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51.
Atomic carbon, a reactive intermediate abundant in the interstellar medium (ISM) can participate in various energetically demanding reactions in its extremely long living (69 min) first excited singlet state ((1)D). Several studies on reactions of oxygen containing species with carbon atoms have been reported, however mechanistic details of the title reaction remain obscure. We report here quantum chemical studies on reactions of methanol with (3)P and (1)D carbon atoms at the CCSD(T)/cc-pVTZ level of theory, with which experimentally well known facile CO production, intermolecular acetaldehyde formation, and intermolecular dimethoxymethane production mechanisms are explained. Energetics of the fragmentation, O-H insertion, C-H insertion, and O-C insertion channels on the triplet and singlet surfaces are studied. The CO production mechanism by C ((1)D) is identified as an oxygen abstraction and a triplet PES seems non-operative. Presenting novel features for the intermolecular reaction channels, current findings may be applicable to C + ROR reactions. 相似文献
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Denis Koschichow Jochen Fröhlich Roberto Ciorciari Ilker Kirik Reinhard Niehuis 《PAMM》2013,13(1):311-312
In the present work, direct numerical simulations (DNS) of the flow through a low-pressure linear turbine cascade T106 with parallel endwalls were conducted to investigate the effects of unsteady passing wakes of the upstream blade row on the secondary flow in the endwall region of the passage. The impact of the wakes on the secondary flow is discussed by means of the time-averaged values. Furthermore, the results of DNS are compared with experimental data. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Ilker Kucuk Atakan Tekgül Kagan Sarlar Ersin Civan Nil Kucuk Barıs Macan 《哲学杂志》2013,93(21):2736-2750
ABSTRACTLa0.7Ca0.3MnO3 perovskite and its composites with graphene nanoplatelet (GNP) were prepared using a wet chemical method. The structural, magnetic and magnetocaloric properties of La0.7Ca0.3MnO3: GNP composites were investigated to determine the effect of GNPs. The results of XRD analysis show that the synthesised powders can be almost indexed to pure phase orthorhombic La0.7Ca0.3MnO3. The magnetic measurements demonstrate that 0.7 and 1% GNP amounts cause an increase in the Curie temperature (TC), and for larger amounts of GNP, the TC monotonically decreases, except for the sample with 10% GNP. The results obtained from the Arrott plots show that the magnetic phase transition of the samples transforms from the first to second order with increasing GNP amount. The changes in the magnetocaloric properties are interpreted in terms of perovskite phase formations via structural analysis. The amounts of graphene nanoplatelets in the oxide powders are correlated with the observed magnetocaloric properties. The best magnetocaloric performance with the maximum magnetic entropy change of 3.99 Jkg?1K?1 and refrigeration capacity of 90 Jkg?1 was obtained at a 2?T magnetic field. 相似文献
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Demir AS Reis O Iğdir AC Esiringü I Eymur S 《The Journal of organic chemistry》2005,70(25):10584-10587
[reactions: see text] Acylphosphonates are potent acyl anion precursors that generate acyl anion equivalents under the promotion of cyanide anion via phosphonate-phosphate rearrangement. These anions readily react with aldehydes to provide cross-benzoin products. In this way it is possible to synthesize a variety of aromatic-aromatic, aromatic-aliphatic, and aliphatic-aromatic benzoins. Moreover the reaction of benzoylphosphonate with potent electrophile 2,2,2-trifluoroacetophenone provided the corresponding aldehyde-ketone coupling product in high yield. 相似文献
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The [2 + 2] cycloadditions of cyclopentyne and benzyne to ethylene are explored at the B3LYP and CASSCF levels, supplemented by CCSD(T) and CAS-MP2 calculations at the stationary points. The biradical path in the benzyne system is computed to be about 4.1 kcal/mol lower than the concerted path, consistent with the experimentally observed loss of original stereochemistry in this cycloaddition. However, computations fail to confirm the 99% stereoretention in the corresponding reaction of cyclopentyne. The concerted and biradical paths in the latter reaction are found to involve nearly isoenergetic barriers, thus predicting only about 75% stereoretention. More sophisticated theoretical methods seem to be needed to resolve the issue in the cyclopentyne system. 相似文献
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Photocatalytic Hydrogen Evolution by Oleic Acid‐Capped CdS,CdSe, and CdS0.75Se0.25 Alloy Nanocrystals
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Emre Aslan Okan Birinci Abdalaziz Aljabour Faruk Özel Ilker Akın Dr. Imren Hatay Patir Dr. Mahmut Kus Prof. Dr. Mustafa Ersoz 《Chemphyschem》2014,15(13):2668-2671
Photocatalytic generation of hydrogen by using oleic acid‐capped CdS, CdSe, and CdS0.75Se0.25 alloy nanocrystals (quantum dots) has been investigated under visible‐light irradiation by employing Na2S and Na2SO3 as hole scavengers. Highly photostable CdS0.75Se0.25 alloy nanocrystals gave the highest hydrogen evolution rate (1466 μmol h?1 g?1), which was about three times higher than that of CdS and seven times higher than that of CdSe. 相似文献
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This article describes the preparation of poly(ethylene glycol) (PEG) ‐based gels for removal of both organic solvents and water through a clean synthesis process without using any initiator, catalyst, activator, or liquid medium. The synthesis of the gels is based on the condensation of different molecular weights of PEG macromolecules with the nine‐functional crosslinker tris[3‐(trimethoxysilyl) propyl] isocyanurate (ICS). Solid‐state 13C and 29Si cross‐polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), and elemental analysis were used to characterize the prepared sorbents. Thermal properties of the synthesized sorbents were examined using thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The swelling capacities of the sorbents were determined by swelling tests in dichloromethane (DCM), tetrahydrofuran (THF), benzene, acetone, and toluene. The water absorbency of the PEG‐based sorbents is also investigated. The effect of the reaction time and reaction temperature on swelling features of the sorbents was studied systematically. The prepared PEG gels have high swelling ratios both in polar and nonpolar solvents. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Ilker Ugulu 《应用光谱学评论》2013,48(2):113-151
Abstract:Heavy metals are significant and extremely persistent environmental pollutants and their toxicity is a problem of increasing significance for ecological, nutritional, and environmental reasons. Biomonitoring methods are gaining more importance because they allow for prediction, detection, and control of potential environmental hazards caused by heavy metal pollution. The objective of the present study was to collect and analyze research on heavy metal accumulation in plant samples using spectrometric detection techniques in Turkey published between 2003 and 2013. Five main criteria were predetermined to limit the study and better portray the studies on heavy metal accumulation using plant samples in Turkey. These criteria were as follows: studies aiming to determine heavy metal accumulation levels, studies sampling plant species growing at various localities in Turkey, studies using spectrometric detection techniques, studies published as journal articles, and studies undertaken between 2003 and 2013. Consequently, 47 studies that satisfied all criteria were considered and selected for this investigation. A content analysis method was used for the review and analysis of the selected studies. The results of the review analysis were grouped under three categories and the findings obtained in this scope were presented. 相似文献