Sn及Sn合金的微观断裂行为

微电子系统中互连尺寸的微细化使构成焊点的钎料合金的力学性能成为影响电子封装与组装产品可靠性的关键因素。因此,在微米及纳米尺度深刻掌握Sn基钎料合金的断裂行为对于更好地预测焊点可靠性具有重要意义。本文针对100Sn、63Sn37Pb、96.5Sn3.5Ag三种Sn及Sn合金,在进行力学性能测试和显微组织分析的基础上,考察了Sn及Sn合金在微米尺度上的动态断裂机制,以及纳米尺度上裂纹尖端的真实物理过程,阐述了Sn基体、含铅Sn合金和无铅Sn合金三者互有关联又各有不同的微观断裂行为特征。     

Al-Ni非晶合金的原子堆垛结构及密度的第一性原理分子动力学模拟

在Al基非晶合金中，Al-Ni系的非晶形成能力（GFA）相比其他系列较佳，但是目前对Al—Ni二元合金系的原子排列、玻璃转变和堆垛密度与成分之间的内在联系，至今还未形成系统的认识．本文利用第一性原理分子动力学（AIMD）模拟方法对AlxNi100-x（x=80，83，85，86，87，90）二元非晶合金的原子堆垛结构和密度进行了研究．双体分布函数和Voronoi多面体分析表明，在该非晶合金系中存在明显的拓扑和化学短程有序，拓扑短程序主要是由以Al原子为中心的类似二十面体结构和以Ni原子为中心的三棱体覆盖三个半八面体（TTP）结构组成．在该合金系非晶中A-与Ni原子间存在强烈的化学交互作用，Al—Ni原子对键长小于原子半径和，化学有序随着Ni含量的增加呈现增加的趋势．AIMD计算结果表明，当x=85时，合金的堆垛密度出现了峰值，偏离了直线规律．综合结构特征和密度特征，从理论上推断，当Al含量为84％～86％时，合金的非晶形成能力较好，可以推广至多元合金体系．     

电脉冲作用下Al-22％Si合金的价电子理论研究

基于固体与分子经验电子理论（EET）,计算了Al—22％Si合金熔体相价电子结构参数,研究了铝硅合金熔体基元键络对温度（能量）变化的敏感性及其对组织形态的影响．结果表明,低过热铝硅合金熔体中n4值较大的Si-Si团簇为过共晶铝硅合金初生硅形核提供了核心,对其周围的Al—Si团簇产生强烈的“类拖曳”效应;熔体温度的变化较明显地影响了该核心键络的稳定性,从而影响了组织形态;脉冲电场作用于合金熔体后,不可恢复地改变了Si-Si团簇键络稳定性,从而对合金凝固组织形态起到变质作用,施加电脉冲的能量越高,Si—Si团簇越不稳定,电脉冲孕育效果越显著．     

熔体过热对Sn—Bi40合金熔体结构转变及凝固组织的影响

以Sn－40wt％Bi合金为研究对象,探索了其在不同温度下恒温过程熔体电阻率随时间的变化规律,以及不同熔体状态与凝固行为及组织的关系．结果显示：在一定的临界温度以上,熔体保温相应时间后电阻率发生异常变化,提示熔体发生了结构变化;且随过热温度的提高,熔体结构转变所需“孕育期”愈短,转变速度愈快．凝固实验表明,一定过热度及相应保温时间所引起的熔体结构状态不同,导致凝固过冷度增大、晶粒明显细化且形态也发生改变．进一步的探索还表明,对应特定保温时间,凝固过冷度在一定的熔体过热温度下出现最大值．对上述现象的作用机理进行了简要的分析讨论．     

AgCu合金的内氧化的微观结构与机制

研究了Ｃｕ含量（原子分数）分别为０．８％，３．３％，６．３％和９．５％的ＡｇＣｕ合金在７５０℃以及在８５０℃的内氧化。发现ＣｕＯ颗粒能在含有０．８％，３．３％和６．３％Ｃｕ的合金表面较均匀形核析出，而Ａｇ－９．５％Ｃｕ合金表面有ＣｕＯ颗粒簇集中析出的现象；并且，内氧化的形核与长大情况随Ｃｕ含量或氧化温度的变化而明显不同，氧化温度及Ｃｕ含量低时，ＣｕＯ的析出与长大规律符合Ｂｏｈｍ－Ｋａｈｌｗｅｉｔ经     

