Search results for "characterization"

showing 10 items of 1054 documents

Selective oxidative dehydrogenation of ethane over SnO2-promoted NiO catalysts

2012

[EN] Ni-Sn-O mixed oxides catalysts have been investigated for the oxidative dehydrogenation of ethane. The catalysts were prepared through the evaporation of aqueous solutions of nickel nitrate and tin oxalate and finally calcined in air at 500 degrees C for 2 h. These materials have been characterized by several techniques (N-2-adsorption, X-ray diffraction, High-Resolution Electron Microscopy, temperature programmed reduction, X-Ray Photoelectron Spectroscopy, Fourier Transformed Infrared Spectroscopy of adsorbed CO and O-18/O-16 isotope exchange). The addition of just a tiny amount of tin highly increases the selectivity to ethylene (from ca. 40% to 80-90%). Thus, high selectivity to et…

SnO2-promotedInorganic chemistrychemistry.chemical_elementInfrared spectroscopyTin oxideCatalysisOxalateCatalysisEthane ODHNiO catalystsEthane oxidationchemistry.chemical_compoundNickelEthyleneTin oxidechemistryDehydrogenationPhysical and Theoretical ChemistryTemperature-programmed reductionTinOxidative dehydrogenation of ethaneNickel oxideCatalyst characterization (XPS HREM oxygen isotope exchange FTIR CO adsorbed)
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Geochemical characterization of soil organic matter and variability of a postglacial detrital organic supply (chaillexon lake, france)

1998

Soil organic matterGeography Planning and DevelopmentOrganic geochemistryEarth and Planetary Sciences (miscellaneous)GeochemistrySoil scienceGeologyEarth-Surface ProcessesCharacterization (materials science)Earth Surface Processes and Landforms
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Heterogeneous Gold Catalyst: Synthesis, Characterization, and Application in 1,4-Addition of Boronic Acids to Enones

2015

The new 1 wt % Au/TiO2–UVM-7 catalyst was prepared and fully characterized. This heterogeneous catalyst proved to be active, selective and recyclable for the unprecedented gold-catalyzed 1,4-addition of various functionalized arylboronic acids to 2-cyclohexen-1-one and other selected enones using toluene as a solvent. The gold-based catalyst was recycled two times and played an active role in this reaction, and the nature of the solvent determined a remarkable change in the products’ selectivities.

Solventchemistry.chemical_compoundChemistryOrganic chemistryGeneral ChemistrySolvent effectsHeterogeneous catalysisSelectivityTolueneCatalysisCatalysisCharacterization (materials science)ACS Catalysis
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New records of Lepidochelys olivacea (Eschscholtz, 1829) (Testudines, Cheloniidae) provide evidence that Uruguayan waters are the southernmost limit …

2017

We report 8 new records of Lepidochelys olivacea marine turtle in the Uruguayan waters, indicating this area as the southernmost limit of distribution for this species in the western Atlantic Ocean. In addition, 1 specimen was subjected to genetic analysis, revealing its population origin in the western Atlantic nesting colonies (Surinam, French Guiana, and Brazil). This report represents an update of the distribution of L. olivacea in the southwestern Atlantic and provides insight into the morphological and genetic characterization of the species at temperate waters.

Southwestern Atlantic Oceangenetic characterizationOlive Ridley Sea Turtle
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Laser-Induced Breakdown Spectroscopy for Rapid Elemental Analysis of Drillcore

2013

Abstract The elemental and mineralogical contents of rock drillcore can be analyzed using a variety of methods. For efficient exploration the characterization of the drillcore should be performed rapidly, so that the further drillings can be better planned and unnecessary costs can be reduced. In this paper, laser-induced breakdown spectroscopy (LIBS) is studied as a potential rapid on-line method for automated elemental analysis of drillcore. The method is based on a pulsed laser beam that transforms a small volume of the sample into plasma. Individual elements in the plasma have characteristic emission patterns detectable by a spectrometer. Based on the measured spectra the amount of diff…

SpectrometerInfraredElemental analysisChemistrySample (material)Analytical chemistryMineralogyHyperspectral imagingGeneral MedicineLaser-induced breakdown spectroscopySpectroscopyCharacterization (materials science)IFAC Proceedings Volumes
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Chemical characterization of ancient liturgical vestment (chasuble) by Inductively Coupled Plasma–Optical Emission Spectrometry (ICP–OES)

2016

Abstract This paper presents the chemical characterization of the yarns of an ancient liturgical vestment (chasuble). The samples have been analyzed for Al, Ag, Au, Cd, Co, Cr, Cu, Ni, Pb and Zn using amounts always less than 1 mg by Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES). Except a sample, silver is the most abundant element in all the yarns. In the samples containing silver, it ranged from 68 to 97%. Only two samples contain aluminum. Although the investigated chasuble is recorded in the inventory as an artifact of the XV century, a part of the yarns is composed of materials attributed to later period. In fact, the voluntary use of aluminum in metal alloys is du…

Spectroscopy.Period (periodic table)Analytical chemistrychemistry.chemical_element02 engineering and technology01 natural sciencesSettore CHIM/12 - Chimica Dell'Ambiente E Dei Beni CulturaliTextile yarnAnalytical ChemistryMetalAluminiumSettore CHIM/01 - Chimica AnaliticaOptical emission spectrometryICP–OESSpectroscopyChemistryMetal010401 analytical chemistry021001 nanoscience & nanotechnology0104 chemical sciencesCharacterization (materials science)MetalsInductively coupled plasma atomic emission spectroscopyvisual_artvisual_art.visual_art_mediumLiturgical vestmentInductively coupled plasma0210 nano-technologyTextile yarnsChasuble
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The Psychological Science Accelerator’s COVID-19 rapid-response dataset

