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Search Results: 1 - 10 of 461439 matches for " Abdelrahman A. Elbadawi "
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Effect of the Cation Size Disorder at the A-Site on the Structural Properties of SrAFeTiO6 Double Perovskites (A = La, Pr or Nd)  [PDF]
Abdelrahman A. Elbadawi, O. A. Yassin, Mohamed A. Siddig
Journal of Materials Science and Chemical Engineering (MSCE) , 2015, DOI: 10.4236/msce.2015.35003
Abstract: In this paper, the cation size disorder effect of the A-site on the structural properties of the SrAFe- TiO6 (A = La, Pr or Nd) was investigated. The compounds were synthesized—as the best of our knowledge—for the first time by conventional and precursor method to get crystalline materials. The results obtained from the experimental measurements carried out on new double perovskite materials were presented. The data of X-ray diffraction (XRD), Fourier Transform Infra Red FTIR were measured at room temperature. From the X-ray diffraction, and by means of standard Rietiveld method, all the samples have the same structure (orthorhombic) with Pnma space group. The difference in the tolerance factor is clearly noticed and refers to the cation size disorder at the A-sites. The Fourier Transform Infra Red FTIR measurement has been done; the results of it confirm the double perovskite structure and the difference between the samples were noticed. The tolerance factors for the samples altered from SrLaFeTiO6 up to SrNdFeTiO6 and this difference return to ionic radius and cation size effect.
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.
The Effect of Replacement of Zn 2+ Cation with Ni 2+ Cation on the Structural Properties of Ba sub>2Zn sub>1–x Ni sub>xWO sub>6 Double Perovskite Oxides (X = 0, 0.25, 0.50, 0.75, 1)  [PDF]
Yousif A. Alsabah, Abdelrahman A. Elbadawi, Eltayeb M. Mustafa, Mohamed A. Siddig
Journal of Materials Science and Chemical Engineering (MSCE) , 2016, DOI: 10.4236/msce.2016.42007
Abstract: The Ba2Zn1-xNixWO6 double perovskite oxides were synthesized using solid state reaction method. The effect of replacement of Zn2+ with Ni2+ cation on the structural properties was investigated by X-ray diffraction (XRD) at room temperature. From the X-ray diffraction and by means of standard Rietiveld method, the samples showed the same cubic crystal structure with (Fm-3m) space group and the crystallite size ranging from 71.91 nm to 148.71 nm. The unit cell volume was found to decrease as a result of the replacement, while there was no significant difference in the value of tolerance factor of the samples. This is may be due to the convergence of ionic radii of Ni2+ and Zn2+ cations. The Fourier Transform Infrared Spectroscopy (FTIR) was performed for the samples and the resultant characteristic absorption bands confirmed the double perovskite structure.
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.
Characterization of the Crystal Structure of Sesame Seed Cake Burned by Nd: YAG Laser  [PDF]
Muna A. Pn Gawbah, Abdelrahman A. Elbadawi, Yousef A. Alsabah, Mohammed U. Orsod, Ali A. S. Marouf
Journal of Materials Science and Chemical Engineering (MSCE) , 2018, DOI: 10.4236/msce.2018.64013
Abstract: This paper reports obtaining of useful and high-value materials from sesame seed cake (SSC). For this purpose, SSC sample was burned for 30 s using Nd: YAG laser with output power 60 W. The products of this process and non-burned SSC were characterized by X-ray diffractometer (XRD), energy dispersive x-ray (EDX) and Fourier transform infrared (FTIR) so as to investigate its crystal structure and chemical components. XRD results of the SSC before burning process showed amorphous silica, rhombohedral phase of carbon, monoclinic phase of aluminum chloride, the hexagonal phase of moissanite-4H, (yellow, black) and hexagonal phase of graphite-2H, C (black). While the results of the burned SSC sample showed that the burning process using the power of Nd: YAG laser cased in appearing of crystalline hexagonal phase for silica and Carbon Nitride and converting the rhombohedral phase of Carbon into hexagonal phase. FTIR showed a number of absorbance peaks assigned to silica.
Indirect Speculative Attacks and the Black Market for Foreing Exchange: The Example of Sudan Indirect Speculative Attacks and the Black Market for Foreing Exchange: The Example of Sudan
Ibrahim A. Elbadawi
Revista de Análisis Económico (RAE) , 1993,
Abstract: Indirect Speculative Attacks and the Black Market for Foreing Exchange: The Example of Sudan The paper extends the recent literature on collapsing exchange roles and balance of payment crises to the case when currency inconvertibility gives rise to the emergence of an "illegal" black market. The presence of the black market generates indirect speculative attacks on the official reserves because, due to inconvertibility, agents cannot directly buy official reserves. The paper derives several conditional probability statements regarding the likelihood of successful devaluation as a way to unify the official and black market exchange rates and achieve economic stabilization.
Possibility of using the beet dyes as a laser gain medium  [PDF]
Abdelaziz Hagar Abdelrahman, Malik A. Abdelrahman, Mohammed Khaled Elbadawy
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.511144

