WAVES IN PRE-STRETCHED INCOMPRESSIBLE SOFT ELECTROACTIVE CYLINDERS:EXACT SOLUTION

This paper studies wave propagation in a soft electroactive cylinder with an underlying finite deformation in the presence of an electric biasing field.Based on a recently proposed nonlinear framework for electroelasticity and the associated linear incremental theory,the basic equations governing the axisymmetric wave motion in the cylinder,which is subjected to homogeneous pre-stretches and pre-existing axial electric displacement,are presented when the electroactive material is isotropic and incompressible.Exact wave solution is then derived in terms of(modified) Bessel functions.For a prototype model of nonlinear electroactive material,illustrative numerical results are given.It is shown that the effect of pre-stretch and electric biasing field could be significant on the wave propagation characteristics.     

PDMS基柔性近眼显示波导光学系统设计

针对近眼显示系统视场小、体积笨重、柔性差、量产性差等问题,文章采用在系统中加入自由曲面和聚二甲基硅氧烷(PDMS)基的设计方法.论述了柔性近眼显示光学系统的设计要求和工作原理,进行初始结构建立;分析了系统杂散光产生的原因,进行杂散光抑制设计;采用XY多项式自由曲面替换传统非球面,进行系统像差校正;采用柱面波导模拟波导弯...     

Facile in situ synthesis of the bismuth oxychloride/bismuth niobate/TiO(2) composite as a high efficient and stable visible light driven photocatalyst

Fe-ions modified mesoporous Bi(2)WO(6) nanosheets (Fe-Bi(2)WO(6)) were successfully synthesized via a simple two-step method, which involved a template-free hydrothermal process and a following impregnation treatment. The resultant products were characterized by XRD, TEM, XPS, EDX, ESR, UV-Vis, PL, and visible light photocatalytic measurements. Experimental results indicated that the addition of a small amount Fe-ions (optimized content at 0.1 wt.%) could evidently improve the activity of Bi(2)WO(6). The apparent reaction rate of Fe-Bi(2)WO(6)-0.1% (k, 0.099 min(-1)) was 3.2 times higher than that of Fe-Bi(2)WO(6)-0% (k, 0.031 min(-1)). The Fe-ions mainly existed as Fe(3+) and Fe(2+) ions, which were uniformly distributed on the surface of Bi(2)WO(6) nanosheets and some Fe(3+)-ions substituted Bi(3+)-ions in Bi(2)O(2) layers. Both of the concentration and state of Fe-ions played vital factors for the improved visible light photocatalytic activities.     

活性炭催化苯一步羟基化制备苯酚(英文)

将市售活性炭经过硝酸、过氧化氢及不同温度进行处理后用于苯的羟基化反应,并研究了活性炭催化苯羟基化反应机理.用Boehm滴定,N2吸附-脱附及X射线光电子能谱对活性炭进行了表征.结果表明,反应体系的pH对催化剂活性具有重要的影响,活性炭对苯的吸附受表面含氧基团含量的影响.模型化合物反应结果表明,活性炭表面的酚羟基和羰基是反应的活性位,两者可相互转化,并在一定的pH条件下达到平衡,该转化使得H2O2活化为羟基自由基,进而与苯反应生成苯酚.在苯羟基化反应中,活性炭表现出良好且稳定的催化性能,苯酚收率可达14.4%.     

In vivo metabolism study of polygalic acid in rat using HPLC-ESI-MSn

A very simple and direct method has been established for the determination of polygalic acid and its metabolites in rat urine based on HPLC coupled with electrospray ionization multi-stage tandem mass spectrometry (HPLC-ESI-MS(n)). The rats were administered a single dose (100 mg/kg) of polygalic acid by oral gavage. The urine samples were collected and purified through a C(18) solid-phase extraction cartridge, and then these pretreated samples were injected into a reversed-phase C(18) column with a gradient elution program, whereas acetonitrile-0.5% aqueous formic acid was used as mobile phase and detected by an on-line MS/MS system. As a result, the parent drug and its four metabolites were identified and characterized in rat urine for the first time by comparing their changes in molecular mass (ΔM), retention times and full-scan MS(n) spectra with those of the parent drug. A possible metabolic pathway of polygalic acid was investigated and proposed. More importantly, the results demonstrated that the newly developed method (HPLC-ESI-MS(n)) was sensitive, simple and suitable for the determination of polygalic acid and its metabolites in biological samples.     

