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51.
52.
R.T. Rajendra Kumar J. Grabowska J.P. Mosnier M.O. Henry E. McGlynn 《Superlattices and Microstructures》2007,42(1-6):337
ZnO nanostructures are grown on Au-catalyzed Si substrates by vapour phase transport between 800 and 1150 C. Nanostructures grown at 800 C are mainly rod-like in structure with diameters of <200 nm. Increasing growth temperature yields combination growth modes with 2D structures (nanowalls/nanosheets) connecting 1D nanorods at intermediate temperatures and a 3D growth mode of foam-like appearance at the highest temperatures. The present work indicates that it may be possible to systematically control the morphology of ZnO nanostructures by varying the growth temperature. 相似文献
53.
Hayes CJ Whittaker BP Watson SA Grabowska AM 《The Journal of organic chemistry》2006,71(26):9701-9712
We have developed an improved and reliable method for stereoselective functionalization at C4 of naturally occurring (+)-catechin. Our method utilizes DDQ oxidation followed by trapping of the quinonemethide intermediate with allyl alcohol. The quinonemethide intermediate can be regenerated from the allyl ether by exposure to boron trifluoride diethyl etherate. This reactive intermediate can be trapped with a wide range of external nucleophiles. NBS bromination, lithium halogen exchange, and alkylation gave access to C8-allyl derivatives of (+)-catechin, and this allyl group was used in a series of cross-metathesis experiments to prepare novel dimeric catechin-derived products. Gallate ester derivatives of the novel C4- and C8-substituted catechins were prepared, and these materials were screened for potential anticancer activity in a range of human cancer cell lines. From these preliminary cytotoxicity assays (MTT) we found that C8-propyl-catechin gallate was more active (IC50 = 31 microM) than catechin gallate (CG, IC50 = 53 microM) or epicatechin gallate (ECG, IC50 = 76 microM) against the colorectal adenocarcinoma cell line HCT116. Differential sensitivity in pancreas (Pan1), bladder (RT112), stomach (MGLVA1), liver (HepG2), and fibroblasts (46Br.1G1) cell lines was also observed. 相似文献
54.
55.
Munshi G Mustafa Sudhir Raniwala T Awes B Rai RS Bhalerao JG Contreras RV Gavai SK Ghosh P Jaikumar GC Mishra AP Mishra H Mishra B Mohanty J Nayak J-Y Ollitrault SC Phatak L Ramello R Ray PK Sahu AM Srivastava DK Srivastava VK Tiwari 《Pramana》2006,67(5):961-981
This is the report of Heavy Ion Physics and Quark-Gluon Plasma at WHEPP-09 which was part of Working Group-4. Discussion and
work on some aspects of quark-gluon plasma believed to have created in heavy-ion collisions and in early Universe are reported. 相似文献
56.
Hanna Grabowska Helena Teterycz Roman Klimkiewicz 《Research on Chemical Intermediates》2005,31(9):797-806
The investigation presented attempts to apply the Zr-Mg-Y oxide system as a catalyst for phenol alkylation with methanol by
a gas-phase reaction. The studies were carried out in a continuous process performed at atmospheric pressure. It was indicated
that the catalyst obtained is active and ortho-selective in the methylation of phenol. At 370°C, in the presence of Zr-Mg-Y oxide catalyst under the experimental conditions
studied, an interesting yield of ortho-cresol (over 46% with 66.5% selectivity) was attained. Zr-Mg-Y-O catalyst was prepared by low temperature method and it was
characterised by X-ray powder diffraction, scanning microscopy and nitrogen physisorption. In addition, in this reaction the
catalytic specificity of Zr-Mg-O, ZrO2, MgO and Y2O3 was examined. 相似文献
57.
The effect of heat-treatment on 10 wt% CuO-ZnAl2O4 catalytic activity in methylation of phenol and the degree of interaction of CuO active phase with support spinel phase were investigated. The CuO-ZnAl2O4 sample was subjected to heat-treatment up to 1000°C. The thermal products were characterized by X-ray diffraction (XRD) analysis, nitrogen adsorption-desorption at -196°C and temperature-programmed desorption (TPD-MS) of CO2. Additionally, the reducibility of copper phases was investigated by temperature-programmed reduction (TPR). XRD patterns of the fresh catalyst sample (calcined at 600°C) indicated the presence of a mixture of poorly crystallized CuO and ZnAl2O4 spinel phase. The presence of two reducible copper species has been found on fresh CuO-ZnAl2O4 catalyst by TPR analysis. After subsequent calcinations in air at elevated temperatures some CuO disappeared with appearance of CuAl2O4 phase. The catalytic results revealed that the CuO addition to ZnAl2O4 increases the activity in ortho-methylation of phenol. Subsequent heat-treatment up to 900°C causes partial deactivation of copper centers, which is the result of transformation of CuO to the inactive CuAl2O4 phase. 相似文献
58.
AM Cardoso SM Alexandre CM Barros AJ Correia NM Nibbering 《Rapid communications in mass spectrometry : RCM》1999,13(19):1885-1888
The collision-induced dissociation (CID) of deprotonated arylalkylamines of general formula R(1)C(6)H(4)CHR(2)CH(2)NR(3)(2) (where R(1) = H, OH, F or NO(2); R(2) = H or OH; R(3) = H or CH(3)) generated by negative chemical ionization with H(2)O and D(2)O as ionizing reagents, is discussed. The negative chemical ionization mass spectra show that, in the absence of a hydroxy group in the aromatic ring, deprotonation takes place at the benzylic position whereas the proton is lost from the OH group when present. The nitro compound forms only M(-.) ions. The CID spectra of the deprotonated molecules show that fragmentations are strongly dependent on the structural features of the molecules, namely the presence or absence of substituents in the aromatic ring or aliphatic chain. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
59.
The gas-phase alkylation of m-cresol (3-methylphenol) with n-and iso-propanol was investigated. The reactions were carried out in a continuous process at atmospheric pressure over an iron catalyst that contains Cr, Si and K oxides. It is possible to obtain n and iso-propyl derivatives of m-cresol with satisfactory selectivity. 相似文献
60.
H. Grabowska R. Klimkiewicz L. Syper J. Wrzyszcz 《Research on Chemical Intermediates》2000,26(4):357-364
The results of gas-phase conversion of ω-phenyl-substituted alcohols (benzyl alcohol, 2-phenylethanol, 3-phenyl-1-propanol)
and their equimolar mixtures with primary normal alcohol (1-octanol) are presented. Reactions were carried out at atmospheric
pressure in the presence of an iron catalyst in the temperature range of 568–673 K and load of 2.0 h−1. 2-Phenylethanol and 3-phenyl-1-propanol undergo dehydrogenation to aldehydes and condensation to esters. At higher temperatures
symmetrical ketones containing ω-phenyl group as substituent are formed. Mixtures of these alcohols with 1-octanol give among
others asymmetrical aromatic-aliphatic ketones. 相似文献