稀土对AM50力学性能及高温蠕变的影响

对Y和富La稀土对镁合金AM50微观组织、铸态力学性能和蠕变性能的影响进行了研究.研究结果表明: AM50中加入Y和富La稀土能有效地细化晶粒,由于显微组织的改善,使得AM50合金的室温和高温力学性能均有一定的提高,并明显地改善了AM50镁合金的抗蠕变性能.填加稀土可以在AM50合金晶界处生成稳定的铝稀土化合物,可以明显提高镁合金AM50的常温及高温(150 ℃)力学性能.与加入富La稀土的AM50相比,加入Y提高力学性能及蠕变抗力的作用更明显.     

铒和钕对铸态ZK60镁合金显微组织和力学性能的影响

研究了铒和钕对铸态ZK60镁合金显微组织和力学性能的影响。结果表明：ZK60镁合金中添加Er或Nd能够细化晶粒，改变合金的显微组织。当ZK60镁合金中加入1．0％（质量分数）的Er或Nd具有最佳的细化效果，与原ZK60镁合金晶粒尺寸相比较，晶粒的平均直径由原来的33．0μm分别减少至23．6和25．2μm。添加Er或Nd的ZK60镁合金形成古有Er或Nd的稀土共晶相，其熔点为518℃。稀土共晶相对晶粒具有钉扎作用，提高合金在150℃时的抗拉强度。稀土共晶相的形态和分布对室温力学性能有显著影响。含有Er的共晶相析出数量较少，沿晶界不连续分布，提高合盒室温强度的同时塑性略有改善，而含有Nd的共晶相形态粗大，析出数量较多，沿晶界网状连续分布，合金固溶强化效果明显减弱，室温强度和塑性均降低。     

富钇混合稀土对AM60镁合金显微组织与力学性能的影响

在AM60镁合金的基础上添加不同质量分数的富Y混合稀土(分别为0.5%,1.0%,1.5%,2.0%),研究了富钇混合稀土对AM60镁合金显微组织与力学性能的影响。结果表明:富Y稀土的加入使AM60镁合金的显微组织明显细化,并能显著提高合金的抗拉强度、屈服强度及延伸率。加入混合稀土后,合金中形成块状的铝钇化合物Al2Y,Al6Mn6Y,β-Mg17Al12相数量减少。当稀土加入量为1%时,合金的各方面性能达到最好。     

富铈混合稀土对AZ81合金组织与性能的影响

研究了富铈混合稀土对挤压铸造AZ81合金的显微组织和力学性能的影响。结果表明:加入不同含量富铈混合稀土的合金中都出现了一种新相Al11(Ce,La)3相,Al11(Ce,La)3相数量增多而Mg17Al12相则减少,能细化合金的组织晶粒,其细化作用在添加了1.5%富铈混合稀土的镁合金中尤为明显,但是当富铈混合稀土加入量大于2.0%时,合金中Al11(Ce,La)3相开始长大以粗大长杆状存在;在富铈混合稀土含量为1.5%时,AZ81合金的室温和150℃的综合力学性能达到最佳效果,超过2.0%时合金的室温和150℃综合力学性能开始下降;合金试样的拉伸断口带有局部韧窝的解理断裂和韧性断裂的混合特征。     

Y对Ti-47Al合金显微组织及室温拉伸性能的影响

系统研究了Ti-47Al-xY（0，0．1，0．3，0．5，0．7，1．0％）合金的显微组织及室温拉伸性能。结果发现：Ti-47Al合金的晶粒尺寸和层片厚度均随着Y含量的增加而降低；当Y含量高于0．1％时，晶内弥散分布YAl2化合物的同时，YAl2开始在晶界处偏析，且随着Y含量的增加Y的晶界偏析越严重；力学拉伸表明，带有0．3％．0．5％Y的Ti-47Al合金有较好的拉伸性能。分析得知，富集Y的YAl2化合物的尺寸及分布对Ti-47Al合金的室温拉伸性能影响起着重要的作用。一方面，组织的细化和晶内细小的YAl2相有利于性能的改善，另一方面，在高Y含量的合金中（超过0．5％Y），晶界处大尺寸YAl2相的解理断裂使Ti-47Al合金提前失效，显著恶化Ti-47Al合金的拉伸性能。这两个方面的因素综合影响着Ti-47Al合金的性能。     

