差热法快速测定钢中氧化夹杂的初探

利用TC -4 3 6氮氧仪的程序升温功能 ,研究了一系列光谱纯氧化物试剂Fe2 O3,MnO2 ,NiO ,CuO ,SiO2 ,Al2 O3以及稀土氧化物La2 O3,CeO2 等的氧释放曲线 ;每种氧化物在给定条件下 ,以跟踪式升温方式受热释放氧 ,得到了分解温度、分解电流和分解功率。发现不同氧化物分解温度由低到高的顺序为 :CuO <Fe2 O3<NiO <MnO2 <SiO2 <Al2 O3。研究了脱氧纯铁与SiO2 或Al2 O3混合物的氧状态分析图 ,模拟钢中夹杂的化学行为。以纯氧化物为参照 ,做了不同钢种中的氧化物夹杂的氧状态分析 ,指认了钢中Al系氧化物夹杂的分解峰 。

多功能生物催化剂——卤醇脱卤酶的研究进展

光学纯的环氧化物及β-取代醇是一类高价值中间体,在手性药物及精细化工合成领域具有十分重要的应用前景。卤醇脱卤酶是一类通过分子内亲核取代机制催化邻卤醇转化为环氧化物的脱卤酶,可以高效高选择地催化环氧化物和邻卤醇之间的转化,因而可以用来合成具有光学纯的环氧化物及β-取代醇等化合物。本文着重介绍了卤醇脱卤酶的催化机理及其应用研究进展,并对研究的发展方向提出了一些设想。

热处理气氛和温度对SnO_2∶Sb超细粉的影响

以SnCl4·5H2O和SbCl3为原料,采用共沉淀法分别制得了纳米级的SnO2∶Sb,Sb2O3和SnO2超细粉,并选取工业用Sb2O3粉末作为参比,运用X射线衍射(XRD)、Leitz多功能显微镜、电阻测试等测试方法对粉末进行了表征,比较系统地研究了热处理气氛和温度对粉末物相和电阻的影响。

Electrochemical hydrogen compression and purification versus competing technologies: Part Ⅱ. Challenges in electrocatalysis

Hydrogen will be at the basis of the World’s energy policy in forthcoming decades, owing to its decarbonized nature, at least when produced from renewables. For now, hydrogen is still essentially produced from fossil feedstock(and to a minor extent from biomass);in consequence the present hydrogen gas on the market is containing non-negligible amounts of impurities that prevent its immediate usage in specialty chemistry or as an energy carrier in fuel cells, e.g. in transportation applications(cars, buses, trains, boats, etc.) that gradually spread on the planet. For these purposes, hydrogen must be of sufficient purity but also sufficiently compressed(at high pressures, typically 70 MPa), rendering purification and compression steps unavoidable in the hydrogen cycle. As shown in the first part of this contribution "Electrochemical hydrogen compression and purification versus competing technologies: Part I. pros and cons", electrochemical hydrogen compressors(EHCs), which enable both hydrogen purification and compression, exhibit many theoretical(thermodynamic) and practical(kinetics) advantages over their mechanical counterparts. However, in order to be competitive, EHCs must operate in very intensive conditions(high current density and low cell voltage) that can only be reached if their core materials, e.g. the membrane and the electrodes/electrocatalysts, are optimized. This contribution will particularly focus on the properties electrocatalysts must exhibit to be used in EHCs: they shall promote(very) fast hydrogen oxidation reaction(HOR) in presence of impurities, which implies that they are(very) tolerant to poisons as well. This consists of a prerequisite for the operation of the anode of an EHC used for the purification-compression of hydrogen, and the materials developed for poison-tolerance in the vast literature on low-temperature fuel cells, may not always satisfy these two criteria, as this contribution will review.

