The structure and electrochemical characteristics of La0.67Mg0.33 (Ni0.8Co0.1Mn0.1)(x) (x=2.5-5.0) multiphase alloys for nickel-metal hydride batteries

This paper presents results concerning structure and electrochemical characteristics of the La0.67Mg0.33 (Ni0.8Co0.1Mn0.1) (x) (x=2.5-5.0) alloy. It can be found from the result of the Rietveld analyses that the structures of the alloys change obviously with increasing x from 2.5 to 5.0. The main phase of the alloys with x=2.5-3.5 is LaMg2Ni9 phase with a PuNi3-type rhombohedral structure, but the main phase of the alloys with x=4.0-5.0 is LaNi(5)phase with a CaCu5-type hexagonal structure. Furthermore, the phase ratio, lattice parameter and cell volume of the LaMg2Ni9 phase and the LaNi5 phase change with increasing x. The electrochemical studies show that the maximum discharge capacity increases from 214.7 mAh/g (x=2.5) to 391.1 mAh/g (x=3.5) and then decreases to 238.5 mAh/g (x=5.0). As the discharge current density is 1,200 mA/g, the high rate dischargeability (HRD) increases from 51.1% (x=2.5) to 83.7% (x=3.5) and then decreases to 71.6% (x=5.0). Moreover, the exchange current density (I-0) of the alloy electrodes first increases and then decrease with increasing x from 2.5 to 5.0, which is consistent with the variation of the HRD. The cell volume reduces with increasing x in the alloys, which is detrimental to hydrogen diffusion and accordingly decreases the low-temperature dischargeability of the alloy electrodes.

杂多酸-聚(二烯丙基二甲基氯化铵)多层膜在4-氨基硫酚修饰金电极上的组装和电化学行为

通过电化学生长法在 4 氨基硫酚自组装膜修饰金电极上制备了包含杂多酸 (SiMo11VO5-4 0 和聚合物阳离子PDDA的多层膜修饰电极。用循环伏安法研究了该多层膜的电化学行为 ,结果表明Mo的第 3个还原峰随多层膜层数的增加显著增长 ,而另两个还原峰增长缓慢。该修饰电极的峰电位随pH的增加而线性负移 ,表明有氢离子参与杂多酸的氧化还原反应。该修饰电极对BrO-3 和HNO2 的还原反应有良好的催化作用 ,催化电流随着层数的增加而增长 ,并且Mo的第三个还原峰电流与CBrO-3 有良好的线性关系。

La_(1-x)Nd_xCrO_3(0.0≤x≤1.0)的化学键参数计算

使用复杂晶体化学键理论计算了La1-xNdxCrO3 (x =0 .0 ,0 .2 ,0 .4,0 .6 ,0 .8,1.0 )的化学键参数 ,如键性、键极化率等。结果表明 ,La-O ,Nd -O和Cr-O键的共价性基本上不随Nd掺杂的变化而变化 ,这个结论与实验结果一致。键极化率和磁距则随着掺杂量的增加而增加。共价性的大小次序为La -O

Investigation of Pr valence and relationship between bond covalency and T-c in Y1-xPrxBa2Cu3O7 (x = 0-1)

The valence of Pr and relationship between bond covalency and T-c in Y1-xPrxBa2Cu3O7 (x = 0-1) have been studied using complex chemical bond theory. The results indicate that the depression of superconductivity in Y1-xPrxBa2Cu3O7 can be reasonably explained by bond covalency difference for the bonds between CuO2 plane and CuO chain. T-c decreases with the decreasing of bond covalency difference and reaches zero when bond covalency difference is zero (or bond covalency in CuO2 exceeds that in CuO chain) at Pr concentration 0.55 and valence +3.30. These are in good agreement with the experiments and meanwhile suggest that the valence of Pr is + 3.30 in Y1-xPrxBa2Cu3O7. The results also indicate that for Pr valence less than +3.15, superconductivity always exists for whatever Pr concentration, whereas for Pr with a valence of +4.0, superconductivity disappears as soon as Pr concentration exceeds 0.19. This supports with the viewpoint that higher valence Pr will contribute more electrons to CuO2 plane, filling the mobile holes responsible for conduction. For PrBa2Cu3O7 with no Ba-site Pr, our calculation suggests that it will be a superconductor if the average valence of Pr is less than +3.15. (C) 1998 Published by Elsevier Science B.V. All rights reserved.

HPLC法测定野生与栽培藏药麻花艽中4种环烯醚萜苷类成分的含量

目的：对野生和栽培藏药麻花艽中龙胆苦苷、落干酸、獐牙菜苦苷和獐牙菜苷4种苦苷类成分进行高效液相色谱的含量测定，并比较分析它们之间的差异。方法：采用Eelipse XDB-C_8色潜柱(4.6 mm*150 mm，5 μm)，流动相A为95％乙腈水溶液，B为5％乙腈(含10 mmol•L~(-1)的甲酸)水溶液，A在0-20min内比例由0-100％进行线性洗脱，流速1.0 mL•min~(-1)，检测波长240 nm，柱温30℃。结果：4种成分均达到基线分离，龙胆菁苷、落干酸、獐牙菜苦苷、獐牙菜苷的线性范围分别为0.60～19•20μg(r=0.9999)，0.24～7.68μg(r=O.9999)，0.38-12.02μg(r=O.9999)，0.05～1.66μg(r=0.9999)；回收率分别为99.73％，98.13％，98.45％，96.22％。结论：栽培藏药麻花艽中苦苷类成分的含量已经接近或超过野生种的水平，可初步代替野生药材人药。

