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Search Results: 1 - 10 of 719 matches for " Dhrubajyoti Chattopadhyay "
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Rectangular Microstrip Antenna Using Inductive Septums for Dual Band Operation with a New Resonant Mode  [PDF]
Rajeev Ranjan, Manish Kr. Verma, Shounak Mukherjee, Dhrubajyoti Ghosh, Sudipta Chattopadhyay
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2012, DOI: 10.4236/jemaa.2012.47040
Abstract: A novel rectangular microstrip antenna on conventional dielectric substrate with centrally loaded inductive septums are proposed for dual band operation. The proposed antenna has been thoroughly investigated and the results are presented in the paper. The conventional patch antenna fabricated on common substrates always resonates at its dominant TM10 mode which produces the radiation field along its broadside direction. In the present investigation, the same microstrip antenna is designed on conventional substrate with centrally located inductive septums beneath the patch, with a view to develop a new resonant mode which will produce radiation like dominant TM10 mode. The speciality of the proposed antenna is to excite a new resonant mode with good impedance bandwidth while the traditional dominant TM10 mode is kept unaltered. A thorough quantitative analysis is presented to justify the reason of generation of new resonant mode along with the traditional dominant TM10 mode. An easy and handful formulation has been established for calculation of the frequency for new resonant mode as a function of antenna parameters and the gap between the septums. The proposed idea has been verified through a commercial software package for a patch operating in C band and an excellent agreement is revealed.
Co-inoculation Effects of Nitrogen Fixing and Phosphate Solublising Micro-Organisms on Teak Tectona grandis and Indian redwood
Bhrigu Aditya,Abhrajyoti Ghosh,Dhrubajyoti Chattopadhyay
eJournal of Biological Sciences , 2009,
Abstract: The effect of nitrogen fixing Azotobacter and phosphate solublising Bacillus megaterium on the growth of two trees; Teak (Tectona grandis) and Indian redwood (Chukrasia tubularis) were tested under nursery condition. The pottery mixture for the Teak and Burmese almond wood seedlings were inoculated with both nirogen Fixing Bacteria and phosphate Solublising Bacteria. The co-inoculation effects were also monitored along with the application of either of single super phosphate or rock phosphate alone or in combination of both. The seedling height and collar diameter of the seedlings were measured after 120 days of trial. Statistically significant positive effect upon co-inoculation was observed on the seedling height and collar diameter for C.tubularis [Critical difference height = 1.11 (P≤ 0.05) and 1.51 (P≤ 0.01); Critical difference collar diameter = 0.18 (P≤ 0.05) and 0.24 (P≤0.01)]. The seedling height of T.grandis was found to be increased significantly upon co-inoculation [Critical difference height = 3.28 (P ≤ 0.05) and 4.67 (P ≤ 0.01)] but the collar diameter showed no significant increase. Current public concerns about the side effects of agrochemicals on human health have renewed interest in bio fertilizers. The present study demonstrated the positive effects of co-inoculation of NFB and PSB on C.tubularis and T.grandis. This finding could be useful for developing a new formulation for biofertilizer under field conditions.
miR-17-5p Downregulation Contributes to Paclitaxel Resistance of Lung Cancer Cells through Altering Beclin1 Expression
Abhisek Chatterjee, Dhrubajyoti Chattopadhyay, Gopal Chakrabarti
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0095716
Abstract: Non- small- cell lung cancer (NSCLC) is one of the most leading causes of cancer-related deaths worldwide. Paclitaxel based combination therapies have long been used as a standard treatment in aggressive NSCLCs. But paclitaxel resistance has emerged as a major clinical problem in combating non-small-cell lung cancer and autophagy is one of the important mechanisms involved in this phenomenon. In this study, we used microRNA (miRNA) arrays to screen differentially expressed miRNAs between paclitaxel sensitive lung cancer cells A549 and its paclitaxel-resistant cell variant (A549-T24). We identified miR-17-5p was one of most significantly downregulated miRNAs in paclitaxel-resistant lung cancer cells compared to paclitaxel sensitive parental cells. We found that overexpression of miR-17-5p sensitized paclitaxel resistant lung cancer cells to paclitaxel induced apoptotic cell death. Moreover, in this report we demonstrated that miR-17-5p directly binds to the 3′-UTR of beclin 1 gene, one of the most important autophagy modulator. Overexpression of miR-17-5p into paclitaxel resistant lung cancer cells reduced beclin1 expression and a concordant decease in cellular autophagy. We also observed similar results in another paclitaxel resistant lung adenosquamous carcinoma cells (H596-TxR). Our results indicated that paclitaxel resistance of lung cancer is associated with downregulation of miR-17-5p expression which might cause upregulation of BECN1 expression.
