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Materials Sciences and Applications 2011年第4期2卷 251-257页

作者： Pawan kumar Kishor Purushottamrao Kolhe Sashikant Janardan Morey chanchal kumar datta 不详

This paper demonstrates the enhancement of mechanical properties and effective optimization of pulsed GTAW process parameters on aluminium alloy 6061 using sinusoidal AC wave with argon plus helium gas mixtures. Modified Taguchi Method (MTM) was employed to formulate experimental layout and to study effect of process parameter optimization on mechanical properties of the weld joints. Microstructural characterization of weld joint was carried out to understand the structural property correlation with process parameters.

关键词： Pulsed GTAW Aluminium Alloy 6061 Gas Mixtures Mechanical Properties Modified Taguchi Method Microstructures

Heat Transfer and Thermal Characteristics Effects on Moving Plate Impinging from Cu-Water Nanofluid Jet

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Journal of Thermal Science 2020年第1期29卷 182-193页

作者： datta Abanti kumar Sonal HALDER Pabitra Department of Aerospace Engineering and Applied Mechanics Indian Institute of Engineering Science and Technology

The present article is focused on modelling of flow and heat transfer behaviour of Cu-water nanofluid in a confined slot jet impingement on hot moving *** parameters such as various moving plate velocities,nanoparticles at various concentrations,variation in turbulent Reynolds number and jet nozzle to plate distance have been considered to study the flow field and convective heat transfer performance of the *** of distribution of local and average Nusselt number and skin friction coefficients at the plate surface are shown to elucidate the heat transfer and fluid flow *** analysis of both stream function and isotherm contours are carried out to perceive the flow pattern and heat transfer mechanism due to moving *** results revealed that average Nusselt number significantly rises with plate velocity in addition with jet inlet Reynolds *** of the average Nusselt numbers are presented.

关键词： Cu-water nanofluid,multiphase mixture model moving plate jet impingement CFD

Effects of patch size, disturbances on diversity and structural traits of tropical semi-evergreen forest in the lowland Indo Burma hotspot: implication on conservation of the threatened tree species

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Journal of Mountain Science 2016年第8期13卷 1397-1410页

作者： Koushik MAJUMDAR Badal kumar datta Plant Taxonomy and Biodiversity Laboratory Department of Botany Tripura University

Information on geographic distribution, population and threat status of most globally red listed species in the Indo Burma zone are inadequate. Given the increase in the prevalence of isolated forest patches in the part of this hotspot, evaluation is necessary on how size of the remnant forest patches and on-going disturbances affects structure and diversity of remaining habitats including the population of some globally threatened tree species. Quantitative vegetation inventory by 500 m long and lO m wide （0.5 ha） line transects were randomly set in nine fragmented tropical semi-evergreen forest patches in Tripura, Northeast India. The studied forests patches grouped into small, medium and large based on their respected sizes. Spatial variability was analysed in woody species diversity and structure along the patch size gradients and their response to both patch size and anthropogenic disturbances. Out of 167 species, 13 identified as red-listed species by IUCN under the present inventory. Most of the diversity and structural parameters showed statistically significant positive response with the forest patch size, except for stand dominance, disturbance, sapling density and number of aggregated distribution pattern decreased when patch size increased. In addition, most of the diversity and structural attributes showed negative response with disturbances. Present baseline data would serve as an effective tool for management and protection of this important forest type. Future habitat restoration programme and strategies for relocation of additional population and re-introduction of those globally threatened trees are recommended.

关键词： Forest diversity Semi-evergreen forest Threatened species Population composition IndoBurma zone

An Elegant Coupled Model

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Advances in Atmospheric Sciences 1993年第2期10卷 257-260页

作者： chanchal Guha-Roy Dilip kumar Sinha Center for Atmospheric Sciences University of Calcutta 92 Acharya Prafulla Chandra RoadCalcutta-700009 IndiaCenter for Atmospheric Sciences University of Calcutta 92 Acharya Prafulla Chandra RoadCalcutta-700009 India

This paper deals with a new family of coupled wave equations which are basically nonlinear in nature. An analytical study enables us to show that these equations exhibit solitary wave profiles. Finally some remarks ar... 详细信息

关键词： An Elegant Coupled Model

Changes of woody species diversity, horizontal and vertical distribution of stems across interior to outside within a primate rich habitat of Northeast India

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Journal of Forestry Research 2016年第4期27卷 787-798页

作者： Koushik Majumdar Bal Krishan Choudhary Badal kumar datta Plant Taxonomy and Biodiversity Lab. Department of Botany Tripura University

