Template-assisted syntheses of two novel porous zirconium methylphosphonates

Two porous zirconium methylphosphonates (designated as ZMPmi and ZMPme respectively) were synthesized by using dibutyl methylphosphonate (DBMP) as a template. Two efficient post-synthetic treatments were developed to remove the incorporated template without destroying the hybrid structures. The materials were characterized by SEM, EPMA, TG, DTA, FTIR, and NMR. Specific surface area and porosity were evaluated by BET, alpha(s)-plots and DFT methods based on N-2 adsorption-desorption isotherms. The specific surface areas of ZMPmi and ZMPme are determined to be 279 and 403 m(2) g(-1) and the maxima of pore size distributions are at 0.7 and 1.3 nm respectively. (c) 2005 Elsevier Inc. All rights reserved.

Polymeric fullerene oxide films produced by decomposition of hexanitro[60]fullerene

A new poly(fullerene oxide) thin film material has been fabricated by thermal activation and electron bombardment on hexanitro[60]fullerene (HNF) film deposited on a An substrate, all under vacuum conditions. The reaction products in the polymerization process are analyzed by XPS, UPS, IR, TGA-MS and LDI-MS techniques. It is found that the main effect of thermal and radiation treatments is to induce cleavage of -NO bonds from HNF molecules resulted in the release of nitric oxide gas and the formation of fullerene-bound oxyradicals, C-60-C-6. Spectroscopic evidence strongly suggests that rearrangement of fullerenic nitro moieties into nitrito groups is involved in the HNF decomposition process prior to the generation of reactive oxyradical intermediates. Consequently, the intermolecular coupling reaction of these oxyradicals leads to carbon polymer networks containing oxygen-bridged fullerenes. The thermally generated polymeric thin film is stable up to 900 K. Electron bombardment is also effective in both the decomposition of -NO2 groups and the removal of -OH groups present in HNF films. UV irradiation at 365 nm alone is shown to be not as efficient for the polymer formation. (C) 2003 Elsevier Ltd. All rights reserved.

Characterization of metal-containing molecular sieves and their catalytic properties in the selective oxidation of cyclohexane

Three types of metal-containing molecular sieves with AFI, AEL and CHA structures (Me = Co, Mn, Cr and V) were synthesized hydrothermally and characterized by XRD, XRF, TG, TPR, NH3-TPD and FT-IR. It was revealed that metals were incorporated into the framework of molecular sieves and induced the presence of charge centers. Both cobalt and manganese in the framework of AIPO-5, AlPO-11 and SAPO-34 were not reducible before the structure collapse. The redox behaviours of these catalysts in cyclohexane oxidation at 403 K using O-2 as oxidant were examined. CoAPO-11 exhibited best activity and good selectivities for the monofunctional oxidation products (88.5%). Cyclohexanol was the major product over most catalysts, whereas for Cr-containing molecular sieves, high selectivity of cyclohexanone was observed. Investigation of reaction mechanism based on CoAPO-11 and CrAPO-5 catalysts indicated that the decomposition of cyclohexyl hydroperoxide (CHHP), the intermediate in cyclohexane oxidation, followed the pathway: cyclohexanone <-- CHHP --> cyclohexanol -->cyclohexanone. (C) 2004 Elsevier B.V. All rights reserved.

耕地土壤交换性钙镁比值的研究

对沈阳市郊区1994个耕地表土(0～20cm)样点和4个典型剖面中交换性Ca/Mg的比值进行了对比研究。结果表明:不同土属耕层土壤中Ca、Mg交换量有较大差别,交换性Ca/Mg的比值主要受母质等成土因素的影响;棕壤的各个土属的Ca/Mg在4左右,石灰性草甸土和草甸沼泽土的Ca/Mg则在8以上。棕壤和草甸土典型剖面不同层次中的Ca/Mg比值有着随深度加深而降低的趋势;由于Ca的植物返还率较Mg高,同一土壤类型中Ca/Mg比值的最大值出现在表土层,母质层中的Ca/Mg则相对稳定。对土壤Ca/Mg进行研究可以丰富土壤离子交换性能研究和土壤发生学特性研究的内容。

