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optimizing the defensive characteristics of mild steel via the electrodeposition of Zn-si3N4 reinforcing particles

Defence Technology（防务技术） 2019年第4期15卷 526-532页

作者： i.G. Akande o.o. oluwole o.s.i. fayomi Department of Mechanical Engineering University of Ibadan Ibadan Oyo state Nigeria Department of Mechanical Engineering Covenant University ota ogun state Nigeria Department of Chemical Metallurgical and Materials Engineering Tshwane University of Technology Pretoria South Africa

The effect of Zn-si3 N4 deposition prepared via direct electrolytic co-deposition on mild steel was studied as a result its inherent vulnerability to corrosion in an aggressive environment and failure on the application of *** experiment was conducted varying the mass concentration of silicon nitride(si3 N4)between 7 and 13 gat cell voltage of 0.3 and 0.5 V,at constant temperature of 45℃.The morphologies of the coated surfaces were characterized using high resolution Nikon optical Microscope and scanning Electron Microscope(sEM)revealing that the particles of the Zn-si3 N4 were homogeneously *** corrosion behaviour was studied using potentiodynamic polarization technique in 3.65%NaCl solution and the microhardness was examined using Brinell hardness testing *** result of the corrosion experiment confirmed an improved corrosion resistance with a reduction in corrosion rate from 9.7425 mm/year to 0.10847 mm/year,maximum coating efficiency of 98.9%,maximum polarization resistance of 1555.3 Ω and a very low current density of 9.33 × 10-6A/*** negative shift in the Ecorr revealed the cathodic protective nature of the *** microhardness was also found to have increased from 137.9 HBN for the unmodified steel to a maximum value of 263.3 HBN for the0.5 Zn-13 si3 N4 coated steel representing 90.9% increment in hardness as a result of the matrix grain refining and dispersion-strengthening ability of the incorporated si3 N4 particles.

关键词： Polarization Corrosion Microhardness Coating Composite Matrix

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Blood biomarkers of Alzheimer’s disease:important considerations for use in clinical practice

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Neural Regeneration Research 2025年第1期20卷 205-206页

作者： sarah Fullam sean o’Dowd Antoinette o’Connor Department of Neurology Tallaght University HospitalDublinIreland Academic Unit of Neurology Trinity College DublinIreland

introduction:Fluid and positron emission tomography(PET)biomarkers that enable the detection of the hallmark proteins of Alzheimer’s disease(AD)(amyloid and tau)have revolutionized our approach to the diagnosis of *** evolution of AD diagnostic criteria to include biological characterization(Alzheimer’s Association Working Group,2023)provides an appropriate framework to reduce levels of clinico-pathologic mismatch and improve in-vivo diagnostic *** the therapeutic landscape for neurodegenerative disease evolves,it is increasingly incumbent on clinicians to provide timely,and pathologically precise diagnoses for ***,the expensive and invasive nature of these tests limits their scalability.

关键词： Blood Alzheimer diagnosis

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Anticorrosion properties and thin film composite deposition of ZnsiC-Cr_3C_2 coating on mild steel

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Defence Technology（防务技术） 2019年第1期15卷 106-110页

作者： A.A.Ayoola o.s.i.fayomi A.P.i.Popoola Chemical Engineering Department Covenant University Chemical Metallurgical and Materials Engineering DepartmentTshwane University of Technology Mechanical Engineering Department Covenant University

This work considered the influence of Cr3 C2 particle loading on microstructure and mechanical properties of Zn-siC-Cr3 C2 nanocomposite produced via electrocodeposition are investigated. The surface nature of the nanocomposite coatings were characterized using scanning electron microscope(sEM)coupled with the energy dispersive spectrometer(EDs). Abrasive wear behaviour and hardness property of Zn-siC-Cr3 C2 nanocomposite produced were investigated using CERT UMT-2 multi-functional tribological tester and Dura scan hardness tester. The corrosion property was evaluated through linear polarization approach. The result showed that the coatings exhibited good stability and Cr_3 C_2 nanocomposite loading significantly improved the micro structural performance, hardness property,wear resistance as well as corrosion resistance of the coatings.

关键词： Zn-siC-Cr3C2 Electrodeposition Coatings Corrosion resistance Hardness

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The inhibitive study of egg shell powder on uns n08904 austenitic stainless steel corrosion in chloride solution

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Defence Technology（防务技术） 2018年第5期14卷 463-468页

作者： o.sanni A.P.i.Popoola o.s.i.fayomi Tshwane University of Technology Department of Chemical Metallurgical and Materials Engineering

The effect of egg shell powder(Es) as an environmental friendly inhibitor was studied for its corrosion inhibitive tendency on N08904 austenitic stainless steel in simulated saline(3.5% NaCl) solution using potentiodynamic polarization, weight loss, and sEM/EDX at room temperature. The experimental data explained the effective performance of Es with values of 57%-100% inhibition efficiency, at 2 g-10 g inhibitor concentration from weight loss tests due to the inhibition of stainless steel. The electrochemical action was as a result of the ionized particles which inhibit the compound influencing the redox reaction mechanism causing surface corrosion. Es's best performance was achieved when 6 g of the inhibitor concentration was added to the saline medium. Corrosion rate value decreased progressively with the presence of inhibitor because of anions adsorption at the interface of the metal film. Corrosion potential(Ecorr) value was found to decrease from-0.3991 V to-0.3447 V in the presence of inhibitor at 2 g concentration, decreasing gradually to-0.2048 at 6 g inhibitor concentration. The compounds identified in the Es completely adsorbed onto the surface of stainless steel as observed from the EDX analysis. The Es adsorption on stainless steel surface obeyed Langmuir adsorption isotherm. A corroded morphology with pits was observed in the sEM results without Es which contrast the images obtained with the presence of Es.

