Seva Bharati

A novel setup combining a LaBr3(Ce)-NaI(Tl) phoswich detector enclosed within twelve BaF2 detectors has been developed for measurements of y-rays over an energy range extending up to 25 MeV. The performance of this setup is systematically investigated up to Ey approximate to 23 MeV obtained from radioactive sources and in-beam reaction 11B(p, y)12C. The energy resolution, time resolution and linearity of the LaBr3(Ce) crystal in the phoswich configuration have been studied. At low energies, the BaF2 detectors along with NaI(Tl) are used as anti-Compton shield of the LaBr3(Ce) crystal and a good improvement in the peak-to-total ratio is achieved. The performance of this array as a high-energy y-ray calorimeter is also studied in add-back mode, demonstrating its capability to reconstruct the electromagnetic shower. The results are validated with the predictions of GEANT4 simulation studies. This dual-mode capability makes the setup highly effective for investigating y-ray transitions over a broad energy spectrum including high-energy y-rays generated from the de-excitation of Giant Dipole Resonance (GDR) and Pygmy Dipole Resonance (PDR) states, as well as from radiative capture reactions.

Heavy metal accumulation in soil is increasing due to opencast coal mining. This research analyzed the heavy metal pollution and associated ecological and human health risk taking 50 soil samples from four overburden dumps (0-year, 4-year, 7-year and 26-year old) at Bansra opencast project (OCP) of Raniganj Coalfield (RCF) and adjacent forest Gurjungle as background values. Six heavy metals (Cd, Cr, Zn, Pb, Ni, and Fe) were tested by inductively coupled plasma optical emission spectrometry (ICP-OES). Heavy metals, except Fe, in overburden dumps exceeded background values displaying high coefficient of variation. Cr, Ni and Fe decreased from 0-year to 26-year dumps, while Pb, Zn and Cd increased. Positive correlations among Cr-Ni-Fe and Pb-Zn metal pairs, principal component analysis (PCA) and agglomerative hierarchical clustering (AHC) identified mainly geogenic and anthropogenic sources. Single element pollution indices (Contamination factor (CF), geoaccumulation index (I-geo) and enrichment factor (EF)) showed extremely high contamination (CF > 6), moderate to extreme pollution and significant to high enrichment. Multi-element indices (degree of contamination (C-deg) and modified degree of contamination (mC(deg))) indicated very high to extreme contamination while pollution load index (PLI 12 to 16) indicated significantly worst soil quality. Ecological risk factor (ERi) varied from low to high for different metals, with contamination higher in 26-year old dump than in running dump, while potential ecological risk (RI > 600) was high in all the dumps. Pb and Cd gave the highest contamination and ecological risk in all the dumps, respectively. The hazard index (HI > 1) and total carcinogenic risk (TCR >10(-4)) assessed through total exposure of metals exceeded the tolerable risk values indicating high non-carcinogenic and carcinogenic health risks, mainly through inhalation followed by ingestion and dermal contact. Children were more susceptible compared to adults. Pb and Cr posed the highest non-carcinogenic risk, while Ni gave the highest carcinogenic risk.

Arsenic (As) and chromium (Cr) are two harmful toxicants as well as carcinogens which can coexist in polluted surface water and groundwater. This coexistence leads to mixture effects in animals including fish. Both of these heavy metals are reported to manifest reactive oxygen species (ROS) mediated toxicity. Though individual neurotoxic effects have been reported, their mixture effects, its mechanism and cellular responses against oxidative stress and DNA damages remain unknown. The present study evaluated the individual and mixture effects of As and Cr at their environmentally relevant concentrations in zebrafish (Danio rerio) brain after 15, 30 and 60 days of exposure. Nrf2, a transcription factor is involved in the expressional regulation of enzymes needed to maintain cellular redox homeostasis. This study reported the expressional pattern of Nrf2 and its associated xenobiotic metabolizing enzyme Nqo1 and other markers of oxidative stress such as ROS generation, reduced glutathione level, lipid peroxidation and catalase activity. Increased malondialdehyde (MDA) content, glutathione level, and catalase activity indicated oxidative stress in exposed groups. In addition, this study revealed expressional alterations of neurotoxicity marker (ache), DNA repair (ogg1, apex1, creb1, polb, mlh1, msh2 and msh6) and tumor suppressor (p53, brca2) genes. Results of ROS generation, MDA level, histopathological analysis, gene expression and immunofluorescence study confirmed that As and Cr did not show antagonistic effects in combination rather indicated additive effects which was dose-dependent but not always linear.

Improved electrode materials result in high power, quick charge/discharge, and efficient conduction of electricity in metal-ion batteries. In this regard, our density functional theory (DFT)-based investigation reveals that ScTe2 monolayer exhibits essential features to function as an electrode material for metal-ion batteries (MIBs). The calculated minimum diffusion energy barriers for Li, Na and K are 0.32, 0.18, and 0.19 eV respectively which support an excellent charge/discharge rate for electrode materials. This system possesses a storage capacity of 357.27, 535.91, and 178.64 mAh/g with open-circuit voltage (OCV) amounting to 1.04, 0.88, and 1.96 V for Li, Na and K respectively. These findings provide valuable insights for designing high-performance electrodes, advancing next-generation metal-ion batteries having improved efficiency and energy density.

This study aims to investigate the thermosolutal performance and irreversibility behavior of a non-Newtonian Casson fluid in a curvilinear porous chamber with baffles under various heating strategies. Thermosolutal convection, driven by temperature and solute concentration gradients, plays a critical role in industrial processes such as electronic cooling, thermal storage, and heat exchangers. The novelty of this work lies in the combined use of a Casson fluid and strategically placed baffles within a curvilinear porous enclosure, alongside non-uniform sinusoidal heating applied to the lower boundary, utilizing multifrequency spatial heating profiles for the first time. The inclusion of baffles significantly enhances control over flow structures and heat transfer efficiency. This numerical analysis explores the effects of key parameters, including the Lewis number (1≤Le≤20), the Darcy number (10−4≤Da≤10−2), the Rayleigh number (104≤Ra≤106), and the Casson fluid parameter (0.1≤β≤10), as well as the amplitude, frequency, and offset temperature of the sinusoidal heating. In spite of solving the Navier–Stokes, thermal, and species transport equations using a higher-order compact scheme, the objective is to examine how these parameters influence flow behavior, heat and solute transfer, kinetic energy (K.E.), and entropy generation. The variation in the Casson fluid parameter (β) from 0.1 to 10 leads to significant enhancements in heat transfer, mass transfer, and kinetic energy by 44.01%, 43.85%, and 210.75%, respectively, while simultaneously reducing the total entropy generation by 4.92%.