Alternating current conductivity and dielectric properties of newly prepared poly(bis thiourea sulphoxide)

Poly(bis-thiourea sulphoxide) was prepared by Michael addition mechanism of thiourea with bis-sulphinyl thiourea, which in turn, was prepared by the reaction of thiourea with thionyl chloride. The formed polymer was identified by microchemical analysis and IR spectrum. Thermogravimetric analysis shows that it is stable up to 490°K, and having thermal activation energy 11.2 K cal·mol m 1 . It is of relatively low molecular weight as found from the inherent viscosity value (0.242 dLg m 1 ). Alternating conductivity measurements at different temperatures and frequencies exhibited that the prepared polymer is a highly polarized material. The relaxation time of the orientational process is about 9 2 10 m 11 second and the activation energy of this process is 0.387 eV. The conduction mechanism could be attributed to the correlated barrier hopping (CBH) model.     

铜钼铅锌共生矿中微量钼测定方法的改进

在铜钼铅锌共生矿溶液中,用抗坏血酸代替硫脲作还原剂,用盐酸代替硫酸,可克服溶液混浊,提高显色液的稳定性,其测定结果准确。     

Comments on the paper “Electrooxidation of borohydride on platinum and gold electrodes: Implications for direct borohydride fuel cell” by E. Gyenge, Electrochim. Acta 49 (2004) 965: Thiourea, a poison for the anode metallic electrocatalyst of the direct borohydride fuel cell?

The present discussion paper deals with the Gyenge's [E. Gyenge, Electrochim. Acta 49 (2004) 965] suggestion to add thiourea (H₂N-CS-NH₂) to the borohydride fuel of the direct borohydride fuel cell (DBFC). It is expected that thiourea inhibits the hydrogen evolution (stem from the borohydride hydrolysis, a side reaction) that occurs at the anode of the DBFC where in fact it is expected the direct oxidation of borohydride.However, thiourea is an organic sulphur compound and it is well known that the sulphur species are poisons for the metallic catalysts. Hence, the present discussion paper asks a question: may thiourea and the sulphur species stem from its decomposition act as poisons of metallic sites of catalysts used as DBFC anodes?     

The influence of thiourea on copper electrodeposition: Adsorbate identification and effect on electrochemical nucleation

The effect of thiourea on copper deposition onto a copper seed layer from an electrolyte composed of CuSO₄, H₂SO₄, deionized water, and thiourea was investigated. Even in the presence of very low concentrations of thiourea, extremely smooth and bright copper deposits were obtained. From the results of X-ray photoelectron spectroscopy, Auger electron spectroscopy, and electrochemical analyses, thiourea was found to react with copper or copper ions leading to the generation of CuS. CuS adsorption onto the copper seed layer seemed to inhibit the initial nucleation of the copper adions, resulting in the formation of smaller Cu grains compared to those forming in the absence of thiourea. CuS was observed to cover all active sites of the 1 cm² copper seed layer above 0.017 g/L thiourea. The surface roughness as well as the mean grain size of the deposits also approached minimum values above this thiourea concentration. Adsorbed CuS was incorporated into the deposits during electroplating, which was believed to be the major factor for the increased resistivity of the deposits.     

2-(2-羟基-5-磺酸基苯基)苯并三唑紫外线吸收剂的合成及应用

以邻硝基苯胺为重氮组分、对羟基苯磺酸为偶合组分,合成邻位含有硝基的偶氮化合物中间体,再利用二氧化硫脲将此中间体还原,制得一种水溶性紫外线吸收剂2-(2-羟基-5-磺酸基苯基)苯并三唑。将该紫外线吸收剂应用于羊毛织物上,并优化上染工艺。研究发现,pH值和紫外线吸收剂的用量对上染率影响较大,处理后的羊毛织物具有较好的紫外线防护效果。     

A kinetic study of the reduction of chromium(VI) to chromium(III) by thiourea

The reduction of chromium(VI) to chromium(III) by thiourea is a key aspect of the chromium(VI)–thiourea–polyacrylamide gel polymer system used in oil recovery processes. A study was undertaken to develop a kinetic model for the reduction reaction. Reaction mixtures were prepared and chromium(VI) concentrations were determined from the mixtures's visible absorbance. The reaction rate was found to depend on the concentrations of chromium(VI), thiourea, and polyacrylamide and on solution pH. A kinetic model for the reactions was developed using the experimental data and previously proposed reaction mechanisms. The model accurately predicts the reaction rate in solutions that do not contain polyacrylamide and predicts a rate that is approximately correct for solutions containing polyacrylamide.     

论氧气法制胍衍生物的化学反应

通过对硫脲衍生物分子化学键的研究，发现了氧气法不仅适用于生产二苯胍，还适用于生产其他胍衍生物。就是说，硫脲衍生物可以通过氧气法制成相应的胍衍生物。氧气法生产胍衍生物的化学反应过程中，铜离子的催化作用发生在硫脲衍生物与氧气进行反应生成二氧化硫脲衍生物的反应阶段。铜离子的催化作用表现为消除硫脲衍生物分子母体的共轭π键，使硫基π键孤离出来，并使硫基极化。本文讨论硫脲衍生物分子母体的化学键及其变化，叙述氧气法制胍衍生物的化学反应。     

SA_2－GD调剖剂的研究及应用

ＳＡ２－ＧＤ是以硫脲－铬盐氧化还原体系交联聚丙烯酰胺而形成的冻胶型调剖剂。本文研究了ＳＡ２－ＧＤ各组分浓度与调剖剂性能的关系．考察了ｐＨ值、温度、铁离子、地层砂和地层水对ＳＡ２－ＧＤ调剖剂性能的影响，介绍了该调剖剂的现场应用情况。ＳＡ２－ＧＤ调剖剂成胶时间长且可调，形成的冻胶强度大，封堵能力强。     

Fabrication of three-dimensional Cu/Ni multilayered microstructure by wet process

Three-dimensional (3D) microstructures were formed using a wet process consisting of the formation of a multilayered microstructure and selective etching of the other layers of the structure. Cylindric Cu/Ni multilayered microstructures of 50 μm in diameter and 30 μm in height were formed by electroplating and photolithography. Cu layers were then etched selectively in acidic thiourea solution. The redox reaction of the multilayered microstructure in the solution was investigated electrochemically. The shapes of three-dimensional microstructures were affected by the surface morphology of the deposited films. Various three-dimensional microstructures having controlled geometric unevenness were obtained using films having smooth surface morphology.     

硫脲对脲酶活性和尿素氮转化的试验初报

本试验研究了硫脲(TU,0.1%,0.3%,0.5%,1.0%,5.0%)不同浓度对土壤脲酶活性、土壤尿素氮转化的影响。室内培养表明,硫脲既是一种弱脲酶抑制剂又是一种硝化抑制剂。硫脲对脲酶活性和尿素水解均有显著的抑制作用,但是作用时间较短;硫脲用量为0.1%时,就起到了抑制作用,用量0.3%～1.0%之间差异不显著,用量1.0%～5.0%之间抑制效果随用量增加而加强。硫脲不仅延缓了土壤NH4 -N的释放高峰期一周,而且降低了土壤中NO3--N的富集,使NO3--N的释放高峰期向后推迟了10天。本试验条件下,土壤中的NH4 -N向NO3--N转化的时间大约为7～10天;土壤中有效氮的释放曲线主要取决于土壤NH4 -N的浓度,受NO3--N的影响次之。