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991.
The S-H bond dissociation enthalpies [BDE(S-H)] of a set of 5-X- and 6-X-3-pyridinethiols (X = F, Cl, CH3, OCH3, NH2, N(CH3)2, CF3, CN, and NO2) have been computed using the density functional theory based (RO)B3LYP procedure with 6-311++G(2df,2p) basis set. The effects of substituents on the BDE(S-H), proton affinity of the pyridinethiol anion [PA(S-)] and ionization energy (IE) are analyzed and their correlations with Hammett's substituent constants are examined. Subsequently, a series of 6-substituted 3-pyridinethiols have been explored to find out their antioxidant potentials. Finally, a number of 3-pyridinethiol based compounds are theoretically proposed as novel antioxidants. 相似文献
992.
993.
Bianchi Type-V Magnetized String Cosmological Model with Variable Magnetic Permeability for Viscous Fluid distribution 下载免费PDF全文
We investigate the Bianchi type-V magnetized string cosmological model with variable magnetic permeability for viscous fluid distribution. The magnetic field is due to an electric current produced along the x-axis. Thus the magnetic field is in yz-plane and F23 is the only non-vanishing component of electromagnetic field tensor Fij. To obtain the deterministic model in terms of cosmic time t, we assume the condition ξθ const where ξ is the coefficient of bulk viscosity and θ the expansion in the model. 相似文献
994.
We reinvestigate the collective effects of the retardation as well as the bending on the Coulomb excitation cross sections and also on the B(E2) strengths of some neutron-rich isotopes using the intermediate energy Coulomb excitation theory. It is found that the B(E2) strengths extracted from the experimental Coulomb excitation cross section data get suppressed approximately by 6%. Furthermore, the obtained B(E2) strengths in the energy range 30-100 MeV/A are found to be in better agreement with the corresponding values known from other sources, than those obtained by using the recoil-corrected relativistic Coulomb excitation theory. 相似文献
995.
A Gaussian whistler pulse is shown to cause ponderomotive acceleration of electrons in a plasma when the peak whistler amplitude
exceeds a threshold value and the whistler frequency is greater than half the cyclotron frequency, ω>ω
c
/2. The threshold amplitude decreases with the ratio of plasma frequency to electron cyclotron frequency, ω
p
/ω
c
. However, above the threshold amplitude, the acceleration energy decreases with ω
p
/ω
c
. The electrons gain velocities about twice the group velocity of the whistler. 相似文献
996.
A series of polymer nanocomposite films based on intercalation of (PAN)8LiCF3SO3 into the nanometric clay channels of an organomodified clay has been prepared using the standard solution-casting technique.
The role of organoclay concentration on polymer–ion interaction, ion–ion interaction, and ion–clay interaction in clay-based
nanocomposite films has been analyzed using Fourier transform infrared (FTIR) analysis. Substantial ion dissociation is observed
even at a very low clay loading (1–2 wt.%) in the nanocomposites. FTIR results suggest the presence of both uncoordinated
CF3SO3
− (free-anions) and ion pairs in the nanocomposite evidenced by changes in CF3SO3
− symmetry from C3ν to Cs and marked asymmetry in the profile of degenerate δd(CF3
−) mode. The experimental results suggest a direct correlation of clay-assisted ion dissociation process with variation in
conductivity (σ
dc) and glass transition temperature (T
g) as a function of clay concentration. A model has been proposed to explain the observed correlation on the basis of polymer–ion–clay
interaction. The proposed scheme of ion transport mechanism appears to be consistent with the experimental observation. 相似文献
997.
Dattatray J. Late Ranjit V. Kashid Chandra Sekhar?Rout Mahendra A. More Dilip S. Joag 《Applied Physics A: Materials Science & Processing》2010,98(4):751-756
Field emission studies of WO2.72 nanowires synthesized by a solvothermal method have been performed in the planar diode configuration under ultra high vacuum
conditions. Fowler–Nordheim plots obtained from the current-voltage characteristics follow the quantum mechanical tunneling
process and a current density of ∼8.3×106 μA/cm2 can be drawn at an applied electric field of 2 V/μm. The field enhancement factor is 33025, while the turn-on field is only
1.4 V/μm. The emission current-time plot recorded at the pre-set value of emission current of 1 μA over a period of more than
3 h exhibits an initial increase and a subsequent stabilization of the emission current. The results reveal that the WO2.72 nanowire emitters synthesized by the solvothermal method are promising cathode materials for practical applications. 相似文献
998.
Prakash Barman M. Shubhakanta Singh Jameson Maibam R. K. Brojen B. Indrajit Sharma 《Indian Journal of Physics》2010,84(6):711-716
A computer program has been developed using Rutherford’s Screened Scattering Model and Energy loss model due to Bethe and
applied to simulate the electron interaction pattern in the sample of NbC and NbN with a resist layer of PMMA (Polymethyl
Methylacrylate). Using the program we have studied the extent of penetration, lateral spread for different electron energies
and the degree of electron back scattering. It has been found that backscattering and lateral spread is more in case of NbC
than in NbN signifying hard, refractory and ceramic properties of NbC. 相似文献
999.
Dalip Singh Mehta Kanchan Saxena Satish Kumar Dubey Chandra Shakher 《Journal of luminescence》2010,130(1):96-102
We report the measurement of coherence characteristics of light-emitting diodes (LEDs). Experiments were performed using red and green color LEDs directly illuminating the Young's double slit kept in the far-zone. Fourier transform fringe analysis technique was used for the measurement of the visibility of interference fringes from which the modulus of degree of spectral coherence was determined. Low degree of spectral coherence, typically 0.4 for red and 0.2 for green LED with double-slit separation of 400 μm was observed. A variable slit was then kept in front of the LEDs and the double slit was illuminated with the light coming out of the slit. Experiments were performed with various slit sizes and the visibility of the interference fringes was observed. It was found that visibility of the interference fringes changes drastically in presence of variable slit kept in front of LEDs and a high degree of spectral coherence, typically 0.85 for red and 0.8 for green LED with double-slit separation of 400 μm and rectangular slit opening of 500 μm was observed. The experimental results are compared with the theoretical counterparts. Coherence lengths of both the LEDs were also determined and it was obtained 5.8±2 and 24±4 μm for green and red LEDs, respectively. 相似文献
1000.
Annu Sharma 《Indian Journal of Physics》2010,84(4):391-395
In the present work, the Binary stopping power theory was used to calculate total ionization cross section and differential
cross section for energy transfer from a swift heavy ion to the target electrons. The dependence on the projectile charge
state is studied. The calculated values are compared with the experimental values collected from the literature. 相似文献