2,136 research outputs found
Mechanism of Cyanide Toxicity and Efficacy of its Antidotes
This paper attempts to review the various antidotes available for countering cyanide threat in the light of the toxicity associated with it. It also critically evaluates the drawbacks and advantages of these antidotes for their therapeutic and/or prophylactic utility. The physico-chemical properties of hydrogen cyanide which make it a chemical warfare agent have also been highlighted. In an attempt to make the complex chemical and biological processes understandable, the chemical structures of the antidotes have been included and simple mechanistic pathways have been used to show the role of antidotes in activating the inhibited enzymes
Flux jumps, Second Magnetization Peak anomaly and the Peak Effect phenomenon in single crystals of and
We present magnetization measurements in single crystals of the tetragonal
compound, which exhibit the phenomenon of peak effect as well as
the second magnetization peak anomaly for H 0.5T (H c). At the lower
field (50mT H 200mT), we have observed the presence of flux jumps,
which seem to relate to a structural change in the local symmetry of the flux
line lattice (a first order re-orientation transition across a local field in
some parts of the sample, in the range of 100mT to 150mT). These flux jumps are
also observed in a single crystal of for H c in the field
region from 2 mT to 25 mT, which are compatible with the occurrence of a
re-orientation transition at a lower field in a cleaner crystal of this
compound, as compared to those of . Vortex phase diagrams drawn for
H c in and show that the ordered elastic glass
phase spans a larger part of (H, T) space in the former as compared to latter,
thereby, reaffirming the difference in the relative purity of the two samples.Comment: 11 pages, 14 figure
Optical transitions and nature of Stokes shift in spherical CdS quantum dots
We study the structure of the energy spectra along with the character of the
states participating in optical transitions in colloidal CdS quantum dots (QDs)
using the {\sl ab initio} accuracy charge patching method combined with the
%pseudopotential based folded spectrum calculations of electronic structure of
thousand-atom nanostructures. In particular, attention is paid to the nature of
the large resonant Stokes shift observed in CdS quantum dots. We find that the
top of the valence band state is bright, in contrast with the results of
numerous {\bf kp} calculations, and determine the limits of
applicability of the {\bf kp} approach. The calculated electron-hole
exchange splitting suggests the spin-forbidden valence state may explain the
nature of the ``dark exciton'' in CdS quantum dots.Comment: 5 pages, 4 figure
Investigations into the potential effects of pedoturbation on luminescence dating
Much effort has been focussed on understanding the luminescence properties of natural minerals to achieve a reliable, accurate and precise dating technique. However, some field related aspects, such as the influence or effect of post-depositional disturbance on luminescence dates, are as yet underexplored. In the case of pedoturbation, depending on its intensity, the rate of sedimentation and unit thicknesses, potentially the whole sedimentary record at a site can be affected. This may lead to distorted OSL chronologies and erroneous sediment burial ages.
