木质类生物质热解过程的热重分析研究

采用非等温热重分析技术,考察了杜松、黄玫瑰、红皮云杉和暴马丁香等4种木质类生物质在30～800℃温度区间内的热解特性(N2气氛下)以及升温速率(10、20、40和60℃·min-1)对热解过程的影响.实验结果表明,木质类生物质的非等温失重过程主要由失水、剧烈失重和缓慢失重三个阶段组成.主要失重温度范围为249～428 ℃,其中挥发分的初析温度(Ts)为249～308℃;微分热失重(DTG)的峰值温度(Tmax)在349～408℃之间;最大失重速率(Wmax)为458.8～2700 ug·min-1.木质类生物质热解活化能(E)为43.51～52.48 kJ·mol-1,指前因子(A)为1.3 × 102～3.6×105 min-1.随升温速率(β)的增加,E增大,Ts和Tmax升高,Wmax提高.     

Digital Speckle Technique Applied to Flow Visualization

ＩｎｔｒｏｄｕｃｔｉｏｎＨｏｌｏｇｒａｐｈｉｃｉｎｔｅｒｆｅｒｏｍｅｔｒｙｈａｓｂｅｅｎｕｓｅｄｆｏｒｏｐｔｉｃａｌｖｉｓｕａｌｉｚａｔｉｏｎａｎｄｄｉａｇｎｏｓｔｉｃｓｉｎｆｌｕｉｄｍｅｃｈａｎｉｃｓａｎｄｔｈｅｒｍａｌｆｌｏｗｆｏｒｍａｎｙｙｅａｒｓ.Ｈｏｗｅｖｅｒ,ｔｈｅｒｅａｒｅｓｏｍｅｄｉｆｆｉｃｕｌｔｉｅｓａｓｓｏｃｉａｔｅｄｗｉｔｈｔｈｅｕｓｅｏｆｃｏｎｖｅｎｔｉｏｎａｌｈｏｌｏｇｒａｐｈｙｉｎｅｎｇｉｎｅｅｒｉｎｇａｐｐｌｉｃａｔｉｏｎｓ[1].Ｔｈｅｍｏｓｔｏｂｖｉｏｕｓｐｒｏｂｌｅ…     

强非线性Duffing方程的摄动解

用参数展开摄动法和改进的 L- P方法求解强非线性 Duffing方程。与寻常的摄动法相比 ,具有较高的精度。     

几何非线性圆板的热弹耦合振动

运用直角坐标下的几何非线性热弹耦合振动基本方程 ,对周边固支、简支圆板运用伽辽金法求解 ,得出振幅随时间变化的数值解。比较了不同热弹耦合参数对应的振动情况 ,得出了热弹耦合效应对振动周期和频率的影响     

Specific degradation of keratin in Xenopus laevis egg extracts undergoing apoptosis

Cytochrome c activates apoptosis specific protease XCPP32 when being added to Xenopus laevis egg extracts, and induces apoptosis in this cell-free system. During apoptosis, cyto-skeleton proteins in egg extracts are degraded. Western blot assay indicates that 42-ku acidic keratin in egg extracts has been degraded by XCPP32. The degradation of 42-ku keratin may be crucial in apoptosis.     

Menadione-induced apoptosis and its mechanism in plants

Menadione can induce apoptosis in tobacco protoplasts. Typical characteristics are detected including the condensation of chromatin, the formation of apoptotic bodies and the degradation of genomic DNA into “DNA ladder”. Specific DNase is activated during this process. Ca²⁺ and Mg²⁺ are necessary for its activation, while Zn²⁺ and EDTA (Ethylenediaminetetraacetic acid) can inhibit its activation. The fragmentation of DNA and lamin can be inhibited by DEVD (Ac-Asp -Glu- Val- Asp-aldehyde). The fragmentation of lamin can also be inhibited by PMSF (Phenylmethylsulfonyl fluoride) and CH (Cyclohexinide). These results show that activation of specific DNase and proteases is involved in menadion-induced apoptosis in plants.     

Low melting point nanocrystalline Sn–Ag solder synthesized by a refined chemical reduction method

The commercial market of Sn-Pb solder is gradually decreasing due to its toxicity, calling for Pb-free substitute materials. Sn-Ag alloy is a potential candidate in terms of good mechanical property. The major problematic issue of using Sn-Ag is their high melting temperature, consequently this study is dedicated to lowering the melt- ing temperature of Sn3.5Ag （wt%） alloy by developing nanomaterials using a chemical reduction approach. The resultant nanocrystalline Sn3.5Ag is characterized by field emission scanning electron microscope. The size dependence of the melting temperature is discussed based on differential scanning calorimetry results. We have reduced the melting temperature to 209.8 ℃ in the nanocrystalline Sn3.5Ag of （32.4± 8.0） nm, compared to ～221 ℃ of the bulk alloy. The results are consistent with the prediction made by a relevant theoretical model, and it is possible to further lower the melting temperature using the chemical reduction approach developed by this study.     

工业控制设备安全测试技术

工业控制设备(ICDs)广泛应用于石油化工、电力水利、轨道交通等国家关键基础设施领域,其正常运行直接关系到工业生产安全、经济安全甚至是国家安全。该文总结了现有工业控制设备普遍存在的共性安全问题,分析了其存在的根源。在此基础上从信息空间和物理空间这2方面分析了网络攻击带来的危害影响,最后总结了工业控制设备安全测试的标准规范、测评认证与面临的问题和挑战。     

Effect of power ultrasound on microstructural characteristics and mechanical properties of Al81.3Sn12.3Cu6.4 monotectic alloy

The liquid phase separation process and solidification process of ternary Al_(81.3)Sn_(12.3)Cu_(6.4) monotectic alloy was accomplished with a 20 kHz ultrasonic field in the power range up to 500 W.As ultrasound power rised,the coarse primary(Al) dendrites turned into fine equiaxed grains,whose size decreased by one order of magnitude as that during static solidification.Meanwhile,rather than pronounced segregation of large secondary(Sn) blocks in the alloy sample solidified under static condition,tiny secondary(Sn) droplets dispersed homogenously within the(Al)matrix in the presence of ultrasound.Under the highest ultrasound power of 500 W,the spherical ternary(Al + Sn + θ(Al_2Cu)) monotectic cells formed.The refinement of primary(Al) dendrites and uniform distribution of secondary(Sn) droplets induced by power ultrasound result in the improvement of microhardness,wear resistance,compressive and yield strength of ternary Al_(81.3)Sn_(12.3)Cu_(6.4) monotectic alloy.     

单细胞凝胶电泳技术在DNA损伤和细胞凋亡检测中的应用

用不同质量浓度的丝裂霉素C(MMC)、卡铂和5-氟尿嘧啶(5- Fu)处理Hela细胞24h,利用单细胞凝胶电泳( SCGE)技术分析这些药物对细胞DNA的损伤情况,结果发现:各药物处理组细胞都出现“彗星”,且随着各药物浓度的增大,彗星率升高,彗尾的荧光强度和长度也随之增大;各剂量组间存在良好的剂量-效应关系,差异显著...