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Antimicrobial activity of metal-substituted cobalt ferrite nanoparticles synthesized by sol-gel technique

Particuology 2018年第5期16卷 141-151页

作者： a.h.ashour Ahmed I.E1-Batal M.I.A.Abdel Maksoud Gharieb S.El-Sayyad Sh.Labib E.Abdeltwab M.M.El-Okr Materials Science Laboratory Radiation Physics Department.National Center for Radiation Research and TechnologyAtomic Energy AuthorityCairoEgypt Drug Microbiology Laboratory Drug Radiation Research DepartmentNational Center for Radiation Research and TechnologyAtomic Energy Authority CairoEgypt Nuclear Chemistry Department Hot Laboratories CenterAtomic Energy AuthorityCairoEgypt Physics Department Faculty of Science (Girls Branch)Al-Azhar UniversityCairo.Egypt Physics Department.Faculty of Science (Boys Branch) Al-Azhar UniversityCairoEgypt

Metal-substituted cobalt ferrites [MxCo(1-x)Fe2O4(M=Zn,Cu,Mn;x=0.0,0.25,0.5,and 0.75)]were synthesized via a sol-gel *** ferrite structures were confirmed by X-ray diffraction, Fourier transform infrared spectroscopy,scanning electron microscopy,surface analysis using the Brunauer-Emmett-Teller method,and energy-dispersive X-ray *** activity of these ferrites against selected pathogenic microbes was *** structures remained cubic spinel phases after substitution of *** strongly influenced the microstructure and homoge- neous grain *** particle size of the ferrites increased linearly with increase in their annealing *** surface area of zinc cobalt ferrite nanoparticles (ZCFO)was 52.56m^2/g,the average pore size was 1.84nm,and pore volume was 0.136mL/*** ferrites showed antimicrobial activity toward all pathogens *** these,the most powerful was ZCFO,showing zones of inhibition of 13.0mm against Bacillus subtilis and Staphylococcus aureus and 12.0mm against Candida ***-irradiated ZCFO nanoparticles (150.0kGy)maintained higher antimicrobial activity than non-irradiated particles,e.g. being active toward *** (16.0mm).ZCFO is proposed as a candidate material for industrial and biomedical purposes.

关键词： Antibacterial Antifungal Zone of inhibition Zinc cobalt ferrite nanoparticles Gamma irradiation

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La^3+ doped LiCo0.25Zn0.25Fe2O4 spinel ferrite nanocrystals:Insights on structural,optical and magnetic properties

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Journal of Rare Earths 2021年第1期39卷 75-82,I0003页

作者： M.I.A.Abdel Maksoud Ahmed El-Ghandour a.h.ashour M.M.Atta Soraya Abdelhaleem Ahmed h.El-hanbaly Ramy Amer Fahim Said M.Kassem M.S.Shalaby A.S.Awed Materials Science Lab. Radiation Physics DepartmentNational Center for Radiation Research and Technology(NCRRT)Atomic Energy AuthorityCairoEgypt Center Photonics and Smart Materials(CPSM) Zewail City of Science and TechnologyOctober Gardens6th of October CityGizaEgypt Polymers Physics Lab. Radiation Physics DepartmentNational Center for Radiation Research and Technology(NCRRT)Atomic Energy AuthorityCairoEgypt Egyptian Nuclear and Radiological Regulatory Authority CairoEgypt Radiation Protection and Dosimetry Department National Center for Radiation Research and Technology(NCRRT)Atomic Energy AuthorityCairoEgypt Magnetic and Thermal Lab Solid State&Accelerators DepartmentNational Center for Radiation Research and TechnologyAtomic Energy AuthorityNasr CityCairoEgypt higher Institute for Engineering and Technology ManzalaDakahliaEgypt

