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Static and dynamic stability responses of multilayer functionally graded carbon nanotubes reinforced composite nanoplates via quasi 3D nonlocal strain gradient theory

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Defence Technology（防务技术） 2022年第10期18卷 1778-1809页

作者： ahmed Amine Daikh mohamed Sid ahmed Houari mohamed Ouejdi Belarbi Salwa A.mohamed mohamed A.Eltaher Laboratoire D'Etude des Structures et de Mecanique des Materiaux Departement de Genie CivilFacultedes Sciences et de La TechnologieUniversite Mustapha Stambouli B.P.305R.P.29000MascaraAlgeria Laboratoire de Genie Energetique et Materiaux LGEMUniversite de BiskraB.P.145R.P07000BiskraAlgeria Department of Engineering Mathematics Zagazig UniversityP.O.Box 44519ZagazigEgypt Faculty of Engineering Mechanical Engineering DepartmentKing Abdulaziz UniversityP.O.Box 80204JeddahSaudi Arabia Faculty of Engineering Mechanical Design and Production DepartmentZagazig UniversityP.O.Box 44519ZagazigEgypt

This manuscript presents the comprehensive study of thickness stretching effects on the free vibration,static stability and bending of multilayer functionally graded(FG)carbon nanotubes reinforced composite(CNTRC)*** nanoscale and microstructure influences are considered through a modified nonlocal strain gradient continuum *** on power-law functions,four different patterns of CNTs distribution are considered in this analysis,a uniform distribution UD,FG-V CNTRC,FG-X CNTRC,and FG-O CNTRC.A 3D kinematic shear deformation theory is proposed to include the stretching influence,which is neglected in classical ***'s principle is applied to derive the governing equations of motion and associated boundary *** solutions are developed based on Galerkin method to solve the governing equilibrium equations based on the generalized higher-order shear deformation theory and the nonlocal strain gradient theory and get the static bending,buckling loads,and natural frequencies of *** with previous works is presented.A detailed parametric analysis is carried out to highlight the impact of thickness stretching,length scale parameter(nonlocal),material scale parameter(gradient),CNTs distribution pattern,geometry of the plate,various boundary conditions and the total number of layers on the stresses,deformation,critical buckling loads and vibration *** new results are also reported in the current study,which will serve as a benchmark for future research.

关键词： 3D shear deformation theory Free vibration Buckling Bending Galerkin method Functionally graded nanotube Nonlocal strain gradient theory

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Nano-crystallites Imine-based Copper(II) Complexes as Mimetics for Copper Oxidase Proteins: Synthesis,Characterization,DFT and Oxidase Mimicking Activity

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Chemical Research in Chinese Universities 2024年第6期40卷 1068-1081页

作者： ALHADHRAMI Abdulrahman ramadan Abd El-Motaleb FATHY ahmed Department of Chemistry College of ScienceTaif UniversityP.O.Box 11099Taif21944Saudi Arabia Chemistry Department Faculty of ScienceKafr El-Sheikh UniversityKafr El-SheikhEgypt Chemistry Department Faculty of ScienceZagazig UniversityZagazigEgypt

Three tridentate imine ligands containing N2S donors were synthesized via Schiff condensation between derivatives of both amino triazine and 2-carbonyl *** reaction of these ligands with CuCl2 in a molar ratio of 1:1 provides three Cu(II) complexes with the general formula [CuLn·Cl_(2)].Analytical,electrical,magnetic,and spectroscopic studies were used to assign the molecular formulae of these metallic *** function theory (DFT) calculations confirmed the structural analysis results obtained from spectroscopic *** various characterization techniques used demonstrated the penta-coordinated slightly distorted square pyramidal structure for the present Cu(II) complexes 1,2,and *** of cyclic voltammetry were done in methanol to define the electrochemical behavior of the current Cu(II) *** biomimetics of catechol oxidase (C.O.);phenoxazinone synthase (PHS) have been studied in the aerobic oxidation of some phenolic substrates,such as 3,5-di-tert-butylcatechol (3,5-DTBCH2);ortho-aminophenol (o-APH3).The three candidate oxidase mimetics showed promising activity in the order 3 > 1 > *** catalytic activity related to the structural properties of existing oxidase mimetics was *** driving force (-ΔG°) controlling the redox reactions of the present biomolecules was calculated from the redox data of Cu(II) complexes 1,2,and *** potential catalytic reaction pathway for the oxidation of the studied phenolic substrates was discussed.