钇对AZ61镁合金组织和性能的影响

在CO2+SF6气体保护条件下感应熔炼制备了不同Y含量的AZ61-x Y(x=0,0.5,1,1.5,2)镁合金,利用光学金相显微镜(OM)、扫描电镜(SEM)、X射线衍射分析(XRD)、能谱分析(EDS)和拉伸及蠕变力学性能测试手段研究了Y添加对AZ61合金显微组织和力学性能的影响。结果表明:合金中添加适量的稀土元素Y后,AZ61合金的显微组织得到明显的细化,合金中除了存在α-Mg和Mg17Al12相,还出现了块状析出相Al2Y。适量的Y显著提高了合金在室温和高温时的强度和塑性,同时合金在150℃/70MPa条件下的抗蠕变性能也有显著的提升。     

热挤压AM50GdX镁合金的腐蚀力学性能研究

通过SEM、光学显微镜、失重测量、拉伸测试等方法研究了热挤压加工对不同Gd含量的AM50GdX镁合金的显微组织及腐蚀力学性能的影响。结果表明:热挤压后,合金内部出现了具有方向性的平行纤维变形组织;随着Gd含量的增加,AM50GdX镁合金组织中β-Mg_(17)A_l(12)相数量减少而Al_2Gd_3相数量和体积增加;1%Gd元素对合金耐蚀性提升作用最大;热挤压处理使合金的晶粒细化,从而使拉伸强度提升了接近50%;由于热挤压处理和1%Gd元素的存在大大改善了AM50镁合金的腐蚀剩余强度性能。     

铈对压铸镁合金AZ91组织和高温性能的影响

采用Olympus—PMG3型光学显微镜、D／Max 2500PC型X射线衍射仪(XRD)、带有EDAX—Falcon能谱仪(EDS)的JSM-5500LV型扫描电子显微镜(SEM)及AG-10TA型电子万能实验机，研究了Ce对压铸镁合金AZ91显微组织、常温性能及高温(150℃)性能的影响。结果表明：AZ91合金中加入Ce后，形成了新的Al4Ce相，使Mg17Al12(γ)相尺寸减小、数量减少、并由网状分布变得离散分布。Ce对AZ91合金常温性能的影响不大，但显著提高了高温性能。加入1．0％Ce的合金具有最好的显微组织和性能，但是Ce的加入量过高，反而使合金的性能降低。     

钇对Mg-9Al-1Si合金蠕变抗力和微观组织的影响

研究了Mg-9Al-1Si-xY合金的高温蠕变性能及其微观组织与力学性能的关系。该合金中的主要强化相Mg2Si呈粗大的汉字状，分布在晶界的周围，在受到应力时，这种汉字状相与基体的界面处易产生微裂纹，降低合金的抗拉强度、塑性等力学性能。在Mg-9Al-1Si合金中加入微量的Y以后，合金的组织得到明显的细化，Mg2Si强化相形貌由粗大的汉字状转变为细小、弥散分布的颗粒状。显微组织的改善，使得Mg-9Al-1Si合金的室温和高温力学性能均有一定的提高，并明显改善了Mg-9Al-1Si的抗蠕变性能。     

钇对IMI829钛合金及Ti—14Al—21Nb合金显微组织和性能的影响

采用光学显微镜、扫描电和力学性能测试设备，研究了在ＩＭＩ８２９和Ｔｉ－１４Ａｌ－２１Ｎｂ合金中添加Ｙ，对合金显微组织遥影响。结果表明，在ＩＭＩ８２９和Ｔｉ－１４Ａｌ－２１Ｎｂ合金中添加Ｙ，可以细化这两种合金的组织和晶粒，使ＩＭＩ８２９－０．２Ｙ合金获得良好的室温力学性能和５５０℃蠕变性能，ｗｇｋｑＴｉ－１４Ａｌ－２１Ｎｂ－０．１Ｙ合金的高温力学性能得到改善。     

