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81.
以往毫米波被动探测中以平面金属目标代替立体金属目标(如装甲目标),而平面金属目标的探测信号又和地面积水的探测信号非常相似,所以导致这三种目标难以分辨。针对这一问题,从毫米波被动探测平面金属、积水、装甲目标探测信号的基本理论出发,通过建立目标模型、推导天线温度计算模型,仿真得到了这三种目标的探测信号,查找信号差异并分析总结了造成差异的根源。仿真结果证实了分析的正确性和有效性,为地面装甲目标识别算法的研究提供了必要的理论支撑和分析依据。 相似文献
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83.
Dr. Sven O. Krabbenborg Prof. Dr. Jurriaan Huskens 《Angewandte Chemie (International ed. in English)》2014,53(35):9152-9167
This review surveys recent developments in the field of electrochemically generated gradients. The gradual variation of properties, which is a key characteristic of gradients, is of eminent importance in technology, for example, directional wetting, as well as biology, for example, chemotaxis. Electrochemical techniques offer many benefits, such as the generation of dynamic solution and surface gradients, integration with electronics, and compatibility with automation. An overview is given of newly developed methods, from purely electrochemical techniques to the combination of electrochemistry with other methods. Electrochemically fabricated gradients are employed extensively for biological and technological applications, such as high‐throughput screening, high‐throughput deposition, and device development, all of which are covered herein. Especially promising are developments towards the study and control of dynamic phenomena, such as the directional motion of molecules, droplets, and cells. 相似文献
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Dr. Guobin Wen Dr. Bohua Ren Dr. Moon G. Park Dr. Jie Yang Dr. Haozhen Dou Dr. Zhen Zhang Dr. Ya-Ping Deng Prof. Zhengyu Bai Prof. Lin Yang Prof. Jeff Gostick Prof. Gianluigi A. Botton Prof. Yongfeng Hu Prof. Zhongwei Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(31):12960-12967
Simultaneously improving energy efficiency (EE) and material stability in electrochemical CO2 conversion remains an unsolved challenge. Among a series of ternary Sn-Ti-O electrocatalysts, 3D ordered mesoporous (3DOM) Sn0.3Ti0.7O2 achieves a trade-off between active-site exposure and structural stability, demonstrating up to 71.5 % half-cell EE over 200 hours, and a 94.5 % Faradaic efficiency for CO at an overpotential as low as 430 mV. DFT and X-ray absorption fine structure analyses reveal an electron density reconfiguration in the Sn-Ti-O system. A downshift of the orbital band center of Sn and a charge depletion of Ti collectively facilitate the dissociative adsorption of the desired intermediate COOH* for CO formation. It is also beneficial in maintaining a local alkaline environment to suppress H2 and formate formation, and in stabilizing oxygen atoms to prolong durability. These findings provide a new strategy in materials design for efficient CO2 conversion and beyond. 相似文献
86.
Dr. Min Luo Dr. Chensheng Lin Donghong Lin Prof. Ning Ye 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(37):16112-16115
The first fluorosulfonic ultraviolet (UV) nonlinear optical (NLO) material, C(NH2)3SO3F, is rationally designed by taking KBe2BO3F2 (KBBF) as the parent compound. C(NH2)3SO3F features similar topological layers as KBBF by replacing inorganic (BO3)3− with organic C(NH2)3+ trigonal units and BeO3F with SO3F− tetrahedra. Therefore, C(NH2)3SO3F is a metal-free UV NLO crystal. Benefiting from the coplanar configuration of the C(NH2)3+ cationic groups, it possesses a large SHG response of 5×KDP and moderate birefringence of 0.133@1064 nm. Besides, it has a short UV cutoff edge of 200 nm. The calculated results reveal the shortest SHG phase-matching wavelengths can reach 200 nm. These findings highlight the exploration of metal-free compounds as nontoxic and low-cost UV NLO materials as a new research area. 相似文献
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88.
Dr. Shengfu Tong Cuiping Luo Jiade Li Dr. Zongwei Mei Prof. Mingmei Wu Prof. Anthony P. O'Mullane Prof. Huaiyong Zhu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21095-21099
The practical applications of non-aqueous lithium-oxygen batteries are impeded by large overpotentials and unsatisfactory cycling durability. Reported here is that commonly encountered fatal problems can be efficiently solved by using a carbon- and binder-free electrode of titanium coated with TiO2 nanotube arrays (TNAs) and gold nanoparticles (AuNPs). Ultraviolet irradiation of the TNAs generates positively charged holes, which efficiently decompose Li2O2 and Li2CO3 during recharging, thereby reducing the overpotential to one that is near the equilibrium potential for Li2O2 formation. The AuNPs promote Li2O2 formation, resulting in a large discharge capacity. The electrode exhibits excellent stability with about 100 % coulombic efficiency during continuous cycling of up to 200 cycles, which is due to the carbon- and binder-free composition. This work reveals a new strategy towards the development of highly efficient oxygen electrode materials for lithium-oxygen batteries. 相似文献
89.
Qi Hu Zhen Han Xiaodeng Wang Guomin Li Ziyu Wang Xiaowan Huang Hengpan Yang Xiangzhong Ren Qianling Zhang Jianhong Liu Prof. Chuanxin He 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(43):19216-19221
Previous density-functional theory (DFT) calculations show that sub-nanometric Cu clusters (i.e., 13 atoms) favorably generate CH4 from the CO2 reduction reaction (CO2RR), but experimental evidence is lacking. Herein, a facile impregnation-calcination route towards Cu clusters, having a diameter of about 1.0 nm with about 10 atoms, was developed by double confinement of carbon defects and micropores. These Cu clusters enable high selectivity for the CO2RR with a maximum Faraday efficiency of 81.7 % for CH4. Calculations and experimental results show that the Cu clusters enhance the adsorption of *H and *CO intermediates, thus promoting generation of CH4 rather than H2 and CO. The strong interactions between the Cu clusters and defective carbon optimize the electronic structure of the Cu clusters for selectivity and stability towards generation of CH4. Provided here is the first experimental evidence that sub-nanometric Cu clusters facilitate the production of CH4 from the CO2RR. 相似文献
90.
Tiago Augusto Donegatti Alnilan Lobato Eliana A. R. Duek Luís Moreira Gonçalves Elisabete Alves Pereira 《Electrophoresis》2020,41(18-19):1576-1583
Aminoglycosides are a relevant class of antibiotics widely used by medics and veterinaries. There are a variety of reasons that make their determination relevant, such as quality control, environment and food contamination assessment, drug-release studies, among others. The lack of a chromophore makes aminoglycoside spectrophotometric detection particularly challenging, often requiring derivatization. In this work, an indirect detection method, making use of imidazole as a probe, applying CZE was successfully tested. It did not require derivatization, which simplified the sample preparation. Suitable figures of merit were obtained; recoveries between 95 and 105%, adequate repeatability and precision, correlation coefficients (r) above 0.998, and limits of detection (LODs) of 3.2 and 11 mg/L for gentamicin and paromomycin, respectively. As a proof-of-concept, it was also applied in a simple controlled release experiment that was well fitted using the Hill equation. 相似文献