Pb, Cu和Zn在自然水体生物膜中铁/锰氧化物等组分上的富集规律

用选择性萃取法萃取天然基质采集的生物膜中的铁/锰氧化物, 考察生物膜上铁/锰氧化物对水体中Pb, Cu及Zn的富集作用. 结果表明, 锰氧化物对生物膜富集Pb起主要作用, 而铁氧化物和除铁/锰氧化物以外的以有机质为主的其它组分的作用很小; 膜上其它组分对Cu的富集贡献较大, 锰氧化物的贡献与铁氧化物的接近; 锰氧化物对Zn的富集贡献最大, 铁氧化物和其它组分的贡献比较接近. 锰氧化物对Pb, Cu及Zn的富集能力分别高于铁氧化物的富集能力, 铁氧化物和锰氧化物对3种金属富集能力的大小顺序分别是Zn>Cu>Pb和Zn>Pb≥Cu.     

自然水体中生物膜的主要化学组分与水体中相关化学物质的关系

自然水体中大多数微生物是以附着状态而不是以游离状态存在的 [1] .微生物附着在固体表面形成生物膜 ,存在于河流、湖泊及湿地环境中的岩石、表层沉积物和悬浮颗粒物表面 ,由不同种类的微生物组成 [2 ] .从环境微生物学角度来看 ,生物膜被定义为一种活跃地生长发育着的单一或混合的微生物群体 ,其不可逆地附着到一种活跃的或非活跃的表面 [3] ,并由微生物群体组成 [4 ] .从环境化学角度来看 ,生物膜是由金属氧化物、有机质及少量矿物质组成的 .金属氧化物和有机质在影响重金属于固相吸附的相对作用已有报道 [5～ 10 ] .生物膜在自然水体中是…     

Lead and Cadmium Adsorption onto Iron Oxides and Manganese Oxides in the Natural Surface Coatings Collected on Natural Substances in the Songhua River of China

Natural surface coatings collected from natural substances(NSCsNS)were employed to study the roles of the main chemical components(iron oxides,manganese oxides,and other components)in controlling the adsorption of lead(Pb)and cadmium(Cd)in aquatic environments.The selective chemical extraction followed by the adsorption of Pb and Cd experiments and statistical analysis,were used to investigate the adsorption property of each component.Hydroxylamine hydrochloride was used to remove manganese oxides selectively,and sodium dithionite was used to extract iron oxides and manganese oxides.The result indicated that iron oxides and manganese oxides played an important role in the adsorption of Pb and Cd on NSCsNS,and the relative contribution was about two-thirds.The contribution of manganese oxides was the greatest,with a lesser role indicated for other components.The adsorption ability of manganese oxides for Pb and Cd was greater than that of iron oxides or other components for Pb and Cd.The Pb adsorption observed in each component was greater than Cd adsorption.     

介孔材料离子导电性的研究

介孔材料由于其奇特的性质和广泛的应用成为人们研究的热点。本文介绍了近几年来介孔材料质子和锂离子导电性的研究现状和发展趋势,主要总结了介孔纯氧化物、介孔纯氧化物的孔内修饰、介孔氧化物的孔壁掺杂修饰、介孔氧化物薄膜、介孔材料与有机高分子复合膜的离子导电性的研究进展。     

Studies of non-stoichiometric oxides by thermoanalytical methods

Non-stoichiometric oxides can be divided into metal-deficient and oxygen-deficient oxides, and a few examples of each type are given in order to show the materials of interest in this field. After a short review of the methods used in the study of these oxides, an account is given of the methods used in and the results obtained from a recent thermogravimetric investigation in atmospheres of controlled oxygen pressure on cerium oxides, plutonium oxides and mixed uranium plutonium oxides, which are all of special interest in research on fuels for nuclear power reactors.     

Reduction of phosphine oxides to phosphines

The digest is devoted to the most widespread reducing agents which are used for the reduction of tertiary and secondary phosphine oxides, phospholene oxides, phospholane oxides, phosphonates, phosphinates, α- and β-hydroxy and thiomethyl phosphine oxides, α-aminophosphine oxides. Stereoselectivity of reactions is described. Methods of stabilization of phosphines which are prone to re-oxidation by the formation of borane-adduct or metal complexes are considered.     

用于消除挥发性有机物的有序多孔金属氧化物催化剂的研究进展

综述了近年来国内外用于消除挥发性有机物的有序多孔金属氧化物催化剂的研究进展, 主要包括有序多孔氧化铈、 氧化锰、 氧化钴、 氧化铁、 氧化铬和钙钛矿型氧化物及其负载贵金属或过渡金属氧化物. 讨论了这些催化剂对典型挥发性有机物氧化的催化性能, 并展望了新型高效消除挥发性有机物催化剂的研发前景及技术发展趋势.     