关键词： Nano-crystallite Imine-based copper(II)complex Mimetics of copper oxidase protein Synthesis and characterization Density function theory(DFT)calculation

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Magnetoresistive properties of Ni-doped La_(0.7)Sr_(0.3)MnO_3 manganites

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Rare Metals 2016年第7期35卷 551-558页

作者： ahmed mohamed ahmed Abd El-Moez ahmed mohamed Medhat Abdelrady Abdellateef Hassan ahmed Abd El-Ghanny Physics Department Faculty of ScienceSohag University

Lao.7Sr0.3Mnl_xNixO3 （x = 0, 0.025, 0.050 and 0.075） ceramics were prepared by the conventional solid-state reaction method. The partial substitution of Mn by Ni2＋ leads to a decrease in cell volume as well as a structural transition from the rhombohedral to the orthorhombic structure. Ni2＋ doping increases the electrical resistivity, decreases the semiconductor-metal transition temperature （Tms） and relatively enhances the room temperature magnetoresistance （MR）, especially in x = 0.025 and around Tins. With respect to conduction mechanism, the small polaron hopping （SPH） and the variable range hopping （VRH） models were used to ex- amine conduction in the semiconducting region.

关键词： Manganites X-ray diffraction Structure Electrical resistivity Magnetoresistance

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Developing Check-Point Mechanism to Protect Mobile Agent Free-Roaming Against Untrusted Hosts

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Computers, Materials & Continua 2022年第8期72卷 3849-3862页

作者： Tarig mohamed ahmed Department of Information Technology FCITKing Abdulaziz UniversityJeddahSaudi Arabia

Mobile Agent has many benefits over traditional distributed systems such as reducing latency,bandwidth,and *** Agent Systems are not fully utilized due to security *** paper focuses on mobile agent protection against malicious hosts.A new security mechanism called Checkpoints has been *** Mechanism(CPM)aims to protect Mobile Agent against malicious hosts in case of Capturing and Integrity *** assumes using a free-roaming mobility mechanism by Mobile agent *** main idea behind CPM is to generate multiple versions of Mobile *** multiple version is used to recover Mobile Agent from Capturing and Integrity attacks by untrusted *** versions are kept in Recovery Host(RH).RH plays a key role in CPM by controlling and monitoring MAs’recovery processes.A prototype method has been used to prove the feasibility of *** p https://***/Default-305-ARrototype was implemented by using *** framework and C#.full discussion for several scenarios has been done to analyze the feasibility and performance for *** found from this research,CPM has a strong ability to protect Mobile Agents from Capturing and Integrity attacks *** addition,there is no negative impact on the overall performance of the mobile agent system.

关键词： Mobile agent security capturing integrity attacks

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Anti-wear properties evaluation of frictional sliding interfaces in automobile engines lubricated by copper/graphene nanolubricants

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Friction 2020年第5期8卷 905-916页

作者： mohamed Kamal ahmed ALI Xianjun HOU mohamed AAABDELKAREEM Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China Automotive and Tractors Engineering Department Faculty of EngineeringMinia UniversityEl-Minia 61111Egypt Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan 430070China

Owing to the significance of improving fuel economy, reducing emissions, and extending the durability of engine components, this study focused on the tribological performance of nano-additives. In this study, copper (Cu) and graphene (Gr) nanomaterials were dispersed in a fully formulated engine oil (5W-30) with different concentrations. The tribological trials were investigated under various speeds and loads, utilizing a reciprocating tribometer to mimic the ring/liner interfaces in the engine. The frictional surface morphologies were com-prehensively analyzed using electron probe X-ray microanalysis (EPMA), field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS), and three dimensional (3D) surface profilometry to explore the mechanisms responsible for improving the tribological performance of the frictional sliding parts in the engine. The tribological test results illustrated that lubrication by nano-additives reduced the wear rate (WR) and friction coefficient (COF) by 25%–30% and 26.5%–32.6%, respectively, as compared with 5W-30. The results showed that this is a promising approach for increasing the durability and lifespan of frictional sliding components and fuel economy in automobile engines.

