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Effect of different metal sulfate precursors on structural and catalytic performance of zirconia in dehydration of methanol to dimethyl ether

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燃料化学学报 2018年第1期46卷 67-74页

作者： Abd el-Aziz A.Said mohamed Abd el-Aal Chemistry Department Faculty of ScienceAssiut University71516 AssiutEgypt

ZrO_2 was treated with 10% SO_4^(2-) from different metal sulfate precursors for methanol dehydration to dimethyl *** the samples exhibited tetragonal phase and no diffraction peaks corresponding to metal sulfates or metal oxides were *** FT-IR results revealed that there were different interactions between sulfate and ZrO_2,and this had a great effect on the surface area of the *** catalytic activity was measured over the catalysts in the temperature range of 100-300 ℃.The results revealed that sulfated zirconia with CuSO_4·5 H_2O and Al_2(SO_4)_3·16 H_2O showed the best catalytic *** maximum yield of DME ≈87% was obtained over CuSZ at a reaction temperature of 275 ℃.Moreover,the catalytic activity of the catalysts was correlated well with their surface acidity that measured by dehydration of isopropanol.

关键词： MSO 4/ZrO2 甲醇脱水 DME

Strong Band-Edge Emission from ZnS Quantum Dots Stabilized by Gum Arabic

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Chinese Physics Letters 2008年第12期25卷 4480-4481页

作者： Hatim mohamed el-Khair Dirar Department of Physics Faculty of Science and Technology Ai-Neelain University PO Pox 12702 Khartoum 11121 Sudan

ZnS quantum dots （QDs）, prepared by soft-condensation, exhibit robust structure of a quantum size equal 3.13 nm mediated two-dimensional gum Arabic surfactant as characterized by scan tunnelling microscope （STM）. Strong blue-shifted absorption and emission bands are depicted by optical characterization even for the sample stored under ambient condition for two weeks. These enhancements can be attributed to the completely passivated surface trap states by Gum Arabic.

关键词： field emission molybdenum dioxide enhancement factor

Advanced algorithms for retrieving pileup peaks of digital alpha spectroscopy using antlions and particle swarm optimizations

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Nuclear Science and Techniques 2020年第4期31卷 47-68页

作者： mohamed S.el_Tokhy Engineering Department NRCAtomic Energy AuthorityP.No.13759InshasEgypt

Optimization algorithms are applied to resolve the second-order pileup(SOP)issue from high counting rates occurring in digital alpha *** are antlion optimizer(ALO)and particle swarm optimization(PSO)*** optimization algorithms are coupled to one of the three proposed peak finder *** custom time-domain algorithms are proposed for retrieving SOP peaks,namely peak seek,slope tangent,and fast array *** addition,an average combinational algorithm is *** time occurrence of the retrieved peaks is tested for an elimination of illusive *** methods are inaccurate and *** and PSO optimizations are used for the localization of retrieved *** cost values that achieve the best fitness values are ***,the optimum positions of the detected peak heights are *** metrics of the optimized algorithms and their influences on the retrieved peaks parameters are *** among such algorithms are investigated,and the algorithms are inspected in terms of their computational time and average *** peak seek algorithm achieves the lowest average computational error for pulse parameters(amplitude and position).However,the fast array algorithm introduces the largest average error for pulse *** addition,the peak seek algorithm coupled with an ALO or PSO algorithm is observed to realize a better performance in terms of the optimum cost and computational *** contrast,the performance of the peak seek recovery algorithm is improved using the ***,the computational time of the peak optimization using the PSO is much better than that of the ALO *** a final conclusion,the accuracy of the peaks detected by the PSO surpasses that for the peaks detected by the *** implemented peak retrieval algorithms are validated through a comparison with experimental results from previous *** proposed algorithms achieve a notable pr

关键词： Alpha spectrometry instrument Second-order pileup Signal processing Optimization algorithms

Predictors of long-term survival after pancreaticoduodenectomy for peri-ampullary adenocarcinoma: A retrospective study of 5-year survivors

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Hepatobiliary & Pancreatic Diseases International 2018年第5期17卷 443-449页

作者： Ayman el Nakeeb mohamed el Sorogy Helmy Ezzat Rami Said mohamed el Dosoky mohamed Abd el Gawad Ahmed M elsabagh Ehab el Hanafy Gastroenterology Surgical Center Mansoura University

