Microstructure and corrosion behavior of electrodeposited nickel prepared from a sulphamate bath

Electrodeposited nickel was prepared from a sulphamate bath at different current densities ranging from 0.01 A cm^− 2 to 0.1 A cm^− 2. Based on the analysis of the microstructure, the corrosion behavior of the electrodeposited nickel in 3.5%NaCl solution was studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). All the electrodeposits display active-passive-transpassive behavior in potentiodynamic polarization process. The electrodeposits with the best corrosion resistance are obtained at 0.05 A cm^− 2. As for other electrodeposits, the corrosion potential and breakdown potential decrease with increasing current density used to prepare electrodeposits. However, the variation of both corrosion current density and passive current density is opposite to that of the corrosion potential. The changes in the charge-transfer resistance determined from the impedance spectra are consistent with the results determined from potentiodynamic measurements.     

Mechanical properties of Cu/SiCp composites fabricated by composite electroforming

The silicon carbide particles (SiC_p) dispersion-strengthened copper matrix composites (Cu/SiC_p) were fabricated by composite electroforming technology. The microstructure, tensile property and wear behavior of Cu/SiC_p composites were investigated. The results showed that composites with different SiC_p contents were obtained. The microstructure of the composite presented a uniform distribution of SiC_p in the matrix and good interfacial integrity. The hardness, yield strength and rigidity of the composites increased with increasing SiC_p content, but at the cost of ductility. Increasing SiC_p content in the composite was not always beneficial to the ultimate tensile strength and wear resistance. The ultimate tensile strength increased with SiC_p content increasing up to 16 vol.% and decreased as exceeding 16 vol.%, and the wear mass loss decreased with SiC_p content increasing up to 21 vol.% and increased again as exceeding 21 vol.%.     

Growth and spectral properties of Er:NaGd(WO4)2 crystal

A high optical quality Er³⁺-doped NaGd(WO₄)₂ single crystal with dimensions of ∅18 × 50 mm³ has been grown using the Czochralski method. The structure of the grown crystal was proved by X-ray powder diffraction. The accurate concentration of Er³⁺ ion in the crystal was measured. The absorption spectra, fluorescence spectra and fluorescence lifetime of the crystal were measured at room temperature. Green up-conversion luminescence has been observed when the crystal is excited at 965 nm.     

Solvothermal synthesis of CoFe<Subscript>2</Subscript>O<Subscript>4</Subscript> hollow spheres

Hollow CoFe₂O₄ spheres consisted of CoFe₂O₄ nanoparticles were synthesized by a facile solvothermal treatment of an ethylene glycol solution of FeCl₃ · 6H₂O, CoCl₂ · 6H₂O, and NaAc at 200 °C in the presence of polyethylene glycol and oleic acid. The products were characterized by powder X-ray diffraction, transmission electron microscopy, selected area electron diffraction, high-resolution transmission microscopy, scanning electron microscopy. The magnetic properties were evaluated using a vibrating sample magnetometer. The probable mechanism of the formation of Hollow CoFe₂O₄ spheres was discussed. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Mobile RFID的安全和隐私问题研究

射频识别技术被广泛应用于物体的自动识别,广泛地部署射频识别的标签会给用户的隐私带来新的安全威胁。目前,射频识别出现一种融合的趋势,阅读器被集成到移动电话中。移动射频识别主要应用于普通终端用户,用户的安全和隐私是最优考虑的问题。论文描述了移动RFID的应用场景和安全及隐私威胁,重点描述了移动环境下特殊的安全和隐私危险及解决移动RFID安全和隐私问题的安全体系构架方案。     

Left-Handed Transmission Line Based on Resonant-Slot Coupled Cavity Chain

In this letter, a novel realization of left-handed transmission line is presented; the proposed structure is based on identical symmetrical resonant-slot coupled cavity chain. The dispersion characteristic of the resonant-slot coupled cavity chain is analyzed by means of field theory and finite element method (FEM) eigenmode simulation, and a left-handed passband is proved to exist. A backward wave behavior is demonstrated unambiguously from FEM driven modal simulation. The phase front is observed to be in the opposite direction with respect to the energy one for a finite nine-unit cell prototype     

2.5Gb/s光纤通信系统的电色散补偿技术研究

介绍了逐渐受到更多关注的高速光纤通信系统的电色散补偿(EDC)技术.我们将研究对象放在了采用啁啾DFB激光器、直接调制方式的2.5Gb/s高速光纤通信系统,通过仿真得到:啁啾系数为2的DFB激光器传输400km后经过8抽头判决反馈均衡器处理可有效地消除色散导致的码间干扰.     

Preparation and Degradation Characteristics of Poly(d,1-laetide) Composite Films

PDLLA/CHI/β-TCP/NGF composite films were prepared by a solvent evaporation method. The degradation characteristics of the poly(d,1-lactide)composite films were studied in vitro and in vivo. The acidity produced by poly(d,1-lactide)materials was not obvious.Adding chitosan andβ-TCP can relieve the acidity problem and improve strength performance of films.The NGF has influences on the degradation characteristics of films.It is verified that PDLLA/CHI/β-TCP/NGF composite films prepared by solvent evaporation method have excellent degradation characteristics.It can be used as a perfect biomaterial for repairing nerve injuries.     

区域人力资本运营的差异比较研究

基于人力资源数量相当的前提下,对中部六省、东部五省人力资本运营的差异进行了比较研究,得到了区域人力资本运营差异的成因主要在于区域人力资本存量、人力人才资源使用效益、区域经济科技平台、人力人才资源素质差异等方面的结论,提出了中部地区人力人才资源开发一体化的战略思路.     

纳豆芽孢杆菌的诱变育种研究

通过实验研究了纳豆芽孢杆菌的育种方法,对初始纳豆芽孢杆菌进行了紫外及微波诱变,采用牛奶-琼脂板筛选菌种,得到了目的菌株QBNW467.研究表明,采用牛奶-琼脂板法筛选诱变后的纳豆芽孢杆菌方法可行,用该法筛选出的菌株QBNW467的固体发酵产酶活性可达2200 IU.g-1.