稀土对Zn＋5%Al合金与钢板湿润性的影响

用Meniscograph等方法测量了钢板与Zn+5％Al合金的湿润性。结果表明,少量稀土可以降低钢板与Zn+5％Al合金的湿润角,增加熔液在钢板上的上升高度,从而改善了钢板与Zn+5％Al合金的湿润性。稀土加入量在0.1％～0.2％范围内可以降低Zn+5％Al合金熔液的表面张力。对稀土的作用机理进行了讨论。     

装备可靠性增长率确定方法研究

从介绍装备可靠性门限值要求入手 ,提出了装备可靠性增长率的确定问题 .充分考虑各种因素对装备外场可靠性增长率影响 ,利用层次分析原理确定了这些因素对装备可靠性增长的影响权重 ,将此权重用于模糊综合评判 ,得到了 Duane模型中增长率的确定方法 .     

boldmath Characterization of the BaBiO3-doped BaTiO3 positive temperature coefficient of a resistivity ceramic using impedance spectroscopy with Tc=155℃

BaBiO₃-doped BaTiO₃ (BB-BT) ceramic, as a candidate for lead-free positive temperature coefficient of resistivity (PTCR) materials with a higher Curie temperature, has been synthesized in air by a conventional sintering technique. The temperature dependence of resistivity shows that the phase transition of the PTC thermistor ceramic occurs at the Curie temperature, T_c=155 ℃, which is higher than that of BaTiO₃ ( ≤ 130 ℃). Analysis of ac impedance data using complex impedance spectroscopy gives the alternate current (AC) resistance of the PTCR ceramic. By additional use of the complex electric modulus formalism to analyse the same data, the inhomogeneous nature of the ceramic may be unveiled. The impedance spectra reveal that the grain resistance of the BB-BT sample is slightly influenced by the increase of temperature, indicating that the increase in overall resistivity is entirely due to a grain-boundary effect. Based on the dependence of the extent to which the peaks of the imaginary part of electric modulus and impedance are matched on frequency, the conduction mechanism is also discussed for a BB-BT ceramic system.     

Characterization of the BaBiO3-doped BaTiO3 positive temperature coefficient of a resistivity ceramic using impedance spectroscopy with Tc=155℃

BaBiO 3-doped BaTiO3(BB-BT) ceramic,as a candidate for lead-free positive temperature coefficient of resistivity (PTCR) materials with a higher Curie temperature,has been synthesized in air by a conventional sintering technique. The temperature dependence of resistivity shows that the phase transition of the PTC thermistor ceramic occurs at the Curie temperature,Tc=155℃,which is higher than that of BaTiO3(≤130℃). Analysis of ac impedance data using complex impedance spectroscopy gives the alternate current (AC) resistance of the PTCR ceramic. By additional use of the complex electric modulus formalism to analyse the same data,the inhomogeneous nature of the ceramic may be unveiled. The impedance spectra reveal that the grain resistance of the BB-BT sample is slightly influenced by the increase of temperature,indicating that the increase in overall resistivity is entirely due to a grain-boundary effect. Based on the dependence of the extent to which the peaks of the imaginary part of electric modulus and impedance are matched on frequency,the conduction mechanism is also discussed for a BB-BT ceramic system.     

动力学蒙特卡洛(KMC)模拟薄膜生长

本文以扩散理论为基础,利用KMC模拟方法,考察了温度对薄膜生长速率和表面形貌的影响以及生长表面的粗糙化相变过程.模拟表明,温度升高有利于提高薄膜生长速率,薄膜生长以“成核-岛数增长-岛的长大融合”的方式进行.模拟发现薄膜生长初期存在粗糙化相变过程,当温度低于相变温度时,薄膜分层生长,生长速率较慢;当温度高于相变温度时,薄膜表面粗糙度骤然升高,生长速率加快.     

微波辅助萃取气相色谱-质谱联用测定蔬菜中的扑草净

研究了微波辅助萃取气相色谱．质谱联用测定植物样品中扑草净的方法，比较了几种不同溶剂的微波萃取效率，从而选取二氯甲烷为萃取溶剂，并采用三因素三水平的正交设计试验对溶剂体积、微波辐射时间、微波功率进行了优化。在优化的实验条件下分析了合成菠菜样品，对0．2μg/g和0．02μg/g的合成菠菜样品，回收率分别为99．5％和92．5％，相对标准偏差分别为5．0％和ll％，方法的线性范围为1．0—400ng／g，检出限为0．22ng／g。方法适合于分析植物样品中的扑草净。     

GC法同时测定酚氨咖敏片中4种组分

建立了同时测定酚氨咖敏片中对乙酰氨基酚、氨基比林、咖啡因和马来酸氯苯那敏4组分含量的毛细管气相色谱法。采用SE-30大口径毛细管色谱柱(30 m×0.53 mm,1.0μm),柱温190℃,汽化室温度220℃,检测器为FID,检测温度250℃,载气为高纯N2,分流比为1∶6,内标为盐酸麻黄碱,以无水乙醇为溶剂,样品无需衍生化处理,直接进样测定。样品中各组分完全分离,辅料无干扰,对乙酰氨基酚、氨基比林、咖啡因和马来酸氯苯那敏分别在20~2000μg/mL、15~1500μg/mL、10~500μg/mL和20~100μg/mL范围内线性关系良好(r0.999),各组分的平均回收率在99.6%~101.2%范围内,RSD2%。     

SiO2气凝胶分子动力学模拟研究进展

二氧化硅(SiO₂)气凝胶是一种拥有三维骨架网络结构的纳米多孔材料,具有高孔隙率、低密度和低热导率等许多独特的性能。但是由于二氧化硅气凝胶本身的脆性及高温稳定性差等原因,限制了其大规模应用。二氧化硅气凝胶的热力学性能与其内部的三维骨架和孔结构紧密相关,掌握二氧化硅气凝胶内部微结构演化规律与宏观性能的关联,是改善其热力学性能的前提。分子动力学模拟可以从原子层面分析和探索气凝胶的结构并预测其热力学性能。本文对分子动力学模拟下二氧化硅气凝胶势函数、多孔结构建模、结构表征、力学性能和热性能方面进行了详细总结,有助于从原子层面解释二氧化硅气凝胶结构与性能之间的关系,为从成分和结构方面设计气凝胶提供一种理论指导方法。     

微波皂化萃取气相色谱法测定生物样品中的多氯联苯

１引言 多氯联苯（ＰＣＢｓ）的性质稳定、毒性大,贻贝等海洋生物能摄取和富集海水中的ＰＣＢｓ,因此研究其中ＰＣＢｓ的测定具有重要意义。生物样品中 ＰＣＢｓ的测定一般要进行预分离处理,索氏萃取分离 ＰＣＢｓ耗时至少８ｈ,加碱皂化生物组织再以液－液萃取提取ＰＣＢｓ需要在沸水浴中回流１～２ｈ,微波直接革取能有效地分离环境样品中的ＰＣＢｓ。本文利用微波皂化萃取（ＭＡＳＥ）气相色谱法（ＧＣ）测定生物样品中的多氯联苯,实验以未受ＰＣＢｓ污染的淡水鱼为空白,用正交试验系统优化了微波功率、微波加热时间、皂化及萃取溶…     

生物材料玻璃化保存方法研究进展

生物材料的玻璃化保存技术一直是低温生物学领域的研究热点,提高冷却速率是实现玻璃化保存的一条途径。介绍了常用玻璃化保存方法的操作方法,分析比较了其冷却速率和保存效果,并提出了一种新颖的玻璃化保存法。