Underpotential Deposition Study and Determination of Bismuth on Gold Electrode by Using Voltammetry

ＴｈｅｃｏｍｂｉｎａｔｉｏｎｏｆｓｔｒｉｐｐｉｎｇｖｏｌｔａｍｍｅｔｒｙｗｉｔｈＵＰＤｃａｎｌｅａｄｔｏｔｈｅｉｍｐｒｏｖｅｍｅｎｔｏｆｓｅｎｓｉｔｉｖｉｔｙ ,ｓｅｌｅｃｔｉｖｉ ｔｙａｎｄｒｅｖｅｒｓｉｂｉｌｉｔｙｆｏｒｅｌｅｃｔｒｏａｎａｌｙｔｉｃａｌｐｕｒｐｏｓｅａｎｄａｖｏｉｄｔｈｅｕｓｅｏｆｔｏｘｉｃｍｅｒｃｕｒｙａｓｔｈｅｗｏｒｋｅｌｅｃｔｒｏｄｅ1ａｎｄｔｈｅｎａｎａｌｙｔｉｃａｌａｐｐｌｉｃａｔｉｏｎｓｈａｖｅｂｅｅｎｄｅｓｃｒｉｂｅｄ .2 4 Ｉｎｔｈｉｓｗｏｒｋ ,ｗｅｄｅｖｅｌｏ…     

活性炭的Zeta电位对其吸附达旦黄规律的影响

The effect of pH on the adsorption of anionic dye Titan yellow on the activated carbon from aqueous solution has been studied. It has been found that the Zeta potential of the activated carbon has a great effect on adsorption capacity of Titan yellow. The kinetic and the thermodynamic parameters of adsorption as a function of pH has been evaluated. The mechanism for adsorption of anionic dye Titan yellow on the activated carbon has also been discussed.     

吸附溶出伏安法测定水中痕量镉

报道了测定痕量镉的一种新方法．在０．０１ｍｏｌ／ＬＨＡｃ－０．０１ｍｏｌ／ＬＮａＡｃ－１．２×１０－５ｍｏｌ／Ｌ乙醛酸缩氨基硫脲（ＧＡＴＳＣ）体系中，Ｃｄ－ＧＡＴＳＣ产生一灵敏的吸附还原波，波的峰电位是－０．４３Ｖ（ｖｓ·ＳＣＥ），峰电流与镉的浓度在１．０×１０－８～８．０×１０－７ｍｏｌ／Ｌ范围内成直线关系．此法用于测定水中痕量镉，结果令人满意。     

用计时电位法测定镧在铝液中的扩散系数

采用新的阳极溶解的计时电位法,测定了稀土金属镧在铝液中的扩散系数。在973K时,测得(Al)=(1.21±0.02)×15~(5)cm~2·s~(-1)。在953～1053K温度范围内,扩散系数与温度的关系为lgD_(La)(Al)=1.04×10~(-4)—4770/T,计算出扩散激活能Q=91.34KJ/mol。     

Theoretical Study on the Antioxidant Activity of Curcumin

The computational results for curcumin at the B3LYP/6-31G(d,p) level show that the enol form of curcumin is more stable than the diketo form because of an intramolecular hydrogen bond, which extends the conjugation effect in the enol chain, formed in the enol structure. Cis-diketone form can not be obtained, presumably due to the strong repulsion between the carbonyl dipoles aligned in parallel. According to the phenolic O-H bond dissociation enthalpy, curcumin in its most stable form can be suggested to be a relatively good antioxidant. In order to avoid overcoming H-bond interaction and to improve the antioxidant activity of curcumin, a catechol moiety was incorporated into curcumin for designing a novel antioxidant. It is found that the designed molecule is much more efficient to scavenge radical than curcumin, comparable to vitamin E. Moreover, the ionization potential of the designed molecule is similar to that of curcumin, indicating that the designed molecule can not display the prooxidant effect.     

镍电极开路电位测定微量硼氢根离子

实验采用循环伏安法，用镍电极代替铂铑等贵金属电极测定了碱性体系中不同硼氢根离子浓度下的开路电位，得出了研究电极的开路电位（-0．355～-0．280vs.SCE／V）与微量硼氢根离子浓度的对应关系，并用于监测电解偏硼酸钠制备硼氢化钠体系中微量硼氢根离子，同时计算了该方法的误差。结果表明，测量结果的相对标准偏差为2．2％；回收率为98．4％。该法简单、快速，可测定10^-5～10^-3mol／L范围的硼氢根离子浓度。     

选相示波伏安法

选相示波伏安法毕树平，都思丹，高鸿（南京大学化学系，２１０００８）关键词示波计时电位法，选相示波伏安法，切口示波计时电位法是利用ｄＥ／ｄｔ～Ｅ曲线上切口的高度或深度进行定量分析的方法［１］，但由于ｄＥ／ｄｔ曲线主要反映充电电流的变化，从而使该方法的检...     

外光电法测量普朗克常量的误差分析与修正

光电效应实验测量得到的普朗克常量与公认普朗克常量值之间存在较大误差,本文通过一系列实验和数据分析,证明了光电效应实验中截止电压对应的光波长并不是滤色片标称的波长,而是小于滤色片标称的波长,是与光电管灵敏度相关的某一起始波长,即起始波长标称不准是误差的主要因素,并设计了相应的改进方案.     

旧知生长引出新知,信息技术提升效益——以“锐角三角函数”单元教学起始课为例

锐角三角函数是初中阶段最后"出场"的新知识(也是开启一个重要的数学分支),可以选择的新知生长点有很多,不少教材都是从生活现实出发,研究特殊直角三角形在生活中的边角关系,依次定义正切、正弦、余弦,最后归纳概括出正切函数、正弦函数、余弦函数,而且分散在两到三个课时中进行,这样当然能化解难点,并且针对每个新出现的三角函数能进行足够的解题训练.然而,上述"分散"课时教学的一个不足就是在新引入一个数学分支时不利于学生第一时间感知整体,对三角函数的源头——"客从何处来"也不甚清楚.基于以上认识,我们整合教材资源,构思了"锐角三角函数"单元教学起始课,本文整理出来,供研讨.