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synthesis and spectroscopic characterization of novel 2-amino-4,5,6,7-tetrahydro-3H-cyclopenta[d]pyrimidine and pyrimido[1,2-α]pyrimidine derivatives

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Chinese Chemical Letters 2015年第6期26卷 690-694页

作者： mohamed s.A.El-Gaby Jehan A.Micky Nadia M.saleh Yousry A.Ammar Heba s.A.mohamed Chemistry Department Faculty of ScienceAl-Azhar University at Assiut Chemistry Department Faculty of Science (Girl’s)Al-Azhar University Chemistry Department Faculty of ScienceAl-Azhar University Photochemistry Department National Research CenterEl-DokkiGizaEgypt

2-Aminocyclopenta[d]pyrimidines 3a-c were achieved via a one-pot, three-component reactions of cyclopentanone 1, aromatic aldehyde and guanidine hydrochloride （1：2：1 molar ratio）. Also, cyclization of 2,5-bis-（arylmethylidene）cyclopentanones 2 with guanidine hydrochloride （1：1 molar ratio） in methanol in the presence of sodium methoxide afforded cyclopenta-[d]pyrimidines 3. Compound 3c has been shown to be a useful building block for the synthesis of some novel pyrimido[ 1,2-a]pyrimidines 5, 7 and 12. The structures of the newly synthesized compounds were confirmed on the basis of analytical and spectral data,

关键词： Multicomponent reaction Cyclopenta[d]pyrimidine Pyrimido[1 2-a]pyrimidine Cyclopentanone

Facies Associations and sequence stratigraphy of the Toarcian Marrat Formation(saudi Arabia) and Their Equivalents in some Gondwanaland Regions

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Journal of Earth science 2023年第1期34卷 242-259页

作者： mohamed Tawfik Abelbaset s.El-sorogy Khaled Al-Kahtany Geology Department Faculty of ScienceZagazig UniversityZagazig44519Egypt Geology and Geophysics Department College of ScienceKing Saud UniversityRiyadh11451Saudi Arabia

The Toarcian Marrat Formation is exposed in outcrops in central saudi Arabia and displays a variety of clastic and carbonate facies associated with well-preserved depositional geometries. It is unconformably overlies the Triassic Minjur Formation and it in turn is overlaid by the Middle Jurassic Dhruma Formation. Thirteen lithofacies types can be identified that permit the recognition of five lithofacies associations in a mixed clastic/carbonate platform. These lithofacies range from low-energy peritidal, intertidal, and back-shoal to moderate-and high-energy shoal and foreshoal lithofacies associations. The Marrat Formation exhibits three depositional sequences, each sequence is grouped into a transgressive systems tract(TsT) and a highstand systems tract(HsT) and then bounded by sequence boundary surfaces(sBss). The TsTs are generally identified in clastic tidal-flat beds and back-shoal wackestones, while the HsT is generally recorded in the carbonate tidal-flat and shoal. The vertical succession of facies associations from peritidal to foreshoal depositional environments is indicative of a deepening upward and retrogradational systems tract, from Lower to Upper Toarcian. The correlation between the studied sections reveals a general shallowing towards the south and the similarities between the studied sequences and others in the Arabian Gulf, the northern Neo-Tethys Plate, and Gondwanaland countries.

关键词： stratigraphy sequence stratigraphy Lower Jurassic Marrat Formation saudi Arabia Neo-Tethys Arabian Gulf Gondwanaland

Mild solutions of a Class of Conformable Fractional Differential Equations with Nonlocal Conditions

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Acta Mathematicae Applicatae sinica 2023年第2期39卷 249-261页

作者： mohamed BOUAOUID sultan Moulay slimane University Faculty of Sciences and TechnicsDepartment of MathematicsBP 52323000Beni MellalMorocco

This paper deals with the existence,uniqueness and continuous dependence of mild solutions for a class of conformable fractional differential equations with nonlocal initial *** results are obtained by means of the cl... 详细信息

关键词： fractional partial differential equations fractional derivatives and integrals cosine family of linear operators nonlocal conditions

Heat transfer of copper/water nanofluid flow through converging-diverging channel

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Journal of Central south University 2016年第2期23卷 484-496页

作者： mohamed Rafik sARI mohamed KEZZAR Rachid ADJABI Mechanical Engineering Department University of Skikda Industrial Mechanics Laboratory Badji-Mokhtar University of Annaba

