Hydrotherrnal synthesis, structure and property of nano-BaTiO3-based dielectric materials

A series of Ba1-xSrxTi1-yZryO3 (0≤x≤0.5, 0≤y≤0.4) and Ba1-xZnxTi1-ySnyO3 (0≤x≤0.3, 0≤y≤0.3) solid solutions were synthesized by Iow-temperature/Iow-pressure hydrothermal method below 170℃, 0.8 MPa. XRD pattern and cell parameters-composition figures of these prepared powders demonstrated that they are completely miscible solid solutions based on BaTiO3. Furthermore, TEM showed that they have a shape of uniform, substantially spherical particles with an average particle size of 70 nm in diameter. The sintered ceramics of those powders doped by Sr2+ and Zr4+ or Zn2+ and Sn4+ have dielectric constant twelve times higher than and dielectric loss 1/6 those of pure BaTiO3 phase at room temperature.     

In∶Nd∶LiNbO_3晶体倍频性能的研究

在LiNbO3 中掺进In2O3 和Nd2O3,以Czochralski技术生长了In∶Nd∶LiNO3 晶体通过光斑畸变法测得In∶Nd∶LiNbO3晶体的光损伤阈值为1. 98×104W /cm2,比Nd∶LiNbO3晶体的1. 6×102W /cm2高两个数量级以上;晶体吸收光谱的测试表明,In∶Nd∶LiNbO3 晶体的吸收边相对Nd∶LiNbO3 晶体发生紫移研究了In∶Nd∶LiNbO3 晶体的倍频性能,结果表明,In∶Nd∶LiNbO3 晶体的相位匹配温度在室温附近,倍频转换效率比Nd∶LiNbO晶体提高二倍.     

Electroresponsive Behavior of Sodium Alginate-g-Poly (acrylic acid) Hydrogel Under DC Electric Field

A novel sodium alginate-graft-poly(acrylic acid) (SA-g-PAA) hydrogel was prepared by radical graft copolymerization with ammonium persulfate (APS) as initiator and N,N′-methylene-bis-(acrylamide) (MBAA) as crosslinker, and its swelling properties and electroresponsive behavior in aqueous NaCl solutions were studied. The results indicated that the water take-up ability of the hydrogel decreased with the increasing ionic strength of aqueous NaCl solution. The hydrogel swollen in a NaCl solution bent toward the cathode under non-contact dc electric fields, and its bending speed and equilibrium strain increased with the increasing of applied voltage. With the increasing of ionic strength of aqueous NaCl solution, the equilibrium strain of the hydrogel increased first and then decreased gradually. The maximum equilibrium strain occurs when the ionic strength of aqueous NaCl solution is 0.03. By changing the direction of the applied potential cyclically, the hydrogel exhibited good reversible bending behavior.     

SMA纤维复合材料超弹性滞回特性研究

本对SMA纤维复合材料的轴向超弹性滞回特性进行理论分析，首先采用三相同心圆柱体模型和多胞模型计算材料的宏细观力学性能及其纤维轴向应力应变响应曲线。超弹性滞回特性的数值计算则采用平均抛物线插值法，最后给出环氧树脂/Ni-44.8wt%Ti纤维复合材料的具体数值结果。     

Numerical modelling of 8mm TM01-TE11 mode converter

A numerical study of TM₀₁-TE₁₁ circular waveguide mode converter, with its optimized size and structure, is presented in this paper. Many factors such as spurious modes, backward wave, perturbation functions of waveguide axis or radius, phase-rematching techniques and ohmic losses are taken into account for the influence to mode converter's efficiency and bandwidth. And the dimensions of an optimized model (f₀=35GHz. with input and output radius a₀=13.6mm) are given.     

铁基非晶磁环的高频响应和ns级脉冲响应特性

为了获取高频和快脉冲条件下铁基非晶磁芯的重要特性参数,对三种国产铁基非晶磁环的高频响应和快脉冲响应特性进行了实验研究.通过1∶1变压器测试回路发现,在1～20 MHz等振幅正弦源信号作用下,磁芯响应信号幅度损失率从0陡增至50％～60％,当源信号频率继续增大时,响应信号幅度损失率维持在50％～60％.对磁芯快前沿脉冲响...     

Recent advances in the bioanalytical methods of polyethylene glycols and PEGylated pharmaceuticals

Polyethylene glycols are synthetic polymers composed of repeating oxyethylene subunits, which have been known for non‐toxic, non‐immunogenic, non‐antigenic, good solubility in water and therefore approved for pharmaceutical applications. Recently, attachment or amalgamation of polyethylene glycols to therapeutic small molecules, peptides, proteins, or nanoparticles has become a mature technology for the sake of improving their pharmacokinetic and pharmacological profiles, also referred to as PEGylation. By comparison, there are only a few PEGylated pharmaceuticals have been registered for further clinical trials and even less was approved for marketing. High failure rate of PEGylated pharmaceuticals in pre‐clinical and clinical trials could be majorly attributed to their unclear pharmacokinetic behaviors. Therefore, the in vivo fate of the PEGylated pharmaceuticals for the various routes of administration needs to be thoroughly investigated An accurate in vivo pharmacological study thereof highly depends on the precise detection of polyethylene glycols as well as their fragments in biological matrixes. The goal of this review is to highlight the analytical methods that were developed and applied to evaluate the polyethylene glycols in pharmaceutical ingredients and excipients, which bring us closer to bridging the gap between the development of polyethylene glycol‐based drug delivery systems and their clinical application.     

Enhanced UV‐B Radiation Increases Glyphosate Resistance in Velvetleaf (Abutilon theophrasti)

Depletion of the ozone layer leads to increasing UV‐B radiation on the earth's surface, which may affect weeds and their responses to herbicides. However, the effect of increased UV‐B radiation on weeds and the interaction of weeds and herbicides are still obscure. The objective of this study was to compare glyphosate efficacy on velvetleaf that was grown under with and without increased UV‐B radiation. Leaf area, dry weight and net photosynthesis of velvetleaf seedlings were adversely affected by increased UV‐B radiation. Leaf cuticle wax significantly increased by 28% under increased UV‐B radiation. Glyphosate efficacy on velvetleaf, evaluated by shoot dry weight, was significantly decreased by increased UV‐B radiation. Exposure to increased UV‐B radiation significantly decreased ¹⁴C‐glyphosate absorption from 49% to 43%, and also resulted in less ¹⁴C‐glyphosate translocation out of treated leaves and less glyphosate accumulation in newly expanded leaves. The decrease in glyphosate efficacy was due to changes in absorption and distribution, which were attributed to increased cuticle wax and decreased photosynthesis caused by increased UV‐B radiation. These results suggest that the responses of weeds to herbicides may be affected by increased UV‐B radiation, to the extent that higher rates may be required to achieve the desired effects.     

Finite-time stability of multi-agent system in disturbed environment

Finite-time stability problem of multi-agent system in disturbed environment is a question with practical significance. In this paper, a multi-agent system moving with obstacle avoidance is studied. The multi-agent system is expected to form a desired formation in finite time. Finite-time control law for continuous multi-agent system is proposed, which ensures that all the agents can pass the obstacles on their way, and the relative position between two agents reaches a constant value in finite time. Based on some notations and proposition given in the paper, the stability analysis is presented. Finally some simulations are presented to show the effectiveness of the method.