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1.
Values of the incoherent scattering function SK for scattering of photons from K-shell electrons are computed for 2He, 3Li, 4Be and 5B at photon energies 6, 10, 14, and 18 keV by using screened hydrogenic wavefunctions. The screening has been taken into account by the Thomas-Fermi model of the neutral atom. Unlike the previous calculations we have used a distorted Coulomb wavefunction for the ejected electron. The effects of Coulomb distortion and of screening corrections are discussed. It is shown that the screening correction and the Coulomb distortion in the ejected electron wavefunction play significant roles in the study of incoherent X-ray scattering by bound electrons. 相似文献
2.
Narayanan Balaji Bhavesh Babulal Gabani Umesh Todmal Suresh P. Sulochana Neeraj Kumar Saini Rajesh Chandran Ramesh Mullangi 《Biomedical chromatography : BMC》2019,33(3)
We developed and validated a simple, sensitive, selective and reliable LC–ESI‐MS/MS method for direct quantitation of dropropizine enantiomers namely levodropropizine (LDP) and dextrodropropizine (DDP) in rat plasma without the need for derivatization as per regulatory guidelines. Dropropizine enantiomers and carbamazepine (internal standard) were extracted from 50 μL rat plasma using ethyl acetate. LDP and DDP resolved with good baseline separation (Rs = 4.45) on a Chiralpak IG‐3 column. The mobile phase consisted of methanol with 0.05% diethylamine pumped at a flow rate of 0.5 mL/min. Detection and quantitation were done in multiple reaction monitoring mode following the transitions m/z 237 → 160 and 237 → 194 for dropropizine enantiomers and the internal standard, respectively, in the positive ionization mode. The proposed method provided accurate and reproducible results over the linearity range of 3.23–2022 ng/mL for each enantiomer. The intra‐ and inter‐day precisions were in the ranges of 3.38–13.6 and 5.11–13.8 for LDP and 4.19–11.8 and 8.89–10.1 for DDP. Both LDP and DDP were found to be stable under different stability conditions. The method was successfully used in a stereoselective pharmacokinetic study of dropropizine enantiomers in rats following oral administration of racemate dropropizine at 100 mg/kg. The pharmacokinetic results indicate that the disposition of dropropizine enantiomers is not stereoselective and chiral inversion does not occur in rats. 相似文献
3.
A novel low-valent titanium (LVT) mediated cleavage of N-allyl/benzyl amines is reported. Regio- and chemo-selective cleavages were also observed. 相似文献
4.
S. S. Nath D. Chakdar G. Gope A. Talukdar D. K. Avasthi 《Journal of Dispersion Science and Technology》2013,34(7):1111-1113
We report synthesis of ZnS quantum dots by chemical method at room temperature. In this technique, ZnS quantum dots are produced by simple chemical reactions where zeolite, acts as matrix, plays the key role in controlling particle growth during synthesis. Quantum dots exhibit luminescence properties such as Zn2+ related emission, efficient low voltage electroluminescence, and super linear voltage-brightness EL characteristics. This study demonstrates the technological importance of semiconductor nanosystems prepared by low cost chemical route. 相似文献
5.
R. Talukdar A. Tripathy P.N. Bajaj P.K. Chakraborti G.D. Saksena 《Optics Communications》1983,45(3):179-182
Crossed laser molecular beam configuration was used to study the photoionization of U and UO by the UV-lines of an argon ion laser. Photoionization efficiencies of both U and UO were found to be line sensitive. Photoionization by the 3638 Å line was observed for the first time. Uranium atom ionization efficiency being higher for the 3345 Å and 3511 Å groups of lines, while UO ionization efficiency being maximum for the 3638 Å line. Dependence of photoion signal on laser power and relative photoionization efficiencies of the two isotopic species of uranium are also investigated. 相似文献
6.
7.
James B. Burkholder Abdelwahid Mellouki Ranajit Talukdar A. R. Ravishankara 《国际化学动力学杂志》1992,24(8):711-725
Rate coefficients, k1, for the reaction OH + HONO → H2O + NO2, have been measured over the temperature range 298 to 373 K. The OH radicals were produced by 266 nm laser photolysis of O3 in the presence of a large excess of H2O vapor. The temporal profiles of OH were measured under pseudo-first-order conditions, in an excess of HONO, using time resolved laser induced fluorescence. The measured rate coefficient exhibits a slight negative temperature dependence, with k1 = (2.8 ± 1.3) × 10?12 exp((260 ± 140)/T) cm3 molecule?1 s?1. The measured values of k1 are compared with previous determinations and the atmospheric implications of our findings are discussed. 相似文献
8.
9.
We derive an off-energy-shell generalization of the two-potential formula by using a coordinate-space approach and apply the
formalism to construct algorithms for studying spatial behaviour of the fully off-shellT matrix. We also suggest some future applications of the proposed theory. 相似文献
10.
A rigorous derivation of the optical theorem (OT) from the conservation of probability flux (CPF) is presented for scattering
on an arbitrary spherically symmetric potential inN-spatial dimensions (ND). The constructed expression for the OT is found to yield the corresponding well-known results for
two- and three-dimensional cases in a rather natural way. The Aharonov-Bohm (AB) effect is considered as a scattering event
of an electron by a magnetic field confined in an infinitely long shielded solenoid and a similar derivation is attempted
for an appropriate optical theorem. Our current understanding of the scattering theory is found to be inadequate for the purpose.
The reason for this is discussed in some detail. 相似文献