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Tuning the reactivity of TiO_(2)layer with uniform distribution of Sub-5 nm Fe_(2)O_(3)particles via in situ voltage-assisted oxidation for robust catalytic reduction

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Nano Materials Science 2024年第2期6卷 223-234页

作者： Nisa Nashrah abdelkarim chaouiki Wail Al Zoubi Young Gun Ko Integrated Materials chemistry Laboratory School of Materials Science and EngineeringYeungnam UniversityGyeongsan38541Republic of Korea

The trade-off between efficiency and stability has limited the application of TiO_(2)as a catalyst due to its poor surface ***,we present a modification of a TiO_(2)layer with highly stable Sub-5 nm Fe_(2)O_(3)nanoparticles(NP)by modulating its structure-surface reactivity relationship to attain efficiency-stability balance via a voltage-assisted oxidation *** situ simultaneous oxidation of the Ti substrate and Fe precursor using high-energy plasma driven by high voltage resulted in uniform distribution of Fe_(2)O_(3)NP embedded within porous TiO_(2)*** surface characterizations with density functional theory demonstrated an improved electronic transition in TiO_(2)due to the presence of surface defects from reactive oxygen species and possible charge transfer from Ti to Fe;it also unexpectedly increased the active site in the TiO_(2)layer due to uncoordinated electrons in Sub-5 nm Fe_(2)O_(3)NP/TiO_(2)catalyst,thereby enhancing the adsorption of chemical functional groups on the *** unique embedded structure exhibited remarkable improvement in reducing 4-nitrophenol to 4-aminophenol,achieving approximately 99%efficiency in 20 min without stability decay after 20 consecutive cycles,outperforming previously reported TiO_(2)-based *** finding proposes a modified-electrochemical strategy enabling facile construction of TiO_(2)with nanoscale oxides extandable to other metal oxide systems.

关键词： Titanium dioxide Oxide nanoparticle Electrochemical oxidation Surface reactivity Efficiency Stability

Exploring Trees Diversity and Ecological Value of Mountain Forests in the Blue Nile Region of Sudan

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Open Journal of Ecology 2024年第3期14卷 245-256页

作者： Dafa-Alla M. Dafa-Alla Haytham H. Gibreel Ahmed A. H. Siddig Yousif E. Yagoub Hashim A. abdelkarim Khatir H.T. Saeed Ahmed I. Abuelbashar Faculty of Forestry-Shambat University of Khartoum Khartoum Sudan Harvard Forest Harvard University Petersham MA USA Faculty of Forest Science and Wood Technology University of Gezira Wad-Medani Sudan Department of Forestry and Range Sciences Faculty of Natural Resources and Environmental Studies Alsalam University Alfula Sudan Forest Research and Gum Arabic Centre Agricultural Research Corporation Khartoum-Soba Sudan

We carried out this research at Abu-Gaddaf Natural Forest Reserve (ANFR) which is located east of Blue Nile River, in Blue Nile State, Sudan. It aims at exploring tree composition assessing their diversity indices, and ecological importance values. For survey of types and estimation of density of tree species in the forest, we randomly distributed 97 circular sample plots (0.1 hectare (ha)). In each sample plot we identified all trees to the species level, recorded their frequencies and computed species diversity and importance value indices (IVI). A total of 13 tree species, which belong to 12 genera and nine families, were identified in the tree layer of the forest. Mean tree density in ANFR was 116 trees/ha, composed mainly of Boswellia papyrifera (Del.) Hochst. (48), followed by Combretum hartmannianu (19) and Lannea fruticosa (18). Fabaceae was the most common family followed by Combretaceae and Malvaceae. B. papyrifera Delile Hochst was the most abundant while Acacia seyal was the least abundant species. Species richness (R = 1.71), evenness (E = 0.69), dominance (0.24) indices and Simpson’s Index of Diversity (D' = 0.76) suggest a moderate diversity, moderate numbers of individuals in each species and a moderate community stability. The research provides empirical results on diversity and ecological importance value of species, signifies the urging need to safeguard threatened species and to prioritize them for conservation, as well as the need to promote management of abundant species to provide multiple forest ecosystem services.

