Molybdenum Carbide‐Embedded Multichannel Hollow Carbon Nanofibers as Bifunctional Catalysts for Water Splitting

With the environmental pollution and non‐renewable fossil fuels, it is imperative to develop eco‐friendly, renewable, and highly efficient electrocatalysts for sustainable energy. Herein, a simple electrospinning process used to synthesis Mo₂C‐embedded multichannel hollow carbon nanofibers (Mo₂C‐MCNFs) and followed by the pyrolysis process. As prepared lotus root‐like nanoarchitecture could offer rich porosity and facilitate the electrolyte infiltration, the Mo₂C‐MCNFs delivered favourable catalytic activity for HER and OER. The resultant catalysts exhibit low overpotentials of 114 mV and 320 mV at a current density of 10 mA cm^?2 for HER and OER, respectively. Furthermore, using the Mo₂C‐MCNFs catalysts as a bifunctional electrode toward overall water splitting, which only needs a small cell voltage of 1.68 V to afford a current density of 10 mA cm^?2 in the home‐made alkaline electrolyzer. This interesting work presents a simple and effective strategy to further fabricating tunable nanostructures for energy‐related applications.     

Optimized Fluorescent Probe for Specific Imaging of Glutathione S‐Transferases in Living Cells and Mice

GSTP1 has been considered to be a marker for malignancy in many tissues. However, the existing GST fluorescent probes are unfavorable for in vivo imaging because of the limited emission wavelength or insufficient fluorescence enhancement (six‐fold). The limited fluorescence enhancement of GST fluorescent probes is mainly ascribed to the high background signals resulting from the spontaneous reaction between GSH and the probes. In this work, a highly specific GST probe with NIR emission has been successfully developed through optimization of the essential unit of the probe to repress the spontaneous reaction. The novel GST probe exhibits over 100‐fold fluorescence enhancement upon incubation with GSTP1/GSH and high selectivity over other potential interference. In addition, the probe has been proved to be capable of tracking endogenous GST in A549 cells. Finally, the in vivo imaging results demonstrate that the probe can be used for effective imaging of endogenous GST activity in subcutaneous tumor mouse with high contrast.     

基于能量传递规律的海洋立管涡激振动抑制研究

涡激振动是造成海洋立管疲劳损伤的重要因素, 抑制振动能够保障结构安全, 延长使用寿命. 多数涡激振动抑制方法基于干扰流场的方式, 但在复杂环境条件下, 仅通过干扰流场对振动的抑制效果有限. 因此, 从结构层面考虑开展了海洋立管涡激振动抑制研究. 基于能量传递的理论, 阐述了立管涡激振动过程中的能量传递规律. 振动能量以行波形式由能量输入区传播至能量耗散区, 主要在能量耗散区被消耗. 通过局部增大能量耗散区的阻尼, 增加振动能量在传播过程中的消耗, 实现涡激振动抑制. 为了求解立管涡激振动响应, 构建了尾流振子预报模型, 并根据实验结果验证了理论模型的可靠性. 基于理论计算得到的能量系数, 判定立管涡激振动的能量输入区和能量耗散区. 通过对比立管增大阻尼前后的响应, 分析了涡激振动抑制效果. 研究结果表明: 在能量输入区增大阻尼对涡激振动的抑制效果并不显著; 在能量耗散区增大阻尼使能量衰减系数达到临界值之后, 能够显著降低立管上部和底部的涡激振动位移; 当能量衰减系数超过临界值后, 继续增大耗散区阻尼对涡激振动抑制效果的提升不明显.      

Nonlinear vibration isolation via an innovative active bionic variable stiffness adapter (ABVSA)

Nonlinear Dynamics - During the process of spacecraft launch, the extreme vibration environment is the major influence factor that induces the failure of the mission. Inspired by the smooth motions...     

Ab initio study on the reaction of Y+ + NH3 → Y+ NH + H2

The reaction of Y⁺ + NH₃ → Y⁺ NH + H₂ was theoretically investigated by ab initio MO methods. Two possible pathways (1–1 H₂ loss and 1–2 H₂ loss) on the singlet potential energy surface and reaction mechanism were examined and discussed. The singlet and triplet PESs of this reaction system were compared to confirm the correctness of spin conservation concepts. © 1996 John Wiley & Sons, Inc.     

Syndioselective propylene polymerizations by ansa-zirconocenium catalyst

The effect of reaction conditions, including catalyst concentration, temperature, and immobilization on support, have been investigated for syndioselective propylene polymerization by the “bare” zirconocenium ion generated from 1,1-diphenyl-methylidene(1-η⁵-cyclopentadienyl)(9-η⁵-fluorenyl)zirconium-dichloride precursor (2). Neither variation of the catalyst concentration nor immobilization of 2 on silica support affect the syndiospecificity of polymerization. The stereoregularity of the syndiotactic polypropylene, as judged from the melting transition temperature and homosteric r-pentad population by ¹³C-NMR, were found to be proportional to polymer molecular weight. These behaviors are compared with a typical isoselective catalyst ethylenebis(4,5,6,7-tetrahydroindenyl) Zr precursor (4). They are in close resemblance in the case of the S-enantiomeric complex of 4, but the racemic mixture of 4 is markedly inferior. The origins of stereo- and regio-errors are discussed. © 1996 John Wiley & Sons, Inc.     

