Search results for "Absorption"

showing 10 items of 2701 documents

Generation of defects in amorphous SiO(2) assisted by two-step absorption on impurity sites.

2011

Generation of the Si dangling bond defect in amorphous SiO(2) (E' centre) induced by tunable pulsed UV laser radiation was investigated by in situ optical absorption measurements. The defect generation efficiency peaks when the photon energy equals ∼5.1 eV, it depends quadratically on laser intensity and is correlated with the native linear absorption due to Ge impurities. We propose a model in which the generation of E' is assisted by a two-step absorption process occurring on Ge impurity sites.

In situAbsorption spectroscopyChemistryDangling bondAnalytical chemistryPhysics::OpticsPhoton energyRadiationCondensed Matter PhysicsMolecular physicsSilica defects two-step absorptionAmorphous solidImpurityGeneral Materials ScienceAbsorption (electromagnetic radiation)Journal of physics. Condensed matter : an Institute of Physics journal
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In situ measurements of molecular iodine in the marine boundary layer: the link to macroalgae and the implications for O<sub>3</…

2010

Abstract. Discrete in situ atmospheric measurements of molecular iodine (I2) were carried out at Mace Head and Mweenish Bay on the west coast of Ireland using diffusion denuders in combination with a gas chromatography-mass spectrometry (GC-MS) method. I2, IO and OIO were also measured by long-path differential optical absorption spectroscopy (LP-DOAS). The simultaneous denuder and LP-DOAS I2 measurements were well correlated (R2=0.80) but the denuder method recorded much higher concentrations. This can be attributed to the fact that the in situ measurements were made near to macroalgal sources of I2 in the intertidal zone, whereas the LP-DOAS technique provides distance-averaged mixing rat…

In situAtmospheric ScienceDaytimebiologyChemistryDifferential optical absorption spectroscopyPhotodissociationAnalytical chemistryIntertidal zonebiology.organism_classificationAlgaeEnvironmental chemistryDiffusion (business)BayAtmospheric Chemistry and Physics
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Correlation BetweenIn Vitro,In Situ, andIn Vivo Models

2008

In situIntestinal permeabilityBiochemistryIn vivoChemistrymedicineBiosimulationmedicine.diseaseIn vitroIntestinal absorptionDrug metabolismCell biology
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In-situ intestinal rat perfusions for human Fabs prediction and BCS permeability class determination: Investigation of the single-pass vs. the Doluis…

2015

Intestinal drug permeability has been recognized as a critical determinant of the fraction dose absorbed, with direct influence on bioavailability, bioequivalence and biowaiver. The purpose of this research was to compare intestinal permeability values obtained by two different intestinal rat perfusion methods: the single-pass intestinal perfusion (SPIP) model and the Doluisio (closed-loop) rat perfusion method. A list of 15 model drugs with different permeability characteristics (low, moderate, and high, as well as passively and actively absorbed) was constructed. We assessed the rat intestinal permeability of these 15 model drugs in both SPIP and the Doluisio methods, and evaluated the co…

In situMaleSingle passIntestinal permeabilitybusiness.industryPharmaceutical ScienceBioequivalencePharmacologymedicine.diseaseBiopharmaceutics Classification SystemModels BiologicalPermeabilityBioavailabilityRatsPerfusionPermeability (earth sciences)Intestinal AbsorptionPharmaceutical PreparationsmedicineAnimalsHumansIntestinal MucosaRats WistarbusinessPerfusionInternational journal of pharmaceutics
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A new cell for the study of in situ chemical reactions using X-ray absorption spectroscopy

2005

An in situ cell for reductive and oxidative treatments at different temperatures that allows the possibility of recording data as a function of temperature has been designed and constructed for X-ray absorption experiments at the GILDA beamline BM08 of ESRF. The cell is linked to a mass quadrupole spectrometer providing control of the reaction gases and monitoring of the products. The apparatus allows measurements to be performed both in transmission and fluorescence geometry. The cell was tested by studying the CO oxidation reaction promoted by a Pt/ceria-zirconia-supported catalyst. The CO(2) yield is correlated with the structural results confirming the existence of a strong metal-suppor…

In situNuclear and High Energy PhysicsAnalytical chemistryChemical reactionRedoxCatalysisSpecimen HandlingCatalysisthree-way catalystX-Ray DiffractionAbsorption (electromagnetic radiation)InstrumentationPlatinumX-ray absorption spectroscopyRadiationSpectrometerChemistryTemperatureSpectrometry X-Ray EmissionCarbon Dioxidein situ EXAFSOxygenYield (chemistry)Flow Injection AnalysisZirconiumOxidation-Reductionstrong metal support interaction
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Molte Palermo. Temi

2019

Nel tema delle incompiute idee di città possibili si riconoscerà il paradigma connotativo dello stesso divenire di Palermo, lungo un percorso millenario di processi di trasformazione nessuno dei quali portato a compimento, in virtù di quel valore distintivo di exemplum che non necessita di ulteriori e conclusive dimostrazioni. Il corso della storia, del resto, ha imposto a Palermo il ciclico riproporsi di destini interrotti. Tale si rilevò l’invenzione della città capitale, quella della “quadratura geometrica e della croce di strade” sovrimpressa a quella archetipica e fondativa della Pan-ormos scambiatrice. E l’incompiutezza sarà il tratto distintivo della città dei rettifili stradali otto…

