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。     

环保型汽油清净剂的研制及性能测试

以聚异丁烯基丁二酰亚胺和脲基氨基甲酸酯化合物为复合清净分散剂、多羟基醚类化合物为协同增效剂，研制了环保型汽油清净剂，通过试验确定了各组分的配比。对汽油清净剂进行了性能测试，如模拟试验、铜片腐蚀性能测试和辛烷值测试等。该汽油清净剂对发动机燃油吸入系统有良好的清洗和保洁功能，达到了降低尾气排放和节省燃油的效果。     

碳酸盐含量自动分析仪的性能测试

作者采用库仑滴定原理，利用光电转换、微机控制电解终点，研制了一台碳酸盐含量自动分析仪。本文介绍了有关仪器性能测试方面的工作，包括对碳酸盐标样（９９．９９％的优级纯ＣａＣＯ３）的测试，准确度达０．０８％，精密度为０．８７％；并与定容测压方法进行了比较，本仪器对油田、沉积物样品进行的测试表明具有分析准确度高、分析速度快、用样量少、自动化程度高等优点。适合在石油、沉积、矿床及第四纪等领域应用。     

龋病人牙釉质表面硬度及抗磨损性能测试

采用人工方法制成人牙釉质浅龋及使用抗龋措施的龋损釉质样本，分别测量各组釉质表面显微硬度，并以微动摩擦磨损试验机测试其抗磨性能，试验结果表明：各组实验组釉质较对照组表面硬度都有不同程度下降，氟化钠前处理会使釉质表达硬度显著下降，人工浅龋牙釉质的抗磨损性能不如正常釉质，使用两种抗龋措施对其抗磨性能没有明显改善。     

VOCs标准吸附管制备及性能测试研究

采用多组分挥发性有机物（VOCs）扩散管（渗透管）标准气体和不锈钢吸附管通过多组分动态配气装置（ISO6145）和气体定量吸收系统制备标准吸附管,通过试验证明,该标准吸附管有很好的一致性和线性。通过稳定性考察证明,用该方法制备的标准吸附管,在密封条件下一年内各组分量值测定结果的相对标准偏差不大于1．5％（n=12）。制备的VOCs标准吸附管可以作为标准物质使用。     

镧对Al-Ti-C晶粒细化剂显微组织与细化性能的影响

采用自蔓延＋熔铸法制备Al-Ti-C晶粒细化剂。通过光学显微镜（OM）、透射电镜（TEM）、扫描电镜（SEM）、X射线衍射仪（XRD）和能谱分析（EDS）等手段，研究了稀土镧对晶粒细化剂的组织结构和细化性能的影响。结果表明：镧极大地提高了石墨在铝熔体中的润湿性；镧的加入改变了TiAl3和TiC的形貌、数量和分布，使块状TiAl3和非团簇状TiC均匀分布在α—Al基体上，从而对工业纯铝产生优异的晶粒细化效果。     

几种新重氮氨基试剂的合成及其分析性能

合成了 6种新的重氮氨基新试剂。研究了试剂亚氨基质子的离解常数p Ka及试剂与 Cd( )的显色反应。结果表明 ,随着试剂 1位苯环上的对、间位取代基的取代基常数 σ值的增大 ,试剂亚氨基的质子离解常数 Ka也增大 ( p Ka值减小 ) ,与 Cd2 +反应的显色酸度也越高 ;反应的最佳操作酸度 p H操作 与试剂p Ka存在如下关系 :p Ka=p H操作 - ( 1 .4± 0 .2 )     

基于2,5-二(4-氨基苯)嘧啶聚酰亚胺的合成及性能表征

1,5-二氮杂戊二烯盐(vinamidium salts)与4-硝基苯甲脒盐在碱性物质的存在下发生成环反应得含嘧啶环的硝基化合物;硝基化合物用Pd/C和水合肼还原得到棒状含氮芳杂环二胺——2,5-二(4-氨基苯基)嘧啶.通过1H-NMR,13C-NMR,IR,MS及元素分析确证了含氮芳杂环二胺及其中间产物的结构.这种二胺或加一定量对苯二胺与均苯二酐(PMDA)或联苯二酐(BPDA)通过两步法聚合获得一系列聚酰亚胺,通过红外、动态力学、静态力学、热重分析、广角X射线衍射等实验测试了该类聚合物的结构、热性能、机械性能及结晶性能.     

柔性交联型聚酰亚胺气凝胶的制备及性能

利用溶胶-凝胶反应制备了聚酰亚胺凝胶, 经过超临界干燥得到了聚酰亚胺气凝胶. 研究了固含量和交联剂比例对气凝胶性能的影响规律. 结果表明, 聚酰亚胺气凝胶的密度和线收缩率都随着固含量和交联剂比例的增加而增加; 随着固含量的增加, 气凝胶的室温热导率呈现出先降低再增加的趋势(0.026~0.033 W·m^-1·K^-1), 气凝胶的力学刚度和强度明显提升; 交联剂的加入, 可以提高材料的韧性, 断裂应变最高达21.7%; 制得的柔性聚酰亚胺气凝胶具有良好的热稳定性, 是满足尖端武器以及空间飞行器对于轻质、 柔性热防护要求的理想材料之一.     

