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Search Results: 1 - 10 of 278 matches for " Rawya Ramadan "
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More Insight on Structure of New Binary Cerium Borate Glasses  [PDF]
Gomaa El-Damrawi, Fawzeya Gharghar, Rawya Ramadan
New Journal of Glass and Ceramics (NJGC) , 2018, DOI: 10.4236/njgc.2018.81002
Abstract: The structure of glasses in the system of xCeO2(100?-x)B2O3, x = 30, 40, 50 mol% CeO2 has been explored for the first time by correlation between data obtained from XRD, FTIR and 11B NMR analyses. NMR spectroscopy andFTIR spectroscopy have confirmed that transformation rate of BO3 to BO4 groups is reduced by CeO2 addition.The concentration of Ce4-O-Ce4 is increased at the expense of
Flat Panel Solar Thermoelectric System Size Optimisation at Different Vacuum Levels  [PDF]
Kazuz Ramadan
Open Journal of Energy Efficiency (OJEE) , 2015, DOI: 10.4236/ojee.2015.44006
Abstract:

A systematic experimental investigation to understand the effect of heat loss and the thermoelectric aspect ratio (cross sectional area and length) on a flat plate solar thermoelectric system performance was carried out. The investigation involved a series of experiments on systems with 4 different sizes of thermoelectric generators, and it was tested in 5 different vacuum levels during the steady-state. The detailed experimental investigation provided a substantial amount of data, which revealed that the system performance of both heat and electricity power were improved when the heat lost was minimised. The system’s performance strongly depended on the aspect ratio of the thermoelectric generators. This finding might have a significant impact on the cost of the system by saving the user’s and the manufacturer’s time in examining different TEGs with different aspect ratios in order to get the optimum size optimisation of the hybrid system, as well as reduce the manufacturing cost.

