Publications by authors named "Krishna Das"

Shifting cultivation, an age-old agricultural practice, is a major factor in forest cover change across Southeast Asia, where repeated cycles of vegetation disturbance and regrowth lead to far-reaching environmental and socio-economic impacts. The present study aims to assess the spatio-temporal patterns of vegetation disturbance and regrowth caused by shifting cultivation in Tripura state of India, over the past three decades, utilizing temporal segmentation of time-series Landsat data. The study analyzed vegetation disturbance and regrowth patterns in a shifting cultivation landscape from 1991 to 2020 using normalized burn ratio trends through LandTrendr, validated by the TimeSync tool.

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This article reports a novel design of a compact tunable resonance filter with a highly extinguished and ultra-broad out-of-band rejection for on-chip amplified spontaneous noise suppression from pump lasers highly demanding for generating pure/entangled photon pairs via χ process in a CMOS compatible silicon photonics technology platform. The proposed device is designed with two identically apodized distributed grating structures for guided Fabry-Perot resonant transmissions in a silicon-on-insulator rib waveguide structure. The device design parameters are optimized by theoretical simulation for a low insertion loss singly-resonant transmission peak at a desired wavelength.

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Coal mining activities greatly damage water resources, explicitly concerning water quality. The adverse effects of coal mining and potential routes for contaminants to migrate, either through surface water or infiltration, into the groundwater table. Dealing with pollution from coal mining operations is a significant surface water contamination concern.

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A new visible-light-mediated non-directed oxidative annulation between 2-arylindazoles and electron-deficient olefins using commercially available piperidine-1-sulfonyl chloride as the radical precursor to afford fused 5,6-dihydroindazolo[2,3-]quinolines has been developed under mild reaction conditions. This transformation occurs two consecutive C-H bond functionalizations. The mechanistic investigation results indicate that the reaction progresses through a radical pathway forming a 2-(2-aryl-2-indazol-3-yl)-3-piperidin-1-ylsulfonyl derivative as an intermediate.

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Numerous factors influence the magnitude and effector phenotype of vaccine-induced CD8 T cells, thereby potentially impacting treatment efficacy. Here, we investigate the effect of vaccination dose, route of immunization, presence of a target antigen-expressing tumor, and heterologous prime-boost with peptide vaccine partner following vaccination with antigen-armed VSV-GP. Our results indicate that a higher vaccine dose increases antigen-specific CD8 T cell proportions while altering the phenotype.

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Accurate interpretation of mercury (Hg) isotopic data requires the consideration of several biotic factors such as age, diet, geographical range, and tissue metabolic turnover. A priori knowledge of prey-predator isotopic incorporation rates and Hg biomagnification is essential. This study aims to assess Hg stable isotopes incorporation in an Arctic species of Phocidae, the hooded seal Cystophora cristata, kept in human care for 24 months (2012-2014) and fed on a constant diet of Norwegian Spring Spawning herring Clupea harengus.

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Given the increased extraction of trace elements for use by new and emerging technologies, monitoring the environmental fate and potential effects of these compounds within the aquatic environment has never been more critical. Here, hepatic trace element concentrations were assessed in a key sentinel predator, the common dolphin (Delphinus delphis), using a long-term dataset. Variation in concentrations were assessed in relation to other elements, time period, decomposition state, sex, age, total body length, sexual maturity and nutritional status, and cause of death.

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An earth-abundant Co(II) salt-catalyzed mild and affordable synthetic route has been developed for the synthesis of industrially relevant 1,4-dicarbonyl compounds (or γ-diketones) oxidative coupling between aryl alkenes and ketones (both cyclic and acyclic) using TBHP and DBU as the oxidant and base, respectively. 1,4-Dicarbonyl compounds are known to be synthesized using expensive metal catalysts, dual catalysts, or low-cost metal complexes combined with an additive or ligand template, which further needs to be synthesized. Herein, we report the synthesis of 1,4-dicarbonyl compounds using cobalt(II) acetate as a catalyst without any expensive co-catalyst or ligand templates.

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Phosphorus to an optimum extent is an essential nutrient for all living organisms and its scarcity may cause food security, and environmental preservation issues vis-à-vis agroeconomic hurdles. Undesirably excess phosphorus intensifies the eutrophication problem in non-marine water bodies and disrupts the natural nutrient balance of the ecosystem. To overcome such dichotomy, biodegradable polymer-based adsorbents have emerged as a cost-effective and implementable approach in striking a "desired optimum-undesired excess" balance pertaining to phosphate in a sustainable manner.

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Neuropsychological impairments are common in children with drug-resistant epilepsy. It has been proposed that epilepsy surgery might alleviate these impairments by providing seizure freedom; however, findings from prior studies have been inconsistent. We mapped long-term neuropsychological trajectories in children before and after undergoing epilepsy surgery, to measure the impact of disease course and surgery on functioning.

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Background And Objectives: Cranial reconstruction presents a significant challenge in cases involving pathologies with skull invasion, and various techniques have been used, including the intraoperative shaping of titanium mesh and the manual sculpting of bone cement serving as surrogates for the excised bone graft. In the context of prefabricated patient-specific implants (PSIs) for cranioplasty, precise surgical execution of craniotomies is paramount. This ensures optimal congruity between the implant and the defect created during the craniotomy, leading to a successful single-stage procedure encompassing both bone removal and reconstruction.

