Recycling of Iron Sintered Wastes Into Nanoparticles Barium Hexaferrite and Zinc-Ferrite Glass-Ceramics

About 25 % of iron oxides in the sintering process are wastes. In this paper, sintered waste (SW) was used as a source of iron oxides to prepare both hard and soft magnetic glass-ceramics via a melting-quenching technique. About 71 % by wt. of sintered waste was used for preparing soft magnetic glass-ceramics, while ～46 % was used for preparing hard magnetic glass-ceramics. The comparison between ferrimagnetic glass-ceramics prepared from pure chemicals and that from sintered waste before and after heat treatment was studied. X-ray diffraction shows crystallization of both hematite and Zn-ferrite phases in sintered waste while pure Zn-ferrite or Ba-hexaferrite phases were crystallized in soft magnetic and hard magnetic glass-ceramics, prepared from sintered waste, respectively. Transmission electron microscopy determined the crystalliza- tion of nano-particles ～20 nm and <15 nm for soft and hard magnetic glass-ceramics respectively. Vibrating scanning magnetometry revealed a significant increase in saturation magnetization from ～26 emu/g for sintered waste to ～44 emu/g in soft magnetic glass ceramics while it decreased to ～12 emu/g for hard magnetic glass-ceramics.     

Study of ceramic ultrafiltration membrane support based on phosphate industry subproduct: Application for the cuttlefish conditioning effluents treatment

The development and the characterisation of a new support for ultrafiltration membranes prepared from the mud of the hydro cyclone laundries of phosphate are presented. The choice of this material is based mostly on its low cost (considering its abundance in the Tunisian ores). Indeed, the use of this material for membrane preparation allows a good management of this subproduct which represents a major problem in phosphate transformation industry due to the resulting environmental pollution.Paste from the mud of the hydro cyclone laundries of phosphate was extruded and heated at 900 °C to produce a porous tubular support having an average pore diameter and a porosity of about 1.05 μm and 39%, respectively. The properties regarding to mechanical and chemical resistances are very interesting. The deposition of the ultrafiltration layer from zirconium material was performed by slip-casting method. The heating treatment at 700 °C leads to an average pore size of 5 nm. The determination of the water permeability shows a value of 86 l/h m² bar. This membrane can be used for crossflow ultrafiltration. The application of the cuttlefish effluent treatment shows an important decrease of turbidity, inferior to 1.5 NTU and chemical organic demand (COD), retention rate of about 60%. So, it seems that this membrane is suitable to use for wastewater treatment.     

Reactions with substituted acrylonitriles: A novel Synthesis of Polysubstituted Pyrimidines

3-Arylacrylonitrile-2-thiocarboxamides ( 1a – d ) reacted with S-methylisothiourea to give 4-amino-6-aryl-2-methylmercaptopyrimidine-5-carbonitriles ( 3a – d ). The products 3a – d were also obtained via the reaction of 3-arylacrylonitrile-2-carbonitriles ( 4a – d ) with S-methylisothiourea. Compounds 4a – d reacted with thiourea and urea to yield 4-amino-6-aryl-2-mercaptopyrimidine-5-carbonitriles ( 5a – d ) and 2-hydroxy derivatives ( 5e – h ) respectively. Oxidation of 5a – d with hydrogen peroxide afforded 5e – h . 5a – h were readily alkylated with methyl iodide to give 3a – d .     

Heat treatment of cream: A model of the butter texture response in relation with triglyceride composition

The effects of thermal treatments on butter texture are known and have been used since 1935 on an industrial scale, but without fundamental knowledge. Butter composition influences firmness, as observed through seasonal and regional variations. Experiments were carried out at 15°C by using a cone penetrometer and an industrial testing machine. A significant correlation between heat treatment efficiency and some prevalent triglycerides and fatty acids on butter firmness was outlined. Three fatty acids (myristic, oleic, palmitic) and four major groups of triglycerides mainly affected the firmness, sometimes leading to an inversion of the thermal effect, according to individual sample composition. A crystallographic and thermodynamic model based on triglycerides properties was developed.     

Crystallinity,particle size,and mechanical properties of fibers in some egyptian and american cotton cultivars

The main objective of this study was to measure the crystallinity, particle size, and mechanical properties of fibers and to assess their relationship in 18 Egyptian and American cotton cultivars. Remarkable variations in crystallinity were found, ranging between 49 and 90%, whereas the range of differences in particle size was somewhat narrow, and so its effect on mechanical properties was not detectable. The cotton cultivars that have higher values of crystallinity are characterized by higher values of tenacity at either $ \frac{1}{8} $ in. or zero gauge and stiffness and by reduced elongation. © 1993 John Wiley & Sons, Inc.     