关键词： Tree Species Diversity Dry-Land Forest Sudan

Recent Advances in Multifunctional Reticular Framework Nanoparticles:A Paradigm Shift in Materials Science Road to a Structured Future

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纳微快报:英文版 2023年第11期15卷 435-502页

作者： Maryam chafiq abdelkarim chaouiki Young Gun Ko Materials Electrochemistry Group School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541Republic of Korea

Porous organic frameworks(POFs)have become a highly sought-after research domain that offers a promising avenue for developing cutting-edge nanostructured materials,both in their pristine state and when subjected to various chemical and structural ***–organic frameworks,covalent organic frameworks,and hydrogen-bonded organic frameworks are examples of these emerging materials that have gained significant attention due to their unique properties,such as high crystallinity,intrinsic porosity,unique structural regularity,diverse functionality,design flexibility,and outstanding *** review provides an overview of the state-of-the-art research on base-stable POFs,emphasizing the distinct pros and cons of reticular framework nanoparticles compared to other types of nanocluster ***,the review highlights the unique opportunity to produce multifunctional tailoring nanoparticles to meet specific application *** is recommended that this potential for creating customized nanoparticles should be the driving force behind future synthesis efforts to tap the full potential of this multifaceted material category.

关键词： Porous organic framework Reticular chemistry Reticular framework nanoparticle Environmental remediation Multifunctional material

Advanced prediction of organic–metal interactions through DFT study and electrochemical displacement approach

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Journal of Magnesium and Alloys 2023年第1期11卷 301-316页

作者： abdelkarim chaouiki Wail Al Zoubi Young Gun Ko Materials Electrochemistry Group School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541South Korea

Heterocyclic compounds are the promising biological compounds as nature-friendly for the corrosion protection of metallic *** this work,three heterocyclic compounds such as 1-azanaphthalene-8-ol(8-AN),2-methylquinoline-8-ol(8-MQ),and 8-quinolinol-5-sulfonic acid(8-QSA)were used as green compounds,and their anti-corrosion performance for AZ31 Mg in saline water was discussed on the basis of impedance interpretation and surface *** found that the electrochemical performance was improved in the order of 8-AN>8-MQ>8-QSA,demonstrating the electron donor effect of N-heterocycles to form coordination complexes on the magnesium *** the electrochemical performance,the protective layer constructed at the optimal concentration reinforces the barrier against aggressive environments,with potential inhibition efficiency of 87.4%,99.0%,and 99.9%for 8-QSA,8-MQ,and 8-AN,*** chemical parameters and electron density distribution for free organic species in the absence and presence of Mg^(2+)cation were evaluated using density functional theory(DFT).Upon the formation of coordination complexes between organic compound and Mg^(2+),energy gap underwent change about ΔE=5.7 eV in the 8-AN/Mg^(2+)***,the adsorption of heterocyclic compounds on Mg surface reveals the formation of strong covalent bonds with Mg atoms,which further confirmed by the electron density difference and projected density of states *** on theoretical calculations,three inhibitors can adsorb on the metal surface in both parallel and perpendicular orientations via C,O and N *** the parallel configuration,the C-Mg,N-Mg and O-Mg bond distances are between 2.11 and 2.25˚A,whereas the distances in the case of perpendicular adsorption are between 2.20 and 2.40˚A(covalent bonds via O and N atoms).The results indicated that parallel configurations are energetically more stable,in which the adsorption energies are-4.48 eV(8-AN),-4.28 eV(8-MQ)and-3.82 e

关键词： Organic layer Heterocyclic compounds Electrochemical behavior DFT modeling

Fabrication of branch-like Aph@LDH-MgO material through organic-inorganic hybrid conjugation for excellent anti-corrosion performance

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镁合金学报(英文) 2023年第7期11卷 2469-2485页

作者： Maryam chafiq abdelkarim chaouiki Rachid Salghi Young Gun Ko Materials Electrochemistry Laboratory School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541Republic of Korea Laboratory of Applied chemistry and Environment ENSAUniversity Ibn ZohrPO Box 1136Agadir80000Morocco

