Dibrugarh, India
Dibrugarh, India

Dibrugarh University is a university in the Indian state of Assam. It was set up in 1965 under the provisions of the Dibrugarh University Act, 1965, enacted by the Assam Legislative Assembly. It is a teaching-cum-affiliating university with limited residential facilities. Wikipedia.


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Sharma V.K.,Gurukul Kangri University | Mazumder B.,Dibrugarh University
International Journal of Biological Macromolecules | Year: 2014

Isabgol husk with sodium alginate was formulated into gliclazide loaded microparticles which were characterized for particle size, swelling index, entrapment efficiency, in vitro release, release kinetics, stability, hypoglycemic effect, surface morphology, and gastrointestinal transition. The particle size in different formulations varied from 752.83±0.630 to 872.03±0.293μm. It was analyzed by dissolution study that up to 98% of loaded gliclazide was released in simulated intestinal fluid (SIF, pH 7.4) within 8h. The formulations containing sodium alginate and Isabgol husk-sodium alginate showed bioequivalency with marketed sustained release tablets (Glizid MR 60®) in terms of release pattern. The drug maintained its integrity in terms of functional groups after fabrication in formulations as observed by FTIR analysis. The hypoglycemic effect of gliclazide loaded Isabgol husk-sodium alginate microparticles was found to be 37±6.356% in terms of changes of blood glucose level from base glucose level (100%) in diabetic condition after 24h of oral administration and it was more than marketed conventional tablets (95.5±3.286%). The retention of microparticles was observed in small intestine up to 10h during whole body X-ray imaging. The study revealed that microparticles composing of Isabgol husk may have the potential for regulating blood glucose level in diabetic animals with controlled release of gliclazide. © 2014 Elsevier B.V.


Mondal M.,Dibrugarh University | Bora U.,Dibrugarh University | Bora U.,Tezpur University
RSC Advances | Year: 2013

The preceding four decades have witnessed a major expansion in the field of free-radical assisted reactions, as they are becoming a key tool in organic, polymer and complex natural product chemistry. This progress has clearly changed the traditional idea of free-radical reactions being "extremely uncontrollable", thereby allowing chemists to deal with free radicals in a more accurate and controlled way. Manganese(iii) acetate mediated radical reactions have reached distinction in this field, as a wide range of protocols involving manganese(iii) acetate under mild and efficient reaction conditions have been developed for the synthesis of biologically active and important organic molecules through oxidation, addition and cyclization reactions, which are in general difficult to achieve by the established synthetic operations. The present review focuses on manganese(iii) acetate mediated oxidative free-radical reactions that have been developed and adapted during the last five years. It includes the advancements made in the field of free-radical promoted carbon-carbon and carbon-oxygen bond forming reactions, illustrating the examples of furans, hydrofurans, pyrroles, bicyclic lactones, biaryls, oxepins, indole-alkaloids, 1,2-benzanthracene and C60-fused tetrahydronaphthalene synthesis. Numerous manganese(iii) acetate initiated carbon-phosphorus bond formation reactions were also devised during recent years, involving both phosphonyl and phosphinoyl radicals, and are a key part of this review. Manganese(iii) acetate promotes functionalization of significant organic compounds, thereby guiding the synthesis of important and complex molecules, such as the formation of propellanes, quinolinones, 1,2-dioxalanes; oxidation of indoles; lactonization of fullerene [C60], malonyl cyclopentanes, glycols; and hydroperoxidation of heterocycles. The review will also envelop several recent milestones that have been achieved in the chemistry of natural products précising the vital role of manganese(iii) acetate in the key synthetic steps. This journal is © The Royal Society of Chemistry 2013.


Mondal M.,Dibrugarh University | Bora U.,Dibrugarh University
Green Chemistry | Year: 2012

An in situ generated catalytic system based on PdCl2 and sodium sulfate exhibited excellent catalytic activity in the Suzuki-Miyaura cross-coupling reactions of aryl halides with arylboronic acids at room temperature in water. A similar catalytic system can be obtained with PdCl 2 and sodium chloride or sodium acetate and is equally effective in Suzuki-Miyaura cross-coupling reactions. This method offers a mild and efficient alternative to the existing protocols since the reaction is proceeded in water at room temperature under ligand free conditions. © The Royal Society of Chemistry 2012.


Gogoi A.,Dibrugarh University | Bora U.,Dibrugarh University
Tetrahedron Letters | Year: 2013

An ipso-hydroxylation of arylboronic acids to phenols using aqueous H 2O2 as oxidant and acidic alumina as catalyst has been reported in this study. The reusability of the catalyst is also investigated. © 2013 Elsevier Ltd. All rights reserved.