This paper addresses the manipulation of structural,morphology,optical and magnetic properties of LiCo0.25Zn0.25Fe2 O4 ferrite via incorporation of different proportions of La^3+at the expense of iron ions using a sol-gel *** samples were characterized using the X-ray diffraction technique(XRD),Fourier transform infrared(FT-IR)spectroscopy,the energy dispersive X-ray spectra(EDX),inductively coupled plasma optical emission spectroscopy(ICP-OES),high resolution scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET)surface area analysis,ultraviolet-diffuse reflectance spectroscopy(UV-DRS),and vibrating sample magnetometer(VSM)*** Rietveld refinements of the samples indicate that at higher concentrations of La^3+,nanostructures with dual phase,*** spinel and orthorhombic LaFeO3 perovskite with space group(Pbnm)*** studies show that the energy band gap(Eg)of the bare LiCo0.25Zn0.25Fe2 O4 ferrite sample(2.18 eV)reaches up to 2.47 eV at x=0.06 and above this concentration,it drops sharply to 2.00 *** the saturation magnetization and the coercivity of LiCo0.25Zn0.25LaxFe2-xO4 are lower than that of LiCo0.25Zn0.25Fe2 O4 ***,the superparamagnetic nature and low values of saturation magnetization and coercivity of LiCo0.25Zn0.25LaxFe2-xO4 NPs are suitable to be applied in transformers core.

关键词： Li-Co-Zn ferrite Superparamagnetic nature Optical properties Magnetic behavior Transformers core Rare earths

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Modifying effects and mechanisms of superfine stainless wires on microstructures and mechanical properties of ultra-high performance seawater sea-sand concrete

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Science China Technological Sciences 2024年第10期67卷 3205-3220页

作者： YU Feng DONG SuFen ashour Ashraf DING SiQi hAN BaoGuo School of Infrastructure Engineering Dalian University of Technology Faculty of Engineering & Informatics University of Bradford Department of Civil and Environmental Engineering The Hong Kong Polytechnic University

Ultra-high-performance seawater sea-sand concrete（UhPSSC） presents a prospective solution to address the natural resource shortage in marine infrastructure construction. To eliminate the corrosion risk of steel fibers and broaden the applicability of UhPSSC, this study investigates the mechanical properties and free chloride ion content as well as microstructures of UhPSSC reinforced with superfine stainless wires（SSWs） under natural curing. The results indicate that 1.5% SSWs can remarkably improve the flexural strength and toughness of UhPSSC by 127% and 1724%, respectively, and mitigate the long-term strength degradation of UhPSSC. The strong interfacial bond between SSW and UhPSSC improves the compactness of UhPSSC, thus reducing the growth space for Ca（Oh）2crystals and swelling hydration products generated by sulfate and magnesium ions. This can be supported by the observed reduction in the Ca/Si ratio of C–S–h gels, Ch crystal orientation index, and ***, through mechanisms such as pull-out, rupture, overlapping network, and internal anchor interface, SSWs effectively prevent microcrack growth and propagation, transforming single long-connected microcracks into multiple-emission microcracks centered on SSW. Additionally, the free chloride ion content of the composites at 28 and 180 d meets the ACI 318-19 standard requirements for concrete exposed to seawater. This compliance is attributed to the chloride immobilization facilitated by Friedel's salt and C–S–h gels within the interfaces around SSWs and sea-sand. Consequently, SSWs-reinforced UhPSSC exhibits considerable potential for applications in sustainable marine infrastructures, demanding long-term mechanical properties and high durability.

关键词： ultra-high performance seawater sea-sand concrete superfine stainless wire mechanical properties chloride ion content microstructure

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黏贴FRP剪力键的FRP-UhPC组合梁受剪性能研究

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中国公路学报 2024年

作者：葛文杰张志文 Ashraf ashour 曹大富李胜才扬州大学建筑科学与工程学院 University of Bradford Faculty of Engineering & Informatics

为了研究纤维增强复合材料（Fiber reinforced polymer， FRP）-超高性能混凝土（Ultra high performance concrete， UhPC）组合梁的受剪性能，对FRP-UhPC组合梁进行四点受弯试验。组合界面采用FRP剪力键（FRP shear key， FSK）与环... 详细信息

