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Mechanical properties of the A356 aluminum alloy modified with La/Ce

Journal of Rare Earths 2013年第8期31卷 811-816页

作者： E. Aguirre-De la Torre R. Pérez-Bustamante J. Camarillo-Cisneros C.D. Gómez-Esparza H.M. Medrano-Prieto R. Martínez-Sánchez Advanced Materials Research Center (CIMAV) National Laboratory of Nanotechnology

The research of rare earths for the synthesis of materials with improved mechanical performance is of great interest when they are considered for potential applications in the automotive industry. In this regard, the effect on the mechanical properties and microstmcture of the automotive A356 aluminum alloy reinforced with 0.2 （wt.%） AI-6Ce-3La （ACL） was investigated. The ACL was added to the melted A356 alloy in the as-received condition and processed by mechanical milling. In the second route, the effect of the ACL processed by mechanical milling and powder metallurgy techniques was investigated, and compared with the results ob- tained from the A356 alloy strengthened with ACL in the as-received condition. Microstmctural properties were evaluated by means of X-ray diffraction in order to observe the solubility of Ce/La in the A1 matrix. In addition, electron microscopy was employed in or- der to investigate the effect of milling time on the size and morphology of La/Ce phase under milling process. Mechanical properties of the A356 alloy modified with ACL were measured by hardness and tensile test. For comparison unmodified specimens of the A356 were characterized according to the previous procedure. The microstructural and mechanical characterization was carried out in specimens alter solution and artificial aging. Observations in scanning electron microscopy indicated a homogeneous dispersion of La/Ce phases by using both routes; however, mechanical results, in the modified A356 alloy with the ACL in the as-received condi- tion, showed an improvement in the mechanical performance of the A356 alloy over that reinforced with the ACL mechanically milled.

关键词： A356 rare earths mechanical milling mechanical properties

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Surfactant-free synthesis of metallic bismuth spheres by microwave-assisted solvothermal approach as a function of the power level

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Frontiers of Materials Science 2016年第4期10卷 394-404页

作者： Miriam ESTRADA FLORES Patricia SANTIAGO JACINTO Carmen M. REZA SAN GERMAN Luis RENDON VAZQUEZ Raul BORJA URBY Nicolas CAYETANO CASTRO Instituto de Investigaciones en Materiales Circuito Exterior S/N Zona de Institutos Ciudad Universitaria C.P. 04510 Mexico D.F. Mexico Instituto de Fisica Circuito de la Investigaci6n Cientffica Edificio Marcos MoshinskyLaboratorio de Materiales Nanoestructurados Ciudad Universitaria C.P. 04510 Mexico D.F. Mexico Escuela Superior de Ingenierfa Qufmica e Industrias Extractivas Unidad Profesional Adolfo L6pez Mateos Edif. Z-5 2do. Piso Instituto Politecnico Nacional C.P. 07738 Mexico D.F. Mexico Centro de Nanociencias y Micro y Nanotecnologfas. Instituto Politecnico Nacional Av. Luis Enrique Erro S/NUnidad Profesional Adolfo Lopez Mateos Zacatenco Delegaci6n Gustavo A. Madero C.P. 07738 Mexico D.F. Mexico

In the present work, the synthesis of micro- and nano-sized spheres of metallic bismuth by microwave-assisted solvothermal method is reported. The synthesis method was carried out at different power levels and at a unique frequency of microwave irradiation. The sphere sizes were controlled by the microwave power level and the concentration of dissolved precursor. Structural and morphological characterization was performed by SEM, HRTEM, EELS and XRD. The results demonstrated that rhombohedral zero valent Bi spheres were synthesized after microwave radiation at 600 and 1200 W. However, if the power level is decreased to 120 W, a monoclinic phase of Bi203 is obtained with a flake-like morphology. In comparison with a conventional hydrothermal process, the microwave-assisted solvothermal approach provides many advantages such as shorter reaction time, optimum manipulation of morphologies and provides a specific chemical phase and avoids the mixture of structural phases and morphologies which is essential for further applications such as drug delivery or functionalization with organic materials, thanks to its biocompatibility.

