Holographic Brownian motion in 2+1 dimensional hairy black holes

In this paper, we investigate the dynamics of a heavy quark for plasmas corresponding to three dimensional hairy black holes. We utilize the AdS/CFT correspondence to study the holographic Brownian motion of this particle with different kinds of hairy black holes. For an uncharged black hole in the low frequency limit we derive analytic expressions for the correlation functions and the response functions and verify that the fluctuation–dissipation theorem holds in the presence of a scalar field against a metric background. In the case of a charged black hole, we think that the results are similar to that derived for an uncharged black hole.     

Evaluating flood extent mapping of two hydraulic models, 1D HEC‐RAS and 2D LISFLOOD‐FP in comparison with aerial imagery observations in Gorgan flood plain,Iran

We compared flood mapping techniques using a one‐dimensional (1D) hydraulic model HEC‐RAS and two‐dimensional (2D) LISFLOOD‐FP for a 10‐km reach of Gorgan River in Iran. Both models were run using the same hydrologic input data. The input into the models was a steady discharge of 90 cm, corresponds to a flood peak occurred on March 25, 2012. Flood maps generated using these two models were compared with an observed flood inundation map, using F‐statistic. The roughness coefficients of the models were calibrated by maximizing the value of the F‐statistic. Based on the F‐statistic, LISFLOOD‐FP gives a slightly better result (F = 0.69) than HEC‐RAS (F = 0.67). Visual comparison of the flood extents generated by the two models showed reasonably good agreement. Validation was done using a flood event occurred on May 31, 2014. The LISFLOOD‐FP model gave a better result for validation as well. The 2D model showed more consistency in comparison with the 1D model.     

Simple Hydrothermal Synthesis of Nickel Hydroxide Flower-Like Nanostructures

α-Ni(OH)₂ flower-like nanostructures were successfully synthesized through one-step hydrothermal method with nickel acetate tetrahydrate, ethylene-1,2-diamine (en), hexamethylenetetramine (HMT) and cetyltrimethylammonium bromide (CTAB) as morphology-directing agents. Optimum conditions to obtain high yield and pure phase α-Ni(OH)₂ were identified by varying experimental parameters such as: en, HMT and CTAB concentration and reaction temperature. The products were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared and thermogravimetric analysis. These results indicated that the α-nickel hydroxide contains water molecules and anions. The hierarchical NiO nanostructures were obtained by the as-synthesized α-Ni(OH)₂ nanostructures annealed at 300 °C for 4 h.     

Methanesulfonic Acid/SiO2 as an Efficient Combination for the Synthesis of 2-Substituted Aromatic and Aliphatic Benzothiazoles from Carboxylic Acids

Methanesulfonic acid/SiO₂ (1 mL/0.3 g) was found to be as an expeditious mixture in the synthesis of 2-substituted aromatic and aliphatic benzothiazoles at 140 °C using carboxylic acids. After a simple workup, benzothiazoles were obtained in good yields. Simplicity, use of widely available and diverse carboxylic acids, and easy handling of the reaction conditions are among the benefits of the method.     

Comparison of novel pyridine-functionalized mesoporous silicas for Au(III) extraction from natural samples

A technique for solid-phase extraction utilizing pyridine-functionalized nanoporous silica (MCM-41, MCM-48 and SBA-15) was developed for the determination of gold in different samples using flame atomic absorption spectrometry. The effects of concentration and volume of eluent, pH of the solution, flow rate of extraction, sample volume and of potentially interfering ions on the efficiency of preconcentration and recovery was investigated. The limit of detection is lower than 45 pg mL^?1. Under optimal conditions, the accuracy and precision (RSD%) of the method were calculated to be >99.5% and <0.7% for the two MCMs (41 and 48) and >89.5%, and <1.5% for SBA-15, respectively. The SPE technique was used to determine the concentration of gold in natural and industrial wastewater with satisfactory results.

Effects of operating parameters on oxidative coupling of methane over Na-W-Mn/SiO2 catalyst at elevated pressures

The effects of operating parameters on oxidative coupling of methane (OCM) over Na-W-Mn/SiO2 catalyst have been studied at elevated pressures of 0.2, 0.3 and 0.4 MPa under low gaseous hourly space velocity (GHSV) and low temperature conditions. Experimental results show that when the operating pressure is increased, C2+ yield slightly decreases, while the maximum ratio of ethylene to ethane remains unchanged. Moreover, it has been found empirically that increase of pressure does not affect the catalyst behavior permanently, the catalyst recovers its original low pressure performance without hysteresis behavior by reducing the pressure. Under the investigated conditions, when oxygen is completely consumed, the increase of GHSV leads to improvement in C2 selectivity, while C3+ and COx selectivities decrease slightly. The C2+ selectivity increases by increase of nitrogen diluent in the feed, but the C3+ hydrocarbons selectivities decrease with increase of nitrogen since it is possible that further dilution at high pressure may reduce the probability of collision between CH3 and C2+ hydrocarbons. During the stability test at high pressure, the catalyst performance remains unchanged throughout the 20 h running. The fresh and used catalysts were characterized using XRD, SEM and N2 adsorption-desorption methods. It was found that the phase transformation of the support from α-cristobalite to tridymite and quartz does not have obvious effect on catalyst performance at high pressure.     

Nuclear data for the cyclotron production of 117Sb and 90Nb

This presented study is to make comparison of cross sections to produce 117Sb and 90Nb via different reactions with particle incident energy up to 70 MeV as a part of systematic studies on particle-induced activations on enriched Sn, Y2O3 and ZrO2 targets, theoretical calculation of production yield, calculation of required thickness of target and suggestion of optimum reaction to produce Antimony-117 and Niobium-90.     

First-Order Formalism for the Quintom Model of Dark Energy

The present paper deals to the quintom model of dark energy. We introduce a first-order formalism, which shows how to relate the potential that specifies the scalar field model to Hubble’s parameter. Reviewing briefly the quintom scenario of dark energy, we present a general procedure to solve the equations of motion for quintom model driven by a couple scalar fields with first-order differential equations.     

Very-high-resolution tandem Fabry-Perot etalon cylindrical beam volume hologram spectrometer for diffuse source spectroscopy

We demonstrate a compact and slitless spectrometer with high resolution formed by cascading a Fabry-Perot etalon (FPE) and a cylindrical beam volume hologram (CBVH). The most significant advantage of this combined spectrometer is that we can independently encode spectral information of a diffuse beam in a 2D plane. Also, we show that in this slitless configuration we can simultaneously benefit from the advantages of both elements: the high resolution of the FPE and the large spectral range of the CBVH. Here, we report on the experimental demonstration of a spectrometer with better than 0.2 nm resolution.