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Friction and wear of sand-contaminated lubricated sliding

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Friction 2018年第4期6卷 457-463页

作者： mohamed ahmed ramadan Faculty of Engineering at Helwan Helwan University

This paper reports a test investigation of friction and wear responses from sand contaminated lubricated sliding. The influence of sand contaminants on wear and friction is characterized. Analyses are completed utilizing segments of piston ring sliding against the cylinder liner. Paraffin oil, with and without sand contaminants, is utilized. The effects of the concentration and particle size of sand are examined. Based on the observations in the present work, we found that friction and wear increase with sand concentration in the lube. Solid proposals ought to be considered, in order to enlighten the general population on the importance of changing a car engine's oil filter regularly.

关键词： sand contamination lubrication oil abrasive wear lubricated sliding

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

Solar thermochemical reactions Ⅱ:Synthesis of 2-aminothiophenes via Gewald reaction induced by solar thermal energy

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Chinese Chemical Letters 2008年第7期19卷 788-790页

作者： ramadan ahmed Mekheimer mohamed Abdallah Ameen Kamal Usef Sadek Chemistry Department Faculty of ScienceEl-Minia UniversityEl-Minia 61519Egypt

Green conditions have been developed for the synthesis of substituted 2-aminothiophenes employing multicomponent reactions of a ketone with active methylene nitrile and elemental sulphur induced by free solar thermal ... 详细信息

关键词： 2-Aminothiophenes Gewald reaction Solar thermal energy

Patterns of liver profile disturbance in patients with COVID-19

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World Journal of Clinical Cases 2022年第7期10卷 2063-2071页

作者： Hend Ibrahim Shousha ahmed ramadan Rania Lithy mohamed El-Kassas Department of Endemic Medicine Faculty of MedicineCairo UniversityCairo 12556Egypt Department of Endemic Medicine Faculty of MedicineHelwan UniversityCairo 11795Egypt

Fever and cough are the most common clinical symptoms of coronavirus disease 2019(COVID-19),but complications(such as pneumonia,respiratory distress syndrome,and multiorgan failure)can occur in people with additional ***-19 may be a new cause of liver disease,as liver profile disturbance is one of the most common findings among *** molecular mechanism underlying this phenomenon,however,is still *** this paper,we review the most current research on the patterns of change in liver profile among patients with COVID-19,the possible explanation for these findings,and the relation to pre-existing liver disease in these patients.

关键词： Liver functions COVID-19 Liver profile Alanine transaminase aspartate transaminase Bilirubin

A Deep Learning Ensemble Method for Forecasting Daily Crude Oil Price Based on Snapshot Ensemble of Transformer Model

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Computer Systems Science & Engineering 2023年第7期46卷 929-950页

作者： ahmed Fathalla Zakaria Alameer mohamed Abbas ahmed ali Department of Mathematics Faculty of ScienceSuez Canal UniversityIsmailia41522Egypt Mining and Petroleum Department Faculty of EngineeringAl-Azhar UniversityQenaEgypt School of Computer Science and Technology Central South UniversityChangshaHunanChina College of Computer Engineering and Sciences Prince Sattam Bin Abdulaziz UniversityAl-Kharj11942Saudi Arabia Higher Future Institute for Specialized Technological Studies Cairo3044Egypt

The oil industries are an important part of a country’s *** crude oil’s price is influenced by a wide range of ***,how accurately can countries predict its behavior and what predictors to employ are two main *** this view,we propose utilizing deep learning and ensemble learning techniques to boost crude oil’s price forecasting *** suggested method is based on a deep learning snapshot ensemble method of the Transformer *** examine the superiority of the proposed model,this paper compares the proposed deep learning ensemble model against different machine learning and statistical models for daily Organization of the Petroleum Exporting Countries(OPEC)oil price *** results demonstrated the outperformance of the proposed method over statistical and machine learning *** precisely,the proposed snapshot ensemble of Transformer method achieved relative improvement in the forecasting performance compared to autoregressive integrated moving average ARIMA(1,1,1),ARIMA(0,1,1),autoregressive moving average(ARMA)(0,1),vector autoregression(VAR),random walk(RW),support vector machine(SVM),and random forests(RF)models by 99.94%,99.62%,99.87%,99.65%,7.55%,98.38%,and 99.35%,respectively,according to mean square error metric.

关键词： Deep learning ensemble learning transformer model crude oil price

Measurements of natural radionuclides in soil samples from Upper Egypt

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Nuclear Science and Techniques 2008年第5期19卷 302-307页

作者： Shaban ramadan mohamed HARB Khaled SALAHEL DIN Abd Elbaset ABBADY mohamed Abd Elleh ali Rolf MICHEL Physics Department Faculty of ScienceSouth Valley University Center for Radiation Protection and Radioecology Hanover University (ZSR)

This paper presents the results of natural radioactivity measured for the soil of Qena using gamma-ray spectrometry at ZSR,Hanover University,*** samples of radioactive concentrations of ^(238)U-series (^(234)Th, ^(214)pb,and^(214)Bi),^(232)Th-series (^(228)Ac,^(212)pb,and ^(208)T1) and ^(40)K were *** objectives were set:(1) activity levels by surface soil sampling at 0～30 cm depth,(2) dose rates of gamma radiation,radium equivalent,index hazard, and effective dose,and (3) ambient dose rates.

