Rational design of perfluorinated sulfonic acid ionic sieve modified separator for high-performance Li-S battery

Journal of Solid State Electrochemistry - Practical application of Li-S battery is limited by the fast capacity decay and low coulombic efficiency caused by the shuttling phenomenon. Modification...     

In-situ SiN combined with etch-stop barrier structure for high-frequency AlGaN/GaN HEMT

The etch-stop structure including the in-situ SiN and AlGaN/GaN barrier is proposed for high frequency applications.The etch-stop process is realized by placing an in-situ SiN layer on the top of the thin AlGaN barrier.F-based etching can be self-terminated after removing SiN,leaving the AlGaN barrier in the gate region.With this in-situ SiN and thin barrier etch-stop structure,the short channel effect can be suppressed,meanwhile achieving highly precisely controlled and low damage etching process.The device shows a maximum drain current of 1022 mA/mm,a peak transconductance of 459 mS/mm,and a maximum oscillation frequency(fmax)of 248 GHz.     

Nb(iPrNPMe2)3Fe–PMe3: A potential high reactivity heterobimetallic catalyst for acetylene cycloadditions

Alkynes cycloaddition reactions are powerful tools for constructing cyclic molecules with optimal atom efficiency, but these reactions cannot proceed at ambient temperature without transition-metal catalysts. In this work, a heterobimetallic complex featuring an Nb–Fe triple bond, Nb(ⁱPrNPMe₂)₃Fe–PMe₃, has been evaluated as the potential catalyst for acetylene cycloaddition, using density functional theory. The calculated results show that the singlet-state (i.e. ground-state) Nb(ⁱPrNPMe₂)₃Fe–PMe₃ can be applied to benzene synthesis, but is not suitable for cyclobutadiene. Benzene can be obtained easily at room temperature and is the unique product on the singlet potential surface. The irradiation of infrared-red light can drive the excitation of singlet Nb(ⁱPrNPMe₂)₃Fe–PMe₃ to its triplet state. Both benzene and cyclobutadiene can be formed on the triplet reaction potential surface due to their low energy barriers. Therefore, Nb(ⁱPrNPMe₂)₃Fe–PMe₃ is a potential high reactivity heterobimetallic catalyst for the cyclotrimerization of alkynes. In the reaction process, the catalytic active site of Nb(ⁱPrNPMe₂)₃Fe–PMe₃ moves from niobium to iron.     

Pharmacokinetic study of tanshinol and ligustrazine in rat plasma after intravenous administration of tanshinol and Danshen Chuanxiongqin Injection

To investigate the effect of ligustrazine on the pharmacokinetic profile of tanshinol after intravenous administration in rats, a sensitive liquid chromatography tandem mass spectrometry method was developed and validated for quantitative determination of tanshinol and ligustrazine in rat plasma. After prepared by protein precipitation, the analytes were separated on a Waters Acquity HSS T3 column (100 × 2.1 mm, 1.8μm) and eluted by 0.1% formic acid in water and acetonitrile at a flow rate of 0.4 ml/min. The precursor–product ion transitions were m/z 197.0 → 135.0 for tanshinol, m/z 417.1 → 255.1 for liquiritin (internal standard) in negative ion mode and m/z 137.1 → 55.0 for ligustrazine in positive ion mode. To avoid the interference of tanshinol metabolite transformation, the stability of analytes in samples collected after administration was assessed. The validated method was successfully applied to a pharmacokinetic study after intravenous administration of single tanshinol and Danshen Chuanxiongqin Injection. After Danshen Chuanxiongqin injection administration, the values of elimination half-time, area under the concentration–time curve and C_o were 0.36 ± 0.13 h, 1.29 ± 0.37 μg/ml h and 10.51 ± 2.58 μg/ml for male rats, respectively. In the single tanshinol group, the corresponding values were 0.56 ± 0.24 h, 1.85 ± 0.44 μg/ml h and 14.11 ± 2.26 μg/ml for male rats—30–40% higher than those for the Danshen Chuanxiongqin Injection group. There was a significant different between male and female rats. This study provided information on the influence of ligustrazine on the pharmacokinetic characteristics of tanshinol after intravenous administration of Danshen Chuanxiongqin Injection in rats, which will be helpful for its clinical application.     

