Equilibrium, kinetic and thermodynamic studies of mercury adsorption on almond shell

The application of almond shell as a low cost natural adsorbent to remove Hg(2+) from aqueous solution was investigated. Batch experiments were carried out to evaluate the adsorption capacity of the material. The chemical and physical parameters such as pH, sorbent amount, initial ion concentration, and contact time were optimized for the maximum uptake of mercury onto the solid surface. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models, and the experimental data were found to fit the Langmuir model rather than the Freundlich. The maximum adsorption capacity obtained from the Langmuir isotherm was 135.13 mg/g. A kinetic study was carried out with pseudo-first-order and pseudo-second-order reaction equations and it was found that the Hg(2+) uptake process followed the pseudo-second-order rate expression. The thermodynamic values, ΔG(0), ΔH(0) and ΔS(0), indicated that adsorption was an endothermic and spontaneous process. The potential of this material for mercury elimination was demonstrated by efficient Hg(2+) removal from a synthetic effluent.     

Centimeter‐Scale and Visible Wavelength Monolayer Light‐Emitting Devices

Monolayer 2D transition metal dichalcogenides (TMDCs) have shown great promise for optoelectronic applications due to their direct bandgaps and unique physical properties. In particular, they can possess photoluminescence quantum yields (PL QY) approaching unity at the ultimate thickness limit, making their application in light‐emitting devices highly promising. Here, large‐area WS₂ grown via chemical vapor deposition is synthesized and characterized for visible (red) light‐emitting devices. Detail optical characterization of the synthesized films is performed, which show peak PL QY as high as 12%. Electrically pumped emission from the synthetic WS₂ is achieved utilizing a transient‐mode electroluminescence device structure, which consists of a single metal–semiconductor contact and alternating gate fields to achieve bipolar emission. Utilizing this aforementioned structure, a centimeter‐scale ( ≈ 0.5 cm²) visible (640 nm) display is demonstrated, fabricated using TMDCs to showcase the potential of this material system for display applications.     

Radiation from a small monopole in a uniaxially anisotropic plasma

The radiation field of a small monopole over a ground plane covered with a uniaxially anisotropic plasma with an arbitrary inclination of the optical axis is studied. A steepest descent evaluation of the field integrals has been performed under the elliptic condition, and some calculated power patterns have been studied in comparison with those for a small dipole in an unbounded uniaxially anisotropic plasma. For an arbitrary inclination of the optic axis, considerable differences between the power patterns of the two configurations have been observed. Lateral waves and concentrated field regions are found to occur from mode coupling at the surface of the ground plane.     

Bandgap Tuning of Sm and Co Co-doped BFO Nanoparticles for Photovoltaic Application

Multiferroic \(BiFeO_3\) (BFO) with bandgap energy (\(E_g\)) between 2.2 eV to 2.7 eV is a potential candidate for photovoltaic (PV) application. However, the efficiency of BFO based PV solar cells is reportedly still too low (less than 2%) to be used for practical applications. Reducing \(E_g\) of BFO without compromising the ferroelectric properties is a big challenge to the scientific community to obtain power conversion efficiencies beyond the maximum value of 26.6% reported in general for silicon based hetero-structure PV solar cells. In this context, samarium (Sm) and cobalt (Co) co-doped BFO (\(Bi_{0.9}Sm_{0.1}Fe_{0.9}Co_{0.1}O_3\)) nanoparticles were synthesized using the sol-gel method. X-ray diffractometry was employed to determine the structure of synthesized nanoparticles. A well-defined crystalline structure of co-doped BFO nanoparticles was confirmed. Field emission scanning electron microscopy was carried out to study grain morphology of synthesized nanoparticles. Sm and Co dopants have been shown to reduce grain size significantly from 68.3 nm to 18.5 nm. An UV-Vis-NIR spectrophotometer was used to measure diffuse reflectance to calculate \(E_g\). A significant reduction of \(E_g\) down to 1.50 eV of co-doped BFO compared to undoped and or single doped counterpart has been manifested.     

Robust consensus of unicycles using ternary and hybrid controllers

This paper presents consensus of the orientations and average positions for a group of unicycles using ternary and hybrid controllers. The decentralized controllers designed to reach consensus of the average positions take only values in the set {?1,0,+1}. In addition, a hybrid controller is introduced to control the orientations. Finite‐time practical consensus of the average positions is proven despite the simple ternary control laws together with asymptotic consensus of the orientations. Furthermore, the consensus problem is studied in the presence of matched input disturbances that are locally rejected using an internal‐model‐based controller. The analysis is performed in a hybrid framework. Simulation results illustrate the effectiveness of the design. Copyright © 2017 John Wiley & Sons, Ltd.     

Intestinal broiler microflora estimation by artificial neural network

Microflora population of poultry was affected by various factors. Many methods and techniques were developed to study microflora population. But, most of them confronted some problems. Moreover, being costly, laborious, and time-consuming made it impossible to measure microflora population several times. In this study, we tried to estimate intestinal microflora population using artificial neural network (ANN). Lactic acid bacteria were used as model of microflora population. Time and lactic acid bacteria were used as input and output variables, respectively. The best model of ANN was determined based on coefficient of determination, root mean square error, and mean absolute error criteria. The results of current study have shown that ANN is appropriate, cheap, and reliable tools to estimate intestinal microflora population (lactic acid bacteria) of broiler at different ages.     

Correlation between localized strain and damage in shear-loaded Pb-free solders

A digital image correlation (DIC) algorithm was employed to measure microscopic strain-field evolution in shear-loaded model solder interconnections made out of a number of Sn-based alloys. Four different solder alloys studied were Sn–36Pb–2Ag, Sn–3.8Ag–0.7Cu (SAC), Sn–3.3Ag–3.82Bi, and Sn–8Zn–3Bi. The measured strain fields were correlated with damage observed at the scale of the sample, and at microscopic length scales.Local strain differs significantly from applied global strain and has been shown to depend on the geometry of the samples as well as the microstructure (on a grain level) of the solder.Strain fields in all solder interconnections were found to localize near but not at the solder–substrate interface and along grain boundaries in the solders. The eventual failure path as observed on the scale of the sample (parallel to the two solder–substrate interfaces with a cross-over from one interface to the other somewhere in the connection) showed a good correlation with measured strain fields in all interconnections.In contrast to the similarity on a macroscopic scale, on a microscopic scale the failure mechanisms were observed to be material specific.     

Technical-economic analysis of electric furnaces for gas nitriding

Metal Science and Heat Treatment -     

Numerical study of film cooling effectiveness of a gas turbine blade under variable blowing ratio and turbulence intensity

The present paper investigates a three-dimensional simulation of film cooling on a C3X turbine blade with a single hole at a suction surface. The Reynolds averaged Navier–Stokes approach with k–ε realizable turbulence model and enhanced wall function are used for the numerical simulation. To simulate the jet flows, the length of the jet input approximately 4.5 times the diameter of the hole is added to the geometry so that the jet outlet flow is closer to the actual condition. The density ratio of the cooling flow to the mainstream flow is assumed about 2. The numerical results in four blowing ratios of 0.5, 0.7, 1.0, and 1.4, and at the low turbulence intensity (0.02%), and high turbulence intensity (12%) are extracted and compared for the turbine blade with a single hole. The results show that the turbulence intensity has a dual effect on the film cooling effectiveness and a higher blowing ratio increases the strength of the jet against the cross-flow. Moreover, it is illustrated that the distribution of the film cooling effectiveness in higher blowing ratios and high turbulence intensity is more uniform than the low blowing ratios and low turbulence intensity.