关键词： microwave oven power level metallic bismuth spherical structures mechanism of formation electron energy loss spectroscopy (EELS)

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Dysregulation of RNA modification systems in clinical populations with neurocognitive disorders

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Neural Regeneration Research 2024年第6期19卷 1256-1261页

作者： Helen M.Knight Merve DemirbugenÖz Adriana PerezGrovas-Saltijeral Division of Cells Organisms and Molecular GeneticsSchool of Life SciencesUniversity of NottinghamNottinghamUK Department of Pharmaceutical Toxicology Faculty of PharmacyAnkara UniversityAnkaraTurkey

The study of modified RNA known as epitranscriptomics has become increasingly relevant in our understanding of disease-modifying *** of N6 adenosine(m^(6)A)and C5 cytosine(m^(5)C)bases occur on mRNAs,tRNA,mt-tRNA,and rRNA species as well as non-coding *** emerging knowledge of RNA binding proteins that act as writer,reader,and eraser effector proteins,comes a new understanding of physiological processes controlled by these *** processes when spatiotemporally disrupted within cellular nanodomains in highly specialized tissues such as the brain,give rise to different forms of *** this review,we discuss accumulating evidence that changes in the m^(6)A and m^(5)C methylation systems contribute to neurocognitive *** studies first identified mutations within FMR1 to cause intellectual disability Fragile X syndromes several years before FMR1 was identified as an m^(6)A RNA reader ***,familial mutations within the m^(6)A writer gene METTL5,m^(5)C writer genes NSUN2,NSUN3,NSUN5,and NSUN6,as well as THOC2 and THOC6 that form a protein complex with the m^(5)C reader protein ALYREF,were recognized to cause intellectual development ***,differences in expression of the m^(5)C writer and reader effector proteins,NSUN6,NSUN7,and ALYREF in brain tissue are indicated in individuals with Alzheimer's disease,individuals with a high neuropathological load or have suffered traumatic brain ***,an abundance of m^(6)A reader and anti-reader proteins are reported to change across brain regions in Lewy bodies diseases,Alzheimer's disease,and individuals with high cognitive reserve.m^(6)A-modified RNAs are also reported significantly more abundant in dementia with Lewy bodies brain tissue but significantly reduced in Parkinson's disease tissue,whilst modified RNAs are misplaced within diseased cells,particularly where synapses are *** parahippocampal brain tissue,m^(6)A modification is enri

关键词： 5-methylcytosine methylation Alzheimer's disease cognitive diseases epitranscriptomics intellectual disability Lewy body diseases N6 adenosine RNA modification

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Landslide susceptibility: a statistically-based assessment on a depositional pyroclastic ramp

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Journal of Mountain Science 2019年第3期16卷 561-580页

作者： Franny G.MURILLO-GARCíA Stefan STEGER Irasema ALCáNTARA-AYALA Institute of Geography National Autonomous University of Mexico (UNAM) Institute for Earth Observation Eurac Research

This study aimed to produce a high-quality landslide susceptibility map for Teziutlán municipality, a landslide-prone region in Mexico, which is characterised by a depositional pyroclastic ramp. The heterogeneous quality of available topographic information(i.e. higher resolution digital elevation model only for a sub-region) encouraged to confront modelling results based on two different study area delineations and two raster resolutions. Input data was based on the larger modelling region L15(163 km2) and smaller S(70 km2; located inside L15) with an associated raster cell size of 15 m(region L15 and S15) and 5 m(region S5). The resulting three data sets(L15, S15 and S5) were included into three differently flexible modelling techniques(Generalized Linear Model-GLM, General Additive Model-GAM, Support Vector Machine-SVM) to produce nine landslide susceptibility models. Preceding variable selection was performed heuristically and supported by an exploratory data analysis. The final models were based on the explanatory variables slope angle, slope aspect, lithology, relative slope position, elevation, convergence index, distance to streams, distance to springs and topographic wetness index. The ability of the models to classify independent test data was elaborated using a k-fold cross validation procedure and the AUROC(Area Under the Receiver Operating Characteristic) metric. In general, all produced landslide susceptibility maps depicted the hillslopes of the ravines, which cut the pyroclastic ramp, as prone to landsliding. The modelling results showed that predictive performances(i.e. AUROC values) slightly increased with an increasing flexibility of the applied modelling technique. Thus, SVM performed best, while the GAM outperformed the GLM. This tendency was most distinctive when modelling with the largest landslide sample size(i.e. data set L15; n = 662 landslides). Non-linear classifiers(GAMs, SVMs) performed slightly better when trained on the basis of lower

