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991.
从理论上研究了共轭高聚物链中在电场作用下极化子运动的热效应.基于SSH模型以及通过绝热动力学演化的方法,模拟了共轭高聚物链中极化子在电场作用下从链左端向右端运动的过程.晶格受到的热扰动作用假设为通过局域的晶格范围内原子位移的随机涨落来实现.结果发现,晶格中的局域热涨落对于运动中的极化子而言等效于一个势垒.势垒高度由高分子中受到热扰动的区域的范围大小以及该区域与其周围环境的温差来决定.当分子中存在热吸收不均匀的现象时,链内极化子迁移率在低电场范围内随电场的变化遵循对数曲线变化规律. 相似文献
992.
Chunlei Li Andrew M. Kiss Douglas G. Van Campen Alex Garachtchenko Yuriy Kolotovsky Kevin Stone Yahong Xu Wenjun Zhang Jeff Corbett 《Journal of synchrotron radiation》2016,23(4):909-918
Typical X‐ray diffraction measurements are made by moving a detector to discrete positions in space and then measuring the signal at each stationary position. This step‐scanning method can be time‐consuming, and may induce vibrations in the measurement system when the motors are accelerated and decelerated at each position. Furthermore, diffraction information between the data points may be missed unless a fine step‐scanning is used, which further increases the total measurement time. To utilize beam time efficiently, the motor acceleration and deceleration time should be minimized, and the signal‐to‐noise ratio should be maximized. To accomplish this, an integrated continuous‐scan system was developed at the Stanford Synchrotron Radiation Lightsource (SSRL). The continuous‐scan system uses an in‐house integrated motor controller system and counter/timer electronics. SPEC software is used to control both the hardware and data acquisition systems. The time efficiency and repeatability of the continuous‐scan system were tested using X‐ray diffraction from a ZnO powder and compared with the step‐scan technique. Advantages and limitations of the continuous‐scan system and a demonstration of variable‐velocity continuous scan are discussed. 相似文献
993.
Magnetically‐Confined Fe‐Mn Bimetallic Oxide Encapsulation as an Efficient and Recoverable Adsorbent for Arsenic(III) Removal
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Li Yu Huijuan Liu Chunlei Liu Huachun Lan Jiuhui Qu 《Particle & Particle Systems Characterization》2016,33(6):323-331
Synthesis of bimetallic‐oxide‐encapsulated magnetic nanoparticles is still significantly challenging and has rarely been attempted previously, due to the effects of lattice mismatch, weak chemical interactions and variances in growth rates between different components, as well as the difficulty in process control for uniform co‐deposition. In the present work, Fe‐Mn bimetallic oxide (FMBO) nanoplatelet encapsulated magnetic nanoparticles (Mag‐FeMn) are prepared by controlled engineering of the interparticle coupling of Fe3O4 and FMBO, with its multifunctional capabilities highlighted in terms of the potentially superior As(III) sequestration and convenient recoverability. Multiple characterization techniques are employed to examine the derived morphologies and to accurately resolve both compositionally and magnetically the hierarchical structure in detail. The synthesized magnetic composites retain highly porous structure with the main components of Fe2O3, FeOOH, Fe3O4, and Mn3O4. Mag‐FeMn exhibits a quite competitive high capacity for As(III) capture (56.1 mg g–1), whereby As(III) oxidation coupled with synchronous sorption contributes to the improved performance. The unique heterostructure of FMBO encapsulation with an embedded magnetic core would be applicable to help with rational synthesis of other bimetallic oxide encapsulated magnetic nanoparticles, and definitely shows promise for the development of new nanotechnology enabled approaches for adsorption‐based water purification. 相似文献
994.
995.
Xiaogang Sun Jun Xing Jingping Qiu 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(6):1151-1156
A series of boron and sulfur co-doped titanium dioxide (TiO2) photocatalysts were prepared by a sol-gel method using boric acid, thiourea and tetrabutyl titanate [Ti(OC4H9)4] as precursors. The photoabsorbance of as-prepared photocatalysts was measured by UV–Vis diffuse reflectance spectroscopy (DRS), and its microstructure was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and N2 adsorption-desorption measurements. The prepared photocatalysts consisted of the anatase phase mainly in the form of spherical particles. The photocatalytic performance was studied by photodegradation of methyl blue (MB) in water under UV and visible light irradiation. The calcination temperature and the codoping content influenced the photoactivity. The synergistic effect of boron and sulfur co-doping played an important role in improving the photocatalytic activity. In addition, the possibility of cyclic usage of codoped TiO2 was also confirmed, the photocatalytic activity of TiO2 remained above 91% of that of the fresh sample after being used four times. It was shown that the co-doped TiO2 could be activated by visible light and could thus be potentially applied for the treatment of water contaminated by organic pollutants. 相似文献
996.
