啁啾堆积脉冲的非线性实验结果进行了对比研究,指出以最大B积分或加权B积分反映非线性自聚焦更为准确。研究还表明,在数nm,ns情况下最快增长频率与窄带激光脉冲的差别不大。 相似文献
979.
A class of differential-difference reaction diffusion equations initial boundary problem with a small time delay is considered. Under suitable conditions and by using method of the stretched variable, the formal asymptotic solution is constructed. And then, by using the theory of differential inequalities the uniformly validity of solution is proved. 相似文献
980.
Metal-induced crystallization method is one of the favorable non-laser crystallization methods for thin-film transistors in large-area displays. However, it is necessary to reduce metal contamination in the film to lower leakage current for the device applications. A new two-step crystallization method, consisting of a nucleation step by AlCl3 vapor-induced crystallization and a grain growth step by a pulsed rapid thermal annealing, has been proposed to increase the grain size and reduce the residual metal contamination in crystallized poly-Si films. The grain size of the poly-Si film crystallized by the VIC + PRTA two-step crystallization process was as large as 70 μm. Furthermore, the Al concentration in the poly-Si film was reduced by two orders of magnitude from 1 × 1020 cm?3 by VIC only process to 1.4 × 1018 cm?3 by the two-step process. As a result, the minimum leakage current of poly-Si TFTs using the poly-Si film prepared by the two-step process was reduced from 1.9 × 10?10 A/μm to 2.8 × 10?11 A/μm at a drain voltage of 5 V, without carrier mobility degradation. 相似文献