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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

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

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

SYNTHESIS,CHARACTERIZATION AND ENHANCED ELECTRICAL PROPERTIES OF CTAB-DIRECTED POLYANILINE NANOPARTICLES

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Chinese Journal of Polymer Science 2011年第2期29卷 181-190页

作者： Lal Said Jan mohamed ahmed Siddig Department of Physics Postgraduate College Mardan23200Khyber PakhtunkhwaPakistan School of Physics and Applied Physics Faculty of Science and TechnologyEL Neelain UniversityKhartoumSudan

Inverse microemulsion system of cetyltrimethylammonium bromide（CTAB） molecules is utilized for virtually monodispersed and controlled growth of HCl polyaniline（PANI） nanoparticles at room temperature（ca.300 K）.The templated electroconductive polymer reveals lamellar crystalline structure under X-ray diffraction signifying marked sub-chain alignment of the polymerized *** nanostructured polymer has spherically symmetric morphology in a size range of 2.0 nm to 6.0 nm under electron microscope *** permeation chromatography gives polydispersity index of 1.02 for nanostructured polymer in agreement with the size monodispersity transpired by electron *** *** conductivityσ_（dc） of PANI at room temperature is 10.11 S/cm whereas the variation of conductivity with temperature in the range 227-303 *** that the conducting mechanism can be considered as three-dimensional variable-range-hopping（3D-VRH）.UV-Vis spectrum indicates two broad absorption bands due to polaron formation that contributes to enhanced electrical conductivity of the *** fundamental absorption edge in the polymer is formed by direct allowed transitions to the extent that the optical band gap value was found to be 2.35 *** crystalline nanostructure and homogeneous doping attained in the cationic template of amphiphile are argued as contributing factors to the enhanced conductivity of the polymer.

关键词： Polyaniline Nanostructured Band gap energy Electrical conductivity

Nonalcoholic fatty liver disease and COVID-19:An epidemic that begets pandemic

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World Journal of Clinical Cases 2021年第17期9卷 4133-4142页

作者： Musaab ahmed mohamed H ahmed College of Medicine Ajman UniversityAjman 346United Arab Emirates Department of Medicine and HIV Metabolic Clinic Milton Keynes University Hospital NHS Foundation TrustMilton Keynes MK56LDUnited Kingdom

Coronavirus disease 2019(COVID-19)caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has become a global pandemic,affecting all the individuals across the ***-19 has gained significant attention due to its high prevalence among individuals with diabetes,nonalcoholic fatty liver disease(NAFLD),and metabolic *** is the hepatic manifestation of metabolic syndrome and can be associated with a high risk of developing type 2 *** association of COVID-19 and NAFLD has also gained more attention because NAFLD is highly associated with the epidemic of *** is a potential risk factor for SARS-CoV-2 infection and severe COVID-19,independent of metabolic ***,it is not yet clear whether the epidemics of obesity and NAFLD have perpetuated the current pandemic of *** research is urgently needed to assess the following:(1)Whether NAFLD is a high risk factor for SARS-CoV-2 infection;(2)Whether NAFLD is associated with the severe form of COVID-19;and(3)Whether the presence of NAFLD can explain the racial variation in the morbidity and mortality associated with *** review summarizes the interactions between COVID-19 and NAFLD,mechanism of liver injury by COVID-19,and effect of lockdown due to COVID-19 on patients with NAFLD.

关键词： Fatty liver COVID-19 Diabetes Obesity Pandemic

DECAY ESTIMATES FOR ISENTROPIC COMPRESSIBLE MAGNETOHYDRODYNAMIC EQUATIONS IN BOUNDED DOMAIN

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Acta Mathematica Scientia 2012年第6期32卷 2211-2220页

作者： mohamed ahmed Abdallah 江飞谭忠 School of Mathematical Sciences Xiamen University College of Mathematics and Computer Science Fuzhou University Institute of Applied Physics and Computational Mathematics

In this paper, under the hypothesis that y is upper bounded, we construct a Lyapunov functional for the multidimensional isentropic compressible magnetohydrodynamic equations and show that the weak solutions decay exponentially to the equilibrium state in L2 norm. Our result verifies that the method of Daoyuan Fang, Ruizhao Zi and Ting Zhang I1] can be adapted to magnetohydrodynamic equations.

关键词： Navier-Stokes equations weak solution decay estimates magnetohydrody-namic

In vitro and in vivo evaluation of cubosomes containing 5-fluorouracil for liver targeting

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Acta Pharmaceutica Sinica B 2015年第1期5卷 79-88页

作者： mohamed Nasr mohamed K.Ghorab ahmed Abdelazem Department of Pharmaceutics and Industrial Pharmacy Faculty of Pharmacy Helwan University Department of Pharmaceutical Chemistry Faculty of Pharmacy Helwan University

The objective of this study was to prepare cubosomal nanoparticles containing a hydrophilic anticancer drug 5-fluorouracil(5-FU) for liver targeting. Cubosomal dispersions were prepared by disrupting a cubic gel phase of monoolein and water in the presence of Poloxamer 407 as a *** loaded with 5-FU were characterized in vitro and in vivo. In vitro, 5-FU-loaded cubosomes entrapped 31.21% drug and revealed nanometer-sized particles with a narrow particle size distribution. In vitro 5-FU release from cubosomes exhibited a phase of rapid release of about half of the entrapped drug during the first hour, followed by a relatively slower drug release as compared to 5-FU solution. In vivo biodistribution experiments indicated that the cubosomal formulation significantly(Po 0.05) increased5-FU liver concentration, a value approximately 5-fold greater than that observed with a 5-FU ***, serum serological results and histopathological findings revealed greater hepatocellular damage in rats treated with cubosomal formulation. These results demonstrate the successful development of cubosomal nanoparticles containing 5-FU for liver targeting. However, further studies are required to evaluate hepatotoxicity and in vivo antitumor activity of lower doses of 5-FU cubosomal formulation in treatment of liver cancer.

