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| 1 | KHCO_3 activated carbon microsphere as excellent electrocatalyst for VO^(2+)/VO_2^+ redox couple for vanadium redox flow battery显示文摘In this paper,carbon microsphere prepared by hydrothermal treatment was activated by KHCO_3 at high temperature,and employed as the catalyst for VO^(2+)/VO_2^+redox reaction for vanadium redox flow battery(VRFB).Carbon microsphere can be etched by KHCO_3 due to the reaction between the pyrolysis products of KHCO_3 and carbon atoms.Moreover,KHCO_3 activation can bring many oxygen functional groups on carbon microsphere,further improving the wettability of catalyst and increasing the active sites.The electrocatalytic properties of carbon microsphere from hydrothermal treatment are improved by high temperature carbonization,and can further be enhanced by KHCO_3 activation.Among carbon microsphere samples,the VO^(2+)/VO_2^+redox reaction exhibits the highest electrochemical kinetics on KHCO_3 activated sample.The cell using KHCO_3 activated carbon microsphere as the positive catalyst demonstrates higher energy efficiency and larger discharge capacity,especially at high current density.The results reveal that KHCO_3 activated carbon microsphere is an efficient,low-cost carbon-based catalyst for VO^(2+)/VO_2^+redox reaction for VRFB system. | Chen Zhao Yuehua Li Zhangxing He Yingqiao Jiang Lu Li Fengyun Jiang Huizhu Zhou Jing Zhu Wei Meng Ling Wang Lei Dai | 2019 | Journal of Energy Chemistry2019，28，2： | 5 |
| 2 | Yoctonewton force detection based on optically levitated oscillator显示文摘Optically levitated oscillators in high vacuum have excellent environmental isolation and low mass compared with conventional solid-state sensors,which makes them suitable for ultrasensitive force detection.The force resolution usually scales with the measurement bandwidth,which represents the ultimate detection capability of the system under ideal conditions if sufficient time is provided for measurement.However,considering the stability of a real system,a method based on the Allan variance is more reliable to evaluate the actual force detection performance.In this study,a levitated optomechanical system with a force detection sensitivity of 6.33±1.62 zN/Hz^(1/2)was demonstrated.And for the first time,the Allan variance was introduced to evaluate the system stability due to the force sensitivity fluctuations.The force detection resolution of 166.40±55.48 yN was reached at the optimal measurement time of 2751 s.The system demonstrated in this work has the best force detection performance in both sensitivity and resolution that have been reported so far for optically levitated particles.The reported high-sensitivity force detection system is an excellent candidate for the exploration of new physics such as fifth force searching,high-frequency gravitational waves detection,dark matter research and so on. | Tao Liang Shaochong Zhu Peitong He Zhiming Chen Yingying Wang Cuihong Li Zhenhai Fu Xiaowen Gao Xinfan Chen Nan Li Qi Zhu Huizhu Hu | 2023 | Fundamental Research2023，3，1： | 1 |
| 3 | RETARDATION OF PHOTOSENSITIZED OXIDATION BY COMPLEX OF HYPOCRELLIN A AND PRASEODYMIUM ION显示文摘This paper studies the retardation process for photosensitized oxidation of 9,10-diphenylanthracene(9,10-DPA) induced by hypocrellin A (HA) as a sensitizer in the presence ofpraseodymium ion (Pr3+).Experimental result shows that the prompt fluorescence of HA can be quenched byPr3+ in methanol.Measurement of fluorescence lifetime reveals that it remains constant with increasing con-centration of Pr3+,thus a static quenching character is indicated.The thermally induced delayed fluorescenceof HA can also be quenched effectively by the Pr3+-HA complex.The delayed fluorescence lifetime is re-duced from 1744±50 ns to 700±50 ns and 500±50 ns in the presence of oxygen and Pr3+ respectively,thusthe quenching of delayed fluorescence is of dynamic character.As compared with the double reciprocal rela-tionship of concentration between the oxidation product derived from singlet oxygen and the reactant,it showsthat the Pr3+-HA complex can quench not only the excited triplet of HA but also the singlet oxygen andtherefore the photosensitized oxidation of 9,10-DPA is retarded efficiently. | Wang Duoyuan He Huizhu(Institute of Photographic Chemistry,Academia Sinica,Beijing 100012,P.R.China) | 1990 | Journal of Rare Earths1990，8，1： | 0 |
| 4 | Numerical Simulation Study on Wear of Spur Gears under Dynamic Conditions显示文摘A numerical simulation model is proposed to predict the wear depth of gears,where Archard's wear equation and a nonlinear dynamic model are combined to establish a wear calculation model under dynamic conditions.The dynamic meshing force,determined by the non-linear dynamic model,and the sliding coefficient are used by Archard's wear equation to calculate the surface wear.Then the dynamic meshing force and sliding coefficient would be recalculated according to the surface wear state.After repeated iterations,the simulation results show that the peak and fluctuation of the meshing force increase first,then decrease,and eventually maintain stability during the process of wear.As for the distribution of wear depth,its fluctuation also increases first and then declines.Finally,the distribution of wear depth becomes V-shaped.Comparing the trends of the two factors,it is clear that the meshing force and wear depth are closely related.Moreover,the wear rate maintains a higher constant value first and then declines to a lower constant value. | Changsong Zheng Zhouli Zhang Chunping He Weipeng Lou Huizhu Li Qiu Du | 2019 | Journal of Beijing Institute of Technology2019，28，1： | 0 |
| 5 | NEW ORGANIC SYSTEM FOR PHOTON-GATED PERSISTENT SPECTRAL HOLE BURNING显示文摘We report a new system of organic materials for photon-gated persistent spectral hole burning by donor-acceptor electron transfer:a tetrabenzoporphyrin derivative as donor and one of several aromatic cyanides as an acceptor in a poly(methyl methacrylate)(FMMA)host matrix.Up to 50C%deep spectral holes in transmission were burnt and appeared very high hole burning efficiency. | WANG Duoyuan HU Lingzhi HE Huizhu XIE Jie ZHANG Junyi ZHAO Lizeng ZHANG Xiulan ZHANG Dongxiang MI Xin NIE Yuxin YE Peixian | 1990 | Chinese Physics Letters1990，7，12： | 0 |
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