Heat transport cycle with methyl alcohol-acetaldehyde chemical reaction

The exothermic reaction of acetaldehyde and methyl alcohol is suggested as a candidate for energy transport and upgrading. A temperature rise of up to 50°C could be obtained for this system. A lower heat source could also be upgraded by using two distillation columns working at different pressures; thus a low level heat source at 60°C could be delivered to a consumer centre at 70°C by this method.     

溴甲烷防除烟草苗床杂草研究

作者在云南省12个县（市），进行溴甲烷熏蒸烟草苗床防除杂草试验，结果表明：在烟草出苗前和出苗期，各处理对单、双子叶杂草防效分别为100％，94.7％～97.4％。在烟苗小十字期和五真时期，40～80g／m~2剂量对单、双子叶杂草防效分别为93.0％～96.8％、91.3％～94.3％；20g／m~2剂量对单、双子叶杂草防效较低，分别为86.8％～87.8％、81.5％～89.1％。各处理对烟草种子及烟苗安全，能间接促进烟草生长，处理区烟苗茎叶粗大，根系发达，烟苗单株茎叶鲜、干重分别比对照增1.27～1.375g、0.1～0.105g，侧根数比对照增10.4～14.7条，根鲜、干重分别比对照增0.038～0.071g、0.0083～0.01g，第五真叶长×宽比对照增1.l～2.3×1.8～1.9cm。认为40～60g/m~2剂量处理有效合理。     

The spontaneous polymerization of methyl methacrylate: 6. Polymerization in solution: participation of transfer agents in the initiation reaction

The rate of the spontaneous polymerization of methyl methacrylate is strongly affected by the addition of transfer agents. The kinetics are interpreted in terms of a participation of transfer agents in the initiation step. In this, the original biradical, .M₂., which is produced from two monomer molecules and which has a high self-termination probability, is converted into polymerizable monoradicals. Increase in the concentration of a strong transfer agent leads to double-transferred compound HH1, the mass spectral identification of which is to be regarded as first direct evidence for the existence of biradical .M₂..     

用化学读出方法测量的FX-L型缬氨酸自由基剂量计

本文提出了一种用20mgL 型缬氨酸溶于10mlFx 溶液构成的 Fx-L 型缬氨酸自由基剂量计。缬氨酸经辐射产生的自由基数量通过分光光度计测量剂量计的光密度来确定。它的测量范围为50Gy—10kGy;当贮藏温度为10—37℃,在近一年时间内,剂量响应的变化不超过5%;它是一种较为简单、精确、适于辐射加工中高剂量测量的剂量计。     

Mechanism for the catalytic exchange of methane with deuterium on Pt(111) surfaces

The reaction of methane with deuterium on Pt(111) single crystals was studied using thermal programmed desorption (TPD) under ultra-high vacuum conditions. Methyl groups, believed to result from the dissociative adsorption of methane under catalytic conditions, were deposited directly by thermal decomposition of methyl iodide. TPD experiments after coadsorption with deuterium show that methane formation occurs in very high yields. Furthermore, the desorbing molecules display a bimodal distribution very similar to that obtained under atmospheric pressures, with maxima for CH₃D and CD₄. This distribution can be explained by a competition between two surface reactions, namely, direct incorporation of hydrogen in methyl groups and methylene formation followed by rapid interconversion to methylidyne before final hydrogenation to methane. We found that the rates for both reactions depend linearly on the coverage of methyl groups, but while the hydrogenation rate is also proportional to the coverage of deuterium, in the case of multiple H-D exchange an almost zero order dependence at low temperatures slowly becomes first order as the reaction temperature is increased. The activation energies for CH₃D and CD₄ formation were estimated to be 17.0 and 6.5 kcal/mol respectively even though the reaction rates displayed comparable values because of a compensation effect in the preexponential factors. Finally, the relative yields for CH₂D₂, CHD₃ and CD₄ are close to the equilibrium values, a result that is consistent with the proposed methylene-methylidyne interconversion step in our mechanism.     

MMA聚合物稀溶液的粘数测定及其动能改正

国际标准化组织(ISO)规定了甲基丙烯酸甲酯聚合物模塑和挤出材料的稀溶液粘数的测定。它适用于甲基丙烯酸甲酯的均聚物、共聚物以及含有低至80％MMA和高至20％其它单体的两者共混物。经验证明,为了获得准确的结果,动能改正是必要的。为此,已知运动粘度的4种校准液体用于粘数测定。     

甲乙酮生产技术及国内市场分析

介绍了甲乙酮的生产方法，分析了国内甲乙酮的生产现状和市场情况，提出了我国甲乙酮今后发展的建议。     

The copolymerization of methyl methacrylate and isoprene in the presence of ethyl aluminium sesquichloride: role of monomer complexes

The kinetics of the spontaneous copolymerization of methyl methacrylate and isoprene in the presence of ethyl aluminium sesquichloride in toluene and at temperatures between 0° and 40°C have been investigated. Irreproducible fast initial rates of copolymerization are followed by slower reproducible rates. The structures of the copolymer and the accompanying Diels-Alder adduct have been determined by ¹H and ¹³C n.m.r.; the copolymers produced under a wide range of conditions are equimolar and highly alternating. The concentrations of various binary and ternary complexes have been assessed through ¹H n.m.r. chemical shift measurements; it is shown that the mechanism of copolymerization cannot involve simply the effective homopolymerization of ternary isoprene-methyl methacrylate-ethyl aluminium sesquichloride complexes.     

Effects of activated carbon characteristics on the simultaneous adsorption of aqueous organic micropollutants and natural organic matter

The overall objective of this research was to determine the effects of physical and chemical activated carbon characteristics on the simultaneous adsorption of trace organic contaminants and natural organic matter (NOM). A matrix of 12 activated carbon fibers (ACFs) with three activation levels and four surface chemistry levels (acid-washed, oxidized, hydrogen-treated, and ammonia-treated) was studied to systematically evaluate pore structure and surface chemistry phenomena. Also, three commercially available granular activated carbons (GACs) were tested. The relatively hydrophilic fuel additive methyl tertiary-butyl ether (MTBE) and the relatively hydrophobic solvent trichloroethene (TCE) served as micropollutant probes. A comparison of adsorption isotherm data collected in the presence and absence of NOM showed that percent reductions of single-solute TCE and MTBE adsorption capacities that resulted from the presence of co-adsorbing NOM were not strongly affected by the chemical characteristics of activated carbons. However, hydrophobic carbons were more effective adsorbents for both TCE and MTBE than hydrophilic carbons because enhanced water adsorption on the latter interfered with the adsorption of micropollutants from solutions containing NOM. With respect to pore structure, activated carbons should exhibit a large volume of micropores with widths that are about 1.5 times the kinetic diameter of the target adsorbate. Furthermore, an effective adsorbent should possess a micropore size distribution that extends to widths that are approximately twice the kinetic diameter of the target adsorbate to prevent pore blockage/constriction as a result of NOM adsorption.     

复合催化剂TiO2/Fe2O3的制备及其光催化性能

以Fe2O3和TiCl4为原料,通过水解法制备Fe2O3/TiO2包覆型复合光催化剂,并用XRD、SEM进行表征。以甲基橙为模型污染物,比较了Fe2O3、TiO2和TiO2/Fe2O3的光催化活性,确定了Fe2O3和TiO2的最佳配比,同时探讨了反应机理。