The main objective of this work is to investigate analytically the steady nanofluid flow and heat transfer characteristics between nonparallel plane walls. Using appropriate transformations for the velocity and temperature, the basic nonlinear partial differential equations are reduced to the ordinary differential equations. Then, these equations have been solved analytically and numerically for some values of the governing parameters, Reynolds number, Re, channel half angle, α, Prandtl number, Pr, and Eckert number, Ec, using Adomian decomposition method and the Runge-Kutta method with mathematic package. Analytical and numerical results are searched for the skin friction coefficient, Nusselt number and the velocity and temperature profiles. It is found on one hand that the Nusselt number increases as Eckert number or channel half-angle increases, but it decreases as Reynolds number increases. On the other hand, it is also found that the presence of Cu nanoparticles in a water base fluid enhances heat transfer between nonparallel plane walls and in consequence the Nusselt number increases with the increase of nanoparticles volume fraction. Finally, an excellent agreement between analytical results and those obtained by numerical Runge-Kutta method is highly noticed.

关键词： nanofluid flow heat transfer copper nanoparticles inclined walls analytical solution

A survey of Racks and Quandles:some Recent Developments

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Algebra Colloquium 2020年第3期27卷 509-522页

作者： mohamed Elhamdadi Department of Mathematics University of South Florida TampaFL 33620USA

This short survey contains some recent developments of the algebraic theory of racks and *** report on some elements of representation theory of quandles and ring theoretic approach to quandles.

关键词： rack quandle representation ring isomorphism

Completed Tensor Product and Flatness

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Algebra Colloquium 2020年第3期27卷 599-606页

作者： mohamed Tabaa Department of Mathematics Faculty of Sciences Mohammed v University in RabatMorocco

We give,in a more general case than the Noetherian case,an answer to the question posed by shaul on the flatness of the completed tensor product.

关键词： preadic topology completed tensor product coherent ring flat module

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

Preparation of composite tubular grafts for vascular repair via electrospinning

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Progress in Natural science:Materials International 2012年第2期22卷 108-114页

作者： salem s.Al-Deyab mohamed El-Newehy Petrochemical Research Chair Department of ChemistryCollege of ScienceKing Saud UniversityRiyadh 11451Saudi Arabia Department of Chemistry Faculty of ScienceTanta UniversityTanta 31527Egypt

A novel type of composite vascular graft was developed via electrospinning in the present *** and chitosan were blended to form the inner and outer ***(l-lactide-co-caprolactone)(P(LLA-CL))was selected as a material for the middle layer of composite vascular *** morphology and diameter of the composite grafts were studied by scanning Electron Microscope(sEM).The results of mechanical tests showed that the composite scaffolds provided the whole grafts with better strength and flexibility compared with blended grafts,mainly due to the fact that the middle layer was P(LLA-CL).Cell viability studies with endothelial cells suggested a prompt adhesion and proliferation duo to the fact that the outer layer was collagen and *** microscopy demonstrated that a monolayer of endothelial cells could be formed after 7 days of *** above results indicated that the composite fibrous scaffolds could be a good candidate for blood vessel repair by electrospinning method.

关键词： Electrospinning Composite Vascular graft Endothelial cell Nanofiber

Host immune cellular reactions in corneal neovascularization

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International Journal of Ophthalmology(English edition) 2016年第4期9卷 625-633页

作者： Nizar s.Abdelfattah mohamed Amgad Amira A Zayed Doheny Eye Institute University of California Ophthalmology Department David Geffen School of Medicine University of California Faculty of Medicine Cairo University Department of surgery Mayo Clinic Rochester

Corneal neovascularization（CNV） is a global important cause of visual impairment. The immune mechanisms leading to corneal heme- and lymphangiogenesis have been extensively studied over the past years as more attempts were made to develop better prophylactic and therapeutic measures. This article aims to discuss immune cells of particular relevance to CNV, with a focus on macrophages, Th17 cells, dendritic cells and the underlying immunology of common pathologies involving neovascularization of the cornea. Hopefully, a thorough understanding of these topics would propel the efforts to halt the detrimental effects of CNV.

关键词： corneal neovascularization macrophage Th17 cells dendritic cells herpes simplex keratitis keratoplasty angiogenesis lymphangiogenesis contact lenses