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排序方式: 共有137条查询结果,搜索用时 15 毫秒
121.
Lima LF Habu S Gern JC Nascimento BM Parada JL Noseda MD Gonçalves AG Nisha VR Pandey A Soccol VT Soccol CR 《Applied biochemistry and biotechnology》2008,151(2-3):283-294
The aim of the work was to study the production of the exopolysaccharides by Agaricus brasiliensis and the isolation of exopolysaccharides (EPSs) with biological effects. A brasiliensis LPB03 was cultured in submerged fermentation in a medium containing glucose, yeast extract, hydrolyzed soybean protein, and salts (pH 6.1) at 29 degrees C and 120 rpm for 144 h. The maximum biomass and EPS yield was 7.80 +/- 0.01 and 1,430.70 +/- 26.75 mg/L, respectively. To isolate the produced EPSs, two methods were compared: (1) with alcohol precipitation and (2) treatment with tricloroacetic acid (TCA), followed by alcohol precipitation. The use of TCA facilitated the purification of the EPS, reducing the amount of the contaminant soy proteins. For monosaccharide identification, the EPSs were hydrolyzed, derivatized to alditol acetates, and analyzed by gas chromatography (GC) and GC-mass spectrometry, which showed the presence (in molar percentage) of mannose (58.7), galactose (21.4), and glucose (13.1) as major sugars, with lower amounts of rhamnose (3.9) and xylose (2.8). Scanning electron microscopy was used to observe the morphological structure of the EPS. The experiments in vivo including EPS in the mice diet during 8 weeks indicated the hipocholesteremic and hypoglycemic effects. 相似文献
122.
S. Kumari Nisha S. K. Asha 《Journal of polymer science. Part A, Polymer chemistry》2013,51(3):509-524
A high‐temperature solution blending process has been used to synthesize a series of copolymers incorporating varying mole ratios of perylenebisimide (PBI) into the backbone of an engineering thermoplastic polyester [poly(1,4‐cyclohexylenedimethylene‐1,4‐cyclohexanedicarboxylate)] (PCCD). A random donor–acceptor copolymer incorporating oligo(p‐phenylene vinylene) (OPV) and PBI was also synthesized. The chemical incorporation of these chromophores into PCCD was confirmed by carrying out the melt condensation using 1,4‐cyclohexanedimethanol and 1,4‐dimethylcyclohexane dicarboxylate with hydroxyl‐functionalized PBI and OPV derivatives. Higher extent of incorporation of PBI (35 mol %) could be achieved using the blending approach retaining solubility, film‐forming ability, and higher molecular weights. The PBI polymers produced using the two different approaches exhibited structural variations. The polymers formed from the solution blending approach had a semicrystalline nature with blocks of PCCD separating the PBI units, whereas those produced using the melt condensation route were amorphous polymers. This structural variation was reflected in their photophysical properties also with the reactive solution‐blended polymers exhibiting higher fluorescence quantum yields. These results demonstrate the easy incorporation of suitably functionalized donor and acceptor moieties into a completely aliphatic polyester backbone to produce free‐standing films of hitherto nonprocessable polymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
123.
Nisha V. Ramadas Carlos R. Soccol Ashok Pandey 《Applied biochemistry and biotechnology》2010,162(4):996-1007
The aim of this work was to statistically optimize the cultural and nutritional parameters for the production of polyhydroxybutyrate (PHB) under submerged fermentation using jackfruit seed hydrolysate as the sole carbon source. On the basis of results obtained from “one variable at a time” experiment, inoculum age, jackfruit seed hydrolysate concentration, and pH were selected for response surface methodology studies. A central composite design (CCD) was employed to get the optimum level of these three factors to maximize the PHB production. The CCD results predicted that jackfruit seed hydrolysates containing 2.5% reducing sugar, inoculum age of 18 h, and initial medium pH 6 could enhance the production of PHB to reach 49% of the biomass (biomass 4.5 g/l and PHB concentration 2.2 g/l). Analysis of variance exhibited a high coefficient of determination (R 2) value of 0.910 and 0.928 for biomass and PHB concentration, respectively, and ensured that the quadratic model with the experimental data was a satisfactory one. This is the first report on PHB production by Bacillus sphaericus using statistical experimental design and RSM in submerged fermentation with jackfruit seed hydrolysate as the sole source of carbon. 相似文献
124.
