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121.
Poonam Singh U.P. Verma Per Jensen 《Journal of Physics and Chemistry of Solids》2011,72(12):1414-1418
The structural, electronic and optical properties of HgAl2Se4 are investigated using the full potential linear augmented plane wave method based on density functional theory. The calculated structural parameters using LDA are in excellent agreement with the available experimental result. The obtained energy band gap (2.24 eV) using EV-GGA approximation is in excellent agreement with experimental data (2.20 eV). Variation in the energy band gap as a function of the unit cell lattice parameter has been studied. The optical properties show a considerable anisotropy, which makes this compound very useful for various linear–nonlinear optical devices. 相似文献
122.
K. Kholiya S. Verma 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,83(1):23-28
The structural and elastic properties of cerium chalcogenides (CeZ, Z = S, Se, Te) under high pressure have been investigated
by using the potential model considered up to third nearest neighbor interaction. The computed values of B1-B2 phase transition
pressure, equation of state (compression curve), bulk modulus, its first order pressure derivative and elastic constants in
the case of cerium chalcogenides agree well with the experimental results. The present study shows the anomalous behavior
of cerium chalcogenides in comparison to the alkaline earth chalcogenides, due to the presence of Kondo effect and reentrant
valence behavior of Ce in cerium chalcogenides. 相似文献
123.
U. P. Verma N. Devi S. Sharma P. Jensen 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,81(4):381-386
First-principles calculations based on the density functional theory are
performed to study the structural properties, spin-polarized electronic band
structures, density of states and magnetic properties of the zinc blende
In1−
x
Mn
x
Sb (x = 0.125, 0.25, 0.50, 0.75, 1.0).
The calculated lattice constants of In1−
x
Mn
x
Sb
obey the Vegard’s law with a marginal upward bowing. With the increase of Mn
concentration in In1−
x
Mn
x
Sb, a transition from
the semi-metallic to the half-metallic behavior happens such that the
majority-spin valence states crosses the Fermi level and the minority-spin
states have a gap at the Fermi level. A large exchange splitting
(∼ 4 eV) is observed between Mn 3d states of the majority-spins
and the minority-spins. The total magnetic moment of
In1−
x
Mn
x
Sb half-metallic ferromagnets per Mn
atom basis is 4μ
B. The total magnetic moment per Mn atom
indicate that Mn atoms act as acceptors in InSb and contribute to holes in
the lattice of InSb. Due to p-d hybridization, the free space charge of Mn
reduces that results a loss in its magnetic moment. The loss in the magnetic
moment of the Mn atoms is converted into a small local magnetic moments on
the In and Sb sites. 相似文献
124.
Javaid A Sheikh Gopal K Khuller Indu Verma 《Journal of immune based therapies and vaccines》2011,9(1):1-8
Background
Immunotherapy to enhance the efficiency of the immune response in tuberculosis patients and to eliminate the persisters could be an additional valuable strategy to complement anti-mycobacterial chemotherapy. This study was designed to assess the immunotherapeutic potential of Ag85B as an adjunct to chemotherapy and its effect against active and persister bacteria left after therapy in mouse model of tuberculosis.Methods
6-8 week old female Balb/c mice were infected with Mycobacterium tuberculosis and treated with chemotherapy or immunotherapy. Protective efficacy was measured in terms of bacterial counts in lungs and spleen. Immune correlates of protection in terms of Th1 and Th2 cytokines were measured by ELISA.Results
Therapeutic effect of Ag85B was found to be comparable to that of short term dosage of antituberculous drugs (ATDs). The therapeutic effect of ATDs was augmented by the simultaneous treatment with rAg85B and moreover therapy with this protein allowed us to reduce ATD dosage. This therapy was found to be effective even in case of drug persisters. The levels of antigen specific IFNγ and IL-12 were significantly increased after immunotherapy as compared to the basal levels; moreover antigen specific IL-4 levels were depressed on immunotherapy with Ag85B.Conclusion
We demonstrated in this study that the new combination approach using immunotherapy and concurrent chemotherapy should offer several improvements over the existing regimens to treat tuberculosis. The therapeutic effect is associated not only with initiating a Th1 response but also with switching the insufficient Th2 immune status to the more protective Th1 response. 相似文献125.
The structural, microstructural, polarization, magnetization, dielectric constant, and relaxor characteristics of 0.7BiFeO3-0.3BaTiO3 (BF-BT) nanocrystals have been studied. BF-BT nanocrystals were prepared by a chemical route using polyvinyl alcohol as surfactant. The phase structure is confirmed by X-ray diffraction and average particle size by transmission and scanning electron microscopy. The magnetoelectric coupling is studied by polarization hysteresis loops under the influence of applied magnetic field and the phase transition anomaly. The diffuse phase transition is studied by modified Curie-Weiss law and relaxor characteristics by Vogel-Fulcher relation. 相似文献
126.
