Effect of exchanging PbO with NiO on the structure and optical parameters action of some lanthanum borate oxide glasses

Journal of Materials Science: Materials in Electronics - This work is an attempt to estimate the effect of the exchanging of PbO with NiO on the optical and structural parameters for some...     

Treatment of sewage and industrial wastewater effluents by the cyanobacteria Nostoc muscorum and Anabaena subcylinderica

The potential of two cyanobacteria, Nostoc muscorum and Anabaena subcylindrica to treat sewage and industrial wastewater effluents was investigated. Two different sites were selected for this study which are located at the drains of sewage plant, a salt and soda production company at Kafr El-Zayat city. All samples were taken from the sewage and/or industrial effluents before treatment. Treatment of the sewage and industrial wastewater effluents by using cyanobacteria (N. muscorum, A. subcylindrica and mixed culture of both) revealed that the pH value of the biologically treated wastewater increased, the electrical conductivity was recovered in a range between (4.7–23.9%) and the total dissolved solids were reduced by (4.4–23.3%). The reduction of turbidity level was in a range between (40–96.4%). The removal efficiency of organic matter (COD, PV) was in a range between (20–57.1%) and (25.7–66.7%), respectively. Phosphorus reduction, nitrate treatment and ammonia elimination efficiencies by cyanobacterial system were (20.8–95%), (19.6–80%) and (20.9–96%), respectively. With respect to the treatment efficiency of wastewater by using single or mixed cultures of cyanobacteria, it was observed that the single cultures in most cases was better than the mixed cultures and this may be due to the competition between mixed cultures for nutrients. However, it could be concluded from the presented data that the treatment of wastewater by cyanobacteria is a fruitful method to produce an effluent of high quality to be used for irrigation.     

Utilization of Black Liquor for Production of Antimicrobial Substance by Streptomyces Species

Utilization of black liquor hydrolyzates, obtained from different sources, for the growth of different Streptomyces species and production of antimicrobial substance was studied. Streptomyces violaceoniger, which exhibited good growth and production of the antimicrobial substance, was chosen for further studies. Removal of aldehydes, lactones, and furfural from the liquor resulted in a considerable increase in biomass and yield.     

Investigation of wall mass transfer characteristics downstream of an orifice

Numerical simulations were performed to determine the effect of Reynolds number and orifice to pipe diameter ratio (d_o/d) on the wall mass transfer rate downstream of an orifice. The simulations were performed for d_o/d of 0.475 for Reynolds number up to 70,000. The effect of d_o/d was determined by performing simulations at a Reynolds number of 70,000 for d_o/d of 0.375, 0.475 and 0.575. The momentum and mass transport equations were solved using the Low Reynolds Number (LRN) K-? turbulence model. The Sherwood number (Sh) profile downstream of the orifice was in relatively good agreement with existing experimental results. The Sh increases sharply downstream of the orifice, reaching a maximum within 1–2 diameters downstream of the orifice, before relaxing back to the fully developed pipe flow value. The Sh number well downstream of the orifice was in good agreement with results for fully developed pipe flow estimated from the correlation of Berger and Hau (1977). The peak Sh numbers from the simulations were higher than that predicted from Tagg et al. (1979) and Coney (1980).     

Effects of Different Microorganisms on Pulp and Paper Properties

Pretreatment of wood chips with some microorganisms including white-rot fungi and streptomyces improves the strength properties of mechanical pulps. We studied the effect of these white-rot fungi and streptomyces on the mechanical properties of handsheets. Strength and optical properties were compared in handsheets prepared from mechanical pulp of treated and untreated wood chips. The fungal pretreatments resulted in handsheet strength properties better than the control and also better than streptomyces when compared at an equivalent freeness. Fungal pretreatments decreased brightness and light-scattering coefficients but did not adversely affect opacity. Lignin content of the chips was reduced by fungal pretreatments.     

