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Search Results: 1 - 10 of 466310 matches for " Said A. Ibrahim "
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Synthesis and thermal studies of mixed ligand complexes of Cu(II), Co(II), Ni(II) and Cd(II) with mercaptotriazoles and dehydroacetic acid  [PDF]
Dina M. Fouad, Ahmed Bayoumi, Mohamed A. ElGahami, Said A. Ibrahim, Abbas M. Hammam
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.28103
Abstract: A series of new mixed ligand complexes of cobalt(II), nickel(II), copper(II) and cadmium(II) have been synthesized with 3benzyl1H4[(2 methoxybenzylidine) amino]1, 2, 4triazole5 thione (MBT), 3bezyl1H4[(4chlorobenzylidine) amino]1, 2, 4triazole5thione (CBT), 3benzyl 1H4[(4nitrobenzylidine)amino]1, 2, 4triazole 5thione (NBT) and dehydroacetic acid sodium salt (Nadha). The mixed ligand complexes have been characterized by elemental analysis, spec troscopic spectral measurements (IR, UVVis.), molar conductance, magnetic measurements and thermal studies. The stoichiometry of these com plexes is M:L1:L2 = 1:1:1, 1:2:1 or 1:1:2 where L1 = NBT, CBT and MBT and L2 = Nadha. Tetrahedral structure was proposed for all Cd(II) mixed ligand complexes while the square planar geometry was proposed for Cu(II) mixed ligand complex with NBT. Octahedral structure was proposed for Ni(II), Co(II) mixed ligand complexes and Cu(II) mixed ligand complexes with CBT and MBT ligands. The thermal decomposition study of the prepared complexes was monitored by TG, DTG and DTA analysis in dynamic nitrogen atmosphere. TG, DTG and DTA studies confirmed the chemical formulations of theses complexes. The kinetic parameters were determined from the the thermal decomposition data using the graphical methods of CoatsRedfern and HorwitzMetzger. Thermodynamic parameters were calculated using standard relations.
Neural Frequency Sweeper for Accelerating S-Parameters Calculation of Planar Microwave Structures
Ezzeldin A. Soliman;Mourad Said Ibrahim
PIER M , 2008, DOI: 10.2528/PIERM08010702
Abstract: This paper presents a new frequency-sweep approach for the efficient calculation of -parameters of planar microwave structures. The approach is based on approximating the frequency dependence of the real and imaginary parts of the -parameters using neural networks. Due to its superior performance, radial basis functions neural network (RBF-NN) is adopted. A limited number of frequency samples are used to train the RBF-NN. Then, the trained RBF-NN is capable of providing a smooth frequency response with very high accuracy in a fraction of a second. The proposed method is applied to a number of planar microwave structures such as: Patch antenna with an inset feed, band-rejection filter, and branch-line coupler. According to the presented results, a speed factor of at least 10 is measured, and a maximum percentage error of 3.29% is recorded.
The Impact of Climate Changes on the Thermal Performance of a Proposed Pressurized Water Reactor: Nuclear-Power Plant
Said M. A. Ibrahim,Mohamed M. A. Ibrahim,Sami. I. Attia
International Journal of Nuclear Energy , 2014, DOI: 10.1155/2014/793908
Abstract: This paper presents a methodology for studying the impact of the cooling water temperature on the thermal performance of a proposed pressurized water reactor nuclear power plant (PWR NPP) through the thermodynamic analysis based on the thermodynamic laws to gain some new aspects into the plant performance. The main findings of this study are that an increase of one degree Celsius in temperature of the coolant extracted from environment is forecasted to decrease by 0.39293 and 0.16% in the power output and the thermal efficiency of the nuclear-power plant considered, respectively. 1. Introduction The main use of water in a thermoelectric power plant is for the cooling system to condense steam and carries away the waste heat as part of a Rankine steam cycle. The total water requirements of the plant depends on a number of factors, including the generation technology, generating capacity, the surrounding environmental and climatic conditions, and the plant’s cooling system, which is the most important factor governing coolant flow rate. Thermal power plants are built for prescribed specific design conditions based on the targeted power demand, metallurgical limits of structural elements, statistical values of environmental conditions, and so forth. At design stage, a cooling medium temperature is chosen for each site considering long term average climate conditions. However, the working conditions deviate from the nominal operating conditions in practice. For this reason, efficiency in electricity production is affected by the deviation of the instantaneous operating temperature of seawater cooling water of a nuclear power plant from the design temperature of the cooling medium extracted from environment to transfer waste heat to the atmosphere via a condenser. Present nuclear plants have about 34–40% thermal efficiency, depending on site (especially water temperature). The cooling process in nuclear power plants requires large quantities of cooling water. The huge amounts of water withdrawal and consumption cause that the electricity has to face the impacts of climate change, that is, in form of increasing sea temperatures or water scarcity. For instance, if seas exhibit too high water temperatures, the continued use of water for cooling purposes may be at risk because the cooling effect decreases and also water quality regulations could be violated. An increase in the temperature of cooling water may have impact on the capacity utilization of thermal power plants in two concerns: (1) reduced efficiency: increased environmental temperature reduces thermal
