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Wear properties of ECAP-processed ultrafine grained Al-Cu alloys
Abd El Aal, M.I.,El Mahallawy, N.,Shehata, F.A.,Abd El Hameed, M.,Yoon, E.Y.,Kim, H.S. Elsevier Sequoia 2010 Materials science & engineering. properties, micro Vol.527 No.16
The wear properties of equal channel angular pressing (ECAP) Al-2, 3 and 5%Cu alloys under dry sliding conditions using different sliding distances and loads were investigated by pin-on-disc dry sliding wear tests. The wear mass loss decreased remarkably as the number of ECAP passes and Cu content increased, being affected more by the sliding distance than by the applied load under the experimental conditions. The wear mechanism was observed to be adhesive and delamination initially, and an abrasive mechanism also appeared as the sliding distance increased. The analysis of the wear surface indicates a transfer of Fe from the rotating disc to the Al-Cu alloy pin with increases in the sliding distance, the applied load, the number of passes and the copper content.
Tensile Properties and Fracture Characteristics of ECAP-Processed Al and Al-Cu Alloys
Mohamed Ibrahim Abd El Aal,Nahed El Mahallawy,Farouk A. Shehata,Mohamed Abd El Hameed,윤은유,이정환,김형섭 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.5
In the present paper, billets of pure Al, and cast-homogenized Al-2 wt.%, 3 wt.%, and 5 wt.% Cu alloys were successfully processed by equal channel angular pressing (ECAP) up to 10 passes without fracture at room temperature using a die with a channel angle of 110o. Giant strains imposed on workpieces lead to extreme dislocation densities, microstructural refinement, and finally ultrafine grained materials. Tensile tests were employed to examine the fracture modes and fracture surface morphologies of the ECAP-processed Al and Al-Cu alloy samples. In particular, the effects of the number of ECAP passes and the Cu content were investigated.
El-Domiaty, Maher M.,Abdel-Aal, Mahmoud M.,El-Shafae, Azza M. The Korean Society of Pharmacognosy 1996 Natural Product Sciences Vol.2 No.2
Four polymethoxyfavones were isolated from the leaves of Citrus deliciosa, three of which (nobiletin, 5-O-demethylnobiletin, and tangeritin) are bioactive. The fourth (7,4'-dihydroxy-5,6,8,3'-tetramethoxyflavone) is reported for the first time in the genus Citrus and is a potential chemotaxonomic marker. The structures of these flavones were confirmed by analysing their spectral data and comparison with similar compounds. The previously reported $^{13}C$ NMR assignment of 5-O-demethylnobiletin has been revised on the basis of 2D NMR experiments (HETCOR, COSY, and COLOC). The chemotaxonomic value of the present finding is verified.
El Gaby, Mohamed S.A.,Kamal El Dean, Adel M.,Gaber, Abd El Aal M.,Eyada, Hassan A.,Al Kamali, Ahmed S.N. Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.8
Condensation of 4-cyano-5,6-dimethyl-3-pyridazinone 1 with aromatic aldehydes gave the novel styryl derivatives 2a-c. Refluxing of compound 2a with phosphorus oxychloride furnished 3-chloropyridazine derivative 3. Compound 3 was reacted with thiourea and produced pyridazine-3(2H)thione 4. Thieno[2,3-c]- pyridazines 5a-e were achieved by cycloalkylation of compound 4 with halocompounds in methanol under reflux and in the presence of sodium methoxide. Also, refluxing of compound 4 with N-substituted chloroacetamide in the presence of potassium carbonate afforded thienopyridazines 6a-e. Cyclization of compound 6 with some electrophilic reagents as carbon disulfide and triethyl orthoformate furnished the novel pyrimido[4',5':4,5]thieno[2,3-c]pyridazines 12 and 13a-c, respectively. Diazotisation of compound 6 with sodium nitrite in acetic acid produced the pyridazino[4',3':4,5]thieno[3,2-d][1,2,3]triazines 14a-c. Ternary condensation of compound 1, aromatic aldehydes and malononitrile in ethanol containing piperidine under reflux afforded the novel phthalazines 16a-c. Compound 3 was subjected to some nucleophilic substitution reactions with amines and sodium azide and formed the aminopyridazines 17a, b and tetrazolo[1,5-b]-pyridazine 19, respectively. The structures of the synthesized compounds were established by elemental and spectral analyses.
