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569 result(s) for "Das, Rakesh"
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Interaction of a quantum particle with gravitational wave in modified gravity theory
We present the formal solution for a quantum mechanical particle responding to gravitational wave (GW) in the framework of modified theories of gravity (MTG) where, apart from the two standard tensorial modes of polarization of GW, we have considered an additional scalar mode. The presence of this longitudinal scalar mode makes it necessary to extend the usual two-dimensional description of matter-GW interaction to a three-dimensional one. Naturally this requires non-trivial changes in the quantum mechanical treatment which we elaborate in this paper.
Computer vision syndrome, musculoskeletal, and stress-related problems among visual display terminal users in Nepal
The use of computers and other Visual Display Terminal (VDT) screens is increasing in Nepal. However, there is a paucity of evidence on the prevalence of Computer Vision Syndrome (CVS) and other occupational health concerns among employees working in front of VDT screens in the Nepalese population. This study aims to estimate the prevalence of CVS, musculoskeletal and work-related stress among VDT screen users in the office, as well as their understanding and usage of preventive measures. The study was a cross-sectional descriptive study among 319 VDT users in office settings in Kathmandu Metropolitan City, Nepal, using a semi-structured self-administered questionnaire. Multivariate logistic regression analysis was conducted to identify the associated factors at 95% CI. P-value <0.05 was considered as statistically significant. The prevalence of CVS was 89.4%. More than eight out of ten study participants reported at least one visual and musculoskeletal symptom. Work-related stress, which was moderate-difficult to handle, was present in 36.7% of the study population. The mean±SD computer usage per day was 7.9±1.9 hours. Tired eye (63.3%), feeling of dry eye (57.8%), headache (56.9%) were the common visual symptoms of CVS reported. Total computer use/day > = 8 hours OR 2.6, improper viewing distance OR 3.2, Not using an anti-glare screen OR 2.6, not using eye-drops, and not wearing protective goggles OR 3.1 were significantly associated with the presence of CVS. There was no statistically significant association between visual symptoms of CVS, musculoskeletal symptoms, and stress with gender. CVS was substantially related to not employing preventive measures, working longer hours, and having an incorrect viewing distance. With more hours per day spent in front of a VDT screen, work-related stress and musculoskeletal complaints were also found to be important correlates. Similarly, work-related stress was found more among those who had less than five years of job.
Cellulolytic and Xylanolytic Enzymes from Yeasts: Properties and Industrial Applications
Lignocellulose, the main component of plant cell walls, comprises polyaromatic lignin and fermentable materials, cellulose and hemicellulose. It is a plentiful and renewable feedstock for chemicals and energy. It can serve as a raw material for the production of various value-added products, including cellulase and xylanase. Cellulase is essentially required in lignocellulose-based biorefineries and is applied in many commercial processes. Likewise, xylanases are industrially important enzymes applied in papermaking and in the manufacture of prebiotics and pharmaceuticals. Owing to the widespread application of these enzymes, many prokaryotes and eukaryotes have been exploited to produce cellulase and xylanases in good yields, yet yeasts have rarely been explored for their plant-cell-wall-degrading activities. This review is focused on summarizing reports about cellulolytic and xylanolytic yeasts, their properties, and their biotechnological applications.
Subarachnoid Hemorrhage and Hydrocephalus
Background: Hydrocephalus associated with subarachnoid hemorrhage is a common neurosurgical problem, the management of which is tailor-made to the patient. It is usually seen with an aneurysmal bleed and is independent of the primary modality of treatment. Aim: This study aimed to provide a comprehensive overview of this important association and discuss the various available treatment modalities. Materials and Methods: A detailed review of the literature was done on the risk factors, pathogenesis, and treatment of hydrocephalus in the setting of subarachnoid hemorrhage. Results: Hydrocephalus occurs in 6% to 67% of subarachnoid hemorrhage (SAH). It may present as acute, subacute, or chronic at the time of presentation. Diagnosis is made with a plain computed tomography scan of the brain, and the treatment is observant, temporary, or permanent cerebrospinal fluid diversion. Conclusion: Hydrocephalus associated with SAH interferes with the outcome of SAH. It prolongs the hospital stay, besides causing additional morbidity. The various risk factors, if present, should warn us to be vigilant, and management is definitely not uniform and is custom made to the patients' needs.