Background: Pancreaticoduodenectomy(PD) is the standard curative treatment for periampullary tumors. The aim of this study is to report the incidence and predictors of long-term survival( ≥ 5 years) after PD. Methods: This study included patients who underwent PD for pathologically proven periampullary adenocarcinomas. Patients were divided into 2 groups: group(I) patients who survived less than 5 years and group(II) patients who survived ≥ 5 years. Results: There were 47(20.6%) long-term survivors( ≥ 5 years) among 228 patients underwent PD for periampullary adenocarcinoma. Patients with ampullary adenocarcinoma represented 31(66.0%) of the long-term survivors. Primary analysis showed that favourable factors for long-term survival include age < 60 years old, serum CEA < 5 ng/mL, serum CA 19-9 < 37 U/mL, non-cirrhotic liver, tumor size < 2 cm, site of primary tumor, postoperative pancreatic fistula, R0 resection, postoperative chemotherapy, and no recurrence. Multivariate analysis demonstrated that CA 19-9 < 37 U/mL [OR(95% CI) = 1.712(1.24 8–2.34 8), P = 0.001], smaller tumor size [OR(95% CI) = 1.335(1.032–1.726), P = 0.028] and R0 resection [OR(95% CI) = 3.098(2.095–4.582), P < 0.001] were independent factors for survival ≥ 5 years. The prognosis was best for ampullary adenocarcinoma, for which the median survival was 54 months and 5-year survival rate was 39.0%, and the poorest was pancreatic head adenocarcinoma, for which the median survival was 27 months and 5-year survival rate was 7%. Conclusions: The majority of long-term survivors after PD for periampullary adenocarcinoma are patients with ampullary tumor. CA 19-9 < 37 U/mL, smaller tumor size, and R0 resection were found to be independent factors for long-term survival ≥ 5 years.

关键词： Pancreatic carcinoma Pancreatic head carcinoma Pancreaticodudenectomy Long-term survival

Impact of preprocessing on medical data classification

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Frontiers of Computer Science 2016年第6期10卷 1082-1102页

作者： Sarab ALMUHAIDEB mohamed el Bachir MENAI Computer Science Department College of Computer and Information Sciences Prince Sultan University Riyadh 11586 Saudi Arabia

The significance of the preprocessing stage in any data mining task is well known. Before attempting medical data classification, characteristics of medical datasets, including noise, incompleteness, and the existence of multiple and possibly irrelevant features, need to be addressed. In this paper, we show that selecting the right combination of prepro- cessing methods has a considerable impact on the classification potential of a dataset. The preprocessing operations con- sidered include the discretization of numeric attributes, the selection of attribute subset（s）, and the handling of missing values. The classification is performed by an ant colony optimization algorithm as a case study. Experimental results on 25 real-world medical datasets show that a significant relative improvement in predictive accuracy, exceeding 60% in some cases, is obtained.

关键词： classification ant colony optimization medical data classification preprocessing feature subset selection,discretization

Processing of Ceramic Based Nanocomposite Usingα-Al_2O_3 Powder and FeCl_2 Solution as Starting Materials

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Journal of Materials Science & Technology 2007年第6期23卷 837-842页

作者： mohamed M.el-Sayed Seleman Department of Materials and Metallurgical Engineering Faculty of Petroleum and Mining EngineeringPost Code 43721SuezEgypt

Alumina-iron nanocomposite powders were prepared by a two-step process. In the first step, α-Al2O3-FeCl2 powder mixture was formed by mixing α-Al2O3 powders with FeCl2 solution followed by drying. In the second step, the FeCl2 in the dry power mixture was selectively reduced to iron particles. A reduction temperature of 750℃ for 15 min in dry H2 was chosen based on the thermodynamic calculations. The concentration of iron in FeCl2 solution was calculated to be 20 vol. pct in the final composite. Two techniques were used to produce composite bulk materials. The Al2O3 nanocomposite powders were divided to two batches. The first batch of the produced mixture was hot pressed at 1400℃ and 27 MPa for 30 min in a graphite die. To study the effect of oxygen on the Al2O3/Fe interface bonding and mechanical properties of the composite, the second batch was heat treated in air at 700℃ for 20 min to partially oxidize the iron particles before hot pressing. Characterization of the composites was undertaken by conventional density measurements, X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM） and electron probe micro analysis （EPMA）. The suggested processing route （mixing, reduction and hot pressing） produces ceramic-metal nanocomposite much tougher than the pure Al2O3. The fracture strength of the produced Al2O3/Fe nanocomposite is nearly twice that of the pure Al2O3. The presence of spinel phase, FeAl204, as thick layer around the Fe particles in the Al2O3 matrix has a detrimental effect on interfacial bonding between Fe and AI203 and the fracture properties of the composite.

