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development and screening of(Ca-P-Si-F)-PEO coatings for biodegradability control of Mg-Zn-Ca alloys

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Journal of Magnesium and Alloys 2022年第8期10卷 2220-2237页

作者： Lara Moreno Marta Mohedano Raul Arrabal Endzhe Matykina Departamento de Ingeniería Química y de Materiales Facultad de Ciencias QuímicasUniversidad Complutense de Madrid28040 MadridSpain

PEO coatings were developed on MgZnxCayalloys for biomedical applications using different treatment times and a novel transparent electrolyte containing Ca,P,Si and F.Surface characteristics and chemical composition of studied materials were evaluated using scanning electron microscopy,X-ray diffraction and optical metrology.Corrosion investigations were performed for uncoated and coated materials using potentiodynamic polarization,electrochemical impedance spectroscopy and hydrogen evolution measurements in three media(0.9wt.%NaCl,α-MEM and inorganic part ofα-MEM).Findings revealed that Zn-rich intermetallics favour the formation of large voids in the coatings.Ca,P,F and Si are successfully incorporated into the coatings.Coatings consist of crystalline phases(Mg O,Mg F_(2)and Ca,Si-rich compounds)and amorphous material.Aminoacids and organic components ofα-MEM solution accelerate corrosion of the bare substrates but have no significant influence on the corrosion resistance of coated specimens.Therefore,inorganicα-MEM can be considered as an appropriate medium for fast screening of PEO coatings.The relatively small amount of F content in the barrier layer facilitates early failure of the coatings,which show undercoating corrosion.Zn-rich intermetallic particles in the undercoating crevice induce a more aggressive corrosive environment and enhanced micro-galvanic couple effect with the Mg matrix.This leads to faster degradation of the coated alloys compared to the bare substrates.

关键词： Magnesium Biomaterials Plasma electrolytic oxidation Corrosion

Photoelectrochemical CO_(2) electrolyzers: From photoelectrode fabrication to reactor configuration

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Journal of Energy Chemistry 2023年第10期85卷 455-480,I0012页

作者： Jose Antonio Abarca Guillermo Díaz-Sainz Ivan Merino-Garcia Angel Irabien Jonathan Albo Departamento de Ingenierías Química y Biomolecular Universidad de CantabriaETSIITAvenida de los Castros s/n39005 SantanderSpain

The photoelectrochemical conversion of CO_(2) into value-added products emerges as an attractive approach to alleviate climate change. One of the main challenges in deploying this technology is, however, the development and optimization of(photo)electrodes and photoelectrolyzers. This review focuses on the fabrication processes, structure, and characterization of(photo)electrodes, covering a wide range of fabrication techniques, from rudimentary to automated fabrication processes. The work also highlights the most relevant features of(photo)electrodes, with special emphasis on how to measure and optimize them. Finally, the review analyses the integration of(photo)electrodes in different photoelectrolyzer architectures, analyzing the most recent research work that comprises photocathode, photoanode,photocathode-photoanode, and tandem photoelectrolyzer configurations to ideally achieve self-sustained CO_(2) conversion systems. Overall, comprehensive guidelines are provided for future advancements in developing effective devices for CO_(2) conversion, bridging the gap towards the use of sunlight as the unique energy input and practical applications.

关键词： decarbonization CO_(2)photoelectroreduction (Photo)Electrodes Fabrication techniques Photoelectrolyzer configuration

Environmental degradation through mining for energy resources:The case of the shrinking Laguna Santa Rosa wetland in the Atacama Region of Chile

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Energy Geoscience

Energy Geoscience 2022年第2期3卷 182-190页

作者： Mohammad Ayaz Alam Rosa Sepúlveda departamento de Geología Facultad de IngenieríaUniversidad de AtacamaAvenida Copayapu 485CopiapoRegion de AtacamaChile

