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61.
Influence of atmospheric air plasma treatment on performance of nanoemulsion silicone softener on polyethylene terephthalate fibers was investigated by the use of fourier transform infrared spectroscopy (FTIR), bending lengths (BL), wrinkle recovery angles (WRA), fiber friction coefficient analysis (FFCA), moisture absorbency (MA), scanning electron microscopy (SEM) and reflectance spectroscopy (RS). Results indicated that the plasma pretreatment modifies the surface of fibers and increases the reactivity of substrate toward nanoemulsion silicone. Moisture regain and microscopic tests showed that the combination of plasma and silicone treatments on polyethylene terephthalate can decrease moisture absorption due to uniform coating of silicone emulsion on surface of fibers. 相似文献
62.
Superbases DBU, DBN, TMG and MTBD are efficient catalysts which have been used in the solvent-free conversion of carbon dioxide and 2-aminobenzonitrile to quinazoline-2,4(1H, 3H)-diones. For the final product, four tautomeric forms have been considered which the stability of the preferred tautomer has been studied by NBO analysis. In this research, two different mechanisms have been proposed for the catalytic behavior of the superbases which can act as a base or a nucleophile in the reaction. Theoretical studies show that two primary steps are the rate-determining step (RDS) of the mechanism. QTAIM analysis and local nucleophilicity index were used for investigation of the molecular aspects of the RDSs. Finally, it has been confirmed the basic role of the applied superbases is more important than nucleophilicity and DBU is the best candidate as an efficient catalyst for this reaction. 相似文献
63.
Alireza Asghari Anahita Gholami Mohammad Bakherad Mohsen Ameri 《Journal of the Iranian Chemical Society》2017,14(10):2127-2133
In this work, the electrochemical oxidation of catechols 1a and 1b was studied in the presence of pyrazolidine-3,5-dione (3a), as a nucleophile, in a mixture of ethanol and a phosphate buffer solution (0.1 M, pH 7), as a green medium, using the cyclic voltammetry and controlled-potential coulometry techniques. The results obtained indicated that the oxidized forms of these catechols (2a and 2b) participated in the Michael addition reactions with pyrazolidine-3,5-dione (3a), and converted, via an ECEC mechanism, to their corresponding benzofurans (7a and 7b). In this work, some new benzofuran derivatives were synthesized with good yields and high purities using a facile, one-pot, and environmentally friendly electrochemical method in the absence of any chemical catalyst, toxic solvent, and hard conditions. 相似文献
64.
An efficient and green method for the synthesis of phthalide [isobenzofuran-1(3H)-one] fused pyrazoles via the catalyst-free condensation reaction of 2-formylbenzoic acid, hydrazine hydrate, and acetylenic esters in water is reported. Reaction of 2-formylbenzoic acid with 6-amino-uracils or cyclic 1,3-diketones resulted in the formation of phthalide-fused pyrimidine or cyclic 1,3-diketone derivatives. 相似文献
65.
Mani A Huisman C Goossens A Schoonman J 《The journal of physical chemistry. B》2008,112(33):10086-10091
Schottky junctions have been realized by evaporating gold spots on top of sexithiophen (6T), which is deposited on TiO 2 or ZnO with e-beam and spray pyrolysis. Using Mott-Schottky analysis of 6T/TiO2 and 6T/ZnO devices acceptor densities of 4.5x10(16) and 3.7x10(16) cm(-3) are obtained, respectively. For 6T/TiO2 deposited with the e-beam evaporation a conductivity of 9x10(-8) S cm(-1) and a charge carrier mobility of 1.2x10(-5) cm2/V s is found. Impedance spectroscopy is used to model the sample response in detail in terms of resistances and capacitances. An equivalent circuit is derived from the impedance measurements. The high-frequency data are analyzed in terms of the space-charge capacitance. In these frequencies shallow acceptor states dominate the heterojunction time constant. The high-frequency RC time constant is 8 micros. Deep acceptor states are represented by a resistance and a CPE connected in series. The equivalent circuit is validated in the potential range (from -1.2 to 0.8 V) for 6T/ZnO obtained with spray pyrolysis. 相似文献
66.
Ahmad Reza Massah Roozbeh Javad Kalbasi Anahita Shafiei 《Monatshefte für Chemie / Chemical Monthly》2012,141(10):643-652
Abstract
ZSM-5 has been modified as supported sulfuric acid (ZSM-5-SO3H) and introduced for the first time as a mild, convenient, reusable, and heterogeneous catalyst. Various types of aldehydes were efficiently converted to their 1,1-diacetates using a catalytic amount of ZSM-5-SO3H in excellent yields under solvent-free and heterogeneous conditions at room temperature. The deprotection of 1,1-diacetates has also been achieved using this novel catalyst in ethanol. The procedure is operationally simple, environmentally benign, and only a stoichiometric amount of anhydride is used. 相似文献67.
Alain Friboulet Ladan Izadyar Berangere Avalle Alberto Roseto Daniel Thomas 《Applied biochemistry and biotechnology》1994,47(2-3):229-239
Since the two reports published in 1986 by the laboratories of R. Lerner and P. G. Schultz, it has been clearly established
that antibodies may be induced to act as catalysts in numerous chemical reactions. In all cases, catalytic antibodies were
elicited using a substratebased approach. In the present article, we propose an alternative and complementary enzyme-based
approach to generate catalytic antibodies. This approach uses the properties of anti-idiotypic antibodies to generate internal
images of enzyme active sites. Experimental results are discussed for polyclonal and monoclonal anti-idiotypic antibodies. 相似文献
68.
A combination of the experimental and theoretical study was carried out on the reaction mechanism associated with the pyrolysis of 2-pyridylacetic acid in the gas phase. Methylpyridine and carbon dioxide were analyzed as the products, using a static system over the pressure range of 18–55 torr and the temperature of 541.2–583.4 K. The experimental kinetic data show that the pyrolysis process is homogeneous, unimolecular and proceeds through a concerted mechanism. Theoretical studies at the B3LYP level using the 6-31G* basis set confirmed an asynchronous concerted mechanism for the reaction. Computed kinetic and activation parameters are in good agreement with the experimental one. 相似文献
69.
70.
Samira Sabagh Mohammad Izadyar Foroogh Arkan 《International journal of quantum chemistry》2020,120(10):e26171
The molecular modification and the effects of the gas and water media on the ability of some flavonoids as the photosensitizers in the natural dye-sensitized solar cells were theoretically investigated. According to the results, water increases the electrophilicity of the dyes and weakens the dye/TiO2 coupling, prohibiting the electron injection toward TiO2. A longer path for charge transfer and a less electron-hole overlap for dihydroxychromens elevate the electron transfer more efficient than trihydroxychromen-based flavonoids. However, the presence of water molecules within an increment in the OH groups in the flavonoid structures improves their spectroscopic properties, which is related to decrement in the gap of the frontier molecular orbitals and increment in the oscillator strength. Also, such favorable structural effects and influence of the water medium on the polarizability and excited-state lifetime have emerged. According to the energy conversion efficiency, water is a favorable solvent for dihydroxychromen-based flavonoids. Finally, different analyses on the structural geometries, excited-state, lifetime within the kinetics, and dynamics of the photovoltaic processes were performed and discussed. 相似文献