查看更多>>摘要：Theoretical study of several O-nitrosyl carboxylate compounds have been performed using quantum computational ab initio RHF and density functional B3LYP and B3PW91 methods with 6-31G** basis set.Geometries obtained from DFT calculations were used to perform the natural bond orbital (NBO) analysis. It is noted that weakness in the O3-N2 bond is due to no1 →σ*O3-N2 delocalization and is responsible for the longer O3-N2 bond lengths in O-nitrosyl carboxylate compounds. It is also noted that decreased occupancy of the localized σo3-N2 orbital in the idealized Lewis structure,or increased occupancy of σo3-N2 of the non-Lewis orbital, and their subsequent impact on molecular stability and geometry (bond lengths) are related with the resulting p character of the corresponding sulfur natural hybrid orbital (NHO) of σo3-N2 bond orbital. In addition, the charge transfer energy decreases with the increase of the Hammett constants of subsitutent groups.
查看更多>>摘要：ZrO2 toughened Al2O3 (Al2O3/ZrO2) ceramic layers with required thickness were prepared by electrophoretic deposition (EPD) method using ethanol suspensions with stabilizing agent of polyethyleneimine (PEI) under constant-voltage mode in this paper. The deposition of Al2O3/ZrO2 ceramic powders occurred on the titanium alloy cathode. A stable suspension with 1wt% PEI in ethanol at pH 5 was prepared in terms of the zeta potential and sedimentation of the suspension.The effects of the suspension concentration, applied voltage, deposition time and processing method of titanium alloy cathode on the coating thickness and morphology were investigated. The deposition layers on titanium alloys with smooth surfaces and thickness of 0.35-1.2mm could be obtained by adjusting the aforementioned parameters. In addition, after being sintered at 1500℃ for 3 h in air atmosphere, ZrO2 toughened A12O3 ceramic layers became smooth and dense.
查看更多>>摘要：This article describes the potential of KMnO4 for oxidation of the thiazine dye (Toluidine blue TB) in an acidic medium. The effect of different operational parameters like initial concentration of dye, potassium permanganate, pH, ionic strength, catalyst, acids and temperature were investigated spectrophotometrically at λmax ＝ 613 nm. The results showed a complete removal of the TB with mineralization of the dye solution. Smooth and complete decoloration was observed in the presence of monobasic acid (HCi) as compared to the H2SO4 where little color removal was observed. Pb was found to be an effective catalyst in oxidation for complete and fast decolorization with mineralization. No significant change at elevated temperatures showed that an intermediate complex degraded with slight change in the temperature. UV/visible spectrophotometry and GC mass analysis showed an intermediate activated complex demethylated sulophooxide of TB which later on degraded into smaller fragments.
Asadollah FARHADIMohammad Ali TAKASSIHamid Reza MEMARIANMousa SOLEYMANI...
91-97页
查看更多>>摘要：Density functional theory (DFT) calculations were carried out on some cyclohexane derivatives to investigate the deviation atoms on the 1- and 4-positions of chair plane. The deviations of chair plane of two position in the cyclohexane derivatives were calculated at the B3LYP/6-31 ++ G(d,p) level. Furthermore, we investigated the correlation between deviations of two positions from chair plane on the chemical shift hydrogen atoms on the 4-position.
查看更多>>摘要：Coordination compounds of modified diamine, the basic unit of which are ethylenediamine, with that of Co (Ⅱ)are prepared. The modified diamines are ethylenedia-ceticacid (EDDA) and N,N,N,N-tetaraethylene-1,2-diamine (TEEDA). These diamines are characterized through 1H-NMR, 13C-NMR, elemental analysis and IR techniques. Cobalt (Ⅱ) complexes of these two ligands were prepared and characterized by physical measurements including elemental analysis, IR, UVVisible, magnetic susceptibilities and conductance measurements. Antibacterial activities are also carried out in order to investigate the biological activity upon complexation. They were screened against four pathogenic bacteria like Escherichia coli, Pseudononas aeroginosa,Klesbella pneumonia and Staphylococcus aureus. The results showed significant enhancement in activities.
Muhammad SULTANHajira TAHIRKhalid AHMEDQazi JAHANZEB...