为了研究纤维增强复合材料（Fiber reinforced polymer， FRP）-超高性能混凝土（Ultra high performance concrete， UhPC）组合梁的受剪性能，对FRP-UhPC组合梁进行四点受弯试验。组合界面采用FRP剪力键（FRP shear key， FSK）与环氧树脂胶结混合处理的方式降低界面滑移的影响。对组合梁的破坏模式、荷载-位移响应、应变响应和滑移响应进行分析，研究了混凝土类型、FSK间距、混凝土板宽度和高度对组合梁受剪性能的影响。结果表明，FRP-UhPC组合梁的破坏模式是剪切破坏，FRP-NSC组合梁的破坏模式是弯、剪协同破坏。组合梁存在剪力滞后效应，随着混凝土板宽度的增大，剪力滞后效应越明显。混凝土采用UhPC、减小FSK间距和提高混凝土板截面尺寸都可以有效提高组合梁的抗剪性能，并减小界面滑移。基于合理假定，提出了FRP-UhPC组合梁的抗剪承载力和考虑剪切变形的挠度计算方法，预测结果与试验结果吻合较好。

关键词：桥梁工程 FRP-UhPC组合梁弯曲试验受剪性能 FRP剪力键

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低周反复荷载作用下SFCBs-RPC框架力学性能分析

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建筑科学 2024年第5期40卷 56-66,77页

作者：罗来勇姚子豪姚山葛文杰 Ashraf ashour 江苏扬建集团有限公司江苏扬州225002 扬州大学建筑科学与工程学院江苏扬州225127 甘肃省工程设计研究院有限责任公司甘肃兰州730030

为研究低周反复荷载作用下钢-FRP复合筋(steel-FRP composite bar,SFCB)活性粉末混凝土(reactive powder concrete,RPC)框架力学性能,基于有限元软件ABAQUS对一榀钢筋混凝土框架在低周反复荷载作用下的力学性能进行分析,模拟结果与试验... 详细信息

为研究低周反复荷载作用下钢-FRP复合筋(steel-FRP composite bar,SFCB)活性粉末混凝土(reactive powder concrete,RPC)框架力学性能,基于有限元软件ABAQUS对一榀钢筋混凝土框架在低周反复荷载作用下的力学性能进行分析,模拟结果与试验吻合性良好。在此基础上,建立SFCBs-RPC框架模型,分析混凝土强度、轴压比及柱纵筋配筋率对SFCBsRPC框架抗震性能的影响。结果表明,SFCB-RPC框架相比钢筋RPC框架具有良好的二次刚度,屈服后承载力提升明显且残余变形率更小,具有良好的变形恢复能力和延性;RPC框架相比普通混凝土框架拥有更高的承载力和延性;框架延性随轴压比和柱纵筋配筋率的增大而降低;SFCBs-RPC框架总体呈现良好延性。

关键词：钢-FRP复合筋活性粉末混凝土混凝土框架抗震性能参数分析

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钢-FRP复合筋增强超高性能混凝土框架梁受弯性能试验研究

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工程力学 2024年

作者：葛文杰张志文 Ashraf ashour 姚山罗来勇曹大富李胜才布拉德福德大学工程与信息学院甘肃省工程设计研究院有限责任公司扬州大学工程结构与防灾减灾研究所江苏扬建集团有限公司扬州大学建筑科学与工程学院

为研究钢-FRP复合筋（steel-FRP composite bar，SFCB）增强超高性能混凝土（ultra-high performance concrete，UhPC）框架梁的受弯性能，对5榀框架梁进行了等效静力试验。对框架梁破坏模式、裂缝、承载力、变形、应变响应和塑性转动... 详细信息

