Monte Carlo simulation to reveal the copper dissolution kinetics of an ion selective electrode based on copper sulfide

The present work aims at studying copper dissolution of a Cu²⁺ ion-selective electrode based on a CuS thin film. The electrode is prepared using electrochemical deposition of CuS on a silicon substrate. The obtained film exhibits an apparent cohesive granular structure with an average grain size of about 33 μm, a small porosity content (<4%) and a thickness of about 7.48 μm. The Cu²⁺ electrochemical response shows a nearly Nernstian behavior in the range of pCu 6–1. The copper dissolution is experimentally studied in a wide pH range. In order to quantitatively predict copper mass dissolution, an original numerical model is developed based on Monte Carlo simulation. Our main hypothesis is based on dissolution probability that triggers the whole dissolution process through solution/electrode surface exchanges. Several probability forms are suggested accounting for the real observed electrochemical kinetics. The experimental results show that, under a low pH, the dissolution process severely leads to the consumption of large material. Moreover, our predictions suggest a dissolution profile as a two-stage process irrespective of pH. Our numerical model is able to fit correctly the observed kinetics considering an exponential probability form under all pH conditions.     

Some transparent semi-conductor metal oxides: Comparative investigations in terms of Wemple–DiDomenico parameters, mechanical performance and Amlouk–Boubaker opto-thermal expansivity

Wemple–DiDomenico model parameters for oxides thin layers (Sb₂O₄, SnO₂, ZnO and WO₃) have been determined from experimental measurement of reflection R(λ) and T(λ) transmission ratios within the Ultraviolet–Visible–Near-Infrared (UV/VIS/NIR) domain (300–1800 nm). This study allowed deducing ε₁(λ) and ε₂(λ) expressions. Exploitation of results concerning their variations enabled estimating the plasma pulse ω_p, the relaxation time τ, the dielectric constant ε_∞ and susceptibility χ_e. Furthermore, opto-thermal and mechanical investigations have been carried out and discussed relatively to the already established optical and thermal characteristics.     

Effect of Oxygen on Methane Steam Reforming in a Sliding Discharge Reactor

Hydrogen‐rich gas can be efficiently produced in compact plasma reformers by the conversion of a variety of hydrocarbon fuels, including natural gas and gasoline. This article describes experimental and modeling progress in plasma reforming of methane using a sliding discharge reactor (SDR). Experiments have been carried out in a compact device operating at low consumed power (1–2 kW). Previous studies of methane steam reforming using a SDR at atmospheric pressure show promising results (H₂ concentration higher than 55 %). In order to study the effect of oxygen on the methane conversion and thus hydrogen production, a small amount of oxygen in the range of 7–20 % was added to the CH₄‐H₂O mixture. An unexpected result was that under our experimental conditions in the SDR oxygen did not have any influence on the methane conversion. Almost the totality of added oxygen is recovered intact. Moreover, part of the H₂ produced was transformed into water by reaction with O₂. A model describing the chemical processes based on classical thermodynamics is also proposed. The results indicate that the reactor design has to be improved in order to increase conversion and hydrogen production.     

Heterogeneous reaction induced by the piston effect in supercritical binary mixtures

It is now well established that the large compressibility of supercritical fluids is responsible for the strong enhancement of the thermo-acoustic heating, leading to the speeding up of the heat transport thanks to the piston effect instead of the expected slowing down. We show in this paper, through numerical simulations, that the hydrodynamics behavior of supercritical fluids also couples with the critical behavior of the solubility of solids to cause the release of a heterogeneous reaction at solid surfaces in dilute binary supercritical mixtures.     

Near-room-temperature mid-infrared quantum well photodetector

We demonstrate InGaAs mid-infrared quantum well infrared photodetectors (MIR PV-QWIPs) that enable cost-effective mature GaAs-based detection and imaging technologies, with exceptional material uniformity, reproducibility, and yield, over a large area, with high spectral selectivity, innate polarization sensitivity, radiation hardness, high detectivity, and high speed operation at TEC temperatures without bias.     

