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Wear properties of copper and copper composites powders consolidated by high-pressure torsion

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Friction 2020年第2期8卷 433-450页

作者： mohamed Ibrahim Abd el AAL Mechanical Engineering Department College of EngineeringPrince Sattam Bin Abdulaziz UniversityWadi Addawaser 11991Saudi Arabia Mechanical Design&Production Department Faculty of EngineeringZagazig UniversityZagazig 44519Egypt

The wear characteristics of Cu and Cu-SiC composite microsize powders consolidated by cold compaction combined with sintering or high-pressure torsion(HPT)were *** HPT processed(HPTed)samples with bimodal and trimodal microstructures and fine Cu grains and SiC particle sizes have superior hardness,reasonable ductility level,and high wear *** wear mass loss and coefficient of friction of HPTed samples were remarkably lower than that of cold-compacted and sintered samples as well as that of micro and nano Cu and Cu-SiC composites from previous *** sample fabrication method has an apparent influence on the wear *** wear mechanism was converted from adhesive,delamination,three-body mechanism,grooves(take off the SiC particles),and cracks into abrasive wear after *** can be considered a dominant wear mechanism in all *** worn surface morphology and analysis support the relationship between wear mechanism and characteristics.

关键词： Cu-SiC composite powders high-pressure torsion(HPT) fine and coarse grains wear characteristics worn surface morphology

On the Gosper’s q-constant Ⅱ_q

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Acta Mathematica Sinica,English Series 2018年第11期34卷 1755-1764页

作者： mohamed el BACHRAOUI Department Mathematical Sciences UAE University

Gosper introduced the functions sinq z and cosq z as q-analogues for the trigonometric functions sin z and cos z respectively. He stated a variety of identities involving these two q-trigonometric functions along with certain constants denoted by Πqn （n ∈ N）. Gosper noticed that all his formulas on these constants have more than two of the Πqn. So, it is natural to raise the question of establishing identities involving only two of the Πqn. In this paper, our main goal is to give examples of such formulas in only two Πqn.

关键词： q-trigonometric functions elliptic functions theta function identities

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橄榄渣基活性炭活化工艺的优化（英文）

新型炭材料 2016年第5期31卷 492-500页

作者： Nour T.Abdel-Ghani Ghadir a.el-Chaghaby mohamed H.elGammal el-Shaimaa A.Rawash Chemistry Department Faculty of ScienceCairo University RCFF Agriculture Research Center

采用KOH对橄榄渣进行活化得到活性炭。设计2~3正交试验来优化制备工艺条件,水平和因子包括活化温度(600,900℃)、活化时间(1,3 h)和浸渍比(1∶2,1∶4)。活性炭的比表面积作为优化的评价指标。通过氮吸附仪、红外光谱仪和扫描电镜等手段... 详细信息

采用KOH对橄榄渣进行活化得到活性炭。设计2~3正交试验来优化制备工艺条件,水平和因子包括活化温度(600,900℃)、活化时间(1,3 h)和浸渍比(1∶2,1∶4)。活性炭的比表面积作为优化的评价指标。通过氮吸附仪、红外光谱仪和扫描电镜等手段对活性炭的表面化学和孔结构进行表征。结果表明,所有因子及其交互水平都非常显著(p<0.05)。活性炭的比表面积和制备条件的相关系数为99.2%。在最条件下制备的活性炭,比表面积为672 m^2/g、平均孔径为2.05 nm,微孔和介孔率分别为81.36%和18.37%。

关键词：橄榄渣活性炭 KOH 渴望函数孔隙率

Ore Controls and Metallogenesis of Au-Ag Deposits at Atalla Mine,Central Eastern Desert of Egypt

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Acta Geologica Sinica(English Edition) 2020年第5期94卷 1451-1470页

作者： mohamed ABD el MONSEF Geology Department Faculty of ScienceTanta UniversityTanta 31527Egypt Institute of Geological Sciences Faculty of ScienceMasaryk UniversityBrnoCzech Republic