Cellular and molecular mechanisms of cigarette smoke-induced lung damage and prevention by vitamin C
Shuvojit Banerjee, Ranajoy Chattopadhyay, Arunava Ghosh, Hemanta Koley, Koustubh Panda, Siddhartha Roy, Dhrubajyoti Chattopadhyay, Indu B Chatterjee
Journal of Inflammation , 2008, DOI: 10.1186/1476-9255-5-21
Abstract: Vitamin C-restricted guinea pigs were exposed to cigarette smoke (5 cigarettes/day; 2 puffs/cigarette) for 21 days with and without supplementation of 15 mg vitamin C/guinea pig/day. Oxidative damage, apoptosis and lung injury were assessed in vitro, ex vivo in A549 cells as well as in vivo in guinea pigs. Inflammation was measured by neutrophilia in BALF. p-Benzosemiquinone was isolated from freshly prepared aqueous extract of cigarette smoke and characterized by various physico-chemical methods, including mass, NMR and ESR spectroscopy. p-Benzosemiquinone-induced lung damage was examined by intratracheal instillation in guinea pigs. Lung damage was measured by increased air spaces, as evidenced by histology and morphometric analysis. Oxidative protein damage, MMPs, VEGF and VEGFR2 were measured by western blot analysis, and formation of Michael adducts using MALDI-TOF-MS. Apoptosis was evidenced by TUNEL assay, activation of caspase 3, degradation of PARP and increased Bax/Bcl-2 ratio using immunoblot analysis and confocal microscopy.Exposure of guinea pigs to cigarette smoke resulted in progressive protein damage, inflammation, apoptosis and lung injury up to 21 days of the experimental period. Administration of 15 mg of vitamin C/guinea pig/day prevented all these pathophysiological effects. p-Benzosemiquinone mimicked cigarette smoke in causing protein modification and apoptosis in vitro and in A549 cells ex vivo as well as apoptosis and lung damage in vivo. All these pathophysiological events were also prevented by vitamin C.p-Benzosemiquinone appears to be a major causative factor of cigarette smoke-induced oxidative protein damage that leads to apoptosis and lung injury. The pathophysiological events are prevented by a moderately large dose of vitamin C.Emphysematous lung damage is a prominent component of Chronic Obstructive Pulmonary Disease (COPD), which is a major and growing cause of morbidity and mortality worldwide. Cigarette smoking is by far the mos
Interaction of Chandipura Virus N and P Proteins: Identification of Two Mutually Exclusive Domains of N Involved in Interaction with P
Arindam Mondal, Arunava Roy, Sandipto Sarkar, Jishnu Mukherjee, Tridib Ganguly, Dhrubajyoti Chattopadhyay
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034623
Abstract: The nucleocapsid protein (N) and the phosphoprotein (P) of nonsegmented negative-strand (NNS) RNA viruses interact with each other to accomplish two crucial events necessary for the viral replication cycle. First, the P protein binds to the aggregation prone nascent N molecules maintaining them in a soluble monomeric (N0) form (N0-P complex). It is this form that is competent for specific encapsidation of the viral genome. Second, the P protein binds to oligomeric N in the nucleoprotein complex (N-RNA-P complex), and thereby facilitates the recruitment of the viral polymerase (L) onto its template. All previous attempts to study these complexes relied on co-expression of the two proteins in diverse systems. In this study, we have characterised these different modes of N-P interaction in detail and for the first time have been able to reconstitute these complexes individually in vitro in the chandipura virus (CHPV), a human pathogenic NNS RNA virus. Using a battery of truncated mutants of the N protein, we have been able to identify two mutually exclusive domains of N involved in differential interaction with the P protein. An unique N-terminal binding site, comprising of amino acids (aa) 1–180 form the N0-P interacting region, whereas, C-terminal residues spanning aa 320–390 is instrumental in N-RNA-P interactions. Significantly, the ex-vivo data also supports these observations. Based on these results, we suggest that the P protein acts as N-specific chaperone and thereby partially masking the N-N self-association region, which leads to the specific recognition of viral genome RNA by N0.
