Iron speciation related to color of Jurassic sedimentary rocks in Turpan Basin, northwest China

Mesozoic-Cenozoic reddish and green beds are widely distributed in northwest China. Mössbauer spectroscopy revealed that the composition of iron species varies with color in the middle-upper Jurassic sedimentary rocks from the Turpan Basin. Three main kinds of iron species were identified: (1) ferric iron of hematite (hem-Fe³⁺), (2) paramagnetic ferric iron (para-Fe³⁺), and (3) paramagnetic ferrous iron (para-Fe²⁺). Pyrite iron (pyr-Fe²⁺) was revealed only in a few samples. In general, there is a direct correlation between rock color, iron species and total iron content, however, in detail, this relationship is more complicated. The reddish rocks contain higher contents of total iron and hem-Fe³⁺, whereas the gray rocks contain much more para-Fe²⁺. However, relatively low hematite content cannot give red color to rocks, probably due to suppression by other pigments such as organic matter in black or chlorite in green. The dark or green rocks normally contain either only paramagnetic Fe²⁺ and paramagnetic Fe³⁺ species or these two species associated with hematite Fe³⁺, but the relative content of hematite species is lower. The variations of different iron species control lithological properties such as color and also may reflect the sedimentary conditions. Moreover, iron speciation in these rocks is one of the main factors, which result the color features of rocks in remote sensing imagery.This revised version was published online in November 2005 with corrections to the Cover Date.     

掺杂SrTiO3体系上甲烷氧化偶联反应的研究—活性氧物种的作用

本文采用循环氧化还原法,脉冲反应及TPD等实验手段对钙钛矿型氧化物掺杂SrTiO_3体系上甲烷氧化偶联反应中的活性氧物种的作用进行了研究.结果表明,催化剂由于掺杂产生的未被充分还原的氧物种(O~(α-)(0<α<2)是活化甲烷并促使其发生偶联反应的主要的活性中心,而表面晶格氧(O_L~(2-))则主要使甲烷深度氧化;消耗掉的未被充分还原的氧或晶格氧可以在高温下氧气氛中氧化复原.对于掺杂的SrTiO_3样品,体相中的氧在惰性气氛或还原气氛中可以向表面扩散.吸附氧可能不直接与甲烷作用而主要通过催化剂表面活性氧物种(O~(α-)或O_L~(2-))而起作用.     

三七水溶性化学成分及其药理研究新进展

综述了近年来三七水溶性化学成分及其药理作用特别是对神经生理活性研究的进展，对三七与人参展其它植物植物进行了比较，阐明了三七所含多肽哆肽成分研究的意义及可行性。     

氧化铝/碳纳米管复合材料的制备及表征

采用聚乙烯醇对碳纳米管表面进行改性，通过化学沉淀法将Al(OH)₃均匀沉积在碳纳米管表面，然后在氮气气氛下于500 ℃煅烧2 h，制备出氧化铝/碳纳米管复合材料。采用TEM、TG、DTA、XRD、IR、氮吸附脱附(比表面积及孔结构分析)等对氧化铝/碳纳米管复合材料进行表征，结果表明:未经聚乙烯醇改性的碳纳米管，氧化铝与碳纳米管相互分离;经聚乙烯醇改性的碳纳米管，氧化铝与碳纳米管结合良好。经聚乙烯醇改性的碳纳米管表面均匀覆盖一层聚乙烯醇膜，通过聚乙烯醇的吸附作用， Al(OH)₃沉积在碳纳米管表面形成一层连续的覆盖层。     

非弹性体增韧—聚合物增韧的新途径

本文是一篇关于非弹性增韧方法的综述。文章首先简要回顾了传统的橡胶增韧韧性聚合物材料的机理,然后着重介绍了最近在国外出现的刚性有机填料(ROF)增韧的基本概念、分析方法和增韧的冷拉机理,列举了脆性塑料粒子和韧性基体组成的合金体系的大量实验结果来说明以上内容,最后通过与传统橡胶增韧机理的对比指出非弹性体增韧是不同于后者的一种新增韧方法,并有可能成为制备高强度、高韧性工程塑料的一种新途径。     

