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81.
The existence of a new class of double humped grey and dark solitons in a Kerr nonlinear medium has been predicted in this paper. Following well known variational procedure, the dynamics of the propagating soliton has been converted to a Hamiltonian formulation. A set of ordinary differential equations is then derived, which was subsequently examined to predict the existence of double humped grey and dark solitons. Linear stability analysis, numerical appreciation and phase plane dynamics show that these solitons are stable. 相似文献
82.
The analytical solution of the quantum driven harmonic oscillator of time dependent mass and frequency (DHTDMF) is exploited to obtain the photon-bunching, photon-antibunching and the nonclassical photon statistics of the input coherent light coupled to the oscillator. We observe that the model Hamiltonian of a DHTDMF coincides with those of the model Hamiltonian of a two-photon coherent state due to H.P. Yuen [Phys. Rev. A 13 (1976) 226]. To substantiate our analytical results, we give a special case corresponding to a damped harmonic oscillator subject to an external periodic force. The quantum statistical properties of the radiation field are discussed for under-, over-, and for critically-damped situations of the oscillator coupled to an initial coherent field. The off-resonance and the near- or on-resonance of the oscillator with respect to the frequency of the external force are discussed. In the determination of quantum statistical properties of the radiation field, we observe that the effects of the driving force are important only when the frequency of the oscillator is in near- or in on-resonance condition with that of the frequency of the external periodic force. 相似文献
83.
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85.
So-Yon Lim Adam Bauermeister Richard A Kjonaas Swapan K Ghosh 《Journal of immune based therapies and vaccines》2006,4(1):5-10
Background
Adjuvants are known to significantly enhance vaccine efficacy. However, commercial adjuvants often have limited use because of toxicity in humans. The objective of this study was to determine the comparative effectiveness of a diterpene alcohol, phyto l and its hydrogenated derivative PHIS-01, relative to incomplete Freund's adjuvant (IFA), a commonly used adjuvant in augmenting protective immunity in mice against E. coli and S. aureus, and in terms of inflammatory cytokines. 相似文献86.
Ankita Chakraborty Sudipto Debnath Tanmoy Ghosh Dilip K. Maiti Swapan Majumdar 《Tetrahedron》2018,74(40):5932-5941
A sustainable route for the N-1 alkylation of imidazole and benzimidazole derivatives has been developed under volatile organic solvent free condition in alkaline water-SDS system. Incorporation of SDS in the reaction medium enhances the reaction rate by suppressing the solubility issue that arises for different substrates. This method provides high yield of the alkylated product in a shorter reaction time. For reactive alkyl halides reaction proceeds at ambient temperature whereas in the cases of less reactive alkyl halides require 55–60?°C to complete alkylation process. N-alkylation induced ring opening of the heterocyclic ring in benzimidazole derivatives to multifunctional aromatic compounds were noticed at 60?°C when more than two equivalents of alkyl halide was used. 相似文献
87.
We investigate the nonlinear optical (NLO) polarizations for various geometric arrangements of the dipolar chromophores in a calix[n]arene geometry. The interactions were studied by using (HF)3 as model compounds both in parallel and frustrated orientations. The interdipolar angle between the monomer molecules is varied so that many different arrangements of the dipoles can be realized which is associated with the opening up of the calix[n]arene rings. Quantum-chemical calculations at both ab initio and semiempirical levels, show that the all-parallel arrangement of the dipoles exhibit the maximum magnitude for the nonlinear optical coefficients at small interdipolar angles for all interdipolar distances. In the frustrated orientations however, the NLO response is maximum at large interdipolar angles corresponding to the flattened calix[n]arene rings. The role of hydrogen bonding in stabilizing these assemblies in various conformations has been investigated. Crystallographic database analysis for calix[3]arenes shows that optical properties in real molecular systems can be modeled based on our simple interaction theory. 相似文献
88.
Ab initio and density functional theoretical studies on hydrogen-bonded complexes of azabenzenes with water, acetamide, and thioacetamide have been carried out to explore the controversy involved in the relative order of their stability in a systematic way. The interaction energies of these complexes have been analyzed using the Morokuma energy decomposition method, and the nature of the various hydrogen bonds formed has been investigated through topological aspects using Bader's atom in a molecule (AIM) theory. Morokuma energy decomposition analysis reveals that the major contributions to the energetics are from the polarization (PL) and charge transfer (CT) energies. From the calculated topological results, excellent linear correlation is shown to exist between the hydrogen-bond length, electron density [rho(r)], and its Laplacian [nabla(2)rho(r)] at the bond critical points for all the complexes considered. 相似文献
89.
The unimolecular and collision-induced fragmentation reactions of the enolate ion of 2,3-butanedione, [CH3COCOCH2]?, have been studied, Unimolecular fragmentation on the metastable ion time-scale forms [HCCO]?, [C2H3O]?, [C3H5O]? and [CH3CO2]?. Charge inversion mass spectrometry shows that the [C2H3O]? ion is the acetyl anion while the [C3H5O]? product is the acetone enolate ion; formation of the latter product involves a large release of kinetic energy (T 1/2 = 0.99 eV). The fragmentation reactions occurring following collisional activation have been determined for 8 keV collisions and over the range 1.5–30 eV center-of-mass collision energy. Formation of [HCCO]? and [CH3CO]? are of the most important reactions following collisional activation and it is concluded that the two reactions have similar critical reaction energies even though formation of [HCCO]? is favored thermochemically. 相似文献
90.
In view of the variety of low-temperature magnetic properties reported recently for kagome lattices with transition-metal ions in different oxidation states, we have investigated the low-energy spectrum and low-temperature thermodynamic properties of antiferromagnetic kagome lattices with varying magnitudes of site spins, employing quantum many-body Heisenberg models. The ground state and the low-lying excitation spectrum are found to depend strongly on the nature of the spin magnitude of the magnetic ions. The system remains highly frustrated if spins are half-odd-integer in magnitude, while the frustration is very weak or almost absent for integer spins or mixed-spin systems. In fact, for a mixed-spin kagome system with a certain magnitude, the whole system behaves as a classical magnet with a ferrimagnetic ground state without any frustration. These theoretical findings are consistent with a few experimental observations recently reported in the literature and would be of value in designing new kagome systems with unusual and interesting low-temperature magnetic properties. 相似文献