Finite-difference time-domain numerical simulation study on the optical properties of silver nanocomposites

The effects of the nanoparticle geometry and the host matrix on the optical properties of silver (Ag) nanocomposites were investigated. The spatial intensity distribution and absorption spectra were obtained by solving Maxwell equations using the finite-difference time-domain method. Local enhancement of the optical field was produced near the surface of the Ag nanoparticle. As the nanoparticle size increased, the plasmon-induced absorption increased and the surface plasmon resonance (SPR) wavelength of the Ag nanocomposite was redshifted. As the nanoparticle geometry was transformed from a sphere to an ellipsoid, two plasmon peaks appeared and their spectral spacing became larger with increasing the aspect ratio. The effects of the nanoparticle size and the anisotropic geometry on the optical properties of the Ag nanocomposites can be described by the Maxwell-Garnett theory and the Drude model. From the absorption spectra of the Ag nanocomposites with five different host matrices (SiO2, Al2O3, ZnO, ZrO2, and TiO2), it was found that the SPR wavelength of the Ag nanocomposite was redshifted with increasing the refractive index of the host matrix.     

Pharmacokinetics of doxazosin gastrointestinal therapeutic system after multiple administration in Korean healthy volunteers

Doxazosin mesylate is a selective alpha-adrenoreceptor antagonist for the treatment of hypertension and benign prostatic hyperplasia. A simple high performance liquid chromatographic method has been developed and validated for the quantitative determination of doxazosin in plasma. A reversed phase C18 column was used for the separation of doxazosin and prazosin (internal standard) with a mobile phase composed of water • acetonitrile • triethylamine (68:32:0.2 v/v, pH 5.0) at a flow rate of 1.2 mL/min. The fluorescence detector was operated at 246 (excitation) and 389 nm (emission). Intra- and inter-day precision and accuracy were acceptable for all quality control samples including the lower limit of quantification of 1 ng/mL. Recovery of doxazosin from human plasma was greater than 93.4%. Doxazosin was stable in human plasma under various storage conditions. This method was used successfully for a pharmacokinetic study in plasma after oral administration of multiple 4-mg dose of doxazosin gastrointestinal therapeutic system formulation to 16 healthy volunteers. At steady state the mean area under the curve for a dosing interval and elimination half-life were calculated to be 367.0 ± 63.5 ng · hr/mL and 29.2 ± 4.5 hr, respectively. There was no difference in pharmacokinetic parameters between male and female.     

Novel Interference Cancellation of Channel Estimation Scheme Based on LTE in V2V Communications

Transportation infrastructures integrate advanced Information Technology to enable the operations and management of transportation systems. Advanced vehicle and road systems of a comprehensive concept that improve the efficiency and safety of road traffic are being built and will be commercially available through Intelligent Transport Systems (ITS) technology and services. To support ITS technology, Vehicle-To-Everything (V2X) is needed, and in the 3rd Generation Partnership Project, many studies have focused on Long Term Evolution (LTE)-based vehicle communications. In order to realize reliable and optimized communications performance in vehicle communications, which move in propagation environments at high speed, in this study, we propose a novel channel estimation scheme suited for LTE sidelink-based Vehicle-To-Vehicle systems. Conventional channel estimation schemes can be categorized as Decision-Directed Channel Estimation, spectral temporal averaging, and smoothing methods. In this study, unlike conventional channel estimation schemes, we propose a Novel Interference Cancellation of Channel Estimation (NICCE) using Quadratic Smoothing of the pilot symbols, which estimates a channel with greater accuracy, and a novel interference cancellation of channel estimation in data symbols. In simulation results, the proposed NICCE scheme shows improved overall performance in terms of the Normalized Mean Square Error and uncoded Bit Error Rate relative to conventional schemes.     

Optical characterization of Cu2ZnSnSe4 grown by thermal co-evaporation

Cu₂ZnSnSe₄ thin films with different substrate temperature and Cu flux were grown by thermal co-evaporation. Raman scattering, photoluminescence, and contactless electroreflectance (ER) measurements were performed. The Raman spectra of Cu₂ZnSnSe₄ show two main peaks at 170 and 192 cm^− 1. The photoluminescence spectrum shows a peak below 1.0 eV. Franz-Keldysh oscillations (FKOs) were observed in the ER spectra. From the analysis of the FKOs, the bandgap energy of Cu₂ZnSnSe₄ thin films is estimated to be 1.07 eV at 90 K and 0.99 eV at room temperature. We conclude that the bandgap energy of Cu₂ZnSnSe₄ thin films is around 1.0 eV.