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141.
Hossein Reza Darabi Ehsan Khatamifar Ali Sharifi Kioumars Aghapoor Khosrow Jadidi 《合成通讯》2017,47(5):428-434
The McMurry coupling of a bis-salisaldehyde 3a with methyl linker as the smallest member of its alkyl series is known to give the remarkably lower yield of the corresponding stilbenophanes. The half part of this molecule, unlike bigger analogues, is a good leaving group which affordsthreo isomer of 4H, 4′H–4,4′-bibenzo[d][1,3]dioxine 4 in high diastereoisomeric ratio (99>). A further study showed that the formation of this key by-product is the reason for formation of other by-products, namely, 5a,10b-dihydrobenzofuro[2,3-b]benzofuran 9 and 2-(2,3-dihydrobenzofuran-2-yl)phenol 10. Two reaction pathways for the formation of by-products have been proposed which are responsible for the unusual activity of dialdehyde 3a. 相似文献
142.
A New Method for Predicting Decomposition Temperature of Imidazolium‐based Energetic Ionic Liquids
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Two novel correlations are introduced to predict decomposition temperatures of imidazolium‐based energetic ionic liquids. The first simple model is based only on the number of some of atoms in cationic and anionic structures. Meanwhile, a suitable correction term was added in the second correlation to adjust the predicted results for the presence of some specific cation/anion moieties. The measured data of 164 different types of imidazolium‐based energetic ionic liquids were used to derive the new correlations. The calculated mean absolute percent errors (MAPEs) of the first and second models are 6 and 4, respectively. The predicted results have confirmed that insertion of correcting function in the second correlation can provide better estimations. These models were also tested and compared with one of the best available group contribution methods, where group contribution method can be applied, for 17 further imidazolium‐based energetic ionic liquids containing complex molecular structures. Furthermore, the predicted values of MAPEs of the new models are close to that of obtained by group contribution method. 相似文献
143.
Samaneh Soloukipour Ehsan Saljoughi Seyed Mahmoud Mousavi Mahdi Pourafshari Chenar 《先进技术聚合物》2017,28(1):113-123
In the present research, novel polyether block amide (PEBA)/polyvinyldene fluoride (PVDF) blend pervaporation (PV) membranes were prepared for the removal of isopropyl alcohol (IPA) from the aqueous solution. The membranes obtained at PEBA/PVDF ratios of 100/0, 95/5, and 90/10 were characterized using scanning electron microscopy, thermogravimetric analysis, water contact angle measurement, and tensile test. Moreover, the PV performance of the membranes was assessed via separation of IPA from the aqueous solution. The blended membranes exhibited higher hydrophobicity and separation factor as well as lower permeability in comparison with the pure PEBA membrane. The blended membrane that was prepared at PEBA/PVDF ratio of 95/5 was found as the optimum membrane providing PV separation index of 3171 that appeared to be the maximum value. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
144.
Adsorption of NH3 and NO2 molecules on C48B6N6 heterofullerene: A DFT study on electronic properties
Adsorption of NH3 and NO2 molecules on the external surface of C48B6N6 heterofullerene is investigated using DFT method. Attachment of NH3 and NO2 on C48B6N6 heterofullerenes are compared with the bare C48B6N6 model optimized at the B3LYP/6-31G? level. The high surface binding energies indicates that ammonia undergoes chemical adsorption and could be compatible with the long recovery time but C48B6N6 should be good NO2 sensors with quick response as well as short recovery time. Total (TDOS) and partial (PDOS) density of state calculations is also considered to elucidate the difference in the NH3 and NO2 gas detection mechanism of C48B6N6. The overlap population density of state (OPDOS) indicated that the chemical adsorption is due to the overlap of atomic orbitals below the Fermi level. The calculated results suggest that the C48B6N6 heterofullerene is a suitable sensor material for NO2 and is an ideal material for elimination and filtering of ammonia. 相似文献
145.