Verification of U mass content in nuclear fuel plates by an absolute method

Nuclear Safeguards is referred to a verification System by which a State can control all nuclear materials (NM) and nuclear activities under its authority. An effective and efficient Safeguards System must include a system of measurements with capabilities sufficient to verify such NM. Measurements of NM using absolute methods could eliminate the dependency on NM Standards, which are necessary for other relative or semi-absolute methods. In this work, an absolute method has been investigated to verify the ²³⁵U mass content in nuclear fuel plates of Material Testing Reactor (MTR) type. The most intense gamma-ray signature at 185.7 keV emitted after -decay of the ²³⁵U nuclei was employed in the method. The measuring system (an HPGe-spectrometer) was mathematically calibrated for efficiency using the general Monte Carlo transport code MCNP-4B. The calibration results and the measured net count rate were used to estimate the ²³⁵U mass content in fuel plates at different detector-to-fuel plate distances. Two sets of fuel plates, containing natural and low enriched uranium, were measured at the Fuel Fabrication Facility. Average accuracies for the estimated ²³⁵U masses of about 2.62% and 0.3% are obtained for the fuel plates containing natural and low enriched uranium; respectively, with a precision of about 3%.     

Preparation and evaluation of cerium(IV) tungstate powder as inorganic exchanger in sorption of cobalt and europium ions from aqueous solutions

Cerium(IV) tungstate powder was chemically synthesized and exploited as adsorbent material for the decontamination study of cobalt and europium ions from radioactive waste solutions under simulated conditions using batch technique. The influences of pH, particle size and temperature have been reported. The uptake of europium was found to be slightly greater than that of cobalt and the apparent sorption capacity increases with increase in temperature. Thermodynamic parameters such as changes in Gibbs free energy (DeltaG degrees), enthalpy (DeltaH degrees), and entropy (DeltaS degrees) were calculated. The numerical value of DeltaG degrees decreases with an increase in temperature, indicating that the sorption reaction of each ion was spontaneous and more favorable at higher temperature. The positive values of DeltaH degrees correspond to the endothermic nature of sorption processes and suggested that chemisorption was the predominant mechanism. A comparison of kinetic models applied to the sorption rate data of each ion was evaluated for the pseudo first-order, the pseudo second-order, intraparticle diffusion and homogeneous particle diffusion kinetic models. The results showed that both the pseudo second-order and the homogeneous particle diffusion models were found to best correlate the experimental rate data. The numerical values of the rate constants and particle diffusion coefficients were determined from the graphical representation of the proposed models. Activation energy (E(a)) and entropy (DeltaS++) of activation were also computed from the linearized form of Arrhenius equation.     

The hydrodynamic effects of single-phase flow on flow accelerated corrosion in a 90-degree elbow

The hydrodynamic effects of single-phase flow on flow accelerated corrosion (FAC) in a single 90-degree elbow were investigated at a Reynolds number of 40,000. Experiments were performed to determine the surface wear patterns using elbows fabricated from hydrocal. The time evolution of the local surface wear was quantified using a laser scanning coordinate measurement system. Numerical simulations for the flow field were performed, and the wear patterns were correlated to the flow structures within the elbow. The wear patterns indicated the development of surface wear in the form of scallops over most of the elbow surface. Elevated levels of wear were found along the inlet of the elbow intrados. Along the elbow extrados, increased levels of wear, starting from 37° downstream of the elbow inlet and up to the elbow exit, were found at prolonged test times. The magnitude of the maximum wear on the surface along the elbow inner radius was found to be approximately 37% higher than the corresponding value at the surface along the outer radius.     

Grafting of cellulose–thiocarbamate with vinyl monomers: Antimicrobial activity

Grafting of vinyl monomers onto cellulose-thiocarbamate was carried out using ceric ammonium sulfate (CAS) as an initiator. The graft yield was found to depend on the amount of thiocarbamate groups, initiator, and monomer concentrations as well as temperature. The graft yield increased with increasing (CAS) concentration. The reactivity of vinyl monomers studied followed the order ethyl acrylate>acrylonitrile. A comparison between the graft yields obtained with the modified cullulose indicated that cellulose thiocarbamates having less than 1.1% nitrogen showed lower graft yields than the unmodified cellulose. Above this, cellulose thiocarbamate was much more amenable to grafting than the unmodified cellulose. The grafted cellulose thiocarbamates exhibited high antifungal activity and had no effect on gram-negative, gram-positive bacteria and yeast. The maximum zone of inhibition was obtained after grafting with 2 h which resulted in 43 and 50% add-on polymer in the cases of acrylonitrile and ethyl acrylate, respectively. Grafted cellulose thiocarbamates with acrylonitrile had higher potency for antifungal activity than that grafted with ethyl acrylate.