Time filter

Source Type

Jeddah, Saudi Arabia

Nafee S.S.,Alexandria University | Nafee S.S.,King Abdullaziz University
Nuclear Technology | Year: 2010

The calibration of gamma-ray cylindrical detectors is often required in the analysis of high or low environmental samples and the homogenously distributive nuclear waste drums. Therefore, a new analytical simulation method is proposed in the present work to calculate the full-energy peak efficiencies of high-purity germanium cylindrical detectors using extended sources of low and high volumes. The sources were mounted at three different positions with respect to the detector's axis (coaxial, parallel, and perpendicular), labeled as Position 1, Position 2, and Position 3, respectively. The self-attenuation and the coincidence summing effects at low sourcedetector distance are also included in the algorithm. A remarkable agreement between the measured and the calculated efficiencies is achieved with discrepancies <4% for the first two positions and between 5 and 7% for the last one. Source

Al-bishri H.M.,King Abdullaziz University | Abdel-Fattah T.M.,Jefferson Lab | Abdel-Fattah T.M.,Christopher Newport University | Mahmoud M.E.,Alexandria University
Journal of Industrial and Engineering Chemistry | Year: 2012

A method is described for highly efficient adsorptive removal of lead with a maximum metal capacity value of 1.300mmolg -1 by using physically immobilized [Bmim +Tf 2N -] on the surface of nano-silica-amine sorbent. Lead sorption was found to be highly dependent and controlled by several experimental factors. The effect of sorbent dose played a significant role by yielding the maximum lead adsorption capacity when 100mg sorbent was used. The effect of lead concentration was examined by various adsorption isotherms. The potential applications for removal of Pb(II) were studied and the percentage recovery values were 99.0-100.0±2.0-5.0%. © 2012 The Korean Society of Industrial and Engineering Chemistry. Source

Mahmoud M.E.,Alexandria University | Al-bishri H.M.,King Abdullaziz University
Separation Science and Technology (Philadelphia) | Year: 2013

A method is described for the selective separation and extraction of cadmium-lead from aqueous solutions by tuning the pH value between 1.0 and 7.0. A modified nano-active silica sorbent was loaded with 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide hydrophobic ionic liquid, [Bmim+Tf2N-] and used in this work. The pH value was found to play a significant role in the sorption capacity of Cd(II) and Pb(II). In pH 1.0, the metal capacity values were characterized as 1.40 and 0.30 mmol g-1 for Cd(II) and Pb(II), respectively. In pH 7.0, Cd(II) and Pb(II) switched their capacity values to 0.65 and 1.00 mmol g-1, respectively. An anion exchange mechanism was proposed in solution with pH 1.0 for exchange of chloroanionic cadmium species by [Tf2N-]. The sorptive separation processes of Cd(II) and Pb(II) were studied and evaluated under the influence of various controlling factors. The potential applications of modified nano-silica sorbent for selective sorptive removal and separation of Cd(II) from Pb(II) in water samples was successfully accomplished by adjusting the pH value of the contact solution between 1.0 and 7.0. The results of this study indicated an efficient extraction behavior of the two examined metal ions. © 2013 Copyright Taylor and Francis Group, LLC. Source

Seyedmousavi S.,RadboudUMC | Seyedmousavi S.,Erasmus University Rotterdam | Seyedmousavi S.,Mazandaran University of Medical Sciences | Netea M.G.,RadboudUMC | And 9 more authors.
Clinical Microbiology Reviews | Year: 2014

Among the melanized fungi, the so-called "black yeasts" and their filamentous relatives are particularly significant as agents of severe phaeohyphomycosis, chromoblastomycosis, and mycetoma in humans and animals. The pathogenicity and virulence of these fungi may differ significantly between closely related species. The factors which probably are of significance for pathogenicity include the presence of melanin and carotene, formation of thick cell walls and meristematic growth, presence of yeast-like phases, thermo- and perhaps also osmotolerance, adhesion, hydrophobicity, assimilation of aromatic hydrocarbons, and production of siderophores. Host defense has been shown to rely mainly on the ingestion and elimination of fungal cells by cells of the innate immune system, especially neutrophils and macrophages. However, there is increasing evidence supporting a role of T-cell-mediated immune responses, with increased interleukin-10 (IL-10) and low levels of gamma interferon (IFN-γ) being deleterious during the infection. There are no standardized therapies for treatment. It is therefore important to obtain in vitro susceptibilities of individual patients' fungal isolates in order to provide useful information for selection of appropriate treatment protocols. This article discusses the pathogenesis and host defense factors for these fungi and their severity, chronicity, and subsequent impact on treatment and prevention of diseases in human or animal hosts. © 2014, American Society for Microbiology. All Rights Reserved. Source

Gheith A.M.,Mansoura University | Hariri M.S.,King Abdullaziz University
Journal of King Abdulaziz University, Marine Science | Year: 2010

Our investigations focus on the significance of texture, fauna, minerals and chemical characteristics of bottom sediments of Sharm Obhur. The back reef zones were subjected to filling, dredging and cutting processes for constructional and urbanization purposes. Shores morphology and sediment properties are changed. The geological study emphasized the nature, composition and chemical characteristics of sediment veneer in addition to the impact of human activity on the environmentally sensitive area like Sharm Obhur. Sediments are believed to be the last sink for contaminants that reach the sea. It is therefore, sedimentary regime to investigate and understand the depositional pattern of sediments. The study proved that Sharm Obhur bottom environment and its shores suffered deterioration due to uncontrolled development. Heavy metals; Zn, Cu, Ni, Cd beside minor elements; Fe and Mn have been increased in bottom sediments most probably due to human activities. The fine sediments are favourable site for the fixation of organic matter and trace elements. Source

Discover hidden collaborations