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91.
提出了一种基于相位调制器(PM)和可调谐光滤波器产生线性调频激光信号的方法。该方法利用带有基频的微波线性调频信号作为相位调制器的驱动信号,窄线宽的激光种子源经相位调制器调制后产生一系列的宽带线性调频激光信号。通过可调谐光滤波器抑制其他边带保留所需阶次的线性调频激光信号。实验结果表明:当光滤波器保留正二阶调频激光信号时,获得了调频带宽为2 GHz、调频速率为6 THz/s的线性调频激光信号。在观测时间为1 ms时,测得的线性调频激光信号的瞬时线宽为3.2 kHz。该方法结构简单,易于实现,并且对调频连续波激光雷达、相干光谱分析等测量应用有重要意义。 相似文献
92.
Junfan Zhang Jing Wang Mengmeng Qian Bo Zhao Ran Wang Xuechun Hao Xinwei Huang Ruiwen Shao Zhenyu Xing Jing Xie Bing Xu Yuefeng Su Feng Wu Guoqiang Tan 《Advanced functional materials》2022,32(1):2108305
Reducing the activation barrier and stabilizing the sulfur species of Li2S cathodes can ultimately enhance cell efficiency and the cycle life of S-based Li-ion batteries (LIBs). Here, a unique synchronous synthesis method is established that can simultaneously construct Li2S encapsulated in conductive protective layers, and accordingly propose a coordination effect of catalysis and domain restriction for Li2S cathodes. Typically, based on the lithiothermic reaction of 8Li + MoS2 + CS2 = 4Li2S + Mo + C, the obtained composite features abundant Mo nanocrystals embedded in crystalline Li2S matrices and then wrapped by few-layer graphene. Notably, all three components derived from lithiothermic reaction are linked by the chemical bonding of Mo? S and C? S, forming a compact Mo-Li2S-graphene triple heterostructure. Systematic studies reveal an unprecedented relevancy between charge overpotential and catalytic activation of Mo-Li2S-graphene, whereas a low activation potential of 2.43 V is achieved. Further studies disclose the relationship between cycle stability and confinement effect of core-shell structure, whereas the improved confinement efficiency for polysulfides enables an excellent cycle life for the Li-S battery. Moreover, the Mo-Li2S-graphene cathode demonstrates promising application for LIB, where the Mo-Li2S-graphene//Si? C battery shows a high capacity of 764 mAh g?1 and outstanding cycle stability. 相似文献
93.
Fei Zhang Yiyu Feng Mengmeng Qin Long Gao Zeyu Li Fulai Zhao Zhixing Zhang Feng Lv Wei Feng 《Advanced functional materials》2019,29(25)
Stress controllability in thermal and electrical conductivity is important for flexible piezoresistive devices. Due to the strength‐elasticity trade‐off, comprehensive investigation of stress‐controllable conduction in elastic high‐modulus polymers is challenging. Here presented is a 3D elastic graphene‐crosslinked carbon nanotube sponge/polyimide (Gw‐CNT/PI) nanocomposite. Graphene welding at the junction enables both phonon and electron transfer as well as avoids interfacial slippage during cyclic compression. The uniform Gw‐CNT/PI comprising a high‐modulus PI deposited on a porous templated network combines stress‐controllable thermal/electrical conductivity and cyclic elastic deformation. The uniform composites show different variation trends controlled by the porosity due to different phonon and electron conduction mechanisms. A relatively high k (3.24 W m?1 K?1, 1620% higher than PI) and suitable compressibility (16.5% under 1 MPa compression) enables the application of the composite in flexible elastic thermal interface conductors, which is further analyzed by finite element simulations. The interconnected network favors a high stress‐sensitive electrical conductivity (sensitivity, 973% at 9.6% strain). Thus, the Gw‐CNT/PI composite can be an important candidate material for piezoresistive sensors upon porosity optimization based on stress‐controllable thermal or electrical conductivity. The results provide insights toward controlling the stress‐induced thermal/electrical conductivities of 3D interconnected templated composite networks for piezoresistive conductors or sensors. 相似文献
94.
