Mg60Cu30Y10合金微观结构的第一性原理研究

该文利用第一性原理计算对Mg60Cu30Y10合金进行了模拟研究,分析Mg60Cu30Y10合金的几何特征：双体关联函数、三体关联函数、空间关联系数,并利用Voronoi拼砌方法对Mg60Cu30Y10合金的结构做了分析.计算发现Mg60Cu30Y10合金中Mg原子的环境与晶态Mg2Cu中的环境类似,而Cu-Y、Y-Y之间的关联对于合金的性能起着决定性的作用.     

Mg-Cu／SiO2催化剂上NO＋CO反应的活性研究

采用溶胶凝胶法制备了Cu／SiO2催化荆,用浸渍法将Mg元素担载在Cu／SiO2催化荆制得Mg-Cu／SiO2催化荆,研究在NO＋CO反应中的催化活性．结果表明,Mg修饰的采用方法（c）制备的Cu／SiO2催化荆,当Cu的含量是载体SiO2质量的2％,Mg的含量是载体SiO2质量的3％时,Mg-Cu／SiO2催化荆活性最高,250℃时NO生成N2的转化率接近100％．     

Mg／Al／Cu类水滑石焙烧产物对茜素黄GG的吸附

采用共沉淀法以不同的Mg^2＋、Al^3＋与Cu^2＋摩尔比制备一系列的镁铝铜三元类水滑石（Cu／Mg／Al—HTLc）。并研究了镁铝铜类水滑石的焙烧产（HTLc-500）对阴离子染料茜素黄GG的吸附特征。分别考察了不同镁铝铜摩尔比的HTLc－500、吸附剂投放量、反应温度、染料的初始浓度等因素对HTLc-500吸附阴离子染料茜素黄GG的影响。结果表明,对于合有20mg／L的茜素黄GG模拟废水溶液,镁铝铜摩尔比为8：10：22的类水滑石,投放量为25mg。在25℃下反应360min。去除率可达到99．14％。     

铜铬钼／=二氧化硅三元复合加氢催化剂中铜,铬,钼的分析

本文报导了Ｃｕ＝ｅｒ－Ｍｏ／ｓｉｏ２三元复合催化剂中Ｃｕ，Ｃｒ，Ｍｏ的测定方法，此法简便，快速，获得令人满意结果。     

南丹大厂矿区土壤中Fe、Zn、Cu含量的测定

采用分光光度法测定广西南丹县大厂镇矿区36个土壤样品中的Fe、Zn、Cu含量.结果表明南丹县大厂矿区土壤中Fe、Zn、Cu含量较高,其中最高含量分别为11 890.73 mg/kg、7 582.87 mg/kg、1 540.78 mg/kg,平均含量分别为10 293.65 mg/kg、4 329.31 mg/kg、589.16 mg/kg.土壤中Fe、Zn、Cu的平均含量分别超过世界土壤背景值、中国土壤背景值、广西土壤背景值的257.14、48.10、19.64;367.33、53.85、26.07;298.12、9.24、28.34倍.     

茶叶中铜铅含量的检测

茶是中华民族的传统饮品,其品种众多,主要从不同的工艺、同种工艺的不同品种、同一品种的不同等级这三方面进行分类.本文利用原子吸收光谱法对在市场上随机收集的各种茶叶中铜、铅的含量进行测定.分析结果表明,茶叶中铜、铅含量和分布状况与茶叶的品种、品质和等级有密切关系.     

火焰原子吸收光谱法测定茶叶中锌、铁、铜、锰

研究火焰原子吸收光谱法测定茶叶中的Zn、Fe、Cu、Mn等4种微量元素。以HNO3和H2O2为茶叶的分解试剂,方法简便,具有良好的精密度和准确度。测得Zn、Fe、Cu、Mn4种元素的相对标准偏差分别为1.5%、1.9%、3.2%、0.35%,4种元素的测试回收率在92.0%~106%之间。     

FAAS法测定土壤微量元素Fe、Cu、Zn、Mn、Pb的有效态含量

采用DTPA浸取液提取土壤中的Fe、Cu、Zn、Mn、Pb元素,用火焰原子吸收光谱法(FAAS)进行测定.该方法回收率在98.4%～102.4%之间;相对标准偏差小于3.7%;检出限低于0.04 mg·L-1.     

火焰原子吸收法快速测定高纯锌中痕量Pb,Cd,Fe,Cu,Sb和Mn的含量

用HNO3溶解试样，配制6种元素混合标准系列溶液，用空气－乙炔火焰原子吸收法连续测定Pb,Cd,Fe,Cu,Sb和Mn的含量。建立了优化的仪器测定条件，并进行了相关的干扰实验。方法的回收率为98.9%-102.0%，相对标准偏差为1.8%-2.5%。     

The developmental trajectory of intrinsic reading motivation: Measurement invariance,group variations,and implications for reading proficiency

The goal of the present study is to extend previous research on the developmental trajectory of intrinsic reading motivation during early adolescence. Using large-scale panel data on secondary school students in Germany, we examined: (1) the longitudinal measurement invariance of intrinsic reading motivation, (2) the generalizability of the developmental trajectory of intrinsic reading motivation across students’ gender, parental socioeconomic status (SES), and school tracks (academic vs. vocational), and (3) the associations between the developmental trajectory of intrinsic reading motivation and the developmental trajectory of reading proficiency. The scale we used to measure intrinsic reading motivation showed the (strict) measurement invariance across six occasions of measurement from Grades 5 to 10, indicating the high structural similarity (e.g., factor loadings, intercepts) of intrinsic reading motivation during early adolescence. Our analyses of latent growth curve models also confirm previous findings that students tend to experience a steady and significant linear decline in intrinsic reading motivation from Grades 5 to 10. This developmental decline also seems to be more pronounced in size (Δ =  − 0.772, p < .001) than previously reported. The developmental decline in intrinsic reading motivation was observed irrespective of students’ gender, parental SES, and school tracks. Male students expressed lower mean-levels of intrinsic reading motivation across the waves and exhibited a steeper motivational decline compared to female students. Despite mean-level differences across the waves, students showed similar degrees of a motivational decline across parental SES and school tracks. Finally, the larger decline in students’ intrinsic reading motivation was associated with the smaller growth of their reading proficiency from Grades 5 to 10. Our study provides further support for the high prevalence of the developmental decline in intrinsic reading motivation during early adolescence, its generalizability across students’ demographic characteristics, and its implications for the development of reading proficiency.     

Effects of surface modification by Ni, Ti and B on electrochemical properties of Mg1.8Cu0.2Ni hydrogen storage alloy

Amorphous alloy Mg1.8Cu0.2Ni was successfully prepared by mechanical alloying (MA) and a series of (n?x)Nix(Ti?B) composites were synthesized by MA. The electrochemical properties of Mg1.8Cu0.2Ni coated by Ni, Ti and B were studied by cyclic charge-discharge, linear polarization curve, and hydrogen diffusion coefficient experiments. Experimental results indicate that Mg1.8Cu0.2Ni-[0.9Ni0.6(Ti?B)] composite which was MA 30 h exhibited the best performance and its initial discharge capacity arrived to 714.1 mAh/g. After 30 cycles the discharge capacity was above 530 mAh/g, which was much higher than that of Mg1.8Cu0.2Ni. And after 100 cycles it holded still 442.1 mAh/g. On all accounts, after modification by Ni, Ti and B, the initial discharge capacity and high-rate discharge ability of the electrode were evidently increased. At the same time, the cycle performance was also improved significantly.