Purification and characterization of manganese peroxidases from native and mutant Trametes versicolor IBL-04

Extracellular manganese peroxidases （MnPs） produced by native and mutant strains of Trametes versicolor IBL‐04 （EB‐60, EMS‐90） were purified by ammonium sulphate precipitation and dialysis, followed by ion‐exchange and gel‐permeation chromatography. The purified enzymes elucidated a single band in the 43‐kDa region on sodium dodecyl sulphate‐polyacrylamide gel electrophoresis. The optimum pH and temperature of the purified enzymes were found to be 5.0 and 40 °C, respec‐tively. Mutant strain MnPs exhibited a broader active pH range and higher thermal stability than native MnP. Purified MnPs from selected mutants showed almost identical properties to native MnP in electrophoresis, steady‐state kinetics, and metal ion and endocrine‐disrupting compound （EDC） degradation efficiency. Although the fastest reaction rates occurred with Mn2＋, MnPs displayed the highest affinity for ABTS, methoxyhydroquinone, 4‐aminophenol and reactive dyes. MnP activity was significantly enhanced by Mn2＋and Cu2＋, and inhibited in the presence of Zn2＋, Fe2＋, ethylene‐diaminetetraacetic acid and cysteine to various extents, with Hg2＋ as the most potent inhibitory agent. MnPs from all sources efficiently catalyzed the degradation of the EDCs, nonylphenol and triclosan, removing over 80%after 3 h of treatment, which was further increased up to 90%in the presence of MnP‐mediator system. The properties of T. versicolor MnPs, such as high pH and ther‐mal stability, as well as unique Michaelis‐Menten kinetic parameters and high EDC elimination effi‐ciency, render them promising candidates for industrial exploitation.

Separation and Purification of Tobacco Peroxidase I from Nicotiana Tobaccum

A new isoenzyme of tobacco peroxidase(TOP) I was purified from tobacco (K326) by using acetone powder, ammonium sulfate precipitation and column chromatography on DEAE-52 cellulose, Sephadex G-75 and DEAE-Sephadex A-50. It is an iron-protein containing haemachrome, whose molecular weight is 21888.5 and the isoelectric point is 3.5. The optimum pH value and temperature of this enzyme is 6.0 and 45℃respectively. The enzyme is stable in the pH range from 3.0 to 10.0 and has a favorable thermostability.

Preparation of Arsenic Oxide and High Purity Ultrafine Antimony Compounds from Flue Dust Containing Arsenic and Antimony

A new hydrometallurgical process of chlorination-distillation at low temperatures about 100 °C was developed for recovery of valuable metal and environmental protection. This process was used to treat flue dust containing arsenic and antimony and satisfactory results were obtained. Over 99% of arsenic and antimony were recovered, and high purity As2O3 and SbCl3 were produced. A metallic alcoholate technique was developed and proved to be of significant to the utilization of antimony resources. Using this technique, a number of antimony oxide powders were prepared, such as high purity and ultrafine Sb2O3, ultrafine Sb2O3-Sb2O5 and Sb2O3-SnO2 composite powders.

Purification and Characterization of Plant Peroxidase from Coccinia Grandis （Ivy Gourd）

Plant peroxidase extracted from Coccinia grandis Lin. （Ivy gourd） was purified from crude extract by ammonium sulfate precipitation, ion-exchange chromatography, and size exclusion chromatography. The purified enzyme preparation exhibited a specific activity of 6106.63 p.mol.minl.mg protein1, while purification fold and yield were 17.45 and 34.70%, respectively. The purified peroxidase was homogenous as judged by native and sodium dodecyl sulfate （SDS） polyacrylamide gel electrophoresis. The molecular weight as determined by gel filtration and SDS-polyacrylamide gel electrophoresis was 45 kD, which suggested that the purified peroxidase contained only one subunit. The apparent Km and Vmax values of the enzyme against phenol were 93 p.M and 561 μmol.min^-1.mg protein^-1, respectively. The temperature and pH optimum for purified peroxidase were 45℃ and pH 6.0, respective. However, it was stable at 30-60℃ and pH 4.0-8.0. The presence of metal ions such as Cu2＋ and Ca2＋ enhanced peroxidase activity. On the other hand, Cr3＋ and Hg2＋ strongly inhibited the enzyme activity at 500 p.M. Sodium dodecyl sulfate reduced a half of peroxidase activity at approximately 3 mM. Ivy gourd was stability in the presence of each urea concentrations. The affinity of the enzyme with different substrates showed as the highest relative activities on gallic acid followed by catechin, ascorbic acid and caffeic acid, respectively.