Culture independent molecular analysis of bacterial communities in the mangrove sediment of Sundarban, India
Abhrajyoti Ghosh, Nirmalya Dey, Amit Bera, Amit Tiwari, KB Sathyaniranjan, Kalyan Chakrabarti, Dhrubajyoti Chattopadhyay
Aquatic Biosystems , 2010, DOI: 10.1186/1746-1448-6-1
Abstract: Two 16 S rRNA gene libraries were constructed and partial sequencing of the selected clones was carried out to identify bacterial strains present in the sediment. Phylogenetic analysis of partially sequenced 16 S rRNA gene sequences revealed the diversity of bacterial strains in the Sundarban sediment. At least 8 different bacterial phyla were detected. The major divisions of detected bacterial phyla were Proteobacteria (alpha, beta, gamma, and delta), Flexibacteria (CFB group), Actinobacteria, Acidobacteria, Chloroflexi, Firmicutes, Planctomycetes and Gammatimonadates.The gammaproteobacteria were found to be the most abundant bacterial group in Sundarban sediment. Many clones showed similarity with previously reported bacterial lineages recovered from various marine sediments. The present study indicates a probable hydrocarbon and oil contamination in this sediment. In the present study, a number of clones were identified that have shown similarity with bacterial clones or isolates responsible for the maintenance of the S-cycle in the saline environment.The majority (60-70%) of the world tropical and subtropical coastlines are covered with mangrove ecosystems. Mangroves are known to be highly productive ecosystems and have immense ecological values. They protect and stabilize the costal zones, nourish and nurture the coastal water with nutrients. They play important role as the feeding and breeding areas of many organisms including plants, animals and micro-organisms. The microbial community in the mangrove sediment is strongly influenced by bio-geographical, anthropological and ecological properties. These properties include food web in the ecosystem, nutrient cycling and the presence of organic and inorganic matters.During the past decade, the development of molecular techniques using nucleic acids has led to many new findings in the studies of microbial ecology [1]. As a basic approach to clarify the microbial communities, 16S rRNA genes are amplified by PCR fro
Black tea prevents cigarette smoke-induced apoptosis and lung damage
Shuvojit Banerjee, Palas Maity, Subhendu Mukherjee, Alok K Sil, Koustubh Panda, Dhrubajyoti Chattopadhyay, Indu B Chatterjee
Journal of Inflammation , 2007, DOI: 10.1186/1476-9255-4-3
Abstract: Guinea pigs were subjected to cigarette smoke exposure from five cigarettes (two puffs/cigarette) per guinea pig/day for seven days and given water or black tea to drink. Sham control guinea pigs were exposed to air instead of cigarette smoke. Lung damage, as evidenced by inflammation and increased air space, was assessed by histology and morphometric analysis. Protein oxidation was measured through oxyblot analysis of dinitrophenylhydrazone derivatives of the protein carbonyls of the oxidized proteins. Apoptosis was evidenced by the fragmentation of DNA using TUNEL assay, activation of caspase 3, phosphorylation of p53 as well as over-expression of Bax by immunoblot analyses.Cigarette smoke exposure to a guinea pig model caused lung damage. It appeared that oxidative stress was the initial event, which was followed by inflammation, apoptosis and lung injury. All these pathophysiological events were prevented when the cigarette smoke-exposed guinea pigs were given black tea infusion as the drink instead of water.Cigarette smoke exposure to a guinea pig model causes oxidative damage, inflammation, apoptosis and lung injury that are prevented by supplementation of black tea.Cigarette smoking is a major cause for the increased incidence of Chronic Obstructive Pulmonary Diseases (COPD), worldwide. The pathogenesis of this disease is usually characterized by abnormal enlargement of airspaces of the lung accompanied by destruction of its walls [1]. This is a major and increasing global health problem, which is currently the 4th leading cause of death, and is projected to become the 3rd commonest cause of death and the 5th commonest cause of disability in the world by the year 2020 [2]. However, the cellular and molecular mechanism of COPD is not clear and there are no effective drug therapies for such lung damage that are able to significantly reduce disease progression.Over the last few decades, inflammation and protease/antiprotease imbalance have been proposed to act a