黄孢原毛平革菌合成木素过氧化物酶的营养调控

本文研究了营养条件对黄孢原毛平革茵(Phanerochale chrysosporium)ME-116合成木素过氧化物酶及其同工酶组分的影响.在最适培养条件下获得1500U/L的酶活.高效液相色谱分离的5个同工酶组分中以P_2组分含量最高.低碳高氮培养基最适于酶的合成.降低氮和KH_2PO_4含量致使各组分含量下降,而改变MgSO_4和CaCl_2浓度对P_2组分无影响.表面活性剂吐温80主要通过提高细胞膜透性而增加酶的合成.黎芦醇对5种同工酶组分的合成均有诱导作用.培养基中各营养因子对木素过氧化物酶的合成存在着复杂的交互作用.

NDVI spatial pattern and its differentiation on the Mongolian Plateau

GIMMS NDVI database and geo-statistics were used to depict the spatial distribution and temporal stability of NDVI on the Mongolian Plateau. The results demonstrated that: (1) Regions of interest with high NDVI indices were distributed primarily in forested mountainous regions of the east and the north, areas with low NDVI indices were primarily distributed in the Gobi desert regions of the west and the southwest, and areas with moderate NDVI values were mainly distributed in a middle steppe strap from northwest to southeast. (2) The maximum NDVI values maintained for the past 22 years showed little variation. The average NDVI variance coefficient for the 22-year period was 15.2%. (3) NDVI distribution and vegetation cover showed spatial autocorrelations on a global scale. NDVI patterns from the vegetation cover also demonstrated anisotropy; a higher positive spatial correlation was indicated in a NW-SE direction, which suggested that vegetation cover in a NW-SE direction maintained increased integrity, and vegetation assemblage was mainly distributed in the same specific direction. (4) The NDVI spatial distribution was mainly controlled by structural factors, 88.7% of the total spatial variation was influenced by structural and 11.3% by random factors. And the global autocorrelation distance was 1178 km, and the average vegetation patch length (NW-SE) to width (NE-SW) ratio was approximately 2.4:1.0.

Synthesis and gas permeability of novel fluorinated poly(phenylene-co-naphthalimide)s

A new class of high-performance polymers [poly(phenylene-co-naphthalimide)s] was prepared through the Ni(0) catalytic coupling of N-(4-chloro-2-trifluromethylphenyl)-5-chloro-1,8-naphthalimide and 2,5-dichlorobenzophenone. The resulting copolymers exhibited high molecular weights (high inherent viscosities) and a combination of desirable properties such as good solubility in dipolar aprotic solvents, film-forming capability, and mechanical properties. The glass-transition temperatures of the copolymers ranged from 320 to 403 degrees C and increased as the content of the naphthalimide moiety increased. Tough polymer films, obtained via casting from N-methylpyrrolidone solutions, had tensile strengths of 64-107 MPa and tensile moduli of 3.4-4.7 GPa. The gas permeability coefficients of the copolymers were measured for H-2, CO2, O-2, CH4, and N-2. They showed oxygen permeability coefficients and permeability selectivity of oxygen to nitrogen (permeability coefficient for O-2/permeability coefficient for N-2) in the ranges of 1.39-4.31 and 4.92-5.38 barrer, respectively.

