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991.
Zhenghong Bao Kang Xiao Xingzhen Qi Xinxing Wang Liangshu Zhong Kegong Fang Minggui Lin Yuhan Sun 《天然气化学杂志》2013,(1):107-113
Cu-Fe composite oxides were prepared by co-precipitation method and tested for higher alcohol synthesis from syngas. The selectivity to C2+OH and C6+OH in alcohol distribution was very high while the methane product fraction in hydrocarbon distribution was rather low, demonstrating a promising potential in higher alcohols synthesis from syngas. The distribution of alcohols and hydrocarbons approximately obeyed Anderson-Schulz-Flory distribution with similar chain growth probability, indicating alcohols and hydrocarbons derived from the same intermediates. The effects of Cu/Fe molar ratio, reaction temperature and gas hourly space velocity (GHSV) on catalytic performance were studied in detail. The sample with a Cu/Fe molar ratio of 10/1 exhibited the best catalytic performance. Higher reaction temperature accelerated water-gas-shift reaction and led to lower total alcohols selectivity. GHSV showed great effect on catalytic performance and higher GHSV increased the total alcohol selectivity, indicating there existed visible dehydration reaction of alcohol into hydrocarbon. 相似文献
992.
以间苯三酚为原料,选甲醇进行甲基化反应制备3,5-二甲氧基苯酚,以丙炔酸乙酯经Pechmann环化反应制备了白柠檬素(5,7-二甲氧基香豆素)。考察了甲基化反应、环化反应的影响因素,结果表明n(间苯三酚)∶n(甲醇)=1∶15,干燥氯化氢为催化剂,75℃反应7h,甲基化收率为82%;n(丙炔酸乙酯)∶n(3,5-二甲氧基苯酚)∶n(无水氯化锌)=1∶3∶1,环化温度为100℃,N2保护下反应2h,环化反应收率为88%,两步反应总收率达73%。目标产物用红外、质谱、核磁分析手段进行了表征和分析。 相似文献
993.
The molecular structure, heats of formation, energetic properties, strain energy and thermal stability for a series of substituted difurazano[3,4-b:3′,4′-e]piperazines and their analogues were studied using density functional theory. The results show that it is a useful way to increase the heat of formation values of energetic compounds by incorporating a five- or six-membered aromatic heterocycle to construct a fused ring system. The calculated detonation properties reveal that introducing one heterocycle to construct a fused ring structure greatly enhances their detonation properties. The substitution of the –NF2, –NO2 or –NHNO2 group is very useful for enhancing the detonation performance for the substituted derivatives. According to molecular structure and natural bond orbital analysis, the introduction of the –NO2, –NF2 or –NHNO2 group decreases the stability of the substituted derivative. There is a weak N–NO2 bond conjugation in the NO2-substituted derivatives. An analysis of the bond dissociation energies for several relatively weak bonds suggests that all the unsubstituted derivatives have good thermal stability, but the substitution of –NO2 or –NF2 remarkably decreases their stability. Considering the detonation performance and thermal stability, eight compounds may be considered as the potential candidates of high-energy density materials with less sensitivity. 相似文献
994.
Xi‐Kai Shu Jia Li Feng Liu Xiao‐Jing Lin Xiao Wang Chun‐Xia Song 《Journal of separation science》2013,36(16):2680-2685
This study aimed to seek an efficient method to extract and purify yunaconitine and 8‐deacetylyunaconitine from Aconitum vilmorinianum Kom. by accelerated solvent extraction combined with pH‐zone‐refining counter‐current chromatography. The major extraction parameters for accelerated solvent extraction were optimized by an orthogonal test design L9 (3)4. Then a separation and purification method was established using pH‐zone‐refining counter‐current chromatography with a two‐phase solvent system composed of petroleum ether/ethyl acetate/methanol/water (5:5:2:8, v/v) with 10 mM triethylamine in the upper phase and 10 mM HCl in the lower phase. From 2 g crude extract, 224 mg of 8‐deacetylyunaconitine (I) and 841 mg of yunaconitine (II) were obtained with a purity of over 98.0%. The chemical structures were identified by ESI‐MS and 1H and 13C NMR spectroscopy. 相似文献
995.
A series of Eu3+-incorporated ETS-10 samples were successfully prepared based on the traditional ion exchange method. The relationship between photogenerated charge behaviors and luminescent properties has been investigated in detail. It has been demonstrated that as a result of the charge transfer from the titanate quantum wires to Eu3+ crystal field states, the host matrix ETS-10 functions as the sensitizer of Eu3+ to enhance the red luminescence, while Eu3+ cations contribute to the recombination of photogenerated charges. The behavior of photogenerated charges has significant impact on the luminescent properties of Eu3+-incorporated ETS-10 materials. 相似文献
996.
