Bioactive glass ceramic is characterized by high mechanical strength and a slow rate of bone bonding. To understand the factors contributing to a decrease in the rate of bone bonding to bioactive glass ceramic, we evaluated the effect of different percentages of bioactive glass crystallization on corrosion behavior, zeta potential, and serum protein adsorption. X-ray diffraction analysis showed that heat treatment of bioactive glass in the temperature range 550 degrees -700 degrees C resulted in the precipitation of Na(2)Ca(2)Si(3)O(9) crystals in the glass matrix. The percentage of crystallization increased in the order: 5%, 8%, 45%, and 83% after thermal treatment at 550 degrees, 600 degrees, 650 degrees, and 700 degrees C/1 h, respectively. Scanning electron microscopic analyses of bioactive glass treated at 550 degrees C showed major glass in glass-phase separation. Moreover, energy-dispersive X-ray analyses indicated that during crystallization P is concentrated in the glassy phase. Induced-coupled plasma analyses showed that after 24 h immersion in simulated body fluid, the concentration of the released P ion increased as the crystallization percentage of bioactive glass increased. zeta potential of bioactive glass samples containing 5% crystallization had a statistically significant higher negative value than control untreated bioactive glass (p <.02). Control untreated bioactive glass adsorbed a statistically significant higher amount of serum protein than bioactive glass samples containing 5% crystallization (p <.02). Results of our study suggest that inhibition of protein adsorption might be responsible for the slow rate of bone bonding to bioactive glass ceramic. It is also possible that conformation changes inhibit the activity of the protein adsorbed onto thermally treated bioactive glass.

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Reductive roasting of ilmenite ore by carbon in the presence of sodium carbonate was carried out at 1000-1200°C for periods of up to 180 min. Additions of sodium carbonate of up to 30 wt% of the ore enhanced the reduction efficiency. The maximum metallization obtained at 1200°C was about 85%, and the rest of the iron exists in the form of sodium-iron-titanates. The type of sodium compound formed in the final product depends on the roasting temperature. The reduction rate data under isothermal conditions were represented by a phase-boundary reaction model for conversions of up to 70 wt%. The apparent activation energy obtained is about 67 kJ Imol. Magnetic separation of roasted products gave different magnetic fractions having different Fe/Ti02 ratios (ranging from 2-3) as well as a non-magnetic fraction that was low in iron and suitable for titanium dioxide production.Resume-Le grillage reductif du minerai d'ilmenite par Ie carbone, en presence du carbonate de sodium, a ete conduit a 1000-1200°C pour des periodes allantjusqu'a 180min. Des additions de carbonate de sodium allant jusqu'a 30% en poids du minerai ont ameliore l'efficacite de la reduction. La metallisation maximum obtenue a 1200°C etait d'environ 85% alors que Ie reste du fer avait la forme de sodium-fer-titanates. Le type de compose de sodium forme dans Ie produit final depend de la temperature de grillage. Les donnees du taux de reduction en conditions isothermales ont ete representees par un modele de reaction de phaselimite pour des conversions jusqu'a 70% en poids. L'activation d'energie apparente obtenue est d'environ 67 kJ Imol. La separation magnetique des produits grilles a donne des fractions magnetiques differentes ayant differents rapports de Fe/Ti02 (entre 2-3) ainsi qu'une fraction non-magnetique qui Hait faible en fer et propice a la production du bioxide de titane.

Talc has found a steadily increasing number of uses such as cosmetics, steatite and cordierite ceramics, for pitch control in the paper industry and as a reinforcing filler in rubber, etc. In this research, the amenability of some Egyptian carboniferous finely disseminated talc ores to beneficiation by flotation was investigated on laboratory scale. The original talc sample is characterized by low MgO content (

Filamentous fungi have been widely utilized in production of enzymes which have many industrial applications. In this study, twenty five local fungal isolates, belonging to Aspergillus sp., Trichoderma sp. and Penicillium sp., were screened under solid state fermentation conditions (SSF) for the production of α-amylase, glucoamylase and cellulase. Asperigillus oryzae F-923, cultivated on wheat bran, was the most promising isolate for production of the target enzymes under this study. Physical parameters of moisture content, pH, temperature and incubation time, optimized were 1:2(w/v), 5.5, 28°C and 72 hr, respectively. The production of enzymes was enhanced when ammonium sulfate was supplemented as a nitrogen source to wheat bran. The production of α-amylase and glucoamylase was also enhanced when 10% (w/w) soluble starch was added as a carbon source to wheat bran. However xylose supplementation at 10% (w/w) was observed to be best for cellulase production. Tap water was found to be efficient for enzymes' extraction from the fermentation medium. Three successive extractions were needed to obtain the produced enzymes from the fermented substrate. Characterization of the produced enzymes revealed that, the optimum temperature for α-amylase and glucoamylase was 60°C, while 50°C was the optimum temperature for cellulase activity. Isopropanol 1:1(v/v) was proved to be more suitable for partial purification of enzymes. Following partial purification of enzymes of glucoamylase, α-amylase and cellulase increased to 10.8, 11.8 and 11.4 folds, respectively.