Structures and electrochemical characteristics of several kinds of alloys

The structures and the electrochemical characteristics of La0.7-xCexMg0.3Ni2.8Co0.5 (x = 0.1-0.5) alloy, Ti0.25-xZrxV0.35Cr0.1Ni0.3 (x = 0.05-0.15) alloy and AB(3

Fe在丝光沸石骨架中取代位置的DFT研究

中国科学院山西煤炭化学研究所

PDP用荧光粉的真空紫外辐照特性

利用“等离子体显示用荧光粉光学测试系统”中147nm真空紫外光,对实用的（Y,Gd）BO_3:Eu红粉,Zn_2SiO_4:Mn和（Ba,Sr,Mg）O·nAl_2O_3:Mn绿粉以及（Ba,Mg）O·nAl_2O_3:Eu~(2+)蓝粉进行较长时间的辐照,以观察荧光粉的衰减特性,发现红粉衰减最小,蓝粉初始衰减较快,而绿粉亮度存在一个先升后降的现象。

Luminescent properties of Ba-3(PO4)(2):Eu, Tb phosphors

Luminescence of europium (III), europium(II) and terbium(III) has been observed in Ba-3(PO4)(2):Eu, Tb phosphors which are synthesized in air atmosphere. The valence state of europium is influenced by amount of terbium. It is notable that the relative intensity of the emission spectra peaks corresponding to Eu2+ is increased if the amount of Tb3+ is increased. These phenomena can be explained by an electron transfer mechanism. We predict a new kind of two-rare-earth codoped trichromatic phosphors in Ba-3(PO4)(2) matrix.

A study of the dependence of ferrocene diffusion on electrolyte concentration and size in a polymer medium using non-steady-state chronoamperometry

This article describes a quantitative study of the diffusion rate of ferrocene(Fc) dissolved in ploy(ethylene glycol)(PEG) medium containing MClO(4)(M = Li+, Na+, Bu(4)N(+), Hx(4)N(+)). The apparent diffusion coefficient D-app and the active concentration c(a) of Fc were simultaneously measured by using non-steady-state chronoamperometry. The D-app and c(a) of Fc have been estimated in PEG containing different concentrations and sizes of supporting electrolyte, and the dependence of D-app on ferrocene concentrations has been observed. The values of D-app decrease with increasing concentrations of Fc, increasing concentrations of LiClO4 or the ratio (O:Li) and also with 4 decreasing cation radius of the electrolyte. The temperature dependencies conform to a simple free volume model. The concentration and size of the counterion dependencies of the diffusion rate are similar to the behavior of their dependencies of ionic conductivity in polyelectrolyte.

Thermal decomposition processes of polyaniline and poly-o-toluidine investigated by direct pyrolysis mass spectrometry

The thermal decomposition of polyaniline(PAn) and poly-o-toluidine(POT) was studied by means of direct pyrolysis mass spectrometry(DM) and MS/MS, The results showed that both benzene-diamine and quinone-diimine units were produced, and the intensities of fragments corresponding to quinone-diimine units increased as the oxidation degrees increased, The mechanism of thermal decomposition of PAn and POT was given for the first time.

高氯酸铒与蛋氨酸配合物的合成及结构研究

在水溶液中合成了标题配合物，其化学式为Ｅｒ（Ｍｅｔ）２（ＣｌＯ４）３·４．５Ｈ２Ｏ（Ｍｅｔ为蛋氨酸）．研究了配合物的红外光谱．用Ｘ射线单晶衍射法测定了配合物的晶体结构，结果表明，其结构式为［Ｅｒ２（ＤＬ－Ｍｅｔ）４·８Ｈ２Ｏ］·（ＣｌＯ４）６·Ｈ２Ｏ．属单斜晶系，空间群为Ｐ２１／ｎ，晶胞参数为：ａ＝１３．８４６（５）Ａ，ｂ＝２１．７９４（７）Ａ，Ｃ＝１９．１３１（５），β＝９０．５１（３）°，Ｖ＝５７７２．８４（３）３，Ｚ＝４．每两个Ｅｒ原子之间通过四个蛋氨酸的羧基桥相连而形成双核配合物．两对对位的蛋氨酸中，其中一个为Ｌ型，而另一个为Ｄ型．每个Ｅｒ原子还与四个水分子配位，其配位数为８．对于每个双核离子而言，其配位多面体由两个四方反棱柱体组成．