关键词： 5-Fluorouracil Hydrophilic drug Cubosomes Liver targeting Hepatotoxicity

Remote Monitoring of Electric Vehicle Charging Stations in Smart Campus Parking Lot

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Journal of Modern Power Systems and Clean Energy 2020年第1期8卷 124-132页

作者： mohamed A.ahmed mohamed R.El-Sharkawy Young-Chon Kim Department of Electronic Engineering Universidad Técnica Federico Santa MaríaValparaíso 2390123Chile Department of Communications and Electronics Higher Institute of Engineering&TechnologyKing MarriottAlexandria 23713Egypt Department of Automotive and Tractor Engineering Minia UniversityEl-Minia 61111Egypt Department of Computer Engineering Chonbuk National UniversityJeonju 561-756Korea

Smart parking lots are smart places capable of supporting both parking and charging services for electric vehicles(EVs).In order to manage EV charging,the parking lot local controller(PLLC)requires data exchange with EV charging stations(EVCSs)through communication ***,data losses and communication delays are unavoidable and may significantly degrade the system *** work aims to investigate the underlying communication networks for remote monitoring of EVCSs in a smart campus parking *** communication network consists of two subnetworks:parking area network(PAN)and campus area network(CAN).PAN covers communication among EVs,charging stations and PLLC,while CAN enables dedicated communication between PLLCs and a global controller of the *** one of the major obstacles in EV system is the lack of unified communication architecture to integrate EVCS in the power grid,we develop communication models for the in-vehicle system and EVCSs based on logical node concept of IEC 61850 ***,we implement network models for EVCSs using OPNET *** communication technologies and configurations are considered in modeling and simulations,and end-toend delay is evaluated and discussed.

关键词： Communication network electric vehicle(EV) electric vehicle charging station(EVCS) IEC 61850 OPNET smart parking lot

ON SINGULAR EQUATIONS INVOLVING FRACTIONAL LAPLACIAN

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Acta Mathematica Scientia 2020年第5期40卷 1289-1315页

作者： ahmed YOUSSFI Ghoulam OULD mohamed MAHMOUD National School of Applied Sciences Sidi mohamed Ben Abdellah University-Fez Laboratory of Mathematical Analysis and Applications My Abdellah Avenue Road ImouzerP.O.Box 72 Fes-Principale30000FezMorocco National School of Applied Sciences Sidi mohamed Ben Abdellah University-Fez My Abdellah Avenue Road ImouzerP.0.Box 72 Fes-Principale30000FezMorocco

We study the existence and the regularity of solutions for a class of nonlocal equations involving the fractional Laplacian operator with singular nonlinearity and Radon measure data.

关键词： fractional Laplacian singular elliptic equations measure data

Insights into the adsorption performance and mechanism of Cr(Ⅵ)onto porous nanocomposite prepared from gossans and modified coal interface:Steric,energetic,and thermodynamic parameters interpretations

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Chinese Journal of Chemical Engineering 2023年第9期61卷 118-128页

作者： mohamed Mobarak Saleh Qaysi mohamed Saad ahmed Yasser F.Salama ahmed mohamed Abbass mohamed Abd Elrahman Hamdy AAbdel-Gawwad Moaaz K.Seliem Physics Department Faculty of ScienceBeni-Suef UniversityEgypt Geology and Geophysics Department College of ScienceKing Saud University11451 RiyadhSaudi Arabia Geology Department Faculty of ScienceBeni-Suef UniversityEgypt Department of Building Materials and Construction ChemistryInstitute of Civil EngineeringTechnische Universitat BerlinBerlinGermany Structural Engineering Department Faculty of EngineeringMansoura UniversityMansouraEgypt Raw Building Materials and Processing Technology Research Institute Housing and Building National Research Center(HBRC)CairoEgypt Faculty of Earth Science Beni–Suef UniversityEgypt

Herein,iron oxide/hydroxides deposits(gossans)were utilized,for the first time,in the fabrication of magnetite nanoparticles(MNPs)to load modified coal(MC).The as-synthesized MNPs@MC composite was characterized via different techniques and utilized for the Cr(Ⅵ)*** studies supported by theoretical treatment were applied to offer a new overview of the Cr(Ⅵ)adsorption geometry and mechanism at 25-45℃.Experimental results suggested that the Cr(Ⅵ)uptake was mainly governed by adsorption-reduction coupled *** Langmuir model fitted well the Cr(Ⅵ)adsorption data with maximum adsorption capacities extended from 115.24 to 129.63 mg·g^(-1).Theoretical calculations indicated that Cr(Ⅵ)ions were adsorbed on the MNPs@MC following the theory of the advanced monolayer statistical *** number of ions removed per site ranged from 1.88 to1.23 suggesting the involvement of vertical geometry and multi-ionic mechanism at all *** increment of the active sites density and the adsorption capacity at saturation with improving temperature reflected an endothermic ***,the Cr(Ⅵ)adsorption was controlled by physical forces as the adsorption energies were less than 40 kJ·mol^(-1).The calculated free enthalpy,*** internal energy explained the spontaneous nature and the viability of Cr(Ⅵ)adsorption on the MNPs@MC *** results offer a new approach in utilizing the iron-rich deposits as gossans in the preparation of magnetic and low-cost adsorbents for wastewater remediation.

关键词： Coal Magnetic nanoparticles Cr(Ⅵ)adsorption Statistical models Thermodynamic parameters