Synthesis and Photochemistry of Novel 3,5-Diacetyl-1,4-dihydropyridines

 Some novel 3,5-diacetyl-1,4-dihydropyridine derivatives were synthesized; their photochemical behaviour was studied under oxygen or argon atmosphere. Irradiation of these compounds resulted in the aromatization of the ring and formation of 3,5-diacetylpyridine derivatives. The presence of oxygen plays an important role in the type, rate, or failure of oxidation. Irradiation of these compounds with of 2-furyl or 5-methyl-2-furyl substituents in position 4 under argon resulted in the formation of a pyridine ring with retention of these substituents, whereas loss of these substituents and ring aromatization was observed upon irradiation under oxygen.     

Extension of the electrolyte NRTL and Wilson models for correlation of viscosity of strong electrolyte solutions at different temperatures

The electrolyte NRTL model [C.C. Chen, L.B. Evans, AIChE J. 32 (1986) 444–454] and electrolyte Wilson model [E. Zhao, M. Yu, R.E. Sauvé, M. Khoshkbarchi, Fluid Phase Equilibr. 173 (2000) 161–175] have been extended for the representation of the dynamic viscosity of strong electrolyte solutions. The models are based on Eyring's absolute rate theory and the electrolyte NRTL and Wilson models for calculating the excess Gibbs energy of activation of the viscous flow. The utility of the models is demonstrated with a successful representation of the viscosity of several electrolyte solutions at different temperatures. The results show that, the model is valid for the whole range of salt concentration and it is reliable for correlation of the viscosity of electrolyte solutions at different temperatures by only four adjustable parameters per binary system.     

Symmetry constraints in energy transfer between state-selected Ar*(3P2, 3P0) metastable atoms and ground state H atoms

The excitation-transfer reaction in thermal energy collisions of state-selected metastable Ar*(³P₂) and Ar*(³P₀) atoms with ground state H atoms, giving excited H*(n = 2) atoms, has been studied with the stationary afterglow technique. The rate constant for the excitation of H atoms by Ar*(³P₂) has been found to be more than one order of magnitude larger than in excitation by Ar*(³P₀). This difference in the reactivity of two metastable species is explained to be a consequence of the attractive nature of the D(²II) and E(²Σ⁺) potentials that develop from the Ar*(³P₂)+H entrance channel and which give curve crossing with the B(²II) and C(²Σ⁺ potentials, respectively, leading to the Ar+H*(n=2) exit channel, whereas only a repulsive ⁴II (Ω=$\text{1}\text{2}$) potential develops from the Ar*(³P₀+H entrance channel.     

Triton Photodisintegration with Effective Field Theory

Effective field theory (EFT) has been recently used for the calculation of neutron–deuteron radiative capture at very low energies. We present here the use of EFT to calculate the two-body photodisintegration of the triton, considering the three-body force. The calculated cross section shows sharp rising from threshold to maximum about 0.88 mb at ~13 MeV and decreasing slightly to about 0.81 mb at ~19 MeV, in agreement with the experimental data. Our results are in good agreement with the experimental data and the other calculations using modern realistic two- and three-nucleon forces, like AV18/UrbanaIX potential.     

Nonclassical properties of a particle in a finite range trap: The f-deformed quantum oscillator approach

A particle bounded in a potential with finite range is described by using an f-deformed quantum oscillator approach. Finite range of this potential can be considered as a controllable deformation parameter. The nonclassical quantum statistical properties of this deformed oscillator can be manipulated by nonlinearities associated to the finite range.     

Thermal entanglement of a two-level atom and bimodal photons in a Kerr nonlinear coupler

In this paper thermally induced entanglement between a two-level atom and photons inside a bimodal nonlinear coupler is studied. The interaction occurs in the presence of a centrosymmetric medium which couples the two photonic modes via the first and third order susceptibilities. Such effects on the atom–photons interaction, however, are assumed negligible so that the linear Jaynes–Cummings model applies. It is further assumed that the coupler is held at a temperature T$T$, so that each of the combined atom–photon states, with a definite, T$T$ dependent, probability, is present. The partially transposed density matrix and, consequently, the negativity, as a measure of entanglement, are determined as functions of temperature. The negativity so calculated shows that the system of a two-level atom and photons is separable at zero temperature, becomes more entangled, reaching the maximal at a certain temperature and asymptotically disentangles. Effect of medium characteristics on such behavior is also discussed.     

Thermal performance investigation of DQW GaInNAs laser diodes

In this work, we optimize the thermal performance of a double quantum well GaInNAs ridge waveguide laser using an accurate in-house 2D electro-opto-thermal laser simulator. The simulator has shown good agreement with experiments after a detailed calibration procedure. Using calibrated material parameters, we investigate the influence of the cladding doping level on the heat generation within the laser. It is found that due to the competition between Joule heating and free carrier absorption, an optimum cladding doping level exists.     

Non-minimally coupled quintom model inspired by string theory

In this Letter we consider a quintom model of dark energy with a single scalar field T given by a Lagrangian which inspired by tachyonic Lagrangian in string theory. We consider non-minimal coupling of tachyon field to the scalar curvature, then we obtain the equation of state (EoS), and the condition required for the model parameters when ω crosses over −1.     

The simple chaotic model of passive dynamic walking

Recent findings on the dynamical analysis of human locomotion characteristics such as stride length signal have shown that this process is intrinsically a chaotic behavior. The passive walking has been defined as walking down a shallow slope without using any muscular contraction as an active controller. Based on this definition, some knee-less models have been proposed to present the simplest possible models of human gait. To maintain stability, these simple passive models are compelled to show a wide range of different dynamics from order to chaos. Unfortunately, based on simplifications, for many years the cyclic period-one behavior of these models has been considered as the only stable response. This assumption is not in line with the findings about the nature of walking. Thus, this paper proposes a novel model to demonstrate that the knee-less passive dynamic models also have the ability to model the chaotic behavior of human locomotion with some modifications. The presented novel model can show chaotic behavior as a stable and acceptable answer using a chaotic function in heel-strike condition. The represented chaotic model is also able to simulate different types of motor deficits such as Parkinson’s disease only by manipulating the value of chaotic parameter. Our model has extensively examined in complexity and chaotic behavior using different analytical methods such as fractal dimension, bifurcation and largest Lyapunov exponent, and it was compared with conventional passive models and the stride signal of healthy subjects and Parkinson patients.