Estimation of metallic iron in rusted sponge-iron: Dissolution of iron oxides by bromine/methanol

The extent to which a number of iron oxides dissolved in cold and hot 5% bromine/methanol reagent was examined during analysis for metallic iron in the presence of oxides found in partially-rusted sponge-iron. At room temperature there was only slight attack on the oxides, but at the reflux temperature of the lixiviant and over a period of 2 hr, both the oxyhydroxides and oxides were attacked, the oxyhydroxides considerably and the other oxides slightly.     

铁、锰氧化物在自然水体生物膜上的分布

在自然水体中 ,生物膜是一个开放的动力学系统 ,生物膜的形成及其组分处于动态的变化中——水环境中的各种成分在生物膜上发生着合成、聚结、转化、降解等作用 ,从而成为生物膜的一部分 ,还会随着生物膜的脱落重新进入水相中 ,所有这些变化 ,与生物膜本身的性质是分不开的 [1～ 3] 。从环境化学角度看 ,自然水体中生物膜主要化学组分包括金属氧化物 (铁氧化物、锰氧化物和铝氧化物等 )、有机质及少量的矿物质 ,其中 ,铁、锰氧化物在影响痕量重金属在水环境中的迁移、最终归宿、生物地球化学特性、生物可利用性和毒性过程中起着非常重要的作…     

稀土处理钢用中间包覆盖剂岩相分析

分析了现场覆盖剂和实验室自配覆盖剂岩相结构，探讨了稀土氧化物在覆盖剂中的赋存状态。结果表明：在本实验条件下的覆盖剂，原渣矿物组成主要是黄长石，另有少量镁橄榄石和含铁的硅酸盐；稀土氧化物在覆盖剂中主要以稀土硅酸盐形式存在；当稀土氧化物含量增加到一定数量时，覆盖剂开始出现固态未溶的稀土氧化物，说明其在覆盖剂中有一定的溶解度；稀土氧化物在覆盖剂中可以部分代替CaO，形成稀土硅酸盐，其形成物种类随覆盖剂碱度降低有增加的趋势。     

IR spectra of manganese oxides with either layered or tunnel structures

Four kinds of manganese oxides with either layered or tunnel structures were prepared by different methods. The structural features of the prepared materials were characterized by power X-ray diffraction, IR spectra and SEM observation. A compare analysis of IR spectra for these materials before and after the acid treatment was carried out. Band around 761 cm(-1) could be assigned to a characteristic adsorbent band of tunnel-type manganese oxides; while it was not observed in layer-type manganese oxides. After the acid treatment, the position and relative intensity of the bands in 300-1200 cm(-1) region showed an obvious change for layered manganese oxides in compare with tunnel-type manganese oxides. The variation of IR spectra could be used to distinguish layered manganese oxides from tunnel manganese oxides.     

钼铈氧化物体系的程序升温还原与还原动力学

运用X射线衍射、红外光谱、热重分析和比表面积测定等方法剖析了钼、铈氧化物的程序升温还原过程。结果表明，金属离子间的相互作用使得氧化物还原反应的活化能降低，有利于其催化性能的提高。     

Novel transition-metal-free heterogeneous epoxidation catalysts discovered by means of high-throughput experimentation

Various transition-metal-free oxides have been studied as catalysts for the epoxidation of cyclooctene with hydrogen peroxide by means of high-throughput experimentation. Different boron, aluminium, and gallium oxides were prepared according to various synthesis methods. A number of pure aluminium and gallium oxides showed very good catalytic performances, while the results obtained with boron oxides or mixed oxides were less positive. The best results were obtained with a gallium oxide catalyst, which gave an epoxide yield of 71 % and a selectivity of 99 % after reaction for 4 h at 80 degrees C. Gallium oxides had not been reported previously as active epoxidation catalysts. The use of high-throughput experimentation proved useful both for discovering new active catalysts and for identifying a number of relationships between the synthesis conditions and the catalytic properties of the transition-metal-free oxides.     

Metal-oxide surfaces

Over the past two decades the amount of effort devoted to the study of metal oxides by surface scientists has increased significantly. The general characteristics of the electronic structure of metal-oxide surfaces are now fairly well understood, although transition-metal oxides have been more thoroughly studied than have non-transition-metal oxides. The geometric arrangement of atoms on the surfaces of a variety of metal oxides has also been determined. Extensive studies have been performed of the interaction of both molecules and metal atoms with metal oxides, where point defects are found to play a dominant role. However, our understanding of the surface properties of metal oxides is still much less compete than it is for metals and semiconductors, and there are several areas where more experimental and theoretical effort needs to be concentrated.     

Transition Metal Oxides for the Oxygen Reduction Reaction: Influence of the Oxidation States of the Metal and its Position on the Periodic Table

Electrocatalysts have been developed to meet the needs and requirements of renewable energy applications. Metal oxides have been well explored and are promising for this purpose, however, many reports focus on only one or a few metal oxides at once. Herein, thirty metal oxides, which were either commercially available or synthesized by a simple and scalable method, were screened for comparison with regards to their electrocatalytic activity towards the oxygen reduction reaction (ORR). We show that although manganese, iron, cobalt, and nickel oxides generally displayed the ability to enhance the kinetics of oxygen reduction under alkaline conditions compared with bare glassy carbon, there is no significant correlation between the position of a metal on the periodic table and the electrocatalytic performance of its respective metal oxides. Moreover, it was also observed that mixed valent (+2, +3) oxides performed the poorest, compared with their respective pure metal oxides. These findings may be of paramount importance in the field of renewable energy.     