Electron-donating methoxy group enhances the stability and efficiency of indole-based fluorescent probe for detecting Cu2+

Research on Chemical Intermediates - Two novel Schiff-base fluorescent probes bearing different substituents were synthesized by the reaction of indole derivatives with 4-aminoantipyrine. The...     

蓝宝石冲击消光晶向效应的第一性原理

蓝宝石的冲击消光现象是高压领域中的研究热点.低压段(86 GPa范围内)的实验研究表明蓝宝石的冲击消光与晶向相关,但在高压段(压力范围:131255 GPa)是否也具有晶向相关性目前尚不清楚.为此,利用第一性原理方法,分别计算了八个不同晶向的蓝宝石理想晶体和含氧离子空位缺陷晶体在高压段的光吸收性质,结果发现:1)蓝宝石在高压段的冲击消光表现出明显的晶向效应,且该效应还随压力增大而增强;一步的数据分析可以看出,在冲击实验采用的波段内,a晶向的消光最弱(透明性最好),c晶向的消光最强与c晶向的消光接近,g晶向的消光要弱于s晶向的消光.鉴于此,如果在高压段开展加窗冲击波实验,建议选择a晶向或m晶向的蓝宝石作为其光学窗口.本文结果不仅有助于深入地认识蓝宝石在极端条件下的光学性质,而且对未来的实验研究有重要的参考作用.     

Harmonically pump a femtosecond optical parametric oscillator to 1.13 GHz by a femtosecond 515 nm laser

We demonstrate a harmonically pumped femtosecond optical parametric oscillator(OPO)laser using a frequency-doubled mode-locked Yb:KGW laser at a repetition rate of 75.5 MHz as the pump laser.Based on a bismuth borate nonlinear crystal,repetition rates up to 1.13 GHz are realized,which is 15 times that of the pump laser.The signal wavelength is tunable from 700 nm to 887 nm.The maximum power of the signal is 207 m W at the central wavelength of 750 nm and the shortest pulse duration is 117 fs at 780 nm.The beam quality(M^2 factor)in the horizontal and vertical directions of the output beam are 1.077 and 1.141,respectively.     

Porous carbon nanospheres with moderately oriented domains for EDLC electrode

Porous carbon nanospheres with moderately oriented microcrystalline structures were prepared via a relatively simple synthetic route in this article. CTAB acted as a structure‐directing agent to induce small sulfonated pitch (SP) pieces to assemble orderly. By this means, the formation of carbon nanospheres was simultaneous with the moderate orientation of carbon microcrystalline without additional process. Owing to the moderately oriented microcrystalline structures, the resultant sample CNS3 possessed a high e‐conductivity of 62.5 S/m. When used as an electrode material for EDLCs, it showed excellent electrochemical properties even without any conductive agent. In an organic electrolyte, the resultant sample CNS3 possessed a high specific capacitance of 155 F/g at 20 A/g and outstanding cycle life with 94.2% capacity retention after 10,000 cycles. This work puts forward a novel design for carbon nanospheres with moderately oriented domains by a simple and energy‐efficient means.     

Space-Confined Atomic Clusters Catalyze Superassembly of Silicon Nanodots within Carbon Frameworks for Use in Lithium-Ion Batteries

Incorporating nanoscale Si into a carbon matrix with high dispersity is desirable for the preparation of lithium-ion batteries (LIBs) but remains challenging. A space-confined catalytic strategy is proposed for direct superassembly of Si nanodots within a carbon (Si NDs⊂C) framework by copyrolysis of triphenyltin hydride (TPT) and diphenylsilane (DPS), where Sn atomic clusters created from TPT pyrolysis serve as the catalyst for DPS pyrolysis and Si catalytic growth. The use of Sn atomic cluster catalysts alters the reaction pathway to avoid SiC generation and enable formation of Si NDs with reduced dimensions. A typical Si NDs⊂C framework demonstrates a remarkable comprehensive performance comparable to other Si-based high-performance half LIBs, and higher energy densities compared to commercial full LIBs, as a consequence of the high dispersity of Si NDs with low lithiation stress. Supported by mechanic simulations, this study paves the way for construction of Si/C composites suitable for applications in future energy technologies.