Layered double hydroxides(LDH)frameworks have shown significant enhancement in stability and reusability,and their tailorable architecture brings new insight into the development of the next generation of hybrid materials,which attracted considerable attention in many fields over the *** of the factors contributing to the widespread applicability of layered double hydroxides is their adaptable composition,which can accommodate a wide spectrum of potential anionic *** exceptional property makes the LDH system simple to adjust for various ***,most LDH systems are synthesized in situ in an autoclave at high temperatures and pressures that severely restrict the industrial use of such coating *** this study,LDH was directly synthesized on a magnesium alloy that had undergone plasma electrolytic oxidation(PEO)treatment in the presence of ethylenediaminetetraacetic acid,thereby avoiding the use of hydrothermal autoclave *** LDH system was compared with a hybrid architecture consisting of organic-inorganic *** organic layer was fabricated on top of the LDH film using 4-Aminophenol(Aph)compound,resulting in a smart hierarchical structure that can provide a robust Aph@LDH film with excellent anti-corrosion *** the molecular level,the conjugation characteristics and adsorption mechanism of Aph molecule were studied using two levels of theory as ***,Localized orbit locator(LOL)-πisosurface,electrostatic potential(ESP)distribution,and average local ionization energy(ALIE)on the molecular surface were used to highlight localization region,reveal the favorable electrophilic and nucleophilic attacks,and clearly explore the type of interactions that occurred around interesting ***,first-principles based on density functional theory(DFT)was applied to study the hybrid mechanism of Aph on LDH system and elucidate their mutual *** experimental and computational analyses suggest t

关键词： Magnesium alloy Surface modification LDH Organic-inorganic hybrid materials Inter-/intra-molecular interactions

Robust SVM-direct torque control of induction motor based on sliding mode controller and sliding mode observer

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Frontiers in Energy 2020年第4期14卷 836-849页

作者： abdelkarim AMMAR Amor BOUREK Abdelhamid BENAKchA LGEB Laboratory Department of Electrical EngineeringUniversity of BiskraBiskraBP 145Algeria

This paper proposes a design of control and estimation strategy for induction motor based on the variable structure *** describes a coupling of sliding mode direct torque control(DTC)with sliding mode flux and speed *** algorithm uses direct torque control basics and the sliding mode approach.A robust electromagnetic torque and flux controllers are designed to overcome the conventional SVM-DTC draw・backs and to ensure fast response and full reference tracking with desired dynamic behavior and low ripple *** sliding mode controller is used to generate reference voltages in stationary frame and give them to the controlled motor after modulation by a space vector modulation(SVM)*** second aim of this paper is to design a sliding mode speed/flux observer which can improve the control performances by using a sensorless algorithm to get an accurate estimation,and consequently,increase the reliability of the system and decrease the cost of using *** effectiveness of the whole composed control algorithm is investigated in different robustness tests with simulation using Matlab/Simulink and verified by real time experimental implementation based on dS pace 1104 board.

关键词： induction motor direct torque control(DTC) space vector modulation(SVM) sliding mode control(SMC) sliding mode observer(SMO) dS1104

Laminar and Turbulent characteristics of the Acoustic/Fluid Dynamics Interactions in a Slender Simulated Solid Rocket Motor chamber

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Computer Modeling in Engineering & Sciences 2021年第5期127卷 437-467页

作者： abdelkarim Hegab Faisal Albatati Mohammed Algarni Department of Mechanical Engineering Faculty of Engineering at RabighKing Abdulaziz UniversityRabigh21911Saudi Arabia

