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971.
972.
Na Liu Yuning Chen Fei Lu Yingze Cao Zhongxin Xue Kan Li Prof. Lin Feng Prof. Yen Wei 《Chemphyschem》2013,14(15):3489-3494
A superhydrophilic and underwater superoleophobic Cu(OH)2‐covered mesh with micro‐ and nanoscale hierarchical composite structures is successfully fabricated through a one‐step chemical oxidation of a smooth‐copper mesh. Such mesh, without any further modification, can selectively separate water from oil/water mixtures with high separation efficiency, and possess excellent stability even after 60 uses. This method provides a simple, low‐cost, and scalable strategy for the purification of oily wastewater. 相似文献
973.
Miao Kan Zhifei Wang Yan Xingtao Wang Jeremy L. Hitt Langqiu Xiao Jeffrey M. McNeill Yong Wang Yixin Zhao Thomas E. Mallouk 《Angewandte Chemie (International ed. in English)》2020,59(28):11462-11469
A molecularly thin layer of 2‐aminobenzenethiol (2‐ABT) was adsorbed onto nanoporous p‐type silicon (b‐Si) photocathodes decorated with Ag nanoparticles (Ag NPs). The addition of 2‐ABT alters the balance of the CO2 reduction and hydrogen evolution reactions, resulting in more selective and efficient reduction of CO2 to CO. The 2‐ABT adsorbate layer was characterized by Fourier transform infrared (FTIR) spectroscopy and modeled by density functional theory calculations. Ex situ X‐ray photoelectron spectroscopy (XPS) of the 2‐ABT modified electrodes suggests that surface Ag atoms are in the +1 oxidation state and coordinated to 2‐ABT via Ag?S bonds. Under visible light illumination, the onset potential for CO2 reduction was ?50 mV vs. RHE, an anodic shift of about 150 mV relative to a sample without 2‐ABT. The adsorption of 2‐ABT lowers the overpotentials for both CO2 reduction and hydrogen evolution. A comparison of electrodes functionalized with different aromatic thiols and amines suggests that the primary role of the thiol group in 2‐ABT is to anchor the NH2 group near the Ag surface, where it serves to bind CO2 and also to assist in proton transfer. 相似文献
974.
Antioxidant Properties of Bio-active Substances from Shrimp Head Fermented by Bacillus licheniformis OPL-007 总被引:1,自引:0,他引:1
Xiangzhao Mao Pei Liu Shuai He Jieling Xie Feifei Kan Chunyu Yu Zhaojie Li Changhu Xue Hong Lin 《Applied biochemistry and biotechnology》2013,171(5):1240-1252
Antioxidative activities were found in the culture supernatant of Bacillus licheniformis OPL-007 using shrimp head waste (SHW) as the sole carbon and nitrogen source. After optimizing fermentation conditions, some bio-active substances were determined from the broth. The contents of total phenols, polysaccharides, reducing sugars, free amino acids, and organic acids were 888.80, 402.74, 85.88, 2,061.79, and 5,426.74 mg/l, respectively. Moreover, the fermentation liquid was found rich in eight essential amino acids and non-protein amino acids. The antioxidant activity of the culture supernatant, in terms of the scavenging activity of DPPH radicals, reducing power, and metal chelating ability, was monitored, and the fermentation liquid showed a strong antioxidant capacity. The results indicate that bio-deproteinization of SHW by B. licheniformis OPL-007 can increase its antioxidant activity, and SHW has the potential application in the production of functional foods. 相似文献
975.
聚邻苯二胺膜电极中辣根过氧化物酶的电子传递 总被引:3,自引:0,他引:3
利用酸的电化学固定法制备含辣根过氧化物酶的聚邻苯二胺膜电极,研究其伏安行为及对H2O2还原的生物电催化作用,结果表明,在所述生物电催化反应中酶与聚合物基质 直接电子传递,但对新制的酶电极而言,电聚合时生成并包埋在酶膜中的寡聚体可作为电子传递体加速氧化态酶的再生,根据酶电极电流响应实验曲线的拟合,发现经态酶的再生速度随是极电位的变化表观上符合Tafel关系式,提出了酶反应学参数的测定方法。 相似文献
976.
