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Application of a new reagent for analysis of oxygen presence in a lowcarbon steel wire rod

journal of Iron and Steel Research International 2021年第6期28卷 729-738页

作者： M.I.Dávila-Pérez h.j.vergara-hernández O.Vázquez-Gómez F.Reyes-Calderón E.López-Martínez j.M.Salgado-López National Technology of Mexico/T.I.of Morelia Morelia 58120MichoacanMexico National Council for Science and Technology CONACYT Mexico City 03940Mexico Isthmus University Santo Domingo TehuantepecOaxaca 70760Mexico Engineering and Industrial Development Center CIDESI Santiago de Queretaro 76125QueretaroMexico

A microstructural analysis was performed to determine the presence of oxygen in a wire rod section of AISI 1008 steel with a surface mechanical failure produced during wire *** failure zone was analyzed by comparison using three different attack reagents:alkaline sodium chromate(ASC),ASC with hydrogen peroxide and amyl alcohol,and a solution of nitric acid in ethyl *** reagents were applied in samples in the failure zone,showing different types of zones in regions with internal and superficial defects such as carbides,pores,cracks,deformation,and detachment zones,indicating the possible presence of *** areas identified were observed by means of an optical microscope and were correlated with the content of elements that were present in the region using a scanning electron microscope and a scattered X-ray energy spectrometer,which determined that the areas identified by chromate sodium correspond to regions with a high concentration of oxygen and slag-forming elements such as silicon,aluminum,and iron;this is associated with the presence of oxygen in the oxide *** was also observed that the ASC and the modified ASC solution with hydrogen peroxide and amyl alcohol could identify areas with a high presence of oxides,while the nitric acid solution only identified the steel *** modified ASC solution is an alternative to identify the presence of chemical variants of oxygen because the conventional formulation is unstable and has a too short shelf life,and therefore,its application must be carried out at the time of preparation.

关键词： Etching Alkaline sodium chromate Oxide presence Internal defect

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Design and characterization of Ti6Al4V/20CoCrMo−highly porous Ti6Al4V biomedical bilayer processed by powder metallurgy

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Transactions of Nonferrous Metals Society of China 2021年第1期31卷 178-192页

作者： E.MIhALCEA h.j.vergara-hernández O.jIMENEZ L.OLMOS j.ChÁVEZ D.ARTEAGA División de Estudios de Posgrado e Investigación Tecnológico Nacional de México/ITMoreliaAv.Tecnológico#1500Colonia Lomas de SantiaguitoMoreliaC.P.58120México Universidad de Guadalajara DIPJoséGuadalupe Zuno#48Los BelenesZapopanC.P.45100México INICIT Universidad Michoacana de San Nicolás de HidalgoFco.J.Mujica S/NMoreliaC.P.58060México Departamento de Ingeniería Mecánica Eléctrica CUCEIUniversidad de GuadalajaraBlvd.Marcelino García Barragán 1421OlímpicaC.P.44430 GuadalajaraJaliscoMéxico Centro de Geociencias Universidad Nacional Autónoma de MéxicoBlvd.Juriquilla No.3001Querétaro 76230México

The aim of this work was to develop a Ti6Al4V/20CoCrMo−highly porous Ti6Al4V bilayer for biomedical *** powder metallurgy technique,with semi-solid state sintering as consolidation step,was employed to fabricate samples with a compact top layer and a porous bottom layer to better mimic natural *** densification behavior of the bilayer specimen was studied by dilatometry and the resulting microstructure was observed by scan electron microscopy(SEM)and computed microtomography(CMT),while the mechanical properties and corrosion resistance were evaluated by compression and potentiodynamic tests,*** results indicate that bilayer samples without cracks were obtained at the interface which has no negative impact on the *** values of the highly porous layer were in the lower range of those of human *** compression behavior is dictated by the highly porous Ti6Al4V ***,the corrosion resistance of Ti6Al4V/20CoCrMo is better than that of Ti6Al4V,which improves the performance of the bilayer *** work provides an insight into the important aspects of a bilayer fabrication by powder metallurgy and properties of Ti6Al4V/20CoCrMo−highly porous Ti6Al4V structure,which can potentially benefit the production of customized implants with improved wear performance and increased in vivo lifetime.