Gogoi S.B.,Dibrugarh University
Transport in Porous Media | Year: 2011

Surfactant loss due to adsorption on the porous medium of an oil reservoir is a major concern in enhanced oil recovery. Surfactant loss due to adsorption on the reservoir rock weakens the effectiveness of the injected surfactant in reducing oil-water interfacial tension (IFT) and making the process uneconomical. In this study, surfactant concentrations in the effluent of the corefloods and oil-water IFT were determined under different injection strategies. It was found that in an extended waterflood following a surfactant slug injection, surfactant desorbed in the water phase. This desorbed surfactant lasted for a long period of the waterflood. The concentration of the desorbed surfactant in the extended waterflood was very low but still an ultralow IFT was obtained by using a suitable alkali. Coreflood results show an additional recovery of 13. 3% of the initial oil in place was obtained by the desorbed surfactant and alkali. Results indicate that by utilizing the desorbed surfactant during the extended waterflood operation the efficiency and economics of the surfactant flood can be improved significantly. © 2011 Springer Science+Business Media B.V.


Gogoi A.,Dibrugarh University | Bora U.,Dibrugarh University
Synlett | Year: 2012

A mild and efficient methodology for the ipso-hydroxylation of arylboronic acids to phenols has been developed using aqueous hydrogen peroxide as oxidizing agent and molecular iodine as catalyst. The reactions were performed at room temperature in short reaction time under metal-, ligand- and base-free conditions. © Georg Thieme Verlag Stuttgart · New York.


Singh A.V.,Dibrugarh University | Nath L.K.,Dibrugarh University
International Journal of Biological Macromolecules | Year: 2012

Highly substituted sago starch phosphate was synthesized using POCl 3 as cross-linking reagent. Titrimetric and Fourier transform infra red (FT-IR) spectral analysis were used to characterize the substitution. Studying the different factors affecting the reaction parameters showed that the optimal conditions for starch phosphorylation were: 4h reaction time and reagent concentration 1.5% (w/w). The physicochemical properties of cross-linked sago starch (CLSS) were done using Scanning electron micrograph (SEM), X-ray powder diffractometer (XRD and Thermogravimetric analysis (TGA). The results revealed that crystalline nature of native sago starch was transformed after cross-linking. TGA report exhibited higher thermal stability, which makes it suitable for various industrial applications. Swelling behavior showed high swelling at low temperature (30 and 60°C) as compared to high temperature (90°C). © 2011 Elsevier B.V.


Singh A.V.,Dibrugarh University | Nath L.K.,Dibrugarh University
International Journal of Biological Macromolecules | Year: 2012

The present investigation concerns with the development of controlled release tablets of lamivudine using acetylated moth bean starch. The acetylated starch was synthesized with acetic anhydride in pyridine medium. The acetylated moth bean starch was tested for acute toxicity and drug-excipient compatibility study. The formulations were evaluated for physical characteristics like hardness, friability, % drug content and weight variations. The in vitro release study showed that the optimized formulation exhibited highest correlation (R) value in case of Higuchi kinetic model and the release mechanism study proved that the formulation showed a combination of diffusion and erosion process. There was a significant difference in the pharmacokinetic parameters (T max, C max, AUC, V d, T 1/2 and MDT) of the optimized formulation as compared to the marketed conventional tablet Lamivir ®, which proved controlled release potential of acetylated moth bean starch. © 2012 Elsevier B.V.


Singh A.V.,Dibrugarh University
Journal of Thermal Analysis and Calorimetry | Year: 2013

The present investigation concerns with thermal analysis of biomaterials such as Chitosan, Xanthan gum, Guar gum Pectin, Karaya gum, Sodium alginate, and Psyllium husk mucilage. The DSC curve of the natural polymers showed its specific endothermic peaks and ΔH f values, and these will be helpful in determining the fitness of the polymers with active drug. The drug and natural polymer compatibility study is now one of the recognized methods for preformulation step in pharmaceutical drug development. All the natural polymers showed endothermic peak below 150 C, and this make them suitable with a wide class of therapeutic drugs. © 2012 Akadémiai Kiadó, Budapest, Hungary.


We have prepared a silica supported palladium nanocatalyst (PdNP@PPh2-SiO2) with high dispersion via a one-step reaction between commercially available 2-diphenylphosphinoethyl-functionalized silica gel (PPh2-SiO2) and PdCl2 without the assistance of an external reductant or stabilizer. The catalyst was well characterized by N2-adsorption, XRD, HRTEM, SEM-EDX and ICP analyses. The supported catalyst exhibited excellent activity for the Suzuki-Miyaura cross-coupling reactions of aryl halides (including aryl chlorides) with arylboronic acids. The facile synthesis of the catalyst combined with high product yields at relatively low catalyst loading (<0.5 mol%) represents one of the most efficient silica supported heterogeneous systems for the Suzuki coupling of aryl chlorides. The catalyst could be reused several times without compromising its activity. © The Royal Society of Chemistry 2015.

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