In this paper,analytical,computational,and experimental studies are integrated to examine unsteady acoustic/vorticity transport phenomena in a solid rocket motor chamber with end-wall disturbance and side-wall ***-fluid dynamic interactions across the chamber may generate intense unsteady vorticity with associated shear *** stresses may cause scouring and,in turn,enhance the heat rate and erosional burning of solid propellant in a real rocket *** this modelling,the unsteady propellant gasification is mimicked by steady-state flow disturbed by end-wall *** analytical approach is formulated using an asymptotic technique to reduce the full governing *** equations that arise from the analysis possess wave properties are solved in an initial-boundary value *** numerical study is performed by solving the parabolized Navier–Stokes equations for the DNS simulation and unsteady Reynolds-averaged Navier–Stokes equations along with the energy equation using the control volume approach based on a staggered grid system with the turbulence *** v2-f turbulence model has been *** results show that an unexpectedly large amplitude of unsteady vorticity is generated at the injection side-wall of the chamber and is then penetrated downstream by the bulk motion of the internal *** stresses may cause a scouring effect and large transient heat transfer on the combustion surface.A comparison between the analytical,computational,and experimental results is performed.

关键词： Acoustic waves solid rocket motor chamber sidewall injection perturbation analysis acoustic instability turbulence models manuscript

COURSE TIMETABLING AT A TUNISIAN UNIVERSITY:A CASE STUDY

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Journal of Systems Science and Systems Engineering 2008年第3期17卷 334-352页

作者： Abdelaziz DAMMAK abdelkarim ELLOUMI Hichem KAMOUN Jacques A.FERLAND Department of Applied Quantitative Methods GIAD Laboratory University of SfaxFSEGTunisia Department of Applied Quantitative Methods GlAD Laboratory University of SfaxFSEGTunisia Département d'Informatique et de Recherche Opérationnelle Universitéde Montréal QuébecCanada

This paper deals with the Course Timetabling Problem at an institution in a Tunisian University. We introduce a heuristic procedure to construct a feasible timetable for all lectures and tutorials taken by different groups of each sub-section of any section. We describe the timetabling problem using a list of all specific hard and soft constraints. We formulate the problem as a set of linear constraints using two sets of binary variables corresponding to lectures and tutorials, respectively. This heuristic is illustrated with real data for a sub-section of the Faculty of Economics and Management Sciences of Sfax in Tunisia, and the resulting timetables are compared with those generated manually. The results of another full section have confirmed the good quality of the proposed heuristic when compared with the hand made solution.

关键词： Educational timetabling integer programming implementations heuristic search

Awareness of Hail Region Population about Facial Nerve Palsy (Seventh Cranial Nerve Palsy)

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Neuroscience & Medicine 2022年第3期13卷 111-119页

作者： Ghorashy Eltayeb Yousif Turki Saud Alshammari Hamoud abdelkarim Almarshadi College of Medicine University of Ha’il Ha’il Saudi Arabia Department of Pathology and Microbiology University of Kordofan El-Obeid Sudan

Background: Facial nerve palsy (seventh cranial nerve palsy) is a common neurological problem. The etiology is not fully understood but it is thought to be due to injury or compression throughout the seventh cranial nerve course. The study aimed to evaluate the awareness of the Hail region population about facial nerve palsy, its risk factors, methods of treatment, and prognosis. Methodology: This cross-sectional descriptive study was conducted in the Hail region from March to June 2022. The study involved 224 participants in the age group 18 - 65 years and data was collected through Google self-administered questionnaire. Results: 65.2% of the participants were 18 - 25 years, 20.1% were 26 - 35 years and 14.7 were above 35 years. 91.9% think that exposure to cold air is the leading cause followed by viral infections (30.4%), stroke (27.6%), and genetic factors (13.8%). diabetes (8.5%), evil eye (7.1%), magic (4%), pregnancy (0.4%) and vitamins deficiency (0.4%). 92% of participants think that facial nerve palsy is not contagious and 8% have no clear idea. 89.7% think that facial nerve palsy is curable, 83.9% think that physiotherapy is the treatment of choice, 94.6% agree that early medical assessment is essential for good outcomes and 92.9 believe that avoidance of cold air is the best method of prevention. Conclusion and Recommendations: The majority of participants show poor awareness regarding the etiology and the preferable treatment of facial nerve palsy. Public medical education and further wider studies are highly recommended.

关键词： Facial Palsy Causes Treatment Hail Awareness