Influence of soaking duration on the selective oxidation and galvanizability of a high‐strength dual phase steel

High‐strength dual phase steels readily exhibit bad galvanizability and coating defects because of selective oxides formed on steel surface during the annealing process prior to galvanizing. To investigate selective oxidation of alloying elements and their effects on glavanizability, a high‐strength dual phase steel was annealed with soaking duration for 45, 90, and 120 s, respectively, and then galvanized using a hot‐dip simulator. Field‐emission scanning electron microscopy characterization revealed that when dual phase steel was soaked for 45 s, selective oxides mainly precipitated along grain boundaries, while only a few of the oxides formed on grains. With soaking duration increased, oxides were so dense that nearly all steel surface was covered, leaving little bare area of the steel surface. Further XPS analysis showed that selective oxides mainly consisted of MnO and Cr₂O₃. In addition, the chemical nature of oxides did not change at all although soaking duration prolonged. Scanning Auger microprobe depth profiles presented that Mn had a much higher tendency to segregate than Cr and Mo. Oxygen penetration depth to subsurface was promoted as soaking duration increased. The formation of interfacial inhibition layer was founded to be greatly influenced by the density and size of surface oxides. The widely spaced small oxides had virtually no adverse effect on wettability because of aluminothermic reduction of oxides by the bath dissolved Al. As the oxides became dense and considerably big, the grains of the inhibition layer in some certain zones became coarse and the galvanizability tended to deteriorate. Copyright © 2011 John Wiley & Sons, Ltd.     

Effects of the substituents on the reactivity of carbonyl oxides. A theoretical study on the reaction of substituted carbonyl oxides with water

The reactions between fifteen carbonyl oxides and water have been investigated with the aim of contributing to a better understanding of the effects of the substituents in the reactivity of carbonyl oxides. We have employed density functional theory and large scale ab initio methods (CCSD(T), CASSCF, and CASPT2), combined with transition state theory, to investigate the addition of water to carbonyl oxide and, for those carbonyl oxides having a methyl substituent in syn, the hydrogen transfer from the methyl group to the terminal oxygen of carbonyl oxide. In this case, the water acts as a catalyst and this reaction can contribute to the atmospheric formation of a hydroxyl radical. Carbonyl oxides with electron withdrawing substituents and zwitterionic character have low energy barriers and react fast, whereas carbonyl oxides with electron releasing substituents have high energy barriers and react slowly. The position of the substituents plays also an important role and carbonyl oxides having a hydrogen atom substituent in syn react faster than carbonyl oxides having a hydrogen atom substituent in anti. The differences in the reactivity of different substituted carbonyl oxides raise up to ten orders of magnitude and the branching ratios for the two different reactions investigated are also reported.     

Base-mediated cyclization reaction of 2-alkynylphenylphosphine oxides: synthesis and photophysical properties of benzo[b]phosphole oxides

The base-mediated intramolecular cyclization reaction of 2-alkynylphenylphosphine oxides affords benzo[ b]phosphole oxides, which show intense blue-green fluorescence. Benzo[ b]phospholes are also prepared by the reduction of benzo[ b]phosphole oxides.     

费-托合成Co/ZrO2-Al2O3催化剂反应性能的研究

以ZrOCl2·6H2O和AlCl3为原料，采用共沉淀方法制得一系列不同ZrO2质量分数的ZrO2-Al2O3混合氧化物载体；并以该混合氧化物为载体，采用初湿浸渍法制得钴质量分数为12％的Co/ZrO2-Al2O3催化剂。XRD、NH3-TPD、TPR和原位IR等表征结果表明，随着混合载体中ZrO2质量分数的增加，载体比表面积先增加后减少，混合载体的平均孔径则小于单一氧化物ZrO2和Al2O3的平均孔径。ZrO2和Al2O3载体混合后会导致氧化物的比表面积和酸性增大并且有新的物相生成。当混合氧化物用作载体时，能够抑制载体表面金属钴的分散，改变催化剂的还原行为，降低催化剂对CO物种的吸附能力。CO加氢反应表明，与单一金属氧化物相比，钴负载ZrO2-Al2O3混合氧化物催化剂的加氢活性和重质烃选择性有所降低。     

Evaluation of bifunctional chiral phosphine oxide catalysts for the asymmetric hydrosilylation of ketimines

A series of bifunctional phosphine oxides have been prepared and evaluated as catalysts for the trichlorosilane mediated asymmetric hydrosilylation of ketimines. bis-Phosphine oxides, hydroxy-phosphine oxides, and biaryl phosphine oxides all demonstrated good catalytic activity, but poor to moderate enantioselectivity. A bis-P-chiral phosphine oxide displayed the highest enantioselectivity of 60%.