Changes in Atlantic Water characteristics in the south-eastern Mediterranean Sea as a result of natural and anthropogenic activities
Mohamed A. Said,Makram A. Gerges,Ibrahim A. Maiyza,Maged A. Hussein
Oceanologia , 2011,
Abstract: The paper investigates the changes in the characteristics of Atlantic Water (AW) flowing eastwards along the Egyptian coast in the south-easternMediterranean during the period 1959-2008. Vertically, only one water mass could be observed in winter in the upper 200 m layer, whereas insummer, there were three distinct water masses. The subsurface water mass, of Atlantic origin, occupying the 50-150 m layer andcharacterized by low salinities from < 38.60 to 38.80 PSU, moves throughout the study area from west to east and spreads over a range of density between 27.5 and 28.5 σt. Temperature and salinity have indicated increasing trends for both temperature and salinity during the last 25 years (1983-2008),reaching 0.85°C decade-1 and 0.073 PSU dec-1, respectively, for the Mediterranean surface waters. For the Atlantic water,the trends were 0.28°C dec-1 for temperature and 0.014 PSU dec-1 for salinity.
Doxorubicin-induced cardiotoxicity in mice; protection by silymarin
Heba Abdelnasser Aniss a, Ashraf El Metwally Said b, Ibrahim Helmy El Sayed c, Camelia AdLy
Egyptian Journal of Hospital Medicine , 2012,
Abstract: Background: despite its vast utility in clinical oncology, the use of doxorubicin is limited by a potentially fatal cardiomyopathy and congestive heart failure. Free radical formation and antioxidants depletion are mechanisms proposed for this cardiomyopathy. The aim of this study is to compare the potential antioxidative protective effect of silymarin on doxorubicin-induced cardiotoxicity in experimental mice. Materials and methods: four groups (ten animals in each group) of experimental mice were used as follows: Group 1, mice received only saline (intraperitoneally) and served as a negative control group; Group 2, mice received doxorubicin (intraperitoneally, 5 mg/kg body weight) in three equal injections over a period of two weeks for a cumulative dose of 15 mg/kg body weight; Group 3, mice orally administrated silymarin (200 mg/day/kg body weight) respectively, through an intragastric feeding tube over a period of three weeks; Group 4, mice treated orally with silymarin plus intraperitoneally doxorubicin administration with the same protocol of groups 3 and 4. Serum lactate dehydrogenase (LDH), creatine phosphokinase (CPK), aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), malondialdehyde (MDA), total nitric oxide (NO), cardiac reduced glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) were measured in all tested groups. Results: doxorubicin elevated the activities of LDH, CPK, AST, ALT, MDA and NO in the cardiac tissue. Cardiac antioxidant enzymes activities SOD and CAT also increased while GPx activity was decreased. Pre-co-treatment with silymarin prevented the changes induced by doxorubicin administration. These findings demonstrate the cardio-protective effect of silymarin on cardiac antioxidant status during doxorubicin induced cardiac damage in mice. Conclusion: silymarin could be recommended for further investigation as potentially new indication for clinical application.
Design and Analysis Considerations of 4-GHz Integrated Antenna with Negative Resistance Oscillator
Said H. Ibrahim
PIER B , 2009, DOI: 10.2528/PIERB08122901
Abstract: The purpose of this paper is to present a complete design and analysis of a new integrated balanced transmitter operated at 4 GHz using microstrip technology. It comprises a 4-GHz two-port negative resistance oscillator and a microstrip-patch antenna resonated at 4 GHz. Three different modules are designed and analyzed. The first one used a Lange coupler as a power splitter while the second and third used a one (two)-section branch couplers. The components of the three modules are designed using full-scale computer simulation program named with MSDES; performed by the author; which takes fully into account all the discontinuities included in the microstrip lines, while the modules are analyzed and optimized using APLAC V7.61 software. The design methodologies of the two-port negative resistance oscillator and microstrip patch antenna are introduced and explained. The analyses of the designed modules show a better efficiency and good performance. The modules give a transmit-antenna gain of 15.7 dB with antenna beam widths 91.7 and 18.2 in -and -planes, respectively. The complete schematic diagrams of the transmitter modules are drawn. These modules can be used in satellite communication, Doppler and other radars, active and semi-active seekers, radio altimeters, missile technology, weapon fuzing, manpack equipment, remote sensing, feed elements in complex antennas, satellite navigation receivers, and biomedical radiators.
