21 research outputs found
A biobibliometric study on Prof. B. N. Koley, an eminent physiologist
No full text74-82This biobibliometric study is based on 251 papers of Prof. B. N. Koley published during 1958-2001. On the basis of collecteddata, this study examines year-wise distribution of papers, research group of the scientist and scattering of papers in differentcommunication channels. In addition, it finds out author productivity, spectrum of research activity through analysis of the titlekeywords, and productivity of Koley's research group. Finally, it shows that the data set does not follow Bradford distribution
Mitochondrial Import Of tRNA: Mechanistic Studies Of Post- Receptor Translocation
No full textMitochondrial Import Of tRNA: Mechanistic Studies Of Post Receptor Translocation
Import of tRNA from the cytosol into the mitochondria of the kinetoplastid protozoon
Leishmania is a multistep process consisting of the binding of tRNA to specific receptors, its
transfer to an intermediate factor and translocation through the membrane. A functional RNA
import complex (RIC) isolated from Leishmania mitochondria or reconstituted by cloned and
expressed protein subunits are being employed in our laboratory to determine molecular basis of
these steps. The RIC from mitochondria of the kinetoplastid protozoon Leishmania tropica
induces translocation of tRNAs across artificial or natural membranes. tRNA import consists of a
number of discrete steps beginning with the binding of the substrate to a receptor subunit RIC1 or
RIC8A, followed by its transfer to a third subunit RIC9. Subsequently the tRNA passes into the
vesicle interior presumably through a membrane embedded translocation channel, the
composition and properties of which are largely unknown. Although the receptor binding and
transfer steps have been characterized in terms of role of specific subunits, little is known about
the final translocation step.
Specifically the objective of my research was to reconstitute functional import pore
complex on lipid bilayers and determine the permeability of such membrane vesicles by RIC
channel under different biochemical and biophysical conditions with tRNA and other different
small molecules, to carry out structural and functional studies of translocation by site directed
mutagenesis of important subunit gene. These experiments provided detailed insights into the
interaction of RIC with mitochondrial and other membranes.
I have shown that subunits RIC6 and RiC9 polymerize on the membrane to form the
hexamer (RIC6)3-(RIC9)3 in presence of RIC4A formed a R3 complex. The resultant complex R3
induced translocation of tRNA when the pH of the medium was lowered to ~6. This process was
independent of ATP and sensitive to the protonophore m-chlorocarbonylcyanide phenylhydrazone
(CCCP), and to the K+ ionophore valinomycin, but resistant to k+/h+ exchanger nigericin,
indicating the requirement of a membrane potrential Δψm generated by transmembrane proton
gradient. Indeed R3 mediated tRNA translocation could be induced at neutral pH by K+ diffusion
potential of 60-90mV (negative inside). However, translocation was independent of tRNA
sequence, and small molecules such as ATP, oligonucleotides, labeled amino acids could be taken
up by R3 liposomes at pH6.0 in contrast to large molecules such as linearized plasmid DNA
which fails the internalization process and shows the size specificity of R3 complex. My results
indicated that the (RIC6)3-(RIC9)3 complex forms a voltage gated pore similar to mitochondrial
protein import channels. To understand the critical residues involves in proton sensing points
mutants of RIC6 subunits were generated in all the 6 cysteines and 6 histidine residues as some of
those residues are involved in proton sensing in a homologous protein rieske fe-s protein of RIC6.