抗结块硝酸铵的制备及性能测试

硝酸铵是一种极易溶于水的无机盐,由于它来源广、成本低以及具有低爆轰性和燃烧时无烟或少烟的特性,因而不仅被作为农用肥料和化工原料,而且还被作为固体推进剂和工业炸药的主要氧化剂.但是,由于硝酸铵具有多晶性,常压下,它有5种热力学稳定的晶体结构[1].每种晶体仅在一定的温度范围内存在,当温度发生变化时,各种晶体之间可以发生转变.当硝酸铵从一种晶体向另一种晶体转变时会伴随着热量、比容、热容和熵等物理参数的突然变化,同时还会引起硝酸铵晶体之间的内凝聚力发生变化,从而导致了硝酸铵易结块性的性质.     

Topological studies on IRC paths of the isomerization reaction of silicon methyl-nitrene

On the basis of kinetic study of isomerization reaction of H_3Si-N, ab initio (RHF, UHF/6-31G) calculations on some points of the singlet and triplet reaction paths were carried out. The breakage and formation of chemical bond in the reaction are discussed. The calculated results show that there is a transitional structure of three-membered ring on each of reaction paths. A 'structural transition region' and a 'structural transition state' in both of studied reaction are found. Our previous conclusion that the structure transition state (STS) always appears before the energy transition state (ETS) in endothermic reaction and after ETS in exothermic reaction is further confirmed. The relationship between the change of spin density distribution and the structural transition state are investigated.     

Analysis of Variance (ANOVA) for Optimizing the Nano-SiO2 Content of High Performance Epoxy Nanocomposites

Epoxy based nanocomposite samples containing SiO₂ nanoparticles (0.0–3.0 %w) were prepared for physical and mechanical evaluation. Some thermomechanical and physical properties of samples were investigated using dynamic mechanical analysis (DMA), tensile strength, hardness and abrasion tests. The main aim of experimentation was to realize the optimum amount of nano-SiO₂ which would demonstrate the best improving effect on mechanical and physical properties of nanocomposite samples and finding how significant a factor is for improving in physical and mechanical properties. Analysis of variance (ANOVA) was applied for optimization of SiO₂ content in epoxy based nanocomposites.     

Performance of Hyperspherical Harmonic Expansionon the Low-lying Pand D States of Helium Atom

IntroductionThe hyperspherical coordinate and corresponding hyperspherical harmonics (HH) havebeen applied to various areas of physics, such as three--body scattering, nuclear and atomicphysics as well as quantum chemistry['J, since the 1950's. The HH--generalized Laguerrefunction method (referred to as HHGLF) [2'3] and several modified versions developed by Dengand his coworkers, such as the potential harmonic--generalized Laguerre function(PHGLF )L'], and the correlation fun ct ion --…     

Cs的覆盖度对Cs/石墨烯的结构稳定性和场发射性能影响

采用密度泛函理论方法,对Cs以不同覆盖度吸附在石墨烯表面时系统的结构稳定性和场发射性能进行了研究.计算结果表明单原子Cs吸附在石墨烯表面的碳六元环的中心位置时系统的能量最低.随着Cs的覆盖度增加,碱金属Cs与石墨烯之间的吸附作用逐渐增强,(4×4)R 0°和(2×2)R 0°结构是稳定的.由于碱金属Cs的修饰作用,Cs/石墨烯体系的功函明显下降,且随着碱金属Cs的覆盖度增大,系统的功函逐渐减小.态密度的计算结果表明功函的下降主要与Cs和石墨烯之间的电子转移有关.随着覆盖度的增大,石墨烯的电子态逐渐向低能方向移动,系统的费米能级升高并导致材料的功函下降.     

氧原子与二硫化碳反应的机理

用从头计算法、内禀反应坐标和电子密度拓扑分析方法研究了3P态氧原子与二硫化碳的反应.找到了分别形成CS SO,S OCS和S2 CO三个反应通道上的极小点和过渡态.采用UHF/631G进行几何构型优化,并在UMP2/631G水平上进行能量校正.三个反应通道上的稳定点和过渡态都经内禀反应坐标(IRC)跟踪得以确认,并用电子密度拓扑分析方法考察了反应过程中化学键的变化.计算结果表明,反应过程中所有稳定点和过渡态都具有Cs对称性,即对每个反应通道而言在整个反应过程中分子始终保持在同一平面内.在三个反应通道中,第一个反应通道O CS2→CS SO由于具有较小的活化能而更容易发生,与实验结果相一致.文中对反应机理进行了较详细的讨论.     

