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Wettability of silicon carbide ceramic by Al_2O_3/Dy_2O_3 and Al_2O_3/Yb_2O_3 systems

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journal of rare Earths 2013年第6期31卷 634-638页

作者： j.A.da silva B.m.moreschi G.C.r.Garcia s.ribeiro Department of materials Engineering (DEmAr) Engineering School of Lorena (EEL)Pólo Urbo IndustrialGleba AI6CP 11612608-970LorenaSPBrazil

Wettability is an important phenomenon in the liquid phase sintering of silicon carbide （siC） ceramics. This work involved a study of the wetting of siC ceramics by two oxide systems, Al2O3 /Dy2O3 and Al2O3 /Yb2O3, which have so far not been studied for application in the sintering of siC ceramics. Five mixtures of each system were prepared, with different compositions close to their respective eutectic ones. samples of the mixtures were pressed into cylindrical specimens, which were placed on a siC plate and subjected to temperatures above their melting points using a graphite resistance furnace. The behavior of the melted mixtures on the siC plate was observed by means of an imaging system using a CCD camera and the sessile drop method was employed to determine the contact angle, the parameter that measures the degree of wettability. The results of variation in the contact angle as a function of temperature were plotted in graphic form which showed that the curves displayed a fast decline and good spreading. All the samples of the two systems presented final contact angles of 40o to 10o indicating their good wetting on siC in the argon atmosphere. The melted/solidified area and interface between siC and melted/solidified phase were evaluated by scanning electron microscopy （sEm） and their crystalline phases were identified by X-ray diffraction （DrX）. The DrX analysis showed that Al2O3 and rE2O3 reacted and formed the Dy3Al5O12 （DyAg） and Yb3Al5O12 （YbAg） phases. The results indicated that the two systems had a promising potential as additives for the sintering of siC ceramics.

关键词： liquid-phase sintering silicon carbide rare earth oxide wettability contact angle

FrACTUrE rEsIsTANCE OF 3D-C/siC COmPOsITEs AT 1300℃

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Acta metallurgica sinica(English Letters) 2004年第4期17卷 437-442页

作者： G.C.ji s.r.Qiao s.m.Du m.Li D.Han j.N.Wei College of materials science and Engineering Northwestern Polytechnical University Xi'an 710072China Material Engineering Department Jiujiang College Jiujiang 332005 ChinaCollege of Materials Science and Engineering Northwestern Polytechnical University Xi'an 710072ChinaMaterial Engineering Department Xi'an Science and Technical University Xi'an 710060 ChinaCollege of Materials Science and Engineering Northwestern Polytechnical University Xi'an 710072ChinaCollege of Materials Science and Engineering Northwestern Polytechnical University Xi'an 710072ChinaMaterial Engineering Department Jiujiang College Jiujiang 332005 China

Based on the energy conservation, the elastic energy linked to the compliance change, non-elastic energy dissipated by irreversible deformation and the resistance for crack propagation were quantitatively characterized by evaluation the load/load point displacement curves tested by three points bend experiment with single notch beam at 1300℃. The cracks length was determined by compliance calibration curves. It is shown by experimental results that the compliance of 3D-C/siC composites changes with the cracks can be described by third order polynomial. The variation of crack advancing resistance with non-dimensional equivalent crack length presents a convex curve. The crack advancing resistance increases firstly and then decreases with the non-dimensional equivalent crack length, finally is in comparatively low level. The maximum values of crack advancing resistance are 269.73kj/m2 for non-dimensional equivalent crack length of 0.318 and original notch length of 0.35mm, and 138.65kj/m2 for non-dimensional equivalent crack length of 0.381 and original notch length of 2.06mm, respectively.

关键词： fracture resistance 3D-C/siC energy conservation

Development of an operational land water mask for mODIs Collection 6,and influence on downstream data products

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International journal of Digital Earth 2017年第2期10卷 207-218页

作者： m.L.Carroll C.m.Dimiceli j.r.G.Townshend r.A.sohlberg A.I.Elders s.Devadiga A.m.sayer r.C.Levy NAsA/GsFC Biospheric sciences Laboratory GreenbeltMDUSA science systems and Applications Inc. LanhamMDUSA Department of Geographical sciences University of MarylandCollege ParkMDUSA Atmospheric Oceanic and Earth SciencesGeorge Mason UniversityFairfaxVAUSA NAsA/GsFC Terrestrial Information systems Laboratory GreenbeltMDUSA fGoddard Earth sciences Technology and research Universities Space Research AssociationGreenbeltMDUSA NAsA/GsFC Climate and radiation Laboratory GreenbeltMDUSA

Data from the moderate resolution Imaging spectro-radiometer(mODIs)on-board the Earth Observing system Terra and Aqua satellites are processed using a land water mask to determine when an algorithm no longer needs to be run or when an algorithm needs to follow a different *** the fourth reprocessing(Collection 6(C6))the mODIs team replaced the 1 km water mask with a 500 m water mask for improved representation of the continental *** new water mask represents more small water bodies for an overall increase in water surface from 1%to 2%of the continental *** this is still a small fraction of the overall global surface area the increase is more dramatic in certain areas such as the Arctic and Boreal regions where there are dramatic increases in water surface area in the new *** products generated by the on-going C6 reprocessing using the new land water mask show significant impact in areas with high concentrations of change in the land water *** differences between the Collection 5(C5)and C6 water masks and the impact of these differences on the mOD04 aerosol product and the mOD11 land surface temperature product are shown.