Gold-silver deposits in the Atalla area occur as hydrothermal quartz veins in NE–SW pre-existing fractures within the Atalla granitic *** orientation of such quartz veins has been attributed to extensional behavior related to the Atalla Shear Zone(ASZ).The Atalla area is covered by a variety of lithologies that are(from oldest to youngest):metasedimentary rocks,metavolcanic rocks,ophiolite assemblage(serpentinites/talc-carbonates),Atalla granite and Dokhan volcanic ***,Atalla granite ranges in composition from granodiorite to *** geochemistry constrains the calc-alkaine affinity of the Atalla granite that was intruded within an orogenic(syncollision)tectonic *** ore minerals are represented by gold/silver(electrum),pyrite(Py1&Py2),arsenopyrite,pyrrhotite,sphalerite,chalcopyrite,galena,covellite and *** temperature of ore formation ranges from 240 to 285℃and the estimated fluid pressure is in the range of 20–100 *** on the geological setting,ore textures and fluid characteristics;the Atalla Au-Ag deposits are considered to be orogenic in nature,formed from a continental collision(~653-590 Ma),synchronous with the emplacement of calc-alkaline magmatism during the evolutionary history of the Arabian Nubian Shield(ANS).The initial ore-forming fluid was primarily derived from a metamorphic source related to ophiolitic-serpentinite rocks under deep regional conditions of greenschist-amphibolite facies,where the Atalla granitic eruption provided the required temperature conditions for the metamorphic process to take *** such conditions,the transportation of ore metals as bisulfide complexes is *** deposition of ore minerals was triggered by fluidwallrock interaction through fracture pathways in conjunction with a temperature-pressure drop that is likely to have been related to uplift into the crustal levels.

关键词： Gold-silver arsenopyrite geothermometry fluid inclusions orogenic deposits Atalla Shear Zone(ASZ)

Epidemiologic Profile Urinary Tract Infections: Experience of the Microbiology Laboratory of the University Hospital mohamed VI in Tangier

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Advances in Infectious Diseases 2024年第3期14卷 620-627页

作者： Nouhaila Chahid Chaimae Errabhi el Ghali Tazi Sihame el jamii Yasmine Kemmach Karima Rissoul Department of Microbiology University Hospital Center of Tangier Tangier Morocco Department of Medicine and Pharmacy University of Abdelmalek Essaadi Tangier Morocco

Urinary tract infection is one of the most common bacterial infections in humans. The urine cytobacteriological examination is the key test for its diagnosis. This work aims to Evaluate the prevalence of urinary tract infection at the Microbiology Laboratory of the University Hospital mohamed VI in Tangier and to highlight its epidemiological and bacteriological characteristics. It was a descriptive study with retrospective data collection which took place from January 2021 to June 2022, at the Microbiology Laboratory of the university hospital mohamed VI in Tangier. It covered all urine cytobacteriological examinations (ECBU) during the study period. We identified 77 cases of urinary tract infections out of 300 requests for (ECBU), that is a positivity rate of 25 %. The mean age was 55 years. The male gender was predominant. The epidemiological profile of the isolated strains was dominated by Enterobacteriaceae 81 %, followed by Gram-positive cocci 11 % and non-fermenting gram-negative bacteria 8 %. The main bacteria responsible for urinary tract infections in order of frequency: Escherichia coli 42 %, Klebsiella pneumoniae 20 %, Enterobacter cloacae 9 %, Staphylococcus aureus 6 %, Pseudomonas aeruginosa 5 % and Acinetobacter baumannii 3%. Most of the analyzed organisms showed resistance, especially to the beta-lactam antibiotic;the enterobacteria strains isolated had revealed resistance to amoxicillin: 74%, to amoxicillin-clavulanic acid in 40% of cases, and to third-generation cephalosporins in 24%. In terms of resistance mechanisms, 11 % of the Enterobacteriaceae were extended-spectrum β-lactamase producers and 9 % of the specimens were identified as carbapenemase producers. Of the Staphylococcus aureus strains isolated, 75% were resistant to meticillin. The Glycopeptides and linezolid were the most active molecules on these isolated strains. 15% of Enterococcus species isolated in our laboratory were resistant to glycopeptides (vancomycin and teicoplanin).

