Tunable full band gap in two-dimensional anisotropic photonic crystals infiltrated with liquid crystals

We analyze the tunability of full band gap in two-dimensional photonic crystals created by square and triangular lattices of anisotropic tellurium rods in air background, considering that the rods are infiltrated with liquid crystal. Using the plane-wave expansion method, we study the variation of full band gap by changing the optical axis orientation of liquid crystal.     

Modeling of transient and steady-state dark current in amorphous silicon p–i–n photodiodes

A theoretical model for describing the bias-dependent transient and steady-state behavior of dark current in hydrogenated amorphous silicon (a-Si:H) p–i–n photodiode has been developed. An analytical expression for the bias-dependent steady-state thermal generation current is derived by solving the continuity equations for both electrons and holes. The model for describing transient dark current in a-Si:H p–i–n photodiode is developed by considering the depletion of electrons from the i-layer and carrier injection through p–i interface. For photodiodes that have very good junction properties, the high initial dark current decreases with time monotonously and reaches a plateau. However, in case of poor junctions, the injection current can be the dominating mechanism for transient leakage current at relatively high biases, the dark current decays initially and then rises to a steady-state value. The proposed physics-based dark current model is compared with published experimental results on several photodiodes. The comparison of the model with the experimental data allows an estimate of active dopant concentration in the p-layer and the defect density in the midgap of i-layer.     

Synthesis and ethylene polymerization of 8‐(fluorenylarylimino)‐5,6,7‐trihydroquinolylnickel chlorides: Tailoring polyethylenes by adjusting fluorenyl position and adduct Et2Zn

A series of 8‐(arylimino)‐5,6,7‐trihydroquinolines ligand pendant fluorenyl group at N‐aryl ring, and their nickel complexes ( Ni1 ? Ni5 ) have been prepared and characterized. Once activated with Et₂AlCl, the complexes Ni1 , Ni2 , and Ni3 bearing ligands from para‐fluorenylaniline produced unimodal polyethylenes; on the contrary complexes Ni4 and Ni5 gave bimodal polyethylenes due to steric influence of ligands from ortho‐fluorenyl anilines. With a increment of Et₂Zn/ Ni4 ratio from 0 to 400, the distinct bimodel polyethylenes were obtained with molecular weights shifted from 14.3 to 57.6 kg·mol^?1; apart shiftment to higher molecular weights, the portion of low molecular weight decreased along with higher portion of high molecular weight. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 1910–1919     

Atomic absorption and inductively coupled plasma–optical emission spectroscopic method for determination of micronutrients and toxic metals in Curcuma longa L. to characterize human health toxicity

Environment-friendly procedures for determination of nutritious and harmful elements in curcuma longa L. and commercially available turmeric powder are presented. Microwave and ultrasound (probe and bath) procedures for sample preparations were adopted and the elements were determined by validated flame atomic absorption and inductively coupled plasma–optical emission spectrometry. Student’s t-test was established whether there was a difference between the sample preparation methods. Trueness of certified values by all methods was ensured which were not differing significantly at 95% level of confidence interval. % recovery and relative standard deviation are in compliance with Food and Drug Administration-USA guidelines for spectrometric determination of elemental composition in food stuffs. Results showed that concentrations of copper, iron, manganese, and zinc found in both types of samples are promising source of nutrition. Exposure to aluminum, cadmium, and lead from consumption of products under investigation was estimated and few sample contents were higher than permissible level suggested by Food and Agriculture Organization-UN. Regarding the food safety monitoring, the proposed methods are rapid and met green chemistry approach can be implemented in laboratories easily for routine analysis.     

Softening Hard Water Using High Frequency Spark Plasma Discharge

Effects of high frequency spark plasma discharge as a time efficiency method in order to softening the natural hard water has been investigated experimentally. A very hard water sample with 331 ± 19 mg/l of CaCO₃ hardness was used. The current and voltage of each spike was about 9.6 A and 3.5 kV respectively at 16 kHz frequency with 35 μs pulse width. Hard water was treated for 2, 4, 6, and 8 min. The concentration of CaCO₃, Ca²⁺ ions, Mg²⁺ ions and pH as well as water conductivity was controlled before and after treatment. The concentration of CaCO₃ dropped by 70%, after 8 min treatment. During the treatment, the pH had a fluctuation about 1.5 and finally remained in neutral state. Also the elemental composition, crystalline structure and morphology of the precipitates were identified. Molecular dynamics simulation revealed that the ozone and hydroxyl play important roles in the softening of the hard water.