CeO2对锂离子电池正极材料LiMn1/3CO1/3Ni/3O2的包覆改性

采用溶胶凝胶法对LiMn1/3CO1/3Ni/3O2表面包覆了1．0wt％的CeO2．采用X射线衍射（XRD）,扫描电镜（SEM）,循环伏安（CV）和恒流充放电对包覆和未包覆的LiMn1/3CO1/3Ni/3O2进行了结构表征与性能测试分析．研究显示,CeO2并没有改变电极材料的晶体结构,仅在电极材料表面形成均匀的包覆层．包覆1．0wt％CeO2后的材料的放电容量和循环性能均明显优于未包覆的材料．在20mA·g^-1的电流密度下,包覆1．0wt％CeO2后的材料的放电容量为182．5mAh·g^-1而未包覆的材料仅为165．8mAh·g-1．包覆1．0wt％CeO2后的材料在3．0C下循环12周后的容量保持率达93．2％,而未包覆的材料的容量保持率仅为86．6％．CV测试表明,CeO2包覆层可以有效的防止正极材料与电解液的直接接触,抑制了材料结构的转变或抑制了与电解液的副反应,从而提高了材料的电化学性能．     

darbufelone对胃癌SGC-7901细胞裸鼠移植瘤血管生成的影响

目的观察环氧合酶-2／5-脂氧合酶双重抑制剂darbufelone对人胃癌皮下移植瘤血管生成的影响,并初步探讨其机制。方法建立裸鼠实体瘤模型,随机分为darbufelone组和对照组,darbufelone及生理盐水分别连续灌服4周。测量肿瘤质量、体积,计算抑瘤率;免疫组化检测CD34并计算微血管密度;RT—PCR法及Western blot法分析移植瘤组织中MMP-9、VEGF的表达。结果darbufelone可明显抑制裸鼠移植瘤的生长,质量抑瘤率为58．42％,体积抑瘤率为67．13％。darbufelone组的微血管密度（MVD）（15．36±0．30）明显低于对照组（29．47±0．63）（P〈0．05）;darbufelone组肿瘤组织中VEGF及MMP-9在基因水平及蛋白水平的表达（P〈0．05）。结论darbufelone能有效抑制裸鼠移植瘤的生长,减少移植瘤组织中VEGF及MMP-9的表达,抑制肿瘤的微血管生成,具有抗血管生成的作用。     

共晶Co79.5Sn20.5合金的液态结构及其液固相关性

利用高温液态X射线衍射仪研究了共晶Co79.5Sn20.5合金熔体的液态结构. 研究表明, 对Co79.5Sn20.5合金熔体而言, 从1350℃至1150℃的温度范围内, 组成该熔体的原子团簇结构稳定, 熔体有序度随着温度降低有所提高. 同时利用“纳米晶粒模型”研究了该合金的液固相关性, 指出该合金熔体是由b Co3Sn2原子团簇和b Co原子团簇2种短程有序结构组成, 其液态结构和固态结构具有很好的一致性.     

钛合金高温塑性变形时的内变量微观组织模型

研究分析合金高温塑性变形时微观组织演变机理的基础上,以位错密度变化率为内变量建立了合金高温塑性变形时的晶粒尺寸模型和位错密度模型．在Ti60合金的应用中表明,样本数据的平均相对误差为9．47％,非样本数据的平均相对误差为13．01％．     

仿射等价Boole函数的分析

利用Boole函数的一些基本变换和相应的不变量，。给出了两个结果：1．Boole函数仿射等价的判定和等价关系求取算法，该算法对Boole函数的科学研究和工程实践都具有重要意义．例如，该算法给出了所有8元3次齐次bent函数的等价关系；2．有效划分了部分参数的Reed—Muller码，如R（4，6）／R（1，6），R（3，7）／R（1，7）．     

Protective effect of tannic acid in mice receiving dietary lead

Summary Mice fed a diet containing both tannic acid and lead acetate showed increased weight gain and greater fecundity when compared with those on a diet containing lead acetate alone. The most significant improvement was provided by adding 2% tannic acid (wt/wt) to ground food containing 3% lead acetate. The affinity of tannic acid for heavy metals is suggested as a reason for this protective effect.     

Subcellular distribution and binding of heavy metals in the untreated liver of the squid; comparison with data from the livers of cadmium and silver-exposed rats

In natural squid liver, about 30% of the total Cd present was found in the cytosolic fraction. A large portion of this Cd was bound to high molecular weight species (mol. wt greater than 70,000). In contrast to Cd, about 60% of the total Ag occurred in the cytosolic fraction; Ag was bound mainly to low molecular weight species (mol. wt less than 20,000).     

