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71.
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
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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
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多孔硅纳米材料具有巨大的比表面积,可调控的物理化学性质,在药物治疗、传感、能源储存与转化等领域拥有巨大的应用前景。尤其在高能量密度锂离子电池领域,多孔硅由于其丰富的孔道结构能有效释放充放电过程中硅体积变化带来的巨大应力以及大大地缩短锂离子传输距离,而引起了人们的广泛研究兴趣。但是,开发简便快速的方法来合成结构可调变的多孔硅纳米材料仍是当前研究的挑战。近年来,一些用来合成多孔硅纳米材料的方法已有报道。我们基于本课题组最近的研究进展和近年来相关文献,比较详细综述了近年来多孔硅纳米材料的制备方法以及重点关注其在高能锂电池领域的应用。最后,对多孔硅纳米材料的未来发展方向做了进一步的展望。 相似文献
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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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Sule Bayraktar 《School science and mathematics》2011,111(3):83-92
The main purpose of this study was to investigate the effectiveness of a primary teacher education program in improving science teaching efficacy beliefs (personal science teaching efficacy beliefs and outcome expectancy beliefs) of preservice primary school teachers. The study also investigated whether the program has an effect on student teachers' attitudes toward science. Data were collected by administering the “Science Teaching Efficacy Beliefs Instrument” and “Attitudes toward Science Scale” to 282 preservice primary teachers (147 freshmen, 135 seniors). Statistical techniques such as means and t‐test were used to analyze the data. Results of the study showed that the primary teacher education program has a medium positive effect on science teaching efficacy beliefs of the primary preservice teachers (t = 4.791, p = .000) and that there were no gender differences in terms of efficacy beliefs. Results also indicated that preservice primary teachers' attitudes toward science were moderately positive and differ by class level. Fourth‐year preservice teachers' attitudes toward science were found to be significantly more positive than the first years (t = 5.494, p = .000). There were no gender differences in attitudes toward science. 相似文献
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