关键词： Epidemiology Urinary Tract Infection Cytobacteriological Urinary Test Uropathogens Multiresistant Bacteria Antibiotic Sensitivity Morocco

Heterogeneous performance analysis of the new model of CFAR detectors for partially-correlated χ~2-targets

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Journal of Systems Engineering and electronics 2018年第1期29卷 1-17页

作者： el_MASHADE mohamed Bakry electrical Engineering Department Faculty of Engineering Al Azhar University

To mitigate the deleterious effects of clutter and jammer, modern radars have adopted adaptive processing techniques such as constant false alarm rate(CFAR) detectors which are widely used to prevent clutter and noise interference from saturating the radar’s display and preventing targets from being *** paper concerns with the detection analysis of the novel version of CFAR schemes(cell-averaging generalized trimmed-mean,CATM) in the presence of additional outlying targets other than the target under research. The spurious targets as well as the tested one are assumed to be fluctuating in accordance with the χ~2-model with two-degrees of freedom. In this situation, the processor performance is enclosed by the swerling models(SWI and SWII). Between these bounds, there is an important class of target fluctuation which is known as modera.ely fluctuating targets. The detection of this class has many practical applications. Structure of the CATM detector is described briefly. Detection performances for optimal, CAM, CA, trimmed-mean(TM) and ordered-statistic(OS) CFAR strategies have been analyzed and compared for desired probability of false alarm and determined size of the reference window. False alarm rate performance of these processors has been evaluated for different strengths of interfering signal and the effect of correlation among the target returns on the detection and false alarm performances has also been studied. Our numerical results show that, with a proper choice of trimming parameters,the novel model CAM presents an ideal detection performance outweighing that of the Neyman-Pearson detector on condition that the tested target obeys the SWII model in its fluctuation. Although the new models CAS and CAM can be treated as special cases of the CATM algorithm, their multi-target performance is modest even it has an enhancement relative to that of the classical CAcheme. Additionally, they fail to maintain the false alarm rate constant when the operati

关键词： adaptive target detection multi-pulse performance noise and interference partially-correlated χ~2-targets SWI & SWII target fluctuation models target multiplicity environments

Innovative surfactant of Gemini-type for dissolution mitigation of steel in pickling HCl medium

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Chinese Journal of Chemical Engineering 2021年第6期34卷 125-133页

作者： Medhat Ka.el mohamed Hegazy Salah Rashwan mohamed el Kotb Department of Chemistry Faculty of ScienceSuez Canal UniversityIsmailia 41522Egypt Egyptian Petroleum Research Institute(EPRI) Nasr CityCairo 11727Egypt

A new surfactant of Gemini-type,N,N'-((phthylbis(oxy))bis(ethane-2,1-diyl))bis(N,N-dimethyldodecan-1-aminium bromide)is prepped&*** dissolution suppression impact of the new compound on steel is performed in 1 mol·L^(-1)HCl environment by means of chemical and electrochemical *** prepared surfactant is an agreeable dissolution inhibitor for *** mitigation efficacy rises with the quantity of the *** surfactant belongs to inhibitors of *** adsorption of the synthesized compound followed the Langmuir's *** negative magnitudes of bothΔG_(ads)^(θ) andΔH^(adsθ)indicate that the adsorption process proceeds from its own accord and *** mechanism of adsorption is elucidated by scanning *** is established that the transfer resistance(R_(ct))value rose,where the value of the phase element(CPE)reduced with the amount of synthesized *** to the experimental data arrived by surface tension measurements,the prepared compound is a powerful active agent at the air/water boundary.

关键词： Innovative Gemini surfactant Synthesis Dissolution mitigation Steel Pickling HCl media

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