关键词： Earth observation image processing land cover remote sensing water resources

Effect of ECAP consolidation temperature on the microstructure and mechanical properties of Al-Cu-Ti metallic glass reinforced aluminum matrix composite

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journal of materials science & Technology 2017年第9期33卷 1031-1038页

作者： m.r.rezaei s.G.shabestari s.H.razavi school of metallurgy and materials Engineering Iran University of Science and Technology (IUST) Center of Excellence for High strength Alloys Technology (CEHsAT) School of Metallurgy and Materials EngineeringIran University of Science and Technology (IUST)

Al;Cu;Ti;metallic glass（AmG） reinforced Al matrix composites were consolidated by equal channel angular pressing（ECAP） process. The effects of ECAP consolidation temperature ranging from room temperature to just below the first crystallization temperature of metallic glass on the consolidation of composites were investigated in terms of the relative densities, structural evolutions and mechanical properties of composites. some intermetallic compounds included Al;CuTi;, Al;Ti and Al;Cu;precipitated from metallic glass particles at consolidation temperature of 300?C. Consolidation temperature did not affect the matrix grains size of the composite. Quantitative analysis revealed that the distribution of reinforcing particles was considerably dependent on consolidation temperature. Density of the composite was increased by increasing the consolidation temperature to 250?C. The composite consolidated at250?C through ECAP process, exhibited the best combination of yield strength and ductility of 184 mPa and 48%, respectively.

关键词： Al matrix composite(AmC) Equal channel angular pressing(ECAP) Consolidation temperature Glass particles

small extrachromosomal circular DNA in amyotrophic lateral sclerosis matter

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Neural regeneration research 2025年第5期20卷 1411-1413页

作者： marcos j.Arauzo-Bravo Daniela Gerovska matthias schwab Alexandra Kretz Computational Biology and systems Biomedicine Biodonostia Health Research InstituteSan SebastianSpain Basque Foundation for science IKERBASQUEBilbaoSpainMax Planck Institute for Molecular BiomedicineComputational Biology and Bioinformatics GroupMünsterNorth Rhine-WestphaliaGermany Department of Cell Biology and Histology Faculty of Medicine and NursingUniversity of Basque Country(UPV/EHU)LeioaSpain Department of Neurology Jena University HospitalJenaThuringiaGermany

Comprehensive studies identify motor neuron spectrum disorders including amyotrophic lateral sclerosis(ALs)as globally rising fatal disorders with the highest prevalence in aging populations,influenced by ethnicity and ancestry(GBD 2016 motor Neuron Disease Colla borators,2018).While~10% of diagnoses involve a family history(fALs),most cases are considered sporadic(sALs).However,population-based studies suggest that even cases without a common index mutation impart heritability(ryan et al.,2019),indicating a crucial role of rare and as yet unknown genetic denominators.

关键词： amyotrophic sclerosis

Hydrogen production by catalytic decomposition of methane using a Fe-based catalyst in a fluidized bed reactor

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journal of Natural Gas Chemistry 2012年第4期21卷 367-373页

作者： D.Torres s.deLlobet j.L.Pinilla m.j.Lzaro I.suelves r.moliner Instituto de Carboquímica CSICMiguel Luesma Castn 450018 ZaragozaSpain

Catalytic decomposition of methane using a Fe-based catalyst for hydrogen production has been studied in this work. A Fe/Al2O3 catalyst previously developed by our research group has been tested in a fluidized bed reactor （FBr）. A parametric study ot the effects of some process variables, including reaction temperature and space velocity, is undertaken. The operating conditions strongly affect the catalyst performance. methane conversion was increased by increasing the temperature and lowering the space velocity. Using temperatures between 700 and 900℃ and space velocities between 3 and 6 LN/（gcat·h）, a methane conversion in the range of 25%-40% for the gas exiting the reactor could be obtained during a 6 h run. In addition, carbon was deposited in the form of nanofilaments （chain like nanofibers and multiwall nanotubes） with similar properties to those obtained in a fixed bed reactor.