关键词： Landslide susceptibility Pyroclastic ramp Logistic regression Generalized Additive Model Support Vector Machine Cross validation

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Spatiotemporal variation in the adult sex ratio,male aggregation,and movement of two tropical cloud forest dung beetles

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Current Zoology 2022年第6期68卷 635-644页

作者： Julliana BARRETTO Martha L.BAENA Israel Huesca DOMıNGUEZ Federico ESCOBAR Red de Ecoetologıa Instituto de EcologıaXalapaC.P.91073Mexico Instituto de Investigaciones Biologicas Universidad Veracruzana.Av.Luis Castelazo Ayala s/n Col.IndustrialAnimasXalapaC.P.91190Mexico

While theory suggests that at conception the sex ratio should be balanced(1:1),this can be variable across space and time in wild ***,studies of the environmental factors that regulate adult sex ratio(ASR)in species with different life history traits are *** capture–recapture over a year,we analyzed the influence of habitat type(forest and nonforest)and season(rainy and dry)on variation in ASR,male aggregation and the trajectory movement of 2 dung beetle species with different life history traits:Deltochilum mexicanum(a hornless roller species)and Dichotomius satanas(a tunneler species with horns on its head and thorax).We found opposite *** *** population tends to be female-biased,but the population of *** tends to be predominantly male,and observed values were not related to habitat type or ***,the 95%confidence intervals estimated were highly variable between seasons depending on *** examining the monthly variation in ASR for both habitats,we found that it depends on the *** addition,male aggregation differed between species depending on habitat type and season,and species movement patterns were closely related to their habitat *** on our results,we argue that comparative population studies of species with different life history traits are necessary to understand the variation in demographic parameters as well as its ecological and evolutionary implications in the face of spatial and climatic environmental variation.

关键词： habitat preference mark-recapture mean crowding seasonality Scarabaeinae sex proportion

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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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Biotransformation and degradation of 2,4,6-trinitrotoluene by microbial metabolism and their interaction

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Defence Technology（防务技术） 2018年第2期14卷 151-164页

作者： mónica y. serrano-gonzález rashmi chandra carlos castillo-zacarias felipe robledo-padilla magdalena de j. rostro-alanis roberto parra-saldivar Tecnologico de Monterrey School of Engineering and ScienceCampus MonterreyAve.Eugenio Garza Sada 2501MonterreyN.L.CP 64849Mexico

2,4,6-trinitrotoluene(TNT) and its derivatives are nitrogen-containing aromatic compounds having chemical and thermal stability at ambient temperature and pressure. TNT has high toxicity and mutagenic activity to humans, plants and animals, thus decontamination processes are necessary. Many microorganisms are capable to bioremediate TNT such as bacteria from the genera Pseudomonas,Enterobacter, Rhodococcus, Mycobacterium, Clostridium and Desulfovibrio: fungus such as Phanerochate and Stropharia species are able to perform TNT biotransformation under aerobic and anaerobic conditions. In this work we review the state of TNT biodegradation by various routes: aerobic, anaerobic,combined, fungal, enzymatic, and bio-electrochemical.