为研究钢-FRP复合筋（steel-FRP composite bar，SFCB）增强超高性能混凝土（ultra-high performance concrete，UhPC）框架梁的受弯性能，对5榀框架梁进行了等效静力试验。对框架梁破坏模式、裂缝、承载力、变形、应变响应和塑性转动能力进行分析，研究了混凝土类型、筋材类型和梁端配筋率对框架梁受弯性能的影响。建立了框架梁三维有限元模型，并基于已验证的模型对SFCB的截面含钢率、内芯钢筋屈服强度、外包FRP弹性模量和极限抗拉强度进行了参数分析。结果表明，框架梁的破坏模式均为梁端混凝土压碎；采用UhPC替代普通混凝土能够显著增强框架梁的抗弯承载力、延性、极限耗能和塑形转动能力，抑制裂缝的产生和扩展；SFCB-UhPC框架梁的塑性转角为钢筋-UhPC框架梁的4.9倍，采用SFCB替代钢筋可以有效提升框架梁的梁端塑形转动能力；梁端配筋率的减小显著降低了梁端抗弯承载力、极限耗能和塑性转动能力，但提高了延性；建立了以梁端控制截面相对受压区高度和截面有效高度为自变量的等效塑性铰长度计算公式，预测值与实测值吻合良好。

关键词： UhPC框架梁钢-FRP复合筋受弯性能等效静力试验有限元法参数分析

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氯盐侵蚀作用后钢-FRP复合筋混凝土柱偏心受压性能试验研究

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建筑结构 2024年

作者：帅华国朱世鑫葛文杰倪增昊 AShRAF ashour 扬州大学工程设计研究院有限公司扬州大学建筑科学与工程学院布拉德福德大学工程与信息学院

为研究氯盐侵蚀作用后钢-FRP复合筋（SFCB）混凝土柱偏心受压性能，对经氯盐侵蚀后的SFCB及SFCB混凝土偏心受压柱进行力学性能试验。研究了配筋类型、配筋率、偏心距、长细比、应力水平与侵蚀时间对承载力、侧向变形、裂缝和破坏形态的... 详细信息

为研究氯盐侵蚀作用后钢-FRP复合筋（SFCB）混凝土柱偏心受压性能，对经氯盐侵蚀后的SFCB及SFCB混凝土偏心受压柱进行力学性能试验。研究了配筋类型、配筋率、偏心距、长细比、应力水平与侵蚀时间对承载力、侧向变形、裂缝和破坏形态的影响。结果表明：筋材强度保留率随侵蚀时间增加而降低，无应力侵蚀180d后，钢筋、SFCB和FRP筋极限强度分别降低了12.2%、9.9%和3.6%；随筋材截面含钢率的增加，SFCB混凝土偏心受压柱承载力逐渐提高，侧向变形逐渐减小；侵蚀后钢筋组、SFCB组和FRP筋组试件极限承载力分别较其侵蚀试件最大下降16.6%、12.4%和7.2%。SFCB混凝土柱具有良好的抵抗侧向变形和裂缝的能力。

关键词：混凝土柱钢-FRP复合筋偏心受压氯盐侵蚀试验研究

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Free vibration and buckling analysis of polymeric composite beams reinforced by functionally graded bamboo fbers

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Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 543-562页

作者： h.M.FEIZABAD M.h.YAS Department of Mechanical Engineering Razi UniversityKermanshah ***Iran

Natural fibers have been extensively researched as reinforcement materials in polymers on account of their environmental and economic advantages in comparison with synthetic fibers in the recent *** fibers are renowned for their good mechanical properties,abundance,and short cycle *** beams are one of the fundamental structural components and are susceptible to mechanical loads in engineering applications,this paper performs a study on the free vibration and buckling responses of bamboo fiber reinforced composite(BFRC)beams on the elastic *** different functionally graded(FG)layouts and a uniform one are the considered distributions for unidirectional long bamboo fibers across the *** elastic properties of the composite are determined with the law of *** hamilton’s principle,the governing equations of motion are *** generalized differential quadrature method(GDQM)is then applied to the equations to obtain the *** achieved outcomes exhibit that the natural frequency and buckling load values vary as the fiber volume fractions and distributions,elastic foundation stiffness values,and boundary conditions(BCs)and slenderness ratio of the beam ***,a comparative study is conducted between the derived analysis outcomes for BFRC and homogenous polymer beams to examine the effectiveness of bamboo fibers as reinforcement materials,demonstrating the significant enhancements in both vibration and buckling responses,with the exception of natural frequencies for cantilever beams on the Pasternak foundation with the FG-◇fiber ***,the obtained analysis results of BFRC beams are also compared with those for carbon nanotube reinforced composite(CNTRC)beams found in the literature,indicating that the buckling loads and natural frequencies of BFRC beams are lower than those of CNTRC beams.