Evaluation of wall boundary condition parameters for gas–solids fluidized bed simulations

Wall boundary conditions for the solids phase have significant effects on numerical predictions of various gas–solids fluidized beds. Several models for the granular flow wall boundary condition are available in the open literature for numerical modeling of gas–solids flow. A model for specularity coefficient used in Johnson and Jackson boundary conditions by Li and Benyahia (Li and Benyahia, AIChE J. 2012;58:2058–2068) is implemented in the open‐source CFD code‐MFIX. The variable specularity coefficient model provides a physical way to calculate the specularity coefficient needed by the partial‐slip boundary conditions for the solids phase. Through a series of two‐dimensional numerical simulations of bubbling fluidized bed and circulating fluidized bed riser, the model predicts qualitatively consistent trends to the previous studies. Furthermore, a quantitative comparison is conducted between numerical results of variable and constant specularity coefficients to investigate the effect of spatial and temporal variations in specularity coefficient. Published 2013 American Institute of Chemical Engineers AIChE J, 59: 3624–3632, 2013     

Characterisation and quantification of phenolic compounds of extra-virgin olive oils according to their geographical origin by a rapid and resolutive LC–ESI-TOF MS method

The phenolic compounds present in seven samples of olive fruits were analysed by a rapid and resolutive LC–ESI-TOF MS method. All samples were collected during the normal picking period for olive oil production, in central and south Tunisia, and were obtained from the Oueslati variety cultivated in different olive growing areas.     

Road network layout based multi-hop broadcast protocols for Urban Vehicular Ad-hoc Networks

Wireless Networks - In recent years, the decentralized wireless Vehicular Ad hoc Networks (VANETs) have emerged as a key technology for Intelligent Transportation Systems&nbsp;(ITS). The need...     

Effect of printing temperature on microstructure,thermal behavior and tensile properties of 3D printed nylon using fused deposition modeling

The present investigation aims at the thermal conditions for the printability of nylon using fused deposition modeling (FDM). Dog-bone like specimens are manufactured under two printing temperatures to measure the tensile performance of 3D printed nylon with respect to the feedstock material properties. Both Scanning Electron Microscopy (SEM) and X-ray micro-tomography analysis are conducted to shed more light on the microstructural arrangement of nylon filaments. Finite element computation based on microstructural implementation is considered to study the main deformation mechanisms associated with the nylon filament arrangement and the process-induced porosity. The results show a narrow temperature range for printability of nylon, and a significant influence of the printing temperature on the thermal cycling, porosity content and mechanical performance. With the support of both numerical and experimental results, complex deformation mechanisms are revealed involving shearing related to the filament sequencing, compression at the junction points and tension within the raster and the frame. All these mechanisms are associated with the particular and regular arrangement of nylon filaments.     

Extension of Einstein's Law for Power‐Law Fluid to Describe a Suspension of Spherical Particles: Application to Recycled Polymer Flow

In this work, Einstein's equation is extended considering a power‐law suspending fluid without any Newtonian approximation. To validate the developed equation, an experimental setup is carried out. Polypropylene (PP) and polyethylene (PE) are injected at different volume fractions. The pressure drops measured in a cylindrical die are analyzed. The results show that the developed relationship allows better prediction of the viscosity of PP/PE blends compared to existing laws. During the recycling of PP, some pollutants are likely to be present in the polymer, mostly PE which tends to form a heterogeneous melt with PP. At low volume fractions, PE disperses mostly as solid spheres in PP due to its higher viscosity, but the viscosity of the PP/PE mixtures is hard to predict. Several studies have derived equivalent viscosity equations for dispersed spherical suspensions in shear‐thinning polymers. Nevertheless, these equations mainly refer to Einstein's equation for suspended spheres in Newtonian fluids. POLYM. ENG. SCI., 59:E387–E396, 2019. © 2019 Society of Plastics Engineers