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Electrospinning of Nylon-6,6 Solutions into Nanofibers: Rheology and Morphology Relationships

Chinese Journal of Polymer Science 2014年第6期32卷 793-804页

作者： Ali Abbasi mohamed mahmoud nasef Matsuura Takeshi Reza Faridi-Majidi Faculty of Chemical Engineering Universiti Teknologi Malaysia Institute of Hydrogen Economy International Campus Universiti Teknologi Malaysia Malaysia-Japan International Institute of Technology International Campus Universiti Teknologi Malaysia Department of Chemical & Biological Engineering University Ottawa Department of Medical Nanotechnology School of Advanced Medical Technologies Tehran University of Medical Sciences

The relationship between the rheological properties of nylon-6,6 solutions and the morphology of their electrospun nanofibers was established. The viscosity of nylon-6,6 in formic acid （90%） was measured in the concentration range of 5 wt%-25 wt% using a programmable viscometer. Electrospinning of nylon-6,6 solutions was carried out under controlled parameters. The chemical structure, morphology and thermal properties of the obtained nanofibers were investigated using Fourier transform infrared spectroscopy （FTIR）, scanning electron microscopy （SEM） and differential scanning calorimetry （DSC）, respectively, Entanglement concentration （ce） was found to be 15 wt% and a power law relationship between specific viscosity and solution concentration was observed with exponents of 2.0 and 3.3 for semi-dilute unentangled （c 〈 ce） and semi-dilute entangled （c 〉 ce） regimes, respectively. The diameter and uniformity of the nanofibers were found to be dependent on the viscosity. Moreover, the average diameter of electrospun nanofibers was found to be dependent on zero shear rate viscosity and normalized concentration （c/ce） in a power law relationship with exponents of 0.298 and 0.816, respectively. For nylon-6,6 solutions, the entanglement concentration （ce = 15 wt%） provides the threshold viscosity required for the formation of a stable polymeric jet during electrospinning and producing uniform beadless fibers. For concentrations less than ce, beaded fibers with some irregularities are formed. DSC analysis showed an increase in crystallinity of all electrospun samples compared to original polymer. Furthermore; Based on FTIR spectroscopy, α phase is dominant in electrospun nanofibers and minor amount offland ）,phases is also available.

关键词： Nylon-6,6 electrospinning Viscosity Nanofibers Entanglement concentration Crystallinity.

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Production of Biodiesel from Cottonseed Oil over Aminated Flax Fibres Catalyst: Kinetic and Thermodynamic Behaviour and Biodiesel Properties

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Advances in Chemical Engineering and Science 2019年第4期9卷 281-298页

作者： Rihab Musaad Moawia mohamed mahmoud nasef Nor Hasimah mohamed Adnan Ripin Hamdy Farag School of Chemical and Energy Engineering Universiti Teknologi Malaysia Skudai Malaysia Chemical Engineering Department Universiti Teknologi PETRONAS Seri Iskandar Malaysia Malaysia Japan International Institute of Technology Universiti Teknologi Malaysia Kuala Lumpur Kuala Lumpur Malaysia Radiation Processing Technology Division Malaysian Nuclear Agency Kajang Malaysia Chemistry Department Faculty of Science Mansoura University Mansoura Egypt Department of Material Process Engineering Graduate School of Engineering Kyushu University Fukuoka Japan

The transesterification of cottonseed oil in the presence of methanol to fatty acid methyl ester (FAME) using flax-based fibres catalyst modified with an alkaline moiety was studied. The catalyst was prepared by radiation induced grafting (RIG) of glycidyl methacrylate (GMA) onto dignified flax fibres followed by amination with diethylamine (DEA) and treatment with NaOH solution. A maximum FAME conversion of 88.6% was obtained at 60°;C with a catalyst dosage of 2.5 wt%, an oil/methanol ratio of 1:33 and a time of 2 h. The biodiesel quality was verified by nuclear magnetic resonance (1H NMR). Kinetic analysis showed a reaction activation energy of 69.33 kJ·molˉ1 and a rate constant of 0.00349 minˉ1 indicating that the catalytic reaction was kinetically controlled. Thermodynamic analyses revealed that the reaction was reversible, non-spontaneous and endothermic with an enthalpy of 66.62 kJ·molˉ1. The obtained biodiesel showed physical and chemical characteristics complying with ASTM D6751. It can be concluded that the alkaline biopolymer catalyst prepared in the present study is a promising green candidate for biodiesel production.

