Synthesis,characterization and biological properties of mixed ligand complexes of cobalt(II/III) valproate with 2,9‐dimethyl‐1,10‐phenanthroline and 1,10‐phenanthroline

The synthesis of mononuclear cobalt(II/III) complexes with two different ligands (complex 2: [Co(valp)₂(2,9‐dmp)] and complex 3: [Co(valp)₂(H₂O)(1,10‐phen)]) was investigated and the characterization of both complexes was achieved using IR, UV–Vis, and single crystal X‐ray diffraction. Using single crystal X‐ray diffraction, the crystal structure of each of the complexes was determined. Additionally, the biological activity of these complexes was studied in five gram‐positive and four gram‐negative bacterial strains. Whereas in all gram‐negative bacteria tested, cobalt valproate complexes did not show any anti‐bacterial activity, both complexes had effects on gram positive bacteria. Complex 2 demonstrated good anti‐bacterial activity against all gram‐positive bacteria with inhibition zone diameter (IZD) ranging between 15–28 mm. Complex 3 exhibited low inhibition activity against all gram‐positive bacteria except E. faecalis with IZD ranging between 11.3–13.7 mm. Moreover, as an indication of its uses as industrial catalyst, the rate of bis(p‐nitrophenyl) phosphate (BNPP) hydrolysis when catalyzed by these complexes was measured at different temperatures, concentrations and pH. Complex 2 proved to be a better catalyst to induce the hydrolysis of BNPP.     

Modelling of CO2 laser welding of magnesium alloys

Laser welding is an important joining process for magnesium alloys. These materials are being increasingly used in different applications such as in aerospace, aircraft, automotive, electronics, etc. To date, carbon dioxide (CO₂) neodymium-doped yttrium aluminum garnet (Nd:YAG) and the high power diode laser have been extensively used to investigate the weldability of magnesium alloys. The present work describes an analytical thermal model for the weldability of magnesium alloys (WE43) using an industrial (CO₂) laser source. The main target of the project is to present to the industrial community a simple and rapid tool for the determination of the penetration depth and the bead width as a function of both the incident laser power and welding speed. The proposed model is based on the Davis thermal approach, largely considered for the characterization of the average radius of the liquid zone, aiming at predicting the joint shape. Moreover, since during the welding process considered in this study, a protecting gas is used to avoid joint oxidation, both thermal convection and radiation phenomena in the welding area have been estimated and introduced in our model for a better characterization of the welding process. The obtained results have been compared to the experimental ones and a satisfactory correlation has been observed, indicating the reliability of the model developed in this study.     

A proposed unsteady bioconvection model for transient thin film flow of rate-type nanoparticles configured by rotating disk

Journal of Thermal Analysis and Calorimetry - The revolution in nanotechnology has made new developments toward enhancement of energy resources which play a substantial role in the growth of...     

Facile synthesis of Cu-LDH with different Cu/Al molar ratios: application as antibacterial inhibitors

Research on Chemical Intermediates - A range of Cu-LDHs has been synthesized by co-precipitation using metal nitrate precursors and sodium carbonate under varying molar ratios Cu/Al...     

M/M/1 Retrial Queue with Collisions and Transmission Errors

Methodology and Computing in Applied Probability - In this paper, an M/M/1 retrial queue with collisions and transmission errors is considered. The collision may occur when a primary arriving...     

Problemes aux limites pour l'equation de boltzmann: existence globale de solutions

This work is concerned by the initial and boundary value problem for the Boltzmann equation. Existence in the large and asymptotic behaviour results are proved for small data and general reemission laws. The colisional kernel satisfies the cut—off angular hypothesesand, the intermolecular potential is such that 7/3 <s≤∞ for the Dirichlet case and 7/3 <s≤5for the general case

Mot—clés: Equation de Boltzmann— Problèmes aux limites intérieurs et extérieurs — Gaz raréfiés —Condition aux limites de Dirichlet— Conditions aux limites non lináeaires— Existence globale de petites solutions     

Assessment of the intrinsic interactions of mesoporous silica with carbon dioxide

Three mesoporous silica, SBA-16, SBA-15 and MCM-41, with different structures and porosities were synthesized via a hydrothermal method and their interactions with carbon dioxide (CO₂) were investigated through thermal programmed desorption (TPD) and differential scanning calorimetry. TPD measurements provided precise assessments of the intrinsic affinity towards CO₂, without the influence of moisture. All silica materials were found to exhibit intrinsic affinity towards carbon dioxide, but the surface basicity, expressed in terms of retained CO₂ amount, is markedly influenced by increases in pore size and framework structures. SBA-15 displayed the highest CRC values, explained in terms of larger pore size, lower numbers of acidic out-of plane Si–OH and higher numbers of much less acidic in-plane silanols. These findings provide valuable information for a better understanding of the role of the silica structure in the intrinsic basicity, prior to further modifications for improving the affinity towards CO₂ or merely for catalysis purposes involving CO₂ as reagents, intermediates or products.