Cyclic softening of the Sn-3.8Ag-0.7Cu lead-free solder alloy with equiaxed grain structure

Low-cycle fatigue behavior of the Sn-Ag-Cu ternary-eutectic alloy was investigated under a fully reversed loading condition. The solder alloy exhibited cyclic softening early in the fatigue life and continued to soften as the number of fatigue cycles increased. Following cyclic loading, numerous microcracks were found in the microstructure. Most of the microcracks were located along the grain boundaries in the areas with finer grains. The areal density of the microcracks increased with both strain amplitude and cycle number. By combining percolation theory with microcracking analysis, the cycle-dependent softening behavior was shown to result from accumulation of microcrack density with fatigue cycles.     

Performance Degradation due to Cascaded Erbium Doped Fiber Amplifier Power Transients in Wavelength Routed Optical Networking

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压缩空气管路系统的设计与制作

设计与制作了一种压缩空气管路系统，该系统简易、实用，适用于替代昂贵的高压瓶装Ｎ２，充当电动控制的气动开关的气源。     

Surfactant‐Free,Self‐Assembled PVA‐Iron Oxide/Silica Core–Shell Nanocarriers for Highly Sensitive,Magnetically Controlled Drug Release and Ultrahigh Cancer Cell Uptake Efficiency

Surfactant‐free, self‐assembled iron oxide/silica core–shell (SAIO@SiO₂) nanocarriers were synthesized as bifunctional magnetic vectors that can be triggered for the controlled release of therapeutic agents by an external magnetic field. In addition, drug release profiles can be well‐regulated through an ultrathin layer of silica shell. The hydrophobic drug molecules were encapsulated within the iron oxide‐PVA core and then further covered with a thin‐layer silica shell to regulate the release pattern. Remote control of drug release from the SAIO@SiO₂ nanocarriers was achieved successfully using an external magnetic field where the core phase being structurally disintegrated to a certain extent while subjected to magnetic stimulus, resulting in a burst release of the encapsulated drug. However, a relatively slow and linear release restored immediately, directly after removal of the stimulus. The nanostructural evolution of the nanocarriers upon the stimulus was examined and the mechanism for controlled drug release is proposed for such a core–shell nanocarrier. Surprisingly, the surfactant‐free SAIO@SiO₂ nanocarriers demonstrated a relatively high uptake efficiency from the HeLa cell line. Together with a well‐regulated controlled release design, the nanocarriers may provide great advantages as an effective cell‐based drug delivery nanosystem for biomedical applications.     

二维Helmholtz方程不适定问题的一种算子软化正则法

本文研究带有混合边界的二维Helmholtz方程不适定问题.为了获得稳定的数值解，利用基于de la ValléePoussin算子的软化正则方法，得到了正则近似解，给出正则近似解与精确解之间在先验参数选取规则之下的误差估计，并通过数值实验检验了数据有噪声扰动时方法的有效性和稳定性.     

全球频率监管热点问题

近年来,随着无线通信技术快速发展,市场对频率资源需求的不断增长。文章主要研究探讨了LTE、Femtocell等新型无线电通信技术对频率分配的影响,以及数字红利、White Spaces和等频率监管热点问题。     

Synthesis and characterization of a narrow‐bandgap polymer containing alternating cyclopentadithiophene and diketo‐pyrrolo‐pyrrole units for solar cell applications

We have synthesized a narrow‐bandgap conjugated polymer ( PCTDPP ) containing alternating cyclopentadithiophene (CT) and diketo‐pyrrolo‐pyrrole (DPP) units by Suzuki coupling. This PCTDPP exhibits a low band gap of 1.31 eV and a broad absorption band from 350 to 1000 nm, which allows it to absorb more available photons from sunlight. A bulk heterojunction polymer solar cell incorporating PCTDPP and C₇₀ at a blend ratio of 1:3 exhibited a high short‐circuit current of 10.87 mA/cm² and a power conversion efficiency of 2.27%. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1669–1675, 2010     

Experimental and Theoretic Study of the Dielectric Properties of Ethanol + Methanol Mixtures

The main objective of this work is to measure the complex permittivity of ethanol + methanol liquid solutions over the full composition range at the temperatures 293, 303 and 313 K by the resonant cavity perturbation method. Dielectric parameters were derived using mixture formulae, and the values of excess permittivity and excess inverse relaxation time were determined using these parameters. By comparing the calculated results to the experiment values it was found that the classical Debye equation needs to be modified to calculate the complex permittivity.     

One-pot Preparation of Fluorinated Polyhydrobenzoacridine-1-one Derivatives under Microwave Irradiation and Solvent-free Conditions

A facile and efficient synthesis of fluorine‐containing polyhydrobenzoacridines was accomplished by a three‐component coupling of fluorinated aldehyde, α‐naphthylamine, and 1,3‐cyclohexanedione or dimedone under microwave irradiation and solvent‐free conditions without catalyst. All new compounds were obtained in moderate to good yields and characterized by standard spectroscopic methods.     

中草药有效成分山姜素的固体表面室温磷光法研究

本文选择滤纸作基质，以ＬｉＡｃ作重原子微扰剂，建立了测定中草药中痕量有效成分山姜素的滤纸表面室温磷光法。该法取样量少（２μＬ），线性范围宽（２．９～５８０ｎｇ／斑），灵敏度高（检出限０．４０ｎｇ／斑），操作简便、快速。