关键词： hydrogen production fluidized bed reactor metal catalysts

solar spectral conversion based on plastic films of lanthanide-doped ionosilicas for photovoltaics:Down-shifting layers and luminescent solar concentrators

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journal of rare Earths 2020年第5期38卷 531-538页

作者： m.A.Cardoso s.F.H.Correia A.r.Frias H.m.r.Goncalves r.F.P.Pereira s.C.Nunes m.Armand P.s.André V.de Zea Bermudez r.A.s.Ferreira Department of Physics and CICECO-Aveiro Institute of materials University of Aveiro3810-193AveiroPortugal Department of Chemistry and CQ-Vr University of Tras-os-Montes e Alto Douro5000-801Vila RealPortugal Instituto de Telecomunicacoes University of Aveiro3810-193AveiroPortugal rEQUImTE Instituto Superior de Engenharia do Porto4200-072PortoPortugal Chemistry Centre and Chemistry Department University of Minho4710-057BragaPortugal CICs-Health sciences research Center and Chemistry Department University of Beira Interior6201-001CovilhaPortugal Electrical Energy storage Department CIC EnergiguneParque Tecnologico de AlavaMinano01510Spain Department of Electrical and Computer Engineering Instituto de TelecomunicacoesInstituto Superior TecnicoUniversidade de Lisboa1049-001LisbonPortugal

The mismatch between the photovoltaic(PV)cells absorption and the solar irradiance on earth is one of the major limitations towards more efficient PV energy *** aspect was addressed by downshifting the solar irradiance on Earth through luminescent down-shifting layers based on lanthanidedoped surface-functionalized ionosilicas(Iss)embedded in poly(methyl methacrylate)(PmmA)coated on the surface of commercial si-based PV *** Is-PmmA hybrid materials exhibit efficient solar radiation harvesting(spectral overlap of^9.5×10^19 photons/(s·m2))and conversion(quantum yield^52%).The direct solar radiation and the down-shifted radiation are partially guided and lost through total internal reflection to the layer edges being unavailable for PV conversion of the coated PV *** tuning the down-shifting layer thickness,it also acts as luminescent solar concentrator enabling the collection of the guided radiation by flexible PV cells applied on the borders of the down-shifting layer leading to an enhancement of the PV energy conversion from^5%(in the case of the single-use of the luminescent down-shifting layer)to^13%comparing with the bare PV *** overall electrical output of the device resulted in an absolute external quantum efficiency increase of^32%for the optimized Eu^3+-based films in the UV spectral region(compared with the bare PV device,which is among the best values reported so far).

关键词： Ionosilicas Lanthanides Photovoltaics Luminescent solar concentrators Down-shifting layers silicon photovoltaic cells

Assessment of mercury(II) bioavailability using a bioluminescent bacterial biosensor: Practical and theoretical challenges

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journal of Environmental sciences 2010年第8期22卷 1137-1143页

作者： Paulo r G Barrocas William m Landing robert j m Hudson Department of sanitation and Environmental Health National School of Public Health Oswaldo Cruz Foundation Department of Oceanography Florida State University. Tallahassee Department of Natural resources and Environmental sciences University of Illinois

Critical methodological challenges in the microbial biosensor approach to assessing Hg（II） bioavailability were evaluated from the perspective of analytical chemists. The main challenge stems from the fact that the chemical speciation of Hg（II） in natural waters exerts a major control on its bioavailability, yet its natural complexation equilibria are extensively altered during conventional bioassays. New data, obtained using a bioluminescent Hg（II）-biosensor, that illustrate these challenges are presented and potential solutions proposed.

关键词： mercury bioavailability biosensor chemical speciation bioluminescent

Effect of External Forced Flow and Boiling Film on Heat Transfer of AIsI 4140 steel Horizontal rod During Direct Quenching

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journal of Iron and steel research International 2011年第10期18卷 34-41页

作者： A H meysami r Ghasemzadeh s H seyedein m r Aboutalebi Department of metallurgy and material Engineering Golpayegan University Centre of Excellent for Advanced material and Processing School of Metallurgy and Material EngineeringIran University of Science and Technology

The effects of rod falling and moving, external flow field, boiling film and radiation were investigated on fluid flow and heat transfer of AIsI 4140 steel horizontal rod during direct quenching by mathematical modeling. The flow field and heat transfer in quenching tank were simulated by computational fluid dynamics （CFD） method considering falling and moving of rods during process. Therefore, modeling of flow field was done by a fixed-mesh method for general moving objects equations, and then, energy equation was solved with a numerical approach so that effeet of boiling film heat flux was considered as a source term in energy equation for solid-liquid boundary. simulated results were verified by comparing with published and experimental data and there was a good agreement between them. Also, the effects of external forced flow and film boiling were investigated on heat flux output, temperature distribution and heat transfer coefficient of rod. Also simulated results determined optimum quenching time for this process.

关键词： direct quenching AIsI 4140 moving object heat transfer modeling