关键词： Biodiesel Production Radiation Grafted Basic Flax Fibres Catalyst Cottonseed Oil Transesterification Kinetics and Thermodynamics Radiation Induced Grafting

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RADIATION GRAFTED POLY(VINYLIDENE FLUORIDE)-GRAFT-POLYSTYRENE SULFONIC ACID MEMBRANES FOR FUEL CELLS:STRUCTURE-PROPERTY RELATIONSHIPS

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Chinese Journal of Polymer Science 2010年第5期28卷 761-770页

作者： mohamed nasef Hamdani Saidi Khairulzaman Mohd Dahlan Institute of Hydrogen Economy Universiti Teknologi MalaysiaInternational City CampusJalan Semarak54100 Kuala LumpurMalaysia Faculty of Chemical and Natural Resources Engineering Universiti Teknologi Malaysia81310 UTM SkudaiJohorMalaysia Radiation Processing Technology Division Malaysian Nuclear AgencyBangi43000 KajangSelangorMalaysia

Structure-property relationships for poly（vinylidene fluoride）-graft-polystyrene sulfonic acid （PVDF-g-PSSA） fuel cell membranes prepared by a single step method involving radiation-induced grafting of sodium styrene sulfonate （SSS） onto electron beam （EB） irradiated poly（vinylidene fluoride）（PVDF） films were established. The physico-chemical properties of the membranes such as ion exchange capacity, water swelling and proton conductivity were correlated with the degree of grafting （G, %） and the structural changes taking place in the membrane matrix during the preparation procedure. The variation in the crystallinity and the thermal stability of membranes was studied by differential scanning calorimetry （DSC） and thermogravimetric analysis （TGA）, respectively. The membranes were found to undergo substantial structural changes in forms of ionic sites increase, hydrophilicity enhancement, hydrophobicity reduction and crystallinity decrease with the variation in G （%） and the preparation method. The structural and thermal properties of the obtained membranes were also compared with their counterparts prepared by a conventional two-steps method i.e. radiation induced grafting of styrene onto EB irradiated PVDF films followed by sulfonation. The PVDF-g-PSSA membranes obtained by a single-step method were found to have superior properties compared to those obtained by the conventional two-steps method.

关键词： PVDF films Sodium styrene sulfonate Radiation-induced grafting Proton exchange membranes.

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Analysing user daylight preferences in heritage buildings using virtual reality

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Building Simulation 2022年第9期15卷 1561-1576页

作者： mohamed Marzouk Maryam ElSharkawy Ayman mahmoud Department of Structural Engineering Faculty of EngineeringCairo University12613GizaEgypt Department of Architecture Engineering Faculty of EngineeringCairo University12613GizaEgypt

Technology has always been creating effective ways to support human *** virtual reality(IVR)has emerged to engage users in a simulated world,and this has gained the interest of a wide variety of users in the heritage industry.A historical case study built in the early 19th century is considered for an adaptive reuse *** palace is located in Cairo,Egypt,and named after Prince Omar *** current palace state incorporates a smashed top-lit zone,which is being studied and analyzed for daylighting *** simulated distinct optimum skylight configurations are suggested for the redesign where the selection should not be based solely on simulation data,but should consider real-user *** daylight design criteria are previously based on simulation data that do not necessarily indicate the users'*** utilizing user interactive tools such as IVR to test daylight redesign options,a whole new dimension is *** this study,the VR users’survey data is statistically analyzed using Statistical Package for Social Sciences(SPSS),where results revealed that the assessment attributes succeeded in reflecting the users'preferences;which,motivated designers to consider potential users’daylight preferences in reused *** paper highlights the most significant emotional attributes that provide cost-effective and reliable information concerned with the performance of daylight in IVR before design *** study compares and analyzes the effect of three skylight designs(Cases A,B&C)on the users'perception before design implementation using(IVR)***-eight participants have contributed to the study,providing their feedback on six attributes namely:Pleasant,Contrasting,Brightness,Uniform Distribution,Visual Comfort,and *** attributes are evaluated for the three cases in space using five scale rating values to reveal that the"Pleasant"attribute is most reliable in the study to reflect th

关键词： daylight preferences heritage buildings rehabilitation immersive virtual reality statistical analysis

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Seismic performance of high-rise buildings in selected regions in Saudi Arabia according to different seismic codes

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Earthquake Engineering and Engineering Vibration 2021年第1期20卷 179-191页

作者： Sayed mahmoud mohamed Alsearheed Waleed Abdallah Department of Civil and Construction Engineering College of EngineeringImam Abdulrahman Bin Faisal UniversitySaudi Arabia Department of Building Engineering College of ArchitectureImam Abdulrahman Bin Faisal UniversitySaudi Arabia Department of Civil Engineering College of Engineering at MatariaHelwan UniversityCairoEgypt

The design code for each country is revised and updated based on an expected zone’s seismic intensities,geotechnical site classifications,structural systems,construction materials and methods of construction in order to provide more realistic considerations of seismic demand,seismic response,and seismic *** on the aforementioned provisions,structures designed according to different seismic codes may yield different performances for the same level of *** study aims to investigate and compare the induced responses related to the earthquake-resistant design of reinforced concrete(RC)buildings according to the Saudi building code(SBC-301),American code(ASCE-7),uniform building code(UBC-97),and European code(EC-8).In order to account for the provision regarding the hazard specification and its effect on the induced seismic responses,four regions in the Kingdom of Saudi Arabia with different seismic levels are *** code provisions related to the specification of site classification and its effect on the induced design base shear are investigated as *** differences are observed in the induced responses with the variation in seismic design codes for the considered seismic hazards and site classifications.

