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Jeddah, Saudi Arabia

Abdel-Aziz M.H.,Lakehead University | Abdel-Aziz M.H.,Alexandria University | Abdel-Aziz M.H.,Kingabdulaziz University | Hassan I.,Arab Academy for Science and Technology | And 2 more authors.
Chemical Engineering and Processing: Process Intensification

Rates of mass transfer at V-corrugated surfaces in a rectangular duct were measured under two phase flow by the limiting current technique. Variables studied were groove angle and peak to valley height of the corrugated surface, solution velocity and superficial gas velocity. For a given solution velocity and superficial gas velocity the mass transfer coefficient was found to increase with increasing groove angle and decrease with increasing groove peak to valley height. The volumetric mass transfer enhancement ratio compared to the smooth surface ranged from 3.7 to 7.58 depending on the operating conditions. The mass transfer data at the corrugated surface were correlated by the equation: Sh=1.52Sc0.33ReL0.285Reg0.28(de/P)0.375.For a batch gas sparged reactor with an active corrugated surface the data were correlated by the equation: j=0.047(Re·Fr)-0.15(de/P)0.6.Implications of the present results for the design and operation of compact continuous two phase and batch gas sparged heat and mass transfer equipments such catalytic reactors, electrochemical reactors, and heat exchangers was noted. © 2013 Elsevier B.V. Source

Gutierrez-Arcelus M.,University of Geneva | Gutierrez-Arcelus M.,Institute of Genetics and Genomics in Geneva iGE3 | Gutierrez-Arcelus M.,Swiss Institute of Bioinformatics | Ongen H.,University of Geneva | And 47 more authors.
PLoS Genetics

Understanding how genetic variation affects distinct cellular phenotypes, such as gene expression levels, alternative splicing and DNA methylation levels, is essential for better understanding of complex diseases and traits. Furthermore, how inter-individual variation of DNA methylation is associated to gene expression is just starting to be studied. In this study, we use the GenCord cohort of 204 newborn Europeans’ lymphoblastoid cell lines, T-cells and fibroblasts derived from umbilical cords. The samples were previously genotyped for 2.5 million SNPs, mRNA-sequenced, and assayed for methylation levels in 482,421 CpG sites. We observe that methylation sites associated to expression levels are enriched in enhancers, gene bodies and CpG island shores. We show that while the correlation between DNA methylation and gene expression can be positive or negative, it is very consistent across cell-types. However, this epigenetic association to gene expression appears more tissue-specific than the genetic effects on gene expression or DNA methylation (observed in both sharing estimations based on P-values and effect size correlations between cell-types). This predominance of genetic effects can also be reflected by the observation that allele specific expression differences between individuals dominate over tissue-specific effects. Additionally, we discover genetic effects on alternative splicing and interestingly, a large amount of DNA methylation correlating to alternative splicing, both in a tissue-specific manner. The locations of the SNPs and methylation sites involved in these associations highlight the participation of promoter proximal and distant regulatory regions on alternative splicing. Overall, our results provide high-resolution analyses showing how genome sequence variation has a broad effect on cellular phenotypes across cell-types, whereas epigenetic factors provide a secondary layer of variation that is more tissue-specific. Furthermore, the details of how this tissue-specificity may vary across inter-relations of molecular traits, and where these are occurring, can yield further insights into gene regulation and cellular biology as a whole. © 2015 Gutierrez-Arcelus et al. Source

Zakia A.J.,Taibah University | Faten F.A.,Kingabdulaziz University
Life Science Journal

The total and dry body weight treated larvae of Aedes aegypti was significantly decreased at different time intervals under investigation (6, 12, 24, and 48 hrs) post-treatment with LC30 of Bt subsp. Kurstaki HD-1. The body water content was decreased significantly at 6 hrs post-treatment, while it was highly significant at the three other treatments. Also hemolymph volume was significantly decreased. A significant increase in hemolymph density was observed only at 12 hrs post treatment. The main of the total hemocyte count in the treated larvae at all inspected time was highly significant increased, also there was a marked variation in the hemocytes percentage of untreated and treated larvae of Aedes eagypti at time intervals. Source

Thermoelectric transport measurements were made on single crystal samples of Tl2GaInSe4. The crystal was prepared by a special design based on the Bridgman technique. Measurements of thermoelectric power were carried out in a special high vacuum-tight calorimeter when the direction of temperature gradient is perpendicular to the cleavage plane. The measurements covered a temperature range extending from 300 to 725 K. The results indicate P-type conductivity for our investigated samples. At room temperature the value of thermoelectric power was 735 μV/deg. The electron to hole mobility ratio was found to be 1.35. The effective mass of holes at room temperature was evaluated as 4:635×10-29 kg, while for electron was equal to 8:468×10-31 kg. The relaxation time of majority and minority carriers was estimated as -p = 2:968×10 10 s and -n = 7:326×10-12 s, respectively. Also, the diffusion coefficient of holes and electrons at room temperature was calculated and found to be 265.132 cm2/s and 358.139 cm2/s, respectively. The diffusion length of holes and electrons are found to be Lp = 2:805×10-4 cm and Ln = 5:122 × 10-5 cm. In addition to these pronounced parameters, the efficiency of thermoelectric element (figure of merit) was evaluated which leads to better applications in many fields. Source

Balkhair K.S.,King Abdulaziz University | Ismail S.M.,Kingabdulaziz University | Ismail S.M.,Assiut University | El-Nakhlawy F.S.,Kingabdulaziz University | Al-Solaimani S.G.,Kingabdulaziz University
Life Science Journal

Field experiments were carried out over two consecutive seasons (2011 and 2012) at an agricultural site in the western region of Saudi Arabia, to study the effect of wastewater irrigation on the yield, toxic metals, and fecal coliform bacteria of white radish crop. Six different wastewater qualities were prepared by diluting various percentages of the treatment plant's effluent with local groundwater (LGW). The crop water requirement for white radish was calculated by Penman-Monteith equation for dry land condition and supplied daily by two drip irrigation systems; surface and subsurface. Root yield, irrigation water use efficiency (IWUE), fecal coliform, and content of toxic metals in the plant and soil were determined at the end of each growing season. Results indicated that the highest root yield/ha, and IWUE were obtained from the treatments of 60T (60% wastewater mixed with 40% LGW) and 100T (100% wastewater). Due to the relatively early cultivation in the second growing season, the total yield/ ha and IWUE were higher than that of the first season.On the other hand, fecal coliform bacteria count and toxic metals increased systematically in the plant and soil as the quantity of wastewater in the irrigation water increased. Notably, the concentrations of toxic metals in the plant and soil were less than that of the cytotoxic standards declared by WHO-FAO (2007) and EU (2002). In conclusion, the best treatments that produced the highest yield and IWUE with minimal microbial contamination were 60T and 100T suggesting a safer use, better performance and considerable LGW conservation. Source

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