Biomechanical Evaluation of Wasp and Honeybee Stingers
In order to design a painless and mechanically durable micro syringe-needle system for biomedical applications, the study of insect stingers is of interest because of their elegant structures and functionalities. In the present work, the structure, mechanical properties and the mechanical behavior during insertion of wasp and honeybee stingers have been investigated. The non-invasive imaging tool, micro-computed tomography has been employed to reveal the 3D-structures of wasp and honeybee stingers. A quasi-static nanoindentation instrument was used to measure the nanomechanical properties. Both wasp and honeybee stingers have graded mechanical properties, decreasing along their longitudinal direction starting from the base. The computed tomography images and the measured material properties from nanoindentation were fed into a computational framework to determine the mechanical behavior of the stingers during penetration. The computation results predicted the penetration angle of +10° for the wasp stinger and −6° for the honeybee stinger, which mimics the practical insertion mechanism of both stingers. Based on this understanding, a wasp and honeybee stringer inspired micro syringe-needle design has also been proposed.
Marine Bacterial Dextranases: Fundamentals and Applications
Dextran, a renewable hydrophilic polysaccharide, is nontoxic, highly stable but intrinsically biodegradable. The α-1, 6 glycosidic bonds in dextran are attacked by dextranase (E.C. 3.2.1.11) which is an inducible enzyme. Dextranase finds many applications such as, in sugar industry, in the production of human plasma substitutes, and for the treatment and prevention of dental plaque. Currently, dextranases are obtained from terrestrial fungi which have longer duration for production but not very tolerant to environmental conditions and have safety concerns. Marine bacteria have been proposed as an alternative source of these enzymes and can provide prospects to overcome these issues. Indeed, marine bacterial dextranases are reportedly more effective and suitable for dental caries prevention and treatment. Here, we focused on properties of dextran, properties of dextran—hydrolyzing enzymes, particularly from marine sources and the biochemical features of these enzymes. Lastly the potential use of these marine bacterial dextranase to remove dental plaque has been discussed. The review covers dextranase-producing bacteria isolated from shrimp, fish, algae, sea slit, and sea water, as well as from macro- and micro fungi and other microorganisms. It is common knowledge that dextranase is used in the sugar industry; produced as a result of hydrolysis by dextranase and have prebiotic properties which influence the consistency and texture of food products. In medicine, dextranases are used to make blood substitutes. In addition, dextranase is used to produce low molecular weight dextran and cytotoxic dextran. Furthermore, dextranase is used to enhance antibiotic activity in endocarditis. It has been established that dextranase from marine bacteria is the most preferable for removing plaque, as it has a high enzymatic activity. This study lays the groundwork for the future design and development of different oral care products, based on enzymes derived from marine bacteria.
How enzymatic activity is involved in chromatin organization
Spatial organization of chromatin plays a critical role in genome regulation. Previously, various types of affinity mediators and enzymes have been attributed to regulate spatial organization of chromatin from a thermodynamics perspective. However, at the mechanistic level, enzymes act in their unique ways and perturb the chromatin. Here, we construct a polymer physics model following the mechanistic scheme of Topoisomerase-II, an enzyme resolving topological constraints of chromatin, and investigate how it affects interphase chromatin organization. Our computer simulations demonstrate Topoisomerase-II’s ability to phase separate chromatin into eu- and heterochromatic regions with a characteristic wall-like organization of the euchromatic regions. We realized that the ability of the euchromatic regions to cross each other due to enzymatic activity of Topoisomerase-II induces this phase separation. This realization is based on the physical fact that partial absence of self-avoiding interaction can induce phase separation of a system into its self-avoiding and non-self-avoiding parts, which we reveal using a mean-field argument. Furthermore, motivated from recent experimental observations, we extend our model to a bidisperse setting and show that the characteristic features of the enzymatic activity-driven phase separation survive there. The existence of these robust characteristic features, even under the non-localized action of the enzyme, highlights the critical role of enzymatic activity in chromatin organization.
Harnessing Activated Hydrochars: A Novel Approach for Pharmaceutical Contaminant Removal
Water contamination is a pervasive global crisis, affecting over 2 billion people worldwide, with pharmaceutical contaminants emerging as a significant concern due to their persistence and mobility in aquatic ecosystems. This review explores the potential of activated hydrochars, sustainable materials produced through biomass pyrolysis, to revolutionize the removal of pharmaceutical contaminants from water sources. These materials possess high surface area, porous structure, and exceptional adsorption capabilities, making them a promising solution. The impact of pharmaceutical contaminants on aquatic ecosystems and human health is far-reaching, affecting biodiversity, water quality, and public health. To address this complex issue, a diverse range of techniques, including adsorption, biodegradation, and advanced oxidation processes, are employed in the pharmaceutical industry. Activated hydrochars offer substantial adsorption capacity, sustainable feedstock origins, and a minimal carbon footprint. This review highlights their potential in pharmaceutical contaminant removal and their broader applications in improving soil and air quality, resource recovery, and sustainable waste management. Interdisciplinary collaboration and the development of intelligent treatment systems are essential to fully unlock the potential of activated hydrochars. Regulatory support and policy frameworks will facilitate their responsible and widespread application, promising a cleaner and more sustainable future. This paper aims to inform scientists, environmental experts, policymakers, and industry stakeholders about the promising role of activated hydrochars in addressing pharmaceutical contaminant challenges.
