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排序方式: 共有87条查询结果,搜索用时 31 毫秒
1.
K. C. Swallow K. Taghizadeh S. Weakland E. F. Plummer W. F. Busby Jr A. L. Lafleur 《International journal of environmental analytical chemistry》2013,93(2-4):113-122
Abstract We have studied the photooxidation of selected polycyclic aromatic hydrocarbons (PAH) in the presence of Ti(IV)oxide in a mixed solvent system consisting of N-methylpyrrolidinone (NMP) and water. Reaction rates for the photooxidation of acenaphthylene and pyrene were investigated by monitoring the disappearance of the PAH substrate from the reaction mixture as a function of time. For both compounds plots of In Co/Ct, as a function of time yielded straight lines, indicating first order kinetics with respect to the substrate. With an initial acenaphthylene concentration of 1.0 gL?1 the first order reaction rate constant was 0.19 hr?1 and the half life was 3.7 hr. With an initial pyrene concentration of 0.2 gL?1 the first order reaction rate constant was 0.0285 hr?1 and the half life was 24 hr. The photoproducts were characterized by high performance liquid chromatography with diode-array detection (HPLC/DAD) and by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (APCI/LC-MS). Although a number of simple oxidation products were identified the bulk of the photoproducts consisted of the parent PAH substituted with one or more solvent (NMP) molecules. The product mixtures from the photooxidation of the non-mutagens acenaphthylene and pyrene were found to be also non-mutagenic in our Salmonella typhimurium forward mutation assay. 相似文献
2.
3.
Mohammad Javad Taghizadeh Hamid ArvinnezhadSaadi Samadi Khosrow Jadidi Abdollah JavidanBehrouz Notash 《Tetrahedron letters》2012,53(38):5148-5150
An efficient, one-pot, three-component procedure for the synthesis of a small library of new chiral spirooxindolopyrrolizidines with high regio-, diastereo-, and enantioselectivity, from the 1,3-dipolar cycloaddition of azomethine ylides and optically active cinnamoyl oxazolidinone is described. The process occurs at room temperature in aqueous ethanol as a green solvent and in the absence of any Lewis acids. The oxazolidinone chiral auxiliary is removed in a non-destructive manner. The reaction mechanism is discussed on the basis of the assignment of the absolute configuration of the cycloadducts, and on theoretical calculations. 相似文献
4.
N. Taghizadeh V. S. Mohammadi 《Journal of Contemporary Mathematical Analysis (Armenian Academy of Sciences)》2017,52(2):61-69
In this article, the Green and Neumann functions are given for a half lens and the Dirichlet and Neumann problems for Poisson equation are solved. All formulas are given in explicit form. 相似文献
5.
Synthesis and computational study of two new glycoluril clips containing benzocrown ether side walls
Esmail Rezaei-Seresht Sirous Salemi Mahnaz Ahmadi Sara Taghizadeh 《Journal of inclusion phenomena and macrocyclic chemistry》2013,76(1-2):69-74
Two new glycoluril-derived molecular clips containing benzocrown ether side walls have been synthesized via reaction of a glycoluril scaffold with two bromomethylated benzocrown ethers. The molecular geometry of their most stable structures were investigated with density functional theory at the B3LYP level of theory using STO-3G, 6-31G, and 6-311G basis sets. Then based on the obtained computer-optimized structures, the binding properties of one clip with some 5-substituted resorcinols have been calculated. 相似文献
6.
Esmail Rezaei-Seresht Sirous Salemi Sara Taghizadeh Mehri Ghorbani 《Journal of inclusion phenomena and macrocyclic chemistry》2013,77(1-4):403-411
Several new clip-shaped molecules, with different degrees of steric hindrance around their cavities as well as more rigidity on their glycoluril scaffold, have been synthesized and the molecular geometry of their most stable structures has been investigated and optimized with density functional theory (DFT) at the B3LYP level of theory using 6-311G basis set. The affinity of these molecular clips for some dihydroxybenzene derivatives (guests) has been computationally and experimentally studied. The clips having dimethyl-substituted aromatic side walls, showed the best interaction energies towards the mentioned guests. Also, the computational results revealed that the more electron-deficient guest interacts more strongly with the clips (hosts). 相似文献
7.
Mohammad Taghi Taghizadeh Nazanin Yeganeh Mostafa Rezaei 《Journal of Thermal Analysis and Calorimetry》2014,118(3):1733-1746
A peak deconvolution procedure used for the analysis of data corresponding to simultaneous overlapping processes begins with separation of individual processes using functions such as Gaussian, Lorentzian, Weibull, and Fraser–Suzuki (FS) followed by application of kinetic analysis methods to the separated peaks. We propose a coupled peak deconvolution procedure to link the parameters of the FS functions of similar peaks in two DTG curves obtained at different linear heating rates, so that the coordinates of each peak can be obtained in a constrained manner. The proposed technique is a kinetic deconvolution method rather than a pure mathematical deconvolution technique. To analyze individual peaks in our study, the non-parametric kinetic and Freidman’s isoconversional methods have been applied to determine kinetic triplet of each process. This technique has been tested with both simulated and experimental data. Using this technique, the effects of molecular weight and degree of hydrolysis of polyvinyl alcohol (PVA) samples on reaction mechanism and activation energy of thermal degradation were studied. The presence of acetate group in the PVA samples causes thermal stability, decreases the rate of main reactions, and increases the activation energy. The results of this study may help tailor heat-resistant materials with proper choice of polymer characteristics. 相似文献
8.
Sacconi L Froner E Antolini R Taghizadeh MR Choudhury A Pavone FS 《Optics letters》2003,28(20):1918-1920
Multiphoton multifocal microscopy (MMM) usually has been achieved through a combination of galvo scanners with microlens arrays, with rotating disks of microlens arrays, and cascaded beam splitters with asynchronous rastering of scanning mirrors. Here we describe the achievement of a neat and compact MMM by use of a high-diffraction-efficiency diffractive-optic element that generates a multiple-spot grid of uniform intensity to achieve higher fidelity in imaging of live cells at adequate speeds. 相似文献
9.
M. R. Taghizadeh P. Blair K. Ballü der A. J. Waddie P. Rudman N. Ross 《Optics and Lasers in Engineering》2000,34(4-6):289-307
Diffractive optical elements have an important role to play in the provision of process adapted beam shaping for laser-materials processing applications. The design techniques and dominant methods of fabrication are described for intra-cavity and external beam shaping diffractive elements fabricated in a variety of dielectric and metallic materials for use with a wide range of laser sources. Theoretical and experimental examples are given in each section. 相似文献
10.
Robabeh Baharfar Mohammad Javad Taghizadeh Majid Ahmadian Seyed Meysam Baghbanian 《中国化学快报》2010,21(2):175-178
<正>The addition of 2,4-dihydroxyaceto(and benzo)phenone to propiolic ester is catalyzed by triphenylphosphine or tert-butyl isocyanide to form O-vinyl aryl derivatives in fairly good yields. 相似文献