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Search Results: 1 - 10 of 96468 matches for " Abdalrawf I. Ahmed "
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Structural and Optical Properties of Mg1-x Znx Fe2 O4 Nano-Ferrites Synthesized Using Co-Precipitation Method  [PDF]
Abdalrawf I. Ahmed, Mohamed A. Siddig, Abdulmajid A. Mirghni, Mohamed I. Omer, Abdelrahman A. Elbadawi
Advances in Nanoparticles (ANP) , 2015, DOI: 10.4236/anp.2015.42006
Abstract: In this work, the Mg1-x Znx Fe2 O4 Nanoferrites (where x = 0.0, 0.2, 0.4, 0.6 and 0.8) was synthesized using co-precipitation method. The investigation of structural and optical properties was carried out for the synthesized samples using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Ultraviolet visible spectrophotometer (UV-Vis). XRD revealed that the structure of these nanoparticles is spinel with space group Fd3m and crystallite size lies in the range 21.0 - 42.8 nm. Lattice parameter was found to increases with Zn concentration and this may be due to the larger ionic radius of the Zn2+?ion. FTIR spectroscopy confirmed the formation of spinel ferrite and showed the characteristics absorption bands around 612, 1146, 1404, 1649 and 3245 cm-1. The energy band gap was calculated for samples with different ratio and was found to be 4.77, 4.82, 4.86, 4.87 and 4.95 eV. The substitution was resulted in slight increased in the lattice constant and that sequentially may lead to the slightly decreased in the energy gap.
Effect of Cu2+ Doping on Structural and Optical Properties of Synthetic Zn0.5CuxMg0.5-xFe2O4 (x = 0.0, 0.1, 0.2, 0.3, 0.4) Nano-Ferrites  [PDF]
Badawi M. Ali, Mohamed A. Siddig, Yousef A. Alsabah, Abdelrahman A. Elbadawi, Abdalrawf I. Ahmed
Advances in Nanoparticles (ANP) , 2018, DOI: 10.4236/anp.2018.71001
Abstract: The samples of Zn0.5CuxMg0.5-xFe2O4 nanoparticle ferrites, with x= 0.0, 0.1, 0.2, 0.3, 0.4 were successfully synthesised. Structural and optical properties were investigated by X-ray Diffraction (XRD), Fourier Transform Infrared spectros-copy (FTIR) and UV-visible spectroscopy. The structural studies showed that all the samples prepared through the Co-precipitation method was a single phase of a face-cantered-Cubic (FCC) spinel symmetry structures with space group (SG): Fd-3m. In the series Zn0.5CuxMg0.5-xFe2O4, the lattice parameter was found to be 8.382 ? for x = 0 and was found to increase with copper con-centration. The grain size obtained from the XRD data analyses was found to be in the range of 15.97 to 28.33 nm. The increased in the grain size may be due to the large ionic radius of Mg2+ (0.86 ?) compared with Cu2+ (0.73 ?). The FTIR spectroscopy confirmed the formation of spinel ferrite and showed the characteristics absorption bands around 580, 1112, 1382, 1682, 1632 and 2920 cm-1. The energy band gap was calculated for samples were found to be in the range 4.04 to 4.67 eV.
Vitamin D Status, C-Reactive Protein and Risk of Coronary Artery Disease—A Hospital-Based Study  [PDF]
Adham I. Ahmed
Pharmacology & Pharmacy (PP) , 2014, DOI: 10.4236/pp.2014.513125
Abstract: Coronary artery disease (CAD) is a leading cause of deaths of women and men worldwide. In this study we tried to assess the relationship between Vitamin D status and CAD. Vitamin D has a big role in the body and debate on its effect on the heart and coronary arteries still exits. C-reactive protein (CRP) is an inflammatory marker which may rise in CHD. Aim: To determine the relationship between Vitamin D status and CRP and CAD risk among patients at middle zone of the Gaza Strip. Methodology: A retrospective case-control, hospital-based study was conducted at Al-Aqsa Martyr’s Hospital in Dier El-Balah City from August 2014 to October 2014. Patients (n = 100) aged above 40 years with confirmed CAD history were recruited using a purposeful, non-random sampling. Vitamin D status assessed by food frequency questionnaire of dietary Vitamin D and serum Vitamin D. Serum Vitamin D was measured using Calbiotech’s 25-OH Vitamin D ELISA and serum CRP was measured by the latex agglutination. SPSS V.19 used for data analysis. Results: Mean of age among cases was (68.28 ± 8.01) higher than controls (57.82 ± 9.61) (P = 0.01); percent of males (54%) was higher than females (46.0%) among cases. Sun exposure and mean duration of daily exposure to sunlight were higher in cases (P > 0.05). Cases were consumed less servings of Vitamin D rich food than controls (P > 0.05). Percent of Vitamin D deficiency among cases (42%) was higher than controls (16.0%) (P = 0.002). Mean of serum Vitamin D in association with positive CRP was (79.95 ± 70.6) lower than those with negative CRP (106.06 ± 68.966) (P = 0.13). Percent of positive serum CRP among cases 30% was higher than controls 10% (P = 0.01). Conclusion: Vitamin D deficiency was associated with positive CRP in patients with CAD. Vitamin D may have an anti-inflammatory effect regarding to our results.