HPLC法测定獐牙菜及其近缘植物中4种有效成分的含量

目的:建立反相高效液相色谱法同时测定獐牙菜及其近缘植物中番木鳖酸、獐牙菜苦苷、龙胆苦苷、芒果苷的含量。方法:采用ZORBAX SB—C18(250 mm×4.6mm,5μm)色谱柱,以流动相甲醇和水(含0.04%磷酸)的比例在0-24 min内由22:78至38:62线性梯度洗脱,流速1 mL•min～1,检测波长254 nm,柱温30℃。结果:4种成分均达到基线分离,番木鳖酸、獐牙菜苦苷、龙胆苦苷、芒果苷的线性范围分别为0.05—6.25μg(r=0.9999),0.0095—2.9 μg(r=0.9998),0.0486—2.56μg(r=0.9999),0.0056—2.8μg(r=0.9998);回收率为102%(RSD=4.4%),97.7%(RSD=4.3%),99.5%(RSD=3.5%),103%(RSD=1.1%)。结论:方法测定快速,结果准确、可靠。

贵州4个洞穴滴水对大气降雨响应的动力学及其意义

在雨季, 采用NaCl 示踪的方法, 对贵州珠江水系的4 个岩溶洞穴(荔波凉风洞、都匀七星洞、安顺将军洞和镇宁犀牛洞)滴水点水的来源、滴水对大气降雨的响应尺度、水动力学过程等进行研究, 揭示出由于岩溶洞穴环境、水运移路径的联通性、水动力学过程等的不一致, 4 个洞穴的不同滴水点滴水对大气降雨响应的时间尺度为0~40 天. 根据水在洞穴顶板的运移特性、水的运行方式、水头类型等水文学特性的差异, 将这4 个洞穴的滴水点划分成5 种水动力学类型. 由于不同洞穴不同滴水点水-土、水-岩作用的时间尺度、作用方式、水运移路径等的差异, 影响到岩溶次生沉积物的物质来源及量度标准,加之不同洞穴各滴水点水动力条件的极大差异, 岩溶次生沉积物过去环境变化指标的解译应该有洞穴滴水水动力条件的结果作为支撑. 根据目前对这4 个洞穴众多滴水点滴水电导率的监测, 电导率与大气降雨量的一致变化, 意味着洞穴滴水形成的岩溶次生沉积物的元素含量具有记录岩溶环境过去变化的意义, 但应以多个点的研究结果来保证解译的正确性.

4. Nomenclature and syntaxonomy of castellano-cantabrian Thymus mastigophorus communities

Rivas Goday, Borja & Izco (Anales Inst. Bot. Cavanilles 26: 153 et seq. including table 2; 1970) described a Thymus mastigophorus association found on the «páramos» of Masa and La Brújula in the province of Burgos, Spain.

The trade unions membership dynamics and union members’ trajectories

This text presents an analysis of aggregated membership’s dynamics for Spanish trade unions, using ECVT data, as well as union memberships’ trajectories, or members’ decisions about joining the organization, permanency and responsibilities, and subsequent attrition. For the analysis of trajectories we make use of information of the records of actual memberships and the record of quitting of CCOO, and of a survey-questionnaire to a sample of leavers of the same union. This study allows us to confirm a linkage between the decision and motivations to become union member, to participate in union activities, the time of permanency, and the motives to quit the organization. We also identify five types of union members’ trajectories, indicating that, far from views that assert a monolithic structure, unions are complex organizations.

Women artists of the international avant-garde: the case of "Abstraction-Création" (1931-1936)

Women’s contribution to abstract art in the interwar period is a subject that, to date, has received very little attention. In this article we deal with the untold story of the participation of women artists in Abstraction-Création, the foremost international group dedicated to abstract art in the 1930s. Founded in Paris in 1931, the group took on the work of two previous collectives to become a platform for the dissemination and promotion of abstract art and consisted of around a hundred members. Twelve of these were women, whose writings and works were published in the group’s annual magazine, abstraction creátion art non figuratif (1932-1936), and who participated in a number of the group’s exhibitions. Compared to what had occurred in previous groups, the participation of women, although reduced in number, was comparable to that of the male artists and being members of the group had a generally positive impact on the women’s careers. However, all this came at the expense of relinquishing any gender specificity in their work and the public presentation of it, and demonstrates that the normalization of women’s contributions to the avant-garde could only be brought about alongside a questioning of the more dogmatic views of modernity.

Cálculo mental com números racionais não negativos: um estudo sobre as estratégias utilizadas por alunos do 4.º ano de escolaridade

Relatório Final apresentado à Escola Superior de Educação de Lisboa para a obtenção de grau de mestre em Ensino do 1.º e 2.º Ciclo do Ensino Básico

O diário de turma no 4º ano de escolaridade

Relatório de Estágio apresentado à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Ensino do 1.º e 2.ºCiclo do Ensino Básico

Contributos da utilização de mapas de conceitos para a aprendizagem de ciências naturais no 4º ano de escolaridade

Relatório de Estágio apresentado à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Ensino do 1º e 2º Ciclos do Ensino Básico

Experimental evidence of the spin-glass transition in the diluted magnetic semiconductor Zn(1-x)Mn(x)In(2)Se(4)

This work reports on magnetic measurements of the quasi-two-dimensional (quasi-2D) system Zn(1-x)Mn(x)In(2)Se(4), with 0.01 <= x <= 1.00. For x > 0.67, the quasi-2D system seems to develop a spin-glass behaviour. Evidence of a true phase transition phenomenon is provided by the steep increase of the nonlinear susceptibility chi(nl) when approaching T(C) from above. The static scaling of chi(nl) data yields critical exponents delta = 4.0 +/- 0.2, phi = 4.37 +/- 0.17 and TC = 3.4 +/- 0.1 K for the sample with x = 1.00 and similar values for the sample with x = 0.87. These critical exponents are in good agreement with values reported for other spin-glass systems with short-range interactions.