Effect of Fe2O3 as an accelerator on the reaction mechanism of Al–TiO2 nanothermite system

Thermite reactions between aluminum and metal oxides could lead to the formation of intermetallic matrix composites used in high-temperature industrial applications. Thermite reaction in Al–TiO₂ system needs a considerable amount of energy to take place by mechanochemical or by the combustion synthesis (CS) method due to the low amount of reaction enthalpy in Al–TiO₂ system. In this study, Fe₂O₃ was chosen as a accelerator for this system, to generate a high amount of heat which could be released between Fe₂O₃ and Al, leading to a more convenient reaction between Al and TiO₂ in the CS process. The results of XRD, SEM, and DSC analyses indicated that both the mechanical activation of Al–TiO₂ system in a high-energy ball mill and the Fe₂O₃ addition led to considerable effects of reduction in the reaction temperature and increase in the reaction intensity in Al–TiO₂ nanothermite system. Finally, it was shown that Fe₃Al intermetallic compounds as well as γ-AlTi and alumina phases in the final products were formed after the CS of the milled powders.     

Parameter evaluation,kinetics, and energy consumption for Cr(VI) photocatalytic reduction under mild conditions

Photocatalytic reduction of hexavalent chromium, Cr(VI), ions in aqueous solutions was studied using remarkably low doses of commercial titania nanoparticles at conventional temperature range of 15–45 °C. A direct imposed irradiation photo-reactor, equipped with ultrasonic source was utilized. Design of experiments, correlating and process optimization were performed using central composite design of response surface methodology. Accordingly, a reduced quadratic expression was developed to predict the reduction efficiency as a function of involved parameters. Analysis of variance shows the agreement of the provided model with experimental data. At the found optimum conditions of titania concentration: 33.1 mg/L, pH: 2.50, temperature: 36 °C and reaction time: 120 min; 81 % efficiency was achieved for reduction of initial 5 mg/L of Cr(VI). The process revealed proceeding through parallel branches of photolysis and photocatalysis, and only UV irradiation was promising for reaction progress. Based on differential method of analysis, the relevant kinetic model, jointed with the Arrhenius equation, was introduced. Energy (electrical and thermal) consumption evaluations revealed that treatment at higher temperatures provides a significant cost reduction. Meantime, a criterion was proposed for a more valid assessment of photocatalytic processes.     

A comparative study of a new heuristic based on adaptive memory programming and simulated annealing: The case of job shop scheduling

In this study, a general framework is proposed that combines the distinctive features of three well-known approaches: the adaptive memory programming, the simulated annealing, and the tabu search methods. Four variants of a heuristic based on this framework are developed and presented. The performance of the proposed methods is evaluated and compared with a conventional simulated annealing approach using benchmark problems for job shop scheduling. The unique feature of the proposed framework is the use of two short-term memories. The first memory temporarily prevents further changes in the configuration of a provisional solution by maintaining the presence of good elements of such solutions. The purpose of the second memory is to keep track of good solutions found during an iteration, so that the best of these can be used as the starting point in a subsequent iteration. Our computational results for the job shop scheduling problem clearly indicate that the proposed methods significantly outperform the conventional simulated annealing.     

Study of the Effects of N Fertilization and Plant Density on the Essential Oil Composition and Yield of Cuminum cyminum L. Seeds by HS–SME

Headspace-solvent microextraction (HS–SME) with sample ultrasound irradiation was successfully used for the study of the influence of nitrogen fertilization and plant density on the essential oil yield and composition of cumin (Cuminum cyminum L.) seeds. The components were collected into a single microdrop of n-heptadecane and directly injected into a GC–MS injection port for analysis. A simplex method was used for fast optimization of the extraction parameters. The experiments were executed as split-plot based on randomized complete block design. Nitrogen fertilization as the main factor (in four levels) and plant density as subsidiary factor (in three levels) were applied. It was shown that the total GC peak areas of the HS–SME extract, is proportional to the essential oil yield of the cumin seeds obtained by a hydrodistillation method. Furthermore, similar trends in the concentrations of cuminaldehyde and most other volatile components were obtained by the two methods.     