The interior forest of protected area（PA）recover quickly in terms of greater diversity and structural complexity than peripheral and outsides, which may be due to high plant-frugivore interactions in the interior forest than the disturbed outsides. To describe the structural and functional differences in tree communities from interior to outside forests with in small PA, we quantitatively analyzed the vegetation of Trishna Wildlife Sanctuary, a rich primate habitat of Northeast India. Vegetation was sampled at C10 cm girth at breast height by 10 m 9 500 m sized20 line transects（10 ha） laid in the interior（N = 7）,peripheral（N = 7） and outside（N = 6） zones of this sanctuary. All transects were ordinated by Principal Component Analysis based on correlation between diversity and existing disturbance indices. We found significant differences（P ／ 0.05） in taxonomic richness and diversity indices between the habitat. Van diagram confirmed greater unique species richness in the interior zone（64） than peripheral（28） and outside（6） zones. Overall density（ha-1） did not differed across the zones, but basal area（m2ha-1） was significantly（P ／ 0.01） high in peripheral zone. Vertical distribution of stem density was linearly declined across zones（r2adj[ 0.70; P ／ 0.01） with increase in the canopy height. Horizontal distribution of adult stems showed significant inverse quadratic relationship（r2adj[ 0.80; P ／ 0.001）, which suggests very low density of canopy forming voluminous trees in the interior *** protection, restoration and management of interior regions are required to preserve local plant genetic diversity and also to maintain suitable habitat for threatened wildlife.

关键词： interior outside habitat restoration Northeast disturbance quickly inverse preserve quadratic

Inhibition of the emergence of multi drug resistant Staphylococcus aureus by Withania somnifera root extracts

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Asian Pacific Journal of Tropical Medicine 2011年第11期4卷 917-920页

作者： Shuvo datta Nishith kumar Pal Ashoke kumar Nandy Department of Microbiology School of Tropical MedicineKolkata-700 073India Department of Microbiology IPGMER244 AJC Rose Road(UCM Building)Kolkata-700 020India Department of Clinical & Experimental Pharmacology School of Tropical MedicineKolkata-700073India

Objective:To search systematically for an alternative therapy with compounds particularly from plant ***:Efficacy test of different root extracts of Withania somnifera(W. somnifera)(L) Dunal against multi drug resistant(MDR) Staphylococcus aureus(***) variants was performed following the agar well diffusion *** of susceptibility pattern of the isolates was carried out by employing disk diffusion method using standard antibiotic disks. Results:In vitro study with *** root extracts was found to be effective against all the MDR *** strains isolated from local and patient *** root extracts of WS showed different degree of effectiveness against the ***:The major active principles responsible for the antibacterial efficacy were mainly present in methanol(MeOH) extract and ethanol(EtOH) extracts as well as in butanol(BuOH) extract *** all the extracts the BuOH fraction was found to be most active against all the isolates but aqueous extract was the least active *** it may be concluded that the antimicrobials from *** may raise an alternative therapy for MDR staphylococcal infections in near future.

关键词： Withania somnifera Antibacterial activity MDR Staphylococcus aureus

Fractional-Order Model of the Disease Psoriasis:A Control Based Mathematical Approach

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Journal of Systems Science & Complexity 2016年第6期29卷 1565-1584页

作者： CAO Xianbing datta Abhirup AL BASIR Fahad ROY Priti kumar College of Science Beijing Technology and Business University Centre for Mathematical Biology and Ecology Department of MathematicsJadavpur University

Autoimmune diseases are generated through irregular immune response of the human body. Psoriasis is one type of autoimmune chronic skin diseases that is differentiated by T-Cells mediated hyper-proliferation of epidermal Keratinocytes. Dendritic Cells and CD8＋ T-Cells have a significant role for the occurrence of this disease. In this paper, the authors have developed a mathematical model of Psoriasis involving CD4＋ T-Cells, Dendritic Ceils, CD8＋ T-Cells and Keratinocyte cell populations using the fractional differential equations with the effect of Cytokine release to observe the impact of memory on the cell-biological system. Using fractional calculus, the authors try to explore the suppressed memory, associated with the cell-biological system and to locate the position of Keratinocyte cell population as fractional derivative possess non-local property. Thus, the dynamics of Psoriasis can be predicted in a better way using fractional differential equations rather than its corresponding integer order model. Finally, the authors introduce drug into the system to obstruct the interaction between CD4＋ T-Cells and Keratinocytes to restrict the disease Psoriasis. The authors derive the Euler-Lagrange conditions for the optimality made through Matlab by developing iterative of the drug induced system. Numerical simulations are schemes.

关键词： Fractional differential equations (FDEs) memory optimal control problem pMHC Pso-riasis.