105-112页
查看更多>>摘要：The kinetics of the reaction of Fast Green dye (FG) with cetylpyridinum chloride was studied in alkaline medium by UV-Visible spectrophotometer. Reduction of Fast Green dye was carried out by varying the fast green dye concentration, cetylpyridinum chloride concentration and concentration of sodium hydroxide. In the present study the reduction of dye was carried out in order to reduce the color content. The interaction of dye was carried out with reducing analyte (cetylpyridinum chloride). The rate of the reaction was determined by varying the above parameters at different temperatures. It was observed that the reduction followed pseudo first-order kinetics with respect to dye, surfactant, OH- ion concentration according to the following reaction pathway.The mechanism for the photo bleaching of the dye has been proposed and well confirmed by the data simulation procedure. The activation parameters of the reaction like entropy of activation (AS) and free energy of activation (AG) showed the extremely solvated states of transient complex which was less disorderly arranged than the oxidized form of dye, whereas Ea values reflects a high amount of energy required for the reduction of dye with cetyipyridinum chloride.
查看更多>>摘要：The effects of CuCl2 and ZnCl2 on the viscosity in aqueous ethanol mixtures (10％-50％ v/v) were studied in the concentration range 1.0 × 10-2-8.0 × 10-2 mol· dm-3at different temperatures. It was found that the viscosities increased with an increase in the concentration of the salts and percent composition of ethanol content, whereas it decreased with an increase in temperature. Ion-ion and ion-solvent interactions are determined with the help of A- and B-coefficients of Jones-Dole equation. The values of A- and B-coefficients are irregular and increase with a rise in temperature and also with an increase in ethanol contents for both salts. Negative values of B-coefficients show that ion solvent interactions is comparatively small and suggest that CuCl2 and ZnCl2 behave as structure breakers in aqueous ethanol mixtures. Thermodynamic parameters like the energy of activation (Eη) and change in entropy of activation (△S*) were also evaluated which confirm the structure breaker behavior of salts in aqueous ethanol mixtures.
查看更多>>摘要：An investigation of the thionine sensitized aerobic photooxidation of thiourea was observed spectropho-tometrically at a wavelength of 598 nm. Articles reported two types of reactions which generally occur in the presence of oxygen: 1) Singlet oxygen, produced by dye sensitization due to the hydrolysis that reacts with thiourea to form oxidative products like urea and other sulfur-containing fragments and 2) bleaching of dye, which leads to the reduction. The rate of reaction in all studied parameters followed first order kinetics with respect to maximum absorption of the dye in the visible band region. Reaction kinetics was significantly dependent upon the medium and the reaction accelerated more rapidly at low pH. A direct relation was exhibited between the thiourea concentration and dye sensitizer,which was not pragmatic with the concentration of dye.The reaction was effected by the temperature, and the values of energy parameters suggested that the energy of activation was low while the entropy of activation increases with the rise in temperature, which indicated a highly solvated state of intermediate complex. Lower value of AH* and AG* at elevated temperature showed that free energy is the driving force for the completion of reaction. A mechanism based on the above findings has been suggested.
查看更多>>摘要：The well recognized model potential is used to investigate the vibrational properties of four Fe-based binary glassy alloys viz. Fe90Zr10, Fes0B20, Fes3B17 and Fe80P20. The thermodynamic and elastic properties are also computed from the elastic limits of the phonon dispersion curves (PDC). Three theoretical approaches given by Hubbard-Beeby (HB), Takeno-Goda (TG) and Bhafia-Singh (BS) are used in the present study to compute the PDC. Six local field correction functions proposed by Hartree (H), Taylor (T), lchimaru-Utsumi (IU), Farid et al. (F) and Sarkar et al. (S) and Sarkar et al.'s local field factor (SLFF) based excgange and correlation function are employed to see the effect of exchange and correlation in the aforesaid properties.
查看更多>>摘要：In the present study, the density functional theory (DFT) and Gibbs free energy calculations were performed to investigate the stability and tautomerism of C4-substituted-3,4-dihydropyrimidin-2(1H)-ones.Three different forms are possible for the ethyl 3,4-dihydropyrimidinones (ethyl 4-aryl-6-methyl-3,4-dihy-dropyrimidin-2(1H)-one-5-carboxylates, ethyl 4-aryl-2-hydroxy-6-methyi-1,4-dihydropyrimidine-5-carboxyiates and ethyl 4-aryi-2-hydroxy-6-methyl-3,4-dihydro-pyrimidine-5-carboxylates) forms that the most stable form is ethyl 4-aryl-6-methyl-3,4-dihydropyrimidin-2 (1H)-one-5-carboxylates (keto-form). The obtained data showed that the substitution on the C4-substitut position can be effective on the equilibrium constant (Keq).
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