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Existence results and behavior analysis for nonlinear age-dependent population dynamics problems with conformable fractional operator

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International Journal of Biomathematics 2024年第5期17卷 229-256页

作者： Hiba el Asraoui M'hamed el Omari Ali el Mfadel khalid Hilal Laboratory of Applied Mathematics Scientific Computing Sultan Moulay Slimane University BP 523 Beni MellalMorocco

In this paper,we investigate the existence of solutions and analyze the large-time behavior for Gurtin-Maccamy population model involving conformable fractional *** a preliminary step,we construct a generic structure of the solution associated with our proposed model by utilizing some basic properties and tools of conformable fractional *** establish the existence of a unique solution of the given model with the given initial *** last,by using the upper and lower solutions for the characteristic equation,we define the upper and lower boundaries for the obtained solution and describe the large-time behavior of the total population.

关键词： Age-dependent population conformable fractional operator upper and lower boundary of the solution dynamics of populations

Saffron(Crocus sativus L.) stigmas as a potential natural additive to improve oxidative stability attributes of sunflower(Helianthus annuus L.) oil stored under different conditions

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Grain & Oil Science and Technology 2024年第3期7卷 133-149页

作者： Moussa Nid Ahmed Karima Abourat Jamila Gagour el Hassan Sakar khalid Majourhat Said Gharby Biotechnology Analytical Sciences and Quality Control Team Polydisciplinary Faculty of Taroudant University Ibnou Zohr Laboratory of Biology Ecology and Health FS Abdelmalek Essaadi University Geo-Bio-Environmental Engineering and Innovation Laboratory Polydisciplinary Faculty of Taroudant University Ibnou Zohr

The aim of our study was to explore the antioxidant potential of Moroccan saffron stigmas（SS） and examine their performance as a natural antioxidant in enhancing the stability and quality properties of edible sunflower oil（SO）, with a focus on understanding the critical importance of edible oil stability for predicting quality deterioration during storage. Bearing this in mind, our research was designed to compare the efficacy of three concentrations of dried SS（at 0.2%, 0.3%, and 0.6%） against tocobiol（a synthetic antioxidant） as a positive control（at 0.3% concentration）. This comparison was conducted under three distinct storage conditions namely accelerated ageing（60 ℃）, exposure to light at ambient temperature, and darkness, to evaluate their impact on preventing severe oxidation and extending oil shelf-life. Oxidation state evolution was evaluated through peroxide value（PV）, free fatty acid（FFA）, anisidine value（p-AV）, K270value（conjugated trienes）, total oxidation index（TOTOX）, iodine value（IV）, and fatty acid composition（FA）. Our results revealed notable differences in stability tracking parameters. Specifically, these parameters were higher in samples stored under accelerated conditions, followed by the samples stored in ambient light, while those stored in darkness showed the highest stability among the three storage conditions. Supplementation of sunflower oil with SS and tocobiol significantly enhanced its oxidation stability. Notably, SS exhibited exceptional effectiveness in stabilizing sunflower oil regardless of SS dose, with the highest efficacy observed at 0.6%. This was evidenced by the slower rate of oxidation parameters under various storage conditions, highlighting a superior antioxidant activity compared to both the non-enriched oil and tocobiol-enriched oil. Furthermore, saffron stigmas, used as a natural supplement,contributed to the preservation of polyunsaturated fatty acids, indicating its potential as a robust source of natural antioxidan

关键词： Crocus sativus L. Helianthus annuus L. Saffron stigmas Shelf-life Sunflower oil Tocobiol

Natural Convection of a Power-Law Nanofluid in a Square Cavity with a Vertical Fin

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Fluid Dynamics & Materials Processing 2024年第9期20卷 2091-2108页

作者： Amira M’hadbi Mohammed el Ganaoui Haïkel Ben Hamed Amenallah Guizani khalid Chtaibi LERMAB Department of Transition and Energy Efficiency ProfessionsIUT H Poincaréde LongwyUniversity of LorraineLongwy54400France LPT Center for Energy Research and Technologies(Borj Cedria2084)University of Tunis El ManarTunis1068Tunisia LTI Department of Mechanical Engineering and ProductionIUTUniversity of Picardie Jules-VerneAmiens80025France

The behavior of non-Newtonian power-law nanofluids under free convection heat transfer conditions in a cooled square enclosure equipped with a heated fin is investigated *** particular,the impact of nanofluids,composed of water and Al_(2)O_(3),TiO_(2),and Cu nanoparticles,on heat transfer enhancement is *** aim of this research is also to analyze the influence of different parameters,including the Rayleigh number(Ra=10^(4)-10^(6)),nanoparticle volume fraction(φ=0%-20%),non-Newtonian power-law indexes(n=0.6-1.4),and fin dimensions(Ar=0.3,0.5,and 0.7).Streamlines and isotherms are used to depict flow and related heat transfer *** indicate that thermal performance improves with increasing Rayleigh number,regardless of the nanoparticle type or nanofluid rheological *** suggests that the buoyancy force has a significant impact on heat transfer,particularly near the heat *** Nusselt number is more sensitive to variations in Cu nanoparticle volume fractions compared to Al₂O₃and TiO₂.Moreover,the average Nusselt numbers for power-law nanofluids with n1)are greater(smaller)than for Newtonian fluids due to the decrease(increase)in viscosity with increasing(decreasing)shear rate,at the same values of Rayleigh number Ra owing to the amplification(attenuation)of the convective ***,the most substantial enhancement is observed with Cu-water shear-thinning nanofluid,where the Nusselt number increases by 136%when changing from Newtonian to shear thinning behavior and by 154.9%when adding 16%nanoparticle volume ***,an even larger increase of 57%in the average Nusselt number is obtained on increasing the fin length from 0.3 to 0.7.