Shang X Marchioni F Sipes N Evelyn CR Jerabek-Willemsen M Duhr S Seibel W Wortman M Zheng Y 《Chemistry & biology》2012,19(6):699-710
Rho GTPases have been implicated in diverse cellular functions and are potential therapeutic targets. By virtual screening, we have identified a Rho-specific inhibitor, Rhosin. Rhosin contains two aromatic rings tethered by a linker, and it binds to the surface area sandwiching Trp58 of RhoA with a submicromolar Kd and effectively inhibits GEF-catalyzed RhoA activation. In cells, Rhosin specifically inhibited RhoA activity and RhoA-mediated cellular function without affecting Cdc42 or Rac1 signaling activities. By suppressing RhoA or RhoC activity, Rhosin could inhibit mammary sphere formation by breast cancer cells, suppress invasion of mammary epithelial cells, and induce neurite outgrowth of PC12 cells in synergy with NGF. Thus, the rational designed RhoA subfamily-specific small molecule inhibitor is useful for studying the physiological and pathologic roles of Rho GTPase. 相似文献
125.
A dual-catalysis/anion-binding approach with a chiral hydrogen bonding (HB) catalyst and an achiral nucleophilic cocatalyst was applied to the kinetic resolution of amines. Out of a structurally diverse collection of 22 nucleophilic species, 4-di-n-propylaminopyridine emerged as the most efficient cocatalyst, allowing for the kinetic resolution of benzylic amines with s-factors of up to 67. 相似文献
126.
Kundu P Singhania N Madras G Ravishankar N 《Dalton transactions (Cambridge, England : 2003)》2012,41(29):8762-8766
We present a green method for the synthesis of ZnO-Au hybrids using an ultrafast microwave-based technique. This method provides good control over the nucleation of the metal nanoparticles on the oxide support, which governs the morphology and microstructure of the hybrids. The hybrids exhibit good catalytic activity for CO oxidation compared to similar hybrids reported in the literature. Detailed XPS investigation reveals the presence of Au-Zn and Au-O bonds at the interface. This surface doping leads to the formation of anionic and cationic Au sites that contribute to the enhanced activity. Our method is general and can be applied for designing other supported catalysts with controlled interfaces. 相似文献
127.
Devendra Singh Negi Nisha Negi Ashok Kumar Katsuyoshi Matsunami Stefan Schulz Peter G. Jones 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(1):87-89
Asarinin, C20H18O6, was isolated as a racemate from the shrub Zanthoxylum alatum. Both forms of the enantiomerically pure substance, (+)‐ and (−)‐asarinin, have been the subject of a total of five previous structure determinations that are essentially identical except for the absolute stereochemistry. However, there seems to be some confusion in the literature concerning these structure determinations of asarinin and also those of its stereoisomer sesamin. The molecular structure of racemic asarinin differs from that of the pure enantiomers in the orientation of one ring system. In the packing of the racemate, molecules are linked by C—H...O interactions to form ribbons parallel to [101]. 相似文献
128.
Karin H. Adolfsson Nisha Yadav Minna Hakkarainen 《Current Opinion in Green and Sustainable Chemistry》2020
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129.
Basak P Nisha CK Manorama SV Maiti S Jayachandran KN 《Journal of colloid and interface science》2003,262(2):560-565
The effect of salt on the associative behavior of intramolecular aggregates obtained from poly(ethylene glycol)-based amphiphilic comb-like polymers in aqueous medium at pH 6.2 has been investigated by surface tension, fluorescence probe, dynamic light-scattering, and viscometry techniques. Results reveal that the addition of salt screens the electrostatic repulsion between the charges along the polymer backbone in the aggregates and consequently (1) reduces the surface activity at the air/water interface, (2) leads to the contraction of the polymer backbone, and (3) reduces the hydrodynamic sizes of the aggregates. In contrast, the hydrophobicity of the aggregates remains unperturbed. 相似文献
130.
A Mitsunobu-based protocol has been developed for the synthesis of symmetrical and unsymmetrical dialkylcarbonates from a variety of primary, secondary and tertiary alcohols using gaseous carbon dioxide, in good to excellent yields. This protocol is mild and efficient compared to other reported methods. 相似文献