As the world strives to replace fossil fuels with clean energy e reflected by global surge in the number of electric vehicles e the environmental impact of mining all the lithium(Li)needed to enable such a transformation has become a problem in its own right.In South America,the biggest problem is the excessive use of water in Li extraction process in one of the driest areas in the world.Apart from causing severe friction over water rights between local communities and mining companies,it puts enormous pressure on the region's fragile and poorly understood wetland ecosystems.Wetlands are one of the most threatened ecosystems on the Earth,despite their great importance as habitats for a vast number of species and corresponding to one of the most productive environments.Present work is the outcome of an investigation on Laguna Santa Rosa's(LSR)vulnerability resulting from ongoing metal mining operations in its surroundings that require a large volume of water extracted from local aquifers,in addition to a high evaporation rate in the area.This groundwater-dependent wetland will soon be further vulnerable with the commencement of water-intensive Li mining at Salar de Maricunga,with the extraction project already having an environmental impact study approved.Sustainability of this wetland protected under the Ramsar Convention and home to numerous wildlife species habiting this highland sector of the Andean Cordillera is vital for the associated ecosystems.The variation in the water surface area of LSR has been deciphered through the application of a Landsat-5 Thematic Mapper(TM)satellite image collection.This has been done both for the hydrological year 2016e2017 and 1993-2014 period.A decreasing trend in the water surface area of LSR,a hypersaline lake at the southern extreme of Salar de Maricunga,a salt flat in the Atacama Region of Chile,was observed through the study of satellite images between 1993 and 2014,showing shrinking of this wetland.However,this shrinking trend was punctuated by extreme rainfall and cons

关键词： Laguna Santa Rosa Salar de Maricunga Lithium Water Wetland Ecosystem

Nonlinear elastic constitutive relations of residually stressed composites with stiff curved fibres

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Applied Mathematics and Mechanics(English Edition) 2022年第10期43卷 1515-1530页

作者： M.H.B.M.Shariff J.Merodio R.Bustamante department of Mathematics Khalifa University of Science and TechnologyAbu Dhabi127788United Arab Emirates departamento de Matemática Aplicada a las TIC ETS de Ingeniería de Sistemas InformaticosUniversidad Politecnica de MadridMadrid28031Spain Departamento de Ingeniería Mecánica Universidad de ChileBeauchef 851Santiago CentroSantiago8370448Chile

Mechanical models of residually stressed fibre-reinforced solids,which do not resist bending,have been developed in the literature.However,in some residually stressed fibre-reinforced elastic solids,resistance to fibre bending is significant,and the mechanical behavior of such solids should be investigated.Hence,in this paper,we model the mechanical aspect of residually stressed elastic solids with bending stiffness due to fibre curvature,which up to the authors’knowledge has not been mechanically modeled in the past.The proposed constitutive equation involves a nonsymmetric stress and a couple-stress tensor.Spectral invariants are used in the constitutive equation,where each spectral invariant has an intelligible physical meaning,and hence they are useful in experiment and analysis.A prototype strain energy function is proposed.Moreover,we use this prototype to give results for some cylindrical boundary value problems.

关键词： fibre-reinforced solid residual stress bending stiffness spectral invariant second gradient finite elasticity

Gas-phase electrocatalytic conversion of CO_2 to chemicals on sputtered Cu and Cu–C catalysts electrodes

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Journal of Energy Chemistry 2019年第4期28卷 46-53页

作者： N.Gutiérrez-Guerra J.A.González J.C.Serrano-Ruiz E.López-Fernández J.L.Valverde A.de Lucas-Consuegra Departamento de Ingeniería Química Facultad de Ciencias y Tecnologías Químicas Universidad de Castilla-La Mancha Instituto Regional de Investigación Científica Aplicada (IRICA) and departamento de Física Aplicada Universidad de Castilla-La Mancha Departamento de Ingeniería Universidad Loyola Andalucía

A novel gas-phase electrocatalytic cell containing a low-temperature proton exchange membrane(PEM)was developed to electrochemically convert CO_2into organic compounds.Two different Cu-based cathode catalysts(Cu and Cu–C)were prepared by physical vapor deposition method(sputtering)and subsequently employed for the gas-phase electroreduction of CO_2at different temperatures(70–90°C).The prepared electrodes Cu and Cu–C were characterized by X-ray diffraction(XRD),X-ray photoemission spectroscopy(XPS)and scanning electron microscopy(SEM).As revealed,Cu is partially oxidized on the surface of the samples and the Cu and Cu–C cathodic catalysts were comprised of a porous,continuous,and homogeneous film with nanocrystalline Cu with a grain size of 16 and 8 nm,respectively.The influence of the applied current and temperature on the electro-catalytic activity and selectivity of these materials was investigated.Among the two investigated electrodes,the pure Cu catalyst film showed the highest CO_2specific electrocatalytic reduction rates and higher selectivity to methanol formation compared to the Cu–C electrode,which was attributed to the higher particle size of the former and lower Cu O/Cu ratio.The obtained results show potential interest for the possible use of electrical renewable energy for the transformation of CO_2into valuable products using low metal loading Cu based electrodes(0.5 mg Cu cm^(-2))prepared by sputtering.

