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991.
The heterogeneous reaction of SO2 on TiO2 particles was studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The influences of the oxygen concentration, relative humidity (RH), and ultraviolet (UV) light illumination (λ ≈ 365 nm) intensity on the reaction were investigated. The main product of the heterogeneous reaction of SO2 on TiO2 particles was sulfate with UV illumination and sulfite without it. The production of sulfate was promoted significantly with UV illumination or water, and there was a synergistic effect when both were present. In the dry system without UV, the heterogeneous reaction of SO2 on TiO2 particles was found to be second-order for SO2 and the initial uptake coefficient, γBET, was determined to be 1.94 × 10?6. With UV and RH = 40%, the reaction order was first-order and the initial uptake coefficient was 1.35 × 10?5. 相似文献
992.
Yu‐Hui Zhang Prof. Dr. Kesheng Song Dr. Nian‐Yong Zhu Dr. Dan Yang Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(2):577-587
As a new type of foldamer, β‐aminoxy peptides have the ability to adopt novel β N? O turns or β N? O helices in solution. Herein, we describe a new subclass of β‐aminoxy peptide, that is, peptides of acyclic β2, 3‐aminoxy acids (NH2OCHR1CHR2COOH), in which the presence of two chiral centers provides insight into the effect of backbone stereochemistry on the folding of β‐aminoxy peptides. Acyclic β2, 3‐aminoxy peptides with syn and anti configurations have been synthesized and their conformations investigated by NMR, IR, and circular dichroism (CD) spectroscopic, and X‐ray crystallographic analysis. The β N? O turns or β N? O helices, which feature nine‐membered rings with intramolecular hydrogen bonds and have been identified previously in peptides of β3‐ and β2, 2‐aminoxy acids, are also predominantly present in the acyclic β2, 3‐aminoxy peptides with a syn configuration and N? O bonds gauche to the Cα? Cβ bonds in both solution and the solid state. In the acyclic β2, 3‐aminoxy peptides with an anti configuration, an extended strand (i.e., non‐hydrogen‐bonded state) is found in the solid state, and several conformations including non‐hydrogen‐bonded and intramolecular hydrogen‐bonded states are present simultaneously in nonpolar solvents. These results suggest that the backbone stereochemistry does affect the folding of the acyclic β2, 3‐aminoxy peptides. Theoretical calculations on the conformations of model acyclic β2, 3‐aminoxy peptides with different backbone stereochemistry were also conducted to elucidate structural characteristics. Our present work may provide useful guidelines for the design and construction of new foldamers with predicable structures. 相似文献
993.
Lili Zhu Xiaodan Chen Qihua Zhao Zhongshu Li Xiangyang Zhang Baiwang Sun Prof. Dr. 《无机化学与普通化学杂志》2010,636(8):1441-1443
The novel heterospin complex [Ni2(PhCOO)4(NITpPy)2]·2CH3CN ( 1 ) was synthesized by the reaction of nickel benzoate and 2‐(4‐pyridyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide (NITpPy) in acetonitrile and dichloromethane solutions. The X‐ray structure determination shows that complex 1 consists of a symmetrical dimeric NiII benzoate paddle‐wheel core and pyridyl nitrogen atoms of radical ligands at the apical position, in addition, the temperature (2–300K) dependent magnetic susceptibility measurements indicate that 1 has antiferromagnetic behavior. 相似文献
994.
Zhi‐An He Guang‐Zhou Lu Lin‐Lin Zhu Yong‐Xue Wang Fu‐Lin Yan Ji‐Xia Zhang 《中国化学会会志》2010,57(2):256-259
Two new ent‐kaurane diterpenoids, taihangexcisoidesin C (1) and its acetonide, taihangexcisoidesin D (2), along with 9 known compounds were isolated from the leaves of Isodon excisoides. The structures of the new compounds were elucidated using 1D and 2D NMR spectroscopy analysis. Compounds 3‐6 and 8‐9 were tested for their antibacterial activity against Escherichia coli, Staphylococcus aureus, S. epidermidis and S. saprophyticus. Compound 6 showed inhibitory effects on Staphylococcus aureus, S. epidermidis and S. saprophyticus MIC values 32, 16 and 16 μg/mL, respectively. All of the compounds didn't show effects on Escherichia coli (MIC > 10 mg/mL). 相似文献
995.
Jian-Feng Zhou Gui-Xia Gong Kun-Bo Shi Yu-Lan Zhu 《Monatshefte für Chemie / Chemical Monthly》2009,140(6):651-654
Abstract A facile procedure for the synthesis of quinoxalines is being reported starting from 3-(2-bromoacetyl)coumarins or 3-(2-bromobutanoyl)coumarins
and substituted o-phenylenediamines. The reactions were carried out under catalyst-free and microwave irradiation conditions producing the
title compounds in moderate to excellent yields in a short time with easy workup. The structures of all new compounds have
been confirmed on the basis of their IR, 1H NMR, 13C NMR, and HRMS data.
Graphical Abstract
相似文献
996.