Polymerization of 2,4-hexadiyn-1,6-diol by chemical vapor deposition

2,4-Hexadiyn-1,6-diol (HDO) was polymerized on glass and silicon plates by chemical vapor deposition without transition metal catalysis to form homogeneous thin films. Structural properties of the films were investigated by FT-IR, UV-visible, Raman, x-ray diffraction, and XPS spectroscopic analyses. The structure of CVD-polymerized HDO (CVD-PHDO) films was different from that of metathesis polymerized HDO (metathesis-PHDO), showing a polyacene-based structure but no polyene structure with acetylenic side groups. © 1996 John Wiley & Sons, Inc.     

Synthesis of Lanthanide–Alkylaluminium Bimetallic Complexes and Studies on Their Catalytic Activities for Polymerization of Some Polar Monomers

Three new lanthanide (Ln)–alkylaluminium (Al) bimetallic complexes with the formula [(μ-CF₃CO₂)₂Ln(μ-CF₃CHO₂)AlR₂ · 2THF]₂ (Ln=Nd, Y, R=i-C₄H₉ (i-Bu); Ln=Eu, R=C₂H₅(Et); THF=tetrahydrofuran) were synthesized by the reaction of Ln(CF₃CO₂)₃ (Ln=Nd, Y) with HAl (i-Bu)₂ and of Eu(CF₃CO₂)₃ with AlEt₃, respectively. Their crystal structures were determined by X-ray diffraction at 233 K. [(μ-CF₃CO₂)₂Nd (μ-CF₃CHO₂)Al(i-Bu)₂ · 2THF]₂ (Nd–Al) and [(μ-CF₃CO₂)₂Y(μ-CF₃CHO₂)Al(i- Bu)₂ · 2THF]₂ (Y–Al) are isomorphous and crystallize in space group P 1 with a =12.441(3) Å [12.347(5) Å for Y–Al], b =12.832(3) Å [12.832(4) Å], c =11.334(3) Å [11.292(8) Å], α=104.93 (2)° [104.45(4)°], β=98.47(2)° [98.81(4)°], γ=64.60(2)° [64.30(3)°], R =0.519 [0.113], R _w=0.0532 [0.110], Z =1 and [(μ-CF₃CO₂)₂Eu(CF₃ CHO₂)AlEt₂ · 2THF]₂(Eu–Al) in space group P 2₁/ n with a =11.913(6) Å, b =14.051(9) Å, c =17.920(9) Å, α=101.88(11)°, β=γ=90°, R =0.0509, R _w=0.0471 and Z =2. The six CF₃CO     

Effect of Cu Ions on the Dipole Moments and Polarization of Strontium Barium Niobate Single Crystals

The crystal growth, the ferroelectric hysteresis loops, and the infrared reflectivity spectra of coppermodified strontium barium niobate (SBN) single crystals are reported. Compared with the undoped SBN crystals, the copper-modified crystals have stable hysteresis loops, the spontaneous polarization of which is about 0.30 C/m², but that of the undoped SBN crystals is only about 0.12 C/m². Their coercive field strength is all about 340 V/mm. The experimental results of the infrared spectra show that the infrared reflectivities vary as the orientations of the dipole moments owing to the copper-doping. The c-axis becomes the most stable orientation of the dipole moments, and the polarization will be locked and won't recede if the copper-modified crystals are polarized into monodomains.     

Magnetron sputtering deposition of silicon nitride on polyimide separator for high-temperature lithium-ion batteries

To date,lithium-ion batteries are becoming increasingly significant in the application of portable devices and electrical vehicles,and revolutionary progress in theoretical research and industrial application has been achieved.However,the commercial polyolefin separators with unsatisfying electrolytes affinity and poor thermal stability have extremely restricted the further application of lithium-ion batteries,especially in the high-temperature fields.In this work,magnetron sputtering deposition technique is employed to modify the commercial polyimide separator by coating silicon nitride on both sides.Magnetron sputtering deposition modified polyimide(MSD-PI)composite separator shows high thermal stability and ionic conductivity.More importantly,compared with the cells using Celgard separator,the cells with MSD-PI separator exhibit superior electrochemical performance,especially long-term cycle performance under high temperature environment,owing to the high thermal conductivity of surface Si3 N4 particles.Hence,lithium-ion batteries with MSD-PI separator are capable of improving thermal safety and capacity retention,which demonstrates that magnetron sputtering deposition technique could be regarded as a promising strategy to develop advanced organic/inorganic composite separators for high-temperature lithium-ion batteries.