Ipomoea aquatica Extract Shows Protective Action Against Thioacetamide-Induced Hepatotoxicity
Salim Said Alkiyumi,Mahmood Ameen Abdullah,Ahmed Salim Alrashdi,Suzy Munir Salama,Siddig Ibrahim Abdelwahab,A. Hamid A. Hadi
Molecules , 2012, DOI: 10.3390/molecules17056146
Abstract: In the Indian system of traditional medicine (Ayurveda) it is recommended to consume Ipomoea aquatica to mitigate disorders like jaundice. In this study, the protective effects of ethanol extract of I. aquatica against liver damage were evaluated in thioacetamide (TAA)-induced chronic hepatotoxicity in rats. There was no sign of toxicity in the acute toxicity study, in which Sprague-Dawley (SD) rats were orally fed with I. aquatica (250 and 500 mg/kg) for two months along with administration of TAA (i.p injection 200 mg/kg three times a week for two months). The results showed that the treatment of I. aquatica significantly lowered the TAA-induced serum levels of hepatic enzyme markers (ALP, ALT, AST, protein, albumin, bilirubin and prothrombin time). The hepatic content of activities and expressions SOD and CAT that were reduced by TAA were brought back to control levels by the plant extract supplement. Meanwhile, the rise in MDA level in the TAA receiving groups also were significantly reduced by I. aquatica treatment. Histopathology of hepatic tissues by H&E and Masson trichrome stains displayed that I. aquatica has reduced the incidence of liver lesions, including hepatic cells cloudy swelling, infiltration, hepatic necrosis, and fibrous connective tissue proliferation induced by TAA in rats. Therefore, the results of this study show that the protective effect of I. aquatica in TAA-induced liver damage might be contributed to its modulation on detoxification enzymes and its antioxidant and free radical scavenger effects. Moreover, it confirms a scientific basis for the traditional use of I. aquatica for the treatment of liver disorders.
Analysis of Electrical Characteristics of Photovoltaic Single Crystal Silicon Solar Cells at Outdoor Measurements  [PDF]
A. Ibrahim
Smart Grid and Renewable Energy (SGRE) , 2011, DOI: 10.4236/sgre.2011.22020
Abstract: The electrical performance of a photovoltaic (PV) silicon solar cell is described by its current–voltage (I–V) character-istic curve, which is in turn determined by device and material properties. In this study, an investigation of the performance and device parameters of photovoltaic single crystalline silicon (Si.) solar cell of the construction n+pp++ PESC(Passivatted Emitter Solar Cell) at different conditions of solar irradiance, title angle and mirror boosting effects had been studied. Also the paper reports on the performance data of the Si. cell, using standard I–V characteristic curves to obtain output parameters and to show that there are possible performance degrading defects presents.
Reliability Modelling and Analysis of Redundant Systems Connected to Supporting External Device for Operation Attended by a Repairman and Repairable Service Station  [PDF]
Ibrahim Yusuf, Rabia Salihu Said, Fatima Salman Koki, Mansur Babagana
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.213145
Abstract: In this paper, probabilistic models for three redundant configurations have been developed to analyze and compare some reliability characteristics. Each system is connected to a repairable supporting external device for operation. Repairable service station is provided for immediate repair of failed unit. Explicit expressions for mean time to system failure and steady-state availability for the three configurations are developed. Furthermore, we compare the three configurations based on their reliability characteristics and found that configuration II is more reliable and efficient than the remaining configurations.
Studies on the Effect of the Capping Materials on the Spherical Gold Nanoparticles Catalytic Activity  [PDF]
Roshdi Seoudi, Doaa A. Said
World Journal of Nano Science and Engineering (WJNSE) , 2011, DOI: 10.4236/wjnse.2011.12008
Abstract: Size-controlled gold nanoparticles (AuNPs) were prepared in the presence of different capping materials (sodium citrate, cetyltrimethylammonium bromide (CTAB), and chitosan). The results obtained suggest that the AuNPs were synthesized with different particle size, which is controlled by changing the molar ratio between sodium citrate, (CTAB), and chitosan to Au (III). The catalytic activities of the AuNPs with different capping materials were studied for 4-nitrophenol reduction by NaBH4 as a model reaction. AuNPs with different capping materials is comparable from the value of the apparent rate constant of 4-nitrophenol reduction (0.6 × 10–3, 1.9 × 10–3, and 2.4 × 10–3 s–1) for sodium citrate, CTAB and chitosan. From the results, it is concluded that, AuNPs catalyzed the electron transfer process between and nitro compounds with all the capping materials used AuNPs capped by chitosan were more active for the reduction than the other two.
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