Catalytic Oxidation of Dimethyl Ether to Dimethoxymethane over Cs Modified HaPW12O40/SiO2 Catalysts

The attractive utilization route for one-step catalytic oxidation of dimethyl ether to dimethoxymethane was successfully carried out over the H3PW12O40（40%）/SiO2 catalyst, modified by Cs, K, Ni, and V. The Cs modification of H3PW12O40（40%）/SiO2 gave the most promising result of 20% dimethyl ether conversion and 34.8% dimethoxymethane selectivity. Dimethoxymethane could be synthe- sized via methoxy groups decomposed from dimethyl ether through the synergistic effect between the acid sites and the redox sites of Cs modified H3PW12O40（40%）/SiO2.     

Transparent conducting oxides: texture and microstructure effects on charge carrier mobility in MOCVD-derived CdO thin films grown with a thermally stable, low-melting precursor

A series of low-melting, thermally stable cadmium metal-organic chemical vapor deposition (MOCVD) precursors have been synthesized, structurally and spectroscopically characterized, and implemented in growth of highly conductive and transparent CdO thin films. One member of the series, bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)(N,N-diethyl-N',N'-dimethyl-ethylenediamine)cadmium(II), Cd(hfa)(2)()(N,N-DE-N',N'-DMEDA), represents a particularly significant improvement over previously available Cd precursors, owing to the low melting point and robust thermal stability. High-quality CdO films were grown by MOCVD on glass and single-crystal MgO(100) between 300 and 412 degrees C. Film growth parameters and substrate surface have large effects on microstructure and electron carrier transport properties. Enhanced mobilities observed for highly biaxially textured films grown on MgO(100) vs glass are attributed, on the basis of DC charge transport and microstructure analysis, to a reduction in neutral impurity scattering and/or to a more densely packed grain microstructure. Although single-grained films grown on MgO(100) exhibit greater mobilities than analogues with discrete approximately 100 nm grains and similar texture, this effect is attributed, on the basis of charge transport and Hall effect measurements as well as optical reflectivity analysis, to differences in carrier concentration rather than to reduced grain boundary scattering. Unprecedented conductivities and mobilities as high as 11,000 S/cm and 307 cm(2)/V.s, respectively, are obtained for epitaxial single-grained films (X-ray diffraction parameters: fwhm(omega) = 0.30 degrees, fwhm(phi) = 0.27 degrees ) grown in situ on MgO(100) at a relatively low temperature (400 degrees C).     

Preparation, characterization, and application of multistimuli-responsive microspheres with fluorescence-labeled magnetic cores and thermoresponsive shells

Novel functional microspheres with multistimuli-responsive properties have been prepared and characterized. The as-prepared microspheres respond to an external magnetic field, environmental temperature, and ultraviolet radiation. The in vitro drug-loading efficiency and drug-release behavior of these microspheres demonstrated that they could be used as drug carriers for drug controlled release. The results of in vivo distribution investigations of these microspheres showed that they exhibit a high magnetic-targeting effect, which holds promise for applications in various fields such as magnetic drug targeting and tissue labeling, among others.     

Experimental and computational studies of intracomplex reactions in Mg+(primary, secondary alkylamine) complexes induced by photoexcitation of Mg+

We report herein a comprehensive study of photoinduced reactions in complexes of Mg+ with primary (n-propyl- and isopropylamine) and secondary amines (dipropyl- and diisopropylamine) in the spectral range of 230-440 nm. Similar to the methyl- and ethylamine complexes studied previously, N-H bond activation of these complexes is very unfavorable. Instead, the C(alpha)-C, C-N, and C(alpha)-H bond-cleavage photoproducts are observed after photoexcitation of the Mg+ complexes (3(2)P<--3(2)S). For Mg+(primary amine) complexes, for example, Mg+-NH2CH2CH2CH3, and Mg+-NH2CH(CH3)2, the photoproducts resulting from C(alpha)--C rupture prevail after P(z) and charge-transfer excitations, whereas the Mg+ photofragment is predominant upon P(x,y) excitation. However, with further N-alkyl substitution, as in Mg+(secondary amine) complexes, for example, Mg+-NH(CH2CH2CH3)2 and Mg+-NH[CH(CH3)2]2, a novel intracomplex C-C coupling photoreaction dominates on P(x,y) excitation of Mg+, which is believed to arise from Mg+* insertion into the C-N bond. With P(z) and charge-transfer excitation, the Mg-R elimination photoproducts, arising from C(alpha)-C bond cleavage, predominate. The energetics and possible mechanisms of the intracomplex photoreactions are analyzed in detail with the help of extensive quantum mechanics calculations.     