A Facile Synthesis of Novel Allenylphosphinates Containing Multi Potential Asymmetric Centers
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Lan Yao Si‐Yu Ji Zhong‐Yuan Xu Yong‐Ming Sun Chang‐Qiu Zhao 《Journal of heterocyclic chemistry》2016,53(4):1155-1158
The novel allenylphosphinates containing up to three axial and phosphorus asymmetric centers were prepared in excellent yields via the reactions of 6‐chloro‐6H‐dibenzo[c,e][1,2]oxaphosphinine to propargyl alcohols. During the process, the configuration of phosphorus determined the biphenyl axial chirality, stereospecifically forming (l)‐stereomers but did not influence the chirality of allenyl axis. 相似文献
997.
998.
A Copper‐Catalyzed Decarboxylative Amination/Hydroamination Sequence: Switchable Synthesis of Functionalized Indoles
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Tian‐Ren Li Bei‐Yi Cheng Ya‐Ni Wang Mao‐Mao Zhang Prof. Dr. Liang‐Qiu Lu Prof. Dr. Wen‐Jing Xiao 《Angewandte Chemie (International ed. in English)》2016,55(40):12422-12426
A copper‐catalyzed decarboxylative amination/hydroamination sequence of propargylic carbamates with various nucleophiles is described for the first time. It features an earth‐abundant metal catalyst, mild reaction conditions, and high efficiency. Further treatments of the resultant key intermediates using an acid or a base in one pot enable the controllable and divergent synthesis of two types of functionalized indoles. Moreover, experiments to demonstrate the synthetic potential of this methodology are performed. 相似文献
999.
Micropatterning of the Ferroelectric Phase in a Poly(vinylidene difluoride) Film by Plasmonic Heating with Gold Nanocages
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Jianhua Li Miaoxin Yang Xiaojun Sun Dr. Xuan Yang Dr. JiaJia Xue Dr. Chunlei Zhu Prof. Hong Liu Prof. Younan Xia 《Angewandte Chemie (International ed. in English)》2016,55(44):13828-13832
Polymer thin films with patterned ferroelectric domains are attractive for a broad range of applications, including the fabrication of tactile sensors, infrared detectors, and non‐volatile memories. Herein, we report the use of gold nanocages (AuNCs) as plasmonic nanostructures to induce a ferroelectric–paraelectric phase transition in a poly(vinylidene fluoride) (PVDF) thin film by leveraging its photothermal effect. This technique allows us to generate patterned domains of ferroelectric PVDF within just a few seconds. The incorporation of AuNCs significantly enhances the pyroelectric response of the ferroelectric film under near‐infrared irradiation. We also demonstrate the use of such patterned ferroelectric films for near‐infrared sensing/imaging. 相似文献
1000.
Zongyang Qiu Prof. Li Song Prof. Jin Zhao Prof. Zhenyu Li Prof. Jinlong Yang 《Angewandte Chemie (International ed. in English)》2016,55(34):9918-9921
Metal‐nanoparticle‐catalyzed cutting is a promising way to produce graphene nanostructures with smooth and well‐aligned edges. Using a multiscale simulation approach, we unambiguously identified a “Pac‐Man” cutting mechanism, characterized by the metal nanoparticle “biting off” edge carbon atoms through a synergetic effect of multiple metal atoms. By comparing the reaction rates at different types of edge sites, we found that etching of an entire edge carbon row could be triggered by a single zigzag‐site etching event, which explains the puzzling linear dependence of the overall carbon‐atom etching rate on the nanoparticle surface area observed experimentally. With incorporation of the nanoparticle size effect, the mechanisms revealed herein open a new avenue to improve controllability in graphene cutting. 相似文献