Search results for "thermal [radiation]"

showing 10 items of 1167 documents

Thermomineral waters of Greece: geochemical characterization

2020

75 °C). In terms of pH most results vary from 5.5 to 823 °C) ii) warm (23 40 °C) iii) thermal (40 75 °C) and iv) hyperthermal (&gtfew springs show either very low pH (&lt10) proposing serpentinization processes. Regarding TDS concentrations collected waters can be subdivided into low salinity (up to 1.5 g/L) brackish (up to 20 g/L) and saline (up to 43 g/L). The medium high salinities can be justified by mixing with sea water and/or strong waterrock interaction processes. Isotope composition of O and H ranges from 12.7 to +2.7 ‰ SMOW and from 91 to +12 ‰ SMOW respectively and is generally comprised between the Global Meteoric Water Line and the East Mediterranean Meteoric Water Line. Only few water samples show a positive shift for δ18O possibly related to high temperature waterrock interaction processes. Carbon dioxide (18 997000 μmol/mol) or N2 (1100 989000 μmol/mol) or CH4 (&ltMany geothermal areas of Greece are located in regions affected by Miocene or Quaternary volcanism and in continental basins characterised by elevated heat flow. Moreover the majority of them is found along the coast as well as in islands of the Aegean Sea and thus thermal water is often brackish to saline due to marine intrusion into costal aquifer. In the present study almost 300 thermal and cold mineral water samples were collected along the Hellenic territory with their physicochemical parameters (temperature pH electrical conductivity and Eh) and the amount of bicarbonates (titration with 0.1N HCl) being determined in situ. Additionally gases found either in free or dissolved phase were sampled. Both water and gas samples were analysed at the INGVPa laboratories for major ions (Ion Chromatography) silica (Inductively Coupled Plasma Optical Emission Spectrometry) chemical composition of free and dissolved gases (Gas Chromatography) water isotopes (O and H) and carbon and helium isotopes of free and dissolved gases (Mass Spectrometry). The temperature of the investigated waters ranges from 6.5 to 98°C pH from 1.96 to 11.98 whilst Total Dissolved Solids (TDS) from 0.06 to 43 g/L. Based on the temperature parameter waters can be divided into four groups: i) cold (&lt0.5 913000 μmol/mol) are the prevailing gas species found in the studied sites. The δ13CCO2 values ranged from 20.1 to +8.5 ‰ whilst the isotope ratio of He from 0.21 to 6.71 R/RA.4) suggesting interaction with H2Srich gases or very high pH values (&gtSettore GEO/08 - Geochimica E Vulcanologia
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Filling the Gap in the Metallacrown Family: The 9‐MC‐3 Chromium Metallacrown

2021

Abstract In this work, we report on a long‐sought missing complex in the metallacrown family. We synthesized and characterized the novel chromium metallacrown (MC) complex {CrIII(μ 2‐piv)3[9‐MCCr(III)N(shi)‐3](morph)3}⋅MeOH (in which shi3−=salicyl hydroxamate, piv=pivalate, and morph=morpholine). The MC with a 9‐MC‐3 cavity of kinetically inert chromium(III) ions was synthesized by a solvothermal reaction. Magnetization measurements reveal a high spin ground state.

9-MC-3540 Chemistry and allied sciencesCluster Compounds | Hot PaperCommunicationOrganic Chemistrykinetic stabilityStructural integritychemistry.chemical_elementGeneral ChemistrySolvothermal reactionCatalysisCommunicationsIonmetallacrownMagnetizationCrystallographyChromiumchemistry.chemical_compoundstructural integritychemistry540 ChemieMorpholinechromiumGround stateMetallacrownChemistry (Weinheim an Der Bergstrasse, Germany)
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Quantum well intermixing in GaInNAs/GaAs structures

2003

We report on the characteristics of quantum well intermixing in GaInNAs/GaAs structures of differing N content. Rapid thermal annealing combined with SiO2 caps deposited on the surface of the samples is used to disorder 1.3 mum GaInNAs/GaAs multiquantum wells which have been preannealed in-situ to the stage of blueshift saturation. The different effects of two capping layer deposition techniques on the interdiffusion of In-Ga have been compared, particular regarding the role of sputtering processes. The dependence of quantum well intermixing-induced photoluminescence blueshift on N concentration has provided extra information on the intrinsic properties of the GaInNAs/GaAs material system. …