关键词： Ferrous chloride Reduction Alumina-iron nanocomposite Spinel phase

Effects of Nickel Distribution on the Strengthening and Toughening of Alumina Ceramics

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Journal of Materials Science & Technology 2008年第5期24卷 723-728页

作者： mohamed.M.el-Sayed Seleman Department of Materials and Metallurgical Eng. Faculty of Petroleum and Mining Eng.Post Code 43721SuezEgypt

Three types of composite materials were designed and fabricated by hot pressing powder blends of alumina with 20 vol. pct nickel particles. The composites differ in the shape, size and distribution of the nickel particles. Composite microstructures are described and measurements of density, hardness, flexure strength, and fracture toughness are reported. The results showed that the fracture strength of the composite with dispersed nickel particles is higher than the other two composites （network microstructure and mixed microstructure） and the alumina matrix. For all the composites studied, tougher materials than the monolithic alumina were produced. The fracture toughness of the composite with a network microstructure is much higher than that of the other composites. The toughening mechanisms were described based on the observation of the fracture surfaces and the crack-particle interactions. Moreover, the parameters for microstructural tailoring of these materials have been deduced. The toughening of the produced composites was explained in light of the interracial bond strength.

关键词： Alumina-nickel composites Nickel morphology Interfacial bonding Fracturetoughness Flexure strength

Experimental and numerical investigation of the abrasive waterjet machining of aluminum-7075-T6 for aerospace applications

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Advances in Manufacturing 2021年第2期9卷 286-303页

作者： Joseck Nyaboro Mahmoud Ahmed Hassan el-Hofy mohamed el-Hofy Department of Industrial and Manufacturing Engineering Egypt-Japan University of Science and Technology(E-JUST)Alexandria 21934Egypt Department of Energy Resources Engineering Egypt-Japan University of Science and Technology(E-JUST)Alexandria 21934Egypt Advanced Manufacturing Research Centre(AMRC)with Boeing The University of SheffieldRotherham S605TZUK

The machining of hard-to-cut materials with a high degree of precision and high surface quality is one of the most critical considerations when fabricating various state-of-the-art engineered *** this investigation,a comprehensive three-dimensional model was developed and numerically simulated to predict kerf profiles and material removal rates while drilling the aluminum-7075-T6 aerospace *** profile and material removal prediction involved three stages:jet dynamic flow modeling,abrasive particle tracking,and erosion rate *** investigations were conducted to validate the developed *** results indicate that the jet dynamic characteristics and flow of abrasive particles alter the kerf profiles,where the top kerf diameter increases with increasing jet pressure and standoff *** kerf depth and hole aspect ratio increase with jet pressure,but decrease with standoff distance and machining *** profiles were characterized by progressive edge rounding and parabolic *** can be minimized by utilizing high jet pressure and small standoff *** material removal rate increases with increasing jet pressure,abrasive particle size,and exposure time,but decreases with increasing standoff distance.

关键词： Non-traditional machining Abrasive waterjet machining Computational fluid dynamics(CFD) Erosion modeling Kerf characteristics

Salt response of the freshwater microalga Scenedesmus obliquus(Turp.)Kutz is modulated by the algal growth phase

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Journal of Oceanology and Limnology 2020年第3期38卷 802-815页

作者： Taha mohamed el-KATONY Magda Faiz el-ADL Department of Botany and Microbiology Faculty of ScienceDamietta UniversityNew Damietta City 34517Egypt

Growth and biochemical responses of the coenobial green alga Scenedesmus obliquus to salinity stress were monitored across different phases of *** alga was cultured on BG11 growth medium and subjected to 0,30,100,and 200 mmol/L NaCl for a period of 20 d,during which algal cultures were harvested at 4-d *** salinity-induced inhibition of algal growth was accompanied with prolongation of timing of the different growth *** sharp and progressive salinity-induced inhibition of algal growth rate during the early phase of growth points to salt shock but moderation of inhibition at the subsequent stages of growth means algal acclimation to *** concentrations of chlorophylls a and b,soluble sugars,proteins as well as those of K+and Na+in the alga exhibited peaks at the initiation of the exponential phase of growth,with increasing magnitude in proportion to the increase in the level of ***,whereas soluble sugars of the alga peaked at initiation of the exponential phase,starch concentration progressively increased with culture age,reaching saturation towards the stationary *** the salinity-induced increase in soluble sugars was most evident at the early stages of growth the reverse was true for *** present results point to fast acclimation of *** to salt stress post a brief salt shock,utilizing soluble sugars,K+and Na+for osmotic *** salinity from 0 to 200 mmol/L NaCl led to progressive increase in soluble sugars,proteins,K+and Na+concentrations of the algal cells,particularly at the early stages of ***,the salinity-induced increase in chlorophyll concentration approached a limit at 100 mmol/L NaCl whereas that in starch concentration was more evident at the later stages of growth.

关键词： carbohydrates growth phase minerals protein salt stress Scenedesmus obliquus