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81.
针对杆件在横向力和轴向压力共同作用下的内力计算问题进行了研究.在考虑杆件变形因素的情形下,推导出了杆件在横向力和轴向压力共同作用下的内力和正应力的计算公式,并与材料力学中未考虑杆件变形因素的对应公式进行了比较,说明了二者之间不同之处. 相似文献
82.
《Particuology》2022
2D nanomaterials are widely investigated for biomedical applications, attributed to their large specific surface area, high therapeutic loading capacity, and unique optical, thermal, and/or electronic characteristics. Lattice defects affect the theranostic performance of 2D nanomaterials significantly by altering their electronic properties and chemical binding. Recent investigations have shown that defect-rich 2D nanomaterials are capable of enhancing tumor treatment through efficient drug delivery, photothermal and photodynamic therapies (PTT and PDT), and improving diagnostics via computed tomography (CT), photoacoustic and magnetic resonance imaging. This review summarizes recent progresses, including synthesis, characterization approach, and applications of defect-engineered 2D nanomaterials that are potentially useful in cancer treatment. The expert opinions are also proposed as the conclusion. 相似文献
83.
为了便于模式变换器的设计,达到双频微波都能集中辐射的目的,提出一种轴向分区的双频磁绝缘线振荡器,该器件束波互作用区为中间隔开、两端不同周期、不同深度的慢波结构,使电子在上下游与不同频率特性的慢波结构进行束波互作用,得到稳定的双频微波输出。使用2.5维全电磁粒子模拟软件进行数值模拟,在工作电压450 kV,电流40 kA条件下输出微波功率为1.4 GW,功率效率约为7%,输出的微波频率分别为1.25 GHz和1.65 GHz,两者频谱幅度相差约为1.5 dB,模式为TEM模。 相似文献
84.
85.
Comparative analysis of the luminescent properties of Y3Al5O12:Ce (YAG:Ce) transparent optical ceramics (OС) with those of single crystal (SC) and single crystalline film (SCF) analogues has been performed under excitation by pulsed synchrotron radiation in the fundamental absorption range of YAG host. It has been shown that the properties of YAG:Ce OC are closer to the properties of the SCF counterpart, where YAl antisite defects are completely absent, rather than to the properties of SC of this garnet with large concentration of YAl antisite defects. At the same time, the luminescence spectra of YAG:Ce OC show weak emission bands in the 200-470 nm range related to YAl antisite defects and charged oxygen vacancies (F+ and F centers). YAG:Ce ОС also possesses significantly larger contribution of slow components in the Ce3+ luminescence decay under high-energy excitation in comparison with SC and SCF of this garnet due to the involvement of antisite defects, charged oxygen vacancies as well as boundaries of grains in the energy transfer processes from the host to the Ce3+ ions. 相似文献
86.
Based on the nonlinear Hoek–Brown failure criterion, elastoplastic analytical solutions are developed for the elastoplastic stresses, strains and plastic zones around a circular tunnel subjected to different value of the axial in situ stress. Effects of the transverse in situ stress, the axial in situ stress and the strength parameters of rock masses on the elastoplastic stresses, strains and plastic zones in the surrounding rock masses are investigated. It is found from the numerical results that the stresses, strains, and plastic zones in the surrounding rock depend not only on the transverse in situ stress but also on the axial in situ stress as well as the mechanical parameters of rock masses. 相似文献
87.
88.
Luis K. Ono Shengzhong Liu Yabing Qi 《Angewandte Chemie (International ed. in English)》2020,59(17):6676-6698
In several photovoltaic (PV) technologies, the presence of electronic defects within the semiconductor band gap limit the efficiency, reproducibility, as well as lifetime. Metal halide perovskites (MHPs) have drawn great attention because of their excellent photovoltaic properties that can be achieved even without a very strict film‐growth control processing. Much has been done theoretically in describing the different point defects in MHPs. Herein, we discuss the experimental challenges in thoroughly characterizing the defects in MHPs such as, experimental assignment of the type of defects, defects densities, and the energy positions within the band gap induced by these defects. The second topic of this Review is passivation strategies. Based on a literature survey, the different types of defects that are important to consider and need to be minimized are examined. A complete fundamental understanding of defect nature in MHPs is needed to further improve their optoelectronic functionalities. 相似文献
89.
Niankun Guo Hui Xue Amurisana Bao Zihong Wang Jing Sun Tianshan Song Xin Ge Wei Zhang Keke Huang Feng He Qin Wang 《Angewandte Chemie (International ed. in English)》2020,59(33):13778-13784
Vacancy defects of catalysts have been extensively studied and proven to be beneficial to various electrocatalytic reactions. Herein, an ultra‐stable three‐dimensional PtCu nanowire network (NNW) with ultrafine size, self‐supporting rigid structure, and Cu vacancy defects has been developed. The vacancy defect‐rich PtCu NNW exhibits an outstanding performance for the oxygen reduction reaction (ORR), with a mass activity 14.1 times higher than for the commercial Pt/C catalyst (20 %.wt, JM), which is currently the best performance. The mass activity of the PtCu NNW for methanol oxidation reaction (MOR) is 17.8 times higher than for the commercial Pt/C catalyst. Density‐functional theory (DFT) calculations indicate that the introduction of Cu vacancies enhances the adsorption capacity of Pt atoms to the HO* intermediate and simultaneously weakens the adsorption for the O* intermediate. This work presents a facile strategy to assemble efficient electrocatalysts with abundant vacancy defects, at the same time, provides an insight into the ORR mechanism in acidic solution. 相似文献
90.
Markus Suta Flavie Lavoie‐Cardinal Claudia Wickleder 《Angewandte Chemie (International ed. in English)》2020,59(27):10949-10954
Inorganic hosts, such as SrB4O7 or certain nitrides, intrinsically stabilize Eu2+ even when the dopant is an Eu3+‐based precursor and reducing conditions are not employed in the synthesis. Although this concept is well known in the synthesis of phosphorescent materials, the mechanistic details are scarcely understood. Herein, we demonstrate that trapped charge carriers, such as color centers, can also act as redox partners to stabilize certain oxidation states of activators. Eu‐activated CsMgCl3 and CsMgBr3 are used as examples. Upon doping with EuCl3 and in the absence of reducing conditions during the synthesis, dominant cyan or green luminescence from Eu2+ ions was observed. Photoluminescence spectroscopy at 10 K revealed that the reduction is correlated to color centers localized at defects. Although defects are typically undesired in phosphors, we have shown that their role may be underestimated and they could be used on purpose in the preparation of selected inorganic phosphors. 相似文献