The Inhibition Performance of trans-Cinnamaldehyde as a Green Compound for Mild Steel in Acidic 1 M HCl Medium: Correlation between Experimental and Theoretical Studies

Protection of Metals and Physical Chemistry of Surfaces - Corrosion inhibition propriety of (2E)-3-phenylprop-2-enal, known as trans-cinnamaldehyde (TCA) for mild steel in 1 M HCl medium was...     

Electrochemical properties of the MmNi3.55Mn0.4Al0.3Co0.4Fe0.35 compound

In this paper, the electrochemical properties of the MmNi_3.55Mn_0.4Al_0.3Co_0.4Fe_0.35 alloy used as a negative electrode in Ni–MH accumulators, have been investigated by different electrochemical methods such as cyclic voltammetry, chronopotentiometry, chronoamperometry and electrochemical impedance spectroscopy. The experimental results indicate that the discharge capacity reaches a maximum value of 260 mAh g⁻¹ after 12 cycles and then decreases to about 200 mAh g⁻¹ after 70 cycles. The value of the mean diffusion coefficient D_H, determined by cyclic voltammetry, is about 3.44 × 10⁻⁹ cm² s⁻¹, whereas the charge transfer coefficient , determined by the same method, is about 0.5 which allows us to conclude that the electrochemical reaction is reversible. The hydrogen diffusion coefficients in this compound, corresponding to 10 and 100% of the charge state, determined by electrochemical impedance spectroscopy, are, respectively, equal to 4.15 × 10⁻⁹ cm² s⁻¹ ( phase) and 2.15 × 10⁻⁹ cm² s⁻¹ (β phase). These values are higher, for the phase and less, for the β phase, than the mean value determined by cyclic voltammetry. We assume that this is related to the number of interstitial sites susceptible to accept the hydrogen atom, which are more numerous in the phase than in the β phase. The chronoamperometry shows that the average size of the particles involved in the electrochemical reaction is about 12 μm.     

Kinetic Monte Carlo and density functional study of hydrogen diffusion in magnesium hydride MgH2

In this work, we propose a model to investigate the hydrogen storage ab/desorption kinetic properties for the pure MgH₂ using Kinetic Monte Carlo (KMC) simulations. To do such computations, the activation energies for different elementary processes have been estimated. Moreover, the different thermodynamical quantities of interest are determined by performing the ab-initio calculations. Then, we discuss the hydrogen diffusion in magnesium hydride (such as adsorption, diffusion and desorption). More precisely, we study the effect of each elementary mechanism on the diffusion that we characterize through the density distribution of hydrogen atoms including filling ratios, diffusion time, temperature and pressure. Among others, we show that all elementary mechanisms are needed to reproduce a behavior of ab/desorption which correlates well with the experimental results reported in literature. In particular, at high temperature and pressure, the results of simulations indicate that the studied material involves slow kinetics.     

Fabrication,microstructure and mechanical properties of novel bulk binderless (Ti0.8Zr0.2)C carbides prepared by mechanical alloying and spark plasma sintering

Nanocrystalline (Ti_0.8Zr_0.2)C powder consisting in grains of about 200 nm in diameter obtained by mechanical alloying was sintered by a spark plasma sintering (SPS) process without the addition of any binder phase. The microstructure, Vickers micro hardness and density in relation to the sintering time and temperature are carefully described. The most suitable sintering condition under pressure of 50 MPa is 1650 °C for 5 min. In this sintering condition, the hardness can reach 2760 Hv and the relative density can reach 98%.     

Influence of mechanical alloying on Ti3SiC2 formation via spark plasma sintering technique from Ti/SiC/C powders

Ti₃SiC₂ was elaborated by two different methods: (i) Spark plasma sintering of 5Ti/2SiC/C powders and (ii) mechanical alloying of powders followed by Spark plasma sintering. The results showed that mechanical alloying was not advantageous for pure Ti₃SiC₂ formation but it can significantly improve the density of the obtained bulk material via the particles refinement as well as the microhardness by increasing the TiC content. It was found that the relative density was increased up to 98.58% for the sintered mechanically alloyed sample whereas it was not more than 96.04% for the sintered 5Ti/2SiC/C starting powders. The Vickers microhardness measured for both bulk samples demonstrates a high improvement for the previously mechanically alloyed powder mixture, as it was of about 1282 Hv and only 581.2 Hv for the alloy obtained from 5Ti/2SiC/C starting powders.     

