Khusayfan N.M.,KingAbdulaziz University |
Qasrawi A.F.,Atilim University |
Khanfar H.K.,King Abdulaziz University
Materials Science in Semiconductor Processing | Year: 2017
The effect of the Yb, In, Ag and Au thin film metal substrates on the structural and electrical properties of Bi2O3 thin films are investigated by means of X-ray diffraction, impedance spectroscopy an current-voltage characteristic techniques. The Bi2O3 films are observed to exhibit a crystallization nature depending on the crystal structure of the substrate. Particularly, when the metal substrate is facing centered cubic, the Bi2O3 prefers the γ− phase of body centered cubic crystallization for the (Yb, Ag and Au)/Bi2O3 interfaces. Whereas when a tetragonal substrate (indium) is used, the tetragonal β−Bi2O3 single phase is preferred. All structural parameters presented by the lattice constant, degree of orientation, dislocation density, micro-strain and grain size are observed to strongly depend on the crystal type. In addition, the evaluation of the Schottky barrier formation at the (Yb, In, Ag, Au)/Bi2O3/Au interfaces by the current-voltage characteristics, revealed that the (In, Au)/Bi2O3/Au interface exhibit ohmic nature of contact and the (Yb, Ag)/Bi2O3/Au are of Schottky type, the rectification ratio for the Yb/Bi2O3/Au interface reaches a value of 105 indicating the applicability of these interfaces in CMOS digital logic devices. Moreover, the impedance spectroscopy analysis revealed that the ohmic interfaces exhibit a negative capacitance effect. The In/β−Bi2O3/Au and Yb/γ−Bi2O3/Au interfaces are performing as microwave traps with wave absorption percentage of 62% and 92% at frequencies of 193 and 1200 MHz, respectively. The features of the devices are promising as they indicate the applicability as microwave resonator and fast electronic switches. © 2017
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 | Year: 2013
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.
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 | Year: 2014
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.
Zaher G.,Kingabdulaziz University |
Adam S.,Kingabdulaziz University
Mediterranean Journal of Hematology and Infectious Diseases | Year: 2012
Acquired haemophilia A is a serious and potentially fatal bleeding disorder. Diagnosis is difficult and maybe delayed due to its rarity. The high mortality rate and the complex nature of treatment necessitate patient management at a haemophilia centre, where the required expertise and resources are available. Prompt diagnosis is crucial and early initiation of therapy could be life saving. Management includes initial control of bleeding followed by an approach to eradicate the coagulation factor inhibitor. In this paper we describe our local experience with acquired haemophilia A, which resulted in the successful control of major bleeding at presentation and eradication of inhibitors.
Al-Attas A.S.,Kingabdulaziz University |
Al-Raimi D.S.,Kingabdulaziz University |
Habeeb M.M.,Kingabdulaziz University |
Habeeb M.M.,Alexandria University
Journal of Molecular Liquids | Year: 2014
2-Amino-5,6-dimethyl-1,2,4-triazine (ADMT) reacts instantaneously with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) in acetonitrile (AN) forming reddish brown charge transfer complex. Absorption spectra of the complex produced multi-charge transfer bands at 460, 560 and 589 nm, respectively. The molecular composition of the formed complex was studied by applying continuous variation and spectrophotometric titration methods where 1:1 charge transfer complex (ADMT: DDQ) is produced. Benesi-Hildebrand equation has been applied to calculate the formation constant KCT and molecular extinction coefficient; they reached high values asserting high stability of the formed CT complex. Enthalpy and entropy of CT complex formation (-ΔHo and -ΔSo) have been estimated utilizing Van't Hoff equation where -ΔHo recorded high value confirming strong bonding between donor and acceptor. Moreover, molecular modeling of the formed complex has been carried out using GAMESS interface computations. These computations included measuring bond lengths, bong angles, distance of close contacts as well as potential energy maps. © 2014 Elsevier B.V.