关键词： high-rise building SBC-301 international seismic codes seismic zones site classifications

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The Rank of the 2-Class Group of Some Fields with LargeDegree

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Algebra Colloquium 2022年第2期29卷 181-188页

作者： mohamed mahmoud Chems-Eddin Department of Mathematics Faculty of Sciences Dhar El Mahraz Sidi Mohamed Ben Abdellah UniversityFezMorocco

Let n≥3 be an integer and d an odd square-free *** compute the rank of the 2-class group of some fields of the form L_(n,d)=Q(ζ_(2^(n)),√d)when all the prime divisors of d are congruent to±3(mod 8)or 9(mod 16).

关键词： cyclotomic Z_(2)-extension 2-rank 2-class group

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Unveiling the complexities of microbiologically induced corrosion:mechanisms,detection techniques,and mitigation strategies

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Frontiers of Environmental Science & Engineering 2024年第10期18卷 15-48页

作者： mahmoud A.Ahmed Safwat A.mahmoud Ashraf A.mohamed Veolia Water Technologies Cairo 11835Egypt Chemistry department Faculty of ScienceAin Shams UniversityCairo 11566Egypt Physics Department Faculty of ScienceNorthern Border UniversityArar 13211Saudi Arabia

Microbiologically induced corrosion(MIC)is a complex and destructive phenomenon that occurs in various sectors,involving the interaction between microorganisms and metal surfaces,resulting in accelerated corrosion *** review article provides a comprehensive analysis of MIC,encompassing microbial species involved,their metabolic activities,and influential environmental factors driving the corrosion *** mechanisms of MIC,both in the presence and absence of oxygen,are explored,along with the diverse effects of microbes on different types of corrosion and their economic *** and monitoring techniques,including traditional and advanced methods such as microbiological and electrochemical methods,are ***,it examines preventive and control measures,such as the use of biocides and their mechanisms of *** to enhance the performance of these control measures and the effectiveness of antimicrobial agents during disinfection processes,including surfactants and chelators,are ***,the review highlights enzymatic remediation as a sustainable alternative approach,providing detailed *** challenges in mitigating MIC and potential future developments and collaborative opportunities are also *** systematic review is a valuable resource for researchers,industry professionals,and policymakers seeking a comprehensive understanding of the complex phenomenon of MIC and effective strategies for its management.

关键词： Metal failure Biofilm formation Enzymatic remediation Antimicrobial agents Bio-corrosion mechanisms

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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

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Price Prediction of Seasonal Items Using Machine Learning and Statistical Methods

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Computers, Materials & Continua 2022年第2期70卷 3473-3489页

作者： mohamed Ali mohamed Ibrahim mahmoud El-Henawy Ahmad Salah Faculty of Computers and Informatics Zagazig UniversityZagazigEgypt

Price prediction of goods is a vital point of research due to how common e-commerce platforms *** are several efforts conducted to forecast the price of items using classicmachine learning algorithms and *** models can predict prices of various financial instruments,e.g.,gold,oil,cryptocurrencies,stocks,and second-hand *** these efforts,the literature has no model for predicting the prices of seasonal goods(e.g.,Christmas gifts).In this context,we framed the task of seasonal goods price prediction as a regression ***,we utilized a real online trailer dataset of Christmas gifts and then we proposed several machine learningbased models and one statistical-based model to predict the prices of these seasonal ***,we utilized a real-life dataset of Christmas gifts for the prediction ***,we proposed support vector regressor(SVR),linear regression,random forest,and ridgemodels as machine learningmodels for price ***,we proposed an autoregressive-integrated-movingaverage(ARIMA)model for the same purpose as a statistical-based ***,we evaluated the performance of the proposed models;the comparison shows that the best performing model was the random forest model,followed by the ARIMA model.

关键词： ARIMA machine learning price prediction random forest ridge support vector regressor

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Solid solution evolution during mechanical alloying in Cu–Nb–Al compounds

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International Journal of Minerals,Metallurgy and Materials 2019年第9期26卷 1129-1139页

作者： Kaouther Zaara mahmoud Chemingui Virgil Optasanu mohamed Khitouni Laboratory of Inorganic Chemistry UR 11-ES-73University of SfaxB.P. 1171Sfax 3018Tunisia ICB UMR 6303 CNRSUniversity of Bourgogne Franche Comté9 av. Alain Savary21078 Dijon CedexFrance

This work concerns the structural evolution of Cu70Nb20Al10(at%) alloy processed by mechanical alloying using a planetary ball mill in air atmosphere for different times(4 to 200 h). The morphological, structural, microstructural, and thermal behaviors of the alloy were investigated by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and differential scanning calorimetry. X-ray diffraction patterns were examined using the Rietveld refinement technique with the help of the MAUD software. A disordered FCC-Cu(Nb,Al) solid solution was formed after 8 h of milling. The crystallite size, microstrain, and lattice parameter were determined by the Rietveld method. With increasing milling time, the crystallite size of the final product-ternary-phase FCC-Cu(Nb,Al)-is refined to the nanometer scale, reaching 12 nm after 200 h. This crystallographic structure combines good mechanical strength and good ductility. An increase in microstrain and partial oxidation were also observed with increasing milling time.

关键词： powder metallurgy mechanical alloying nanomaterials copper-based alloy solid solution

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