关键词： C02 valorization Electro-reduction Cu catalyst PEM Selectivity Methanol production

硫化物介质中银合金失泽过程中铜的作用（英文）

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Transactions of Nonferrous Metals Society of China 2019年第12期29卷 2646-2657页

作者： J.ORTíZ-CORONA F.J.RODRíGUEZ-GóMEZ Departamento de Ingeniería Metalúrgica Facultad de QuímicaUniversidad Nacional Autónoma de México

由于暴露在硫化物环境(H2S)中,银和银合金的外观美感和电学性能往往会发生一些变化,这是文化遗产金属制品腐蚀和防护领域的一个问题。采用电化学阻抗谱(EIS)和扫描电子显微镜(SEM)技术分析0.925、0.800和0.720银合金在0.07%(体积分数)... 详细信息

由于暴露在硫化物环境(H2S)中,银和银合金的外观美感和电学性能往往会发生一些变化,这是文化遗产金属制品腐蚀和防护领域的一个问题。采用电化学阻抗谱(EIS)和扫描电子显微镜(SEM)技术分析0.925、0.800和0.720银合金在0.07%(体积分数)硫化铵溶液中浸没不同时间的失泽过程中铜的作用。极化曲线表明,铜含量和硫化物使腐蚀电流密度增大,延缓银合金的钝化。在开路电势(OCP)处得到的阻抗谱呈现不完整的、压扁的单一容抗弧,表明电荷转移电阻随着合金中铜含量增大而降低。相反,双层电容随着铜含量增大而增大。SEM-EDS分析表明,由于S优先与Cu反应,银合金中的富铜相被选择性溶解,导致局部腐蚀,从而延缓钝化膜的形成。在铜含量较低的合金中观察到明显的局部腐蚀。硫化介质中银合金失泽的机理取决于合金的性质以及铜对硫的较大亲和力。银和铜溶解形成腐蚀产物的过程被认为是速率决定步骤。

关键词：银保护与修复失泽电化学阻抗谱银合金腐蚀机理

缓蚀离子存在条件下阳极氧化提高Ti-6Al-4V合金的耐蚀性

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Transactions of Nonferrous Metals Society of China 2022年第6期32卷 1896-1909页

作者： A.L.MARTINEZ D.O.FLAMINI S.B.SAIDMAN Instituto de ingeniería Electroquímica y Corrosión(INIEC) Departamento de Ingeniería Química(DIQ)Universidad Nacional del Sur(UNS)Argentina Consejo Nacional de Investigaciones Científicas y Técnicas(CONICET) Bahía BlancaArgentina

通过恒电流阳极氧化在Ti−6Al−4V合金表面制备彩色氧化物薄膜。采用3种不同的含有腐蚀无机缓蚀剂的水溶液(Na_(2)MoO_(4),NaH_(2)PO_(4)和NH_(4)VO_(3))进行阳极化处理,研究缓蚀剂阴离子对合金在Ringer溶液中腐蚀行为的影响。采用开路电... 详细信息

通过恒电流阳极氧化在Ti−6Al−4V合金表面制备彩色氧化物薄膜。采用3种不同的含有腐蚀无机缓蚀剂的水溶液(Na_(2)MoO_(4),NaH_(2)PO_(4)和NH_(4)VO_(3))进行阳极化处理,研究缓蚀剂阴离子对合金在Ringer溶液中腐蚀行为的影响。采用开路电位(OCP)、Tafel极化、线性扫描伏安(LSV)和计时电流(CA)等手段,评估处理后电极的腐蚀性能。通过释放的Mo、V和P,采用ICP-AES技术检测缓蚀剂离子的掺入。利用扫描电子显微镜(SEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)对形成的氧化物进行表征。结果表明,无论采用何种溶液,均获得无孔或裂纹的致密无定形氧化物。在Na_(2)MoO_(4)溶液中阳极氧化样品的腐蚀电流密度最低(0.11μA/cm^(2)),即使在Ringer溶液中浸泡168 h,仍能保护合金,而未检测到裂纹或腐蚀产物。XPS分析结果显示,钼以Mo^(6+)和Mo^(4+)的形式掺入氧化膜中。