关键词： bilayer structure composites porosity sintering permeability compression behavior corrosion

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Constrained sintering and wear properties of Cu-WC composite coatings

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Transactions of Nonferrous Metals Society of China 2017年第10期27卷 2214-2224页

作者： j.L.CABEZAS-VILLA L.OLMOS h.j.vergara-hernández O.jIMéNEZ P.GARNICA D.BOUVARD M.FLORES División de Estudios de Posgrado e Investigación TecNM/Instituto Tecnológico de MoreliaAv. Tecnológico #1500 Colonia Lomas de Santiaguito Morelia Michoacán C. P. 58120 México INICIT Universidad Michoacana de San Nicolás de HidalgoFco. J. Mujica S/N Morelia Michoacán C. P. 58060 México Universidad de Guadalajara Departamento de Ingeniería de ProyectosJosé Guadalupe Zuno # 48 Los Belenes Zapopan Jalisco C. P. 45100 México Univ. Grenoble Alpes CNRS SIMaP 38000 Grenoble France

Coatings of metal matrix composites(Cu?WC)were fabricated by solid-state *** reinforcing particles indifferent quantities from5%up to30%(volume fraction)were mixed with Cu *** mixing,the powders were poured ontothe surface of copper *** was carried out at1000°C under a reducing atmosphere in a vertical *** was affected by both rigid substrates and WC particles which retarded the radial and axial densification of ***,the coatings were strongly attached to the substrate,and WC particles were randomly distributed within the *** addition ofthe reinforcing particles enhanced the microhardness and reduced the volume loss in wear tests to1/17compared to the *** predominant wear mechanism was identified as abrasion at a load of5N.20%WC(volume fraction)reinforcingparticles led to the maximum values of properties for the composite coating.

关键词： constrained sintering dilatometry dry sliding wear microhardness metal matrix composites coating

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The dark side of cyclooctatetraene(COT):Photophysics in the singlet states of“self-healing”dyes

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Chinese Chemical Letters 2024年第8期35卷 225-228页

作者： Supphachok Chanmungkalakul Syed Ali Abbas Abedi Federico j.hernández jianwei Xu Xiaogang Liu Fluorescence Research Group Singapore University of Technology and DesignSingapore 487372Singapore Department of Chemistry University College LondonLondon WC1H 0AJUnited Kingdom Institute of Sustainability for Chemicals Energy and Environment(ISCE2)Agency for ScienceTechnology and Research(A^(∗)STAR)Jurong Island 627833Singapore

Cyclooctatetraene(COT)attachment to fluorophores(“self-healing”dyes)is known for quenching reac-tive triplet states via triplet-state energy transfer(TET),enhancing ***,COT’s impact on singlet states remains *** calculations reveal that COT induces energy transfer to dark states in deep blue dyes while promoting photoinduced electron transfer(PET)and intersystem crossing(ISC)in visible dyes,potentially compromising brightness and/or *** address this,we pro-pose the use of △E descriptor to optimize COT’s *** findings uncover COT’s multifaceted *** insights will guide the development of superior triplet state quenchers and photostable dyes.

关键词： Cyclooctatetraene Photostability Triplet state quencher Energy transfer Electron transfer

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Geochemistry and mineralogy of beach sediments in the northern Gulf of Mexico,Tamaulipas state,Mexico:implication for provenance

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journal of Palaeogeography 2024年第3期13卷 375-400页

作者： Mayank Shukla Sanjeet K.Verma Mayla A.Ramos-Vázquez john S.Armstrong-Altrin Karla R.hernández-Martínez Sumit Mishra Vivek P.Malviya héctor hernández-Mendoza Posgrado de la Division de Geociencias Aplicadas Instituto Potosino de Investigacion Científica y Tecnologica(IPICYT)Camino a la Presa San José2055San Luis Potosí78216Mexico Division de Geociencias Aplicadas Instituto Potosino de Investigación Científica y Tecnologica(IPICYT)Camino a la Presa San Jose 2055San Luis Potosí78216Mexico Universidad Nacional Autonoma de México Instituto de Ciencias del Mar y LimnologíaUnidad de ProcesosOceanicos y CosterosCiudad UniversitariaCiudad de México 04510Mexico Department of Marine Sciences Bharathidasan UniversityTiruchirappalli620024Tamil NaduIndia Instituto de Geociencias Universidad Nacional Autonoma de MéxicoBoulevard Juriquilla 300176230JuriquillaQueretaroMexico Department of Applied Geology Dr.Harisingh Gour Central UniversitySagar470002Madhya PradeshIndia Instituto de Investigacion de Zonas Desérticas Universidad Autònoma de San Luis PotosíAltair 200CP 78377San LuisS.L.P.Mexico Universidad del Centro de Mexico Capitán Caldera 75CP 78250San LuisS.L.P.Mexico

