皇竹草KP-AQ浆CEpH漂白

文中对皇竹草KP-AQ浆的CEpH漂白条件、漂白浆特性及其打浆性能进行了研究,并与芦苇浆作了比较.实验结果表明,皇竹草浆CEpH漂白较佳条件为:总用氯量11%,C、H段用氯比为7:3;E段H2O2用量1.3%,漂白浆得率89.4%,白度84.9%ISO,返黄值2.5,粘度863mL/g,卡伯值1.7;打浆度为41～42°SR时,皇竹草漂白浆主要物理指标为:紧度0 58g/cm3,耐破指数2.92kPa·m2/g,耐折度16次,撕裂度指数8.16mN·m2/g,裂断长4070m;皇竹草漂白浆白度、得率、返黄值、卡伯值等综合性能优于芦苇浆,粘度低于芦苇浆;芦苇浆比皇竹草浆更易打浆;芦苇漂白浆强度指数稍高于皇竹草浆.     

声发射技术在大型观览车主轴检测中的应用

主轴是大型观览车结构中的重要部件,具有难以拆卸的特点,一旦发生故障,危险性极大。根据大型观览车主轴的结构特点,制定了相应的声发射检测方案,对在役观览车主轴中的异常声响进行了声发射在线检测,分析并给出了异常声响信号的声发射参数特征、定位特征和波形频谱特征,并对两个检验周期中声发射检测的结果进行了比较。结果表明,声发射检测技术可以用于大型观览车主轴运行状态的监测与评价。     

防止我国由无缝钢管大国变成无缝钢管“穷”国的思考

介绍了当前我国无缝钢管行业的基本情况,指出我国无缝钢管行业由大国走向强国的同时,正在变成无缝钢管“穷”国.分析了我国无缝钢管行业经济效益下滑的主要原因,提出了通过控制投资规模淘汰落后产能,加快企业重组提高产业集中度,依靠技术进步、加强企业管理,降低钢管制造成本以及调整品种结构,提高产品附加值和探索“走出去”道路,避免反...     

Mild alkaline pre-treatments loosen fibre structure enhancing methane production from biomass crops and residues

Three ligno-cellulosic substrates representing varying levels of biodegradability (giant reed, GR; fibre sorghum, FS; barley straw, BS) were combined with mild alkaline pre-treatments (NaOH 0.05, 0.10 and 0.15 N at 25 °C for 24 h) plus untreated controls, to study pre-treatment effects on physical-chemical structure, anaerobic digestibility and methane output of the three substrates. In a batch anaerobic digestion (AD) assay (58 days; 35 °C; 4 g VS l⁻¹), the most recalcitrant substrate (GR) staged the highest increase in cumulative methane yield: +30% with NaOH 0.15 N over 190 ml CH₄ g⁻¹ VS in untreated GR. Conversely, the least recalcitrant substrate (FS) exhibited the lowest gain (+10% over 248 ml CH₄ g⁻¹ VS), while an intermediate behaviour was shown by BS (+15% over 232 ml CH₄ g⁻¹ VS). Pre-treatments speeded AD kinetics and reduced technical digestion time (i.e., the time needed to achieve 80% methane potential), which are the premises for increased production capacity of full scale AD plants. Fibre components (cellulose, hemicellulose and acid insoluble lignin determined after acid hydrolysis) and substrate structure (Fourier transform infra-red spectroscopy and scanning electron microscopy) outlined reductions of the three fibre components after pre-treatments, supporting claims of loosened binding of lignin with cellulose and hemicellulose. Hence, mild alkaline pre-treatments were shown to improve the biodegradability of ligno-cellulosic substrates to an extent proportional to their recalcitrance. In turn, this contributes to mitigate the food vs. fuel controversy raised by the use of whole plant cereals (namely, maize) as feedstocks for biogas production.     