I have found out the critical cysteine and histidines along the protein chain are responsible for
proton sensing. Atomic force microscopy has been used to find out the nature of the reconstituted
channel in vitro. Atomic Force Microscopy of R3 revealed particles with an asymmetric surface
groove of ~20 nm rim diameter and ~1 nm depth
Non-uniqueness of Hölder continuous solutions for Inhomogeneous Incompressible Euler flows
No full textWe consider the inhomogeneous (or density dependent) incompressible Euler equations in a three-dimensional periodic domain. We construct density and velocity such that, for any , both of them are -Hölder continuous and is a weak solution to the underlying equations. The proof is based on typical convex integration techniques using Mikado flows as building blocks. As a main novelty with respect to the related literature, our result produces a Hölder continuous density.41 pages. arXiv admin note: text overlap with arXiv:2006.06482, arXiv:2101.09278 by other author
Non-uniqueness of Hölder continuous solutions for stochastic Euler and Hypodissipative Navier-Stokes equations
No full textHere we construct infinitely many Hölder continuous global-in-time and stationary solutions to the stochastic Euler and hypodissipative Navier-Stokes equations in the space for , with and respectively. A modified stochastic convex integration scheme, using Beltrami flows as building blocks and propagating inductive estimates both pathwise and in expectation, plays a pivotal role to improve the regularity of Hölder continuous solutions for the underlying equations. As a main novelty with respect to the related literature, our result produces solutions with noteworthy Hölder exponents.38 pages. arXiv admin note: substantial text overlap with arXiv:2401.09894 by other author
INDIAN JOURNAL OF PHYSIOLOGY AND ALLIED SCIENCES: AN ANALYSIS OF CITATION PATTERN
No full text23-26The present study covers 457 citations appended to 26 research articles published in the four issues of the quarterly Indian Journal of Physiology and Allied Sciences,vol. 55(200 1). The articles are contributed by 75 authors (74 - Indian). From the citation count it appears that the solo research in physiology is quite substantial (about 24%). Though about 77% of the work is the result of team research, the team size is found to be small ranging from 2 to 5. Of the citations, 76.81 per cent relate to journal articles, 18.59 to monographs, and the rest to conference papers, theses, etc. The ratio of Indian to foreign citations is found to be almost 1:6. Of the total citations, 4.59 percent are author self citations, and 2.84 percent are journal self citations. Of the citing articles one is single- authored,10 are two-authored, 9 three-authored, 4 four-authored, and one each five- authored and six-authored. No collaboration was noticed in the case of 23 citing articles.The remaining 3 articles were the results of two-institution collaboration
Nobel Laureate Anthony J Leggett: A scientometric portrait
No full textThis paper attempts to analyse the publication productivity of Anthony J. Leggett, the 2003 Nobel Prize winner in physics. His contributions peaked in 1987, 1994, and 1998 with 10 papers each. He had 194 publications during 1964 - 2004 in domains like Superfluid 3He (65), Foundations of Quantum Mechanics (36), Dissipative Quantum Systems (24), Atomic Alkali Gases (18), and Miscellaneous (51)which were analysed for authorship pattern with his 70 collaborators. Most active collaborators with Anthony J Leggett were: A. Garg with six papers and A. O. MCaldeira, D. M. Ginsberg, D. J. Vanharlingen , F. Sols, S.Takagi and D. A. Wollman with five papers each. His productivity coefficient was 0.60 which clearly indicates that his productivity
increased after 50 percentile age. The highest degree of collaboration (1) for Anthony J. Leggett was found during 1964, 1971 and 1983. Journals have been the most preferred channel of communication, where as many as 139 papers out of 194 have been published. The core journals publishing his papers were: Phys. Rev. Leu. (42), Phys. Rev. B (9), J. Low Temp. Phys. (8),Phys. Rev. A (7), Ann. Phys. (6), Foundations of physics (6), J. Phys.(5), Prog. Theor: Phys. (5), and Rev. Mod. Phys. (5).Publication density was 3.02 and publication concentration was 3.59
Phylogenetic background of E. coli isolated from asymptomatic pregnant women from Kolkata, India
No full textIntroduction: Asymptomatic bacteriuria (ABU) in pregnancy generates medical complications. E. coli is the common etiologic agent responsible for ABU-associated infections. This study aimed to identify the phylogenetic background and drug resistance in asymptomatic E. coli from a pregnant population.