Geochemical and mineralogical studies were performed in the La Pesca(LP)and Tesoro Altamira(TA)beach sediments,located in the Tamaulipas state,northern Gulf of *** main aim of this study is to infer the weathering history and provenance and to discriminate the tectonic environment of the beach *** sediments are composed of quartz with small amounts of accessory minerals such as plagioclase,calcite,orthoclase,microcline,and *** beach sediments are classified as fine-grained and very well sorted,however LP has coarse skewed and leptokurtic sediments,whereas TA has fine-skewed and very leptokurtic *** chemical index of weathering(CIW’)indicates intense weathering in the source *** quartz grain microtextures in the LP and TA are classified into mechanical,chemical,and mechanical/chemical *** features such as fractures,pits,percussion marks,abrasion fatigue,and V-shaped marks favor high-energy littoral,fluvial,subaqueous-marine,and aeolian *** chemical features indicate solution pits and crystalline overgrowth,which suggests a silica saturated marine *** mechanical/chemical features display adhering particles and elongated depressions suggest formation in a sub-aqueous nearshore marine *** and trace elements-based provenance discrimination diagrams indicate a felsic source derived from the Mesa Central(MC),Sierra Madre Oriental(SMOr)and Oaxaquia *** major and trace element concentrations imply a passive margin setting for the northern Gulf of Mexico,which is consistent with the general geology.

关键词： Beach sediments Geochemistry Mineralogy Provenance Tamaulipas Tectonic setting

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Learning to bag with a simulation‐free reinforcement learning framework for robots

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IET Cyber-Systems and Robotics 2024年第2期6卷 52-66页

作者： Francisco Munguia-Galeano jihong Zhu juan David hernández Ze ji Cooper Group University of LiverpoolLiverpoolUK School of Physics Engineering and Technology University of YorkYorkUK School of Computer Science and Informatics Cardiff UniversityCardiffUK School of Engineering Cardiff UniversityCardiffUK

Bagging is an essential skill that humans perform in their daily ***,deformable objects,such as bags,are complex for robots to manipulate.A learning-based framework that enables robots to learn bagging is *** novelty of this framework is its ability to learn and perform bagging without relying on *** learning process is accomplished through a reinforcement learning(RL)algorithm introduced and designed to find the best grasping points of the bag based on a set of compact state *** framework utilises a set of primitive actions and represents the task in five *** our experiments,the framework reached 60% and 80% success rates after around 3 h of training in the real world when starting the bagging task from folded and unfolded states,***,the authors test the trained RL model with eight more bags of different sizes to evaluate its generalisability.

关键词： reinforcement learning robot learning robotics

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Accuracy of tree mapping based on hand-held laser scanning comparing leaf-on and leaf-off conditions in mixed forests

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journal of Forestry Research 2024年第5期35卷 14-25页

作者： Frederico Tupinambá-Simões Adrián Pascual juan Guerra-hernández Cristóbal Ordóñez Tiago de Conto Felipe Bravo iuFOR Sustainable Forest Management Research InstituteUniversity of Valladolid&INIAValladolidSpain Department of Geographical Sciences University of MarylandCollege ParkMD 20742USA Forest Research Centre School of AgricultureUniversity of LisbonTapada da Ajuda1349‑017 LisbonPortugal