关键词： engine tribology nanomaterial nanolubricant friction wear tribofilm

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Characteristics,composition and functional properties of seeds,seed cake and seed oil from different Brassica carinata genotypes

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Food Bioscience 2022年第4期48卷 300-309页

作者： Adel Abdelrazek Abdelazim Mohdaly mohamed Fawzy ramadan Food Science and Technology Department Faculty of AgricultureFayoum UniversityEl-FayoumP.O.63514Egypt Agricultural Biochemistry Department Faculty of AgricultureZagazig UniversityZagazigP.O.44519Egypt Deanship of Scientific Research Umm Al-Qura UniversityMakkahP.O.715Saudi Arabia

Carinata(Brassica carinata)is an oilseed crop with potential in biofuel production and livestock *** present research was conducted to evaluate twenty Brassica carinata genotypes used in breeding programs to develop commercial production of Brassica carinata with low levels of erucic *** following characters were evaluated:oil contents,fatty acid profiles,physicochemical characteristics of oils,as well as the content of protein,total phenolic compounds,and the antiradical activity of Brassica carinata defatted seed *** oil analysis indicated desirable quality,including low percentages of free fatty acids(FFA),high amounts of unsaponifiable matter(USM),and low values for primary and secondary oxidation products that were under the regulated *** oil contents of the samples varied between 27.0 and 39.2%.A total of 16 fatty acid compositions were identified in different *** compared to the commercial canola oil,it was observed that Brassica carinata 14C genotype had quite similar fatty acid *** phenolics and protein contents of Brassica carinata cake extract varied from 43.2 to 132 mg/100 g and from 24.6 to 35.4%,*** can be noted that Brassica carinata genotype 14C with low erucic acid(EA)and high oleic acid contents consider as an edible oil *** EA,the genotypes 3C,10C,and 17C with low EA content could be recommended as a basis for further breeding *** carinata cake from different genotypes might be a valuable source of natural antioxidants due to their antioxidant capacities and free radical scavenging potential.

关键词： Brassicaceae Cruciferae Canola Physicochemical properties Erucic acid Phenolics Antioxidants Seed cake Breeding

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Experimental and parametrical investigation of pre-stressed ultrahigh-performance fiberreinforced concrete railway sleepers

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Frontiers of Structural and Civil Engineering 2023年第3期17卷 411-428页

作者： Sayed ahmed Hossam ATEF mohamed HUSAIN Department of Structural Engineering Faculty of EngineeringZagazig UniversityZagazig 44519Egypt Track Work Department National Authority for TunnelsCairo 11522Egypt

In this study,ultrahigh-performance fiber-reinforced concrete(UHPFRC)used in a type B70 concrete sleeper is investigated experimentally and *** main parameters investigated are the steel fiber volume fractions(0%,0.5%,1%,and 1.5%).Under European standards,35 UHPFRC sleepers are subjected to static bending tests at the center and rail seat sections,and the screw on the fastening system is pulled *** first cracking load,failure load,failure mode,crack propagation,load–deflection curve,load–crack width,and failure load from these tests are measured and compared with those of a control sleeper manufactured using normal concrete *** accuracy of the parametric study is verified ***,the results of the study are applied to UHPFRC sleepers with different concrete volumes to investigate the effects of the properties of UHPFRC on their *** and parametric study results show that the behavior of UHPFRC sleepers improves significantly when the amount of steel fiber in the mix is *** manufactured using UHPFRC with a steel fiber volume fraction of 1%and a concrete volume less than 25%that of standard sleeper B70 can be used under the same loads and requirements,which contributes positively to the cost and surrounding environment.

