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Hāora, India

Das S.,Uluberia College | Roymondal U.,Raidighi College | Chottopadhyay B.,Jadavpur University | Sahoo S.,Raidighi College

The expression of functional proteins plays a crucial role in modern biotechnology. The free-living cynobacterium Synechocystis PCC 6803 is an interesting model organism to study oxygenic photosynthesis as well as other metabolic processes. Here we analyze a gene expression profiling methodology, RCBS (the scores of relative codon usage bias) to elucidate expression patterns of genes in the Synechocystis genome. To assess the predictive performance of the methodology, we propose a simple algorithm to calculate the threshold score to identify the highly expressed genes in a genome. Analysis of differential expression of the genes of this genome reveals that most of the genes in photosynthesis and respiration belong to the highly expressed category. The other genes with the higher predicted expression level include ribosomal proteins, translation processing factors and many hypothetical proteins. Only 9.5% genes are identified as highly expressed genes and we observe that highly expressed genes in Synechocystis genome often have strong compositional bias in terms of codon usage. An important application concerns the automatic detection of a set of impact codons and genes that are highly expressed tend to use this narrow set of preferred codons and display high codon bias .We further observe a strong correlation between RCBS and protein length indicating natural selection in favor of shorter genes to be expressed at higher level. The better correlations of RCBS with 2D electrophoresis and microarray data for heat shock proteins compared to the expression measure based on codon usage difference, E(g) and codon adaptive index, CAI indicate that the genomic expression profile available in our method can be applied in a meaningful way to study the mRNA expression patterns, which are by themselves necessary for the quantitative description of the biological states. © 2012 Elsevier B.V. Source

Ghosh B.,Jadavpur University | Paul S.N.,Jadavpur University | Das C.,Uluberia College | Paul I.,Jadavpur University | Banerjee S.,Vidyasagar College Day
Brazilian Journal of Physics

The pseudopotential technique is applied to a multicomponent plasma consisting of nonthermal electrons and warm positive and negative ions with drift motion with a view to studying ion-acoustic double layers. Conditions for the existence of such layers are obtained, two critical concentrations of negative ions being identified which control the formation and nature of the ion-acoustic double layers. The effects of nonthermal electrons, negative-ion concentration, and negative-ion temperature on the double layer formation and structure are also investigated. The nonthermal electrons and the negative ions are shown to contribute significantly to the excitation and structure of the double layers. The importance of the results in the context of magnetospheric and auroral plasmas is discussed. © 2013 Sociedade Brasileira de Física. Source

Sarkar S.K.,Jadavpur University | Sarkar S.K.,Uluberia College | Jana M.S.,Jadavpur University | Mondal T.K.,Jadavpur University | Sinha C.,Jadavpur University
Applied Organometallic Chemistry

Alcohols are oxidized by N-methylmorpholine-N-oxide (NMO), Bu tOOH and H2O2 to the corresponding aldehydes or ketones in the presence of catalyst, [RuH(CO)(PPh3) 2(SRaaiNR)]PF6 (2) and [RuCl(CO)(PPh3)(S κRaaiNR)]PF6 (3) (SRaaiNR (1) = 1-alkyl-2-{(o- thioalkyl)phenylazo}imidazole, a bidentate N(imidazolyl) (N), N(azo) (N) chelator and SκRaaiNR is a tridentate N(imidazolyl) (N), N(azo) (N), Sκ-R is tridentate chelator; R and R are Me and Et). The single-crystal X-ray structures of [RuH(CO)(PPh3) 2(SMeaaiNMe)]PF6 (2a) (SMeaaiNMe = 1-methyl-2-{(o- thioethyl)phenylazo}imidazole) and [RuH(CO)(PPh3) 2(SEtaaiNEt)]PF6 (2b) (SEtaaiNEt = 1-ethyl-2-{(o- thioethyl)phenylazo}imidazole) show bidentate N,N chelation, while in [RuCl(CO)(PPh3)(SκEtaaiNEt)]PF6 (3b) the ligand SκEtaaiNEt serves as tridentate N,N,S chelator. The cyclic voltammogram shows RuIII/RuII (~1.1 V) and Ru IV/RuIII (~1.7 V) couples of the complexes 2 while Ru III/RuII (1.26 V) couple is observed only in 3 along with azo reductions in the potential window +2.0 to -2.0 V. DFT computation has been used to explain the spectra and redox properties of the complexes. In the oxidation reaction NMO acts as best oxidant and [RuCl(CO)(PPh 3)(SκRaaiNR)](PF6) (3) is the best catalyst. The formation of high-valent RuIV=O species as a catalytic intermediate is proposed for the oxidation process. Copyright © 2014 John Wiley & Sons, Ltd. Source

Ghosh B.,Jadavpur University | Paul S.N.,Swami Vivekananda Institute of Science and Technology | Das C.,Uluberia College | Sinhamahapatra A.,B N Mahavidyalaya | Paul I.,Jadavpur University
Indian Journal of Physics

To describe the nonlinear interactions of a magneto-hydrodynamic wave with its second harmonic propagating in a planar waveguide filled with cold magnetized plasma, coupled mode equations have been derived. Solution of these equations shows the possibility of energy transfer between the fundamental and the second harmonic. © 2011 IACS. Source

Ghosh B.,Jadavpur University | Paul S.N.,Jadavpur University | Das C.,Uluberia College | Paul I.,Jadavpur University
Canadian Journal of Physics

Modulational instability of high frequency surface waves on a plasma half-space is investigated taking into account finite temperature effects. The second harmonic generated through nonlinear self-interaction of the waves is found to carry a fraction of the surface wave energy into the bulk of the plasma. This is found to influence the modulational instability mechanism. To describe the nonlinear evolution of the wave, a nonlinear Schrodinger equation is derived in which the coefficient of the nonlinear term becomes a complex quantity. From this evolution equation we derive the condition of instability and show that high-frequency surface waves on a warm plasma half-space are modulationally unstable. © 2012 Published by NRC Research Press. Source

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