Effect of Fe doping on structure,magnetic and electrical properties La0.7Ca0.3Mn0.5Fe0.5O3 manganite

The crystal and magnetic structures of La_0.7Ca_0.3Mn_0.5Fe_0.5O₃ compound have been studied by neutron powder diffraction in the temperature range of 10–300 К. The magnetization and electrical resistivity measurements have been also performed in the temperature range of 5–300?K in magnetic fields up to 1?T. These experimental results indicate a formation of a complex magnetic state in which the long-range antiferromagnetic G-type phase coexists with the short-range ferromagnetic clusters. The electrical conductivity of La_0.7Ca_0.3Mn_0.5Fe_0.5O₃ demonstrates an anomalous temperature behavior suggesting a switching between different states. The origin of the unconventional magnetic state, the mechanisms of the electrical conductivity, and correlation between magnetic and transport properties in this manganite have been discussed.     

基于挣值管理的项目工期成本优化分析

基于挣值管理的思想,论文利用计量模型建立成本、工期、质量函数关系,对项目在实施阶段某一时刻的状态进行分析,运用工期成本之间的替代关系为项目经理人提供决策的依据与控制方向,实现项目最优管理.     

Electroactive polymers containing 3-arylcarbazolyl units as hole transporting materials for OLEDs

Monomers and their polymers containing 3-arylcarbazolyl electrophores have been synthesized by the multi-step synthetic route. The materials were characterized by thermo-gravimetric analysis, differential scanning calorimetry and electron photoemission technique. The polymers represent materials of high thermal stability having initial thermal degradation temperatures in the range of 331–411 °C. The glass transition temperatures of the amorphous polymeric materials were in the rage of 148–175 °C. The electron photoemission spectra of thin layers of monomers showed ionization potentials in the range of 5.6–5.65 eV. Hole-transporting properties of the polymers were tested in the structures of organic light emitting diodes with Alq₃ as the green emitter. The device containing hole-transporting layers of polyether with 3-naphthylcarbazolyl groups exhibited the best overall performance with a maximum current efficiency of 3.3 cd/A and maximum brightness of about 1000 cd/m².     

水杨醛缩胺类双席夫碱过渡金属配合物的合成与表征

以水杨醛与乙二胺为原料,通过席夫碱反应合成一类水杨醛缩胺类双席夫碱,并进一步与铜、锌、镍3种金属离子络合得到3种过渡金属配合物;采用元素分析、红外光谱和紫外光谱对席夫碱及其金属配合物的结构进行表征.结果表明,合成的水杨醛缩乙二胺配体分子结构与理论结构相符,且分别与铜、锌、镍离子络合形成了稳定的过渡金属配合物.     

新型罗丹明B衍生物的合成及其对Cu^2＋的检测

以罗丹明6G、乙二胺、水杨醛为原料在无水乙醇中合成了一种新型罗丹明B类衍生物。在pH=6.54条件下,该衍生物的乙醇溶液无荧光及紫外-可见吸收。相比于其它一些常见金属离子,其对Cu（Ⅱ）具有较高的选择性响应：加入Cu2＋溶液后,溶液迅速由无色变为粉红色,表现出较大的荧光强度和紫外-可见吸收且结合过程为可逆反应。由该衍生物对Cu（Ⅱ）响应的工作曲线得出：Cu（Ⅱ）浓度在0~1.0×10-4mol/L范围内服从朗伯-比尔定律,相关系数r=0.9973,检出限为6.328×10-8μg/mL。应用等摩尔连续变化法求得该衍生物与Cu（Ⅱ）络合比为1：1,条件稳定常数K=2.561×105（室温）。     

二苯甲胺缩水杨醛类Schiff碱的合成及其表征

以二苯甲酮为原料经过酰胺化、还原、水解得二苯甲胺盐酸盐,再与水杨醛及其衍生物5-氯水杨醛反应,生成了两种二苯甲胺缩水杨醛类Schiff碱。其中二苯甲胺盐酸盐的酰化最佳反应条件为:回流温度控制在140℃,时间为20h,收率为89%;目标产物总收率均为97%以上,并利用IR、MS、1 H NMR、UV-vis及荧光光谱等方法对产物进行了表征。     

1-磺甲基四氮唑-5-硫醇双钠盐的合成

研究了头孢尼西的侧链１－磺甲基四氮唑－５－硫醇双钠盐的合成。以亚硫酸氢钠、甲醛、氨水为原料，经五步反应可制备１－磺甲基四氮唑－５－硫醇双钠盐，五步反应总收率为１０．８％ 。在原文献的基础上，作了一些改进，最主要的是第三步的烷基化试剂由溴乙烷替代碘甲烷，降低了工业成本，使本工艺易于工业化。     

Synthesis and Characterization of Mono‐, Di‐, and Tetranitrated 7,8‐Disubstituted Glycolurils

Three 7,8‐disubstitited glycolurils were synthesized and subjected to various nitration conditions yielding the corresponding mono‐, di‐, and tetranitro derivatives. Prior to their synthesis, these nitrated compounds were evaluated computationally to determine their densities and heats of formation, from which explosive performance was predicted. Details on the methods used for the synthesis as well as the results from their computational analysis are discussed.     

N—（D,L—异丙酸基）—马来酰亚胺的合成

研究Ｎ－（Ｄ,Ｌ－异丙酸基）－马来酰胺酸闭环合成Ｎ－（Ｄ,－异丙酸基）－马来酰亚胺,考察了溶剂、催化剂用量、反应时间对产率的影响,同时也考察了混合剂对粗产物重结晶的影响,确定了最佳反应条件。所得Ｎ－（Ｄ,Ｌ－异丙酸基－）民来酰亚胺的产率达５２％。本实验具有产率高、溶剂容易回收、ＡＭＡ不需纯化等优点。     

含水杨基新型席夫碱的合成与表征

研究水杨醛分别与间苯二胺、邻氨基对甲苯酚、邻氨基苯甲醇、邻氨基苯甲醚进行反应合成了新型的席夫碱。以无水乙醇作为溶剂,在pH 7~8的条件下顺利合成了对应的Schiff碱,并对各个Schiff碱的合成条件分别进行了探索性试验,确定了合成它们的各自优化条件;产品通过元素、UVI、R1、H NMR和13C NMR分析。