Matsui K Nazifi E Kunita S Wada N Matsugo S Sakamoto T 《Journal of photochemistry and photobiology. B, Biology》2011,105(1):81-89
Mycosporine-like amino acids (MAAs) are UV absorbing pigments, and structurally distinct MAAs have been identified in taxonomically diverse organisms. Two novel MAAs were purified from the cyanobacterium Nostoc commune, and their chemical structures were characterized. An MAA with an absorption maximum at 335 nm was identified as a pentose-bound porphyra-334 derivative with a molecular mass of 478 Da. Another identified MAA had double absorption maxima at 312 and 340 nm and a molecular mass of 1,050 Da. Its unique structure consisted of two distinct chromophores of 3-aminocyclohexen-1-one and 1,3-diaminocyclohexen and two pentose and hexose sugars. These MAAs had radical scavenging activity in vitro; the 1050-Da MAA contributed approximately 27% of the total radical scavenging activities in a water extract of N. commune. These results suggest that these glycosylated MAAs have multiple roles as a UV protectant and an antioxidant relevant to anhydrobiosis in N. commune. 相似文献
146.
Ehsan Bafekrpour George P. Simon Chunhui Yang Jana Habsuda Minoo Naebe Bronwyn Fox 《Journal of Thermal Analysis and Calorimetry》2012,109(3):1169-1176
Synthetic graphite?Cphenolic nanocomposites were designed and synthesized with a compositional gradient which is shown to influence transient temperature fields during rapid temperature changes. Such nanocomposites were fabricated using a compression moulding technique, and thermal conductivity and heat capacity of nanocomposites were experimentally determined using a modified transient plane source technique over a wide temperature range from 253.15 to 373.15?K. The effects of four compositional gradient configurations on the transient temperature field across the thickness of a nanocomposite plate, at a high imposed temperature, was investigated. The transient time and temperature fields in nanocomposite structures were highly affected by the compositional gradient configurations. 相似文献
147.
Md. Mahmudul Hasan Md. Elius Hossain M.A. Mamun M.Q. Ehsan 《Journal of Saudi Chemical Society》2012,16(2):145-151
The redox behavior of Cd(II) and the interaction of Cd(II) with cyclic amino acid, proline, have been studied in 0.1 M KCl, 0.1 M NaClO4 and acetate buffer of different pH. The CVs were recorded at glassy carbon electrode within the potential window 200 and ?1500 mV. The reference and counter electrode used were Ag/AgCl and Pt wire, respectively. The cyclic voltammograms show one pair of cathodic and anodic peaks for the Cd(II)/Cd(0) system indicating the involvement of two electron transfer processes. The peak potential shift and charge transfer rate constant (kf) values strongly support the interaction between metal and ligand. The higher value of peak current ratio and peak potential separation (ΔE) indicate that the systems are quasireversible. The effect of supporting electrolyte and concentration of electro active species on the interaction were also studied. 相似文献
148.
We have developed a new method for the preparation of unsymmetrical imides using liquid carboxylate salts via a Ritter-type process. The reactions were carried out with nitriles and n-butylammonium carboxylates as ionic liquids in the presence of triflic anhydride (Tf2O) as the promoter. Mild reaction conditions, simplicity of the procedure, and proton-free conditions are the main advantages of this procedure. 相似文献
149.
Ehsan Ghazanfari Sibel Pamukcu Mesut Pervizpour Zuleima Karpyn 《Transport in Porous Media》2014,105(1):235-253
Evaluation of relative permeability coefficients is one of the key steps in reliable simulation of two-phase flow in porous media. An extensive body of work exists on evaluation of these coefficients for two-phase flow under pressure gradient. Oil transport under an applied electrical gradient in porous media is also governed by the principles of two-phase flow, but is less understood. In this paper, relative permeability coefficients under applied electric field are evaluated for a specific case of two- phase fluid flow in water-wet porous media, where the second fluid phase is oil. It is postulated that the viscous drag on the oil phase, exerted by the electro-osmotic flow of the water phase, is responsible for the transport of oil in the absence of a pressure gradient. Reliable prediction of the flow patterns necessitates accurate representation and determination of the relative permeability coefficients under the electrical gradient. The contribution of each phase to the flow is represented mathematically, and the relative permeability coefficients are evaluated through electro-osmotic flow measurements conducted on oil bearing rock cores. 相似文献
150.
Ehsan Momtahan 《代数通讯》2013,41(11):4167-4171
A well-known result by Y. Utumi states: Every right or left self-injective ring is von Neumann regular modulo its Jacobson radical. In this note, we give an example of a commutative ?0-self-injective ring which is not von Neumann regular modulo its Jacobson radical. 相似文献