Generalized Order Statistics from Generalized Exponential Distributions in Explicit Forms  [PDF]
Hazem I. El Shekh Ahmed
Open Journal of Statistics (OJS) , 2013, DOI: 10.4236/ojs.2013.32014
Abstract:

The generalized order statistics which introduced by [1] are studied in the present paper. The Gompertz distribution is widely used to describe the distribution of adult deaths, and some related models used in the economic applications [2]. Previous works concentrated on formulating approximate relationships to characterize it [3-5]. The main aim of this paper is to obtain the distribution of single, two, and all generalized order statistics from Gompertz distribution with some special cases. In addition the conditional distribution of two generalized order statistics from the same distribution is obtained. The Gompertz distribution has a continuous probability density function with location parameter a and shape parameter b, \"\", where x restricted by the interval\"\" . The nth moment generated function of the Gompertz distributed random variable X is given on the form: \"\" where,

Evaluating Reference Crop Evapotranspiration (ETo) in the Centre of Guanzhong Basin—Case of Xingping & Wugong, Shaanxi, China  [PDF]
Hussein I. Ahmed, Junmin Liu
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.55055
Abstract: In this paper, the Penman-Monteith method was applied to evaluate the reference crop evapotranspiration. A reliable estimation of the reference evapotranspiration (ETo) is of critical importance and required accurate estimates to close the water balance. The aim of this paper is estimating the reference evapotranspiration (ETo) as preliminary to use for groundwater modeling in the area. Based on FAO-Penman-Monteith method, ETo calculator software was applied. Meteorological data within this study were obtained from two gauges stations (Xing ping and Wu gong) and available literatures. The results indicated that the values of ETo for a period (1981-2009)29 yearsin two stations approximately the same. Specifically, is ranged between 0.4 - 6.9 mm /day, 0.4 - 6.7 mm/day and the average value is 2.6 mm/ day, 2.6 mm/day in Xing ping and Wu gong respectively. In addition, the maximum values were occurred in summer season (May, June and July). The result also found that the correlation coefficient ≈ 1. Moreover, “ETo” was increasing by recent years. The reference crop evapotranspiration for some crops were calculated.
Simultaneous Bilateral Spontaneous Pneumothorax: Report of 6 Adult Patients  [PDF]
Ahmed I. Al-Azzawi
World Journal of Cardiovascular Surgery (WJCS) , 2015, DOI: 10.4236/wjcs.2015.52004
Abstract: Background: Spontaneous pneumothorax (SP) refers to the spontaneous presence of air in the pleural sac(s) without iatrogenic or traumatic factors. The simultaneous bilateral SP (SBSP) is rare yet serious clinical condition which may pose a significant threat to patient’s life. Herein, 6 patients with SBSP managed in Sulaimaniyah Teaching Hospital (STH) over 6-year period (2006-2011) are reported with literature review. Methodology: A prospective clinical study. The diagnosis was made on clinical and radiographic grounds. The initial therapy was a bilateral tube thoracostomy (BTT) followed by chemical pleurodesis. Thoracotomy for excision of subpleural blebs or bullae and pleurectomy was performed for prolonged air leak (lasting >14 days). Results: There were 5 males (83.33%) and 1 female (16.67%) with a mean age of 34.8 years ranging between 20 and 50. All patients had presented with dyspnea and chest pain and were smokers. Three patients (50%) had primary (PSP) whereas the remaining had secondary (SSP) (chronic obstructive pulmonary disease—COPD, n = 2 and pneumonia, n = 1). None of the patients had recurrence. Unilateral thoracotomy was necessary in 5 patients (SSP, n = 3 and PSP, n = 2). Prolonged air leak was observed once postoperatively (16.7%) while mortality was nil. Conclusions: Prompt recognition of this rare yet potentially serious condition is crucial. The clinical diagnosis is straightforward with plain chest radiography being the most helpful workup. The initial therapy is via BTT followed by pleurodesis. Surgery is necessary for prolonged air leak and failure of the lung to expand.
Extraction of Aspirated Headscarf Pins with Fiberoptic Bronchoscopy  [PDF]
Ahmed I. Al-Azzawi
World Journal of Cardiovascular Surgery (WJCS) , 2017, DOI: 10.4236/wjcs.2017.712016
Abstract: Background: Foreign body aspiration is a common yet preventable health problem. Headscarf pin aspiration is a unique example of aspirated foreign bodies in young Muslim women usually removed using the rigid bronchoscope. However, the flexible bronchoscope is increasingly used for this purpose. This prospective study was conducted in Sulaimaniyah Teaching Hospital, Sulaimaniyah, Iraq and aimed to evaluate the usefulness of fiberoptic bronchoscope for removal of aspirated headscarf pins in view of the relevant literature. Methodology: Fifty female patients with headscarf pin aspiration were managed by fiberoptic bronchoscopy over an 8-year period (January 2008 to December 2015). The procedure was performed under local anesthesia and conscious sedation through the mouth. Results: The age ranged from 10 to 45 years with a mean of 27.5. All patients had cough, five had unilateral wheeze (10%) while haemoptysis occurred twice (4%). Fiberoptic bronchoscopy succeeded in 45 cases (90%). Rigid bronchoscopy under general anesthesia was necessary in (n = 4, 8%) while one patient (2%) required thoracotomy. Conclusion: Fiberoptic bronchoscopy is safe and effective in removal of aspirated headscarf pins and should be tried first.
