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211.
Sangeeta Yadav Pramod Kumar Yadav Dinesh Yadav Kapil Deo Singh Yadav 《Applied biochemistry and biotechnology》2009,159(1):270-283
An indigenously isolated fungal strain identified as Aspergillus terricola with assigned fungal strain number MTCC 7588 has been used as source for pectin lyase production. The extracellular pectin
lyase was purified to homogeneity from the culture filtrate of A. terricola by ion exchange and gel filtration chromatography. The determined molecular weight was 35 ± 01 kDa. The K
m and k
cat (turnover) values of the purified enzyme at 37 °C using citrus pectin as the substrate were found to be 1.0 mg/ml and 110.0 s−1, respectively. The pH and temperature optima of the enzyme were 8.0 and 50 °C, respectively. The retting ability of the purified
pectin lyase for natural fibers viz. Cannabis sativa and Linum usitatissimum has been demonstrated for the first time. 相似文献
212.
213.
The optimization to achieve stable and high-yield gold nanoparticles in block copolymer-mediated synthesis has been examined.
Gold nanoparticles are synthesized using block copolymer P85 in gold salt HAuCl4·3H2O solution. This method usually has a very limited yield which does not simply increase with the increase in the gold salt
concentration. We show that the yield can be enhanced by increasing the block copolymer concentration but is limited to the
factor by which the concentration is increased. On the other hand, the presence of an additional reductant (trisodium citrate)
in 1:1 molar ratio with gold salt enhances the yield by manyfold. In this case (with additional reductant), the stable and
high-yield nanoparticles having size about 14 nm can be synthesized at very low block copolymer concentrations. These nanoparticles
thus can be efficiently used for their application such as for adsorption of proteins. 相似文献
214.
Nilesh M. Vaghela Nandhibatla V. Sastry Vinod K. Aswal 《Colloids and surfaces. A, Physicochemical and engineering aspects》2011,373(1-3):101-109
The influence of two salts as additives namely sodium chloride and sodium sulphate and a nonelectrolyte, 2-butoxyethanol on surface chemical and aggregation characteristics of ionic liquids (IL) of 1-octyl-3-methylimidazolium chloride, [C8mim][Cl], 1-octyl-3-methylimidazolium bromide, [C8mim][Br], and 1-octyl-3-methylimidazolium iodide, [C8mim][I] in aqueous media were monitored through surface tension and small angle neutron scattering measurements. The addition of salts drastically decreased the critical aggregation concentration (CAC) and increased the area per adsorbed IL molecule. The co-ions of salts modify the surface of IL molecules and aggregates through various interactions such as charge neutralization, specific interactions and dehydration The results obtained by analyzing the SANS curves in the whole Q range showed that the oblate ellipsoidal shape of the aggregates of ionic liquids is un-altered upon the addition of additives. However the additives facilitate the growth of the aggregates in to microstructures with cubic packing at high salt concentrations. 相似文献
215.
Gregorio Peron Deepak Raj Pant Shyam Sharan Shrestha Sangeeta Rajbhandary Stefano DallAcqua 《Molecules (Basel, Switzerland)》2020,25(24)
Phloroglucinols are characteristic constituents of Hypericum japonicum that are claimed to exert several bioactivities, such as anti-inflammatory, anti-depressant and anti-viral ones. Phloroglucinols are unstable compounds and their synthesis is challenging; thus, isolation from natural sources is still one of the main strategies for obtaining these constituents in purified form. Assessing the presence of phloroglucinols in plant materials can be of interest for compound isolation, and LC-MS approaches afford sensitivity and specificity in this regard. In this work, we combined data from quadrupole-time of flight (QTOF) and ion trap (IT) mass spectrometers in order to assess the presence of the phloroglucinols characteristic of H. japonicum and to elucidate their MS fragmentation pathways. The identified compounds present similar structures bearing the 1,3,5-trihydroxybenzene core with different substitutions, which, in constituents at higher MW, is linked to 3′,3′-dimethyl-6′-oxo-phlorisobutyrophenone by a methylene bridge. Differences in MS2 spectra of the considered phloroglucinols are useful for compound identification and differentiation, and to perform dereplication studies. Overall, the proposed approach could be useful for the analysis of phloroglucinols in H. japonicum and other plant species. 相似文献
216.
Rajkamal Kushwaha Sangeeta Garg Shailendra Bajpai 《Research on Chemical Intermediates》2018,44(10):5759-5786
Rice husk was utilized as a silica source for the synthesis of mesoporous silica (MS), which was further used for the surface modification of iron oxide nanoparticles (IO-NPs) to form mesoporous silica-modified iron oxide nanoparticles (MSIO-NPs). IO-NPs and MSIO-NPs were characterized using FT-IR, XRD, X-ray photoelectron spectroscopy, vibrating sample magnetometry, nitrogen adsorption–desorption, TEM and dynamic light scattering analysis. The catalytic activity of MSIO-NPs was tested for degradation and mineralization of Nile blue sulphate dye (NBS) in Fenton-like oxidation process. The degradation efficiency and total organic carbon (TOC) removal of NBS dye onto MSIO-NPs was found to be 92.46 and 66.58%, respectively, after 20 min of reaction time using 5 mM of H2O2 concentration. Modified generalized kinetic model was developed for TOC removal of dye degradation onto MSIO-NPs, to account for oxidizable compounds, non-oxidizable compounds, and intermediate organic compounds. The intermediate products formed during degradation of NBS dye were detected by LC–MS experiment and ten fragments were identified based on mass to charge ratio (m/z). The mechanistic pathway for degradation of NBS dye onto MSIO-NPs has been proposed. 相似文献
217.
Shashwati Sen DK Aswal Ajay Singh TV Chandrasekhar Rao KP Muthe JC Vyas LC Gupta SK Gupta VC Sahni 《Pramana》2002,58(5-6):867-870
The MgB2 superconductor, synthesized using solid-state and liquid-phase sintering methods, have been characterized for various properties.
The upper critical field, irreversibility line and critical current density have been determined using magnetization data.
The current-voltage characteristics recorded under an applied magnetic field revealed the existence of vortex glass transition.
The surface analysis using X-ray photoelectron spectroscopy shows that MgB2 is sensitive to atmospheric degradation. 相似文献
218.
Zemlyanaya E. V. Kiselev M. A. Zbytovska J. Almasy L. Aswal V. K. Strunz P. Wartewig S. Neubert R. 《Crystallography Reports》2006,51(1):S22-S26
The structure of polydispersed populations of unilamellar vesicles is studied by small-angle neutron scattering for three types of lipid systems, namely, single-, two-and four-component vesicular systems. Results of the numerical analysis based on the separated-form-factor model are reported. 相似文献
219.
The layered manganite Nd2−2x
Sr1+2x
Mn2O7, with x varying between 0 and 0.5, has been synthesized using solid-state reaction method. We have found that Nd2−2x
Sr1+2x
Mn2O7 do not form the single-phase layered compound with A3B2O7 structure. Instead, mixtures of various phases, such as, orthorhombic perovskite, i.e., Nd1−z
Sr
z
MnO3, layered manganite and unreacted starting compounds, have been obtained. Except for x=0.4, which is found to be an antiferromagnetic insulator, all other x values yielded metal-insulator transition and ferromagnetic ordering. 相似文献