关键词： Ti−6Al−4V合金阳极氧化无机缓蚀剂腐蚀防护

Palm oil biodiesel:An assessment of PAH emissions,oxidative potential and ecotoxicity of particulate matter

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Journal of Environmental Sciences 2021年第3期33卷 326-338页

作者： Silvana Arias Francisco Molina John R.Agudelo Grupo de Investigación en Gestión y Modelación Ambiental-GAIA Escuela AmbientalFacultad de IngenieríaUniversidad de Antioquia UdeACalle 70 No.52-21MedellínColombia Departamento de Ingeniería Mecánica Universidad de Antioquia UdeA

This work assessed the impact of fuelling an automotive engine with palm biodiesel(pure,and two blends of 10%and 20%with diesel,B100,B10 and B20,respectively)operating under representative urban driving conditions on 17 priority polycyclic aromatic hydrocarbon(PAH)compounds,oxidative potential of ascorbic acid(OP^(AA)),and ecotoxicity through D aphnia pulex mortality test.PM diluted with filtered fresh air(WD)gathered in a minitunel,and particulate matter(PM)collected directly from the exhaust gas stream(W/oD)were used for comparison.Results showed that PM collecting method significantly impact PAH concentration.Although all PAH appeared in both,WD and W/oD,higher concentrations were obtained in the last case.Increasing biodiesel concentration in the fuel blend decreased all PAH compounds,and those with 3 and 5 aromatic rings were the most abundant.Palm biodiesel affected both OP^(AA)and ecotoxicity.While B10 and B20 exhibited the same rate of ascorbic acid(AA)depletion,B100 showed significant faster oxidation rate during the first four minutes and oxidized 10%more AA at the end of the test.B100 and B20 were significantly more ecotoxic than B10.The lethal concentration LC50 for B10 was 6.13 mg/L.It was concluded that palm biodiesel decreased PAH compounds,but increased the oxidative potential and ecotoxicity.

关键词： Biodiesel Particulate matter P emissions Oxidative stress Ecotoxicity Daphnia pulex

旋转输运速度场积分SPH对流扩散方程解的收敛性

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Acta Mechanica Sinica 2023年第2期39卷 61-70页

作者： Pablo Eleazar Merino-Alonso Fabricio Macià Antonio Souto-Iglesias departamento de Arquitectura Constructión y Sistemas Oceánicos y NovalesUniversidad Politécnica de MadridMadridSpain departamento de Matemática e Informática Aplicadas a las ingenierías Civil y Naval Universidad Politécnica de MadridMadridSpain

本文在刚性旋转输运速度场的特殊情况下,建立了二维平流扩散方程的积分光滑粒子流体动力学(SPH)解的收敛性.考虑了Morris等人对拉普拉斯算子的近似,在傅里叶空间中建立了SPH解与精确解的收敛性.证明了如果满足核的傅里叶变换的某个条件... 详细信息

本文在刚性旋转输运速度场的特殊情况下,建立了二维平流扩散方程的积分光滑粒子流体动力学(SPH)解的收敛性.考虑了Morris等人对拉普拉斯算子的近似,在傅里叶空间中建立了SPH解与精确解的收敛性.证明了如果满足核的傅里叶变换的某个条件,即我们称之为正条件,则收敛是有保证的.这个条件是核的傅里叶变换其径向轮廓的一阶矩为正,并通过数值验证说明了分析结果.根据L2范数和最大范数,比较了使用不同核包括SPH社区更常用的核(即Wendland核以及三次和线性样条核)获得的数值解.除此之外,提出并测试了一个病理核,该核不满足正条件,导致了非收敛结果.这一事实表明,在对流扩散方程的情况下,正条件不仅是收敛的充分条件,也是必要条件.

关键词： Smoothed particle hydrodynamics Numerical analysis Diffusion Convergence Fourier analysis