关键词： Heat transfer nanofluid non-Newtonian fluid natural convection

Stoichiometry and Stability Constant Values for Copper (II) Chelates with Ethylene Diamine in Deep Eutectic Solvents (DES) (Ethaline) Solutions

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Open Journal of Applied Sciences 2024年第9期14卷 2592-2609页

作者： khalid el Ttaib Abdolhadi Benhmid Rifat Hasan Omar Chemistry Department Faculty of Science University of Benghazi Benghazi Libya

In this study we used the deep eutectic solvents (ionic liquids) to investigate the reaction between copper (II) with ethylene diamine (en). Two of the existing methods for analyzing spectrophotometric measurements have been applied for establishing, the stoichiometry and whenever possible, the stability constants of the chelates formed. The method of continuous variations was necessary to determine first whether, the metal ion and the ligand ethylene diamine form one or more than one chelate, when more than one chelate formed, the results obtained depend on the wavelength and for meaningful conclusions the wavelengths were carefully selected. The empirical formulae of the chelates were further substantiated by the molar ratio method. The effect of time and temperature on the formation and stability of these chelates in solution is also studied. The stability constants, K1 and K2 for the copper (II) chelates were calculated, though reliable, and are comparable to literature values.

关键词： Cu(II) Ethylene Diamine (en) Deep Eutectic Solvents Job’s Method Ionic Liquids and Stability Constant

Determination of Latent Heats of Vaporization and Fusion

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Advances in Chemical Engineering and Science 2024年第3期14卷 113-124页

作者： Lahbib Abbas Lahcen Bih khalid Yamni Abderrahim elyahyaouy Abdelmalik el Attaoui Zahra Ramzi Chemistry Department Faculty of Science and Technology Moulay Ismail University Meknes Er-Rachidia Morocco Engineering Sciences and Professions Laboratory National School of Arts and Crafts Moulay Ismail University Meknes Meknes Morocco Materials Membranes and Nanotechnology Chemistry Department Faculty of Sciences Moulay Ismail University Meknes Zitoune Mekns Morocco Physics Department Faculty of Sciences Ibn Tofail University Kenitra Morocco Laboratory of Molecular Chemistry Materials and Environment (LCM2E) Multidisciplinary Faculty of Nador Mohamed 1st University Oujda Nador Morocco Laboratory of SCiMATOP Chemistry Department Faculty of Sciences Semlalia Cadi Ayyad University Marrakech Morocco

Water is the most abundant liquid on the surface of the earth. It is a liquid whose properties are quite surprising, both as a pure liquid and as a solvent. Water is a very cohesive liquid: its melting and vaporization temperatures are very high for a liquid that is neither ionic nor metallic, and whose molar mass is low. Thus, water remains liquid at atmospheric pressure up to 100C while similar molecules such as H2S, H2Se, H2Te for example would give a vaporization temperature close to 80C. This cohesion is in fact ensured by hydrogen bonds between water molecules. This type of bonds between neighboring molecules, hydrogen bonds, is quite often found in chemistry [1] [2]. Any change in the state of aggregation of a substance occurs with the absorption or release of a certain amount of latent heat of transformation. Latent heat of fusion, vaporization or sublimation is the ratio of the energy supplied as heat to the mass of the substance that is melted, vaporized or sublimated. As a result of the reversibility of the processes, the fusion heat is equal to the heat released in the reverse process: crystallization and solidification heat. And likewise the heat of vaporization is equal to the heat of condensation. This equality of heat is often used to determine experimentally either of these quantities. There are two main measurement methods: 1) Direct measurement using the calorimeter, 2) Indirect measure based on the use of the VantHoff relationship. The objective of this work is to measure the latent heat of water vaporization and verify the compatibility of the experimental values with the values given by the tables using the indirect method.