A novel three-dimensional coordination polymer [Cd2(C3H2O4)2(H2O)2(μ 2-hmt)] n (hmt = hexamethylenetetramine): synthesis and crystal structure

The self-assembly of the Cd^II ion, hexamethylenetetramine (hmt) and malonate ligand yields a three-dimensional (3D) coordination polymer [Cd₂(C₃H₂O₄)₂(H₂O)₂( ₂-hmt)] _n with channels. The Cd^II ion is located in a octahedral coordination environment, composed of four oxygen atoms from three malonates, one oxygen atom of water and one nitrogen atom of hmt. Two oxygen atoms of each malonate coordinate to the same Cd^II ion and the other two oxygen atoms connect to adjacent two Cd^II ions respectively to form a two-dimensional infinite network, these networks are bridged by ₂-hmt coordinated to Cd^II ions to product a 3D architecture.     

Crystal Structure and Characterization of a Large Polyoxotungstate (NH4)21{La(H2O)5[Ni(H2O)]2As4W40O140}·53H2O

The heteropolytungstate (NH4)₂₁{La(H₂O)₅[Ni(H₂O)]₂As₄W₄₀O₁₄₀}·53H₂O is obtained by the reaction of Na₂₇[NaAs₄W₄₀O₁₄₀]· 60H₂O with NiCl₂·6H₂O, La(NO₃)₃·6H₂O and NH₄Cl at pH‐4.5. The structure and chemical composition are determined by X‐ray diffraction analysis and elemental analysis. The crystal data and main structure refinement are a = 1.9551(3) nm, b = 2.4156(4) nm, c= 3.7068(6) nm, β = 91.505(3)°, V = 17.500 (5) nm³, monoclinic crystal system with space group P2₁/n, Z = 4, R₁ = 0.0573, wR₂ = 0.0717 [I >2<s?(I)], R₁, = 0.2463 and wR₂ = 0.1199 (all data). [La(H₂O)₅] {Ni(H₂O)}₂AS₄W₄₀O₁₄₀ has C₂, symmetry. IR spectra of the ligand [NaAs₄W₄₀O₁₄₀]^27‐ and its three complexes were discussed.     

WOx/TiO2光催化剂的可见光催化活性机理探讨

采用磁控溅射技术在用浸渍提拉法制得的TiO2薄膜上，溅射氧化钨层,通过气相反应中光催化降解二甲苯的实验表明，WOx/TiO2薄膜具有可见光活性.通过UV-Vis吸收光谱、X射线光电子能谱（XPS）等方法对其可见光活性的机理进行探索.UV-Vis吸收光谱表明WOx,TiO2对可见光响应的范围有一定的扩展,吸收强度增加.XPS表明WOx/TiO2薄膜表面形成了明显的W杂质能级和Ti缺陷能级,这是WOx/TiO2在可见光范围有一吸收的主要原因,也是光催化剂具有可见光活性的必要条件之一，同时杂质能级的存在使半导体费米能级上移,载流子增加,光催化效率提高.     

聚丙烯酰胺/醋酸铬与聚丙烯酰胺/酚醛胶态分散凝胶的纳米颗粒自组织分形结构

采用原子力显微镜 ,分别对无机交联体系聚丙烯酰胺 Cr3+ 和有机交联体系聚丙烯酰胺 酚醛胶态分散凝胶的微观结构进行了显微图像分析 .发现无论是在有机还是无机交联体系中 ,也无论聚丙烯酰胺和交联剂浓度如何变化 ,在微米尺度上最终形成的都是具有自相似性的树枝状分形图像 ,在更小尺度上则发现单个小树杈分形体都是由纳米级的颗粒紧密堆积而成 .在所研究的胶态分散凝胶体系中 ,树枝状分形结构的形成及其具体的形态取决于聚丙烯酰胺的浓度 ,而交联剂的有无及其多少只对树枝状凝胶分形的几何形态产生一定影响 .实验结果还表明纳米级 (≤ 10 0nm)的胶体颗粒构成的分形结构的凝胶其弹性模量G′比微米级的高出一个数量级 .且粒子尺度越小 ,则凝胶的力学稳定性越强