North Eastern Regional Institute of Science and Technology

About: North Eastern Regional Institute of Science and Technology is a education organization based out in Itanagar, India. It is known for research contribution in the topics: Population & Raman spectroscopy. The organization has 813 authors who have published 1429 publications receiving 16122 citations.

In vitro study on antioxidant activity and phenolic content of three Piper species from North East India

Abstract: The antioxidant activities of water (W) methanol (ME), water: methanol (1:1), ethanol (ET), chloroform (CH), ethyl acetate (EA) and petroleum ether (PE) extracts of the leaf of three Piper species viz; Piper betle L, Piper betleoides C.DC and Piper wallichii (Miq.) Hand-Mazz was investigated using several in vitro antioxidant assays. The scavenging activity was evaluated by using DPPH (2,2′-diphenyl-1-picryl hydrazyl), FRAP (ferric reducing antioxidant power), ABTS [2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid)], hydrogen peroxide scavenging, hydroxyl radicals scavenging, chelating power and reducing power assay. These methods were used for evaluating the best solvent system for extracting the antioxidants. The total phenolic content (TPC) and total flavonoid content (TFC) were also determined for all the extract. The phenolic acid and flavonoids i.e. catechin, quercetin, gallic acid, coumaric acid and protocatechuic acid which may be responsible for antioxidant activity in the fraction of best solvent system were evaluated. The catechin found to be higher (>1.1 mg/g) in all the species in water: methanol extract. The study revealed that Piper species may be used as one of the source of potential antioxidants.

Ranking of Sites for Installation of Hydropower Plant Using MLP Neural Network Trained with GA

Abstract: Every energy system which we consider is an entity by itself, defined by parameters which are interrelated according to some physical laws. In recent year tremendous importance is given in research on site selection in an imprecise environment. In this context, decision making for the suitable location of power plant installation site is an issue of relevance. Environmental impact assessment is often used as a legislative requirement in site selection for decades. The purpose of this current work is to develop a model for decision makers to rank or classify various power plant projects according to multiple criteria attributes such as air quality, water quality, cost of energy delivery, ecological impact, natural hazard, and project duration. The case study in the paper relates to the application of multilayer perceptron trained by genetic algorithm for ranking various power plant locations in India.

Effects of grain refinement and residual elements on hot tearing in aluminum castings

Abstract: In the present work, some investigations have been carried out on hot tears in the Al–1 wt.% Sn alloy, with the objective of preventing hot tearing in aluminum castings. Al–1Sn alloy is extremely prone to hot tearing due to its long freezing range and is an ideal model for studying hot tearing. Experiments were conducted with varying grain refiner (Al–5Ti–1B) percent and pouring temperature. Grain refiner was added to the melt up to 3.0% by weight, which is the conventional limit for grain refiner addition. However, it was found that the maximum addition of grain refiner could not prevent hot tearing, which contradicts the conclusions of some earlier researchers. A mathematical model developed from the experimental data (using regression analysis) has indicated that, among all the constituents present in the Al–1Sn alloy, tin highly increases hot tearing tendency, whereas titanium in the grain refiner decreases hot tearing tendency. The model has also indicated that iron, which is the common impurity in commercial aluminum, reduces hot tearing. Based on the aforesaid model, further experiments were conducted with the addition of iron, which has resulted in complete elimination of hot tearing. Microstructural analysis was carried out using a scanning electron microscope (SEM). The leaf-like structure containing the Al–Sn–Fe-rich phase held the adjacent grains together and thus prevented hot tearing.

Phase transition studies in symmetric dimeric liquid crystals

Abstract: As a part of the systematic studies on symmetric liquid crystal dimer homologous series, α,ω-bis-(4-n-alkylaniline benzylidene-4′-oxy) alkanes, (referred to as m.OnO.m with m = 3, 4, and 5; and n = 8, 9, and 10), we present in this article the nature of phase transitions across isotropic–nematic and nematic–smectic-A (N–SmA) phases exhibited by the just mentioned compounds. The methods employed are differential scanning calorimetry and dilatometry. The compounds studied were 3.O8O.3, 4.O8O.4, and 5.O8O.5; and 3.O9.03, 5.O9O.5, 3.O10O.3, 4.O10O.4, and 5.O10O.5. Different from the case of their corresponding monomers, all these compounds exhibit a nematic phase only with the exception of 5.O8O.5 which exhibits a SA phase in addition to the nematic phase. The phase transitions viz., isotropic–nematic transitions studied in all these compounds were confirmed to be of first-order nature, whereas the N–SmA transition exhibited by the compound 5.O8O.5 only was found to be of second-order nature. We also report in this article the calculated density jumps, thermal expansion coefficient maxima, and pressure dependence of transition temperatures which are analyzed in the light of the available literature data.

Heat transfer enhancement in a thermosyphon using TiO2 nanofluid through natural convection

Abstract: Performance of thermosyphon can be improved by using nanofluid where the colloidal suspension of nanosized TiO2 (1-100 nm) particle in the basefluid enhances the heat transfer characteristics of th...