Nowadays the dye lasers play as an important tool and are used in many applications including spectroscopy, medicine and dermatology. This research was carried out to study the possibility of using the beet dyes as a laser gain medium. The fluorescence quantum yield was determined by the comparative method with rodamine b as an organic dye standard. The value of the fluorescence quantum yield was found about (0.14) and the fluorescence quantum yield was developed until reaching about (0.323). The increasing of fluorescence quantum yield of dye solution as a result of increasing the viscosity of solvent was observed clearly. The study concluded that the beet dyes are so sensitive to fluorescence and it is very suitable to be used as a laser gain medium.

Multiresolution Video Watermarking Algorithm Exploiting the Block-Based Motion Estimation  [PDF]
Salwa A. K. Mostafa, Abdelrahman Ali
Journal of Information Security (JIS) , 2016, DOI: 10.4236/jis.2016.74021
Abstract: This paper presents a novel technique for embedding a digital watermark into video frames based on motion vectors and discrete wavelet transform (DWT). In the proposed scheme, the binary image watermark is divided into blocks and each watermark block is embedded several times in each selected video frame at different locations. The block-based motion estimation algorithm is used to select the video frame blocks having the greatest motion vectors magnitude. The DWT is applied to the selected frame blocks, and then, the watermark block is hidden into these blocks by modifying the coefficients of the Horizontal sub-bands (HL). Adding the watermark at different locations in the same video frame makes the scheme more robust against different types of attacks. The method was tested on different types of videos. The average peak signal to noise ratio (PSNR) and the normalized correlation (NC) are used to measure the performance of the proposed method. Experimental results show that the proposed algorithm does not affect the visual quality of video frames and the scheme is robust against a variety of attacks.
An overwhelming post-splenectomy infection (OPSI)
Elbadawi O,Ali SR,Waheed A,Khan S
Journal of Emergency Medicine, Trauma and Acute Care , 2012, DOI: 10.5339/jemtac.2012.13
Abstract: We present the case of a 25 year old man who had a splenectomy five years previously following a road traffic accident (RTA). He presented to our A&E department one evening with fever and upper abdominal pain associated with nausea and vomiting. Clinical examination was unremarkable. Initial investigations revealed only pyuria. He was treated symptomatically along with parenteral antibiotic and admitted to the general medical ward. Within few hours he deteriorated rapidly with septic shock, multi-organ failure, disseminated intravascular coagulation (DIC) and eventually cardio-respiratory arrest. Despite all resuscitative measures he died within few hours of admission. Splenectomized patients are prone to develop severe infection, including sepsis and meningitis, due to OPSI, or overwhelming post-splenectomy infection. Presentation may be mild, but the course is rapid and the prognosis is very poor, even in young people. It is important that splenectomized patients receive vaccines according to guidelines, take antibiotic prophylaxis and are educated to seek medical attention at the earliest sign of even minor infections.
The Role of CeO2-Doping of Fe2O3/Co3O4 System on Its Structural Characteristics  [PDF]
Neven A. Hassan, Gehan A. Fagal, Abdelrahman A. Badawy, Gamil A. El-Shobaky
Open Journal of Applied Sciences (OJAppS) , 2013, DOI: 10.4236/ojapps.2013.31013

The role of ceria doping (0.75 - 3 mol%) on solid-solid interactions between ferric and cobaltic oxides was investigated. The investigated solids were characterized by TGA, DTA, XRD and HRTEM. The results revealed that ceria much enhanced the formation of nanosized CoFe2O4 (10 - 30 nm). The stimulation effect of ceria towards cobalt ferrite formation was evidenced from analysis of DTA and XRD investigations. In fact, the area of endothermic peak located at 575- 680relative to solid-solid interaction between ferric and cobaltic oxide increased by increasing the dopant concentration. This treatment decreased the activation energy of formation of the produced ferrite from 33 - 9.2 kJ/mol upon doping with 3 mol% CeO2. HRTEM analysis revealed the formation of homogenous nanosized CoFe2O4. The formation effect of ceria dopant towards the formation of CoFe2O4 has been tentatively attributed to an effective increase in the mobility of the reacting cations.

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