Cs的覆盖度对Cs/石墨烯的结构稳定性和场发射性能影响

采用密度泛函理论方法,对Cs以不同覆盖度吸附在石墨烯表面时系统的结构稳定性和场发射性能进行了研究。计算结果表明单原子Cs吸附在石墨烯表面的碳六元环的中心位置时系统的能量最低。随着Cs的覆盖度增加,碱金属Cs与石墨烯之间的吸附作用逐渐增强,(4×4)R 0°和(2×2)R 0°结构是稳定的。由于碱金属Cs的修饰作用,Cs/石墨烯体系的功函明显下降,且随着碱金属Cs的覆盖度增大,系统的功函逐渐减小。态密度的计算结果表明功函的下降主要与Cs和石墨烯之间的电子转移有关。随着覆盖度的增大,石墨烯的电子态逐渐向低能方向移动,系统的费米能级升高并导致材料的功函下降。     

Variable ranking based on the estimated degree of separation for two distributions of data by the length of the receiver operating characteristic curve

Variable responses are fundamental for all experiments, and they can consist of information-rich, redundant, and low signal intensities. A dataset can consist of a collection of variable responses over multiple classes or groups. Usually some of the variables are removed in a dataset that contain very little information. Sometimes all the variables are used in the data analysis phase. It is common practice to discriminate between two distributions of data; however, there is no formal algorithm to arrive at a degree of separation (DS) between two distributions of data. The DS is defined herein as the average of the sum of the areas from the probability density functions (PDFs) of A and B that contain a ≥ percentage of A and/or B. Thus, DS90 is the average of the sum of the PDF areas of A and B that contain ≥90% of A and/or B. To arrive at a DS value, two synthesized PDFs or very large experimental datasets are required. Experimentally it is common practice to generate relatively small datasets. Therefore, the challenge was to find a statistical parameter that can be used on small datasets to estimate and highly correlate with the DS90 parameter. Established statistical methods include the overlap area of the two data distribution profiles, Welch’s t-test, Kolmogorov–Smirnov (K–S) test, Mann–Whitney–Wilcoxon test, and the area under the receiver operating characteristics (ROC) curve (AUC). The area between the ROC curve and diagonal (ACD) and the length of the ROC curve (LROC) are introduced. The established, ACD, and LROC methods were correlated to the DS90 when applied on many pairs of synthesized PDFs. The LROC method provided the best linear correlation with, and estimation of, the DS90. The estimated DS90 from the LROC (DS90–LROC) is applied to a database, as an example, of three Italian wines consisting of thirteen variable responses for variable ranking consideration. An important highlight of the DS90–LROC method is utilizing the LROC curve methodology to test all variables one-at-a-time with all pairs of classes in a dataset.     

高效液相色谱/质谱分析抱茎獐牙菜提取物中的苷性成分

采用高效液相色谱／质谱法（HPLC／MS）分析抱茎獐牙菜提取物中5种苷性成分。在C18柱上,以甲醇（A：含20％水）和水（B：含10％甲醇）为流动相,流速1mL／min,线性梯度洗脱B从100％到0％,35min,液相色谱-质谱质联用（LC／MS）,大气压化学电离源（APCI）,对其中5种苷性成分进行定性鉴定。经HPLC／APCIMS分析确证,抱茎獐牙菜提取物中含有獐牙菜苦苷（swertiamarin）、龙胆苦苷（gentiopicroside）、獐牙菜苷（sweroside）、异红草苷（isoorientin）和獐牙菜山酮苷（swertianolin）。采用外标法定量,回收率分别为98．3％、106．7％、92．3％、88．2％和107．3％,该方法简便、快速、准确。     

三电子原子的超球坐标分析和基态能态计算

用超球坐标表示多电子原子的薛定谔方程,从符合Pauli原理的全反称波函数出发,推导出相应的超球径耦合微分方程,其形式与双电子原子的相似。以九维超球谐为投影函数构造S₃群不可约表示的对称基,将超球谐-广义Laguerre展开法(HHGL)推广到Li原子,首次对其Schrdinger方程的精确求解进行了研究,基态能量的计算值与实验值接近。最后,还从波函数出发对提高计算的精度进行了讨论。     

Analysis of the concept of minimum energy path on the potential energy surface of chemically reacting systems

Some confusion regarding the properties of minimum energy paths is evident in the literature. We show that a way of steepest descent on a potential surface can be defined independently upon the choice of the coordinate systems. The result is applied to mass-weighted coordinates and their use is critically reviewed. Fukui's IRC appears to be a special case of the steepest descent path starting from a saddle point. The impossibility to define a general ascent path is illustrated and the relations of IRC to real trajectories are discussed.