North Eastern Hill University

About: North Eastern Hill University is a education organization based out in Shillong, Meghalaya, India. It is known for research contribution in the topics: Population & Ruthenium. The organization has 2318 authors who have published 4476 publications receiving 48894 citations.

Transport processes during the incubation time of ion track etching in polymers

Abstract: The processes which take place in polymers before visible etch track formation sets in after exposure to alkaline solutions, i.e. during the so-called “incubation time”, are thought to consist of the penetration of the liquid into the polymer and the polymer’s subsequent glassy-to-rubbery phase transformation. We have studied systematically the first of these steps – the penetration process – by measuring the depth distributions of tracer ions dissolved in the penetrant solutions in different polymers as a function of pH value, temperature, and penetration time. Determination of the free volume of pristine and ion-irradiated polymers by positron annihilation spectroscopy served as an additional important source of information. Our findings show that the solutions’ penetration is often a highly complex process which eventually dominates the overall incubation time.

Above-barrier resonances: analytical expressions for energy and width

Abstract: We construct a smooth realistic barrier potential that can generate resonances above the top of the barrier provided a parameter λ controlling the flatness of the barrier is larger than the critical value λ = (2)1/2. The energies and widths of resonances are expressed analytically in terms of the characteristics of the barrier, namely height, range and flatness. In order to obtain a more versatile and asymmetric barrier, two symmetric barriers are merged together side by side and the exact transmission coefficient across such a barrier is derived.

In vivo anthelmintic activity of Clerodendrum colebrookianum Walp., a traditionally used taenicidal plant in Northeast India

Abstract: Although there are several effective drugs available for the treatment of intestinal helminths, the fact remains that they continue to remain out of reach to a vast majority of people in the world, especially in developing countries. On the other hand, there are a great many herbal remedies that are effective against common intestinal worms and are easily available to common people in developing countries. Clerodendrum colebrookianum Walp. (Lamiaceae) is a perennial shrub which is native to South and Southeast Asia. Traditionally, the leaves of this plant are used by the indigenous people of Northeast India as a remedy for the treatment of intestinal tapeworm infections. The aim of this study was to evaluate and authenticate the anthelmintic efficacy of C. colebrookianum leaf extract in experimentally induced Hymenolepis diminuta (a zoonotic tapeworm) infections in Wistar rats. The efficacy of the plant extract was assessed by monitoring the eggs per gram of faeces (EPG) counts and worm recovery rates of experimental animals, following treatment with the leaf extract of this plant at three different doses, i.e. 200, 400 and 800 mg/kg body weight, each given singly for 5 days. The results obtained revealed that the leaf extract of C. colebrookianum possesses a dose-dependent efficacy against the larval, immature and adult stages of H. diminuta. However, the efficacy of the extract was found to be considerably high only against the adult stages of the parasite. For this stage, a single 800-mg/kg dose of extract, given for 5 days, resulted into 68.42 % reduction in the EPG counts and 62.50 % reduction in the worm counts in the extract-treated group of animals, as compared to the control. The reference drug, praziquantel (5 mg/kg, single dose), however, showed slightly better efficacy and caused 95.16 and 87.00 % reductions in the EPG and worm counts of treated animals, respectively. Unlike the adult stages, the efficacy of the plant extract was recorded to be comparatively low against the larval and immature stages of the parasite, as the treatment of animals with the highest dose of extract (800 mg/kg) could cause only 37.50 and 54.00 % reductions in worm counts, respectively. The experimental evidence obtained in this study suggests that leaves of C. colebrookianum possess significant anthelminthic properties and supports their use against intestinal tapeworm infections in traditional medicine.