The possibility of dehydration (cross-linking) of polyvinyl alcohol upon microwave irradiation of thin polymer films was examined. The properties of polyvinyl alcohol samples treated by convection heating and irradiation were compared. Immobilization of polyvinyl alcohol on polymer matrices by microwave irradiation was studied. 相似文献
The synthesis of composite sorbents from porous silica modified by polyvinyl alcohol was studied. The initial silica retained its porosity after modification which was performed by application of polyvinyl alcohol from aqueous solution. The subsequent thermal or microwave treatment gave nanolayers of water-resistant polyvinyl alcohol. Microwave irradiation was found to be more advantageous than conventional thermal treatment from the viewpoint of the polymeric phase and sorbent parameters. Sorption properties of the resulting sorbents with respect to protein, oligonucleotide, and dyes were studied. 相似文献
The work describes the accelerated enzymatic digestion of several proteins in various solvent systems under microwave irradiation. The tryptic fragments of the proteins were analyzed by matrix-assisted laser desorption/ionization mass spectrometry. Under the influence of rapid microwave heating, these enzymatic reactions can proceed in a solvent such as chloroform, which, under traditional digestion conditions, renders the enzyme inactive. The digestion efficiencies and sequence coverages were increased when the trypsin digestions occurred in acetonitrile-, methanol- and chloroform-containing solutions that were heated under microwave irradiation for 10 min using a commercial microwave applicator. The percentage of the protein digested under microwave irradiation increased with the relative acetonitrile content, but decreased as the methanol content was increased. These observations suggest that acetonitrile does not deactivate the enzyme during the irradiation period; in contrast, methanol does deactivate it. In all cases, the digestion efficiencies under microwave irradiation exceed those under conventional conditions. 相似文献
Human urotension-Ⅱwas synthesized efficiently on Wang resin under microwave irradiation using Fmoc/tBu orthogonal protection strategy.Disulphide bridge was formed on solid phase with the irradiation of microwave,then the whole peptide was cleaved from the resin.The purity of crude peptide cyclized under microwave irradiation was higher than that under room temperature. 相似文献
The polycondensation of D ,L ‐lactic acid upon microwave irradiation was studied. The results of polycondensation by means of microwave were compared to those obtained from conventional heating of lactic acid at 100°C, and it was found that the reaction proceeds with much higher rate upon microwave irradiation. The oligomer mixtures formed were investigated by means of matrix‐assisted laser desorption/ionization mass spectrometry (MALDI MS). The molecular mass of the poly(lactic acid) formed under microwave irradiation was found to increase with irradiation time, and the formation of cyclic oligomers after 20 min of reaction time was also revealed. 相似文献
Chitosan nanoparticles (CHN) were prepared based on ionotropic gelation between low moleculer weight chitosan and sodium tripolyphosphate (TPP) under microwave irradiation. Particle size, zeta potential, and FT-IR techniques were used for characterization of CHN. The influence of reaction time on the nanoparticle size distribution was investigated, and the results showed that the microwave irradiation method evidently decreases the reaction times and particle size over the conventional method. It was determined by the results of the zeta potential measurements that synthesized CHN under microwave irradiation clearly exhibits more homogeneous and stable dispersion. 相似文献
The effect of traveling microwave irradiation on the crystallinities of CdS nanoparticles and Bi2S3 nanorods was studied. Results showed that as compared with stationary microwave irradiation the crystallinities and the crystal growth of sulfide nanoparticles were improved. Traveling microwave irradiation can supply narrower frequency distribution and stronger power density of irradiation, CdS nanoparticles and Bi2S3 nanorods obtained are better in crystallinities and larger in size than under stationary microwave irradiation. 相似文献
The influence of microwave irradiation on the mass transfer kinetics of an insulin variant in reversed-phase liquid chromatography (RPLC) was investigated. The elution band profiles of insulin were obtained by the pulse-response method, under linear conditions. The RPLC column was placed in a microwave oven and the incremental change in the temperature of the column effluent stream at various microwave energies and mobile phase flow rates were measured. The microwave energy dissipated in the column was set at 15 and 30 W and the mobile phase flow rate was varied from 1.0 to 2.5 mL/min at a mobile phase composition of acetonitrile, water, and trifloroacetic acid (31:69:0.1, v/v/v). The experimental data were analyzed using the conventional method of moment analysis and the lumped pore diffusion model. Regardless of mobile flow rates, the effluent temperatures measured at 15 and 30 W microwave power input were 25+/-1 and 30+/-1 degrees C, respectively. The effect of microwave irradiation on the mass transfer of the variant insulin was determined by comparing the band profiles obtained under the same experimental conditions, at the same column temperature, with and without irradiation. The calculated intraparticle diffusion coefficient, D(e), at 30 W (30+/-1 degrees C) microwave irradiation was ca. 20% higher than without irradiation at 30+/-1 degrees C. These preliminary results suggest that microwave irradiation may have a significant influence on the intraparticle diffusion of insulin in RPLC. 相似文献
Summary: Radical homopolymerizations and copolymerizations of styrene were performed in toluene and N,N‐dimethylformamide (DMF) as solvents using different initiators with and without microwave irradiation. Only the homopolymerization of styrene under microwave irradiation in DMF with DtBP showed significantly enhanced styrene conversion whereas other initiators resulted in no or only slight increase of styrene conversion under microwave irradiation. In any case, DMF was required to gain in styrene conversion under microwave irradiation. Significantly higher monomer conversions were observed under otherwise comparable conditions in the copolymerization of styrene and methyl methacrylate (MMA) in DMF. Microwave‐induced selectivity of monomers was not observed in copolymerizations.
Yield of styrene polymerizations under varying reaction conditions initiated by DtBP. 相似文献