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121.
122.
Haiming Li Dr. Tailin Wang Dr. Xue Wang Prof. Guangda Li Prof. Jianxing Shen Prof. Jinling Chai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(35):9022-9030
We have successfully synthesized Na2FePO4F/biocarbon nanocomposite hollow microspheres from FeIII precursor as cathodes for sodium-ion batteries through self-assembly of yeast cell biotemplate and sol-gel technology. The carbon coating on the nanoparticle surface with a mesoporous structure enhances electron diffusion into Na2FePO4F crystal particles. The improved electrochemical performance of Na2FePO4F/biocarbon nanocomposites is attributed to the larger electrode−electrolyte contact area and more active sites for Na+ on the surface of hollow microspheres compared with those of Na2FePO4F/C. The Na2FePO4F/biocarbon nanocomposite exhibits a high initial discharge capacity of 114.3 mAh g−1 at 0.1 C, long-cycle stability with a capacity retention of 74.3 % after 500 cycles at 5 C, and excellent rate capability (70.2 mAh g−1 at 5 C) compared with Na2FePO4F/C. This novel nanocomposite hollow microsphere structure is suitable for improving the property of other cathode materials for high-power batteries. 相似文献
123.
Haiming Wang 《Optics and Lasers in Engineering》1997,27(2):191-200
A vibration sensor based on the principle of long-range optical triangulation is designed. The sensor is capable of dynamically gauging displacement with accuracy better than 10 μm. Inspection of both broad-band random vibrations with very low frequencies (pseudo-dc) and high frequency narrow-band tonal vibrations has been realized. 相似文献
124.
Antioxidant compounds from propolis collected in Anhui, China 总被引:1,自引:0,他引:1
The antioxidant activities of the chloroform, ethyl acetate and n-butanol extract fractions from propolis collected in Anhui, China were evaluated in this study. The ethyl acetate fraction contained the highest amount of total phenolics and total flavonoids, and showed the greatest 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging capacities and Ferric Reducing/Antioxidant Power (FRAP). The antioxidant activity of twenty-two compounds isolated from the ethyl acetate fraction was also evaluated using the above-mentioned three assays. The results indicated that phenolics contributed to the antioxidant activity of propolis collected in Anhui, China. Therefore, propolis collected in Anhui, China and its phenolics might be used as a natural antioxidant. 相似文献
125.
The size dependence of optical and electronic properties of semiconductor quantum dots (QDs) have been extensively studied in various applications ranging from solar energy conversion to biological imaging. Core/shell QDs allow further tuning of these properties by controlling the spatial distributions of the conduction-band electron and valence-band hole wave functions through the choice of the core/shell materials and their size/thickness. It is possible to engineer type II core/shell QDs, such as CdTe/CdSe, in which the lowest energy conduction-band electron is largely localized in the shell while the lowest energy valence-band hole is localized in the core. This spatial distribution enables ultrafast electron transfer to the surface-adsorbed electron acceptors due to enhanced electron density on the shell materials, while simultaneously retarding the charge recombination process because the shell acts as a tunneling barrier for the core localized hole. Using ultrafast transient absorption spectroscopy, we show that in CdTe/CdSe-anthraquinone (AQ) complexes, after the initial ultrafast (~770 fs) intra-QD electron transfer from the CdTe core to the CdSe shell, the shell-localized electron is transferred to the adsorbed AQ with a half-life of 2.7 ps. The subsequent charge recombination from the reduced acceptor, AQ(-), to the hole in the CdTe core has a half-life of 92 ns. Compared to CdSe-AQ complexes, the type II band alignment in CdTe/CdSe QDs maintains similar ultrafast charge separation while retarding the charge recombination by 100-fold. This unique ultrafast charge separation and slow recombination property, coupled with longer single and multiple exciton lifetimes in type II QDs, suggests that they are ideal light-harvesting materials for solar energy conversion. 相似文献
126.
在二甲基甲酰胺(DMF)溶剂中,下缘含端基溴的四取代硫桥[4]芳烃1和NaN3反应得到含叠氮端基硫桥[4]芳烃衍生物2,利用点击反应,以CuSO4/VcNa为催化剂,叠氮基硫桥[4]芳烃衍生物2和端基炔蒽醌衍生物3反应合成了以三唑基为连接的蒽醌基硫桥杯芳烃衍生物4,其通过了1H NMR,FT-IR,MS (MALDI-TOF)和元素分析等表征.荧光光谱实验研究了化合物4对金属离子的荧光传感行为,结果表明化合物4对Al3+表现出了很好的荧光响应和良好的选择性.Job实验表明4对Al3+的配比为1∶2;荧光滴定实验表明:在室温条件下,在CHCl3-CH3CN(V∶V=3∶1)溶剂中,4对Al3+作用的键合常数Ks为2670 dm3·mol-1.因此,化合物4有望作为A13+的新型荧光传感器. 相似文献
127.
Haiming Wang 《Fiber and Integrated Optics》2013,32(3):293-308
Abstract An improved method has been implemented to study the refection of optical plane waves from anisotropic and absorbing films. The refection from anisotropic non-absorbing films and from isotropic non-absorbing films can be shown as some special cases. The method in this paper can be applied to almost all kinds of materials involved in optical films and integrated optics studies. Guided waves in the anisotropic and absorbing waveguides are determined, and the prism coupler method is employed to determine refractive indices and thickness of the anisotropic and absorbing films. The results show that when we only couple light beams into films with small effective indices, the effect of the absorption can be neglected. 相似文献
128.
利用真空电子束蒸发技术,通过改变Al的蒸发速率在P型〈1 0 0〉晶向的单晶硅片上制备了两种不同平整度的Al膜,在草酸中对它们分别进行一次阳极氧化,研究Al膜平整度对硅基AAO(多孔硅基氧化铝)有序度的影响.结果表明,硅基AAO的有序度对Al膜的平整度有很大的依赖性,硅基Al膜的平整度越高,所获得的硅基AAO的有序度就越好.另外,对平整度较差的Al膜进行二次阳极氧化可以显著地改善硅基AAO的有序度. 相似文献
129.
三元复合驱碱/表面活性剂/聚合物模拟原油乳状液稳定动力学特性 总被引:2,自引:0,他引:2
基于两相分离的乳状液稳定模型,研究了三元复合驱模拟原油乳状液稳定动力学特性;通过液膜强度和油水界面张力探讨了碱/表面活性剂/聚合物对模拟原油乳状液稳定动力学特性的影响机理。 结果表明,乳状液稳定模型可以很好的评价乳状液的稳定性,并得到乳状液的稳定动力学特性;碱浓度小于900 mg/L有利于乳状液的稳定,碱浓度大于900 mg/L不利于乳状液的稳定;表面活性剂和聚合物浓度的增加使得形成的模拟原油乳状液更加稳定;模拟原油乳状液的稳定作用主要是通过碱、表面活性剂降低油水界面张力并增加油水界面膜强度,聚合物通过提高界面膜强度实现的,三者存在协同效应。 相似文献
130.
Haiming Wang 《Tetrahedron letters》2009,50(19):2200-2203
A class of chiral self-supported catalysts prepared from bis-BINOL ligands and diethyl zinc were successfully applied in the hetereogeneous enantioselective epoxidation of a range of (E)-α,β-unsaturated ketones, affording the corresponding epoxy ketones in high enantioselectivity. The self-supported catalysts were easily recovered from the reaction mixture and were reusable for several consecutive runs. 相似文献