FAN LeQing CHEN Yuan WU JiHuai LI ZhaoLei XIAO YaoMing HUANG MiaoLiang YU HaiJun 《中国科学:化学(英文版)》2013,56(10):1470-1477
Mesoporous TiO2microsphere(MTM)was synthesized via a simple solution route and then mixed with commercial TiO2(P25)to form highly homogeneous and stable TiO2colloid by simple hydrothermal treatment.The TiO2colloid was coated onto the plastic conductive substrate to prepare mesoporous TiO2film for flexible dye-sensitized solar cells(DSSCs)by low-temperature heat treatment.The influence of MTM content on the physicochemical properties of the flexible TiO2film was characterized by scanning electron microscope,transmission electron microscopy,X-ray diffraction,energy-dispersive X-ray spectrometer,N2adsorption-desorption isotherms,UV–vis absorption and diffuse reflectance spectra.It is revealed that with increasing the MTM content,the dye-loading capability of TiO2film and light-harvesting efficiency of flexible DSSCs are improved due to MTM having high surface area and acting as a light scattering center,respectively,resulting in the enhancement of photocurrent of flexible DSSCs.However,more and larger cracks having negative effect on the performances of flexible DSSCs are formed simultaneously.Under the optimal condition with MTM content of 20%,a flexible DSSC with overall light-to-electric energy conversion efficiency of 2.74%is achieved under a simulated solar light irradiation of 100 mW cm 2(AM 1.5),with 26%improvement in comparison with DSSCs based on P25 alone. 相似文献
997.
HUANG Jing CHEN PengYu YANG Xiao TANG RunLi WANG Lei QIN JinQui LI Zhen 《中国科学:化学(英文版)》2013,56(9):1213-1220
In this paper, two AIE-active luminogens (Oxa-pTPE and Oxa-mTPE) constructed from tetraphenylethene and oxadiazole units were successfully synthesized and their thermal, optical and electronic properties were investigated. By linking TPE to the oxadiazole core through meta-or para-position, the intramolecular conjugation is effectively controlled. Thanks to the intelligent molecular design and specific AIE feature, when fabricated as emissive layers in non-doped OLEDs, they exhibit blue or deep-blue emission with CIE coordinates of (0.17, 0.23) and (0.15, 0.12), and good efficiencies with ηC, max and ηP, max up to 1.52 cd A-1 and 0.84 Im W-1 , shedding some light on the construction of deep-blue AIE fluorophores. 相似文献
998.
Dong‐Cheng Hu Chao‐Hu Xiao Guo‐Zhe Guo Yun‐Xia Yang Jia‐Cheng Liu 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(4):356-359
A one‐dimensional AgI coordination complex, catena‐poly[[silver(I)‐μ‐{2‐[2‐(pyridin‐4‐yl)‐1H‐benzimidazol‐1‐ylmethyl]phenol‐κ2N2:N3}] perchlorate monohydrate], {[Ag(C19H15N3O)]ClO4·H2O}n, was synthesized by the reaction of 2‐[2‐(pyridin‐4‐yl)‐1H‐benzimidazol‐1‐ylmethyl]phenol (L) with silver perchlorate. In the complex, the L ligands are arranged alternately and link AgI cations through one benzimidazole N atom and the N atom of the pyridine ring, leading to an extended zigzag chain structure. In addition, the one‐dimensional chains are extended into a three‐dimensional supramolecular architecture via O—H...O hydrogen‐bond interactions and π–π stacking interactions. The complex exhibits photoluminescence in acetonitrile solution, with an emission maximum at 390 nm, and investigation of the thermal stability reveals that the network structure is stable up to 650 K. 相似文献
999.
Lulu Huang Xiao Xiao Yinping Xie Hubert Kageruka Youe Zhou Fengjiao Deng Hongying Zhong 《Analytica chimica acta》2013
The inhomogeneous re-crystallization process of matrix materials is the major concerns associated with matrix assisted laser desorption/ionization (MALDI) analysis. We describe here the approach termed compressed matrix thin film (CMTF) in order to make a uniform matrix deposition. In this approach, solid matrix particles are compressed under 10 MPa of pressure by a compressor that is regularly used in infrared spectroscopic analysis. Then aqueous samples can be deposited on the surface of the matrix film. Major advantages of the CMTF approach are summarized as follows. (1) Reproducible sample preparation procedure. Size and thickness of matrix thin films can be controlled by using a fixed mold.force and known amount of matrix materials. (2) Significantly decreased shot-to-shot variations and enhanced reproducibility. (3) Tolerance for in situ salt washing. Because matrix materials are hydrophobic, salts can be washed away while proteins or peptides are retained on the surface of matrix thin films through hydrophobic interactions. (4) Improved sensitivity. The hydrophobic coating of MALDI sample plate by matrix thin films prevents the spreading of samples across the plate and confines analytes to a small area, leading to increased local concentration. (5) A new means for tissue analysis. Tissue sections can be directly transferred to the uniform surface of matrix materials for reproducible and quantitative comparison of different molecules in different localization. The proposed CMTF should be an enabling technique for mass spectrometric analysis with improved correlations between signal intensities and sample quantities. 相似文献
1000.
Paper-based microfluidic devices have been widely investigated in recent years. Among various detection techniques, colorimetric method plays a very important role in paper-based microfluidic devices. The limitation, however, is also clear: they generally require highly sensitive indicators. In this work, we have developed a novel enrichment-based paper test for the discrimination of heavy-metal ions. Comparing to regular paper-based microfluidic devices, enrichment-based technique showed largely improved sensitivity. Combining with eight pyridylazo compounds and array technologies-based pattern-recognition, we have obtained the discrimination capability of eight different heavy-metal ions at same concentration as low as 50 μM using our enrichment-based pyridylazo compounds array paper. Identification of the heavy-metal ions was readily achieved using a standard chemometric approach. This method can be, of course, used for other analytes as well. 相似文献