关键词： bamboo fiber free vibration buckling analysis functionally graded(FG)beam elastic foundation generalized differential quadrature method(GDQM)

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holographic dark energy in non-conserved gravity theory

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Communications in Theoretical Physics 2024年第4期76卷 126-133页

作者： h R Fazlollahi Institute of Gravitation and Cosmology Peoples Friendship University of Russia(RUDN University)6 Miklukho-Maklaya StMoscow117198Russia

Recently, reconsidering the Rastall idea T_(μ;νν)^(v)=α_(,μ) through relativistic thermodynamics gives a new form for the scalar field α which led us to construct modern modified theory of gravity debugged ‘non-conserved gravity theory’ Fazlollahi 2023 Euro. Phys. J. C 83 923. This theory unlike other modified theories of gravity cannot directly explain the current acceleration expansion in the absence of the cosmological constant and or existence of other forms of dark energy. hence, in this study we have reinvestigated holographic dark energy Ρ_(X)~h^(2) in the non-conserved theory of gravity. In this context, the density and pressure of dark energy depend on the non-conserved term and density of the dust matter field. As shown, due to non-conservation effects on large-scale structures, unlike the original holographic model, our model onsets an acceleration epoch for the current Universe satisfies observations. Moreover, the interaction and viscous scenarios are studied for this model.

关键词： non-conserved gravity covariant form of thermodynamics holographic dark energy

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Novel synthesis of stabilized Bi1-x-yGdxDyyO1.5 solid electrolytes with enhanced conductivity for intermediate temperature solid oxide fuel cells（SOFCs）

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Journal of Rare Earths 2024年第10期42卷 1903-1911页

作者： Ahmed h.Ibrahim Yehia M.Abbas h.A.Ayoub Marwa h.Ali Mustafa Aldoori Materials Science Laboratory Physics DepartmentFaculty of ScienceSuez Canal University Ministry of higher Education and Scientific Research Aliraqia University

herein,we report the synthesis of a Dy-Gd co-doped cubic phase-stabilized Bi2O3solid electrolyte system via solid-state processing under atmospheric *** with Dy3+and Gd3+has been observed to significantly enhance the densification process during sintering for stabilization purposes,thereby improving the electrical properties of δ-Bi2O3-type *** synthesized ceramics were characterized using X-ray diffraction（XRD）,field emission scanning electron microscopy-energy dispersive X-ray spectroscopy（FESEM-EDX）,thermal gravimetry/differential thermal analysis（TG/DTA）,and the four-point probe technique（4PPT）.XRD analysis reveals that the samples Bi1-x-yGdxDyyO1.5（y=0.05/x=0.05,0.10,0,15,and 0.20,and x=0.05/y=0.10,0.15,and 0.20） exhibit a stable face-centered cubic δ-phase and a mixed-phase crystallographic *** XRD analysis of the stabilized δ-phase suggests that the prepared oxides show a face-centered cubic（FCC） structure with a space group of *** micrographs reveal that the composition Bi0.90Gd0.05Dy0.05O1.5has no significant ***,an evident increase in the pore formation is observed as the amount of Gd2O3increases until it reaches 20%.This finding suggests that dense pellets are formed during the sintering process at 900-1000℃.The DTA analyses were performed to verify the phase stability,which agrees with the XRD *** electrochemical performance of the synthesized Dy-Gd co-doped Bi2O3solid electrolyte system was evaluated and analyzed in detail by using the electrochemical impedance spectroscopy（EIS） technique,Based on EIS and conductivity measurements,Bi0.75Gd0.20Dy0.05O1.5exhibits the lowest activation energy of 0.519 eV and the highest conductivity value of 0.398 S/cm at 627℃compared to the other samples;this composition can be used as a solid electrolyte for intermediatetemperature solid oxide fuel cells（SOFCs）.

关键词： Electrochemical impedance spectroscopy (EIS) Fast Fourier transform (FFT) Rare earths Rietveld Solid oxide fuel cells (SOFCs) Solid-state processing

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