Microstructural Evolution of Cast Hyper-Eutectic Al-18% Si Alloy during Cyclic Semi-Solid Heat Treatment  [PDF]
Mohamed Ramadan
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2015, DOI: 10.4236/jmmce.2015.35041
Abstract: The cyclic semi-solid heat treatment represents a promising technique for improving microstructure and mechanical properties of a wide range of metallic alloys. In the current research the influence of cyclic semi-solid heat treatment on microstructure of Al-18% Si alloy containing 0.8% Fe has been studied. All specimens were heated in an electrically heated resistance furnace with heating rate of 10°C·min-1 to 585°C. For a complete one cycle heat treatment (5 min heating time), samples after 5 min holding at 585°C were cooled to a temperature of 550°C in still air cooling and the samples were taken out immediately for water quenching. It was found that heat treatment cycles should be limited to 3 cycles or less in order to maintain fine grain size and globular structure without agglomeration and coalescence. Cyclic semi-solid heat treatment changes morphology of iron-rich intermetallics phases to be plate-like and fine plate iron-rich intermetallics phases, in stead of needle-like iron-rich intermetallics phases that are observed in as-cast samples. Cyclic heating shows a relatively higher hardness for all heating cycles compared with as-cast one due to its finer and globular structure. Cyclic semi-solid heat treatment technique results in lower coarsening rate constant compared with isothermal heat treatment one due to coarsening discontinuous effect.
Association of Human Herpesvirus 6 and 8 in Relapsing Remitting Multiple Sclerosis Type during Exacerbation  [PDF]
Hassan Salama, Mohamed El-Khateeb, Rawya Bader, Mohamed Saleh, Enas Hamad
Neuroscience & Medicine (NM) , 2010, DOI: 10.4236/nm.2010.11005
Abstract: Multiple Sclerosis (MS) is a chronic demyelinating disease of the CNS with assumed autoimmune etiology. Human herpes viruses have probable effects on relapsing-remitting MS pathogenesis presumably through molecular mimicry and/or bystander mechanisms. In this study we probed the possible contribution of the two herpes viruses, human herpesvirus 6 (HHV-6) and human herpesvirus 8 (HHV-8), in clinically definite multiple sclerosis (CDMS) pa-tients-relapsing remitting type (RRMS) during clinical exacerbations. All patients had no history of immune modulating or suppressing drugs intake in the last 6 months. The peripheral blood samples, from CDMS patients (n = 20) (13F/7M, age (y) = 30.3 ± 3.21) and other immune mediated neurological disorders (OIND) (11F/9M, age = 25.2 ± 12.1), (My-asthenia Gravis, Guillain Barré Syndrome, ischemic stroke in adolescent and young adult with no clear risk factors), as a control group, had been enrolled within 15 months (January-2007-- March -2008). We investigated the existence of specific deoxyribonucleic acid (DNA) sequences belonging to HHV-6 and HHV-8, using polymerase chain reaction (PCR) in the isolated peripheral blood mononuclear cells (PBMCs) and in plasma. PCR demonstrated HHV-6 DNA in 7 cases (35%), HHV-8 sequences in only one cases (5%) in PBMCs from 20 relapsed CDMS patients; all HHV-6 posi-tive cases showed positive plasma results, while the blood samples from 20 OIND patients showed negative results ex-cept one case (5%) out of 9 cases of GBS was positive for HHV-8 in PBMCs. We consequently concluded that there is considerable evidence in this study that proposed the roles of HHV-6 and HHV-8 in MS pathogenesis and clinical ex-acerbation.
Observation on Baseline Sensitivity of Erysiphe necator Genetic Groups to Azoxystrobin  [PDF]
Hajaj Ramadan Hajjeh
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.311199
Abstract: Powdery mildew, caused by Erysiph necator, is a common and severe fungal disease of grapevine all over the world. The disease costs millions of dollars to vine growers, due to intensive use of fungicides and yield losses. Recently in population of E. necator two genetic groups have been described, the two groups seem to occupy different temporal niches, with a temporal alternation that is clear-cut in vineyards intensively treated with chemical fungicides. QoI-STAR (Quinol Outside Inhibitors-Strobilurin Type of Action and Resistance) fungicides are widely used to control the disease, and generally carry a high risk of pathogen resistance development. To clarify the behaviors of the biotrophic fungus when treated with azoxystrobin as a representative of QoI-STAR, baseline sensitivity of laboratory isolates were determined. A leaf bioassay and the primers RSCBF1 and RSCBR2 designed on the highly conserved regions of cytb gene in fungi were used. Partial sequence of E. necator cytb gene were obtained. Attempts to obtain a laboratory mutant were not totally successful. The sensitivity to azoxystrobin (EC50) in isolates of genetic group B was significantly higher than in isolates of group A, to which all the isolates collected later in the season belonged. The higher sensitivity to azoxystrobin fungicides observed in group B isolates can be at the basis of their precocious disappearance in vineyards, and can have important implications for powdery mildew control strategies.
A Study on Developing the Role of Human Resource Information Systems for Good Leadership  [PDF]
Harini Methuku, Hatim Ramadan
American Journal of Industrial and Business Management (AJIBM) , 2013, DOI: 10.4236/ajibm.2013.35057
Abstract:

The research is a human and context oriented study in the field of information systems (IS), human resource information systems (HRIS), leadership, human resource management (HRM) and tacit knowledge are focused in the study. HRIS and leadership are two main concepts of the research, whereas HRM provides an application area and managerial activities of leadership for HRIS. Tacit knowledge is used to describe and interpret actions that make leadership activities, sensitive and successful. The theoretical framework consists of when thinking and acting in the current way, what kind of information systems it produces, and when thinking and acting in another way, what kind of information systems it creates. The framework has its base on thinking and acting in a conventional, routine and stereotyped way, which hinders the process of observing, finding out, applying and using alternative thoughts and actions although they might provide useful and innovative solutions or activities for IS design. The main idea is to understand, interpret and to describe the phenomenon of the activities of good leadership and the phenomenon of the role of HRIS in the case organizations.