:Science::Physics::Optics and light [DRNTU]Materials sciencePhotoluminescencebusiness.industryAlloyGeneral Physics and Astronomyengineering.materialSettore ING-INF/01 - ElettronicaBlueshiftGallium arsenidechemistry.chemical_compoundchemistrySputteringQuantum well intermixing GaInNAsengineeringOptoelectronicsRapid thermal annealingbusinessSaturation (magnetic)Quantum well
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Effects of rapid thermal annealing on the optical properties of low-loss 1.3μm GaInNAs∕GaAs saturable Bragg reflectors

2004

We report studies of the effect of rapid thermal annealing (RTA) on the optical properties of a low-loss 1.3 mum saturable Bragg reflector (SBR), consisting of a GaInNAs/GaAs single quantum well embedded in an AlAs/GaAs Bragg reflector grown monolithically on a GaAs substrate. RTA gives rise to a blueshift of the photoluminescence (PL) peak (and therefore of the excitonic absorption peak) and an enhancement of PL intensity, while the reflectivity properties including peak reflectivity and bandwidth are not degraded. Temperature dependent photoluminescence measurements show that the RTA-induced blueshift of photoluminescence consists of two components: one originating from the increase of op…

:Science::Physics::Optics and light [DRNTU]PhotoluminescenceMaterials scienceCondensed Matter::Otherbusiness.industrychemical beamPhysics::OpticsGeneral Physics and AstronomyNonlinear opticsCondensed Matter::Mesoscopic Systems and Quantum Hall EffectDistributed Bragg reflectorBlueshiftGallium arsenideCondensed Matter::Materials Sciencechemistry.chemical_compoundchemistryOptoelectronicsSemiconducting galliumRapid thermal annealingbusinessSemiconductor quantum wellsRefractive indexQuantum wellJournal of Applied Physics
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Negative thermal expansion in cuprite-type compounds: A combined synchrotron XRPD, EXAFS, and computational study of Cu2O and Ag2O

2006

Cuprite-type oxides (Cu2O and Ag2O) are framework structures composed by two interpenetrated networks of metal-sharing M4O tetrahedra (M = Cu, Ag). Both compounds exhibit a peculiar negative thermal expansion (NTE) behaviour over an extended temperature range (9 240 K for Cu2O, 30-470 K for Ag2O). High-accuracy synchrotron powder diffraction and EXAFS measurements were performed from 10 K up to the decomposition temperature to understand the nature of the NTE effects. The critical comparison of the diffraction and absorption results concerning the temperature dependence of the interatomic distances and of the atomic vibrational parameters proves to be fundamental in defining the local dynam…

ABSORPTION FINE-STRUCTUREPOWDER DIFFRACTIONExtended X-ray absorption fine structureChemistryThermal decompositionCupriteCharge densityGeneral ChemistryAtmospheric temperature rangeCondensed Matter PhysicsThermal expansionCrystallographyChemical bondNegative thermal expansionPhysics::Atomic and Molecular ClustersSCATTERINGRADIATIONGeneral Materials ScienceThermal expansionTEMPERATUREPowder diffractionJournal of Physics and Chemistry of Solids
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Semi-Empirical Calculations of Hole Polarons in MgO and KNbO3 Crystals

1998

The semi-empirical quantum chemical INDO method has been used for cluster and large unit cell calculations of hole polarons bound to a cation vacancy in highly ionic MgO and partly covalent perovskite KNbO 3 . In both cases a hole is well localized on an oxygen atom displaced towards the vacancy. The calculated optical and thermal ionization energies for V - and V 0 centers are in excellent agreement with experimental data for MgO. In KNbO 3 we predict the existence of one-site and two-site (molecular) polarons with close absorption energies (1 e V). The relevant experimental data are discussed.

Ab initio quantum chemistry methodsChemistryVacancy defectBound stateIonic bondingThermal ionizationIonization energyAtomic physicsCondensed Matter PhysicsPolaronElectronic Optical and Magnetic MaterialsPerovskite (structure)physica status solidi (b)
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Modelling temperature-dependent dynamics of single and mixed infections in a plant virus

2022

Multiple viral infection is an important issue in health and agriculture with strong impacts on society and the economy. Several investigations have dealt with the population dynamics of viruses with different dynamic properties, focusing on strain competition during multiple infections and the effects on viruses’ hosts. Recent interest has been on how multiple infections respond to abiotic factors such as temperature (T). This is especially important in the case of plant pathogens, whose dynamics could be affected significantly by global warming. However, few mathematical models incorporate the effect of T on parasite fitness, especially in mixed infections. Here, we investigate simple mat…