Analysis of disc brake squeal using a ten-degree-of-freedom model
I Ahmed
International Journal of Engineering, Science and Technology , 2011,
Abstract: Disc brake squeal is considered as a highly main source of discomfort for passengers. It is also considered to be a high frequency noise when it is bigger than 1 kHz audible vibration of braking components. It is a significant problem in passenger vehicles that has not been solved satisfactorily until recently. Many manufacturers of brake pad materials spend up to fifty percent of their engineering budgets on noise, vibration and harshness (NVH) issues. Squeal noise is strongly correlated to the squeal index and degree of instability of the brake system assembly. Decreasing this squeal noise to some extent during braking is a very important matter for the comfort of passengers. So, a mathematical prediction model of 10-degree-of-freedom has been developed to study the effect of different brake components parameters on the degree of instability and squeal index of the brake system. The model has considered such factors as the distance between clamping bolts of the caliper, width and thickness of the friction material, which were not fully covered previously besides some other factors. Complex eigenvalue analysis by analytical program has been used to predict the unstable frequencies in the ventilated disc brake system assembly. It is evident from the analysis that Young’s moduli of the rotor and friction material have a great effect on the occurrence of squeal. The harder the friction material the bias of the brake to squeal. It is shown also that the squeal noise of the brake decreases with increasing semi-distance between the clamping bolts of the caliper to be at optimum value between 50-70 mm. However increasing the friction material thickness to 11 mm decreases the squeal index and instability of the system. The results have show that the predicted squeal tendency at varying all the studies parameters is as less as possible to be 43 % compared to other single parameters.
Investigation and Comparison of 2.4 GHz Wearable Antennas on Three Textile Substrates and Its Performance Characteristics  [PDF]
M. I. Ahmed, M. F. Ahmed, A. A. Shaalan
Open Journal of Antennas and Propagation (OJAPr) , 2017, DOI: 10.4236/ojapr.2017.53009
Abstract:
In this paper, two different methods were used for investigating the RF characteristics of three types of textile materials. Goch, Jeans and Leather substrates were studied. A microstrip ring resonator method and DAK (Dielectric Assessment Kit) method were used. Bluetooth antennas were designed and fabricated using these substrates. The results were compared for the two methods. The bending effect of these antennas on its impedance characteristics due to human body movements was also studied. Finally, all antennas were simulated by CST simulator version 2016, fabricated using folded cupper and measured by Agilent 8719ES VNA. The measured results agree well with the simulated results.
Effect of Zirconium Oxide Nano-Fillers Addition on the Flexural Strength, Fracture Toughness, and Hardness of Heat-Polymerized Acrylic Resin  [PDF]
Mohamed Ashour Ahmed, Mohamed I. Ebrahim
World Journal of Nano Science and Engineering (WJNSE) , 2014, DOI: 10.4236/wjnse.2014.42008
Abstract:

Purpose: The mechanical strength of polymethyl methacrylate (PMMA) remains far from ideal for maintaining the longevity of denture. The purpose of this study was to evaluate the effect of Zirconium oxide (ZrO2) nanofillers powder with different concentration (1.5%, 3%, 5% and 7%) on the flexural strength, fracture toughness, and hardness of heat-polymerized acrylic resin. Materials and methods: Zirconium oxide powders with different concentrations (1.5%, 3%, 5% and 7%) were incorporated into heat-cure acrylic resin (PMMA) and processed with optimal condition (2.5:1 Powder/monomer ratio, conventional packing method and water bath curing for 2 hours at 95C) to fabricate test specimens of PMMA of dimensions (50 × 30 × 30 mm) for the flexural strength, fracture toughness, and (50 × 30 × 30 mm) were fabricated for measuring hardness. PMMA without additives was prepared as a test control. Three types of mechanical tests; flexural strength, fracture toughness and hardness were carried out on the samples. The recorded values of flexural strength in (MPa), fracture toughness in (MPa.m1/2), and hardness (VHN) were collected, tabulated and statistically analyzed. One way analysis of variance (ANOVA) and Tukey’s tests were used for testing the significance between the means of tested groups which are statistically significant when the P value ≤ 0.05. Results: Addition of Zirconium oxide nanofillers to PMMA significantly increased the flexural strength, fracture toughness and hardness. Conclusion: These results indicate that Zirconium oxide nanofillers added to PMMA has a potential as a reliable denture base material with increased flexural strength, fracture toughness, and hardness. According to the results of the present study, the best mechanical properties were achieved by adding 7%wt ZrO2 concentration.

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