关键词： Austenitic stainless steel Corrosion inhibition Egg shell Chloride Langmuir

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Characterization of ceramic reinforced titanium matrix composites fabricated by spark plasma sintering for anti-ballistic applications

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Defence Technology（防务技术） 2018年第5期14卷 408-411页

作者： s.W.Maseko A.P.i.Popoola o.s.i.fayomi Department of Chemical Metallurgicaland Materials EngineeringTshwane University of TechnologyPretoriaSouth Africa Department of Mechanical Engineering Covenant UniversityOtaNigeria

Titanium has found extensive use in various engineering applications due to its attractive physical,mechanical, and chemical characteristics. However, titanium has relatively low hardness for use as an armour material. ZrB2 was incorporated to the Ti matrix to form a Ti-based binary composites. in this study, powder metallurgy techniques were employed to disperse the ceramic particulates throughout the matrix material then consolidated through spark plasma sintering. The composites were densified at1300 ℃, pressure of 50 MPa, and holding time of 5 min. The microstructure and phase analysis of the sintered composites was carried out using sEM and XRD, while the hardness was determined using Vickers' microhardness tester. The sEM and XRD results confirmed the presence of the TiB whiskers which renowned with the improving the hardness of titanium. The hardness of the composite with 10 wt% ZrB_2 showed the highest hardness compared to that obtained for the 5 and 15 wt% ZrB_2 composites which was 495 and 571 Hv respectively.

关键词： sPs TiB whiskers Hardness Titanium matrix composites Reinforcement

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Electrolytic deposition of super-smart composite coating of Zn-V2o5-Nbo2 on low carbon steel for defence application

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Defence Technology（防务技术） 2018年第5期14卷 446-450页

作者： o.s.i.fayomi L.R.Kanyane A.P.i.Popoola s.o.oyedepo Department of Chemical Metallurgical and Materials EngineeringTshwane University of TechnologyP.M.B.X680PretoriaSouth Africa Department of Mechanical Engineering Covenant UniversityP.M.B 1023OtaNigeria

Despite the massive usages of low carbon steel in automobile for engineering components, its corrosion and high friction coefficient in aggressive environment make it limited in service. This paper is aimed at modifying low carbon steel structural component with thin film composite for enhanced mechanical and corrosion properties. The steel structure was electrodeposited with Zn-V_2 o_5 and embedded with varied Nbo_2 weight concentration of 6-12 wt % based electrolyte. scanning electron microscope(sEM) and high optical microscope was used to study the microstructural evolution of the fabricated coatings. The thermal stability of the fabricated coatings was studied in an isothermal furnace at 300 ℃ and 600 ℃ and further characterized using a high tech optical microscope. Potentiodynamic polarization technique was used to investigate the corrosion behavior of the composites in 3.65% NaCl. From the result, the effect of Nbo_2 on Zn-V_2 o_5-Nbo_2 was massive with improved crystal grain within the coatings lattices. The coating possesses strong metallurgical bonding and good corrosion resistance properties of about 0.315 mm/yr corrosion rate compare to 4.1 mm/yr of as-received sample. No doubt the impact of thermal shock on the resilient characteristics of the composite coating was moderate owing to the stable adherent properties of the deposited coatings.

关键词： Electrodeposition Low carbon steel Micro-hardness Thermal stability corrosion behavior Rare earth metal(REM)

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influence of spark plasma sintering on microstructure and corrosion behaviour of Ti-6Al-4V alloy reinforced with micron-sized si_3N_4powder

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Defence Technology（防务技术） 2018年第5期14卷 403-407页

作者： F.M.Kgoete A.P.i.Popoola o.s.i.fayomi Department of Chemical Metallurgical & Materials Engineering Tshwane University of Technology Department of Mechanical Engineering Covenant University

Ti-6 Al-4 V-si3 N4 composites were effectively fabricated by spark plasma sintering(sPs) technique. The addition of si_3 N_4 on Ti-6 Ai-4 V was varied from 5% to 15%(wt fraction). The effect of si_3 N_4 addition on the densification, microstructure, and microhardness and corrosion behaviour of Ti-6 Al-4 V was *** increase in microhardness value was recorded from 325.46 HV_(0.1) to 585.73 HV_(0.1). X-ray diffraction(XRD) analysis showed that the intensity of diffraction peaks of si3 N4 phase in the composites *** sintered Ti-6 Al-4 V reinforced with si_3 N_4 compacts revealed the non-existence of intermediate phases, such as Tisi_2(titanium silicide) which was expected. sEM analysis of the spark plasma sintered composites revealed a and β phase microstructures in Ti-6 Al-4 V with uniform distribution of si3 N4 particulates in the matrix. The corrosion resistance property of the material was improved by the addition of si_3 N_4 from 0.986629 mm/year to 0.030547 mm/year.