Structure of victorin C,the major host-selective toxin fromCochliobolus victoriae

Summary The predominant host-selective toxin fromCochliobolus victoriae, victorin C, is a peptide with an apparent mol. wt of 796, representing a cyclic array of the subunits1–6. The structure of the toxin has now been established as in16 through analysis of the degradation products generated by enzymic and non-enzymic partial hydrolysis. The presence of a hydrated aldehydo group requires for victorin C the composition C₃₁H₄₅O₁₃N₆Cl₃ with an amended mol. wt of 814, for which independent experimental support has been secured.     

固体氧化物燃料电池金属连接体材料

本文简述了固体氧化物燃料电池(SOFC)连接体材料的发展过程,重点介绍了金属连接体材料的研发现状。目前研究和使用的合金有三种:Cr基合金、Ni基合金和铁素体不锈钢。Cr基合金的耐热温度能达到SOFC的要求,并且其表面氧化后生成的Cr2O3有很高的电导率,但是Cr元素的挥发很容易引起阴极中毒而降低电池性能;Ni基合金有很高的抗氧化性,但其热膨胀系数(TEC)比电解质(如YSZ)大很多,热膨胀系数的不匹配很容易造成电池破裂;铁素体不锈钢能满足SOFC所要求的强度,并且有合适的热膨胀系数,但是也需要在其表面制备保护层来降低氧化速率和Cr挥发。本文以有代表性的合金作为例子对三种合金的性质作了总结,并给出了本实验室所开发的几种Fe-Cr高温合金(铁素体不锈钢)的性能。最后总结了合金连接体的发展方向。     

Distribution of cadmium,zinc and copper in the musselMytilus edulis. Existence of cadmium-binding proteins similar to metallothioneins

Summary The study of the distribution of Cd, Zn and Cu in homogenates of mussels has shown that Zn and Cu are principally associated with high mol. wt. proteins. The same distribution is observed for Cd in untreated mussels, but in Cd chronically intoxicated animals, the metal is principally bound to low mol. wt. proteins synthesized in response to the uptake of the cation and similar to metallothioneins of vertebrates.This research was carried out in participation in the Belgian National Research and Development Program on the Environment-Water-Sea Project-Office of the Prime Minister-Interministerial Commission for Science Policy and Programmation.I am grateful to Prof.A. Disteche and Dr.Ch. Gerday for theiradvice throughout this work. I thankR. Biondo andN. Gerardin for excellent technical assistance.     

Immunosuppressive effect of a mouse placenta fraction on H-2 incompatible split heart allografts

Summary A soluble placenta fraction from mice (A.CA) mated with H-2 histoincompatible males (A/Sn) significantly prolonged the survival of heterotopic A/Sn heart transplants in A.CA recipients. No prolongation of A/Sn heart graft survival was obtained with the corresponding A.CA placenta fraction after A.CA × A.CA mating.The work was supported by the Danish Medical Research Council (Project No. 512-3088).     

Trichinella spiralis: Acceleration and inhibition of cyst calcification in rats

Summary Daily administration of vitamin D₃ (75,000 IU/kg b.wt) for 7 days acceleratedTrichinella spiralis cyst calcification in rats with a 14-week-old infection. When disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) was administered (50 mg/kg b.wt) from 2 days before until 2 days after vitamin D₃ treatment, cyst calcification was inhibited. Thus, the ability to inhibitT. spiralis calcification has been demonstrated for the first time.Supported in part by EKU faculty research grant No. 03-05.Much appreciation goes to Dr Gordon S. Hassings and the Proctor and Gamble Company, Miami Valley Laboratories, Cincinnati, Ohio USA for providing the EHDP used in this study.     

Effect of a sesquiterpene fromAristolochia indica Linn. on fertility in female mice

Summary A sesquiterpene isolated from the roots ofAristolochia indica (Linn.) was found to exert 100% interceptive activity and 91.7% anti-implantation activity in mice at a single oral dose of 100mg/kg b. wt. No toxic effect was found at the dose levels used.The authors wish to thank Dr S. C. Pakrashi and his associate Mr P. P. Ghosh Dastidar of Medicinal Chemistry Department for isolating the compound for this study. Thanks are also due to Director-General of Indian Council of Medical Research for granting a Junior Research Fellowship to C.S.     

Effect of aloe lectin on deoxyribonucleic acid synthesis in baby hamster kidney cells

Summary A homogeneous glycoprotein (mol.wt 40,000) containing 34% carbohydrate was isolated fromAloe arborescens var.natalensis. At a concentration of 5 g/ml, this glycoprotein was shown to stimulate deoxyribonucleic acid (DNA) synthesis in baby hamster kidney (BHK) cells and to have the properties of a lectin which reacts with sheep blood cells. The chemical and physical properties of the glycoprotein (aloe lectin) are also discussed.