关键词：土壤环境放射能 γ光谱测定法辐射暴露环境剂量

Geology and Mineral Chemistry of Uranium-and Thorium-bearing Minerals in Rare-Metal(NYF)Pegmatites of Um Solimate,South Eastern Desert,Egypt

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Acta Geologica Sinica(English Edition) 2021年第5期95卷 1568-1582页

作者： mohamed A.ali ahmed E.ABDEL GAWAD mohamed M.GHONEIM Nuclear Materials Authority 530 El-MaadiCairoEgypt

The garnet muscovite granitic pegmatite of Um Solimate,in southern Egypt,represents a promising asset for strategic and economic metals,especially Bi-Ni-Ag-Nb-Ta as well as U and *** ore bodies occur as large masses,pockets and/or veins of very coarse-grained pegmatites,which consist mainly of K-feldspar,quartz and albite with subordinate muscovite,garnet,and *** data revealed that e U-and e Th-contents of the pegmatites reach up to 39 ppm and 82 ppm,*** studied pegmatites are enriched in primary U and Th minerals(uraninite,coffinite,thorianite and uranothorite)as well as Hf-rich zircon and monazite,which give rise to anomalous radioactive ***-tantalium-bearing minerals(***,microlite and uranopyrochlore),xenotime,barite,galena,fluorite,and apatite are ubiquitous,and,consequently,the studied pegmatites belong tothe Niobium-Yttrium-Fluorine-type(NYF)*** noble metal mineralization includes argentite(Ag_(2)S),native Ni and Bi as well as bismite and *** addition,beryl and tourmaline are observed in pegmatites near the contact with metasediments and ultramafic *** observed compositional variations of Ta/(Ta+Nb)and Mn/(Mn+Fe)ratios in columbite(0.08-0.45 and 0.11-0.57,respectively)and Hf contents in zircon(3.54-6.46 wt%)may reflectan extreme degree of magmatic fractionation leading to formation of the pegmatite orebody.

关键词： radioactivity rare-metal mineralization pegmatites U/Th-bearing minerals Um Solimate Egypt

The vitreomacular interface in different types of agerelated macular degeneration

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International Journal of Ophthalmology(English edition) 2017年第2期10卷 246-253页

作者： mohamed Abd ElM onaem El-Hifnawy Hisham ali Ibrahim Amir ramadan Gomaa mohamed A Elmasry Ophthalmology Department Alexandria University Faculty of MedicineKhartoum SquareAzaritaAlexandria 21526Egypt

AIM： To evaluate the vitreomacular interface in cases with wet age-related macular degeneration（AMD） and to compare them to eyes with dry AMD and normal ***： This was a cross-sectional comparative study that included 87 eyes with wet AMD,42 eyes with dry AMD and 40 eyes without AMD as a control *** coherence tomography（OCT） examination was performed for all patients to assess the vitreomacular ***： In the wet AMD group,34.5% of cases had vitreomacular adhesion（VMA）.Only 14.3% of dry AMD cases and 10% of control cases had *** was a significant difference between the control group and the wet AMD group（P=0.004） as well as the dry and wet AMD group（P=0.017）.There was also a significant difference between the incidence of VMA in patients with subretinal choroidal neovascularization（CNV,type 1） and intraretinal CNV（type 2 or type 3）（P=0.020）.CONCLUSION： There is an association between posterior vitreous attachment and *** is also an increased incidence of VMA with intra-retinal CNV.

关键词： age-related macular degeneration vitreomacular interface optical coherence tomography macula

Gut virome:New key players in the pathogenesis of inflammatory bowel disease

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World Journal of Methodology 2025年第2期15卷 27-43页

作者： Helal F Hetta Rehab ahmed Yasmin N ramadan Hayam Fathy Mohammed Khorshid mohamed M Mabrouk Mai Hashem Department of Medical Microbiology and Immunology Faculty of MedicineAssiut UniversityAssiut 71515Egypt Division of Microbiology Immunology and BiotechnologyFaculty of pharmacyUniversity of TabukTabuk 71491Saudi Arabia Division of Microbiology Immunology and BiotechnologyDepartment of Natural Products and Alternative MedicineFaculty of PharmacyUniversity of TabukTabuk 71491Saudi Arabia Department of Internal Medicine Division HepatogastroenterologyAssiut UniversityAssiut 71515Egypt Department of Clinical Research Egyptian Developers of Gastroenterology and Endoscopy FoundationCairo 11936Egypt Department of Internal Medicine Faculty of Medicine.Tanta UniversityTanta 31527Egypt Department of Tropical Medicine Gastroenterology and HepatologyAssiut University HospitalAssiut 71515Egypt

Inflammatory bowel disease(IBD)is a chronic inflammatory illness of the *** the mechanism underlying the pathogenesis of IBD is not fully under-stood,it is believed that a complex combination of host immunological response,environmental exposure,particularly the gut microbiota,and genetic suscept-ibility represents the major *** gut virome is a group of viruses found in great frequency in the gastrointestinal tract of *** gut virome varies greatly among individuals and is influenced by factors including lifestyle,diet,health and disease conditions,geography,and *** majority of research has focused on the significance of gut bacteria in the progression of IBD,although viral populations represent an important component of the *** conducted this review to highlight the viral communities in the gut and their expected roles in the etiopathogenesis of IBD regarding published research to date.

关键词： Inflammatory bowel disease Pathogenesis Gut virome Bacteriophage Eukaryotic viruses