关键词： Laccases Aerobic degradation Anaerobic degradation Fungal TNT degradation

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Enhanced Ferromagnetism in ZnO Nanoribbons and Clusters Passivated with Sulfur

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Nano Research 2008年第5期1卷 420-426页

作者： Andres R.Botello-Mendez Florentino Lopez-Urias Mauricio Terrones Humberto Terrones National Laboratory for Nanoscience and Nanotechnology Research(LINAN) Advanced Materials DepartmentIPICYTCamino a la Presa San José205578216S.L.P.Mexico

Inspired by recent experimental results,the electronic and magnetic properties of sulfur-passivated ZnO clusters and zigzag nanoribbons have been studied using fi rst principles calculations in the framework of the local spin density *** the case of the ZnO nanoribbons,the sulfur atoms or thiol groups were attached in different ways to the zinc or oxygen atoms located at the edges,whereas in clusters,the sulfur atoms were set on the surface,mainly interacting with atoms with low-coordinate *** an exhaustive atomic relaxation,we found that a magnetic moment emerges in zigzag nanoribbons both with and without sulfur-passivation on the ***,the magnitude of the magnetic moment is very sensitive to sulfur *** particular,we found that when sulfur is attached to the zinc atoms in an alternating fashion along the ribbon edges,the magnetic moment is a maximum(1.4μB/unit cell).In the case of clusters,we found that the Zn_(15)O_(15) cluster exhibits a high spin moment of 5.5μB when capped with sulfur *** calculations indicate that sulfur-passivating of ZnO nanosystems could be responsible for recently observed ferromagnetic responses.

关键词： Zinc oxide sulfur magnetism nanoribbons clusters

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Variability in the Light Absorption Coefficient by Phytoplankton,Non-Algal Particles and Colored Dissolved Organic Matter in the Northern Gulf of California

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Open Journal of Marine Science 2018年第1期8卷 20-37页

作者： Stella P.Betancur-Turizo Adriana G.González-Silvera Eduardo Santamaría-Del-Angel Roberto Millán-Núnez Eduardo Millán-Núnez Héctor García-Nava Víctor M.Godínez Laura Sánchez-Velasco Facultad de Ciencias Marinas Universidad Autonoma de Baja CaliforniaEnsenadaMéxico Grupo de Investigacion en Oceanología Facultad de Oceanografía FísicaEscuela Naval de Cadetes“Almirante Padilla”Barrio BosqueSector ManzanilloCartagena de IndiasColombia Departamento de Ecología Marina CICESEEnsenadaMéxico Instituto de Investigaciones Oceanológicas Universidad Autónoma de Baja CaliforniaEnsenadaMéxico Departamento de Oceanografía Física CICESEEnsenadaMéxico Departamento de Plancton y Ecología Marina CICIMAR-IPN.Av.Instituto Politécnico Nacional s/nLa PazMéxico

Variability of the optical properties of the northern Gulf of California (México) were analyzed for the first time based on six cruises performed from spring to summer (March to September) between 2008 and 2013. The changes observed in the absorption by three seawater components (phytoplankton, detritus and chromophoric dissolved organic matter or CDOM) were analyzed in relation to changes in bio-optical regions and composition of the phytoplankton community (determined based on phytoplankton pigments). Two regions with unique bio-optical characteristics were identified separated by a narrow transition zone: the Upper Gulf of California (UGC) and Northern Gulf of California (NGC). Despite the temporal changes in their spatial distribution they maintained particular characteristic. UGC is characterized by an average Chla of 1.78 mg/m3, the dominance of microphytoplankton (diatoms and dinoflagellates) and a stronger contribution of detritus to total light absorption. NGC is characterized by an average Chla of 0.7 mg/m3 and the predominance of picophytoplankton, characterized by the dominance of zeaxanthin (marker pigment for cyanobacteria) and/or chlorophyll b (marker pigment for green algae), along with a co-dominium by CDOM and phytoplankton to light absorption. Results indicate that Case II waters can be very different when evaluating the individual contribution by phytoplankton, detritus and CDOM to total light absorption what has to be considered for the selection of bio-optical models for each specific region what can also help to a better definition of the related uncertainties.

关键词： Light Absorption Phytoplankton CDOM Detritus Ocean Color Gulf of California

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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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