Shumin Han Yuan Li Zhong Zhang Xilin Zhu Jinhua Li Lin Hu 《Frontiers of Chemistry in China》2009,4(1):48-51
The Ml-Mg-Ni-based (Ml = La-rich mixed lanthanide) hydrogen storage alloy Ml0.88Mg0.12Ni3.0-Mn0.10Co0.55Al0.10 was prepared by inductive melting. The micro-structure was analyzed by XRD and SEM. The alloy consists mainly of CaCu5-type phase, Ce2Ni7-type phase and Pr5Co19-type phase. The electrochemical measurements show that the maximum discharge capacity is 386 mAh/g, 16.3% higher than that
of the commercial AB5-type alloy (332 mAh/g). At discharge current density of 1 100 mA/g, high rate dischargeability is 62%, while that of the
AB5-type alloy is only 45%. The discharge capacity decreases to 315 mAh/g after 300 charge/ discharge cycles, 81.5% of the
maximum discharge capacity.
__________
Translated from Journal of Xi’an Jiao Tong University, 2008, 42(3) (in Chinese) 相似文献
997.
Aiju Zhang Zhihong Li Zicheng Li Yumei Zhu 《Journal of Sol-Gel Science and Technology》2009,49(1):6-11
SiO2–Al2O3–Na2O glass coated cubic boron nitride (cBN) abrasive particles were prepared by sol–gel technique. The results indicated that
SiO2–Al2O3–Na2O glass was excellent material for oxidation protection of cBN abrasive grains because coefficient of thermal expansion of
this glass closely matched that of cBN materials. The single particle compressive strength and impact toughness of this glass
coated cBN abrasive particles were significantly increased. For the application of glass coated cBN abrasives to vitrified
grinding wheels, it was evident that the glass coating provided high bonding strength between cBN abrasive grains and vitrified
bond system. 相似文献
998.
Xinchen Kang Wenting Shang Qinggong Zhu Jianling Zhang Tao Jiang Buxing Han Zhonghua Wu Zhihong Li Xueqing Xing 《Chemical science》2015,6(3):1668-1675
We proposed a strategy to synthesize mesoporous inorganic salt particles using the special properties of ionic liquid (IL) mixtures, and hollow mesoporous LaF3, NdF3, and YF3 particles were synthesized and characterized using different techniques. The size of the mesopores in the salt particles was about 4 nm, and the materials were full of crystal defects. The LaF3, NdF3 and YF3 particles were used as the catalysts for the cyanosilylation reaction of benzaldehyde using trimethylsilyl cyanide, and Ru/LaF3 and Ru/NdF3, in which Ru nanocatalysts were supported on the LaF3 and NdF3 particles with mesopores, were used to catalyze hydrogenations of benzene to cyclohexane and levulinic acid (LA) to γ-valerolactone (GVL). It was discovered that the activities of these catalysts were unprecedentedly high for these reactions. Detailed study showed that both the crystal defects and the mesopores in the salt particles played crucial roles for the extremely high catalytic activity. 相似文献
999.
Fang Zhu 《Analytica chimica acta》2009,650(2):202-196
A method based on solid-phase microextraction (SPME) and gas chromatography with mass spectrometry (GC/MS) for the determination of 18 organophosphorus pesticides (OPPs) in textiles is described. Commercially available SPME fibers, 100 μm PDMS and 85 μm PA, were compared and 85 μm PA exhibited better performance to the OPPs. Various parameters affecting SPME, including extraction and desorption time, extraction temperature, salinity and pH, were studied. The optimized conditions were: 35 min extraction at 25 °C, 5% NaSO4 content, pH 7.0, and 3.5 min desorption in GC injector port at 250 °C. The linear ranges of the SPME-GC/MS method were 0.1-500 μg L−1 for most of the OPPs. The limits of detection (LODs) ranged from 0.01 μg L−1 (for bromophos-ethyl) to 55 μg L−1 (for azinphos-methyl) and the RSDs were between 0.66% and 9.22%. The optimized method was then used to analyze 18 OPPs in textile sample, and the determined recoveries were ranged from 76.7% to 126.8%. Moreover, the distribution coefficients of the OPPs between 85 μm PA fiber and simulative sweat solution (Kpa/s) were determined. The determined Kpa/s of the OPPs correlated well with their octanol-water partition coefficients (r = 0.764 and 0.678) and water solubility (r = −0.892 and −0.863). 相似文献
1000.
W. Z. Zhang Ma Shuang M. C. Zhu Liu Lei E. J. Gao 《Russian Journal of Coordination Chemistry》2009,35(12):874-878
A novel complex [Zn(Qina)2(DMSO)2] · 2DMSO (I) (Qina = quinaldic acid, DMSO = dimethyl sulfoxide) has been synthesized and characterized by X-ray diffraction, elementary analysis, and IR spectrum. The unit cell parameters for complex I: a = 8.2884(11), b = 22.015(3), c = 9.0685(12) Å, β = 100.61(0)°, V = 1626.41(40) Å3, Z = 2, space group, P21/n. In the complex I, the Zn(II) atom was six-coordinated to form a distorted octahedral geometry by two Qina ligands and two dimethyl sulfoxide molecules. The crystal structure is stabilized by hydrogen bonds, C - H... π, π-π stacking interaction between adjacent complexes. The binding of the complex I with calf thymus DNA has been investigated by fluorescence spectroscopic studies. The result suggested that the complex intercalates into DNA base pairs. 相似文献