Sources and dynamics of sedimentary organic matter in Sundarban mangrove estuary from Indo-Gangetic delta

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Ecological Processes 2017年第1期6卷 69-83页

作者： M.Bala Krishna Prasad Alok kumar A.L.Ramanathan Dilip kumar datta 22616 Shining Harness Street ClarksburgMD 20871USA School of Environmental Sciences Jawaharlal Nehru UniversityNew Delhi 110067India Environmental Science Discipline Khulna UniversityKhulna 9208Bangladesh

Introduction:Mangrove forests are highly productive ecosystems distributed along the tropical coast *** biogeochemistry of mangroves are primarly driven by both allochthonous and autochthonous *** of organic matter in coastal ecosystems enables to understand the biogeochemical transformation of organic matter and its influence on ecosystem productivity in response to various changing environmental ***,the elemental and stable carbon and nitrogen levels were employed to understand the organic matter(OM)dynamics in the Sundarban mangrove ecosystem(India-Bangladesh).Results:Differences in stable isotope values indicate that variable sources influence the OM dynamics in Sundarban *** progressive enrichment inδ13C levels along the land-coastal continuum indicates that the terrestrial and marine inputs are dominant at the landward and seaward ends,*** CuO oxidationderived lignin phenol monomers describe significant levels of total lignin are preserved in Sundarban mangrove sediments during *** phenol monomer ratios are lower than the plant litter explaining that aromatic ring cleavage is the dominant mechanism for the lignin ***,the Ad/Al ratios were higher than the plant litter explaining the oxidation of propyl side chain of vascular OM influencing the carbon cycling in Sundarban ***,the Ad/Al ratios describe the vascular OM degradation is through the oxidation of propyl side ***:The regional variability in land-use regulates the spatial variability in C,N,OC/TN ratio,δ13C andδ15N between the Indian and the Bangladesh Sundarban mangroves and indicates that in the upstream terrestrial organic matter and/or mangrove plant litter contribute significant amount of organic matter,whereas the marine POC influences the organic matter dynamics in *** three end-member mixing model applying terrestrial plant litter,seston,and marine POC as e

关键词： Sundarban mangrove Organic carbon Stable isotopes Lignin phenols Three end-member mixing model

Loss of disabled-2 expression is an early event in esophageal squamous tumorigenesis

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World Journal of Gastroenterology 2006年第37期12卷 6041-6045页

作者： kumar Anupam Chatopadhyay Tusharkant Siddhartha datta Gupta Ralhan Ranju Department of Biochemistry All India Institute of Medical Sciences Ansari Nagar New Delhi 110029 India Department of GI Surgery All India Institute of Medical Sciences Ansari Nagar New Delhi 110029 India Department of Pathology All India Institute of Medical Sciences Ansari Nagar New Delhi 110029 India

AIM: Disabled-2 (DAB2) is a candidate tumor-suppressor gene identified in ovarian cancer that negatively influences mitogenic signal transduction of growth factors and blocks ras activity. In a recent study, we observed down-regulation of DAB2 transcripts in ESCCs using cDNA microarrays. In the present study, we aimed to determine the clinical significance of loss of DAB2 protein in esophageal tumorigenesis, hypothesizing that DAB2 promoter hypermethylation-mediated gene silencing may account for loss of the protein. METHODS: DAB2 expression was analyzed by immunohistochemistry in 50 primary esophageal squamous cell carcinomas (ESCCs), 30 distinct hyperplasia, 15 dysplasia and 10 non-malignant esophageal tissues. To determine whether promoter hypermethylation contributes to loss of DAB2 expression in ESCCs, methylation status of DAB2 promoter was analyzed in DAB2 immuno-negative tumors using methylation-specifi c PCR. RESULTS: Loss of DAB2 protein was observed in 5/30 (17%) hyperplasia, 10/15 (67%) dysplasia and 34/50 (68%) ESCCs. Significant loss of DAB2 protein was observed from esophageal normal mucosa to hyperplasia, dysplasia and invasive cancer (Ptrend < 0.001). Promoter hypermethylation of DAB2 was observed in 2 of 10 (20%) DAB2 immuno-negative ESCCs. CONCLUSION: Loss of DAB2 protein expression occurs in early pre-neoplastic stages of development of esophageal cancer and is sustained down the tumorigenic pathway. Infrequent DAB2 promoter methylation in ESCCs suggests that epigenetic genesilencing is only one of the mechanisms causing loss of DAB2 expression in ESCCs.

关键词： Disabled-2 DOC-2 Esophageal cancer Promoter hypermethylation Dysplasia

Hot mold casting process of ancient East India and Bangladesh

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China Foundry 2010年第2期7卷 171-177页

作者： Barnali Mandal Prasanta kumar datta Department of Metallurgical & Material Engineering Jadavpur University

Ancient casting process for production of brass or bronze utensils and icons were made in hot molds using clay molded investment casting or piece mold process,as presumed by *** mold process is still traditionally practiced in many parts of Eastern India and Bangladesh along with investment casting ***,Bengal artisans are more accustomed to piece mold process unlike tribal artisans who practiced investment casting *** piece mold casting process has been reconstructed to get the idea of metal characteristics in order to investigate ancient casting process of Bengal and *** characterization of ancient archaeo-metal products come to a type of cast Cu-Sn-Zn-Pb type quaternary alloy produced by a slow freezing *** these alloys physically differ from the traditional cast alloy of binary Cu-Zn type brass,the physical characteristics are similar to the binary cast alloy *** investigation throws light on the similarity of the production processes by which ancient artisans probably produced cast metal products.

关键词： piece mold casting characterization hot-molds copper-alloys