Density functional theory studies on the Raman and IR spectra of meso-tetraphenylporphyrin diacid

The vibrational spectra of meso-tetraphenylporphyrin diacid (H4TPP2+) have been studied with the density functional theory. Raman and IR spectra of H4TPP2+ and its N-deuterated analogue (D4TPP2+) are measured and compared with the computational results. Complete assignments of observed IR and Raman bands were proposed on the bases of calculation results. The DFT calculations reproduce 140 observed fundamentals with the RMS 8.6 cm-1. The computational as well as the experimental results reveal that the saddle-distortion of porphyrin macrocycle for the diacid leads to a significant effect on its vibrational spectra. Especially, several out-of-plane skeletal modes, which were either unobserved or very weak in the Raman spectra of CuTPP and H2TPP, are activated in the Raman spectra of the diacids. In addition, enhancement for the Raman bands of phenyl CC stretching modes were observed and attributed to the conjugation effect of pi-systems of the phenyl and the porphyrinato macrocycles.     

Comparisons of NMR spectral quality and success in crystallization demonstrate that NMR and X-ray crystallography are complementary methods for small protein structure determination

X-ray crystallography and NMR spectroscopy provide the only sources of experimental data from which protein structures can be analyzed at high or even atomic resolution. The degree to which these methods complement each other as sources of structural knowledge is a matter of debate; it is often proposed that small proteins yielding high quality, readily analyzed NMR spectra are a subset of those that readily yield strongly diffracting crystals. We have examined the correlation between NMR spectral quality and success in structure determination by X-ray crystallography for 159 prokaryotic and eukaryotic proteins, prescreened to avoid proteins providing polydisperse and/or aggregated samples. This study demonstrates that, across this protein sample set, the quality of a protein's [15N-1H]-heteronuclear correlation (HSQC) spectrum recorded under conditions generally suitable for 3D structure determination by NMR, a key predictor of the ability to determine a structure by NMR, is not correlated with successful crystallization and structure determination by X-ray crystallography. These results, together with similar results of an independent study presented in the accompanying paper (Yee, et al., J. Am. Chem. Soc., accompanying paper), demonstrate that X-ray crystallography and NMR often provide complementary sources of structural data and that both methods are required in order to optimize success for as many targets as possible in large-scale structural proteomics efforts.     

离子选择电极—流动注射分析法动力学测定葡萄糖存在下的果糖

本文将离子电极与流动注射分析相结合，利用３０℃下，在强碱性介质中，果糖和葡萄糖与２，４－二硝基酚钠反应速度明显差异，动力学测定了葡萄糖存在下果糖的含量。自制了２，４－二硝基酚电极作为动力学电位测定用的工作电极。本法测定果糖的范围为０．０２～１．００ｍｏｌ／Ｌ，其ＲＳＤ为４．０％～４．９％，ＲＥ为１．０～５．０％；当Ｃ葡／Ｃ果≤３倍时，葡萄糖的干扰不超过５％；本法也曾成功地用于果葡萄浆测定，其ＲＳＤ     

树脂法再生贮氢合金材料包覆液工艺中树脂吸附性能研究

本文研究并探讨了NK-ELN型离子交换树脂在再生贮氢合金材料包覆液过程中，温度、流速、溶液中离子浓度等条件对树脂交换容量和再生效率的影响，为树脂法再生贮氢合金材料包覆液工艺的制定，提供了一系列重要参数。     

2, 2＇─(1, 4─亚乙二氧基)—二苯甲酸与钴(Ⅱ)生成的两种配合物的结构研究

硝酸钴与２，２＇－（１，４－亚乙二氧基）－二苯甲酸（Ｈ２Ｌ，图１）作用分别得到红色配合物ＣｏＬ＇和蓝色配合物ＣｏＬ″。经元素分析、红外光谱、紫外可见光谱、热分析等方法进行了表征、ＣｏＬ＇配合物的分子式为［ＣｏＬ．Ｈ２Ｏ］．３Ｈ２Ｏ，近八面体构型，羧酸根以双齿形式与Ｃｏ（Ⅱ）螯合；ＣｏＬ″配合物分子式为［ＣｏＬ″］。Ｈ２Ｏ，近四面体构型，羧酸根以单齿形与Ｃｏ（Ⅱ）配位。