In the theme of unfinished ideas of possible cities will recognize the connotative paradigm of the evolution of Palermo will be recognised along a thousand year path of transformational processes none of which was completed by virtue of the distinctive value of exemplum that does not require additional and conclusive demonstrations. The course of history has moreover imposed on Palermo a cyclical recurrence of broken destinies. This was evidence of the invention of the capital city that of the “geometric square and the cross roads” superimposed on the archetypal underpinning of Pan-ormos as a place of exchange. And incompleteness will be the hallmark of the city of the nineteenth century straight roads heading towards undefined destinations the symptomatic expression of the idea of a preordained effect of suspension. Similarly unfinished will be the Palermo of the redevelopment plans in the nineteenth and twentieth centuries upto the shapeless development of the contemporary city and the new arterial routes (the Circonvallazione) manifestations of further “Palermo as abstraction” ever more distant from “Palermo as places”. A city ultimately characterized by continuous metamorphoses replacement of values absorptions oblivion and cultural desecration. From this distance one can indeed observe Palermo from a marginal and peripherical point of view as regards its urban limits opening up a different prospect penetrating and maybe even superior able to understand facts and phenomena in depth.Settore ICAR/14 - Composizione Architettonica E Urbana
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Integrazione di celle solari di terza generazione nel vetromattone per la realizzazione di pannelli traslucidi fotovoltaici. Analisi prestazione e st…

2013

L’articolo illustra i primi risultati ottenuti nell’ambito dell’analisi prestazionale del vetromattone fotovoltaico, un prodotto edilizio innovativo derivato dall’integrazione di celle fotovoltaiche di terza generazione (DSSC) nel vetromattone, ideato per la realizzazione di involucri traslucidi energeticamente effi cienti ed “attivi”, in grado di ridurre i consumi energetici degli edifi ci e di produrre, al contempo, energia verde. L’analisi è stata condotta su quattro differenti ipotesi di integrazione. Attraverso simulazioni numeriche si è effettuata una valutazione dell’energia assorbita dagli strati attivi oltre che delle prestazioni ottiche complessive del dispositivo. Lo studio anali…

In this article the fi rst results of the performance analysis of the photovoltaic glassblock are given. The photovoltaic glassblock is an innovative product which integrates third generation solar cells (DSSC) invented for the construction of translucent building envelopes energetically effi cient and “active” able to reduce the energy consumption in buildings and to produce at the same time green energy. The analysis was conducted on four different hypotheses of integration through numerical simulations in order to evaluate the energy absorption and the optical performance of the device. The software simulations represent a fi rst step for the understanding of the performance of the element and prelude to an experimental analysis session. The results of a research conducted about national and international patents publications on the DSSC technology and its applications will be illustrated too. The data collected during this research had been organized in a digital database.Settore ICAR/10 - Architettura Tecnica
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A theoretical study of the emission spectra of indole and its analogs: indene, benzimidazole, and 7-azaindole

2000

Abstract The complete active space (CAS) SCF method and multiconfigurational second-order perturbation theory (CASPT2) have been used to study the electronic spectra of indole, indene, benzimidazole, and 7-azaindole. The paper is focused on the study of the low-lying valence triplet and singlet electronic states at the optimized geometries of the excited states. The geometries have been optimized by using analytic CASSCF derivatives. CASPT2 point calculations have been performed in order to obtain band origins and relaxed emission energies. The results are analyzed in the context of the complex emission processes, both fluorescence and phosphorescence, displayed by the title compounds, whic…

Indole testchemistry.chemical_compoundValence (chemistry)Absorption spectroscopychemistryComputational chemistryExcited stateGeneral Physics and AstronomyComplete active spaceSinglet statePhysical and Theoretical ChemistryIndenePhosphorescenceChemical Physics
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A two-component model for the 2260cm−1 infrared absorption band in electron irradiated amorphous SiO2

2011

Abstract We report an experimental study by infrared absorption (IR) measurements focused on the effects of electron irradiation in the dose range from 1.2 × 10 3  kGy to 5 × 10 6  kGy on the intrinsic band peaked at 2260 cm − 1 in amorphous silicon dioxide (a-SiO 2 ) materials. This IR band is particularly relevant as it is assigned to an overtone of the strong asymmetric stretching vibration of Si–O–Si bridges and consequently it is intimately related to the Si–O–Si bond angle distribution. In a recent work we have shown that structural modifications induced by irradiation take place through the nucleation of confined high-defective and densified regions statistically dispersed into the w…

Infrared absorptionAbsorption spectroscopyChemistrybusiness.industrySettore FIS/01 - Fisica SperimentaleAnalytical chemistryNucleationElectron irradiationInfrared spectroscopySilicaCondensed Matter PhysicsElectronic Optical and Magnetic MaterialsAmorphous solidMolecular geometryOpticsMolecular vibrationDensificationMaterials ChemistryCeramics and CompositesElectron beam processingAmorphous silicon dioxideIrradiationbusinessJournal of Non-Crystalline Solids
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High-Resolution Spectroscopy and Preliminary Global Analysis of C–H Stretching Vibrations of C2H4 in the 3000 and 6000 cm-1 Regions

2010

International audience; Ethylene (ethene, H2C=CH2) is a naturally occurring compound in ambient air that affects atmospheric chemistry and global climate. The C2H4 spectrum is available in databases only for the 1000 and 3000 cm−1 ranges. In this work, the ethylene absorption spectrum was measured in the 6030- 6250 cm−1 range with the use of a high resolution Bruker IFS 125HR Fourierspectrometer and a two-channel opto-acoustic spectrometer with a diode laser. As a secondary standard of wavelengths, the methane absorption spectrum was used in both cases. A preliminary analysis was realized thanks to the tensorial formalism developed by the Dijon group that is implemented in the XTDS software…

Infrared absorption[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry[CHIM.THEO] Chemical Sciences/Theoretical and/or physical chemistryEthyleneDiode laser spectroscopy[ CHIM.THEO ] Chemical Sciences/Theoretical and/or physical chemistryFourier transform spectroscopyEarth and planetary atmospheres
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