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Kokrajhar, India

Swargiary A.,Bodoland University | Roy B.,North - Eastern Hill University
Medicinal Plants | Year: 2015

Aqueous extract of Alpinia nigra (Gaertn.) is a widely used traditional medicine by Tripuri tribe of North-east India against intestinal helminthiasis. Our earlier studies have established the anthelminthic properties of the plant; however, very few literature is available about its antioxidant properties. The present study tries to explore its phytochemical constituents and antioxidant properties. The antioxidant activities of the plant was investigated using 1,1 diphenyl 2 picrylhydrazyl (DPPH), FRAP assay, Ferric reducing power test and hydrogen pero xide (H2O2) free radical scavenging power tests. Qualitative test for alkaloids, carbohydrate, flavonoids, glycosides, phenols and saponins were also determined along with the quantitative test for total phenolic compounds (TPC). The extracts showed positive results for all the phytochemicals studied. The total phenolic content (TPC) was found to be 40.65±0.43 and 25.66±0.3 mgGAE/g for ethanol-and aqueous extracts, respectively. Good antioxidant and free radical scavenging power have also been seen compared to the standard ascorbic acid. Ethanol extract was found more active compared to the aqueous extract. Therefore, the shoot-extract the Alpinia nigra could be used as a potential source of natural antioxidant and may be a good candidate for plant based pharmaceutical products. © 2015, IndianJournals.com. All rights reserved. Source


Deka R.K.,Gauhati University | Paul A.,Bodoland University
Pramana - Journal of Physics | Year: 2013

An analysis is performed to study the unsteady, incompressible, one-dimensional, free convective flow over an infinite moving vertical cylinder under combined buoyancy effects of heat and mass transfer with thermal and mass stratifications. Laplace transform technique is adopted for finding solutions for velocity, temperature and concentration with unit Prandtl and Schmidt numbers. Solutions of unsteady state for larger times are compared with the solutions of steady state. Velocity, temperature and concentration profiles are analysed for various sets of physical parameters. Skin friction, Nusselt number and Sherwood number are shown graphically. It has been found that the thermal as well as mass stratification affects the flow appreciably. © 2013 Indian Academy of Sciences. Source


Paul A.,Bodoland University | Deka R.K.,Gauhati University
International Journal of Chemical Engineering | Year: 2013

An analysis is performed to study the heat and mass transfer on the flow past an infinite moving vertical cylinder, in the presence of first-order chemical reaction. The closed-form solutions of the dimensionless governing partial differential equations are obtained in terms of Bessel's functions and modified Bessel's functions by the Laplace transform technique. The transient velocity profiles, temperature profiles, and concentration profiles are studied for various sets of physical parameters, namely, the chemical reaction parameter, Prandtl number, Schmidt number, thermal Grashof number, mass Grashof number, and time. The skin friction, Nusselt number, and Sherwood number are also obtained and presented in graphs. It is observed that in presence of as well as increase in chemical reaction the flow velocity decreases. Also, in presence of destructive chemical reaction the concentration profile and Sherwood number tend to the steady state at large time. © 2013 Ashish Paul and Rudra Kanta Deka. Source


Brahma J.,Science College | Brahma B.K.,Bodoland University
International Journal of Conservation Science | Year: 2016

Throughout history, natural products from plants have played sustaining roles in the lives of humans, especially for food sources and for medicinal products. Oral interviews with local and village elders have enumerated 50 species of economically important wild aromatic plants used as vegetables, spices, condiments and medicines for curing different ailments. Of these six aromatic plants were analyzed to evaluate nutritional and bioactive compounds. The results revealed that it contains moisture content in the range of 66-87% of fresh weight, ash content 20-43% of dry weight, crude protein in 12-25% of dry weight, total solids in 13-34% of dry weight, carbohydrates in a range of 7-42% of dry weight and crude fat in 0.68-2.0% of dry weight. Qualitative phytochemical analysis of these plants confirms the presence of bioactive compounds like steroids, alkaloids, flavonoids, tannins, saponins and trace amounts of micro nutrient elements. Thus, preliminary study and qualitative analysis draws attention on the signifance of these phytochemicals with respect to the role of wild plants in traditional medicinal system and the need for further studies in treatment of many diseases. Source


Deka R.K.,Gauhati University | Paul A.,Bodoland University
Magnetohydrodynamics | Year: 2014

An exact analysis is performed to study the unsteady one-dimensional MHD free convective flow past an infinite vertical cylinder in the presence of homogeneous chemical reaction of first order. Analytical solutions of the unsteady governing linear equations are obtained by Laplace transform technique. Transient velocity, temperature, concentration profiles, skin friction, Nusselt and Sherwood numbers are presented for various physical parameters, such as thermal Grashof number, mass Grashof number, chemical reaction parameter, magnetic parameter, Prandtl number and Schmidt number. It is observed that the velocity field decreases with the increase in chemical reaction parameter as well as in magnetic field parameter. Further, it is shown that as the time progresses, the velocity, temperature and the concentration approach the steady state. Source

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