Abd El Aal, Mohamed Ibrahim,Yong Um, Ho,Yoo Yoon, Eun,Seop Kim, Hyoung Elsevier 2015 Materials science & engineering. properties, micro Vol.625 No.-
<P><B>Abstract</B></P> <P>In this paper, billets of Al-1080 were successfully processed by ECAP up to 1 pass, and a combination of ECAP + extrusion with extrusion ratios of 2 and 8 through a newly designed integrated die at room temperature. The combination of ECAP + extrusion processes was observed to produce finer grain sizes with greater fractions of high angle grain boundaries (HAGBs) than the ECAP. The average grain size was further decreased and the fraction of high angle grain boundaries (HAGBs) was increased with the increase of the extrusion ratio. Direct extrusion after ECAP enhanced the mechanical properties (tensile strength and hardness) with conserving reasonable degree of ductility (elongation %). ECAP and ECAP + extrusion processed samples, showed large dimple size in the tensile fracture surfaces with clear ductile fracture mode.</P>
Alaa El din-Abdel Aal Moubasher,Emad Abdelrehim Taha,Ehab Mohamed Elnashar,Ahmed Abdel Aal Abdel Maged,Asmaa Mohamed Zahran,Heba Hassan Sayed,Hisham Diab Gaber 대한생식의학회 2021 Clinical and Experimental Reproductive Medicine Vol.48 No.1
Objective: This study was conducted to investigate the relationship of semen parameters in samples used for intracytoplasmic sperm injection (ICSI) with fertilization and pregnancy rates in infertile couples.Methods: In this prospective study of Infertile couples with male factor infertility that had undergone ICSI, fractions of the same semen samples obtained for microinjection (to ensure the best predictability) were evaluated to determine the semen parameters and sperm DNA fragmentation index (DFI) on the day of oocyte recovery.Results: In total, 120 couples completed the study and were subdivided into fertilized (n=87) and non-fertilized couples (n=33). The fertilized couples were further classified into pregnant (n=48) and non-pregnant (n=39) couples. Compared to non-fertilized and non-pregnant couples, fertilized and pregnant couples showed statistically significantly higher sperm viability and percentage of normal sperm morphology, as well as significantly lower sperm DFI values. A receiver operating characteristic curve analysis of data from the 120 ICSI cycles showed that sperm viability, normal sperm morphology percentages, and sperm DFI were significant prognostic indicators of fertilization at cutoff values of 40%, 7%, and 46%, respectively. A sperm DFI of 46% showed sensitivity and specificity of 95% and 90%, respectively, for predicting fertilization, and no clinical pregnancies occurred in couples with a sperm DFI above 46%.Conclusion: Semen parameters from the ICSI day sample, especially sperm viability, normal morphology, and DFI, had an impact on fertilization and pregnancy outcomes in ICSI cycles.
Recycling of AlSi8Cu3 alloy chips via high pressure torsion
Abd El Aal, M.I.,Yoo Yoon, E.,Seop Kim, H. Elsevier Sequoia 2013 Materials science & engineering. properties, micro Vol.560 No.-
In this paper, AlSi8Cu3 alloy chips were consolidated via HPT at an applied pressure 8GPa for 10 revolutions at room temperature. The microstructure and hardness of the HPT consolidated chips were investigated and compared with those of the HPT processed solid AlSi8Cu3 alloy samples and cold compacted chip samples. The HPT process successfully resulted in fully densified bulk samples with a higher microhardness due to the finer Al matrix grains and Si particles sizes with more grain boundaries with high angles and more homogeneous deformation than those in the HPT processed solid AlSi8Cu3 alloy samples due to the higher imposed total strain.
Nadia Abdel Aal,M. Bououdina,A. Hajry,A. A. Chaudhry,J. A. Darr,A. A. Al-Ghamdi,E. H. El-Mossalamy,Attieh A. Al-Ghamdi,YongKielSung,Farid El-Tantawy 한국생체재료학회 2011 생체재료학회지 Vol.15 No.2
Hydroxyapatite(HAP) nanoparticles were successfully prepared from the biowaste chicken eggshells and phosphoric acid solution by chemical precipitation methods. The structures of HAP were characterized in terms of the X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform-infrared (FT-IR) spectroscopy. The effect of temperature on the crystallinity and lattice parameters of prepared HAP was monitored by X-ray powder diffraction. Energy dispersive X-ray analysis revealed that the HAP had a Ca/P molar ratio of about 1.65 and 1.69for as prepared and sintered HAP at 1200oC (1 hour), respectively. The temperature dependence on the electrical conductivity of sintered HAP nanoparticle was investigated. Furthermore, dielectric properties such as dielectric constant and dielectric loss as a function of frequency for the sintered HAP were also studied.