Abiotic componenteducation.field_of_studybiologyMathematical modelCo-infection dynamicsApplied Mathematicsmedia_common.quotation_subjectPopulationTranscritical bifurcationsRNA virusAbiotic stressbiology.organism_classificationCompetition (biology)BifurcationsCompetition modelTranscritical bifurcationThermal reaction normsEvolutionary biologyNonlinear dynamicsModeling and SimulationPlant virusDynamical systemseducationmedia_commonApplied Mathematical Modelling
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Endovenous ablation of refluxing saphenous and perforating veins.

2017

Abstract. Since the end of the nineties endovenous thermal ablation and more recently non-thermal, non-tumescent techniques have been developed and improved. Until now, because of their favourable side effect profile in conjunction to sustained efficacy, in many countries they already replaced high ligation and stripping in the treatment of refluxing saphenous veins as well as for treatment of perforators and selected tributaries. Now, studies and comparative trials are available with long-term follow-ups for most of the techniques, providing valid data on occlusion and reflux rates, side effect profiles, and health related quality of life.

Ablation Techniquesmedicine.medical_specialtyTime FactorsSide effectRadiofrequency ablationThermal ablation030204 cardiovascular system & hematologylaw.invention030207 dermatology & venereal diseases03 medical and health sciences0302 clinical medicinePostoperative ComplicationslawRisk FactorsOcclusionMedicineHumansSaphenous VeinHealth related quality of lifebusiness.industryEndovenous ablationComparative trialSurgerySteamTreatment OutcomeVenous InsufficiencyCatheter AblationLaser TherapyPerforating veinsCardiology and Cardiovascular MedicinebusinessVASA. Zeitschrift fur Gefasskrankheiten
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The effects of water absorption and salt fog exposure on agglomerated cork compressive response

2022

The replacement of synthetic foams with agglomerated cork in sandwich composites can meet the increasing environmental concerns. Its peculiar morphology and chemical composition lead to outstanding dimensional recovery that endorsed a broad investigation of its compressive behavior. The knowledge of neat material response is fundamental to obtain a reliable design dataset, but it is necessary to consider all the environmental factors (water, moisture and sunlight) that significantly modify material mechanical properties. In view of this, the present work investigates the effect of distilled and seawater absorption and salt fog exposure on the compressive behavior of two agglomerated corks w…

Absorption of waterMaterials scienceAgglomerated corkMechanical propertiesCorkengineering.materialThermal diffusivitywater absorptionGeneral Materials ScienceComposite materialSandwich structuresChemical compositionSalt fog exposurePolymer compositesMaterialesMoistureForestryagglomerated corkagglomerated cork; water absorption; salt fog exposureCompressive strengthSettore ING-IND/22 - Scienza E Tecnologia Dei MaterialiDistilled waterengineeringsalt fog cork aging compressive responseWater absorptionSeawatersalt fog exposure
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Absorption kinetics and swelling stresses in hydrothermally aged epoxies investigated by photoelastic image analysis

2015

Abstract The present work proposes an experimental optical methodology able to measure the transient swelling stresses induced by the water uptake ageing of polymers. In particular, the work describes the implementation of a Photoelastic technique to quantify internal stresses arising during the hydrothermal ageing of cast epoxy samples. The material investigated is a model DGEBA/DDS epoxy system. Curing and post-curing cycles have been optimised in order to obtain a fully cured, high T g , and completely stress free initial condition. Rectangular beam samples were then left in a hydrothermal bath at 90 °C, and regularly monitored by gravimetric and photoelastic analyses. The quantitative e…

Absorption of waterMaterials sciencePhotoelastic stress analysiPolymers and PlasticsThermosetting polymerSwelling stresseSettore ING-IND/14 - Progettazione Meccanica E Costruzione Di MacchineDesorptionMaterials ChemistrymedicineComposite materialSettore ING-IND/15 - Disegno E Metodi Dell'Ingegneria IndustrialeCuring (chemistry)chemistry.chemical_classificationHydrothermal ageingPolymerEpoxyCondensed Matter PhysicschemistryMechanics of Materialsvisual_artThermosetting resinvisual_art.visual_art_mediumGravimetric analysisSettore CHIM/07 - Fondamenti Chimici Delle TecnologieSwellingmedicine.symptom
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