关键词： spark plasma sintering si3N4 Ti-6Al-4V Microstructure Corrosion

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structural evolution, optoelectrical and corrosion properties of electrodeposited Wo_3 integration on Zn-Tio_2 electrolyte for defence super application

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Defence Technology（防务技术） 2018年第5期14卷 396-402页

作者： A.A.Daniyan L.E.Umoru o.s.i.fayomi A.P.i.Popoola Department of Materials science and Engineering Obafemi Awolowo University Department of Chemical Metallurgical and Materials Engineering Tshwane University of Technology Department of Mechanical Engineering Covenant University

Multifunctional nano composite coatings of Zn-Tio_2-Wo_3 were deposited electrolytically on mild steel(Ms) from Zn bath, having Zn^(2+) ions and uniform dispersion of Tio_2 and Wo_3 nano particulates. The electrical, optical and corrosion resistance characteristics of the electrocodeposited coatings were assessed by Keithley 2400 series source meter with Multimeters, Newport solar simulator and a PGsTAT30 Autolab potentiostat respectively. The morphological characteristics of the composite coatings were characterized by scanning electron microscope(sEM) equipped with energy dispersive spectrometer(EDs). The result revealed that the electrocodeposits showed good stability and Zn-Tio_2-Wo_3 nanocomposite deposits displayed enhanced microstructural qualities, good electrical conductivity and exhibited enriched corrosion resistance.

关键词： Nano-composite Electrocodeposition Corrosion Conductivity and resistance

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Revisiting cerebral endothelial cells in Alzheimer’s disease

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Neural Regeneration Research 2025年第10期20卷 2911-2912页

作者： Amira s.Hanafy Department of Neurosurgery University Hospital BonnBonnGermany

Alzheimer’s disease(AD)is the most common neurodegenerative disorder characterized by slow and progressive decline of cognitive and memory *** only approximately 5%of the cases,AD is familial,as often predisposed by genetic mutations(Hoogmartens et al.,2021),while sporadic AD accounts for approximately 95%of the *** amyloid cascade hypothesis is one of the fundamental hypotheses put out to explain AD pathogenesis as dysregulated homeostasis of amyloid-β(Aβ)peptides that leads to the accumulation of Aβplaques in the parenchyma,an anatomical hallmark of AD.

关键词： Alzheimer Aβ cerebral

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Emerging structures and dynamic mechanisms ofγ-secretase for Alzheimer’s disease

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Neural Regeneration Research 2025年第1期20卷 174-180页

作者： Yinglong Miao Michael s.Wolfe Computational Medicine Program and Department of Pharmacology University of North Carolina–Chapel HillChapel HillNCUSA Department of Medicinal Chemistry University of KansasLawrenceKSUSA

γ-secretase,called“the proteasome of the membrane,”is a membrane-embedded protease complex that cleaves 150+peptide substrates with central roles in biology and medicine,including amyloid precursor protein and the Notch family of cell-surface *** inγ-secretase and amyloid precursor protein lead to early-onset familial Alzheimer’s disease.γ-secretase has thus served as a critical drug target for treating familial Alzheimer’s disease and the more common late-onset Alzheimer’s disease as ***,critical gaps remain in understanding the mechanisms of processive proteolysis of substrates,the effects of familial Alzheimer’s disease mutations,and allosteric modulation of substrate cleavage byγ-*** this review,we focus on recent studies of structural dynamic mechanisms ofγ-*** mechanisms,including the“Fit-stay-Trim,”“sliding-Unwinding,”and“Tilting-Unwinding,”have been proposed for substrate proteolysis of amyloid precursor protein byγ-secretase based on all-atom molecular dynamics *** an incorrect registry of the Notch1 substrate was identified in the cryo-electron microscopy structure of Notch1-boundγ-secretase,molecular dynamics simulations on a resolved model of Notch1-boundγ-secretase that was reconstructed using the amyloid precursor protein-boundγ-secretase as a template successfully capturedγ-secretase activation for proper cleavages of both wildtype and mutant Notch,being consistent with biochemical experimental *** approach could be potentially applied to decipher the processing mechanisms of various substrates byγ-*** addition,controversy over the effects of familial Alzheimer’s disease mutations,particularly the issue of whether they stabilize or destabilizeγ-secretase-substrate complexes,is ***,an outlook is provided for future studies ofγ-secretase,including pathways of substrate binding and product release,effects of modulators on familial Alzheimer’s disease mutations

关键词： Alzheimer’s disease amyloid precursor protein cryo-EM structures drug design intramembrane proteolysis molecular dynamics Notch

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