Brain-targeted intranasal zaleplon solid dispersion in hydrophilic carrier system; 23 full-factorial design and in vivo determination of GABA neurotransmitter

Intranasal zaleplon solid dispersion was formulated to enhance the solubility, bioavailability and deliver an effective therapy. Zaleplon belongs to Class II drugs, and undergoes extensive first-pass metabolism after oral absorption exhibiting 30% bioavailability. A 2³ full-factorial design was chosen for the investigation of solid dispersion formulations. The effects of different variables include drug to carrier ratio (1:1 and 1:2), carrier type (polyethylene glycol 4000 and poloxamer 407), and preparation method (solvent evaporation and freeze drying) on different dissolution parameters were studied. The dependent variables determined from the in vitro characterization and their constraints were set as follows: minimum mean dissolution time, maximum dissolution efficiency and maximum percentage release. Numerical optimization was performed according to the constraints set based on the utilization of desirability functions. Differential scanning calorimetry, infrared spectroscopy, X-ray diffraction and scanning electron microscopy were performed. Ex vivo estimation of nasal cytotoxicity and assessment of the γ-aminobutyric acid level in plasma and brain 1?h after nasal SD administration in rabbits compared to the oral market product were conducted. The selected ZP-SD, with a desirability 0.9, composed of poloxamer 407 at drug to carrier ratio 1:2 successfully enhanced the bioavailability showing 44% increase in GABA concentration than the marketed tablets.     

Effect of steam treatment on the activities of Pt/NH4-MOR catalysts for n-pentane hydroisomerization and hydrocracking

The rationale of this work is to study the effect of using Pt containing catalysts supported on NH₄-MOR zeolite, before or after steaming, to show how steam treatments affect the activities of catalysts used primarily for the hydroconversion of light naphtha to improve its octane rating. Hence, the reactions of the hydroisomerization and hydrocracking of n-pentane, were investigated at temperatures between 250 and 500 °C in a pulsed microcatalytic reactor using catalysts containing 0.25, 0.35 and 0.60 wt.% Pt supported on NH₄-MOR. The effect of steaming on the dispersion of Pt, acid sites strength distribution, intraparticle diffusion resistance and the catalytic activities were investigated. Steaming was found to enhance catalytic activity deterioration. This effect was significantly increased with increasing Pt content in the catalysts. The calculated activation energy and entropy values using the current catalysts were correlated with the activity levels for hydroisomerization and hydrocracking of n-pentane.     

Perovskite-based proton conducting membranes for hydrogen separation: A review

Hydrogen is considered a fuel of the future due to its diversified supply and zero greenhouse gas emission. The application of advanced membrane technology for hydrogen separation within the larger hydrogen production process context can substitute the use of more expensive and energy intensive cryogenic distillation and pressure swing adsorption technologies. This review overviews the basic aspects and progresses in perovskite-based proton conducting hydrogen separation membranes. Different configurations such as symmetric, asymmetric, hollow fiber, and surface modified perovskite membranes with various compositions are discussed and summarized. The challenges and future directions of such membranes are also elaborated.     

Optimization of enzymatic assay for the measurement of lipoxygenase activity in organic solvent media

Lipoxygenases (LOX; EC 1.13.11.12) are an important class of non-heme iron enzymes that catalyze the di-oxidation of PUFA to hydroperoxy FA, which can be measured by the xylenol orange method (FOX). To determine the enzymatic production of these FA in organic solvent media, the FOX assay was optimized using the standard cumene hydroperoxide. An increase in the proportion of methanol from 0 to 75% in the FOX reagent resulted in a 93% increase in the molar absorption coefficients at 560 nm. In addition, the presence of linoleic acid in the cumene hydroperoxide sample enhanced the formation of the FOX complex, resulting in a 50% increase in the sensitivity of the method. Moreover, when perchloric acid was used, the source of ferrous ions and presence of denatured LOX had little effect on the sensitivity of the FOX assay whereas sensitivity decreased by 40–46% with sulfuric acid. The overall results demonstrated that the modified FOX assay may be used for the precise and accurate measurement of hydroperoxy FA obtained by LOX activity in organic solvent media.     

Thermodynamics of micellization of poly-styrene-block-poly(ethylene/propylene) copolymers in decane

Light scattering was used to establish the dependence of the critical micelle temperature, CMT, on concentration for solutions of three polystyrene-block-poly(ethylene/propylene) copolymers in decane. Electron microscopy studies of particles isolated from the solutions showed that the micelles had narrow size distributions and micellization could be treated thermodynamically as a closed association. The light scattering results were used to calculate the standard Gibbs energies of micellization, ΔG^φ, and the standard enthalpy, ΔH^φ, and entropy contributions, —TΔS^φ. The values of ΔH^φ were large and negative, and markedly dependent on the molecular weight of the polystyrene block. The values of ΔG^φ for the three samples were on the other hand very similar to each other. The standard entropy contributions were unfavourable to micelle formation.