关键词： Latent Heat of Vaporization Latent Heat of Fusion Calorimetry Relationship of Vant’Hoff

Modeling environmental sensitivity and risk assessment of PAHs in sediments along two marine coastal areas in Egypt

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Petroleum Research 2024年第1期9卷 125-142页

作者： Muhammad A.el-Alfy National Institute of Oceanography and Fisheries NIOFCairoEgypt

Modeling the environmental sensitivity index(ESI)is vital in the planning and management processes,especially along the coastal *** main objectives of the study were to define the main sources of polycyclic aromatic hydrocarbons(PAHs),establish an ESI model,and measure the risk of PAHs on humans and the environment using various *** methodology of the research involved analyzing PAHs according to the EPA 550 methodology in sediments of the coastline in two important coastline areas in Egypt,namely the Gulf of Suez and the Mediterranean Sea,modeling the sensitivity of PAHs using ArcGIS 10.5 by integrating different physical,biological,and land use/cover factors,identifying the sources,and performing a risk *** sediment samples were collected from each *** produced sensitivity map could explain the highly sensitive areas along the Mediterranean Sea and Gulf of Suez coastlines(especially areas that were near drains'outlets,industrial sites,and sea ports).The highest mean PAH concentrations were Acenaphthylene and Fluorine in the Mediterranean Sea and Suez Gulf,***'s obvious that the individual PAH concentrations were within the ERL,ERM,and Pel threshold limits,indicating no adverse biological *** ratios of BaA/BaA+Chy,Flu/Flu+Py,and Ant/Ant+Phe gave an indication that most PAH sources were petrogenic(63.64%)and others(36.36%)were from petroleum *** principle component analysis(PCA)indicated a diverse correlation among the isomer ratios and LU/LC *** carcinogenic risk values were in the very low category(elines and seawater free of oil spillage act

关键词： Polycyclic aromatic hydrocarbons(PAHs) Modeling Sensitivity Gulf of Suez And Mediterranean sea

Systematic Method for Constructing Lewis Representations

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Open Journal of Inorganic Chemistry 2024年第1期14卷 1-18页

作者： Lahbib Abbas Lahcen Bih khalid Yamni Abderrahim elyahyaouy Abdelmalik el Attaoui Zahra Ramzi Materials Membranes and Nanotechnology Faculty of Science and Technology Moulay Ismail University Meknes Er-Rachidia Morocco Engineering Sciences and Professions Laboratory National School of Arts and Crafts Moulay Ismail University Meknes Meknes Morocco Materials Membranes and Nanotechnology Chemistry Department Faculty of Sciences Moulay Ismail University Meknes Meknes Morocco Physics Department Faculty of Sciences Ibn Tofail University Kenitra Morocco Laboratory of Molecular Chemistry Materials and Environment (LCM2E) Multidisciplinary Faculty of Nador Mohamed 1st University Oujda Nador Morocco Laboratory of SCiMATOP Chemistry Department Faculty of Sciences Semlalia Cadi Ayyad University Marrakech Morocco

The systematic method for constructing Lewis representations is a method for representing chemical bonds between atoms in a molecule. It uses symbols to represent the valence electrons of the atoms involved in the bond. Using a number of rules in a defined order, it is often better suited to complicated cases than the Lewis representation of atoms. This method allows us to determine the formal charge and oxidation number of each atom in the edifice more efficiently than other methods.

关键词： Systematic Method Lewis Representation Chemical Bond Formal Charge Oxidation Number

Graphite Carbone Structure

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Crystal Structure Theory and Applications 2024年第1期12卷 1-10页

作者： Lahbib Abbas Lahcen Bih khalid Yamni Abderrahim elyahyaouy Abdelmalik el Attaoui Zahra Ramzi Materials Membranes and Nanotechnology Laboratory Faculty of Science and Technology Moulay Ismail University Errachidia Morocco Engineering Sciences and Professions Laboratory National School of Arts and Crafts Moulay Ismail University Meknes Morocco Materials Membranes and Nanotechnology Laboratory Chemistry Department Faculty of Sciences Moulay Ismail Univer-sity Meknes Morocco Physics Department Faculty of Sciences Ibn Tofail University Kenitra Morocco Laboratory of Molecular Chemistry Materials and Environment (LCM2E) Multidisciplinary Faculty of Nador Mohamed 1st University Nador Morocco Laboratory of SCiMATOP Chemistry Department Faculty of Sciences Semlalia Cadi Ayyad University Marrakech Morocco

Carbon graphite is a crystalline form of carbon consisting of layers of hexagonal carbon atoms arranged in a two-dimensional “graphene” structure. Graphene layers are stacked on top of each other, forming a three-dimensional structure with a high degree of anisotropy. The carbon atoms within each layer are linked together by strong covalent bonds, creating a strong, stable lattice structure. However, the layers themselves are held together by weak van der Waals forces, enabling them to slide easily over each other. The properties of carbon graphite are highly dependent on the orientation and alignment of the graphene layers. When the layers are aligned parallel to each other, the material exhibits high strength and stiffness along the alignment direction, but is weaker and more flexible in other directions. Carbon graphite is used in a variety of applications where high strength, rigidity and electrical conductivity are required. Some common applications include electrical contacts, electric motor brushes, and as a structural material in aerospace and defense applications. The aim of our work is to describe the structure of graphite, its physical and chemical properties and its applications.

关键词： Graphite Graphene Hexagonal Structure Hardness Rigidity electrical Con-ductivity

Adaptive Backstepping Control Design for Semi-Active Suspension of Half-Vehicle With Magnetorheological Damper

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