ETHNO-BASED STUDENT'S ORGANISATION AND MOVEMENT FOR ETHNIC AUTONOMY IN NORTH-EAST INDIA: UNDERSTANDING THE ROLE OF ALL RABHA STUDENT'S UNION (ARSU) IN THE MOVEMENT FOR RABHA ETHNIC AUTONOMY IN ASSAM
DHRUBAJYOTI DAS
Indian Streams Research Journal , 2012,
Abstract: North-East India continues to be a hot bed of ethno-based educated youth led or student led movement for quite some time now. The educated youths as well as the student's of different ethnic groups of this region have been launching massive movements on the issues of ethno-cultural identity, socio-economic backwardness, etc. and at times it also extends to secessionist overtones or separatist demands. It has been observed that society, polity, economy of all the states in North-East India are today greatly affected and influenced by these educated youth led students movements. Ethnobased youth organization and movement has emerged as a strong force through which the emerging educated elites of the different ethnic groups in North-East India seek to fulfil their aspirations, rights, demands, to safeguard their language, literature, and socio-cultural heritage as well as to safeguard and maintain their distinct ethnic identity, as well as to create a separate political arrangement or political space for all round development of their respective ethnic communities within the existing polity. It has been observed that ethno-based youth organizations have become the fore-runner as well as played active and leading role in the ethnic autonomy demand movement of these respective ethnic communities in North-East India.
Analytical Solution for Bending Stress Intensity Factor from Reissner’S Plate Theory  [PDF]
Lalitha Chattopadhyay
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.35060
Abstract: Plate-type structural members are commonly used in engineering applications like aircraft, ships nuclear reactors etc. These structural members often have cracks arising from manufacture or from material defects or stress concentrations. Designing a structure against fracture in service involves consideration of strength of the structure as a function of crack size, dimension and the applied load based on principles of fracture mechanics. In most of the engineering structures the plate thickness is generally small and in these cases though the classical plate theory has provided solutions, the neglect of transverse shear deformation leads to the limitation that only two conditions can be satisfied on any boundary whereas we have three physical boundary conditions on an edge of a plate. In this paper this incompatibility is eliminated by using Reissner plate theory where the transverse shear deformation is included and three physically natural boundary conditions of vanishing bending moment, twisting moment and transverse shear stress are satisfied at a free boundary. The problem of estimating the bending stress distribution in the neighbourhood of a crack located on a single line in an elastic plate of varying thickness subjected to out-of-plane moment applied along the edges of the plate is examined. Using Reissner’s plate theory and integral transform technique, the general formulae for the bending moment and twisting moment in an elastic plate containing cracks located on a single line are derived. The thickness depended solution is obtained in a closed form for the case in which there is a single crack in an infinite plate and the results are compared with those obtained from the literature.
An Intrusion Detection System for Kaminsky DNS Cache poisoning
Dhrubajyoti Pathak, Kaushik Baruah
International Journal of Engineering Research , 2014,
Abstract: : Domain Name System (DNS) is the largest and most actively distributed, hierarchical and scalable database system which plays an incredibly inevitable role behind the functioning of the Internet as we know it today. A DNS translates human readable and meaningful domain names such as www.iitg.ernet.in into an Internet Protocol (IP) address such as 202.141.80.6. It is used for locating a resource on the World Wide Web. Without a DNS, the Internet services as we know it, would come to a halt. In our thesis, we proposed an Intrusion Detection System(IDS) for Kaminsky cache poisoning attacks. Our system relies on the existing properties of the DNS protocol.
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