Molecular characterization and immune role of TLR7 in Labeo rohita
Toll-like receptors (TLRs) play a vital role in the immune response by recognizing pathogen-associated molecular patterns (PAMPs) and triggering signaling pathways that activate innate immunity. In bony fish, TLR7 is essential for both antiviral and antibacterial defense; however, its interactions with a wide range of ligands and pathogens are still not well understood across various fish species. This study focuses on the identification and characterization of TLR7 in (LrTLR7) and aims to evaluate its response to pathogen challenges and stimulation by PAMPs. To clone the TLR7 gene, RNA was extracted from kidney tissue using a standard protocol, followed by cDNA synthesis with commercial kits. The TLR7 gene was amplified by PCR, and the gel-purified product was cloned into the pGEM-T Easy vector. DNA sequencing and BLAST analysis confirmed the identity of the LrTLR7 gene. The ORF of LrTLR7 cDNA was predicted using ORF-finder, while structural motifs in the encoded protein were identified through SMART. Phylogenetic relationships were analyzed using MEGA7 to construct evolutionary trees. Gene expression profiles of LrTLR7 were evaluated by quantitative real-time PCR (qRT-PCR) across developmental stages, tissues/organs of rohu fingerlings, and during challenges with and infections, as well as LPS and Poly I:C stimulation. Mucosal RBCs and PBLs were isolated using density-gradient centrifugation with HiSep™ LSM 1077 (Himedia, India). Cultured gill (LRG) cells in Leibovitz's L-15 medium were infected with or at a multiplicity of infection (MOI) of 1, following established protocols. LrTLR7 showed the closest phylogenetic affinity to TLR7 in . During embryonic development, LrTLR7 expression surged dramatically (~111-fold, <0.05) in embryos at 120 h post-fertilization (hpf). In juveniles, the gene was ubiquitously expressed across tissues/organs, with peak expression in gills (~2,000-fold). Following infection with or , LrTLR7 gene transcripts in the liver increased sharply at 6 hpi (~93-fold and ~53,000-fold, respectively). In the infected fish, mucosal RBCs showed a ~500,000-fold upregulation ( <0.05), while PBLs exhibited maximal responses at 24 hpi (~5,000-fold for and ~10 million-fold for ). In the LRG cell line, LrTLR7 gene expression rose ~30-fold by 3 hpi. during infection. stimulation with LPS or poly I:C triggered a ~30,000-fold increase in hepatic LrTLR7 expression at 12 h post-stimulation, with kidney tissue showing secondary activation. Mucosal RBCs and PBLs displayed rapid (1-3 h) LrTLR7 upregulation following ligand exposure. Imiquimod and gardiquimod activated LrTLR7-signalling pathways in both and systems, elevating transcription of IRF7 and type I interferon genes. Similar to higher vertebrates, LrTLR7 plays a crucial role in responding to pathogenic invasions and various PAMPs to induce innate immunity. Consequently, TLR7 in fish represents a significant target for immune activation using specific agonists or ligands, which could aid in the prevention of fish diseases.
Order-disorder transition in active nematic: A lattice model study
We introduce a lattice model for active nematic composed of self-propelled apolar particles, study its different ordering states in the density-temperature parameter space, and compare with the corresponding equilibrium model. The active particles interact with their neighbours within the framework of the Lebwohl-Lasher model, and move anisotropically along their orientation to an unoccupied nearest neighbour lattice site. An interplay of the activity, thermal fluctuations and density gives rise distinct states in the system. For a fixed temperature, the active nematic shows a disordered isotropic state, a locally ordered inhomogeneous mixed state, and bistability between the inhomogeneous mixed and a homogeneous globally ordered state in different density regime. In the low temperature regime, the isotropic to the inhomogeneous mixed state transition occurs with a jump in the order parameter at a density less than the corresponding equilibrium disorder-order transition density. Our analytical calculations justify the shift in the transition density and the jump in the order parameter. We construct the phase diagram of the active nematic in the density-temperature plane.