In this study, we investigate topology control as a means of obtaining the best possible compromise between the conflicting requirements of reducing energy consumption and improving network connectivity. A topology design algorithm capable of producing network topologies that minimize energy consumption under a minimum‐connectivity constraint is presented. To this end, we define a new topology metric, called connectivity efficiency, which is a function of both algebraic connectivity and the transmit power level. Based on this metric, links that require a high transmit power but only contribute to a small fraction of the network connectivity are chosen to be removed. A connectivity‐efficiency‐based topology control (CETC) algorithm then assigns a transmit power level to each node. The network topology derived by the proposed CETC heuristic algorithm is shown to attain a better tradeoff between energy consumption and network connectivity than existing algorithms. Simulation results demonstrate the efficiency of the CECT algorithm. 相似文献
95.
Yulu Yang Yang Tang Haomin Jiang Yongmei Chen Pingyu Wan Maohong Fan Rongrong Zhang Sana Ullah Lun Pan Ji-Jun Zou Mengmeng Lao Wenping Sun Chao Yang Gengfeng Zheng Qiling Peng Ting Wang Yonglan Luo Xuping Sun Alexander S. Konev Oleg V. Levin Panagiotis Lianos Zhuofeng Hu Zhurui Shen Qinglan Zhao Ying Wang Nadia Todorova Christos Trapalis Matthew V. Sheridan Haipeng Wang Ling Zhang Songmei Sun Wenzhong Wang Jianmin Ma 《中国化学快报》1990,30(12):2089-2109
In this roadmap, we address the development and perspectives of hydrogen evolution reaction, oxygen reduction reaction, oxygen evolution reaction, carbon dioxide reduction reaction and nitrogen reduction. 相似文献
96.
Dr. Fa-Jie Chen Dr. Mengmeng Zheng Vincent Nobile Dr. Jianmin Gao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(20):e202200058
This work reports a novel chlorooxime mediated modification of native peptides and proteins under physiologic conditions. This method features fast reaction kinetics (apparent k2=306±4 M−1s−1 for GSH) and exquisite selectivity for cysteine residues. This cysteine conjugation reaction can be carried out with just single-digit micromolar concentrations of the labeling reagent. The conjugates show high stability towards acid, base, and external thiol nucleophiles. A nitrile oxide species generated in situ is likely involved as the key intermediate. Furthermore, a bis-chlorooxime reagent is synthesized to enable facile Cys-Cys stapling in native peptides and proteins. This highly efficient cysteine conjugation and stapling was further implemented on bacteriophage to construct chemically modified phage libraries. 相似文献
97.
Wireless Networks - In this paper, we investigate the impacts of mobility on the characterization of energy consumption in wireless networks. Considering a linear wireless network deployed for an... 相似文献
98.
Xiao Qi Feng Jinrong Feng Mengmeng Li Jiawen Liu Yi Wang Dan Huang Shan 《Mikrochimica acta》2019,186(7):1-9
Microchimica Acta - A self-sacrificing catalytic method is described for the preparation of magnetic core/dual-functional-shell nanocomposites composed of magnetite, gold and Prussian blue (type... 相似文献
99.
以PbCl2为介质, 采用无电沉积方法制备了掺钯碳纳米管, 并对其形貌和结构进行了表征. 结果表明, 掺入的钯纳米粒子分布均匀、 粒径均一, 掺杂量与粒径尺寸适中; 所掺入的纳米粒子的成分为0价态的钯, 且掺杂类型为p型. 电接触性能测试结果表明, 掺钯碳纳米管与金电极间的接触电阻得到了明显改善, 阻值平均降幅高达近71.09%. 相似文献
100.
Pin Gao Yanfang Zhang Guangsu Huang Mengmeng Chen Jing Zheng 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(2):142-147
The multi-hydroxymethyl structure of resol makes it suitable for connecting two or more polyacrylamide chains as a crosslinker in oil recovery applications, but control of the structure and composition of the resol, whether in practice or theory, is still a controversial problem. In the present research, a series of resol prepolymers synthesized with different amounts and types of catalysts, formaldehyde to phenol molar ratio, reaction temperature and charging steps were characterized by high-performance liquid chromatography. It is found that the compositions of the resols barely changed with almost all the varying conditions, but the contents of each component were greatly affected by the variation of reaction conditions. Finally, the best conditions for preparing resol crosslinker were obtained. 相似文献