Anurag Jayswal Sarita Choudhury Ram U. Verma 《Journal of Applied Mathematics and Computing》2014,45(1-2):87-97
A new class of exponential form of vector variational-like inequality problems is introduced, and then the equivalence among (weakly) efficient solutions, vector critical points of vector optimization problem and the solutions of vector variational-like inequalities under the framework of (p,r)-invexity is established. To the best our knowledge, the presented results are new and highly application oriented to other results based on generalized invexities to the context of optimization problems in the literature. 相似文献
127.
On the basis of the general framework of H-maximal monotonicity (also referred to as H-monotonicity in the literature), a generalization to Rockafellar’s theorem in the context of solving a general inclusion problem involving a set-valued maximal monotone operator using the proximal point algorithm in a Hilbert space setting is explored. As a matter of fact, this class of inclusion problems reduces to a class of variational inequalities as well as to a class of complementarity problems. This proximal point algorithm turns out to be of interest in the sense that it plays a significant role in certain computational methods of multipliers in nonlinear programming. The notion of H-maximal monotonicity generalizes the general theory of set-valued maximal monotone mappings to a new level. Furthermore, some results on general firm nonexpansiveness and resolvent mapping corresponding to H-monotonicity are also given. 相似文献
128.
Inderpreet Singh A. Verma I. Kaur L. M. Bharadwaj V. Bhatia V. K. Jain C. S. Bhatia P. K. Bhatnagar P. C. Mathur 《Journal of Polymer Science.Polymer Physics》2010,48(1):89-95
DC conductivity of conjugated polymer‐single‐walled carbon nanotube (SWNT) composite films has been measured for different SWNT concentrations. The composite was prepared by dispersing SWNTs in the poly (3‐octylthiophene), P3OT matrix already dissolved in xylene. The conductivity of the composite films showed a rapid increase as the SWNT concentration increases beyond a certain value. This behavior is explained in terms of percolating paths provided by the SWNTs in the volume of polymer matrix. To investigate the effect of length of nanotubes on the percolation conductivity, different SWNT samples were employed with similar diameter but varying tube lengths. It was found that the conductivity of the composite films is strongly dominated by the length of the nanotubes. Lower percolation limit and high conductivity value of composite films is observed for longer nanotubes. Furthermore, the conductivity is observed to be dependent on the size of the host polymer molecule also. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 89–95, 2010 相似文献
129.
The kinetics of hydrolysis of p‐nitrophenyl acetate catalyzed by α‐chymotrypsin (α‐CT) has been studied in the presence of several cationic surfactants having different head groups maintaining the dodecyl hydrophobic residue and bromide counterion. The enzyme activity was tested in the presence of dodecyl trimethylammonium bromide (DTAB), dodecylpyridinium bromide (DPB), dodecyldimethylethanolammonium bromide (DDMEAB), dodecyldiethylethanolammonium bromide (DDEEAB), benzyldimethyldodecylammonium bromide (BDDAB), and dodecyltriphenylphosphonium bromide (DTPB) surfactants. The extent of superactivity depends upon head groups of surfactants. The activity of α‐CT depends on the surfactant concentration and it varies with the surfactant head group dimensions (DTPB > DDEEAB > DTAB > BDDAB > DDMEAB > DPB). For all surfactants, DTPB exhibits highest superactivity. The effects of surfactants on the apparent kinetic parameters like Michaelis constant Km and the catalytic constant kcat have been determined. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 377–381, 2009 相似文献
130.
Mahendra K. Verma 《Pramana》2003,61(3):577-594
Energy cascade rates and Kolmogorov’s constant for non-helical steady magnetohydrodynamic turbulence have been calculated
by solving the flux equations to the first order in perturbation. For zero cross helicity and space dimensiond = 3, magnetic energy cascades from large length-scales to small length-scales (forward cascade). In addition, there are energy
fluxes from large-scale magnetic field to small-scale velocity field, large-scale velocity field to small-scale magnetic field,
and large-scale velocity field to large-scale magnetic field. Kolmogorov’s constant for magnetohydrodynamics is approximately
equal to that for fluid turbulence (≈ 1.6) for Alfvén ratio 05 ≤r
A ≤ ∞. For higher space-dimensions, the energy fluxes are qualitatively similar, and Kolmogorov’s constant varies asd
1/3. For the normalized cross helicity σc →1, the cascade rates are proportional to (1 − σc)/(1 + σc , and the Kolmogorov’s constants vary significantly with σcc. 相似文献