Pedoturbation can result in sediment mixing and/or exhumation that affect luminescence both at the bulk and single grain level. Effects of these two principle processes on luminescence ages are examined using standard multigrain and single grain protocols. High resolution sampling of surface gopher mounds was used to determine the efficiency of bio-exhumation in resetting luminescence signal. Results show this is an inefficient mechanism for onsite sediment bleaching. The effects on luminescence signal of bio-mixing were explored by comparing a sample collected from within a krotovina (infilled burrow) to an adjacent undisturbed sample. Results show the difficulties in identifying pedoturbated samples at the single aliquot level and the possible inaccuracies in using the lowest palaeodose values to calculate OSL ages. Where pedoturbation of samples is suspected, use of probability plots of palaeodoses data is recommended. From these plots it is proposed that only data falling within a normal distribution centred on the peak probability be used to calculated OSL ages and to mitigate problems arising from pedoturbation
Fluorinated Epoxy Resins-based Sorbent Coating Materials for Quartz Piezoelectric Crystal Detector
Fluorinated epoxy resins were synthesised and evaluated as sorbent coating materials for the detection of organophosphorus compounds using quartz piezoelectric crystal detector. These resins were prepared by reacting excess of epichlorohydrin with each of or in combination of fluorinated diols, ie, a, a, a', a' tetrakis (trifluoromethyl) 1,3 benzene dimethanol (TTFMBD), 4,4'bis-2-hydroxy hexafluoro isopropyl) biphenyl (BHHFIBP), 4,4'dihydroxyocta fluorodiphenyl (DHOFDP) and 2,2,3,3,4,4 hexafluoro 1,5 pentanediol (HFPD) in the presence of sodium hydroxide at reflux temperature. These polymers were extracted in organic solvents and dried. Each of these fluoroepoxy resins were coated over quartz piezoelectric crystal by solution-casting method and tested using dimethylmethyl phosphonate (DMMP) as model compound. Change in the frequency (AF) of quartz piezoelectric crystal oscillator was recorded. Sensitive and potential fluorinated epoxy resins, ie, diglycidylethers (DGE) of HFPD-TTFMBD (in the molar ratio 6:4) and DGE (HFPD-BHHFIBP in the molar ratio 4:6) were characterised by viscosity, number average molecular weight (Mn), epoxy equivalent, infrared spectroscopy, and thermal stability
Magnetotransport of SrIrO 3 -based heterostructures
Transition-metal oxide (TMO) based heterostructures provide fertile playground to explore or
functionalize novel quantum materials. In this regard, the combination of 3d and 5d TMOs have
gained special interest because of the simultaneous appearance of strong spin-orbit coupling
and electron correlation at the interface of those heterostructures. Artificial breaking of the
inversion symmetry in heterostructures may also result in a distinct interfacial Dzyaloshinskii-
Moriya interaction (DMI) and the formation of non-collinear magnetic spin structures in case
of magnetic TMOs. Among the 5d TMOs, SrIrO3 (SIO) has gained significant attention because
of its large spin-orbit coupling and the semi-metallic ground state, which are highly susceptible
to structural distortions. Here, we report on the preparation and the characterisation of
structural, electronic and magnetic properties of epitaxial heterostructures consisting of the 5d
TMO SIO and the 3d antiferromagnetic insulator LaFeO3
Graphene Transport at High Carrier Densities using a Polymer Electrolyte Gate
We report the study of graphene devices in Hall-bar geometry, gated with a
polymer electrolyte. High densities of 6 are
consistently reached, significantly higher than with conventional back-gating.
The mobility follows an inverse dependence on density, which can be correlated
to a dominant scattering from weak scatterers. Furthermore, our measurements
show a Bloch-Gr\"uneisen regime until 100 K (at 6.2 ),
consistent with an increase of the density. Ubiquitous in our experiments is a
small upturn in resistivity around 3 , whose origin is
discussed. We identify two potential causes for the upturn: the renormalization
of Fermi velocity and an electrochemically-enhanced scattering rate.Comment: 13 pages, 4 figures, Published Versio
Enzyme Inhibition by Molluscicidal Components of Myristica fragrans Houtt. in the Nervous Tissue of Snail Lymnaea acuminata
This study was designed to investigate the effects of molluscicidal components of Myristica fragrans Houtt. (Myristicaceae) on certain enzymes in the nervous tissue of freshwater snail Lymnaea acuminata Lamarck (Lymnaeidae). In vivo and in vitro treatments of trimyristin and myristicin (active molluscicidal components of Myristica fragrans Houtt.) significantly inhibited the acetylcholinesterase (AChE), acid and alkaline phosphatase (ACP/ALP) activities in the nervous tissue of Lymnaea acuminata. The inhibition kinetics of these enzymes indicates that both the trimyristin and myristicin caused competitive noncompetitive inhibition of AChE. Trimyristin caused uncompetitive and competitive/noncompetitive inhibitions of ACP and ALP, respectively whereas the myristicin caused competitive and uncompetitive inhibition of ACP and ALP, respectively. Thus results from the present study suggest that inhibition of AChE, ACP, and ALP by trimyristin and myristicin in the snail Lymnaea acuminata may be the cause of the molluscicidal activity of Myristica fragrans
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