静电层层组装的微量热研究

利用静电层层组装技术,在CaCO3微球表面交替沉积带相反电荷的聚电解质制备多层膜。在静电层层组装过程中伴随热效应出现,借助微量热仪对该热效应进行精确测定,从而为层层组装过程提供一种新的表征手段。     

Comparative study of cable parallel manipulators with and without hybrid-driven planar five-bar mechanism

Cable parallel manipulators (CPMs) relay on cables instead of rigid links to support and manipulate the end-effector. The CPMs are required not only for operations with lower inertia and high payload, but also for output with greater flexibility. The paper is devoted to present and analyze a cable parallel manipulator with and without hybrid-driven planar five-bar mechanism (HDPM). The cable parallel manipulator with the HDPM combines positive features of both the cable parallel manipulator and the HDPM. Comparative study of kinematics and dynamics of the CPMs with and without HDPM are studied. Drive torques and drive powers are given to compare the load carrying capacity of the two manipulators, and workspace, stiffness performance, singularity analysis are also carried out. Simulation examples are presented to demonstrate the CPMs with and without HDPM and their mechanics performance.     

Ultra-small platinum nanoparticles segregated by nickle sites for efficient ORR and HER processes

In the electrochemical process,Pt nanoparticles(NPs)in Pt-based catalysts usually agglomerate due to Oswald ripening or lack of restraint,ultimately resulting in reduction of the active sites and catalytic efficiency.How to uniformly disperse and firmly fix Pt NPs on carbon matrix with suitable particle size for catalysis is still a big challenge.Herein,to prevent the agglomeration and shedding of Pt NPs,Ni species is introduced and are evenly dispersed in the surface of carbon matrix in the form of Ni-N-C active sites(Ni ZIF-NC).The Ni sites can be used to anchor Pt NPs,and then effectively limit the further growth and agglomeration of Pt NPs during the reaction process.Compared with commercial Pt/C catalyst,Pt@Ni ZIF-NC,with ultralow Pt loading(7 wt%)and ideal particle size(2.3 nm),not only increases the active center,but also promotes the catalysis kinetics,greatly improving the ORR and HER catalytic activity.Under acidic conditions,its half-wave potential(0.902 V)is superior to commercial Pt/C(0.861 V),and the mass activity(0.38 A per mg Pt)at 0.9 V is 4.7 times that of Pt/C(0.08 A per mg Pt).Besides,it also shows outstanding HER performance.At 20 and 30 mV,its mass activity is even 2 and 6 times that of Pt/C,respectively.Whether it is under ORR or HER conditions,it still shows excellent durability.These undoubtedly indicate the realization of dual-functional catalysts with low-Pt and high-efficiency properties.     

Acetylene black-ionic liquids composite electrode: a novel platform for electrochemical sensing

A novel electrochemical sensing platform was developed that is based on the modification of a glassy carbon electrode with acetylene black and ionic liquids. The resulting electrode exhibited excellent electrocatalytic activity towards trifluralin in showing markedly increased redox peak currents. The experimental parameters affecting the response to trifluralin were optimized. Under optimal conditions, a linear response was obtained in the range from 80 nM to 12 µM of trifluralin (R?=?0.9994). The detection limit is 10 nM (at S/N?=?3) after open-circuit accumulation for 120 s. The method was successfully applied to determine trifluralin in soil samples. Features such as a large electroactive area, fast electron transfer and low background current make this composite electrode a promising platform for fabricating reliable electrochemical sensors for various species.