Characteristics of Gelatin from Giant Grouper (Epinephelus Lanceolatus) Skin

Gelatin extraction from the skin of giant grouper (Epinephelus lanceolatus) was conducted by acid process with a yield of 20.27 g/100 g wet skin sample. The characteristics of extracted gelatin from giant grouper was investigated in this study, and further compared to that from commercial tilapia. Results showed that when compared to commercial tilapia, giant grouper had lower levels of bloom strength and foam formation ability, but greater values of viscosity, foam stability, and lightness (L*) on gelatin skin. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis revealed three high-bands intensities of major protein components of giant grouper skin gelatin, representing α1-chain, α2-chain, and β-components, and was similar to that of standard calf skin collagen type I. Compared to giant grouper, commercial tilapia contained extra proteins with molecular weight less than 70 kDa on the sodium dodecyl sulphate-polyacrylamide gel electrophoresis of both skin gelatins.     

世界大气田分布特征

截至2002年底,全球共发现355个大气田,集中分布于西西伯利亚、扎格罗斯、波斯湾、卡拉库姆、美国墨西哥湾、北海和卡那封等盆地,其储集层以二叠系-第四系为主。大气田的形成和展布主要受控于区域大地构造背景、有效烃源岩的分布、有利的储盖组合和圈闭类型等条件。认为中国含油气盆地复杂的地质条件决定了中国天然气的勘探将是一个长期的过程,预计天然气储量增长将持续相当长的一段时间,建议在今后重视盖层的研究,强化油型气和原油裂解气的勘探。     

On the origin of decay of spin current with temperature in organic spintronic devices

This article addresses the most challenging question facing the organic spintronics community today – what causes the universal loss of Giant Magnetoresistance (GMR) signal in organic spin valve devices made with different spin-polarized electrodes and organic semiconductor spacers? Careful analysis of our own and other experimental results available in literature indicate that transition of transport from polaron tunneling limit (suggested by the variable range hopping model) to thermally activated hopping limit (in the temperature range of 40–58 K) marks the most significant decrease of spin relaxation in organic semiconductors. With increasing occupancy of the available hopping sites by the thermally activated carriers, chances of spin flip inside the organic semiconductors increases significantly causing fast spin relaxation in the spin-valves.     

基于超磁致伸缩材料的振动能量复合采能装置现状分析

振动能量采能装置为大规模的MEMS设备网络摆脱传统物理连接和电源维护的限制提供了可能,但传统振动能量采能装置大多采用单一换能器的单一采能模块,存在采能效率提升难度大、环境适应性差等缺陷,因此需要推动传统采能模式向多种换能器协同采能的复合模式转变.从超磁致伸缩材料的优异特性出发,整理归纳了目前基于超磁致伸缩材料的振动能量...     

超磁致伸缩微位移执行器的矢量阻抗分析模型

超磁致伸缩微位移执行器应用于精密、超精密加工场合时,执行器系统易受外负载影响,且在动态工作状态下会产生磁滞和涡流等效应,引起工作性能发生改变。应用线性压磁方程,机电换能方程和阻抗分析理论建立超磁致伸缩执行器的矢量阻抗分析模型。模型中将执行器系统的矢量阻抗分为机械导纳和电气阻抗两部分讨论,在机械导纳中引入负载影响,将压磁系数定义为复常数,模拟磁滞效应;在电气阻抗中,通过在求解的超磁致伸缩材料内部磁场引入涡流影响项来模拟系统的非线性特性;两部分之和得出超磁致伸缩微位移执行器系统的矢量阻抗。试验结果显示模型计算的系统矢量阻抗值与测量值间幅值误差约7%,相位误差约7.7%,表明所建立的模型能够近似描述系统在精密加工场合时的阻抗特性,可为超磁致伸缩微位移执行器的设计、控制和性能优化提供指导。     

Cu对NiFe/Cu/NiFe层状薄膜的巨磁阻抗效应影响的研究

用直流磁控溅射方法制备了NiFe/Cu/NiFe层状薄膜 ,研究了Cu膜宽度对NiFe/Cu/NiFe层状薄膜的巨磁阻抗效应的影响 ,结果表明 ,层状薄膜的巨磁阻抗效应随Cu膜宽度发生振荡现象 ;并提出了一个等效电路模型直观地解释了层状薄膜增强巨磁阻抗效应的机理