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121.
We have observed cyclotron resonance in a high-mobility GaAs/AlGaAs two-dimensional electron gas by using the techniques of terahertz time-domain spectroscopy combined with magnetic fields. From this, we calculate the real and imaginary parts of the diagonal elements of the magnetoconductivity tensor, which in turn allows us to extract the concentration, effective mass, and scattering time of the electrons in the sample. We demonstrate the utility of ultrafast terahertz spectroscopy, which can recover the true linewidth of cyclotron resonance in a high-mobility (>10(6) cm(2)V(-1)s(-1)) sample without being affected by the saturation effect. 相似文献
122.
Liang X Guo C Ma J Wang J Chen S Liu H 《The journal of physical chemistry. B》2007,111(46):13217-13220
Aggregation and disaggregation of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers, Pluronics P103 and P104, in aqueous solutions during a heating and cooling cycle were investigated by dynamic laser scattering (DLS) and 1H NMR spectroscopy. Temperature hysteresis was observed by DLS when cooling the copolymer aqueous solutions because larger aggregates existed at temperatures lower than critical micellization temperature (CMT), but no temperature differences were observed by NMR. This phenomenon was explained as the forming of water-swollen micelles at temperatures lower than CMT during the cooling process. 相似文献
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124.
Xu L Luo M Jiang C Wei X Kong P Liang X Zhao J Yang L Liu H 《Applied biochemistry and biotechnology》2012,166(4):933-941
Hexavalent chromate reductase was characterized and was found to be localized in the cytoplasmic fraction of a chromium-resistant
bacterium Pannonibacter phragmitetus LSSE-09. The Cr(VI) reductase activity of cell-free extract (S12) was significantly improved by external electron donors, such as NADH, glucose, acetate, formate, citrate, pyruvate, and
lactate. The reductase activity was optimal at pH 7.0 with NADH as the electron donor. The aerobic and anaerobic Cr(VI)-reduction
enhanced by 0.1 mM NADH were respectively 3.5 and 3.4 times as high as that without adding NADH. The Cr(VI) reductase activity
was inhibited by Mn2+, Cd2+, Fe3+, and Hg2+, whereas Cu2+ enhanced the chromate reductase activity by 29% aerobically and 33% anaerobically. The aerobic and anaerobic specific Michaelis–Menten
constant K
m of S12 fraction was estimated to be 64.95 and 47.65 μmol L−1, respectively. The soluble S150 fractions showed similar activity to S12 and could reduce 39.7% and 53.4% of Cr(VI) after 1 h of incubation aerobically and anaerobically while the periplasmic contents
showed no obvious reduction activity, suggesting an effective enzymatic mechanism of Cr(VI) reduction in the cytoplasmic fractions
of the bacterium. Results suggest that the enzymatic reduction of Cr(VI) could be useful for Cr(VI) detoxification in wastewater. 相似文献
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<正>The vehement explosion in two-dimensional (2 D) materials has led to one exciting new discoveries after another for the past 15 years.This circumstance resembles a famous movie "The Gold Rush"(1925) expressed the true story about the stream of American people as crowded as the hurricane to join the gold racing in the 19~(th) century.Similarly,the family of 2 D materials has gained tremendous interest from broad scientific community 相似文献
127.
Bing Sun Xiao-Fei Liu Xiang-Yang Li Yang Cao Ze Yan Lin Fu Prof. Nujiang Tang Prof. Qiang Wang Prof. Xiangfeng Shao Prof. Dezheng Yang Prof. Hao-Li Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(1):209-214
Two-dimensional (2D) hybrid perovskites have shown many attractive properties associated with their soft lattices and multiple quantum well structure. Herein, we report the synthesis and characterization of two new multifunctional 2D hybrid perovskites, (PED)CuCl4 and (BED)2CuCl6, which show reversible thermochromic behavior, dramatic temperature-dependent conductivity change, and strong ferromagnetism. Upon temperature change, the (PED)CuCl4 and (BED)2CuCl6 crystals exhibit a reversible color change between yellow and red-brown. The associated structural changes were monitored by in situ temperature-dependent powder X-ray diffraction (PXRD). The (BED)2CuCl6 exhibits superior thermal stability, with a thermochromic working temperature up to 443 K. The conductivity of (BED)2CuCl6 changes over six orders of magnitude upon temperature change. The 2D perovskites exhibit ferromagnetic properties with Curie temperatures around 13 K. 相似文献
128.
Plasmonic/Nonlinear Optical Material Core/Shell Nanorods as Nanoscale Plasmon Modulators and Optical Voltage Sensors
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Dr. Anxiang Yin Dr. Qiyuan He Zhaoyang Lin Dr. Liang Luo Yuan Liu Sen Yang Hao Wu Dr. Mengning Ding Prof. Yu Huang Prof. Xiangfeng Duan 《Angewandte Chemie (International ed. in English)》2016,55(2):583-587
Herein, we report the design and synthesis of plasmonic/non‐linear optical (NLO) material core/shell nanostructures that can allow dynamic manipulation of light signals using an external electrical field and enable a new generation of nanoscale optical voltage sensors. We show that gold nanorods (Au NRs) can be synthesized with tunable plasmonic properties and function as the nucleation seeds for continued growth of a shell of NLO materials (such as polyaniline, PANI) with variable thickness. The formation of a PANI nanoshell allows dynamic modulation of the dielectric environment of the plasmonic Au NRs, and therefore the plasmonic resonance characteristics, by an external electrical field. The finite element simulation confirms that such modulation is originated from the field‐induced modulation of the dielectric constant of the NLO shell. This approach is general, and the coating of the Au NRs with other NLO materials (such as barium titanate, BTO) is found to produce a similar effect. These findings can not only open a new pathway to active modulation of plasmonic resonance at the sub‐wavelength scale but also enable the creation of a new generation of nanoscale optical voltage sensors (NOVS). 相似文献
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130.
C Yu G Li X Guan J Zheng D Luo L Li 《Physical chemistry chemical physics : PCCP》2012,14(35):12368-12377
This work has initiated an investigation on the electrochemical behaviors and the structure changes of the composite electrode 0.3Li(2)MnO(3)·0.7LiMn(1/3)Ni(1/3)Co(1/3)O(2) when charged with different cut-off voltages. It is found that the charge cut-off voltages could not only affect the capacity property and coulombic efficiency, but also alter the electrode kinetics of the composite. As a consequence, the electrochemical activation of the composite electrode is highly dependent on the charge cut-off voltages: when the charge cut-off voltage is higher than 4.5 V, the inert component Li(2)MnO(3) in the composite electrode is completely activated. At the meanwhile, there occurred an irreversible oxygen loss during the initial charge process, which yielded a hollow sphere in the electrode. Regardless of charge voltages, Mn ions in the composite electrode were presented in an oxidation state of +4, while Co(2+) ions were detected at the surface of the electrode when cycled at low voltages. Ni ions in the composite could react with organic or inorganic species and then cover the surface of the cycled electrode. 相似文献