Intermittent and scaling behaviour of shower particles produced in the collsions of 28Si-Em at 14.6A GeV

In the present paper an attempt has been made to study the intermittent and scaling behaviour of particles produced in the interactions of ²⁸Si-Em at 14.6A GeV. For this purpose, the method of normalized scaled factorial moments, F _q , has been utilized. We have also studied some interesting features regarding the occurence of non-thermal phase transition and scaling nature of F _q -moments.     

Approximate solution of the system of nonlinear integral equation by Newton-Kantorovich method

The Newton-Kantorovich method is developed for solving the system of nonlinear integral equations. The existence and uniqueness of the solution are proved, and the rate of convergence of the approximate solution is established. Finally, numerical examples are provided to show the validity and the efficiency of the method presented.     

Correlation of plasma electron temperature with neutron emission ina low-energy plasma focus

Correlation of neutron emission with plasma electron temperature in a low-energy (2.3 kJ) plasma focus is investigated. To determine the plasma temperature by continuum X-ray analysis, cobalt is selected as the filter, which discriminates the line radiation from the background impurities like carbon, nitrogen, and oxygen, or the copper of which plasma focus electrodes are made. For a pressure range of high neutron emission (1-4 mbar), the neutron yield is found to correlate with the plasma temperature. The highest temperature recorded is 5 keV at 2.5 mbar, the filling pressure for the highest neutron emission in this device     

Correction to: Thermal performance enhancement of shell and helical coil heat exchanger using MWCNTs/water nanofluid

Journal of Thermal Analysis and Calorimetry -     

Porous carbon as electrode material in direct ethanol fuel cells (DEFCs) synthesized by the direct carbonization of MOF-5

Porous carbon (PC-900) was prepared by direct carbonization of porous metal-organic framework (MOF)-5 (Zn₄O(bdc)₃, bdc?=?1,4-benzenedicarboxylate) at 900 °C. The carbon material was deposited with PtM (M?=?Fe, Ni, Co, and Cu (20 %) metal loading) nanoparticles using the polyol reduction method, and catalysts PtM/PC-900 were designed for direct ethanol fuel cells (DEFCs). However, herein, we are reporting PtFe/PC-900 catalyst combination which has exhibited superior performance among other options. This catalyst was characterized by powder XRD, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and selected area electron diffraction (SAED) technique. The electrocatalytic capability of the catalyst for ethanol electrooxidation was investigated using cyclic voltammetry and direct ethanol single cell testing. The results were compared with those of PtFe and Pt supported on Vulcan XC72 carbon catalysts (PFe/CX-72 and Pt/XC-72) prepared via the same method. It has been observed that the catalyst PtFe/PC-900 developed in this work showed an outstanding normalized activity per gram of Pt (6.8 mA/g Pt) and superior power density (121 mW/cm² at 90 °C) compared to commercially available carbon-supported catalysts.     

Improvement of Power Conversion Efficiency of P3HT/PCBM Polymer Solar Cell Systems by Optimization of the Process Steps

In this work, different steps involved in the fabrication of polymer solar cells were optimized using P3HT/PCBM heterojunction. Steps included spinning speed for coating of the PEDOT:PSS layer, use of filter for the PEDOT:PSS layer, spinning speed for coating of the active layer, sequence of annealing of the active layer either before or after electrode deposition, and modification of the cooling mechanism (either by cooling rapidly or slowly after heating of the active layer). Investigation of these steps led to an improvement of the power-conversion efficiency (PCE) of the polymer solar cells, especially the last step involving the change of cooling mechanism, which improved PCE by 25%.     

A highly alpha-regioselective AgOTf-catalyzed nucleophilic substitution of the Baylis-Hillman acetates with indoles

An efficient method for highly alpha-regioselective nucleophilic substitution of the Baylis-Hillman acetates with indoles catalyzed by AgOTf in high yields (72-99%) has been developed. Reductive cyclization of the substitution products furnished the azepinoindole derivatives in good yields (up to 93%).     

Effect of pre-ionization on Cu Kα emission from a small plasma focus

One of the most important factors for optimizing the X-ray emission from a plasma focus device is the use of pre-ionization before triggering the device. In this paper, we investigated the effect of pre-ionization on Cu Kα and total X-ray emission from a Mather-type plasma focus device. The Cu Kα and total X-ray yield is measured as a function of the deuterium-filling pressure by using PIN-diode detectors. The maximum Cu Kα emission is found to be 1.95 J for the α-source and 1.62 J without the α-source, with corresponding average efficiencies of 0.049 and 0.06% without and with the α-source, respectively. The maximum total X-ray yield in 4π geometry is estimated to be about 2.64 and 2.12 J, with corresponding efficiencies of about 0.08 and 0.064% with and without the α-source, respectively.     

Selective recovery of gold(III) using cotton cellulose treated with concentrated sulfuric acid

Novel utilization of cotton cellulose was developed by chemically modifying with concentrated sulfuric acid to prepare a novel kind of adsorption gel for gold. The adsorption behaviors of the gel were investigated for various metals from acidic chloride media. The gel was found to be highly selective for Au(III) over other precious and base metals tested over the whole concentration range of hydrochloric acid. The maximum adsorption capacity for Au(III) was evaluated as 6.21 mmol/g at 303 K. The amount of adsorbed Au(III) was increased with increasing temperature. A kinetic study for the adsorption of Au(III) at various temperatures confirmed the endothermic adsorption process following pseudo-first order kinetics. The activation energy was evaluated as 78.8 kJ/mol. Interestingly, it was found that the adsorbed Au(III) was reduced to elemental form which was evidenced by the clearly visible elemental gold particles which was further confirmed by means of the X-ray diffraction spectrum and optical microscope image of the gel after the adsorption of Au(III). The mechanism of Au(III) adsorption on the cotton gel and its reduction to elemental gold was proved from the results of IR-spectra. The main mechanism could be explained in terms of the coordination of Au(III) to oxygen atom of C–O–C linkage of cross linked cotton gel and to the oxygen atoms of the hydroxyl groups at C₂ and C₃ atoms of pyranose ring of cotton cellulose followed by the reduction to metallic gold. The adsorbed gold in the cotton gel can easily be recovered by incineration.     

Pulsed ion beam-assisted carburizing of titanium in methane discharge

The carburizing of titanium (Ti) is accomplished by utilizing energetic ion pulses of a 1.5 kJ Mather type dense plasma focus (DPF) device operated in methane discharge. X-ray diffraction (XRD) analysis confirms the deposition of polycrystalline titanium carbide (TiC). The samples carburized at lower axial and angular positions show an improved texture for a typical (200)TiC plane. The Williamson--Hall method is employed to estimate average crystallite size and microstrains in the carburized Ti surface. Crystallite size is found to vary from ～ 50 to 100~nm, depending on the deposition parameters. Microstrains vary with the sample position and hence ion flux, and are converted from tensile to compressive by increasing the flux. The carburizing of Ti is confirmed by two major doublets extending from 300 to 390~cm^-1 and from 560 to 620~cm^-1 corresponding to acoustic and optical active modes in Raman spectra, respectively. Analyses by scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS) have provided qualitative and quantitative profiles of the carburized surface. The Vickers microhardness of Ti is significantly improved after carburizing.