2023

Funder: Amazon Web Services (AWS) Imagine Grant

Statistics and Probability223 participants with varying completion rates. Participants completed the survey from 111 geopolitical regions in 44 unique languages/dialects. The anonymized dataset described here is provided in both raw and processed formats to facilitate re-use and further analyses. The dataset offers secondary analytic opportunities to explore copingBF Psychology230 Affective NeuroscienceHealth Behaviorand demographic information for each participant. Each participant started the study with the same general questions and then was randomized to complete either one longer experiment or two shorter experiments. Data were provided by 73Message framingDiseasesLibrary and Information Sciences:Ciências Sociais::Psicologia [Domínio/Área Científica]geographical and cultural context characterizationHV Social pathology. Social and public welfare. CriminologypandemiatEducationa general questionnaire examining health prevention behaviors and COVID-19 experienceddc:150SDG 3 - Good Health and Well-beingRA0421 Public health. Hygiene. Preventive MedicineSurveys and QuestionnairesAdaptation PsychologicalyleiskartoituksetHumansPendienteHealth behaviorsPandemicsframingBehaviour Change and Well-beingEmotion regulationSelf-determination messagingand self-determination across a diverseCOVID-19kansainvälinen vertailuResearch dataComputer Science Applicationswhich can be merged with other time-sampled or geographic data.cognitive reappraisalsglobal sample obtained at the onset of the COVID-19 pandemicterveyskäyttäytyminenIn response to the COVID-19 pandemic/dk/atira/pure/sustainabledevelopmentgoals/good_health_and_well_beingand autonomy framing manipulations on behavioral intentions and affective measures. The data collected (April to October 2020) included specific measures for each experimental studyStatistics Probability and UncertaintyPeople’s healthtutkimusaineistosurvey-tutkimusDatasetInformation Systemsthe Psychological Science Accelerator coordinated three large-scale psychological studies to examine the effects of loss-gain framing
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Microstructural sensitivity of local porosity distributions

1992

The recently introduced concept of local porosity distributions for the geometric characterization of arbitrary porous media is scrutinized using computer generated pore space images. The paper presents the first direct determination of local porosity distributions from digital images. Pore space images with identical two point correlation functions are employed to analyse the geometrical sensitivity of the local porosity concept. The main finding is that local distributions can be used to discriminate between images which are indistinguishable using standard correlation functions. We also discuss the question of length scales associated with the local porosity concept.

Statistics and ProbabilityDigital imageGeometryCharacterisation of pore space in soilSensitivity (control systems)Condensed Matter PhysicsPorosityPorous mediumPhysics::GeophysicsCharacterization (materials science)MathematicsPoint correlationPhysica A: Statistical Mechanics and its Applications
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Characterization of the parameters of interior permanent magnet synchronous motors for a loss model algorithm

2017

Abstract The paper provides the results of a detailed experimental study on the variations of the characteristics of an interior permanent magnet synchronous motor, when load, speed and/or magnetization conditions vary. In particular, the characterization is carried out by assessing, for several working conditions, the motor parameters that influence its efficiency. From the knowledge of the variability of these parameters, it is possible to develop a dynamic model of the motor, which accurately describes its behaviour and allows estimating the power losses for whatever speed and load. In order to validate the model, the values of the power losses obtained by using the model are compared wi…

Statistics and ProbabilityEngineering3304020209 energyCondensed Matter Physic02 engineering and technologySettore ING-IND/32 - Convertitori Macchine E Azionamenti ElettriciControl theoryComponent (UML)0202 electrical engineering electronic engineering information engineeringElectrical and Electronic EngineeringInstrumentationPermanent magnet synchronous motorInterior permanent magnet synchronous motorSpeed control drive systembusiness.industryApplied Mathematics020208 electrical & electronic engineeringInterior permanent magnet synchronous motors; Power loss minimization; Speed control drive systems; Statistics and Probability; 3304; Condensed Matter Physics; Applied MathematicsCondensed Matter PhysicsPower loss minimizationCharacterization (materials science)Power (physics)Settore ING-IND/31 - ElettrotecnicaMotor efficiencySynchronous motorbusinessSettore ING-INF/07 - Misure Elettriche E ElettronicheAlgorithmMeasurement
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Local porosity theory for electrical and hydrodynamical transport through porous media

1993

The current status of local porosity theory for transport in porous media is briefly reviewed. Local porosity theory provides a simple and general method for the geometric characterization of stochastic geometries with correlated disorder. Combining this geometric characterization with effective medium theory allows for the first time to understand a large variety of electrical and hydrodynamical flow experiments on porous rocks from a single unified theoretical framework. Rather than reproducing or rephrasing the original results the present review attempts instead to place local porosity theory within the context of other current developments in theory and experiment.

Statistics and ProbabilityPhysicsContext (language use)MechanicsCondensed Matter PhysicsPhysics::GeophysicsCharacterization (materials science)Theoretical physicsPermeability (earth sciences)Flow (mathematics)Simple (abstract algebra)Current (fluid)PorosityPorous mediumPhysica A: Statistical Mechanics and its Applications
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