Nanosized silver–palm pollen nanocomposite,green synthesis,characterization and antimicrobial activity

Palm pollen (PP) has been widely used in nutrition, pharmaceutical and cosmetic industries. In the present study, we explored the potential of PP in the synthesis of a silver nanoparticle (Ag NP). PP was used as both reducing and stabilizing agent. The Ag/PP nanocomposite was examined by field emission electron microscopy, X-ray diffraction, Fourier transform infrared (FT-IR) spectroscopy, ultraviolet spectroscopy and zeta potential measurement. The biosynthesized NPs showed surface plasmon resonance centered at 425 nm with an average particle size measured to be 23 nm and a zeta potential of ?30.9 mV. Prominent FT-IR signals were obtained and ascribed to phenolic and carbohydrate compounds involved in the formation of the Ag NPs, and proteins which participated in stabilization of the Ag NPs. The biologically synthesized Ag NPs were found to be extremely effective against E. coli (13.8 ± 0.25 mm) with a minimum inhibitory concentration of 20 µg/mL. Thus, such biosynthesized Ag NPs can be used in medicinal applications.     

用于电催化氧化甲醛的新型Ni(OH)2-X/CPE负载电极的制备

采用一种简易的方法制备了新型Ni(OH)2-X/CPE电极,并将其用于电催化氧化甲醛反应.采用扫描电镜和能量散射谱对所制Ni(OH)2-X/CPE电极进行了表征,并运用循环伏安法、电化学阻抗谱和计时电流法考察了该电极的电化学性能.结果表明,该Ni(OH)2-X/CPE电极对甲醛氧化表现出高电催化活性,这归功于X具有纳米孔结构和大的比表面积.电子传递系数和催化反应速率常数分别为0.7和6.1×104 cm3/(mol·s).该电极对甲醛氧化具有高而稳定的电催化活性,且制备重复性高,有望应用于燃料电池中.     

Determination of Epinephrine in Pharmaceutical Formulation by an Optimized Novel Luminescence Method Using CdS Quantum Dots as Sensitizer

In this article, a novel chemiluminescence method using water-soluble CdS quantum dots (QDs) as sensitizers is proposed for the chemiluminometric determination of epinephrine. The method is based on the quenching effect of epinephrine on the chemiluminescence emission generated by the mixing of CdS quantum dots (QDs) with hydrogen carbonate (HCO₃ ^-) in the presence of hydrogen peroxide (H₂O₂) in an alkaline medium. The optimization of variables influencing the chemiluminescence response of the method has been carried out by using experimental design. Under the optimal conditions, there is good linear relationship between the relative chemiluminescence intensity and the concentration of epinephrine over the range of 5?×?10^?9–1?×?10^?6?molL^?1 with a 3σ detection limit of 5?×?10^?11?molL^?1. The method has been successfully applied to the determination of epinephrine in pharmaceutical formulation and the recovery test was done in human urine.     

Facile synthesis of highly fluorescent Boranil complexes

Complexation of a large variety of Anils (aniline-imines) with boron(III) precursors provides stable Boranils, some of which have been structurally characterized. Analysis of their optical properties reveals that the fluorescence stems from an intraligand charge transfer (ILCT) state with the best quantum yields reaching 90%. Chemistry on the Boranils allows grafting of photoactive modules acting as energy antennae for borondipyrromethene (Bodipy) and subphtalocyanine (SubPc) fluorophores.     

Eco‐friendly and Efficient Synthesis of 2,3‐Dihydroquinazolin‐4(1H)‐ones

A simple and facile method for the synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones through the direct cyclocondensation of one‐pot three‐component cyclocondensation of isatoic anhydride, ammonium acetate (or primary amines) and aldehydes; and anthranilamide and aldehydes using silica supported ferric chloride (SiO₂‐FeCl₃) as catalyst under solvent‐free conditions is described.