薄壁铸造和退火工艺对LPCNi3.55Co0.75Mn0.4Al0.3贮氢合金电化学性能的影响

研究了不同铸锭厚度(1～10mm)对薄壁铸造的铸态和退火态LPCNi3．55Co0.75Mn0.4Al0.3贮氢合金电化学性能的影响。结果发现：铸态LPCNi3．55Co0.75Mn0.4Al0.3合金的0．2C放电容量随着合金锭厚度的增加有增大的趋势。10mm厚铸态合金的活化性能优于其它厚度的合金，且在1C的放电容量和循环稳定性比在其它厚度的高。主要原因应归结为该厚度合金具有更大的晶胞体积和更小的晶格应力。退火态3mm LPCNi3．55Co0.75Mn0.4Al0.3合金的综合电化学性能比铸态更优异，6mm合金的循环稳定性和3～6mm合金的活化性能得到改善。主要原因应归结为晶格应力的极大释放以及Mn等元素偏析的改善。     

主成份分析同时单点pM滴定法研究

本文将主成份分析应用于单点ＰＭ滴定法中，同时测定了多组分金属离子混合物各组分浓度。讨论了方法原理，建立了主成份常数矩阵，对２１个三元、四元混合样进行了测定，得到满意结果。     

含镧的Bi2Te3基化合物的溶剂热合成及微观结构

以BiCl3,LaCl3和Te粉为原料,用溶剂热合成法制备了含稀土元素的单相LaxBi4Te6(x≤1)热电材料纳米粉末.研究发现,三元化合物LaxBi4Te6具有与二元Bi2Te3化合物相同的晶体结构和相似的晶格常数。LaxBi4Te6中的La含量随合成温度升高而增加,但与反应时间没有显著关系。LaxBi4Te6合成粉末的颗粒尺寸在30nm左右,并且几乎与反应温度和反应时间没有关系。在120℃合成的粉末基本上为不规则多面体形状,在150℃及以上温度合成的粉末则趋向于薄片状．并存在一些直径在50～80nm之间的纳米管。     

环状配合物Me_2Si［η~5－C_5H_4Fe（CO）_2］_2SnR_2的合

通过ＳｎＣｌ_２对化合物Ｍｅ_２Ｓｉ［η~５－Ｃ_５Ｈ_４Ｆｅ（ＣＯ）］_２（μ－ＣＯ）_２（Ⅰ）中Ｆｅ－Ｆｅ键的插入反应以及Ⅰ被Ｎａ－Ｈｇ齐还原所生成的相应双铁负离子｛Ｍｅ_２Ｓｉ［η~５－Ｃ_５Ｈ_４Ｆｅ（ＣＯ）_２］_２｝~（２－）与ＳｎＲ_２Ｃｌ_２（Ｒ＝Ｍｅ，Ｐｈ）的亲核反应，合成了环状化合物Ｍｅ_２Ｓｉ［η~５－Ｃ_５Ｈ_４Ｆｅ（ＣＯ）_２］_２ＳｎＲ_２［Ｒ＝Ｃｌ（１），Ｍｅ（２），Ｐｈ（３）］。以元素分析、ＩＲ和~１ＨＮＭＲ谱表征了它们的结构，并用Ｘ射线衍射测定了配合物３的晶体结构。３为单斜晶系，空间群Ｐ２_１／ｎ，ａ＝１．０３８４（３）ｎｍ，ｂ＝１．６３８４（１）ｎｍ，ｃ＝１．５７６２（５）ｎｍ，β＝９７．９３（２）°，Ｖ＝２．６５６（２）ｎｍ~３，Ｚ＝４，Ｄｘ＝１．７１ｇ／ｍＬ。     

The structures,binding energies and vibrational frequencies of Ca3 and Ca4 — An application of the CCSD(T) method