The use of mobile laser scanning to survey forest ecosystems is a promising,scalable technology to describe forest 3D structures at high *** confirm the con-sistency in the retrieval of forest structural parameters using hand-held laser scanning(hLS),before operationalizing the method,confirming the data is *** analyzed the per-formance of tree-level mapping based on hLS under differ-ent phenology conditions on a mixed forest in western Spain comprising Pinus pinaster and two deciduous species,Alnus glutinosa and Quercus *** area was surveyed twice during the growing season(july 2022)and once in the deciduous season(February 2022)using several scan-ning *** reference data(418 trees,15 snags)was used to calibrate the hLS data and to assess the influence of phenology when converting 3D data into tree-level attrib-utes(DBh,height and volume).The hLS-based workflow was robust at isolating tree positions and recognizing stems despite changes in ***-six percent of all pairs matched below 65 *** DBh,phenology barely altered *** observed a strong agreement when comparing hLS-based tree height *** values exceeded 2 m when comparing height measurements,confirming height data should be carefully used as reference in remote sensing-based inventories,especially for deciduous *** volume was more precise for pines(r=0.95,and rela-tive RMSE=21.3–23.8%)compared to deciduous species(r=0.91–0.96,and relative RMSE=27.3–30.5%).hLS data and the forest structural complexity tool performed remark-ably,especially in tree positioning considering mixed forests and mixed phenology conditions.

关键词： Precision forestry Forest monitoring Mobile laser scanning Forest inventory

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DNA metabarcoding reveals seasonal changes in diet composition across four arthropod-eating lizard species(Phrynosomatidae:Sceloporus)

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Integrative Zoology 2024年第3期19卷 480-495页

作者： Mauricio hernÁndez Stephanie hEREIRA-PAChECO Antton ALBERDI Aníbal h.DÍAZ DE LA VEGA-PÉREZ Arturo ESTRADA-TORRES Sergio ANCONA Yendi E.NAVARRO-NOYA Doctorado en Ciencias Biológicas Centro Tlaxcala de Biología de la ConductaUniversidad Autónoma de TlaxcalaTlaxcalaMexico Estación Científica La Malinche Centro Tlaxcala de Biología de la ConductaUniversidad Autónoma de TlaxcalaTlaxcalaMexico Center for Evolutionary hologenomics The Globe InstituteUniversity of CopenhagenCopenhagenDenmark Consejo Nacional de Ciencia y Tecnología-Centro Tlaxcala de Biología de la Conducta Universidad Autónoma de TlaxcalaTlaxcalaMexico Departamento de Ecología Evolutiva Instituto de EcologíaUniversidad Nacional Autónoma de MéxicoMexico CityMexico Laboratorio de Interacciones Bióticas Centro de Investigación en Ciencias BiológicasUniversidad Autónoma de TlaxcalaSan Felipe IxtacuixtlaTlaxcalaMexico

Diet composition and its ecological drivers are rarely investigated in coexisting closely related *** used a molecular approach to characterize the seasonal variation in diet composition in four spiny lizard species inhabiting a mountainous *** metabarcoding revealed that the lizards Sceloporus aeneus,***,***,and *** mostly consumed arthropods of the orders hemiptera,Araneae,hymenoptera,and *** terrestrial lizards *** and *** mostly predated ants and spiders,whereas the arboreal–saxicolous *** and saxicolous *** largely consumed grasshoppers and *** taxonomic and phylogenetic diversity of the prey was higher during the dry season than the rainy season,likely because reduced prey availability in the dry season forced lizards to diversify their diets to meet their nutritional *** and phylogenetic composition varied seasonally depending on the species,but only dietary composition varied with *** dietary turnover was greater in *** than in ***,suggesting site-specific seasonal variability in prey availability;no other differences among species were ***,which lives at the highest altitude in our study site,displayed interseasonal variation in diet *** differences were correlated with the species’feeding strategies and elevational distribution,which likely contributed to the coexistence of these lizard species in the studied geographic area and beyond.

关键词： arthropod-eating lizards diet breadth environmental barcoding mountainous ecosystem seasonal dietary shifts

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Generalized height-Diameter Models for Pinus montezumae Lamb. and Pinus pseudostrobus Lindl. Plantations in Michoacan, Mexico

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Open journal of Forestry 2024年第3期14卷 214-232页

作者： jonathan hernández-Ramos Valentín josé Reyes-hernández héctor Manuel De los Santos-Posadas Aurelio Manuel Fierros-González Enrique Buendía-Rodríguez Gerónimo Quiñonez-Barraza Instituto Nacional de Investigaciones Forestales Agrcolas y Pecuarias (INIFAP)-Campo Experimental Bajo Celaya Guanajuato Mxico Colegio de Postgraduados (COLPOS) Campus Montecillo Mxico INIFAP Campo Experimental Valle de Mxico Texcoco Mxico INIFAP Campo Experimental Valle del Guardiana Durango Mxico

