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The first iron complex capable of olefin cis -dihydroxylation in combination with H2O2 provides a functional model for Rieske dioxygenases. Mechanistic studies on the model reaction suggest the participation of an FeIII(η2-OOH) intermediate, with the oxygen atoms coming exclusively from H2O2 (see reaction scheme; L denotes a tris(6-methyl-2-pyridylmethyl)amine ligand, Solv=solvent). The similarities between the model and the enzymes strengthen the proposal that an FeIII–peroxo intermediate is involved in the enzymatic reactions. 相似文献
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多孔硅/多孔氧化铝与PVK复合光致发光特性 总被引:2,自引:1,他引:1
用旋涂法实现了多孔硅、多孔氧化铝与聚乙烯咔唑(PVK)的复合,研究了多孔硅/PVK、多孔氧化铝/PVK复合体系的光致发光性能。PL谱的测试发现,多孔硅/PVK复合体系的PL谱同时具有多孔硅和PVK的发射峰。此外,在485nm的位置出现了一个新峰,讨论了这个峰的来源。而多孔氧化铝与PVK复合后,没有产生新的峰。但多孔氧化铝与PVK复合后,由于多孔氧化铝纳米孔的纳米限制效应使PVK的发光峰出现大幅度蓝移。从多孔硅与多孔氧化铝发光机制的不同出发,讨论了多孔硅、多孔氧化铝与PVK复合后产生不同结果的原因。 相似文献
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Azobenzene-containing TiO2/γ-glycidoxypropyltrimethoxysilane and methyltrimethoxysilane hybrid films are prepared by combining a low temperature sol–gel
process and a spin-coating technique. The trans–cis isomerization of azobenzene small molecules inside organic–inorganic hybrid films is induced by a photoirradiation under
UV light. It is noted that below a baking temperature of 150 °C is necessary for the hybrid films in optical storage or optical
switching applications. The change of the refractive index and thickness of the hybrid films with real-time heating temperature
are observed by using a prism coupling technique. The structural properties of the hybrid films are also characterized and
investigated by thermal gravimetric analysis, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.
The results indicate that the as-prepared hybrid films might allow directly integrating the optical storage or optical switching
devices with the waveguide devices on the same chip. 相似文献
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Anusree Mukherjee Marlène Martinho Dr. Emile L. Bominaar Dr. Eckard Münck Prof. Dr. Lawrence Que Jr. Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(10):1780-1783
Picky ferryl : The complex [Fe(Tp)(BF)] (Tp=hydrotris(3,5‐diphenylpyrazolyl)borate; BF=benzoylformate) reacts with O2 to generate an oxidant (see picture; O red, pink; Fe yellow; N blue; C gray; H white) that oxidizes added hydrocarbons shape‐selectively. Discrimination derives from a cleft formed by two phenyl groups of the Tp ligand, favoring oblate spheroidal substrates.
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The noise suppression techniques with wavelet transform (WT) are widely used in non-destructive testing and evaluation (NDT&E), especially in ultrasonics. Complete reconstruction theory with hard or soft thresholds, reconstruction technique based on the singularities of noise and signal, matched filter with an impulse response, and optimal frequency-to-bandwidth ratio of wavelet technique have all been used to analyze ultrasonic signals for noise suppression. But a more simple and effective technique has been pursued for decades. This paper develops a new technique using WT for the right purpose. In this work, WT is treated as a band-pass filter whose central frequency and frequency bandwidth (CF&FB) are determined by the spectra distribution of an ultrasonic signal captured from real testing situation. For the purpose of matching their CF&FB well, a technique for evaluating the optimal scale of a daughter wavelet is carried out too. By acting this daughter wavelet as a band-pass filter, we can obtain excellent de-noising results, even when the signal to noise ratio (SNR) is below -18 dB. The performance of the technique has been done by ultrasonic signals with computer generated white noises. Finally, the experimental verification is performed on a pipeline specimen with man-made small flaws with good results obtained. The results show that the technique is more suitable for processing heavy noised ultrasonic signals, and it can also be used in automatic flaw detection. 相似文献