Methodology: E. coli was confirmed biochemically from culture-positive urine samples collected from asymptomatic pregnant women. Phylogenetic typing was done by polymerase chain reaction (PCR). The isolates were subjected to antibiotic susceptibility testing and extended-spectrum beta-lactamase (ESBL) production. Statistical significance was determined using SPSS 17.0 software.
Results: Bacteriuria was observed in 113 (22.6%) of 500 asymptomatic pregnant females. E. coli was reported in 44 (38.9%) of 113 isolates. The mean age-wise distribution was 25.14 ± 4.63. Although pathogenic phylogroup B2 was predominant (54.5%), incidence of non-pathogenic phylogroup B1 (27.3%) was found to be statistically significant (p ≤ 0.001), and B1 and B2 were correlated with respect to total ABU population. Antibiotic sensitivity against ampicillin (34.1%), ceftazidime (50%), cefotaxime (47.7%), ciprofloxacin (47.7%), amikacin (86.4%), nitrofurantion (79.5%), and co-trimoxazole (36.4%) was observed. Multidrug resistance (MDR) and ESBL production was reported in 26 (59.1%) of 44 and 18 (69.2%) of the 26 MDR isolates, respectively. A significant distribution of phylogroup B1 (p = 0.03) with drug resistance was also observed.
Conclusions: This is the first study that reported significant incidence of non-pathogenic phylogroup B1 in asymptomatic E. coli with high incidence of MDR isolated from pregnant women in Kolkata, India. These varied resistance patterns present major therapeutic and infection control challenges during pregnancy
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Unlocking Water's Potential for Energy Storage: Abundant Materials for a Ubiquitous Problem
No full textWater is an absolute necessity for life as we know it. It provides a useful medium in which chemical reactions take place that allowed for the development of single cellular organisms. When combined with the evolutionary accident that was pho- tosynthesis, water became not only a useful medium chemical reactions, but also a ready feedstock for the storage of chemical energy.
The potential to use water as the feedstock for energy storage is not simply of interest on the cellular level. One of the earliest popular references to the use of water for energy storage was by the 19th-century science fiction writer Jules Verne
in The Mysterious Island in 1874, and ever since then idea has tantalized scientists and engineers. The benefits of a energy system based on the conversion of water into a fuel and then back to water are self-evident and as a result the topic has been the focus considerable interest over the past 144 years. In that time, however, the energy required to produce hydrogen at the scale necessary has not been available.
The technologies required to enable the actual transition from a carbon-based energy dependence to a renewable energy system are only recently coming on-line. The greatest driver in this transition is the realization that continued reliance on fossil energy has placed us at the cusp of environmental catastrophe. This, in turn, has driven the development of renewable energy generation technologies. Gains in renewable energy capacity have exposed the inherent dissonance between when renewable energy is available and when energy in general in demand, in order to bridge that gap energy storage technologies need to be developed and deployed on a truly massive scale.
The scale of the energy storage problem necessitates strategies that utilize abun- dant materials for components of an energy storage system. This allows us to fall back on some microbial wisdom and refocus on water as an energy storage feedstock. Converting water into hydrogen and oxygen and then storing the hy-
drogen for later use as a fuel can be achieved by three means: thermochemical, photoelectrochemical, and electrochemical. The most technologically feasible and widely applicable method of hydrogen generation is via electrochemical means. Of the electrochemical devices for hydrogen production, the most efficient rely on the use of platinum group metals (PGM) as catalysts, adding significant cost to their manufacture and limiting the scale at which they can be deployed. This points to the need to develop non-PGM catalysts for use in water-splitting devices.
This dissertation focuses on two main subjects. First is the synthesis and physical characterization of first-row transition metal-based materials deposited in meso- porous substrates and their electrochemical performance as catalysts in water- splitting reactions. Second is the field’s current understanding of correlation be- tween the presence of iron and catalyst efficacy with the author’s own work demonstrating the superior performance of iron based catalysts. It is the hope of the author that reader will gain knowledge of the methods of deposition in porous carbon substrates and an understanding of electrochemical characterization of catalyst performance as it applies to water-splitting reactions