Synthesis and structure of hydroxyisoxazolidines and derivatives of hydroxylamine and alkenals

The reactions of N-substituted hydroxylamines with alkenals serve as a method for the synthesis of the corresponding 2-substituted 3(5)-hydroxyisoxazolidines. The reaction pathway is determined by the nature of the substituent attached to the nitrogen atom. Ring-chain isomerism has been detected in these newly obtained compoundsTranslated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1270–1276, September, 1987.     

红霉素9,11-亚胺醚和乙腈分子加合物的合成和晶体结构

通过控制红霉素A (E)肟的贝克曼重排反应条件合成了一种关键中间体红霉素9,11-亚胺醚, 该化合物可与乙腈形成稳定的分子加合物(摩尔比为1∶1), 未见文献报道. 阐述了该化合物的合成、晶体结构、晶体学数据和结构参数. 该化合物为无色透明晶体, 属单斜晶系, 空间群P2₁. 对该加合物和已知化合物红霉素6,9-亚胺醚晶体结构的对照解析, 有助于对重排反应机理、异构化机理和两异构体还原差异性的分析, 对重排反应和还原反应起到积极的指导作用.     

Ti-V基储氢合金及其氢化物的物相结构与组分优化设计

Ti-V基储氢合金在室温、常压下即可表现出良好的储氢特性,且质量储氢容量明显高于传统AB₅型储氢合金,从而在氢气的精制和回收、运输和储存及热泵等方面有较早的应用。 此外,在混合气体分离、核反应堆中处理氢的同位素、镍氢电池及燃料电池负极材料等方面也得到了广泛的研究与关注。 基于目前Ti-V基储氢合金的研究现状,概述了该类合金的优势、限制性因素(包括成因)及改性手段。 此外,为了进一步理解Ti-V基合金储氢机理、构建合金组分与储氢特性之间的对应关系,本工作重点围绕Ti-V基储氢合金及其氢化物的结构、组分优化设计展开综述,并对其未来研究方向做出展望。     

Sizes of atoms and ions and covalency of bonding in molecules and crystals

A new system of atomic radii for the elements up to barium inclusive is constructed. Values of the radii are chosen so as the dependence between the dissociation energy of diatomic homonuclear molecules and a depth of atom overlapping is monotonous, and the scatter of data is minimal. The depth of overlapping is calculated as a difference between the sum of atomic radii and an experimental interatomic distance. Conclusions are made that: the radii of free atoms and ions are determined by the value of the electron density equal to 0.01 au; they considerably change in molecules and crystals only as a result of the charge transfer from cation to anion; covalent bonding is well described by the overlapping of free atoms (ions), confined by the surface of the given radius, and its energy depends upon the depth of overlapping of valence electron densities of atoms. A method of overlapping atoms is proposed for the approximate estimation of ionic sizes and charges in bound systems.     

四环素-铕与卵磷脂的相互作用及卵磷脂的测定

以四环素(TC)-Eu3 作为荧光探针,提出了新的荧光光度法测量卵磷脂(PC)。在pH 5.7的酸度条件下,扫描不同浓度的PC与TC-Eu3 的荧光光谱。通过优化实验条件,得到了测定PC的最佳条件。卵磷脂能使TC-Eu3 位于612 nm处的特征荧光显著增强且增强的荧光强度与PC的量成正比。测量的线性范围为4.0×10-7~1.4×10-5mol/L,检出限为3.9×10-8mol/L。该方法已用于实际样品的测定。     

