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Pankaj Hazarika Swapnalee Sarmah Diganta Kalita Nashreen S. Islam 《Transition Metal Chemistry》2008,33(1):69-77
A set of new diperoxovanadate(V) complexes with the dipeptides glycyl–glycine or glycyl–leucine as ancillary ligands of the
type, A[VO(O2)2(peptide)(H2O)] · H2O, A = Na or K have been synthesized and characterized by elemental analysis, thermal analysis, magnetic susceptibility and
spectral studies. The complexes contain side-on bound peroxo groups and a dipeptide zwitterion as co-ligand, binding the metal
center unidentately through O (carboxylate) atom. The compounds are highly stable toward decomposition in solutions of acidic
as well as physiological pH and serve as weak substrates to catalase, undergoing degradation in the presence of the enzyme
at a rate much slower than H2O2. The compounds stoichiometrically oxidize GSH to GSSG. On comparing the GSH oxidizing ability of these compounds with those
of previously reported peroxotungsten compounds containing similar co-ligands, a significant difference was noted. The compounds
induce a strong inhibitory effect on alkaline phosphatase activity with a potency higher than that of the free peptides, vanadate,
or peroxovanadate. 相似文献
23.
Complex coacervation of gelatin A and sodium alginate was carried out to obtain the maximum coacervate yield. Turbidity and coacervate yield (%) measurements were carried out to support the ratio of the two polymers and pH that produced maximum coacervation. The optimum ratio between gelatin A-sodium alginate and pH to form the maximum coacervate complex was found to be 3.5:1 and 3.5–3.8, respectively. Olive oil microencapsulation was carried out at the optimized ratio and pH. Microcapsules were crosslinked by using glutaraldehyde. Scanning electron microscopy studies confirmed the formation of free flowing spherical microcapsules of different sizes. The size of microcapsules increased with the increase in the concentration of the polymer. The encapsulation efficiency and the release rates of olive oil were dependent on the amount of crosslinker, oil loading and polymer concentration. Thermogravimetric study revealed improvement of thermal stability with crosslinking. Fourier Transform Infrared Spectroscopy study showed that there was no significant interaction between olive oil and gelatin-alginate complex. 相似文献
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We present a soft-lithography based method to fabricate plastic thin film fluidic devices on glass and plastic substrates. Principles of soft-lithography and spin casting were used to generate the films. The thickness of these films is controllable and the patterns we have generated have submicron scale dimensions. By using commercially available compact disc (CD) components as molds, we have been able to generate parallel line and cross patterns on these thin films. These patterned films could be lifted from the substrates and further folded into rolls. 相似文献
25.
Palash M. Saikia Bornali Boruah Biswajit Kakoty Pankaj Hazarika 《Journal of Dispersion Science and Technology》2014,35(7):997-1002
The binding of curcumin with chitosan in the presence of nonionic surfactant, iso-octylphenoxy-polyethoxy-ethanol (Triton X-100) and its stability in such systems have been investigated by monitoring the changes in the absorption spectra at physiological pH (7.4). It was observed that curcumin binds to chitosan more than 10 times stronger in presence of TX 100 at the experimental condition. From spectrophotometric analysis of the kinetics of degradation of the dye, it was observed that the yield of suppression of degradation of curcumin by chitosan increases by 33.5% in the presence of TX 100 than alone. The interaction of the dye with chitosan has been found to be exothermic and driven by hydrophobic interactions, hydrogen bond formation, and electrostatic interactions. 相似文献
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Indranirekha Saikia Moushumi Hazarika Najrul Hussian Manash R. Das Chandan Tamuly 《Tetrahedron letters》2017,58(45):4255-4259
Here, biogenic synthesis of Fe2O3@SiO2 nanoparticles using fruit extract of Zanthoxylum rhetsa is reported. The SiO2 nanoparticles was synthesized using paddy straw which is a byproduct obtained in cultivation of rice. The composite was characterised by spectroscopic method like XRD, SEM, TEM and EDX analysis. The ipso-hydroxylation reactions were carried out with excellent yield within a moderate time period with mild reaction condition in all cases. Therefore, this approach may be considered as simple, easy, cheap and greener, environment friendly protocol for ipso-hydroxylation of arylboronic acids at 50 °C temperature. 相似文献
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A simple and efficient synthesis of bis- and tris-indolylalkanes from carbonyls (aldehydes/ketones) and indoles with excellent yields in the presence of dodecylsulphonic acid (DSA) in water at room temperature is described. The catalyst is also applicable for the synthesis of 3,3-di(3-indolyl)oxindoles. The dodecylsulphonic acid acts as both Brønsted acid and surface-active agent in the reaction mixture. 相似文献
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In the present work we have worked out phasor diagrams with the help of the concept of moving vectors. We show that the area enclosed by the phasor diagrams behaves like lifetime of atomic states. We also make a comparative study of our model with the models suggested by other workers to explain lasing without inversion. 相似文献
29.
Manashjyoti Konwar Roktopol Hazarika Abdul A. Ali Mitali Chetia Nageshwar D. Khupse Prakash J. Saikia Diganta Sarma 《应用有机金属化学》2018,32(8)
A novel and highly efficient method for the synthesis of 1,4‐disubstituted‐1H‐1,2,3‐triazoles by copper‐catalyzed azide‐alkyne cycloaddition has been developed. This economic and sustainable protocol uses a readily available Benedict's solution/Vitamin C catalyst system affording a wide range of 1,4‐disubstituted‐1H‐1,2,3‐triazoles under mild conditions. 相似文献
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The quantum chromodynamics-inspired potential model pursued by us earlier has been recently modified to incorporate an additional factor ‘c’ in the linear cum Coulomb potential. While it felicitates the inclusion of standard confinement parameter b?=?0.183 GeV2 unlike in previous work, it still falls short of explaining the Isgur-Wise function for the B mesons without ad hoc adjustment of the strong coupling constant. In this work, we determine the factor ‘c’ from the experimental values of decay constants and masses and show that the reality constraint on ‘c’ yields bounds on the strong coupling constant as well as on slope and curvature of Isgur-Wise function allowing more flexibility to the model. 相似文献