Tree height (h) in a natural stand or forest plantation is a fundamental variable in management, and the use of mathematical expressions that estimate h as a function of diameter at breast height (d) or variables at the stand level is a valuable support tool in forest inventories. The objective was to fit and propose a generalized h-d model for Pinus montezumae and Pinus pseudostrobus established in forest plantations of Nuevo San juan Parangaricutiro, Michoacan, Mexico. Using nonlinear least squares (NLS), 10 generalized h-d models were fitted to 883 and 1226 pairs of h-d data from Pinus montezumae and Pinus pseudostrobus, respectively. The best model was refitted with the maximum likelihood mixed effects model (MEM) approach by including the site as a classification variable and a known variance structure. The Wang and Tang equation was selected as the best model with NLS;the MEM with an additive effect on two of its parameters and an exponential variance function improved the fit statistics for Pinus montezumae and Pinus pseudostrobus, respectively. The model validation showed equality of means among the estimates for both species and an independent subsample. The calibration of the MEM at the plot level was efficient and might increase the applicability of these results. The inclusion of dominant height in the MEM approach helped to reduce bias in the estimates and also to better explain the variability among plots.

关键词： Random Covariate Random Effects Variance Structure Forest Inventories Forest Management Mixed Models

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BaTiO_(3)solid solutions co-doped with Gd^(3+)and Eu^(3+):Synthesis,structural evolution and dielectric properties

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journal of Rare Earths 2024年第10期42卷 1920-1926页

作者： R.Martínez-López M.Pérez-Labra j.A.Romero-Serrano F.R.Barrientos-hernández M.Reyes-Pérez M.I.Valenzuela-Carrillo G.Urbano-Reyes V.E.Reyes-Cruz G.I.Dávila-Pulido Academic Area of Earth Sciences and Materials Autonomous University of Hidalgo StateRoad Pachuca-Tulancingo Km 4.5 Mineral de La Reforma.Hidalgo42184Mexico Metallurgy and Materials Department ESIQIE-IPNUPALMZacatencoCiudad de Mexico07738Mexico Autonomous University of Coahuila Boulevard Adolfo López Mateos S/nNueva RositaCoahuila26800Mexico

In this paper,the synthesis,structural evolution,and dielectric properties of BaTiO_(3)solid solutions codoped with rare earth elements(Gd^(3+)and Eu^(3+))prepared using the solid-state reaction method are *** pure precursor powders of BaCl_3,TiO_(2),Gd_(2)O_(3),and Eu_(2)O_(3)were mixed in stoichiometric proportions,ground in an agate mortar before being uniaxially pressed at 250 MPa and sintered at 1300℃in air atmosphere for 6 h to obtain Ba_(1-3x)Gd_(2x)Ti_(1-3x)Eu_(4x)O_(3)(x=0,0.0015,0.01 and0.1).X-ray diffraction(XRD)and Rietveld's refinement results reveal the crystal phase ferroelectric tetragonal BaTiO_(3)for the samples with x=0,0.0015 and 0.01,as well as a consistent increment in the lattice parameters caused by the *** solubility limit of Gd^(3+)and Eu^(3+)in the BaTiO_(3)structure is reached for the sample with x>0.01,and the orthorhombic Eu_2TiO_(5)and monoclinic BaTi_(2)O_(5)secondary phases were *** Raman results show the characteristic peaks of ferroelectric tetragonal BaTiO_(3)around 716 cm^(-1)(LO of A1 symmetry),515 cm^(-1)(TO of A1 symmetry),and 305 cm^(-1)(B1).The maximum relative permittivity measured at 1 khz was recorded to be 6151.8 for the sample with x=0.0015,and a decrease in the Curie temperature to 105℃with respect to the undoped sample was *** punctual microanalysis for the samples with x=0.0015,0.01,and 0.1 reveals grains composed of Ba,Ti,O,Gd,and Eu homogeneously distributed in the BaTiO_(3)*** Ba/Ti ratios for samples with x=0.0015,0.01 and 0.1 are 2.86,2.91,and 0.68,respectively,indicating substitution at the Ti site for samples with x=0.0015 and 0.01 and a substitution at the Ba site for the sample with x=0.1.

关键词： BaTiO_(3) Doping Gadolinium Europium Synthesis Rare earths

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