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71.
Li Feng Chang Guan Ji-rong Chang Hai-min Zhai Guo-sheng An Wen-sheng Li 《矿物冶金与材料学报》2018,25(11):1354-1361
By mixing preheated high-aluminum bronze powders with different amounts of Al2O3 powder, a low-pressure cold-sprayed coating was prepared and sprayed onto a Cr12MoV steel substrate. The hardness of the coating and the bonding strength between the coating and the substrate were tested with a HV-1000 microhardness tester and a mechanical universal testing machine. The surface microstructure, cross-section and tensile fracture surface of the coating were observed with a scanning electron microscope (SEM). Correspondingly, the influences of the preheat treatment temperature of the bronze powder and the Al2O3 content on the coating performance were investigated. The results indicate that the hardness of bronze powders decreased and the coating deposition rate increased after the preheating treatment of the bronze powder. The Al2O3 content in the mixed powders contributed to the deformation of bronze powders during the spraying process. This trend resulted in varied performance of the coating. 相似文献
72.
Diffraction anomaly corresponds to an energy re-distribution in the reflected and transmitted light beams and in different diffraction orders of a grating, which leads to sharp modulations on the transmission and reflection spectra. In gratings sitting on a transparent substrate, this portion of the energy is actually transferred to channels separated from the reflected and transmitted beams. These channels are based on multiple degenerated diffraction processes at the same wavelength as the diffraction anomaly. The spectroscopic response of these channels is sensitive to the change in the environmental refractive index and can be utilized in sensor devices. 相似文献
73.
Yuying Qu Yingchun Li Xiaoli Tan Weixiang Zhai Dr. Guifang Han Dr. Jingli Hou Prof. Guoquan Liu Prof. Yuguang Song Prof. Yangping Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(33):7888-7895
Tetrathiatriarylmethyl (TAM, trityl) radicals have found wide applications as spin probes/labels for EPR spectroscopy and imaging, and as polarizing agents for dynamic nuclear polarization. The high hydrophilicity of TAM radicals is essential for their biomedical applications. However, the synthesis of hydrophilic TAM radicals (e.g., OX063) is extremely challenging and has only been reported in the patent literature, to date. Herein, an efficient synthesis of a highly water-soluble TAM radical bis(8-carboxyl-2,2,6,6-tetramethylbenzo[1,2-d:4,5-d′]bis([1,3]dithiol-4-yl)-mono-(8-carboxyl-2,2,6,6-tetrakis(2-hydroxyethyl)benzo[1,2-d:4,5-d′]bis([1,3]dithiol-4-yl)methyl (TFO), which contains four additional hydroxylethyl groups, relative to the Finland trityl radical CT-03, is reported. Similar to OX063, TFO exhibits excellent properties, including high water solubility in phosphate buffer, low log P, low pKa, long relaxation times, and negligible binding with bovine serum albumin. On the other hand, TFO has a sharper EPR line and higher O2 sensitivity than those of OX063. Therefore, in combination with its facile synthesis, TFO should find wide applications in magnetic resonance related fields and this synthetic approach would shed new light on the synthesis of other hydrophilic TAM radicals. 相似文献
74.
Tailorable PC71BM Isomers: Using the Most Prevalent Electron Acceptor to Obtain High‐Performance Polymer Solar Cells
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Xin‐Xing Zhan Xin Zhang Si‐Min Dai Shu‐Hui Li Xu‐Zhai Lu Dr. Lin‐Long Deng Prof. Su‐Yuan Xie Prof. Rong‐Bin Huang Prof. Lan‐Sun Zheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(52):18709-18713
Despite being widely used as electron acceptor in polymer solar cells, commercially available PC71BM (phenyl‐C71‐butyric acid methyl ester) usually has a “random” composition of mixed regioisomers or stereoisomers. Here PC71BM has been isolated into three typical isomers, α‐, β1‐ and β2‐PC71BM, to establish the isomer‐dependent photovoltaic performance on changing the ternary composition of α‐, β1‐ and β2‐PC71BM. Mixing the isomers in a ratio of α/β1/β2=8:1:1 resulted in the best power conversion efficiency (PCE) of 7.67 % for the polymer solar cells with PTB7:PC71BM as photoactive layer (PTB7=poly[[4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl][3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl]]). The three typical PC71BM isomers, even though sharing similar LUMO energy levels and light absorption, render starkly different photovoltaic performances with average‐performing PCE of 1.28–7.44 % due to diverse self‐aggregation of individual or mixed PC71BM isomers in the otherwise same polymer solar cells. 相似文献
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76.
Yuanzheng Zhai Jinsheng Wang Bo-tao Zhang Yongli Guo Yanguo Teng Jun Zhou 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(1):315-323
A physical, hydrochemical and isotopic evaluation of springs in Beijing was conducted in 2009 to reveal apparent changes in the properties of those springs. The results showed that most of the 2nd class springs and more than 50 % of the 1st class springs recorded in the early 1980s were depleted, while the discharges of existing springs have also decreased sharply. In addition, the majority of springs were of the HCO3–Ca–Mg type and good water quality, with the quality indices changing slightly compared to those recorded 30 years ago. The abundances of 2H, 18O, and 3H in the springs indicated that most of the springs were of meteoric origin with a relatively close connection to modern atmospheric precipitation. As a result, the springs have a relatively strong renewability within a shallow circulation. 相似文献
77.
介绍了金属材料专业课实践教学改革的思路和过程,围绕培养学生工程能力和创新精神,以典型产品带动专业课理论和实践教学,实现实践教学环节和内容的贯通,建立由多个环节有机组成的实践教学体系,通过综合性、工程性、设计性、创造性的实践教学,以科研生产促进实践教学开展,丰富和完善各个实践教学环节并突出能力培养,从而有利于学生提高工程实践能力及创新精神。 相似文献
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