Summary The Ca₃ and Ca₄ metallic clusters have been investigated using state-of-the-artab initio quantum mechanical methods. Large atomic natural orbital basis sets have been used in conjunction with the singles and doubles coupled-cluster (CCSD) method, a coupled-cluster method that includes a perturbational estimate of connected triple excitations, denoted CCSD(T), and the multireference configuration interaction (MRCI) method. The equilibrium geometries, binding energies and harmonic vibrational frequencies have been determined with each of the methods so that the accuracy of the coupled-cluster methods may be assessed. Since the CCSD(T) method reproduces the MRCI results very well, cubic and quartic force fields of Ca₃ and Ca₄ have been determined using this approach and used to evaluate the fundamental vibrational frequencies. The infrared intensities of both thee mode of Ca₃ and thet ₂ mode of Ca₄ are found to be small. The results obtained in this study are compared and contrasted with those from our earlier studies on small Be and Mg clusters.Dedicated to Prof. Klaus Ruedenberg on the occasion of his 70th birthday     

丙烯腈中铁铜等15种杂质元素的电感耦合等离子体发射光谱法测定

采用电感耦合等离子体发射光谱法同时测定了丙烯腈中的Al、B、Ca、Cd、Cr、Cu、Fe、K、Li、Mg、Mn、Na、Ti、Sr、Zn15种杂质元素；比较了HNO3和HN03-HClO4 2种消解样品的方法；结果表明，后者能使样品消解彻底，无丙烯腈残留；考察了酸度和丙烯腈残留量对测定结果的影响；酸度对测定结果无影响，丙烯腈残留对元素分析结果(除№外)有较强的抑制作用，对K测定结果影响复杂；元素的检出限为0．001～0．2mg／L，标准加入回收率为92％～112％；方法安全、简便、快速、准确。     

Amorphous Coatings and Surfaces on Structural Materials

Metallic glasses show a unique combination of high strength, excellent corrosion, and wear resistances because of their amorphous structure having a short-range order. In spite of excellent properties, the application of metallic glasses is restricted because of their inherent limitations in the bulk form, including limited tensile ductility. Using metallic glasses as the coatings for structural applications is an attractive way of taking advantage of their superior properties. Additionally, metallic glass-based composites having crystalline phases embedded in a amorphous matrix have also shown improved properties. Thus, metallic glasses can be synthesized as the coatings or subjected to surface modification to provide functionally superior surfaces. This article is a review of metallic glass-based coatings and surface modification of metallic glasses to achieve functionally superior surfaces for structural applications. Essential theoretical concepts were discussed which influence the processing. Common ways of processing along with the influence of various processing parameters were explored. Some non-conventional techniques which emerged as a result of continued efforts were also taken into account. Corrosion and wear properties of these materials along with the underlying mechanisms were discussed in detail. Focus was given to the recent product level applications explored in the open literature. Current challenges in the field were reviewed and guidelines for the future developments were provided.     

Bromine,arsenic, cadmium,and lead in several key food groups: an assessment of relative risk

ABSTRACT

This study endeavoured to provide an overview of the bromine, Br, arsenic (As, a metalloid) and metal (cadmium, Cd, and lead, Pb) relative risk associated with the consumption of relevant food groups (lean fish, fatty fish, bivalves, cephalopods, fresh fruit, dried fruit, and green vegetables) in Portugal. Though As, Cd, and Pb have been frequently studied, a comprehensive overview applying the same state-of-the-art methodology to a wide array of foods is missing. Besides, there is a large deficit of content information and risk assessment studies on Br. Thus, it is important to apply a mathematically realistic and innovative methodology (extreme value theory) to recent and accurate databases for the aforementioned food groups and elements.

Best fits to Br, As (total), Cd, and Pb concentrations were attained through different functions, ranging from the normal distribution to the Weibull distribution. A semi-probabilistic risk assessment approach on the basis of four alternative scenarios (one monthly meal; one weekly meal; three weekly meals; one daily meal) showed low relative risk regarding Br and Pb in the selected food groups, including bivalves, which contained the highest Br and Pb contents. With respect to total As, high relative risk values were calculated for seafood, but it should be emphasized that this As is overwhelmingly organic, thus presenting low risk. For Cd, substantial relative risk associated with bivalves’ and cephalopods’ consumption, particularly with one or more weekly meal(s), was found. However, the current study enables us to compare between the relative risk of the studied food groups and scenarios, and other studies encompassing the whole diet and following long-term dietary patterns are needed for the assessment of absolute risk.