Study by AES and EELS spectroscopies of antimony and phosphorus evaporated on massive indium and on cleaned InP

In this paper, we give some results related to interaction mechanism between the elements V such as antimony or phosphorus with the metal indium. We used both powerful spectroscopy methods the Auger electron spectroscopy (AES) and the electron energy loss spectroscopy (EELS) for which the spectra were recorded in direct mode N(E). The antimony was evaporated on pure In metal or on cleaned InP surface involving the In metal because of its cleaning by the argon ion bombardment at low energy 300 eV. The antimony flow composed of Sb₄ species arrived with a thermal energy on the In metal surface. Such an energy was sufficient to their diffusion into the In matrix because of the low melting point of In metal (123 °C). A nucleation phenomenon occurred between Sb₄ and the In metal to form small islands of antimony metal in bulk. Further antimony evaporation enabled to increase the size of these islands towards the surface. However, the antimony evaporated on cleaned InP reacted chemically with the In metal distributed on the InP surface to form a thin layer of InSb. The inner stoichiometric layers of InP and the size of Sb₄ species and also the stability of InP versus the temperature impeded the interdiffusion phenomenon of antimony to occur deeply into the InP matrix. The InSb layer played the role to stabilise the surface of the InP compound versus the heating at 450 °C and the electron irradiation of 4 KeV energy. But, the phosphorus evaporation on In metal or on cleaned InP led to form chemical bonds InP. The phosphorus flow included chemical species P and P₂ with a thermal energy able to stimulate the chemical reactivity process between indium and phosphorus to form the InP compound.     

Characterization and Cheese-Making Properties of Rennet-Like Enzyme Produced by a Local Algerian Isolate of Aspergillus niger

An ochratoxin free extracellular acid protease was produced by solid state cultivation of Aspergillus niger FFB1. The purified enzyme (48.7 kDa) showed an optimal milk clotting activity at pH 5.5 and 45°C in the presence of 0.01 M CaCl₂. The enzyme was stable at least 24 h at 35°C in the pH range of 5.5–7.0. Thermal denaturation started above 45°C. Fresh cheese manufactured with reconstituted cow milk and the purified enzyme showed similar basic characteristics (pH 4.5, acid taste, white color) as marketed cheeses obtained with calf rennet. This emphasizes the value of exploiting local biological resources for value added food processing in developing countries.     

Thermomechanical approach for the modeling of oblique machining with a single cutting edge

This article aims to predict performances of oblique machining with a single cutting edge. A thermomechanical approach for the modeling of oblique cutting with a single cutting edge is proposed. A good agreement was found between predicted and experimental data. New rules were established to determine experimentally the average friction coefficient and chip flow angle at the rake face. The computation algorithm permits to predict all thermomechanical parameters such as cutting forces, cutting temperatures, and chip geometry. Besides, all predicted oblique machining parameters are mainly controlled by the Po-criterion, which is defined as the ratio of tool–chip contact length to uncut chip thickness.     

Preparation of poly (N,N‐dimethylaminoethyl methacrylate) (PDAEM) membranes: Application for water purification

The present work concerns a development of new membranes for performing ions separation. These membranes were prepared by solution casting followed by solvent evaporation, using a commercial cellulose triacetate (CTA), synthesized poly (N,N‐dimethylaminoethyl methacrylate), macrocylic polyethers (15‐crown‐5 and Dibenzo‐24‐crown‐8) as carrier and dioctylphtalate as plasticizer. Different Polymer Inclusion Membranes were characterized using physical and chemical techniques as well as Fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy. Transport of lead and cadmium in aqueous solution has been studied using these systems. The selective separation of these membranes is accomplished by the presence of specific compounds, called carriers, in the membrane phase. The carriers are responsible to facilitate the transport of the target component across selective membranes. The influence of the membrane nature has been studied using some supports of different physical characteristics. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46592.