977.
介绍并表征了一套单法兰集成的低能电子显微镜. 这套显微镜中采用了10o偏转角的磁分束器,从而有利于将其集成到一个10 in的法兰上. 电子光学系统中的一些修正单元被简化,以使其结构简单,容易操作. 样品被置于地电位,方便各静电透镜浮在高电压上. 通过几个实验展示了这台显微镜在典型的低能电子成像、低能电子衍射和光电子成像模式下的性能. 低能电子成像的空间分辨率为51 nm. 利用飞秒激光做光源,相应的非线性光电子发射过程使得这台设备非常适合进行光学近场现象的观察,并获得110 nm的光电子成像空间分辨率. 相似文献
978.
In this paper we generalize the method used to prove the Prime Number Theorem to deal with finite fields, and prove the following
theorem:
$
\pi (x) = \frac{q}
{{q - 1}}\frac{x}
{{\log _q x}} + \frac{q}
{{(q - 1)^2 }}\frac{x}
{{\log _q^2 x}} + O\left( {\frac{x}
{{\log _q^3 x}}} \right),x = q^n \to \infty
$
\pi (x) = \frac{q}
{{q - 1}}\frac{x}
{{\log _q x}} + \frac{q}
{{(q - 1)^2 }}\frac{x}
{{\log _q^2 x}} + O\left( {\frac{x}
{{\log _q^3 x}}} \right),x = q^n \to \infty
相似文献
979.
Dr. Kun Liu Xiangfei Wu Dr. S. B. Jennifer Kan Dr. Seiji Shirakawa Prof. Dr. Keiji Maruoka 《化学:亚洲杂志》2013,8(12):3214-3221
Catalytic asymmetric synthesis of axially chiral o‐iodoanilides and o‐tert‐butylanilides as useful chiral building blocks was achieved by means of binaphthyl‐modified chiral quaternary ammonium‐salt‐catalyzed N‐alkylations under phase‐transfer conditions. The synthetic utility of axially chiral products was demonstrated in various transformations. For example, axially chiral N‐allyl‐o‐iodoanilide was transformed to 3‐methylindoline by means of radical cyclization with high chirality transfer from axial chirality to C‐centered chirality. Furthermore, stereochemical information on axial chirality in o‐tert‐butylanilides could be used as a template to control the stereochemistry of subsequent transformations. The transition‐state structure of the present phase‐transfer reaction was discussed on the basis of the X‐ray crystal structure of ammonium anilide, which was prepared from binaphthyl‐modified chiral ammonium bromide and o‐iodoanilide. The chiral tetraalkylammonium bromide as a phase‐transfer catalyst recognized the steric difference between the ortho substituents on anilide to obtain high enantioselectivity. The size and structural effects of the ortho substituents on anilide were investigated, and a wide variety of axially chiral anilides that possess various functional groups could be synthesized with high enantioselectivities. This method is the only general way to access a variety of axially chiral anilides in a highly enantioselective fashion reported to date. 相似文献
980.
Vertical cavity surface emitting laser transverse mode and polarization control by elliptical holes photonic crystal 下载免费PDF全文
The polarization of traditional photonic crystal (PC) vertical cavity surface emitting laser (VCSEL) is uncontrollable, resulting in the bit error increasing easily. Elliptical hole photonic crystal can control the transverse mode and polarization of VCSEL efficiently. We analyze the far field divergence angle, and birefringence of elliptical hole PC VCSEL. When the ratio of minor axis to major axis b/a=0.7, the PC VCSEL can obtain single mode and polarization. According to the simulation results, we fabricate the device successfully. The output power is 1.7 mW, the far field divergence angle is less than 10°, and the side mode suppression ratio is over 30 dB. The output power in the Y direction is 20 times that in the X direction. 相似文献
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