Habeeb M.M.,Kingabdulaziz University |
Habeeb M.M.,Alexandria University |
Al-Attas A.S.,Kingabdulaziz University |
Al-Raimi D.S.,Kingabdulaziz University
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2015
Charge transfer (CT) interaction between 3,5-dimethylpyrazole (DMP) with the π-acceptor 2,3-dichloro-5,6-dicyano-p-benzoquinon (DDQ) has been investigated spectrophotometrically in acetonitrile (AN). Simultaneous reddish brown color has been observed upon mixing donor with acceptor solutions attributing to CT complex formation. The electronic spectra of the formed complex exhibited multi-charge transfer bands at 429, 447, 506, 542 and 589 nm, respectively. Job's method of continuous variations and spectrophotometric titration methods confirmed the formation of the studied complex in 1:2 ratio between DMP and DDQ. Benesi-Hildebrand equation has been applied to calculate the stability constant of the formed complex where it recorded high value supporting formation of stable complex. Molecular orbital calculations using MM2 method and GAMESS (General Atomic and Molecular Electronic Structure System) interface computations as a package of ChemBio3D Ultra12 software were carried out for more analysis of the formed complex in the gas phase. The computational analysis included energy minimisation, stabilisation energy, molecular geometry, Mullikan charges, molecular electrostatic potential (MEP) surfaces of reactants and complex as well as characterization of the higher occupied molecular orbitals (HOMO) and lower unoccupied molecular orbitals (LUMO) surfaces of the complex. A good consistency between experimental and theoretical results has been recorded. ©2015 Elsevier B.V. All rights reserved.
Zakia A.J.,Taibah University |
Faten F.A.,Kingabdulaziz University
Life Science Journal | Year: 2012
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.
Al Orainy R.H.,Kingabdulaziz University
Acta Physica Polonica A | Year: 2013
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.
PubMed | Alexandria University and Kingabdulaziz University
Type: | Journal: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy | Year: 2015
Charge transfer (CT) interaction between 3,5-dimethylpyrazole (DMP) with the -acceptor 2,3-dichloro-5,6-dicyano-p-benzoquinon (DDQ) has been investigated spectrophotometrically in acetonitrile (AN). Simultaneous reddish brown color has been observed upon mixing donor with acceptor solutions attributing to CT complex formation. The electronic spectra of the formed complex exhibited multi-charge transfer bands at 429, 447, 506, 542 and 589nm, respectively. Job()s method of continuous variations and spectrophotometric titration methods confirmed the formation of the studied complex in 1:2 ratio between DMP and DDQ. Benesi-Hildebrand equation has been applied to calculate the stability constant of the formed complex where it recorded high value supporting formation of stable complex. Molecular orbital calculations using MM2 method and GAMESS (General Atomic and Molecular Electronic Structure System) interface computations as a package of ChemBio3D Ultra12 software were carried out for more analysis of the formed complex in the gas phase. The computational analysis included energy minimisation, stabilisation energy, molecular geometry, Mullikan charges, molecular electrostatic potential (MEP) surfaces of reactants and complex as well as characterization of the higher occupied molecular orbitals (HOMO) and lower unoccupied molecular orbitals (LUMO) surfaces of the complex. A good consistency between experimental and theoretical results has been recorded.
PubMed | King Abdulaziz University, Taif University, KingAbdulaziz University and University of Nottingham
Type: | Journal: BMC complementary and alternative medicine | Year: 2016
High plasma concentration of low-density lipoprotein cholesterol (LDL-c) plays a significant role in the incidence of atherosclerosis and coronary heart diseases. The aim of this study was to investigate the mechanism by which the citrus flavonoid, hesperetin, regulates the LDL receptor (LDLr) gene in the human liver using the human hepatoma cell line, HepG2.Luciferase reporter gene assays were performed (in the absence of lipoprotein) to measure the activity of the LDLr promoter and the promoters of the sterol regulatory element binding protein (SREBP) transcription factors that control the LDLr promoter.Only SREBP-1 promoter activity was significantly increased 4h after exposure to 200M hesperetin. However, after 24h incubation with 200M hesperetin, the activities of all the promoter-constructs, SREBP-1a, -1c, -2 and LDLr, were significantly increased. The effects of 200M hesperetin on elevating LDLr mRNA levels were possibly due to regulation of LDLr gene transcription by SREBP-la and SREBP-2.We conclude that 200M hesperetin was likely to have stimulated LDLr gene expression in human hepatoma HepG2 cells via increased phosphorylation of PI3K andERK1/2, which increased SREBP-1a and SREBP-2 mRNA levels and enhanced the maturation of the encoded proteins. This may lead to lower plasma LDL cholesterol; therefore, diets supplemented with hesperidin might provide cardio-protective effects and reduce mortality and morbidity from coronary heart diseases.