On Mutually Orthogonal Graph-Path Squares  [PDF]
Ramadan El-Shanawany
Open Journal of Discrete Mathematics (OJDM) , 2016, DOI: 10.4236/ojdm.2016.61002
Abstract:

A decomposition \"\" of a graph H is a partition of the edge set of H into edge-disjoint subgraphs \"\". If \"\" for all \"\", then G is a decomposition of H by G. Two decompositions \"\" and \"\" of the complete bipartite graph \"\" are orthogonal if, \"\"for all \"\". A set of decompositions \"\"of \"\" is a set of k mutually orthogonal graph squares (MOGS) if \"\" and \"\" are orthogonal for all \"\" and \"\". For any bipartite graph G with n edges, \"\"denotes the maximum number k in a largest possible set \"\" of MOGS of \"\" by G. Our objective in this paper is to compute \"\" where \"\" is a path of length d with

Influence of Semi-Solid Isothermal Heat Treatment on Microstructure and Mechanical Properties of Ductile Cast Iron  [PDF]
Mohamed Ramadan, Naglaa Fathy
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2014, DOI: 10.4236/jmmce.2014.21005
Abstract: In this research, the effect of semi-solid isothermal heat treatment on microstructure, hardness and impact toughness of ductile iron (DI) is studied. Heat-treated air-cooled ductile iron shows spheroid graphite, cementite and fine pearlite matrix structure. At the early stages of heating time (up to 20 min), the DIs show significant decrease in amounts of graphite and significant increase in amounts of cementite. By increasing heating time, above 20 min, the DIs show slightly decrease in amounts of graphite and slightly increase in amounts of cementite. Hardness values increase by increasing heating time. Meanwhile, the impact toughness decrease with increasing heating time. The optimum heating treatment condition for reasonable structure and mechanical properties could be achieved at the temperature of 1165℃ for the heating time range of 10 to 15 min.
Unusual Catalytic Process Involving OH and NH Exchange  [PDF]
Ramadan M. Ramadan, Ahmad K. Abu Al-Nasr
International Journal of Organic Chemistry (IJOC) , 2012, DOI: 10.4236/ijoc.2012.21011
Abstract: Interaction of some transition metals species with a Schiff base, 1, derived from 4,6-diacetylresorcinol and 2-amino- 5-methylphenol (1:2 mole ratio) yielded the two compounds 4-ethanimidoyl-6-[(1E)-N-(2-hydroxy-4-methylphenyl) ethanimidoyl]benzene-1,3-diol, 2, and 4,6-diacetyl-1,3-diaminobenzene, 4 via unusual catalytic process involving OH and NH exchange. All the compounds are characterized by elemental analysis, IR, mass and 1H NMR. The structure of the two compounds 2 and 4 are also determined by X-ray analysis. The crystal structure analysis revealed that the two compounds crystallized in the monoclinic space group P21/c with a Z value of 4.
Are the Criteria for Health and Safety Available in Adjustable Saudi School Furniture?  [PDF]
Khalid Al Saleh, Mohamed Ramadan
iBusiness (IB) , 2011, DOI: 10.4236/ib.2011.32027
Abstract: This research investigated the effect of adjustable Saudi chair-table combinations available in the local market on the students' health and safety. Thirty seven young students participated in this research. Ten chair-table combinations, within three different activities (reading, writing, and looking at the blackboard), were the independent variables. Normalized discomfort ratings, and neck dorsal and upper trapezius muscular activities were the dependent variables. Variances among students' body dimensions and classroom furniture were also studied. There were higher levels of neck dorsal and upper trapezius muscular contractions associated with less dimensions of chair-table combinations compared to high dimensions of chair-table combinations. Normalized discomfort ratings at the neck, shoulder, thigh, and feet were significantly higher at high chair-table dimensions. Matched school furniture to the student dimensions was associated with low dimensions of chair-table combinations. The suitability of the local adjustable chair-table combination was not fit to the students’ health. Saudi furniture industry should review and provide the local schools with the most appropriate furniture to Saudi students’ anthropometric dimensions.
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