Rayleigh–Benard Convection in the homeotropic nematic liquid crystal by a Gaussian laser beam absorption

The Rayleigh–Benard Convection (RBC) were studied theoretically in the homeotropic nematic liquid crystal (NLC) cell due to the absorption of a normally incident Gaussian light beam from upper side of the cell. It was shown that a convection of hydrodynamic motion in the NLC can be induced and eventually the molecular director coupling with hydrodynamics reorients the director. An external magnetic field parallel to the director decreases the director reorientation and the radial flow velocity, while the velocity in the z direction is unaffected. The results were found to be in a range that can easily be checked experimentally.     

Transient absorption–dispersion properties of four-level atomic system via elliptically polarized probe light and magnetic field

A novel four-level atomic system which interacted by an elliptically polarized probe field and a control laser field in the presence of external magnetic field is proposed. Here, we are interested in the transient properties of a weak probe field due to its potential application on quantum computing and quantum communication. It is shown that the external magnetic field and relative phase between two electric field components of the probe field can influence the probe absorption and dispersion.     

Phase Control of Transient Optical Properties of Quantum-Dot Nanostructure via Terahertz Signal Radiation

We theoretically analyze the transient properties of a probe field absorption dispersion in a quantum-dot nanos- trueture driven by terahertz signal radiation. Here a four-level quantum-dot nanostructure is designed numerically by Schrodinger and Poisson＇s equations. We show that in the presence of the THz signal, the medium becomes phase dependent and the absorption dispersion can be dramatically influenced by the relative phase between applied fields.     

Optical bistability and multistability in a parametric region

We study the optical bistability (OB) and optical multistability (OM) behaviors in a five-level $\Lambda $ -type parametric region atomic system by two-photon resonant transitions. We find that the intensity threshold of OB and switching from OB to OM or vice versa can be controlled via quantum interference between different two-photon transitions pathways.     

Er3＋ ion concentration effect on transient and steady-state behavior in Er3＋ ：YAG crystal

The effect of Er3＋ ion concentration on transient and steady-state behavior in 45-nm Er3＋ ：YAG crystal is investigated. It is shown that by changing the signal field, the coherent field and the concentration of Er3＋ ions in the crystal, the absorption, dispersion, and group index of the weak probe field can be adjusted. Also, it is found that the probe absorption occurs in the presence of population inversion and probe amplification is obtained in the absence of population inversion.     

Effect of Quantum Interference from Incoherent Pumping Field and Spontaneous Emission on Controlling the Optical Bistability and Multi-Stability

Optical bistability (OB) and optical multi-stability (OM) of a four-level Λ-type atomic system with two fold lower levels inside a unidirectional ring cavity is investigated. The effect of quantum interference arising from spontaneous emission and incoherent pumping on OB and OM is discussed. It is found that the threshold of OB and OM can be controlled by quantum interference mechanisms. In addition intensity of coupling field and the rate of an incoherent pumping field on behavior of OB and OM are then discussed.     

Electro-assisted self-assembly of mesoporous silica thin films: application to electrochemical sensing of glutathione in the presence of copper

Journal of Solid State Electrochemistry - Oxidation of the reduced form of glutathione based on the 1:1 copper(Cu+2)-glutathione(GSH) complexes was found to occur at a decreased overpotential at a...     

Evaluation of poly ε-caprolactone electrospun nanofibers loaded with Hypericum perforatum extract as a wound dressing

Research on Chemical Intermediates - In this study, for the first time, a biocompatible and non-toxic herbal wound dressing was made by encapsulation of Hypericum perforatum alcoholic extract at...     

Sensitized spectrophotometric determination of Cr(III) ion for speciation of chromium ion in surfactant media using alpha-benzoin oxime

A simple and accurate micellanized spectrophotometric method for determination of trace amounts of Cr(III) ion in tab and top water and a synthetic mixture has been described. The micellar method is based on effect of organized molecular assemblies such as micelles in spectrophotometric measurement due to their effect on the systems of interest. The ability of micellar system in solubilizing of sparingly soluble ligand or complexes has been used for increasing figures of merit of an analytical method. Due to solubility increasing in aqueous media requirement for a primary extraction can be eliminated. Using the alpha-benzoin oxime (alpha-BO) spectrophotometric determination of Cr(III) ion has been performed and results are compared. The spectrophotometric determination of Cr(III) ion using alpha-BO in the presence of non-ionic surfactant Triton X-100 has been performed. The influence of type and amount of surfactant, pH, complexation time and amount of ligand were examined. Finally, the repeatability, accuracy and the effect of interfering ions on the determination of Cr(III) ion was evaluated. The proposed methods successfully with recovery yield of almost 100% have been applied to the rapid and simple determination of Cr(III) ion in the real samples. There is a good agreement between methods and atomic absorption spectrometry. The Beers law is obeyed over the concentration range of 0.1-13.7 microg mL(-1) for micellar media. The detection limit is 0.8 ng mL(-1). The molar absorptivity of complex is 5350 L mol(-1) cm(-1).     

Role of incoherent pumping and Er3+ ion concentration on subluminal and superluminal light propagation in Er3+-doped YAG crystal

We study the absorption-dispersion process and group index of weak probe field in a four-level Er3+:YAG crystal.We find that the Er3+ion concentration and incoherent pumping field can influence the absorption-dispersion process and group index of weak probe field.Moreover,our results show that Er3+ion concentration plays a major role in lasing without inversion and absorption with inversion.