Effect of electrotransport treatment on susceptibility of high-strength low alloy steel to hydrogen embrittlement

Electrotransport theory is defined as mass transportation of solute such as hydrogen in metal under the influence of an electrostatic force field. In this study, electrotransport treatment was applied to remove the accumulated hydrogen inside of the high-strength low alloy steel. The effectiveness of the electrotransport treatment was evaluated by hydrogen concentration measurement, slow strain rate test, and fracture surface analysis. The efficiency of electrotransport treatment is improved with increasing applied current and time, and the highest efficiency was obtained as 88.7% at 450 A for 40 min. The ultimate tensile strength and elongation of specimen after electrotransport treatment was enhanced dramatically in comparison with that of specimen under hydrogen charging condition. The brittle fracture mode was observed on the hydrogen charged specimen, but a clear ductile fracture mode was observed on the specimen after electrotransport treatment. These results confirm that the electrotransport treatment is effective to remove the accumulated hydrogen inside of the high-strength low alloy steel.     

台达机电产品在晶体切断机上的应用

晶体切断机为晶体切断专用设备,适用于半导体材料晶体坯料去头尾、切段等工作。本文主要介绍台达机电产品在该设备上的应用。     

Engineering design of a cardiac myocyte

We describe a design algorithm to build a cardiac myocyte with specific spatial dimensions and physiological function. Using a computational model of a cardiac muscle cell, we modeled calcium (Ca²⁺) wave dynamics in a cardiac myocyte with controlled spatial dimensions. The modeled myocyte was replicated in vitro when primary neonate rat ventricular myocytes were cultured on micropatterned substrates. The myocytes remodel to conform to the two dimensional boundary conditions and assume the shape of the printed extracellular matrix island. Mechanical perturbation of the myocyte with an atomic force microscope results in calcium-induced calcium release from intracellular stores and the propagation of a Ca²⁺ wave, as indicated by high speed video microscopy using fluorescent indicators of intracellular Ca²⁺. Analysis and comparison of the measured wavefront dynamics with those simulated in the computer model reveal that the engineered myocyte behaves as predicted by the model. These results are important because they represent the use of computer modeling, computer-aided design, and physiological experiments to design and validate the performance of engineered cells. The ability to successfully engineer biological cells and tissues for assays or therapeutic implants will require design algorithms and tools for quality and regulatory assurance. W.J. Adams and T. Pong contributed equally to this work.     

Characterization of slow charge transfer processes in differential pulse voltammetry at spherical electrodes and microelectrodes

The use of differential pulse voltammetry at spherical electrodes for the study of the kinetic of charge transfer processes is analyzed. An analytical solution is presented, valid for any value of the electrode radius, the heterogeneous rate constant and the transfer coefficient.Several reversibility criteria are established based on the variation of DPV peak with the duration of the potential pulses and the electrode radius. Moreover, general working curves for extraction of kinetic parameters from DPV experiments are given.The anomalous shape of DPV curves for quasireversible processes with small values of the transfer coefficient is reported. The effect of the presence of both electroactive species on DPV curves for quasireversible and irreversible systems is also studied.     

Influence of dynamic straining on hydrogen embrittlement of UNS-G41300 and UNS-S31803 steels in a low H2S concentration environment

The hydrogen embrittlement of UNS-G41300 and UNS-S31803 steels in sodium thiosulphate solutions was studied. Slow strain rate and electrochemical tests were used. The influence of elastic and plastic strain on the hydrogen embrittlement process of these materials was investigated.The results showed that thiosulphate solutions efficiently simulate an aggressive environment containing low concentrations of hydrogen sulfide, being effective in promoting the embrittlement of the UNS-G41300 steel. For this tempered martensitic steel, under the test conditions, the role of a dynamic process of plastic straining on its hydrogen embrittlement was demonstrated.For the UNS-S31803 steel, a duplex (austenitic-ferritic) stainless steel, the study of the hydrogen embrittlement with the solutions used required cathodic polarization and showed that the embrittlement preferably occurs in the ferritic phase.     

缺省参数对TCP起始阶段性能的影响

对TCP在初始化阶段设置的参数作了讨论，并结合先前的TCP机制在这方面的不足对NewReno TCP进行了修改，提出了一种新的算法NewReno—1，不但提高了TCP的传输效率，而且在很大程度上降低了报文的丢失概率。     

慢波结构的纵向谐振特性研究

利用传输线理论分析了单模慢波结构纵向谐振的形成，说明了由于慢波结构与其输入、输出端阻抗不匹配导致纵向谐振的出现；根据有限元方法，通过求解S参数矩阵，研究了过模慢波结构TM0模的纵向谐振特性，获得了其形成时纵向波数与频率的满足条件及场分布特点，给出了纵向谐振发生时场的典型分布及实验上判断其发生的方法，并探讨了它对微波器件中束波相互作用的影响。     

茶树施用控释氮肥的产量和品质效应

采用盆栽和大田试验,研究了控释氮肥对茶树生长发育、茶叶产量和品质的影响。结果表明,控释氮肥能明显促进茶树的生长发育,茶树新梢数、百芽重、成熟叶片数量及叶绿素含量、树高和主杆直径等均有明显提高,从而使盆栽茶树根、茎和叶各部位的生物产量比施普通尿素分别提高了58.3%、36.9%和17.2%。10个大田试验的茶叶产量增加了4.2%￣24.1%,平均9.6%。茶叶品质成分氨基酸、咖啡碱和水浸出物含量有不同程度提高,其中氨基酸增幅明显,但对茶多酚含量的影响不大,茶叶酚氨比明显降低。可见,控释氮肥具有明显的增产提质效果。