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A laser beam propagating in air and passing through a point diffraction interferometer (PDI) produces stable interferograms that can be used to extract wavefront data such as major atmospheric characteristics: turbulence strength, inner scale and outer scale of the refractive index. These parameters need to be taken into consideration when developing defense laser weapons since they can be affected by thermal fluctuations that are due to the changes in temperature in close proximity to the propagating beam and results in phase shifts that can be used to calculate the temperature which causes wavefront perturbations on a propagating beam. 相似文献
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S. Ramanathan M. B. Kakade P. V. Ravindran B. B. Kalekar K. V. Chetty A. K. Tyagi 《Journal of Thermal Analysis and Calorimetry》2006,84(2):511-519
Precursor powders for
yttrium aluminum garnet (YAG) were synthesized by solution combustion reactions
(nitrate–glycine reaction with stoichiometric and sub-stoichiometric
amount of fuel) and simple decomposition of nitrate solution. The TG-DTA,
FTIR and XRD analyses of the precursors and the typical heat-treated samples
were carried out to understand the processes occurring at various stages during
heating to obtain phase pure YAG. Precursors from all the reactions exhibited
dehydration of adsorbed moisture in the temperature range of 30 to 300°C.
The precursor from nitrate–glycine reaction with stoichiometric amount
of fuel (precursor- A) contained entrapped oxides of carbon (CO and CO2)
and a carbonaceous contaminant. It exhibited burning away of the carbonaceous
contaminant and crystallization to pure YAG accompanied by loss of oxides
of carbon in the temperature ranges of 400 to 600 and 880 to 1050°C. The
precursor from simple decomposition of nitrates (precursor-B) exhibited denitration
cum dehydroxylation and crystallization in the temperature ranges of 300 to
600 and 850 to 1050°C. The precursor from nitrate–glycine reaction
with sub-stoichiometric amount of fuel (precursor-C) contained entrapped carbon
dioxide and exhibited its release during crystallization in the temperature
range of 850 to 1050°C. This study established that, in case of metal
nitrate–glycine combustion reactions, crystalline YAG formation occurs
from an amorphous compound with entrapped oxides of carbon. In case of simple
decomposition of metal nitrates, formation of crystalline YAG occurs from
an amorphous oxide intermediate. 相似文献
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K. V. Chetty P. M. Mapara Rajendra Swarup S. K. Patil 《Journal of Radioanalytical and Nuclear Chemistry》1988,121(1):149-159
The extraction of U(VI) by mixtures of HTTA and TBP from aqueous thiocyanate medium has been studied. From the data obtained it was observed that the predominant uranium species extracted, causing synergic enhancement in the extraction of U(VI), is UO2(SCN)TTA · 2TBP when benzene and cyclohexane are used as diluents, and that at a very low concentration of TBP the contribution of additional species, viz. UO2(TTA)2 · TBP becomes significant. With chloroform as diluent, however, both of these species are contributing to the synergic enhancement. The extraction of a quaternary uranium species, UO2(SCN)TTA · 2TBP, involving the participation of the aqueous anion is thus established. Equilibrium constants for the various extraction equilibria involved are calculated. 相似文献
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William M.R. Matshe Lesego L. Tshweu Sindisiwe Mvango Zamani E.D. Cele Avashnee S. Chetty Lynne A. Pilcher Ibukun M. Famuyide Lyndy J. McGaw Dale Taylor Liezl Gibhard Gregory S. Basarab Mohammed O. Balogun 《Macromolecular bioscience》2023,23(5):2200518
Uncomplicated malaria is effectively treated with oral artemisinin-based combination therapy (ACT). Yet, there is an unmet clinical need for the intravenous treatment of the more fatal severe malaria. There is no combination intravenous therapy for uncomplicated due to the nonavailability of a water-soluble partner drug for the artemisinin, artesunate. The currently available treatment is a two-part regimen split into an intravenous artesunate followed by the conventional oral ACT . In a novel application of polymer therapeutics, the aqueous insoluble antimalarial lumefantrine is conjugated to a carrier polymer to create a new water-soluble chemical entity suitable for intravenous administration in a clinically relevant formulation . The conjugate is characterized by spectroscopic and analytical techniques, and the aqueous solubility of lumefantrine is determined to have increased by three orders of magnitude. Pharmacokinetic studies in mice indicate that there is a significant plasma release of lumefantrine and production its metabolite desbutyl-lumefantrine (area under the curve of metabolite is ≈10% that of the parent). In a Plasmodium falciparum malaria mouse model, parasitemia clearance is 50% higher than that of reference unconjugated lumefantrine. The polymer-lumefantrine shows potential for entering the clinic to meet the need for a one-course combination treatment for severe malaria. 相似文献
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T. Gangaiah K. V. S. Murthy G. R. K. Naidu K. Venugopal Chetty 《Journal of Radioanalytical and Nuclear Chemistry》1992,162(2):253-258
Isotope exchange behavior of bis(resacetophenone oxime)copper(II) complex with copper(II) in tri-n-butyl-phosphate and methanol medium has been studied. The studies were carried out at different temperatures varying the concentration of both metal ion and complex. The results show that the complex is labile in the kinetic sense. Increase in temperature increases the isotope exchange rate. The increase in concentration also results in enhancement of the rate of reaction. 相似文献
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Measurements of the temperature dependence of the Buckingham effect (electric-field-gradient-induced birefringence, EFGIB) for gaseous nitrous oxide are presented. Measurements span the temperature range 298.5-473.9 K, which allows for separation of the temperature-independent hyperpolarizability term from the temperature-dependent quadrupole term, yielding a quadrupole moment of Θ = (-11.03 ± 0.41) × 10(-40) C m(2), and a hyperpolarizability term of b = (-0.638 ± 0.063) × 10(-60) C(3) m(4) J(-2). For dipolar molecules, the quadrupole moment is origin dependent, and the value reported here is referred to an origin called the effective quadrupole center (EQC). Comparison of this value with the center of mass (CM) quadrupole moment obtained from MBER experiments yields information about the dynamic dipole-quadrupole and dipole-magnetic dipole polarizabilities. The temperature-independent term, previously assumed to contribute negligibly to the EFGIB, is found to contribute some (5.2 ± 0.6)% to the effect at room temperature and clearly needs to be accounted for if the quadrupole moment is to be definitively established. 相似文献
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Mayne L Kan ZY Chetty PS Ricciuti A Walters BT Englander SW 《Journal of the American Society for Mass Spectrometry》2011,22(11):1898-1905
Measurement of the naturally occurring hydrogen exchange (HX) behavior of proteins can in principle provide highly resolved
thermodynamic and kinetic information on protein structure, dynamics, and interactions. The HX fragment separation-mass spectrometry
method (HX-MS) is able to measure hydrogen exchange in biologically important protein systems that are not accessible to NMR
methods. In order to achieve high structural resolution in HX-MS experiments, it will be necessary to obtain many sequentially
overlapping peptide fragments and be able to identify and analyze them efficiently and accurately by mass spectrometry. This
paper describes operations which, when applied to four different proteins ranging in size from 140 to 908 residues, routinely
provides hundreds of useful unique peptides, covering the entire protein length many times over. Coverage in terms of the
average number of peptide fragments that span each amino acid exceeds 10. The ability to achieve these results required the
integrated application of experimental methods that are described here and a computer analysis program, called ExMS, described
in a following paper. 相似文献