Ni(Ⅱ)和Zn(Ⅱ)的乙基黄原酸盐与吡啶碱配合物的合成及性质的研究

乙基黄原酸基的结构为:(简写为Exan,它是一个双齿配体,能和许多金属离子形成稳定配合物。 本文依据实验结果,对3种Ni(Ⅱ)和2种Zn(Ⅱ)的乙基黄原酸盐混合配合物的性质作一些系统的比较.应用红外光谱讨论这些混合配合物的C—O及C—S键振动频率位移;用热谱讨论它们的热稳定性及失重过程的变化;通过组成分析用电子光谱及磁学方     

Synthesis and Characterization of Chloralose-Derived Thiosemicarbazones and Semicarbazones and Investigation of Their Antimicrobial Properties

Thiosemicarbazones(7–10)/semicarbazones(11–14) were synthesized in good yields via the condensation of α-gluco-, β-gluco-, galacto-, manno- chloralose derived 1,4-furanodialdoses (1-4) with thiosemicarbazide(5)/semicarbazide(6). The structures of all products were characterized by FTIR, NMR spectroscopic methods and elemental analysis. The compounds have been found to display moderate antimicrobial activity against Gram-positive, Gram-negative bacteria and antifungal activity against a Candida albicans. MIC values of the compounds range from 260 to 1510 μg/mL.     

Resurrection and Reactivation of Acetylcholinesterase and Butyrylcholinesterase

Organophosphorus (OP) nerve agents and pesticides present significant threats to civilian and military populations. OP compounds include the nefarious G and V chemical nerve agents, but more commonly, civilians are exposed to less toxic OP pesticides, resulting in the same negative toxicological effects and thousands of deaths on an annual basis. After decades of research, no new therapeutics have been realized since the mid-1900s. Upon phosphylation of the catalytic serine residue, a process known as inhibition, there is an accumulation of acetylcholine (ACh) in the brain synapses and neuromuscular junctions, leading to a cholinergic crisis and eventually death. Oxime nucleophiles can reactivate select OP-inhibited acetylcholinesterase (AChE). Yet, the fields of reactivation of AChE and butyrylcholinesterase encounter additional challenges as broad-spectrum reactivation of either enzyme is difficult. Additional problems include the ability to cross the blood brain barrier (BBB) and to provide therapy in the central nervous system. Yet another complication arises in a competitive reaction, known as aging, whereby OP-inhibited AChE is converted to an inactive form, which until very recently, had been impossible to reverse to an active, functional form. Evaluations of uncharged oximes and other neutral nucleophiles have been made. Non-oxime reactivators, such as aromatic general bases and Mannich bases, have been developed. The issue of aging, which generates an anionic phosphylated serine residue, has been historically recalcitrant to recovery by any therapeutic approach—that is, until earlier this year. Mannich bases not only serve as reactivators of OP-inhibited AChE, but this class of compounds can also recover activity from the aged form of AChE, a process referred to as resurrection. This review covers the modern efforts to address all of these issues and notes the complexities of therapeutic development along these different lines of research.     

Interaction and Stability of Mixed Micelle and Monolayer of Nonionic and Cationic Surfactant Mixtures

Interaction and stability of binary mixtures of cationic surfactants hexadecyltrimethylammonium bromide (HTAB) or hexadecylpyridinium bromide (HPyBr) with nonionic surfactant decanoyl-N-methyl-glucamide (Mega-10) have been studied at different mole fraction of cationic surfactants by using interfacial tension measurements and fluorescence probe techniques. From interfacial tension measurements, the critical micellar concentration and various interfacial thermodynamic parameters have been evaluated. The experimental cmc's were analyzed with the pseudophase separation model, the regular solution theory, and the Maeda's approach. These approaches allowed us to determine the interaction parameter and composition in the mixed state. By using the static quenching method, the mean micellar aggregation numbers of pure and mixed micelles of HTAB + Mega-10 were obtained. It has been observed that the aggregation number of mixed micelles deviates negatively from the ideal behavior. The micropolarity of the micelle was monitored with pyrene fluorescence intensity ratio and found to be increase with the increase of ionic content. The polarization of fluorescence probe Rhodamine B was monitored at different mole fraction of cationic surfactants.