Kalyani Government Engineering College

About: Kalyani Government Engineering College is a education organization based out in Kalyani, West Bengal, India. It is known for research contribution in the topics: Catalysis & Population. The organization has 2955 authors who have published 6686 publications receiving 80472 citations.

Role of metal-reducing bacteria in arsenic release from Bengal delta sediments

Abstract: The contamination of ground waters, abstracted for drinking and irrigation, by sediment-derived arsenic threatens the health of tens of millions of people worldwide, most notably in Bangladesh and West Bengal1,2,3. Despite the calamitous effects on human health arising from the extensive use of arsenic-enriched ground waters in these regions, the mechanisms of arsenic release from sediments remain poorly characterized and are topics of intense international debate4,5,6,7,8. We use a microscosm-based approach to investigate these mechanisms: techniques of microbiology and molecular ecology are used in combination with aqueous and solid phase speciation analysis of arsenic. Here we show that anaerobic metal-reducing bacteria can play a key role in the mobilization of arsenic in sediments collected from a contaminated aquifer in West Bengal. We also show that, for the sediments in this study, arsenic release took place after Fe(iii) reduction, rather than occurring simultaneously. Identification of the critical factors controlling the biogeochemical cycling of arsenic is one important contribution to fully informing the development of effective strategies to manage these and other similar arsenic-rich ground waters worldwide.

Regulation of matrix metalloproteinases: an overview.

Abstract: Matrix metalloproteinases (MMPs) are a major group of enzymes that regulate cell-matrix composition. MMP genes show a highly conserved modular structure. Ample evidence exists on the role of MMPs in normal and pathological processes, including embryogenesis, wound healing, inflammation, arthritis, cardiovascular diseases, pulmonary diseases and cancer. The expression patterns of MMPs have interesting implications for the use of MMP inhibitors as therapeutic agents. Insights might be gained as to the preference for a general MMP inhibitor as opposed to an inhibitor designed to be specific for certain MMP family members as it relates to a defined disease state, and may give clues to potential side effects. The signalling pathways that lead to induction of expression of MMPs are still incompletely understood, but certain patterns are beginning to emerge. Regarding inhibition of MMP expression at the level of kinase pathways, it is possible that selective chemical inhibitors for distinct signalling pathways (e.g. MAPK, PKC) will hopefully, soon be available for initial clinical trials. Overexpression of selective dual specificity MAPK phosphatases have been shown to prevent MMP promoter activation which could also be used as a novel strategy to prevent activation of AP-1 and ETS transcription factors and MMP promoters in vivo. Interactions between members of different transcription factors provide fine-tuning of the transcriptional regulation of MMP promoter activity. MMPs play a crucial role in tumor invasion. Although the expression of MMPs in malignancies has been studied widely, the specific role of distinct MMPs in the progression of cancer may be more complex than has been assumed. For example, it has recently been shown that MMP-3, MMP-7, MMP-9 and MMP-12 can generate angiostatin from plasminogen, indicating that their expression in peritumoral area may in fact serve to limit angiogenesis and thereby inhibit tumor growth and invasion. The recent view about the role of stromal cells in the progression of cancer cell growth and metastasis is particularly interesting, and additional studies about the regulation of MMP gene expression and activity in malignancies are needed to understand the role and regulation of MMPs in tumor cell invasion.

Validity index for crisp and fuzzy clusters

Abstract: In this article, a cluster validity index and its fuzzification is described, which can provide a measure of goodness of clustering on different partitions of a data set. The maximum value of this index, called the PBM-index, across the hierarchy provides the best partitioning. The index is defined as a product of three factors, maximization of which ensures the formation of a small number of compact clusters with large separation between at least two clusters. We have used both the k-means and the expectation maximization algorithms as underlying crisp clustering techniques. For fuzzy clustering, we have utilized the well-known fuzzy c-means algorithm. Results demonstrating the superiority of the PBM-index in appropriately determining the number of clusters, as compared to three other well-known measures, the Davies–Bouldin index, Dunn's index and the Xie–Beni index, are provided for several artificial and real-life data sets.

Mechanism of antibacterial activity of copper nanoparticles.

Abstract: In a previous communication, we reported a new method of synthesis of stable metallic copper nanoparticles (Cu-NPs), which had high potency for bacterial cell filamentation and cell killing. The present study deals with the mechanism of filament formation and antibacterial roles of Cu-NPs in E. coli cells. Our results demonstrate that NP-mediated dissipation of cell membrane potential was the probable reason for the formation of cell filaments. On the other hand, Cu-NPs were found to cause multiple toxic effects such as generation of reactive oxygen species, lipid peroxidation, protein oxidation and DNA degradation in E. coli cells. In vitro interaction between plasmid pUC19 DNA and Cu-NPs showed that the degradation of DNA was highly inhibited in the presence of the divalent metal ion chelator EDTA, which indicated a positive role of Cu(2+) ions in the degradation process. Moreover, the fast destabilization, i.e. the reduction in size, of NPs in the presence of EDTA led us to propose that the nascent Cu ions liberated from the NP surface were responsible for higher reactivity of the Cu-NPs than the equivalent amount of its precursor CuCl2; the nascent ions were generated from the oxidation of metallic NPs when they were in the vicinity of agents, namely cells, biomolecules or medium components, to be reduced simultaneously.

Causality between energy consumption and economic growth in India: a note on conflicting results

Abstract: This note examines the different direction of causal relation between energy consumption and economic growth in India. Applying Engle–Granger cointegration approach combined with the standard Granger causality test on Indian data for the period 1950–1996, we find that bi-directional causality exists between energy consumption and economic growth. Further, we apply Johansen multivariate cointegration technique on the different set of variables. The same direction of causality exists between energy consumption and economic growth. This is different from the results obtained in earlier studies.