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A metal-free, visible-light-mediated C-H silylation of 2-indazoles with triphenylsilane has been developed employing 4CzIPN as a photocatalyst and triisopropylsilanethiol as a hydrogen atom transfer (HAT) reagent under aerobic reaction conditions. This method shows tolerance toward many functional groups and affords a variety of silylated indazoles at up to 89% yield. The experimental results suggest that the reaction progresses through a radical pathway.

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Decompressive craniectomy (DC) is a well-established neurosurgical intervention in patients with high intracranial pressure who fail to respond to medical treatment. Data on predictive factors for functional outcomes in patients with DC who have malignant middle cerebral artery (MCA) infarction as opposed to intracranial hemorrhage (ICH) are scarce. Eighty-four patients who underwent DC treatment for ICH and malignant MCA infarction were examined.

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We report the Cu(II) catalyzed synthesis of β-disubstituted ketones from styrene via oxo-alkylation with unactivated cycloalkanes as the alkylating agent in presence of tert-butylhydroperoxide (TBHP) and 1-methylimidazole as oxidant and base respectively. β-disubstituted ketones are known to be synthesized by using either expensive Ru/Ir complexes, or low-cost metal complexes (e. g.

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Acyl hydrazones are a class of synthetically important organic compounds that are recurrently in high demand for synthesis and use in various fields of chemistry and biology. We report the first Co(II) catalyzed one-component one-pot sustainable synthesis of acyl hydrazones only from acyl hydrazides under mild reaction conditions. Traditional and contemporary methodologies use two components (usually acyl hydrazides and aldehydes/ketones/alcohols/styrene) as the coupling partners.

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Rapid climate change has led to enhanced soil salinity, one of the major determinants of land degradation, resulting in low agricultural productivity. This has a strong negative impact on food security and environmental sustainability. Plants display various physiological, developmental, and cellular responses to deal with salt stress.

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Methylmercury (MeHg) is a pervasive environmental contaminant in aquatic ecosystems that can reach elevated concentrations in fish of high trophic levels, such as salmonids. The present study aims at investigating the individual and combined impacts of dietary MeHg and fatty acids on lipid metabolism in juvenile rainbow trout (Oncorhynchus mykiss) with a focus on two key organs, adipose tissue and liver. MeHg and fatty acids are both known to act on energy homeostasis although little is known about their interplay on lipid metabolism in fish.

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Information on pollutant trophodynamics can be crucial for public health, as contaminated food consumption may lead to deleterious effects. This study was performed in Puruzinho Lake, a remote body of water in the Brazilian Amazon from which a riparian human population obtains an important part of its animal protein intake. Samples from 92 individuals, comprising 13 species and four trophic guilds (iliophagous, planktivorous, omnivorous, and piscivorous fish) were analysed for the determination of trace elements (Fe, Cr, Mn, Ni, Zn, Ca, Sr, Cd, Sn, Tl and Pb) and methylmercury concentrations.

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Aim: To evaluate a lesion detection algorithm designed to detect focal cortical dysplasia (FCD) in children undergoing stereoelectroencephalography (SEEG) as part of their presurgical evaluation for drug-resistant epilepsy.

Method: This was a prospective, single-arm, interventional study (Idea, Development, Exploration, Assessment, and Long-Term Follow-Up phase 1/2a). After routine SEEG planning, structural magnetic resonance imaging sequences were run through an FCD lesion detection algorithm to identify putative clusters.

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Endovascular procedures have become a mainstay in the treatment of neurovascular pathologies like arteriovenous malformations and aneurysms. Catheter-induced blister-like aneurysms (BBAs) have not been described so far in the neurosurgical literature. The authors report a rare case of a possible, catheter-induced (iatrogenic) BBA of the supra-ventral wall of the internal carotid artery (ICA) post-endovascular coiling for posterior communicating artery (PComA) aneurysm and bring the rapid progression of BBA and the grade prognosis.

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Background: Post-styloid parapharyngeal space tumours (PPS) have a notorious course owing to their anatomy and proximity to neurovascular bundles. Nerve injuries are usual outcomes in schwannomas. Our case is the first documented complication of contralateral hemiplegia occurring in the postoperative period in a benign PPS tumour.

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The acceptorless dehydrogenative coupling (ADC) between alcohols and amines to produce imines has been achieved mostly by employing precious-metal-based complexes or complexes of earth-abundant metal ions with sensitive and complicated ligand systems as catalysts mostly under harsh reaction conditions. Methodologies using readily available earth-abundant metal salts as catalysts without the requirement of ligand, oxidant, or any external additives are not explored. We report an unprecedented microwave-assisted CoCl-catalyzed acceptorless dehydrogenative coupling of benzyl alcohol and amine for the synthesis of -aldimines, -heterocycles, and H under mild condition, without any complicated exogenous ligand template, oxidant, or other additives.

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Actinomycetes are considered a never-ending treasure trove of biometabolites, which always fascinated researchers. However, to combat with newly emerging bacterial strains, the search for novel or analogs of existing therapeutic agents is recommended. In this context, this research work was carried out to search for a biopotent Actinomycetal strain grown in untapped soil, near the Hirakud dam.

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Objective: The accurate prediction of seizure freedom after epilepsy surgery remains challenging. We investigated if (1) training more complex models, (2) recruiting larger sample sizes, or (3) using data-driven selection of clinical predictors would improve our ability to predict postoperative seizure outcome using clinical features. We also conducted the first substantial external validation of a machine learning model trained to predict postoperative seizure outcome.

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