314 research outputs found
OPTIMIZATION OF BIOMASS CULTURE YIELD AND L-DOPA COMPOUND IN THE CALLUS CULTURE FROM COTYLEDONARY LEAVES OF MUCUNA PRURIENS
ABSTRACTObjective:  The objective of the present study was to evaluate the optimization of callus biomass culture yield and high-performance liquid chromatography (HPLC) analysis of L-DOPA compound in the callus culture from cotyledonary leaves of Mucuna pruriensMethods : M. pruriens seed explants were inoculated onto Murashige and Skoog medium supplemented with different concentrations of 2-isopentenyl adenine (2iP) and Gibberellic acid (GA3) for germination of plants. The in vitro cotyledonary leaf and hypocotyl explants were cultured on MS basal media containing various concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D), 1- Naphthaleneacetic acid (NAA), 6-Benzylaminopurine (BA) and 2iP for callus induction. A standard approach of Latin square method was followed for screening of media to establish optimum culturing of callus by manipulating the concentration of auxins (2, 4-D, Indole-3-acetic acid (IAA) and NAA) and cytokinins (BA and 2iP) alone and in combinations. The harvested callus biomass was screened for a major metabolite namely L- Dopa compound using HPLC.Results: Cotyledonary leaf explants showed better callus initiation than hypocotyl explants. Maximum callus induction was observed in Murashige and Skoog (MS) medium containing 4.92µM 2iP. Further screening of callus culture was carried out on MS medium supplemented with different concentrations and combinations of 2, 4-D, NAA,  IAA, (BA)  and 2iP individually and in combinations. Optimum callus biomass of 21.63 g/L dry weight (246.31 g/L fresh weight) was developed on MS media containing 2.26µM 2, 4-D, 2.22µM BA and 4.92µM 2iP. The harvested callus biomass was subjected to extraction and purification of L- Dopa compound.Conclusion: The present study concludes that  HPLC analysis of cell biomass extracts in comparison  with extracts from seeds of mother plants of Mucuna prurienss showed main component of L- Dopa was present in sufficiently large amounts in the undifferentiated cultured cells.Keywords: Mucuna pruriens, Callus biomass, L-Dopa, HPLC analysi
Effects of interaction on an adiabatic quantum electron pump
We study the effects of inter-electron interactions on the charge pumped
through an adiabatic quantum electron pump. The pumping is through a system of
barriers, whose heights are deformed adiabatically. (Weak) interaction effects
are introduced through a renormalisation group flow of the scattering matrices
and the pumped charge is shown to {\it always} approach a quantised value at
low temperatures or long length scales. The maximum value of the pumped charge
is set by the number of barriers and is given by . The
correlation between the transmission and the charge pumped is studied by seeing
how much of the transmission is enclosed by the pumping contour. The (integer)
value of the pumped charge at low temperatures is determined by the number of
transmission maxima enclosed by the pumping contour. The dissipation at finite
temperatures leading to the non-quantised values of the pumped charge scales as
a power law with the temperature (), or with
the system size (), where is a
measure of the interactions and vanishes at . For a double
barrier system, our result agrees with the quantisation of pumped charge seen
in Luttinger liquids.Comment: 9 pages, 9 figures, better quality figures available on request from
author
Neural Network Based Recognizing Surgically Altered Face Images for Real Time Security Application
Transport in quantum wires
With a brief introduction to one-dimensional channels and conductance
quantisation in mesoscopic systems, we discuss some recent experimental puzzles
in these systems, which include reduction of quantised conductances and an
interesting {\it odd-even} effect in the presence of an in-plane magnetic
field. We then discuss a recent non-homogeneous Luttinger liquid model proposed
by us, which addresses and gives an explanation for the reduced conductances
and the {\it odd-even} effect. We end with a brief summary and discussion of
future projects.Comment: Talk presented at the International Discussion Meeting on Mesoscopic
and Disordered systems, December, 2000, 16 pages, 2 figure
Field Theories of Frustrated Heisenberg Antiferromagnets
We study the Heisenberg antiferromagnetic chain with both dimerization and
frustration. The classical ground state has three phases: a Neel phase, a
spiral phase and a colinear phase. In each phase, we discuss a non-linear sigma
model field theory governing the low energy excitations. We study the theory in
the spiral phase in detail using the renormalization group. The field theory,
based on an matrix-valued field, becomes and
Lorentz invariant at long distances where the elementary excitation is
analytically known to be a massive spin- doublet. The field theory
supports solitons which lead to a double degeneracy in the spectrum for
half-integer spins (when there is no dimerization).Comment: Latex, 12 pages, 2 figures (gzipped and uuencoded
Transport through quasi-ballistic quantum wires: the role of contacts
We model one-dimensional transport through each open channel of a quantum
wire by a Luttinger liquid with three different interaction parameters for the
leads, the contact regions and the wire, and with two barriers at the contacts.
We show that this model explains several features of recent experiments, such
as the flat conductance plateaux observed even at finite temperatures and for
different lengths, and universal conductance corrections in different channels.
We discuss the possibility of seeing resonance-like structures of a fully open
channel at very low temperatures.Comment: revtex, 5 pages, 1 eps figure; clarifications added in light of new
experiment
Junction of several weakly interacting quantum wires: a renormalization group study
We study the conductance of three or more semi-infinite wires which meet at a
junction. The electrons in the wires are taken to interact weakly with each
other through a short-range density-density interaction, and they encounter a
general scattering matrix at the junction. We derive the renormalization group
equations satisfied by the S-matrix, and we identify its fixed points and their
stabilities. The conductance between any pair of wires is then studied as a
function of physical parameters such as temperature. We discuss the possibility
of observing the effects of junctions in present day experiments, such as the
four-terminal conductance of a quantum wire and crossed quantum wires.Comment: RevTeX, 13 pages, including 4 eps figure
Bosonic Mean Field Theory of the Spiral Phases of Heisenberg Antiferromagnets on a Chain
We develop a novel bosonic mean field theory to describe the spiral phases of
a Heisenberg antiferromagnet on a one-dimensional chain, in terms of three
bosons at each site. The ground state is disordered and for large values of the
spin , two different and exponentially small energy gaps are found. The
spin-spin correlation function is computed and is shown to decay exponentially
at large distances. Our mean field theory is also shown to be exact in a
large- generalization.Comment: plain.tex, TIFR/TH/92-66, IISc/CTS/92-1
Transcription profiling reveals potential mechanisms of dysbiosis in the oral microbiome of rhesus macaques with chronic untreated SIV infection.
A majority of individuals infected with human immunodeficiency virus (HIV) have inadequate access to antiretroviral therapy and ultimately develop debilitating oral infections that often correlate with disease progression. Due to the impracticalities of conducting host-microbe systems-based studies in HIV infected patients, we have evaluated the potential of simian immunodeficiency virus (SIV) infected rhesus macaques to serve as a non-human primate model for oral manifestations of HIV disease. We present the first description of the rhesus macaque oral microbiota and show that a mixture of human commensal bacteria and "macaque versions" of human commensals colonize the tongue dorsum and dental plaque. Our findings indicate that SIV infection results in chronic activation of antiviral and inflammatory responses in the tongue mucosa that may collectively lead to repression of epithelial development and impact the microbiome. In addition, we show that dysbiosis of the lingual microbiome in SIV infection is characterized by outgrowth of Gemella morbillorum that may result from impaired macrophage function. Finally, we provide evidence that the increased capacity of opportunistic pathogens (e.g. E. coli) to colonize the microbiome is associated with reduced production of antimicrobial peptides
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