关键词： pre-stressed concrete sleeper ultrahigh performance fiber-reinforced concrete pull-out test static bending test steel fiber aspect ratio volume fraction

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A hydromechanical approach for anisotropic elasto-viscoplastic geomaterials:Application to underground excavations in sedimentary rocks

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Underground Space 2019年第2期4卷 109-120页

作者： mohamed Mahjoub ahmed Rouabhi Mines ParisTech PSL Research UniversityCentre de Ge´osciencesFontainebleauFrance

To better describe excavation operations in deep geological formations,several aspects should be considered,especially the material anisotropy,time-dependent behavior,and hydromechanical *** the present paper,a hydromechanical model based on the framework of continuous porous media was *** mechanical elasto-viscoplastic constitutive model accounted for the material elastic and non-elastic anisotropies,using a transformation between the real transversely isotropic material and a fictitious isotropic *** the hydraulic behavior,the permeability was expressed as a function of the volumetric viscoplastic *** model was applied to a case study of two tunnel excavations in an anisotropic rock under an initial anisotropic stress *** results of the numerical simulations using a finite element code were in good agreement with the field convergence and permeability data.

关键词： Hydromechanical behavior Transverse isotropy Tunnel excavation Viscoplasticity Permeability

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Age distribution,polyps and rectal cancer in the Egyptian population-based cancer registry

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World Journal of Gastroenterology 2012年第30期18卷 3997-4003页

作者： Darlene Veruttipong Amr S Soliman Samuel F Gilbert Taylor S Blachley ahmed Hablas mohamed ramadan Laura S Rozek Ibrahim A Seifeldin Department of Epidemiology University of Michigan School of Public HealthAnn ArborMI 48109United States Department of Biostatistics University of Michigan School of Public HealthAnn ArborMI 48109United States Tanta Cancer Center and the Gharbiah Population-Based Cancer Registry Tanta 31512Egypt Department of Environmental Health Science University of Michigan School of Public HealthAnn ArborMI 48109United States

AIM:To describe the clinical and epidemiologic profiles of the disease and to compare the findings with those generated from the previous hospital-based ***:The Gharbiah cancer registry is the only population-based cancer registry in Egypt since *** analyzed the data of all colorectal cancer patients included in the registry for the period of *** medical records of the 1364 patients diagnosed in Gharbiah during the study period were retrieved and the following information abstracted:age,residence,diagnosis date,grade,stage,topology,clinical characteristics,and histology *** census data for 1996 and 2006 were used to provide the general population's statistics on age,sex,residence and other related demographic *** addition to age-and sex-specific incidence rate analyses,we analyze the data to explore the incidence distribution by rural-urban differences among the 8 districts of the *** also compared the incidence rates of Gharbiah to the rates of the Surveillance Epidemiology and End Results(SEER) data of the United ***:Over the 9 year-period,1364 colorectal cancer cases were *** disease incidence under age 40 years was relatively high(1.3/10 5) while the incidence in the age groups 40 and over was very low(12.0/10 5,19.4/10 5 and 21.2/10 5 in the age groups 40-59 years,60-69 years and > 70 years,respectively).The vast majority of tumors(97.2%) had no polyps and 37.2% of the patients presented with primary lesions in the *** cancer was more common in patients from urban(55%) than rural(45%) *** differences in colon and rectal cancer incidence in the 8 districts of the study province may reflect different etiologic patterns in this *** registry data of Egypt shows a slightly higher incidence of colorectal cancer than the United States in subjects under age 40 *** results also shows significantly lower incidence of colorectal cancer in subjects over age

关键词： Colorectal cancer Young-onset Polyps Developing countries Egypt

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Exact and heuristic formulae to compute the geodetic height from the ellipse equation

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Geodesy and Geodynamics 2024年第2期15卷 150-155页

作者： mohamed Eleiche ahmed Hamdi Mansi Construction Department Faculty of EngineeringEgyptian Russian UniversityCairoEgypt Istituto Nazionale di Geofisica e Vulcanologia Sezione di PisaPisaPlItaly

The conversion of the cartesian coordinates of a point to its geodetic equivalent coordinates in reference to the geodetic ellipsoid is one of the main challenges in *** ellipse equation in the meridian plane significantly influences the value of the geodetic *** research analyzes this influence and how it can contribute to their *** study investigates the mathematical relation between them and presents an exact formula relating to the geodetic height and the ellipse *** addition,a heuristic formula for the relation between the geodetic height and the ellipse equation is proposed,which is independent of the geodetic latitude and has a relative accuracy better than 99.9 %.The calculation is stable,and the cost is low.

关键词： Ellipse equation Geodetic height Heuristic geodetic height

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