Aluminum, iron and zinc containing MCM-41 molecular sieves were prepared by the hydrothermal method. The catalyst was characterized by the XRD, BET (surface area), FT–IR and 29Si, 27Al MAS–NMR techniques. The catalytic activity of these molecular sieves was tested with esterification reaction used with phthalic anhydride (PAH) and methanol (MeOH) in the autoclave at 135 °C, 150 °C and 175 °C. Conversion increases with an increase in temperature and mole ratio. The activity of these catalysts followed the order: Al-MCM-41 (112) > Fe-MCM-41 (115) > Al-MCM-41 (70) > Al-MCM-41 (52) > Fe-MCM-41 (61) > Al, Zn-MCM-41 (104) > Al-MCM-41 (30). The reaction yielded both monomethyl phthalate (MMP) and dimethyl phthalate (DMP). The nature of the catalyst sites has been proposed using with water as an impurity. The selectivity of the dimethyl phthalate increases with increase in temperature and mole ratio. The weight of the catalyst was optimized at 0.07 g. The hydrophilic and hydrophobic nature of the catalyst has been explained by the influence of water and the external surface acidity also facilitates the reaction and this has been confirmed by the supporting reaction. 相似文献
The kinetics of oxidation of a number of meta- and para-substituted benzaldehydes by quinolinium fluorochromate, QFC has been studied in aqueous acetic acid medium in the presence of acid. The products of oxidation are the corresponding benzoic acids. The reaction is first order each in substrate, QFC and HClO4. Electron-withdrawing substituents increase the rate, while electron-releasing substituents decrease it and the rate data obey Hammett's relationship. The reaction constant for the oxidation has a value of 1.16±0.07 at 30°C. The activation enthalpies and entropies are calculated and the possible mechanism for oxidation is discussed. 相似文献
The synthesis of substituted imidazolium-type ionic liquids via a simple method is described. Our synthesized ionic liquids are more useful in the catalytic behavior of the Mannich reaction. 相似文献
The present study was carried out to understand the effect of cortisol on caspase expression in the C2C12 and 3 T3-L1 cells under co-culture system. Cells were co-cultured by using transwell inserts with a 0.4-μm porous membrane to separate C2C12 and 3 T3-L1 preadipocyte cells. Each cell type was grown independently on the transwell plates. Following cell differentiation, inserts containing 3 T3-L1 cells were transferred to C2C12 plates and inserts containing C2C12 cells were transferred to 3 T3-L1 plates. A total of 10 μg/μl of cortisol was added to the medium. Following treatment of cortisol for 3 days, the cells in the lower well were harvested for analysis. Caspases such as caspase 3, caspase 7, and caspase 9 were selected for the analysis. qRT-PCR results indicated the significant increase in the mRNA expression of caspase 3, caspase 7, and caspase 9. Caspase 3, 7, and 9 activities were also increased in the mono- and co-cultured C2C12 and 3 T3-L1 cells. In addition, confocal microscopical investigation indicated that cortisol increases caspase expressions in the mono- and co-cultured C2C12 and 3 T3-L1 cells. Taking all these together, we concluded that the co-culture system reflects the exact effect of cortisol on caspase expression, which is quite distinct from one dimensional mono-cultured experiments. 相似文献
In this paper, a facile immobilization of copper hexacyanoferrate nanoparticles (CuHCFNP) on a paraffin wax-impregnated graphite electrode (PIGE) was carried out using the room-temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) as an ionic binder. The characteristics of the CuHCFNP/EMIMBF4 gel-modified electrode were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques, and the modified electrode morphology was also characterized using field emission scanning electron microscopy (FESEM). The electrocatalytic behavior of butylated hydroxyl anisole (BHA) at the modified electrode has been investigated in 0.1 M KNO3 in static and dynamic conditions. Under the optimum conditions, the oxidation peak current was proportional to the BHA concentration in the range from 1.5 to 1000 μM with a detection limit of 0.5 μM (S/N = 3). The proposed method was applied to determine BHA content in real samples with satisfactory results.
Thermostable xylanase isoforms T70 and T90 were purified and characterized from the xerophytic Opuntia vulgaris plant species. The enzyme was purified to homogeneity employing three consecutive steps. The purified T70 and T90 isoforms yielded a final specific activity 134.0 and 150.8 U mg?1 protein, respectively. The molecular mass of these isoforms was determined to be 27 kDa. The optimum pH for the T70 and T90 xylanase isoforms was 5.0 and the temperature for optimal activity was 70 and 90 °C, respectively. The Km value of T70 and T90 enzyme isoforms was 3.49, 2.1 mg ml?1, respectively when oat spelt xylan was used as a substrate. The T70 had a Vmax of 10.4 μmol min?1 mg?1, and T90 had a Vmax of 8.9 μmol min?1 mg?1, respectively. In the presence of 10 mM Co2+, and Mn2+ the activity of T70 and T90 isoforms increased, where as 90 % inhibition was noted with of the use 10 mM Hg2+, Cd2+, Cu2+, Zn2+ while partial inhibition was observed in the presence of Fe3+, Ni2+, Ca2+and Mg2+. The T70 and T90 isoforms retained nearly 50 % activity in the presence of 2.0 M urea, while use of 40 mM SDS lowered the activity nearly 38–41 %. The substrate specificity of both T70 and T90 isoforms showed maximum activity for oat spelt xylan. Western blot, immunodiffusion, and in vitro inhibition assays confirmed reactivity of the T90 isoform with polyclonal anti-T90 antibody raised in rabbit, as well as cross-reactivity of the antibody with the T70 xylanase isoform. 相似文献
Plant gums are bio-organic substances that are derived from the barks of trees. They are biodegradable and non-adverse complex polysaccharides that have been gaining usage in recent years due to a number of advantages they contribute to various applications. In this study, gum was collected from Moringa oleifera and Azadirachta indica trees, then dried and powdered. Characterizations of gum polysaccharides were performed using TLC, GC-MS, NMR, etc., and sugar molecules such as glucose and xylose were found to be present. Effects of the gums on Abelmoschus esculentus growth were observed through root growth, shoot growth, and biomass content. The exposure of the seeds to the plant gums led to bio stimulation in the growth of the plants. Poor quality soil was exposed to the gum polysaccharide, where the polysaccharide was found to improve soil quality, which was observed through soil analysis and SEM analysis of soil porosity and structure. Furthermore, the plant gums were also found to have bio-pesticidal activity against mealybugs, which showed certain interstitial damage evident through histopathological analysis. 相似文献