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61.
Nonlinear Dynamics - As the use of viscoelastic materials becomes increasingly popular, stability of viscoelastic structures under random loads becomes increasingly important. This paper aims at... 相似文献
62.
Dr. Karl P. J. Gustafson Arnar Guðmundsson Dr. Éva G. Bajnóczi Dr. Ning Yuan Prof. Xiaodong Zou Prof. Ingmar Persson Prof. Jan-E. Bäckvall 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(15):3411-3419
The activation process of a known Ru-catalyst, dicarbonyl(pentaphenylcyclopentadienyl)ruthenium chloride, has been studied in detail using time resolved in situ X-ray absorption spectroscopy. The data provide bond lengths of the species involved in the process as well as information about bond formation and bond breaking. On addition of potassium tert-butoxide, the catalyst is activated and an alkoxide complex is formed. The catalyst activation proceeds via a key acyl intermediate, which gives rise to a complete structural change in the coordination environment around the Ru atom. The rate of activation for the different catalysts was found to be highly dependent on the electronic properties of the cyclopentadienyl ligand. During catalytic racemization of 1-phenylethanol a fast-dynamic equilibrium was observed. 相似文献
63.
Dr. Hong Shang Yu Gu Prof. Yingbin Wang Dr. Zicheng Zuo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(24):5434-5440
Nonuniform nucleation is one of the major reasons for the dendric growth of metallic lithium, which leads to intractable problems in the efficiency, reversibility, and safety in Li-based batteries. To improve the deposition of metallic Li on Cu substrates, herein, a freestanding current collector (NGDY@CuNW) is formed by coating pyridinic nitrogen-doped graphdiyne (NGDY) nanofilms on 3D Cu nanowires (CuNWs). Theoretical predictions reveal that the introduction of nitrogen atoms in the 2D GDY can enhance the binding energy between the Li atom and GDY, therefore improving the lithiophilicity on the surface for uniform lithium nucleation and deposition. Accordingly, the deposited metallic Li on the NGDY@CuNW electrode exhibits a dendrite-free morphology, resulting in significant improvements in terms of the reversibility with a high coulombic efficiency (CE) and a long lifespan at high current density. Our research provides an efficient method to control the surface property of Cu, which also will be instructive for other metal batteries. 相似文献
64.
Dr. Yongqi Yao Dr. Qifu Lin Dr. Wen Yang Prof. Dr. Weitao Yang Prof. Dr. Fenglong Gu Prof. Dr. Wei Guo Prof. Dr. Dingqiao Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(25):5607-5610
A cobalt(II)-catalyzed [4+2] annulation of picolinamides with alkynes via C−H bond activation has been developed. The operationally simple annulation reaction allows for the synthesis of acyl-substituted 1H-benzoquinoline bearing multiple aromatic rings (up to 96 % yield) without co-oxidant or other oxidation factors under mild conditions. Several control experiments were carried out. This practical [4+2] annulation provides an efficient route to access highly functionalized compounds. 相似文献
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67.
Song Zhang Luke A. Galuska Xiaodan Gu 《Journal of polymer science. Part A, Polymer chemistry》2022,60(7):1108-1129
Thin films with a nanometer-scale thickness are of great interest to both scientific and industrial communities due to their numerous applications and unique behaviors different from the bulk. However, the understanding of thin-film mechanics is still greatly hampered due to their intrinsic fragility and the lack of commercially available experimental instruments. In this review, we first discuss the progression of thin-film mechanical testing methods based on the supporting substrate: film-on-solid substrate method, film-on-water tensile tests, and water-assisted free-standing tensile tests. By comparing past studies on a model polymer, polystyrene, the effect of different substrates and confinement effect on the thin-film mechanics is evaluated. These techniques have generated fruitful scientific knowledge in the field of organic semiconductors for the understanding of structure–mechanical property relationships. We end this review by providing our perspective for their bright prospects in much broader applications and materials of interest. 相似文献
68.
Ming-Qiang Huang Huan-Huan Wang Xiao-Bin Shan Liu-Si Sheng Chang-Jin Hu Xue-Jun Gu Wei-Jun Zhang 《中国化学会会志》2023,70(4):938-948
Secondary organic aerosol (SOA) produced by ozonolysis of styrene and other alkene compounds is a major part of fine particles in urban atmospheres. The atmospheric ozonolysis process of styrene is simulated in a smog chamber, and the formed SOA particles are detected on-line by a synchronous radiation vacuum ultraviolet photoionization mass spectrometer (VUV-PIMS) in this study. Through molecular ion peaks in the photonionization mass spectra of SOA and the corresponding photoionization efficiency curve, combined with off-line measurement verification of ultraviolet visible and infrared absorption spectra, it is determined that formaldehyde, formic acid, benzene, phenol, benzaldehyde, and benzoic acid are the main constituents of styrene SOA. These provide new information for studying the atmospheric ozonolysis oxidation mechanism of styrene. VUV-PIMS can get over complicated sample preparation procedures, secondary pollution, and other shortcomings of the off-line method and is a useful instrument to measure constituents and unveil the formation process of SOA particles. 相似文献
69.
Linjun Qi Ming Dong Jinlong Qian Shuling Yu Prof. Xiaofeng Tong 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202215397
Reductive elimination of alkyl−PdII−O is a synthetically useful yet underdeveloped elementary reaction. Here we report that the combination of an H-bonding donor [PyH][BF4] and AgNO3 additive under toluene/H2O biphasic system can enable such elementary step to form alkyl nitrate. This results in the Pd0-catalyzed asymmetric carbonitratations of (Z)-1-iodo-1,6-dienes with (R)-BINAP as the chiral ligand, affording alkyl nitrates up to 96 % ee. Mechanistic studies disclose that the reaction consists of oxidative addition of Pd0 catalyst to vinyl iodide, anion ligand exchange between I− and NO3−, alkene insertion and SN2-type alkyl−PdII−ONO2 reductive elimination. Evidences suggest that H-bonding interaction of PyH⋅⋅⋅ONO2 can facilitate dissociation of O2NO− ligand from the alkyl−PdII−ONO2 species, thus enabling the challenging alkyl−PdII−ONO2 reductive elimination to be feasible. 相似文献
70.