Government College

About: Government College is a based out in . It is known for research contribution in the topics: Population & Ring (chemistry). The organization has 4481 authors who have published 5986 publications receiving 57398 citations.

Groundwater geochemistry and identification of hydrogeochemical processes in a hard rock region, Southern India.

Abstract: Hydrogeochemical investigations were carried out in Chithar River basin, Tamil Nadu, India to identify the major geochemical processes that regulate groundwater chemistry. For this study, long-term (1991-1997) and recent water quality data (2001-2002) for 30 groundwater wells spread over the study area were used to understand the groundwater geochemistry and hydrogeochemical process regulating groundwater quality. Groundwater quality data obtained from more than 400 water samples were employed. Results of electrical conductivity and chloride express large variation between minimum and maximum values and high standard deviation, which suggests that the water chemistry in the study region is not homogeneous and influenced by complex contamination sources and geochemical process. Nitrate and depth to water table expose the influences of surface contamination sources, whereas dissolved silica, fluoride and alkalinity strongly suggest the effect of rock-water interaction. In the study region, weathering of carbonate and silicate minerals and ion exchange reactions predominantly regulate major ion chemistry. Besides, the concentrations of sulphate, chloride and nitrate firmly suggest the impact of agricultural activities such as irrigation return flow, fertiliser application, etc on water chemistry in the study region.

Coesite in Himalayan eclogite and implications for models of India-Asia collision

Abstract: Coesite, recognized petrographically and confirmed by in situ Raman microprobe spectroscopy, is reported from an eclogite from the Kaghan valley, Pakistan, and represents the first record of ultrahigh-pressure metamorphism in the Himalaya. The formation conditions of >27 kbar implied by the presence of coesite are supported by garnet-pyroxene- phengite barometry (27–29 kbar, 690–750 °C). If, as seems likely from previous field and geochronologic studies, the eclogites represent metamorphosed dikes, sills, and lava flows of Permian age within the granitic gneiss-metapelite-marble sequence of the Higher Himalayan crystalline nappes, then continental crust—the leading edge of the Indian plate— must also have been subducted to coesite-forming depths (90–100 km). This more than doubles previous depth estimates and, on the basis of available geochronological data for this area, requires average exhumation rates at least twice as fast (∼10 mm/yr) as previously imagined. A further implication, based on interpretations of deep seismic data, is that the present-day shallow angle of subduction of Indian plate lithosphere beneath Tibet represents a significant change from an initially much steeper angle.

Activation of microglia and astrocytes: a roadway to neuroinflammation and Alzheimer's disease.

Abstract: Alzheimer's disease (AD) is a neurodegenerative disease that is of high importance to the neuroscience world, yet the complex pathogenicity is not fully understood. Inflammation is usually observed in AD and could implicate both beneficial or detrimental effects depending on the severity of the disease. During initial AD pathology, microglia and astrocyte activation is beneficial since they are involved in amyloid-beta clearance. However, with the progression of the disease, activated microglia elicit detrimental effects by the overexpression of pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) bringing forth neurodegeneration in the surrounding brain regions. This results in decline in Aβ clearance by microglia; Aβ accumulation thus increases in the brain resulting in neuroinflammation. Thus, Aβ accumulation is the effect of increased release of pro-inflammatory molecules. Reactive astrocytes acquire gain of toxic function and exhibits neurotoxic effects with loss of neurotrophic functions. Astrocyte dysfunctioning results in increased release of cytokines and inflammatory mediators, neurodegeneration, decreased glutamate uptake, loss of neuronal synapses, and ultimately cognitive deficits in AD. We discuss the role of intracellular signaling pathways in the inflammatory responses produced by astrocytes and microglial activation, including the glycogen synthase kinase-3β, nuclear factor kappa B cascade, mitogen-activated protein kinase pathways and c-Jun N-terminal kinase. In this review, we describe the role of neuroinflammation in the chronicity of AD pathogenesis and an overview of the recent research towards the development of new therapies to treat this disorder.